JP2023002050A - Release film and film laminate - Google Patents

Abstract

To provide a release film, which has excellent releasability at the time of peeling the release film, via an adhesive layer, from an optical member (adherend) and the like such as a member and the like constituting a display panel and which also has excellent antistaticity and, especially, rub resistance.SOLUTION: Provided is a release film having, on at least one surface of a substrate film, a release layer formed of a resin composition comprising the following component (A), component (B), and component (C). Component (A):one or more selected from a polymer (a1) obtained by doping a polymer formed of thiophene or a thiophene derivative with another anionic compound and a polymer (a2) obtained by self-doping a polymer formed of thiophene or a thiophene derivative with an anionic group possessed by the polymer. Component (B): a release agent. Component (C): fluororesin particles.SELECTED DRAWING: None

Description

The present invention relates to release films and film laminates.

A release film having a release layer on at least one surface of a substrate film is used in various fields such as industrial materials, optical materials, electronic component materials, and battery packaging materials. For example, in the manufacturing process of display panels and the like, release films are used to protect adhesives used to bond panel constituent members together.

As the base film for the release film, polyethylene terephthalate (PET) film, which is a typical polyester film, especially biaxially oriented PET film, is widely used due to its excellent transparency, mechanical strength, heat resistance, flexibility, etc. It is
A common problem with polyester films is that they tend to generate static electricity and become electrified, which is a common problem with plastic films. sometimes.
As a result, not only problems due to adhesion and entanglement of foreign matter due to static electricity, but also serious problems such as damage to nearby electronic elements due to electrostatic interference and product defects may occur. Therefore, countermeasures against static electricity by means of equipment in the manufacturing process are not necessarily sufficient, and antistatic treatment of the release film itself is desired.

Therefore, for example, Patent Documents 1 and 2 propose a release film having an antistatic layer and a release layer in this order on the surface of the base film, and are said to have excellent releasability and excellent antistatic properties. be.

JP-A-2010-6079 JP 2014-151573 A

However, the release films as disclosed in Patent Documents 1 and 2 not only make the manufacturing process complicated because the number of layers to be laminated increases, but also increase potential problems between layers such as poor adhesion. Tend.
On the other hand, when a release film having antistatic properties and releasability is formed on the surface of the base film by a single-layer coating, the antistatic performance is reduced due to friction during the manufacturing process and inspection process. there was a case.

The problem to be solved by the present invention is that when the release film is peeled off from an optical member (adherend) such as a member constituting a display panel through an adhesive layer, it has excellent releasability and antistatic properties. Another object of the present invention is to provide a release film which is particularly excellent in abrasion resistance.

In view of the above-mentioned circumstances, the present inventors have made intensive studies and found that the above problems can be easily solved by using a release film provided with a release layer having a specific configuration. was completed. That is, the present invention has the following aspects.

[1] A release film having a release layer formed from a resin composition containing the following components (A), (B) and (C) on at least one surface of a base film.
Component (A): (a1) a polymer obtained by doping a compound comprising thiophene or a thiophene derivative with another anionic compound; One or more selected from coalescence Component (B): release agent Component (C): fluororesin particles [2] The release agent of component (B) is selected from the group of long-chain alkyl group-containing compounds and waxes The release film according to the above [1], which is one or more.
[3] The above [1] or [2], wherein the fluororesin particles of component (C) are one or more selected from the group consisting of hexafluoropropylene-tetrafluoroethylene copolymer and polytetrafluoroethylene. release film.
[4] The release film according to any one of [1] to [3] above, wherein the fluororesin particles of component (C) have an average particle size of 10 to 1000 nm.
[5] Any one of the above [1] to [4], wherein the content of the fluororesin particles of the component (C) is 0.1 to 20% by mass as a proportion of the total nonvolatile components in the resin composition. 1. The release film according to 1.
[6] The release film according to any one of [1] to [5] above, wherein the resin composition further contains a binder resin as component (D).
[7] The release film according to [6] above, wherein the binder resin of component (D) is one or more selected from the group consisting of polyurethane resins, polyester resins and acrylic resins.
[8] The resin composition further contains, as component (E), one or more selected from glycerin, polyglycerin, glycerin or alkylene oxide adducts to polyglycerin, sugar alcohols and sugar alcohol condensates. The release film according to any one of [1] to [7].

[9] The surface resistivity (R _x ) of the release layer, and the surface resistivity (R _Y ) of the release layer after 5 reciprocating friction treatments were performed on the surface of the release layer with a cupra nonwoven fabric under a load of 680 g. (R _Y /R _x ) is 4.0 or less, the release film according to any one of the above [1] to [8].
[10] Acrylic adhesive tape ("No. 31B" manufactured by Nitto Denko Corporation) was attached to the release layer and left at 23°C for 1 hour, and then under the conditions of 23°C and a tensile speed of 300 mm/min. The release film according to any one of [1] to [9] above, which has a measured 180° peeling force of 200 mN/cm or less.
[11] The release film according to any one of [1] to [10] above, wherein the base film is a polyester film.
[12] A film laminate in which the release film according to any one of [1] to [11] above is bonded to an optical member via an adhesive layer.
[13] The film laminate according to [12] above, wherein the optical member is a resin film or a glass substrate.
[14] The film laminate according to [13] above, wherein the resin film is selected from a polyester film, a polyimide film, and a cyclic polyolefin film.
[15] The film laminate according to [13] or [14] above, which is a laminated film in which a functional layer is provided on the surface of the resin film in contact with the adhesive layer.
[16] The film laminate according to [15] above, wherein the functional layer is another release layer.
[17] The film laminate according to [16] above, wherein the other release layer contains a curable silicone resin.
[18] The film laminate according to any one of [12] to [17] above, which has a total thickness of 200 μm or less.

According to the present invention, excellent releasability when peeling the release film from an optical member (adherend) such as a member constituting a display panel through an adhesive layer, and antistatic properties, especially friction resistance A release film with excellent properties is provided, and its industrial utility value is high.

An example of an embodiment of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below, and can be arbitrarily modified without departing from the gist of the present invention.
In this specification, the term "A to B" (A and B are arbitrary numbers) regarding the description of numerical values means "A or more and B or less" (when A < B) or "A or less than B " (when A>B) and "preferably greater than A" or "preferably less than B" (when A<B)) or "preferably greater than B" or "preferably less than A" It also includes the meaning of "smaller" (when A>B).
In addition, the expression "A or more" or "B or less" includes the meaning of "preferably larger than A" or "preferably less than B".
In the present invention, a combination of preferred aspects is a more preferred aspect.
In this specification, when the expression "(meth)acrylic acid" is used, it means one or both of "acrylic acid" and "methacrylic acid". Similarly, "(meth)acrylate" means one or both of "acrylate" and "methacrylate", and "(meth)acryloyl" means one or both of "acryloyl" and "methacryloyl".

<Release film>
Each member will be described in more detail below, but first, each member constituting the release film will be described in more detail.
[Base film]
The material of the base film constituting the release film is not particularly limited as long as it exhibits a film shape. For example, it may be made of paper, resin, metal, etc. Among these, it is preferably made of resin from the viewpoint of mechanical strength and flexibility.

Examples of base films made of resin include polyethylene, polypropylene, cycloolefin polymer (COP), polyester, polystyrene, acrylic resin, polycarbonate, polyurethane, triacetylcellulose (TAC), polyvinyl chloride, polyethersulfone, polyamide, and polyimide. , a resin film in which a polymer such as polyamideimide is formed into a film. A mixture of these materials (polymer blend) or a composite of constituent units (copolymer) may also be used as long as they can be formed into a film.

Among the substrate films exemplified above, polyester films are particularly preferable because of their excellent physical properties such as heat resistance, flatness, optical properties, and strength.
The polyester film may have a single layer structure or a multilayer structure. When the polyester film has a multi-layer structure, the polyester film may have a two-layer structure, a three-layer structure, or the like, or may have a multi-layer structure of four or more layers, provided that the gist of the present invention is not deviated. It is not particularly limited.
Moreover, the 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 more preferable from the viewpoint of the balance of mechanical properties, flatness, and thinning.

The polyester, which is the raw material of the polyester film, may be homopolyester or copolymer polyester. When it is made of homopolyester, it is preferably obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol.
Examples of aromatic dicarboxylic acids include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of aliphatic glycols include ethylene glycol, diethylene glycol and 1,4-cyclohexanedimethanol. Typical polyesters include polyethylene terephthalate and the like.
On the other hand, the dicarboxylic acid component of the copolymerized polyester includes one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, adipic acid, sebacic acid and oxycarboxylic acid. Glycol components include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexanedimethanol and neopentyl glycol.

The polyester polymerization catalyst is not particularly limited, and conventionally known compounds can be used, such as titanium compounds, germanium compounds, antimony compounds, manganese compounds, aluminum compounds, magnesium compounds and calcium compounds.

In order to suppress the precipitation amount of the oligomer component, the film may be produced using a polyester having a low content of the oligomer component as a raw material. As a method for producing a polyester having a low content of oligomer components, various known methods can be used.
Further, the polyester film may have a structure of three or more layers, and the outermost layer of the polyester film may be a layer using a polyester raw material having a low content of the oligomer component, thereby suppressing the precipitation amount of the oligomer component.
Moreover, the polyester may be obtained by further increasing the reaction temperature and subjecting it to melt polycondensation under reduced pressure after the esterification or transesterification reaction.

In order to improve the weather resistance of the film and prevent deterioration of adherends (for example, optical members such as members constituting display panels), the polyester film may contain an ultraviolet absorber. The ultraviolet absorber is a compound that absorbs ultraviolet rays and is not particularly limited as long as it can withstand the heat applied during the manufacturing process of the polyester film.

As the UV absorber, there are organic UV absorbers and inorganic UV absorbers, and organic UV absorbers are preferable from the viewpoint of transparency. The organic UV absorber is not particularly limited, and examples thereof include cyclic iminoester-based, benzotriazole-based, and benzophenone-based. From the viewpoint of durability, cyclic imino esters and benzotriazoles are more preferable.
It is also possible to use two or more types of ultraviolet absorbers in combination.

Particles can be blended into the polyester film for the main purpose of imparting slipperiness and preventing the occurrence of scratches in each step. The types of particles to be blended are not particularly limited as long as they are particles capable of imparting lubricity. Examples include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, Inorganic particles such as aluminum oxide and titanium oxide; and organic particles such as acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin and benzoguanamine resin. Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

The shape of the particles to be used is not particularly limited either, and any of spherical, lumpy, rod-like, flattened and the like may be used. Moreover, there are no particular restrictions on its hardness, specific gravity, color, and the like. Two or more types of these series of particles may be used in combination, if necessary.

Also, the average particle size of the particles used is usually 5 μm or less, preferably in the range of 0.01 to 3 μm. When it is 5 μm or less, the surface roughness of the film does not become too rough, and problems do not occur when various surface functional layers are formed in subsequent steps, which is preferable.
The average particle size can be obtained by observing the particles with a transmission electron microscope (TEM), measuring the particle sizes of 10 particles, and calculating the average value.

Furthermore, the content of particles in the polyester film is usually less than 5% by weight, preferably in the range of 0.0003-3% by weight. When no particles are contained, or when the content of particles is small, the transparency of the polyester film is high, but the slipperiness may be insufficient. Therefore, it may be necessary to take measures such as improving slipperiness by including particles in the release layer. If the particle content is less than 5% by mass, the transparency of the polyester film can be sufficiently ensured.
When particles are contained in the polyester film, it is preferable, for example, to provide a surface layer and an intermediate layer and to contain the particles in the surface layer. In this case, it is more preferable to have a multi-layer structure having a surface layer containing particles, an intermediate layer, and a surface layer containing particles in this order.

The method of adding particles to the polyester film is not particularly limited, and conventionally known methods can be employed. For example, in the case of a multi-layered polyester film, it can be added at any stage during the production of the polyester constituting each layer, but it is preferably added after the completion of the esterification or transesterification reaction.

In addition to the particles described above, conventionally known antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film, if necessary.

The thickness of the polyester film is not particularly limited as long as it can be formed as a film. It is in the range of 75 μm.

Next, production examples of the polyester film will be specifically described, but the following production examples are not limited at all. For example, when producing a biaxially stretched film, it is preferable to extrude the above-described dried pellets of the polyester raw material from a die using an extruder as a molten sheet, and cool and solidify with a cooling roll to obtain an unstretched sheet. In this case, it is preferable to increase the adhesion between the sheet and the rotating cooling drum in order to improve the flatness of the sheet, and the electrostatic application adhesion method and/or the liquid coating adhesion method are preferably employed.
The resulting unstretched sheet is then biaxially stretched. In that case, first, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120° C., preferably 80 to 110° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the film is stretched in a direction perpendicular to the stretching direction of the first stage. In this case, the stretching temperature is usually 70 to 170° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. be.
Subsequently, heat treatment is carried out at a temperature of usually 180 to 270° C. under tension or under relaxation of 30% or less to obtain a biaxially stretched film. In the above stretching, a method of stretching in one direction in two or more stages can also be employed. In that case, it is preferable to carry out so that the stretching ratios in the two directions finally fall within the above ranges.

A simultaneous biaxial stretching method can also be employed in the production of the polyester film. The simultaneous biaxial stretching method is a method of simultaneously stretching and orienting the unstretched sheet in the machine direction and the width direction while the temperature is controlled at usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is is preferably 4 to 50 times, more preferably 7 to 35 times, still more preferably 10 to 25 times in terms of area magnification.
Subsequently, heat treatment is performed at a temperature of usually 170 to 250° C. under tension or under relaxation of 30% or less to obtain a stretched and oriented film. Conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be used for the simultaneous biaxial stretching apparatus that employs the above-described stretching methods.

[Release layer]
The release film of the present invention has a release layer formed from a resin composition containing the following components (A), (B) and (C) on at least one surface of the base film.
Component (A): (a1) a polymer obtained by doping a compound comprising thiophene or a thiophene derivative with another anionic compound; One or more selected from coalescence Component (B): release agent Component (C): fluororesin particles

When producing a film with high transparency, i.e., low haze, the amount of particles that can be added to the base film is limited. In particular, silica particles are often added. On the other hand, in the resin composition for forming the release layer of the release film of the present invention, when silica particles are contained, the friction resistance of the release layer formed is rather reduced compared to when it is not contained. However, when the fluororesin particles as the component (C) are contained, the friction resistance of the formed release layer is improved. Although the details of the reason for this are not clear, it is believed that the self-lubricating property of the fluororesin particles contributes to this.
The term "rubbing resistance" used herein is an evaluation based on changes in surface resistivity measured by the method described in Examples below.

(Component (A))
The component (A) used in the present invention includes (a1) a polymer obtained by doping a compound comprising thiophene or a thiophene derivative with another anionic compound and (a2) an anionic group in a compound comprising thiophene or a thiophene derivative. It is one or more selected from self-doped polymers.
Component (A) includes, for example, those obtained by polymerizing a compound of the following formula (1) or (2) in the presence of a polyanion.
The polymer (a1) and the polymer (a2) may be used together.

In the above formula (1), R ¹ and R ² each independently represent hydrogen or an aliphatic hydrocarbon group, alicyclic hydrocarbon group or aromatic hydrocarbon group having 1 to 20 carbon atoms.

In the above formula (2), n represents an integer of 1-4.

Examples of polyanions used in polymerization include poly(meth)acrylic acid, polymaleic acid, polystyrenesulfonic acid, polyvinylsulfonic acid and the like. As a method for producing such a polymer, for example, the method disclosed in JP-A-7-90060 can be employed.

In the present invention, the compound of formula (2) wherein n is 2 and polystyrene sulfonic acid is used as the polyanion is preferably used.

Moreover, when these polyanions are acidic, they may be partially or wholly neutralized. Ammonia, organic amines, and alkali metal hydroxides are preferable as the base used for neutralization.

The content of component (A) in the resin composition is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and still more preferably as a proportion of the total non-volatile components in the resin composition. is 1 to 10% by mass. When the content of component (A) is equal to or less than the upper limit, the strength and transparency of the release layer are good. On the other hand, when the content of component (A) is at least the lower limit, sufficient antistatic properties can be obtained.

(Component (B))
Component (B) used in the present invention is a release agent. From the viewpoint of improving releasability, it is preferable to use one or more compounds selected from the group consisting of long-chain alkyl group-containing compounds and waxes as component (B).

((long-chain alkyl group-containing compound))
A long-chain alkyl group-containing compound is a compound having a linear or branched alkyl group usually having 6 or more carbon atoms, preferably 8 or more carbon atoms, more preferably 12 or more carbon atoms.
Examples of alkyl groups include hexyl group, octyl group, decyl group, lauryl group, octadecyl group, and behenyl group.
Examples of compounds having a long-chain alkyl group include various long-chain alkyl-group-containing polymer compounds, long-chain alkyl-group-containing ester compounds, long-chain alkyl-group-containing amide compounds, and long-chain alkyl-group-containing ether compounds. . Considering heat resistance and stain resistance, it is preferably a polymer compound containing a long-chain alkyl group, and from the viewpoint of being able to effectively impart releasability, it should be a polymer compound having a long-chain alkyl group on the side chain. is more preferred.

A polymer compound having a long-chain alkyl group in a side chain can be obtained by reacting a polymer having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the reactive groups include hydroxyl groups, amino groups, carboxyl groups, acid anhydrides, and the like. Examples of polymers having these reactive groups include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, reactive group-containing polyester resins, and reactive group-containing poly(meth)acrylic resins. Among these, polyvinyl alcohol is preferable in consideration of releasability and ease of handling.

Examples of compounds having an alkyl group capable of reacting with the reactive group include isocyanates containing long-chain alkyl groups such as hexyl isocyanate, octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate, and behenyl isocyanate; hexanoyl chloride, octa long-chain alkyl group-containing acid chlorides such as noyl chloride, decanoyl chloride, lauroyl chloride, octadecanoyl chloride and behenoyl chloride; long-chain alkyl group-containing amines, long-chain alkyl group-containing alcohols, and the like. Among these, long-chain alkyl group-containing isocyanates are preferred, and octadecyl isocyanate is particularly preferred, in consideration of releasability and ease of handling.

Polymer compounds having long-chain alkyl groups in side chains can also be obtained by polymerizing long-chain alkyl (meth)acrylates or by copolymerizing long-chain alkyl (meth)acrylates with other vinyl group-containing monomers. . Examples of long-chain alkyl (meth)acrylates include hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, and behenyl (meth)acrylate. be done.

((wax))
Examples of waxes include natural waxes, synthetic waxes, waxes containing these waxes, and the like.

Natural waxes include vegetable waxes, animal waxes, mineral waxes, petroleum waxes, and the like.
Plant waxes include candelilla wax, carnauba wax, rice wax, Japan wax, jojoba oil and the like. Animal waxes include beeswax, lanolin, whale wax and the like. Mineral waxes include montan wax, ozokerite, and ceresin. Petroleum wax includes paraffin wax, microcrystalline wax, petrolatum, and the like.

Synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, fatty acid amides, amines, imides, ester waxes, ketones and the like.
Synthetic hydrocarbons include Fischer-Tropsch wax (Sasol wax), polyethylene wax, oxidized polyethylene wax, oxidized polypropylene wax, and the like. It also includes low-molecular-weight polymers (number-average molecular weight of 500 to 20,000), specifically polypropylene, ethylene-acrylic acid copolymer, polyethylene glycol, polypropylene glycol, block or graft combination of polyethylene glycol and polypropylene glycol, and the like. is mentioned.
Modified waxes include montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives and the like. The term "derivative" as used herein refers to a compound obtained by purification, oxidation, esterification, saponification, or a combination thereof.
Hydrogenated waxes include hydrogenated castor oil, hydrogenated castor oil derivatives and the like.

Among these waxes, synthetic waxes are preferable, synthetic hydrocarbons are more preferable, and oxidized polyethylene waxes and oxidized polypropylene waxes are even more preferable, from the viewpoint of excellent release performance and easy availability.

The content of component (B) in the resin composition is preferably 1 to 80% by mass, more preferably 5 to 60% by mass, and still more preferably 10 to 50% as a proportion of the total nonvolatile components in the resin composition. It is in the range of % by mass. When the content of the component (B) is equal to or less than the upper limit, the strength of the release layer is good. On the other hand, when the content of the component (B) is at least the lower limit, the release property of the release film of the present invention becomes good.

(Component (C))
Component (C) used in the present invention is fluororesin particles. The fluororesin particles refer to fluororesins having a particulate form in a dispersing solvent such as water or alcohol at 25°C.
By containing fluororesin particles, the resin composition according to the present invention not only achieves compatibility between releasability and antistatic properties, but is particularly excellent in abrasion resistance.

Examples of fluororesin particles include polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer. polymers, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) and hexafluoropropylene-tetrafluoroethylene copolymer (FEP). Among these, FEP and PTFE are preferred from the viewpoint of versatility, and FEP is more preferred.

The average particle diameter of the fluororesin particles measured by dynamic light scattering in the dispersion solvent is preferably 10 to 1000 nm, more preferably 20 to 500 nm, and even more preferably 50 to 300 nm. If the average particle size is within such a range, good coating appearance and improvement in the strength of the release layer can be expected.
Commercial products can be used as such fluororesin particles, and examples thereof include "Neoflon FEP ND-110", "Polyflon PTFE D-210C" and "Neoflon PFA AD-2CRER" manufactured by Daikin Industries, Ltd.

The average particle size of the fluororesin particles is preferably 0.1 to 10 times the film thickness of the release layer, more preferably 0.3 to 5 times, still more preferably 0.5 to 3 times. Within this range, the ease of handling of the release film and the strength of the release layer are improved.

The content of component (C) in the resin composition is preferably 0.1 to 20% by mass, more preferably 0.3 to 10% by mass, and still more preferably as a proportion of the total non-volatile components in the resin composition. is in the range of 0.5 to 5% by mass. When the content of component (C) is at most the upper limit, good coating appearance and strength of the release layer are improved.
On the other hand, when the content of component (C) is at least the lower limit, the film handleability is improved and the strength of the release layer is improved.

(Component (D))
The resin composition forming the release layer according to the present invention preferably contains a binder resin as component (D). More preferably, the binder resin is one or more selected from the group consisting of polyurethane resins, polyester resins and acrylic resins.
When the release layer contains one or more selected from the group consisting of polyurethane resins, polyester resins and acrylic resins, the release layer has improved film formability, transparency, releasability, and the like.

((polyurethane resin))
A urethane resin is a polymer compound having a urethane bond in its molecule, and is preferably water-dispersible or water-soluble. In the present invention, these may be used alone or in combination of two or more.

In order to impart water dispersibility or water solubility, it is common and preferred to introduce a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a sulfonyl group, a phosphoric acid group or an ether group into the urethane resin. Among the hydrophilic groups, a carboxyl group or a sulfonic acid group is particularly preferable from the viewpoint of physical properties of the release layer and adhesion between the release layer and the substrate film.

One of the methods for producing urethane resin is by reaction between a hydroxyl group-containing compound and isocyanate. As the hydroxyl group-containing compound used as a raw material, polyols are preferably used, and examples thereof include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

Polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol and the like.

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.).

Examples of polycarbonate-based polyols include polycarbonate diols obtained by dealcoholization of polyhydric alcohols and dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, etc., such as poly(1,6-hexylene) carbonate, poly( 3-methyl-1,5-pentylene)carbonate and the like.

Among these, polyester polyols are preferred.

Polyisocyanate compounds used to obtain urethane resins include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate; - Aliphatic diisocyanates having aromatic rings such as tetramethylxylylene diisocyanate; aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate and hexamethylene diisocyanate; Alicyclic diisocyanates such as methane diisocyanate and isopropylidene dicyclohexyl diisocyanate are exemplified. These may be used alone or in combination of multiple types.

A chain extender may be used when synthesizing the urethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with isocyanate groups. Alternatively, a chain extender having two amino groups can be mainly used.

Examples of chain extenders having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol; aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene; esters such as neopentyl glycol hydroxypivalate. Glycols such as glycol can be mentioned.

Examples of chain extenders having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine and diphenylmethanediamine; ethylenediamine, propanediamine, hexanediamine, 2,2-dimethyl-1,3-propanediamine; , 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine Alicyclic diamines such as 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, 1,4-diaminocyclohexane, 1,3-bisaminomethylcyclohexane, etc. is mentioned.

((polyester resin))
Examples of polyester resins include those composed of polyvalent carboxylic acids and polyvalent hydroxy compounds as shown below as main constituents.
That is, polyvalent carboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6- Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid , succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salts and ester-forming derivatives thereof can be used. Polyvalent hydroxy compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neo Pentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylol Propionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate, and the like can be used. One or more of these compounds may be appropriately selected, and a polyester resin may be synthesized by a conventional polycondensation reaction.

Further, a product obtained by copolymerizing sulfoisophthalic acid as a part of the above polyvalent carboxylic acid, introducing a sulfonic acid group into the polyester skeleton, and neutralizing to make it hydrophilic is preferably used. The amount to be copolymerized is generally 1 to 10 mol %, preferably 2 to 8 mol %, based on the total polycarboxylic acid. By introducing an appropriate amount of sulfonic acid groups, the water dispersion stability can be further improved.

((acrylic resin))
An acrylic resin is a polymer composed of polymerizable monomers including acrylic and methacrylic monomers. These may be homopolymers, copolymers, or copolymers with polymerizable monomers other than acrylic and methacrylic monomers.
Copolymers of these polymers with other polymers (eg, polyester, polyurethane, etc.) are also included. Examples are block copolymers and graft copolymers. That is, the acrylic resin may be an acrylic-modified polyester resin or an acrylic-modified polyurethane resin.
Alternatively, a polymer obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyester solution or a polyester dispersion (sometimes a mixture of polymers) is also included. Also included are polymers obtained by polymerizing polymerizable monomers having carbon-carbon double bonds in polyurethane solutions and polyurethane dispersions (mixtures of polymers in some cases). Polymers (polymer mixtures in some cases) obtained by polymerizing polymerizable monomers having carbon-carbon double bonds in other polymer solutions or dispersions are also included.
Moreover, in order to further improve the adhesion of the release layer to the substrate film, it is possible to contain a hydroxy group and an amino group.

The polymerizable monomer having a carbon-carbon double bond is not particularly limited, but particularly representative compounds include, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citracone Various carboxyl group-containing monomers such as acids, and salts thereof; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, monobutylhydroxyfumarate, monobutyl various hydroxyl group-containing monomers such as hydroxyitaconate; various alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate acrylic acid esters; various nitrogen-containing compounds such as (meth)acrylamide, diacetoneacrylamide, or (meth)acrylonitrile; hydroxyl group-containing nitrogen-containing compounds such as N-methylol (meth)acrylamide; styrene, α-methylstyrene, Various styrene derivatives such as divinylbenzene and vinyltoluene; various vinyl esters such as vinyl propionate; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane; system monomers; various vinyl halides such as vinyl chloride and vinylidene chloride; and various conjugated dienes such as butadiene.

Among the above acrylic resins, polymers obtained by polymerizing polymerizable monomers including acrylic and methacrylic monomers are preferable, and it is more preferable that the polymerizable monomers contain alkyl (meth)acrylic acid esters.
Further, the resin composition is preferably diluted with a solvent to form a coating liquid as described later, and the solvent preferably contains water as the main solvent (50% by mass or more). In other words, the polymerizable monomer preferably has a hydrophilic group such as a hydroxyl group or a carboxyl group from the viewpoint of facilitating the dissolution or dispersion of the component (D) when the coating liquid is water-based.
Therefore, the acrylic resin is also preferably a polymer obtained by polymerizing a polymerizable monomer containing a hydrophilic group-containing monomer such as an alkyl (meth)acrylic acid ester and a hydroxyl group-containing monomer or a carboxyl group-containing monomer.
The acrylic resin may also be an emulsion polymer obtained by polymerizing a polymerizable monomer in the presence of a surfactant, for example.

As component (D), polyurethane resins and polyester resins are preferable, and polyester resins are more preferable. Polyester having a naphthalene skeleton is more preferable from the viewpoint of the strength of the release layer.

When the resin composition further contains component (D), its content is preferably 1 to 60% by mass, more preferably 2 to 30% by mass, and more preferably 2 to 30% by mass, as a proportion of the total nonvolatile components in the resin composition. It is preferably in the range of 2 to 10% by mass. When the content of the component (D) is at most the upper limit, sufficient releasability and antistatic properties are obtained.
On the other hand, when the content of component (D) is at least the lower limit, the strength of the release layer is sufficient.

(Component (E))
The resin composition for forming the release layer according to the present invention contains glycerin as a component (E) for the purpose of achieving both high antistatic properties and high transparency without impairing the release properties. , polyglycerin, the glycerin or an alkylene oxide adduct to the polyglycerin, a sugar alcohol, and a sugar alcohol condensate.

((glycerin, polyglycerin, said glycerin or an alkylene oxide adduct to said polyglycerin))
Examples thereof include one compound selected from (b1) glycerin or polyglycerin represented by the following formula (3) and (b2) an alkylene oxide adduct to the glycerin or the polyglycerin (b1), or a derivative thereof. .

n in the above formula (3) is preferably in the range of 2-10, more preferably in the range of 2-6. Within this range, the durability of the release layer is further improved, and the antistatic property is also improved.

The alkylene oxide adduct to polyglycerin has a structure obtained by addition polymerization of alkylene oxide to the hydroxyl group of polyglycerin represented by the general formula (3).

Here, the structure of the alkylene oxide to be added may be different for each hydroxyl group of the polyglycerin skeleton. Moreover, it is sufficient that at least one hydroxyl group in the molecule is added, and not all hydroxyl groups need to be added with an alkylene oxide or a derivative thereof.

A preferred alkylene oxide to be added to polyglycerin is ethylene oxide or propylene oxide. If the alkylene chain of the alkylene oxide is too long, the hydrophobicity of the alkylene oxide becomes strong, the dispersibility in the coating liquid deteriorates, and the antistatic properties and transparency of the release layer tend to deteriorate. From this point of view, ethylene oxide is more preferable.
The number of additions is preferably in the range of 200 to 2,000, more preferably in the range of 250 to 1,000, even more preferably in the range of 300 to 800, in terms of the number average molecular weight of the final compound.

The polyglycerin or the alkylene oxide adduct to polyglycerin may be used singly or in combination of two or more.

((sugar alcohol))
Sugar alcohol refers to chain polyhydric alcohols such as aldoses and ketoses in which carbonyl groups are reduced, or cyclic polyhydric alcohols such as cyclitol. Specific examples include sugar alcohols having 4 carbon atoms such as erythritol and threitol obtained by reducing monosaccharides; sugar alcohols having 5 carbon atoms such as ribitol, arabinitol and xylitol; Examples include chain sugar alcohols such as sugar alcohols having 6 carbon atoms such as lactitol. Further, cyclic sugar alcohols represented by cyclitols such as inositol are included. Disaccharide alcohols such as maltitol, lactitol and isomaltulose reduced products obtained by reducing disaccharides can also be exemplified.
In addition, when the said sugar-alcohol has a stereoisomer, all those stereoisomers are included. Moreover, the sugar alcohols may be used alone, or two or more of them may be used in combination.

The sugar alcohol is preferably a sugar alcohol having 4 to 12 carbon atoms, more preferably a sugar alcohol having 4 to 6 carbon atoms, from the viewpoint of achieving both high antistatic property and high transparency without impairing releasability. Sugar alcohols having 6 carbon atoms are more preferred, and particularly preferred. A chain sugar alcohol is preferred. From the above point of view, it is preferable to use sorbitol among the above sugar alcohols.

((sugar alcohol condensate))
Sugar alcohol condensates formally refer to compounds in the form of intramolecular and/or intermolecular dehydration condensation of hydroxyl groups of sugar alcohols, exemplified by sorbitan and isosorbide.

When the resin composition further contains component (E), its content is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, and more preferably 20 to 90% by mass, as a proportion of the total nonvolatile components in the resin composition. It is preferably in the range of 30 to 80% by mass. When the content of component (E) is equal to or less than the upper limit, the release layer has sufficient water resistance.
On the other hand, when the content of component (E) is at least the lower limit, a uniform release layer having sufficient conductivity, transparency and film-forming properties can be obtained.

(Component (F))
The resin composition forming the release layer according to the present invention may contain a cross-linking agent as component (F) for the purpose of improving the durability of the release layer.
As the cross-linking agent, various known cross-linking agents can be used, and examples thereof include melamine compounds, epoxy compounds, carbodiimide compounds, oxazoline compounds, isocyanate compounds, silane coupling compounds and the like. Among these, melamine compounds, epoxy compounds, isocyanate compounds, and carbodiimide compounds are preferable from the viewpoint of suppressing deterioration of antistatic properties after exposure to air, and melamine compounds and epoxy compounds are more preferable from the viewpoint of the strength of the release layer. . These may be used alone, or two or more of them may be used in combination.

((melamine compound))
A melamine compound is a compound having a melamine skeleton in the compound, and examples thereof include alkylolated melamine derivatives, compounds obtained by reacting alkylolated melamine derivatives with alcohol to partially or completely etherify them, and mixtures thereof. can be used. Methanol, ethanol, isopropanol, n-butanol, isobutanol and the like are preferably used as alcohols for etherification.
Moreover, the melamine compound may be either a monomer or a polymer of dimers or higher, or a mixture thereof. Further, melamine may be partially co-condensed with urea or the like, and a catalyst may be used to increase the reactivity of the melamine compound.

((epoxy compound))
Epoxy compounds are compounds having an epoxy group in the molecule, and include condensates with hydroxyl groups and amino groups such as epichlorohydrin, ethylene glycol, polyethylene glycol, glycerin, polyglycerin and bisphenol A, and polyepoxy compounds. , diepoxy compounds, monoepoxy compounds and glycidylamine compounds.
Examples of polyepoxy compounds include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether and trimethylolpropane poly glycidyl ether and the like.
Examples of diepoxy compounds include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcinol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether. Ether and polytetramethylene glycol diglycidyl ether and the like.
Examples of monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether and phenyl glycidyl ether, and examples of glycidylamine compounds include N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3 -Bis(N,N-diglycidylamino)cyclohexane and the like. From the viewpoint of improving the adhesion of the release layer to the base film, a polyether-based epoxy compound is preferred.
As for the amount of epoxy groups, a polyepoxy compound having a polyfunctionality of 3 or more is preferable to a bifunctional one.

((carbodiimide compound))
A carbodiimide compound is a compound having a carbodiimide structure, and is a compound having one or more carbodiimide structures in the molecule. A polycarbodiimide compound having two or more carbodiimide structures in is more preferred.

A carbodiimide compound can be synthesized by a conventionally known technique, and generally a condensation reaction of a diisocyanate compound is used. The diisocyanate compound is not particularly limited, and both aromatic and aliphatic compounds can be used. Specifically, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate and dicyclohexylmethane 4,4'-diisocyanate.

The content of the carbodiimide group contained in the carbodiimide compound is usually 100 to 1000, preferably 250 to 800, more preferably 300 to 300, in terms of carbodiimide equivalent (weight [g] of the carbodiimide compound to give 1 mol of carbodiimide group). 700 range. By using within the above range, the durability of the release layer is improved.

Furthermore, in order to improve the water solubility and water dispersibility of the polycarbodiimide compound, a surfactant may be added, polyalkylene oxide, quaternary ammonium salt of dialkylamino alcohol, and Hydrophilic monomers such as hydroxyalkylsulfonates may be added and used.

((oxazoline compound))
An oxazoline compound is a compound having an oxazoline group in the molecule, and a polymer containing an oxazoline group is particularly preferable, and can be synthesized by polymerization of an addition polymerizable oxazoline group-containing monomer alone or with another monomer. Addition polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like can be mentioned, and one or a mixture of two or more thereof can be used. Among these, 2-isopropenyl-2-oxazoline is suitable because it is easily available industrially. Other monomers are not limited as long as they are copolymerizable with addition-polymerizable oxazoline group-containing monomers. , n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group and cyclohexyl group); acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, Unsaturated carboxylic acids such as styrenesulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); Unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth)acrylamide, N-alkyl (Meth)acrylamide and N,N-dialkyl(meth)acrylamide (as alkyl groups, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; vinyl chloride and vinylidene chloride halogen-containing α,β-unsaturated monomers such as; α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene; be able to.
Also, the oxazoline compound may have a polyalkylene oxide chain such as a polyethylene oxide chain, and for example, a (meth)acrylate having a polyalkylene oxide chain may be used as another monomer.
From the viewpoint of improving the adhesion of the release layer to the base film, the oxazoline group content of the oxazoline compound is preferably 0.5 to 10 mmol/g, more preferably 1 to 9 mmol/g, and still more preferably 3 to 8 mmol/g. , particularly preferably in the range of 4 to 6 mmol/g.

((isocyanate compound))
An isocyanate 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; aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate and hexamethylene diisocyanate; Alicyclic isocyanate etc. are illustrated.
Polymers and derivatives of these isocyanates such as buret products, isocyanurate products, uretdione products and carbodiimide modified products are also included. These may be used alone or in combination of multiple types. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferable than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.

When used in the form of blocked isocyanate, blocking agents include, for example, bisulfites; phenolic compounds such as phenol, cresol and ethylphenol; alcoholic compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol and ethanol. Compounds; active methylene compounds such as methyl isobutanoylacetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate and acetylacetone; mercaptan compounds such as butyl mercaptan and dodecyl mercaptan; ε-caprolactam, δ-valerolactam, etc. amine compounds such as diphenylaniline, aniline and ethyleneimine; acid amide compounds of acetanilide and acetic acid amide; . These may be used alone or in combination of two or more.

Also, the isocyanate compound may be used alone, or may be used as a mixture or combination with various polymers. From the viewpoint of improving the dispersibility and crosslinkability of the isocyanate compound, it is preferable to use a mixture or combination with a polyester resin or a urethane resin.

((silane coupling compound))
A silane coupling compound is an organosilicon compound having an organic functional group and a hydrolyzable group such as an alkoxy group in one molecule. For example, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4- epoxy group-containing compounds such as ethyltrimethoxysilane; vinyl group-containing compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; styryl group-containing compounds such as p-styryltrimethoxysilane and p-styryltriethoxysilane; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, etc. (Meth) acrylic group-containing compounds; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)- 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N Amino group-containing compounds such as -(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane; tris(trimethoxysilylpropyl) Isocyanurate, isocyanurate group-containing compounds such as tris(triethoxysilylpropyl) isocyanurate; and mercapto group-containing compounds such as ethoxysilane.

When the resin composition further contains component (F), its content is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass as a proportion of the total non-volatile components in the resin composition. % by mass or less. When the component (F) is within the above range, the durability of the release layer is improved.

(Component (G))
The resin composition forming the release layer according to the present invention preferably contains a surfactant as component (G) in order to improve coatability onto the substrate film. As the surfactant, from the viewpoint of low foaming properties and not impairing the antistatic property of the release layer obtained, a nonion having one selected from polyalkylene oxide, polyglycerin, and derivatives thereof in its structure. surfactants are more preferred, nonionic surfactants containing polyalkylene oxide are more preferred, and nonionic surfactants containing polyethylene oxide are particularly preferred.

Furthermore, as the surfactant, those having a branched alkyl group-substituted acetylene structure or a fluoroalkyl group in the hydrophobic part are more preferable.
Examples of surfactants having a branched alkyl group-substituted acetylene structure in the hydrophobic portion include nonionic surfactants having a structure having polyethylene oxide in the side chain, as shown in the following formula (4).

m and n in the above formula (4) are positive numbers indicating the number of moles of ethylene oxide added.
In the above formula (4), the average of m+n is preferably 1.3 or more and 30 or less, more preferably 2 or more and 20 or less, and still more preferably 4 or more and 10 or less.

Moreover, surfactants may be used alone, or two or more of them may be used in combination.

When the resin composition further contains component (G), its content is preferably 0.1 to 20% by mass, more preferably 0.5 to 15, as a proportion of the total nonvolatile components in the resin composition. % by mass, more preferably in the range of 2 to 10% by mass. When the component (G) is within the above range, good coatability is obtained, the transparency of the release layer is maintained, and the durability of the release layer is improved.

(Other ingredients)
In addition to the above components, additives such as reaction modifiers and adhesion enhancers may be added as appropriate within a range that does not impair the gist of the present invention.

(solvent)
The resin composition according to the present invention contains the above components (A) to (C), optionally added components (D) to (G), and other components, and may be diluted with a solvent to form a coating liquid. preferable. That is, it is preferable to apply the liquid coating liquid to the substrate film, and if necessary, dry and cure the release layer to form the release layer. The above components (A) to (C), optionally added components (D) to (G), and other components constituting the resin composition may be dissolved in a solvent, but may be dispersed in the solvent. You may let
When used as a coating liquid, the concentration of all non-volatile components in the resin composition in the coating liquid is preferably 0.1 to 50% by mass. If it is 0.1% by mass or more, a release layer having a desired thickness can be efficiently formed. On the other hand, when it is 50% by mass or less, it is easy to dissolve or disperse in the solvent, and coating is easy. From the above viewpoints, the concentration of all non-volatile components in the resin composition in the coating liquid is more preferably 0.5 to 30% by mass, more preferably 1 to 15% by mass.

The solvent is not particularly limited, and both water and organic solvents can be used. From the viewpoint of environmental protection, it is preferable to use water as the main solvent (50% by mass or more). That is, it is preferable to use the resin composition according to the present invention as an aqueous coating liquid for forming the release layer. The water content is preferably 60% by mass or more, more preferably 70% by mass or more. The aqueous coating liquid may contain a small amount of organic solvent. The specific amount of the organic solvent should be less than water on a mass basis, for example less than 30% by mass, preferably less than 20% by mass, more preferably less than 10% by mass in the solvent.
Organic solvents used in combination with water include alcohols such as ethanol, isopropanol, ethylene glycol and glycerin; ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether and tetrahydrofuran; ketones such as acetone and methyl ethyl ketone; ethyl acetate. and amines such as dimethylethanolamine. These can be used singly or in combination. By appropriately selecting and including these organic solvents in the aqueous coating liquid as necessary, the stability and coatability of the coating liquid can sometimes be improved.

When only an organic solvent is used as the solvent, the organic solvent includes 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 and isobutyl methyl ketone; alcohols such as ethanol and 2-propanol; ethers such as diisopropyl ether and dibutyl ether. These may be used singly or in combination of two or more in consideration of solubility, coatability, boiling point, and the like.

It can be assumed that unreacted substances such as the above components (A) to (C), compounds after reaction, or a mixture thereof are present in the release layer.

(Method for producing release film (method for forming release layer))
A method for forming a release layer according to the present invention will be described below.
The method for forming the release layer is not particularly limited, and conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, and curtain coating can be used.
In-line coating and off-line coating are methods for forming the release layer. Drying and curing conditions are not particularly limited. For example, when a release layer is provided by offline coating, the temperature is usually 80 to 200° C. for 3 to 40 seconds, preferably 140 to 180° C. for 3 to 40 seconds. As a guideline, heat treatment is recommended. On the other hand, when the release layer is provided by in-line coating, it is generally preferable to perform heat treatment at 70 to 280° C. for 3 to 200 seconds.

In the present invention, the release layer is preferably formed by in-line coating, which treats the film surface during the film-forming process of the polyester film.
In-line coating is a method of coating in the process of polyester film production, specifically, a method of coating at any stage from melt extrusion of polyester to stretching, heat setting and winding. Usually, it is coated on an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, or a film after heat setting and before winding up.
Although it is not limited to the following, for example, in sequential biaxial stretching, a method in which a uniaxially stretched film stretched in the longitudinal direction (machine direction) is coated and then stretched in the transverse direction is excellent. According to such a method, film formation and release layer formation can be performed at the same time, which is advantageous in terms of manufacturing cost. In addition, since stretching is performed after coating, the thickness of the release layer can be changed by the stretching ratio. Also, thin film coating can be performed more easily compared to off-line coating films.
Further, by providing a 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 performed at 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 can be adhered more firmly. can. Furthermore, a strong release layer can be formed, and performance such as resistance to migration to various functional layers that can be formed on the release layer and resistance to moist heat can be improved.

Further, 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 constituting the laminated polyester film of the present invention may be previously subjected to surface treatment such as corona treatment or plasma treatment.

The non-volatile component coating amount of the release layer is preferably 1 to 300 mg/m ² , more preferably 5 to 150 mg/m ² , still more preferably 10 to 75 mg/m ² , particularly preferably 20 to 50 mg/m ² . is in the range of If the coating amount of the release layer is within the above range, it is possible to ensure appropriate releasability from the pressure-sensitive adhesive layer.

The total thickness of the release film of the present invention is preferably 200 µm or less, more preferably 5 µm or more and 125 µm or less, even more preferably 8 µm or more and 100 µm or less, and 12 µm or more and 75 µm or less, from the viewpoint of handleability. The following are particularly preferred.

(Physical properties of release film)
The haze of the release film of the present invention is preferably 10% or less, more preferably 5% or less, still more preferably 2.0% or less, and 1.0% or less. Especially preferred. Within the above range, it becomes easy to perform inspections while the release film of the present invention is attached in manufacturing and processing steps using the release film of the present invention.

The peel strength of the release film of the present invention to the release layer and the acrylic pressure-sensitive adhesive tape ("No. 31B" manufactured by Nitto Denko Corporation) can be evaluated by the measurement method described in Examples below.
The release force evaluated in this way can be easily adjusted by the release agent content. When light peeling is desired, it can be said that good peelability is obtained at 500 mN/cm or less, but 200 mN/cm or less is preferable, and 110 mN/cm or less is more preferable.
The lower limit is not particularly limited, but is preferably 20 mN/cm or more, more preferably 40 mN/cm or more, from the viewpoint of avoiding peeling at an unintended timing when the adhesive layer is laminated.

The antistatic properties of the release film of the present invention can be evaluated by measuring the surface resistivity of the release layer provided on the surface of the substrate film. It can be said that the lower the surface resistivity of the surface of the release film (the surface of the release layer), the better the antistatic property. The surface resistivity can be measured by the method described in Examples below.
If the surface resistivity is 1×10 ¹² Ω/□ or less, it can be said that it has antistatic properties, and if it is 1× ^{10 10} Ω/□ or less, it can be said that it has good antistatic properties. /□ or less is preferable because it can be said that the antistatic performance is extremely good. Above all, if it is 1×10 ⁶ Ω/□ or less, it can be said that the antistatic performance is particularly good.
Although there is no particular lower limit for the surface resistivity, it is preferable to set the surface resistivity to 1×10 ⁴ Ω/□ or more in consideration of the cost required for manufacturing the present film.

In the release film of the present invention, the surface resistivity of the release layer is R _x , and the surface resistivity of the release layer after rubbing the surface of the release layer with a cupra nonwoven fabric 5 times under a load of 680 g is R The surface resistivity ratio (R _Y /R _x ) where _Y is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.0 or less.
The rubbing of the surface of the release layer of the release film can be performed using a rubbing tester by the method described in Examples below.
For example, in the manufacturing process of a display panel, when the film is conveyed with the release film still attached, friction may occur due to contact between the guide roll and the film surface, and the antistatic performance may deteriorate. If the surface resistivity ratio (R _Y /R _x ) is within the above range, deterioration in antistatic performance due to friction or the like can be suppressed, and practical use is possible without any problem.

The above compounds and components in the release layer can be analyzed by, for example, TOF-SIMS, ESCA, fluorescent X-ray analysis, and the like.

<Film laminate>
The film laminate of the present invention has a form in which the release film is bonded to an optical member via an adhesive layer.

[Adhesive layer]
Examples of adhesives for forming the adhesive layer include acrylic adhesives, urethane adhesives, synthetic rubber adhesives, natural rubber adhesives, silicone adhesives, polyester adhesives, and vinyl alkyl ether adhesives. , epoxy adhesive, etc. can be used. Among them, acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, and silicone pressure-sensitive adhesives are preferable, and from the viewpoint of heat resistance and transparency, silicone pressure-sensitive adhesives are more preferable. Two or more kinds of materials can be mixed and used as long as the optical properties are not affected, or two or more layers can be used.
The pressure-sensitive adhesive may be of emulsion type, solvent type or non-solvent type, and may be of cross-linking type or non-cross-linking type.
Furthermore, the adhesive layer can be formed by adding particles such as fillers, additives, and the like to the adhesive.

[Optical member]
The optical member is a resin film or a glass substrate.
The resin film is preferably a resin film selected from polyester film, polyimide film, and cyclic polyolefin film.
Moreover, it is preferable to be a laminated film in which a functional layer is provided on the surface of the resin film in contact with the adhesive layer.
A release layer is preferable as the functional layer. The functional layer is a layer different from the release layer in the release film of the present invention, and is hereinafter referred to as "another release layer" for convenience.

The "other release layer" preferably contains a curable silicone resin from the viewpoint of releasability from the adhesive layer.
Examples of the "other release layer" include a first layer formed from a silicone composition containing a curable silicone resin containing no fluorine substituents as a main component, and a second layer containing a component having a fluorine substituent. A structure having two layers in sequence can be mentioned.

Another example of the "other release layer" is a layer formed from a silicone composition containing, as a main component, a curable silicone resin containing fluorine substituents.

Further, another example of the "other release layer" is a layer formed from a silicone composition containing a curable silicone resin containing no fluorine substituent as a main component.

In addition, the "main component" here means the component with the largest mass ratio among the constituent components.

The total thickness of the film laminate of the present invention is preferably 200 μm or less, more preferably 9 μm or more and 125 μm or less, even more preferably 12 μm or more and 125 μm or less, from the viewpoint of handleability, and 25 μm or more and 125 μm. The following are particularly preferred.

(Manufacturing method of film laminate)
The method for producing the film laminate of the present invention is not particularly limited. The film laminate of the present invention can be produced by laminating another resin film or glass substrate on the layer. The method of applying the adhesive layer-forming liquid is not particularly limited, and a conventionally known method can be used.
Further, as described above, other resin films may be provided with a functional layer on the surface in contact with the adhesive layer.

<Application of release film and film laminate>
Since the release film of the present invention has excellent releasability and antistatic properties, it can be suitably used in the following forms. However, the present invention is not limited to such applications.
A film laminate having a configuration in which the release film of the present invention is laminated on one side of an adhesive layer, and a release film having a higher peel strength than the release film is laminated on the opposite side of the adhesive layer. After peeling off the release film of the present invention, the exposed adhesive layer surface is attached to an adherend such as an optical member, and after curing the adhesive layer, the release film having a high peel strength is peeled off. can be used as However, it is not limited to such usage.

An optical member can be mentioned as an adherend. As described above, the optical member includes a resin film selected from polyester film, polyimide film, and cyclic polyolefin film, or a glass substrate.

In addition, when the release film of the present invention is peeled off from an optical member, which is an adherend, such as a member constituting a display panel, the adherend is not damaged as much as possible and is smoothly peeled off. Since it can be peeled off, it can be suitably used for display panels.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples without departing from the gist thereof.
Moreover, the measurement method and evaluation method used in the present invention are as follows.

<Evaluation method>
(1) Intrinsic viscosity of polyester (IV)
Precisely 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 (weight ratio) to dissolve, and measure with a viscosity measuring device (Rigosha Co., Ltd. "VMS -022UPC-F10") was used to measure the intrinsic viscosity (IV) at 30°C.

(2) Average particle diameter of particles in the base film Using a transmission electron microscope (TEM) ("H-7650" manufactured by Hitachi High-Tech Co., Ltd., acceleration voltage 100 kV), base films of Examples and Comparative Examples was observed, and the average value of the particle diameters of 10 particles was taken as the average particle diameter.

(3) Concentration of Nonvolatile Components in Coating Liquid Using a halogen moisture meter (“HR73” manufactured by Mettler Toledo Co., Ltd.), the concentration was measured at 105° C. for 60 minutes.

(4) Coating amount of release layer It was calculated from the non-volatile component concentration of the coating liquid, the coating amount before drying derived from the consumption of the coating liquid, the transverse stretching ratio, and the like.

(5) Film haze Measured according to JIS K 7136 using a haze meter (“HM-150” manufactured by Murakami Color Research Laboratory).

(6) Release force of release layer On the release layer surface of the release films obtained in Examples and Comparative Examples, the adhesive surface of a 5 cm wide adhesive tape ("No. 31B" manufactured by Nitto Denko Co., Ltd.) was applied with a load of 2 kg. The rubber roller was made to reciprocate one time and pressure-bonded, and the peel strength was measured after being left at 23° C. for 1 hour. The peel strength was measured by using a small tabletop tester "AGX-plus" (manufactured by Shimadzu Corporation), and performing 180° peeling under conditions of an ambient temperature of 23°C and a tensile speed of 300 mm/min.

(7) Surface resistivity of release layer Using a four-point ESP probe on a low resistivity meter ("Loresta GP MCP-T600" manufactured by Nitto Seiko Analytic Tech Co., Ltd.), measurement atmosphere of 23 ° C., 50% RH After conditioning the release films obtained in Examples and Comparative Examples for 30 minutes, the surface resistivity of the release layer surface was measured.
The resistivity correction factor (RCF value) was fixed at 4.235.

(8) Friction treatment of release layer Using a rubbing tester (manufactured by Ohira Rika Kogyo Co., Ltd.), a cupra nonwoven fabric (Ozu Sangyo Co., Ltd.) with four layers of 5 cm x 10 cm on a flat friction element of 5 cm x 7 cm The company's "Bemcot M-3II") is wound without slack, and the release layer surface of the release film obtained in Examples and Comparative Examples is rubbed 5 times (15 cm length range) at a load of 680 g. Surface resistivity was measured. The method for measuring the surface resistivity is as described in (7).
Further, the surface _resistivity ratio _{(R Y /} R _x ) was calculated.

(9) Average particle diameter of fluororesin particles or silica particles Using a particle size distribution meter (“ELSZ-2000ZS” manufactured by Otsuka Electronics Co., Ltd.) by the dynamic light scattering method, the concentration of the sample is adjusted with pure water so that the optimum amount of light can be obtained. It was adjusted and the average particle size was measured. The particle size in the present invention is the particle size (D50) at 50% cumulative volume measured in this manner.

<Materials used>
Polyester raw materials for base films used in Examples and Comparative Examples are as follows.

[Polyester (1)]
A substantially particle-free polyethylene terephthalate having an intrinsic viscosity of 0.64 dL/g

[Polyester (2)]
Polyethylene terephthalate having an intrinsic viscosity of 0.65 dL/g containing 0.2% by mass of amorphous silica having an average particle size of 2.4 μm

The components of the resin composition for forming the release layer were as follows.
(Component (A))
A1: A conductive agent “AS-G1” (manufactured by Shin-Etsu Polymer Co., Ltd., containing polyethylenedioxythiophene and polystyrenesulfonic acid as main components) was neutralized with concentrated aqueous ammonia to pH=9.

(Component (B))
B1: Aqueous dispersion of a long-chain alkyl group-containing compound obtained by reacting polyvinyl alcohol having an average degree of polymerization of 500 and a degree of saponification of 88 mol% with excess octadecyl isocyanate and dispersing the purified product in water using a nonionic dispersant. Stuff

(Component (C))
C1: FEP particle aqueous dispersion with an average particle size of 119 nm (“Neophron FEP ND-110” manufactured by Daikin Industries, Ltd.)
C2: PTFE particle aqueous dispersion with an average particle size of 168 nm (“Polyflon PTFE D-210C” manufactured by Daikin Industries, Ltd.)
In addition, all the average particle diameters are values measured by the method of (9) above.

(Component (D))
D1: Polyester resin aqueous dispersion monomer composition copolymerized with the following composition:
(Acid component) 2,6-naphthalenedicarboxylic acid/5-sodium sulfoisophthalic acid = 92/8 (molar ratio)
(Diol component) Ethylene glycol/diethylene glycol = 80/20 (molar ratio)

(Component (E))
E1: polyglycerol with average n = 4 in the formula (3) E2: sorbitol

(Component (F))
F1: polymethylolated melamine F2: polyglycerol polyglycidyl ether

(Component (G))
G1: In the above formula (4), a nonionic surfactant having a structure having a polyethylene oxide in the side chain in which the average of m + n is 10 G2: A branched perfluoroalkenyl group as a hydrophobic group and a polyethylene oxide chain as a hydrophilic group (average chain length 8 units) fluorine-based nonionic surfactant

(Comparative component (H))
H1: Spherical silica particles having an average particle size of 67 nm The average particle size is the value measured by the method (9) above.

(Example 1)
A blend of polyester (1) and polyester (2) at a weight ratio of 92/8 is used as a raw material for layer A, and only polyester (1) is used as a raw material for layer B, and each is supplied to an extruder and heated to 285 ° C. It is melted and divided into two layers, the A layer being the outermost layer (surface layer), and the B layer being the intermediate layer. They were co-extruded so that A = 5/90/5, and cooled and solidified while being brought into close contact with a mirror surface cooling drum having a surface temperature of 40 to 50°C to prepare an unstretched film. This film was stretched 3.7 times in the longitudinal direction while being passed through a group of heating rolls at 85° C. to obtain a uniaxially stretched film. On one side of this uniaxially stretched film, a resin composition 1 (coating liquid 1, non-volatile component concentration: 4.4% by mass) having the composition shown in Table 1 below was applied, and then this film was introduced into a tenter stretching machine and stretched at 100°C. After stretching 4.3 times in the width direction and further heat treatment at 230 ° C., 2% relaxation treatment is performed in the width direction, and the coating amount after drying is 46 mg / m ² . A release film of Example 1 was obtained as a biaxially stretched film having a thickness of 50 μm. The evaluation results of this release film are shown in Table 2 below.

(Examples 2 to 11, Comparative Examples 1 to 3)
Release films of Examples 2 to 11 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1 except that the resin composition for forming the release layer was changed to the composition shown in Table 1. . Table 2 shows the evaluation results.

The release films obtained in Examples 1 to 11 of the present invention had both excellent releasability and antistatic properties, and also had excellent transparency. Moreover, it turned out that it is especially excellent in abrasion resistance. Compared with Examples 1 to 11, Comparative Example 1 in which the fluororesin particles of the component (C) were not added, and Comparative Examples 2 and 3 in which silica particles were added instead of the fluororesin particles were improved in abrasion resistance. was inferior in
INDUSTRIAL APPLICABILITY The release film obtained by the present invention has excellent releasability and antistatic properties, and also has excellent abrasion resistance, and has high industrial utility value.

Claims (18)

A release film having a release layer formed from a resin composition containing the following component (A), component (B) and component (C) on at least one surface of a base film.
Component (A): (a1) a polymer obtained by doping a compound comprising thiophene or a thiophene derivative with another anionic compound; One or more selected from coalescence Component (B): release agent Component (C): fluororesin particles The release film according to claim 1, wherein the component (B) release agent is one or more selected from the group consisting of long-chain alkyl group-containing compounds and waxes. 3. The release film according to claim 1, wherein the fluororesin particles of component (C) are one or more selected from the group consisting of hexafluoropropylene-tetrafluoroethylene copolymer and polytetrafluoroethylene. The release film according to any one of claims 1 to 3, wherein the fluororesin particles of component (C) have an average particle size of 10 to 1000 nm. The separation according to any one of claims 1 to 4, wherein the content of the fluororesin particles of the component (C) is 0.1 to 20% by mass as a proportion of the total nonvolatile components in the resin composition. mold film. The release film according to any one of claims 1 to 5, wherein the resin composition further contains a binder resin as component (D). 7. The release film according to claim 6, wherein the binder resin of component (D) is one or more selected from the group consisting of polyurethane resins, polyester resins and acrylic resins. Claims 1 to 3, wherein the resin composition further comprises, as component (E), one or more selected from glycerin, polyglycerin, alkylene oxide adducts to said glycerin or said polyglycerin, sugar alcohols and sugar alcohol condensates. 8. The release film according to any one of 7. The ratio of the surface resistivity (R _x ) of the release layer to the surface resistivity (R _Y ) of the release layer after 5 reciprocating friction treatments were performed on the release layer surface with a cupro nonwoven fabric under a load of 680 g. The release film according to any one of claims 1 to 8, wherein (R _Y /R _x ) is 4.0 or less. An acrylic adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation) is attached to the release layer and left at 23°C for 1 hour. The release film according to any one of claims 1 to 9, which has a 180° peel force of 200 mN/cm or less. The release film according to any one of claims 1 to 10, wherein the base film is a polyester film. A film laminate in which the release film according to any one of claims 1 to 11 is bonded to an optical member via an adhesive layer. The film laminate according to claim 12, wherein the optical member is a resin film or a glass substrate. 14. The film laminate according to claim 13, wherein the resin film is selected from polyester film, polyimide film, and cyclic polyolefin film. 15. The film laminate according to claim 13 or 14, which is a laminate film in which a functional layer is provided on the surface of the resin film in contact with the adhesive layer. 16. The film laminate according to claim 15, wherein the functional layer is another release layer. 17. The film laminate according to claim 16, wherein said other release layer comprises a curable silicone resin. The film laminate according to any one of claims 12 to 17, which has a total thickness of 200 µm or less.