JP2022186742A - release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film that includes a release layer containing a silicone compound on at least one side of a polyester film (substrate), the release film capable of maintaining adhesion between the polyester film (substrate) and the release layer even when the release layer makes contact with a solvent, thus retaining excellent releasability.

SOLUTION: A release film includes a release layer on at least one side of a polyester film. The release layer contains a silicone compound, and a compound containing a methacryloyl group. The compound containing a methacryloyl group is a combination of urethane methacrylate and a polyfunctional methacrylate compound excluding the urethane methacrylate.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a release film comprising a release layer containing a silicone compound on at least one side of a polyester film.

As an example of a manufacturing method for a liquid crystal display device used as an image display device for liquid crystal televisions, computer displays, mobile phones, digital cameras, etc., a release film is attached to one side of an adhesive layer, and the adhesive layer is used as a polarizing plate. After producing a polarizing plate with an adhesive layer by sticking to, when laminating with a liquid crystal cell, the release film is peeled off and the adhesive layer and the glass substrate of the liquid crystal cell are stuck. .

In recent years, as displays have become larger, the dimensions of optical members such as polarizing plates and release films have increased. The ability to be peeled off, that is, the property of being able to be peeled off with a small force (also referred to as "light peelability") has come to be demanded.
In this respect, silicone is a material that excels in the property that it can be peeled off with a small force due to the flexibility of the siloxane skeleton and the low surface energy due to methyl group substitution. Therefore, a release film having a release layer containing silicone has attracted attention as a release film for protecting an adhesive to which optical members such as members constituting a liquid crystal display are attached.

Patent Document 1 discloses a coating formed using a release coating composition containing an aqueous dispersion of an alkenyl group-containing silicone, an aqueous dispersion of a silicone having an Si—H group, and a cross-linking reaction inhibitor having an ethynyl group. A silicone release polyester film having a layer is disclosed.

In Patent Document 2, on at least one side of a substrate film, an aqueous dispersion of an alkenyl group-containing silicone, an aqueous dispersion of a silicone having an Si—H group, and a carboxyl group and an ionic group on the main skeleton and side chains. Disclosed is a silicone release film having a coated layer formed using a release coating composition comprising an aqueous dispersion of an organically free acrylic resin.

JP 2013-208810 A JP 2014-213590 A

As described above, a release film having a configuration in which a release layer containing a silicone compound is laminated on a polyester film (substrate) tends to have a reduced release performance when the release layer comes into contact with a solvent. Admitted. For example, when an adhesive resin composition containing a solvent is applied to the release layer to form an adhesive layer on the release layer, the release performance of the release layer is reduced, and the adhesive layer is difficult to peel off. There was something that happened. In particular, this tendency appeared strongly when the release layer came into contact with the solvent after the release film was stored for a long period of time in a state in which the release layer was laminated on the polyester film (substrate). This is probably because the adhesiveness between the release layer and the polyester film (substrate) was lowered.

Therefore, the present invention relates to a release film having a release layer containing a silicone compound on at least one side of a polyester film (substrate). ) and the release layer, and to provide a new release film capable of maintaining excellent releasability, and a method for producing the same.

The present invention is a release film having a release layer on at least one side of a polyester film, wherein the release layer contains a silicone compound and a (meth)acryloyl group-containing compound. We propose a release film.

The present invention also provides a release film having a release layer on at least one side of the polyester film, wherein the release layer comprises a silicone compound and a compound containing a (meth)acryloyl group. A release film characterized by being a layer formed from a composition is proposed.

The present invention is also characterized by forming a release layer by applying a release layer-forming composition containing a silicone compound and a compound containing a (meth)acryloyl group to at least one side of a polyester film. We propose a method for manufacturing a release film that

In the release film proposed by the present invention, the release layer laminated on the polyester film (substrate) contains, in addition to the silicone compound, a compound containing a (meth)acryloyl group, so that the release layer becomes a solvent. The adhesiveness between the polyester film (substrate) and the release layer can be maintained even when it comes into contact with. Therefore, for example, when forming a pressure-sensitive adhesive sheet with a release layer, a solvent-containing pressure-sensitive adhesive resin composition is applied onto the release layer, and the release layer is in contact with the solvent, even if the polyester film Adhesion between the (substrate) and the release layer can be maintained.
Further, according to the release film manufacturing method proposed by the present invention, the release film proposed by the present invention can be manufactured.

Next, the present invention will be described based on embodiments. However, the present invention is not limited to the embodiments described below.

<<This release film>>
A release film (referred to as "this release film") according to an embodiment of the present invention includes a release layer ( (referred to as "this release layer"), and the release layer is characterized by containing a silicone compound and a compound containing a (meth)acryloyl group.

<This polyester film>
The polyester film serves as a base material for the release film.
The present polyester film may be a non-stretched film (sheet) or a stretched film. Among them, stretched films uniaxially or biaxially stretched are preferred. Among them, a biaxially stretched film is preferable from the viewpoint of excellent balance of mechanical properties and flatness.

(this polyester)
The polyester (also referred to as "the present polyester"), which is the main component resin of the present polyester film, may be a homopolyester or a copolyester.

The above-mentioned main component resin means a resin having the largest mass ratio among the resins constituting the present polyester film, and is 50% by mass or more, or 75% by mass or more, or 90% by mass of the resin constituting the present polyester film. The case where it accounts for more than mass % or 100 mass % can be mentioned.

When the polyester is a homopolyester, it is preferably obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol.
Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol, and the like. .
Typical polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like.

On the other hand, when the present polyester is a copolymerized polyester, it is preferably a copolymer containing 30 mol % or less of the third component.
Examples of the dicarboxylic acid component of the copolymer polyester include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid and the like.
Examples of the glycol component of the copolymer polyester include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like.

It is preferable that 80 mol % or more, preferably 90 mol % or more of the polyester is polyethylene terephthalate, which is an ethylene terephthalate unit, or polyethylene-2,6-naphthalate, which is an ethylene-2,6-naphthalate unit. .

(particle)
The present polyester film may contain particles for the main purpose of imparting slipperiness.
The type of particles is not particularly limited as long as they are particles that can impart easy lubricity. Examples include particles of silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide and titanium oxide. Further, heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755, etc. may be used. Examples of other heat-resistant organic particles include thermosetting urea resin, thermosetting phenol resin, thermosetting epoxy resin, benzoguanamine resin, and the like. Furthermore, precipitated particles obtained by partially precipitating a metal compound such as a catalyst during the polyester production process can also be used.
The shape of the particles is not particularly limited, and may be, for example, spherical, massive, rod-like, or flat.
There are no particular restrictions on the hardness, specific gravity, color, etc. of the particles.
Moreover, two or more types of particles may be used in combination as necessary.

The average particle size of the particles is preferably 0.1 to 5 μm.
If the average particle diameter of the particles is 0.1 μm or more, aggregation of the particles can be suppressed and dispersibility can be ensured. On the other hand, if the average particle diameter of the particles is 5 μm or less, the surface roughness of the film does not become too rough, and the release layer can be suitably provided in the post-process.
From this point of view, the average particle size of the particles is preferably 0.1 to 5 μm, more preferably 0.5 μm or more or 3 μm or less.

The particle content in the present polyester film is preferably 0.0003 to 5% by weight.
If the particle content is 0.0003% by mass or more, the slipperiness of the film can be made suitable. On the other hand, if the particle content is 5% by mass or less, the smoothness of the film surface can be sufficiently ensured.
From this point of view, the particle content is preferably 0.0003 to 5% by mass, more preferably 0.001 to 3% by mass.

(other additives)
The present polyester film can also contain other additives as needed. For example, it may contain antioxidants, heat stabilizers, lubricants, dyes, pigments, and the like.

(Thickness of this polyester film)
The thickness of the present polyester film is preferably as thin as possible in terms of cost. On the other hand, if the thickness is too thin, the flatness of the film may be impaired by wrinkles or the like due to heat treatment during processing, and the protective function as a release film may not be sufficient. Therefore, the thickness of the present polyester film is preferably 10 μm to 125 μm, more preferably 12 μm or more or 75 μm or less.

The present polyester film may have a single layer structure or a multilayer structure of two or more layers, and is not particularly limited.
When the present polyester film contains particles, it preferably has a structure of three or more layers from the viewpoint of ensuring transparency without degrading the slipperiness. It is more preferable that the particles are contained in the outermost layer.

<Main release layer>
The release layer is a layer containing a silicone compound and a compound containing a (meth)acryloyl group.
Here, the silicone compound and the (meth)acryloyl group-containing compound are used as different compounds. That is, it does not mean that only silicone compounds containing (meth)acryloyl groups are used.

When a release layer containing a silicone compound, for example, a release layer formed by crosslinking or curing a silicone compound, comes into contact with a solvent such as toluene, the insufficiently cured uncured portion dissolves or swells. , There is a tendency for the adhesion between the polyester film, which is the base film, and the release layer to deteriorate. This tendency appeared strongly when in contact with the solvent of
On the other hand, as a result of various investigations, the present inventors found that when the present release layer is formed by blending a silicone compound with a compound containing a (meth)acryloyl group, the present release layer comes into contact with the solvent. It was found that the adhesiveness between the polyester film (substrate) and the release layer can be maintained even when the composition is applied. The reason for this is not clear, but it is believed that the (meth)acryloyl group-containing compound affects the adhesion between the silicone compound and the polyester film.

The release layer preferably has a crosslinked structure having a skeleton derived from a silicone compound. Having such a crosslinked structure is preferable because it can ensure release performance.
Among them, it is preferable to have a crosslinked structure having a skeleton derived from a compound containing a silicone compound and a (meth)acryloyl group. Having such a crosslinked structure is preferable because it is believed that the adhesion between the polyester film and the release layer is improved.
Among them, it is more preferable to contain a Si—H group derived from a silicone compound and/or a urethane structure derived from a urethane (meth)acrylate from the viewpoint of adhesion between the polyester film and the release layer.

(silicone compound)
A silicone compound is a compound having a silicone structure in its molecule, in other words, a compound having a main skeleton formed by siloxane bonds.
Examples of the silicone compound or main skeleton constituting the silicone compound include organopolysiloxane such as polydimethylsiloxane, acrylic-grafted silicone, silicone-grafted acrylic, amino-modified silicone, perfluoroalkyl-modified silicone, and alkyl-modified silicone. . Among them, organopolysiloxane such as polydimethylsiloxane is preferable from the viewpoint of excellent releasability.

Among them, a silicone compound having a functional group capable of reacting with a (meth)acryloyl group is preferred, and among these, a silicone compound containing a Si—H group is particularly preferred.
The Si—H group of the silicone compound has the property of enhancing adhesion with the present polyester film. However, the Si—H groups may decrease due to aging, for example, when the film is stored for a long period of time in the form of a release film, resulting in a decrease in adhesion to the polyester film. Therefore, by blending a compound containing a (meth)acryloyl group, the adhesiveness to the present polyester film can be further enhanced.
Among them, a silicone compound having an Si—H group and an alkenyl group is preferable from the viewpoint of forming a crosslinked structure having a skeleton derived from the silicone compound in the release layer.

The molecular weight of the silicone compound is not particularly limited. Among them, the number average molecular weight is preferably 5,000 or more, more preferably 10,000 or more, from the viewpoint of adhesion between the polyester film (substrate) and the release layer. Although the upper limit is not particularly limited, it is usually 1,000,000 or less.
The number average molecular weight of the silicone compound can be measured, for example, by gel permeation chromatography (GPC) and calculated as a polystyrene equivalent value.

The silicone compound is preferably contained in the release layer at a rate of 50 to 99% by mass.
If the silicone compound is contained in the release layer in an amount of 50% by mass or more, it is preferable because sufficient releasability can be obtained, and if it is 99% by mass or less, it is preferable because sufficient solvent resistance can be obtained.
From this point of view, the silicone compound is preferably contained in the present release layer at a rate of 50 to 99% by mass, especially 60% by mass or more or 99% by mass or less, and among them 70% by mass or more or 98% by mass or less. is more preferably contained in a ratio of

(Compound containing (meth)acryloyl group)
The compound containing a (meth)acryloyl group includes a polymer (meth)acrylate compound and a monomer (meth)acrylate compound, any of which may be used. Moreover, these can also be used together.
Here, polymeric (meth)acrylate compounds mean macromonomers.

Examples of (meth)acrylate compounds include urethane (meth)acrylate compounds, epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, polyalkylene (meth)acrylate compounds, and other (meth)acrylate compounds. can be mentioned.
The terms "(meth)acryloyl group-containing compound", "(meth)acrylate compound", and "(meth)acrylate" used herein are all of a compound containing an acryloyl group and a compound having a methacryloyl group. It is a concept that includes both, and may contain either an acryloyl group or a methacryloyl group, or both.

As the urethane (meth)acrylate compound, conventionally known compounds can be used, and there is no particular limitation. For example, a compound obtained by reacting a (meth)acrylate compound having a hydroxyl group with an isocyanate compound, A compound obtained by reacting a meth)acrylate compound, a polyol, and an isocyanate compound can be used. The urethane (meth)acrylate compound may be a polymer or a monomer, but is preferably a polymer from the viewpoint of adhesion to the polyester film.

(Meth)acrylate compounds having a hydroxyl group include, for example, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerin mono(meth)acrylate, glycerin di( meth)acrylate, diglycerin mono(meth)acrylate, diglycerin tri(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate ) acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, sorbitol di(meth)acrylate, sorbitol tri(meth)acrylate ) acrylate, sorbitol tetra(meth)acrylate, sorbitol penta(meth)acrylate, sorbitol mono(meth)acrylate diglycerin di(meth)acrylate, adduct of glycidyl (meth)acrylate and (meth)acrylic acid, bimolecular ( Reaction product of meth)acrylic acid and one molecule of 1,6-hexanedioldiglycidyl, reaction product of two molecules of epoxy (meth)acrylic acid and one molecule of neopentylglycol diglycidyl, two molecules of ( Reaction product of meth)acrylic acid and 1 molecule of bisphenol A diglycidyl, reaction product of 2 molecules of (meth)acrylic acid and diglycidyl of propylene oxide adduct of bisphenol A, 2 molecules of (meth)acrylic acid and one molecule of diglycidyl phthalate, a reaction product of two molecules of (meth)acrylic acid and one molecule of polyethylene glycol diglycidyl, two molecules of (meth)acrylic acid and one molecule of polypropylene glycol di- Examples include reaction products of (meth)acrylic acid and polyol diglycidyl, such as reaction products with glycidyl. These may be used alone or in combination of multiple types.

Among them, diglycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentatri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, and dipentaerythritol tri(meth)acrylate. The number of (meth)acryloyl groups in one molecule such as erythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, sorbitol tri (meth) acrylate, sorbitol tetra (meth) acrylate, sorbitol penta (meth) acrylate Three or more are preferred, and dipentaerythritol penta(meth)acrylate, sorbitol penta(meth)acrylate and the like having five or more (meth)acryloyl groups per molecule are more preferred.

An isocyanate-based compound is a compound having an isocyanate derivative structure represented by isocyanate or blocked isocyanate. Examples of isocyanates include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate and naphthalene diisocyanate, and aromatic rings such as α,α,α',α'-tetramethylxylylene diisocyanate. Aliphatic isocyanates such as aliphatic isocyanate, methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, Alicyclic isocyanates such as methylenebis(4-cyclohexyl isocyanate) and isopropylidene dicyclohexyl diisocyanate can be exemplified. Reaction products of these isocyanates and various polymers and compounds may also be used. Polymers and derivatives of these isocyanates such as burettes, isocyanurates, uretdione compounds and carbodiimide modified products can also be used. These may be used alone or in combination of multiple types. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are preferred, and alicyclic isocyanates are more preferred, from the viewpoint of improving the adhesion of the release layer to the polyester film.

Examples of polyols include polycarbonate polyols, polyester polyols, polyether polyols, etc. High molecular weight polyols and low molecular weight polyols can be used.

The high molecular weight polyol is not particularly limited, but preferably has a number average molecular weight of 400 to 8,000, more preferably 400 to 4,000. When the number average molecular weight is within this range, the viscosity is appropriate and a good appearance of the release layer can be obtained.

Examples of high-molecular-weight polyols include polycarbonate polyols, polyester polyols, and polyether polyols. Polycarbonate polyol is preferred in order to improve adhesion to the polyester film.

Polycarbonate polyols are obtained from polyhydric alcohols and carbonate compounds by a dealcoholization reaction. Polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane Diol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane diol, neopentyl glycol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane 1,4-benzenedimethanol, 1,3-benzenedimethanol, 4,4'-naphthalenedimethanol, 3 , 4′-naphthalenedimethanol and the like. Examples of carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate. Examples of polycarbonate polyols obtained from these reactions include polyhexamethylene carbonate diol and polycyclohexylene carbonate diol. be able to. Among these, polyhexamethylene carbonate diol is preferable from the viewpoint of adhesion of the release layer to the polyester film.

Polyester polyols include polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides. substances and polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol , 2-methyl-2-propyl-1,3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2 ,5-dimethyl-2,5-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2 -hexyl-1,3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamine, lactonediol, etc.), lactone compounds such as polycaprolactone Examples include those having a derivative unit.

Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol and the like.

The low-molecular-weight polyol is not particularly limited, but examples thereof include those having a number average molecular weight of 60 or more and less than 400. For example, ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol , 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol , diethylene glycol, triethylene glycol, tetraethylene glycol, and other aliphatic diols having 2 to 9 carbon atoms; 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,4-bis diols having an alicyclic structure having 6 to 12 carbon atoms such as (hydroxyethyl)cyclohexane, 2,7-norbornanediol, tetrahydrofurandimethanol, 2,5-bis(hydroxymethyl)-1,4-dioxane; ,2-dimethylolpropanoic acid, 2,2-dimethylolbutanoic acid, and other dimethylolalkanoic acids, trimethylolpropane, pentaerythritol, sorbitol, and other low-molecular-weight polyhydric alcohols. Among these, dimethylolalkanoic acid is preferable from the viewpoint of improving the stability of the aqueous dispersion of the urethane (meth)acrylate compound.

As the epoxy (meth)acrylate compound, conventionally known compounds can be used, and there is no particular limitation. For example, a compound obtained by reacting an epoxy resin with (meth)acrylic acid or a carboxyl group-containing (meth)acrylate. can be mentioned.

Examples of epoxy resins include compounds containing an epoxy group in the molecule. Polyepoxy compounds such as polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, cresol novolak type, phenol novolac type novolac epoxy resin, bisphenol A type , bisphenol F type, bisphenol S type and other bisphenol type epoxy resins. Among these, cresol novolak type epoxy resins are preferred.

(Meth)acrylic acid includes acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid and citraconic acid.

The epoxy (meth)acrylate compound is preferably a composite resin made of a urethane resin from the viewpoint of further improving the adhesion to the polyester film.
Conventionally known urethane resins can be used as the urethane resin.
Urethane resins are generally produced by the reaction of polyols and isocyanates.
Examples of polyols include the aforementioned polyester polyols, polycarbonate polyols, polyether polyols, etc. These compounds may be used singly or in combination.
Among the above, polyester polyols are more preferable from the viewpoint of adhesion to the polyester film.

Examples of (meth)acrylate compounds include monofunctional (meth)acrylates, bifunctional (meth)acrylates, polyfunctional (meth)acrylates, and the like. Here, the polyfunctional (meth)acrylate refers to a compound having three or more (meth)acrylate groups in one molecule.
A (meth)acrylate compound may be a polymer or a monomer. A monomer is preferable from the viewpoint of reactivity with the silicone compound.

The monofunctional (meth)acrylate is not particularly limited. For example, alkyl (meth)acrylate such as methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc. hydroxyalkyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate ) acrylate, alkoxyalkyl (meth)acrylate such as ethoxypropyl (meth)acrylate, aromatic (meth)acrylate such as benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, diaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate ) Amino group-containing (meth)acrylates such as acrylate, methoxyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, ethylene oxide-modified (meth)acrylates such as phenylphenol ethylene oxide-modified (meth)acrylate, glycidyl ( Meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (meth)acrylic acid and the like can be mentioned.

Examples of bifunctional (meth)acrylates include, but are not limited to, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth) alkanediol di(meth)acrylate such as acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecanedimethylol di(meth)acrylate, bisphenol A ethylene oxide modified di(meth)acrylate, bisphenol F ethylene oxide modified Bisphenol-modified di(meth)acrylate such as di(meth)acrylate, glycerin di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol di(meth)acrylate, dipentaerythritol di(meth)acrylate, polyethylene glycol Di(meth)acrylate, polypropylene glycol di(meth)acrylate, urethane di(meth)acrylate, epoxy di(meth)acrylate and the like can be mentioned.

Examples of polyfunctional (meth)acrylates include, but are not limited to, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, and propylene oxide. Modified trimethylolpropane tri(meth)acrylate and other alkylenoxide-modified trimethylolpropane tri(meth)acrylate, isocyanuric acid ethylene oxide-modified tri(meth)acrylate, ε-caprolactone-modified tris(acroxyethyl) isocyanurate, etc. Isocyanuric acid-modified tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate Acrylates, tetramethylolmethane ethylene oxide-modified tetra(meth)acrylate, alkylenoxide-modified pentaerythritol tetra(meth)acrylate such as ethylene oxide-modified pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipenta Erythritol hexa(meth)acrylate and the like can be mentioned.

Among these, bifunctional (meth)acrylates or polyfunctional (meth)acrylates are preferable, and polyfunctional (meth)acrylates are more preferable, from the viewpoint of forming crosslinks more efficiently and increasing the solvent resistance of the release layer. . Specifically, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipenta Erythritol hexa(meth)acrylate is preferred, and trimethylolpropane tri(meth)acrylate and dipentaerythritol hexa(tri)acrylate are more preferred.

Compounds containing (meth)acryloyl groups include urethane (meth)acrylates, mixtures of urethane (meth)acrylates and (meth)acrylate compounds other than urethane (meth)acrylates, or epoxy (meth)acrylates. ) It is preferably a composite resin of acrylate and urethane resin.
Conventionally, it has been known that when a release layer is formed by cross-linking or curing a silicone compound, if the silicone compound is used in combination with a urethane resin, the urethane resin inhibits the curing of the silicone compound. Therefore, it was common technical knowledge to avoid blending a urethane-based compound with a silicone compound. Surprisingly, however, as described above, the compounds containing (meth)acryloyl groups in the release layer include urethane (meth)acrylates, or urethane (meth)acrylates and urethane (meth)acrylates (excluding When a meth) acrylate compound or a composite resin of epoxy (meth) acrylate and urethane resin is combined, even if the release layer comes into contact with a solvent, the polyester film (base material) and the release layer It was confirmed that it is possible to effectively suppress the deterioration of the adhesion with.

Thus, as the compound containing a (meth)acryloyl group, urethane (meth)acrylate, or (meth)acrylate compounds other than urethane (meth)acrylate and urethane (meth)acrylate, or epoxy (meth)acrylate and When a combination of a composite resin and a urethane resin is used, the main release layer preferably has a crosslinked structure containing Si—H groups and a urethane structure, as described above.
At this time, the Si—H group is derived from the silicone compound, and the urethane structure is derived from the urethane (meth)acrylate.
In general, silicone compounds are hydrophobic and have low surface free energy. On the other hand, the resin skeleton of polyurethane has high polarity and high surface free energy. For this reason, even if these are mixed, it is considered that they normally repel each other and form a separate structure. However, in the present invention, if the urethane structure is introduced as a urethane (meth)acrylate instead of a polyurethane, some of the (meth)acryloyl groups react with the silicone compound, thereby suppressing the separation of the two. I found it. From this, it is considered that the introduction of the urethane structure could improve the solvent resistance, which was inadequate if only the silicone compound was used.
This technical concept is not limited to urethane (meth)acrylates, and can also be applied to other (meth)acryloyl group-containing compounds. Moreover, the present invention is not limited only to cases where the above technical ideas are clearly expressed.

(other ingredients)
The release layer can contain other components in addition to the silicone compound and the (meth)acryloyl group-containing compound. For example, polymers, cross-linking agents, particles, antifoaming agents, coatability improvers, thickeners, organic lubricants, antistatic agents, ultraviolet absorbers, antioxidants, foaming agents, dyes, pigments, etc. may be used in combination. It is possible. Specific examples of polymers include polyester resins, acrylic resins, urethane resins, polyvinyl (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starches, and the like. can be done.

The components contained in the release layer can be analyzed by TOF-SIMS, X-ray photoelectron spectroscopy (ESCA), fluorescent X-rays, or the like.

(Film thickness of the release layer)
The film thickness of the release layer is preferably 0.005 μm to 1 μm.
If the thickness of the release layer is 1 μm or less, deterioration of the appearance of the coating film and insufficient curing of the coating film can be suppressed. Sufficient releasability can be obtained.
From this point of view, the thickness of the release layer is preferably 0.005 μm to 1 μm, more preferably 0.02 μm or more or 0.5 μm or less, and more preferably 0.045 μm or more or 0.085 μm or less. preferable.

(Method for forming the release layer)
The release layer is a resin composition containing a silicone compound, a compound containing a (meth)acryloyl group, and, if necessary, a catalyst, particularly a platinum group metal catalyst, a catalytic activity inhibitor, etc. (also referred to as a "mold layer forming composition").
However, the detailed method of forming the release layer using the release layer-forming composition will be described later, and the release layer-forming composition will be described here.

(silicone compound)
The outline of the silicone compound is as described above.
Among those mentioned above, the silicone compound used in the present release layer-forming composition preferably contains a curable silicone compound in consideration of heat resistance and stain resistance.
As the type of curable silicone compound, any curing reaction type such as addition curing type, condensation curing type, ultraviolet curing type, electron beam curing type, etc. can be used. Among them, addition-curable silicone compounds are more preferable from the viewpoint that they can increase the coating film cohesive strength.

An addition-curable silicone compound is a silicone compound having an unsaturated hydrocarbon group and a hydrogen group as functional groups in its structure, and an addition curing reaction is carried out by the reaction of these functional groups. That is, it is a mixture of a silicone compound having an Si—H group and a silicone compound containing an alkenyl group, or a silicone compound containing an Si—H group and a vinyl group in its molecule.
From the viewpoint of pot life, it is preferable that the unsaturated hydrocarbon group and the hydrogen group are not present in the same molecule, and it is preferable to include the functional groups in separate silicone molecules and use a mixture thereof. Therefore, it is preferable to use a mixture of a silicone compound having an unsaturated hydrocarbon group as a functional group and a silicone compound having a hydrogen group as a functional group.

Examples of the silicone compound having an unsaturated hydrocarbon group as a functional group include polydimethylsiloxane containing an unsaturated hydrocarbon group.
At least two unsaturated hydrocarbon groups must be contained in the polydimethylsiloxane molecule. Examples of unsaturated hydrocarbon groups include alkenyl groups having 2 to 8 carbon atoms such as vinyl, propenyl, butenyl and pentenyl groups. Among these, a vinyl group is preferable from the viewpoint of industrial availability.
Alkenyl groups containing at least two may contain alkenyl groups with different carbon numbers.
The unsaturated hydrocarbon group-containing polydimethylsiloxane has an alkenyl group and a methyl group as functional groups directly linked to silicon atoms, and may also have various other functional groups. Examples of functional groups other than methyl include alkyl groups such as ethyl, propyl and butyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl and methylphenyl; and alkoxy groups such as groups. From the viewpoint of adhesion to the polyester film, it preferably contains a phenyl group or a methoxy group.

On the other hand, examples of the silicone compound having a hydrogen group as a functional group include hydrogen group-containing polydimethylsiloxane. A hydrogen group-containing polydimethylsiloxane is a polydimethylsiloxane having hydrogen atoms bonded to silicon atoms. At least two silicon-bonded hydrogen atoms must be contained in one molecule, and preferably three or more are contained from the viewpoint of curing properties. The silicon-bonded hydrogen atoms can be terminal or side chains of the polydimethylsiloxane molecular chain.
Hydrogen group-containing polydimethylsiloxane has hydrogen groups and methyl groups as functional groups directly linked to silicon atoms, but may have various other functional groups. Examples of functional groups other than methyl include alkyl groups such as ethyl, propyl, and butyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl and methylphenyl; and alkoxy groups such as groups.

The polydimethylsiloxane skeleton of the unsaturated hydrocarbon group-containing polydimethylsiloxane and the hydrogen group-containing polydimethylsiloxane may be linear or branched.

When blending unsaturated hydrocarbon-containing polydimethylsiloxane and hydrogen group-containing polydimethylsiloxane, the molar ratio of all Si—H groups to all alkenyl groups (Si—H group amount/alkenyl group amount) is 1.0 to 5.0. is preferably
If the molar ratio is 1.0 or more, the curability can be maintained, and if it is 5.0 or less, the amount of remaining Si—H groups is not too large, and the peeling force against the adhesive becomes heavy. It is preferable because it is not overdone.
From this point of view, it is preferably 1.0 to 5.0, more preferably 1.6 or more or 4.8 or less, and particularly preferably 2.0 or more or 4.6 or less.

The silicone compound used in the present release layer-forming composition may be a solvent-type curable silicone or a non-solvent-type curable silicone. It is also possible to use a mixture of solvent curable silicone and non-solvent curable silicone.
Whether it is a solvent-type curable silicone or a non-solvent curable silicone, it is a curable silicone that has releasability, and includes an addition reaction between a vinyl group and a group having a silicon-hydrogen bond during the curing process. (so-called addition-type silicones) are preferred.

From the viewpoint of work environment and safety such as organic solvent explosion and fire, it is preferable that the main solvent of the coating liquid used for forming the release layer is water, and the above-mentioned silicone compound is used as a silicone emulsion. is preferred.
When water is used as the main solvent, water accounts for preferably 80% by mass or more of the solvent, more preferably 90% by mass or more, and more preferably 95% by mass or more.
When emulsifying a silicone compound, a surfactant component can be used as an emulsion stabilizer.

Examples of surfactants include nonionic surfactants and anionic surfactants.
Nonionic surfactants include polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ethers, polyoxyalkylene phenyl ethers such as polyoxyethylene phenyl ethers, glycerin alkyl ethers, glycerin fatty acid esters and alkylene glycol adducts thereof, polyglycerin Fatty acid esters and their alkylene glycol adducts, propylene glycol fatty acid esters and their alkylene glycol adducts, polyalkylene glycol fatty acid esters and the like can be mentioned. Examples of anionic surfactants include fatty acid soaps such as sodium stearate and triethanolamine palmitate, alkyl ether carboxylic acids and their salts, alkyl sulfonic acids, alkene sulfonates, fatty acid ester sulfonates, and alkyl sulfate ester salts. , secondary higher alcohol sulfates, alkyl and allyl ether sulfates, fatty acid ester sulfates, polyoxyethylene alkyl sulfates, funnel oil and other sulfates, alkyl phosphates, ether phosphates, Alkyl allyl ether phosphates, amide phosphates and the like can be mentioned. Among these surfactants, nonionic surfactants are preferred, and polyoxyalkylene alkyl ethers and polyoxyalkylene phenyl ethers are more preferred from the viewpoint of the stability of the silicone emulsion.

Examples of polyoxyalkylene alkyl ethers include polyoxyethylene alkyl ethers, polyoxypropylene alkyl ethers, polyoxybutylene alkyl ethers, and the like. Among these, polyoxyethylene alkyl ether is preferred. The alkyl group is preferably a straight or branched alkyl group having 8 to 30 carbon atoms, more preferably a straight or branched alkyl group having 8 to 16 carbon atoms.

Examples of polyoxyalkylene phenyl ether include polyoxyethylene phenyl ether, polyoxypropylene phenyl ether, polyoxybutylene phenyl ether and the like. Among these, polyoxyethylene alkyl ether is preferred. Moreover, the phenyl group is an unsubstituted or substituted phenyl group, preferably a styrenated phenyl group in which a hydrogen atom of the phenyl group is substituted with a styryl group.

(Compound containing (meth)acryloyl group)
The (meth)acryloyl group-containing compound contained in the release layer-forming composition is as described above.

The content of the compound containing a (meth)acryloyl group contained in the present release layer-forming composition is preferably 1 to 50% by mass relative to the total non-volatile components in the present release layer-forming composition.
If the content of the compound containing the (meth)acryloyl group is 1% by mass or more, it is preferable because the adhesion of the release layer to the polyester film is obtained, and if it is 50% by mass or less, the releasability is improved. It is preferable because it is excellent.
From this point of view, the content of the (meth)acryloyl group-containing compound is preferably 1 to 50% by mass, especially 1% by mass, as a proportion of the total nonvolatile components in the release layer-forming composition. or more or 40% by mass or less, more preferably 2% by mass or more or 30% by mass or less.

The content of the (meth)acryloyl group-containing compound contained in the release layer-forming composition is preferably 1 to 100 parts by mass per 100 parts by mass of the silicone compound.
If the content of the compound containing the (meth)acryloyl group is 1 part by mass or more, it is preferable from the viewpoint that the adhesion of the release layer to the polyester film is obtained, and if it is 100 parts by mass or less, the release It is preferable from the viewpoint that it is preferable because it has excellent properties.
From this point of view, the content of the (meth)acryloyl group-containing compound is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the silicone compound content, especially 1 part by mass or more or 65 parts by mass parts or less, more preferably 2 parts by mass or more or 40 parts by mass or less.

(platinum group metal catalyst)
The release layer-forming composition can also be used in combination with a catalytic amount of a platinum group metal catalyst.
This platinum group metal catalyst is a catalyst for promoting a curing reaction of a silicone compound, for example, an addition curing reaction, and conventionally known addition reaction catalysts can be used.

Examples of platinum group metal catalysts include platinum-based, palladium-based and rhodium-based catalysts. Among these, platinum-based catalysts are preferred.
Examples of the platinum-based catalyst include chloroplatinic acid, alcohol solutions and aldehyde solutions of chloroplatinic acid, and complexes of chloroplatinic acid with various olefins or vinyl siloxanes.
From the viewpoint of pot life, the timing of blending the platinum group metal catalyst is preferably within 20 hours immediately before applying the release layer-forming composition, preferably within 10 hours. It is more preferable to have

The ratio of the platinum group metal catalyst to the silicone compound in the release layer is preferably in the range of 1 to 1000 ppm, more preferably in the range of 20 ppm or more or 800 ppm or less. Within the above range, it is possible to achieve both acceleration of the addition-type curing reaction and a suitable pot life.

(Other additive ingredients)
If necessary, the release layer-forming composition may contain a reactive heavy release modifier, a diluent solvent, a reaction modifier, an adhesion enhancer, an acetylene derivative, various organic nitrogen compounds, various phosphorus compounds, oxime compounds, and organic halogen compounds. Catalytic activity inhibitors such as compounds, oxazoline compounds, epoxy compounds, cross-linking agents such as silane coupling agents, particles, antifoaming agents, coatability improvers, thickeners, organic lubricants, antistatic agents, UV absorbers , antioxidants, foaming agents, dyes, pigments, etc. may be used in combination.

The reactive heavy release modifier is a type of heavy release modifier that reacts with the siloxane polymer of the release paint and is incorporated therein when the paint dries.
The chemical structure of the reactive heavy release modifier is preferably one having, for example, a vinyl group as a reactive group and generally called MQ resin or MDQ resin.

Diluting solvents include aromatic hydrocarbons such as toluene, aliphatic hydrocarbons such as hexane, heptane and isooctane, esters such as ethyl acetate and butyl acetate, ketones such as ethyl methyl ketone (MEK) and isobutyl methyl ketone. , alcohols such as ethanol and 2-propanol, and ethers such as diisopropyl ether and dibutyl ether. These are preferably used singly or in combination in consideration of solubility, coatability, boiling point, and the like.

<Lamination structure of the release film>
Since the release film may be provided with the release layer on one side or both sides of the polyester film, it has a laminated structure in which the release layer is laminated on one side or both sides of the polyester film. or another layer may be provided on the surface side of the release layer, or the release layer is laminated on one side of the polyester film and another layer is provided on the other side. may

Examples of the "other layer" include an antistatic layer, an oligomer sealing layer, an adhesive layer, and a release layer having a composition different from that of the release layer.
As an example of the laminated structure of the release film, the release layer is laminated on one side of the polyester film, and the antistatic layer, oligomer sealing layer, and adhesive layer are laminated on the other side. Laminate configurations with

The antistatic layer may contain an electronically conductive compound.
Examples of electronically conductive organic compounds include ammonium group-containing compounds, polyacetylene, polyphenylene, polyaniline, polypyrrole, polyisothianaphthene, and polythiophene. Among these, polythiophene, that is, a polymer obtained by homopolymerizing or copolymerizing thiophene or a thiophene derivative can be mentioned.
In addition to the electronically conductive compound, the antistatic layer contains one or more compounds selected from the group of polyalkylene oxide, glycerin, polyglycerin, and alkylene oxide adducts to glycerin or polyglycerin, or derivatives thereof. You may

When the antistatic layer is formed by coating, the coating liquid may contain, for example, surfactants, other binders, particles, antifoaming agents, coatability improvers, thickeners, antioxidants, ultraviolet absorbers, and foaming agents. , dyes, pigments, etc. These additives may be used alone, or two or more of them may be used in combination, if necessary.
In addition, chemical treatment, corona discharge treatment, plasma treatment, or the like may be applied to the present polyester film as a substrate before coating.

The oligomer sealing layer contains a coating layer formed from a coating system containing 70% by mass or more of a cross-linking agent as a non-volatile component, or a hydrolyzable alkoxysilicate and/or a polycondensate thereof. preferable.

As the cross-linking agent, various known cross-linking agents can be used, such as oxazoline compounds, melamine compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, silane coupling compounds and the like.

Examples of hydrolyzable alkoxysilicates include structures represented by the general formula Si(OR ₁ ) ₄ (R1 represents a hydrocarbon group having 1 to 10 carbon atoms).
The oligomer sealing layer may further contain inorganic particles, and specific examples of inorganic particles include silica, alumina, kaolin, calcium carbonate, titanium oxide, and barium salts.
In addition, the oligomer sealing layer may contain antifoaming agents, coatability improvers, thickeners, organic lubricants, organic polymer particles, antioxidants, ultraviolet absorbent foaming agents, dyes, and the like. good.

The adhesive layer contains an adhesive composition. The adhesive composition can be used without particular limitation as long as it can impart adhesiveness, and examples thereof include acrylic adhesives, urethane-based adhesives, rubber-based adhesives, and silicone-based adhesives. Among these, acrylic pressure-sensitive adhesives are preferable from the viewpoint of easy adjustment of pressure-sensitive adhesive properties and excellent transparency. Moreover, as a formation method of an adhesive, a thermosetting type, an active-energy-ray-curable type, a hot-melt type, etc. can be mentioned, for example.
When the adhesive layer is formed by coating, the coating liquid contains, for example, a binder, a cross-linking agent, a surfactant, particles, an antifoaming agent, a coatability improver, a thickener, an antioxidant, an ultraviolet absorber, and a foaming agent. , dyes, pigments, etc. These additives may be used alone, or two or more of them may be used in combination, if necessary.

<Method for producing the present release film>
The release film is obtained by applying the release layer-forming composition containing a silicone compound and a compound containing a (meth)acryloyl group to one side or both sides of the polyester film, and charging if necessary. The release layer is formed by forming the "other layers" such as the prevention layer, the oligomer sealing layer, and the adhesive layer, or by curing at any of these stages, and if necessary, heat treatment. can be manufactured.

The polyester film may be subjected to a surface treatment such as corona treatment or plasma treatment before the release layer-forming composition is applied. Furthermore, the present polyester film may be provided in advance with a coating layer such as an adhesive layer.

Heat treatment is generally used as an energy source for the curing treatment. However, ultraviolet irradiation and electron beam irradiation can be used together.

The method for forming the release layer, that is, the method for applying the release layer-forming composition may be in-line coating or offline coating.

Among them, it is preferable to employ in-line coating to form the release layer.
In-line coating is a method of coating in the process of manufacturing a polyester film. Specifically, it is a method in which coating is performed at any stage from melt extrusion of polyester to stretching, heat setting and winding. Usually, there is a method of coating an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, and a film after heat setting and before winding. can.

In the method for producing the release film, it is preferable to stretch the release layer after forming the release layer in the process of producing the polyester film.
For example, in sequential biaxial stretching, a method of applying the release layer-forming composition to a uniaxially stretched film stretched in the longitudinal direction (vertical direction) and then stretching the film in the transverse direction is preferred. According to such a method, the production of the present polyester film and the formation of the present release layer can be performed simultaneously, which is advantageous in terms of production cost. Furthermore, since stretching is performed after coating, the thickness of the release layer can be changed by the stretching ratio, and thin film coating can be performed more easily than offline coating. Further, by providing the release layer on the film before stretching, the release layer can be stretched together with the polyester film, thereby firmly adhering the release layer to the polyester film. . Furthermore, in the production of biaxially stretched polyester film, the film can be restrained in the vertical and horizontal directions by holding the ends of the film with a clip or the like while the film is stretched. High temperature can be applied while maintaining the properties. Therefore, since the heat treatment applied after coating can be made to a high temperature that cannot be achieved by other methods, the film-forming property of the release layer is improved, and the release layer and the polyester film are more strongly adhered. Furthermore, the present release layer can be made strong, and the performance and durability of the present release layer can be improved.

When the release layer is provided by inline coating, the release layer-forming composition described above is used as an aqueous solution or an aqueous dispersion, and the solid content concentration is adjusted to about 0.1 to 50% by mass as a guideline. Application on film is preferred.
In addition, the coating liquid may contain a small amount of an organic solvent for the purpose of improving the dispersibility in water, improving the film-forming properties, etc., within the scope not impairing the gist of the present invention. Only one type of organic solvent may be used, or two or more types may be used as appropriate.

Examples of methods for applying the release layer-forming composition include multi-roll coating, gravure coating, reverse gravure coating, reverse roll coating, direct gravure coating, die coating, air doctor coating, blade coating, rod coating, bar coating, and curtain coating. Conventionally known coating methods such as coating, knife coating, transfer roll coating, squeeze coating, impregnation coating, kiss coating, spray coating, calendar coating and extrusion coating can be used. For example, a coating technique as shown in "Coating Method" (written by Yuji Harasaki, published by Maki Shoten, 1979) can be used.
The coating head used at this time includes, for example, an air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, Curtain coaters, calendar coaters, extrusion coaters and the like can be exemplified.

After the release layer is formed as described above, the release layer is heated to 70° C. or higher, especially 80° C. or higher or 270° C. or lower, especially 100° C. or higher or 270° C. or lower, especially 180° C. or higher. Preferably, the release layer is dried or cured.
In particular, when the release layer is provided by off-line coating, heat treatment is preferably carried out at 80 to 200° C. for 3 to 40 seconds, preferably 100 to 180° C. for 3 to 40 seconds.
On the other hand, when the release layer is provided by inline coating, heat treatment is usually performed at 70 to 270° C. for 3 to 200 seconds, preferably at 180° C. or higher, especially at 180 to 270° C. for 3 to 200 seconds. The heat treatment may be performed together with the heat setting process of the film described above.

Regardless of off-line coating or in-line coating, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used together as needed.
The polyester film may be previously subjected to surface treatment such as corona treatment or plasma treatment.

<Characteristics of this release film>
The release film is measured under conditions of a tension speed of 0.3 m/min after attaching an acrylic adhesive tape (manufactured by Nitto Denko, No. 502) to the release layer and leaving it at room temperature for 1 hour. The 180° peel force can be 200 mN/cm or less, especially 100 mN/cm or less, especially 50 mN/cm or less. The lower limit of the peel force is not limited, and is specifically 0.1 mN/cm or more.

For this release film, Bemcot (“M-3II” manufactured by Asahi Kasei Fibers Co., Ltd.) impregnated with 4 mL of toluene on the surface of the release layer is attached to a rubbing tester (manufactured by Ohira Rika Kogyo Co., Ltd.), and the sample is subjected to an arm load of 680 g. After performing solvent treatment by reciprocating the release layer surface of the film 10 times, acrylic adhesive tape (manufactured by Nitto Denko, No. 502) was attached to this release layer and left for 1 hour at room temperature. The 180° peel force measured under the condition of 0.3 m/min can be 300 mN/cm or less, especially 200 mN/cm or less, especially 100 mN/cm or less. The lower limit of the peel force is not limited, and is specifically 0.1 mN/cm or more.
The present release film can thus obtain excellent releasability even after solvent treatment.

This release film is stored in an environment of 23 ° C. 50% RH for 1 month with an untreated polyester film overlaid on the release layer surface of the film, and then after solvent treatment on the release layer surface. , Acrylic adhesive tape (manufactured by Nitto Denko Co., Ltd., No. 502) was attached to the release layer and left for 1 hour at room temperature. It can be 800 mN/cm or less, especially 500 mN/cm or less, especially 350 mN/cm or less.
The present release film can obtain excellent release properties even after solvent treatment after long-term storage.

This release film can have a residual adhesion rate of 80% or more, which is the ratio of "F1/F0" measured as follows using an acrylic adhesive tape (manufactured by Nitto Denko, No. 31B). Among them, it can be 85% or more, among them 90% or more, among these 93% or more. The upper limit of this residual adhesion rate is 100%.
F1: After attaching the above adhesive tape to the release layer of the release film and heat-treating at 100 ° C. for 1 hour, the release film was peeled off, the remaining adhesive tape was attached to a stainless steel plate, and the tensile speed was 0.3 m. / min 180 ° peel force F0: The adhesive tape is attached as it is to a stainless steel plate, and the 180 ° peel force measured in the same manner as F1 This release film is thus applied to the adhesive layer. Low contamination can be obtained.

<Uses of this release film>
This release film has excellent releasability, solvent resistance even after long-term storage, and low contamination. can do.
Therefore, the present release film can be suitably used in the manufacture of liquid crystal display devices used as image display devices such as liquid crystal televisions, computer displays, mobile phones and digital cameras, and in the manufacture of ceramic capacitors.
If a specific example is given, an adhesive layer is laminated on the release layer of the release film to prepare a release film with an adhesive layer, and the adhesive layer is attached to a polarizing plate to form an adhesive layer. After manufacturing the polarizing plate with liquid crystal, the base film can be peeled off and the adhesive layer and the glass substrate of the liquid crystal cell can be bonded to each other when bonding to the liquid crystal cell.
It is also effective for producing a release film with an adhesive layer formed using an adhesive resin composition containing a solvent.

<<explanation of words>>
In general, "sheet" is defined in JIS as a thin, flat product whose thickness is small relative to its length and width. A thin flat product with an extremely small thickness and an arbitrarily limited maximum thickness, usually supplied in the form of a roll (Japanese Industrial Standard JIS K6900). However, the boundary between a sheet and a film is not clear, and there is no need to distinguish between the two in the present invention. “Film” shall be included even in cases where

In the present invention, when described as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, "X or more and Y or less" and "preferably larger than X" or "preferably Y It also includes the meaning of "less than".
In addition, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably greater than X" unless otherwise specified, and is described as "Y or less" (Y is an arbitrary number). If not otherwise specified, it also includes the meaning of "preferably smaller than Y".

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.
Measurement methods and evaluation methods used in the examples are as follows.

(1) Method for measuring intrinsic viscosity of polyester Accurately weigh 1 g of polyester from which components incompatible with polyester have been removed, add 100 ml of a mixed solvent of phenol/tetrachloroethane = 50/50 (mass ratio) to dissolve, Measured in °C.

(2) Measurement of average particle size (d50) The average particle size d50 and

(3) Method for measuring film thickness of release layer The surface of the release layer was dyed with RuO ₄ and embedded in epoxy resin. Then, a section prepared by the ultrathin section method was stained with RuO ₄ and the cross section of the release layer was measured using a transmission electron microscope (H-7650 manufactured by Hitachi High-Technologies Corporation, accelerating voltage 100 kV).

(4) Evaluation of peeling force of release film One side of a double-sided adhesive tape ("No. 502" manufactured by Nitto Denko Co., Ltd.) cut to a width of 5 cm was crimped once with a 2 kg rubber roller on the surface of the release layer of the sample film. Then, the peel force was measured after being left at room temperature for 1 hour. For the peel strength, "Ezgraph" manufactured by Shimadzu Corporation was used, and 180° peeling was performed at a tensile speed of 300 mm/min. This peel force is indicated in the table as "Initial".
Those having an "initial" peel force of 200 mN/cm or less are preferred.

(5) Evaluation of release force after heating of release film One side of a double-sided adhesive tape (“No. After reciprocating press-bonding, it was heated in an oven at 100° C. for 1 hour. After that, the peel force was measured after being left at room temperature for 1 hour. For the peel strength, "Ezgraph" manufactured by Shimadzu Corporation was used, and 180° peeling was performed at a tensile speed of 300 mm/min. The peel force is shown in the table as "after heating".

(6) Evaluation of peel strength after solvent treatment of release film An untreated polyester film is superimposed on the surface of the release layer of the sample film, and one week after the film is prepared, the untreated polyester film is peeled off, and toluene Bemcot (“M-3II” manufactured by Asahi Kasei Fibers Co., Ltd.) impregnated with 4 mL was attached to a rubbing tester (manufactured by Ohira Rika Kogyo Co., Ltd.), and the release layer surface of the sample film was reciprocated 10 times with an arm load of 680 g. After air-drying, one side of a double-sided adhesive tape (“No. 502” manufactured by Nitto Denko Co., Ltd.) cut to a width of 5 cm was pressed back and forth once with a 2 kg rubber roller, and the peel strength was measured after being left at room temperature for 1 hour. For the peel strength, "Ezgraph" manufactured by Shimadzu Corporation was used, and 180° peeling was performed at a tensile speed of 300 mm/min. The release force is shown in the table as "after solvent treatment".
Those having a peel strength of 300 mN/cm or less "after solvent treatment" are preferred.

(7) Release force evaluation after solvent treatment after one month of release film Storage for one month in an environment of 23 ° C. 50% RH with an untreated polyester film overlaid on the release layer surface of the sample film After that, using a release film obtained by peeling off the untreated polyester film, 180° peeling was performed in the same manner as the peeling force for "after solvent treatment". The table shows this release force as "after 1 month after solvent treatment".
Those having a peel strength of 800 mN/cm or less "one month after solvent treatment" are preferable.

(8) Evaluation of residual adhesion rate of release film Adhesive tape “No. 31B” (manufactured by Nitto Denko Corporation) was pressed back and forth once on the surface of the release layer with a 2 kg rubber roller, and heat-treated at 100 ° C. for 1 hour. did. Next, the pressure-bonded release film is peeled off, and the remaining adhesive tape "No. 31B" is used to measure the adhesive force F1 according to the method of JIS-C2107 (adhesive force to stainless steel plate, 180° peeling method). do. The percentage of F1 with respect to the adhesive force F0 when the adhesive tape "No. 31B" was directly attached and peeled off from the stainless steel plate was taken as the residual adhesive ratio.
A residual adhesion rate close to 100% is preferred.

Next, materials used in Examples and Comparative Examples will be described.

<Polyester (A)>
Polyethylene terephthalate homopolymer having an intrinsic viscosity of 0.63

<Polyester (B)>
A polyethylene terephthalate homopolymer having an intrinsic viscosity of 0.65 containing 0.2% by mass of silica particles having an average particle size of 2 μm

<Vinyl group-containing polydimethylsiloxane (IA)>
Aqueous dispersion of vinyl group-containing polydimethylsiloxane having a vinyl group content of 0.16 mmol/g (emulsifier: nonionic surfactant)

<Hydrogen group-containing polydimethylsiloxane (IIA)>
Aqueous dispersion of hydrogen group-containing polydimethylsiloxane having Si—H group content of 6.6 mmol/g (emulsifier: nonionic surfactant)

<Hydrogen group-containing polydimethylsiloxane (IIB)>
Aqueous dispersion of hydrogen group-containing polydimethylsiloxane having Si—H group content of 8.1 mmol/g (emulsifier: nonionic surfactant)

<Hydrogen group-containing polydimethylsiloxane (IIC)>
Aqueous dispersion of hydrogen group-containing polydimethylsiloxane having Si—H group content of 12.7 mmol/g (emulsifier: nonionic surfactant)

<Acryloyl group-containing compound (IIIA)>
A urethane (meth)acrylate formed from a polyhexamethylene carbonate diol unit having a molecular weight of 1100: a dimethylolpropanoic acid unit: a hydrogenated xylylene diisocyanate unit: a dipentaerythritol pentaacrylate unit = 11:7:40:42 (mol%) is mixed with 50 parts by mass of dipentaerythritol hexaacrylate, 27 parts by mass of dipentaerythritol hexaacrylate, and 23 parts by mass of trimethylolpropane triacrylate; dispersion

<Acryloyl group-containing compound (IIIB)>
Acryloyl group-introduced cresol novolak type epoxy resin (acryloyl group: cresol novolac type epoxy resin monomer = 1:1.1 (mol%)) and isophorone diisocyanate: terephthalic acid: isophthalic acid: ethylene glycol: diethylene glycol: dimethylol A core-shell structure obtained by mixing and dispersing a polyester-based urethane resin formed from propanoic acid = 12:19:18:21:25:5 (mol%) at a solid content mass ratio of 1.0:1.0 Water-dispersed composite resin (mass ratio of acryloyl group to composite resin: 14% by mass (solid content ratio)) with (acryloyl group-containing resin in core, urethane resin in shell)

<Acrylic resin (IVA)>
Aqueous dispersion of acrylic resin polymerized with the following composition Emulsion polymer of ethyl acrylate/n-butyl acrylate/methyl methacrylate/N-methylolacrylamide/acrylic acid = 65/21/10/2/2 (mass%) (emulsifier: anionic surfactant)

<Urethane resin (IVB)>
400 parts of polycarbonate polyol consisting of 1,6-hexanediol and diethyl carbonate and having a number average molecular weight of 2000, 10.4 parts of neopentyl glycol, 58.4 parts of isophorone diisocyanate, and 7.4 parts of dimethylolbutanoic acid. Aqueous dispersion of urethane resin obtained by neutralizing prepolymer with triethylamine and chain-extending with isophoronediamine

<Platinum group metal catalyst (V)>
Complexes of chloroplatinic acid with vinylsiloxanes

<Example 1>
A mixed raw material obtained by mixing polyesters (A) and (B) at a ratio of 90% by mass and 10% by mass, respectively, is used as a raw material for the outermost layer (surface layer), and only polyester (A) is used as a raw material for the intermediate layer. After each was supplied to the machine and melted at 285 ° C., it was placed on a cooling roll set at 40 ° C. in a layer configuration of 2 types and 3 layers (surface layer / intermediate layer / surface layer = 1: 8: 1 discharge rate). Co-extrusion was cooled and solidified to obtain an unstretched sheet. Next, after stretching 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the roll peripheral speed difference, a coating liquid having the composition shown in Table 1 below was applied to one side of this longitudinally stretched film, and led to a tenter. , stretched 4.3 times in the transverse direction at 110 ° C., heat-treated at 235 ° C., relaxed 2% in the transverse direction, and had a thickness of 50 μm with a release layer having a thickness (after drying) of 0.06 μm. A release film (sample) was obtained.

The obtained polyester film was evaluated, and the releasability after solvent treatment after one month was also good. The properties of this film are shown in Table 2 below.

<Examples 2 to 21>
A polyester film was obtained in the same manner as in Example 1, except that the composition of the coating agent in Example 1 was changed to that shown in Table 1.
As shown in Table 2, the obtained polyester film had good releasability and residual adhesiveness after one month of solvent treatment.

<Comparative Example 1>
A polyester film was obtained in the same manner as in Example 1, except that no coating layer was provided.
The obtained polyester film was evaluated, and the results are shown in Table 2, indicating that the releasability was poor.

<Comparative Examples 2 to 6>
A polyester film was obtained in the same manner as in Example 1, except that the composition of the coating agent in Example 1 was changed to that shown in Table 1.
The obtained polyester film was evaluated, and the results are as shown in Table 2. It was inferior in releasability after solvent treatment after one month, residual adhesion rate, initial peeling physical properties, and the like.

From the above Examples/Comparative Examples and various test results conducted by the inventors so far, the release layer laminated on the polyester film (substrate), in addition to the silicone compound, (meth) compound containing an acryloyl group By containing, even if the release layer comes into contact with the solvent, it was confirmed that the adhesion between the polyester film (substrate) and the release layer can be preferably maintained.

The release film of the present invention is a release film that has little deterioration of release properties due to solvents during processing of the adhesive layer even after long-term storage. can be suitably used as

Claims (15)

A release film comprising a release layer on at least one side of a polyester film, the release layer comprising a silicone compound and a compound containing a (meth)acryloyl group.
A release film, wherein the compound containing a (meth)acryloyl group is a combination of a urethane (meth)acrylate and a polyfunctional (meth)acrylate compound other than the urethane (meth)acrylate. However, the release film according to claim 1, except for one containing a photopolymerization initiator. A release film having a release layer on at least one side of a polyester film, and the release layer is formed from a release layer-forming composition containing a silicone compound and a compound containing a (meth)acryloyl group. A release film that is a layer consisting of
A release film, wherein the compound containing a (meth)acryloyl group is a combination of a urethane (meth)acrylate and a polyfunctional (meth)acrylate compound other than the urethane (meth)acrylate. The release film according to claim 3, wherein the release layer is a layer obtained by curing the release layer-forming composition by heat treatment. The release film according to any one of claims 1 to 4, wherein the urethane (meth)acrylate contains both a high molecular weight polyol and a low molecular weight polyol as polyols. The release film according to any one of claims 1 to 5, wherein the silicone compound is organopolysiloxane. The release film according to any one of claims 1 to 6, wherein the silicone compound contains vinyl group-containing polydimethylsiloxane. The release film according to any one of claims 1 to 7, wherein the silicone compound contains vinyl group-containing polydimethylsiloxane and hydrogen group-containing polydimethylsiloxane. The release film according to any one of claims 1 to 8, wherein the silicone compound is a Si—H group-containing silicone compound. A release film manufacturing method for forming a release layer by applying a release layer-forming composition containing a silicone compound and a compound containing a (meth)acryloyl group to at least one side of a polyester film,
A method for producing a release film, wherein the compound containing a (meth)acryloyl group is a combination of a urethane (meth)acrylate and a polyfunctional (meth)acrylate compound other than the urethane (meth)acrylate. The method for producing a release film according to claim 10, wherein the release layer-forming composition is applied and cured by heat treatment to form the release layer. 12. The method for producing a release film according to claim 10, wherein stretching is performed after forming a release layer in the process of producing the polyester film. 13. The method for producing a release film according to any one of claims 10 to 12, wherein after the release layer is formed, the release layer is heated to 180°C or higher. A pressure-sensitive adhesive sheet with a release film, comprising a structure in which a pressure-sensitive adhesive layer is laminated on the release layer of the release film according to any one of claims 1 to 9. A pressure-sensitive adhesive with a release film, characterized in that a pressure-sensitive adhesive composition containing a solvent is applied to the release layer of the release film according to any one of claims 1 to 9 to form the pressure-sensitive adhesive layer. Sheet manufacturing method.