JP2012041437A - Surface-treated polyvinyl alcohol-based polymer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film obtained by using a polyvinyl alcohol-based polymer, holding high flexibility and transparency, excellent in slidability so that blocking phenomenon hardly takes place, and excellent also in heat sealability; and to provide a method for producing the film.SOLUTION: The film comprises a polyvinyl alcohol-based polymer on the surface of which microparticles are arranged. The film surface has arithmetic average roughness (Ra) of 80-300 nm, and Young's modulus of the film is 150 MPa or less. The method for producing the film, having surface arithmetic roughness (Ra) of 80-300 nm, includes a step of coating the surface of a polyvinyl alcohol-based polymer film with a coating liquid containing microparticles by the gravure coating method.

Description

  The present invention relates to a film using a polyvinyl alcohol polymer. More specifically, the present invention relates to a film that maintains high flexibility and transparency, is excellent in slipperiness, hardly causes a blocking phenomenon, and has excellent heat sealability.

  Polyvinyl alcohol (hereinafter, “polyvinyl alcohol” may be abbreviated as “PVA”) polymer film is widely used as various packaging materials because of its excellent transparency and surface gloss and excellent toughness. Yes. However, since the PVA polymer film is poor in slipperiness, the films are in close contact with each other, so that a so-called blocking phenomenon is liable to occur. It was difficult to unwind the film, and the film adhered to the apparatus and the workability deteriorated. In some cases, the film was broken and the work was interrupted.

  As a general method for preventing blocking of a synthetic resin film, a method of forming an organic polymer coating layer by applying an organic solvent solution containing a hydrophobic organic polymer to the surface of the synthetic resin film is known. It has been. However, even if this method is applied to the PVA polymer film, the hydrophobic organic polymer has poor adhesive strength with the PVA polymer film, so that the heat sealability of the hydrophobic organic polymer itself is excellent. Even if it is a thing, when heat-sealing a process film, it is easy to peel in the interface of a coating layer and a PVA-type polymer film layer, and it was difficult to improve joining force as a result. In addition, when the coating layer of the organic polymer is formed by the above method, the treatment film is adhered with a well-known adhesive usually used for adhesion of PVA polymer films such as calcium bromide and magnesium nitrate. However, there are problems such as a significant decrease in adhesiveness and a limited use. Therefore, the above method for forming a coating layer of a hydrophobic organic polymer has not been practical as a method for preventing blocking of a PVA polymer film.

  Therefore, in order to improve such a defect, a method of preventing blocking of the PVA film by applying a hydrophobic synthetic resin emulsion under tension to the surface of the PVA film at a specific coating amount and drying (see Patent Document 1) ), A surface treatment liquid comprising a styrene resin emulsion and / or a methacrylic resin emulsion, a PVA resin aqueous solution, an aqueous solution or emulsion of a silicone water repellent, and an aqueous dispersion of fine particles having an average particle diameter of 5 to 1000 mμ. A method of preventing blocking by using it for the surface treatment of a polymer film (see Patent Document 2), a copolymer of methyl methacrylate, styrene and a vinyl monomer having a specific functional group, having an average particle size of 0.02 to 1 μm Improved blocking resistance by applying a specific amount of copolymer particles And the like (see Patent Document 3) have been proposed.

Japanese Patent Laid-Open No. 49-1000018 JP 57-92031 A Japanese Patent Laid-Open No. 3-121841

However, there is room for further improvement in order to obtain a film using a PVA polymer that maintains high flexibility and transparency, is excellent in slipperiness, hardly causes a blocking phenomenon, and has excellent heat sealability. was there.
Therefore, the present invention is a film using a PVA polymer, which maintains high flexibility and transparency, is excellent in slipperiness and hardly causes a blocking phenomenon, and has excellent heat sealability and the film. It aims at providing the manufacturing method of a film.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have obtained fine particles on the surface of the PVA polymer film by forming fine particles to form a surface-treated film. When the arithmetic average roughness (Ra) of the film surface of the film surface-treated by applying a coating liquid containing particles by applying a gravure coating method is in the range of 80 to 300 nm, the flexibility and transparency of the film The present inventors have found that the slipperiness and heat sealability can be improved without impairing the properties, and have further studied based on the findings to complete the present invention.

That is, the present invention
[1] A film in which fine particles are arranged on the surface of a PVA polymer film, the film surface having an arithmetic average roughness (Ra) of 80 to 300 nm and a Young's modulus of 150 MPa or less,
[2] The film according to [1], wherein the average particle size of the fine particles is 0.02 to 0.5 μm,
[3] The film according to [1] or [2], wherein the fine particles are formed from a copolymer of (meth) acrylic acid ester and aromatic vinyl.
[4] The film according to any one of the above [1] to [3], wherein the fine particles are fixed to the surface of the polyvinyl alcohol polymer film by a binder,
[5] The film according to [4], wherein the binder is a PVA polymer,
[6] The film according to any one of [1] to [5], wherein the haze value is 0 to 5%,
[7] A method for producing a film having an arithmetic average roughness (Ra) of the film surface of 80 to 300 nm, comprising a step of applying a coating liquid containing fine particles to the surface of the PVA polymer film by a gravure coating method,
[8] The production method of the above [7], wherein the average particle size of the fine particles is 0.02 to 0.5 μm,
[9] The method according to the above [7] or [8], wherein the fine particles are formed from a copolymer of (meth) acrylic acid ester and aromatic vinyl.
[10] The manufacturing method according to any one of the above [7] to [9], wherein the cell depth of the gravure printing plate is 5 to 18 μm,
[11] The production method according to any one of [7] to [10], wherein the coating liquid includes the fine particles and a binder.
[12] The production method of the above [11], wherein the binder is a PVA polymer.
About.

  According to the present invention, a film using a PVA polymer, which maintains high flexibility and transparency, is excellent in slipperiness, hardly causes a blocking phenomenon, and is excellent in heat sealability. can get.

The present invention is described in detail below.
The film of the present invention is formed by arranging fine particles on the surface of a PVA polymer film. And the arithmetic mean roughness (Ra) of the film surface of the said film exists in the range of 80-300 nm, and Young's modulus is 150 Mpa or less.

  The PVA polymer constituting the PVA polymer film used in the present invention includes vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl laurate, and vinyl stearate. Those obtained by saponifying a polyvinyl ester polymer obtained by polymerizing one or more vinyl esters such as vinyl benzoate can be used. Among the above-mentioned vinyl esters, vinyl acetate is preferable from the viewpoints of ease of production of PVA polymer, availability, cost and the like.

  The above-mentioned polyvinyl ester polymer is preferably obtained using only one or two or more kinds of vinyl esters as a monomer, and obtained using only one kind of vinyl ester as a monomer. Is more preferable, but may be a copolymer of one or more vinyl esters and other monomers copolymerizable therewith, as long as the effects of the present invention are not impaired. .

  Examples of other monomers copolymerizable with the vinyl ester include, for example, α-olefins having 2 to 30 carbon atoms such as ethylene, propylene, 1-butene and isobutene; (meth) acrylic acid or a salt thereof; (Meth) methyl acrylate, (meth) ethyl acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, ( (Meth) acrylic acid esters such as t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate; (meth) acrylamide, N-methyl ( (Meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acryl (Meth) acrylamide derivatives such as amide, (meth) acrylamide propanesulfonic acid or salts thereof, (meth) acrylamidepropyldimethylamine or salts thereof, N-methylol (meth) acrylamide or derivatives thereof; N-vinylformamide, N-vinyl N-vinylamides such as acetamide and N-vinylpyrrolidone; 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, stearyl vinyl ether, etc. Vinyl ether; vinyl cyanide such as (meth) acrylonitrile; halogenated vinyl such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride; vinegar Allyl compounds such as allyl acid and allyl chloride; maleic acid or its salts, esters or acid anhydrides; itaconic acid or its salts, esters or acid anhydrides; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate; unsaturated sulfone An acid etc. can be mentioned. Said polyvinyl ester-type polymer can have a structural unit derived from 1 type, or 2 or more types of an above described other monomer.

  The proportion of structural units derived from the other monomers in the polyvinyl ester polymer 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, more preferably 5 mol% or less.

  As the PVA polymer constituting the PVA polymer film, a polymer not graft-copolymerized can be preferably used, but the PVA polymer is 1 as long as the effects of the present invention are not impaired. It may be modified with a seed or two or more kinds of graft copolymerizable monomers. The graft copolymerization can be performed on at least one of the polyvinyl ester polymer and the PVA polymer obtained by saponifying it. Examples of the graft copolymerizable monomer include unsaturated carboxylic acids or derivatives thereof; unsaturated sulfonic acids or derivatives thereof; α-olefins having 2 to 30 carbon atoms, and the like. The proportion of structural units derived from the graft copolymerizable monomer in the polyvinyl ester polymer or PVA polymer is based on the number of moles of all structural units constituting the polyvinyl ester polymer or PVA polymer. It is preferable that it is 5 mol% or less.

  As the PVA polymer constituting the PVA polymer film, an uncrosslinked polymer can be preferably used. However, the PVA polymer is a part of the hydroxyl group as long as the effects of the present invention are not impaired. May be cross-linked.

  The degree of polymerization of the PVA polymer constituting the PVA polymer film is preferably in the range of 200 to 6000, and more preferably in the range of 500 to 4000. When the degree of polymerization is 200 or more, it becomes easy to stably produce a PVA polymer film, and sufficient film strength can be obtained. On the other hand, when the degree of polymerization exceeds 6000, there is a tendency that poor processability during the production of a PVA polymer film tends to occur. In addition, the polymerization degree of a PVA polymer as used in this specification means the average degree of polymerization measured according to description of JISK6726-1994.

  Moreover, it is preferable that the saponification degree of the PVA polymer which comprises a PVA polymer film exists in the range of 80-100 mol%. When the degree of saponification is 80 mol% or more, the strength of the PVA polymer film and thus the film of the present invention using the PVA polymer film can be improved. In this specification, the saponification degree of the PVA polymer is the total of the structural units (typically vinyl ester units) of the PVA polymer that can be converted to vinyl alcohol units by saponification and vinyl alcohol units. The proportion (mol%) of the number of moles of the vinyl alcohol unit relative to the number of moles. The degree of saponification can be measured according to the description of JIS K6726-1994.

  If desired, the PVA polymer film may contain a plasticizer. As the plasticizer, polyhydric alcohol is preferably used, and specific examples include glycerin, ethylene glycol, propylene glycol, diethylene glycol, diglycerin, triethylene glycol, tetraethylene glycol, trimethylolpropane and the like. it can. The PVA polymer film can contain one or more of these plasticizers. Among these, glycerin is preferable from the viewpoint of plasticizing effect, compatibility with PVA-based polymer, high boiling point, and the like.

  Although there is no restriction | limiting in particular in content of the plasticizer in a PVA-type polymer film, 50 mass parts or less are preferable with respect to 100 mass parts of PVA-type polymers, and 20 mass parts or less are more preferable. When the content of the plasticizer exceeds 50 parts by mass with respect to 100 parts by mass of the PVA polymer, the PVA polymer film tends to be too flexible and a problem is likely to occur in the film forming property.

  When the PVA polymer film is produced using a stock solution for producing a PVA polymer film, which will be described later, the film-forming property is improved and the occurrence of film thickness unevenness is suppressed, and the film is produced. When a metal roll or belt is used, the PVA polymer film can be easily peeled off from the metal roll or belt. Therefore, it is preferable to add a surfactant to the stock solution. When a PVA polymer film is produced from a stock solution containing a surfactant, the PVA polymer film may contain a surfactant. The surfactant compounded in the stock solution for producing the PVA polymer film, and the type of the surfactant contained in the PVA polymer film is not particularly limited, but it can be peeled off from a metal roll or belt. In view of the above, an anionic surfactant or a nonionic surfactant is preferable, and a nonionic surfactant is more preferable.

  As the anionic surfactant, for example, a carboxylic acid type such as potassium laurate; a sulfate ester type such as octyl sulfate; a sulfonic acid type such as dodecylbenzene sulfonate and the like are suitable.

Nonionic surfactants include, for example, alkyl ether types such as polyoxyethylene oleyl ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate; polyoxyethylene laurylamino Alkylamine type such as ether; alkylamide type such as polyoxyethylene lauric acid amide; polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; alkanolamide type such as oleic acid diethanolamide; polyoxyalkylene allyl phenyl ether The allyl phenyl ether type is preferred.
These surfactants may be used alone or in combination of two or more.

  When a surfactant is blended in a stock solution for producing a PVA polymer film, the content of the surfactant in the stock solution, and thus the content of the surfactant in the PVA polymer film, is determined as the stock solution or PVA. It is preferably within the range of 0.01 to 0.5 parts by mass, and within the range of 0.02 to 0.3 parts by mass with respect to 100 parts by mass of the PVA polymer contained in the polymer polymer film. It is more preferable that it is in the range of 0.05 to 0.1 parts by mass. When the content of the surfactant is 0.01 parts by mass or more with respect to 100 parts by mass of the PVA polymer, the film forming property and the peelability can be improved. On the other hand, when the surfactant content is 0.5 parts by mass or less with respect to 100 parts by mass of the PVA polymer, the surfactant bleeds out on the surface of the PVA polymer film and blocking occurs. It can suppress that handleability falls.

The PVA polymer film may be composed of only the PVA polymer or may be composed of only the PVA polymer and the above-described plasticizer and / or surfactant. Other components other than the above-mentioned PVA polymer, plasticizer and surfactant, such as an agent, an antifreezing agent, a pH adjusting agent, a concealing agent, a coloring preventing agent, and an oil agent may be contained.
The proportion of the total of the PVA polymer, plasticizer and surfactant in the PVA polymer film is preferably in the range of 50 to 100% by mass, and in the range of 80 to 100% by mass. Is more preferable.

  Although the thickness in particular of a PVA-type polymer film is not restrict | limited, The thing within the range of 5-100 micrometers is used suitably. The thickness of the PVA polymer film can be obtained as an average value by measuring the thickness at any five locations.

  The shape of the PVA polymer film is not particularly limited, and a single layer film having a quadrangular shape (for example, a rectangle, a square, etc.), a circle, a triangle, or the like is laminated, and a part thereof is bonded. Can be appropriately set according to the use of the film of the present invention, the process passability when arranging the fine particles, etc. It is preferable to have a shape in which a long PVA-based polymer film is wound in a roll shape. The width of the long PVA polymer film is preferably in the range of 10 to 200 cm, and more preferably in the range of 50 to 150 cm. The length of the long PVA polymer film is preferably in the range of 5 to 5000 m.

  The production method of the PVA polymer film used in the present invention is not particularly limited. For example, the above-described PVA polymer constituting the PVA polymer film, and, if necessary, a plasticizer and a surfactant. Etc. can be produced using a stock solution in which components such as PVA polymer, a PVA polymer, a solvent and, if necessary, a component such as a plasticizer and a surfactant are contained, and a PVA polymer is melted. .

  Examples of the solvent used for preparing the stock solution include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylol. Propane, ethylenediamine, diethylenetriamine and the like can be mentioned, and one or more of these can be used. Among these, water is preferable from the viewpoint of environmental load and recoverability.

  The volatile fraction of the stock solution used for film formation (the content ratio of volatile components such as a solvent removed by volatilization or evaporation during film formation in the stock solution) varies depending on the film formation method, film formation conditions, etc. It is preferably within the range of -95% by mass, and more preferably within the range of 55-90% by mass. When the volatile content of the stock solution is 50% by mass or more, the viscosity of the film-forming stock solution does not become too high, and filtration and defoaming are smoothly performed during preparation of the stock solution, and there are few foreign matters and defects. Is easy to manufacture. On the other hand, when the volatile fraction of the stock solution is 95% by mass or less, the concentration of the film-forming stock solution does not become too low, and the production of an industrial PVA polymer film becomes easy.

  Examples of the film forming method for forming a PVA polymer film using the above-described stock solution include a wet film forming method, a gel film forming method, a casting film forming method, and an extrusion film forming method. These film forming methods may be employed alone or in combination of two or more. Among these film forming methods, the casting film forming method or the extrusion film forming method is preferable because a PVA polymer film having a uniform film thickness and width and good physical properties can be obtained. The PVA polymer film can be subjected to a drying treatment or a heat treatment as necessary.

As a specific method for forming a PVA polymer film, for example, using a T-type slit die, hopper plate, I-die, lip coater die, etc., the stock solution for film formation is positioned on the most upstream side. It discharges or casts uniformly on the peripheral surface of the rotating heated first roll (or belt), and volatilizes from one surface of the film discharged or cast on the peripheral surface of the first roll (or belt). The component is evaporated and dried, and then the other surface of the discharged or cast film is passed over the peripheral surface of the heated second roll (or drying roll) to be dried, and on the downstream side thereof Industrially preferred is a method of further drying on the circumferential surface of one or a plurality of rotating heated rolls arranged, or passing through a hot air drying device and further drying, and then winding it on a winding device. Adopt Can. Drying with a heated roll and drying with a hot air dryer may be performed in an appropriate combination.
In order to adjust the PVA polymer film to an appropriate state, it is preferable that a heat treatment device; a humidity control device; a motor for driving each roll; a speed adjustment mechanism such as a transmission or the like is attached.
The drying temperature in the drying process in the production process of the PVA polymer film is preferably in the range of 50 to 150 ° C, more preferably in the range of 60 to 140 ° C.

  Examples of the fine particles used in the present invention include silicon oxide (colloidal silica, etc.), calcium carbonate, magnesium carbonate, calcium sulfate, magnesium sulfate, calcium stearate, magnesium stearate, titanium dioxide, talc, kaolin, clay, bentonite. Particles formed from inorganic substances such as polyethylene wax, polytetrafluoroethylene, melamine-guanamine copolymer, polyvinyl acetate, ethylene / vinyl acetate copolymer, vinyl chloride / vinyl acetate copolymer, poly (meth) From organic substances such as acrylic acid, copolymers of (meth) acrylic acid and aromatic vinyl (acrylic acid / styrene copolymer, etc.), copolymers of (meth) acrylic ester and aromatic vinyl, silicone resin, etc. Examples thereof include particles to be formed.

  Examples of the (meth) acrylic acid ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic acid. Examples include esters of (meth) acrylic acid and alcohols having 1 to 8 carbon atoms such as 2-ethylhexyl. Among these, methyl (meth) acrylate is preferable.

  Examples of the aromatic vinyl include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, 1-vinylnaphthalene, and 2-vinylnaphthalene. Among these, styrene is preferable.

  The fine particles may be used alone or in combination of two or more. Among the above-mentioned fine particles, since a film excellent in transparency can be obtained, particles formed from an organic substance are preferable, and a film excellent in blocking resistance can be obtained. Particles formed from a copolymer of (meth) acrylic acid ester and aromatic vinyl are more preferable, and particles formed from a methyl methacrylate / styrene copolymer are more preferable.

The average particle diameter of the fine particles is not particularly limited as long as the arithmetic average roughness (Ra) of the film surface of the obtained film is within the range specified in the present invention, but is within the range of 0.02 to 0.5 μm. It is preferable that it is in the range of 0.05 to 0.2 μm. When the average particle size is 0.02 μm or more, the slipperiness of the obtained film can be further improved, and the blocking phenomenon can be effectively suppressed. On the other hand, the transparency of the film obtained by an average particle diameter being 0.5 micrometer or less can be improved more.
The average particle size of the fine particles is determined by observing the film surface of the film of the present invention formed thereon with an electron microscope and measuring the particle size of any ten fine particles on the observed image (maximum in the observed image). It can be obtained by measuring the length) and averaging it.

  The film of the present invention is formed by arranging fine particles on the surface of a PVA polymer film. Here, even if all of the microparticles are in direct contact with the surface of the PVA polymer film, some or all of the microparticles are not in direct contact with the surface of the PVA polymer film and pass through a binder described later. It may be arranged. The fine particles can be arranged on the surface of the PVA polymer film by using the fine particles alone and spraying the fine particles on the surface of the PVA polymer film. However, the fine particles are more uniformly arranged. Therefore, it is preferable to apply the coating liquid containing fine particles on the surface of the PVA polymer film and further dry it as necessary. Examples of the liquid medium used in the coating liquid include water, methanol, and isopropanol, although depending on the type of fine particles.

  When the fine particles are arranged using the coating liquid, the emulsion in which the fine particles are dispersed is used as it is as the coating liquid, or the liquid medium and / or other components are optionally added to the emulsion. It is preferable to use a coating solution added with a binder (described later). By using an emulsion in which fine particles are dispersed, the particle size stability and economics of the fine particles can be improved.

Moreover, when arranging microparticles | fine-particles using a coating liquid, it is preferable that a coating liquid contains a binder further. By using a coating solution containing fine particles and a binder, a film in which the fine particles are fixed to the surface of the PVA polymer film by the binder can be obtained, and the dropping of the fine particles due to friction or the like can be effectively suppressed. Can do.
Although there is no restriction | limiting in particular in the raw material of the said binder, Since the adhesive force with a PVA-type polymer film is strong and it can suppress more effectively that an application layer falls, a PVA-type polymer is preferable. There is no restriction | limiting in particular in the kind of PVA-type polymer used as a binder, What was mentioned above as a PVA-type polymer which comprises a PVA-type polymer film can be used. In this case, the PVA polymer used as the binder may be the same type as the PVA polymer constituting the PVA polymer film or may be a different type.

  The degree of polymerization of the PVA polymer used as the binder is preferably in the range of 50 to 4000, more preferably in the range of 100 to 3500, and still more preferably in the range of 200 to 3000. . When the degree of polymerization is 50 or more, the film of the present invention can be produced more stably. Moreover, when the said polymerization degree is 4000 or less, it can suppress that the viscosity of a coating liquid becomes high too much, and can reduce the thickness spot at the time of application | coating.

  The saponification degree of the PVA polymer used as the binder is preferably in the range of 75 to 100 mol%, more preferably in the range of 80 to 100 mol%. When the saponification degree is 75 mol% or more, the adhesive force with the PVA polymer film can be further improved.

  The binder is preferably dissolved in the coating liquid, and the binder can be easily dissolved by appropriately changing the type of the liquid medium contained in the coating liquid. In particular, when a PVA polymer is used as the binder, when water is used as the liquid medium, the PVA polymer can be dissolved efficiently and can be easily recovered, which is an environmental load. Can be reduced, which is preferable.

  When the coating liquid contains a binder, the content ratio of the fine particles and the binder in the coating liquid is not particularly limited, but [mass of microparticles] / [mass of binder] is in the range of 20/1 to 1/20. It is preferable that it is in the range of 1/5 to 2/1.

  When the fine particles are arranged using the coating liquid, there is no particular limitation on the solid content concentration of the coating liquid used, and it can be set as appropriate according to the desired coating amount, etc. Considering workability at the time of application, it is preferably in the range of 0.05 to 5% by mass, and more preferably in the range of 0.1 to 3% by mass. In addition, solid content concentration of a coating liquid can be calculated | required by remove | dividing the mass at the time of drying a coating liquid by the mass before drying a coating liquid.

  Examples of the method for applying the coating liquid to the surface of the PVA polymer film include a roll coater method, an air doctor method, a blade coater method, a spray method, a dip method, and the like. It is preferable to employ a coater method, particularly a gravure coating method. By adopting the gravure coating method, a film excellent in flexibility can be easily produced.

The specific operation method of the gravure coating method is not particularly limited, and a known gravure coating method can be employed. For example, a gravure roll in which a plurality of concave cells for holding the coating liquid are formed on the peripheral surface (gravure plate surface) is arranged so that the lower part of the peripheral surface is immersed in the coating liquid in the container, and gravure A method of applying a coating solution to the surface of the PVA polymer film can be adopted by bringing the PVA polymer film into contact with the upper surface of the roll. Further, the coating liquid may be supplied to the peripheral surface of the gravure roll via the finisher roll without disposing the lower part of the peripheral surface of the gravure roll soaked in the coating liquid in the container. In the part where the gravure roll comes into contact with the PVA polymer film, it is preferable to dispose the impression cylinder on the opposite side of the gravure roll with respect to the PVA polymer film.
The type of gravure roll to be used is not particularly limited as long as the film of the present invention is obtained, but the size and shape can be easily obtained because a film with little variation in arithmetic average roughness (Ra) at each position of the film is easily obtained. However, it is preferable to use a gravure roll in which the same cells are uniformly arranged on the peripheral surface.

  The cell depth of the gravure plate surface of the gravure roll to be used is preferably in the range of 5 to 18 μm, and more preferably in the range of 8 to 15 μm. When the depth of the cell of the gravure plate surface is 5 μm or more, the arithmetic average roughness (Ra) of the film surface of the film of the present invention can be easily made 80 nm or more. On the other hand, when the cell depth of the gravure printing plate is 18 μm or less, the amount of coating liquid applied to the surface of the PVA polymer film becomes too large, and the arithmetic average roughness (Ra) of the film surface becomes too high. Can be suppressed, and the transparency and heat sealability of the resulting film can be further improved.

  It is preferable to further dry as necessary after applying the coating solution. As temperature at the time of drying, it can be in the range of 70-110 degreeC, for example. Moreover, 1 to 30 seconds can be adopted as the drying time. In addition, drying may be performed under normal pressure or under reduced pressure.

  The fine particles may be arranged on only one side of the PVA polymer film or on both sides, but the slipperiness can be sufficiently improved regardless of the direction of the laminated film. Therefore, it is preferable to dispose on both surfaces because a film having better blocking resistance can be obtained.

In the film of the present invention, the amount of the fine particles arranged on the surface of the PVA polymer film improves the transparency and provides a film having excellent slipperiness and consequently blocking resistance. per side of the united film is preferably in a range of 0.005~0.2g / ^{m 2,} and more preferably in a range of 0.01 to 0.1 g / ^{m 2.}

Since the arithmetic average roughness (Ra) of the film surface of the film of the present invention can improve slipperiness and heat sealability without impairing the flexibility and transparency of the film, it is within the range of 80 to 300 nm. Yes, preferably in the range of 90 to 250 nm, more preferably in the range of 100 to 200 nm. When the arithmetic average roughness (Ra) of the film surface is less than 80 nm, the slipperiness of the film is lowered and the blocking resistance is deteriorated. On the other hand, if the arithmetic average roughness of the film surface exceeds 300 nm, the transparency of the film decreases. In the film of the present invention, the arithmetic average roughness (Ra) on one side on which the fine particles are arranged may be at least within the above range, the fine particles are arranged on both sides of the PVA polymer film, and It is preferable that the arithmetic average roughness (Ra) on each surface is in the above range.
Said arithmetic mean roughness (Ra) can be calculated | required as an average value of each arithmetic mean roughness (Ra) measured in arbitrary five places of the film surface, Specifically, in the item of an Example. It can obtain | require by the method mentioned later. Here, each arithmetic mean roughness (Ra) can be measured according to JIS B0601: 2001.

  The Young's modulus of the film of the present invention is preferably 150 MPa or less, more preferably 135 MPa or less, and further preferably 125 MPa or less. A film having a Young's modulus of 150 MPa or less has sufficient flexibility. Although there is no restriction | limiting in particular in the minimum of a Young's modulus, Since it becomes a film which has sufficient intensity | strength, it is preferable that a Young's modulus is 80 Mpa or more. In addition, the Young's modulus of a film can be measured by the method mentioned later in the item of an Example. The film having the above Young's modulus can be easily obtained by adopting a gravure coating method when a coating liquid containing fine particles is applied to the surface of the PVA polymer film.

  Moreover, according to this invention, the film which maintains high transparency is obtained. The degree of transparency of the film of the present invention can be evaluated by the haze value. Specifically, the haze value of the film is preferably in the range of 0 to 5%, and in the range of 0 to 3%. It is more preferable. A film having a haze value of 5% or less has preferable transparency when used as a packaging material. In addition, the haze value of a film can be measured by the method mentioned later in the item of an Example.

  Although there is no restriction | limiting in particular in the use of the film of this invention, It can use preferably in a packaging material application taking advantage of properties, such as high softness | flexibility, transparency, and heat sealability.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. In addition, each measurement or evaluation method of arithmetic average roughness (Ra), Young's modulus, haze value, heat seal strength, and slipperiness of the film followed the following method.

(1) Measuring Method of Arithmetic Average Roughness (Ra) of Film The arithmetic average roughness (Ra) of the film was measured using a white interference microscope “New View 6300” manufactured by Zygo as follows.
The flow at the time of applying arbitrary 5 places in one side of the film obtained in the following Examples or Comparative Examples at a magnification of 20 times and applying the coating liquid with a gravure roll at any position of each observation image Arithmetic average roughness (Ra) was measured at 250 μm in the direction (MD; the flow direction when immersed in the coating liquid in Comparative Example 1). The average value of the measured values at five locations was defined as the arithmetic average roughness (Ra) of the film surface.

(2) Method for Measuring Young's Modulus of Film The Young's modulus of the film was measured as follows using a tensile tester “AG-IS” manufactured by Shimadzu Corporation.
The film obtained in the following examples or comparative examples was left to adjust humidity for 20 hours under conditions of 20 ° C. and 65% RH, and then flow direction (MD; In Comparative Example 1, the flow direction when immersed in the coating liquid) × width direction (TD) = 200 mm × 15 mm, cut into a size of 100 mm, and attached to a testing machine at 20 ° C. and 65% RH. A tensile test was performed at a tensile speed of 1000 mm / min, and the Young's modulus was calculated from the ratio of the obtained initial stress and initial strain.

(3) Method for measuring haze value of film The haze value of the film was measured according to the description of JIS K7105-1981 using a haze meter “HZ-1” manufactured by Suga Test Instruments Co., Ltd.

(4) Measuring method of heat seal strength of film Two films obtained in the following examples or comparative examples were superposed, and a part thereof was heated to 380 ° C. and heat sealed, and then perpendicular to the part. Cut into a size of 15 mm in width and 200 mm in length (the heat-sealed part is 15 mm in width and about 100 mm in length) and left to stand for 24 hours under conditions of 5 ° C. and 40% RH. ) Is attached to the tensile tester described in) at a chuck interval of 100 mm, a tensile test is performed at a tensile speed of 1000 mm / min under the conditions of 5 ° C. and 40% RH, and the tensile strength when peeling at the heat seal interface is defined as the heat seal strength. did.

(5) Evaluation method of slipperiness of film The slipperiness of the film was evaluated as follows using a friction measuring device "AN" manufactured by Toyo Seiki Seisakusho Co., Ltd.
The test piece was in close contact with the main body tilt plate and weight of the measuring machine (the surface facing the main body tilt plate was 60 mm wide and 100 mm long, and the weight was 1000 g), and the tilt angle was adjusted to 0 °. A weight was placed on the test piece of the plate so that the test piece faced. Thereafter, the angle of the inclined plate was gradually increased, and the angle at which the weight slipped and dropped (fall angle) was measured. The same test was performed 10 times, and the average value of the 10 measurement results obtained was evaluated as the slipperiness of the PVA film. The smaller the drop angle, the greater the slipperiness.

[Example 1]
In a PVA aqueous solution containing 1.5% by mass of PVA (saponified product of vinyl acetate homopolymer) having a polymerization degree of 2400 and a saponification degree of 99.2 mol%, a methyl methacrylate / styrene copolymer having an average particle diameter of 0.1 μm. [PVA] / Emulsion of polymer (methyl methacrylate unit / styrene unit (molar ratio) = 50/50) (methyl methacrylate / styrene copolymer particles dispersed in water at a concentration of 30% by mass) [Methyl methacrylate / styrene copolymer] (mass ratio) = 3/1 was added to obtain a coating solution.
On the other hand, an aqueous solution having a PVA concentration of 10% by mass containing 100 parts by mass of PVA (saponified product of vinyl acetate homopolymer) having a polymerization degree of 1700 and a saponification degree of 99.9 mol% and 12 parts by mass of glycerin as a plasticizer is used as a metal roll. It dried above and obtained the long PVA film (what was wound by roll shape) of width 90cm, length 1000m, and thickness 50micrometer.
Using the gravure roll having a cell depth of 14 μm on one side of the long PVA film, the coating solution is in a ratio of 0.020 g / m ² of methyl methacrylate / styrene copolymer. Then, the above coating solution was similarly applied to the other surface, and further dried with hot air at 80 ° C. for 2 seconds to obtain a film in which fine particles were arranged on both sides of the PVA film. . In addition, application | coating of the coating liquid was performed continuously along the flow direction (length direction of a long PVA film) at the time of film-forming of a long PVA film. Table 1 shows various measurements or evaluation results of the obtained film.

[Example 2]
The concentration of PVA in the PVA aqueous solution used for the production of the coating liquid was changed from 1.5% by mass to 1.2% by mass ([PVA] / [methyl methacrylate / styrene copolymer] (mass ratio) = 3/1 remains maintained), the amount of methyl methacrylate / styrene copolymer, except for changing from 0.020 g / ^{m 2} to 0.016 g / ^{m 2} to obtain a film in the same manner as in example 1 . Table 1 shows various measurements or evaluation results of the obtained film.

[Example 3]
The concentration of PVA in the PVA aqueous solution used for the production of the coating liquid was changed from 1.5 mass% to 2.5 mass% ([PVA] / [methyl methacrylate / styrene copolymer] (mass ratio) = 3/1 remains maintained), the amount of methyl methacrylate / styrene copolymer, except for changing from 0.020 g / ^{m 2} to 0.033 g / ^{m 2} to obtain a film in the same manner as in example 1 . Table 1 shows various measurements or evaluation results of the obtained film.

[Example 4]
Instead of an emulsion of methyl methacrylate / styrene copolymer having an average particle size of 0.1 μm, methyl methacrylate / styrene copolymer having an average particle size of 0.2 μm (methyl methacrylate unit / styrene unit (mol) Ratio) = 50/50) A film was obtained in the same manner as in Example 1 except that an emulsion (methyl methacrylate / styrene copolymer particles dispersed in water at a concentration of 30% by mass) was used. . Table 1 shows various measurements or evaluation results of the obtained film.

[Example 5]
Instead of the gravure roll depth of the cell is 14 [mu] m, using a gravure roll depth of the cell is 17 .mu.m, 0.024 g / ^{m 2} the amount of methyl methacrylate / styrene copolymer, from 0.020 g / ^{m 2} A film was obtained in the same manner as in Example 1 except that the change was made. Table 1 shows various measurements or evaluation results of the obtained film.

[Comparative Example 1]
The coating solution used in Example 1 was applied to both sides of the PVA film used in Example 1 so that the methyl methacrylate / styrene copolymer was 0.020 g / m ² per side by dipping. The film was dried with hot air at 100 ° C. for 30 seconds to obtain a film in which fine particles were arranged on both sides of the PVA film. In addition, application | coating of a coating liquid is continuously performed by immersing a PVA film in a coating liquid along the flow direction (length direction of a long PVA film) at the time of film-forming of a long PVA film. It was. Table 1 shows various measurements or evaluation results of the obtained film.

[Comparative Example 2]
Instead of the gravure roll depth of the cell is 14 [mu] m, using a gravure roll depth of the cell is 20 [mu] m, 0.029 g / ^{m 2} the amount of methyl methacrylate / styrene copolymer, from 0.020 g / ^{m 2} A film was obtained in the same manner as in Example 1 except that the change was made. Table 1 shows various measurements or evaluation results of the obtained film.

[Comparative Example 3]
Instead of an emulsion of methyl methacrylate / styrene copolymer having an average particle size of 0.1 μm, methyl methacrylate / styrene copolymer having an average particle size of 1.0 μm (methyl methacrylate unit / styrene unit (mol) Ratio) = 50/50) A film was obtained in the same manner as in Example 1 except that an emulsion (methyl methacrylate / styrene copolymer particles dispersed in water at a concentration of 30% by mass) was used. . Table 1 shows various measurements or evaluation results of the obtained film.

[Comparative Example 4]
Instead of an emulsion of methyl methacrylate / styrene copolymer having an average particle size of 0.1 μm, methyl methacrylate / styrene copolymer having an average particle size of 0.01 μm (methyl methacrylate unit / styrene unit (mol) Ratio) = 50/50) A film was obtained in the same manner as in Example 1 except that an emulsion (methyl methacrylate / styrene copolymer particles dispersed in water at a concentration of 30% by mass) was used. . Table 1 shows various measurements or evaluation results of the obtained film.

[Comparative Example 5]
The PVA film used in Example 1 was used as it was without applying the coating solution. The various measurements or evaluation results of the film are shown in Table 1.

  As is clear from the results in Table 1, the films of Examples 1 to 5 were excellent in all of flexibility, transparency, heat sealability, and slipperiness.

  According to the present invention, while maintaining high flexibility and transparency, a film having excellent slipperiness, hardly causing a blocking phenomenon, and excellent in heat sealability can be obtained. Can be preferably used.

Claims (12)

  A film in which fine particles are arranged on the surface of a polyvinyl alcohol polymer film, wherein the film surface has an arithmetic average roughness (Ra) of 80 to 300 nm and a Young's modulus of 150 MPa or less.   The film according to claim 1, wherein an average particle diameter of the fine particles is 0.02 to 0.5 μm.   The film of Claim 1 or 2 in which the said microparticle is formed from the copolymer of (meth) acrylic acid ester and aromatic vinyl.   The film according to any one of claims 1 to 3, wherein the fine particles are fixed to the surface of the polyvinyl alcohol polymer film by a binder.   The film according to claim 4, wherein the binder is a polyvinyl alcohol polymer.   The film of any one of Claims 1-5 whose haze value is 0 to 5%.   The manufacturing method of the film whose arithmetic mean roughness (Ra) of the film surface is 80-300 nm including the process of apply | coating the coating liquid containing microparticles | fine-particles on the surface of a polyvinyl alcohol-type polymer film by the gravure coating method.   The manufacturing method of Claim 7 whose average particle diameter of the said microparticle is 0.02-0.5 micrometer.   The manufacturing method of Claim 7 or 8 in which the said microparticle is formed from the copolymer of (meth) acrylic acid ester and aromatic vinyl.   The manufacturing method of any one of Claims 7-9 whose depth of the cell of a gravure printing plate is 5-18 micrometers.   The manufacturing method of any one of Claims 7-10 in which the said coating liquid contains the said microparticle and a binder.   The manufacturing method of Claim 11 whose said binder is a polyvinyl alcohol-type polymer.