KR102693250B1 - Synthetic leather for crash pad and preparation method thereof - Google Patents

Abstract

The present invention relates to a composite functional artificial leather useful as a cover for a crash pad having excellent durability and reduced residual volatile organic compounds (VOCs), and to a crash pad including the same.
An artificial leather for a crash pad according to one aspect comprises: a fiber substrate layer made of a high-density ultra-fine fiber nonwoven fabric; a solvent-free urethane adhesive layer provided on the fiber substrate layer and having micropores formed by inorganic hollow spheres; and a skin layer provided on the solvent-free urethane adhesive layer and including a polyurethane resin manufactured by reacting a polyol compound, an amine chain extender, and an alicyclic isocyanate compound.

Description

Synthetic leather for crash pad and preparation method thereof

The present invention relates to a composite functional artificial leather useful as a cover for a crash pad having excellent durability and reduced residual volatile organic compounds (VOCs), and to a crash pad including the same.

The vehicle interior part called crash pad is installed at the bottom of the windshield, and is manufactured in a shape that can be attached to a dashboard that integrates various instruments such as a speedometer and fuel gauge, as well as audio and navigation. In particular, for safety, a skin layer is formed to have various patterns on a urethane foam layer that absorbs shock and provides cushioning. A typical crash pad is composed of a product that has been surface-treated using a spray method on a urethane foam layer.

However, the above method has limitations in implementing various surface patterns, and it is difficult to implement a luxurious vehicle interior atmosphere such as a high-sensitivity touch.

Recently, crash pads are being developed in the form of natural leather wrapping to express a high-sensitivity touch and a luxurious vehicle interior atmosphere. Natural leather materials are usually manufactured from cowhide, but cowhide can express a luxurious interior atmosphere, but due to the nature of the material, there is a large difference depending on the age or part of the cow, and wrinkles, shrinkage, and deformation occur depending on the management method. In addition, since it is entirely dependent on imports and is expensive, it is limited to luxury cars, which limits its application to various car models. Therefore, there is a need for the development of artificial leather that exhibits a similar appearance to natural leather and high durability, and crash pads utilizing it.

One aspect is to provide an artificial leather for a crash pad and a crash pad including the same, which uses a high-density ultra-fine fiber nonwoven fabric as a fiber substrate and controls the polyol composition of polyurethane forming a solvent-free adhesive layer, a skin layer, and a surface treatment layer to improve the physical properties.

In addition, the present invention aims to provide an artificial leather for a crash pad using a 100% solid solvent-free urethane adhesive applied to a solvent-free adhesive layer, and a crash pad including the same.

In addition, it is intended to provide an artificial leather for a crash pad having microscopic pores formed in a non-woven adhesive layer and a crash pad including the same.

An artificial leather for a crash pad according to one aspect comprises: a fiber substrate layer made of a high-density ultra-fine fiber nonwoven fabric; a solvent-free urethane adhesive layer provided on the fiber substrate layer and having micropores formed by inorganic hollow spheres; and a skin layer provided on the solvent-free urethane adhesive layer and made of a polyurethane resin manufactured by reacting a polyol compound, a polyisocyanate compound, and a chain extender.

In addition, the method may further include a surface treatment layer formed by combining with a skin layer and coating with a urethane surface treatment coating solution.

Additionally, the high-density microfiber nonwoven fabric may include one having a density of 0.2 to 0.6 g/cm3.

In addition, the high-density ultra-fine nonwoven fabric may include a sea-island type fiber comprising at least one thermoplastic resin selected from the group consisting of polyamide (PA), polyethylene terephthalate (PET), and polytrimethylene terephthalate (PTT) as a main component, and at least one selected from the group consisting of a low-molecular-weight polyethylene terephthalate copolymer (co-PET) and polylactic acid (PLA) as a marine component.

In addition, the high-density ultrafine fiber nonwoven fabric may include a product manufactured by a step of performing an ultrafine fiber process on a high-density nonwoven fabric in a sodium hydroxide (NaOH) aqueous solution having a concentration of 2 to 10% for 5 to 30 minutes.

In addition, the solvent-free polyurethane adhesive layer may include a hydroxyl-terminated urethane prepolymer polymerized with a resin including a polyol compound, a chain extender, and a polyisocyanate compound, a crosslinking agent in an amount of 10 to 40 parts by weight relative to the hydroxyl-terminated urethane prepolymer, and an inorganic hollow sphere in an amount of 5 to 20 parts by weight relative to the hydroxyl-terminated urethane prepolymer.

In addition, the polyol compound may include 65 to 80 parts by weight of a carbonate-based polyol having a weight average molecular weight in the range of 500 to 3000, 12 to 30 parts by weight of an ether-based polyol having a weight average molecular weight in the range of 500 to 3000, and 2 to 10 parts by weight of an ester-based polyol having a weight average molecular weight in the range of 1000 to 3000.

Additionally, the chain extender may include at least one selected from the group consisting of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and dipropylene glycol.

Additionally, the polyisocyanate compound may include at least one selected from the group consisting of 4,4-diphenylmethane diisocyanate (DMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H ₁₂ MDI), and xylene diisocyanate (XDI).

In addition, the non-solvent type urethane adhesive layer may have micropores formed by inorganic hollow spheres having a particle diameter of 50 to 120 ㎛ and a density of 0.1 to 0.3 g/cm3.

Additionally, the non-woven polyurethane adhesive layer may have a thickness in the range of 100 to 450 ㎛.

Additionally, the polyol compound of the skin layer may include a carbonate polyol and 2 to 30 parts by weight of an ester polyol relative to the carbonate polyol.

In addition, the skin layer is composed of a plurality of layers including a second skin layer provided on a non-solvent type urethane adhesive layer, and a first skin layer provided on the second skin layer, and the second skin layer may include inorganic hollow spheres having a particle diameter of 10 to 50 ㎛ and a density of 0.25 to 0.6 g/cm3.

Next, the crash pad according to one aspect includes a crash pad cover made of artificial leather, and the artificial leather includes: a fiber substrate layer made of high-density ultra-fine fiber nonwoven fabric; a solvent-free urethane adhesive layer provided on the fiber substrate layer and having micropores by inorganic hollow spheres; and a skin layer provided on the solvent-free urethane adhesive layer and including a polyurethane resin manufactured by reacting a polyol compound, a chain extender, and a polyisocyanate compound.

In addition, the artificial leather may further include a surface treatment layer formed by bonding to the skin layer and coating a urethane surface treatment compound.

According to the artificial leather for a crash pad according to one aspect and the crash pad including the same, the following effects can be expected.

First, it can improve the durability performance of vehicle interior materials, especially crash pad covering materials, such as high light resistance, heat aging resistance, chemical resistance, and hydrolysis resistance.

In addition, by utilizing a 100% solid solvent-free urethane adhesive in the adhesive layer, the residual amount of volatile organic compounds (VOC) can be reduced.

In addition, by utilizing inorganic hollow spheres capable of absorbing and dissipating solar heat, surface heat damage can be reduced, and a similar sensibility, such as volume and touch, of natural leather can be exhibited, while at the same time, molding processability, such as wrinkle resistance, can be improved.

Figure 1 is a cross-sectional view showing a cut surface of artificial leather according to one embodiment.
Figure 2 is a drawing of a cross-section of artificial leather manufactured according to Example 1 observed using a scanning electron microscope (SEM).
FIG. 3 is a drawing illustrating a crash pad manufactured using artificial leather manufactured in an embodiment of the present invention.
Figure 4 is a drawing of a cross-section of a conventional artificial leather manufactured in Comparative Example 1 of the present invention observed using a scanning electron microscope (SEM).

Like reference numerals refer to like elements throughout the specification. This specification does not describe all elements of the embodiments, and general information within the technical field to which the present invention pertains or information that is redundant between the embodiments is omitted.

Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

The terms first, second, etc. are used to distinguish one component from another, and the components are not limited by the aforementioned terms.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

The identification codes in each step are used for convenience of explanation and do not describe the order of each step. Each step may be performed in a different order than specified unless the context clearly indicates a specific order.

The operating principle and embodiments of the present invention will be described with reference to the attached drawings below.

The present invention relates to artificial leather having high durability and environmental friendliness for a crash pad cover and a crash pad utilizing the same.

Referring to FIG. 1, an artificial leather according to one embodiment includes a fiber substrate layer made of a high-density ultra-fine fiber nonwoven fabric, a solvent-free urethane adhesive layer provided on top of the fiber substrate layer, and a skin layer provided on top of the solvent-free urethane adhesive layer. According to an embodiment, a surface treatment layer may be provided on top of the skin layer.

The synthetic leather's solvent-free urethane adhesive layer, skin layer, and surface treatment layer are made of polyurethane resin. This polyurethane resin can be produced by polymerizing a polyol compound including an aliphatic or alicyclic polyisocyanate compound, a carbonate polyol, and an ester polyol.

Polyurethane consists of two phases within the polymer, namely, a hard segment (HS) and a soft segment (SS), and the hard segment, which forms a crystalline structure through physical bonding, exists in a form in which it is dispersed in the soft segment domain. The properties and rigidity of polyurethane vary not only by the cohesion of the hard segment but also by the type of soft segment. Depending on the type of polyol used as the soft segment, the mechanical properties, thermal properties, hydrolysis resistance, and chemical resistance vary.

The artificial leather according to the published invention has a newly designed polyol composition of a polyurethane resin forming a solvent-free urethane adhesive layer, a skin layer, and a surface treatment layer, thereby implementing properties suitable for a crash pad cover. Specifically, it simultaneously improves high durability performances such as high light resistance, heat aging resistance, chemical resistance, and hydrolysis resistance suitable for a crash pad cover, while reducing the residual amount of volatile organic compounds (VOC).

Hereinafter, each layer constituting the artificial leather according to the published invention will be described in more detail.

First, the fiber base layer is applied to realize a feeling similar to natural leather. The fiber base layer is provided with a long-fiber type high-density ultra-fine non-woven fiber base material to realize a feeling of filling and formability in the crash pad cover.

Long-fiber high-density ultra-fine fiber nonwoven fabric has higher strength and density and superior quality than conventional short-fiber high-density nonwoven fabric, making it a suitable material for use as a textile base material for vehicle interior materials such as crash pads.

The long-fiber high-density ultra-fine fiber nonwoven fabric can be manufactured by two or more composite processes selected from spunbond, needle punching, and spunlace methods.

The long-fiber high-density ultra-fine nonwoven fabric can have a density characteristic of 0.3 g/cm3 or more, preferably 0.3 to 0.6 g/cm3, more preferably 0.4 to 0.5 g/cm3. Accordingly, there is an advantage in that high density can be achieved without a separate shrinkage process, a separate impregnation process can be omitted, and impregnation processing can be performed using a low-concentration polyurethane resin compound.

Below, to aid understanding, a method for manufacturing a long-fiber, high-density nonwoven fabric is described.

For the production of a long-fiber type high-density ultra-fine nonwoven fabric, at least one general-purpose filament yarn selected from the group consisting of polyethylene terephthalate (PET) and polyamide (PA) can be used, and according to an embodiment, a sea-island type or split filament yarn including at least one selected from the group consisting of PET/PA (polyethylene terephthalate/polyamide), PET/PLA (polyethylene terephthalate/polylactic acid), PET/Co-PET (polyethylene terephthalate/co-polyethylene terephthalate), and PA/Co-PET (polyamide/co-polyethylene terephthalate) can be used.

Hereinafter, for convenience of explanation, a method for manufacturing a long-fiber high-density nonwoven fabric using a filament yarn will be described.

A long-fiber high-density ultra-fine nonwoven fabric can be manufactured by a composite spinning method using a high-molecular-weight thermoplastic resin and a low-molecular-weight resin. At this time, in order to manufacture a nonwoven fabric with excellent quality, a spinning speed in the range of 3,000 to 7,000 m/min, preferably in the range of 4,000 to 5,000 m/min, can be applied.

A process for manufacturing a long-fiber high-density nonwoven fabric may include a step of forming a web by a spunbond method using a sea-island filament yarn; a step of performing cold calendaring of the web; a step of laminating and stretching the cold-calendered web, performing a needle punching process, and performing water bonding to manufacture a high-density nonwoven fabric; and a step of providing the manufactured high-density nonwoven fabric to a microfine process in a sodium hydroxide (NaOH) aqueous solution having a concentration ranging from 2 to 10%.

First, a process of forming a web using a spunbond method using a sea-type filament yarn can be performed.

The type of sea-island filament yarn used in this step may be one having an average fineness of 2.0 to 5.0 denier, preferably 2.5 to 3.8 denier.

Specifically, a sea-island filament yarn can be used that includes at least one thermoplastic resin selected from the group consisting of polyamide (PA), polyethylene terephthalate (PET), and polytrimethylene terephthalate (PTT) as a main component, and at least one selected from the group consisting of low-molecular-weight polyethylene terephthalate copolymer (co-PET) and polylactic acid (PLA) as a marine component.

When the sea-type filament yarn is prepared, the island component is mixed at a weight ratio of 60 to 80% and the sea component is mixed at a weight ratio of 20 to 40% and spun at a high speed (3000 to 7000 m/min) to form a web (30-50 g/cm2) using the spunbond method.

Next, the cold calendaring process of the web can be performed.

In this step, a cold calendaring method was applied to treat the surface without applying heat to ensure the shape stability of the web.

Next, a step is performed to laminate and stretch the web that has undergone cold calendaring, then perform a needle punching process and hydraulic bonding to manufacture a high-density nonwoven fabric.

In this step, the web is cross-lapped and drafted according to the required weight (300-600 g/cm2) for high weight, and then treated with PPSC (penetrations per square centimeter) of 100 to 800 ea/cm2 by needle punching and then water-bonded to produce a high-density nonwoven fabric.

Next, the manufactured high-density nonwoven fabric can be subjected to a microfine process in a sodium hydroxide (NaOH) aqueous solution having a concentration of 2% to 10% for 5 to 30 minutes, preferably 5 to 10 minutes, to manufacture a long-fiber type high-density microfine nonwoven fabric fiber base material.

The fiber substrate layer may be provided with a thickness of 0.7 to 1.3 mm, preferably 0.8 to 1.1 mm, but the thickness of the fiber substrate layer is not limited thereto.

Next, the solvent-free urethane adhesive layer can function as an adhesive for bonding the skin layer and the fiber substrate layer. The solvent-free urethane adhesive layer is provided in a form in which inorganic hollow spheres are uniformly distributed in the polyurethane resin and form pores. In the present invention, by using a 100% solid solvent-free urethane resin having micropores by inorganic hollow spheres, the residual amount of volatile organic compounds (VOCs) is reduced. In addition, by forming micropores using inorganic hollow spheres, the touch and volume of the artificial leather are increased, and the molding processability such as wrinkle resistance is improved while minimizing heat damage to the surface by absorbing solar heat.

The solventless urethane resin can be provided using a hydroxyl-terminated urethane prepolymer, an isocyanate-based crosslinking agent, and a urethane conversion catalyst as materials. Specifically, the solventless urethane resin can be coated by mixing a hydroxyl-terminated urethane prepolymer as a main component and an isocyanate-based crosslinking agent as an isocyanate-based compound at a constant component ratio at high speed and discharging the mixture to form a reaction solution, and according to an embodiment, a urethane conversion catalyst can be used to promote the coating reaction.

Below, the components used to provide a non-solvent type urethane resin are described in detail.

First, a hydroxyl-terminated urethane prepolymer of a non-solvent type urethane resin can be prepared by polymerizing a resin including a polyol compound, a chain extender, and a polyisocyanate compound.

The hydroxyl-terminated urethane prepolymer is a 100% solids reaction product that exists in a crystallized solid form at room temperature through the addition reaction of a polyol compound and a polyisocyanate, but can be melted below 60°C, and is designed to exhibit an appropriate viscosity while forming a rigid urethane bond and improving production stability and reproducibility.

The hydroxyl group-terminated urethane prepolymer is preferably one having a melt viscosity of 2000 to 8000 cps, preferably 3500 to 6500 cps at 60°C.

If the melting viscosity at 60℃ is less than 2000 cps, it is difficult to control the thickness uniformly, and the crosslinking and curing reactions are too slow, which deteriorates the overall physical properties, so it is not desirable. On the other hand, if it exceeds 8000 cps, there is a limit to uniform mixing in a high-speed reaction molding machine, and production stability deteriorates.

It is efficient to melt and react the hydroxyl-terminated urethane prepolymer at 60°C or lower, taking into account production stability, production efficiency, gelation time, and reactivity.

If the melting temperature of the hydroxyl-terminated urethane prepolymer is too high, it takes a long time to melt, and due to the high temperature of the urethane reaction solution, crosslinking and curing reactions occur rapidly during the coating process, shortening the gelation time. As a result, there is a problem that uniform coating is difficult and an uneven urethane adhesive layer is formed, thereby reducing product uniformity. Therefore, the published invention utilizes a solvent-free urethane adhesive that can exhibit rigidity and strong cohesion while having a suitable melting temperature and viscosity by adjusting the reaction ratio of crystalline polyol and other polyols.

Hereinafter, the components and content ratios of the polyol compound, chain extender, and polyisocyanate compound that are materials of the hydroxyl group-terminated urethane prepolymer will be described in more detail.

The polyol compound can be provided in a mixed form of 65 to 80 parts by weight of a carbonate polyol having a molecular weight of 500 to 3000 and having two or more functional groups, 12 to 30 parts by weight of an ether polyol having a molecular weight of 500 to 3000, and 2 to 10 parts by weight of an ester polyol having a molecular weight of 1000 to 3000 and having a solidification temperature of 20 to 50°C.

Here, the carbonate polyol can be synthesized by a transesterification reaction and a condensation reaction of a hydroxy compound including at least one selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and cyclohexane diol and at least one ester compound selected from the group consisting of alkylene carbonate, diaryl carbonate, and dialkyl carbonate. A polyurethane synthesized by utilizing the carbonate polyol synthesized in this manner exhibits excellent properties in terms of chemical resistance, hydrolysis resistance, weather resistance, and heat resistance.

In addition, ester polyols can be synthesized by a polycondensation reaction between diols such as ethylene glycol, 1,4-butanediol, and 1,6-hexanediol and adipic acid (AA), sebaic acid (SA), and terephthalic acid. Polyurethane synthesized using ester polyols synthesized in this manner exhibits excellent characteristics in terms of mechanical properties, adhesive strength, dimensional stability, and flexibility.

Next, a low molecular weight polyol can be used as a chain extender. For example, at least one material selected from the group consisting of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and dipropylene glycol can be used as a chain extender. In addition, in order to design a rigid urethane structure by increasing the degree of crosslinking curing, a multifunctional low molecular weight polyol having a molecular weight of 500 or less and a functional group of 3 or more can be used in combination.

Next, as the polyisocyanate compound, at least one selected from the group including 4,4-diphenylmethane diisocyanate (DMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H12MDI), and xylene diisocyanate (XDI) can be used.

Meanwhile, the inorganic hollow spheres can be formed in a weight ratio of 5 to 20, preferably 8 to 10, relative to the total weight of the hydroxyl-terminated urethane prepolymer.

If the amount of inorganic hollow spheres used is less than 5 weight ratio, sufficient pores may not be formed in the solvent-free urethane adhesive layer, and if the amount of inorganic hollow spheres used is more than 20 weight ratio, excessive pores may occur, resulting in reduced adhesion. Therefore, it is desirable to appropriately control the amount of inorganic hollow spheres used.

Inorganic hollow spheres can be formed with a core portion made of a gas such as pentane and a cell portion made of an inorganic material such as silica, ceramic, or glass. In addition, the inorganic hollow spheres can be formed with a particle diameter of 60 to 120 ㎛ and a density in the range of 0.1 to 0.3 g/cm3.

Next, as an isocyanate-based crosslinking agent of the non-solvent urethane resin, at least one selected from the group including an isocyanate-terminated prepolymer capable of reacting with active hydrogen of a hydroxyl group in a molecular structure as a reactant of a low molecular weight polyol and an isocyanate, a carbodiimide-modified MDI, a biuret-type HDI, and an isocyanurate-type HDI can be used.

The isocyanate crosslinking agent can be used in an amount ranging from 1.05 to 2.5 equivalents per 1 equivalent of the hydroxyl-terminated urethane prepolymer.

If the amount of isocyanate crosslinking agent used is less than 1.05 equivalents per 1 equivalent of urethane prepolymer, the degree of crosslinking and curing may be insufficient, which may result in deterioration of adhesive strength and other physical properties. If it is 2.5 equivalents or more, a large amount of unreacted isocyanate crosslinking agent residue may remain, which may result in deterioration of hydrolysis resistance, chemical resistance, and adhesive strength, and may result in problems such as reduced product uniformity.

Next, as a urethane conversion catalyst of the solvent-free urethane resin, at least one selected from the group consisting of triethylamine, bis(dimethylamino ether), N,N-dimet methylcyclohexylamine, Tris-dimethyl amino propyl amine, n-butyl tin diacetate, 1,8-diazabicyclo(5,4,0)undec-7-ene (DBU), and DBU-octylate can be used.

The solvent-free urethane adhesive layer can be provided with a thickness in the range of 100 to 450 ㎛, but the thickness of the solvent-free urethane adhesive layer is not limited thereto.

The skin layer may be provided in a single or multiple layers. When the skin layer is provided in multiple layers, wear resistance, friction resistance, and color resistance according to the surface pattern can be supplemented. For example, the skin layer may include a second skin layer provided on a solvent-free urethane adhesive layer, and a first skin layer provided on the second skin layer. In Fig. 1, for convenience of explanation, the skin layer includes the first skin layer and the second skin layer as an example, but the formation example of the skin layer is not limited thereto, and it goes without saying that the skin layer may be provided in three or more layers.

The second skin layer may include inorganic hollow spheres similarly to the non-solvent urethane adhesive layer described above. For example, the second skin layer may have micropores formed by inorganic hollow spheres having a particle diameter of 10 to 50 ㎛ and a density of 0.25 to 0.6 g/cm3, thereby providing the skin layer with improved heat-resistant aging performance.

Below, to help you understand, we will explain how to manufacture the skin layer.

The skin layer may be formed of a polyurethane resin manufactured by reacting a polyisocyanate compound, a polyol compound, and an amine chain extender. For example, the polyurethane resin may be manufactured by reacting a polyurethane prepolymer obtained by polymerizing a polyisocyanate compound and a polyol compound including a carbonate polyol and an ester polyol, with a chain extender.

As the type of polyisocyanate compound, at least one selected from the group consisting of hexamethylene diisocyanate (HDI), propylene diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate (IPDI), and 4,4-dicyclohexylmethane diisocyanate (H ₁₂ MDI) can be used, and preferably at least one selected from the group consisting of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and 4,4-dicyclohexylmethane diisocyanate (H ₁₂ MDI) can be used.

As types of polyol compounds, carbonate-based polyols having a weight average molecular weight in the range of 1,000 to 3,500 and ester-based polyols having a weight average molecular weight in the range of 1,000 to 3,000 can be used.

If the molecular weight of the polyol compound is too low, the modulus of the skin layer increases and the elongation decreases, resulting in poor surface feel and hardening of the product. On the other hand, if the molecular weight of the polyol compound is too high, a soft skin layer can be realized, but stickiness may occur on the surface and mechanical properties may deteriorate. Therefore, it is desirable to appropriately control the molecular weight of the polyol compound.

In addition, the carbonate polyol and ester polyol included in the polyol compound may be included so that the mixing ratio of the carbonate polyol to the ester polyol has a weight ratio of 100 to 2 to 30, preferably a weight ratio of 100 to 7 to 20. When the weight ratio of the polyol compound components is within the above-mentioned ratio range, excellent light resistance, hydrolysis resistance, and heat aging resistance can be secured.

As a polyol compound, a carbonate polyol may be used, which is synthesized by a known synthetic method, such as a condensation reaction of at least one dihydroxyl compound selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexane diol, and 1,4-cyclohexane dimethanol, with a diaryl carbonate, a dialkyl carbonate, or phosgene. A polyurethane manufactured using such a carbonate polyol is excellent in terms of hydrolysis resistance, weather resistance, and heat resistance.

As a polyol compound, the ester polyol may be an aliphatic polyester polyol obtained by esterification reaction of a low molecular weight polyol such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and the like with a polycarboxylic acid such as adipic acid (AA), and according to an embodiment, the ester polyol may be a polyester polyol obtained by ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone.

The chain extender may be at least one of an aliphatic amine chain extender and an alicyclic amine chain extender. For example, at least one selected from the group consisting of hexamethylene diamine, dicyclohexylamine, and isophoronediamine may be used, but the types of chain extenders that can be used are not limited thereto.

The surface treatment layer is provided for the purpose of adjusting the glossiness of the skin layer surface, matching the color, and improving functions such as light resistance and stain resistance.

The surface treatment layer can be manufactured using a non-yellowing polyurethane resin as a main raw material. Specifically, it can be formed by coating a urethane surface treatment coating solution containing a non-yellowing polyurethane resin, a gloss remover, an antifouling additive, and a solvent on the surface of the skin layer.

The non-yellowing polyurethane resin can be produced by reacting a polyurethane prepolymer prepared by polymerizing a polyisocyanate compound and a polyol compound including a carbonate polyol having a weight average molecular weight of 1,000 to 3,500 and an ester polyol having a weight average molecular weight of 1,000 to 3,000, with a chain extender. The produced non-yellowing polyurethane resin can have a solid content of 15 to 40 wt%.

As a type of polyisocyanate compound, one type selected from the group including hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and 4,4-dicyclohexylmethane diisocyanate (H12MDI) may be used alone or in combination of two or more types, preferably, two types may be used in a weight ratio of 1 to 0.5 to 1 to 1.5.

At least one selected from hexamethylene diamine, dicyclohexylamine, and isophorone diamine can be used as a chain extender to improve heat resistance, hydrolysis resistance, and chemical resistance.

As a type of polish remover, at least one selected from the group including organic fine powder and inorganic fine powder can be used.

Here, the organic fine powder may include at least one selected from the group consisting of acrylic resin particles, styrene resin particles, styrene-acrylic resin particles, phenol resin particles, melamine resin particles, acrylic-polyurethane resin particles, polyester resin particles, nylon resin particles, silicone resin particles, polyethylene resin particles, and urethane beads.

Additionally, the inorganic fine powder may include at least one selected from the group consisting of talc, mica, calcium carbonate, magnesium carbonate, alumina, silica, carbon black, titanium oxide, magnesium hydroxide, bentonite, and graphite.

In this specification, the term fine powder means powder having an average particle size of 10 ㎛ or less. If the average particle size of the fine powder exceeds 10 ㎛, scratch resistance may be reduced during the process of forming a thin film coating on the surface of the product, and problems may occur with the appearance of the product.

The gloss remover may be included in an amount of 5 to 20 parts by weight, preferably 10 to 18 parts by weight, per 100 parts by weight of the non-yellowing polyurethane resin.

If the content of the gloss remover is too low, the effect of quenching the gloss may not be sufficient. On the other hand, if the content of the gloss remover is too high, the properties of the artificial leather may deteriorate. Therefore, it is desirable to appropriately adjust the content of the gloss remover within the above-mentioned range.

Hydroxy silicone polyacrylate can be used as a type of antifouling additive.

Hydroxy silicone polyacrylate may be included in an amount of 2 to 10 parts by weight, preferably 3 to 8 parts by weight, per 100 parts by weight of the non-yellowing polyurethane resin.

As the type of solvent, at least one selected from the group consisting of dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), N-ethylpyrrolidone, dimethyl sulfoxide (DMSO), ethyl acetate, methyl ethyl ketone, and alcohol may be used, and preferably, one selected from the group consisting of dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), ethyl acetate, methyl ethyl ketone, and isopropyl alcohol may be used alone or in combination of two or more. More preferably, two or more types may be used in combination, and for example, dimethylformamide, methyl ethyl ketone, and isopropyl alcohol may be mixed in a weight ratio of 50 to 15 to 25 to 25 to 35.

The solvent may be included in an amount of 70 to 200 parts by weight, preferably 90 to 150 parts by weight, per 100 parts by weight of the non-yellowing polyurethane resin.

If the amount of solvent used is less than 70 parts by weight, the film-forming properties and frictional colorability may deteriorate. On the other hand, if it exceeds 200 parts by weight, there is a concern that the film formation after drying may be incomplete, and problems such as residues of organic solvent in the film may occur. Therefore, it is desirable to appropriately adjust the solvent content within the above-mentioned range.

Above, the structure of artificial leather and the components forming each layer of artificial leather were explained.

The method for manufacturing artificial leather of the present invention described above is as follows.

A method for manufacturing artificial leather according to one embodiment comprises the steps of forming a skin layer by coating a polyurethane resin for skin on a release paper having various patterns formed thereon, the step of forming a solvent-free urethane adhesive layer on the skin layer, the step of laminating the skin layer and a textile substrate while maintaining the solvent-free urethane adhesive layer in an appropriate adhesive state, and the step of post-curing the laminated product, peeling the release paper from the skin layer, and forming a surface treatment layer.

The coating for forming each layer by the method for manufacturing such artificial leather can be performed by at least one of the knife method, the gravure method, the reverse gravure method, and the spray coating method, and there is no special limitation.

Any explanation that overlaps with the description of the structure of artificial leather described above in relation to the manufacturing process of artificial leather will be omitted.

Next, preferred embodiments of the published invention are described. The following embodiments are described only for the purpose of expressing the invention more clearly, and the scope of the invention is not limited by the following embodiments.

[Preparation Example 1]: For skin layer polyurethane resin

100 parts by weight of carbonate polyol having a weight average molecular weight of 2,000 (T-6002, manufactured by Asahi Kasei), 8 parts by weight of ester polyol having a weight average molecular weight of 2,000 (K-340 (EG/1.4BD/AA), manufactured by Dongsung Chemical), and 110 parts by weight of dimethylformamide (DMF) solvent were each charged into a reaction tank in the first stage and stirred for 1 hour while maintaining the temperature at 50 ℃. Then, dicyclohexylmethane-4,4-diisocyanate (H12MDI) was charged in 2 to 3 portions to prevent a rapid reaction. The polyol and diisocyanate were reacted for 2 hours. Isophorondiamine (IPDA) was charged in the third stage while maintaining the temperature at 70 to 80 ℃ and reacted. When the appropriate viscosity is reached, 1 part by weight of methanol as a blocking agent is added to the reactant at a temperature of 75°C or lower, and 100 parts by weight of dimethylformamide (DMF) and 60 parts by weight of methyl ethyl ketone (MEK) are added as solvents to mask the NCO group. - After confirming that there is no NCO group, the reaction is terminated, thereby obtaining a resin for skin coating.

Next, 15 parts by weight of dimethylformamide, 30 parts by weight of methyl ethyl ketone, and 15 parts by weight of color-developing toner were mixed with 100 parts by weight of a resin for skin coating, and then mixed with a stirrer for about 30 minutes to prepare a skin coating solution-1.

Next, 10 parts by weight of inorganic hollow spheres having a diameter of 20 to 60 ㎛ and a density of 0.35 to 0.6 g/cm ³ were mixed into skin coating solution-1 to prepare skin coating solution-2.

[Preparation Example 2]: Dance form Hydroxyl-terminated urethane for urethane resin Prepolymer

120 kg of carbonate polyol having a number average molecular weight of 2,000, 32 kg of crystalline ester polyol having a number average molecular weight of 2,000, and 8 kg of 1,4 butanediol were placed in a reactor and uniformly mixed at 70 to 80°C for 30 minutes. Considering the exothermic reaction, the mixture was cooled to about 65°C, and 8 kg of 4,4-diphenylmethane diisocyanate (MDI) was added to the mixture. Subsequently, after reacting for about 3 hours, 18 kg of inorganic hollow spheres were added to obtain a hydroxyl-terminated urethane prepolymer.

[Preparation Example 3]: Long fiber type High density Ultrafine yarn Nonwoven fiber substrate

A web having a basis weight of 38 to 40 g/cm ² was manufactured by a spunbond process using filament yarns of 3.0 denier and sea-island type (PET/Co-PET, 70/30, 25 islands), then cold calendaring was performed, and the calendared web was laminated and stretched into multiple layers, and then a needle punching process was performed at 330 to 350 ea/cm ² , and then water bonded to manufacture a nonwoven fabric having a width of 1950 mm, an average weight of 300 g/m ³ , and an average thickness of 0.83 mm.

Next, a long-fiber, high-density, ultra-fine nonwoven fiber base material was manufactured through a microfine process in a 3% sodium hydroxide (NaOH) aqueous solution for 30 minutes, and the results are shown in [Table 1] below.

division Extreme detail jeon after Weight (g/m ² ) 300 240 Thickness (mm) 0.83 0.65 Apparent density (g/cm ³ ) 0.36 0.37 tensile strength
(kgf/inch) MD 28.8 25.1 CD 33.7 29.8 Believers (%) MD 75.7 108.6 CD 97 129.1 Tear strength (kgf) MD 4.5 4.3 CD 3.5 3.5 MD: machine direction (vertical direction)

Referring to [Table 1], it was confirmed that the long-fiber nonwoven fabric had a very high apparent density and exhibited high-density characteristics without going through a separate shrinkage process.

In the case of long-fiber nonwoven fabrics, since the fibers have a property of returning to their original shape, even if heat or physical force is applied in a subsequent process such as ultrafine processing, the density after ultrafine processing tends to be similar to that before ultrafine processing, so it was possible to manufacture a stable long-fiber high-density ultrafine nonwoven fabric fiber base material.

[Preparation Example 4]: Urethane surface treatment coating solution

A polyol mixture containing 100 parts by weight of carbonate polyol having a weight average molecular weight of 2,000 and 12 parts by weight of ester polyol having a weight average molecular weight of 2,000 as main raw materials and 100 parts by weight of dimethylformamide (DMF) solvent were first introduced into a reaction vessel, stirred for 1 hour while maintaining a temperature of 50°C, and then isophorone diisocyanate (IPDI) was introduced in 2 to 3 portions to prevent a rapid reaction. The polyol and diisocyanate were reacted for 2 hours. Thirdly, 5 parts by weight of cyclohexyldiamine were added. The viscosity was increased by adding the solution while maintaining the temperature at 80℃ to prevent overheating due to the temperature rise caused by the reaction heat.

When the appropriate viscosity was reached, 1 part by weight of methanol as a blocking agent was added while maintaining the temperature of the reactant below 75 ℃, and 100 parts by weight of dimethylformamide (DMF), 60 parts by weight of methyl ethyl ketone (MEK), and 60 parts by weight of isopropyl alcohol (IPA) were added as solvents to mask the NCO group. -The reaction was terminated after confirming that there was no -NCO group. At this time, 0.3 parts by weight of an anti-yellowing agent and an antioxidant were each added during the reaction process to synthesize a polyurethane for surface treatment.

Next, dimethylformamide (DMF)/methyl ethyl ketone (MEK)/isopropyl alcohol (IPA) solvents were added at a weight ratio of 50/20/30 to 100 parts by weight of the polyurethane resin, stirred at low speed for 2 hours at room temperature, and a surface treatment coating solution containing 15 wt% of solids was prepared.

Next, 6 parts by weight of hydroxy silicone modified polyacrylate, a reactive additive, was added to 100 parts by weight of the surface treatment coating solution and stirred for about 1 hour. Then, 0.2 parts by weight of an anti-foaming agent, 0.5 parts by weight of an antioxidant, and 0.15 parts by weight of an anti-yellowing agent were added and stirred.

Next, 0.5 parts by weight of silica and 1.0 parts by weight of urethane beads were sequentially added to the surface treatment coating solution and stirred to mix.

Next, 15 parts by weight of melamine resin particles were added to the surface treatment coating solution and stirred at low speed for about 20 minutes, and then 20 parts by weight of p-toluene sulfonic acid, a reaction accelerator, was added and mixed to prepare a urethane surface treatment coating solution.

[Example 1]: Manufacturing of artificial leather

The skin coating solution-1 manufactured in [Preparation Example 1] was applied to a release paper with a thickness of 40 ㎛ after drying, pre-dried at about 80 to 90°C for 1 minute, and then dried at 120 to 130°C for 3 minutes to form a first skin layer film. The skin coating solution-2 containing the inorganic hollow spheres manufactured in [Preparation Example 1] was applied to a thickness of 40 ㎛ on the first skin layer and dried to form a second skin layer.

[Preparation Example 2] 100 parts by weight of the urethane prepolymer was heated and melted at 60°C, and then maintained at 60°C in a thermostable container. Next, a mixture of 23 parts of an isocyanate crosslinking agent and 0.5 parts of a curing catalyst Polycat-8 was mixed in a high-speed stirrer at a stirring speed of 3,000 rpm for 2 seconds to obtain a reaction mixture of a solvent-free urethane adhesive, and the reaction mixture was discharged on a release paper having a surface film layer formed thereon to a thickness of 350 μm and dried. It was heated and dried at a temperature gradient of 110 to 135°C for about 3 minutes to maintain an appropriate adhesive state, and then combined with the high-density ultra-fine nonwoven fiber substrate manufactured in [Preparation Example 3]. After bonding, the post-curing was performed at about 80°C for 24 hours, the release paper was peeled off, and the urethane surface treatment coating solution of [Preparation Example 4] was coated using the gravure coating method to manufacture an artificial leather product for vehicle interior materials. A photograph of the cross-section of the manufactured artificial leather observed using a scanning electron microscope (SEM) is shown in Fig. 2, and a crash pad to which the manufactured artificial leather was applied is illustrated in Fig. 3.

[Comparative Example 1]: Manufacturing of artificial leather

An aqueous urethane resin composition for skin coating was applied to a 40 ㎛ thickness on a release paper after drying, pre-dried at about 80 to 90°C for 1 minute, and then dried at 130 to 140°C for 5 minutes to form a first skin surface layer film. An aqueous urethane composition for skin coating was applied to a 40 ㎛ thickness on the first skin surface layer and dried to form a second skin surface layer.

After drying the water-dispersed polyurethane adhesive on the upper part of the dry skin surface layer, an adhesive layer with a thickness of 120 ㎛ was formed, and then heat was applied at 110 to 120°C to harden it, and while maintaining an appropriate adhesive state, the high-density nonwoven fabric prepared in [Preparation Example 3] was laminated, and after maturing for 48 hours while maintaining a temperature of 80°C, the release paper was peeled off to manufacture artificial leather. A photograph of the cross-section of the manufactured artificial leather observed using a scanning electron microscope (SEM) is shown in Fig. 4.

[Comparative Example 2]: Manufacturing of artificial leather

[Preparation Example 1] The skin coating solution-1 manufactured in the above was applied to a release paper with a thickness of 40 ㎛ after drying, pre-dried at about 80℃ for 1 minute, and then dried at 110 to 130℃ for 3 minutes to form a first skin surface layer film. The skin coating solution-1 was applied to a thickness of 40 ㎛ on the first skin surface layer and dried to form a second skin surface layer.

After drying an organic solvent-type urethane adhesive on the upper part of the dry skin surface layer, an adhesive layer was formed with a thickness of 120 ㎛, and then heat was applied at 110 to 120°C to maintain an appropriate adhesive state, and the high-density nonwoven fabric prepared in [Preparation Example 3] was laminated, and after maturing for 48 hours while maintaining a temperature of 80°C, the release paper was peeled off to manufacture artificial leather.

The properties of artificial leather manufactured in [Example 1], [Comparative Example 1], and [Comparative Example 2] were measured using the methods below, and the results are shown in [Table 2] below.

Light resistance

After irradiating with 126 MJ/ ^m2 at a temperature of 90℃ and an internal humidity of 50% RH on a black panel using a tester specified in ISO 105, the difference in color fading by the naked eye was judged using the gray scale specified in ISO 105-A02 to obtain a grade.

Heat aging resistance

After keeping the sheets in a hot air circulation oven maintained at 140℃ for 96 hours, the difference in fading by visual inspection was judged using the gray scale specified in ISO 105-A02 to obtain a grade.

Friction coloration

The specimen was fixed to a friction tester (friction tester type Ⅱ for color fastness of JIS L 0823) test stand, and the friction element of the tester was covered and fixed with a cotton cloth. After moving the surface of the specimen back and forth 100 times with a load of 4.9 N (500 gf), a reciprocating speed of 30 times/min, and a moving distance of 100 mm, the degree of contamination of the cotton cloth was judged by a contamination gray scale (JIS L 0805 contamination gray scale) to obtain a grade. In addition, the cotton cloth was immersed in artificial sweat for 10 minutes, lightly squeezed, and a friction test was performed to determine the grade. The artificial sweat was prepared by mixing 8 g of Class 1 or higher of JIS K 9019 (sodium phosphate tetrahydrate), 8 g of Class 1 or higher of JIS K 8150 (sodium chloride), and 5 g of Class 1 or higher of JIS K 8355 (glacial acetic acid) in pure water to make a volume of 1 L. (pH 4.5)

My drug resistance

The surface was wiped with gauze soaked in a sufficient amount of test solution (weakly alkaline glass cleaner, mixture of 95% distilled water and 5% neutral detergent, mixture of 50% isopropyl alcohol and 50% distilled water, unleaded gasoline) in a back and forth motion 10 times, and then left at room temperature for 1 hour. The difference in discoloration by the naked eye was judged using the gray scale specified in ISO 105-A02 to obtain a grade.

Emotion

The softness, such as volume and touch, was evaluated using a test method based on EN ISO 17235.

division Comparative Example 1 Comparison Example 2 Example 1 Light fastness 3rd grade Grade 4 Grade 4 Dry/wet friction colorability 3rd grade Grade 4 Grade 4 My drug resistance 3rd grade Grade 4 Grade 4 Heat aging resistance 3.5 grade Grade 4 Grade 4 or higher Wrinkle Bad commonly Good VOC residual amount 3 ppm or less 35 ppm or more 5 ppm or less Touch, Formability △ ○ ◎ △: After commercialization, the texture and formability are poor.
○: After commercialization, the texture and formability are average.
◎: Excellent texture and moldability after commercialization

Referring to [Table 2], the artificial leather according to [Example 1] of the present invention exhibits superior characteristics in terms of light resistance, chemical resistance, heat aging resistance, friction discoloration, wrinkle resistance, and touch compared to the artificial leather according to [Comparative Example 1]. Compared to the artificial leather according to [Comparative Example 2], it exhibits superior characteristics in terms of touch, moldability, heat aging resistance, and residual volatile organic compounds (VOC), and shows a tendency similar to the texture of natural leather.

Although the preferred embodiments of the artificial leather of the present invention have been described above, the scope of the present invention is not limited to the embodiments described above and the claims below, and various modifications and equivalent embodiments are possible from the present invention by those skilled in the art.

101: Textile base layer
102: Non-solvent type urethane adhesive layer
103: Skin layer
103a: 1st skin layer
103b: 2nd skin layer
104: Surface treatment layer

Claims (15)

A textile base layer made of high-density ultra-fine non-woven fabric;
A solvent-free urethane adhesive layer provided on the above-mentioned fiber substrate layer and having micropores by inorganic hollow spheres; and
It includes a skin layer formed on the non-solvent type urethane adhesive layer and made of a polyurethane resin manufactured by reacting a polyol compound, a polyisocyanate compound, and a chain extender;
The above-mentioned non-solvent type urethane adhesive layer is an artificial leather for a crash pad having micropores formed by inorganic hollow spheres having a particle diameter of 50 to 120 ㎛ and a density of 0.1 to 0.3 g/cm ³ . In paragraph 1,
Artificial leather for a crash pad further comprising a surface treatment layer formed by bonding to the above skin layer and coating a urethane surface treatment coating solution. In paragraph 1,
Artificial leather for a crash pad, wherein the above high-density ultra-fine fiber non-woven fabric has a density of 0.2 to 0.6 g/cm3. In paragraph 1,
The above high-density ultra-fine fiber non-woven fabric is
Containing as a main component at least one thermoplastic resin selected from the group consisting of polyamide (PA), polyethylene terephthalate (PET), and polytrimethylene terephthalate (PTT).
An artificial leather for a crash pad comprising a sea-island type fiber comprising at least one selected from the group consisting of a low molecular weight polyethylene terephthalate copolymer (co-PET) and polylactic acid (PLA) as a sea component. In paragraph 1,
The above high-density ultra-fine fiber non-woven fabric is
An artificial leather for a crash pad, comprising a step of performing a microfine processing on a high-density nonwoven fabric in a sodium hydroxide (NaOH) aqueous solution having a concentration of 2 to 10% for 5 to 30 minutes. In paragraph 1,
The above-mentioned non-solvent type urethane adhesive layer is,
A hydroxyl-terminated urethane prepolymer polymerized with a resin containing a polyol compound, a chain extender and a polyisocyanate compound,
10 to 40 parts by weight of a crosslinking agent relative to the above hydroxyl group-terminated urethane prepolymer,
An artificial leather for a crash pad comprising 5 to 20 parts by weight of inorganic hollow spheres blended with the hydroxyl group-terminated urethane prepolymer. In paragraph 6,
The above polyol compound is,
65 to 80 parts by weight of a carbonate polyol having a weight average molecular weight in the range of 500 to 3000,
12 to 30 parts by weight of an ether polyol having a weight average molecular weight of 500 to 3000; and
Artificial leather for a crash pad comprising 2 to 10 parts by weight of an ester polyol having a weight average molecular weight in the range of 1000 to 3000. In paragraph 6,
The above chain extender is,
Artificial leather for a crash pad comprising at least one selected from the group consisting of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and dipropylene glycol. In paragraph 6,
The above polyisocyanate compound is,
An artificial leather for a crash pad comprising at least one selected from the group consisting of 4,4-diphenylmethane diisocyanate (DMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H12MDI), and xylene diisocyanate (XDI). delete In paragraph 1,
The above-mentioned non-solvent type urethane adhesive layer is,
Artificial leather for a crash pad, characterized by having a thickness in the range of 100 to 450 ㎛. In paragraph 1,
The polyol compound of the above skin layer is
Carbonate polyols,
An artificial leather for a crash pad, characterized in that it contains 2 to 30 parts by weight of an ester polyol relative to the carbonate polyol. In paragraph 1,
The above skin layer is composed of a plurality of layers including a second skin layer provided on the non-solvent type urethane adhesive layer and a first skin layer provided on the second skin layer,
The above second skin layer,
An artificial leather for a crash pad comprising inorganic hollow spheres having a particle diameter of 10 to 50 ㎛ and a density of 0.25 to 0.6 g/cm3. Includes a crash pad cover made of artificial leather,
The above artificial leather,
A textile base layer made of high-density ultra-fine non-woven fabric;
A solvent-free urethane adhesive layer provided on the above-mentioned fiber substrate layer and having micropores by inorganic hollow spheres; and
A skin layer is provided on the non-solvent type urethane adhesive layer and includes a polyurethane resin manufactured by reacting a polyol compound, a chain extender, and a polyisocyanate compound;
The above-mentioned non-solvent type urethane adhesive layer is a crash pad having micropores formed by inorganic hollow spheres having a particle diameter of 50 to 120 ㎛ and a density of 0.1 to 0.3 g/cm ³ . In Article 14,
The above artificial leather,
A crash pad further comprising a surface treatment layer formed by bonding to the above skin layer and coating a urethane surface treatment compound.

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