JP2001247625A - Vinyl alcohol-based polymer and film readily soluble in cold water using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified vinyl alcohol-based polymer suffering no damage to ready solubility in cold water even after brought into contact with any of an alkaline substance and an acid substance for a long term and suffering few troubles in the production, and a film readily soluble in cold water. SOLUTION: The vinyl alcohol-based polymer is mainly composed of a vinyl alcohol structural unit and contains 0.01-30 mole% of a structural unit represented by the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modified vinyl alcohol-based polymer, and more particularly, to a raw material for a water-soluble film which does not impair the solubility in cold water even when it is in contact with an alkaline substance or an acidic substance for a long time. The present invention relates to a vinyl alcohol-based polymer suitable as a polymer and a cold water-soluble film containing the same as a main component.

[0002]

2. Description of the Related Art Polyvinyl alcohol (hereinafter, abbreviated as PVA) has excellent interface characteristics and strength characteristics as a few crystalline water-soluble polymers, and is therefore used as a stabilizer for paper processing, fiber processing and emulsions. In addition to being used, it has an important position as a raw material for PVA-based films and PVA-based fibers. Further, in recent years, along with subdivision of these uses and enhancement of functions, development of PVA-based resins having various structures as raw materials has been promoted.

[0003] Above all, films utilizing the water solubility of PVA are widely used for packaging purposes. For example, if it is harmful to the human body, or if it comes into contact with the human body, it will be difficult to remove it,
Substances that are difficult to handle and that are water-soluble or water-dispersible and in a dry state are used by being wrapped in a water-soluble film. Materials that are packaged and used in water-soluble films include laundry detergents, insecticides, herbicides,
Examples include industrial chemicals such as fungicides, bleaching agents, bath agents, pigments, dyes, and the like. When used in a package with a water-soluble film, when a predetermined amount is packaged with a water-soluble film and put into water without opening it when used, the film for packaging dissolves in a short time, It is necessary to dissolve or decompose into
VA and the like have been used.

Conventionally, PVA used as a raw material for a water-soluble film has been a partially saponified PVA having high solubility in cold water. PVA of partially saponified type is
Although it is easily soluble in cold water, when it comes into contact with an alkaline substance, there is a problem that the saponification reaction proceeds by the alcal, and as a result, dissolution in cold water becomes difficult. In recent years, there has been an increasing need for a film having higher water solubility, and a modified vinyl alcohol-based polymer having a hydrophilic group other than a hydroxyl group introduced therein has been studied as a raw material thereof.

As these modified PVAs, modified PVAs having a carboxyl group in the molecule are known, and in addition, saponified products of copolymers of allyl esters and vinyl acetate (JP-A-62-179550). ), 2-pyrrolidone ring-containing PVA (JP-A-2-129445) and the like.

However, carboxyl group-modified PVA
The film made of does not lose the solubility in cold water even when it comes into contact with an alkaline substance, but has the problem that the water solubility in cold water is lost when it comes into contact with an acidic substance. Further, a film made of a saponified product of a copolymer of allyl ester and vinyl acetate and a film made of 2-pyrrolidone-containing PVA have a poor copolymerizability between an allyl ester or 2-pyrrolidone ring-containing monomer and a vinyl ester. It is necessary to use a large amount of allyl ester or 2-pyrrolidone ring-containing monomer during copolymerization, or it is not easy to separate the allyl ester and vinyl ester remaining after polymerization by distillation. Because of the problem, development of a modified PVA that can be produced by an industrially feasible method and that is a raw material for a highly water-soluble film has been desired.

[0007]

As a modified vinyl alcohol polymer having improved water solubility, a copolymer of vinyl acetate having a sulfonic acid group such as sodium allyl sulfonate and vinyl acetate is saponified. The resulting sulfonic acid-modified PVA is disclosed (JP-A-54-138036), and the cold-water-soluble film made from the sulfonic acid-modified PVA is more soluble in cold water than the conventional film made from modified PVA. Is better. However, this sulfonic acid-modified PVA has a production problem that a chain transfer to sodium allyl sulfonate is apt to occur during polymerization, and it is difficult to obtain a polymer having a high degree of polymerization. In addition, the water solubility of a film made of the same as that of a conventional modified PV
Although it is higher than A, there is a problem that physical properties such as mechanical strength are low. In addition, a water-soluble film made of a modified PVA obtained by partially acetalizing benzaldehyde sulfonic acid or the like with PVA (Japanese Patent Application Laid-Open No. 63-218741) is disclosed, but in order to complete the acetalization reaction, It is necessary to carry out the reaction at a high temperature for a long time of 20 hours or more, and there is a problem in production such as low productivity.

The object of the present invention is to provide a method for producing a vinyl alcohol-based polymer having a sulfonic acid group in a molecule by a method having a small production problem, and a method for producing the same from an alkaline substance or an acidic substance for a long time. An object of the present invention is to provide a raw material for a cold-water-soluble film in which the cold-water-soluble property is not impaired even when contacted.

[0009]

The present invention is characterized in that a copolymer mainly comprising a vinyl alcohol structural unit contains 0.01 to 30 mol% of a structural unit represented by the following chemical formula 1. And a cold water easily soluble film characterized by comprising a vinyl alcohol polymer and a main component thereof.

[0010]

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[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The vinyl alcohol-based polymer of the present invention mainly comprises a vinyl alcohol structural unit and contains 0.01 to 30 mol% of a structural unit represented by the following chemical formula (3). It can include a saponified vinyl ester structural unit and the like.

[0013]

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This modified vinyl alcohol-based polymer is obtained by adding phenylhydrazine p-sulfonic acid to an aqueous solution of a saponified copolymer of a vinyl ester and diacetone acrylamide and stirring the mixture at room temperature or high temperature. The polymer can be easily produced by adding the hydrazino group of phenylhydrazine p-sulfonic acid to the carbonyl group in the diacetone acrylamide unit of the polymer.

Examples of the vinyl ester used in the production of the copolymer include vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, and the like. Of these, vinyl acetate is the most industrially preferred.

As a method for copolymerizing vinyl ester and diacetone acrylamide, there are known bulk polymerization, solution polymerization,
Various polymerization methods such as emulsion polymerization and suspension polymerization can be used, and among them, solution polymerization using methanol as a solvent is industrially preferable.

The content of diacetone acrylamide in the copolymer of vinyl ester and diacetone acrylamide is 0.01 to 30 mol%, preferably 1 to 30 mol%.
１５15 mol%. Diacetone acrylamide is 0.
When the amount is less than 01 mol%, the amount of phenylhydrazine p-sulfonic acid added is small, and the film obtained therefrom does not show sufficient cold water solubility. On the other hand, if the content exceeds 30 mol%, the effect of improving the solubility in cold water becomes saturated, and there are many problems at the time of production, and the raw material cost is high, and the practicality is poor.

The degree of polymerization of the copolymer is not particularly limited, but is preferably 300 to 3000. If the degree of polymerization of the copolymer is less than 300, the strength of the film tends to be low, and if it exceeds 3000, the cold water dissolution rate tends to decrease.

As a method for saponifying a copolymer of a vinyl ester and diacetone acrylamide, conventionally known alkali saponification and acid saponification can be applied. Among them, alkali saponification in methanol is carried out using alkali hydroxide. Alcohol decomposition is preferred.

The saponification degree of the saponified product of the copolymer of vinyl ester and diacetone acrylamide is 50 mol%
Or more, more preferably 85 mol%
That is all. When the saponification degree is less than 50 mol%, the reaction time between the carbonyl group in diacetone acrylamide and the hydrazino group of phenylhydrazine p-sulfonic acid becomes longer, or when formed into a film, physical properties such as strength are reduced. There is a tendency.

The copolymer of vinyl ester and diacetone acrylamide is a monomer copolymerizable with at least one of vinyl ester and diacetone acrylamide, for example, unsaturated monomers such as crotonic acid and (meth) acrylic acid. Monocarboxylic acids and esters thereof, maleic acid, itaconic acid, unsaturated dicarboxylic acids such as fumaric acid and anhydrides thereof, monoalkyl esters, alkali metal salts, amide group-containing monomers other than diacetone acrylamide, alkyl vinyl ethers, vinyl Pyrrolidones and the like may be copolymerized as long as the effects of the present invention are not impaired.

The amount of the phenylhydrazine p-sulfonic acid used in the production of the vinyl alcohol polymer of the present invention can be variously varied. The molar amount of the diacetone acrylamide unit in the saponified copolymer of acrylamide and the molar amount thereof is preferably 2 to 2 times.

The method of reacting a saponified product of a copolymer of vinyl ester and diacetone acrylamide with phenylhydrazine p-sulfonic acid is usually carried out in water, and phenylhydrazine p-aqueous solution is added to an aqueous solution of the saponified copolymer. -Add sulfonic acid and react with stirring at room temperature or under heating, or add water and phenylhydrazine p-sulfonic acid to the saponified product of the copolymer, then react while heating and stirring to dissolve. And the like. This reaction has a higher reaction rate than the acetalization reaction between PVA and a sulfonic acid group-containing aromatic aldehyde, and is allowed to react at room temperature or the saponification of the copolymer of vinyl ester and diacetone acrylamide. By adding phenylhydrazine p-sulfonic acid when dissolving the substance in water, it is excellent in that the reaction is completed at the time of dissolution.

The rate of reaction between the carbonyl group in the diacetone acrylamide unit and the hydrazino group of phenylhydrazine p-sulfonic acid is promoted under weakly acidic conditions of pH 3 to 5, so that a water-soluble acidic compound is added during the reaction. , The reaction can be completed in a shorter time. As the water-soluble acidic compound used at this time, various known organic or inorganic acids are used. Such compounds include, for example, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and carboxylic acid, sulfonic acid, sulfinic acid, barbituric acid, uric acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, and oxalic acid. Acid, malonic acid,
Organic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, fumaric acid, maleic acid, tartaric acid, citric acid, lactic acid, benzoic acid, phthalic acid, benzenetricarboxylic acid and the like, and any amount of water-soluble acid Compounds can be added.

The cold water easily soluble film of the present invention is formed by using the above-mentioned vinyl alcohol-based polymer as a main component, and may be formed by a known method such as a casting method or an extrusion method. Can be used. In the present invention, cold water refers to water at -10 to 40C. The thickness of the film may be arbitrarily set according to the purpose of use, but is preferably 10 to 200 μm. further,
In forming the film, a plasticizer for the water-soluble polymer may be added as necessary. Preferred plasticizers include, for example, glycerin, diethylene glycol,
Examples include triethylene glycol, polyethylene glycol, polyglycerol, triethanolamine, triethanolamine acetate and the like.

The cold water-soluble film of the present invention may be a water-soluble polymer such as PVA, starch, a cellulose derivative or an alkali metal salt thereof, an aqueous emulsion, a suspension or the like, as long as the effects of the present invention are not impaired. Muddy or clay,
It may contain a pigment such as titanium oxide.For example, a compound having a sulfonic acid group such as sodium polystyrene sulfonate or polyacrylic acid is added to be used in combination with a conventional technique such as improving water solubility. You can also.

The cold-water-soluble film of the present invention does not lose its cold-water solubility even when it comes into contact with an alkaline substance or an acidic substance. Therefore, having such properties, it is suitable for packaging of substances that are harmful to the human body, difficult to remove by touching the human body, or that need to be accurately weighed during use and difficult to handle. ing.
Then, when the package is put into water as it is when used even after a long period of time, the film dissolves immediately and the contents dissolve or disperse. That is, the cold-water-soluble film of the present invention is suitably used as a direct-casting type packaging film.

[0028]

Next, the present invention will be described more specifically with reference to examples.

Production of saponified diacetone acrylamide-vinyl acetate copolymer Synthesis Example 1 1000 parts by weight of vinyl acetate, methanol 3 in a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser
After charging 50 parts by weight and purging the system with nitrogen, the internal temperature was raised to 60 ° C. A solution prepared by dissolving 1 part by weight of 2,2'-azoisobutyrylonitrile in 50 parts by weight of methanol was added to the system, and polymerization was started. After the initiation of polymerization, 150 parts by weight of diacetone acrylamide was added to 100 parts of methanol.
The solution dissolved in parts by weight was added dropwise at a constant rate over 5 hours, and the polymerization was stopped after 6 hours. When the polymerization was stopped, the solid content in the system was 52% by weight, and the polymerization yield of vinyl acetate was 7%.
2%. The remaining vinyl acetate was distilled off while adding methanol vapor to the obtained reaction mixture to obtain a 50% by weight methanol solution of a vinyl acetate polymer containing a diacetone acrylamide copolymer component. 500 of this one
50 parts by weight of methanol and 10 parts by weight of a methanol solution having a concentration of sodium hydroxide of 4% by weight were added to the parts by weight, mixed well, and a saponification reaction was carried out at 40 ° C. The obtained gel was pulverized, washed well with methanol, and then dried to obtain a saponified copolymer of diacetone acrylamide and vinyl acetate. The degree of polymerization of this saponified copolymer was 1700, the degree of saponification was 98.0 mol%, and the elemental analysis measurement revealed that the content of the diacetone acrylamide copolymer component was 4.8 mol%. .

Synthesis Examples 2 to 6 A copolymer obtained by copolymerizing vinyl acetate and diacetone acrylamide according to the above-mentioned method was saponified, and the structural units, the degree of polymerization and the degree of saponification of the copolymer were obtained. And unmodified PVA without using diacetone acrylamide were obtained. Table 1 shows data on the saponified copolymer and unmodified PVA.

[0031]

[Table 1]

Example 1 A powder of a saponified copolymer of diacetone acrylamide and vinyl acetate obtained in Synthesis Example 1 was dissolved in water to prepare a 10% by weight aqueous solution. To 100 parts by weight of this aqueous solution was added 2 parts by weight of phenylhydrazine p-sulfonic acid, and the mixture was reacted while heating and stirring at 30 ° C. for 1 hour. The resulting reaction mixture was dropped into a large amount of acetone and precipitated to obtain a purified sulfonic acid-modified vinyl alcohol polymer.

A 10% by weight aqueous solution of this sulfonic acid-modified vinyl alcohol polymer was prepared, and was cast on a flat polyester plate having a smooth surface using an applicator.
Drying and peeling gave a transparent and uniform film. The thickness of the obtained film was about 30 μm. 1cm x 1cm
Was cut out, immersed in water at 20 ° C., and the time required for the film to completely dissolve (dissolution time) was measured. As shown in Table 2, excellent cold water solubility was shown.

A bag having a size of 5 cm × 5 cm was prepared from the obtained film, and 20 g of a laundry detergent (product “Zab”: manufactured by Kao) was placed in the bag and heat-sealed to obtain a detergent-enclosed bag. Similarly, aluminum sulfate powder-containing bags were obtained for aluminum sulfate powder. These 6
1cm × 1cm from bag after leaving for 1 month and 1 year
Was cut out, immersed in water at 20 ° C., and the time required for dissolution was measured. As is clear from Table 2, good cold water solubility was exhibited by contact with the drug for 6 months and 1 year, and the effect was not lost even by long-term drug contact.

Example 2 A saponified copolymer of diacetone acrylamide-vinyl acetate obtained in Synthesis Example 2 in a stainless steel dissolving bottle 10
Parts by weight, 4 parts by weight of phenylhydrazine p-sulfonic acid and 90 parts by weight of pure water were added, and reacted at 90 ° C. for 1 hour while stirring and dissolving. In the same manner as in Example 1, a purified sulfonic acid-modified vinyl alcohol-based polymer was obtained from the obtained reaction mixture, a cast film was prepared from a 10% by weight aqueous solution, and the time required for dissolution was measured. Table 2
As shown in FIG. Next, bags each containing a laundry detergent and aluminum powder were prepared, and the film dissolution time required after standing for 6 months and 1 year was measured. And the effect was not lost by prolonged drug contact.

Example 3 A saponified copolymer of diacetone acrylamide-vinyl acetate obtained in Synthesis Example 3 was placed in a stainless steel dissolving bottle.
0 parts by weight, 0.5 parts by weight of phenylhydrazine p-sulfonic acid and 90 parts by weight of pure water were added, and the mixture was reacted at 90 ° C. for 1 hour while stirring and dissolving. In the same manner as in Example 1, a purified sulfonic acid-modified vinyl alcohol-based polymer was obtained from the obtained reaction mixture, a cast film was prepared from a 10% by weight aqueous solution, and the time required for dissolution was measured. As shown in Table 2, excellent cold water solubility was exhibited. Next, each bag body containing a laundry detergent and aluminum sulfate powder was prepared, and the time required for dissolving each film after being left for 6 months and 1 year was measured. As shown in Table 2,
All exhibited good cold water solubility, and their effects were not lost even by prolonged drug contact.

Example 4 A saponified copolymer of diacetoneacrylamide-vinyl acetate 1 obtained in Synthesis Example 4 was placed in a dissolution bottle made of stainless steel.
0 parts by weight, 6 parts by weight of phenylhydrazine p-sulfonic acid and 90 parts by weight of pure water were added, and the mixture was stirred at 90 ° C. and reacted for 1 hour while dissolving. In the same manner as in Example 1, a purified sulfonic acid-modified vinyl alcohol-based polymer was obtained from the obtained reaction mixture, a cast film was prepared from a 10% by weight aqueous solution, and the time required for dissolution was measured. As shown in Table 2, excellent cold water solubility was exhibited. Next, each bag body containing a laundry detergent and aluminum sulfate powder was prepared, and the time required for dissolving each film after being left for 6 months and 1 year was measured. It showed good solubility and its effect was not lost by prolonged drug contact.

Example 5 A powder of a saponified copolymer of diacetone acrylamide and vinyl acetate obtained in Synthesis Example 5 was dissolved in water to prepare a 10% by weight aqueous solution. 2.5 parts by weight of phenylhydrazine p-sulfonic acid was added to 100 parts by weight of this aqueous solution,
The reaction was carried out while heating and stirring at 10 ° C. for 10 minutes. Example 1
In the same manner as described above, a purified sulfonic acid-modified vinyl alcohol-based polymer was obtained from the obtained reaction mixture, a cast film was prepared from a 10% by weight aqueous solution, and the time required for dissolution was measured. As shown, it showed excellent cold water solubility. Next, each bag body containing a laundry detergent and aluminum sulfate powder was prepared, and the time required for dissolving each film after being left for 6 months and 1 year was measured. It showed good solubility and its effect was not lost by prolonged drug contact.

Comparative Example 1 For the unmodified PVA obtained in Synthesis Example 6, a 10% by weight aqueous solution was prepared, a cast film was prepared in the same manner as in Example 1, and the time required for dissolution was measured. 2 showed good cold water solubility, but each bag containing a laundry detergent and aluminum sulfate powder was prepared, and the time required to dissolve each film after leaving it for 6 months and 1 year was measured. As shown in Table 2, the solubility in cold water decreased with time, and the solubility in cold water was remarkably lost.

Comparative Example 2 A stainless steel dissolving bottle was charged with 10 parts by weight of the unmodified PVA obtained in Synthesis Example 6, 2 parts by weight of phenylhydrazine p-sulfonic acid and 90 parts by weight of pure water, and stirred at 90 ° C. to dissolve. While reacting for 1 hour.

In the same manner as in Example 1, a purified polymer was obtained from the obtained mixture, a cast film was prepared from a 10% by weight aqueous solution, and the time required for dissolution was measured.
As shown in Table 2, it showed good cold water solubility, but each bag containing a laundry detergent and aluminum sulfate powder was prepared, and the time required for dissolving each film after being left for 6 months and 1 year was measured. As shown in Table 2, the solubility in cold water decreased with time, and the solubility in cold water was remarkably lost.

Comparative Example 3 A film was prepared in the same manner as in Example 1 except that phenylhydrazine p-sulfonic acid was not added, and the time required for dissolution was measured. As shown in Table 2, the solubility in cold water was poor. Each bag body containing a laundry detergent and aluminum sulfate powder was prepared, and the time required to dissolve each film after being left for 6 months and 1 year was measured. As shown in Table 2, the solubility in cold water was as follows. Was inferior.

[0043]

[Table 2]

[0044]

As described above, the vinyl alcohol polymer of the present invention has good copolymerizability with vinyl ester and diacetone acrylamide in the production process, and the obtained diacetone acrylamide-vinyl ester copolymer is obtained. When the saponified product is stirred in water, it easily reacts with phenylhydrazine p-sulfonic acid, so that there is little problem in the production and industrial production is possible. Moreover,
The polymer is extremely useful as a cold-water-soluble film because its cold-water solubility is not impaired even when it is brought into contact with an alkaline substance or an acidic substance for a long time.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA28 AA28X AA29 AA29X AA35 AA78 AA78X AF05 AH04 BA01 BB02 BC01 4J100 AD02P AG02Q AG03Q AG04Q AM21Q BA03H BA14Q BA46H BA56H BC43H CA04 CA05 CA31 DA01 JA38 HA38

Claims (2)

[Claims] (1) In a copolymer mainly composed of vinyl alcohol structural units, the structural unit represented by the following chemical formula (1) is added to 0.1.
A vinyl alcohol-based polymer, which is contained in an amount of from 01 to 30 mol%. Embedded image 2. A cold water easily soluble film comprising the polymer according to claim 1 as a main component.