JP6623531B2 - Polyvinyl alcohol composition - Google Patents

Description

  The present invention relates to a polyvinyl alcohol composition.

  Polyvinyl alcohol (PVA) is known as a fiber material, a polarizing plate material, and a barrier material. In these technical fields, there is a problem that transparency is lowered or whitened when PVA is stretched or molded.

  For example, in Patent Literature 1, it is necessary to use a PVA-based film with a high stretching ratio in order to obtain a polarizing film with a high degree of polarization for achieving a high contrast such as a liquid crystal monitor or a liquid crystal television. As the stretching ratio is increased, whitening (fine cracks and voids) of the film occurs. To address this problem, Patent Document 1 focuses on the influence of structural or physical differences in the thickness direction of the PVA-based polymer film, and controls the birefringence difference between the PVA-based film laminates to increase the draw ratio. To obtain a PVA-based film that does not whiten.

  On the other hand, Patent Literature 2 discloses, as a packaging laminated film for filling food, medicine, or electronic components, from the outside, an antistatic agent layer, a gas barrier laminated film layer, a polyolefin layer, and an antistatic agent-containing heat seal layer. Are disclosed. The polyvinyl alcohol (PVA) -based resin is a resin constituting the gas barrier laminated film layer. When heat-sealing the laminate, if the PVA-based resin is whitened and the transparency is impaired, poor appearance will occur. Thus, the invention described in Patent Document 2 attempts to solve problems such as transparency, antistatic properties, and gas barrier properties by devising a laminated structure and a material to be used.

JP 2005-324355 A JP 2008-143033 A

  Patent Literature 1 discloses that the configuration of a PVA-based film laminate (difference in birefringence between laminates) is controlled against the problem of whitening (fine cracks and voids) caused by highly stretching a PVA-based film. This suppresses stretch whitening of the PVA-based film. However, in this method, it is necessary to precisely control the materials and their thicknesses in order to precisely control the birefringence of each layer of the laminate. In addition, the PVA-based polymer film needs to have a three-layer structure, and can only be used in technically and cost-limited fields.

  Patent Literature 2 discloses a packaging laminated film using polyvinyl alcohol (PVA) as a gas barrier laminated film layer. However, there is a device for improving poor appearance (deterioration of transparency) during molding of a PVA-based resin itself. It is not seen and its usable applications are limited.

  An object of the present invention is to provide a polyvinyl alcohol-based composition having excellent moldability without causing whitening (fine cracks or voids) when a polyvinyl alcohol (PVA) film is stretched.

The present invention has solved the above-mentioned problem by setting the functional group content of the polyvinyl alcohol (A) and the crosslinked resin particles (B) contained in the polyvinyl alcohol-based composition to a specific range.
That is, the present invention relates to a polyvinyl alcohol-based composition containing a polyvinyl alcohol (A) and a crosslinked resin particle (B), wherein the polyvinyl alcohol-based composition satisfies all of the following conditions (1) to (4): Composition.
(1) The total amount of hydroxyl groups in polyvinyl alcohol (A) is 0.2 to 30 mmol / g.
(2) The crosslinked resin particles (B) have at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group or a salt thereof, and an amide group, and the total amount of the functional groups is 0.3. ５5 mmol / g.
(3) The crosslinked resin particles (B) are a monofunctional ethylenically unsaturated monomer having one ethylenically unsaturated group and a polyfunctional ethylene having two or more ethylenically unsaturated groups. and sexual unsaturated monomer, Ri Oh resin particles obtained by radical polymerization, an average particle diameter of 0.5 to 3.0 [mu] m, variation coefficient of Ru der 10% or less.
(4) The total amount of the functional groups derived from the polyvinyl alcohol (A) contained in the polyvinyl alcohol-based composition is equal to or greater than the total amount of the functional groups derived from the crosslinked resin particles (B).
The total amount of the functional groups derived from the polyvinyl alcohol (A) and the cross-linked resin per 1 g of the total of the polyvinyl alcohol (A) and the cross-linked resin particles (B) contained in the polyvinyl alcohol-based composition The difference from the total amount of the functional groups derived from the particles (B) is at most 25 mmol.

  ADVANTAGE OF THE INVENTION According to this invention, it became possible to provide the polyvinyl alcohol type composition excellent in moldability, without producing whitening (fine cracks and voids) when the polyvinyl alcohol (PVA) film is stretched.

  The polyvinyl alcohol composition of the present invention contains polyvinyl alcohol (A) and crosslinked resin particles (B).

Polyvinyl alcohol (A) is, for example,
As fully saponified polyvinyl alcohol, PVA-124 (manufactured by Kuraray, saponification degree 98.0 to 99.0 mol%, polymerization degree 2400), PVA-117 (manufactured by Kuraray, saponification degree 98.0 to 99.0 mol%, polymerization degree 1700) ), JC-25 (manufactured by Japan Vineyard Poval, saponification degree 99.0 mol% or more, polymerization degree 2500);
As an intermediate saponified polyvinyl alcohol, PVA-617 (manufactured by Kuraray, saponification degree 94.5 to 95.5 mol%, polymerization degree 1700), PVA-613 (manufactured by Kuraray, saponification degree 92.5 to 94.5 mol%, polymerization degree 1300) ), JM-23 (manufactured by Japan Vineyard Poval, saponification degree: 96.0 to 98.0 mol%, polymerization degree: 2300);
As partially saponified polyvinyl alcohol, PVA-205 (manufactured by Kuraray, saponification degree: 86.5 to 89.0 mol%, polymerization degree: 500), PVA-217 (manufactured by Kuraray, saponification degree: 87.0 to 89.0 mol%, polymerization degree: 1700) ), PVA-417 (manufactured by Kuraray, saponification degree 78.0 to 81.0 mol%, polymerization degree 1700), JP-18 (manufactured by Nippon Vine Poval, saponification degree 87.0 to 89.0 mol%, polymerization degree 1800) );
As low saponified polyvinyl alcohol, PVA-505 (manufactured by Kuraray, saponification degree 72.5 to 74.5 mol%, polymerization degree 500);
And the like.
The polyvinyl alcohol (A) is not particularly limited to these.

  As the polyvinyl alcohol (A) of the present invention, a compound in which the total amount of hydroxyl groups per 1 g of the resin is 0.2 to 30 mmol is used. Further, more preferably, it is 5 to 23 mmol / g, and further preferably 6 to 20 mmol / g. When the amount of the functional group of the polyvinyl alcohol (A) is 0.2 mmol / g or more, the compatibility with the crosslinked resin particles (B) described later is improved. When the amount of the functional group of the polyvinyl alcohol (A) is 30 mmol / g or less, the interaction (hydrogen bond, etc.) caused by the functional group in the polyvinyl alcohol (A) can be appropriately reduced, and the crosslinked resin particles ( B) can enter between the chains of the polyvinyl alcohol (A), so that the compatibility of both can be improved, and as a result, whitening, cracks and voids of the sheet can be suppressed.

Further, the composition of the present invention may use the following binders together for the purpose of adjusting the physical properties of the coating film.
For example, polyurethane resin, polyurea resin, polyurethane urea resin, polyester resin, unsaturated polyester resin, polyether resin, polycarbonate resin, epoxy resin, amino resin, styrene resin, acrylic resin, methacrylic resin, melamine resin, polycarboxylic acid or the like Salt, polyamide resin, phenol resin, vinyl resin, vinyl chloride, urethane resin containing vinyl chloride-vinyl acetate acidic group, petroleum resin, casein, shellac, rosin-modified maleic resin, rosin-modified phenol resin, polysaccharide, cellulose, nitrocellulose Cellulose analogues such as acetate butyrate, cyclized rubber, chlorinated rubber, oxidized rubber, hydrochloride rubber, alkyd resin, silicone resin, fluororesin, drying oil, synthetic drying oil, chlorinated polypropylene, butyral resin Vinylidene chloride resins.
These resins may be used alone or in combination of two or more.

The crosslinked resin particles (B) include a monofunctional ethylenically unsaturated monomer having one ethylenically unsaturated group and a polyfunctional ethylenically unsaturated monomer having two or more ethylenically unsaturated groups. Is a resin particle obtained by radical polymerization of a monomer and has at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group or a salt thereof, and an amide group.
Such crosslinked resin particles (B) may be a monofunctional ethylene having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group or a salt thereof, and an amide group, and one ethylenically unsaturated group. Obtained by radical copolymerization of an unsaturated monomer, a polyfunctional ethylenically unsaturated monomer having two or more ethylenically unsaturated groups, and optionally other monomers. Can be.

  The monofunctional ethylenically unsaturated monomer having a hydroxyl group, the monofunctional ethylenically unsaturated monomer having a carboxyl group or a salt thereof, and the monofunctional ethylenically unsaturated monomer having an amito group include the following. And an ethylenically unsaturated monomer such as

Examples of the monofunctional ethylenically unsaturated monomer having a hydroxyl group include hydroxyalkyl (meth) acrylate and its ε-caprolactone adduct, and an ethylenically unsaturated monomer having an aromatic or alicyclic hydrocarbon group. Can be
Specific examples thereof include hydroxyalkyl (meth) acrylates having an alkyl group having 1 to 4 carbon atoms, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; Ε-caprolactone adduct of hydroxyalkyl (meth) acrylate having 1 to 4 carbon atoms, such as 1 mol of ε-caprolactone of 2-hydroxyethyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate , 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate and the like, but the present invention is not limited only to such examples. These monofunctional ethylenically unsaturated monomers having a hydroxyl group may be used alone or in combination.

Monofunctional ethylenically unsaturated monomers having a carboxyl group or a salt thereof include (meth) acrylic acid, maleic anhydride, itaconic acid, itaconic anhydride, 2- (meth) acryloyloxyethyl-succinic acid, 2- (meth) acryloyloxyethyl-hexahydrophthalic acid, 2- (meth) acryloyloxyethyl-phthalic acid and the like can be mentioned.
Further, examples of the acidic group salt-containing ethylenically unsaturated monomer include sodium (meth) acrylate, potassium (meth) acrylate, sodium styrenesulfonate, and the like.

  Monofunctional ethylenically unsaturated monomers having an amide group include (meth) acrylamide, dimethyl (meth) acrylamide, isopropyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, methyl chloride quaternary salt, N-methylol (Meth) acrylamide and the like.

  Monofunctional ethylenically unsaturated monomers having these functional groups can be copolymerized with other ethylenically unsaturated monomers to obtain crosslinked resin particles (B).

Other monofunctional ethylenically unsaturated monomers, for example,
Alkyl (meth) acrylates such as methyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isononyl (meth) acrylate, and stearyl (meth) acrylate ;
Alicyclic hydrocarbon group-containing (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate;
Epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate, α-methylglycidyl (meth) acrylate, and 3,4-epoxycyclohexylmethyl (meth) acrylate;
Phosphate group-containing (meth) acrylates such as 2- (meth) acryloyloxyethyl acid phosphate; dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate quaternary compound, dimethylaminoethylbenzyl (meth) acrylate Amino group-containing (meth) acrylates such as quaternaries;
Aromatic ring-containing ethylenically unsaturated monomers such as styrene, α-methylstyrene, 1-butylstyrene, chlorostyrene, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate;
Ethylenically unsaturated monomers having an alkyl ether structure such as methoxyethyl (meth) acrylate and butoxyethyl (meth) acrylate;
Fluorine-containing ethylenically unsaturated monomers such as trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, and heptadecafluorodecyl (meth) acrylate;
Alkoxysilyl group-containing ethylenically unsaturated monomers such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane;
And the like.

As a polyfunctional ethylenically unsaturated monomer having two or more ethylenically unsaturated groups, for example,
Allyl (meth) acrylate, 1-methylallyl (meth) acrylate, 2-methylallyl (meth) acrylate, 1-butenyl (meth) acrylate, 2-butenyl (meth) acrylate, 3- (meth) acrylate Butenyl, 1,3-methyl-3-butenyl (meth) acrylate, 2-chloroallyl (meth) acrylate, 3-chloroallyl (meth) acrylate, o-allylphenyl (meth) acrylate, (meth) acrylic acid 2- (allyloxy) ethyl, allyl lactyl (meth) acrylate, citronellyl (meth) acrylate, geranyl (meth) acrylate, rosinyl (meth) acrylate, cinnamyl (meth) acrylate, diallyl maleate, diallyl itaconic acid, (Meth) vinyl acrylate, vinyl crotonate, vinyl oleate, vinyl linolenate, (meth) acrylic Acid 2- (2'-vinyloxyethoxy) unsaturated group-containing (meth) acrylic acid esters such as ethyl;
Ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, diacrylic acid Polyfunctional (meth) acrylates such as 1,1,1-trishydroxymethylethane, 1,1,1-trishydroxymethylethane triacrylate, and 1,1,1-trishydroxymethylpropane triacrylate;
Divinyls such as divinylbenzene and divinyl adipate;
And diallyls such as diallyl isophthalate, diallyl phthalate and diallyl maleate.

  These ethylenically unsaturated monomers are not limited to the exemplified compounds, and two or more kinds can be used in combination.

The amount of the ethylenically unsaturated monomer having the above functional group (hydroxyl group, carboxyl group or salt thereof, and amide group) used for copolymerization of the crosslinked resin particles (B) is based on the total amount of the monomers. Of these monomers, it is preferably used in an amount of 0.5 to 50% by weight, and more preferably 1 to 30% by weight of all monomers.
When the content of the ethylenically unsaturated monomer containing a hydroxyl group, a carboxyl group or a salt thereof, and an amide group is 0.5% by weight or more, compatibility with the polyvinyl alcohol (A) is improved. When the content of the ethylenically unsaturated monomer containing the functional group is 50% by weight or less, the stability during the synthesis of the resin particles (B) is improved.

  The polyfunctional ethylenically unsaturated monomer is preferably used in an amount of 0.5 to 30% by weight of all monomers. By setting the amount of the polyfunctional ethylenically unsaturated monomer within the above range, the resin particles (B) can be synthesized stably and the resin particles (B) can be sufficiently crosslinked, so that cracks and voids during stretching can be reduced. Generation can be effectively suppressed.

  In the present invention, when synthesizing the crosslinked resin particles (B), a radical polymerizable initiator is used. The radical polymerizable initiator is a compound that generates a radical by heat or a catalyst, thereby promoting cleavage of an unsaturated group in the ethylenically unsaturated monomer and causing a radical chain reaction. Examples of the radical polymerizable initiator include ionic / nonionic initiators, and these can be used alone or in combination in the present invention.

For example, as the ionic initiator, 2,2′-azobis [2- (phenylamidino) propane] dihydrochloride (VA-545, manufactured by Wako Pure Chemical Industries), 2,2′-azobis (2-amidinopropane) dihydrochloride A cationic initiator such as chloride (V-50, manufactured by Wako Pure Chemical Industries);
And anionic initiators such as potassium persulfate (KPS, manufactured by Wako Pure Chemical Industries) and ammonium persulfate (APS, manufactured by Wako Pure Chemical Industries).

As the nonionic initiator, 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70, manufactured by Wako Pure Chemical Industries), 2,2′-azobis (2,4- Nonionic azo polymerization initiators such as alkylazo compounds such as dimethylvaleronitrile) (V-65, manufactured by Wako Pure Chemical) 2,2'-azobisisobutyronitrile) (V-60, manufactured by Wako Pure Chemical),
Hydroperoxides such as methyl ethyl ketone peroxide (Permec H, manufactured by NOF Corporation) and cyclohexanone peroxy species (Perhexa H, manufactured by NOF Corporation) and the like.
The initiator is not particularly limited thereto, and initiators exemplified in the prior literature (Japanese Patent Application Laid-Open No. 2008-007688) studied by the present inventors can also be used.
Further, two or more types can be used in combination.

The initiator is preferably used in an amount of 0.10 to 10% by weight based on the total amount of the monomers.

  The present invention is also characterized in that, when synthesizing resin particles, polymerization is performed in water and / or an alcohol solvent. By adjusting the mixing ratio of water and alcohol, the polymerization stability and particle size of the particles can be controlled. The higher the proportion of water in the solvent, the easier it is to synthesize particles with a smaller particle size. Conversely, the higher the proportion of the solvent, the larger particles can be produced.

Specific examples of alcohol solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butanol and the like.
However, it is possible to synthesize by adding an organic solvent other than the alcohol-based solvent as needed. Examples of the organic solvent other than the alcohol solvent include ethers such as diethyl ether, isopropyl ether, butyl ether, methyl cellosolve, and tetrahydrofuran; and ketones such as acetone, methyl ethyl ketone, and diethyl ketone. These organic solvents can be used as a mixture of two or more kinds.

  The water and / or solvent used in the synthesis of the resin particles is preferably 70 to 90% by weight based on the total weight of the system, and the amount of water in the solvent is preferably 0 to 70% by weight.

The crosslinked resin particles (B) thus obtained have the above-mentioned functional group content of 0.05 to 10 mmol, preferably 0.3 to 5 mmol / g, more preferably 0.3 to 3 mmol / g per 1 g of the resin. g is more preferable.
When the amount of the functional group in the resin particles (B) is 0.05 mmol / g or more, the functional groups in the polyvinyl alcohol (A) interact with each other, and the phase between the polyvinyl alcohol (A) and the resin particles (B) is changed. The solubility is improved. From the viewpoint of the stability of the particles at the time of synthesis of the resin particles (B), it is important that the amount of the functional group in the resin particles (B) is 10 mmol / g or less.

The crosslinked resin particles (B) preferably have an average particle diameter of 0.1 to 8.0 μm and a coefficient of variation of 25% or less, and more preferably have an average particle diameter of 0.5 to 3.0 μm. More preferably, the coefficient of variation is 10% or less.
The crosslinked resin particles (B) are added to the polyvinyl alcohol (A). By adding the crosslinked resin particles (B), the sheet formed from the polyvinyl alcohol-based composition is suppressed from whitening (cracks and voids) during stretching, and as a result, can be improved in moldability. .

In addition, by adding the crosslinked resin particles (B), the surface of the polyvinyl alcohol-based sheet can be made matte to give a design property.
Further, when the average particle diameter of the resin particles (B) is larger than the thickness of the polyvinyl alcohol-based sheet, irregularities are generated on the sheet surface, and the objective contact area of the sheet surface is reduced. As a result, slipperiness and blocking resistance can be improved.

  By reducing the coefficient of variation (monodispersity of the particles) of the crosslinked resin particles (B) (sharpening the particle size distribution), the compatibility with the polyvinyl alcohol (A) is more uniformly controlled, and the slippage is improved. It is possible to more uniformly control the unevenness of the sheet surface which affects the properties and blocking resistance.

The average particle size referred to in the present invention is the number average of 100 particles measured by a scanning electron microscope (SEM), and the coefficient of variation is calculated by the following formula by statistically calculating the particle diameter of the 100 particles. It is a numerical value.
Coefficient of variation (%) = (standard deviation / average particle size) × 100

Further, the crosslinked resin particles (B) preferably contain substantially no dispersion stabilizer.
The dispersion stabilizer refers to a surfactant capable of forming micelles or a high molecular weight substance that functions as a dispersion stabilizer. For example, as the surfactant, an alkyl sulfonate such as sodium dodecyl sulfonate, an anionic surfactant such as an alkylbenzene sulfonate such as sodium dodecylbenzene sulfonate,
Cationic surfactants such as coconutamine acetate, alkylamine salts such as stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride;
Furthermore, amphoteric surfactants such as lauryl betaine and stearyl betaine, and further non-ionic surfactants such as polyethylene glycol alkyl ether such as polyethylene glycol nonylphenyl ether can be used. Further, those in which a functional group copolymerizable with an ethylenically unsaturated monomer is bonded to these surfactants can also be referred to as surfactants.

  Examples of the high molecular weight dispersion stabilizer include polyvinyl alcohol, polyacrylic acid, copolymers thereof and neutralized products thereof, and polymethacrylic acid, copolymers thereof and neutralized products thereof, polyvinylpyrrolidone, hydroxypropyl Cellulose (HPC) and the like can be mentioned.

  As a method for preparing particles, there are generally various methods such as an emulsion polymerization method, a dispersion polymerization method, a suspension polymerization method, a soap-free emulsion polymerization method, and in the present invention, a resin effective for controlling the properties of a coating film is used. In providing fine particles, it is preferable to synthesize resin particles by a synthesis technique that does not use these dispersion stabilizers. Specifically, the present invention is achieved by using a dispersion polymerization method capable of producing micron-sized monodispersed fine particles in the absence of a dispersion stabilizer, particularly using a method developed by the present inventors. Details are disclosed in JP-A-2001-278907. In this synthesis method, by performing polymerization using a specific ionic initiator, particles can be formed in the absence of a dispersion stabilizer. Further, by adding a nonionic initiator, particles having a relatively large particle size can be obtained.

  By such a synthesis method, monodispersed crosslinked resin particles (B) can be obtained. That is, an ethylenically unsaturated monomer having a functional group (at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group or a salt thereof, and an amide group) and other monofunctional / polyfunctional ethylenically unsaturated monomers After the monomer is uniformly dissolved in the solvent to remove dissolved oxygen, the reaction system is heated to 60 to 80 ° C. Thereafter, a solution obtained by dissolving a radical polymerizable initiator in a solvent is added, and the mixture is heated and stirred for 3 to 10 hours.

  However, when it is necessary to use a dispersion stabilizer due to adjustment of physical properties or the like, fine particles can be synthesized by adding a dispersion stabilizer. When a dispersion stabilizer is used, it is preferably used in an amount of 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the monomer.

The crosslinked resin particles (B) preferably have a glass transition temperature of 10 to 180 ° C, more preferably 20 to 160 ° C, and still more preferably 80 to 160 ° C.
When the glass transition temperature of the crosslinked resin particles (B) is 10 ° C. or higher, the shape of the resin particles (B) at room temperature is maintained, and the sheet surface has slipperiness, blocking resistance, and gloss (matte). Can be maintained and improved. The crosslinked resin particles (B) having a glass transition temperature of 180 ° C. or lower have an appropriate hardness, and can maintain the moldability (crack resistance) of the polyvinyl alcohol-based sheet even if a large amount is added to the composition. , It is difficult to lose the balance with other physical properties (gloss, design).

  In addition, the glass transition temperature referred to here is a glass transition temperature of a resin obtained by drying a dispersion of the crosslinked resin particles (B) to a solid content of 100% and measured by differential scanning calorimetry (DSC). It indicates that. For example, the glass transition temperature is predicted by setting an aluminum pan containing a sample weighing about 10 mg of a sample and an aluminum pan containing no sample in a DSC device, and using the liquid pan in a nitrogen stream with liquid nitrogen. After cooling to a glass transition temperature minus 50 ° C., the temperature is raised to a predicted glass transition temperature plus 50 ° C. at a heating rate of 10 ° C./min, and a DSC curve is plotted. The slope of the straight line extending from the baseline on the low temperature side of this DSC curve (the portion of the DSC curve in the temperature region where no transition and reaction does not occur in the test piece) to the high temperature side and the curve of the step change portion of the glass transition become maximum. From the intersection with the tangent drawn at such a point, the extrapolated glass transition onset temperature (Tig) can be determined, and this can be determined as the glass transition temperature. The glass transition temperature of the present invention describes a value measured by the above method.

In the present invention, the total amount of the hydroxyl groups of the polyvinyl alcohol (A) in the polyvinyl alcohol-based composition is the amount of the functional groups (hydroxyl group, carboxyl group or salt thereof, and amide group) of the crosslinked resin particles (B). It is important that the total amount is not less than the total amount, and the difference is at most 25 mmol / g, preferably 2 to 23 mmol / g, more preferably 3 to 20 mmol / g.
That is, the total amount of the functional groups in the polyvinyl alcohol (A) −the total amount of the functional groups in the resin particles (B) ≦ 25.0 mmol / g.

By setting the difference in the functional group content between the polyvinyl alcohol (A) and the crosslinked resin particles (B) within this range, whitening when a sheet obtained from the polyvinyl alcohol-based composition is stretched and molded is sufficiently suppressed. can do.
The whitening state before and after stretching and molding of the sheet was measured by the number of cracks and voids generated and the rate of change in HAZE.
The method of measuring the number of cracks and voids is as follows.
For a flat laminate obtained by applying and curing the resin composition of the present invention to a substrate at a predetermined film thickness, a square (4 cm × 4 cm) sample is arranged in parallel with the length direction from the center in the width direction of the film. The sample was collected, and the center of the sample was observed at a magnification of 100 times using a microscope (“BX51” manufactured by Olympus). At that time, the number of cracks (ruptures perpendicular to the stretching direction) and the number of voids (rod-like defects having a long axis in the stretching direction) were determined by fixing the microscope during observation and confirming the number within one field of the microscope. Counted. This operation was repeated twice, and the average value was obtained.
The measuring method of the change rate of the HAZE is as follows.
The turbidity of the above-mentioned square sample was measured using “Haze Meter NDH2000” manufactured by Nippon Denshoku Industries. The measurement was repeated three times, and the average value was taken.

The smaller the difference between the total amount of the hydroxyl groups in the polyvinyl alcohol (A) and the total amount of the functional groups in the crosslinked resin particles (B), the smaller the surface of the polyvinyl alcohol (A) and the crosslinked resin particles (B). The effect of the compatibility of the functional groups is sufficiently exhibited, and as a result, whitening (cracks and the like) during stretching of the polyvinyl alcohol-based sheet is suppressed, and the moldability is improved.
If the difference between the total number of hydroxyl groups in the polyvinyl alcohol (A) and the total number of functional groups in the crosslinked resin particles (B) exceeds 25 mmol / g, the polyvinyl alcohol (A) and the resin particles (B) The difference in the amount of the functional groups becomes too large, and the compatibility effect of the surface functional groups is not sufficiently exhibited. As a result, the effect of improving the whitening (cracks, etc.) and the moldability during stretching of the polyvinyl alcohol-based sheet is obtained. I can't.

The addition ratio of polyvinyl alcohol (A) / cross-linked resin particles (B) in the composition of the present invention is such that the difference in the number of functional groups between polyvinyl alcohol (A) and resin particles (B) falls within the above range. The composition is not particularly limited as long as it is possible, but the resin ratio in the composition is preferably from 1 to 80% by weight, more preferably from 5 to 50% by weight.
If the addition amount of the resin particles (B) is less than 1% by weight, the amount of the resin particles in the composition is too small, so that sufficient effects on moldability and mattability cannot be obtained. On the other hand, if the amount of the resin particles (B) exceeds 80% by weight, the amount of the resin particles with respect to the binder is too large, and the coatability is reduced.

The composition of the present invention may contain an organic solvent. Examples of the organic solvent include aromatic solvents such as toluene and xylene; alcohol solvents such as iso-propyl alcohol, n-butyl alcohol and propylene glycol monomethyl ether; and ester solvents such as ethyl acetate, butyl acetate and cellosolve acetate. Solvent: Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone are exemplified.
The organic solvent preferably has a boiling point of 50 ° C to 200 ° C. If the boiling point is lower than 50 ° C., the solvent tends to evaporate when the composition is applied to the substrate, and the solid content increases, making it difficult to apply the composition with a uniform film thickness. When the boiling point is higher than 200 ° C., it becomes difficult to dry the solvent. Note that two or more solvents may be used.

  A white or black pigment may be added to the composition of the present invention so that the formed layer is not transparent but white or black. In the case of white color, titanium oxide is generally used. When making black, carbon black is generally used. Titanium oxide and carbon black are dispersed using a part of the curable resin (I) having a crosslinkable functional group, for example, using a wet media disperser, and added to the remaining acrylic copolymer (A). Can be obtained. As the wet media disperser, scandics, ball mills, paint shakers, basket mills, dyno mills, ultravisco mills, annular dispersers, jet mills, homogenizers and the like can be used.

  As a medium used for dispersion, zirconia, alumina, glass beads, steel beads, or the like can be used, and a medium having a diameter of 0.1 to 5 mm can be used.

  Further, organic or inorganic fine particles can be added to the composition of the present invention as an auxiliary agent to such an extent that the effect of the above-mentioned crosslinked resin (B) is not impaired.

  Specific examples of the organic fine particles include polymer fine particles such as nylon (registered trademark) resin, melamine resin, guanamine resin, phenol resin, urea resin, and silicone resin, or cellulose powder, nitrocellulose powder, wood powder, waste paper powder, Rice husk flour, starch and the like. One type of organic particles may be used, or two or more types may be used in combination.

  Specific examples of the inorganic fine particles include oxides, hydroxides, sulfates, carbonates, and silicates of metals such as magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony, and titanium. System fine particles. More specific examples include silica gel, aluminum oxide, calcium hydroxide, calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate, zinc oxide, lead oxide, diatomaceous earth, zeolite, aluminosilicate, talc, white carbon, mica , Glass fiber, glass powder, glass beads, clay, wollastonite, iron oxide, antimony oxide, titanium oxide, lithopone, pumice powder, aluminum sulfate, zirconium silicate, barium carbonate, dolomite, molybdenum disulfide, iron sand, carbon black, etc. Contained inorganic particles. One type of inorganic particles may be used, or two or more types may be used in combination.

For the purpose of imparting weather resistance to the composition of the present invention, the composition may further contain an ultraviolet absorber, an ultraviolet stabilizer, and the like.
Examples of the UV absorber include organic UV absorbers such as benzotriazole UV absorber, benzophenone UV absorber, triazine UV absorber, indole UV absorber, and inorganic UV absorbers such as zinc oxide. And ultraviolet absorbers.
As the ultraviolet stabilizer, an ultraviolet stabilizer such as a hindered amine compound is suitably used. An ultraviolet absorber or an ultraviolet stabilizer may be added to the composition as an additive, or an ultraviolet absorber or an ultraviolet stabilizer having a functional group may be used by reacting with an acrylic copolymer. Alternatively, it may be used by reacting with another resin.
The ultraviolet absorber and the ultraviolet stabilizer are used in an amount of 0.1 to 30 parts by mass, preferably 1 to 20 parts by mass, based on 100 parts by mass of the solid content of the composition excluding the ultraviolet absorber and the ultraviolet stabilizer. preferable.

  In the composition of the present invention, if necessary, a filler, a thixotropy-imparting agent, an antioxidant, an antioxidant, an antistatic agent, a flame retardant, and a thermal conductivity improver as long as the effects of the present invention are not impaired. Various additives such as a plasticizer, an anti-dripping agent, an antifouling agent, an antiseptic, a bactericide, an antifoaming agent, a leveling agent, a thickener, a pigment dispersant, and a silane coupling agent may be further added. .

  Next, an example of a laminate (packaging material) including a layer formed from the polyvinyl alcohol-based composition of the present invention will be described. The configuration of the laminate including the polyvinyl alcohol-based composition of the present invention and the intended use are not limited thereto.

The polyvinyl alcohol composition of the present invention can be used, for example, as a packaging material for food, medicine, and cosmetics. Here, specifically, an example of a laminated body configuration for food packaging is shown.
As a laminate configuration for food packaging, for example, from the outermost layer side, a protective layer / outer layer side resin film layer / adhesive layer / heat seal layer are laminated in this order. In the food packaging material, the side that comes into contact with the food is called the inner layer side, and the opposite side is called the outer layer side. The above-described lamination structure is an example, and for example, another film layer may be further laminated on the outer layer side and the inner layer side via an adhesive layer. An aluminum foil or the like can be used instead of the outer resin film layer.

Examples of the outer resin film layer include a nylon-based thermoplastic resin film, a PET film, and a biaxially oriented polypropylene (OPP) film, and a nylon-based thermoplastic film is more preferable. A stretched nylon-based thermoplastic film is preferred.
Examples of the nylon-based thermoplastic resin film include films formed of nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like. Is mentioned.

Next, an example of a method for producing a food packaging material will be described. The method for producing the food packaging material of the present invention is not limited to this example.
One side of a 15 μm thick nylon film is subjected to corona treatment. Next, a composition containing polyvinyl alcohol (A) and crosslinked resin particles (B) is applied by a roll coating method so as to have a thickness of 5 μm (solid content) after drying, and dried in an oven at 100 ° C. To evaporate the solvent. The stretched nylon film coated with the composition and dried is placed in a constant temperature room at 50 ° C. and left for 4 days.

As a method for applying the polyvinyl alcohol-based composition of the present invention to the outer resin film layer, a conventionally known method can be used. Specific examples include comma coating, gravure coating, reverse coating, roll coating, lip coating, and spray coating.
The thickness of the protective layer is preferably from 0.5 to 30 μm, more preferably from 2 to 20 μm.

Next, an anchor coating agent is applied to the non-coated surface of the stretched nylon film on which the polyvinyl alcohol composition of the present invention is laminated, and the resin (melted polyethylene) constituting the heat seal layer is melted at 320 ° C. by an extrusion laminating machine. And laminated with LLDPE (linear low density polyethylene).
The obtained laminate is cut out to an appropriate size according to the intended use, and heat-sealed at 150 ° C., 2 kg / cm 2 for 1 second on the LLDPE / LLDPE side to make a bag.

As an adhesive used for bonding the outer resin film layer of the food packaging material and the heat seal layer, various materials such as a hot-melt type, a UV-curable type, etc. can be used in addition to a thermosetting type.
Examples of the thermosetting adhesive include an adhesive obtained by blending various polyol components and a curing agent component represented by an isocyanate component. For example, examples of the polyisocyanate-based anchor coating agent include trade name: EL-540 / CAT-RT32 manufactured by Toyo Morton Co., Ltd. Examples of the polyester-based adhesive include TOMOFLEX TM-K55 / CAT-10L (trade name, manufactured by Toyo Morton Co., Ltd.). Examples of the hot-melt adhesive include products manufactured by Dow Corning Toray Co., Ltd.
The adhesive used for bonding the outer resin film layer and the heat seal layer of the food packaging material of the present invention is not limited to the above example.

  The food packaging container contains food (solid, powder, liquid, etc.) inside. At the time of accommodation, the inside can be sealed by facing the heat seal layers, heat sealing the outer peripheral portion, and integrating the heat seal layers. The heat seal layer other than the sealed outer peripheral portion is in contact with the contents.

  The polyvinyl alcohol-based composition of the present invention can be suitably used as a food packaging material, for example, a snack packaging material or a retort pouch packaging material. In addition, it can be suitably used as a pharmaceutical packaging material, for example, an infusion pack, a chemical packaging material, and a cosmetic packaging material.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. In Examples, “parts” indicates “parts by mass” and “%” indicates “% by mass”.

Production Example 1 "Pre-crosslinked resin particle dispersion"
70 parts of methanol, 13.5 parts of water, 3 parts of α-methylstyrene, 10.4 parts of styrene, 0.8 parts of divinylbenzene in a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube. And 0.8 parts of methacrylic acid were charged, and the temperature was raised to 60 ° C. while stirring under a nitrogen atmosphere. When the temperature in the flask reached 60 ° C., 0.07 part of 2,2′-azobis (2-amidinopropane) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries) was dissolved in 0.5 part of ion-exchanged water. And a solution prepared by dissolving 0.15 parts of 2,2'-azobis (2,4-dimethylvaleronitrile) (V-65, manufactured by Wako Pure Chemical Industries, Ltd.) in 1 part of methanol are added simultaneously, and the mixture is heated with stirring for 6 hours. A resin particle dispersion having an average particle size of 1.4 μm and a coefficient of variation of 3.2% was obtained. Thereafter, the methanol in the dispersion was removed by a heating and pressurizing operation to obtain an aqueous dispersion having a solid content of 20%. The amount of hydroxyl groups contained in 5 g of the dispersion (including 1 g of solid content) is 0.62 mmol.

Production Examples 2 to 12, Comparative Production Examples 1 to 3
The reaction was carried out in accordance with the composition shown in Table 1 to obtain crosslinked resin particle dispersions (Production Examples 2 to 12, Comparative Production Example 2) and resin particle dispersions (Comparative Production Examples 1 and 3). Table 1 shows the average particle size, the coefficient of variation, and the glass transition temperature (Tg).
The solid content, average particle size, coefficient of variation, and glass transition temperature (Tg) were measured by the methods described below.

《Measurement of solid content》
The weight of an aluminum dish with a lid having a diameter of 55 mm and a depth of 15 mm was measured to four decimal places. About 1.5 g of the resin solution was collected in an aluminum dish, immediately closed, and the weight was measured quickly and accurately. With the lid removed, it was placed in a 150 ° C. oven and dried for 20 minutes. After cooling to room temperature, the weight of the aluminum dish and the lid was measured, and the solid content was calculated by the following equation.
Solid content (%) = (weight after drying−weight of aluminum dish) ÷ (weight before drying−weight of aluminum dish) × 100

<< Measurement of average particle size >>
The average particle diameter in the present invention was calculated by the number average of particles measured by a scanning electron microscope (SEM).
10 mg of sufficiently dried crosslinked resin particles were placed on one side of the conductive tape on the sample stage and fixed. Further, platinum / palladium vapor deposition was performed using a sputtering apparatus. The sample after the pretreatment was set in a JIB-4600F system manufactured by JEOL Ltd., and an image of the sample was observed at an arbitrary magnification according to the particle diameter.
The diameter of 100 particles in the obtained image was measured to the first decimal place, and the number average was defined as the average particle diameter of the present invention.

《Calculation of variation coefficient》
The coefficient of variation in the present invention is a numerical value obtained by statistically calculating the particle diameter of 100 particles measured by SEM and using the following equation.
Coefficient of variation (%) = (standard deviation / average particle diameter) × 100

<< Measurement of glass transition temperature (Tg) >>
The glass transition temperature in the present invention was measured using a differential scanning calorimetry (DSC) system.
20 mg of sufficiently dried crosslinked resin particles were packed in an aluminum pan and capped. This measurement sample was set in a DSC220CU system manufactured by SII, and measurement was performed under the following conditions.
Nitrogen flow rate 50ml / min
Measurement temperature range 30-230 ° C
Heating rate 10 ° C / min
Based on the obtained calorie change spectrum, the glass transition temperature was determined as the extrapolation start temperature of the endothermic reaction.

"Example 1"
80 g (solid weight) of completely saponified polyvinyl alcohol (having a saponification degree of 99 mol%) (hereinafter referred to as PVA) having a hydroxyl group content of 22.3 (mmol / g) was used for the crosslinked resin particles obtained in Production Example 1. In addition to 100 g of the dispersion (including 20 g of solid content), isopropyl alcohol (IPA) was further added so that the solid content became 13%, followed by stirring to obtain a composition. The amount of hydroxyl groups derived from PVA contained in a total of 100 g of PVA and crosslinked resin particles contained in the composition was 22.3 × 80 = 1784 mmol, and the amount of hydroxyl groups derived from crosslinked resin particles was 0.62 × 20 = 12.4 mmol. Therefore, the difference between the amount of hydroxyl groups derived from HPC and the amount of hydroxyl groups derived from cross-linked resin particles per 1 g of the total of the HPC and cross-linked resin particles contained in the protective paint is 17.7 mmol.
Using a bar coater, the obtained protective paint is applied to the corona-treated surface of a stretched nylon film having a thickness of 25 μm that has been subjected to corona treatment in advance, and dried in an oven at 100 ° C. for 1 minute to evaporate the solvents. Was. A bar coater was selected so that the film thickness after drying was 5 μm.

  Next, a polyisocyanate-based anchor coating agent “EL-540 / CAT-RT32” (trade name, manufactured by Toyo Morton Co., Ltd.) at a solid content of 10 wt% is applied to the non-coated surface of the stretched nylon film on which the composition of the present invention is laminated. Coating and extrusion line speed of 100 m / min by a laminating machine (Musashino Kikai). , Molten polyethylene (LDLC600A manufactured by Nippon Polychem Co., Ltd.) is melted at 320 ° C., laminated at 18 μm, and laminated with LLDPE (linear low-density polyethylene) (TUX-FCD # 40 manufactured by Tocelo) to form a primary laminate. did.

白 Whitening after film stretching (number of cracks, number of voids) ≫
With respect to the film obtained by stretching the obtained primary laminate 7 mm in the length direction, a square (4 cm × 4 cm) sample was sampled from the center in the width direction of the film in parallel with the length direction, and the sample was taken with a microscope (Olympus “ BX51 ") was used to observe the center of the sample at a magnification of 100x. At that time, the number of cracks (ruptures perpendicular to the stretching direction) and the number of voids (rod-like defects having a long axis in the stretching direction) were determined by fixing the microscope during observation and confirming the number within one field of the microscope. Counted. This operation was repeated twice, and the average value was obtained.

<< Whitening after film stretching (Haze change rate) >>
For the film before and after stretching the obtained primary laminate 7 mm in the length direction, square (4 cm × 4 cm) samples were taken from the center in the width direction of the film in parallel with the length direction. Turbidity (Haze) of this sample was measured using “Haze Meter NDH2000” manufactured by Nippon Denshoku Industries. The measurement was repeated three times, and the average value was taken.

"Examples 2 to 22", "Comparative Examples 1 to 6"
According to Table 2, a primary laminate was formed in the same manner as in Example 1.
The hydroxyl content of the partially saponified PVA (degree of saponification: 87 mol%) used in Examples 13 and 14 and Comparative Example 6 was 17.6 mmol / g.
Further, polypropylene (hereinafter referred to as PP) has a total amount of 0 mmol / g of functional groups selected from the group consisting of a hydroxyl group, a carboxyl group or a salt thereof, and an amide group.
In this specification, Production Examples 2, 3, 9, and 10 are Reference Production Examples, and Examples 2, 3, 9, and 10 using the Production Examples are Reference Examples.

As shown in Table 2, Comparative Examples 1, 3, and 6 using the crosslinked resin particles of Comparative Production Examples 1 and 3 having no specific functional group have insufficient compatibility with the polyvinyl alcohol (A). In addition, since the crosslinked resin particles are not uniformly dispersed in the protective layer, stretch whitening properties (the number of cracks, the number of voids, and the rate of change in HAZE) are poor.
In Comparative Examples 2, 3, and 6 using the resin particles of Comparative Production Examples 2 and 3, which were not crosslinked, the uniform dispersion state and compatibility with the polyvinyl alcohol (A) after stretching were lost, and the stretching whitening property ( The number of cracks, the number of voids, and the rate of change in HAZE are poor.

  As shown in Table 2, in Comparative Examples 4 and 5, in which the binder did not have a specific functional group, the binder was not compatible with the resin particles (B), and the whitening property was the number of cracks (the number of cracks, the number of voids, and the rate of change in HAZE). Is bad.

  A laminate obtained by applying and curing the composition of the present invention on a plastic film or a plastic molded product, an aluminum foil, an aluminum plate, a copper foil, a tin plate, a galvanized steel plate, a glass plate, a glass bottle, etc. is used for outdoor displays and marking films. It can be used for glass scattering prevention film, anti-reflection film, heat ray prevention film and the like.

Furthermore, since the composition of the present invention is excellent in moldability, it is suitable for film materials and packaging materials that require processing.
Therefore, the composition of the present invention includes, for example, various recording materials, IC cards, IC tags, etc., packaging materials for medicines and foods, marking films, photosensitive resin plates, adhesive sheets, dye-sensitized solar cells, Resin film for polarizing plate protection, resin film for antireflection, optical resin film such as light diffusion film, glass shatterproof resin film, decorative sheet, resin film for building materials such as resin film for windows, display material, illuminated signboard, etc. Can be used for indoor and outdoor overlay resin films and shrink films.

Claims (3)

A polyvinyl alcohol-based composition containing polyvinyl alcohol (A) and crosslinked resin particles (B),
A polyvinyl alcohol-based composition that satisfies all of the following conditions (1) to (4).
(1) The total amount of hydroxyl groups in polyvinyl alcohol (A) is 0.2 to 30 mmol / g.
(2) The crosslinked resin particles (B) have at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group or a salt thereof, and an amide group, and the total amount of the functional groups is 0.3. ５5 mmol / g.
(3) The crosslinked resin particles (B) are a monofunctional ethylenically unsaturated monomer having one ethylenically unsaturated group and a polyfunctional ethylene having two or more ethylenically unsaturated groups. and sexual unsaturated monomer, Ri Oh resin particles obtained by radical polymerization, an average particle diameter of 0.5 to 3.0 [mu] m, variation coefficient of Ru der 10% or less.
(4) The total amount of the functional groups derived from the polyvinyl alcohol (A) contained in the polyvinyl alcohol-based composition is equal to or greater than the total amount of the functional groups derived from the crosslinked resin particles (B).
The total amount of the functional groups derived from the polyvinyl alcohol (A) and the cross-linked resin per 1 g of the total of the polyvinyl alcohol (A) and the cross-linked resin particles (B) contained in the polyvinyl alcohol-based composition The difference from the total amount of the functional groups derived from the particles (B) is at most 25 mmol. The crosslinked resin particles (B) are resin particles obtained by radical polymerization of a monofunctional ethylenically unsaturated monomer and a polyfunctional ethylenically unsaturated monomer in the absence of a dispersant. The polyvinyl alcohol-based composition according to claim 1 , wherein: The glass transition temperature of the already cross-linked resin particles (B) is 80 to 160 ° C., polyvinyl alcohol composition according to claim 1 or 2.