JP2011116430A - Water-soluble multiple layer film for wrapping acidic or alkaline substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-soluble film that highly suppresses a reduction in water soluble property and drop durability, and that excels in chemical resistance, when the film is used for wrapping a substance of which pH of saturated aqueous solution at 20&deg;C is 4 or less or 9 or more, and also to provide a wrapped body where the substance is wrapped with the water-soluble film. <P>SOLUTION: There are provided the water-soluble multiple layer film having a layer containing polyvinyl alcohol polymer (X layer) and a layer containing at least one resin selected from polysaccharide and acrylic resin (Y layer), and used for wrapping the substance of which pH of saturated aqueous solution at 20&deg;C is 4 or less or 9 or more, and the wrapped body formed by wrapping the substance with the water-soluble multiple film, and keeping the Y layer of the water-soluble multiple layer film physically in contact with the substance. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a water-soluble multilayer film for packaging a substance that has a saturated aqueous solution having a pH of 4 or less or 9 or more when the saturated aqueous solution is made at 20 ° C., and the substance is a water-soluble multilayer film. The present invention relates to a packaged product.

  In recent years, various chemicals, etc. are sealed and packaged in unit quantities in water-soluble films (unit packaging), and when used, they are put into the water in their packaging form, and the contents are used by dissolving or dispersing the entire packaging film in water. Has been adopted. The advantages of this unit packaging are that it can be used without directly touching dangerous chemicals during use, and that a certain amount is packaged, so that no weighing is required during use. Conventionally, as such a water-soluble film for unit packaging, a single-layer film formed from an unmodified partially saponified polyvinyl alcohol and added with a plasticizer such as glycerin is used. However, when an acidic or alkaline substance is packaged using such a single layer film, the content (acidic or alkaline substance) reacts with partially saponified polyvinyl alcohol during the storage period, and the partially saponified polyvinyl alcohol is crosslinked. There has been a problem that the water-soluble film becomes insoluble due to the progress of the reaction and saponification reaction. A method using modified polyvinyl alcohol is known in order to suppress a decrease in water solubility of the water-soluble film due to such contents. Specifically, modified polyvinyl alcohol into which a structural unit having a carboxyl group is introduced is used. Method used (Patent Document 1), Method of improving the saponification degree of polyvinyl alcohol by reducing the reactivity and improving the water solubility lost by introducing a structural unit having a hydrophilic group such as sulfonic acid (patent Document 2), a method of introducing an N-vinylamide monomer, a carboxyl group, and the like (Patent Document 3) are known.

By the way, when storing or transporting a package body in which an acidic or alkaline substance is packaged, if the package body falls or hits another object and is easily broken, the practicality is remarkably impaired. Especially in winter, the film is hardened and easily broken. Therefore, the water-soluble film is required to suppress not only the decrease in water solubility but also the decrease in drop strength.
However, even when the above-described modified polyvinyl alcohol is used, when a saturated aqueous solution at 20 ° C. is used, the saturated aqueous solution has a pH of 4 or less or 9 or more when packaged as a content. Further, there is room for further improvement in order to highly suppress the decrease in water solubility and drop strength.
On the other hand, a single-layer film formed from a water-soluble cellulose resin or a water-soluble acrylic resin has insufficient film strength, and a package formed by packaging the contents with such a single-layer film is There were problems such as being easily broken when dropped.

Japanese Patent Laid-Open No. 4-170405 Japanese Patent Laid-Open No. 7-118407 JP 2003-171424 A

  In the present invention, when a saturated aqueous solution is packaged at 20 ° C., when a substance whose pH is 4 or lower or 9 or higher is packaged, the decrease in water solubility and drop strength is suppressed to a high degree. It aims at providing the water-soluble film which is excellent in property, and the package formed by packaging the said substance with the said water-soluble film.

  As a result of intensive studies to achieve the above object, the present inventor has obtained a layer (X layer) containing a polyvinyl alcohol polymer (hereinafter, “polyvinyl alcohol” may be abbreviated as “PVA”), The present invention has been found to achieve the above object by a water-soluble multilayer film having a layer (Y layer) containing at least one kind of resin selected from saccharides and acrylic resins. Was completed.

That is, the present invention
[1] A water-soluble multilayer film having a layer (X layer) containing a PVA polymer and a layer (Y layer) containing at least one resin selected from polysaccharides and acrylic resins, A water-soluble multilayer film for packaging a substance in which the pH of the saturated aqueous solution becomes 4 or lower or 9 or higher when the saturated aqueous solution is made in
[2] The water-soluble multilayer film of [1], wherein the resin is a cellulose resin,
[3] The water-soluble multilayer film according to [1] or [2], wherein the X layer contains 0.01 to 3% by mass of a crosslinking agent,
[4] The water-soluble multilayer film of [3], wherein the crosslinking agent is a boron compound,
[5] The water-soluble multilayer film according to any one of the above [1] to [4], comprising only two layers of one X layer and one Y layer,
[6] The water-soluble multilayer film according to any one of the above [1] to [5], wherein the substance is a detergent, a bleach, or an agrochemical.
[7] When a saturated aqueous solution is formed at 20 ° C., a substance whose pH of the saturated aqueous solution is 4 or less or 9 or more is packaged with the water-soluble multilayer film of any one of the above [1] to [6] A package in which the Y layer of the water-soluble multilayer film and the substance are in contact with each other,
[8] The package of the above [7], which is formed from the water-soluble multilayer film, and the bag is filled with the substance in the Y layer.
About.

  When the water-soluble multilayer film of the present invention is packaged with a substance whose pH of the saturated aqueous solution is 4 or less or 9 or more when the saturated aqueous solution is formed at 20 ° C., the water-soluble multilayer film is highly reduced in water solubility and drop strength. It has excellent chemical resistance.

Hereinafter, the present invention will be described in detail.
The water-soluble multilayer film of the present invention has a layer (X layer) containing a PVA polymer and a layer (Y layer) containing at least one resin selected from polysaccharides and acrylic resins.

  As the PVA polymer constituting the X layer, a polymer produced by polymerizing a vinyl ester monomer and saponifying the resulting polyvinyl ester polymer can be used. Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, and the like. Among these, vinyl acetate is preferable.

  The above-mentioned polyvinyl ester polymer may be obtained using only one or two or more vinyl ester monomers as monomers, but within the range not impairing the effects of the present invention, It may be a copolymer of one type or two or more types of vinyl ester monomers and other monomers copolymerizable therewith. Examples of such other monomers include ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene and isobutene; acrylic acid or a salt thereof; methyl acrylate, ethyl acrylate, and n-propyl acrylate. Acrylic acid esters such as i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; Salts thereof: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, methacryl Metas such as dodecyl acid and octadecyl methacrylate Rylates; acrylamide derivatives such as acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropyldimethylamine or salts thereof, N-methylolacrylamide or derivatives thereof; methacrylamide , N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropyldimethylamine or salts thereof, methacrylamide derivatives such as N-methylolmethacrylamide or derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl Vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether Vinyl ethers such as stearyl vinyl ether; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; Examples include acid or a salt or ester thereof; itaconic acid or a salt or ester thereof; a vinylsilyl compound such as vinyltrimethoxysilane; and isopropenyl acetate.

  In addition to the above, other suitable monomers (other monomers copolymerizable with vinyl ester monomers) include N-vinylamides, and in particular, monomers represented by the following formula (I), N- Vinyl-2-pyrrolidones and N-vinyl-2-caprolactam are preferred.

^{_{CH 2 = CH-N (R}} 1) -C (= O) -R 2 (I)
(In the formula, R ¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ² represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)

In the above formula (I), examples of the alkyl group having 1 to 3 carbon atoms represented by R ¹ include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Examples of the alkyl group having 1 to 5 carbon atoms represented by R ² include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n- A pentyl group, an isopentyl group, etc. can be mentioned.

  Specific examples of the monomer represented by the above formula (I) include N-vinylformamide, N-methyl-N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylacetamide and the like.

  Examples of the N-vinyl-2-pyrrolidones include N-vinyl-2-pyrrolidone, N-vinyl-3-propyl-2-pyrrolidone, N-vinyl-5,5-dimethyl-2-pyrrolidone, N -Vinyl-3,5-dimethyl-2-pyrrolidone etc. are mentioned.

  Furthermore, examples of suitable other monomers (other monomers copolymerizable with vinyl ester monomers) other than the N-vinylamides described above include sulfonic acid group-containing monomers. Any sulfonic acid group-containing monomer may be used as long as it has a sulfonic acid group or a salt thereof in the molecule and can be copolymerized with a vinyl ester monomer. Specific examples of the sulfonic acid group-containing monomer include, for example, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-1-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, or alkalis thereof. Metal salts; Olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, or alkali metal salts thereof. Among these, 2-acrylamido-2-methylpropanesulfonic acid or an alkali metal salt thereof is preferable from the viewpoint of reactivity when copolymerized with a vinyl ester monomer and stability during saponification. Examples of the alkali metal include sodium, potassium, lithium, and the like.

  The copolymerization ratio of these other monomers (other monomers copolymerizable with the vinyl ester monomer) is 15 mol% or less based on the number of moles of all structural units constituting the polyvinyl ester polymer. Preferably, it is 10 mol% or less. Although there is no restriction | limiting in particular about a lower limit, It is preferable that it is 0.01 mol% or more, and it is more preferable that it is 0.05 mol% or more.

The saponification degree of the PVA polymer constituting the X layer is preferably in the range of 75 to 99 mol%, and more preferably in the range of 80 to 97 mol%. By using the PVA polymer having the above saponification degree, the dissolution time of the resulting water-soluble multilayer film is further shortened, and the water used for dissolution does not need to be heated to a high temperature.
Here, the degree of saponification of the PVA polymer is the total number of moles of structural units (typically vinyl ester units) that can be converted to vinyl alcohol units by saponification and the vinyl alcohol units of the PVA polymer. On the other hand, it means the ratio (mol%) occupied by the number of moles of the vinyl alcohol unit, and can be measured according to the description of JIS K6726-1994.

The degree of polymerization of the PVA polymer constituting the X layer is preferably in the range of 300 to 2500, and more preferably in the range of 400 to 2400. When the polymerization degree of the PVA polymer is 300 or more, the strength of the obtained water-soluble multilayer film can be prevented from excessively decreasing, and the polymerization degree of the PVA polymer is 2500 or less. Thus, the dissolution time of the obtained water-soluble multilayer film is further shortened.
Here, the degree of polymerization (Po) of the PVA polymer means an average degree of polymerization measured according to the description of JIS K6726-1994. After re-saponifying and purifying the PVA polymer, The intrinsic viscosity [η] (unit: dl / g) measured in water can be obtained by the following equation.
Po = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

  Moreover, as a PVA type polymer which comprises X layer, you may use together 2 or more types of PVA type polymers from which a saponification degree, a polymerization degree, etc. mutually differ. In particular, when a PVA polymer having a saponification degree of 90 mol% or more and a polymerization degree of 1500 or more is added at a ratio of 5 to 30 mass% based on the total mass of the PVA polymer constituting the X layer, the resulting water-soluble solution is obtained. In some cases, the sealing strength, drop strength, water solubility, etc. of the porous multilayer film are improved.

In this invention, when X layer contains 0.01-3 mass% of crosslinking agents, the drop strength of the water-soluble multilayer film obtained can be improved, and it is preferable. As for the content rate of the crosslinking agent in X layer, it is more preferable that it exists in the range of 0.03-2.5 mass%. Here, the content (% by mass) of the crosslinking agent is a value calculated by [mass of crosslinking agent in X layer / mass of X layer] × 100.
The cross-linking agent is not particularly limited as long as it can cause a cross-linking reaction with the PVA polymer, but a boron compound is preferable.

  Here, examples of the boron compound include boric acid and borates (calcium salt, zinc salt, cobalt salt, ammonium salt, sodium salt, potassium salt, lithium salt, borax, etc.). Of these, boric acid Borax is preferred.

  Moreover, in this invention, when X layer contains 1-30 mass% of plasticizers, the sealing workability of the obtained water-soluble multilayer film, sealing strength, and drop strength can be improved, and it is preferable. The plasticizer content in the X layer is more preferably in the range of 2 to 25% by mass. Here, the content (mass%) of the plasticizer is a value calculated by [mass of plasticizer in the X layer / mass of the X layer] × 100.

  As the plasticizer, polyhydric alcohol is preferably used. Examples of the polyhydric alcohol include ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane and the like, and these use one kind or two or more kinds. be able to. Among these, ethylene glycol, glycerin, and diglycerin are preferably used.

  In order to improve the film forming property when producing the X layer, a surfactant can be blended in the raw material for producing the X layer. When the X layer is manufactured using a raw material in which a surfactant is blended, the X layer may contain a surfactant. The content of the surfactant in the X layer is preferably within a range of 0.01 to 7 parts by mass with respect to 100 parts by mass of the PVA polymer constituting the X layer, and is 0.02 to 5 parts by mass. More preferably within the range.

  Examples of the surfactant include an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant. Surfactant may be used individually by 1 type, or may use 2 or more types together.

  Examples of the anionic surfactant include carboxylic acid types such as potassium laurate; sulfate ester types such as octyl sulfate; sulfonic acid types such as dodecylbenzenesulfonate and sodium alkylbenzenesulfonate; polyoxyethylene lauryl ether phosphate mono Ethanolamine salt, octyl phosphate potassium salt, lauryl phosphate potassium salt, stearyl phosphate potassium salt, octyl ether phosphate potassium salt, dodecyl phosphate sodium salt, tetradecyl phosphate sodium salt, dioctyl phosphate Ester sodium salt, Trioctyl phosphate sodium salt, Polyoxyethylene aryl phenyl ether phosphate potassium salt, Polyoxyethylene aryl ester Such as alkenyl ether phosphate amine salts.

  Examples of nonionic surfactants include alkyl ether types such as polyoxyethylene oleyl ether and polyoxyethylene lauryl ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate. An alkylamine type such as polyoxyethylene lauryl amino ether; an alkylamide type such as polyoxyethylene lauric acid amide; a polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; an alkanolamide type such as oleic acid diethanolamide; Examples include allyl phenyl ether type such as oxyalkylene allyl phenyl ether.

  Examples of the cationic surfactant include amines such as laurylamine hydrochloride; quaternary ammonium salts such as lauryltrimethylammonium chloride; and pyridinium salts such as laurylpyridinium chloride.

  Examples of amphoteric surfactants include N-alkyl-N, N-dimethylammonium betaine.

The X layer may be composed of only the PVA polymer, or may be composed of at least one selected from the group consisting of the PVA polymer and the above-mentioned crosslinking agent, plasticizer and surfactant. However, if necessary, other components other than the above-mentioned PVA polymer, crosslinking agent, plasticizer and surfactant, such as an antioxidant, an antifreezing agent, a pH adjuster, a concealing agent, an anti-coloring agent, and an oil agent May further be contained.
The proportion of the total of the PVA polymer, the crosslinking agent, the plasticizer, and the surfactant in the X layer is preferably in the range of 50 to 100% by mass, and in the range of 80 to 100% by mass. It is more preferable that it is in the range of 95 to 100% by mass.

  As a method for producing the X layer, for example, a method using a PVA polymer solution in which a PVA polymer is dissolved in a solvent (a casting film forming method, a solution coating method, a wet film forming method (into a poor solvent) Discharge), gel film forming method (a method in which a PVA polymer aqueous solution is once cooled and gelated, and then a solvent is extracted and removed to obtain a PVA polymer film), and a combination thereof); including a plasticizer Examples thereof include a melt extrusion film forming method in which a PVA polymer (which may further contain moisture, an organic solvent, etc.) is melted. Among these, the casting film forming method and the melt extrusion film forming method are preferable.

  As the solvent used for producing the X layer, water is representative, but organic solvents such as methanol, ethanol, propanol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone should be used. You can also. When using these organic solvents, it is preferable to use together with water. In particular, when the X layer is produced by the solution coating method, it is possible to shorten the drying time by mixing methanol, ethanol or propanol with water, and it is also possible to reduce the quality of the coated film. preferable.

  The X layer containing the above-mentioned crosslinking agent, plasticizer, surfactant or other component can be easily produced by using the PVA polymer solution containing these components.

  The Y layer of the water-soluble multilayer film of the present invention contains at least one resin selected from polysaccharides and acrylic resins. Representative examples of the polysaccharides include starches and cellulose resins.

  Examples of starches include naturally occurring starch such as potato starch, corn starch, wheat starch, and rice starch, or starch obtained by heating and gelatinizing these starches; acetylated oxidized starch, octenyl succinate starch sodium, starch acetate, oxidized starch, Examples include hydroxypropyl starch, hydroxypropylated phosphoric acid crosslinked starch, phosphoric acid monoesterified phosphoric acid crosslinked starch, phosphorylated starch, nitrated starch and the like.

  Examples of the cellulose-based resin include carboxymethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and methylcellulose.

  Examples of the acrylic resin include polyacrylamide.

As at least one resin selected from polysaccharides and acrylic resins, polysaccharides, particularly cellulose resins, are more preferable for achieving the object of the present invention. Among cellulose resins, those having an average of 0.1 to 3 hydroxyl groups substituted with methoxy groups per glucose ring unit are preferred.
The viscosity of the aqueous solution containing 2% by mass of the polysaccharide is preferably in the range of 1 to 30,000 mPa · s, as measured with a Brookfield viscometer (20 rpm) at 20 ° C., and 5 to 10,000 mPa. More preferably within the range of s, and even more preferably within the range of 10 to 5,000 mPa · s.
The viscosity of the acrylic resin aqueous solution is preferably within a range of 20 to 150 mPa · s, more preferably within a range of 30 to 100 mPa · s, as a Gardner viscosity (25 ° C.).

The Y layer may be composed only of at least one resin selected from polysaccharides and acrylic resins, but if necessary, a plasticizer, a surfactant, a crosslinking agent, an antioxidant, an antifreezing agent Further, other components other than the above-described resins, such as a pH adjusting agent, a concealing agent, a coloring preventing agent, and an oil agent may be further contained.
The proportion of at least one resin selected from polysaccharides and acrylic resins in the Y layer is preferably in the range of 50 to 100% by mass, and preferably in the range of 80 to 100% by mass. More preferably, it is still more preferably in the range of 95 to 100% by mass.

  As a method for producing the Y layer, for example, a method using a resin solution in which at least one resin selected from polysaccharides and acrylic resins is dissolved in a solvent (casting film forming method, solution coating method, wet film forming) And a melt extrusion film forming method in which the above resin containing a plasticizer (which may further contain moisture, an organic solvent, etc.) is melted. A film-forming method, a solution coating method and a melt-extrusion film-forming method are suitable.

Regarding the water solubility of the water-soluble multilayer film of the present invention, the complete dissolution time of the water-soluble multilayer film measured by the following measurement method is preferably 500 seconds or less, more preferably 300 seconds or less, and 200 seconds. Or less, more preferably 100 seconds or less. Although there is no restriction | limiting in particular about the minimum of the complete dissolution time of a water-soluble multilayer film, It is preferable that the said complete dissolution time is 1 second or more, and it is more preferable that it is 2 seconds or more.
The water-soluble multilayer film of the present invention preferably exhibits the complete dissolution time before packaging a substance in which the pH of the saturated aqueous solution is 4 or lower or 9 or higher when the saturated aqueous solution is made 20 ° C. However, after the substance is packaged, the complete dissolution time is exhibited even after the substance is packaged and stored for a long time (for example, stored for 30 days under constant temperature and humidity of 20 ° C. and 65% RH). It is preferable.

  The complete dissolution time of the water-soluble multilayer film can be measured as follows. That is, 325 ml of ion-exchanged water is placed in a 500 ml glass beaker (trunk diameter 8.5 cm) and the water temperature is kept at 20 ° C. The sample water-soluble multilayer film is conditioned to 65% RH at a temperature of 20 ° C., then cut into a size of 3.5 cm × 4 cm, and the window frame is formed into a slide mount having a size of 2.3 cm × 3.4 cm. In a state where the film is sandwiched, in the center of the water in the glass beaker, a magnetic stirrer having a rotor of 5 cm in length is used to quickly immerse and observe with a stirring force of 280 rpm. Do. The film immersed in water dissolves on the slide mount over time, or after it breaks, it comes off the slide mount, dissolves gradually while floating in water, and becomes invisible to the naked eye, so immediately after immersing the film The time until disappearance with the naked eye is measured, and this is taken as the complete dissolution time. Depending on the type of additive added to the X layer and Y layer, etc., the additive may remain in the water without dissolving after dissolution of the film. From immediately after immersing the film, until the PVA polymer contained in the X layer and at least one resin selected from the polysaccharide and acrylic resin contained in the Y layer are at least dissolved and cannot be seen with the naked eye This time may be the complete dissolution time.

  In order to obtain a water-soluble multilayer film having water solubility as described above, any of at least one resin selected from a PVA polymer contained in the X layer and a polysaccharide and an acrylic resin contained in the Y layer It is preferable to use a water-soluble one. A water-soluble PVA polymer can be easily obtained by appropriately adjusting the degree of saponification, the degree of polymerization, the degree of modification with a comonomer, and the like. Moreover, the water solubility of a water-soluble multilayer film can be adjusted also by adjusting suitably the thickness of each layer which comprises a water-soluble multilayer film, or the whole thickness.

  The water-soluble multilayer film of the present invention has the X layer and the Y layer. The water-soluble multilayer film of the present invention may be composed of only one layer or two or more X layers and one layer or two or more Y layers, but is water-soluble other than the X layer and the Y layer. A layer having Z (Z layer) may be included. As a specific layer structure of the water-soluble multilayer film of the present invention, for example, a two-layer structure of X layer / Y layer; Y layer / X layer / Y layer, Z layer / X layer / Y layer, X layer / Z 3 layer configuration such as layer / Y layer; 4 layer configuration such as X layer / Y layer / X layer / Y layer, X layer / Z layer / X layer / Y layer, Z layer / X layer / Z layer / Y layer, etc. The layer structure in which the Y layer is located on at least one surface of the water-soluble multilayer film is preferable, and the two-layer structure of X layer / Y layer is more preferable.

  The thickness per layer of the X layer or the Y layer depends on the production method thereof, but when the X layer or the Y layer is a film (when it is not formed by a coating method), it is water soluble. From the viewpoint of properties, it is preferably in the range of 10 to 90 μm, more preferably in the range of 15 to 80 μm, and still more preferably in the range of 20 to 50 μm. When the X layer or the Y layer is a coating layer formed by a coating method, the thickness of each layer is preferably in the range of 0.5 to 20 μm, and preferably in the range of 1 to 10 μm. More preferably, it is further in the range of 2 to 5 μm. Moreover, it is preferable that the thickness of the whole water-soluble multilayer film of this invention exists in the range of 10-100 micrometers, and it is more preferable that it exists in the range of 20-45 micrometers.

When the water content of the water-soluble multilayer film of the present invention is in the range of 1 to 10% by mass, the sealing strength, drop strength, dimensional stability and the like can be improved. The moisture content is more preferably in the range of 1 to 8% by mass. When the moisture content is too low, the film itself is easily torn due to dropping or the like, and is easily broken at the seal portion. Further, the dimensional change tends to increase during storage after packaging. The moisture content can be adjusted by appropriately selecting the amount of water used as a solvent in producing the moisture content, drying conditions, and the like. Here, the moisture content can be determined by the following equation from the mass before and after drying when drying at 50 ° C. for 2 hours under a reduced pressure of 1 Pa or less.
Moisture content (mass%) = 100 × [mass of film before drying−mass of film after drying] / mass of film before drying

  There is no restriction | limiting in particular in the manufacturing method of the water-soluble multilayer film of this invention, For example, X layer and Y layer are prepared beforehand, these are laminated; From polysaccharide and acrylic resin with respect to X layer prepared beforehand A method of coating a coating liquid for forming a Y layer containing at least one selected resin; a coating liquid for forming an X layer containing a PVA polymer on a Y layer prepared in advance A method of coating; a method of co-extruding the X layer and the Y layer; and when the X layer is manufactured, before the X layer is completely dried or cooled, the Y layer is extruded or coated on the X layer and laminated. Examples include a sequential film forming method in which the X layer and the Y layer are dried or cooled simultaneously. In the method of preparing the X layer and the Y layer in advance and laminating them, it may be laminated using a water-soluble adhesive between the X layer and the Y layer, or between the X layer and the Y layer. An appropriate moisture may be applied to one or both of the adhesion surfaces to soften or partially dissolve only the surface, and then the X layer and the Y layer may be pressed and laminated. Among these, the method of coating the coating liquid for forming Y layer containing at least 1 sort (s) of resin chosen from polysaccharide and acrylic resin with respect to X layer prepared previously is preferable.

  As a specific method for coating the coating liquid for forming the Y layer on the X layer prepared in advance, for example, the resin is dissolved in a solvent so that the concentration becomes 1 to 30% by mass, and the Y liquid And a coating solution for forming a film is prepared, and this is coated by a usual coating method (for example, gravure roll coating, Meyer bar coating, reverse roll coating, air knife coating, spray coating, etc.). Here, examples of the solvent include water or a mixture of water and alcohol. The coating process and conditions are not particularly limited, but the method of coating the coating solution on a roll or belt during film formation of the X layer, and then drying or solidifying; once forming the X layer, in the subsequent process For example, a method of applying an appropriate coat and drying or solidifying may be used. At that time, it is important to adjust the temperature, amount, drying or solidification temperature, timing, etc. of the coating solution so that the physical properties of the X layer are not impaired. Drying conditions are preferably within a temperature range of 30 to 120 ° C. and a time range of 3 to 200 seconds. Examples of the drying method include hot air drying, hot roll drying, and far infrared drying.

  The multilayer film obtained as described above can be used as it is or as a multilayer film of the present invention by further laminating the above-described Z layer or the like as necessary. In addition, the multilayer film may be stretched in the transverse direction and / or the longitudinal direction as necessary. When a multilayer film is produced by coating the X layer prepared in advance with the coating liquid for forming the Y layer, the film may be stretched before the drying step or stretched after the drying step. Good. The temperature during stretching is preferably in the range of 20 to 120 ° C. The draw ratio is preferably in the range of 1.05 to 5 times, more preferably in the range of 1.1 to 3 times. If necessary, the residual stress can be reduced by heat fixing the multilayer film after stretching.

The water-soluble multilayer film of the present invention is used for packaging a substance that has a saturated aqueous solution having a pH of 4 or less or 9 or more when formed into a saturated aqueous solution at 20 ° C. When the saturated aqueous solution has a pH of 4 or lower when the saturated aqueous solution is obtained at 20 ° C., an inorganic strong acid (for example, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, chloric acid, bromic acid, iodic acid, permanganic acid) Etc.), and when the substance is solid, it can be packaged as it is or mixed with other substances and packaged when the substance is liquid, such as porous silica. The carrier can be held and packaged.
Examples of substances whose pH of the saturated aqueous solution becomes 9 or more when the saturated aqueous solution is obtained at 20 ° C. include hydroxides such as sodium hydroxide and potassium hydroxide, sodium cyanate, diamine silver, and tetraamine copper. Is done. Further, bleaching agents, detergents, agricultural chemicals, digestive agents and the like containing these can be mentioned. The water-soluble multilayer film of the present invention has a particularly remarkable effect in applications for packaging detergents, bleaches or agricultural chemicals, especially in applications for packaging detergents or agricultural chemicals.
In addition, in the case of a substance that dissolves even at the same amount as water at 20 ° C., the pH at 20 ° C. when mixed and dissolved in water at a ratio of 100 g of the substance / 100 g of water is measured, and the obtained value is It shall be regarded as “the pH of the saturated aqueous solution”.

  When the above-mentioned substance is packaged with the water-soluble multilayer film of the present invention, the effect of the present invention is remarkably exhibited, so that the Y layer of the water-soluble multilayer film of the present invention is in contact with the above-mentioned substance. It is preferable. As a specific packaging form of the above substance, for example, a bag formed of the water-soluble multilayer film of the present invention and filled with the substance in a bag in which the Y layer is disposed inside is preferable. Can be mentioned.

  The method for producing the bag is not particularly limited, but the bag can be produced by utilizing a general heat sealing method. That is, for example, after two water-soluble multilayer films having a Y layer located on at least one surface are aligned so that the Y layers face each other, a hot plate is pushed from the upper surface of the periphery (each side). The said bag can be manufactured by the method of heat-sealing by applying heat welding. It is preferable to arrange hard rubber, heat-resistant plastic, metal, or the like on the lower surface side when the hot plate is pressed. The heat seal temperature, pressure, time, and seal width at the time of heat sealing are not particularly limited as long as the object is achieved, but the seal width is within a range of 0.3 to 5 mm, and the temperature of the hot plate is 100 to 100 mm. Examples are a range of 180 ° C., a hot plate pressure of 0.5 to 2 kg / 20 cm, and a time of 1 to 10 seconds.

  A package formed by packaging a substance (contents) in which the saturated aqueous solution has a pH of 4 or lower or a pH of 9 or higher when the saturated aqueous solution is formed at 20 ° C. with the water-soluble multilayer film of the present invention is in this form. It can be stored and transported, and further can be used by putting it in water or the like in this form.

  In the water-soluble multilayer film of the present invention, when the above substances are packaged, the drop strength is highly suppressed. The drop strength of the water-soluble multilayer film after the above-mentioned substance is packaged and stored for a long time (for example, stored for 30 days under constant temperature and humidity of 20 ° C. and 65% RH) is as follows. The number of broken bags measured by the bag test is preferably 5/20 or less, and more preferably 3/20 or less.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The complete dissolution time, moisture content measurement, and drop bag breaking test were performed by the following methods.

325 ml of ion-exchanged water was placed in a glass beaker (body diameter 8.5 cm) having a complete dissolution time of 500 ml, and the water temperature was kept at 20 ° C. Next, the water-soluble multilayer film as a sample obtained in the following examples or comparative examples was conditioned to a humidity of 65% RH at a temperature of 20 ° C., then cut into a size of 3.5 cm × 4 cm, and a window frame of 2 280 rotations / second using a magnetic stirrer having a rotor of 5 cm in the center of water in the glass beaker with the film sandwiched between slide mounts having a size of 3 cm × 3.4 cm. The sample was quickly immersed and observed under a high intensity of stirring. The film soaked in water dissolves on the slide mount over time or breaks, then comes off the slide mount, dissolves gradually while floating in water, and becomes invisible to the naked eye. The time until disappearance with the naked eye was measured to determine the complete dissolution time. In addition, the said complete dissolution time was measured about three samples produced or processed on the same conditions, and the average value was calculated | required.

Measurement of moisture content Using a vacuum dryer (“DP33” manufactured by Yamato Scientific Co., Ltd.) and a vacuum pump (“VR16LP” manufactured by Hitachi Koki Co., Ltd.), drying at 50 ° C. for 2 hours under a reduced pressure of 1 Pa or less. It calculated | required by the following formula from the mass of the film before and behind drying when performed.
Moisture content (mass%) = 100 × [mass of film before drying−mass of film after drying] / mass of film before drying

Drop bag breaking test Sample packagings (A) and (B) for storage test obtained in the following examples or comparative examples were stored for 2 hours under conditions of 5 ° C. and 65% RH, and then they were 1 cm thick. Then, the bag surface was horizontally dropped from a height of 2 m on a 50 cm × 50 cm concrete plate, and the bag was checked for tearing. Of the 20 bags produced or treated under the same conditions, the number of bags torn (number of broken bags) was measured and used as an index of the drop strength of the water-soluble multilayer film.

[Example 1]
An aqueous solution containing 15 parts by mass of PVA having a degree of saponification of 88 mol% and a degree of polymerization of 1700 and 3.9 parts by mass of glycerin (PVA concentration is 15% by mass) (solution X) is cast on a conveyor belt, and 120 on the belt. A film (X layer) having a thickness of 30.2 μm, a width of 60 cm, and a length of 1050 m was obtained by drying for 5 minutes while applying hot air of ° C.
On the other hand, the degree of methoxy group substitution (average number of hydroxyl groups substituted with methoxy groups per glucose ring unit) is 1.9, and the degree of hydroxypropoxy group substitution (substituted with hydroxypropoxy groups per glucose ring unit) Hydroxypropyl methylcellulose (HPMC) having an average number of hydroxyl groups of 0.25 and a viscosity of 50 mPa · s when a 2% by mass aqueous solution at 20 ° C. is manufactured by Shin-Etsu Chemical Co., Ltd. Name) An aqueous solution containing 5% by mass of 60SH50) was prepared and used as a coating solution (Y solution).
The Y liquid is coated on the film (X layer) using a gravure roll with a width of 54 cm at a speed of 5 m / min, and immediately dried with hot air at 100 ° C. for 30 seconds to form a coat layer (Y layer). A multilayer film having a two-layer configuration of X layer / Y layer was obtained. The moisture content of the obtained multilayer film was 2.9% by mass. The average thickness of the coat layer (Y layer) was found to be 1.9 μm by cross-sectional observation with a microscope.

Both ends of this multilayer film were cut off by 5 cm each with a slitting device to a width of 50 cm and a length of 1000 m, and then wound on a cylindrical paper tube having an outer diameter of 88.2 mm and a winding surface of 15 kg / m. The film was continuously wound up under the conditions of a take-up speed of 40 m / min and a touch roll pressure of 3 kg / m ² to obtain a roll.

  A plurality of 10 cm × 10 cm multilayer films were cut out from this roll, and the heat was heated to 160 ° C. with respect to the portion from the end of the three sides to the inner side of 3 mm for two of each of the multilayer films. The plate was pressed at a pressure of 1 kg / 10 cm for 1 second to produce 66 heat-sealed bags, and 43 of the heat-sealed bags had sodium hydroxide powder (pH of saturated aqueous solution at 20 ° C. was 14). 10 g of each was added, and the remaining fourth side was heat sealed in the same manner as described above to prepare a sample package for storage test (A). In addition, 10 g of phosphoric acid powder (pH of aqueous solution is 2 when made into saturated aqueous solution at 20 ° C.) is put in each of the remaining 23 heat-sealed bags, in the same manner as in preparation of sample package for storage test (A). A sample package (B) for preservation test was produced.

  About 20 of the 43 sample packages for preservation test (A) obtained, a drop bag breakage test was conducted immediately after production by the method described above. In addition, the remaining 23 sample packagings for storage test (A) and 23 sample packagings for storage test (B) were stored for 30 days under constant temperature and humidity control at 20 ° C. and 65% RH. About 20 test sample packages (A) and 20 storage test sample packages (B), a drop bag breaking test was performed by the method described above. Further, a multilayer film was cut out from each of the remaining three storage test sample packages (A) and three storage test sample packages (B), and the complete dissolution time (average value; n = 3) was measured. In addition, the complete dissolution time (average value; n = 3) was measured by the method mentioned above also about the film before making it into a heat seal bag obtained from the roll-shaped thing. The results are shown in Table 1.

[Example 2]
Instead of the hydroxypropyl cellulose (HPMC) used in the preparation of the coating liquid (Y liquid) in Example 1, the methoxy group substitution degree is 1.8 and the viscosity when a 2 mass% aqueous solution at 20 ° C. is 100 mPa · s. A multilayer film was obtained in the same manner as in Example 1 except that methylcellulose (MC) (“Metroze” (trade name) SM-100 manufactured by Shin-Etsu Chemical Co., Ltd.) was used. The multilayer film had an X layer thickness of 30.2 μm, a Y layer thickness of 2.1 μm, and a multilayer film moisture content of 3.0 mass%. Using this multilayer film, a roll was obtained in the same manner as in Example 1.
Each evaluation was performed in the same manner as in Example 1 using this roll. The results are shown in Table 1.

[Example 3]
In Example 1, as an X solution, an aqueous solution prepared by further adding 0.2 parts by mass of boric acid to an aqueous solution containing 15 parts by mass of PVA having a saponification degree of 88 mol% and a polymerization degree of 1700 and 3.9 parts by mass of glycerin. A multilayer film was obtained in the same manner as in Example 1 except that it was used. The multilayer film had an X layer thickness of 32.6 μm, a Y layer thickness of 2.4 μm, and a moisture content of the multilayer film of 3.0% by mass. Using this multilayer film, a roll was obtained in the same manner as in Example 1.
Each evaluation was performed in the same manner as in Example 1 using this roll. The results are shown in Table 1.

[Example 4]
In Example 1, 5 mass% of hydroxypropylmethylcellulose (HPMC) (“Metrozu” (trade name) 60SH50 manufactured by Shin-Etsu Chemical Co., Ltd.) and silica having an average particle size of 6.6 μm (manufactured by Tosoh Corporation) were used as the Y liquid. A multilayer film was obtained in the same manner as in Example 1 except that an aqueous solution containing 0.4% by mass was used. In this multilayer film, the X layer had a thickness of 30.2 μm, the Y layer had a thickness of 2.8 μm, and the multilayer film had a moisture content of 3.1% by mass. Using this multilayer film, a roll was obtained in the same manner as in Example 1.
Each evaluation was performed in the same manner as in Example 1 using this roll. The results are shown in Table 1.

[Comparative Example 1]
A roll was obtained in the same manner as in Example 1 except that the film (X layer) obtained in Example 1 was used alone without being laminated with the Y layer. The moisture content of the X layer was 3.0% by mass.
Each evaluation was performed in the same manner as in Example 1 using this roll. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, the X liquid used in Example 3 was used as the X liquid, and a film (X layer) having a thickness of 32.6 μm obtained by finely adjusting the casting amount on the conveyor belt was defined as Y. A roll was obtained in the same manner as in Example 1 except that it was used alone without being laminated with a layer. The moisture content of the X layer was 3.2% by mass.
Each evaluation was performed in the same manner as in Example 1 using this roll. The results are shown in Table 1.

[Comparative Example 3]
In Example 1, a 28.9 μm-thick film (Y layer) obtained by using the Y liquid used in Example 1 instead of the X layer and finely adjusting the amount of casting onto the conveyor belt ) Was used in the same manner as in Example 1 except that it was used alone. The moisture content of the Y layer was 1.9% by mass.
Each evaluation was performed in the same manner as in Example 1 using this roll. The results are shown in Table 1.

[Comparative Example 4]
In Example 1, instead of PVA having a saponification degree of 88 mol% and a polymerization degree of 1700, a saponification degree of 96 mol%, a polymerization degree of 1700, and sodium 2-acrylamido-2-methylpropanesulfonate were used as all structural units (vinyl units). A 31.5 μm thick film (X layer) obtained in the same manner as in Example 1 except that a 3 mol% PVA-based polymer was used was used alone without being laminated with the Y layer. Except that, a roll was obtained in the same manner as in Example 1. The moisture content of the X layer was 4.1% by mass.
Each evaluation was performed in the same manner as in Example 1 using this roll. The results are shown in Table 1.

[Comparative Example 5]
In Example 1, instead of PVA having a saponification degree of 88 mol% and a polymerization degree of 1700, a saponification degree of 94 mol%, a polymerization degree of 1700, and 4 mol of N-vinyl-2-caprolactam based on the total structural unit (vinyl unit). Example 2 except that a 29.4 μm-thick film (X layer) obtained in the same manner as in Example 1 was used without being laminated with the Y layer, except that a PVA polymer containing 1% was used. In the same manner as in Example 1, a roll was obtained. The moisture content of the X layer was 3.8% by mass.
Each evaluation was performed in the same manner as in Example 1 using this roll. The results are shown in Table 1.

  When the water-soluble multilayer film of the present invention is packaged with a substance whose pH of the saturated aqueous solution is 4 or less or 9 or more when the saturated aqueous solution is formed at 20 ° C., the water-soluble multilayer film is highly reduced in water solubility and drop strength. It has excellent chemical resistance. For this reason, the water-soluble multilayer film of the present invention can be preferably used as a packaging film for packaging detergents, bleaches, agricultural chemicals and the like.

Claims (8)

  A water-soluble multilayer film having a layer containing a polyvinyl alcohol polymer (X layer) and a layer containing at least one resin selected from polysaccharides and acrylic resins (Y layer), saturated at 20 ° C A water-soluble multilayer film for packaging a substance having a pH of 4 or less or 9 or more when the aqueous solution is made into an aqueous solution.   The water-soluble multilayer film according to claim 1, wherein the resin is a cellulose resin.   The water-soluble multilayer film according to claim 1 or 2, wherein the X layer contains 0.01 to 3% by mass of a crosslinking agent.   The water-soluble multilayer film according to claim 3, wherein the crosslinking agent is a boron compound.   The water-soluble multilayer film according to any one of claims 1 to 4, comprising only two layers of one X layer and one Y layer.   The water-soluble multilayer film according to any one of claims 1 to 5, wherein the substance is a detergent, a bleaching agent, or an agricultural chemical.   A substance having a pH of 4 or lower or 9 or higher when the saturated aqueous solution is made into a saturated aqueous solution at 20 ° C is packaged with the water-soluble multilayer film according to any one of claims 1 to 6. A package comprising a Y layer of the water-soluble multilayer film and the substance in contact with each other.   The package according to claim 7, wherein the substance is filled in a bag formed of the water-soluble multilayer film and having a Y layer disposed inside.