JP6970400B2 - Release film and laminate using it - Google Patents

Description

The present invention relates to a release film and a laminate using the same.

In recent years, with the growth of information technology-related businesses, the amount of various film materials used in the optical display field such as liquid crystals and organic EL has increased dramatically.

A release film based on a polyester film is one of these materials, and the release film is used to produce an adhesive sheet (OCA: Optically Clear Adjust) used for bonding optical films to each other. It is widely used as a composition of a release film / OCA / release film.

When this OCA is used by being bonded to an optical member, one of the release films of the release film / OCA / release film is peeled off and bonded to the optical member to form an optical member / OCA / release film. It is said that.

The OCA used is required to be highly transparent and smooth, and when there are many coarse protrusions on the release layer surface, the shape of the release surface is transferred to the OCA, causing problems such as deterioration of transparency and generation of bright spots. It causes.

Further, when the surface of the polyester film of the base material is smoothed in order to prevent the above problems, the slipperiness deteriorates, and problems such as transportability, blocking when rolled, and peeling charge when pulling out the roll occur. ..

Therefore, in Patent Document 1, a release layer made of curable silicone is provided on an undercoat layer made of a silane coupling agent containing a specific amount of anionic antistatic agent, and the thickness of the undercoat layer and the release layer are provided. By defining the 10-point average roughness Rz of the surface, a release film having excellent antistatic property, curability of the release layer, and adhesion is proposed.

Further, Patent Document 2 defines the inclination of the main axis of the orientation angle, the arithmetic mean roughness (Sa) of the surface of the release layer, the sharpness of the surface height distribution (SKu), and the surface roughness Sa of the surface of the release type layer. At the same time as giving smoothness to the adhesive layer, slipperiness is improved even when it is overlapped with the hard coat layer, blocking does not occur, defects can be easily detected by an automatic inspection machine, and to prevent scattering. A release film used for a base-less double-sided pressure-sensitive adhesive sheet used for a protective film has been proposed.

Further, in Patent Document 3, a release film in which a polyester layer containing no antimony element is used as both outer layers, and a coating layer and a curable silicone resin are provided on one side of a laminated polyester film composed of at least two layers. Amount of oligomer after treatment at a predetermined temperature and time, amount of silicone transfer on the release surface, arithmetic average roughness of the release surface (Ra), arithmetic average roughness of the surface without the release layer (Ra) And by defining the ten-point average roughness Rz and the arithmetic average roughness Ra of the release surface, in order to cope with the miniaturization and sophistication of wiring, it is used on the film for the multi-layer printed wiring board manufactured by the build-up method. As a support for forming the interlayer insulating material of the above, a release film having good releasability, migration, oligomer encapsulation, blocking property, and surface smoothness has been proposed.

Further, Patent Document 4 defines the particle size and concentration contained in the release layer and the opposite surface thereof, smoothes the surface so that SRa and SRz are within a certain range, and manufactures a laminated ceramic sheet having few defects. Release films used for this are provided.

Japanese Patent No. 6130230 Japanese Unexamined Patent Publication No. 2017-13387 Japanese Unexamined Patent Publication No. 2014-8720 Japanese Unexamined Patent Publication No. 2015-33811

However, since the release film described in Patent Document 1 does not specify the surface roughness of the surface of the non-release layer and the peeling force, the surface of the release layer and the surface of the non-release layer may slip too much. There are problems such as misalignment during transportation, misalignment during winding and unwinding, and practical use.

Further, since the release film described in Patent Document 2, Patent Document 3 and Patent Document 4 does not specify the release force, the transparency of OCA after peeling by the release film is lowered and the surface is roughened. There is a problem that it cannot be used practically.

Therefore, the present invention provides a release film having excellent transportability and workability for suppressing surface roughness of OCA due to the release film bonded at the time of peeling and storage, and a laminate using the same.

In order to solve the above problems, the present invention has the following configuration.

The release film of the present invention is a release film in which a release layer is provided on one side of a polyester film, and the surface roughness (Sa) of the surface on the release layer side is 5 to 15 nm and the average height is 10 points. (Rz) is 500 nm or less, the surface roughness (Sa) of the surface on the polyester film side (hereinafter referred to as the non-release layer side) is 5 to 15 nm, and the surface is pressed against the surface on the release layer side and peeled off. This is a release film having a release force of 10 to 20 N / 50 mm from the adhesive tape on the surface on the non-release layer side.

Further, the laminate of the present invention is a laminate containing the first release film, the pressure-sensitive adhesive sheet, and the second release film in this order, and is the first release film and the second release film. The film is the release film according to any one of claims 1 to 4, and the release layer of both the first release film and the second release film is on the pressure-sensitive adhesive sheet side. The release force (F1) from the adhesive tape on the surface of the first release film on the release layer side is 50 to 100 mN / 50 mm, and the surface of the second release film on the release layer side. The peeling force (F2) from the adhesive tape is 70 to 1000 mN / 50 mm, and the ratio of the peeling force (F2 / F1) is 1.2 to 20.

The release film and laminate of the present invention are release films or laminates for preventing deterioration of OCA transparency and surface roughness after peeling by the release film, which could not be achieved by the prior art. Excellent in transportability and workability.

In the present invention, "the surface on the non-release layer side after being pressure-contacted with the surface on the release layer side and peeled off" means that two same release films are prepared and the first release film is released from the mold. The surface on the layer side and the surface on the non-release layer side of the second release film were brought into contact with each other at 1.0 MPa for 2 hours and peeled off, and then the non-release layer of the second release film was released. Refers to the side surface. Further, the "release layer side surface" refers to the surface of the release film opposite to the polyester film side, that is, the surface of the release layer, and the surface on the side on which the release layer of the polyester film is laminated. It does not mean that. The "adhesive tape" refers to a polyester adhesive tape (No. 31B tape, 50 mm width) manufactured by Nitto Denko Corporation.

The polyester film used for the release film of the present invention may have a single layer, a two-layer structure, or even a three-layer structure, and may have four layers or four layers or three layers as long as the gist of the present invention is not exceeded. It may have more layers, and is not particularly limited.

The polyester constituting the polyester film in the present invention is preferably a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, and homopolyesters and copolymerized polyesters are exemplified.

As the homopolyester, those obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol are preferable.

Examples of the aromatic dicarboxylic acid of homopolyester include terephthalic acid and 2,6-naphthalenedicarboxylic acid.

Examples of the aliphatic glycol include ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol and the like.

Typical polyesters include polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and the like.

Further, as the dicarboxylic acid of the copolymerized polyester, one or two kinds such as phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid such as paraoxybenzoic acid and the like. It is exemplified that the above is used together.

As the aliphatic glycol, one or two kinds such as ethylene glycol, diethylene glycol and neopentyl glycol are exemplified in combination.

The polyester film used in the present invention may contain compounds such as antimony compounds, titanium compounds and phosphorus compounds. Each concentration is not particularly limited as long as it does not exceed the gist of the present invention.

In the present invention, it is preferable to add particles to the polyester film mainly for the purpose of imparting slipperiness. The type of particles to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness, and specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples thereof include particles such as magnesium, kaolin, aluminum oxide and titanium oxide, and heat-resistant organic particles such as thermosetting urea resin, thermosetting phenol resin, thermosetting epoxy resin and benzoguanamine resin. Further, during the polyester manufacturing process, precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed can also be used. On the other hand, the shape of the particles to be used is not particularly limited, and any of spherical, lumpy, rod-shaped, flat-shaped and the like may be used. Further, the hardness, specific gravity, color and the like are not particularly limited. Two or more kinds of these series of particles may be used in combination, if necessary.

The average particle size of the particles used is usually in the range of 0.01 to 3 μm, preferably 0.01 to 1 μm. If the average particle size is less than 0.01 μm, the particles tend to aggregate and the dispersibility may be insufficient, while if it exceeds 3 μm, the surface roughness of the film becomes too coarse, and later Problems may occur when the release layer is applied in the process.

Further, the particle content in the polyester film is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. If the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient. On the other hand, if it is added in an amount of more than 5% by weight, the transparency of the film may be insufficient.

When the average particle size of the particles is small and the particle content is small, the Sa and Rz of the surface on the release layer side and / or the surface on the non-release layer side become small. On the other hand, when the average particle size of the particles is large and the particle content is large, Sa and Rz become large. By adjusting the average particle size and the particle content of these particles, the desired Sa and Rz can be realized.

The method of adding the particles to the polyester film is not particularly limited, and a conventionally known method can be adopted. For example, the particles can be added at any stage in which the polyester is produced, but it is preferably added at the stage of esterification or at the stage of polycondensation reaction after the completion of the transesterification reaction.

As a method for blending the particles and the polyester raw material, a kneading extruder with a vent is used, a method of blending the slurry of particles dispersed in ethylene glycol or water with the polyester raw material, or a kneading extruder is used for drying. Examples thereof include a method of blending the mixed particles with the polyester raw material.

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

The thickness of the polyester film constituting the release film of the present invention is not particularly limited as long as it can be formed as a film, but is usually 12 to 250 μm, preferably 25 to 188 μm, more preferably 25 to 188 μm. It is in the range of 38 to 125 μm.

Next, a production example of the polyester film in the present invention will be specifically described, but the present invention is not limited to the following production examples.

First, using the polyester raw material described above, the molten sheet extruded from the die is cooled and solidified with a cooling roll to obtain an unstretched sheet. In this case, in order to improve the flatness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method and / or the liquid coating adhesion method is preferably adopted. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. It is also possible to adopt a method in which stretching in one direction is performed in two or more steps. In that case, it is preferable that the stretching ratios in the two directions are finally within the range of the stretching ratios of the simultaneous biaxial stretching method described later.

Further, for the production of the polyester film in the present invention, the simultaneous biaxial stretching method can also be adopted. The simultaneous biaxial stretching method is a method in which the unstretched sheet is simultaneously stretched and oriented in the mechanical direction and the width direction while the temperature is controlled at 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is The area magnification is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times. Then, the heat treatment is subsequently performed at a temperature of 170 to 250 ° C. under tension or relaxation within 30% to obtain a stretch-oriented film. As for the simultaneous biaxial stretching device that employs the above-mentioned stretching method, a conventionally known stretching method such as a screw method, a pantograph method, and a linear drive method can be adopted.

Further, a so-called coating and stretching method (in-line coating), which treats the film surface during the stretching step of the polyester film described above, can be applied. When the coating layer is provided on the polyester film by the coating and stretching method, the coating can be applied at the same time as stretching, and the thickness of the coating layer can be reduced according to the stretching ratio, so that a film suitable as a polyester film can be obtained. Can be manufactured.

In the present invention, it is essential that the surface roughness (Sa) of the surface on the release layer side is 5 to 15 nm. If the surface roughness (Sa) of the surface on the release layer side is less than 5 nm, peeling charge will occur when blocking or unwinding the film, and workability will deteriorate. If it exceeds 15 nm, after adhesive coating When stored in that state, dents or the like may be generated on the adhesive surface.

In the present invention, it is essential that the 10-point average height (Rz) of the surface on the release layer side is 500 nm or less. If the 10-point average height (Rz) of the surface on the release layer side exceeds 500 nm, it causes defects such as roughness and dents on the OCA surface after peeling.

In the present invention, it is essential that the surface roughness (Sa) of the surface on the non-release layer side is 5 to 15 nm. Further, in the present invention, the peeling force with the adhesive tape on the surface on the non-release layer side after pressure contact with the surface on the release layer side and peeling (hereinafter, peeling from the adhesive tape on the surface on the non-release layer side). It is essential that the force) is 10 to 20 N / 50 mm. If the surface roughness (Sa) of the surface on the non-release layer side is less than 5 nm, or if the peeling force of the surface on the non-release layer side from the adhesive tape exceeds 20 N / 50 mm, the slipperiness is lowered and the transportability is reduced. Is reduced, blocking and peeling charge when the film is unwound occur. When the surface roughness (Sa) of the surface on the non-release layer side exceeds 15 nm and the peeling force of the surface on the non-release layer side from the adhesive tape is less than 10 N / 50 mm, the slipperiness becomes too high. Misalignment during transportation, winding, and unwinding occur.

In the present invention, the peeling force of the surface on the non-release layer side from the adhesive tape is not particularly limited in the above range, but before or after forming the release layer, the surface on the non-release layer side. A method of coating a slippery imparting agent can be mentioned. Further, there is also a method of forming a release layer and at the same time coating a surface on the non-release layer side with a slippery imparting agent. That is, there is a method of forming a release layer containing a silicon atom (hereinafter, may be referred to as Si) and transferring Si to the surface on the non-release layer side at the same time as winding. Of these, a method of forming a release layer containing Si and transferring Si to the surface on the non-release layer side at the same time as winding is preferable in terms of cost. As a method of transferring Si contained in the release layer to the surface on the non-release layer side, when forming the release layer, the Si is wound without being completely cured, and Si is transferred to the surface on the non-release layer side. Transfer method, increase the tension at the time of winding after forming the release layer, increase the surface pressure of the wound roll, transfer Si to the surface on the non-release layer side, to the roll after winding There is a method of applying heat to cure the release layer in a state where the release layer is in contact with the surface on the non-release layer side, and transferring Si to the surface on the non-release layer side. By such a method or the like, the Si concentration of the target surface on the non-release layer side and the peeling force from the adhesive tape on the surface on the non-release layer side can be obtained. In order to further enhance the effect of transferring Si from the release layer to the surface on the non-release layer side, the release layer may contain a transfer component in advance.

In the release film of the present invention, the peeling force of the surface on the release layer side from the adhesive tape is preferably 50 to 1000 mN / 50 mm. If the peeling force is less than 50 mN / 50 mm, the peeling force may be peeled off during transportation after being bonded to the adhesive. Further, if the peeling force exceeds 1000 mN / 50 mm, the release film may not be peeled off from the adhesive, or the adhesive surface may be roughened or dented when the release film is peeled off. The release force of the release layer of the release film can be adjusted, for example, by changing the amount of the release control agent added.

In the release film of the present invention, it is preferable that the dynamic friction coefficient of the surface on the non-release layer side after pressure contact with the surface on the release layer side and peeling is 0.3 to 0.5. Here, the definition of "the surface on the non-release layer side after pressure contact with the surface on the release layer side and peeling" is as described above. If the coefficient of kinetic friction is less than 0.3, deviation is likely to occur during transportation, which may cause a problem in the process. Further, if the dynamic friction coefficient exceeds 0.5, defects such as scratches are likely to occur during transportation, and the defects may easily cause deformation or roughness of the adhesive.

The release film of the present invention preferably has a peeling charge of 3.0 kV or less when unwound. The amount of peeling charge at the time of unwinding refers to the roll surface potential when the release film is unwound from the roll. When the amount of peeling charge when unwinding exceeds 3.0 kV, the film clings to the device or human body due to static electricity, which deteriorates workability and tends to cause uneven coating when the adhesive is applied. There is.

Keeping the dynamic friction coefficient of the surface of the release film on the non-release layer side and the amount of peeling charge when unwinding within the above ranges means the surface roughness (Sa) of the surface on the release layer side, 10-point average. It can be achieved by adjusting the height (Rz), the surface roughness (Sa) of the surface on the non-release layer side, and the peeling force of the surface on the non-release layer side from the adhesive tape within the above ranges.

Examples of the material for forming the release layer in the present invention include an alkyd resin-based release agent, a polyolefin-based release agent, a long-chain alkyl group-containing resin-based release agent, a fluorine-based release agent, and a silicone-based release agent. Examples thereof include a mold agent, a mixture of an organic type and a silicone type, or a copolymer resin type mold release agent. Of these, silicone-based mold release agents are particularly preferable because they exhibit excellent mold release properties and heat resistance. Silicone-based mold release agents are classified according to reaction form, such as heat-curable type such as addition reaction type and condensation reaction type, ultraviolet curable type, electron beam curable type, and combined heat and ultraviolet curable type. Silicone release agents can also be used.

The thickness of the release layer is preferably 10 to 500 nm, more preferably 30 to 200 nm. If the release layer is too thin, the peeling performance may deteriorate, and if it is too thick, flatness, dryness, and uneven coating may occur. The thickness of the release layer can be determined by a method of confirming the thickness of the release layer by cutting out a section after embedding it in a resin and observing it using a transmission electron microscope, and the thickness confirmed in that way. Examples thereof include a method of creating a calibration curve of Si amount kcps for X-ray fluorescence measurement, measuring Si amount kcps, and confirming the thickness.

As a method of applying the material for forming these release layers to the polyester film, a general coating method can be used. For example, a coating method such as a gravure coat, a gravure reverse coat, a lip coat, a die coat, a micro gravure coat, a Meyer bar coat, and a multi-stage reverse coat can be used.

In the present invention, the curing conditions for forming the release layer on the polyester film are not particularly limited, but are not particularly limited, but are 60 to 200 ° C. for 3 to 40 seconds, preferably 80 to 180 ° C. for 3 to 3 to. It is good to heat treat for 40 seconds. Further, if necessary, heat treatment and activation energy ray irradiation such as ultraviolet irradiation may be used in combination.

Further, the polyester film constituting the release film may be subjected to surface treatment such as corona treatment and plasma treatment in advance.

A layer for improving the adhesion between the release layer and the polyester film, a layer for preventing precipitates such as oligomers from the polyester film from precipitating on the surface of the release layer may be provided between the polyester film and the release layer. , The number of layers is not particularly limited. Such a layer may be provided at the time of forming the polyester film, or may be provided by coating or the like after forming the polyester film. When provided by coating, a general coating method can be used. For example, a coating method such as a gravure coat, a gravure reverse coat, a lip coat, a die coat, a micro gravure coat, a Meyer bar coat, and a multi-stage reverse coat can be used.

In the present invention, the curing conditions for forming the above-mentioned layer are not particularly limited, but the heat treatment is performed at 60 to 200 ° C. for 3 to 40 seconds, preferably 80 to 180 ° C. for 3 to 40 seconds. Good to do. Further, if necessary, heat treatment and activation energy ray irradiation such as ultraviolet irradiation may be used in combination.

The laminate of the present invention is a laminate containing a first release film, an adhesive sheet, and a second release film in this order, and the first release film and the second release film are included in this order. Both are the release films according to any one of claims 1 to 4, and both the first release film and the second release film have the release layer on the pressure-sensitive adhesive sheet side. The peeling force (F1) from the adhesive tape on the surface of the first release film on the release layer side is 50 to 100 mN / 50 mm, and the adhesion of the surface of the second release film on the release layer side is 50 to 100 mN / 50 mm. The peeling force (F2) from the tape is 70 to 1000 mN / 50 mm, and the ratio of the peeling force (F2 / F1) is 1.2 to 20.

If the release force (F1) of the first release film on the release layer side surface from the adhesive tape is less than 50 mN / 50 mm, it may be peeled off during transportation after being bonded to the adhesive, and is 100 mN / If it exceeds 50 mm, the first release film is peeled off first, which may reduce workability.

If the release force (F2) of the second release film on the surface on the release layer side with the adhesive tape is less than 70 mN / 50 mm, the second release film will be released when the first release film is peeled off. There is a possibility of peeling, which may reduce workability. If it exceeds 1000 mN / 50 mm, it will not peel off when the release film is peeled off, or the adhesive surface will be rough or dented when peeled off. May be done.

The ratio of the release force (F2 / F1) is the release force (F2) from the adhesive tape on the surface of the second release film on the release layer side, and the release force ratio (F2) of the surface of the first release film on the release layer side. It is divided by the peeling force (F1) from the adhesive tape. If the peeling force ratio (F2 / F1) is less than 1.2, there is a concern that the second release film will be peeled off when the first release film is peeled off. Further, when the peeling force ratio (F2 / F1) exceeds 20, the peeling force may become too strong, and when the peeling force is peeled off, the adhesive surface may be roughened or dents may be generated.

In the present invention, the pressure-sensitive adhesive is not particularly limited, but an acrylic pressure-sensitive adhesive is preferable. Further, ultraviolet curable adhesives and the like can be mentioned. By irradiating the ultraviolet curable pressure-sensitive adhesive with ultraviolet rays, the base polymer is crosslinked by the polymerizable compound, and the storage elastic modulus of the pressure-sensitive adhesive is enhanced. The composition of the ultraviolet curable pressure-sensitive adhesive is not particularly limited, but generally contains a base polymer and a polymerizable compound. The polymerization curing method by irradiation with ultraviolet rays may be any of a radical type, a cationic type and an anion type, and a light-induced alternating copolymer type that does not require an initiator can also be used. Further, a hybrid type in which these are combined may be used. Generally, radical type or cationic type is often used.

Examples of the polymerizable compound include various types such as polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based, and include ultraviolet curable monomers, oligomers, and prepolymers. The polymerizable compound preferably has an ultraviolet polymerizable functional group, and more preferably contains an acrylic monomer or an oligomer component having two or more of the functional groups. The two or more polymerizable functional groups may be the same or different. Examples of the ultraviolet curable acrylic compound include polyfunctional acrylates, epoxy acrylates, urethane acrylates, polyester acrylates, polyether acrylates, and spiroacetal acrylates. These polymerizable compounds may be present in the pressure-sensitive adhesive composition or may be bonded to a functional group such as a hydroxy group of the base polymer.

The UV curable pressure-sensitive adhesive preferably contains a photopolymerization initiator. The photopolymerization initiator generates radicals, acids, bases and the like by irradiation with ultraviolet rays, and can be appropriately selected depending on the type of the polymerizable compound and the like. A photoradical generator is preferably used for photoradical polymerization, a photoacid generator is preferably used for photocationic polymerization, and a photobase generator is preferably used for photoanionic polymerization. As the photoradical generator, a compound having one or more radical generation points in the molecule is used, for example, hydroxyketones, benzyldimethylketals, aminoketones, acylphosphine oxides, benzophenones, trichloromethyls. Examples thereof include a group-containing triazine derivative.

The base polymer of the ultraviolet curable adhesive is not particularly limited, and acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate / vinyl chloride copolymer, modified polyolefin, epoxy type, fluorine type, natural rubber, etc. A rubber-based polymer such as synthetic rubber can be appropriately selected and used.

As the pressure-sensitive adhesive having excellent optical transparency and adhesiveness, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferably used. In the acrylic pressure-sensitive adhesive, the content of the acrylic-based base polymer with respect to the total solid content of the pressure-sensitive adhesive composition is preferably 50% by weight or more, more preferably 70% by weight or more, and more preferably 80% by weight or more. Is even more preferable.

As the acrylic polymer, a polymer having a monomer unit of a (meth) acrylic acid alkyl ester as a main skeleton is preferably used. In addition, in this specification, "(meth) acrylic" means acrylic and / or methacryl. As the (meth) acrylic acid alkyl ester, a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferably used. The content of the (meth) acrylic acid alkyl ester is preferably 40% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more, based on the total amount of the monomer components constituting the base polymer. The acrylic base polymer may be a copolymer of a plurality of (meth) acrylic acid alkyl esters. The arrangement of the constituent monomer units may be random or block.

The acrylic-based base polymer preferably contains an acrylic monomer unit having a crosslinkable functional group as a copolymerization component. When the base polymer has a crosslinkable functional group, it can be easily cured by ultraviolet irradiation. Examples of the acrylic monomer having a crosslinkable functional group include a hydroxy group-containing monomer and a carboxy group-containing monomer. Above all, it is preferable to contain a hydroxy group-containing monomer as a copolymerization component of the base polymer. When the base polymer has a hydroxy group-containing monomer as a monomer unit, the crosslinkability of the base polymer is enhanced, and the white turbidity of the pressure-sensitive adhesive in a high-temperature and high-humidity environment tends to be suppressed, so that the pressure-sensitive adhesive has high transparency. Is obtained.

The acrylic base polymer preferably contains a highly polar monomer unit such as a nitrogen-containing monomer in addition to the above-mentioned (meth) acrylic acid alkyl ester and hydroxy group-containing monomer unit. By containing a highly polar monomer unit such as a nitrogen-containing monomer unit in addition to the hydroxy group-containing monomer unit, the pressure-sensitive adhesive has high adhesiveness and holding power, and white turbidity in a high-temperature and high-humidity environment is suppressed. ..

The acrylic polymer as a base polymer can be obtained by polymerizing the above-mentioned monomer components by various known methods such as solution polymerization, emulsion polymerization and bulk polymerization. The solution polymerization method is preferable from the viewpoint of the balance of characteristics such as the adhesive force and the holding force of the pressure-sensitive adhesive and the cost.

A crosslinked structure may be introduced into the base polymer of the ultraviolet curable pressure-sensitive adhesive. The cross-linked structure is formed, for example, by adding a cross-linking agent after the polymerization of the base polymer and heating. As the cross-linking agent, commonly used ones such as an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an oxazoline-based cross-linking agent, an aziridine-based cross-linking agent, a carbodiimide-based cross-linking agent, and a metal chelate-based cross-linking agent can be used. Further, by mixing a radically polymerizable compound having a functional group capable of binding to the functional group of the base polymer and a radically polymerizable functional group with the base polymer, the radically polymerizable functional group can be introduced into the base polymer. .. As the functional group that can be bonded to the functional group of the base polymer, an isocyanate group is preferable. Since the isocyanate group forms a urethane bond with the hydroxy group of the base polymer, a radically polymerizable functional group can be easily introduced into the base polymer. In the pressure-sensitive adhesive composition, silane is used for the purpose of adjusting the adhesive strength. A coupling agent or a tackifier may be contained. Further, the pressure-sensitive adhesive composition may contain additives such as a plasticizer, a softener, a deterioration inhibitor, a filler, a colorant, an antioxidant, a surfactant, and an antistatic agent.

The pressure-sensitive adhesive may be a single layer or a multi-layer structure in which a plurality of pressure-sensitive adhesives are laminated. When the pressure-sensitive adhesive has a multi-layer structure, at least one layer may be an ultraviolet curable pressure-sensitive adhesive, but all layers may be an ultraviolet-curable pressure-sensitive adhesive.

The thickness of the pressure-sensitive adhesive is preferably 20 μm or more. When the thickness of the adhesive is 20 μm or more, it is possible to provide step absorption to the step of the printed portion of the front transparent member when the adhesive is attached to the front transparent member such as a touch panel or the front transparent plate. The upper limit of the thickness of the adhesive is not particularly limited, but 500 μm or less is preferable, and 300 μm or less is more preferable, considering the viewpoint of weight reduction and thinning of the image display device, ease of forming the adhesive, handleability, and the like. , 100 μm or less is more preferable.

In the laminate of the present invention, after pressure contacting with the surface on the release layer side and peeling, the surface on the non-release layer side of the first release film and the surface on the release layer side are pressed and peeled off. The coefficient of dynamic friction with the surface of the second release film on the non-release layer side is preferably 0.5 or less. If the coefficient of kinetic friction exceeds 0.5, defects such as scratches may easily occur during transportability. Further, when the laminated body is unwound, the peeling charge amount may easily exceed 3 kV. Here, "the surface on the non-release layer side of the first release film after being pressure-contacted with the surface on the release layer side and peeled off" means that two first release films are prepared and one sheet is prepared. The surface of the first release film of the eye on the release layer side and the surface of the second first release film on the non-release layer side were brought into contact with each other at 1.0 MPa for 2 hours and peeled off. Refers to the surface of the second release film on the non-release layer side. Further, "the surface on the non-release layer side of the second release film after being pressure-contacted with the surface on the release layer side and peeled off" means that two second release films are prepared and the first sheet. After the surface of the second release film on the release layer side and the surface of the second release film on the non-release layer side were brought into contact with each other at 1.0 MPa for 2 hours and peeled off. Refers to the surface of the second release film on the non-release layer side. The coefficient of kinetic friction here is the surface of the second release film after the release on the non-release layer side and the second release of the second release film after the release. Refers to the coefficient of dynamic friction between the film and the surface on the non-release layer side.

The laminate of the present invention preferably has a peeling charge amount of 3.0 kV or less when unwound. If the amount of peeling charge exceeds 3.0 kV, workability tends to decrease.

The dynamic friction coefficient between the non-release layer side of the first release film and the non-release layer side of the second release film, and the amount of peeling charge when unwinding the laminate are within the above ranges. It can be achieved by adjusting the surface roughness (Sa) on the non-release layer side and the peeling force on the non-release layer side of the release film 1 and the second release film within the above ranges.

In the laminate of the present invention, the degree of increase in haze of the pressure-sensitive adhesive after peeling off the first release film and the second release film is preferably 5 or less. The degree of increase in the haze of the pressure-sensitive adhesive after peeling off the first release film and the second release film determines the haze of the pressure-sensitive adhesive after peeling off the first release film and the second release film. It is divided by the haze of the laminated body before it is used. If the degree of increase in haze of the pressure-sensitive adhesive after peeling off the first release film and the second release film exceeds 5, it becomes impossible to secure the desired transparency when using OCA.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

The measurement method used in the present invention is as follows.

[Measuring method]
(1) Surface roughness The surface on the release layer side and the surface on the non-release layer side are 1 mm using a non-contact surface / layer cross-sectional shape measurement system VertScan R5300GL-Lite-AC manufactured by Ryoka System using an objective lens 50 times. It was set to the measurement area of the corner and measured according to ISO 25178-3.2 (2010).
(2) Peeling force from the release layer side surface with the adhesive tape A polyester adhesive tape (Nitto Denko Corporation No. 31B tape, 50 mm width) was applied as an adhesive tape to the release layer side surface of the release film. The tapes were bonded together while being pressure-bonded with a 5 kg roller, left at room temperature for 24 hours, and then the peel strength when the tape was peeled at a peeling speed of 300 mm / min and a peeling angle of 180 ° was measured with a tensile tester.
(3) Peeling force from the adhesive tape on the surface on the non-release layer side after pressure contact with the surface on the release layer side and peeling Two sheets of the same release film were prepared. The surface of the first release film on the non-release layer side and the surface of the second release film on the release layer side faced each other. The two release films facing each other were brought into contact with each other at a pressure of 1.0 MPa for 2 hours, and then peeled off. The peeling force of the surface of the first release film on the non-release layer side was measured by the method (2) above.
(4) Slipability (coefficient of dynamic friction)
The release surface side and the non-release surface side of the two release films face each other, and the dynamic friction coefficient on the non-release surface side after contacting the facing samples at a pressure of 1.0 MPa for 2 hours is measured. bottom. The method was measured under the following conditions using a jig (Shinto Kagaku Co., Ltd., surface measuring machine HEIDON-Type14FW) conforming to JIS K7125 (1999).

Sliding surface: length 150 mm x width 100 mm
Slip piece: length 50 mm x width 50 mm
Load: 2.0N
Slip speed: 100 mm / min
Measurement sample:
1) When measuring the dynamic friction coefficient of the surface on the non-release layer side of the release film Sliding surface: 125 μm "Lumirror" U48, Sliding piece: Surface on the non-release surface side of the release film 2) First of the laminate When measuring the dynamic friction coefficient between the surface on the non-release layer side of the release film and the surface on the non-release layer side of the second release film Sliding surface: The non-release surface side of the first release film Surface, slip piece ... In the case of the release film of the second release film on the non-release surface side, the moving friction coefficient: 1), 0.3 to 0.5 was accepted. In the case of the laminated body of 2), 0.5 or less was regarded as acceptable.
(5) Measurement of peeling charge amount at the time of unwinding The roll surface immediately after unwinding 20 m of the release film or laminate at a speed of 2 m / s using FMX-003 manufactured by Simco Japan is 50 mm from the roll surface. Potential measurements were taken at distant points. Peeling charge amount: 3.0 kV or less was regarded as acceptable.
(6) Evaluation of transportability A 1000 mm wide release film is unwound at a film transport speed of 10 m / min for 1000 m, wound with a tension of 20 kgf, and a film with a deviation of 10 mm or more at the end of the film is × 5 to 10 mm. Those less than 5 mm were marked with ◯.
(7) Workability evaluation When the release film is unwound, the film clings to the device or the human body due to the release discharge, and the workability is poor. It was marked as ○.
(8) Comprehensive Judgment Comprehensive judgment was made with ○ for both (6) and (7) above, △ for either △, and × for either. ..
(Example 1)
3-part by weight of BY24-846B (manufactured by Dow Corning Co., Ltd., content 98% by weight), which is 3-glycidoxypropyltrimethoxysilane, BY24-846C (Toray, Inc.), which is 3-methacryloxypropyltrimethoxysilane. Made by Dow Corning Co., Ltd., content 99% by weight) 1 part by weight, bis (ethylacetate acetate) (2,4-pentandionate) aluminum BY24-846E (manufactured by Toray Dow Corning Co., Ltd., content) 38% by weight) A primer coating solution was prepared by mixing 2 parts by weight with 60 parts by weight of toluene and 60 parts by weight of isopropyl alcohol (IPA).

3 parts by weight of LTC761 (manufactured by Toray Dow Corning Co., Ltd.), which is an addition reaction type curable silicone resin, and 1 part by weight of LTC303E (manufactured by Toray Dow Corning Co., Ltd.), which is an addition reaction type curable silicone resin. 0.04 part by weight of SRX212 (manufactured by Toray Dow Corning) as a curing agent was added to a solution mixed with 46 parts by weight of n-peptane and 50 parts by weight of toluene, and mixed to prepare a release layer coating liquid 1. ..

A primer coating solution was applied to a 100 μm-thick polyethylene terephthalate film (“Lumilar (registered trademark)” R41 manufactured by Toray Industries, Inc.) so that the coating thickness after drying was 50 nm. After applying in 3 and drying and curing at 100 ° C. for 5 seconds, the release layer coating liquid 1 was continuously applied to the Meyer bar No. 1 so that the coating thickness became 50 nm. It was applied in No. 5 and dried and cured at 150 ° C. for 20 seconds to obtain a release film. The surface roughness, friction coefficient and peeling charge were measured, and the results are shown in Table 1. A release film with good transportability and workability was obtained.
(Example 2)
Addition reaction type curable silicone resin X62-2832 (manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts by weight, peeling control agent KS3800 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.85 parts by weight, adhesion improver X92-185 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.08 parts by weight, curing agent PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.09 parts by weight, n-peptane 75 parts by weight, toluene A release layer coating liquid 2 mixed in 20 parts by weight was prepared.

As the release layer, the release layer coating liquid 2 was used, and a polyethylene terephthalate film having a thickness of 75 μm (“Lumilar (registered trademark)” R41 manufactured by Toray Industries, Inc.) was used in the same manner as in Example 1. , A release film was prepared. The surface roughness, friction coefficient and peeling charge were measured, and the results are shown in Table 1. A release film with good transportability and workability was obtained.
(Example 3)
Additive reaction type curable silicone resin KS847H (manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts by weight, curing agent PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.04 parts by weight, silica particles QCB- A mold release layer coating liquid 3 was prepared by mixing 0.01 part by weight of 100 (manufactured by Shin-Etsu Silicone Co., Ltd.) with 50 parts by weight of toluene and 50 parts by weight of n-heptane.

The same as in Example 1 except that the release layer coating liquid 3 was used as the release layer and a polyethylene terephthalate film having a thickness of 75 μm (“Lumilar (registered trademark)” R74 manufactured by Toray Industries, Inc.) was used. , A release film was prepared. The surface roughness, friction coefficient and peeling charge were measured, and the results are shown in Table 1. A release film with good transportability and workability was obtained.
(Example 4)
A release film was produced in the same manner as in Example 1 except that a polyethylene terephthalate film having a thickness of 75 μm (“Lumilar (registered trademark)” R41 manufactured by Toray Industries, Inc.) was used without applying a primer layer. .. The surface roughness, friction coefficient and peeling charge were measured, and the results are shown in Table 1. A release film with good transportability and workability was obtained.
(Comparative Example 1)
The same as in Example 2 except that a polyethylene terephthalate film having a thickness of 75 μm (“Lumilar (registered trademark)” U483 manufactured by Toray Industries, Inc.) was used with the release layer set to 10 nm without applying a primer layer. , A release film was prepared. The surface roughness, friction coefficient and peeling charge were measured, and the results are shown in Table 1. Both transportability and workability were x.
(Comparative Example 2)
A release film was produced in the same manner as in Example 3 except that a polyethylene terephthalate film having a thickness of 75 μm (“Lumilar (registered trademark)” S28 manufactured by Toray Industries, Inc.) was used with the release layer set to 15 nm. The surface roughness, friction coefficient and peeling charge were measured, and the results are shown in Table 1. Both transportability and workability were x.
(Comparative Example 3)
0.03 part by weight of silica particles QCB-100 (manufactured by Shinetsu Silicone Co., Ltd.) is added to the release layer coating liquid 1, and the release layer is 200 nm, and a polyethylene terephthalate film having a thickness of 100 μm (manufactured by Toray Industries, Inc.) “ A release film was produced in the same manner as in Example 1 except that Lumirror (registered trademark) "T60) was used. The surface roughness, friction coefficient and peeling charge were measured, and the results are shown in Table 1. Both transportability and workability were x.
(Comparative Example 4)
A release film was produced in the same manner as in Comparative Example 2 except that the silica particles QCB-100 (manufactured by Shin-Etsu Silicone Co., Ltd.) of Comparative Example 2 were made 0.03 part by weight and the release layer was 200 nm. The surface roughness, friction coefficient and peeling charge were measured, and the results are shown in Table 1. The transportability was ×, but the workability was ○.
(Example 5)
[Preparation of adhesive]
(Preparation of base polymer)
2-Ethylhexyl acrylate (2EHA): 70 parts by weight, N-vinylpyrrolidone (NVP): 15 parts by weight, and hydroxyethyl as monomer components in a reaction vessel equipped with a thermometer, agitator, cooler and nitrogen gas inlet tube. Acrylate (HEA): 15 parts by weight, azobisisobutyronitrile as a thermal polymerization initiator: 0.2 parts by weight, α-thioglycerol (TGR) as a chain transfer agent: 0.12 parts by weight, ethyl acetate 233 by weight. It was added together with a weight portion and stirred for 1 hour in a nitrogen atmosphere at 23 ° C. to perform nitrogen substitution. Then, the reaction was carried out at 65 ° C. for 5 hours, followed by a reaction at 70 ° C. for 2 hours to prepare an acrylic base polymer solution.
(Preparation of UV curable pressure-sensitive adhesive composition)
In the acrylic base polymer solution obtained above, polypropylene glycol diacrylate (trade name: NK ester APG-400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) is used as a bifunctional acrylate having an ether bond with respect to 100 parts by weight of the base polymer. ): 7 parts by weight; Trimethylol propane adduct of xylylene diisocyanate as an isocyanate-based cross-linking agent (trade name: Takenate D110N, manufactured by Mitsui Chemicals, Inc.): 0.3 parts by weight; and 2,2 as a photopolymerization initiator. -Dimethoxy-1,2-diphenylethane-1-one (trade name: Irgacure 651, manufactured by BASF): After adding 0.1 part by weight, mix uniformly to prepare an ultraviolet curable pressure-sensitive adhesive composition. bottom.
(Preparation of laminated body)
Using the release film described in Example 2 as a second release film, the above-mentioned adhesive is applied onto the release layer surface so that the thickness after drying is 60 μm, and dried at 100 ° C. for 3 minutes. After removing the solvent, the release film described in Example 1 was used as the first release film, and the release layer surface thereof was laminated toward the adhesive side, and crosslinked by aging treatment in an atmosphere of 25 ° C. for 3 days. Was carried out, and a laminated body was obtained.

From the first release film side or the second release film side of the laminate, a ^{UV lamp with an energy density of long wavelength ultraviolet rays: 300 mW / cm 2} is used to irradiate ultraviolet rays with an integrated light amount of about 10,000 mJ / cm 2. , The adhesive was cured.

After curing, the dynamic friction coefficient and the amount of peeling charge on the non-release layer side of the first release film and the non-release layer side of the second release film were measured. The results are shown in Table 2.
(Example 6)
The laminate was the same as in Example 5, except that the first release film used the release film described in Example 4 and the second release film used the release film described in Example 3. It was created. The coefficient of dynamic friction and the amount of peeling charge on the non-release layer side of the first release film and the non-release layer side of the second release film of the produced laminate were measured. The results are shown in Table 2.
(Comparative Example 5)
The laminate was the same as in Example 5, except that the first release film used the release film described in Comparative Example 2 and the second release film used the release film described in Comparative Example 3. It was created. The coefficient of dynamic friction and the amount of peeling charge on the non-release layer side of the first release film and the non-release layer side of the second release film of the produced laminate were measured. The results are shown in Table 2.
(Comparative Example 6)
The laminate was the same as in Example 5, except that the first release film used the release film described in Comparative Example 3 and the second release film used the release film described in Comparative Example 4. It was created. The coefficient of dynamic friction and the amount of peeling charge on the non-release layer side of the first release film and the non-release layer side of the second release film of the produced laminate were measured. The results are shown in Table 2.
(Comparative Example 7)
The laminate was the same as in Example 5, except that the first release film used the release film described in Comparative Example 2 and the second release film used the release film described in Comparative Example 3. It was created. The coefficient of dynamic friction and the amount of peeling charge on the non-release layer side of the first release film and the non-release layer side of the second release film of the produced laminate were measured.

Claims (7)

A release film having a release layer provided on one side of a polyester film, the surface roughness (Sa) of the surface on the release layer side is 5 to 15 nm, and the 10-point average height (Rz) is 500 nm or less. , The surface roughness (Sa) of the surface on the polyester film side (hereinafter referred to as the non-release layer side) is 5 to 15 nm, and the surface on the non-release layer side after being pressure-contacted with the surface on the release layer side and peeled off. A release film for an adhesive sheet (hereinafter referred to as OCA (Optically Clear Adjust)) used for bonding optical films to each other , which has a peeling force of 10 to 20 N / 50 mm from the adhesive tape on the surface. The release film for OCA according to claim 1 , wherein the release force of the surface on the release layer side from the adhesive tape is 50 to 1000 mN / 50 mm. The release film for OCA according to claim 1 or 2, wherein the dynamic friction coefficient of the surface on the non-release layer side after pressure contact with the surface on the release layer side and peeling is 0.3 to 0.5. The release film for OCA according to any one of claims 1 to 3, wherein the release charge amount when unwound is 3.0 kV or less. A laminate containing the first release film, the pressure-sensitive adhesive sheet, and the second release film in this order, wherein the first release film and the second release film are all claimed 1 to 4. The release film according to any one of the above, the first release film and the second release film are both arranged so that the release layer is on the pressure-sensitive adhesive sheet side, and the first release film is used. The peeling force (F1) of the release layer side surface of the mold film from the adhesive tape is 50 to 100 mN / 50 mm, and the peeling force (F2) of the second release layer side surface of the release layer side from the adhesive tape. ) is 70~1000mN / 50mm, a ratio of their peel strength (F2 / F1) is 1.2 to 20, OCA laminate. The second release film after pressure contact with the surface on the release layer side and the surface on the non-release layer side of the first release film and the surface on the release layer side after peeling. The OCA laminate according to claim 5, wherein the coefficient of kinetic friction with the surface on the non-release layer side of the above is 0.5 or less. The OCA laminate according to claim 5 or 6, wherein the peeling charge amount at the time of unwinding is 3.0 kV or less.