JPH05301975A - Sheet - Google Patents

Abstract

(57) [Summary] [Structure] PVA (A) having a syndiotacticity of 55% or more and a saponification degree of 10 mol% or more and less than 90 mol% as indicated by a diad, and a water-soluble polyhydric alcohol plasticizer (B). And a sheet comprising a water-insoluble ester plasticizer (C). [Effect] The sheet of the present invention has a conventional atactic P
Compared with the sheet obtained by using VA, the humidity dependence of the morphology is small, the humidity dependence of mechanical properties is small, the water resistance is excellent, the Young's modulus of the sheet is high, and the tensile strength is high. Since it has excellent characteristics such that it is not easily attacked by organic solvents, mineral oils, vegetable oils, etc., it is useful for a wide range of applications such as conveyor belts, conduction belts, cushioning materials, and vibration damping materials.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyvinyl alcohol-based sheet, particularly a conveyor, which has a low elongation and a high strength, is flexible, and is excellent in water resistance (temperature and humidity dependence of morphology, humidity dependence of mechanical properties). Belt, conduction belt, cushioning material,
A sheet suitable for a damping material.

[0002]

2. Description of the Related Art Polyvinyl alcohol-based sheets have a high Young's modulus, a high tensile strength, and can be softened by adding a small amount of plasticizer, are hard to be charged, and are susceptible to organic solvents, mineral oil, vegetable oil, etc. Due to its characteristics such as difficulty, it is widely used in conveyor belts, conduction belts, cushioning materials and the like. However, the sheet obtained by molding conventional polyvinyl alcohol has low water resistance due to high solubility of polyvinyl alcohol in water, and also has a large humidity dependency of the form, so that it can be used only under limited conditions. I couldn't use it.

For this purpose, a method of adding particles of a hydrophobic thermoplastic resin (Japanese Patent Publication No. 48-38468), a method of adding fats and oils or a wax (Japanese Patent Publication No. 40-40468), and a long direction oriented in parallel in one direction. A method in which a non-woven fabric having a layer of fibers or yarns and a composition of hydrophobic thermoplastic resin particles, fats or waxes are used in combination (Japanese Patent Publication No. 48-4295).
1), a method in which a non-woven fabric made of polyvinyl alcohol fibers superposed on both surfaces of a layer of filaments or threads oriented in parallel in one direction is used in combination (Japanese Patent Publication No. Sho 49-12158),
A method of using a non-woven fabric superposed on both surfaces of a layer of filaments or threads oriented in parallel in one direction (JP-B-49-12).
159) and other improved methods have been proposed. However, the method of adding particles of other thermoplastic resin, fats and oils, or wax to polyvinyl alcohol has a problem that the characteristics originally possessed by polyvinyl alcohol may be impaired and the processability is deteriorated. In addition, the method of using a layer or nonwoven fabric of parallel-oriented long fibers or yarns in combination has a large humidity dependency of the form in the conventional polyvinyl alcohol sheet, and therefore, the parallel-oriented long fibers or yarns of normal thickness are used. When the layer and the non-woven fabric are used together, the morphological change cannot be sufficiently suppressed and curling occurs in the length direction or the width direction, so that there is a problem that the range of application is limited.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyvinyl alcohol-based sheet which has a low morphological dependence on temperature and humidity, a small humidity dependence on mechanical properties, and a good water resistance.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that syndiotacticity by diad display is 55% or more and saponification degree is 10 mol% or more and less than 90 mol%. The present invention has been completed by finding a sheet comprising the polyvinyl alcohol (A), the water-soluble polyhydric alcohol plasticizer (B), and the water-insoluble ester plasticizer (C).

The polyvinyl alcohol (A) of the present invention is
Syndiotacticity indicated by diad (hereinafter syndiotacticity means indicated by diad) is 55% or more and saponification degree is 10 mol% or more 90.
It is less than mol% of syndiotactic polyvinyl alcohol (hereinafter abbreviated as S-PVA). The syndiotacticity of the polyvinyl alcohol (A) needs to be 55% or more, preferably 58% or more, more preferably 60% or more. Increasing syndiotacticity is effective in improving strength, water resistance and heat resistance,
If the syndiotacticity is too high, problems will occur in the sheet manufacturing process and the production of S-PVA itself will be difficult, so the syndiotacticity is 70%.
The following are preferred.

The degree of saponification of S-PVA is 10 mol% or more 9
It is necessary to be 0 mol% or less, and particularly 50 mol% or more and less than 90 mol% is preferable for the purpose of improving heat resistance, water resistance and flexibility, and particularly for the purpose of improving flexibility. Therefore, 30 to 70 mol% is preferable. Here, the degree of saponification represents the ratio of vinyl alcohol units after saponification to units that can be converted into vinyl alcohol units by saponification in a homopolymer or copolymer of vinyl ester such as vinyl pivalate. The residue is a vinyl ester unit such as a vinyl pivalate unit.

The degree of polymerization of S-PVA is appropriately selected depending on the application of the sheet, but it is 5 from the viewpoint of the strength and processing characteristics of the sheet.
00 or more is preferable, 1000 or more is more preferable,
Even more preferably 1500 or more. The upper limit of the degree of polymerization is not particularly limited, but it is preferably 30,000 or less from the viewpoint of processing characteristics such as molding of S-PVA into a sheet state and press stretching. Here, the degree of polymerization of S-PVA is such that polyvinyl acetate obtained by completely saponifying the polyvinyl alcohol-based polymer and then acetylating it has an intrinsic viscosity (30
It is represented by the viscosity average degree of polymerization determined from (measured at ° C) and is a value calculated by the following formula. P = ([η] × 1000 / 7.94) ↑ (1 / 0.62)

The method for producing S-PVA is not particularly limited, but the method disclosed in JP-A-3-121102 is preferred. That is, a method of saponifying a vinyl ester-based polymer obtained by homopolymerization of vinyl pivalate or copolymerization of vinyl pivalate and vinyl acetate in the absence of oxygen is preferable.

The water-soluble polyhydric alcohol plasticizer (B) (hereinafter abbreviated as plasticizer (B)) of the present invention is a substantially water-soluble plasticizer having two or more hydroxyl groups. If there is no particular restriction. Specific examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, propylene glycol, 2,3-butanediol, 1,3-butanediol. , Glycerin, petriol (3-methylpentane-
1,3,5-triol) and the like. Among these polyhydric alcohol plasticizers (B), glycerin,
Most preferred are 1,3-butanediol, petriol and mixtures thereof.

The water-insoluble ester plasticizer (C) of the present invention (hereinafter abbreviated as plasticizer (C)) is substantially water-insoluble and is particularly preferably any plasticizer having an ester bond. There is no limit. Specific examples thereof include dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-phthalate.
Ethylhexyl, diisooctyl phthalate, dioctyl phthalate, dinonyl phthalate, diisodecyl phthalate,
Phthalate ester plasticizers such as diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butylbenzyl phthalate, butyllauryl phthalate, tributyl phosphate, trioctyl phosphate, tricresyl phosphate, triphenyl phosphate, triphenyl phosphate. Phosphate ester plasticizers such as ethyl and cresyl diphenyl phosphate,
Dioctyl succinate, diisodecyl succinate, dioctyl adipate, diisodecyl adipate, dioctyl azelate, dibutyl sebacate, dioctyl sebacate, dioctyl tetrahydrophthalate, dioctyl tetrahydrophthalate, and other dibasic ester plasticizers, tri Aromatic carboxylic acid ester plasticizers such as trioctyl melitate, diethylene glycol dibenzoate, and octyl oxybenzoate, butyl oleate, tetrahydrofurfuryl oleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triester Fatty acid ester plasticizers such as acetyl and tributyrin, polypropylene adipate, polypropylene sebacate, polyesters such as phthalate polyester Ester plasticizers such as ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, tributyl acetyl citrate, diethylene glycol dibenzolyate, diethylene glycol di2-ethyl butyrate, triethylene glycol di2-ethyl butyrate Is mentioned. Among these ester plasticizers (C), phthalic acid ester plasticizers, phosphoric acid ester plasticizers, and mixtures thereof are most preferable.

There is no particular limitation on the mixing ratio of the water-soluble polyhydric alcohol plasticizer (B) and the water-insoluble ester plasticizer (C) to S-PVA (A), but from the viewpoint of the strength of the sheet. , The total amount of the plasticizer (B) and the plasticizer (C) is 5 to 10 parts by weight of S-PVA (A).
0 parts by weight is preferable, 5 to 70 parts by weight is more preferable,
5 to 50 parts by weight is more preferable, 5 to 30 parts by weight is more preferable, and 10 to 30 parts by weight is particularly preferable. If the total amount of the plasticizer (B) and the plasticizer (C) is larger than 100 parts by weight, the strength of the sheet may be significantly reduced, or other materials may be contaminated due to migration of the plasticizer. is there. Further, when the total amount of the plasticizer (B) and the plasticizer (C) is less than 5 parts by weight, the flexibility of the sheet is lowered, the flexibility of the sheet is lowered,
May become brittle at low temperatures.

The blending ratio [(B) / (C)] of the plasticizer (B) and the plasticizer (C) is not particularly limited, but is 5/9.
5 to 95/5 are preferable, and 20/80 to 80/20 are even more preferable. If the amount is out of the above range, either moldability or sheet flexibility may be insufficient.

The sheet comprising the S-PVA (A), the water-soluble polyhydric alcohol plasticizer (B) and the water-insoluble ester plasticizer (C) of the present invention is in a range that does not impair the effects of the present invention. In, it is preferable that water is contained, and the water content is preferably an equilibrium water content. When the sheet contains the equilibrium water content, the sheet properties are particularly improved. Other compounding ingredients include vegetable oils such as soybean oil, rapeseed oil, linseed oil, castor oil or processed oils thereof, various mineral oils, various oils such as animal oils, and inorganic compounds such as clay, kaolin, silica, titanium oxide and calcium carbonate. Etc. If necessary, a dye or pigment for coloring, a stabilizer such as an antioxidant or an ultraviolet absorber may be added.

In order to widely use the sheet of the present invention as a conveyor belt, a conduction belt, a cushioning material, a vibration damping material, etc., the thickness of the sheet is preferably about 0.3 mm or more. If the thickness is less than about 0.3 mm, the mechanical properties of the synthetic resin single sheet are not sufficient, or the influence of humidity and moisture becomes relatively large, and the effect of the S-PVA of the present invention is sufficient. It may not be possible to exhibit.
In addition, when at least one surface of the sheet is laminated with the fibrous material, the characteristics using the synthetic resin sheet of the present invention are often not exhibited unless the sheet has a thickness of 0.3 mm or more.
Examples of the method for producing the sheet of the present invention include a cast film-forming method from a solution, a wet film-forming method (extrusion of S-PVA into a poor solvent), and a dry-wet film-forming method. The method of extruding S-PVA to which a solvent is added is preferable because a thick sheet that is particularly suitable for the above purpose can be easily obtained.

The solvent used in the present invention includes
Dimethyl sulfoxide, dimethylformamide, dimethylacetamide, water, hexafluoroisopropanol, polyhydric alcohol, ester and the like are used alone or in combination. Also, an aqueous solution of an inorganic salt such as lithium chloride or calcium chloride can be used alone or as a mixture with the above solvent. Among these, water, dimethyl sulfoxide, glycerin, 1,3-butanediol, petriol (3-methylpentane-1,3,5-triol), ethylene glycol, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, etc. Used by preference. Water, glycerin, 1,3-butanediol, petriol, dibutyl phthalate, tricresyl phosphate and mixtures thereof are the most preferred solvents. As a solvent for extrusion molding,
When the polyhydric alcohol plasticizer or the ester plasticizer is used, the polyhydric alcohol plasticizer or the ester plasticizer is left in the S-PVA as it is to efficiently produce the sheet of the present invention. You can The concentration of S-PVA during extrusion is usually 30-
60% by weight, the extrusion temperature is usually from room temperature to 3
It is in the range of 00 ° C. In the state where the solvent is added to the S-PVA powder in the above range, the powder is in a so-called wet or swelling state and the shape is still powdery, and the powder is supplied to the extrusion molding machine and heated / heated by the molding machine. Mixing under pressure produces a solution of uniform concentration and is extruded from the die.
The extruded sheet is heated to remove a predetermined amount of solvent, especially water.

After being dried, the S-PVA sheet of the present invention can be remarkably improved in strength and water resistance by further rolling with hot rolls and subsequent heat treatment.
It is considered that this is because the rolling treatment promotes the orientation of S-PVA molecules. The purpose of this heat treatment is to remove the strain generated in the rolling process with hot rolls and to improve the toughness of the sheet.

Next, the laminated sheet of the present invention will be described. The laminated sheet of the present invention has at least one layer of S-PVA.
A sheet made of S-PVA,
S-PVA or conventional syndiotacticity is about 53
% Of PVA (hereinafter abbreviated as A-PVA) and the like are laminated in two or more layers. Conveyor belts have a wide variety of configurations such as thickness, width, length, etc., and composites with other materials, depending on the purpose and application, but the thickness is 1.0 mm or more and several mm, and sometimes 10 mm. Thick items are often used. Although a thick sheet of S-PVA can be directly produced by the above-mentioned method, its efficiency is low considering the extrudability of S-PVA having a strong hydrogen bond and the subsequent processability of drying, rolling and heat treatment. A method of forming a laminated sheet by adhering / compositing a sheet made of S-PVA, is preferable. An ordinary adhesive can be used for the adhesion, but a method of utilizing the property of polyvinyl alcohol to dissolve and adhere the surface portion by using hot water pressurized at a high temperature is preferable.

The laminated sheet of the present invention has at least 1
It may be a composite in which various fiber materials are laminated on one surface. A laminated sheet in which at least one surface of S-PVA is composited with various fibrous materials is used as a belt for a conveyor or a belt for conduction, and when it is desired to change the friction coefficient between the front surface and the back surface, or when the material is transported. It is preferably used when it is desired to use a covering material suitable for the characteristics of the object on the belt surface. When the front and back surfaces of the S-PVA sheet are laminated with the same or different fibrous materials to form a composite, the toughness of the S-PVA sheet is utilized and the fibrous material is used. The feature of can be utilized between the transported object and the transmission pulley. In the case of a laminated sheet obtained by compounding a conventional sheet made of A-PVA and a fibrous material, particularly when a fibrous material is used for only one surface or the fibrous material on two surfaces is different. In this case, the laminated sheet was often curled because the expansion and contraction due to moisture absorption and release were different between the two surfaces of A-PVA. Since the form (expansion and contraction) of the laminated sheet has little humidity dependency, curling is less likely to occur, and the form retention of the laminated sheet is greatly improved. As the fibrous material used for the laminated sheet, a woven fabric, a knitted fabric or a non-woven fabric of various fibers, and those obtained by treating these with a resin are used.

The laminated sheet of the present invention is S-PVA.
A sheet made of another polymer substance may be laminated on at least one surface of the sheet made of. Examples of the polymer substance laminated on the flexible S-PVA sheet include natural and synthetic rubbers, polyurethane elastomers, polyolefin elastomers, polyester elastomers, and the like. Among these, polyurethane elastomers and polyester elastomers are particularly preferable polymer substances. A-PVA
Compared to the laminated sheet obtained using the sheet consisting of
When the above-mentioned polymer substance is laminated on the S-PVA sheet of the present invention, shape retention is remarkably improved.

PVA has a vibration damping effect, and a laminated sheet obtained by laminating a sheet made of S-PVA and a steel sheet, a steel material, etc. is compared with a conventional laminated sheet made of A-PVA and a steel sheet. The morphological stability against humidity is extremely high, and there is no trouble such as curling of the steel sheet due to expansion and contraction of the attached polyvinyl alcohol, and it is useful as a vibration damping material with good dimensional stability.

[0022]

The present invention will be specifically described with reference to the following examples. In the following examples, "parts" and "%" mean weight basis unless otherwise specified.

Example 1 7 parts of glycerin, 5 parts of dibutyl phthalate, 7 parts of kaolin, to 100 parts of S-PVA powder having a syndiotacticity of 61.8%, a saponification degree of 81 mol% and a polymerization degree of 1750. 0.5 parts of green pigment paste and 120 parts of water were mixed. The mixture was fed to a screw extruder and extruded from a die by adjusting the barrel temperature in sequence from 50 ° C to 250 ° C to obtain a sheet having a thickness of 6.0 mm. The obtained sheet was dried at 70 ° C. for 80 hours to obtain a water content of 9%,
By rolling at 120 ° C and heat treatment at 160 ° C,
A sheet made of S-PVA having a thickness of 1.5 mm was obtained. This sheet had a glycerin content of 7 parts, a dibutyl phthalate content of 5 parts, and a water content of 8 parts with respect to 100 parts of S-PVA. The results of measuring the physical properties of the obtained sheet are shown in Table 1.

Comparative Example 1 A having a syndiotacticity of 52.8%, a saponification degree of 81 mol% and a polymerization degree of 1750, obtained by saponification of polyvinyl acetate.
A sheet of A-PVA was prepared in the same manner as in Example 1 using -PVA. The results of measuring the physical properties of the obtained sheet are shown in Table 1.

[0025]

[Table 1]

1) Using a sample with a width of 10 mm and a length of 100 mm, the form (length L ↓ 1, thickness t ↓ 1, width w ↓ 1) and 20 ° C. after standing at 20 ° C. and 65% RH for 24 hours. After standing in water for 24 hours (long L ↓ 2, thickness t ↓ 2, width w ↓
The value calculated from 2) by the following formula. Water resistance (%) =
{(L ↓ 2 × t ↓ 2 × w ↓ 2) / (L ↓ 1 × t ↓ 1 × w ↓ 1)
−1} × 100 2) The tensile strength at 2% elongation is defined as Young's modulus.

Example 2 1.5 mm thick and 600 m wide obtained by the method of Example 1.
Two sheets of S-PVA having a length of m and a length of 50 m were prepared.
After heating this sheet to 95 ° C, steam was sprayed between the two sheets so that the amount of adhesion was 75 g / m ↑ 2, and the sheets were pressed with a nip roll, and a 100 ° C heating furnace was set to 1.
It was passed through for 5 minutes, and was pressed by a press roll three times during that time to be bonded to obtain a laminated sheet having a thickness of 3.0 mm. The conveyor belt produced by cutting this sheet to a length of 10 m and endlessly processing both ends had remarkably good morphological stability against humidity as compared with the laminated sheet made of A-PVA. That is, in the case of a conveyor belt made by using a laminated sheet made of A-PVA, it was necessary to adjust the pulley interval at low humidity and high humidity, but the laminated sheet made of S-PVA of the present invention was used. In the case of conveyor belts made using it, this was not necessary. Further, since the conveyor belt made of the laminated sheet of S-PVA of the present invention has a high water resistance, the surface of the conveyor belt is not deteriorated even if it is washed with hot water after being used for food transportation. ..

Example 3 3.0 mm thick and 600 m wide obtained by the method of Example 2.
A sheet having a thickness of 4.5 m was obtained by laminating a sheet having a thickness of 1.5 mm obtained by the method of Example 2 to a sheet made of S-PVA having a length of 50 m and a length of 50 m in the same manner as in Example 2.
A laminated sheet of m was obtained. The steel sheet wrapper belt made by cutting this sheet to a width of 500 mm and a length of 8 m and processing both ends endlessly has better morphological stability with respect to humidity and tensile strength than a laminated sheet made of A-PVA. Since the thickness is large, the required thickness of the wrapper belt may be smaller than that of the conventional laminated sheet made of A-PVA, and the weight of the machine itself can be reduced.

Example 4 Thickness 3.0 mm, width 600 m obtained by the method of Example 2
Width 1700 by connecting 3 sheets of m in the vertical direction
A sheet having a length of 20 mm and a length of 20 mm was used. Vinylon # 4 canvas was attached to one surface of this sheet and then cut to obtain a sheet having a thickness of 3.5 mm, a width of 1500 mm and a length of 18 m. A belt made by endless processing both ends with the polyvinyl alcohol sheet side as the front side and the canvas side as the back side is not only stronger than the belt made using the conventional A-PVA sheet, but also the belt. Since it does not expand or contract due to changes in humidity, it did not warp and could be used stably.

Example 5 Vinylon # 5300 was applied to one side of the sheet obtained in Example 1.
No. 0 canvas was attached to the other surface, and a needle-punched nonwoven fabric made of polyester having a thickness of 2.5 mm was attached to the other surface to form a sheet having a thickness of 4.3 mm, a width of 600 mm, and a length of 30 m. Elevator belts for buckets made with the canvas side as the front side and the non-woven fabric side as the back side, bolted at both ends with endless processing, have a thickness greater than that of a belt made using conventional A-PVA sheets. Since it can be made 10% thinner, the machine becomes slimmer, and since it is less affected by humidity, which has different effects from the non-woven fabric side and the canvas side, it does not curl like the conventional product.

Example 6 A 0.5 mm urethane elastomer sheet was attached to one side of the sheet obtained in Example 1, and the urethane elastomer side was used as the surface for endless processing to give a thickness of 2.0.
mm, width 450 mm, and perimeter 5 m. The surface of this conveyor belt is polyurethane elastomer, so it has a high coefficient of friction and wear resistance.
Moreover, since the back surface is reinforced by a high-strength S-PVA conveyor belt, it is excellent as a steeply inclined conveyor belt. That is, in the case of the conventional conveyor belt using A-PVA, the polyvinyl alcohol portion on the back surface expands and contracts due to the change in humidity to cause curling of the conveyor belt, but in the case of the conveyor belt of the present invention, the humidity dependence Because of the small size, no curling was observed.

Example 7 According to the same method as in Example 1, S- having a thickness of 0.5 mm was used.
A sheet made of PVA was made. Using this sheet as a surface material, a polyvinyl chloride sheet having a thickness of 10 mm was attached to the back surface. The laminated sheets were cut into strips having a width of 100 mm and a length of 1 m to obtain a cushioning material for installing a steel pipe or a steel plate coil. Since the surface of this cushioning material is covered with a sheet of polyvinyl alcohol, it has excellent oil resistance and does not swell even if a steel pipe or steel plate coil to which rust-preventing oil is attached is installed, and it is a sheet made of S-PVA. Since the surface is covered, there is little morphological change even if it gets wet with water etc. and it can be used stably.

Example 8 A sheet having a thickness of 3 mm obtained in Example 2 was cut into a sheet having a width of 5 mm to obtain a belt-shaped belt. The endless processed belt was excellent in oil resistance and morphological stability as a conductive belt between pulleys.

Example 9 Vinylon # 5300 was applied to one side of the sheet obtained in Example 1.
0 canvas is attached, and a polyurethane elastomer sheet with a thickness of 1.0 mm is attached to the other surface, and a thickness of 3.
A sheet having a length of 0 mm, a width of 500 mm and a length of 10 m was prepared. The sheet side of the polyurethane elastomer was used as the front surface, the canvas side was used as the back surface, and both ends were endless processed to form a conveyor belt. This conveyor belt has greater strength than the conventional sheet made of A-PVA,
Moreover, the morphological stability was good and no curling occurred even when moisture was absorbed from the vinylon canvas side.

Example 10 The sheet having a thickness of 0.5 mm obtained in Example 7 was bonded to an iron plate having a thickness of 1.0 mm by using a rubber adhesive. The iron plate laminated with this polyvinyl alcohol serves as a vibration-damping iron plate, and since a sheet made of S-PVA is used, curling does not occur even when used in different humidity conditions.

[0036]

The sheet comprising S-PVA of the present invention is S
-Due to the high crystallinity of PVA, the strong intermolecular hydrogen bonding and the presence of hydrophobic groups, the morphology is less dependent on humidity and has less mechanical properties than sheets obtained using conventional A-PVA. It has low humidity dependency, excellent water resistance, high Young's modulus of the sheet, high tensile strength, organic solvent,
It has excellent features such as being less susceptible to mineral oil, vegetable oil, etc., so it is a conveyor belt, a conduction belt,
It is useful for a wide range of applications such as cushioning materials and damping materials.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location C08L 29/04 LGU 6904-4J (72) Inventor Ryoichi Kuroda 2-5 Hiranocho, Chuo-ku, Osaka City -4 Claret Trading Co., Ltd. (72) Inventor Takashi Ishihara, Nitta 1099 Kawabe, Mabi-cho, Kibi-gun, Okayama Prefecture Inside the Okayama Plant, Povaron Co., Ltd. (72) Masatoshi Tanaka, Kawabe, Mobi-cho, Kibi-gun, Okayama Prefecture Tag 1099 Povalon Co., Ltd. Okayama Factory

Claims (2)

[Claims] 1. A syndiotacticity of 55% or more and a degree of saponification of 10 mol% or more 90 indicated by diads.
A sheet comprising less than mol% of polyvinyl alcohol (A), a water-soluble polyhydric alcohol plasticizer (B) and a water-insoluble ester plasticizer (C). 2. A laminated sheet in which at least one layer is the polyvinyl alcohol (A) according to claim 1.