JPH0483634A - Vapor-permeable and oil-repellent paper and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain vapor-permeable and oil-repellent paper having heat resistance, vapor permeability, water absorbability, water resistance, oil repellency and heat-sealing properties, and suitable for use to wrap cooked foodstuffs, frozen foodstuffs, etc., by laminating a vapor- permeable heat-sealing layer and a vapor-permeable non-heat-sealing layer to make a wet web and applying oil-repellent treatment to the resultant wet web with a fluoro-surfactant. CONSTITUTION:This vapor-permeable and oil-repellent paper is manufactured by making a wet web from a papermaking material including thermoplastic multi-branch type fibers and thermoplastic composite fibers, which forms a heat-sealing layer 2, and a papermaking material consisting of papermaking natural fibers or papermaking semi-synthetic fibers, which forms a non-heat-sealing layer 1, and by applying heat treatment under no-pressure or under pressure to the resultant wet web after a fluoro-surfactant is internally added to, or applied to. the wet web. The thermoplastic multi-branch type fibers are such fibers as pulp-like multi-branch type hydrophilic fibers consisting of a thermoplastic resin such as polyethylene. On the other hand, the thermoplastic composite fibers are such fibers as short fibers consisting of two or more kinds of thermoplastic synthetic-resin components having different melting points. This vapor-permeable and oil-repellent paper provides a wrapping material having heat resistance, vapor permeability for water vapor, water absorbability, wet strength, oil repellency and heat-sealing properties either on one face or on both faces, in the case where foodstuffs are heated or defrosted in a microwave oven as they are wrapped in this paper.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention has heat resistance, breathability, water absorption, water resistance, oil repellency, and heat sealability, and is suitable for packaging prepared foods, frozen foods, etc. The present invention relates to a breathable oil-repellent paper suitable for use.

[Conventional technology]

In recent years, with the mention of microwave ovens, the demand for cooked foods or cooked frozen foods that can be heated or thawed in microwave ovens has expanded, and many of these foods are usually made of plastic film and paper such as polyethylene. It is a heat-sealable packaging material consisting of a laminate of , and is sold individually packaged with the plastic film side facing the food on the inside.

For this reason, when heating and defrosting the entire bag in a microwave oven, the generated water vapor cannot escape to the outside of the package, resulting in excessive steaming of the food or tearing of the packaging bag, so be sure to remove the packaging. Must be heated and thawed. In order to package each bag individually so that it can be heated and thawed, it is necessary to use a packaging material that can dissipate the water vapor generated during heating and thawing. Packaging materials with heat-sealing properties have been proposed for microwave-heated foods (Utility Model Openings, 1986-
No. 203028). However, such perforated packaging materials have the disadvantage that when thawing frozen foods or heating foods, molten fats and oils seep through the small holes and create stains, reducing the product value.

There has also been a proposal to obtain a packaging material that is breathable, heat-sealable, and oil-repellent by laminating a plastic film with small holes and paper and then impregnating it with an oil repellent (Japanese Patent Laid-Open No. 63 -55075), the diameter of the small pores is as large as 20 to 3000μ, so molten oil and fat during food heating easily passes through these small pores and reaches the paper surface, so the oil repellency of the laminate is actually that of paper. It will depend on the oil repellency.

However, impregnation with an oil repellent does not provide enough oil repellency to prevent penetration of molten oil.

In addition, a laminate of paper and a heat-sealable nonwoven fabric containing polyolefin fibers has been proposed as a breathable packaging sheet (Japanese Patent Application Laid-Open No. 61-33952), but it is not suitable for packaging food cooked in microwave ovens. This sheet also absorbs oil, so it is not suitable for individual packaging of foods containing oil.

[Problem to be solved by the invention]

Even if an oil repellent is internally added or applied to conventional porous heat seal paper, the oil repellency cannot be improved, and it is inevitable that oil will be absorbed and oil stains will be formed on the paper. In order to prevent oil stains, it is not enough to simply use an oil repellent; the base sheet must be dense and dense. However, in order to dissipate water vapor, sufficient breathability is required, which means porosity. Conventionally, breathability and oil repellency were contradictory conditions, but it is necessary to have both. This is difficult, and a packaging material that has sufficient oil repellency against food oils and fats even when heated in a microwave oven, and has both air permeability and heat sealability has not yet been obtained.

In view of these circumstances, the present invention has been developed to provide heat resistance that prevents deformation or melting even when heated and thawed while packaged prepared foods, frozen foods, etc., air permeability that allows water vapor to escape,
The purpose of this invention is to provide a heat-sealable paper that has water absorbency for thawed water, water resistance that reduces strength loss due to absorption of thawed water, and oil repellency that does not absorb oil.

[Means for Solving the Problems] The present invention provides a breathable heat-sealing layer made of thermoplastic multi-branched fibers and thermoplastic composite fibers, and a breathable non-heat-sealing layer made of papermaking natural fibers or papermaking semi-synthetic fibers. This invention relates to an air-permeable oil-repellent paper characterized in that a sealing layer is joined by paper-weaving and treated with oil-repellent treatment using a fluorosurfactant.

In the present invention, the thermoplastic hyperbranched fiber is a hydrophilic pulp-like hyperbranched fiber made of a thermoplastic resin such as polyethylene or polypropylene, and is sold under the trade name SW I) by Mitsui Petrochemical Industries, Ltd., for example. has been done. The melting point of polyethylene-based SWP is 125-135°C, and the melting point of polypropylene-based SWP is 140-165°C.
It is. When a wet paper containing thermoplastic hyperbranched fibers alone or in a high proportion is heated below the melting point of the thermoplastic hyperbranched fibers to form a sheet, the highly fibrillated thermoplastic hyperbranched fibers They are physically intertwined to form a sheet with very few voids. Even if this sheet is further heated below its melting point, the size of the voids does not change; however, if it is heated above its melting point without applying pressure, the thermoplastic multibranched fibers will shrink, especially the fine fibrils. Because of the intense heating, voids are created in the areas that were filled before heating, and the pore diameters of the small voids increase to become a porous film. Furthermore, when heated under pressure above the melting point, the molten thermoplastic multi-branched fibers are pressurized before they shrink due to heat, so the voids are filled and a film with almost no voids is formed.

In addition, thermoplastic composite fibers are short fibers made of two or more types of thermoplastic synthetic resin components with different melting points; - In the shell, a component with a high melting point forms a core and a component with a low melting point forms a sheath. For example, the core is made of polypropylene (melting point 163°C) and the sheath is made of ethylene vinyl acetate copolymer (melting point %~+00°C) or polyethylene (13
0 to 134°C), and those using polyethylene terephthalate (melting point 260°C) for the core and ethylene vinyl acetate copolymer, polyethylene, or modified polyethylene terephthalate (melting point 110°C) for the sheath. be. When this composite fiber is heated without pressure at a temperature below the melting point of the core component and above the melting point of the sheath component, it becomes a net-like porous sheet, and when heated under pressure, it has voids at a specific combination of temperature and pressure. It has the property of producing a breathable film.

The present inventor has discovered that an air-permeable heat-sealing layer having voids with small pores can be formed by blending the thermoplastic multi-branched fibers and thermoplastic composite fibers and treating them under appropriate heat treatment conditions; Furthermore, this heat-seal layer and a non-heat-seal layer made of natural fibers for paper manufacturing or semi-synthetic fibers for paper manufacturing are bonded together, and the sheet is treated with an oil-repellent treatment using a fluorosurfactant to make cooked foods, frozen foods, etc. The present invention was achieved based on the discovery that a sheet that does not stain with molten fats and oils from foods can be obtained even when heated and thawed in a microwave oven.

That is, the breathable oil-repellent paper according to the present invention comprises a papermaking raw material containing thermoplastic multi-branched fibers and thermoplastic conjugate fibers forming a heat-sealing layer, and papermaking natural fibers or papermaking semi-fibers forming a non-heatsealing layer. It is produced by combining papermaking raw materials made of synthetic fibers to form a wet paper, internally adding or coating a fluorosurfactant to the wet paper, and then heat-treating the paper under no pressure or under pressure.

When the papermaking raw materials forming the heat-sealing layer and the papermaking raw materials forming the non-heat-sealing layer are combined and heat-treated, the heat-sealing layer is blended depending on whether the process is carried out under pressure or no pressure. The desired blending ratio and heat treatment conditions of the thermoplastic multi-branched fiber and the thermoplastic conjugate fiber are different. In addition, the melting point of the low melting point component of the thermoplastic composite fiber is lower than or about the same as the melting point of the thermoplastic multibranched fiber used, and the melting point of the high melting point component of the composite fiber is the melting point of the thermoplastic multibranched fiber. Choose one with a composition that will give you a higher value.

When performing heat treatment without pressure, it is necessary to raise the heating temperature to a temperature higher than the melting point of the thermoplastic multibranched fiber and the melting point of the low melting point component (sheath component in the case of core-sheath type) in the composite fiber. 50 to 90% by weight, preferably 80 to 90ffiJt% of thermoplastic multi-branched fibers are blended. The thermoplastic multi-branched fibers are heat-treated under no pressure to cause the fibrils to shrink and the pore diameters of the small gaps between the fibers to increase, resulting in a heat-sealing layer with appropriate air permeability. If only thermoplastic multi-branched fibers are used, the strength of the heat-sealing layer will be weak and the paper will break during the paper making process, so one layer of thermoplastic composite fibers will be added to increase the tensile strength.
It is blended in an amount of 0 to 20% by weight, preferably 10 to 15% by weight. The low melting point component in this composite fiber is ethylene vinyl acetate copolymer or polyethylene, and the high melting point component is polypropylene or polyethylene terephthalate. It is necessary that it expresses the following.

When heat-treating without applying pressure, the bonding strength between the heat-sealing layer and the non-heat-sealing layer is inferior to that of heat-treating under pressure. It is desirable to incorporate fibers or semi-synthetic fibers for papermaking into the heat-sealing layer so that the interlayer adhesive strength is reinforced by the adhesive force between similar fibers. The amount of natural fiber for paper making or semi-synthetic fiber for paper making blended in the heat seal layer is up to 40% by weight. If it exceeds 40% by weight, the thermoplastic multi-branched fibers in the heat seal layer will lack uniformity and the heat seal strength will also decrease.

In the case of heat treatment under pressure, if the thermoplastic multi-branched fibers are used alone or in a high proportion in the heat-sealing layer, the molten thermoplastic multi-branched fibers will fill the voids and become a non-porous film. Breathability is lost. Therefore, the blending amount of the thermoplastic hyperbranched fiber is IO to 501Rffi%, preferably 20 to 30% by weight, and the blending amount of the thermoplastic composite fiber is 50 to 90% by weight, preferably 70 to 80% by weight.
shall be. The thermoplastic multi-branched fibers are selected to have a melting point equal to or higher than the low melting point component of the thermoplastic conjugate fiber to be blended at the same time, and a melting point lower than the high melting point component of the conjugate fiber. The heating temperature is higher than the melting point of the thermoplastic multi-branched fiber and higher than the melting point of the low melting point component of the thermoplastic conjugate fiber, so that the thermoplastic multi-branched i! The temperature should be within a range that does not exceed the melting point of the woven fiber by 10℃ or more, and the pressure should be within a linear pressure of 30 to 6
It is desirable that it be about 0 g/cm.

In such pressurized heating, only the low melting point component of the thermoplastic composite fiber melts, and the high melting point component of the thermoplastic composite fiber forms a net and forms a film leaving voids around it, and these voids are heated Since the plastic multi-branched fibers are melted and filled, the heat-seal layer has appropriate air permeability. When a heat seal layer is formed only with thermoplastic composite fibers without blending thermoplastic multibranched fibers, the pore size of the voids is large and oils and fats are likely to seep through the voids, even if oil-repellent treatment is applied. Unable to prevent oil stains on food. Since a large amount of thermoplastic conjugate fiber is blended in the heat seal layer produced by pressure heating, the components of the thermoplastic conjugate fiber affect the heat seal strength. The low melting point component of the composite fiber is polyethylene or ethylene vinyl acetate copolymer, and the high melting point component is polypropylene or the like. Polyethylene terephthalate as a high melting point component is not preferred because it does not melt at the heat sealing temperature (usually 150 to 200°C) and may reduce sealing strength.

When heated under pressure, the bond between the heat-sealing layer and the non-heat-sealing layer becomes strong, but the air permeability is slightly lower than when heated without applying any pressure. In order to improve the properties, the heat-sealing layer contains up to 40% by weight of natural fibers for papermaking, semi-synthetic fibers for papermaking, and synthetic fibers for papermaking (polyester fibers, polyamide fibers, vinylon, etc.) that have a melting point higher than the heat treatment temperature. Can be added.

The non-heat-sealable layer is required to have air permeability, wet strength, oil repellency, printability, etc. in addition to the property that it cannot be heat-sealed, and is formed from natural fibers for papermaking or semi-synthetic fibers for papermaking. The most desirable constituent fiber is bleached softwood pulp, but hardwood pulp, Manila hemp pulp, rayon cellulose acetate, etc. may also be used. Furthermore, in order to improve the interlayer bonding strength between the heat-sealing layer and the non-heat-sealing layer when heat treatment is performed without applying pressure, thermoplastic composite fibers similar to the thermoplastic composite fibers blended into the heat-sealing layer are added. can also be blended into the non-heat seal layer. However, in this case, the content should be 15 ffi M% or less so that the non-heat sealing layer does not exhibit heat sealing properties.

The air permeability of the non-heat-sealing layer is determined by the beating degree and basis weight of the raw material, but no matter what the basis weight, the air permeability is 500 m.
1/min or more, preferably 100ml/min or more is required. Therefore, if the basis weight is low, since the sheet is thin, it is okay to use paper with a high degree of beating and fewer voids.
When the basis weight is high, the above air permeability cannot be obtained unless the beating degree is lowered to increase the voids in the paper. - As an example, a non-heat sealing layer with a basis weight of 30 to 40 g/m2 is formed using bleached softwood bulb 10006, and the air permeability of this streak is set to 500 to 80 g/m2.
In order to achieve 0 ml/min, the degree of beating needs to be 650 mIC3F or higher using Canada Rosuisan. Here, the air permeability is a constant differential pressure of 100 m + n1 (to 1 c
It is defined as the amount of air that passes through a passing surface of m” in 1 minute, and the exact unit is ml/min-cm2・100mm Hx
0, as measured by a cigarette paper air permeability meter.

A wet paper strength enhancer is added to the non-heat seal layer in order to impart wet strength. As the wet paper strength enhancer, polyamide polyamine epichlorohydrin resin, dialdehyde starch, etc. can be used, and the amount added is 0.0% as a solid content based on the natural fiber for paper manufacturing or the semi-synthetic fiber for paper manufacturing.
1 to 1.0%, preferably 0.3 to 0.5%.

The breathable oil-repellent paper according to the present invention, as shown in FIG.
It can be formed as a two-layer laminated paper 3 consisting of a non-heat-sealing layer 1 and a heat-sealing layer 2, or as shown in FIG. A laminated paper 4 is formed. Here, the "combining" may be a method of combining and drying wet paper, which is commonly used in paper manufacturing technology.

The heat seal layer has a basis weight of 10 to 30 g/m', preferably 15 to 20 g/m'. If the basis weight is lower than 10 g/m', sufficient heat sealing strength and oil barrier properties cannot be obtained. If it is higher than 30 g/m', the air permeability will be low and the cost will be high. Since the air permeability needs to be higher than that of the entire laminated paper, it is adjusted by adjusting the composition of raw fibers and the degree of beating so that the air permeability is 500 ml/min or more, preferably 1000 ml/min or more. The general method of use is to package and heat-seal the two-layer structure of air-permeable oil-repellent paper, which consists of a sealing layer and a non-heat-sealing layer, with the heat-seal layer on the inside that contacts the food. Oil paper is useful when used as an inner bag material when partially heat-sealing the inner bag to the outer bag in a bag with a double structure consisting of an inner bag and an outer bag.

A high degree of oil repellency is imparted to both the heat seal layer and the non-heat seal layer of the breathable oil repellent paper of the present invention. Oil repellency is achieved by internally adding fluorosurfactants to each papermaking raw material.
After fixing, paper is made, or after paper making, a fluorosurfactant solution is applied using a roll coater or the like.

Fluorine surfactants include perfluoroalkyl carboxylates, perfluoroargylsulfonates, perfluoroalkyl phosphates, perfluoroalkyl phosphates, and perfluoroalkyl phosphates having a perfluoroalkyl group having 6 to 14 carbon atoms. Polymer-type fluorosurfactants, etc., in which alkyl sulfonic acid amides, perfluoroalkyl sulfonic acid amide, etc. are introduced as pendant chains into the carboxyl group of polyacrylic acid or polymethacrylic acid in the form of an ester bond, etc. Generally, commercially available fluorosurfactants can be used.

When a fluorosurfactant is internally added to papermaking raw materials, it is added in the form of an aqueous solution or emulsion to the papermaking raw materials in a solid content of 0.1-2.0% by weight, preferably 0°2-1.0ff.
Add it 1%. When the fluorosurfactant is anionic, a cationic fixing agent can be added so that the surfactant is sufficiently fixed to the papermaking raw material. The fixing agent is preferably added before adding the fluorosurfactant, and the amount added is preferably 0.1 to 1.0 mm% in terms of solid content based on the papermaking raw material.

When applying a fluorosurfactant using a roll coater or the like, an aqueous solution or emulsion with a solid content concentration of 0.1 to 10.0% is used.

[Effect]

In the breathable oil-repellent paper according to the present invention, the heat-sealing layer is formed from thermoplastic multi-branched fibers and thermoplastic composite fibers, and when the thermoplastic multi-branched fibers are mixed in a high proportion of 50% or more by weight, the heat-sealing layer is non-heat-sealable. When the layers are bonded together, they are heat-treated under no pressure, and due to the heat shrinkage of the thermoplastic multi-branched fibers, countless pores are formed in the heat-sealing layer, creating air permeability, and the added heat Reinforcement is obtained by melting the low melting point components of the plastic composite fiber and forming a net of the high melting point components. In addition, when the heat seal layer is formed with a low content of thermoplastic multi-branched fibers of 50% by weight or less,
Thermoplastic composite fiber is 50ffiffi! 6 or more, and when bonded to the non-heat seal layer, heat treated under pressure, the thermoplastic composite fibers are formed into a film with voids left, and the thermoplastic multi-branched fibers are formed into a film. It fills the voids and becomes moderately porous. As described above, the heat-sealing layer of the breathable oil-repellent paper of the present invention has numerous extremely small pores uniformly dispersed therein due to the skillful combination of ingredients and heat treatment conditions, resulting in an air permeability of 100 ml/min or more. It is a dense layer that has good air permeability and can prevent oil stains, so by applying oil repellent treatment, the heat-sealing layer stops oils and fats from the packaged food, making it a non-heat-sealable layer. It does not seep through to the layers. Furthermore, due to the reinforcing effect of the thermoplastic composite fibers, a product with excellent wet strength can be obtained.

〔Example〕

Examples of breathable oil-repellent paper according to the present invention are shown below, and in each example, oil resistance, air permeability, interlayer strength, heat seal strength, and wet tensile strength were evaluated as follows.

Oil resistance> Measured by the kit test described in TAPPI Practical Test Method UM557 (1988). Place the test piece with the test side facing up, and add 1 drop of kit test solution from a height of 25 mm.
15 seconds after dropping the drop, excess liquid was wiped off, and it was observed whether the kit test liquid penetrated and became transparent. Twelve types of test liquids with different compositions are tested, and the highest liquid number that does not become transparent is displayed as the oil resistance.

Air permeability> Using a cigarette paper air permeability measuring device, the differential pressure was 100 mm1-1.
, 0, the amount of air passing through 1 cm of one test piece was measured.

Interlaminar strength〉 One end of a test piece with a diameter of 15 mm and a length of 200 mm was separated into a non-heat-sealing layer and a heat-sealing layer.
mm, and the maximum value during that time was taken as the interlayer strength.

Heat seal strength〉 Using a heat seal tester (manufactured by Tester Sangyo),
After heat-sealing at 60° C. and 2 kg/cm” for 2 seconds, it was cut into 15 mm widths and subjected to a T-peel test to determine the peel strength, which was defined as the heat-seal strength.

Wet tensile strength> A test piece with a diameter of 15 mm and a length of 200 mm was immersed in tap water at 20° C. for 30 minutes, excess water was wiped off with a filter paper, and the tensile strength was measured using a Schopper tensile tester.

Example 1 Tsubo used for individual packaging of frozen pies as follows: l'c
A two-layer laminated breathable oil-repellent paper of 58 g/mt was produced.

650rr LIC3 of softwood bleached pulp submerged in Canadian filter water
After beating to F, a polyamide polyamine epichlorohydrin wet paper strength enhancer (manufactured by Dick Vercules Co., Ltd.,
Product name Kaimen 557, hereafter Kaimen 557 ■- (abbreviated) was added at 0.5% by weight (solid content/solid content) and the first
It was used as a raw material for paper making.

Next, as the second papermaking raw material, polyethylene synthetic valve (manufactured by Mitsui Petrochemical Industries, Ltd., trade name SWP, hereinafter abbreviated as SWP) 90 ff1m% and a core-sheath type thermoplastic composite of ethylene vinyl acetate copolymer and polypropylene were used. A fiber (manufactured by Chisso ■, trade name: EA Woven Fiber, hereinafter abbreviated to EA Woven Fiber) containing IO weight percent was prepared.

Introducing the above two types of papermaking raw materials into each cylinder of a Yankee type cylinder paper machine equipped with two cylinders,
A two-layer laminated paper with a basis weight of 58 g/m' was produced.The non-heat sealing layer formed from the first papermaking raw material had a basis weight of 40g/m', and the heat sealing layer formed from the second papermaking raw material had a basis weight of 40g/m'. The basis weight of the seal layer was 8 g/m2.

Next, a fluorine-based surfactant (manufactured by Asahi Glass, trade name: Asahi Guard A) was applied to the two-layer laminated paper using a roll coater.
A fluorine treatment liquid containing 0.6% by weight (solid content) of G530), 20% by weight of ethyl alcohol, and 79.4% by weight of water was applied.

The fluorine-treated two-layer laminated paper was then passed through a supercalender with no pressure between the rolls at a roll temperature of 150°C to melt the heat seal layer and form a breathable film.

The thus obtained sheet-like material having a two-layer structure with a non-heat-sealable layer made of wood pulp on one side and a heat-sealed layer made of an air-permeable film on the other side was evaluated for air permeability, oil resistance, and heat-sealing strength. , wet tensile strength, etc. were measured, and the results are shown in Table 1.

After gravure printing a pattern on the non-heat-sealable layer of the sheet-like material, heat-sealing is performed to form a size of 16C11 in length and 16cm in width.
Make a 1/4 inch bag and put a frozen pie (made by Kyodo Dairy Products, frozen baked and edible potato pie) into a bag.
I sealed it. Place this packaging bag on a ceramic plate and microwave it (NIE6360 model high frequency output 6 manufactured by Matsushita Electric Industrial).
00W) for 3 minutes using the defrost menu. During heating in the microwave oven, a large amount of steam was observed escaping from the bag to the outside, and no oil stains were observed on the top surface of the bag or the surface in contact with the plate immediately after heating. There was no condensation water on the inside of the bag, and no water from thawing accumulated inside the bag, so it was obvious that the water generated when the frozen pie thawed turned into water vapor and emanated to the outside through the breathable bag. Met.

The thawed pie did not contain excessive moisture and become excessively soft, and the pie crust had an appropriate hardness, and had desirable quality as a commercial product.

Practical Example I A two-layer laminated breathable oil-repellent paper with a basis weight of 58 g/m'' for use in hamburger packaging bags was produced in the following manner.

After beating the softwood bleached bulb to 650 mIC3F by submerging it in Canada filtration water, 0.5 weight 06 (solid content/solid content) of Kaimen 557H was added, and then a fluorosurfactant (
Manufactured by Sumiya Kagaku Kogyo ■, product name: Sumirezu Resin FP 15
0) was added in an amount of 0.45% by weight (solid content/solid content).
It was used as a raw material for paper making.

Next, as the second papermaking raw material, S W P 30 ffi
ffi % and EΔ fiber 7 5 5 7 1-(0.1% by weight (solid content/solids)), then 0.15 weight ff 1% (solid content/solid content) of the above fluorosurfactant was added. minute) was prepared.

Introducing the above two types of papermaking raw materials into each cylinder of a Yankee type cylinder paper machine equipped with two cylinders,
A two-layer laminated paper with a basis weight of 58 g/m" was produced. The non-heat-sealable layer formed from the first papermaking raw material had a basis weight of 40g/m", and the non-heat sealing layer was formed from the second papermaking raw material. The basis weight of the heat seal layer was 18 g/+112.

The resulting two-layer laminated paper was subsequently heated to a roll temperature of 1
The paper was passed through a super calendar at 30° C. and a pressure of 40 kg/C1n between rolls to melt the heat-sealing layer and form a breathable film.

The results of measuring the properties in the same manner as in Example 1 for the thus obtained sheet-like product having a two-layer structure, with one side being a non-heat-sealing layer made of wood pulp and the other side being a heat-sealing layer made of a breathable film. are shown in Table 1.

As shown in Table 1, the product of the present invention based on Example 2 has an air permeability of I 70 mj/min, and has practically sufficient heat seal strength, wet tensile strength, and oil resistance. It was something to do.

After gravure printing a pattern on the non-heat-sealable layer of the sheet-like material, heat-sealing is performed to form a sheet with a length of 210 mm and a width of 1.
A 20 mm gusset bag (folded bag) was manufactured. Put a commercially available hamburger (made by Numa's Bakery, sold at 7-Eleven, product name: Cheeseburger) in this bag, fold the opening twice and secure it with cellophane tape, place it on a ceramic plate, and heat it in the same microwave as in Example 1. and heated for 30 seconds on high heat. While heating in the microwave,
A large amount of steam was observed escaping from the bag to the outside, and condensation water adhered to the surface of the dish. However, there was no condensation water on the inner surface of the bag, and it was clear that the water vapor generated by heating had emanated to the outside through the breathable bag. There were no oil stains on the surface of the bag, and the melted cheese, oil, and sauces from the cheeseburger were blocked by the heat seal layer on the inner surface of the bag and did not penetrate into the non-heat seal layer. The cheeseburger did not become excessively soft due to excessive water content, and the bread part had an appropriate hardness, so it had desirable quality as a product.

Example 3 A two-layer laminated breathable oil-repellent paper with a basis weight of 58 g/m2 used for individual packaging of frozen pies and having a higher interlayer strength between the two layers than in Example 1 was manufactured as follows. .

After beating the softwood bleached bulb to 700 mIC3F at Canadian freeness, Kymen 557H (15% by weight (solid content/solid content)) was added to prepare the first papermaking raw material.

Next, as the second papermaking raw material, 5WP60 weight 06 and E
A mixture containing 10% by weight of A fiber and 30% by weight of the bleached softwood pulp (freeness: 700 mIC3F) was prepared.

In the same manner as in Example 1, a two-layer laminated paper with a tsubo ffi of 58 g/m2 was made, coated with a fluorine-based surfactant, and then supercalendered. A sheet material having a two-layer structure consisting of a non-heat-sealable layer and a heat-sealable layer of 18 g/m' consisting of a porous film on the other side was produced. The air permeability, oil resistance, heat seal strength, wet tensile strength, etc. of the sheet-like material were measured, and the results are shown in Table 1.

As shown in Table 1, the product of the present invention based on Example 3 has a high air permeability of 1500 ml/min, and has practically sufficient heat seal strength, wet tensile strength, and oil resistance. there were. The interlaminar strength between the non-heat sealing layer and the heat sealing layer was 70 g/15 mm, which was significantly improved compared to the interlaminar strength of Example 1, which was 10 g/15 mm.

After gravure printing a design on the non-heat-sealable layer of the sheet-like material, it was heat-sealed to a size of 16 cm long and 16 cm wide.
A bag of size m was prepared, and the frozen pie was heated and defrosted in the microwave in the same manner as in Example 1.

During heating in the microwave oven, a large amount of steam was observed escaping from the bag to the outside, and no oil stains were observed on the top surface of the bag or the surface in contact with the plate immediately after heating. There was no condensation water on the inside of the bag, and no water from thawing accumulated inside the bag, and it was clear that the moisture generated when the frozen pie thawed turned into water vapor and emanated to the outside through the breathable bag. Met. The thawed pie did not contain excessive moisture and become excessively soft, and the pie crust had an appropriate hardness, and had desirable quality as a commercial product.

Next, put Ig butter (manufactured by Snow Brand Milk Products) in a three-sided sealed bag, place it on a plate, place a 100 g load on top of the bag, and heat it for 1 minute using the defrost menu in the microwave. When the afterload was removed (no oozing of molten butter was observed), it was clear that there was a barrier property against molten fats and oils.

Comparative Example 1 Paper with a thickness of 30 g/m" and a paper size of 17 g/m"
A sheet made of extrusion laminated polyethylene was prepared, and its properties are shown in Table 1.

Using this sheet, we conducted a thawing test on a frozen pie in the same manner as in Example 1. As a result, we found that significant condensation was observed inside the bag because the generated water vapor could not escape outside the bag, and the frozen pie was exposed to excess moisture. Because it had become excessively soft due to moisture, it had no suitable firmness for a pie, and its commercial value was significantly impaired.

Furthermore, as a result of wrapping and heating a cheeseburger using this sheet in the same manner as in Example 2, significant condensation was observed inside the bag because the generated water vapor could not escape outside the bag.
The cheeseburger was excessively soft due to excess moisture, and the bread lacked the proper hardness, significantly reducing its commercial value.

↓ Fall 2 The sheet used in Comparative Example 1 was embossed with a pinpoint pattern and perforated, and its properties are shown in Table 1.

Using this sheet, we conducted a thawing test on a frozen pie in the same manner as in Example 1. As a result, the generated water vapor was released to the outside of the bag, but due to the low air permeability of the bag, the release of water vapor was insufficient. As a result, condensation water was observed on the inside of the bag, and the outside of the bag was also wet.

Furthermore, large oil stains were formed around the mechanically embossed perforations on the top surface of the bag and the surface that came into contact with the plate, resulting in an unsightly appearance and a significant deterioration of the product image.

Furthermore, as a result of packaging and heating a cheeseburger using this sheet in the same manner as in Example 2, the generated water vapor diffuses to the outside of the bag, and almost no condensation water is seen on the inner surface of the bag, and the cheeseburger is There was no tendency to over-soften due to excess moisture, or oil and sauce stains formed around the mechanical perforations of the embossed bag surface.

In order to avoid getting your hands dirty when eating this hamburger, the instructions are to tear off one end of the bag and grab it from the top of the bag to eat it, so stains on the surface of the bag are undesirable and can significantly reduce the value of the product. It was damaging.

Comparative Example 3 A two-layer laminated paper with a basis weight of 5 Bg/m'' was prepared in the same manner as in Example 3, except that the thermoplastic multi-branched fiber SwP was not blended in the heat seal layer and the EA fiber was blended at 70 mm%. A sheet material having a two-layer structure consisting of a non-heat-sealing layer of 140 g/m2 and a heat-sealing layer of 18 g/m' is produced by applying a fluorosurfactant and then supercalendering. did.

The air permeability, oil resistance, heat seal strength, and wet tensile strength of the sheet-like material were measured, and the results are shown in Table 1.

As seen in Table 1, the sheet material based on Comparative Example 3 has a porous structure with lower density and higher air permeability than the product of the present invention based on Example 3, and has a higher heat seal strength and oil resistance. It was of low quality.

After gravure printing a pattern on the non-heat-sealable layer of the sheet-like material, heat-sealing is performed to form a sheet with a height of 16C1n and a width of 16cm.
A cm bag was prepared, and the frozen pie was heated and thawed in the microwave in the same manner as in Example 1.

During heating in the microwave, a large amount of steam was observed escaping from the bag to the outside, and the moisture generated when the frozen pie was thawed became water vapor and radiated to the outside through the breathable bag. A large oil stain appeared on the bag due to melted oil and fat during thawing, which significantly damaged the appearance of the bag and reduced its commercial value.

Next, 1 g of butter (manufactured by Snow Brand Milk Products) was placed in a three-sided sealed bag, placed on a plate, a 100 g load was placed on top of the bag, and the bag was heated for 1 minute using the defrost menu in a microwave oven. When the load was removed after heating, melted butter seeped out from inside the bag to the surface of the bag through the gaps in the sheet, causing stains on the surface.

In this way, the sheet-like material according to this comparative example has a porous structure, so it has high air permeability, but even though it has high oil resistance, oil and fat easily penetrate inside the sheet and reach the opposite side of the sheet. Since it easily permeates through, it is not preferred as a packaging material for microwave ovens. By comparing this comparative example and Example 3, it was found that blending thermoplastic multi-branched fibers in the heat seal layer is essential in order to obtain a product that has both air permeability, oil resistance, and barrier properties. I know.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a packaging material that has heat resistance, water vapor permeability, water absorption, wet strength, oil repellency, and heat sealability on one or both sides when food is heated and thawed in a microwave while still being packaged. Therefore, a breathable oil-repellent paper suitable for individual packaging of foods heated and thawed in a microwave oven, frozen foods, etc. is provided.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a two-layer breathable oil-repellent paper according to the present invention, and FIG. 2 is a partial cross-sectional view of a three-layer breathable oil-repellent paper according to the present invention. ■...Non-heat seal layer 2...Heat seal layer 3...2-layer structure breathable oil-repellent paper 4...3-layer structure breathable oil-repellent paper

Claims (5)

[Claims] (1) A breathable heat-sealing layer made of thermoplastic multi-branched fibers and thermoplastic composite fibers and a breathable non-heat-sealing layer made of papermaking natural fibers or papermaking semi-synthetic fibers are joined by papermaking, and fluorine A breathable oil-repellent paper characterized by being oil-repellent treated with a surfactant. (2) A breathable heat-sealing layer containing 50 to 90% by weight of thermoplastic multibranched fibers and 10 to 20% by weight of thermoplastic composite fibers, and a breathable non-heat-sealing layer made of natural fibers for papermaking or semi-synthetic fibers for papermaking. A breathable oil-repellent paper characterized in that a sealing layer is joined by paper-making and treated with oil-repellent treatment using a fluorine-based surfactant. (3) A papermaking raw material containing 50 to 90% by weight of thermoplastic multi-branched fibers and 10 to 20% by weight of thermoplastic composite fibers and a papermaking raw material consisting of natural fibers for papermaking or semi-synthetic fibers for papermaking are combined and wetted. After forming paper and performing oil-repellent treatment by internally adding or applying a fluorosurfactant to the wet paper, under no pressure,
Claim 2, characterized in that the heat treatment is carried out at a temperature that is higher than the melting point of the thermoplastic multi-branched fiber, higher than the melting point of the low melting point component of the thermoplastic conjugate fiber, and lower than the melting point of the high melting point component of the thermoplastic conjugate fiber. The method for producing the breathable oil-repellent paper described. (4) A breathable heat-sealing layer containing 10 to 50% by weight of thermoplastic multibranched fibers and 50 to 90% by weight of thermoplastic composite fibers, and a breathable non-heat-sealing layer made of natural fibers for papermaking or semi-synthetic fibers for papermaking. A breathable oil-repellent paper characterized in that a sealing layer is joined by paper-making and treated with oil-repellent treatment using a fluorine-based surfactant. (5) A papermaking raw material containing 10 to 50% by weight of thermoplastic multi-branched fibers and 50 to 90% by weight of thermoplastic composite fibers and a papermaking raw material consisting of natural fibers for papermaking or semi-synthetic fibers for papermaking are combined and wetted. After forming paper and performing oil-repellent treatment by internally adding or applying a fluorosurfactant to the wet paper, under pressure,
The heat treatment is carried out within a temperature range that is higher than the melting point of the thermoplastic multibranched fiber and higher than the melting point of the low melting point component of the thermoplastic composite fiber, but not higher than the melting point of the thermoplastic multibranched fiber by 10°C or more. The method for producing breathable oil-repellent paper according to claim 4.