JP2022036894A - Release film, release film with adhesive layer and film laminate - Google Patents

Abstract

To provide a release film that can make an adhesive layer surface smooth by suppressing irregularity of an adhesive layer surface, and, is excellent also in light release property.SOLUTION: A release film having a structure provided with a mold releasing layer on one side of a base film, in which the adhesion energy of the releasing layer is 35 mJ/m2 or larger and 39 mJ/m2 or smaller, and after an acrylic adhesive tape is adhered to the releasing layer, is cut into a size of 50 mm×300 mm, in this state, heating and holding for 1 hour at 100°C (preset temperature) in a hot air oven, after leaving to stand for 1 hour at 23°C and 50%RH, 180° peeling force under condition of tensile speed 300 mm/minute is 15 mN/cm or smaller.

Description

The present invention relates to a release film, a release film with an adhesive layer, and a film laminate.

As an example of a method for manufacturing a liquid crystal display device used as an image display device for a liquid crystal television, a computer display, a mobile phone, a digital camera, etc., a release film with an adhesive layer, that is, a release layer on one side of the adhesive layer is provided. When the pressure-sensitive adhesive layer is attached to a polarizing plate to produce a polarizing plate with an adhesive layer using a release film with an adhesive layer, which is formed by laminating a base film, and then bonded to a liquid crystal cell. Examples thereof include a method of peeling off the base film (release film) provided with the release layer and attaching the pressure-sensitive adhesive layer and the glass substrate of the liquid crystal cell to the production.

In recent years, as the size of displays has increased, the dimensions of optical members such as polarizing plates and release films have increased, and the release films used in the manufacture of liquid crystal display devices as described above are light even if the peeling area is large. There is a growing demand for properties that can be peeled off.
Silicone is a material excellent in the property of being able to be peeled off with a small force (also referred to as "light peeling property") due to the flexibility of the siloxane skeleton and the low surface energy due to the substitution of a methyl group. Therefore, as a release film for protecting the adhesive for adhering optical members, for example, members constituting a liquid crystal display, a heat / ultraviolet curable silicone release agent containing a silicone resin as a main component is cured. A release film provided with a release layer is attracting attention.

Regarding the release film provided with the release layer containing silicone as the main component resin, for example, in Patent Document 1, the release is light at the time of peeling, the holding power at the time of storage is excellent, and the air exposure resistance and non-migration property are improved. An excellent release film is a release film in which at least one side of a polyester film is coated with a paint containing a curable silicone as a main component resin, and the paints are solvent-type curable silicone and solvent-free curable silicone. Disclosed is a release film containing a reactive heavy peeling adjusting agent as a main component and having a specific range of the ratio of SiH group to vinyl group in the coating material.

Patent Document 2 contains a reactive silicone resin having a hexenyl group, a vinyl group, a phenyl group, and a hydrosilyl group as functional groups, an unreactive silicone resin having a mass average molecular weight of 50,000 to 100,000, and a platinum-based catalyst. Disclosed is a release film characterized by having a silicone-based release layer formed from a coating liquid on one side of the polyester film.

Patent Document 3 describes a release film having a release layer on at least one side of a polyester film, and the composition forming the release layer is a curable silicone (A) having a number average molecular weight of 50,000 or more. The curable silicone (B) containing a curable silicone (B) having a number average molecular weight of 30,000 or less has a T unit structure, and the curable silicone (B) has a T unit structure in a polysiloxane chain. A release film is disclosed, wherein the content ratio of the above is 3 mol% or more in siloxane units.

By the way, optical members such as polarizing plates and touch sensors may be distributed in a form in which an adhesive layer and a release film are laminated. For example, a protective film is laminated on one surface of an optical member so as to be peelable via a light adhesive layer, and a release film with an adhesive layer is laminated on the other surface, that is, a release film / It may be distributed in the form of an adhesive layer / optical film / light adhesive layer / protective film.
At this time, if the peeling force when peeling the release film from the adhesive layer is larger than the adhesive force between the optical member and the light adhesive layer, the phenomenon that the protective film is peeled off first, the so-called "crying farewell phenomenon" occurs. It could occur. Therefore, the release film with an adhesive layer used for optical applications is required to have excellent light peelability that can be peeled off with even smaller force.

Further, conventionally, even if the surface of the adhesive layer (also simply referred to as “the surface of the adhesive layer”) on the side of the release film with the adhesive layer that is not in contact with the release film has some irregularities, the surface of the adhesive layer is an optical member. It was not a problem because it was bonded to. However, in recent years, as each member has become thinner and quality requirements for optical properties have increased, unevenness on the surface of the pressure-sensitive adhesive layer in the release film with a pressure-sensitive adhesive layer has become an issue. That is, if the surface of the adhesive layer is uneven, distortion occurs at the interface between the adhesive layer and the optical member when the adhesive layer is attached to the optical member, and the distortion causes light to be scattered, which hinders accurate optical inspection. Sometimes became.
Therefore, with respect to the release film with an adhesive layer, the surface of the adhesive layer on the side not in contact with the release film is required to be smooth with few irregularities.

Japanese Unexamined Patent Publication No. 2009-214359 Japanese Unexamined Patent Publication No. 2016-188265 Japanese Unexamined Patent Publication No. 2020-108937

As a result of investigating the cause of unevenness on the surface of the adhesive layer on the side not in contact with the release film with respect to the release film with the adhesive layer, the present inventor mainly causes 2 due to the interaction between the release layer and the adhesive layer. It was found that unevenness is formed on the surface of the adhesive layer due to one cause. That is, if the surface of the release layer is uneven, the surface of the adhesive layer may be uneven due to the effect, and the incompatible component is eluted from the release layer to the adhesive layer side, so that the adhesive layer is adhered. As a result of cissing when the composition is applied, or the incompatible component invading the adhesive layer to form a phase release structure, the surface of the adhesive layer may be uneven. I found it.

Therefore, the present invention relates to a release film and a release film with an adhesive layer, a new release film capable of suppressing unevenness on the surface of the adhesive layer and smoothing the surface, and yet having excellent light peelability, as well as a new release film. , A new release film with an adhesive layer and a film laminate using this are intended to be provided.

The present invention is a release film having a structure in which a release layer is provided on one side of a base film, and the adhesion energy of the release layer is 35 mJ / m ² or more and 39 mJ / m ² or less. Acrylic adhesive tape is attached to the release layer, cut into a size of 50 mm x 300 mm, and in that state, heated and held at 100 ° C (set temperature) for 1 hour in a hot air oven, and then 23 ° C, 50%. We propose a release film having a 180 ° peeling force of 15 mN / cm or less under the condition of a tensile speed of 300 mm / min after being allowed to stand in RH for 1 hour.

The present invention also proposes a release film provided with a release layer formed by curing the release layer composition on one side of the base film.
At this time, as the release layer composition, a release layer composition containing a curable silicone resin having a number average molecular weight (Mn) of 20,000 or more and 350,000 or less as a main component resin, or 0. We propose a release layer composition containing 01 to 5.0 mol% of phenyl groups.

The present invention also proposes a release film with an adhesive layer having a structure in which an adhesive layer is laminated on the release layer of the release film.

The present invention further proposes a film laminate having a structure in which an optical member is bonded to the surface of the pressure-sensitive adhesive layer of the release film with a pressure-sensitive adhesive layer.

The release film, the release film with an adhesive layer, and the film laminate proposed by the present invention are not only excellent in light peelability, but also can suppress unevenness on the surface of the adhesive layer to obtain excellent smoothness. Therefore, the release film, the release film with an adhesive layer, and the film laminate proposed by the present invention can be particularly suitably used for optical applications.

An adhesive layer is formed on the release layer surface (also referred to as “release surface”) of the release film (sample film) obtained in Example 1, and the surface of the adhesive layer is referred to by Bruker Japan Co., Ltd. ) Image data (5 times) measured for a region of 928 × 1235 μm using a Control GT. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Example 2 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Example 3 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 1 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 2 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 3 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 4, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 5 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 6 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 7, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 8 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area. An adhesive layer is formed on the release surface of the release film (sample film) obtained in Comparative Example 9 as described later, and the surface of the adhesive layer is 928 × 1235 μm using Contour GT manufactured by Bruker Japan Co., Ltd. Image data (5 times) measured for the area.

Next, an example of the embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described below.

<<< Release film >>>
The release film (referred to as “main release film”) according to an example of the embodiment of the present invention has a release layer (“main release type”) on at least one side of the base film (referred to as “main base film”). It is a release film provided with a layer).

The release type film may be provided with the main release type layer on one side of the main base film, and as described later, the main release type film is provided with another layer between the main base film and the main release type layer. May be good.

<< This base film >>
The material of the base film is not particularly limited as long as it is in the form of a film. For example, it may be made of paper, resin, metal, or the like. Among these, it is preferably made of resin from the viewpoint of mechanical strength and flexibility.

Examples of the resin-made base film include a film formed by forming a polymer such as polyethylene, polypropylene, polyester, polystyrene, polycarbonate, polyether sulfone, polyamide, and polyimide into a film. Further, as long as it can be formed into a film, it may be a mixture of these materials (polymer blend) or a composite of structural units (copolymer).

Among the films exemplified above, the polyester film is particularly preferable because it has excellent physical properties such as heat resistance, flatness, optical properties, and strength.
The polyester film may be a single layer or a multilayer film (laminated film) having two or more layers having different properties.
Further, the polyester film may be a non-stretched film (sheet) or a stretched film. Above all, a stretched film stretched in the uniaxial direction or the biaxial direction is preferable. Among them, a biaxially stretched film is more preferable from the viewpoint of balance of mechanical properties and flatness.

The polyester which is the main component resin of the polyester film may be a homopolyester or a copolymerized polyester.
The "main component resin" means the resin having the largest mass ratio among the resins constituting the present polyester film, and is 50% by mass or more or 75% by mass or more of the resin constituting the present polyester film. , Or 90% by mass or more, or 100% by mass is assumed.

The homopolyester is preferably obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. At this time, examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,4. -Cyclohexanedimethanol and the like can be mentioned.
As a typical homopolyester, polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and the like can be exemplified.

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

Among them, as the present base film, polyethylene terephthalate in which 60 mol% or more, preferably 80 mol% or more is an ethylene terephthalate unit is preferable.

The base film may contain particles for the main purpose of imparting slipperiness and preventing scratches in each step.
When the particles are blended, the type of the particles to be blended is not particularly limited as long as the particles can be easily slipped, and for example, silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, phosphorus. Examples thereof include inorganic particles such as magnesium acid, kaolin, aluminum oxide and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin and benzoguanamine resin. Further, during the polyester production process, precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed can also be used.

The shape of the particles is not particularly limited. For example, it may be spherical, lumpy, rod-shaped, flat-shaped, or the like. Further, there are no particular restrictions on the hardness, specific gravity, color, etc. of the particles. Further, if necessary, two or more kinds of particles having different physical characteristics may be used in combination.

The average particle size of the particles is preferably 0.1 μm or more and 5 μm or less, and more preferably 0.5 μm or more or 4 μm or less, and more preferably 1 μm or more or 4 μm or less. By using particles having such an average particle size, it is possible to give an appropriate surface roughness to the film and secure good slipperiness and smoothness.

Regarding the particle content in the base film, when there are no or few particles, the transparency of the film is high, but the slipperiness may be insufficient. On the other hand, if the particle content is too high, the transparency of the film may be insufficient. From this point of view, the particle content in the base film is preferably 5% by mass or less, and more preferably 0.1% by mass or more or 3% by mass or less.
In applications that require a high level of inspection, there may be a problem that the convex shape derived from particles existing on the surface of the substrate film is transferred to the adhesive layer. Therefore, it may be preferable that at least one side surface or both side surfaces of the substrate film are configured so that the particles do not exist so that the particles do not interfere with the inspection. In addition, the amount of particles on both the front and back sides is increased by reducing the amount of particles on the surface in contact with the adhesive layer or reducing the particle size to smooth the surface while increasing the surface roughness of the opposite surface. Alternatively, the particle sizes may be different from each other.

<< This release layer >>
The release type layer is a layer formed by curing a release layer composition (referred to as "main release type layer composition") containing a curable silicone resin ("main cure type silicone resin") as a main component resin. , Is arranged on at least one side of the substrate film.
It can also be said that the release layer is a release layer containing a cured product obtained by curing the release layer composition.

<Main release layer composition>
The release type layer composition may be a composition containing a curable silicone resin as a main component resin.
The release-type layer composition may contain components other than the curable silicone resin, and if necessary, for example, a catalyst, a reaction control agent, a cross-linking agent, a polymerization initiator, particles, a diluting solvent, and the like. Additives can be included.

The above-mentioned "main component resin" means a resin having the largest mass ratio among the resins constituting the present release type layer composition, and is 50% by mass or more of the resin constituting the present release type layer composition. , Or 75% by mass or more, 90% by mass or more, or 100% by mass is assumed.

The main release layer composition to the main release layer contains 0.01 to 5.0 mol% of phenyl with respect to the total amount of the siloxane component, that is, the total amount of the siloxane component contained in the main release layer composition or the main release layer. It preferably contains a group.
The alkenyl group (for example, vinyl group, hexenyl group) or Si that may remain on the surface of the release type layer because the release type layer composition or the main release type layer contains a predetermined amount of phenyl group. -The H group can be coated, the interaction between the release type layer and the adhesive layer can be reduced, and further light peeling effect can be expected to be exhibited.
From this point of view, the release type layer composition or the present release type layer preferably contains 0.01 to 5.0 mol% of phenyl groups with respect to the total amount of siloxane components, and more than 0.05 mol% or more. It is particularly preferable that the phenyl group contains 4.0 mol% or less, particularly 0.1 mol% or more or 3.0 mol% or less, and more preferably 0.2 mol% or more or 2.0 mol% or less.

In order for the release layer composition or the release layer to contain phenyl groups in the above proportions, a curable silicone resin containing phenyl groups in a predetermined proportion may be used. However, the method is not limited to this method. For example, a compound containing a phenyl group, for example, a non-curable silicone resin having a phenyl group, a silane compound, or the like may be added.

Further, when the amount of the alkenyl group, that is, the residual functional group having a double bond such as a hexenyl group or a vinyl group is small with respect to the total amount of the siloxane component, the main release layer composition or the main release layer is released from the mold. The layer may not be sufficiently cured, while a large excess of alkenyl groups tends to increase the peeling force after air exposure. From this, it is preferable that the release type layer composition to the present release type layer contains 0.4 to 1.0 mol% of alkenyl groups with respect to the total amount of siloxane components, and more than 0.5 mol% or more. It is particularly preferable that the alkenyl group is contained in an amount of 0.9 mol% or less, particularly 0.6 mol% or more or 0.8 mol% or less.
Further, in the release layer composition or the release layer, if the Si—H group amount is small with respect to the total siloxane component amount, the release layer is not sufficiently cured, while the Si—H group amount is large. If it is excessive, the remaining Si—H groups may react with the adhesive layer, which may affect the heavy release of the release film. From this, the release type layer composition to the present release type layer preferably contains 0.8 to 2.2 mol% of Si—H groups with respect to the total amount of siloxane components, and more preferably 1.2 mol%. It is particularly preferable that the Si—H group is contained in an amount of 2.1 mol% or less, particularly preferably 1.4 mol% or more or 2.0 mol% or less.

The total siloxane component content in the main release layer composition to the main release layer can be measured by, for example, 1H-NMR from the integral ratio of the dimethylsiloxane unit of the main chain and the other units, and the phenyl group content. , The content of the alkenyl group and the Si—H group can also be evaluated by measuring, for example, 1H-NMR. However, the method is not limited to this method.

<Main curable silicone resin>
In the present invention, the "curable silicone resin" means a silicone resin having a property of being curable. In addition, those that can be cured by mixing a cross-linking agent in advance are also included.
The curing method of the curable silicone resin is arbitrary. For example, even if it has the property of reacting with moisture in the air and curing by a condensation reaction, or the one having the property of curing by an addition reaction by heating, it is addition-polymerized or radically polymerized by light. It may have the property of being cured.
Of these, a thermosetting silicone resin that cures by an addition reaction due to heating is preferable because there are no by-products of the curing reaction and the physical properties of the cured film are stable.
When the present curable silicone resin is a heat-curable type, an alkenyl group such as a vinyl group (Vi group) or a hexenyl group is introduced into the side chain and / or the terminal of the main chain composed of a siloxane bond in the structure. Is preferable.

The present curable silicone resin may be a polymer having a siloxane bond consisting of silicon and oxygen as a main chain.
Examples of the present curable silicone resin include those in which various substituents are introduced into the side chain or the end of the main chain composed of a siloxane bond. At this time, examples of the substituent include any one of a methyl group, a phenyl group, a polyether group, an epoxy, amines, a carboxyl group, an aralkyl group, and the like, or a combination of two or more thereof.

As an example of a method for making the main release layer composition or the main release layer contain phenyl groups in a predetermined ratio, it contains 0.01 to 5.0 mol% of phenyl groups, and more than 0.05 mol% among them. Alternatively, an example of using this curable silicone resin containing a phenyl group of 4.0 mol% or less, particularly 0.1 mol% or more or 3.0 mol% or less, and among them 0.2 mol% or more or 2.0 mol% or less. Can be mentioned.
At this time, it is more preferable that the molar ratio of the phenyl group (phenyl group / methyl) to the methyl group of the present curable silicone resin is 0.0001 to 0.05, and more preferably 0.0005 or more or 0.04 or less. Among them, 0.001 or more or 0.03 or less, and more preferably 0.02 or more or 0.02 or less.

As an example of this curable silicone resin, either a phenyl group, a Si—H group (also simply referred to as “H group”), an alkenyl group, or these are attached to the side chain or the terminal of a linear main chain composed of a siloxane bond. Examples thereof include silicone resins in which two or more types have been introduced.
At this time, the content of the phenyl group in the present curable silicone resin is preferably 0.01 to 5.0 mol%, particularly 0.05 mol% or more or 4.0 mol% or less, and among them, 0.1 mol% or more or It is more preferably 3.0 mol% or less, more preferably 0.2 mol% or more or 2.0 mol% or less.
Similarly, at this time, the content of Si—H groups in the present curable silicone resin is preferably 0.8 to 2.2 mol%, particularly 1.2 mol% or more or 2.1 mol% or less, and 1.4 mol among them. It is more preferably% or more or 2.0 mol% or less.
Similarly, at this time, the content of the vinyl group in the present curable silicone resin is preferably 0.4 to 1.0 mol%, particularly 0.4 mol% or more or 1.0 mol% or less, and among them, 0.6 mol% or more. Alternatively, it is more preferably 0.9 mol% or less.

The present curable silicone resin may be a combination of two or more types of curable silicone resins. In that case, the content ratio of each of the above-mentioned functional groups is preferably such that the average value of two or more types of curable silicone resins is within the above range.

The number average molecular weight (Mn) of the present curable silicone resin is preferably 20,000 or more and 350,000 or less.
If the number average molecular weight (Mn) of the present-curable silicone resin is too low, the amount of the low-molecular-weight silicone resin eluted or transferred to the adhesive layer when the adhesive layer is laminated on the release-type film is not preferable. Even if the release layer is thickly applied, the light peeling effect tends to be poor. On the other hand, if the number average molecular weight (Mn) of the present-curing silicone resin is too high, the viscosity becomes high and the fluidity of the present-release layer composition decreases, and when the present-release layer composition is applied, the present-release layer composition is applied. It is not preferable because streaky coating unevenness occurs and it becomes difficult to smooth the surface of the release type layer.
From this point of view, the number average molecular weight (Mn) of the present curable silicone resin is preferably 20,000 or more, more preferably 50,000 or more, particularly 100,000 or more, and particularly 150,000 or more. preferable. On the other hand, it is preferably 350,000 or less, more preferably 300,000 or less, and particularly preferably 250,000 or less.

From the same viewpoint, the mass average molecular weight (Mw) of the present curable silicone resin is preferably 35,000 to 600,000, particularly 50,000 or more or 500,000 or less, particularly 100,000 or more or 450,000 or less, and particularly 120,000 or more. Is even more preferable.

In this curable silicone resin, the ratio (Mw / Mn) of the mass average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 1.7 to 2.7, and above all, 1.9 or more or 2.5. The following is more preferable. By satisfying this range, it can be expected that the crosslinking reaction will proceed efficiently.

The present curable silicone resin may be composed of a combination of two or more types of curable silicone resins, and in that case, it is preferable that the average of the molecular weights of the two or more types of curable silicone resins is within the above range. ..

The present curable silicone resin preferably has a viscosity of 10 to 400 mcps at 25 ° C. when its content is adjusted to 15% by mass by diluting with an n-heptane solvent.
When the viscosity of the present curable silicone resin is 10 mcps or more, repelling is suppressed by an appropriate viscosity of the coating liquid, and a good coat appearance can be obtained, which is preferable. On the other hand, when the viscosity is 400 mcps or less, the fluidity of the release layer composition can be maintained, and when the release layer composition is applied, it is possible to suppress the occurrence of streak-like coating unevenness. This is preferable because the surface of the release layer can be smoothed.
From this point of view, the viscosity of the present curable silicone resin is more preferably 40 mcps or more, and more preferably 80 mcps or more. On the other hand, it is more preferably 300 mcps or less, and more preferably 200 mcps or less.

The present curable silicone resin may be either a solvent-free curable silicone or a solvent-curable silicone. Moreover, you may use both in combination.
Here, the "solvent-free curable silicone" is a silicone having a viscosity that can be applied without being diluted with a solvent, has a short polysiloxane chain, and has a relatively low molecular weight.
On the other hand, the "solvent-type curable silicone" is a silicone having a viscosity so high that it cannot be coated unless it is diluted with a solvent, and is a silicone having a relatively high molecular weight as compared with the solvent-free curable silicone.
Above all, the present curable silicone resin preferably has a medium number average molecular weight (Mn) and a medium viscosity as described above, and further, the adhesion to the base film is good, and the adhesion to the base film is good. The solvent-type curable silicone is preferable from the viewpoint that the coating appearance (unevenness) is good and the film thickness of the release type layer can be easily adjusted.

<Other ingredients>
As described above, the present release type layer composition may contain, for example, a curing catalyst, particles, a diluting solvent, a reaction control agent, a cross-linking agent, a polymerization initiator, an adhesion strengthening agent, as required, in addition to the present curing type silicone resin. Other additives can be contained.
For example, as an example of the present release layer composition, a catalyst containing a present curable silicone resin, a cross-linking agent having a hydrosilyl group (SiH group) at the side chain and / or the terminal of a main chain composed of a siloxane bond, and platinum (Pt). , And a composition containing a solvent.

(catalyst)
The release-type layer composition promotes a hydrosilylation addition reaction between a curing catalyst, that is, an alkenyl group bonded to a silicon atom of a curing silicone, and a hydrogensilane (SiH) group of a silicone cross-linking agent, if necessary. May contain a catalyst for the purpose.
Examples of the curing catalyst include platinum black, second platinum chloride, platinum chloride acid, a reaction product of platinum chloride acid and a monovalent alcohol, a complex of platinum chloride acid and olefins, and a platinum-based catalyst such as platinum bisacetacetate. Examples thereof include platinum group metal catalysts such as palladium catalysts and rhodium catalysts. However, it is not limited to these.

The content of the curing catalyst in the main release layer composition is preferably 0.5 to 500 mass ppm as a metal equivalent amount with respect to the main curable silicone, and above all, 5 mass ppm or more or 300 mass ppm. Hereinafter, among them, it is more preferably 10 mass ppm or more or 200 ppm or less.

(Crosslinking agent)
The cross-linking agent is preferably a cross-linking agent having a siloxane bond (also referred to as “silicone cross-linking agent”). Among them, those having a silicon atom-bonded hydrogen atom (SiH group) at the side chain and / or the terminal of the main chain composed of a siloxane bond are preferable.

For example, it is represented by the following general formula (1), and at least 2, preferably 3 or more (usually about 3 to 200), more preferably 3 to 100, and particularly 3 to 50 in one molecule. Examples thereof include those having a silicon atom-bonded hydrogen atom (SiH group).

R _b H _c SiO _{(4-bc) / 2} (1)

In formula (1), R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms. Further, b is 0.7 to 2.1, particularly 0.8 to 2.0, c is 0.001 to 1.0, and b + c is 0.8 to 3.0, particularly 1.0 to 2. It is a positive number that satisfies 5.

Here, as R, the same group as R in the alkenyl group-containing organopolysiloxane can be mentioned, but those having no aliphatic unsaturated bond such as an alkenyl group are preferable.

This silicon atom-bonded hydrogen atom is bonded to both of these, whether it is bonded to a silicon atom at the end of the molecular chain or to a silicon atom in the middle of the molecular chain (non-terminal of the molecular chain). It may be a thing.

The molecular structure of the silicone cross-linking agent may be linear, cyclic, branched, or three-dimensional network structure.
Further, the number of silicon atoms (or degree of polymerization) in one molecule is preferably 2 to 1,000, particularly 3 or more or 500 or less, particularly 3 or more or 300 or less, and particularly 4 or more or 150 or less. It is even more preferable to have it.

Examples of the silicone cross-linking agent include tris (dimethylhydrogensiloxy) methylsilane, tris (dimethylhydrogensiloxy) phenylsilane, 1,1,3,3-tetramethyldisiloxane, and 1,3,5,7-tetramethyl. Cyclotetrasiloxane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, double-ended trimethylsiloxy group-blocked methylhydrogenpolysiloxane, double-ended trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane co-weight Combined, both-ended dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, both-ended dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane, both-ended dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both-ended trimethyl Syloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, both-terminal trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane / dimethylsiloxane copolymer, (CH ₃ ) ₂ HSiO _1/2 unit and SiO _4/2 unit In the copolymers consisting of (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units and (C ₆ H ₅ ) SiO _3/2 units, etc., and examples of these compounds. Examples thereof include those in which a part or all of the methyl group is replaced with another alkyl group such as an ethyl group or a propyl group, or an aryl group such as a phenyl group. However, it is not limited to these.

(particle)
The release type layer composition may contain particles as a measure for adjusting the peeling force or preventing blocking, if necessary.
At this time, the type of the particles is not particularly limited as long as the particles can impart the above-mentioned characteristics, and for example, silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, etc. Examples thereof include inorganic particles such as aluminum oxide and titanium oxide, and organic particles such as silicone resin, acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin and benzoguanamine resin.
Among them, it is preferable that the particles are composed of a silicone resin from the viewpoint of good compatibility with the silicone resin which is a binder resin component.

The shape of the particles is not particularly limited. For example, it may be spherical, lumpy, rod-shaped, flat-shaped, or the like.
Further, there are no particular restrictions on the hardness, specific gravity, color, etc. of the particles.
Two or more kinds of these particles may be used in combination, if necessary.

(Diluting solvent)
The release type layer composition can contain a diluting solvent, if necessary.
Examples of the diluting solvent include aromatic hydrocarbons such as toluene, aliphatic hydrocarbons such as hexane, heptane and isooctane, esters such as ethyl acetate and butyl acetate, ethyl methyl ketone (MEK) and isobutyl methyl ketone. Examples thereof include ketones such as ketones, ethanol, alcohols such as 2-propanol, ethers such as diisopropyl ether and dibutyl ether, and the like. It is preferable to use these individually or in combination in consideration of solubility, coatability, boiling point and the like.

(Reaction control agent)
The release type layer composition can contain a reaction control agent, if necessary.
Examples of the reaction control agent include acetylene alcohol and the like.
One type of reaction control agent may be used, or two or more types may be used in combination, if necessary.
The content of the reaction control agent is preferably 0.001 to 5.0 parts by mass, particularly 0.01 parts by mass or more or 1.0 part by mass or less, per 100 parts by mass of the total amount of the main release layer composition. Among them, it is more preferably 0.05 part by mass or more or 0.5 part by mass or less.

<Thickness of this release layer>
The thickness of the release type layer is not particularly limited. If the thickness of the release layer is large, it is difficult to transmit the influence of the base film, for example, the influence of the hardness of the base film to the release surface of the release film, which is preferable. From this point of view, it is preferably 0.01 μm or more, more preferably 0.05 μm or more, and further preferably 0.10 μm or more. On the other hand, if the thickness of the release layer is too thick, blocking may occur and the appearance of the coat may be deteriorated. Therefore, the thickness is preferably 10 μm or less, particularly 5.0 μm or less, and 2.0 μm among them. Hereinafter, it is particularly preferable that it is 1.0 μm or less, and more preferably 0.50 μm or less.

<< Other layers >>
The release film may include an "other layer" between the substrate film and the release layer.
Examples of the "other layer" include an anchor coat layer for enhancing the adhesion between the base film and the release type film, and exudation (bleeding, plate-out) of a compound or oligomer onto the film surface. In addition to the oligomer-sealing layer to be sealed, an antistatic layer having antistatic properties can be mentioned. However, it is not limited to these.

<< Manufacturing method of this release film >>
In the release type film, a coating layer such as an antistatic layer or an oligomer-sealing layer is formed on one side or both sides of the base film, if necessary, and then the release layer composition is formed on these surfaces. It can be manufactured by applying an object, drying it, and curing it.

As a method for applying the main release layer composition, conventionally known coating methods such as multi-roll coat, reverse gravure coat, direct gravure coat, bar coat, and die coat can be used. Regarding the coating method, there is a description example in "Coating method" (published by Yuji Harasaki, Maki Shoten, 1979).

Before applying the release type layer composition, the polyester film may be subjected to surface treatment such as corona treatment and plasma treatment in advance.

The amount of the release layer composition applied, that is, the thickness of the release layer (after drying) is determined from the viewpoint of preventing blocking and suppressing the increase in transferability (that is, the characteristic that the release agent component is transferred to the adhesive tape or the like). , It is preferable to make it thinner. On the other hand, from the viewpoint of maintaining light peelability (low peeling force), it is preferable to make the thickness thicker.
In consideration of this point, the coating amount of the main release layer composition, that is, the thickness of the main release layer (after drying) is preferably 0.1 to 5.0 g / m ² , and more preferably 0. .2 g / m ² or more or 3.0 g / m ² or less, more preferably 0.3 g / m ² or more or 2.0 g / m ² or less.

When the release type layer composition is cured by heating, it may be heated using a conventionally known heat treatment apparatus. For example, a heating oven, a hot plate, a hot air dryer, a near-infrared lamp, an air dryer and the like can be exemplified. The heat treatment temperature is preferably 35 to 220 ° C., more preferably 40 ° C. or higher or 200 ° C. or lower, and even more preferably 50 ° C. or higher or 180 ° C. or lower.
Further, the heat treatment time is preferably 3 seconds to 3 minutes, particularly preferably 5 seconds or more or 2 minutes or less, and particularly preferably 5 seconds or more or 1 minute or less.

On the other hand, when the release layer composition is cured by ultraviolet irradiation, it can be irradiated with ultraviolet rays using a conventionally known ultraviolet irradiation device. At this time, as the light source, for example, a fusion (H) lamp, a metal halide lamp, a high-pressure mercury lamp (ozone generation type, ozoneless type), a UV-LED, or the like can be used.

The amount of ultraviolet irradiation is not particularly limited. In terms of integrated light quantity, it is preferably 10 to 3000 (mJ / cm ² ), among which 50 (mJ / cm ² ) or more or 2000 (mJ / cm ² ) or less, and 100 (mJ / cm ² ) or more or 100 (mJ / cm 2) or more. It is particularly preferably 1500 (mJ / cm ² ) or less.

<< Physical characteristics of this release film >>
The release film can have the following physical characteristics.

<Adhesion energy>
The adhesion energy of the release layer in the release film is preferably 35 mJ / m ² or more and 39 mJ / m ² or less, and more preferably 36 mJ / m ² or more or 39 mJ / m ² or less. Above all, it is more preferably 36 mJ / m ² or more or 38 mJ / m ² or less.
When the adhesion energy of the release type layer satisfies the above range, the present release type layer forms a surface having appropriate wettability, and even when the adhesive layer is provided on the main release type layer, the main release type layer is released. Elution of the incompatible component from the mold layer to the adhesive layer side causes repelling when the adhesive layer composition is applied, or the incompatible component invades into the adhesive layer and has a phase release structure. It is possible to obtain light releasability while suppressing the formation of.

<Elastic modulus>
The elastic modulus of the release layer in the release film is 0.1 MPa or more, preferably 0.2 MPa or more, and particularly preferably 0.5 MPa or more. On the other hand, the upper limit value is preferably 8.0 MPa or less, more preferably 6.0 MPa or less, and particularly preferably 5.0 MPa or less.
When the release type layer simultaneously satisfies the above ranges with respect to the adhesion energy and the elastic modulus, the surface of the adhesive layer formed on the main release type layer can maintain the smoothness.

The adhesion energy and elastic modulus of this release layer are determined by using an atomic force microscope (trade name: SPM-9700HT, manufactured by Shimadzu Corporation) with a silicon probe (team nanotec, LRCH, radius of curvature: 250 nm, spring constant:). It can be calculated according to the JKR two-point method based on the force curve obtained by attaching 0.2 N / m) and tapping at 600 m / s.

<Heat peeling force>
This release film is an acrylic adhesive tape, for example, Nitto Denko No. After laminating 502, cutting into a size of 50 mm × 300 mm, heating and holding in a hot air oven at 100 ° C (set temperature) for 1 hour, and then allowing to stand at 23 ° C and 50% RH for 1 hour. Satisfies the 180 ° peeling force under the condition of a tensile speed of 300 mm / min, that is, the peeling force when the acrylic adhesive tape is peeled 180 ° under the condition of a tensile speed of 300 mm / min, which is 15 mN / cm or less. Is preferable. Above all, 14 mN / cm or less, and above all, 11 mN / cm or less is more preferable.
The peeling force can be measured using, for example, a tensile tester (“EZgraph” manufactured by Shimadzu Corporation). However, the present invention is not limited to such a testing machine.

<<< Release film with adhesive layer >>>
A release film with an adhesive layer (referred to as a "release film with an adhesive layer") having an adhesive layer ("the adhesive layer") on the release layer of the release film using the release film. ) Can be produced.

<Smoothness (mapping property) of the surface of this adhesive layer>
The release film with the adhesive layer can have a image quality value of 70 or more on the surface of the adhesive layer, that is, the surface of the adhesive layer on the side not in contact with the release film, and more preferably 75 or more. Can be. Satisfying such a mapping property value indicates that the surface of the present adhesive layer is extremely smooth.

In order for the surface of the adhesive layer in the release film with the adhesive layer to satisfy the above-mentioned image quality value, as described above, the number average molecular weight (Mn) of the present-curable silicone resin forming the present-release layer is determined. By adjusting the content of the phenyl group in the release layer composition or the release layer to a predetermined range while adjusting the content to a predetermined range, the unevenness of the surface of the release layer can be suppressed, and the present invention can be suppressed. As a result of suppressing the elution of the incompatible component to the adhesive layer side, the unevenness of the surface of the adhesive layer can be suppressed and smoothed.

<Arithmetic mean height (Sa) on the surface of the adhesive layer>
In the release film with the present adhesive layer, the arithmetic average height (Sa, ISO 25178 surface texture) of the surface of the main adhesive layer, that is, the surface of the main adhesive layer on the side not in contact with the main release film is 53 nm or less. It can be 35 nm or less, particularly preferably 30 nm or less, and particularly preferably 25 nm or less.

The arithmetic mean height (Sa, ISO25178 surface texture) is a parameter obtained by extending the arithmetic average roughness Ra in three dimensions, and is the average of the absolute values of the differences in height of each point with respect to the average surface of the surface. It is a numerical value representing.

<< This adhesive layer >>
The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive composition (referred to as "the present pressure-sensitive adhesive composition") onto the release-type film and curing the pressure-sensitive adhesive composition.

<This adhesive composition>
The present pressure-sensitive adhesive composition is mainly composed of a urethane-based resin, whether it is an acrylic-based pressure-sensitive adhesive composition containing an acrylic resin as a main component resin or a rubber-based pressure-sensitive adhesive composition containing rubber as a main component. The urethane-based pressure-sensitive adhesive composition may be a silicone-based pressure-sensitive adhesive composition, or may be a silicone-based pressure-sensitive adhesive composition containing a silicone resin as a main component.
Among them, the present pressure-sensitive adhesive composition is preferably an acrylic pressure-sensitive adhesive composition containing an acrylic resin as a main component because the pressure-sensitive adhesive force and the peeling power can be adjusted in a well-balanced manner and the cost is low.

The above-mentioned "main component resin" means a resin having the highest mass ratio among the resins constituting the present pressure-sensitive adhesive composition. For example, it means a component which occupies 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more of the total amount of the resin constituting the present pressure-sensitive adhesive composition. The upper limit is usually 99.99% by mass.

In addition to the above-mentioned main components, the present pressure-sensitive adhesive composition may contain, for example, a silane coupling agent, an antistatic agent, other acrylic pressure-sensitive adhesives, other pressure-sensitive adhesives, urethane resins, and rosins, in addition to the cross-linking agents described below. , Rosin ester, hydrogenated rosin ester, phenol resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene resin, xylene resin and other adhesives, colorants, fillers, Conventionally known additives such as antiaging agents, ultraviolet absorbers, and functional dyes, and additives such as compounds that cause color development or discoloration by ultraviolet rays or irradiation with radiation can be blended.
The blending amount of these additives is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly 5% by mass or less, and the molecular weight of the additive is 10,000. It is preferable that a low molecular weight component lower than the above is not contained as much as possible in terms of excellent durability.

(Acrylic resin)
Examples of the acrylic resin which is the main component resin of the pressure-sensitive adhesive composition include (meth) acrylic polymers.

The (meth) acrylic polymer is a polymer having a (meth) acrylic acid alkyl ester as a main constituent unit.
Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, n-propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, and n- (meth) acrylic acid. Butyl, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate and n-hexyl (meth) acrylate, (meth) acrylate Examples thereof include isobornyl, 4-t-butylcyclohexyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentaenyl (meth) acrylate, and adamantyl (meth) acrylate. These may be used alone or in combination of two or more. Among these, methyl (meth) acrylate is preferable from the viewpoint of compatibility of the (meth) acrylic polymer with (meth) acrylate and heat resistance of the cured resin layer. The (meth) acrylic polymer may have a radically polymerizable double bond.

The (meth) acrylic polymer is a (meth) acrylic acid ester other than the (meth) acrylic acid alkyl ester, (meth) acrylic acid, and others for the purpose of improving the glass transition temperature, mechanical properties, compatibility, etc. A compound having a vinyl group can be copolymerized. Examples of the (meth) acrylic acid ester other than the (meth) acrylic acid alkyl ester include (meth) acrylic such as (meth) hydroxyethyl acrylate, (meth) hydroxypropyl acrylate, and (meth) hydroxybutyl acrylate. (Meta) acrylic acid alkoxyalkyl esters such as hydroxyalkyl acid, methoxymethyl (meth) acrylate, ethoxymethyl (meth) acrylate, ethoxymethyl (meth) acrylate, (meth) acrylic acid Examples thereof include phenyl, benzyl (meth) acrylate, glycidyl (meth) acrylate, and γ-butyrolactone (meth) acrylate.
Examples of the compound having a vinyl group include acrylamide compounds such as dimethylacrylamide, hydroxyethylacrylamide and dimethylaminopropylacrylamide, styrene compounds such as styrene, α-methylstyrene and p-methoxystyrene, maleic anhydride and the like. Can be done.

The glass transition temperature (Tg) can be obtained from the following Fox formula from the type and mass fraction of the monomer forming the (meth) acrylic polymer.
1 / Tg = Σ (Wi / Tgi) In this formula, Tg is derived from the glass transition temperature (unit: K) of the (meth) acrylic polymer, and Wi is derived from the monomer i constituting the (meth) acrylic polymer. The mass fraction of the monomer unit of, Tgi indicates the glass transition temperature (unit is K) of the homopolymer of the monomer i. As the value of Tgi, the value described in POLYMERHANDBOOK Volume 1 (WILEY-INTERSCIENCE) can be used.

In the present invention, the copolymerization component may contain an acrylic monomer (a1) at a point of reaction point with a cross-linking agent described later.

The acrylic monomer (a1) becomes a reaction point of a crosslinked structure when copolymerized with other copolymerization components to form an acrylic resin, and reacts with a functional group contained in the crosslinking agent (B) described later. A monomer containing a possible functional group may be used. Examples of such an acrylic monomer (a1) include a hydroxyl group-containing monomer, an amino group-containing monomer, an acetoacetyl group-containing monomer, an isocyanate group-containing monomer, and a glycidyl group-containing monomer. Among these, a hydroxyl group-containing monomer is preferably used because it can efficiently carry out a cross-linking reaction with a cross-linking agent. The acrylic monomer (a1) may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl (meth). ) Acrylic acid hydroxyalkyl esters such as acrylates, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylates, oxyalkylene-modified monomers such as diethylene glycol (meth) acrylates and polyethylene glycol (meth) acrylates, and 2-acrylate. Primary hydroxyl group-containing monomers such as leuroxyethyl 2-hydroxyethylphthalic acid and N-methylol (meth) acrylamide; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro2-hydroxypropyl Secondary hydroxyl group-containing monomers such as (meth) acrylate; Tertiary hydroxyl group-containing monomers such as 2,2-dimethyl2-hydroxyethyl (meth) acrylate can be mentioned.

Among the above hydroxyl group-containing monomers, a primary hydroxyl group-containing monomer is preferable because it has excellent reactivity with a cross-linking agent, and further, the use of 2-hydroxyethyl acrylate has less impurities such as di (meth) acrylate. It is particularly preferable because it is easy to manufacture.

As the hydroxyl group-containing monomer used in the present invention, it is preferable to use a monomer having a content ratio of di (meth) acrylate as an impurity of 0.5% or less, further 0.2% or less, particularly 0. It is preferable to use 1% or less. As the hydroxyl group-containing monomer, specifically, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate and the like are particularly preferable, and these are preferable because they have a low molecular weight and are easy to purify.

Examples of the amino group-containing monomer include t-butylaminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and the like.

Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.

Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate and allyl glycidyl (meth) acrylate.

The content of the acrylic monomer (a1) in the copolymerization component is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and particularly 0.2 to 3% by mass.
If the amount of the acrylic monomer (a1) is too small, the number of cross-linking points at the time of cross-linking is too small, so that the cohesive force after cross-linking tends to be insufficient, and if it is too large, the adhesive force tends to be too low.

Further, if necessary, a copolymerizable monomer (a2) other than (a1) can be contained as a copolymerization component.
Examples of the copolymerizable monomer (a2) include methyl metallicate, ethyl (meth) acrylate, n-butyl methacrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, and n-propyl (meth) acrylate. , N-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (Meta) acrylic acid alkyl ester-based monomers such as (meth) acrylate and isobornyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, ethoxylated o-phenylphenyl (meth) Aromatic ring-containing monomers such as acrylate, phenoxydiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, styrene, (meth) acryloylmorpholine, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, (meth). ) Amid-based monomers such as acrylamide, acrylonitrile, methacrylate, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinylpyrrolidone, itaconic acid dialkyl ester, fumaric acid. Examples thereof include dialkyl esters, allyl alcohols, acrylic chlorides, methyl vinyl ketones, N-acrylamide methyltrimethylammonium chlorides, allyltrimethylammonium chlorides, and dimethylallylvinyl ketones.

The content ratio of the copolymerizable monomer (a2) in the copolymerization component is preferably 0 to 20% by mass, more preferably 1 to 15% by mass, and particularly 2 to 10% by mass, and the copolymerizable monomer (a2). If a2) is too large, the adhesive properties tend to deteriorate.

(Crosslinking agent)
The present pressure-sensitive adhesive composition may contain a cross-linking agent, if necessary, depending on the curing method thereof.
Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, aldehyde-based cross-linking agents, amine-based cross-linking agents and the like. Among them, an isocyanate-based cross-linking agent is preferably used in terms of improving the adhesion to the substrate or the reactivity with the acrylic resin.
The cross-linking agent may be used alone or in combination of two or more.

The content of the cross-linking agent is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the main component resin. Is.
When the content of the cross-linking agent is within the above range, the cohesive force is not insufficient and the desired durability can be obtained, while the flexibility and the adhesive force can be prevented from being lowered.

Regarding the curing reaction, in the case of photo-curing by irradiating with active energy rays, it is preferable to add a polyfunctional (meth) acrylate to the present pressure-sensitive adhesive composition as a cross-linking agent.
Examples of such polyfunctional (meth) acrylates include trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and di. Examples thereof include pentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and glycerin polyglycidyl ether poly (meth) acrylate.

<Thickness of this adhesive layer>
The thickness of the adhesive layer is not particularly limited. For example, from the viewpoint of imparting sufficient adhesive strength and filling the unevenness and steps of the base material to which the adhesive is adhered, it is preferably 0.1 μm or more, particularly 0.5 μm or more, and particularly 1 μm or more. It is even more preferable to have it. On the other hand, from the viewpoint of material usage efficiency, permeability, and outgas, it is preferably 10,000 μm or less, more preferably 3000 μm or less, and even more preferably 1000 μm or less.

<<< This film laminate >>>
A film laminate (referred to as "the film laminate") having a structure in which an optical member is bonded to the surface of the adhesive layer of the release film with the adhesive layer can be produced.

Examples of the optical member include a polarizing plate and a touch sensor. Further, it may be an in-vehicle optical member such as a touch panel mounted on an automobile.

(Polarizer)
The material and composition of the polarizing plate are arbitrary. For example, a stretched polyvinyl alcohol film using iodine as an alignment dye and a TAC (triacetyl cellulose) film laminated as a protective film have been widely put into practical use as this type of polarizing plate.
Further, the polarizing plate may have a layer structure on the surface having functions such as a hard coat having substantially no phase difference, antiglare, low reflection, and antistatic.

(Touch sensor)
The touch sensor is a member that grasps the touch point in response to the contact when the user touches the image displayed on the screen with a finger or a touch pen. , A method such as a surface wave method using infrared rays or ultrasonic waves is exemplified.
Generally, the touch sensor is mounted on a display device such as a liquid crystal display panel or an organic EL.
Further, in recent years, as an alternative to the glass substrate, there is a tendency to focus on flexibility and use a base film.
The touch sensor film is generally provided with a patterned transparent conductive layer for performing the function of the sensing electrode.

<<< Explanation of words and phrases >>>
In the present invention, the term "film" shall include a "sheet", and the term "sheet" shall include a "film".
Further, when the term "panel" is used, such as an image display panel or a protective panel, it includes a plate, a sheet, and a film.

In the present invention, when "X to Y" (X and Y are arbitrary numbers) is described, it means "X or more and Y or less" and "preferably larger than X" or "preferably Y" unless otherwise specified. It also includes the meaning of "smaller".
Further, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably larger than X" and is described as "Y or less" (Y is an arbitrary number). In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

Next, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the examples described below.

<Evaluation method>
In the following, various physical properties were measured and evaluated as follows.

(1) Viscosity of curable silicone resin The curable silicone resin is solvent-diluted with n-heptane to 15% by mass, and the viscosity of this solution at 25 ° C is measured by an E-type viscometer (TVE manufactured by Toki Sangyo Co., Ltd.). -22L ") Measured using a viscometer.

(2) Molecular weight measurement of curable silicone resin A chromatogram is measured using a GPC measuring device, and a number average molecular weight (Mn) and a weight average molecular weight (Mw) are obtained based on a calibration curve using standard polystyrene. It is shown in Table 2. Specifically, 4 mg of the sample for measurement was dissolved in 4 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into a GPC measuring device for measurement. Tetrahydrofuran (THF) was used as the eluent. "Ecosec8320" manufactured by Tosoh Corporation is used for analysis, "TSKgel guardcolum HXL-L" manufactured by Tosoh Corporation is used for the guard column, and "TSKgel GMHXL" manufactured by Tosoh Corporation is connected to the column. used. The analysis was performed under the conditions of an oven temperature of 40 ° C. and a THF flow rate of 1.0 mL / min, and RI was used for detection.

(3) Measurement of thickness of release layer In order to suppress reflection from the back surface, a black tape (vinyl tape VT-50 manufactured by Nichiban Co., Ltd.) was attached to the measurement back surface of the sample film in advance. For the measurement, a spectrophotometer (UV visible spectrophotometer V-670 manufactured by JASCO Corporation) is used to measure the absolute reflectance in the wavelength range of 300 to 800 nm in the synchronous mode, incident angle of 5 °, and N polarization. , Response Fast, data acquisition interval 1.0 nm, bandwidth 10 nm, scanning speed 1000 m / min. The film thickness of the release layer was determined by comparing the data obtained by this measurement with the data calculated with the refractive index of silicone as 1.43.

(4) Heat peeling force One side of acrylic double-sided adhesive tape (“No.502” manufactured by Nitto Denko Corporation) is attached to the surface of the release layer of the sample film, cut into a size of 50 mm × 300 mm, and in this state. Then, heat and hold at 100 ° C. (set temperature) for 1 hour in a hot air oven, then stand at 23 ° C. and 50% RH for 1 hour, and then use a tensile tester (Shimadzu Corporation "EZgraph"). Then, the 180 ° peeling force was measured under the condition of a tensile speed of 300 mm / min.

(5) Adhesion energy of the release layer The surface of the release layer of the sample film was observed with an atomic force microscope, and the obtained image was analyzed to calculate the adhesion energy.
At this time, a silicon probe (made by team nanotec, LRCH, radius of curvature: 250 nm, spring constant: 0.2 N / m) was attached to an atomic force microscope (trade name: SPM-9700HT, manufactured by Shimadzu Corporation), and 600 m / s. It was calculated according to the JKR two-point method based on the force curve obtained by tapping in.

(6) Measurement of elastic modulus of the release layer The elastic modulus was calculated according to the JKR two-point method based on the force curve obtained by the same device / method as the adhesion energy measurement.

(7) Evaluation of unevenness on the surface of the pressure-sensitive adhesive layer The following pressure-sensitive adhesive composition is applied to the surface (release surface) of the release layer of the sample film so that the film thickness in a wet state is 2 mil, and the temperature is 150 ° C., 3 A pressure-sensitive adhesive layer was formed by heat treatment for a minute and cured, and the unevenness of the surface of the pressure-sensitive adhesive layer on the side not in contact with the release surface was evaluated by the following methods (7-1) to (7-3).

<< Adhesive composition >>
Main agent (acrylic resin): AT352 (manufactured by Saiden Chemical) 100 parts by mass Hardener: AL (manufactured by Saiden Chemical) 0.25 parts by mass Additive: X-301-375SK (manufactured by Saiden Chemical) 0.25 parts by mass Additive : X-301-352S (manufactured by Saiden Chemical Co., Ltd.) 0.25 parts by mass Toluene: 40 parts by mass

(7-1) Visual Judgment An adhesive layer is formed on the release surface of the sample film as described above, and the unevenness of the surface of the adhesive layer on the side not in contact with the release surface is visually observed, and the following determination criteria are used. Judgment was made according to the above, and the judgment results are shown in Table 2.
(criterion)
○ (good): The surface unevenness is so good that it cannot be recognized, or the surface unevenness is very slight.
Δ (poor): Surface unevenness can be recognized.
× (very poor): Surface unevenness can be clearly recognized.

(7-2) Arithmetic mean height (Sa) measurement of the surface of the adhesive layer An adhesive layer is formed on the release surface of the sample film as described above, and the side that conforms to ISO25178 and is not in contact with the release surface. The arithmetic mean height (Sa) of the surface of the adhesive layer was measured in a region of 928 × 1235 μm using a Contour GT manufactured by Bruker Japan Co., Ltd. The measured arithmetic mean height (Sa) is shown in Table 2.

(7-3) Evaluation of image quality of the surface of the adhesive layer The adhesive layer is formed on the release surface of the sample film as described above, and the unevenness of the surface of the adhesive layer on the side not in contact with the release surface is imager. Using a measuring device (ICM-1DP, manufactured by Suga Test Instruments Co., Ltd.), the film is applied in the vertical direction (silicone release layer and adhesive layer coating) under the conditions of an optical axis of 0 ° (transmission mode) and an optical comb width of 0.125 mm. Measurements were made three times each in the direction) and the horizontal direction, and the average value was used for evaluation.
The larger the mapability value, the less the distortion of the image projected on the surface of the adhesive layer, and the clearer the image can be obtained.

[material]
The following raw materials were used in Examples and Comparative Examples.

<Release layer composition>
a1: Curable silicone resin composition (a curable silicone resin (number average molecular weight: 176000) in which a vinyl group is introduced into a side chain and / or a terminal of a main chain composed of a siloxane bond) and a main chain composed of a siloxane bond. A mixture containing a cross-linking agent having a Si—H group introduced into the side chain and / or the terminal (viscosity: 95 mcps).
a2: Curable silicone resin composition (curable silicone resin having a vinyl group introduced into the side chain and / or the terminal of the main chain composed of a siloxane bond, number average molecular weight: 10600, viscosity: 1.7 mcps).
a3: Curable silicone resin composition (a curable silicone resin (number average molecular weight: 364000) in which a vinyl group is introduced into a side chain and / or a terminal of a main chain composed of a siloxane bond) and a main chain composed of a siloxane bond. A mixture containing a cross-linking agent having a Si—H group introduced in the side chain and / or the terminal (viscosity: 410 mcps).
a4: Curable silicone resin composition (a curable silicone resin (number average molecular weight: 399000) in which a hexenyl group is introduced into the side chain and / or the terminal of the main chain composed of a siloxane bond) and the main chain composed of a siloxane bond. A mixture containing a cross-linking agent having a Si—H group introduced into the side chain and / or the terminal (viscosity: 430 mcps).

(Composition analysis of curable silicone resin)
The composition analysis of the curable silicone resin used in Examples and Comparative Examples was performed using 400 MHz-NMR (Bruker Avance 400M), and the results are shown in Table 1.
For 1H-NMR measurement, CDCl ₃ was used as a solvent, and the peak derived from the methyl group of dimethylsiloxane was used as a chemical shift reference, and the measurement was carried out at a temperature of 30 ° C.
Table 1 below shows the content ratio (mol%) of each functional group in the curable silicone resin.

b1: Cross-linking agent (CL750: manufactured by Momentive Performance Materials)
c1: Addition type platinum catalyst (PL-50T: manufactured by Shin-Etsu Chemical Co., Ltd.)
c2: Addition type platinum catalyst (CM678: manufactured by Momentive Performance Materials)
c3: Addition type platinum catalyst (SRX212: manufactured by Dow Toray Co., Ltd.)

[Example 1]
A release layer composition consisting of the following release agent composition A is applied to one side of a 38 μm-thick PET film “T100-38” manufactured by Mitsubishi Chemical Corporation by a bar coat method, and heat-treated at 150 ° C. for 15 seconds to cure. Then, a release layer having a thickness (after drying) of 0.23 μm was formed to obtain a release film (sample film).

<Release agent composition-A>
Curable silicone resin composition a1: 98% by mass
Addition type platinum catalyst c1: 2% by mass
The release layer composition was diluted with n-heptane to adjust the solid content concentration to 5.4% by mass.

[Example 2]
In Example 1, the same as in Example 1 except that the solid form concentration of the release layer composition was changed to 3.7% by mass so that the thickness of the release layer (after drying) was 0.18 μm. A release film (sample film) was obtained.

[Example 3]
In Example 1, the same as in Example 1 except that the solid content concentration of the release layer composition was changed to 1.9% by mass so that the thickness of the release layer (after drying) was 0.09 μm. To obtain a release film (sample film).

[Comparative Example 1]
In Example 1, the release layer composition was produced in the same manner as in Example 1 except that the release layer composition was changed to the following release agent composition-B, and the release layer had a thickness (after drying) of 0.23 μm. A release film (sample film) having a layer was obtained.

<Release agent composition-B>
Curable silicone resin composition a2: 91% by mass
Crosslinker b1: 3% by mass
Addition type platinum catalyst c2: 6% by mass
The release layer composition was diluted with n-heptane to adjust the solid content concentration to 5.4% by mass.

[Comparative Example 2]
In Comparative Example 1, the same as in Comparative Example 1 except that the solid content concentration of the release layer composition was changed to 3.7% by mass so that the thickness of the release layer (after drying) was 0.14 μm. To obtain a release film (sample film).

[Comparative Example 3]
In Comparative Example 1, the same applies to Comparative Example 1 except that the solid content concentration of the release layer composition was changed to 1.9% by mass so that the thickness of the release layer (after drying) was 0.07 μm. To obtain a release film (sample film).

[Comparative Example 4]
In Example 1, the release layer composition was produced in the same manner as in Example 1 except that the release layer composition was changed to the following release agent composition-C, and the release layer had a thickness (after drying) of 0.24 μm. A release film (sample film) having a layer was obtained.

<Release agent composition-C>
Curable silicone resin composition a3: 99% by mass
Addition type platinum catalyst c1: 1% by mass
The release layer composition was diluted with n-heptane to adjust the solid content concentration to 5.4% by mass.

[Comparative Example 5]
In Comparative Example 4, the same as in Comparative Example 4 except that the solid content concentration of the release layer composition was changed to 3.7% by mass so that the thickness of the release layer (after drying) was 0.16 μm. To obtain a release film (sample film).

[Comparative Example 6]
In Comparative Example 4, the same applies to Comparative Example 4 except that the solid content concentration of the release layer composition was changed to 1.9% by mass so that the thickness of the release layer (after drying) was 0.09 μm. To obtain a release film (sample film).

[Comparative Example 7]
In Example 1, the release layer composition was produced in the same manner as in Example 1 except that the release layer composition was changed to the following release agent composition −D, and the release layer had a thickness (after drying) of 0.28 μm. A release film (sample film) having a layer was obtained.

<Release agent composition-D>
Curable Silicone Resin Composition a4: 99% by Mass
Addition type platinum catalyst c3: 1% by mass
The release layer composition was diluted with n-heptane to adjust the solid content concentration to 5.4% by mass.

[Comparative Example 8]
In Comparative Example 7, the same applies to Comparative Example 7 except that the solid content concentration of the release layer composition was changed to 3.7% by mass so that the thickness of the release layer (after drying) was 0.22 μm. To obtain a release film (sample film).

[Comparative Example 9]
In Comparative Example 7, the same applies to Comparative Example 7 except that the solid content concentration of the release layer composition was changed to 1.9% by mass so that the thickness of the release layer (after drying) was 0.11 μm. To obtain a release film (sample film).

The characteristics of each release film (sample film) obtained in the above Examples and Comparative Examples are summarized in Table 2.

<Discussion>
Based on the above examples and the test results conducted by the inventor so far, a release layer composition is obtained from a curable silicone having a medium number average molecular weight (Mn) having a number average molecular weight (Mn) of 20,000 or more and 350,000 or less. By using it as the main component resin of the above and adjusting the release layer composition so as to contain a predetermined amount of phenyl groups, not only light peelability can be realized but also unevenness on the surface of the adhesive layer can be suppressed. It turned out that it can be smoothed. At this time, it is possible to suppress the unevenness of the surface of the adhesive layer because the surface of the release layer has an appropriate wettability and the low molecular weight silicone resin, that is, the incompatible component is eluted or transferred to the adhesive layer side. It can be considered that this is the result of being able to suppress it.

In particular, a mold release formed by applying and curing a release layer composition containing a curable silicone having a medium number average molecular weight (Mn) of 20,000 or more and 350,000 or less as a main component resin. The release film having a layer has good light peelability and high smoothness even when the release layer is thickly coated with a coating thickness of more than 0.1 g / m ² (thickness after drying: 0.18 μm or more). It was found that a good adhesive layer surface can be obtained.
Further, as described above, the release layer composition containing a curable silicone resin having a medium molecular weight as a main component resin has a high coating liquid in order to increase the thickness of the release layer for the purpose of light peeling. Even when prepared at a concentration, the viscosity of the coating liquid can be kept within an appropriate region, the coating appearance (without coating unevenness such as streaks) is good, and the peeling force value varies within the release film surface. It was found that a mold release film having a stable peeling property with reduced viscosity can be produced.
It can be inferred that the release layer of the example has almost no change in adhesion energy even if the film thickness is increased, and a stable film formation is formed. On the other hand, in all of the comparative examples, it was confirmed that the adhesion energy tends to decrease as the thickness of the release layer increases.

Furthermore, based on the above examples and the test results conducted by the inventor so far, when the adhesive layer is formed on the release layer, if a phenyl group is present in the release layer, the unevenness of the surface of the adhesive layer is suppressed. , It turned out that the peeling can be made lighter.
Although the detailed mechanism is unknown at this time, the release layer composition (release layer composition a3, a4, etc.) containing a curable silicone resin having a general high molecular weight as a main component resin is made into a medium molecular weight. It is presumed that the unreacted component of the increasing reactive group (alkenyl group, Si—H group) is hidden from the pressure-sensitive adhesive by the phenyl group (interaction between the phenyl group and the alkenyl group, Si—H group).
Further, from the above-mentioned Examples and the test results conducted by the inventor so far, it has been found that it is preferable that the release layer contains 0.01 to 5.0 mol% of phenyl groups with respect to the total amount of siloxane components. rice field.

Claims (12)

It is a release film having a structure in which a release layer is provided on one side of the base film.
The adhesion energy of the release layer is 35 mJ / m ² or more and 39 mJ / m ² or less, an acrylic adhesive tape is attached to the release layer, cut into a size of 50 mm × 300 mm, and hot air is provided in that state. After heating and holding at 100 ° C. (set temperature) for 1 hour in a formula oven and then allowing it to stand at 23 ° C. and 50% RH for 1 hour, the 180 ° release force under the condition of a tensile speed of 300 mm / min is 15 mN /. Release film that is cm or less. The release film according to claim 1, wherein the release layer has a thickness (after drying) of 0.05 μm to 2.0 μm. The release layer is a release layer obtained by curing a release layer composition containing a curable silicone resin having a number average molecular weight (Mn) of 20,000 or more and 350,000 or less as a main component resin. The release film described. The release film according to claim 3, wherein the curable silicone resin has a viscosity at 25 ° C. of 10 to 400 mcps when adjusted to 15% by mass by diluting with an n-heptane solvent. The release layer according to any one of claims 1 to 4, wherein the release layer is a release layer obtained by curing a release layer composition containing 0.01 to 5.0 mol% of phenyl groups with respect to all siloxane components. Release film. The release film according to any one of claims 1 to 5, wherein the base film is a polyester film. A release film with an adhesive layer having a structure in which an adhesive layer is laminated on the release layer of the release film according to any one of claims 1 to 6. The adhesive layer according to claim 7, wherein the arithmetic average height (Sa, ISO25178 surface texture) of the surface of the adhesive layer (referred to as "adhesive layer surface") on the opposite side of the release film is 53 nm or less. Release film. The release film with an adhesive layer according to claim 7 or 8, wherein the image quality value of the surface of the adhesive layer is 70 or more. The release film with an adhesive layer according to any one of claims 7 to 9, wherein the adhesive layer is a layer composed of an acrylic adhesive. A film laminate having a structure in which an optical member is bonded to the surface of the pressure-sensitive adhesive layer of the release film with a pressure-sensitive adhesive layer according to any one of claims 7 to 10. The film laminate according to claim 11, wherein the optical member is a polarizing plate or a touch sensor.

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