JP2002146053A - Polyvinyl alcohol film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polyvinyl alcohol film that has excellent opacifying effect, mechanical strength and appearance. SOLUTION: The polyvinyl alcohol film includes the filler in an amount of 0.1-50 pts.wt. per 100 pts.wt. of polyvinyl alcohol resin and has a surface roughness (Ra) defined in JIS B 0601 of <=2 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl alcohol-based film, and more particularly, to a polyvinyl alcohol-based film having excellent concealing properties and appearance and excellent mechanical strength.

[0002]

2. Description of the Related Art Conventionally, polyvinyl alcohol-based films have been widely used as various packaging materials for accommodating agricultural chemicals, chemicals, dyes, detergents, fertilizers, cosmetics, sanitary goods, etc. by utilizing their water solubility. .

[0003] For the purpose of improving the water solubility, for example, Japanese Patent Application Laid-Open No. 4-170405 discloses a monomer unit having a carboxyl group in a molecule.
10 mol%, saponification degree 80 mol% or more, and 2
A water-soluble film made of a modified polyvinyl alcohol having a 4% by weight aqueous solution at 0 ° C. having a viscosity of 46 cps or more is disclosed in Japanese Patent Application Laid-Open No. H10-60207. Water-soluble films containing polyvinyl alcohol and water-insoluble or poorly-soluble fine powder having an average particle size of 150 μm or less have been proposed.

[0004]

However, in recent years, a film having a hiding property has been required from the viewpoint of improvement in appearance quality, and in the above-mentioned disclosed technology, although the water solubility is improved, Such concealability has not been studied in detail, and as a result of a detailed study by the present inventors, in order to impart concealment, the clay described in the above publication,
Simply blending an inorganic substance such as titanium oxide or calcium carbonate causes agglomerates to be generated on the film surface, resulting in poor mechanical strength and appearance of the film. To satisfy such concealing properties, mechanical strength, and appearance, It turns out that there is still room for improvement.

Accordingly, an object of the present invention is to provide a polyvinyl alcohol-based film having excellent concealing properties, mechanical strength, and appearance in such a background.

[0006]

Means for Solving the Problems However, as a result of intensive studies on such problems, the present inventor has found that a filler is added in an amount of 0.1 part by weight to 100 parts by weight of a polyvinyl alcohol-based resin.
~ 50 parts by weight, and JIS B 0601
It has been found that a polyvinyl alcohol-based film having a film surface roughness (Ra) of 2 μm or less defined by the above meets the above object, and has completed the present invention.

In the present invention, when a dispersion obtained by blending an aqueous dispersion of a filler having a concentration of 1 to 40% by weight and an aqueous solution of a polyvinyl alcohol resin having a concentration of 10 to 50% by weight is formed into a film, The effects of the invention are remarkably exhibited.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The polyvinyl alcohol-based resin used in the present invention is not particularly limited, and is generally a saponified product or a derivative thereof obtained by saponifying a lower alcohol solution of polyvinyl acetate with a saponification catalyst such as an alkali or an acid. Further, a modified polyvinyl alcohol resin such as a saponified product of a copolymer of vinyl acetate and a monomer having a copolymerizability with vinyl acetate can also be used. The content of such a copolymerizable monomer is preferably 0.5 to 10 mol%, and particularly preferably 1 to 7 mol%.

Examples of the monomer include ethylene, propylene, isobutylene, α-octene, α-dodecene,
Olefins such as α-octadecene, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride,
Unsaturated acids such as itaconic acid or salts thereof or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefins such as ethylenesulfonic acid, allylsulfonic acid and methallylsulfonic acid Sulfonic acids or salts thereof, alkyl vinyl ethers,
Dimethylallyl vinyl ketone, N-vinyl pyrrolidone,
Polyvinyl chloride, vinylidene chloride, polyoxyethylene (meth) allyl ether, polyoxyalkylene (meth) allyl ether such as polyoxypropylene (meth) allyl ether, polyoxyethylene (meth) acrylate,
Polyoxyalkylene (meth) acrylates such as polyoxypropylene (meth) acrylate, polyoxyalkylene (meth) acrylamides such as polyoxyethylene (meth) acrylamide and polyoxypropylene (meth) acrylamide, and polyoxyethylene (1- (meth) ) Acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, diacrylacetoneamide, etc. No.

Further, N-acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium chloride, N-acrylamidopropyltrimethylammonium chloride, 2-acryloxyethyltrimethylammonium chloride,
2-methacryloxyethyltrimethylammonium chloride, 2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, 3-butenetrimethylammonium chloride, dimethyldiallylammonium chloride, diethyldiallylammonium chloride, etc. And the like. Further, a polyvinyl alcohol-based resin containing an acetoacetyl group can also be used. Among the above-mentioned modified polyvinyl alcohol-based resins, a carboxyl group-modified polyvinyl alcohol-based resin is particularly preferable in that it is inexpensive and easily available.

Although the degree of saponification of the polyvinyl alcohol resin is not particularly limited, it is preferably 70 to 98 mol%, more preferably 75 to 97 mol%, and particularly preferably 80 to 96 mol%. If the saponification degree is less than 70 mol%, the water solubility will decrease,
Conversely, if it exceeds 98 mol%, the solubility in water is undesirably reduced.

Although the average degree of polymerization is not particularly limited, it is preferably 300 to 4000, more preferably 400 to 3000, and particularly preferably 500 to 2
000. If the average degree of polymerization is less than 300, the mechanical strength of the film decreases, and if it exceeds 4,000, the viscosity of the aqueous solution increases, which is not preferable because it causes inconvenience during film formation. In the present invention, not only one kind of the polyvinyl alcohol-based resin but also two or more kinds thereof can be used in combination.

The filler used in the present invention is not particularly limited, and examples thereof include clay, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate, satin white, talc, silicate, pulp, cellulose and the like. And titanium dioxide is particularly preferably used.

The particle size of the filler is not particularly limited, but is preferably 0.10 to 15 μm, more preferably 0.15 to 13 μm, and particularly preferably 0.20 to 13 μm.
10 μm. If the particle size is less than 0.10 μm, the concealing property will decrease, and if it exceeds 15 μm, the film strength will decrease, which is not preferable.

The content of the filler is as follows:
For 100 parts by weight of polyvinyl alcohol resin,
It is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 40 parts by weight, particularly preferably 1.0 to 30 parts by weight.
Parts by weight. When the content is less than 0.1 part by weight, it is difficult to obtain the concealing property. When the content exceeds 50 parts by weight, the film strength is undesirably reduced.

In the present invention, a film is produced by adding a filler to a polyvinyl alcohol resin, and the resulting film has a surface roughness (Ra) of 2 μm.
m, more preferably 1.8.
μm or less, particularly preferably 1.5 μm or less. If the surface roughness (Ra) of such a film exceeds 2 μm, agglomerates of the filler occur frequently, and the effect of the present invention is not exhibited. The surface roughness (Ra) of the film is measured according to JIS.
It is measured according to B0601.

In producing the polyvinyl alcohol-based film, the film surface roughness (Ra) is 2 μm.
m or less, and the aqueous polyvinyl alcohol-based resin dispersion containing the filler is applied onto a smooth metal surface such as a roll, drum, or endless belt (the temperature of the metal surface is about 90 to 100 ° C.). It is obtained by a method of casting, or a method of melt-molding a composition obtained by adding water or a plasticizer and a filler to the resin as appropriate by an extrusion method or the like.In the present invention, the former casting method is particularly preferred. It is preferably used.

In the casting method, a polyvinyl alcohol-based resin, a filler, and water may be appropriately mixed and dispersed to form a cast film. In the present invention, however, an aqueous dispersion of the filler is once prepared, After blending and dispersing the aqueous dispersion of the filler and the aqueous solution of the polyvinyl alcohol-based resin, it is preferable to cast and form a film in order to obtain a film having excellent mechanical strength without generating agglomerates on the film surface.

The aqueous dispersion of the filler is preferably an aqueous dispersion having a concentration of 1 to 40% by weight, more preferably 5 to 30% by weight, and particularly preferably 1 to 40% by weight.
0 to 25% by weight. If the concentration is less than 1% by weight, the productivity is reduced, and if it exceeds 40% by weight, aggregates are generated, which is not preferable.

The aqueous solution of the polyvinyl alcohol resin is preferably an aqueous solution having a concentration of 10 to 50% by weight, more preferably 13 to 45% by weight, and particularly preferably 15 to 40% by weight. If the concentration is 1
If it is less than 0% by weight, poor drying or dripping will occur, and the productivity will be reduced. If it exceeds 50% by weight, dispersibility will be poor, which is not preferable.

Further, the concentration of the aqueous dispersion (dope) after mixing and dispersing the aqueous dispersion of the filler and the aqueous solution of the polyvinyl alcohol resin is preferably 10 to 50% by weight as the concentration of the polyvinyl alcohol resin. More preferably, it is 15 to 40% by weight. If the concentration is less than 15% by weight, poor drying or dripping will occur, and the productivity will decrease.
If the content exceeds 0% by weight, die lines and poor appearance are caused, resulting in poor coatability.

In the above casting method, if necessary, a plasticizer (glycerin, diglycerin, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, etc.), a release agent (sorbitan ester ether, etc.), cissing prevention Agents (polyoxyethylene alkyl phenyl ether, etc.) may be added, and further, antioxidants (phenol-based, amine-based, etc.),
You may add usual additives, such as a stabilizer (phosphate ester etc.), a coloring agent, a fragrance | flavor, a bulking agent, an enveloping agent, an ultraviolet absorber, an inorganic powder, a surfactant, etc.

The thickness of the polyvinyl alcohol-based film thus obtained cannot be unconditionally determined depending on the type and use of the contents to be packaged, but is preferably from 10 to 70 μm, more preferably from 15 to 65 μm,
If it is less than 10 μm, the mechanical strength will be insufficient, and
If it exceeds μm, the solubility is lowered and the film forming efficiency is lowered, which is not preferable.

The obtained polyvinyl alcohol-based film may be provided with an embossed pattern, a satin pattern, or the like on one or both sides thereof, if necessary.

Further, the polyvinyl alcohol-based film of the present invention may contain other water-soluble polymers (sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, etc.) as long as the object of the present invention is not impaired. Methylcellulose, hydroxyethylcellulose, starch, etc.), rust preventives, coloring agents and the like can also be added.

The contents packaged in the polyvinyl alcohol-based film of the present invention are not particularly limited as long as they are dissolved or dispersed in water and used, and may be any of alkaline, neutral and acidic. You may. The shape of the contents may be any of granules, tablets, powders, pellets and the like, and in some cases, may be liquid. Specific examples of the contents include powdered soap, synthetic detergent, pesticide, bactericide,
Deodorants, insecticides, and the like are preferable, and detergents and agricultural chemicals are preferable.

In packaging the contents using the polyvinyl alcohol-based film of the present invention, the film is preliminarily formed into a bag, and the contents are stored and packaged. The contents are placed directly on the film surface. And packaging methods.

Thus, the polyvinyl alcohol-based film of the present invention has excellent concealing properties, mechanical strength, and appearance, and is used as a water-soluble packaging material for agricultural chemicals, drugs, dyes, detergents, fertilizers, cosmetics, sanitary products, and the like. Very useful.

[0029]

The present invention will be specifically described below with reference to examples. In the examples, “parts” and “%” mean on a weight basis unless otherwise specified.

Example 1 Using a homomixer, titanium dioxide (particle size: 0.25 μm)
m) was dispersed in water to prepare an aqueous dispersion having a concentration of 15%. Such an aqueous dispersion is treated with polyvinyl alcohol (P-
1) (Saponification degree: 88 mol%, average polymerization degree: 1400) 2
In a 3% aqueous solution, 10 parts of polyvinyl alcohol were mixed with 100 parts of polyvinyl alcohol, and 20 parts of glycerin and 0.5 part of release agent were mixed with 100 parts of polyvinyl alcohol.
And dope with stirring (concentration: 20%)
Was prepared.

The dope was cast on a metal roll having a surface temperature of 94 ° C., and dried to obtain a 30 μm thick polyvinyl alcohol film. The surface roughness (Ra) of the obtained polyvinyl alcohol-based film is 1.2 μm.
m. In addition, the surface roughness (Ra) is JIS B 0
601 was measured using an ultra-depth shape measuring microscope VK-8500 manufactured by Keyence Corporation. This polyvinyl alcohol-based film was evaluated as follows.

(Hiding property) Turbidity meter N manufactured by Nippon Denshoku Co., Ltd.
The total light transmittance of the obtained polyvinyl alcohol-based film was measured using DH2000, and evaluated as follows. ○: Total light transmittance is less than 50% ×: Total light transmittance is 50% or more

(Mechanical strength) Autograph A manufactured by Shimadzu Corporation
Using GS-1000, the tensile strength of the obtained polyvinyl alcohol-based film was measured under the following conditions, and evaluated as follows. [Conditions] Measurement environment: 20 ° C. × 50% RH Tensile speed: 200 mm / min Distance between checks: 50 mm Film width: 15 mm ○: Tensile strength of 35 MPa or more ×: Tensile strength of less than 35 MPa

(Appearance) The obtained polyvinyl alcohol-based film was visually observed and evaluated as follows.・ ・ ・: No filler aggregate was found on the film surface ×: Filler aggregate was found on the film surface

Examples 2 to 6 and Comparative Examples 1 to 3 The same experiment as in Example 1 was carried out except that the formulation was changed as shown in Table 1, and a polyvinyl alcohol film having a thickness of 30 μm was obtained. The same evaluation as in Example 1 was performed on the obtained polyvinyl alcohol-based film.

[Table 1] Polyvinyl alcohol aqueous solution filler aqueous dispersion liquid dope filler film type concentration type concentration content concentration concentration surface roughness (%) (%) (parts) (%) (μm) Example 1 P-123 TiO ₂ 15 10 20 1.2 {2 P-1 23 TiO ₂ 5 30 16 1.4} 3 P-2 18 TiO ₂ 20 10 17 1.2 {4 P-2 15 Talc 25 10 14 1.3} 5 P-3 25 Talc 15 30 17 1.5 〃 6 P-4 23 TiO ₂ 15 10 20 1.3 Comparative Example 1 P-1 23 TiO ₂ 15 0.05 23 0.1 〃 2 P-1 23 TiO ₂ 15 60 12 1.8 ３ 3 P-1 23 TiO ₂ 50 10 22 2.8

Note: The filler content is based on 100 parts of polyvinyl alcohol. The concentration of the dope is the concentration of the polyvinyl alcohol resin. The symbols in the table are as follows. P-1: Polyvinyl alcohol having a saponification degree of 88 mol% and an average degree of polymerization of 1400 P-2: Polyvinyl alcohol having a saponification degree of 88 mol% and an average degree of polymerization of 2000 P-3: Saponification degree of 95 mol% and an average degree of polymerization Polyvinyl alcohol of 1100 P-4: Carboxyl group content 2 mol%, saponification degree 95
Carboxyl group-modified polyvinyl alcohol having an average degree of polymerization of 1700 by mol% (modified by copolymerizing maleic acid) TiO ₂ : titanium dioxide The results of the examples and comparative examples are shown in Table 2.

[0038]

[0039]

The polyvinyl alcohol-based film of the present invention contains 0.1 to 50 parts by weight of a filler with respect to 100 parts by weight of a polyvinyl alcohol-based resin, and has a film surface roughness defined by JISB0601. (R
Since a) is 2 μm or less, in particular, a dispersion obtained by mixing an aqueous dispersion of a filler having a concentration of 1 to 40% by weight and an aqueous solution of a polyvinyl alcohol-based resin having a concentration of 10 to 50% by weight is formed into a film. As a result, it shows excellent effects in all of concealability, mechanical strength, and appearance, and is very useful as a water-soluble packaging material for agricultural chemicals, drugs, dyes, detergents, fertilizers, cosmetics, sanitary products, etc. It is something.

[Procedure amendment]

[Submission date] October 5, 2001 (2001.10.
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction contents]

(Mechanical strength) Autograph A manufactured by Shimadzu Corporation
Using GS-1000, the tensile strength of the obtained polyvinyl alcohol-based film was measured under the following conditions, and evaluated as follows. [Conditions] Measurement environment: 20 ° C. × 50% RH Peeling speed: 200 mm / min Distance between chucks : 50 mm Film width: 15 mm ・ ・ ・: Tensile strength of 35 MPa or more ・ ・ ・: Tensile strength of less than 35 MPa

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 7:00 B29L 7:00

Claims (4)

[Claims] 1. A film containing 0.1 to 50 parts by weight of a filler with respect to 100 parts by weight of a polyvinyl alcohol-based resin, and having a film surface roughness (Ra) of 2 μm or less as defined by JIS B0601. A polyvinyl alcohol-based film, characterized in that: 2. A film formed by mixing an aqueous dispersion of a filler having a concentration of 1 to 40% by weight with an aqueous solution of a polyvinyl alcohol resin having a concentration of 10 to 50% by weight. The polyvinyl alcohol-based film according to claim 1, 3. The polyvinyl alcohol-based film according to claim 1, wherein the polyvinyl alcohol-based resin has a saponification degree of 70 to 98 mol% and an average polymerization degree of 300 to 4000. 4. The polyvinyl alcohol-based film according to claim 1, wherein the polyvinyl alcohol-based resin is a carboxyl group-modified polyvinyl alcohol-based resin.