Air-permeable liquid-repellent sheet

Abstract

To provide a breathable and liquid-repellent sheet that achieves both excellent breathability and excellent liquid repellency without containing fluorine-based materials. [Solution] A breathable and liquid-repellent sheet having a resin layer on one or both sides of a base layer made of polyethylene nonwoven fabric, wherein the resin layer contains (A) a nonfluorine polymer and (B) polyvinyl alcohol with a saponification degree of 60 mol% or more.

Description

[Technical Field]

[0001] This invention relates to a breathable, liquid-repellent sheet. More specifically, it relates to a breathable, liquid-repellent sheet that does not use materials containing fluorine atoms, has excellent breathability and liquid repellency, and is suitable as a packaging material that comes into contact with food. [Background technology]

[0002] Foods that are susceptible to deterioration and alteration due to oxygen in the air are sometimes packaged with oxygen absorbers before being sold on the market. In this case, the oxygen absorber is often used in small packets, for example, in the form of powder, granules, or small lumps, and then packaged inside the packaging material. Furthermore, fast food items such as hamburgers, hot dogs, and fried chicken, which are intended to be consumed soon after purchase, may be served to customers while still warm and freshly cooked, in simple packaging made of easily openable materials.

[0003] Packaging materials used for such purposes are required to possess appropriate breathability and liquid repellency. In other words, packaging materials for oxygen absorbers need to be breathable because they must allow oxygen from the air outside the small bag to be absorbed by the oxygen absorber inside the bag, and they also need to be liquid-repellent to prevent erosion by oils and other substances in the enclosed food. On the other hand, food packaging materials require breathability to avoid wetting due to the condensation of steam emitted from hot food, and also require liquid-repellent properties to suppress erosion from oils and other substances in the packaged food.

[0004] Conventionally, oil-resistant paper impregnated with a fluorine-based oil-resistant agent was used as packaging material for the above-mentioned applications. However, in recent years, the use of fluorinated compounds has begun to be restricted, mainly in Europe and the United States. For example, in the United States, the Hazardous Substances Control Act has been enacted, which regulates permissible levels of PFAS (perfluoroalkyl and polyfluoroalkyl compounds) and other substances in the environment. In the EU, regulations are being considered that would completely ban the manufacture, market placement, and use of mixtures and articles containing PFAS within the EU.

[0005] In response to these developments, various liquid-repellent papers that do not contain fluorine have been proposed. For example, Patent Document 1 discloses a non-fluorine copolymer composition containing a non-fluorine copolymer and an acetylene alcohol, and explains that processed paper obtained by treating paper with this composition exhibits excellent oil resistance. Furthermore, Patent Document 2 discloses a packaging material for oxygen absorbers comprising, in this order, an inner layer containing a thermoplastic resin layer, an intermediate layer containing non-fluorine-based oil-resistant paper, and another inner layer containing a thermoplastic resin layer, wherein the packaging material has internal ventilation holes that penetrate the inner and intermediate layers and external ventilation holes that penetrate the outer layer, without penetrating the entire front and back surfaces of the packaging material, and it is explained that using this as packaging material for oxygen absorbers achieves both oil resistance and oxygen absorption. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-067108 [Patent Document 2] International Publication No. 2023 / 189698 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, conventional techniques still result in oil-resistant paper with insufficient breathability and liquid repellency. The present invention has been made in view of the above circumstances, and its purpose is to provide a breathable and liquid-repellent sheet that achieves both excellent breathability and excellent liquid repellency without containing fluorine-based materials.

Means for Solving the Problems

[0008] The present invention is as follows. <<Aspect 1>> A breathable and liquid-repellent sheet having a resin layer on one or both sides of a base material layer made of a polyethylene-based nonwoven fabric, wherein the resin layer (A) a non-fluorine-based polymer, and (B) polyvinyl alcohol having a saponification degree of 60 mol% or more is included, a breathable and liquid-repellent sheet. <<Aspect 2>> The breathable and liquid-repellent sheet according to Aspect 1, wherein the (A) non-fluorine-based polymer is an acrylic polymer. <<Aspect 3>> The breathable and liquid-repellent sheet according to Aspect 1, wherein in the resin layer, the amount of the (B) polyvinyl alcohol with respect to 100 parts by mass of the (A) non-fluorine-based polymer is 1.0 part by mass or more and 1,000 parts by mass or less. <<Aspect 4>> The breathable and liquid-repellent sheet according to any one of Aspects 1 to 3, wherein the polyethylene-based nonwoven fabric is a nonwoven fabric made of continuous long fibers of high-density polyethylene. <<Aspect 5>> A method for manufacturing a breathable and liquid-repellent sheet, including applying a coating liquid on one or both sides of a base material layer made of a polyethylene-based nonwoven fabric, wherein the coating liquid (A) a non-fluorine-based polymer, and (B) polyvinyl alcohol having a saponification degree of 60 mol% or more is included, a manufacturing method. <<Aspect 6>> The manufacturing method according to Aspect 5, wherein the coating liquid contains alcohol.

Advantages of the Invention

[0009] According to the present invention, there is provided a breathable and liquid-repellent sheet in which excellent breathability and excellent liquid repellency are compatible without containing a fluorine-based material. The breathable and liquid-repellent sheet of the present invention can be suitably applied, for example, as a packaging material for a food deoxidizer, a packaging material for food, etc.

Modes for Carrying Out the Invention

[0010] 《Air-permeable, liquid-repellent sheet》 The air-permeable, liquid-repellent sheet of the present invention is A breathable and liquid-repellent sheet having a resin layer on one or both sides of a base layer made of polyethylene nonwoven fabric, The aforementioned resin layer (A) Non-fluorinated polymers, and (B) Polyvinyl alcohol with a degree of saponification of 60 mol% or more including, It is a breathable, liquid-repellent sheet.

[0011] <Base material layer> The base layer in the breathable, liquid-repellent sheet of the present invention is made of a polyethylene nonwoven fabric. The polyethylene nonwoven fabric constituting the base layer in the present invention is preferably a high-density polyethylene nonwoven fabric, and more preferably a continuous long-fiber nonwoven fabric of high-density polyethylene. High-density polyethylene continuous long-fiber nonwoven fabric is suitable as the base layer in the present invention because it has high water resistance and strength, as well as excellent surface smoothness.

[0012] In the present invention, the thickness of the base material layer is preferably 0.10 mm or more and 0.30 mm or less, more preferably 0.12 mm or more and 0.25 mm or less, and even more preferably 0.15 mm or more and 0.20 mm or less, considering the balance between the handling properties and strength of the base material layer. The basis weight (surface density) of the substrate layer is 30 g / m². 2 More than 120g / m 2 The following ranges are preferred, and more preferably, 40 g / m². 2 More than 100g / m 2 The following applies:

[0013] The fiber diameter of the fibers constituting the polyethylene nonwoven fabric used as the base layer of the present invention is preferably 0.01 to 30 μm, more preferably 0.05 to 25 μm, even more preferably 0.1 to 20 μm, particularly preferably 1.0 to 15 μm, and most preferably 1.5 to 10 μm. The average single-fiber fineness of the fibers constituting the thermoplastic long-fiber nonwoven fabric is preferably 0.7 dtex or more and 5 dtex or less.

[0014] In polyethylene nonwoven fabrics, the fibers may be fixed to each other, for example, by adhesive or by heat fusion. Spunbond nonwoven fabrics are particularly preferred.

[0015] Such high-density polyethylene continuous filament nonwoven fabrics are available commercially, and a preferred example is "Tyvek®" manufactured by Asahi DuPont Flashspun Products Co., Ltd.

[0016] <Resin layer> In the air-permeable liquid-repellent sheet of the present invention, the resin layer is present on one or both sides of the base layer. This resin layer (A) Non-fluorinated polymers, and (B) Polyvinyl alcohol with a degree of saponification of 60 mol% or more Includes. The resin layer may contain any components other than (A) a non-fluorinated polymer and (B) polyvinyl alcohol.

[0017] ((A) Non-fluorinated polymer) In the resin layer of the air-permeable liquid-repellent sheet of the present invention, (A) the non-fluorinated polymer preferably has repeating units derived from an acrylic monomer having a long-chain hydrocarbon group. The number of carbon atoms in this long-chain hydrocarbon group may be, for example, 6 to 20. Furthermore, it is preferable that this (A) non-fluorinated polymer does not have an aromatic ring.

[0018] (A) As the non-fluorinated polymer, acrylic polymers are particularly preferred, and plant-derived acrylic polymers are especially preferred. Such acrylic polymers are available commercially; for example, Daikin Industries, Ltd.'s "Unidyne XP8001" can be used.

[0019] ((B) Polyvinyl alcohol) The polyvinyl alcohol (hereinafter referred to as "PVA") in the resin layer of the air-permeable liquid-repellent sheet of the present invention is a polymer having repeating units derived from vinyl alcohol, and the concept includes unmodified PVA, modified PVA, and copolymerized PVA.

[0020] Unmodified PVA includes those obtained by saponifying a homopolymer of vinyl esters, and those obtained by saponifying a copolymer of two or more vinyl esters.

[0021] Modified PVA includes those obtained by substituting at least a portion of the molecular ends, main chain, and side chains of unmodified PVA with reactive groups, and those obtained by solubilizing unmodified PVA. Examples of modified PVA include carboxyl group modified PVA, carboxylate salt modified PVA, silicon modified PVA, acetoacetyl group modified PVA, diacetone group modified PVA, maleic anhydride modified PVA, hydroxyl group modified PVA, and cross-linked PVA.

[0022] Copolymerized PVA includes those obtained by saponifying a copolymer of a vinyl ester and another monomer. The other monomer may be, for example, an α-olefin, preferably ethylene. In the present invention, copolymerized PVA is preferred as the PVA, and saponified vinyl ester-ethylene copolymers are preferred. The content of ethylene units in the vinyl ester-ethylene copolymer (ethylene copolymerization ratio) is preferably 0.5 to 19.0 mol%. A content of ethylene units of 0.5 mol% or more results in good water resistance of the resulting permeable liquid-repellent sheet. A value of 19.0 mol% or less facilitates the preparation of aqueous solutions or aqueous dispersions of copolymerized PVA. The content of ethylene units in the vinyl ester-ethylene copolymer is more preferably 1.5 to 15.0 mol%, even more preferably 2.0 to 12.0 mol%, and particularly preferably 4.0 to 8.0 mol%.

[0023] The saponified vinyl ester-ethylene copolymer has repeating units derived from vinyl alcohol and repeating units derived from ethylene, and optionally further repeating units derived from vinyl ester, but may or may not have other repeating units. The structure of the other repeating units is not particularly limited.

[0024] The degree of saponification of PVA in the resin layer is 60 mol% or higher. By having a degree of saponification of PVA of 60 mol% or more, the resulting air-permeable, liquid-repellent sheet exhibits high liquid repellency, particularly oil repellency, without compromising breathability. The degree of saponification of PVA may be 70 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, 95 mol% or more, 98 mol% or more, or 99 mol% or more, or it may be 100 mol%.

[0025] In this specification, the degree of saponification is the value measured by the method described in "3.5 Degree of Saponification" of JIS K6726:1994.

[0026] ((A) Non-fluorinated polymer and (B) Polyvinyl alcohol ratio) In the resin layer of the air-permeable liquid-repellent sheet of the present invention, the amount of (B) polyvinyl alcohol per 100 parts by mass of (A) non-fluorinated polymer is preferably 1.0 part by mass or more and 1,000 parts by mass or less. By having this value of 1.0 part by mass or more and 1,000 parts by mass or less, the liquid repellency, and especially the oil repellency, of the resulting air-permeable liquid-repellent sheet is enhanced. The amount of (B) polyvinyl alcohol per 100 parts by mass of (A) nonfluorine polymer may be 3.0 parts by mass or more, 10 parts by mass or more, 30 parts by mass or more, 50 parts by mass or more, or 100 parts by mass or more, and may be 800 parts by mass or less, 600 parts by mass or less, 500 parts by mass or less, 400 parts by mass or less, 300 parts by mass or less, or 200 parts by mass or less.

[0027] (optional ingredient) As described above, the resin layer of the breathable and liquid-repellent sheet of the present invention contains (A) a non-fluorine-based polymer and (B) polyvinyl alcohol. The resin layer may contain other components in addition to these. Examples of other components that may be contained in the resin layer include general additives (e.g., defoamers, viscosity modifiers, pH adjusters, etc.) contained in the resin coating liquid.

[0028] (Amount of resin layer) In the breathable and liquid-repellent sheet of the present invention, the amount of the resin layer is 0.15 g / m as the total amount of (A) non-fluorine-based polymer and (B) polyvinyl alcohol per unit area of the breathable and liquid-repellent sheet. 2 or more and 2.00 g / m 2 or less is preferable. If the resin layer is in this range of amount, high breathability and good liquid repellency can be ensured, and at the time of coating the resin layer, it is easy to ensure film thickness uniformity and the advantage that the drying time can be shortened can be obtained. The amount of the resin layer in the breathable and liquid-repellent sheet is 0.20 g / m 2 or more, 0.50 g / m 2 or more, 0.70 g / m 2 or more, 1.0 g / m 2 or more, or 1.2 g / m 2 or more may also be acceptable, and 1.80 g / m 2 or less, 1.50 g / m 2 or less, 1.20 g / m 2 or less, 1.00 g / m 2 or less, 0.80 g / m 2 or less, or 0.50 g / m 2 or less may also be acceptable.

[0029] In the breathable and liquid-repellent sheet, the amount of (A) non-fluorine-based polymer is, as the amount of (A) non-fluorine-based polymer per unit area of the breathable and liquid-repellent sheet, 0.05 g / m 2 or more, 0.10 g / m 2 or more, 0.15 g / m 2 or more, or 0.18 g / m 2 or more may be acceptable, and 1.50 g / m 2 or less, 1.20 g / m 2 or less, 1.00 g / m2 Below 0.80g / m 2 Below 0.50g / m 2 The following, or 0.30 g / m² 2 The following is acceptable: The amount of (B) polyvinyl alcohol in the air-permeable liquid-repellent sheet is 0.05 g / m², expressed as the amount of (B) polyvinyl alcohol per unit area of ​​the air-repellent sheet. 2 More than 0.10g / m 2 More than 0.15g / m 2 Above, or 0.20 g / m² 2 The above is acceptable, and 1.00 g / m 2 Below 0.80g / m 2 Below 0.50g / m 2 The following, or 0.40 g / m 2 The following is acceptable:

[0030] (Position of the resin layer) In the breathable liquid-repellent sheet of the present invention, the resin layer is present on one or both sides of the base material layer. Whether the resin layer is present on one side of the base layer or on both sides of the base layer, the resin layer remains near the surface of the base layer without filling the interior of the base layer. This avoids filling the pores (gaps between fibers) of the permeable liquid-repellent sheet that constitutes the base layer, thus ensuring high breathability of the permeable liquid-repellent sheet.

[0031] When applying the air-permeable liquid-repellent sheet of the present invention to packaging materials that come into contact with food, if the resin layer is present on only one side of the base material layer, it is preferable to use the air-permeable liquid-repellent sheet in a direction that allows the resin layer to come into contact with the food. For example, when using the breathable liquid-repellent sheet of the present invention as a packaging material for an oxygen absorber, it is preferable to form the packaging so that the resin layer is on the outside. On the other hand, when using the air-permeable liquid-repellent sheet of the present invention as a packaging material for food products such as fast food, it is preferable to form the packaging so that the resin layer is on the inside.

[0032] When the resin layer is present on both sides of the substrate layer, the amount of resin layer described above is the recommended value for each side. In other words, the total amount of resin layer present on both sides of the substrate layer is twice the recommended value for the resin layer described above.

[0033] Method for manufacturing air-permeable, liquid-repellent sheets The air-permeable, liquid-repellent sheet of the present invention may be manufactured by any method, as long as it has the above-described configuration. The air-permeable, liquid-repellent sheet of the present invention is, for example, A method for producing an air-permeable liquid-repellent sheet, comprising applying a coating liquid to one or both sides of a base layer made of polyethylene nonwoven fabric, The aforementioned coating liquid, (A) Non-fluorinated polymers, and (B) Polyvinyl alcohol with a degree of saponification of 60 mol% or more including, It may be manufactured according to the manufacturing method.

[0034] (Coating liquid) The coating liquid used in the method for producing the air-permeable liquid-repellent sheet of the present invention is (A) Non-fluorinated polymers, and (B) Polyvinyl alcohol with a degree of saponification of 60 mol% or more It contains, preferably, these dissolved or dispersed in a suitable solvent.

[0035] The (A) non-fluorinated polymer and (B) polyvinyl alcohol contained in the coating liquid may be appropriately selected according to the desired (A) non-fluorinated polymer and (B) polyvinyl alcohol in the resin layer of the permeable liquid-repellent sheet of the present invention.

[0036] The degree of saponification of (B) polyvinyl alcohol contained in the coating solution is 60 mol% or more, the same as that of (B) polyvinyl alcohol contained in the resin layer of the air-permeable liquid-repellent sheet. (B) When the degree of saponification of polyvinyl alcohol is 60 mol% or higher, the above-mentioned advantageous effects are exhibited for air permeable liquid-repellent sheets, and the following advantages are available for coating liquids. (B) By having a degree of saponification of polyvinyl alcohol of 60 mol% or more, the penetration of the coating solution into the substrate layer can be adjusted to an appropriate range. That is, a coating solution containing polyvinyl alcohol with a degree of saponification of 60 mol% or more readily adheres to the substrate layer and does not penetrate the substrate layer excessively. Therefore, such a coating solution can form a resin layer near the surface of the substrate layer without the resin layer filling the interior of the substrate layer, thereby ensuring the breathability of the resulting permeable liquid-repellent sheet.

[0037] The solvent for the coating solution can be any solvent as long as it can dissolve or disperse (A) a non-fluorinated polymer and (B) polyvinyl alcohol. The solvent for the coating solution may be, for example, water, or a mixture of water and a water-soluble organic solvent. Examples of water-soluble organic solvents include alcohol, acetone, dioxane, acetic acid, 1,2-dimethoxyethane, etc., and one or more selected from these may be used. Specific examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, t-butyl alcohol, etc., with ethanol being preferred.

[0038] The solvent of the coating solution used in the method for producing the air-permeable liquid-repellent sheet of the present invention preferably contains alcohol (particularly ethanol). By including alcohol in the solvent of the coating solution, the penetration of the coating solution into the substrate layer is adjusted to an appropriate range. The solvent for the coating solution is preferably a mixed solvent containing water and alcohol. The amount of alcohol in this solvent is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, relative to the total amount of the coating solution.

[0039] Furthermore, when using commercially available solutions or dispersions containing solvents as (A) non-fluorinated polymer and (B) polyvinyl alcohol, the solvents contained in these commercially available products may be included as is in the solvent of the coating solution. The coating solution may contain (A) a non-fluorinated polymer and (B) polyvinyl alcohol, as well as a solvent, and other common additives found in resin coating solutions (e.g., defoamers, viscosity modifiers, pH adjusters, etc.).

[0040] The solid content concentration of the coating solution may be appropriately set by a person skilled in the art, depending on the coating method adopted.

[0041] (Formation of a resin layer on a substrate layer) The above-mentioned coating liquid is applied to one or both sides of a substrate layer to form a coating film, and then, if necessary, the obtained coating film is dried to form a resin layer on one or both sides of the substrate layer, thereby obtaining the breathable liquid-repellent sheet of the present invention. The coating method is preferably a printing method or a coating method because it is possible to form a uniform coating film at high speed. Examples of printing methods include gravure printing, flexographic printing, and offset printing. Examples of coating methods include roll coating, knife coating, air knife coating, die coating, blade coating, bar coating, bill blade coating, and short dwell blade coating. Drying may be carried out, for example, by letting it stand at a temperature of 50°C to 120°C for a period of time of, for example, 10 seconds to 1 hour. [Examples]

[0042] The present invention will be specifically described below with reference to examples and comparative examples relating to the present invention. However, the present invention is not limited to these examples and comparative examples. The gas permeability, moisture permeability, and liquid repellency of the permeable and liquid-repellent sheets obtained in the examples and comparative examples were evaluated as follows.

[0043] (1) Measurement of gas permeability As gas permeability, air permeability and water vapor permeability were measured using the following methods. (1-1) Measurement of air permeability The air permeability of the permeable liquid-repellent sheet was measured in accordance with JIS P8117:2009 using a Gurley-type densometer manufactured by Toyo Seiki Seisakusho Co., Ltd. Here, a smaller measured value indicates higher air permeability. For the intended applications of the air-permeable liquid-repellent sheet of the present invention, an air permeability of 10,000 seconds / 100 mL or less is sufficient. (1-2) Measurement of moisture permeability The moisture permeability of the air-permeable liquid-repellent sheet is measured according to JIS L1099:2012 "Test Method for Moisture Permeability of Textile Products" A-1 (Calcium Chloride Method) (g / m²). 2 The evaluation was performed under conditions of 40°C and 90% RH, in accordance with (h). Here, a higher measurement value indicates higher breathability.

[0044] (2) Evaluation of liquid repellency As for liquid repellency, oil resistance and alcohol resistance were measured by the following methods. (2-1) Measurement of oil resistance The oil resistance of the permeable liquid-repellent sheet was measured on the resin layer-forming surface in accordance with J.TAPPI Pulp Test Method No. 41:2000 "Test Method for Oil Repellency of Paper and Paperboard (Kit Method)". The measurement was performed visually, and the kit number with the highest number of samples where no penetration of the test liquid to the reverse side was observed was used as the indicator of oil resistance. In this test, samples with a higher maximum kit number are judged to have higher oil resistance. (2-2) Measurement of alcohol resistance The alcohol resistance of the permeable liquid-repellent sheet was measured on the resin layer-forming surface in accordance with JIS L1912. Specifically, an ethanol aqueous solution was dropped onto the resin layer-forming surface of the permeable liquid-repellent sheet sample, left to stand for 5 minutes, and then visually observed from the back side to check for penetration of the ethanol aqueous solution. The same procedure was performed using ethanol aqueous solutions of different concentrations, and the concentration of the most concentrated ethanol aqueous solution that did not penetrate to the back side was used as the alcohol resistance index (score). In this test, samples with higher scores are judged to have higher alcohol resistance. For the intended use of the air-permeable liquid-repellent sheet of the present invention, an alcohol resistance of approximately 30 to 40 is considered preferable.

[0045] The materials used in the following examples and comparative examples are as follows: <Base material layer> Asahi DuPont Flashspun Products Co., Ltd., product name "Tyvek 1059B" (basis weight 64.5g / m²) 2 (178 μm thickness) (A) Non-fluorinated polymers Aqueous solution containing 18% by mass of acrylic polymer, manufactured by Daikin Industries, Ltd., product name "Unidyne XP-8001". (B) Polyvinyl alcohol Examples 1 and 3-10, and Comparative Example 5: Kuraray Co., Ltd., product name "Kuraray Poval 28-98", degree of saponification 98 mol% Example 2: Mitsubishi Chemical Corporation, product name "Gosenol KL-05", degree of saponification 80 mol% Comparative Example 4: Mitsubishi Chemical Corporation, product name "Gosenex LW-100", degree of saponification 40 mol%

[0046] Examples 1-10 and Comparative Examples 1-5 A coating solution was prepared by dissolving a predetermined amount of (B) polyvinyl alcohol in warm water, mixing it with a predetermined amount of (A) aqueous solution containing a non-fluorinated polymer, and then adding a predetermined amount of ethanol and mixing thoroughly. Using a tabletop bar coater (manufactured by Matsuo Sangyo Co., Ltd., model "K202"), a predetermined amount of coating liquid was applied to one side of the base material layer, and then dried for 1 minute in a drying oven heated to 80°C to form a resin layer on one side of the base material layer, thereby producing an air-permeable liquid-repellent sheet. Here, the specified amounts of (A) non-fluorinated polymer, (B) polyvinyl alcohol, and ethanol, as well as the coating solution, are the amounts listed in Table 1. The obtained air-permeable, liquid-repellent sheets were evaluated according to the method described above. The results are shown in Table 1.

[0047] [Table 1]

[0048] As shown in Table 1, the sheets of Comparative Examples 1 to 3, in which the resin layer contained (A) a non-fluorinated polymer but (B) polyvinyl alcohol, had excellent air permeability but insufficient liquid repellency (especially oil resistance). On the other hand, the sheet of Comparative Example 5, in which the resin layer contained (B) polyvinyl alcohol but not (A) a non-fluorinated polymer, had excellent moisture permeability, but insufficient air permeability and liquid repellency (especially oil resistance). Furthermore, although the resin layer of Comparative Example 4 contained (A) a non-fluorinated polymer and (B) polyvinyl alcohol, the degree of saponification of (B) polyvinyl alcohol was low at 40 mol%, resulting in excellent expected permeability, but insufficient liquid repellency (especially oil resistance).

[0049] In contrast to these, the permeable liquid-repellent sheets of Examples 1 to 10, in which the resin layer contains (A) a non-fluorinated polymer and (B) polyvinyl alcohol with a degree of saponification of 60 mol% or more, were verified to have excellent moisture permeability and liquid repellency. In particular, it was revealed that when the amount of (B) polyvinyl alcohol per 100 parts by mass of (A) non-fluorinated polymer in the resin layer is 450 parts by mass or less, it exhibits extremely high air permeability in addition to moisture permeability and liquid repellency.

Claims

1. A breathable and liquid-repellent sheet having a resin layer on one or both sides of a base layer made of polyethylene nonwoven fabric, The aforementioned resin layer (A) Non-fluorinated polymers, and (B) Polyvinyl alcohol with a degree of saponification of 60 mol% or more including, A breathable, liquid-repellent sheet.

2. The air-permeable liquid-repellent sheet according to claim 1, wherein the (A) non-fluorinated polymer is an acrylic polymer.

3. The permeable liquid-repellent sheet according to claim 1, wherein in the resin layer, the amount of (B) polyvinyl alcohol per 100 parts by mass of (A) nonfluorine polymer is 1.0 part by mass or more and 1,000 parts by mass or less.

4. The breathable and liquid-repellent sheet according to any one of claims 1 to 3, wherein the polyethylene-based nonwoven fabric is a nonwoven fabric made of continuous long fibers of high-density polyethylene.

5. A method for producing an air-permeable liquid-repellent sheet, comprising applying a coating liquid to one or both sides of a base layer made of polyethylene nonwoven fabric, The aforementioned coating liquid, (A) Non-fluorinated polymers, and (B) Polyvinyl alcohol with a degree of saponification of 60 mol% or more including, Manufacturing method.

6. The manufacturing method according to claim 5, wherein the coating liquid contains alcohol.

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