WO2024258063A1 - Method for manufacturing biodegradable filter material, biodegradable filter material, air purification filter comprising same, and home appliance - Google Patents

Abstract

Provided are a method for manufacturing a biodegradable filter material, a biodegradable filter material, an air purification filter comprising same, and a home appliance, the method comprising the steps of: preparing a biodegradable resin blend by blending a biodegradable resin composition; preparing a melted biodegradable resin blend by increasing the temperature of the biodegradable resin blend; and preparing a biodegradable fiber member by spinning the melted biodegradable resin blend, wherein the biodegradable resin composition comprises a biodegradable resin and an additive, the additive includes a viscosity modifier, a charging agent or a combination thereof, and the melt flow rate (MFR) of the melted biodegradable resin blend, measured at 230°C according to ASTM D1238, is greater than 120 g/10 min and less than or equal to 550 g/10 min.

Description

Method for manufacturing biodegradable filter material, biodegradable filter material, air purifying filter and home appliance containing the same

The present invention relates to a method for manufacturing a biodegradable filter medium, a biodegradable filter medium, an air purifying filter including the same, and a home appliance.

As the amount of plastic waste increases, the treatment of plastic waste is becoming more important. Incineration of plastic waste causes air pollution by dust and harmful gases and global warming by releasing large amounts of carbon dioxide. Landfilling of plastic waste causes environmental pollution such as a shortage of landfill sites and non-decomposition of plastic waste. The need for recycling of plastics is increasing. For example, the use of recyclable polymers such as biodegradable polymers is being considered.

Plastics manufactured in the form of nonwoven fabrics are mainly used for consumables such as masks, filters, wet tissues, diapers, and dust bags. Nonwoven fabrics usually contain composite materials to satisfy the required process properties, mechanical properties, etc. Composite materials include, for example, non-biodegradable petroleum-based plastics in addition to biodegradable polymers. Therefore, they are classified as general waste rather than recyclable waste, making them difficult to recycle.

A recyclable, non-woven plastic material is required.

An air purifying filter is used to remove fine dust. An air purifying filter includes a filter medium, such as a melt-blown filter medium, to provide dust collection performance. A melt-blown filter medium requires a more sophisticated manufacturing process than a filter medium manufactured by other methods. The melt-blown process is a process of manufacturing a fiber by supplying high-temperature air while extruding a molten resin through a fine hole of a nozzle. The molten resin is required to withstand high temperatures while also having excellent flow performance. Since the molten resin has excellent flow performance, the diameter of the fibers radiated by air at high temperatures can be reduced, and the mechanical properties of the melt-blown filter medium can be easily controlled. If the molten resin is thermally deformed at high temperatures, the radiating of the molten resin becomes impossible.

Meltblown media is generally manufactured using petroleum-based polymers having excellent melt flowability and thermal stability. Meltblown media can be manufactured by controlling the melt flowability of the molten petroleum-based resin to 1,000 g/10 min or more. Such petroleum-based polymers include, for example, polyethylene, polypropylene, and polystyrene. However, such petroleum-based polymers have a disadvantage in that they are not biodegradable.

Biodegradable resins have low thermal stability and melt flowability compared to, for example, petroleum-based resins, making them difficult to apply to the meltblown process. Nonwoven fabrics manufactured using biodegradable resins are used for, for example, wet tissues and masks, but their use is limited in applications requiring additional properties such as filtration efficiency, such as air purifiers. Therefore, a method for manufacturing a filter medium and a filter medium that are manufactured using biodegradable resins but provide improved properties are required.

One aspect is to provide a method for preparing a novel biodegradable filter media which provides improved filtration efficiency and biodegradability.

Another aspect is to provide a novel biodegradable filter medium having improved filtration efficiency and biodegradability.

Another aspect is to provide an air purifying filter comprising the biodegradable filter medium.

Another aspect is to provide a home appliance comprising the air purifying filter.

On one side,

A step of preparing a biodegradable resin blend by blending a biodegradable resin composition;

A step of preparing a molten biodegradable resin blend by heating the biodegradable resin blend; and

A step of preparing a biodegradable fiber member by spinning the above-mentioned molten biodegradable resin blend,

The above biodegradable resin composition comprises a biodegradable resin and an additive, wherein the additive comprises a viscosity modifier, a charging agent or a combination thereof,

A method for manufacturing a biodegradable filter material is provided, wherein the melt flow rate (MFR) of the above-mentioned melted biodegradable resin blend measured at 230° C. according to ASTM D1238 is greater than 120 g/10 min to 550 g/10 min.

On the other hand,

Contains biodegradable fibers,

The above biodegradable fiber member comprises a biodegradable resin and an additive,

A biodegradable filter medium is provided, wherein the additive comprises a viscosity modifier, a charging agent, or a combination thereof.

On the other hand,

An air purifying filter comprising a biodegradable filter medium according to the above is provided.

On the other hand,

Home appliances including air purifying filters are provided.

According to one aspect, a biodegradable filter medium having improved properties can be manufactured by controlling the melt flowability of a molten biodegradable resin blend.

The filtration efficiency and biodegradability of the biodegradable filter medium manufactured by this method can be improved.

Figure 1 is a flow chart of a method for manufacturing a biodegradable filter medium according to an exemplary embodiment.

Figure 2 is a visual image of the biodegradable filter medium manufactured in Example 3.

Figure 3 is a schematic cross-sectional view of a filter having a biodegradable filter medium according to an exemplary embodiment.

FIG. 4 is a schematic cross-sectional view of a filter having a biodegradable filter medium according to another exemplary embodiment.

FIG. 5 is a schematic cross-sectional view of a filter having a biodegradable filter medium according to another exemplary embodiment.

The present disclosure described below can have various transformations and various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present disclosure to specific embodiments, but should be understood to include all transformations, equivalents, or substitutes included in the technical scope of the present disclosure.

The terms used below are used only to describe specific embodiments and are not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. Hereinafter, the terms "comprises" or "contains" or "has" and the like are intended to indicate the presence of a feature, number, step, operation, component, part, ingredient, material or a combination thereof described in the specification, but should be understood to not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, ingredients, materials or combinations thereof. That is, the terms "comprises" or "contains" in the present disclosure mean including the target component or component without limitation of a specific aspect, and do not exclude the addition of additional components or components other than the target component or component. The "/" used below may be interpreted as "and" or "or" depending on the context.

In order to clearly express various layers and regions in the drawings, the thickness is shown enlarged or reduced. Similar parts are designated by the same drawing reference numerals throughout the specification. When a part such as a layer, film, region, or plate is referred to as being “on” or “over” another part throughout the specification, this includes not only the case where it is directly above the other part, but also the case where there is another part in between. The terms first, second, etc. may be used throughout the specification to describe various components, but the components should not be limited by the terms. The terms are used only to distinguish one component from another. In the present specification and the drawings, components having substantially the same functional configuration are referred to by the same reference numerals, and redundant descriptions are omitted.

In the present disclosure, "polylactic acid" means any polymer containing a repeating unit formed by ring-opening polymerization of a lactide monomer. The polymer includes a homopolymer or a copolymer, and is not limited to a specific embodiment in which the polymer exists. For example, the polymer includes various embodiments, such as an unrefined or refined polymer after ring-opening polymerization is completed, a polymer included in a liquid or solid resin composition before product molding, or a polymer included in a plastic, film, or fabric after product molding is completed.

In the present disclosure, “lactide” includes L-lactide composed of L-lactic acid, D-lactide composed of D-lactic acid, and meso-lactide composed of L-lactic acid and D-lactic acid.

In the present disclosure, “poly-L-lactic acid (PLLA)” means a polymer comprising repeating units formed by ring-opening polymerization or direct polymerization of an L-lactide monomer.

In the present disclosure, “poly-D-lactic acid (PDLA)” means a polymer comprising repeating units formed by ring-opening polymerization or direct polymerization of a D-lactide monomer.

In the present disclosure, “polybutylene succinate (PBS)” means a polymer comprising repeating units formed by sequential polymerization of 1,4-butanediol and succinic acid.

In the present disclosure, “polycaprolactone (PCL)” means a polymer comprising repeating units formed by ring-opening polymerization of ε-caprolactone.

In this disclosure, “petroleum-based resin” means a resin or polymer manufactured using raw materials obtained from petroleum.

In this disclosure, “biodegradable resin” means a resin or polymer that is decomposed into water, carbon dioxide, etc. by microorganisms, etc.

In this disclosure, “non-biodegradable resin” means a resin or polymer that takes more than 100 years to decompose and is substantially non-degradable.

In the present disclosure, a “thermoplastic resin” is a resin whose flexibility increases as temperature increases.

In the present disclosure, the “weight average molecular weight” of the polymer is measured using gel permeation chromatography (GPC) and is a relative value to a polystyrene standard sample.

Hereinafter, a method for manufacturing a biodegradable filter according to exemplary embodiments, a biodegradable filter, an air purifying filter including the same, and a home appliance are described in more detail.

A method for manufacturing a biodegradable filter medium according to one embodiment comprises the steps of: blending a biodegradable resin composition to prepare a biodegradable resin blend; heating the biodegradable resin blend to prepare a molten biodegradable resin blend; and spinning the molten biodegradable resin blend to prepare a biodegradable fiber member, wherein the biodegradable resin composition comprises a biodegradable resin and an additive, wherein the additive comprises a viscosity modifier, a charging agent, or a combination thereof, and wherein a melt flow rate (MFR) of the molten biodegradable resin blend measured at 230° C. according to ASTM D1238 is more than 120 g/10 min to 550 g/10 min. The melt flow rate (MFR) of the molten biodegradable resin blend as measured at 230° C. according to ASTM D1238 can be, for example, 121 g/10 min to 550 g/10 min, 150 g/10 min to 550 g/10 min, 200 g/10 min to 550 g/10 min, 250 g/10 min to 550 g/10 min or 300 g/10 min to 500 g/10 min.

A biodegradable filter medium providing both improved filtration efficiency and biodegradability can be effectively manufactured when the melt flow rate (MFR) of the molten biodegradable resin blend is in the range of more than 120 g/10 min to 550 g/10 min as measured at 230° C. according to ASTM D1238. If the melt flow rate is too low, the relative filtration efficiency of the biodegradable filter medium may be reduced due to an increase in the diameter of biodegradable fibers manufactured in the spinning process. If the melt flow rate is too high, the thermal stability of the biodegradable resin may be reduced, which may cause thermal decomposition of the biodegradable resin. The possibility of occurrence of defects in the spinning process from the molten biodegradable resin blend including the thermally decomposed biodegradable resin increases.

Referring to Fig. 1, a method for manufacturing a biodegradable filter material according to one embodiment is described.

First, a biodegradable resin blend is prepared by blending a biodegradable resin composition.

A biodegradable resin composition includes a biodegradable resin and an additive. The additive includes a viscosity modifier, a charging agent, or a combination thereof. The biodegradable resin composition includes a biodegradable resin. By including the biodegradable resin in the biodegradable resin composition, biodegradability of the biodegradable filter medium is improved. The biodegradable resin includes, for example, polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PBH), cellulose, or a combination of two or more thereof. The biodegradable resin may be, in particular, polylactic acid.

The polylactic acid can be, for example, poly-L-lactic acid manufactured from L-lactide or L-lactic acid. The polylactic acid can be, for example, poly-D-lactic acid manufactured from D-lactide or D-lactic acid. The polylactic acid can be, for example, a mixture of poly-L-lactic acid and poly-D-lactic acid. A stronger bond can be obtained between them due to the opposite stereostructures thereof.

Polylactic acid is an aliphatic polyester containing repeating units of the following chemical formula 1, for example.

<Chemical Formula 1>

In the above chemical formula 1, n is a number greater than or equal to 2. The acidity of the polylactic acid can be, for example, 50 meq/kg or less. The acidity of the polylactic acid is not limited to this range, but can provide further improved properties within this acidity range. For example, the acidity of the polylactic acid can be 1 to 50 meq/Kg, 1 to 30 meq/Kg, 1 to 10 meq/Kg, or 2 to 5 meq/Kg. The acidity of the polylactic acid can be measured, for example, according to ASTM D664.

The optical purity of the polylactic acid can be, for example, 90% or higher. The optical purity of the polylactic acid can be, for example, 93% or higher, 95% or higher, or 97% or higher. If the optical purity of the polylactic acid is lower than 90%, the mechanical properties of the biodegradable resin composition may deteriorate. The glass transition temperature (Tg) of the polylactic acid can be, for example, 50° C. or higher. The glass transition temperature of poly-L-lactic acid (PLLA) is, for example, 55 to 68° C. or 60 to 68° C. The glass transition temperature (Tg) of the polylactic acid can be measured using, for example, a Differential Scanning Calorimeter (DSC), a Dynamic Mechanical Analyzer (DMA), a Thermomechanical Analyzer (TMA), and/or a Thermogravimetric Analyzer (TGA).

Polybutylene succinate (PBS) is an aliphatic polyester containing repeating units of the following chemical formula 2, for example. In the following chemical formula 2, n is a number greater than or equal to 2.

<Chemical Formula 2>

Polycaprolactone (PCL) is an aliphatic polyester containing repeating units of the following chemical formula 3, for example. In the following chemical formula 3, n is a number of 2 or greater.

<Chemical Formula 3>

Biodegradable resins are, for example, biodegradable polymers. Biodegradable polymers are, for example, thermoplastic polymers.

The weight average molecular weight of the biodegradable polymer can be, for example, 10,000 to 500,000 Dalton, 100,000 to 300,000 Dalton, or 10,000 to 500,000 Dalton. The weight average molecular weight of the polylactic acid can be, for example, 10,000 to 500,000 Dalton, 100,000 to 300,000 Dalton, or 10,000 to 500,000 Dalton. If the weight average molecular weight of the biodegradable polymer is less than 10,000 Dalton, the heat resistance of the biodegradable resin composition may be excessively reduced. If the weight average molecular weight of the biodegradable polymer is more than 500,000, melting may be difficult. The weight average molecular weight can be measured using GPC (Gel Permeation Chromatography) for a polystyrene standard sample.

The biodegradable resin composition may include, for example, polylactic acid. The biodegradable resin composition may be free of, for example, a petroleum-based non-biodegradable resin. The biodegradable resin composition may not include a petroleum-based non-biodegradable resin. A petroleum-based resin is a resin or polymer obtained from petroleum. The petroleum-based non-biodegradable resin may be, for example, an olefin-based resin. The petroleum-based non-biodegradable resin may be, for example, polyethylene, polypropylene, polystyrene, etc., but is not limited thereto, and includes any petroleum-based resin that is not biodegradable and is used in the relevant technical field. Generally, a biodegradable resin and a petroleum-based non-biodegradable resin are mixed and used to enhance the properties of a biodegradable resin. In contrast, a biodegradable filter medium manufactured using the biodegradable resin composition of the present disclosure can provide excellent filtration efficiency and mechanical properties even though it includes only a biodegradable resin without including a petroleum-based non-biodegradable resin.

The biodegradable resin composition comprises polylactic acid, and the polylactic acid content can be, for example, 95 wt% or more, 97 wt% or more, 98 wt% or more, or 99 wt% or more of the total weight of the biodegradable resin composition. The polylactic acid content can be, for example, 95 wt% to 99.9 wt%, 97 wt% to 999 wt%, 98 wt% to 99.9 wt%, or 99 wt% to 99.9 wt% of the total weight of the biodegradable resin composition.

The biodegradable resin composition may include a viscosity modifier as an additive. The viscosity modifier may include, for example, an organic peroxide-based viscosity modifier, a vinyl-based viscosity modifier, an acrylic-based viscosity modifier, or a combination thereof.

Since the biodegradable resin composition includes a viscosity modifier, the diameter of a biodegradable fiber manufactured from the biodegradable resin composition can be more easily controlled.

Organic peroxide viscosity modifiers include, for example, 2.5-dimethyl-2,5-di(tert-butylperoxy)hexane, ditert-butyl peroxide, ditert-amyl peroxide, tert-butyl cumyl peroxide, di(tert-butylperoxy-isopropyl)-benzene, dicumyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, 3,3,5,7,7-pentamethyl-1,2,4-trioxepane or a combination thereof. The organic peroxide viscosity modifier may be, for example, a reactive viscosity modifier that reacts with the biodegradable resin. The organic peroxide viscosity modifier may react with the biodegradable resin to cleave chains of the biodegradable resin, thereby improving the fluidity of the biodegradable resin composition. The reaction of the organic peroxide viscosity modifier with the biodegradable resin may be, for example, a radical reaction. The radical reaction may be, for example, a chain radical reaction. Therefore, by improving the fluidity of the biodegradable resin composition, the production of a biodegradable resin blend from the biodegradable resin composition and/or the spinning of biodegradable fibers from the biodegradable resin blend may be more easily performed.

The vinyl-based viscosity modifier can include, for example, poly(vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate), fluoroethylene vinyl ether, 2-butenedioic acid (2Z)-, 1-(1-methylethyl) ester, N,N'-bis(2,2,6,6,-tetramethylpiperidin-4-yl)-1,3-dicarboxamide, or a combination thereof. The vinyl-based viscosity modifier can adjust the viscosity of the biodegradable resin composition by blending it with the biodegradable resin.

The acrylic viscosity modifier may include methyl methacrylate, butyl methacrylate, butyl methacrylate, butyl methacrylate, or a combination thereof. The acrylic viscosity modifier can control the viscosity of the biodegradable resin composition by blending with the biodegradable resin.

The content of the viscosity modifier included in the biodegradable resin composition may be from more than 0 to 5 wt%, from more than 0.5 wt% to 4 wt%, from 0.6 wt% to 3 wt%, or from 0.6 wt% to less than 2 wt% of the total weight of the biodegradable resin composition. If the content of the viscosity modifier increases excessively, the fluidity of the biodegradable resin composition may increase excessively, thereby reducing the thermal stability of the biodegradable resin composition. Accordingly, thermal decomposition of the molten biodegradable resin blend obtained from the biodegradable resin composition may occur. As a result, it may be difficult to easily perform spinning of biodegradable fibers from the molten biodegradable resin blend.

The biodegradable resin composition may contain a precipitant as an additive.

The charging agent may include, for example, a metal oxide charging agent, an imide charging agent, or a combination thereof.

Since the biodegradable resin composition includes a charge, a biodegradable filter medium manufactured from the biodegradable resin composition can be more easily charged. The charged biodegradable filter medium can have, for example, a positive charge placed on the surface of the biodegradable filter medium. Accordingly, particles having a negative charge can be more easily adsorbed on the surface of the charged biodegradable filter medium. As a result, the filtration efficiency of the biodegradable filter medium can be further improved.

The metal oxide cathode may include, but is not limited to, TiO ₂ , SiO ₂ , ZnO, SnO ₂ or a combination thereof, and any metal oxide used as a cathode in the art may be used.

The imide-based major premise includes, but is not limited to, any imide-based compound used as a major premise in the art, including, but not limited to, Poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-s-triazine-2,4-diyl]-[(2,2,6,6-tetramethyl-4-piperidyl)imino]-hexamethylene-[(2,2,6,6-tetramethyl-4-piperidyl)imino], 4-Nitro-N-phenylphthalimide, 1,4-Phenylene-bis-maleimide, 4,4'-Bismaleimidodiphenylmethane, or combinations thereof.

The content of the charging agent included in the biodegradable resin composition may be 0 to 5 wt%, 0.5 wt% to 5 wt%, 0.5 wt% to 4 wt%, or 0.5 wt% to 3 wt% of the total weight of the biodegradable resin composition. If the content of the charging agent is too high, the increase in the charging effect obtained compared to the amount of charging agent added may be minimal. If the content of the charging agent is too low, the charging effect may be minimal.

The biodegradable resin composition can contain, for example, more than 0.5 to less than 2 parts by weight, 0.6 to 1.9 parts by weight, or 0.6 to 1.8 parts by weight of the organic peroxide viscosity modifier with respect to 100 parts by weight of the biodegradable resin. The biodegradable resin composition can contain, for example, more than 0.5 to less than 2 wt%, 0.6 to 1.9 wt%, or 0.6 to 1.8 wt% of the organic peroxide viscosity modifier with respect to the total weight of the biodegradable resin composition. When the biodegradable resin composition contains the organic peroxide viscosity modifier in such an amount, the biodegradability of a biodegradable filter obtained from the biodegradable resin composition can be further improved.

The biodegradable resin composition may contain, for example, 0 to 5 parts by weight, 0.5 to 4 parts by weight, or 0.5 to 3 parts by weight of the metal oxide charging agent based on 100 parts by weight of the biodegradable resin. The biodegradable resin composition may contain, for example, 0 to 5 wt%, 0.5 to 4 wt%, or 0.5 to 3 wt% of the metal oxide charging agent based on the total weight of the biodegradable resin composition. When the biodegradable resin composition contains the charging agent in this content range, the filtration efficiency of the biodegradable filter medium can be further improved.

The biodegradable resin composition may contain, for example, 0.5 to 2 wt% of the organic peroxide viscosity modifier and 0 to 5 wt% of the metal oxide charging agent based on 100 wt% of the biodegradable resin. The biodegradable resin composition may contain, for example, 0.5 to 2 wt% of the organic peroxide viscosity modifier and 0 to 5 wt% of the metal oxide charging agent based on the total weight of the biodegradable resin composition. When the biodegradable resin composition simultaneously contains the organic peroxide viscosity modifier and the metal oxide charging agent in such content ranges, the filtration efficiency and biodegradability of the biodegradable filter medium can be further improved.

In the biodegradable resin composition, for example, the solvent may be absent (free). The solvent may be, for example, an aqueous solvent such as water, alcohol, and/or an organic solvent such as hexane. The biodegradable resin composition may be maintained in a liquid state by increasing the temperature of the biodegradable resin without a separate solvent. There may be no intentional addition of a solvent during the manufacturing process of the biodegradable resin composition. That is, the biodegradable resin composition may be manufactured by a dry method.

The additives may further include, for example, a heat stabilizer, a hydrophilicity regulator, an ultraviolet stabilizer, a flame retardant, an inorganic filler, an organic filler, a softener, a plasticizer, a pigment, an antistatic agent, a terminal blocker, a metal deactivator, an antioxidant, a heat stabilizer, a lubricant, a tackifier, a plasticizer, a crosslinking agent, a fragrance, an antibacterial agent, a dispersant, a polymerization inhibitor, a flame retardant, an antioxidant, a light stabilizer, a processing aid, a fluorinated anti-dripping agent, an antifriction agent, an antiwear agent, a colorant, a release agent, or a combination thereof. The additives are not limited to these, and any additives that can improve the properties of the biodegradable filter medium in the art may be used. The content of the additive may be, for example, 0 to 10 wt%, 0 to 7 wt%, 0 to 5 wt%, 0 to 3 wt% or 0 to 1 wt% of the total weight of the biodegradable resin composition.

The biodegradable resin composition may include, for example, an inorganic filler. The inorganic filler acts as a support or filler that supports the shape of the biodegradable filter medium against external impact, for example as a hard core, thereby improving the impact resistance and/or heat resistance of the biodegradable filter medium including the inorganic filler. The content of the inorganic filler may be, for example, 0 to 5 wt%, 0 to 3 wt%, or 0 to 1 wt% of the total weight of the biodegradable resin composition. If the content of the inorganic filler is too low, the effect obtained by the inorganic filler may be minimal. If the content of the inorganic filler is too high, agglomeration of the inorganic filler may occur and it may be difficult to obtain uniform dispersion of the inorganic filler. The inorganic filler may have a form such as a fiber, a plate, or a particle. The aspect ratio of the platelet or fibrous inorganic filler may be, for example, 5 to 100, 5 to 50, 5 to 30, 5 to 20 or 5 to 10. When the inorganic filler has a fibrous form in this range, the bonding of the biodegradable resin and the inorganic filler can be more effectively achieved. The heat resistance and/or impact resistance of the biodegradable filter medium containing such inorganic filler can be further improved. The inorganic filler can be, for example, talc, glass wool, glass fiber, mica, alumina, wollastonite, clay, mica, kaolinite, montmorillonite, zeolite, graphite, carbon nanotubes, carbon black, zinc oxide, magnesium oxide, titanium oxide, calcium sulfide, boron nitride, calcium carbonate, barium sulfate, aluminum oxide, neodymium oxide, mineral whiskers, basalt fibers, wallstonite, or a combination of two or more thereof. The inorganic filler can include, for example, talc, glass wool, mica, and the like. The inorganic filler can be, for example, a non-carbonaceous filler. The average particle diameter of the inorganic filler can be 1 ㎛ to 100 ㎛, 1 ㎛ to 50 ㎛, 1 ㎛ to 30 ㎛, or 1 ㎛ to 10 ㎛. The average particle diameter is, for example, a value of the median particle diameter (D50) when 50% is accumulated from the small particle side in volume conversion, as measured using a laser scattering particle size distribution meter (e.g., Horiba LA-920). Alternatively, the average particle diameter is an arithmetic mean value of particle diameters of the inorganic filler obtained from a scanning electron microscope (SEM) image of a biodegradable filter medium including the inorganic filler, calculated manually or by software. The particle diameter of the inorganic filler is, for example, an average value of the maximum and minimum distances between longitudinal ends.

The biodegradable resin composition may include, for example, an organic filler. Organic fillers include, for example, sodium benzoate, potassium benzoate, lithium benzoate, calcium benzoate, magnesium benzoate, barium benzoate, lithium terephthalate, sodium terephthalate, potassium terephthalate, calcium oxalate, sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosate, calcium octacosate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, zinc salicylate, aluminum dibenzoate, potassium dibenzoate, lithium dibenzoate, sodium β-naphthalate, sodium cyclohexanecarboxylate, and the like. Carboxylic acid metal salts, organic sulfonates such as sodium p-toluenesulfonate and sodium sulfoisophthalate, carboxylic acid amides such as stearic acid amide, ethylenebislauric acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide and trimesic acid tris(t-phthalamide), low-density polyethylene, high-density polyethylene, polypropylene, polyisopropylene, polybutene, poly-4-methylpentene, poly-3-methylbutene-1, polyvinylcycloalkane, polyvinyltrialkylsilane, sodium salts of ethylene-acrylic acid or methacrylic acid copolymers, sodium salts of styrene-maleic anhydride copolymers, sodium salts or potassium salts of polymers having carboxyl groups (so-called ionomers), benzylidene sorbitol and its derivatives, phosphoric acid such as trade names NA-11 and NA-71 manufactured by ADEKA Ester metal salts, and 2,2-methylbis(4,6-di-t-butylphenyl)sodium, etc. can be mentioned. For example, ethylenebislauric acid amide, benzylidene sorbitol and its derivatives, organic carboxylic acid metal salts, carboxylic acid amides, phosphoric acid ester metal salts such as NA-11 and NA-71 manufactured by ADEKA can be used. The organic filler can be used, for example, as one type alone or as a mixture of two or more types. When the biodegradable resin composition includes an organic filler, the impact resistance and/or heat resistance of the biodegradable filter medium can be additionally improved. The content of the organic filler included in the biodegradable resin composition can be 0 to 5 wt%, 0 to 3 wt%, or 0 to 1 wt% of the total weight of the biodegradable resin composition.

The biodegradable resin composition may include, for example, a terminal blocker. The terminal blocker may include a carbodiimide compound such as a polycarbodiimide compound or a monocarbodiimide compound. When the compound reacts with some or all of the terminal carboxyl groups of polylactic acid, side reactions such as hydrolysis are blocked, so that the water resistance of a molded article including the biodegradable resin composition may be improved. Accordingly, the durability of a molded article including the biodegradable resin composition under a high temperature and high humidity environment may be improved. The polycarbodiimide compound may be, for example, poly(4,4'-diphenylmethanecarbodiimide), poly(4,4'-dicyclohexylmethane carbodiimide), poly(1,3,5-triisopropylbenzene) polycarbodiimide, poly(1,3,5-triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide, or the like. The above monocarbodiimide compound may be, for example, N,N'-di-2,6-diisopropylphenylcarbodiimide, etc. The content of the terminal blocker included in the biodegradable resin composition may be 0 to 5 wt%, 0 to 3 wt%, or 0 to 1 wt% of the total weight of the biodegradable resin.

The biodegradable resin composition may contain a stabilizer or a colorant to stabilize the molecular weight or color at the time of molding. As the stabilizer, a phosphorus stabilizer, a hindered phenol stabilizer, an ultraviolet absorber, a heat stabilizer, an antistatic agent, etc. can be used. As the phosphorus stabilizer, phosphorous acid, phosphoric acid, phosphonic acid and their esters (phosphite compounds, phosphate compounds, phosphonite compounds, phosphonate compounds, etc.) and tertiary phosphines can be used. As a stabilizer containing a phosphonite compound as a main component, Sandostab P-EPQ (Clariant), Irgafos P-EPQ (CIBA SPECIALTY CHEMICALS), etc. can be used. As stabilizers containing phosphite compounds as their main components, PEP-8 (Asahi Densha Kogyo), JPP681S (Tohoku Chemical Industry), PEP-24G (Asahi Densha Kogyo), Alkanox P-24 (Great Lakes), Ultranox P626 (GE Specialty Chemicals), Doverphos S-9432 (Dover Chemical), Irgaofos126, 126 FF (CIBA SPECIALTY CHEMICALS), PEP-36 (Asahi Densha Kogyo), PEP-45 (Asahi Densha Kogyo), Doverphos S-9228 (Dover Chemical) etc. can be used. As the hindered phenol stabilizer (antioxidant), a general compound blended in a conventional resin can be used. The hindered phenol stabilizer may be, for example, 3,9-bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, but is not limited thereto, and any hindered phenol compound used as an oxidation stabilizer of a resin composition in the relevant technical field may be used. The content of the phosphorus stabilizer and the hindered phenol antioxidant in the biodegradable resin composition may be 0 to 5 wt%, 0 to 3 wt%, or 0 to 1 wt% with respect to the total weight of the biodegradable resin composition.

The biodegradable resin composition may include an ultraviolet absorber. By including an ultraviolet absorber, it is possible to suppress deterioration of the weather resistance of a molded product due to the influence of a rubber component or a flame retardant. As the ultraviolet absorber, a benzophenone-based ultraviolet absorber; a benzotriazole-based ultraviolet absorber; a hydroxyphenyl triazine-based ultraviolet absorber; a cyclic iminoester-based ultraviolet absorber; a cyanoacrylate-based ultraviolet absorber, etc. may be used. The content of the ultraviolet absorber in the biodegradable resin composition may be 0 to 5 wt%, 0 to 3 wt%, or 0 to 1 wt% of the total weight of the biodegradable resin composition.

The biodegradable resin composition may contain dyes or pigments as colorants to impart various colors to the molded product.

The biodegradable resin composition may include an antistatic agent to impart antistatic performance to the molded product.

The biodegradable resin composition may additionally contain, in addition to the above, a thermoplastic resin, a flow modifier, an antibacterial agent, a dispersant such as liquid paraffin, a photocatalytic fouling agent, a heat ray absorber, and a photochromic agent.

The step of preparing a biodegradable resin blend by blending a biodegradable resin composition can be performed by, for example, an extruder, a Banburry mixer, a kneader, a continuous kneader, a roll, etc.

In the step of preparing the biodegradable resin blend, an extruder may be used in particular. The extruder may include, for example, a first zone including a hopper, a second zone including a header, and one or more intermediate zones disposed therebetween. The temperatures of the first zone, the second zone, and the one or more intermediate zones therebetween may be independently from one another 175 to 200° C. or 180 to 195° C. When the first zone, the second zone, and the intermediate zone have temperatures in this range, the biodegradable resin composition can be blended more effectively. If the temperatures of the first zone, the second zone, and the intermediate zone are too low, blending of the biodegradable resin composition may be incomplete. If the temperatures of the first zone, the second zone, and the intermediate zone are too high, thermal decomposition of the biodegradable resin may occur.

The temperature in the extruder can increase from the first region through the intermediate region to the second region. The temperature of the second region can be higher than that of the first region. The temperature difference between the second region and the first region can be 5 to 20° C. or 10 to 20° C. The intermediate region can include, for example, a third region, a fourth region, a fifth region, and a sixth region. For example, the temperature of the first region can be 175 to 185° C. For example, the temperature of the second region can be 190 to 200° C. For example, the temperature of the third region can be 180 to 190° C. For example, the temperature of the fourth region can be 180 to 190° C. For example, the temperature of the fifth region can be 185 to 195° C. For example, the temperature of the sixth region can be 185 to 195° C. Since the first to sixth zones have such temperature ranges, the biodegradable resin blend can be more easily manufactured. The biodegradable resin composition described above can be fed, for example, through a hopper in the first zone, and sequentially passed through the third zone, the fourth zone, the fifth zone, and the sixth zone, and then the biodegradable resin blend can be discharged through a die in the second zone including a header. The biodegradable resin composition is blended while moving, for example, from the third zone to the sixth zone.

Next, the biodegradable resin blend is heated to prepare a molten biodegradable resin blend.

Biodegradable fibers can be spun from the molten biodegradable resin blend by melting the biodegradable resin blend to prepare a molten biodegradable resin blend.

The temperature of the molten biodegradable resin blend can be, for example, 200 to 300 °C, 200 to 250 °C or 200 to 230 °C. The melt flow rate (MFR) of the molten biodegradable resin blend measured at 230 °C according to ASTM D1238 in this temperature range can be, for example, greater than 120 g/10 min to 550 g/10 min, 121 g/10 min to 550 g/10 min, 150 g/10 min to 550 g/10 min, 200 g/10 min to 550 g/10 min, 250 g/10 min to 550 g/10 min or 300 g/10 min to 500 g/10 min.

Next, the molten biodegradable resin blend is spun to prepare a biodegradable fiber member.

Melting and spinning of the biodegradable resin blend can be performed sequentially or simultaneously. For example, the biodegradable resin blend in particle form can be fed into a spinning device, and the biodegradable resin blend can be melted and spun through a nozzle of a die simultaneously. Alternatively, the biodegradable resin blend in particle form can be fed into a spinning device, the biodegradable resin blend can be melted, and then the molten biodegradable resin blend can be spun through a die.

Conditions for spraying the molten biodegradable resin blend can be controlled by, for example, nozzle temperature, air pressure and air temperature.

The nozzle temperature for spinning the molten biodegradable resin blend can be, for example, 200 to 250° C., 210 to 240° C., or 220 to 230° C. By having a nozzle temperature in this range, the dimensional stability and/or properties of the spun biodegradable resin fibers can be more easily controlled. Accordingly, the manufactured biodegradable filter medium can have improved filtration efficiency and biodegradability.

The air pressure applied to the molten biodegradable resin fibers can be, for example, 1 to 10 Nm ³ /min, 2 to 8 Nm ³ /min, 3 to 7 Nm ³ /min or 4 to 5.5 Nm ³ /min. By having the air pressure in this range, the dimensional stability and/or physical properties of the spun biodegradable resin fibers can be more easily controlled. Accordingly, the manufactured biodegradable filter medium can have improved filtration efficiency and biodegradability.

The air temperature applied to the molten biodegradable resin fibers may be, for example, 205 to 255° C., 215 to 245° C., or 225 to 235° C. By having an air temperature in this range, the dimensional stability and/or physical properties of the radiated biodegradable resin fibers can be more easily controlled. Therefore, the manufactured biodegradable filter medium can have improved filtration efficiency and biodegradability.

The radiated biodegradable resin fibers can form a biodegradable fiber member.

Referring to Fig. 3, biodegradable resin fibers radiated from a nozzle can be arranged in a web shape on a collector and wound on a winder. In this way, a biodegradable fiber member can be manufactured. The biodegradable fiber member can be, for example, in the form of a non-woven fabric.

Next, the step of preparing a rolled biodegradable fiber member by rolling the biodegradable fiber member may be further included.

The filtration efficiency of the biodegradable filter media manufactured by additionally rolling the biodegradable fiber member can be further improved. The rolling of the biodegradable fiber member can be performed at, for example, 50 to 80° C., 55 to 75° C., or 60 to 70° C. If the rolling temperature is too low, the effect of improving the filtration efficiency may be minimal. If the rolling temperature is too high, defects may occur due to melting of the biodegradable fiber. The rolling can be performed, for example, by a heating roller. The heating roller can be, for example, a calender roller. The rolling can be performed, for example, by calendering. The calendering can be performed, for example, by a pair of calender rolls. The speed at which the biodegradable fiber member is supplied to the calendering rolls can be 10 cm/min to 20 m/min. The temperature of the calendering rolls can be, for example, 50 to 80° C., 55 to 75° C., or 60 to 70° C.

Next, the method may further include a step of electrifying the biodegradable fiber member to prepare an electrified biodegradable fiber member.

The treatment can be performed dry or wet.

Dry charging treatment is a method of directly charging a biodegradable fiber member without using a liquid, for example, a polar solvent. The dry charging treatment can be performed, for example, by electric charging. The dry charging treatment can be performed, for example, by plasma charging treatment or corona charging treatment. The charging treatment can be performed, for example, by electric charging. The voltage applied during the dry charging treatment can be, for example, 10 kV or more, 20 kV or more, 30 kV or more, or 40 kV or more. When the applied voltage has a value in this range, a positive charge can be effectively charged on the surface of the biodegradable fiber member.

Wet charging is a charging method using a liquid, for example, a polar solvent. As a wet charging method, for example, a method of applying a polar solvent to a biodegradable fiber member and then applying an external force at the same time as applying the polar solvent, or a method of applying an external force while immersing the biodegradable fiber member in a polar solvent filled in a container, etc., may be used. The polar solvent may be a liquid having low electrical conductivity, such as water, alcohol, acetone, or water containing ammonia dissolved therein. By using water as a polar solvent, the working environment when charging the biodegradable fiber member is excellent, and ignition can be prevented during the drying stage of the charged biodegradable fiber member. The temperature of the polar solvent used in the wet charging process may be, for example, 40°C or lower or 30°C or lower, but if it is not limited to this range, any temperature that can charge the biodegradable fiber member may be used. The method for applying the polar solvent to the biodegradable fiber member may be, for example, a method for applying the polar solvent in the form of a mist, droplet, or liquid using a spray, shower, or nozzle. The method for immersing the biodegradable fiber member in the polar solvent may be, for example, a method for using an impregnation device. The method for applying or immersing the polar solvent to the biodegradable fiber member is not limited to the above-described methods, and any method capable of electrifying the biodegradable fiber member may be used. The method for applying the force may be, for example, a method for applying ultrasonic waves, vibration, or a method for colliding a solvent flow of a polar solvent. By using a method for colliding a solvent flow of a polar solvent, the polar solvent can be applied to the biodegradable fiber member while simultaneously applying the force. By using an ultrasonic method, the formation of open pores and changes in fiber orientation in the biodegradable fiber member can be prevented during the process of applying the force. The intensity or time of the force applied to the biodegradable fiber member can be appropriately adjusted in order to increase the amount of charge of the biodegradable fiber member.

The biodegradable fibrous member charged by the wet charging method may be subjected to an additional drying process to remove the polar solvent. Drying of the charged biodegradable fibrous member may be performed by a device such as a candle dryer, a heating roller, a hot air dryer, a hot air dryer, an electric furnace, a heat plate, or the like. The drying temperature may be, for example, 120° C. or lower, 105° C. or lower, or 90° C. or lower. Alternatively, without using a drying device, the charged biodegradable fibrous member may be dried naturally as a fiber or nonwoven fabric, or the polar solvent may be removed by applying ultrasonic waves or vibrations to the biodegradable fibrous member.

The charging treatment can be performed, for example, by hydrocharging. The water pressure applied to one side of the biodegradable fiber member during hydrocharging can be, for example, 0.1 bar or more, 0.5 bar or more, 1 bar or more, 2 bar or more, 3 bar or more, 5 bar or more, or 10 bar or more. By applying the water pressure in this range, water can be sufficiently supplied to the inside of the biodegradable fiber member. The suction rate applied to the other side of the biodegradable fiber member opposite to the one side during hydrocharging can be 50% or more, 60% or more, 70% or more, or 80% or more. The suction rate represents, for example, the ratio of the suction motor RPM to the maximum output value of the process in the suction step for removing water before the drying step after the moisture treatment during hydrocharging. If the suction rate is too low, the charging effect can be poor. Excessively high suction rates may increase the likelihood of defects in the biodegradable fiber member.

According to another embodiment, a biodegradable filter medium comprises a biodegradable fibrous member, wherein the biodegradable fibrous member comprises a biodegradable resin and an additive, wherein the additive comprises a viscosity modifier, a charging agent, or a combination thereof.

The biodegradable fiber member may satisfy, for example, the following mathematical expression 1:

<Mathematical Formula 1>

7 < [A + 1/10ХB]

In the above formula,

A is the elongation (%) of the biodegradable filter material at 25 ℃, and B is the tensile strength (kgf/cm ² ) of the biodegradable filter material at 25 ℃.

The biodegradable filter medium may have, for example, a value of [A + 1/10ХB] of 8 or more, 9 or more, 10 or more, 15 or more, or 20 or more in mathematical formula 1. When the biodegradable filter medium satisfies mathematical formula 1, the dimensional stability and durability of the biodegradable filter medium are improved, and the biodegradable filter medium can be easily formed into various shapes.

The elongation at break of the biodegradable filter medium as measured in accordance with ASTM D 638 can be, for example, 4 % or more, 10 % or more, or 20 % or more. The elongation at break of the biodegradable filter medium can be, for example, 200 % or less, 100 % or less, or 50 % or less. The elongation at break of the biodegradable filter medium can be, for example, 4 % to 200 %, 4 % to 100 %, 4 % to 50 %, 10 % to 50 %, or 20 % to 50 %. If the elongation at break of the biodegradable filter medium is too low, it may be difficult to form the biodegradable filter medium into other shapes. For example, it may be difficult to apply the biodegradable filter medium to a bonding process with other filter materials. If the elongation at break of the biodegradable filter medium is too high, the dimensional stability of the biodegradable filter medium may be deteriorated and the durability may be deteriorated.

The tensile strength of the biodegradable filter medium, as measured according to ASTM D 638, can be, for example, 4.0 kgf/cm ² or greater, 6.0 kgf/cm ² or greater, 8.0 kgf/cm ² or greater, 10.0 kgf/cm ² or greater, or 20 kgf/cm ² or greater. The tensile strength of the biodegradable filter medium can be, for example, 4.0 to 100 kgf/cm ² , 6.0 to 80 kgf/cm ² , 8.0 to 60 kgf/cm ² , 10 to 50 kgf/cm ^{2 ,} or 20 to 50 kgf/cm ² . If the tensile strength of the biodegradable filter medium is too low, the dimensional stability of the biodegradable filter medium may be deteriorated and the durability may be deteriorated. If the tensile strength of the biodegradable filter medium is too high, it may be difficult to shape the biodegradable filter medium into another shape. For example, it may be difficult to apply biodegradable media to processes such as blending with other media.

For a melt of the biodegradable filter material, the melt index, more specifically the melt flow rate (MFR), measured at 230° C. according to ASTM D1238, can be, for example, more than 120 g/10 min to 550 g/10 min, 121 g/10 min to 550 g/10 min, 150 g/10 min to 550 g/10 min, 200 g/10 min to 550 g/10 min, 250 g/10 min to 550 g/10 min or 300 g/10 min to 500 g/10 min. The melt flow rate (MFR) according to ASTM D1238 can be determined, for example, by measuring the weight of the resin discharged through an orifice having an inner diameter of 2.09 mm and a length of 8 mm at 230° C., using a 160 g load, for 10 minutes. If the melt flow rate is too low, the diameter of the fibers to be spun may increase excessively, which may lower the filtration efficiency of the biodegradable media at the same thickness. If the melt flow rate is too high, the heat resistance of the fibers to be spun may be lowered, which may cause thermal deformation of the biodegradable resin blend during the melting step and/or the spinning step, which may make it difficult to manufacture the biodegradable media.

The biodegradation period of the biodegradable filter medium can be, for example, 80% or less, 75% or less, 70% or less, 60% or less, or 50% or less of the biodegradation period of a biodegradable filter medium composed solely of a biodegradable resin used in the manufacture of the biodegradable filter medium. Since the biodegradable filter medium is manufactured from a biodegradable resin composition additionally comprising an additive including a viscosity modifier, a charging agent, or a combination thereof, the biodegradation period can be shortened compared to a biodegradable filter medium manufactured from only a biodegradable resin without such additive. Accordingly, the recycling efficiency of the biodegradable filter medium can be further improved. The biodegradable filter medium manufactured from a biodegradable resin composition additionally comprising an additive including a viscosity modifier, a charging agent, or a combination thereof includes an additive, and the additive can include the viscosity modifier, the charging agent, or a combination thereof. The biodegradability of the biodegradable filter medium can be measured, for example, according to ISO 14855-2.

The biodegradable filter medium comprises a biodegradable fibrous member, wherein the biodegradable fibrous member can be, for example, a web comprising biodegradable fibers. The biodegradable filter medium can be, for example, in the form of a biodegradable nonwoven fabric. The fiber diameter of the biodegradable fibrous member can be, for example, 1 to 10 μm, 1 to 8 μm, 1 to 6 μm or 1 to 4 μm. When the biodegradable fibrous member has a fiber diameter in this range, the filtration efficiency and biodegradability of the biodegradable filter medium can be further improved. If the fiber diameter of the biodegradable fibrous member is excessively reduced, the strength of the biodegradable filter medium can be reduced. If the fiber diameter of the biodegradable fibrous member is excessively increased, the filtration efficiency and biodegradability of the biodegradable filter medium can be reduced.

The unit weight of the biodegradable filter medium can be, for example, 10 to 300 g/m ² , 20 to 200 g/m ² , 30 to 100 g/m ² or 30 to 80 g/m ² . When the biodegradable filter medium has the maximum unit weight in this range, improved filtration efficiency and biodegradability can be provided at the same time. If the unit weight of the biodegradable filter medium is excessively reduced, the mechanical strength may be excessively reduced, which may cause breakage of the biodegradable filter medium in a subsequent molding process, making it difficult to apply it to a subsequent molding process, etc. If the unit weight of the biodegradable filter medium is excessively increased, the energy required in a subsequent molding process may excessively increase, which may lower the process efficiency during filter manufacturing.

The average pore size of the biodegradable filter medium may be, for example, 10 to 50 μm, 10 to 40 μm, 10 to 30 μm or 10 to 20 μm. When the biodegradable filter medium has an average pore size in this range, it can provide both improved filtration efficiency and biodegradability. If the average pore size of the biodegradable filter medium is excessively reduced, the differential pressure may increase excessively, which may limit the application. If the average pore size of the biodegradable filter medium is excessively increased, the filtration efficiency may decrease excessively, which may make it difficult to apply it to filter applications.

The maximum pore size of the biodegradable filter medium can be, for example, 70 ㎛ or less, 60 ㎛ or less, 50 ㎛ or less, 40 ㎛ or less, or 35 ㎛ or less. When the biodegradable filter medium has a maximum pore size in this range, it can provide both improved filtration efficiency and biodegradability. If the maximum pore size of the biodegradable filter medium increases excessively, the filtration efficiency of the biodegradable filter medium may decrease. If the maximum pore size of the biodegradable filter medium decreases excessively, the differential pressure of the biodegradable filter medium may increase excessively. The fiber diameter, the average pore size, and the maximum pore size included in the biodegradable fibrous member can be calculated automatically by software or manually by manual means from, for example, a scanning electron microscope image of the biodegradable fibrous member.

The filtration efficiency of the biodegradable filter media measured according to EN1822 can be, for example, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, 98% or more or 99% or more. Due to the filtration efficiency of the biodegradable filter media, it can be applied to filters for various purposes. The differential pressure measured according to EN1822 of the biodegradable filter media can be, for example, 10 _mmH2O or less, 8 _mmH2O or less, 6 _mmH2O or less or 5 _mmH2O or less. The differential pressure measured according to EN1822 of the biodegradable filter media can be, for example, 0.1 _mmH2O or more, 0.5 _mmH2O or more, 0.7 _mmH2O or more or ₁ mmH2O or more. The differential pressure of the biodegradable filter medium as measured according to EN1822 can be, for example, 0.1 to 10 _mmH2O , _0.5 to 10 mmH2O, 0.5 to 8 _mmH2O , 0.5 to 6 _mmH2O or 0.5 to 5 _mmH2O or less. Since the biodegradable filter medium has a differential pressure in this range, it can be applied to various filters by simultaneously providing good filtration ability and filtration life. If the differential pressure of the biodegradable filter medium is too low, the filtration ability may be insufficient. If the inlet of the biodegradable filter medium is too high, the filter life may be excessively short.

The biodegradable filter medium can be, for example, a charged biodegradable filter medium. The charged biodegradable filter medium can include a charged charge. The charged biodegradable filter medium can filter negatively charged dusts and the like more effectively, for example, by being positively charged on the surface and/or inside of the biodegradable filter medium. The filtration efficiency of the charged biodegradable filter medium measured according to EN1822 can be, for example, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 98% or more, 99% or more. The filtration efficiency of the charged biodegradable filter medium can be improved by 10% or more, 20% or more, 30% or more, 40% or more, or 50% or more compared to the filtration efficiency of an uncharged biodegradable filter medium. Since the charged biodegradable filter medium provides such a high filtration efficiency, it can be applied to filters for various purposes. Biodegradable media is, for example, meltblown media manufactured by a meltblown process. Since the biodegradable media is a meltblown media, the filtration efficiency of the biodegradable media can be further improved.

A filter according to another embodiment comprises the biodegradable filter medium described above.

The filter may be, for example, an air purifying filter. The filter may have, for example, a single-layer structure or a multi-layer structure. The filter may have, for example, a single-layer structure composed of the biodegradable filter medium described above.

The filter has a multilayer structure including, for example, an inner layer and an outer layer, and at least one of the inner layer and the outer layer may include the biodegradable filter medium described above. Both the inner layer and the outer layer may be made of a biodegradable resin. The filter may not include a petroleum-based non-biodegradable resin. The filter may have a multilayer structure including, for example, a filter layer and a support layer. The filter layer may be arranged upstream of the air flow compared to the support layer, and at least one of the filter layer and the support layer may include the biodegradable filter medium described above. The filter may have a multilayer structure including, for example, at least one filter layer arranged between a plurality of support layers. Since the filter has such a structure, it can provide excellent dust collection efficiency and durability. In addition, the filter assembly can be configured by further including a filter holder that mechanically supports the filter. As a result, the filter assembly can provide excellent dust collection efficiency and mechanical properties at the same time. Therefore, the filter assembly can be used for various purposes.

Referring to FIG. 3, a filter (1) includes an inner layer (100) and an outer layer (200), the inner layer (100) includes a first filter layer (10) including the biodegradable filter medium described above, the biodegradable filter medium including a first biodegradable polymer, the outer layer (200) includes a second support layer (40) disposed on one surface of the inner layer (100) and including a second biodegradable polymer; and a third support layer (50) disposed on the other surface of the inner layer (100) and including a third biodegradable polymer, the second support layer (40) being disposed upstream of the air flow compared to the first filter layer (10).

The inner layer (100) includes a first filter layer (10) that provides a filtering function to the filter. The outer layer (200) includes a second support layer (40) and a third support layer (50) that each protect both sides of the inner layer (100).

The first filter layer (10) is, for example, the biodegradable filter medium described above, and includes the first biodegradable polymer. Alternatively, the first filter layer (10) is, for example, a meltblown nonwoven fabric including the biodegradable filter medium described above. Since the first filter layer (10) includes the meltblown nonwoven fabric, the filter can provide excellent filtration efficiency. The first filter layer (10) can be manufactured by, for example, thermocompression bonding the biodegradable filter medium alone or together with another layer, but is not necessarily limited to this method, and can be manufactured by a known meltblown nonwoven fabric manufacturing method within the scope of using the biodegradable filter medium.

At least one of the second support layer (40) and the third support layer (50) is, for example, a spunbond nonwoven fabric. The second support layer (40) and the third support layer (50) are, for example, a spunbond nonwoven fabric containing a second biodegradable polymer. Since the second support layer (40) and/or the third support layer (50) contains a spunbond nonwoven fabric, the inner layer (100) can be protected and the mechanical strength of the filter (1) can be further improved.

The second support layer (40) and the third support layer (50) can be manufactured by, for example, melt-spinning a third biodegradable polymer to produce a spunbond web and then thermo-compression bonding it alone or together with other layers, but are not necessarily limited to this method and can be manufactured by a known meltblown nonwoven fabric manufacturing method.

Referring to FIG. 4, a filter (1) includes an inner layer (100) and an outer layer (200), the inner layer (100) includes a first filter layer (10) including the biodegradable filter medium described above; and a first support layer (20) including a second biodegradable polymer, the outer layer (200) includes a second support layer (40) disposed on one surface of the inner layer (100) and including a third biodegradable polymer; and a third support layer (50) disposed on the other surface of the inner layer (100) and including a third biodegradable polymer, and the first filter layer (10) is disposed upstream of the air flow compared to the first support layer (20). The biodegradable filter medium includes the first biodegradable polymer.

The inner layer (100) includes a first filter layer (10) that mainly provides a filtering function to the filter and a first support layer (20) that supports the first filter layer (20). The outer layer (200) includes a second support layer (40) and a third support layer (50) that protect both sides of the inner layer (100), respectively.

The first filter layer (10) is, for example, the biodegradable filter medium described above, and includes the first biodegradable polymer. Alternatively, the first filter layer (10) is, for example, a meltblown nonwoven fabric including the biodegradable filter medium described above. Since the first filter layer (10) includes the meltblown nonwoven fabric, the filter can provide excellent dust collection efficiency. The first filter layer (10) can be manufactured by, for example, thermocompression bonding the biodegradable filter medium alone or together with another layer, but is not necessarily limited to this method, and can be manufactured by a known meltblown nonwoven fabric manufacturing method within the scope of using the biodegradable filter medium.

At least one of the second support layer (40) and the third support layer (50) is, for example, a spunbond nonwoven fabric. The first support layer (20) is, for example, a spunbond nonwoven fabric containing the third biodegradable polymer. Since the first support layer (20) includes a spunbond nonwoven fabric containing the second biodegradable polymer, the filter bag (1) can provide excellent mechanical strength. The second support layer (40) and/or the third support layer (50) is, for example, a spunbond nonwoven fabric containing the second biodegradable polymer. Since the second support layer (40) and/or the third support layer (50) includes a spunbond nonwoven fabric, the inner layer (100) can be protected and the mechanical strength of the filter bag (1) can be further improved.

The first support layer (20) can be manufactured by, for example, melt-spinning a second biodegradable polymer to produce a spunbond web and then thermo-compression-bonding it alone or together with another layer, but is not necessarily limited to this method, and can be manufactured by a known spunbond nonwoven fabric manufacturing method. The second support layer (40) and the third support layer (50) can be manufactured by, for example, melt-spinning a third biodegradable polymer to produce a spunbond web and then thermo-compression-bonding it alone or together with another layer, but is not necessarily limited to this method, and can be manufactured by a known meltblown nonwoven fabric manufacturing method.

Referring to FIG. 5, the inner layer (100) may further include a second filter layer (30) that is disposed, for example, on one side of the first filter layer (10) and includes a fourth biodegradable polymer, as compared to FIG. 4. Since the inner layer (100) additionally includes the second filter layer (30), the dust collection efficiency of the filter (1) may be further improved. The second filter layer (30) may include, for example, the biodegradable filter medium described above. The biodegradable polymers included in the first filter layer (10) and the second filter layer (30) may be the same or different from each other.

The breaking elongation of the second biodegradable polymer included in the first support layer (20) may be greater than the breaking elongation of the first biodegradable polymer included in the first filter layer (10). In addition, the breaking elongation of the second biodegradable polymer included in the first support layer (20) may be greater than the breaking elongation of the third biodegradable polymer included in the second support layer (40) and the third support layer (50). The durability of the filter may be improved by the first support layer (20) including the second biodegradable polymer having an improved breaking elongation.

The first biodegradable polymer can include, for example, polylactic acid. For specific details on polylactic acid, see the section on biodegradable resin compositions described above. The second biodegradable polymer and the third biodegradable polymer can be selected from, for example, the biodegradable polymers included in the biodegradable filter medium. The first biodegradable polymer, the second biodegradable polymer, and the third biodegradable polymer can be the same or different. The fourth biodegradable polymer can include, for example, polybutylene succinate, polycaprolactone, or a combination thereof. For more specific details on polybutylene succinate and polycaprolactone, see the section on biodegradable resins described above.

A home appliance according to another embodiment may include the filter described above. The home appliance may include, for example, an air purifying filter.

The home appliance can provide an excellent filtration effect by including the filter described above. The home appliance includes, but is not limited to, a vacuum cleaner, an air purifier, etc., and any home appliance that includes the filter described above is possible.

Alternatively, industrial, industrial or military products other than home appliances may also include the above-described filters. Industrial products may be, for example, large trucks. Industrial products may be, for example, large plants such as semiconductor factories. Military products may be, for example, military vehicles.

The present invention is described in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the present invention and the scope of the present invention is not limited to these examples.

(Manufacture of biodegradable filter media)

Examples 1 to 11 and Comparative Examples 1 to 4

Biodegradable resin compositions of Examples 1 to 11 and Comparative Examples 1 to 4 having the compositions shown in Table 1 were prepared by mixing 2.5-dimethyl-2,5-di(tert-butylperoxy)hexane as a viscosity control agent and/or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane as a charging agent with respect to 100 parts by weight of polylactic acid homopolymer (PLLA, NatureWorks 4030D) as a biodegradable resin. The biodegradable resin compositions did not contain a separate solvent. The biodegradable resin compositions were fed into an extruder and extruded to prepare biodegradable resin blends.

The extruder included a first zone including a hopper, a second zone including a head, and third zones, fourth zones, fifth zones and sixth zones sequentially arranged from the first zone to the second zone between the first zone and the second zone.

The temperature of the first region was 180 ℃, the temperatures of the third and fourth regions were 185 ℃, the temperatures of the fifth and sixth regions were 190 ℃, and the temperature of the second region was 195 ℃.

The feed weight was 12 kg/hr, the screw speed was 600 rpm and the die pressure was 36 bar. The die was included in the head.

A biodegradable fiber member was manufactured by melting a biodegradable resin blend and spinning it using a melt-blown method. The biodegradable fiber member had a nonwoven form. The biodegradable fiber member corresponds to a biodegradable filter medium.

In the melt blown process, the nozzle temperature was 220-230 ℃, the air pressure was 4 to 5.5 Nm ³ /min., and the air temperature was 225 to 235 ℃.

The biodegradable fiber members manufactured in Examples 5 to 10 were charged by adding an electric charging process. The electric charging process was performed by corona charging.

The biodegradable fiber member manufactured in Example 11 was manufactured by adding a hydrocharging process.

The hydrocharging process was performed by supplying distilled water at a water pressure of 2 bar on one side of the biodegradable fiber member and suctioning the opposite side at a suction rate of 80%, followed by drying.

The biodegradable fiber members manufactured in Examples 10 and 11 were manufactured by adding a calendering process of passing the biodegradable fiber members between a pair of calendering rolls at 70° C.

Evaluation Example 1: Melt Flow Measurement

Melt flow was measured for the biodegradable resin blends prepared in Examples 1 to 11 and Comparative Examples 1 to 4.

Melt flow rate was measured at 230°C according to ASTM D1238 using a melt flow meter (Dynisco Melt Flow Indexer, LMI 5000 Series, load 2160 g).

Melt flow rate (MFR, g/10 min) is the weight of the resin extruded for 10 minutes at a constant temperature and a specified force. The measurement results are shown in Table 1 below.

Evaluation Example 2: Measuring Filtration Efficiency

The filtration efficiency was measured for the nonwoven biodegradable filter media manufactured in Examples 1 to 11 and Comparative Examples 1 to 2.

Filtration efficiency was measured according to EN1822 using a filter tester (TSI Corporation, model 8130A, flow rate 32 L/min, NaCl 0.3 ㎛ particles). Filtration efficiency is the particle removal rate when a fluid containing particles of a certain size is passed through an area of 100 cm ² of nonwoven fabric at a certain speed. The measurement results are shown in Table 1 below.

Viscosity modifier content [wt%] Melt Flow Rate (MFR) [g/10min] Preliminary content [wt%] Calculating temperature [℃] Charging Conditions Filtration efficiency [%] Comparative Example 1 0 70 0 - - 8.7 Comparative Example 2 0.5 120 0 - - 14.6 Example 1 0.7 205 0 - - 16.0 Example 2 0.8 250 0 - - 17.2 Example 3 1.0 450 0 - - 23.7 Example 4 1.5 530 0 - - 16.9 Comparative Example 3 2.0 600 0 - - No radiation Comparative Example 4 3.0 700 0 - - No radiation Example 5 1.0 450 0 - Electric charging 68 Example 6 1.0 450 0.5 - Electric charging 79 Example 7 1.0 450 1.0 - Electric charging 89 Example 8 1.0 450 2.0 - Electric charging 86 Example 9 1.0 450 3.0 - Electric charging 89 Example 10 1.0 450 1.0 70 Electric charging 92 Example 11 1.0 450 1.0 70 Electric charging 95

As shown in Table 1, the biodegradable filter media manufactured in Examples 1 to 4 showed improved melt flowability and improved filtration efficiency compared to the biodegradable filter media manufactured in Comparative Examples 1 to 2.

In Comparative Examples 1 and 2, the melt flow of the biodegradable resin blend was lowered compared to Examples 1 to 4, and thus the spinning of fine biodegradable fibers was not performed smoothly. Therefore, the filtration efficiency of the biodegradable filter media manufactured in Comparative Examples 1 and 2 was lowered.

In Comparative Examples 3 to 4, the melt flow of the biodegradable resin blend was improved compared to Examples 1 to 4, but thermal decomposition occurred. Therefore, defects occurred during the spinning process from the molten resin blend, making it impossible to manufacture a biodegradable fiber member.

The biodegradable filter media manufactured in Examples 5 to 11 had further improved filtration efficiency by adding a charging process.

The biodegradable filter media manufactured in Examples 6 to 9 had improved filtration efficiency compared to Example 5 by additionally including a precipitator.

The biodegradable emulsifiers manufactured in Examples 10 to 11 had additionally improved filtration efficiency by adding a calendaring process.

Evaluation Example 3: Biodegradability Evaluation

The biodegradability of the biodegradable filter media manufactured in Examples 2 to 3 and Comparative Example 1 was evaluated.

Biodegradability was measured according to ISO 14855-2. The time required to reach 80% biodegradability was measured and is shown in Table 2 below.

Melt Flow Rate (MFR)
[g/10min] Biodegradation period
[Day] Comparative Example 1 70 45 Example 2 250 28 Example 3 450 20

As shown in Table 2, the biodegradation period of the biodegradable filter media of Examples 2 to 3 was reduced by 80% or less compared to the biodegradation period of the biodegradable filter media of Comparative Example 1.

The biodegradability of the biodegradable filter media of Examples 2 to 3 was significantly improved compared to the biodegradable filter media of Comparative Example 1.

Evaluation Example 4: Measurement of fiber diameter, average pores, maximum pores, and unit weight

For the cross-sections of the biodegradable filter media manufactured in Examples 1 to 4, images were measured using a scanning electron microscope, and the biodegradable average fiber diameter, average pore size, and maximum pore size were calculated using image analysis software. The calculation results are shown in Table 3 below. The average fiber diameter is the arithmetic mean value of the diameters of the fibers measured in the cross-section images of the biodegradable filter media. The average pore size is the arithmetic mean value of the diameters of the pores defined by the fibers measured in the cross-section images of the biodegradable filter media. The maximum pore size is the maximum value among the pore sizes used in the calculation of the average pore size.

The unit weight was derived by measuring the area and weight of the biodegradable filter media manufactured in Examples 1 to 4. The unit weight is shown in Table 3 below.

Average fiber diameter [㎛] Average pore size
[㎛] Maximum pore size [㎛] Unit weight
[g/m ² ] Example 1 4.75 ± 0.92 10.8 ± 0.4 26.8 ± 2.7 60 Example 2 4.32±0.63 11.8 ± 0.4 31.1 ± 1.9 60 Example 3 2.53 ± 0.65 14.9 ± 0.1 36.0 ± 0.3 60 Example 4 2.93 ± 0.75 12.3±0.3 28.1 ± 1.3 60

As shown in Table 3, the biodegradable filter media manufactured in Examples 1 to 4 exhibited an average fiber diameter of 2 to 5 μm, an average pore size of 10 to 20 μm, and a maximum pore size of 40 μm or less.

[Explanation of symbols]

1 filter 10 1st filter layer

20 1st support layer 30 2nd filter layer

40 2nd support layer 50 3rd support layer

100 inner layer 200 outer layer

According to one aspect, a biodegradable filter medium having improved properties can be manufactured by controlling the melt flowability of a molten biodegradable resin blend.

The filtration efficiency and biodegradability of the biodegradable filter medium manufactured by this method can be improved.

Claims (15)

A step of preparing a biodegradable resin blend by blending a biodegradable resin composition; A step of preparing a molten biodegradable resin blend by heating the biodegradable resin blend; and A step of preparing a biodegradable fiber member by spinning the above-mentioned molten biodegradable resin blend, The above biodegradable resin composition comprises a biodegradable resin and an additive, wherein the additive comprises a viscosity modifier, a charging agent or a combination thereof, A method for manufacturing a biodegradable filter material, wherein the melt flow rate (MFR) of the above-mentioned melted biodegradable resin blend measured at 230° C. according to ASTM D1238 is greater than 120 g/10 min to 550 g/10 min. A method for producing a biodegradable filter medium in claim 1, wherein the biodegradable resin comprises polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PBH), cellulose or a combination thereof. In the first paragraph, the biodegradable resin composition comprises polylactic acid, The above biodegradable resin composition is free of petroleum-based non-biodegradable resin, A method for producing a biodegradable filter material, wherein the polylactic acid content is 97 wt% or more based on the total weight of the biodegradable resin composition. In the first paragraph, the viscosity modifier comprises an organic peroxide-based viscosity modifier, a vinyl-based viscosity modifier, an acrylic-based viscosity modifier, or a combination thereof. The above organic peroxide viscosity modifier is 2.5-dimethyl-2,5-di(tert-butylperoxy)hexane, ditert-butyl peroxide, ditert-amyl peroxide, tert-butyl cumyl peroxide, di(tert-butylperoxy-isopropyl)-benzene, dicumyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, Containing 3,3,5,7,7-pentamethyl-1,2,4-trioxepane or a combination thereof, The above vinyl-based viscosity modifier includes poly(vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate), fluoroethylene vinyl ether, 2-butenedioic acid (2Z)-, 1-(1-methylethyl) ester, N,N'-bis(2,2,6,6,-tetramethylpiperidin-4-yl)-1,3-dicarboxamide, or a combination thereof. The above acrylic viscosity modifier includes methyl methacrylate, ethyl methacrylate, butyl methacrylate, propyl methacrylate, butyl methacrylate or a combination thereof. In the first paragraph, the charging agent includes a metal oxide charging agent, an imide charging agent, or a combination thereof, A method for manufacturing a biodegradable filter medium, wherein the metal oxide charge comprises TiO ₂ , SiO ₂ , ZnO, SnO ₂ or a combination thereof. A method for producing a biodegradable filter medium, wherein the above imide-based premise comprises Poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-s-triazine-2,4-diyl]-[(2,2,6,6-tetramethyl-4-piperidyl)imino]-hexamethylene-[(2,2,6,6-tetramethyl-4-piperidyl)imino], 4-Nitro-N-phenylphthalimide, 1,4-Phenylene-bis-maleimide, 4,4'-Bismaleimidodiphenylmethane or a combination thereof. In the first paragraph, the biodegradable resin composition comprises 0.5 to 2 parts by weight of the organic peroxide viscosity modifier per 100 parts by weight of the biodegradable resin, or The biodegradable resin composition comprises 0 to 5 parts by weight of the metal oxide electrostatic agent per 100 parts by weight of the biodegradable resin, or The biodegradable resin composition comprises 0.5 to 2 parts by weight of the organic peroxide viscosity modifier and 0 to 5 parts by weight of the metal oxide charging agent, based on 100 parts by weight of the biodegradable resin. A method for producing a biodegradable filter medium, wherein the biodegradable resin composition is free of a solvent. In the first paragraph, the step of preparing the biodegradable resin blend is performed by an extruder, The extruder comprises a first region comprising a hopper, a second region comprising a header, and at least one intermediate region disposed therebetween, The temperatures of the first region, the second region and at least one intermediate region therebetween are independently 175 to 200° C., A method for manufacturing a biodegradable filter medium, wherein the temperature increases from the first region through the intermediate region to the second region. In the first paragraph, a step of preparing a rolled biodegradable fiber member by rolling the biodegradable fiber member is further included, The above rolling is performed at 55 to 75° C., and further includes a step of electrifying the biodegradable fiber member to prepare an electrified biodegradable fiber member. The above charging process is performed by electric charging or hydro charging, The voltage applied during the above electric charging is 10 kV or more, A method for manufacturing a biodegradable filter medium, wherein the applied water pressure during the hydrocharging is 1 bar or higher and the suction rate is 50% or higher. Contains biodegradable fibers, The above biodegradable fiber member comprises a biodegradable resin and an additive, A biodegradable filter medium comprising the above additives, a viscosity modifier, a charging agent or a combination thereof. In claim 9, a biodegradable filter material having a melt flow rate (MFR) measured at 230° C. according to ASTM D1238 of more than 120 g/10 min to 550 g/10 min with respect to a melt of the biodegradable filter material. A biodegradable filter medium in claim 9, wherein the biodegradation period of the biodegradable filter medium is 80% or less of the biodegradation period of a biodegradable filter medium composed only of the biodegradable resin. In the 9th paragraph, the fiber diameter of the biodegradable fiber member is 1 to 10 ㎛, The unit weight of the biodegradable filter material ^is 10 to 300 g/m2, the average pore size is 10 to 20 ㎛, and the maximum pore size is 40 ㎛ or less. A biodegradable filter medium having a filtration efficiency of 50% or more and a differential pressure of 5 _mmH2O or less as measured according to EN1822. A biodegradable filter medium in claim 9, wherein the biodegradable filter medium is a charged biodegradable filter medium, and the filtration efficiency of the charged biodegradable filter medium measured according to EN1822 is 75% or more. An air purifying filter comprising a biodegradable filter medium according to any one of claims 12 to 13. A home appliance comprising an air purifying filter according to Article 14.

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