JP2007070493A - Water-soluble film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-soluble film superior in solubility in a cold water, useful as packing materials for various kinds of medicines such as agrochemicals and detergents for washing, specially suitable for packing of a fiber softening agent. <P>SOLUTION: The water-soluble film is formed by containing a polymer obtained by graft polymerization of vinylpyrrolidone to polyvinyl alcohol. It is preferable that the water-soluble film contains 10 wt.% or more of the polymer having a K value of 12-150 and obtained by graft-polymerizing vinylpyrrolidone to polyvinyl alcohol of which the polymerization degree is 100-4,000, and the saponification degree is 70-100 mole%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water-soluble film suitably used for packaging various chemicals.

  In recent years, various chemicals such as laundry detergents, agricultural chemicals, bleaching agents, toiletry products, industrial chemicals, etc., have been sealed and packaged (unit packaging) with a water-soluble film, and then put into the water as it is. Is being used by dissolving or dispersing the whole packaging film in water. Such unit packaging can be used without direct contact with dangerous chemicals on the body, the content is packed in a certain amount, so there is no need to measure it at the time of use, and the container packaging the medicine This is useful in that processing after use is unnecessary.

  As an example of unit packaging of various chemicals using a water-soluble film, it has been disclosed to unit-pack a single detergent used for washing clothes with a water-soluble film made of partially saponified polyvinyl alcohol (Patent Document 1). . However, the water-soluble film made of partially saponified polyvinyl alcohol has a problem that the solubility of the film in low-temperature water is not sufficient, and the solubility in water decreases when stored for a long time in a state where an alkaline detergent is packaged. Has the problem.

  In contrast, attempts have been made to improve the solubility of water-soluble films in water by introducing an anionic group into polyvinyl alcohol. Using such a water-soluble film made of polyvinyl alcohol modified with an anionic group, a sheet-like detergent package in which a water-soluble film is bonded on both sides of a layer containing a detergent composition is manufactured, or a liquid detergent is packaged. Or packaging an alkaline substance (Patent Documents 2 to 4).

  Conventionally, the fiber softener has been mainly liquid type containing 3 to 15% by weight of a cationic surfactant. However, in recent years, there is a tendency to increase the concentration in order to reduce the amount used. When such a fiber softener is required to be unit-wrapped with a water-soluble film, when the fiber softener is packaged using a water-soluble film made of polyvinyl alcohol modified with an anionic group, There is a problem that the solubility in cold water is remarkably reduced, and the solubility in water decreases with time when the fiber softener is stored for a long time in a packaged state. Although the reason is not clear, it is considered that an anionic group part contained in polyvinyl alcohol and a cationic substance which is a main component of the fiber softener cause an interaction.

As a method for solving this problem, it has been proposed to introduce a specific unsaturated compound into polyvinyl alcohol (Patent Document 5). However, even when a fiber softener is packaged using a water-soluble film made of polyvinyl alcohol modified with a specific unsaturated compound as described above, the solubility of the water-soluble film in water is not always sufficient, Moreover, when it preserve | saved for a long time in the state which packaged the fiber softener, there existed a problem that the solubility to water fell.
JP-A-61-57700 JP 10-72599 A Japanese Patent No. 3262406 Japanese Patent Laid-Open No. 9-324096 Japanese Patent Laid-Open No. 2002-3896

  The present invention has been made in view of the above, and an object thereof is to provide a water-soluble film having excellent solubility in cold water. Moreover, it is useful as a packaging material for various chemicals such as agricultural chemicals and laundry detergents, and an object thereof is to provide a water-soluble film particularly suitable for packaging of fabric softeners.

  As a result of intensive studies, the present inventors have found that a polymer obtained by graft-polymerizing vinyl pyrrolidone to polyvinyl alcohol (hereinafter, also simply referred to as a graft polymer) is extremely useful in producing a target water-soluble film, The present invention has been completed.

  That is, the water-soluble film of the present invention contains a polymer obtained by graft polymerization of vinyl pyrrolidone to polyvinyl alcohol.

  In the above, 10% by weight or more of a polymer having a K value of 12 to 150 obtained by graft polymerization of vinyl pyrrolidone to polyvinyl alcohol having a polymerization degree of 100 to 4000 and a saponification degree of 70 to 100 mol%. Is preferred.

  As a polymer obtained by graft-polymerizing vinyl pyrrolidone with polyvinyl alcohol, a polymer obtained by blending vinyl pyrrolidone with a polyvinyl alcohol solution and polymerizing with hydrogen peroxide or an organic peroxide as an initiator may be used. it can.

  The water-soluble film of the present invention has excellent solubility in cold water, and is useful as a packaging material for various abrasives such as agricultural chemicals and laundry detergents. In particular, even when the fiber softener is packaged and stored for a long period of time, the solubility is unlikely to decrease, so that it is suitably used as a fiber softener packaging film.

  Polyvinyl alcohol (hereinafter sometimes referred to as PVA) as a raw material for the graft polymer used in the present invention preferably has a degree of polymerization of 100 to 4000, and more preferably 100 to 3000. When the degree of polymerization is less than 100, the strength of the film becomes weak, and when it exceeds 4000, the time required for dissolution in water becomes long.

  The saponification degree of polyvinyl alcohol is preferably 70 to 100 mol%, and more preferably 70 to 99 mol%. If the degree of saponification is less than 70 mol%, the strength of the film becomes weak, and if it exceeds 99 mol%, it may be difficult to prepare an aqueous solution.

  Furthermore, when the K value of the graft polymer is less than 12, the strength of the film becomes weak, and when it exceeds 150, it becomes difficult to use because it is hardly soluble in water.

  The amount of vinylpyrrolidone in the graft polymer is preferably 5 to 900% by weight with respect to polyvinyl alcohol. If it is less than 5% by weight, sufficient water solubility cannot be obtained, and if it exceeds 900% by weight, the strength of the film tends to be lowered.

  The water-soluble film of the present invention preferably contains 10% by weight or more of the graft polymer. If it is less than 10% by weight, it is difficult to obtain the intended effect of the present invention.

  The graft polymer can be obtained by a production method in which vinyl pyrrolidone is blended in a polyvinyl alcohol solution and polymerized using an appropriate initiator.

  As the initiator, hydrogen peroxide or organic peroxide usually used for radical polymerization can be used. Examples of the organic peroxide include tert-butyl hydroperoxide, di-tert-butyl peroxide, benzoyl peroxide and the like. What is necessary is just to select the reaction method and reaction conditions according to the example of general radical polymerization.

  In general, a water-soluble film is required to have a strength that can withstand use in a hot and humid region or a cold region, and particularly needs to have impact resistance at a low temperature. For the purpose of improving the impact resistance at low temperatures, various plasticizers can be blended with the water-soluble film of the present invention in order to lower the glass transition point of the water-soluble film. Furthermore, a plasticizer can also be blended for the purpose of improving solubility in water and processability.

  As the plasticizer, those generally used as a plasticizer for PVA are used without particular limitation. For example, glycerin, diglycerin, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, pentaerythritol, 1 Polyhydric alcohols such as 1,3-butanediol; Polyethers such as polyethylene glycol and polypropylene glycol; Polyvinylamides such as polyvinylpyrrolidone; Phenol derivatives such as bisphenol A and bisphenol S; N-methylpyrrolidone and dimethylacetamide Amide compounds; compounds obtained by adding ethylene oxide to polyhydric alcohols such as glycerin, pentaerythritol, sorbitol, water, etc. Or more can be used species or two or. Among these plasticizers, glycerin, diglycerin, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, polyethylene glycol, and polyvinylpyrrolidone are used for the purpose of improving the water solubility of the water-soluble film. Is preferred. Furthermore, glycerin, diglycerin, trimethylolpropane, polyethylene glycol, and polyvinyl pyrrolidone are particularly preferable from the viewpoint of suppressing a decrease in water solubility of the water-soluble film due to bleed out of the plasticizer.

  There is no particular restriction on the molecular weight of polyethylene glycol when polyethylene glycol is used as a plasticizer, but the number average molecular weight is compatible with the graft polymer and suppresses the decrease in water solubility of the water-soluble film due to bleeding out. Is preferably 100 to 1000. Although there is no restriction | limiting in particular also about the molecular weight of polyvinylpyrrolidone, It is preferable that it is 1000-20000 in a weight average molecular weight from a compatible point with a graft polymer.

  The blending amount of the plasticizer is preferably 1 to 50 parts by weight, more preferably 1 to 35 parts by weight with respect to 100 parts by weight of the graft polymer. When the blending amount of the plasticizer is less than 1 part by weight, the effect of blending the plasticizer may not be manifested. On the other hand, when the blending amount of the plasticizer exceeds 50 parts by weight, the bleedout of the plasticizer increases and the resulting water-soluble film may have a reduced blocking resistance. If the plasticizer in the water-soluble film is transferred to the contents of the package, the water solubility of the water-soluble film may decrease over time, or the flexibility at low temperatures may decrease. In order to avoid such a situation, the amount of the plasticizer is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the graft polymer.

  Moreover, the heat seal temperature of a water-soluble film falls, so that the compounding quantity of a plasticizer increases, and there exists a tendency for the productivity at the time of bag-making a water-soluble film to improve. From such a viewpoint, it is preferable to blend the plasticizer at a rate such that the heat seal temperature of the obtained water-soluble film is 170 ° C. or lower, and the plasticizer is blended at a rate so as to be 160 ° C. or lower. Is more preferable.

Furthermore, the compounding amount of the plasticizer tends to affect the strength and Young's modulus of the resulting water-soluble film. From the practical point of the water-soluble film, the strength of the film is preferably 0.5 kg / mm ² or more, and more preferably 0.8 kg / mm ² or more. From the viewpoint of shape stability of the obtained water-soluble film and processability such as a bag making machine, the Young's modulus of the water-soluble film is preferably 0.5 kg / mm ² or more, and 1.0 kg / mm ² or more. More preferably. Therefore, it is preferable to add a plasticizer so that a water-soluble film having such a strength and Young's modulus in such a range can be obtained.

  Sugar can be mix | blended with the water-soluble film of this invention as needed, and, thereby, the solubility to water and form stability of a water-soluble film can be improved more. As the saccharide, any of monosaccharides such as glucose, chain sugar alcohols such as oligosaccharides, polysaccharides and mannitol can be used. Examples of polysaccharides include starch, cellulose, chitin, chitosan, hemicellulose, pectin, pullulan, agar, alginic acid, carrageenan, dextrin, trehalose, and the like, and one or more of these can be used. Examples of the chain sugar alcohol include tetrites having 4 carbon atoms such as trait and erythrite, pentites having 5 carbon atoms such as arabit and xylit, and hexits having 6 carbon atoms such as glycit, mannitol and sorbit. .

  Starch is particularly preferable among the above saccharides from the viewpoint that the solubility of the water-soluble film in cold water becomes better. As the starch, for example, raw starch such as corn and potato, and modified starch (dextrin, oxidized starch, etherified starch, cationized starch, etc.) obtained by subjecting these to physical or chemical treatment can be used.

  The amount of the saccharide is 1 to 30 parts by weight with respect to 100 parts by weight of the graft polymer from the viewpoint of the form stability of the water-soluble film and the cold water solubility of the packaging body in which the fiber softener is packaged with the water-soluble film. It is preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight. If the amount of saccharide is less than 1 part by weight, the effect of improving the form stability of the water-soluble film and the solubility in cold water may not be exhibited. On the other hand, when the amount of the saccharide is more than 30 parts by weight, the solubility in water may be lowered, particularly when the package is dissolved with a small amount of water (at the time of high cation concentration).

  If necessary, the water-soluble film of the present invention can further contain an inorganic filler. By using an inorganic filler, anti-blocking properties can be imparted to the water-soluble film. Examples of inorganic fillers that can be used are silica, heavy, light or surface-treated calcium carbonate, aluminum hydroxide, aluminum oxide, titanium oxide, diatomaceous earth, barium sulfate, calcium sulfate, zeolite, zinc oxide, silicic acid, silicic acid Examples thereof include clay, talc and the like such as salt, mica, magnesium carbonate, kaolin, halosite, pyroferrite, and sericite, and one or more of these can be used. Among these, silica and talc are preferable because the dispersibility of the graft polymer is good. The average particle diameter of the inorganic filler is preferably 1 μm or more from the viewpoint of antiblocking properties of the water-soluble film, and is preferably 10 μm or less from the viewpoint of dispersibility in the graft polymer. In order to satisfy both requirements of the anti-blocking property of the water-soluble film expressed by blending the inorganic filler and the dispersibility of the inorganic filler in PVA, the average particle size is more preferably about 1 to 7 μm. .

  The blending amount of the inorganic filler is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of PVA from the viewpoint of anti-blocking of the water-soluble film and dispersibility of the inorganic filler in PVA. The amount is more preferably 15 parts by weight, and particularly preferably 1 to 10 parts by weight. In addition, when it mixes over 20 weight part of inorganic fillers, the dispersibility to PVA will fall, an inorganic filler will aggregate, and there exists a tendency for the water solubility of the water-soluble film obtained to fall.

  In the water-soluble film of the present invention, additives such as a colorant, a fragrance, an extender, an antifoaming agent, a release agent, an ultraviolet absorber, and a surfactant can be appropriately blended as necessary. For example, by blending a surfactant at a ratio of 0.01 to 5 parts by weight with respect to 100 parts by weight of the graft polymer, a metal surface such as a die or a drum of the film forming apparatus, a film formed, or a film stock solution And the peelability can be improved.

  In addition, the water-soluble film of the present invention may have a different type of PVA, carboxymethylcellulose, polyacrylamide, polyacrylic from the graft polymer used in the present invention, as long as the effects of the present invention are not impaired. A water-soluble polymer such as an acid or a salt thereof, methylcellulose, or hydroxymethylcellulose can also be blended. In particular, the water solubility of the film can be further improved by adding a low-viscosity type carboxymethylcellulose.

  The method for producing the water-soluble film of the present invention is not particularly limited, but if necessary, the above graft polymer is blended with a plasticizer, a saccharide, an inorganic filler and other components, and dissolved in a solvent in a stirring tank. What is necessary is just to prepare a manufacturing raw material by preparing by mixing by a well-known method, such as the method of disperse | distributing and the method of melt-kneading in an extruder.

  A film-forming method generally used for forming a film from the above-mentioned raw materials, for example, a casting film-forming method, a wet film-forming method, a dry film-forming method, an extrusion film-forming method, a melt film-forming method, a coat A water-soluble film can be produced by a film-forming method such as a method or an inflation film-forming method. For example, the components necessary for the production of the water-soluble film of the present invention include one or more solvents such as water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, methanol, n-propanol, i-propanol, and phenol. What is necessary is just to manufacture by film forming methods, such as a casting film forming method, after melt | dissolving in a liquid mixture and preparing uniform film forming stock solution. The concentration of the film-forming stock solution is preferably 70% by weight or less (the solvent content is 30% by weight or more) from the viewpoint of viscosity.

  The thickness of the water-soluble film of the present invention is preferably 10 to 200 μm, and more preferably 20 to 150 μm from the viewpoint of the balance between film strength and water solubility.

  In order to improve the anti-blocking property of the water-soluble film of the present invention, the surface of the water-soluble film is roll matted as necessary, or powder for preventing blocking such as silica and starch is applied to the water-soluble film. Or embossing. Roll matting of the film surface can be performed by forming fine irregularities on the roll that comes into contact with the film before drying during film formation. The embossing treatment can be generally performed by nipping between an embossing roll and a rubber roll while applying heat and pressure after the film is formed. Application of powder has a great effect of preventing blocking, but it may not be used depending on the application. There are no such restrictions on the roll matting or embossing treatment, and roll matting is particularly preferred from the viewpoint of the effect of preventing blocking.

  The water-soluble film of the present invention has an excellent dissolution rate in cold water, and the complete dissolution time in 5 ° C. water when the film thickness is 40 μm can be 80 seconds or less, more preferably 60 seconds or less, Particularly preferably, it is set to 40 seconds or less. In addition, the complete dissolution time in 5 ° C. water referred to in this specification is a value measured by a slide mount method. That is, it is a value obtained by measuring a time until a film is completely dissolved by cutting a 40 μm-thick film into a 40 mm × 40 mm square, sandwiching it in a slide mount, and immersing it in 5 ° C. water under stirring. . The complete dissolution time when the film thickness is different from 40 μm is a value obtained by converting the film thickness to 40 μm by the following formula (I).

Dissolution time (seconds) = (40 / film thickness (μm)) ² × dissolution time (seconds) (I)

  The water-soluble film of the present invention is excellent in cold water solubility when a fiber softener is packaged to form a package, and after packaging the fiber softener, the package left at room temperature for 10 minutes is 40 × 40 mm. A complete dissolution time (film thickness of 40 μm) in 5 ° C. water measured by a slide mount method can be 120 seconds or less, more preferably 100 seconds or less, and particularly preferably 80. Less than a second.

  In addition, the water-soluble film of the present invention has an advantage that the solubility hardly decreases with time even when the fiber softener is packaged and stored for a long time. As an accelerated test for long-term storage, a package in which a fiber softener is packaged with a water-soluble film is placed in a constant temperature and humidity chamber at 30 ° C. and 80% RH and taken out after 2 weeks. When the dissolution time of the film was measured by the above method, the ratio of the dissolution time (A) after leaving the packaging body wrapped with the fiber softener for 10 minutes at room temperature to the dissolution time (B) after the storage acceleration test ( B / A) is preferably 3.0 or less, more preferably 2.0 or less, further preferably 1.5 or less, and particularly preferably 1.20 or less.

  In order to package a fiber softener using the water-soluble film of the present invention, a method conventionally used for film-wrapping an article can be appropriately employed. As a method of packaging the fiber softener, the film after the fiber softener is packaged is heat-sealed using a three-side seal automatic packaging machine, or the peripheral portion of the film is adhered with an adhesive, and the obtained bag Examples thereof include a method of heat-sealing or bonding the open portion after filling the fabric softener from the open portion.

  The solid content obtained by drying the undissolved material remaining in the washing machine after using the packaging body in which the fiber softener is packaged with the water-soluble film of the present invention in a commercially available washing machine is preferably 1.0 g or less, and 0.5 g or less. Is more preferable, and 0.3 g or less is particularly preferable.

  The fiber softener that can be packaged with the water-soluble film of the present invention is not particularly limited, and all fiber softeners that are routinely used in general households are targeted. Specific examples thereof include quaternary ammonium salts such as di (hardened beef tallow alkyl) dimethylammonium chloride, methyl di (hardened beef tallow alkyl) amine (Japanese Patent Laid-Open No. 52-579965), acylated alkanolamine (Japanese Patent Laid-Open No. 58-60070). No. gazette). Since the water-soluble film of the present invention has a characteristic that the solubility in water does not decrease even when the cationic surfactant is packaged, it is also suitable for packaging the cationic surfactant.

  The fiber softener preferably has a moisture content of 10% by weight or less, more preferably 8% by weight or less, and particularly preferably 5% by weight or less. When the moisture content of the fiber softener exceeds 10% by weight, the plasticizer in the water-soluble film moves to the fiber softener side when packaged with a water-soluble film, and the plasticizer in the water-soluble film decreases. And the solubility of the package in water may be reduced. For the fabric softener, if necessary, solvents such as ethyl alcohol, isopropyl alcohol, propylene glycol, polyhydric alcohol, nonionic surfactants, water-soluble salts such as ammonium chloride, fragrances, colorants, antifoaming agents, An anti-redeposition agent, a fluorescent brightening agent, a bactericidal agent, a shrinking agent, a silicone compound, an inorganic electrolyte, an antibacterial agent, an antioxidant, a preservative, and the like may be blended.

  The fiber softener may be in any form such as solid, powder, granule, liquid and the like. A typical form of the fabric softener is a dispersion containing a dilong chain alkyl quaternary ammonium salt as a main component, but may be a powder or a tablet.

  When the fiber softener is packaged with a water-soluble film, the filling ratio of the fiber softener is preferably 60 to 98%, and more preferably 70 to 95%. If the filling rate of the fabric softener is too small, the package will contain a lot of air, so it will be difficult to sink in the water when the package is placed in the washing machine, and the dissolution time will tend to be long There is. For this reason, it is preferable that the filling rate of the fiber softener is 60% or more. On the other hand, when the filling rate of the fabric softener exceeds 98%, the package body sinks too quickly in water, and the package body tends to remain at the bottom of the washing machine and the solubility in water tends to decrease.

  Usually, the fabric softener is added at the time of final rinsing, but as a method to save labor, a separate drawer is provided in the washing machine, and when the laundry starts, a package containing the fiber softener is put in this drawer. There is a method in which the package is made to flow into the washing machine tub by the action of water used for rinsing. When using a package containing a fabric softener in a washing machine having such a structure, the amount of water that normally flows in the drawer is less than the amount of water in the washing tub. Needs to dissolve and flow down into the tank. In this case, if the amount of air is adjusted by changing the filling rate of the fabric softener in the package, when the water flows into the drawer, the package is appropriately floated by the buoyancy of the air, Since the lower part comes into contact with water, the package can be dissolved even with a small amount of water, and the package can be prevented from remaining in the drawer in a state where it does not dissolve in water.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the following examples and comparative examples, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.

[Examples 1 to 4, Comparative Examples 1 and 2]
Thereafter, 15 parts by weight of glycerin as a plasticizer and water are added to 100 parts by weight of each powdered polymer to prepare an equal 5% aqueous solution (water content 90%), which is cast on a polyester film at room temperature. After drying, a film having a thickness of 40 μm was obtained by peeling from the polyester film. The obtained film was heat-treated at 100 ° C. for 10 minutes. These films were evaluated as follows. The filling factor of the package was 90%.

Powdery polymer 1: Polyvinyl alcohol (PVA) (polymerization degree 200, saponification degree 98-99 mol%) grafted with vinylpyrrolidone (VP) (vs PVA 5.26 wt%), K value 23, solid content 97. 1% powder.
Powdery polymer 2: Powder having a K value of 31 and a solid content of 98.5% obtained by graft polymerization of VP (vs. PVA 42.9 wt%) to PVA (polymerization degree 2400, saponification degree 98-99 mol%).
Powdery polymer 3: Powder having a K value of 40 and a solid content of 96.3% obtained by graft polymerization of VP (vs. PVA 150 wt%) to PVA (polymerization degree 500, saponification degree 72.5-74.5 mol%).
Powdery polymer 4: Powder having a K value of 94 and a solid content of 99.0% obtained by graft polymerization of VP (vs. PVA 900 wt%) on PVA (polymerization degree 3500, saponification degree 87-89 mol%).
Powdered polymer 5: Powder of polyvinyl alcohol (polymerization degree 3500, saponification degree 87-89 mol%).
Powdery polymer 6: Polyvinylpyrrolidone K-30 powder.

  In Examples and Comparative Examples, measurement and evaluation of various properties of films were performed by the following methods.

[Method for evaluating film solubility (measurement of dissolution time) (1)]
A magnetic stirrer was installed in a constant temperature bath at 5 ° C. A 1 liter glass beaker containing 1 liter of distilled water was placed in the thermostatic bath and stirred at 330 rpm using a 5 cm rotor. After the distilled water in the beaker reached 5 ° C., water solubility measurement was started.

  That is, the film is cut into 4 cm × 4 cm squares, sandwiched between slide mounts, immersed in 5 ° C. stirring water, and the film dissolved state is observed. The time (seconds) until the film is completely dissolved. ) Was measured. When the film thickness was different from 40 μm, the film thickness was converted to a value of 40 μm according to the following formula (I).

Dissolution time (seconds) = (40 / film thickness (μm)) ² × dissolution time (seconds) (I)

[Method for evaluating solubility of film (measurement of dissolution time) (2)]
A 4.5cm x 4.5cm bag is made from the film, and 7g of a softening agent (Safanol P-200 manufactured by Sanyo Chemical Industries, Ltd.) and hexylene glycol (weight ratio is 1: 1) is placed inside. Then, it was heat sealed and sealed to produce a package. Ten minutes after packaging, the package was cut into 4 cm × 4 cm and evaluated for water solubility at 5 ° C.

[Method for evaluating storage stability of film]
Make a 4.5cm x 4.5cm bag from the film, and put 7g of a softening agent (Safanol P-200 manufactured by Sanyo Chemical Industries, Ltd.) and hexylene glycol (weight ratio is 1: 1) inside. The package was made by heat sealing and sealing. As an accelerated test for long-term storage, this packaging bag was placed in a constant temperature and humidity chamber at 30 ° C. and 80% RH, taken out after 2 weeks, and the water solubility of the packaged film was measured according to the method described above.

  The storage stability of the film is determined by the ratio of the dissolution time (A) after standing for 10 minutes at room temperature and the dissolution time (B) after the storage acceleration test (B / A) was obtained and evaluated by the magnitude of the value.

[Method for evaluating solubility of package (measurement of remaining amount)]
Make a 4.5cm x 4.5cm bag from the film, and put 7g of a softening agent (Safanol P-200 manufactured by Sanyo Chemical Industries, Ltd.) and hexylene glycol (weight ratio is 1: 1) inside. The package was made by heat sealing and sealing. Using a commercially available washing machine (Drum type dry washing machine manufactured by Sharp Corporation), driving the washing machine by putting the package in a drawer dedicated to fabric softener, collecting the residue in the drawer after washing, The weight after drying at 105 ° C. for 6 hours was measured and evaluated.

[Measurement method of Young's modulus and strength]
A film having a width of 10 mm was conditioned for one week under an atmosphere of 20 ° C. and 65% RH, and then a tensile test was performed by an autograph. The chuck interval was 50 mm, and the pulling speed was 500 mm / min.

  As can be seen from the results shown in Table 1, in Examples 1 to 4, good results were obtained in any of water solubility, storage stability, and physical properties. On the other hand, in Comparative Example 1, it was difficult to dissolve in water, and when the package was used in a washing machine, there was much undissolved residue in the drawer exclusively for the softener. In Comparative Example 2, it was recognized that the storage stabilizer when the fiber softener was packaged was low, and the strength and Young's modulus were low.

The water-soluble film of the present invention is suitably used as a package for various chemicals such as laundry detergents, agricultural chemicals, bleaching agents, toiletry products, and industrial chemicals.

Claims (3)

  A water-soluble film comprising a polymer obtained by graft-polymerizing vinyl pyrrolidone to polyvinyl alcohol.   It is characterized by containing 10% by weight or more of a polymer having a K value of 12 to 150 obtained by graft polymerization of vinyl pyrrolidone to polyvinyl alcohol having a polymerization degree of 100 to 4000 and a saponification degree of 70 to 100 mol%. The water-soluble film according to claim 1. The polymer obtained by graft polymerization of vinyl pyrrolidone to polyvinyl alcohol is obtained by blending vinyl pyrrolidone in a polyvinyl alcohol solution and polymerizing using hydrogen peroxide or an organic peroxide as an initiator. The water-soluble film according to claim 1 or 2.