JPH0568504B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a cold water easily soluble film for packaging, and more specifically, it is made of a water soluble polymer obtained by saponifying a copolymer of allyl ester and vinyl ester, and is a direct cast type film. The present invention relates to a cold water easily soluble film suitable for use in packaging materials. (Prior Art) In recent years, water-soluble films have been used for packaging purposes. Packaging of water-soluble or water-dispersible solid substances in a dry state, especially those that are harmful to the user, require accurate weighing during use, or are difficult to remove when in contact with the human body. It is used for purposes. These dry solid substances include cleaning products such as laundry detergents and bleaches, chemicals such as herbicides, insecticides, and fungicides, and finely powdered water-soluble or Examples include water-dispersible substances. In this case, when a predetermined amount of the fine powder substance is packaged in a water-soluble film and put into water without opening the package during use, the packaging film dissolves in a short time and the fine powder substance inside becomes water-soluble. It is necessary to dissolve or disperse the Therefore, films used for packaging are required to be readily soluble in cold water. Conventionally, polyvinyl alcohol (hereinafter abbreviated as PVA) has been used as a film-forming substance for such water-soluble films. In that case, partially saponified PVA is used because fully saponified PVA is difficult to dissolve in cold water. Partially saponified PVA is easily soluble in cold water, but when it comes into contact with alkaline substances, the saponification reaction progresses due to the alkali, resulting in poor stability over time. There was a problem that became difficult. Recently, as a way to improve this drawback, a water-soluble film using PVA modified with unsaturated carboxylic acid as a film-forming material has been commercially available ["Applications and Markets of Water-Soluble Polymers", Paragraphs 266-277 (C.M.C. occurrence)〕. (Problem to be solved by the invention) However, when modified with an unsaturated carboxylic acid,
A film made of PVA does not lose its cold water solubility even when it comes into contact with an alkaline substance, but has the disadvantage that its cold water solubility is impaired when it comes into contact with an acidic substance. Therefore, an object of the present invention is to provide a cold water easily soluble film for packaging whose cold water solubility is not impaired even if it comes into contact with either alkaline or acidic substances for a long period of time. (Means for Solving the Problems) In order to achieve the above objectives, the present inventors have conducted intensive research and found that a water-soluble film made of a specific water-soluble polymer is exposed to an alkaline substance or an acidic substance for a long period of time. The present inventors have discovered that even when they come into contact, their cold water solubility is not impaired, leading to the completion of the present invention. That is, the present invention uses a water-soluble polymer having a saponification degree of 65 mol% or more obtained by saponifying a copolymer of 2 to 40 mol% of allyl ester and 98 to 60 mol% of vinyl ester as a film-forming substance. The object of the present invention is to provide a cold water easily soluble film for packaging, which is characterized by the following characteristics. The production of a copolymer of allyl ester and vinyl ester and its saponification for producing a water-soluble polymer in the present invention are described, for example, in
This can be carried out by a method known in Japanese Patent No. 102937. First, copolymerization of allyl ester and vinyl ester is obtained by copolymerizing allyl ester and vinyl ester in the presence of a polymerization catalyst using a lower alcohol such as methanol as a solvent. The allyl ester in the copolymer ranges from 2 to 40 mol%, preferably from 5 to 30 mol%. If the allyl ester content is less than 2 mol %, the saponified product will have poor cold water solubility, and if it comes into contact with an alkaline or acidic substance, the cold water solubility will be impaired. On the other hand, 40
If the amount exceeds mol%, the strength of the film may decrease, making it unsuitable for packaging. The degree of polymerization of the copolymer is not particularly limited, but preferably 200 to 3000. Moreover, the saponified product of the copolymer can be obtained by adding an acid or an alkali to an alcoholic solution or hydroalcoholic solution of the copolymer and saponifying the solution. Examples of the alcohol include methanol, ethanol, etc., and methanol is preferably used. As a saponification catalyst, sodium hydroxide,
An alkaline catalyst such as sodium methylate or an acid catalyst such as sulfuric acid or hydrochloric acid is used. Saponification degree of allyl ester and vinyl ester components is 65 mol%
It is preferable to increase the content to 90 mol% or more. If the saponification degree is too low, cold water solubility will be poor. The water-soluble polymer of the present invention can be obtained by heat-drying the saponified product obtained by saponification as described above and pulverizing it if necessary. Examples of allyl esters in the present invention include allyl formate, allyl acetate, allyl butyrate, allyl caproate, and allyl maleate. Examples of vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, and allyl lauric acid. Among them, allyl acetate and vinyl acetate are particularly preferred industrially. Allyl ester and vinyl ester may be used alone or in combination.
It is also possible to use a mixture of more than one type. The copolymer of allyl ester and vinyl ester in the present invention may also include monomers copolymerizable with vinyl ester and/or allyl ester, such as crotonic acid and (meth)acrylic acid. Saturated monocarboxylic acids and their esters, unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid and their anhydrides, monoalkyl esters, alkali metal salts, ethylene,
α-olefins such as propylene, (meth)allylsulfonic acid, ethylenesulfonic acid, sulfonic acid malate and their alkali metal salts, amide group-containing monomers such as acrylamide and N-methylolacrylamide, alkyl vinyl ethers, vinyl pyrrolidone, etc. They may be copolymerized within a range that does not impair the effects of the present invention. The easily cold water-soluble film for packaging of the present invention is obtained by using the above-mentioned water-soluble polymer as a film-forming substance. The film forming method is as follows:
Known methods such as a casting method and an extrusion method can be used as appropriate. Further, the thickness of the film is arbitrary, but preferably 10μ to 150μ. Furthermore, when forming a film, a plasticizer may be added to the water-soluble polymer as necessary. Preferred plasticizers include, for example, glycerin, diethylene glycol, triethylene glycol, polyethylene glycol, polyglycerol, tetraethylene glycol, triethanolamine, 1,3-
Examples include butanediol, triethanolamine acetate, and ethanolacetamide. In addition, the cold water easily soluble film for packaging of the present invention is
As long as the effects of the present invention are not impaired, for example,
PVA, starches, cellulose derivatives, water-soluble polymers such as polyacrylic acid or its alkali metal salts, aqueous emulsions/suspensions, or materials containing pigments such as clay and titanium oxide may be used. (Example) Next, the present invention will be described in more detail with reference to Examples. Note that "parts" and "%" in the examples indicate "parts by weight" and "% by weight" unless otherwise specified. Reference Example 1 (Synthesis of water-soluble polymer) 1000 parts of vinyl acetate and 25 parts of allyl acetate were charged into a flask equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, and after replacing the system with _N2 ,
The internal temperature was raised to 60°C. To this system, add 10 parts of 2,2'-azobisisobutyronitrile to 300 parts of methanol.
A solution dissolved in 1 part was added to start polymerization. 225 parts of allyl acetate was added dropwise at a constant rate during 5 hours after the start of polymerization, and the polymerization was stopped after 6 hours. The solid content concentration in the system at the time of termination of polymerization was 50%, and the polymerization yield based on all monomers was 62%. After expelling unreacted vinyl acetate and allyl acetate under reduced pressure, a 45% methanol solution of the copolymer was obtained. It was confirmed by quantitative determination of unpolymerized allyl acetate and vinyl acetate that the copolymer contained 15 mol% of allyl acetate units and 85 mol% of vinyl acetate units. While stirring 100 parts of a methanol solution of this copolymer at 40°C, 15 parts of a 1N methanol solution of caustic soda was added thereto, mixed well, and then allowed to stand. After 30 minutes, the solidified polymer was pulverized using a pulverizer, washed with methanol, and dried to obtain a polymer powder. The obtained powder was dissolved in water and the viscosity was measured at 30°C, and it was found to be 8 centipoise at a solid content concentration of 4%. Moreover, the degree of saponification of this powder was 98 mol%. Reference Example 2 (Synthesis of water-soluble polymer) Using 1000 parts of vinyl acetate and 50 parts of allyl acetate,
After performing _N2 substitution and heating to 60°C in the same manner as in Reference Example 1, a solution of 5 parts of 2,2'-azobisisobutyronitrile dissolved in 260 parts of methanol was added to the system, Polymerization started. Polymerization was stopped 5 hours after the start of polymerization. The solid content concentration in the system was 60%. Then, unreacted allyl acetate and vinyl acetate were removed in the same manner as in Reference Example 1 to obtain a 47% methanol solution of the copolymer. It was confirmed by the same quantitative method as in Reference Example 1 that the copolymer contained 6 mol% of allyl acetate units and 94 mol% of vinyl acetate units. While stirring 100 parts of a methanol solution of this copolymer at 40°C, 13 parts of a 1N methanol solution of caustic soda was added in the same manner as in Reference Example 1 to obtain a solidified polymer, which was crushed, washed, and dried. A polymer powder was obtained. This powder was dissolved in water and its viscosity was measured at 30°C and found to be 15 centipoise at a solid content of 4%.
Moreover, the degree of saponification of this powder was 94 mol%. Design Example 3 (Synthesis of water-soluble polymer) Using 1000 parts of vinyl propionate and 25 parts of allyl butyrate, the system was replaced with _N2 and heated to 60°C in the same manner as in Reference Example 1, and then 2, A solution of 10 parts of 2'-azobisisobutyronitrile dissolved in 300 parts of methanol was added to initiate polymerization. 225 parts of allyl acetate was added dropwise at a constant rate during 5 hours after the start of polymerization, and the polymerization was stopped after 6 hours. The solid content concentration in the system at the time of termination of polymerization was 48%. Next, reference example 1
Unreacted vinyl propionate and allyl butyrate were removed in the same manner as above to obtain a 47% methanol solution of the copolymer. The copolymer has 7 allyl butyrate units.
It was confirmed by the same quantitative method as in Reference Example 1 that it contained 93 mol% of vinyl propionate units. While stirring 100 parts of a methanol solution of this copolymer at 40°C, 13 parts of a 1N methanol solution of caustic soda was added in the same manner as in Reference Example 1 to obtain a solidified polymer, which was crushed, washed, and dried. A polymer powder was obtained. When this powder was dissolved in water and the viscosity was measured at 30°C, it was 10 centipoise at a solid content of 4%.
The degree of saponification of this powder was 96 mol%. Example 1 The powder obtained in Reference Example 1 was dissolved in water to prepare a 10% aqueous solution. This aqueous solution was cast using an applicator onto a polyester plate with a smooth and horizontal surface, and dried in an oven to obtain a transparent and uniform film. The thickness of the obtained film was 28μ. A bag with a size of 5 x 5 cm was made from the obtained film, and 20 g of laundry detergent (trade name: "Zabu" manufactured by Kao) was placed in the bag and heat-sealed. Heat-sealed bags were also produced in the same manner for sodium carbonate powder, ammonium sulfate salt powder, or herbicide (trade name "Kitajin P" Kumiai Chemical). This product was left at room temperature for 1 year, and after 6 months and 1 year, a 1 x 1 cm film was cut out and immersed in water at 20°C to measure the time required for the film to completely dissolve (the time required for the film to dissolve). The results are shown in Table 1. As is clear from Table 1, all of them maintained easy solubility in cold water with almost no change in solubility over time. Example 2 The powder obtained in Reference Example 2 was dissolved in water to prepare Example 1.
A film was prepared in the same manner as in Example 1, and the change over time in the water solubility of the film due to the drug was measured in the same manner as in Example 1. The results are shown in Table 1. The thickness of the film was 27μ. As is clear from Table 1, the changes over time for all drugs were greater than in Example 1, but they substantially maintained easy cold water solubility. Example 3 The powder obtained in Reference Example 2 and 10% glycerin were dissolved in water to prepare a 12% aqueous solution. A film was prepared using this aqueous solution in the same manner as in Example 1, and the change in water solubility of the film due to the drug over time was measured in the same manner as in Example 1. The results are shown in Table 1. In addition, the film thickness is
It was 32μ. As is clear from Table 1, all the drugs were easily cold water-soluble films with little change in solubility over time. Comparative Example 1 A film was prepared in the same manner as in Example 1, except that PVA having a saponification degree of 88 mol% and a 4% aqueous solution having a viscosity of 7 centipoise at 30°C was used instead of the powder obtained in Reference Example 1. We measured the change in the water solubility of the film over time due to the drug. Table 1 shows the results.
Shown below. The thickness of the film was 28μ. As is clear from Table 1, the cold water solubility of the film was impaired by any of the drugs. Comparative Example 2 Containing 1.5 mol% of maleic acid groups instead of the powder obtained in Reference Example 1, the degree of saponification was 96 mol%, 30
A film was prepared in the same manner as in Example 1 except that modified PVA having a viscosity of 4% aqueous solution at 10 centipoise at °C was used, and the change over time in the water solubility of the film due to the drug was measured. The results are shown in Table 1. The thickness of the film was 28μ. As is clear from Table 1, alkaline substances remained easily soluble in cold water, but those that came into contact with acidic substances became less soluble in cold water. Comparative Example 3 A film was prepared in the same manner as in Example 3, except that PVA with a saponification degree of 93 mol% and a 4% aqueous solution having a viscosity of 16 centipoise at 30°C was used instead of the powder obtained in Reference Example 2. We measured the change in the water solubility of the film over time due to the drug. Table 1 shows the results.
Shown below. As is clear from Table 1, the cold water solubility of the film was impaired by any of the drugs. Example 4 The powder obtained in Reference Example 3 was dissolved in water, a film was prepared in the same manner as in Example 1, and the change over time in the water solubility of the film due to the drug was measured. The results are shown in Table 1. Note that the thickness of the film was 25μ. As is clear from Table 1, all drugs showed almost no change over time and remained easily soluble in cold water.

【table】

[Table] Reference Examples 4 to 7 The following powdered polymers were obtained in a manner similar to Reference Examples 1 to 3. Reference example 4: Allyl acetate unit is 1.0 mol% 30°C, 4% aqueous solution viscosity is 10 centipoise Saponification degree is 98 mol% Reference example 5: Allyl acetate unit is 3.0 mol% 30°C, 4% aqueous solution viscosity is 9 centipoise Saponification degree is 97.5 mol% Reference example 6: Allyl acetate unit is 35 mol% At 30℃, 4% aqueous solution viscosity is 6 centipoise Saponification degree is 68 mol% Reference example 7: Allyl acetate unit is 43 mol% At 30℃, 4% aqueous solution viscosity is 68 mol% 4 centipoise Saponification degree is 98 mol% Examples 5, 6 and Comparative Examples 4, 5 The powders obtained in Reference Examples 4 to 7 are dissolved in water,
A 10% aqueous solution was prepared. This aqueous solution was cast onto a flat polyester plate with a smooth surface, and heated to 65% at 20°C.
It was left to dry at RH to obtain a uniform film with a thickness of 100μ. Table 2 shows the characteristic values of the obtained film. The breaking strength and breaking elongation of the film were measured using a Strograph (manufactured by Toyo Seiki Co., Ltd.) at 20° C., 65% RH, and a tensile speed of 50 mm/min. Regarding heat sealability, we stacked two films and used an impulse heat sealer to heat seal them for 2 seconds at a temperature of 180℃ and a load of 1Kg/cm ² to evaluate the heat sealability as follows. did. ○: Not fused and peeled off ×: Easily peeled off As is clear from Examples 5 and 6 and Comparative Examples 4 and 5 in Table 2, the films of Examples were easily soluble in cold water;
Although both strength and heat-sealability are good, Comparative Example 4 has a small amount of allyl acetate unit, which is a component of the polymer, at 1 mol %, is not easily soluble in cold water, and has poor heat-sealability. In addition, in Comparative Example 5, the allyl acetate unit was
It is 43 mol% and is soft and cannot maintain its shape.

[Table] (Effects of the Invention) The film of the present invention is easily soluble in cold water, and its cold water solubility is not impaired even when it comes into contact with alkaline or acidic substances. Therefore, the film of the present invention is particularly suitable for water-soluble or water-dispersed materials that are harmful to the user, require accurate metering during use, or are difficult to remove when in contact with the human body. Suitable for packaging films for solid substances. The packaged product can be directly put into water when used. That is, the film of the present invention is a cold water easily soluble film for packaging a packaged product containing chemicals and the like, which is used by putting it into water as it is;
It is suitable as a cold water easily soluble film for packaging so-called direct throw type packages.

Claims (1)

[Claims] 1. A water-soluble polymer with a degree of saponification of 65% or more obtained by saponifying a copolymer of 2 to 40 mol% of allyl ester and 98 to 60 mol% of vinyl ester is used as a film-forming substance. A cold water easily soluble film for packaging, which is characterized by: 2. The cold water easily soluble film for packaging according to claim 1, wherein the allyl ester is allyl acetate. 3. The cold water easily soluble film for packaging according to claim 1, wherein the vinyl ester is vinyl acetate.