JP3367708B2 - Polyvinyl alcohol-based laminated film - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film suitable for unit packaging of an alkaline substance. 2. Description of the Related Art In recent years, detergents, sizing agents, dyes, agricultural chemicals or various other chemicals are sealed in a water-soluble film in unit amounts, and the required number of the containers are poured into water as they are when used. ,
It has been practiced to dissolve or disperse the contents together with the packaging film in water. According to this unit packaging
There is an advantage that not only the trouble of calculating one by one at the time of use can be saved, but also the hands are not contaminated. The water-soluble film used for such a unit package is one that easily dissolves or swells in a large amount of water to lose its form, and is used for packaging detergents and alkaline chemicals such as borax and sodium carbonate. As being alkali resistant,
Furthermore, it is required that the packaging film has considerable mechanical strength. Several patent applications have been filed as such a packaging film, and the present applicant has also filed a polyvinyl alcohol film for packaging an alkaline substance obtained by forming an oxyalkylene group-containing polyvinyl alcohol-based resin (Japanese Patent Application Laid-Open No. 61-315604). ) Developed. [0003] The use of such a water-soluble film for unit packaging has been diversified, and in recent years, a film capable of freely setting a dissolution or swelling temperature has been demanded. Accordingly, the present applicant has also attempted such a request by using a film made of the above-mentioned oxyalkylene group-containing polyvinyl alcohol. However, in such a film, although the dissolution or swelling temperature can be set to some extent freely by a combination of the oxyalkylene group content and the degree of saponification, when the dissolution or swelling temperature is set to be high, the alkali resistance is reduced and the film is deteriorated. When the film is brought into contact with an alkaline substance for a long time, the water solubility of the film is suppressed, and dissolution at the set temperature does not occur, or when the dissolution or swelling temperature is set low, the water resistance in practical use is extremely high. The size of the film becomes small, and the film easily starts to dissolve, for example, only by handling the film with wet hands, and there is room for improvement. [0004] However, the present inventor has conducted intensive studies to solve the above problems, and as a result, the content of oxyalkylene groups was 1 to 20% by weight and the degree of saponification was 90 to 1%.
An oxyalkylene group-containing polyvinyl alcohol resin (A) having an outer layer of 10 mol% or more and less than 15 wt% and an saponification degree of 80 to 100 mol%; A laminated film having a polyvinyl alcohol-based resin (B) as an inner layer, and the oxyalkylene group content in the oxyalkylene group-containing polyvinyl alcohol resin (B) and the oxyalkylene group-containing polyvinyl alcohol resin (A) The difference in oxyalkylene group content in the resin is 5% by weight
The present inventors have found that the polyvinyl alcohol-based laminated film described above meets such an object, and have completed the present invention. In the present invention, two types of oxyalkylene group-containing polyvinyl alcohol-based films having a specific oxyalkylene group content and saponification degree are laminated, that is, the outer layer is provided with water resistance in a short time. Alkali resistance and water resistance are always provided by providing a film whose dissolution or swelling temperature in water can be freely set while having it, and by providing a film that has alkali resistance and easily dissolves in a large amount of water regardless of the water temperature in the inner layer. We have developed a water-soluble film for unit packaging that can set the melting or swelling temperature freely to some extent while having sufficient properties, and expanded the range of use of such a film. Hereinafter, the present invention will be described in detail. [0008] The oxyalkylene group-containing polyvinyl alcohol resin used in the present invention is typically vinyl acetate, polyoxyethylene (meth) allyl ether,
It can be obtained by copolymerizing with polyoxyalkylene (meth) allyl ether such as polyoxypropylene (meth) allyl ether and then saponifying. Components other than polyoxyalkylene (meth) allyl ether as copolymerization components, for example, α-olefins (ethylene, propylene, long-chain α-olefins, etc.), ethylenically unsaturated carboxylic acid monomers, (acrylate, methacrylate, acrylonitrile) , Methacrylonitrile, vinyl chloride, vinyl ether, etc.) in an amount of about 30 mol% or less. As a polymerization method for obtaining an oxyalkylene group-containing polyvinyl alcohol, a solution polymerization method is usually employed, and in some cases, a suspension polymerization method, an emulsion polymerization method and the like can be employed. As the saponification reaction, an alkali saponification method, an acid saponification method, or the like is employed. Oxyalkylene group-containing polyvinyl alcohol other than the above,
Vinyl acetate, polyoxyethylene (meth) acrylate, polyoxypropylene (meth) acrylate, polyoxyethylene (meth) acrylamide, polyoxypropylene (meth) acrylamide, polyoxyethylene (1- (meth) acrylamide-1,1) -Dimethylpropyl) ester, polyoxyethylene vinyl ether,
Copolymerization of polyoxypropylene vinyl ether, etc.,
It can also be obtained by saponification. The oxyalkylene group-containing polyvinyl alcohol can also be obtained by a reaction of an alkylene oxide with polyvinyl alcohol, or a polymerization of vinyl acetate with polyoxyalkylene glycol followed by saponification. The polyoxyalkylene (meth) allyl ether copolymerization ratio of the oxyalkylene group-containing polyvinyl alcohol resin used as the outer layer (A) is 0.1%.
The condensation degree of the polyoxyalkylene in the polyoxyalkylene (meth) allyl ether is suitably from 1 to 300, and especially from 3 to 50. Is preferably 1 to 20% by weight, particularly 5 to 20% by weight, more preferably 8 to 20% by weight. If the proportion exceeds 20% by weight, sufficient short-time water resistance cannot be obtained. If the amount is less than 5% by weight, sufficient solubility in water cannot be obtained. The dissolution or swelling temperature of the film made of such an oxyalkylene group-containing polyvinyl alcohol resin can be freely set by a combination of the oxyalkylene group content and the saponification degree. When such a temperature is set high to make the film insoluble in water at normal temperature, it is advantageous to further heat-treat or heat-stretch the obtained film. Even when the temperature is set low, such a film has water resistance, so that it is not easily dissolved even if it is handled with wet hands. The copolymerization ratio of the polyoxyalkylene (meth) allyl ether of the oxyalkylene group-containing polyvinyl alcohol resin used as the inner layer (B) is 0.1.
The condensation degree of the polyoxyalkylene in the polyoxyalkylene (meth) allyl ether is suitably from 1 to 300, and especially from 3 to 50. Oxyalkylene units account for at least 10 % by weight of the total
Is preferably less than 15% by weight . If the proportion is less than 10% by weight, sufficient alkali resistance cannot be obtained. A film made of such an oxyalkylene group-containing polyvinyl alcohol-based resin is a water-soluble film which has sufficient alkali resistance and is easily dissolved in a large amount of water regardless of the water temperature. In the present invention, the difference between the oxyalkylene group content in the oxyalkylene group-containing polyvinyl alcohol (B) and the oxyalkylene group content in the oxyalkylene group-containing polyvinyl alcohol (A) is 5% by weight.
It is essential that the content be at least 8% by weight. If the difference is less than 5% by weight, it is difficult to control the dissolution temperature, impart water resistance in a short time, impart alkali resistance, and the like. The method for producing the film in the present invention is not particularly limited, and a known method may be employed. The methods (A) and (B) may be separately formed by extrusion molding or the like and then laminated, or may be formed by coextrusion molding or multilayer inflation. Molding, multilayer blow molding, and the like are used. At the time of such molding, a coloring agent, if necessary,
Ordinary additives such as fragrances, extenders, defoamers, release agents, and ultraviolet absorbers may be appropriately blended, and ordinary polyvinyl alcohol, starch, carboxymethylcellulose, methylcellulose, and hydroxymethylcellulose as long as the properties are not lost. May be mixed. Such a polyvinyl alcohol-based laminated film is water resistant in a two-layer system,
Although it is sufficiently excellent in alkali resistance, heat resistance, mechanical strength, etc., if necessary, it is also possible to laminate a partially saponified oxyalkylene group-containing polyvinyl alcohol resin as an intermediate layer. There is no particular limitation on the advantageous substance to be packaged using the thus obtained laminated film, as long as it is a solid substance exhibiting an alkaline property and is used by dissolving in water at the time of use.For example, detergents and agricultural chemicals, It is suitably used for unit packaging of fertilizers, photographic developers, dyes and the like. In the present invention, by laminating two kinds of oxyalkylene group-containing polyvinyl alcohol-based films having a specific oxyalkylene group content and a degree of saponification, the alkali resistance and the water resistance are always sufficient. While having this, the dissolution or swelling temperature was set to some extent freely, and the range of use of such a film was expanded. The present invention will be described below in more detail with reference to examples. Example 1 As the outer layer, an average polymerization of 620, a copolymerization ratio of polyoxyethylene monoallyl ether (condensation degree of oxyethylene of 15) units of 0.4 mol%, a ratio of oxyalkylene units in the whole polymer of 5.9% by weight, acetic acid The degree of saponification of the vinyl component is an oxyalkylene group-containing polyvinyl alcohol-based resin composed of 95 mol%, and the average degree of polymerization is 6 as an inner layer.
20, the copolymerization ratio of polyoxyethylene monoallyl ether (condensation degree of oxyethylene 20) units is 0.75 mol%, the ratio of oxyalkylene units in the whole polymer is 13.0% by weight, the saponification degree of vinyl acetate component is An oxyalkylene group-containing polyvinyl alcohol-based resin composed of 92 mol% is supplied to an extruder equipped with a two-layer ring die and melted at a temperature of 210 ° C. from a ring die slit having a slit diameter of 100 mm and a slit clearance of 1.5 mm. The film was discharged at 210 ° C., blown with cooling air to form a cylindrical film, flattened with a stabilizer, and wound up with a pinch roller to obtain a laminated film having a thickness of 100 μm (each 50 μm). The discharge rate of such resin is 10 kg /
hr, the film take-up speed was 10 m / min. The laminated film was set to be dissolved at 40 ° C. The physical properties of the laminated film were measured by the following methods. (1) A laminated film having a water resistance of 20 cm × 20 cm was prepared. This laminated film is placed on a horizontal plane such that the outer layer is on the upper side, and 10 drops of distilled water are dropped with a Komagome pipette to 30
After standing for a minute, water droplets were wiped off and the film was visually observed. No swelling at all ... ○ Swells slightly .... △ Film breaks. × (2) Laminate a 2cm × 2cm laminated film in hot water and water. It was measured. Completely dissolved within 3 minutes ・ ・ ・ ◎◎ Completely dissolved in 3 to 10 minutes ・ ・ ・ ・ ・ ・ ○ Completely dissolved in 10 to 30 minutes ・ ・ ・ ・ ・ ・ △ Not completely dissolved in more than 30 minutes ・ ・× (3) Alkali resistance 10 g of an alkaline detergent is placed in a bag made of a laminated film of 5 cm × 5 cm and heat-sealed.
It was left for 2 months in the environment of RH. The detergent-containing film after standing was put into water adjusted to a dissolution set temperature, and the complete dissolution time was measured. Completely dissolved within 3 minutes ・ ・ ・ ◎◎ Completely dissolved within 3 to 10 minutes ・ ・ ・ ・ ・ ・ ○ Completely dissolved within 10 to 30 minutes ・ ・ ・ ・ ・ ・ ・ △ Not completely dissolved within 30 minutes ・ ・C. Example 2 As the outer layer, the average polymerization degree was 390, and the copolymerization ratio of polyoxyethylene monoallyl ether (oxyethylene condensation degree 15) units was 0.1. 5 mol%, the ratio of oxyalkylene units in the whole polymer is 7.3% by weight, and the degree of saponification of the vinyl acetate component is 95 mol%. Oxyethylene monoallyl ether (degree of condensation of oxyethylene 20) units copolymerization ratio 0.8 mol%, ratio of oxyalkylene units in the whole polymer 13.8 times %, The degree of saponification of the vinyl acetate component was 92 mol%, and the mixture was fed to an extruder using an oxyalkylene group-containing polyvinyl alcohol-based resin and co-extruded at 210 ° C. to form a laminated film having a thickness of 100 μm (each 50 μm). Obtained. The laminated film was set to melt at 37 ° C. The physical properties of the laminated film were measured according to Example 1. The results are summarized in Table 1. Table 1 Water resistance Hot water water solubility Alkali resistance Example 1 ○ ○ Example 2 ○ ○ の本 本】 本 本 本 本 本 本 本 本 本. By laminating two kinds of oxyalkylene group-containing polyvinyl alcohol films with a degree of saponification, the dissolution or swelling temperature can be set to some extent freely while always having sufficient alkali resistance and mild water resistance. However, since the range of use of such a film can be expanded, it is very industrially advantageous.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (1)

(57) Claims 1. An oxyalkylene group-containing polyvinyl alcohol-based resin (A) having an oxyalkylene group content of 1 to 20% by weight and a saponification degree of 90 to 100% by mole as an outer layer. When the oxyalkylene group content is 10 % by weight or more, 1
A laminated film having an oxyalkylene group-containing polyvinyl alcohol-based resin (B) having an inner layer of less than 5% by weight and a saponification degree of 80 to 100 mol%, and (B)
Wherein the difference between the oxyalkylene group content in the oxyalkylene group-containing polyvinyl alcohol-based resin (A) and the oxyalkylene group content in the oxyalkylene group-containing polyvinyl alcohol-based resin (A) is 5.0% by weight or more. Polyvinyl alcohol-based laminated film .