Composite paper having oil resistance

Abstract

The present invention addresses the problem of providing a composite paper which exhibits excellent oil resistance, water vapor permeability, and water resistance even when hot and oily food is wrapped therein. The above problem can be solved by using a composite paper comprising an oil-resistant layer formed on at least one surface of a base paper, wherein the oil-resistant layer comprises a vinyl alcohol polymer (A) having a content of ethylene units of 2 to 10 mol %, a viscosity-average degree of polymerization of 300 to 2000, a saponification degree of 95 to 99.5 mol %, a total content of carboxyl groups and lactone rings of 0.02 to 3 mol %, a melting point of 180 to 230 C., a content of 1,2-glycol bonds of 1.2 to 2 mol %, and a molar fraction of central hydroxyl groups in chains of three consecutive hydroxyls by a triad expression relative to vinyl alcohol units of 65 to 98 mol %, the base paper has an air permeability resistance of 1000 seconds or less and a bulk density of 0.5 to 1.0 g/cm.sup.3, and the oil-resistant layer is formed in an amount of 0.1 to 10.0 g/m.sup.2 in terms of dry mass. The oil-resistant layer may also contain a fluorine compound (B), a layered inorganic compound (C) having an average aspect ratio of 20 to 1000, a fatty acid sizing agent (D), or a cross-linking agent (E).

Claims

1. A composite paper, comprising: an oil-resistant layer, which comprises: a vinyl alcohol polymer, which has an amount of ethylene units ranging from 2 mol % to 10 mol %, a viscosity-average degree of polymerization ranging from 300 to 2000, a saponification degree ranging from 95 mol % to 99.5 mol %, a total amount of a carboxyl group and a lactone ring ranging from 0.02 mol % to 3.0 mol %, a melting point ranging from 180 C. to 230 C., an amount of a 1,2-glycol bond ranging from 1.2 mol % to 2 mol %, and a molar fraction of a central hydroxyl group in a chain of three consecutive hydroxyls by a triad expression relative to vinyl alcohol units ranging from 65 mol % to 98 mol %, a base paper, which has an air permeability resistance that is less than or equal to 1000 seconds and a bulk density ranging from 0.5 g/cm.sup.3 to 1.0 g/cm.sup.3 , and wherein the oil resistant layer further comprises a fluorine compound in an amount ranging from 1 part to 50 parts by mass, based on 100 parts by mass of the vinyl alcohol polymer, where the oil-resistant layer is formed in an amount ranging from 0.1 g/m.sup.2 to 3.0 g/m.sup.2 in terms of dry mass, wherein the oil-resistant layer is formed on a surface of the base paper.

2. The composite paper as claimed in claim 1, which has a water vapor transmission rate that is more than or equal to 1000 g/m.sup.2.Math.24 h.

3. The composite paper as claimed in claim 1, wherein the oil-resistant layer further comprises: a layered inorganic compound in an amount ranging from 10 parts to 200 parts by mass, based on 100 parts by mass of the vinyl alcohol polymer, wherein the layered inorganic compound has an average aspect ratio ranging from 20 to 1000, and the oil-resistant layer is formed in an amount ranging from 0.5 g/m.sup.2 to 10.0 g/m.sup.2 in terms of dry mass.

4. The composite paper as claimed in claim 3, wherein the layered inorganic compound is kaolin.

5. The composite paper as claimed in claim 3, wherein the layered inorganic compound is talc.

6. The composite paper as claimed in claim 3, wherein the layered inorganic compound is a swelling clay mineral.

7. The composite paper of claim 3, wherein the oil-resistant layer further comprises: a fatty acid sizing agent in an amount that is less than or equal to 50 parts by mass, based on 100 parts by mass of the vinyl alcohol polymer.

8. The composite paper of claim 1, wherein the oil-resistant layer further comprises: a cross-linking agent in an amount that is less than or equal to 30 parts by mass, based on 100 parts by mass of the vinyl alcohol polymer.

9. The composite paper as claimed in claim 8, wherein the cross-linking agent is a polyamide epichlorohydrin compound.

10. The composite paper as claimed in claim 8, wherein the cross-linking agent is a zirconium compound.

11. The composite paper as claimed in claim 10, wherein the cross-linking agent is zirconium oxynitrate.

Description

EXAMPLES

(1) The present invention will be detailed with reference to Examples, but the present invention is not limited to these examples. In Examples and Comparative Examples below, unless otherwise indicated, parts and % are parts by mass and % by mass, respectively.

(2) [Evaluation of a Composite Paper]

(3) (1) Evaluation of Oil Resistance

(4) Kit Test

(5) Oil resistance is generally determined by TAPPI UM557 Repellency of Paper and Board to Grease, Oil, and Waxes (Kit Test).

(6) Oil resistance is usually evaluated by a kit test (TAPPI UM557). A kit test is a technique in which a processed paper is put in a hydrocarbon or is contacted with a hydrocarbon mixture with gradually reducing surface tension (castor oil, a mixture of toluene and heptane in various rates) for 15 sec to evaluate resistance against permeation.

(7) Since a kit test can give an index in a very short time, it has been extensively used as a convenient means for evaluating oil resistance, but evaluation obtained from this test may not be a reflection of reality. For example, when, for a given fat, good oil resistance is indicated by a kit test using a fat mixture at a temperature higher than room temperature, actual oil resistance may not be practically acceptable. We, therefore, performed a series of practically usable performance tests described below.

(8) (2) Practical Oil Resistance Evaluation

(9) Resistance Test for a Fatty Acid Mixture

(10) As a fatty acid mixture, five mixtures (A*), (B*), (C*), (D*) and (E*) having the compositions shown in Table 1 are prepared from pure compounds.

(11) TABLE-US-00001 TABLE 1 Mixture Mixture Mixture Mixture Mixture (A*) (B*) (C*) (D*) (E*) (% by (% by (% by (% by (% by mass) mass) mass) mass) mass) Castor oil 80 Oleic acid C18 20 75 62 41 9 Linolenic acid C18 11 4 3 2 Palmitic acid C16 14 32 38 18 Lauric acid C12 2 8 56 Capric acid C10 3 6 Caprylic acid C8 1 8 Caproic acid C6 6 1

(12) The above mixture generates a waxy solid having various melting points at room temperature. In order to make a composition and a temperature of each mixture even, it is stored at 60 C. at least for 30 min.

(13) Next, a composite paper prepared in an Example or Comparative Example is cut into a size of 5 cm5 cm, and each test piece is put on a black paper and placed in an oven at 60 C. Then, five drops of the test mixture are dropped onto the oil-resistant layer side of the test piece. The door of the dryer is closed and the test piece is kept in contact with drops of the test mixture for 10 min. Then, the door of the dryer is opened and mixture drops are removed using a blotting paper. Each test mixture is judged to be positive when permeation is not observed while being judged to be negative when permeation is observed from darkening of the droplet-applied area in each surface. For each mixture, at least two test pieces are used for evaluation. The test result is recorded as a code of the test mixture before the first test mixture which permeates the test piece although, when permeation is observed for a fatty acid mixture of composition (A*), it is judged to be negative.

(14) The above test shows that permeability of a hot fatty acid within a temperature range of 40 to 60 C. depends on its chemical structure. For example, heat permeability of a linear fatty acid on a paper sized with an oil-repellent material depends primarily on a length of a hydrocarbon chain, that is, the carbon number of the fatty acid. If the carbon number is low, a time required is reduced and droplets of the fatty acid permeate into a sized paper at a certain temperature. Furthermore, with the same carbon number, it can be found that permeability in a sized paper is substantially unsusceptible to the presence of unsaturation in the structure of a linear fatty acid in comparison with a corresponding saturated fatty acid.

(15) Mixture (A*) contains 20% fatty acid and is diluted with 80% castor oil. (A*) is less permeable and thus generally used for determining the lower performance value required generally for a fast food, for example, the performance value required for producing a disposable paper for a hamburger. A general sized paper as described above usually has a test kit value of 3 to 5. Compositions of mixtures (B*), (C*), (D*) and (E*) represent fatty acid compositions of olive oil, an animal oil, butter and coconut oil, respectively. Since this test utilizes a fatty acid being present in triglycerines contained in a common fat, oil-resistance behavior of a paper under more practical conditions can be evaluated.

(16) Regarding oil resistance when a hot food is packaged, a test for resistance to oleic acid or hot corn oil described below, was performed. A test for resistance to oleic acid is very meaningful in examining the presence of high oil-repellency under practical conditions, because oleic acid is the most prevailing fatty acid among those constituting animal or vegetable oils.

(17) Test for Resistance to Oleic Acid

(18) A composite paper prepared in an Example or Comparative Example is cut into a square of 10 cm10 cm, and placed in an oven at 60 C. Then, twenty drops of oleic acid are dropped onto the oil-resistant layer side of the composite paper. The test piece thus prepared is left in the oven at 60 C. for 2 hours. Then, oleic-acid droplets are removed using a blotting paper and the sample is placed on a black paper. When oleic acid permeates the paper, the permeated area is observed as a black spot. In this test, when permeation is not observed in any area where oleic acid is added dropwise, the test is judged to be positive (that is, resistance to oleic acid is demonstrated). In contrast, when permeation is observed, the test is judged to be negative (that is, resistance to oleic acid is not demonstrated).

(19) Hot Corn Oil Test

(20) This test is a technique used for evaluating a wrapping paper for a fast food. A composite paper prepared in an Example or Comparative Example is cut into a size of 5 cm5 cm, and each test piece is placed on a black paper and then 1 mL of corn oil is added dropwise onto the oil-resistant layer side of the test piece. The time of addition is regarded as a test initiation time, the test piece is placed in an oven at 110 C. for 20 min and at certain intervals, whether the oil is absorbed or not is observed. When oil absorption occurs, the paper becomes transparent and an absorption degree is indicated by blackening of the test piece. When absorption is observed in 20 min, the test is judged to be negative while when absorption is not observed after 20 min, the test is judged to be positive.

(21) (3) Air Permeation Resistance

(22) It was determined using an Oken type smoothness and air permeability tester in accordance with JIS P8117. An air permeation resistance value is a time taken for passing of 100 mL of air through a certain area. Thus, the larger an air permeation resistance value is, the less air permeates.

(23) (4) Water Vapor Permeability

(24) In accordance with test methods for determination of the water vapor transmission rate of moisture-proof packaging materials (dish method) as described in JIS Z0208-1976, measurement was conducted under the conditions of a temperature of 40+/0.5 C. and a relative humidity of 90+/2%. A water vapor transmission rate of 1000 to 5000 g/m.sup.2.Math.24 hr is judged as suitable to food packaging without dew condensation in the package or moisture absorption from the outside of the package.

(25) (5) Evaluation of Practical Water Resistance

(26) On the coated side of a composite paper prepared in an Example or Comparative Example was placed one steamed meat bun (Tenshinkaku-Hojun nikuman from Nippon Ham), which was then cooked using a microwave by heating at 600 W for one min. One minute later, the composite paper and the steamed meat bun were taken out from the microwave. The steamed meat bun was removed from the composite paper, and the surface of the composite paper was visually observed. Detachability of the food was judged in accordance with the following criteria. Here, evaluation rate A or B can be said to be practically suitable.

(27) A: No adhesion of a croute of steamed meat bun

(28) B: Some adhesion of a thin croute of steamed meat bun

(29) C: Adhesion of a large croute of steamed meat bun

(30) D: Peeling of the bottom of a steamed meat bun and adhesion of a croute and contents

(31) (6) Water-resistant Surface Strength

(32) On the oil-resistant layer side of a composite paper prepared in an Example or Comparative Example was added dropwise about 0.1 mL of ion-exchanged water at 20 C., which was then rubbed with the tip of a finger. Elution of the coating material was observed and rated on a scale of one to five below.

(33) 5: Water resistance is excellent without sliminess.

(34) 4: Sliminess is present, but no changes are observed in the coating layer.

(35) 3: Some of the coating material is emulsified.

(36) 2: The coating material is totally re-emulsified.

(37) 1: The coating material is dissolved.

(38) [Synthesis of Vinyl Alcohol Polymer PVA-1]

(39) In a 250 liter pressurized reaction vessel equipped with a stirrer, a nitrogen inlet, an ethylene inlet, an initiator input port and a delay solution input port were charged 107.2 kg of vinyl acetate, 42.8 kg of methanol and 15.6 g of maleic anhydride, and the mixture was warmed to 60 C., and the system was nitrogen-substituted by nitrogen bubbling for 30 min. Then, ethylene was introduced to a reaction vessel pressure of 5.9 Kg/cm.sup.2. An initiator, 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile)(AMV) was dissolved in methanol to prepare a 2.8 g/L solution, which was then bubbled with nitrogen gas for nitrogen substitution. Separately, maleic anhydride was dissolved in methanol to prepare a 5% solution as a delay solution, which was then bubbled with nitrogen gas for nitrogen substitution. After adjusting an inner temperature of the polymerization vessel to 60 C., 204 mL of the above initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to keep a reaction vessel pressure at 5.9 kg/cm.sup.2 and a polymerization temperature at 60 C. The polymerization was conducted while AMV using the above initiator solution at 640 mL/hr and maleic anhydride using the above delay solution were continuously added such that a ratio of vinyl acetate to maleic anhydride is kept constant. After 4 hours when a rate of polymerization reached 30%, the mixture was cooled to quench the polymerization. At this point, the total amount of the maleic anhydride delay solution added by delay was 1400 mL. The reaction vessel was opened to remove ethylene and nitrogen gas was bubbled for completely removing ethylene. Then, the unreacted vinyl acetate monomer was removed under a reduced pressure to give a solution of polyvinyl acetate in methanol. To the obtained polyvinyl acetate solution was added methanol to adjust a concentration to 30 A). To 333 g of the solution of polyvinyl acetate in methanol (100 g of polyvinyl acetate in the solution) was added 46.5 g (a molar ratio [MR] based on vinyl acetate units in polyvinyl acetate: 0.05) of an alkali solution (a 10 A) solution of NaOH in methanol) for saponification. One minute after adding the alkali, the gelated system was pulverized by a pulverizer, and left at 40 C. for one hour to promote saponification. Then, 1000 g of methyl acetate was added to neutralize the residual alkali. After confirming completion of neutralization using a phenolphthalein indicator, to the PVA as a white solid obtained by filtration was added 1000 g of methanol, and the mixture was left at room temperature for 3 hours for washing. After repeating the above washing operation three times, the PVA obtained by centrifugal deliquoring was left in an oven at 70 C. for 2 days to give a dry PVA (PVA-1).

(40) [Analysis of Vinyl Alcohol Polymer PVA-1]

(41) For the vinyl alcohol polymer having carboxyl groups or lactone rings obtained, a saponification degree was 98.5 mol %. Furthermore, the solution of the polyvinyl acetate in methanol was obtained by removing the unreacted vinyl acetate monomers after polymerization. Then, as reprecipitation purification, the solution was mixed with n-hexane to perform precipitation and the precipitate was dissolved in acetone. After repeating the reprecipitation purification three times, it was dried under a reduced pressure at 80 C. for 3 days to give a pure polyvinyl acetate. The polyvinyl acetate was dissolved in DMSO-D.sub.6, and was analyzed using 500 MHz proton NMR (JEOL Ltd.; GX-500) at 80 C. Thus, a content of ethylene units was 7 mol %. After the solution of the polyvinyl acetate in methanol was saponified with an alkaline molar ratio of 0.5, the product was pulverized, left at 60 C. for 5 hours for completing saponification and then extracted by methanol soxhlet for 3 days and then dried under a reduced pressure at 80 C. for 3 days to give a purified ethylene-modified PVA having carboxyl groups or lactone rings. An average polymerization degree of the PVA was 1000 as determined as usual in accordance with JIS K6726. For the purified PVA, a content of carboxyl groups or lactone rings, a content of 1,2-glycol bonds and a content of hydroxyl groups in chains of three consecutive hydroxyls were 0.246 mol %, 1.61 mol % and 87%, respectively, as determined by a 500 MHz proton NMR apparatus (JEOL Ltd.; GX-500). Furthermore, a 5% aqueous solution of the purified modified PVA was prepared and used for forming a cast film to a thickness of 10 m. The film was dried under a reduced pressure at 80 for one day and then a melting point of the PVA was 210 C. as measured using DSC (Mettler Inc., TA3000) in accordance with the method described above.

(42) [Synthesis and Analysis of Vinyl Alcohol Polymers PVA-2 to PVA-9]

(43) PVA-2 to PVA-9 were prepared as described for PVA-1, except that a process for producing a vinyl alcohol polymer was changed as shown in Table 2. The analysis results for the obtained PVAs are shown in Table 3.

(44) TABLE-US-00002 TABLE 2 Ethylene pressure Polymer- during Delay Initiator Polymer- Rate of Alkali ization polymer- Total Total ization Polymer- amount for temperature VAc MeOH ization Charge amount Charge amount time ization saponification ( C.) (kg) (kg) (kg/cm.sup.2) Type A) (g) (ml) Type B) (g) (ml) (hr) (%) (MR) PVA-1 60 107.2 42.8 5.9 MAn 15.6 1,400 AMV 204 640 4 30 0.05 PVA-2 60 107.2 42.8 5.9 AMV 200 600 3.5 35 0.05 PVA-3 60 107.2 42.8 5.9 IA 60 15,000 AMV 300 800 3.5 30 0.05 PVA-4 60 119.8 30.1 4.7 AMV 116 360 4 25 0.1 PVA-5 Identical to PVA-4 0.02 PVA-6 60 76.6 73.3 6.5 AMV 175 552 3 20 0.1 PVA-7 60 106.1 43.9 1.4 AMV 53 168 4 20 0.05 PVA-8 60 78.3 71.7 5.7 MAn 5.3 837 AMV 255 804 10 60 0.05 PVA-9 60 123 26.9 2.6 3MPA 2.3 1581 AMV 355 1118 7 50 0.05 A) MAn; Maleic anhydride IA; Itaconic acid 3MPA; 3-Mercaptopropionic acid B) AMV; 2,2-Azobis(4-methoxy-2,4-dimethylvaleronitrile)

(45) TABLE-US-00003 TABLE 3 Molar fraction of Content of Carboxylic Content of central OH groups modified Saponification acid + Melting 1,2-glycol in chains of three ethylene Polymerization degree lactone point bonds consecutive hydroxyls PVA (mol %) degree (mol %) (mol %) ( C.) (mol %) (mol %) PVA-1 7 1000 98.5 0.246 210 1.61 87 PVA-2 7 1000 98.5 0.035 213 1.61 89 PVA-3 7 1000 98.5 2.550 200 1.40 80 PVA-4 5 1500 99.5 0.041 224 1.66 90 PVA-5 5 1500 96.5 0.041 190 1.50 76 PVA-6 10 500 99.0 0.054 211 1.53 84 PVA-7 3 1500 98.5 0.031 230 1.73 95 PVA-8 10 400 96 0.166 189 1.28 79 PVA-9 3 500 97 0.277 207 1.66 88
[Synthesis and Analysis of Vinyl Alcohol Polymers PVA-10 to PVA-22]

(46) PVA-10 to PVA-22 were prepared as described for PVA-1, except that a process for producing a vinyl alcohol polymer was changed as shown in Table 4. The analysis results for the obtained PVAs are shown in Table 5.

(47) TABLE-US-00004 TABLE 4 Ethylene Polymer- pressure in Delay Initiator Polymer- Rate of Amount of ization polymer- Total Total ization Polymer- alkali for temperature VAc MeOH ization Charge amount Charge amount time ization saponification ( C.) (kg) (kg) (kg/cm.sup.2) Type A) (g) (ml) Type B) (g) (ml) (hr) (%) (MR) PVA-10 60 81.9 68 MAn 12.3 1375 AMV 224 705 4 40 0.05 PVA-11 60 81.9 68 MAn 12.3 1375 AMV 224 705 4 40 0.2 PVA-12 60 101.7 48.3 2.0 AMV 139 438 5 40 0.05 PVA-13 60 57.5 92.5 AMV 471 1484 5 60 0.05 PVA-14 60 81.9 68 10.2 MAn 12.3 1375 AMV 500 1500 4 30 0.1 PVA-15 60 107.2 42.8 5.9 IA 120 30,000 AMV 400 900 3.5 30 0.05 PVA-16 0 22.5 127.2 0.1 NPP 402 1446 10 75 0.01 PVA-17 Identical to PVA-1 0.015 PVA-18 Identical to PVA-1 0.013 PVA-19 20 23.1 126.8 0.70 NPP 198 714 12 75 0.1 PVA-20 20 55.9 93.6 5.8 NPP 710 2559 5 40 0.2 PVA-21 100 91.9 58.1 3.2 V-40 65 234 5 40 0.04 PVA-22 60 81.9 68 0.99 MAn 12.3 1375 AMV 330 1200 4 38 0.2 A) MAn; Maleic anhydride IA; Itaconic acid B) AMV; 2,2-Azobis(4-methoxy-2,4-dimethylvaleronitrile) NPP; n-Propyl peroxydicarbonate/N,N-dimethylaniline = 1/1 V-40; 1,1-Azobis(cyclohexane-1-carbonitrile)

(48) TABLE-US-00005 TABLE 5 Molar fraction of Content of Carboxylic Content of central OH groups modified Saponification acid + Melting 1,2-glycol in chains of three ethylene Polymerization degree lactone point bonds consecutive hydroxyls PVA (mol %) degree (mol %) (mol %) ( C.) (mol %) (mol %) PVA-10 0 1000 98.5 0.247 224 1.78 98 PVA-11 0 1000 99.9 0.247 235 1.8 99 PVA-12 1 1500 98.5 0.04 230 1.75 94 PVA-13 0 500 99 0.048 228 1.78 99 PVA-14 15 1000 98.5 0.250 190 1.40 75 PVA-15 7 1000 98.5 5.000 178 1.28 74 PVA-16 3 500 97.0 0.016 205 1.69 89 PVA-17 7 1000 93.0 0.246 175 1.45 77 PVA-18 7 1000 90.0 0.246 170 1.30 70 PVA-19 5 210 99 0.025 223 1.49 91 PVA-20 10 500 99.5 0.043 207 1.02 85 PVA-21 3 500 97.0 0.071 205 2.10 89 PVA-22 2 1000 99.9 0.220 231 1.75 92

Example 1

Preparation of A Composite Paper

(49) A 10% aqueous solution of vinyl alcohol polymer PVA-1 was prepared and applied to a base paper with a basis weight of 47 g/m.sup.2, a bulk density of 0.8 g/m.sup.2, an air permeability resistance of 200 sec, using a 2-roll type size press for testing (Kumagai Riki Kogyo Co., Ltd.). The application was conducted at 50 C. under the condition of 100 m/min, and then the paper was dried at 110 C. for 1 min to give a coated paper. The amount of the coating liquid in terms of solid was 1.8 g/m.sup.2 (both sides). The obtained coated paper was humidity-conditioned at 20 C. and 65% RH for 72 hours, to prepare a composite paper.

(50) [Evaluation of a Composite Paper]

(51) For the composite paper thus obtained, oil resistance, practical water resistance, air permeability resistance, water vapor transmission rate and water-resistant surface strength were measured as described above. In the evaluation of oil resistance, a kit value was 9. In the evaluation of practical oil resistance, permeation was not observed until a mixed solution (C*) assuming an animal oil in a test of resistance to a fatty acid mixture. Furthermore, in a test of resistance to oleic acid, permeation was not observed, so that it was judged to be positive, that is, sufficiently high resistance. A test of resistance to a hot corn oil was negative. An air permeability resistance was 100,000 sec or more, a water vapor transmission rate was 2,630 g/m.sup.2, a water-resistant surface strength was 3, and practical water resistance was rated as D.

Examples 2 to 21

(52) A coated paper was prepared as described in Example 1, except that an oil-resistant layer had a composition as shown in Table 6, and the composite paper was evaluated. The results are shown in Table 6.

(53) As shown in Table 6, a composite paper containing a predetermined range of vinyl alcohol polymer of the present invention shows good results in any evaluation of oil resistance, water vapor permeability, air permeability resistance, practical water resistance, and water-resistant surface strength.

Comparative Examples 1 to 19

(54) A coated paper was prepared as described in Example 1, except that an oil-resistant layer had a composition as shown in Table 7, and the composite paper was evaluated. The results are shown in Table 7.

(55) TABLE-US-00006 TABLE 6 Composition of an oil-resistant layer Crosslinking Fluorine Base Base Coating PVA agent oil-repellent paper air paper amount amount amount agent .sup.E) permeability bulk both PVA (parts by Crosslinking (parts by (parts by resistance density sides type weight) agent type weight) weight) (sec) (g/cm.sup.3) (g/m.sup.2) Example 1 PVA-1 100 200 0.8 1.8 Example 2 PVA-1 100 Glyoxal .sup.A) 5 200 0.8 2.0 Example 3 PVA-1 100 Polyamide 20 200 0.8 2.5 epichlorohydrin .sup.B) Example 4 PVA-1 100 Zirconium 5 200 0.8 2.4 ammonium carbonate .sup.C) Example 5 PVA-1 100 Zirconium 5 200 0.8 2.4 oxynitrate .sup.D) Example 6 PVA-2 100 200 0.8 1.8 Example 7 PVA-3 100 Polyamide 20 200 0.8 2.1 epichlorohydrin .sup.B) Example 8 PVA-3 100 Zirconium 5 200 0.8 2.1 oxynitrate .sup.D) Example 9 PVA-4 100 15 0.7 7.0 Example 10 PVA-4 100 Polyamide 20 15 0.7 7.5 epichlorohydrin .sup.B) Example 11 PVA-5 100 15 0.7 6.0 Example 12 PVA-5 100 Polyamide 20 15 0.7 6.2 epichlorohydrin .sup.B) Example 13 PVA-5 100 Zirconium 5 15 0.7 6.5 oxynitrate .sup.D) Example 14 PVA-6 100 700 0.8 1.5 Example 15 PVA-7 100 700 0.8 1.0 Example 16 PVA-8 100 700 0.8 1.5 Example 17 PVA-8 100 Polyamide 20 700 0.8 1.5 epichlorohydrin .sup.B) Example 18 PVA-9 100 700 0.8 1.6 Example 19 PVA-1 100 10 15 0.7 2.8 Example 20 PVA-1 100 20 15 0.7 1.7 Example 21 PVA-1 100 Polyamide 20 10 15 0.7 2.8 epichlorohydrin .sup.B) Evaluation of composite paper Fatty Air- Water vapor Practical Water- acid permeation transmission water- resistant Kit mixture Oleic-acid Hot corn resistance rate resistance surface value test Resistance oil test (sec) (g/m.sup.2) evaluation strength Example 1 9 C* Positive Negative >100,000 2,630 D 3 Example 2 9 C* Positive Negative >100,000 2,500 D 3 Example 3 12 D* Positive Positive >100,000 2,800 C 5 Example 4 9 C* Positive Negative >100,000 2,890 C 4 Example 5 9 C* Positive Negative >100,000 2,740 B 5 Example 6 9 C* Positive Negative >100,000 2,580 D 4 Example 7 12 D* Positive Positive >100,000 3,120 B 5 Example 8 9 C* Positive Negative >100,000 3,320 B 5 Example 9 7 C* Positive Negative 990,000 1,550 C 4 Example 10 8 C* Positive Negative >100,000 1,480 C 5 Example 11 7 C* Positive Negative >100,000 2,070 D 3 Example 12 8 C* Positive Negative >100,000 1,940 C 5 Example 13 7 C* Positive Negative >100,000 1,980 B 5 Example 14 12 D* Positive Positive >100,000 4,000 C 4 Example 15 12 D* Positive Positive >100,000 4,220 C 4 Example 16 12 D* Positive Positive >100,000 4,000 D 3 Example 17 12 D* Positive Positive >100,000 3,850 B 5 Example 18 12 C* Positive Negative >100,000 4,060 C 3 Example 19 12 E* Positive Positive 70 >5000 B 3 Example 20 10 E* Positive Positive 40 >5000 A 4 Example 21 12 E* Positive Positive 75 >5000 A 5 .sup.A) from BASF .sup.B) Polycup 172 from Ashland Inc. .sup.C) Bacote-20 from MEL Chemicals Inc. .sup.D) Zircosole ZN from Daiichi Kigenso Kagaku Kogyo Co., Ltd. .sup.E) PT-5045 from Solvay

(56) TABLE-US-00007 TABLE 7 Composition of an oil-resistant layer Crosslinking Fluorine Base Base Coating PVA agent oil-repellent paper air paper amount amount amount agent .sup.E) permeability bulk both PVA (parts by Crosslinking (parts by (parts by resistance density sides type weight) agent type weight) weight) (sec) (g/cm.sup.3) (g/m.sup.2) Comparative PVA-10 100 200 0.8 1.8 Example 1 Comparative PVA-10 100 Polyamide 20 200 0.8 2.5 Example 2 epichlorohydrin .sup.B) Comparative PVA-11 100 200 0.8 2.0 Example 3 Comparative PVA-12 100 15 0.7 7.0 Example 4 Comparative PVA-12 100 Polyamide 20 15 0.7 7.5 Example 5 epichlorohydrin .sup.B) Comparative PVA-13 100 700 0.8 1.0 Example 6 Comparative PVA-14 100 200 0.8 cannot be applied on a Example 7 base paper because PVA-14 is insoluble in water Comparative PVA-15 100 200 0.8 2.0 Example 8 Comparative PVA-15 100 Polyamide 20 200 0.8 2.4 Example 9 epichlorohydrin .sup.B) Comparative PVA-15 100 Zirconium 5 200 0.8 2.1 Example 10 oxynitrate .sup.D) Comparative PVA-16 100 200 0.8 2.0 Example 11 Comparative PVA-17 100 200 0.8 2.2 Example 12 Comparative PVA-18 100 200 0.8 2.5 Example 13 Comparative PVA-19 100 200 0.8 2.4 Example 14 Comparative PVA-20 100 200 0.8 cannot be applied on a Example 15 base paper because a filamentous substance precipitates during coating Comparative PVA-21 100 200 0.8 2.0 Example 16 Comparative PVA-22 100 200 0.8 cannot be applied on a Example 17 base paper because a filamentous substance precipitates during coating Comparative PVA-1 100 200 0.8 11 Example 18 Comparative PVA-1 100 200 0.8 0.08 Example 19 Evaluation of composite paper Fatty Air- Water vapor Practical Water- acid permeation transmission water- resistant Kit mixture Oleic-acid Hot corn resistance rate resistance surface value test Resistance oil test (sec) (g/m.sup.2) evaluation strength Comparative 8 A* Negative Negative >100,000 3,400 D 2 Example 1 Comparative 8 A* Negative Negative >100,000 3,140 D 3 Example 2 Comparative 8 A* Negative Negative >100,000 2,980 D 2 Example 3 Comparative 5 Negative Negative Negative 48,000 6,800 D 2 Example 4 Comparative 5 Negative Negative Negative 52,000 6,720 D 3 Example 5 Comparative 5 Negative Negative Negative 45,000 4,500 D 2 Example 6 Comparative cannot be applied on a base paper because PVA-14 is insoluble in water Example 7 Comparative 8 B* Positive Negative >100,000 3,540 D 1 Example 8 Comparative 9 B* Positive Negative >100,000 3,310 D 2 Example 9 Comparative 8 B* Positive Negative >100,000 3,280 D 2 Example 10 Comparative 7 A* Negative Negative >100,000 2,530 D 3 Example 11 Comparative 9 A* Negative Negative >100,000 3,310 D 1 Example 12 Comparative 9 A* Negative Negative >100,000 3,670 D 1 Example 13 Comparative 4 Negative Negative Negative 72,000 3,500 D 2 Example 14 Comparative cannot be applied on a base paper because a filamentous substance precipitates during coating Example 15 Comparative 7 A* Negative Negative >100,000 3,060 D 2 Example 16 Comparative cannot be applied on a base paper because a filamentous substance precipitates during coating Example 17 Comparative 9 C* Positive Negative >100,000 <1000 D 2 Example 18 Comparative 1 Negative Negative Negative 4,300 >5,000 D 3 Example 19 .sup.B) Polycup 172 from Ashland Inc. .sup.D) Zircosole ZN from Daiichi Kigenso Kagaku Kogyo Co., Ltd. .sup.E) PT-5045 from Solvay

(57) Comparative Examples 1 to 6 show the evaluation results of composite papers containing a vinyl alcohol polymer with an ethylene content of less than 2 mol %. In all cases, resistance to oleic acid (60 C.) or resistance to hot corn oil (110 C.) as an indicator of oil resistance at a high temperature was not observed, and water-resistant surface strength is insufficient without adding a cross-linking agent.

(58) In Comparative Example 7, the use of a vinyl alcohol polymer with an ethylene content of more than 10 mol % was attempted, but a composite paper cannot be produced due to the presence of insoluble components during preparing a coating liquid.

(59) Comparative Examples 8 to 10 show the evaluation results of composite papers with a total content of carboxyl groups and lactone rings of more than 3 mol %. In all cases, water-resistant surface strength is insufficient.

(60) Comparative Example 11 shows the evaluation results of a composite paper containing a vinyl alcohol polymer with a total content of carboxyl groups and lactone rings of less than 0.02 mol %, and resistance to oleic acid or hot corn oil was not observed.

(61) Comparative Examples 12 and 13 show the evaluation results of composite papers containing a vinyl alcohol polymer with a saponification degree of less than 95 mol % and a melting point of lower than 180 C. In both cases, water-resistant surface strength was insufficient.

(62) Comparative Example 14 shows the evaluation results of a composite paper containing a vinyl alcohol polymer with a polymerization degree of less than 300, and its kit value is low, so that resistance to a fatty acid mixture, oleic acid or hot corn oil is not observed. Furthermore, water-resistant surface strength is also insufficient.

(63) In Comparative Example 15, the use of a vinyl alcohol polymer with a content of 1,2-glycol bonds of less than 1.2 mol % was attempted, but a filamentous substance precipitated in the coating liquid, so that a composite paper could not be stably obtained.

(64) Comparative Example 16 shows the evaluation results of a composite paper containing a vinyl alcohol polymer with a content of 1,2-glycol bonds of more than 2.0 mol %, and resistance to oleic acid or hot corn oil is not observed and water-resistant surface strength is insufficient.

(65) In Comparative Example 17, the use of a vinyl alcohol polymer with a saponification degree of more than 99.5 mol % and a melting point of higher than 230 C. was attempted, but a filamentous substance precipitated in the coating liquid, so that a composite paper could not be stably obtained.

(66) Comparative Example 18 shows the evaluation results of a composite paper to which a predetermined range of vinyl alcohol polymer of the present invention is applied in an amount of more than 10.0 g/m.sup.2, and water vapor transmission rate is as insufficient as 950 g/m.sup.2 and furthermore, water-resistant surface strength is insufficient.

(67) Comparative Example 19 shows the evaluation results of a composite paper to which a predetermined range of vinyl alcohol polymer of the present invention is applied in an amount of less than 0.5 g/m.sup.2, and oil resistance is insufficient.

Example 22

Preparation of a Dispersion of a Layered Inorganic Compound

(68) Kaolin-1 (BARRISURF HX from Imerys Minerals Japan K. K.; average particle size: 1.5 m, average aspect ratio: 100) was dispersed in water to a concentration of 40%, which was then processed by a domestic mixer for 10 min, to prepare a dispersion. For determining an average particle size, a dispersion obtained was diluted with ion-exchanged water to 0.05% by mass, and grain size distribution was measured by a laser diffraction particle size analyzer (Shimadzu Corporation: SALD-2200) and an average was calculated as an average particle size.

(69) [Preparation of a Coating Liquid]

(70) A 14% aqueous solution of vinyl alcohol polymer PVA-1 was prepared. The aqueous solution of vinyl alcohol polymer was mixed with the above kaolin dispersion, such that kaolin content became 40 parts based on 100 parts of vinyl alcohol polymer. Then, water was added to the mixture such that a solid concentration became 15% to prepare a coating liquid.

(71) [Preparation of a Composite Paper]

(72) The coating liquid obtained above was applied to a base paper A (a base paper with a basis weight of 70 g/m.sup.2, a bulk density of 0.7 g/cm.sup.3, and an air permeability resistance of 15 sec), using a 2-roll type size press for testing (Kumagai Riki Kogyo Co., Ltd.). The application was conducted at 50 C. under the condition of 100 m/min, and then the paper was dried at 110 C. for 1 min to give a coated paper. The amount of the coating liquid in terms of solid was 5.8 g/m.sup.2 (both sides). The obtained coated paper was humidity-conditioned at 20 C. and 65% RH for 72 hours, to prepare a composite paper.

(73) [Evaluation of a Composite Paper]

(74) For the composite paper thus obtained, oil resistance, practical water resistance, air permeability resistance, water vapor transmission rate and water-resistant surface strength were measured as described above. In the evaluation of oil resistance, a kit value was 8. In the evaluation of practical oil resistance, permeation was not observed until a mixed solution (C*) assuming an animal oil in a test of resistance to a fatty acid. Furthermore, a test of resistance to oleic acid was judged to be positive. In a test of resistance to hot corn oil, permeation was not observed, so that it was judged to be positive, that is, sufficiently high resistance. An air permeability resistance was 80,000 sec, and a water vapor transmission rate was 2,100 g/m.sup.2. Furthermore, practical water resistance was rated as A because a croute of a steamed meat bun did not adhere to the coating surface. A water-resistant surface strength was rated as 5.

Examples 22 to 49

(75) Composite papers were prepared and evaluated as described in Example 22, except that a composition of an oil-resistant layer was changed as shown in Table 8. The results are shown in Table 8. Details of the layered inorganic compounds in the table are as follows. Kaolin-2 (BARRISURF LX from Imerys Minerals Japan K. K.: average particle size: 1.5 m, aspect ratio: 60) Kaolin-3 (Eckalite120 from Imerys Minerals Japan K. K.: average particle size: 1.6 m, aspect ratio: 30) Kaolin-4 (Flat DS from Imerys Minerals Japan K. K.: average particle size: 4 m, aspect ratio: 8) Talc (EX-15 from Yamaguchi Mica Co., Ltd.: average particle size: 15 m, aspect ratio: 20) Montmorillonite (Kunipia from Kunimine Industries CO., Ltd.: average particle size: 0.1 to 0.5 m, aspect ratio: 200)

(76) As shown in Table 8, composite papers containing a predetermined range of vinyl alcohol polymer and a particular layered inorganic compound of the present invention exhibited good results in all evaluations of oil resistance, water vapor permeability, air permeability resistance, practical water resistance and water-resistant surface strength.

Comparative Examples 20 to 34

(77) Composite papers were prepared and evaluated as described in Example 22, except that a composition of an oil-resistant layer was changed as shown in Table 9. The results are shown in Table 9.

(78) TABLE-US-00008 TABLE 8 Composition of an oil-resistant layer Inorganic Additive Base Base Coating PVA Inorganic compound amount paper air paper amount amount compound amount (parts permeability bulk both PVA (parts by Inorganic Aspect (parts by Additive by resistance density sides type weight) compound ratio mass) type mass) (sec) (g/cm.sup.3) (g/m.sup.2) Example 22 PVA-1 100 Kaolin-1 100 40 15 0.7 5.8 Example 23 PVA-1 100 Kaolin-1 100 10 15 0.7 6.4 Example 24 PVA-1 100 Kaolin-1 100 25 15 0.7 6.2 Example 25 PVA-1 100 Kaolin-1 100 60 15 0.7 5.5 Example 26 PVA-1 100 Kaolin-1 100 180 15 0.7 3.8 Example 27 PVA-1 100 Kaolin-1 100 40 Fatty acid 20 15 0.7 6.0 sizing agent .sup.A) Example 28 PVA-1 100 Kaolin-1 100 40 Polyamide 20 15 0.7 5.8 epichlorohydrin .sup.B) Example 29 PVA-1 100 Kaolin-1 100 40 Zirconium 5 15 0.7 5.6 oxynitrate .sup.C) Example 30 PVA-1 100 Kaolin-2 60 40 200 0.8 2.1 Example 31 PVA-1 100 Kaolin-3 30 40 200 0.8 2.2 Example 32 PVA-1 100 Talc 20 40 200 0.8 1.9 Example 33 PVA-1 100 Montmorillonite 200 40 200 0.8 2.4 Example 34 PVA-2 100 Kaolin-1 100 40 15 0.7 5.9 Example 35 PVA-3 100 Kaolin-1 100 40 15 0.7 5.8 Example 36 PVA-3 100 Kaolin-1 100 40 Fatty acid 20 15 0.7 6.1 sizing agent .sup.A) Example 37 PVA-4 100 Kaolin-1 100 40 15 0.7 5.9 Example 38 PVA-4 100 Kaolin-1 100 40 Fatty acid 20 15 0.7 6.1 sizing agent .sup.A) Example 39 PVA-5 100 Kaolin-1 100 40 15 0.7 5.9 Example 40 PVA-5 100 Kaolin-1 100 40 Fatty acid 20 15 0.7 6.1 sizing agent .sup.A) Example 41 PVA-5 100 Kaolin-1 100 40 Polyamide 20 15 0.7 5.9 epichlorohydrin .sup.B) Example 42 PVA-6 100 Kaolin-1 100 40 700 0.8 2.1 Example 43 PVA-7 100 Kaolin-1 100 40 700 0.8 1.2 Example 44 PVA-8 100 Kaolin-1 100 40 700 0.8 1.8 Example 45 PVA-8 100 Kaolin-1 100 40 700 0.8 1.8 Example 46 PVA-9 100 Kaolin-1 100 40 700 0.8 2.0 Example 47 PVA-1 100 Kaolin-1 100 5 15 0.7 4.9 Example 48 PVA-1 100 Kaolin-1 100 220 15 0.7 3.4 Example 49 PVA-1 100 Kaolin-4 8 40 15 0.7 5.3 Evaluation of composite paper Fatty Air- Water vapor Practical Water- acid permeation transmission water- resistant Kit mixture Oleic-acid Hot corn resistance rate resistance surface value test Resistance oil test (sec) (g/m.sup.2) evaluation strength Example 22 8 C* Positive Positive 80,000 2,100 A 5 Example 23 5 A* Positive Negative 50,000 3,050 B 4 Example 24 7 B* Positive Negative 65,000 2,800 B 5 Example 25 8 C* Positive Positive 82,000 1,400 A 5 Example 26 9 D* Positive Positive 60,000 2,400 A 5 Example 27 10 D* Positive Positive 53,000 >5000 A 5 Example 28 9 D* Positive Positive 55,000 3,600 A 5 Example 29 8 D* Positive Positive 60,000 3,400 A 5 Example 30 10 D* Positive Positive <100,000 1,750 A 5 Example 31 9 C* Positive Positive 80,000 2,120 B 4 Example 32 9 C* Positive Positive 80,000 1,890 B 4 Example 33 10 D* Positive Positive <100,000 1,250 A 5 Example 34 8 C* Positive Positive 73,000 2,350 B 4 Example 35 8 C* Positive Positive 71,000 2,400 A 5 Example 36 11 E* Positive Positive 64,000 4,600 A 5 Example 37 9 D* Positive Positive 82,000 2,900 A 5 Example 38 10 D* Positive Positive 69,000 >5000 A 5 Example 39 8 C* Positive Positive 90,000 3,100 B 4 Example 40 10 D* Positive Positive 65,000 >5000 A 5 Example 41 9 C* Positive Positive 72,000 4,400 A 5 Example 42 12 D* Positive Positive 90,000 3,700 A 5 Example 43 12 E* Positive Positive <100,000 2,100 A 5 Example 44 12 E* Positive Positive <100,000 4,300 A 5 Example 45 12 E* Positive Positive <100,000 3,900 A 5 Example 46 12 E* Positive Positive <100,000 3,450 A 5 Example 47 3 A* Positive Negative 31,000 3,300 D 3 Example 48 4 A* Positive Negative 45,000 2,900 B 4 Example 49 2 A* Positive Negative 30,000 3,200 B 4 .sup.A) NS-815 from TOHO Chemical Industry Co., Ltd. .sup.B) Polycup 172 from Ashland Inc.. .sup.C) Zircosole ZN from Daiichi Kigenso Kagaku Kogyo Co., Ltd.

(79) TABLE-US-00009 TABLE 9 Composition of an oil-resistant layer Inorganic Base Base Coating PVA Inorganic compound Additive paper air paper amount amount compound amount amount permeability bulk both PVA (parts by Inorganic Aspect (parts by Additive (parts by resistance density sides type weight) compound ratio mass) type mass) (sec) (g/cm.sup.3) (g/m.sup.2) Comparative PVA-10 100 Kaolin-1 100 40 15 0.7 6.2 Example 20 Comparative PVA-11 100 Kaolin-1 100 40 15 0.7 6.1 Example 21 Comparative PVA-12 100 Kaolin-1 100 40 15 0.7 6.0 Example 22 Comparative PVA-13 100 Kaolin-1 100 40 700 0.8 2.2 Example 23 Comparative PVA-14 100 Kaolin-1 100 40 15 0.7 cannot be applied on a Example 24 base paper because PVA-14 is insoluble in water Comparative PVA-15 100 Kaolin-1 100 40 15 0.7 6.1 Example 25 Comparative PVA-16 100 Kaolin-1 100 40 700 0.8 2.0 Example 26 Comparative PVA-17 100 Kaolin-1 100 40 200 0.8 2.4 Example 27 Comparative PVA-18 100 Kaolin-1 100 40 200 0.8 2.6 Example 28 Comparative PVA-19 100 Kaolin-1 100 40 200 0.8 3.7 Example 29 Comparative PVA-20 100 Kaolin-1 100 40 200 0.8 cannot be applied on a Example 30 base paper because a filamentous substance precipitates during coating Comparative PVA-21 100 Kaolin-1 100 40 200 0.8 3.6 Example 31 Comparative PVA-22 100 Kaolin-1 100 40 200 0.8 cannot be applied on a Example 32 base paper because a filamentous substance precipitates during coating Comparative PVA-1 100 Kaolin-2 30 40 200 0.8 0.08 Example 33 Comparative PVA-1 100 Kaolin-2 30 40 200 0.8 21** Example 34 Evaluation of composite paper Fatty Air- Water vapor Practical Water- acid permeation transmission water- resistant Kit mixture Oleic-acid Hot corn resistance rate resistance surface value test Resistance oil test (sec) (g/m.sup.2) evaluation strength Comparative 5 A* Negative Negative 3,100 4,800 C 3 Example 20 Comparative 5 A* Negative Negative 2,400 4,300 C 3 Example 21 Comparative 5 A* Negative Negative 3,200 4,750 C 3 Example 22 Comparative 6 A* Negative Negative 3,050 4,840 C 3 Example 23 Comparative cannot be applied on a base paper because PVA-14 is insoluble in water Example 24 Comparative 8 B* Positive Negative 63,000 2,700 C 3 Example 25 Comparative 6 A* Negative Negative 51,000 3,200 B 4 Example 26 Comparative 6 A* Negative Negative 65,000 2,900 B 4 Example 27 Comparative 6 A* Negative Negative 72,000 2,300 B 4 Example 28 Comparative 5 A* Negative Negative 54,000 4,000 C 3 Example 29 Comparative cannot be applied on a base paper because a filamentous substance precipitates during coating Example 30 Comparative 4 A* Negative Negative 56,000 3,850 C 3 Example 31 Comparative cannot be applied on a base paper because a filamentous substance precipitates during coating Example 32 Comparative 1 Negative Negative Negative 3,200 >5000 D 3 Example 33 Comparative 8 A* Negative Negative >100,000 <1000 B 4 Example 34 **Uneven coating

(80) Comparative Examples 20 to 23 show the evaluation results of composite papers containing a vinyl alcohol polymer with an ethylene content of less than 2 mol %. In any case, a kit value was 5 to 6, indicating medium oil resistance, but high practical oil resistance at a high temperature was not observed and water resistance was insufficient.

(81) In Comparative Example 24, the use of a vinyl alcohol polymer with an ethylene content of more than 10 mol % was attempted, but a composite paper could not be prepared due to the presence of unsolved components during preparing a coating liquid.

(82) Comparative Example 25 shows the evaluation results of a composite paper containing a vinyl alcohol polymer with a total content of carboxyl groups and lactone rings of more than 3 mol %. Water resistance was insufficient.

(83) Comparative Example 26 shows the evaluation results of a composite paper containing a vinyl alcohol polymer with a total content of carboxyl groups and lactone rings of less than 0.02 mol %, but the layered inorganic compound precipitated due to insufficient dispersibility of the coating liquid, leading to tendency to uneven coating. Thus, resistance to corn oil at a high temperature is not observed.

(84) Comparative Examples 27 and 28 show the evaluation results of composite papers containing a vinyl alcohol polymer with a saponification degree of less than 95 mol % and a melting point of lower than 180 C. In both cases, water resistance is insufficient.

(85) Comparative Example 29 shows the evaluation results of a composite paper containing a vinyl alcohol polymer with a polymerization degree of less than 300, but resistance to a fatty acid mixture at a high temperature is low and resistance to corn oil is not observed. Also, water resistance is insufficient.

(86) In Comparative Example 30, the use of a vinyl alcohol polymer with a content of 1,2-glycol bonds of less than 1.2 mol % was attempted, but a filamentous substance precipitated in the coating liquid and thus a composite paper was not stably produced.

(87) Comparative Example 31 shows the evaluation results of a composite paper containing a vinyl alcohol polymer with a content of 1,2-glycol bonds of more than 2.0 mol %, but resistance to a fatty acid mixture at a high temperature is low, resistance to corn oil is not observed, and water resistance is insufficient.

(88) In Comparative Example 32, the use of a vinyl alcohol polymer with a saponification degree of more than 99.5 mol % and a melting point of higher than 230 C. was attempted, but a filamentous substance precipitated in the coating liquid, and thus a composite paper was not stably produced.

(89) Comparative Example 33 shows the evaluation results of a composite paper to which a predetermined range of vinyl alcohol polymer of the present invention was applied in an amount of less than 0.1 g/m.sup.2, and oil resistance is insufficient.

(90) Comparative Example 34 shows the evaluation results of a composite paper to which a predetermined range of vinyl alcohol polymer of the present invention was applied in an amount of 10 g/m.sup.2 or more per one side, and resistance to a fatty acid mixture at a high temperature is low and resistance to corn oil is not observed.

INDUSTRIAL USABILITY

(91) A composite paper of the present invention can keep practically acceptable oil resistance even when it wraps a hot and oily food and exhibits excellent water resistance even when it wraps a steamy food, and it is, therefore, useful for providing a practically useful greaseproof paper for a wrapping or package for various fried foods and fat-containing foods.