JP2016165825A - Mold release film excellent in releaseability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold release film that has a small peeling force and is hard to increase the peeling force in a state of being stuck to an adhesive layer even with the long lapse of time, and is low in migration of a silicone component to the adhesive layer, and accordingly does not lower the adhesive force of the stuck adhesive layer and is excellent in peelability.SOLUTION: A mold release film 5 has a mold release agent layer 4 that contains a silicone-based mold release agent and a thickness of 0.4-2 μm provided on one surface of a base material film 1, and has a binder resin layer 2 containing inorganic fine particles and/or polymer fine particles as fine particles 3 provided on the other surface. The fine particles 3, the binder resin layer 2 and the mold release agent layer 4 satisfy the following conditions (1) and (2): (1) a volume-based average particle diameter of the fine particles 3 is twice or more a thickness of the mold release agent layer 4; and (2) a thickness of the binder resin layer 2 is in a range of 25-60% of the volume-based average particle diameter of the fine particles 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a release film used for surface protection of various adhesive products and sticky objects. More specifically, the peeling force is small, and even when time passes in the state of being bonded to the pressure-sensitive adhesive layer, the peeling force is hardly increased, and the transfer of the silicone component to the pressure-sensitive adhesive layer is small, and thus bonding is performed. The present invention relates to a release film that does not decrease the adhesive strength of the pressure-sensitive adhesive layer and has excellent peelability.

  Conventionally, release films (sometimes referred to as release films) have been used for various applications. Above all, it has a pressure-sensitive adhesive layer used in the production of green sheet molding release films, polarizing plates, optical filters, flat panel displays, etc. used in the production of various ceramic electronic parts such as ceramic multilayer capacitors and ceramic substrates. Widely used for release films for optical members, touch panel members, release films for adhesive layers for bonding optical members, and the like.

  Green sheets used in the production of various ceramic electronic components such as ceramic multilayer capacitors and ceramic substrates are becoming thinner as ceramic multilayer capacitors become smaller and larger in capacity. When a green sheet is peeled from a release film, if the release force of the release film is large, the green sheet is damaged. Therefore, a release film having a smaller peel force than the conventional one is required.

On the other hand, in an optical member such as a polarizing plate or a retardation plate that is a member constituting a liquid crystal display, an adhesive layer for bonding the optical member to each other or another member, and for protecting the adhesive layer A release film is used.
The release film used for the application needs to be able to be peeled lightly even if the peel area is large, as the size of the optical member such as a polarizing plate and the release film increase as the display becomes larger. Therefore, there is a demand for a release film having a smaller peeling force than conventional ones. Moreover, about the adhesive layer for optical members for bonding the structural member and optical members of a touch panel, with thinning of tablet PC, a tablet terminal, a touch panel, etc., even a thin adhesive layer of an optical member A pressure-sensitive adhesive layer having a weak cohesive force is used so as to follow a step (for example, a step of frame printing used for a cover glass of a portable terminal). However, when a pressure-sensitive adhesive layer having a weak cohesive force is used, the release film having a smaller peeling force than conventional ones will be deformed if the release force of the release film is too large. Is required.

As described above, a release film for forming a ceramic green sheet and a release film for an optical member having various pressure-sensitive adhesive layers are required to have a release film having a smaller peeling force than conventional ones. Against this background, Patent Document 1 proposes a release film using a cured silicone containing silicone having only one vinyl group in the molecule.
Further, in Patent Document 2, an oligomer precipitation preventing layer is applied to one side of a polyester film, and a release layer containing a solventless addition reaction curable silicone is provided thereon, and the tape peeling force is 15 mN / cm or less. In addition, a release film having a migration evaluation adhesion rate of silicone components of 90% or more has been proposed.
Furthermore, in patent document 3, the release which performed the heat processing for 20 hours or more in 50-65 degreeC environment using the addition reaction type silicone which does not add the light peeling component, such as polydimethylsiloxane which does not have a functional group. A release film having a peeling force of acrylic pressure-sensitive adhesive of 0.15 N / 50 mm or less and a residual adhesive rate of 90% or more has been proposed.

In each of Patent Documents 1 to 3, a release film is proposed that has a small peeling force and does not reduce the adhesive strength of the bonded adhesive layer. However, since the release film described in Patent Document 1 uses a cured silicone containing silicone having only one vinyl group in the molecule, silicone having only one vinyl group unless the vinyl group is completely reacted. Is likely to move to the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer is reduced.
Moreover, about the release film of patent document 2, it is different from the conventional release film that the precipitation prevention layer of an oligomer is provided. However, since solvent-free addition reaction curable silicone is used, the release performance falls within the category of conventional release films.
Furthermore, the release film described in Patent Document 3 is lightly peeled by aging addition-reactive silicone to which no lightly peeling component is added. In this case, a release film that does not decrease the adhesive strength of the bonded adhesive layer is obtained for light peeling, but it is difficult to further reduce the peeling force.

  The release film described in Patent Document 4 is obtained by applying a silicone release layer containing inert particles having a predetermined particle diameter to a polyester film to a predetermined thickness. Blocking that occurs when the silicone release layer is thickened (a phenomenon in which when the release film is rolled into a roll, the back surface of the release film and the release layer are pseudo-bonded and cannot be wound well) This is solved by putting inert particles in the silicone release layer. However, since the silicone release layer is discontinuous due to the inert particles, when the solvent comes into contact with the solvent, the solvent may permeate the interface between the inert particles and the silicone, and the silicone may fall off. In addition, when adding a release film to protect the surface of the pressure-sensitive adhesive layer in order to add inert particles having a particle size larger than the thickness of the silicone release layer, the inert particles are placed on the pressure-sensitive adhesive layer side. It may adhere and reduce the adhesive strength of the adhesive layer.

JP 2008-265227 A JP 2012-136612 A JP 2006-007689 A JP2013-208897A

  In the present invention, the peeling force is small, and even when time passes in the state of being bonded to the pressure-sensitive adhesive layer, the peeling force is hardly increased, and the silicone component is less transferred to the pressure-sensitive adhesive layer, and thus bonded. It is an object of the present invention to provide a release film that does not decrease the adhesive strength of the pressure-sensitive adhesive layer and has excellent peelability.

  As a result of intensive studies to solve these problems, in order not to reduce the adhesive strength of the pressure-sensitive adhesive layer, a release film using a silicone-based release agent (sometimes called a release agent) is used. It has been found that there is a need for less silicone transfer to the layer. In addition, even when using a silicone release agent with little silicone migration to the pressure-sensitive adhesive layer, as a result of studying to reduce the peel force, by increasing the thickness of the release agent layer to a specific thickness or more It was found that the peel force can be reduced. However, when the thickness of the release agent layer is increased, the release film is wound into a roll shape, and when the release agent layer is combined with the back surface of the release film, blocking occurs, and the release agent layer is released. It was found that the film could not be rewound cleanly into a roll. In the production process, the base film used for the release film contains lubricant particles in order to prevent blocking even when the base film is wound into a roll shape. A film is being formed. For this reason, on the back surface of the release film, the surface of the base film has an uneven structure. By increasing the thickness of the release agent layer, the uneven structure on the surface of the base film is released. The filling of the agent layer is considered to cause the blocking.

  In addition, the present invention has been completed by intensively studying a method for achieving both peelability and blocking resistance. In the present invention, the thickness of the release agent layer is set to 0.4 μm or more in order to reduce the peeling force even when a release agent with little migration of the silicone component to the pressure-sensitive adhesive layer is used. In addition, in order to prevent blocking between the release agent layer and the back surface of the release film, the present invention provides a surface roughness corresponding to the thickness of the release agent layer on the surface opposite to the release agent layer of the base film. The technical idea is to achieve both releasability and anti-blocking property by forming the uneven shape.

  In order to solve the above problems, the present invention provides a release agent layer containing a silicone-based release agent at a thickness of 0.4 to 2 μm on one surface of a base film, and on the other surface, A release film provided with a binder resin layer containing inorganic fine particles and / or polymer fine particles as fine particles, wherein the fine particles, the binder resin layer, and the release agent layer are (1) the volume of the fine particles. The reference average particle diameter is at least twice the thickness of the release agent layer, and (2) the binder resin layer has a thickness of 25 to 60% of the volume reference average particle diameter of the fine particles. A release film characterized by being in the range is provided.

  The inorganic fine particles are preferably at least one selected from the group of inorganic particles consisting of silica, calcium carbonate, calcium phosphate, barium sulfate, kaolin, glass powder, and talc. The polymer fine particles are selected from a polymer resin particle group consisting of a silicone resin, an acrylic resin, a polyamide resin, a polyester resin, a polyethylene resin, a polypropylene resin, a polystyrene resin, and an epoxy resin. It is preferable that it is a seed or more.

  Moreover, it is preferable that the said base film is a polyester resin film.

  The present invention also includes a laminate in which an adhesive layer is laminated on at least one surface of a resin film, or a single adhesive layer and the release film, and the release agent is provided on the surface of the adhesive layer. Provided is a laminated film obtained by laminating the release film via a layer.

ADVANTAGE OF THE INVENTION According to this invention, the mold release film for shaping | molding of a ceramic green sheet and the mold release film excellent in the peelability for optical members which have various adhesive layers can be provided. The release film of the present invention has a small peel force, and even when time passes in the state of being bonded to the pressure-sensitive adhesive layer, the peel force is hardly increased, and the silicone component does not migrate to the pressure-sensitive adhesive layer. It is possible to provide a release film excellent in releasability that does not reduce the adhesive strength of the bonded pressure-sensitive adhesive layer.
In addition, the release film of the present invention is excellent in that it does not reduce the adhesive strength of the adhesive layer bonded, and can be rewound cleanly without causing blocking even when wound into a roll shape. It has both releasability and anti-blocking properties, has a great industrial utility value, and its industrial value is extremely large.

It is sectional drawing which shows an example of the release film of this invention typically. It is sectional drawing which shows typically the 1st form example of the laminated | multilayer film of this invention. It is sectional drawing which shows typically the 2nd form example of the laminated | multilayer film of this invention.

Hereinafter, preferred embodiments of the present invention will be described.
FIG. 1 is a cross-sectional view schematically showing an example of a release film of the present invention, in which a binder resin layer 2 is formed on one side of a base film 1, and a silicone system is provided on the opposite side of the base film 1. The mold release agent layer 4 is formed.
The binder resin layer 2 contains inorganic fine particles and / or polymer fine particles as fine particles 3 for preventing blocking.

In the release film 5 of the present invention, the resin film used as the base film 1 may be selected according to the use, but the polyester resin film, polyamide resin film, polyimide resin film, polyolefin resin film, polyvinyl chloride resin film. , Polystyrene resin film, acrylic resin film, acetate resin film, polyphenylene sulfide resin film, and the like.
Among these, a polyester resin film is preferable from the viewpoints of characteristics such as optical characteristics and heat resistance, price, and appearance. Examples of the polyester resin include polyethylene terephthalate, polyethylene naphthalate, a copolymer of polyethylene isophthalate and polyethylene terephthalate, and polybutylene terephthalate. Among these, polyethylene terephthalate (PET) is particularly preferable from the viewpoint of cost and optical properties. Also, from the viewpoint of optical characteristics, monoaxially stretched or biaxially stretched polyethylene terephthalate for optics is preferable.
Further, if necessary, the surface of the base film 1 may be subjected to easy adhesion treatment such as surface modification by plasma discharge or corona discharge, application of an anchor coating agent, and the like.

  The thickness of the base film 1 is not particularly limited, but assuming the ease of handling as the release film 5 and winding the release film 5 in a roll shape, the thickness of the base film 1 is About 10-200 micrometers is preferable.

  In the present invention, even if the thickness of the release agent layer containing the silicone release agent is increased, the base material film does not cause blocking when the release agent layer is combined with the back surface of the release film. An uneven structure having a surface roughness corresponding to the thickness of the release agent layer is formed on the surface opposite to the release agent layer of 1. In order to form a concavo-convex structure on the surface of the base film 1, the binder resin layer 2 containing inorganic fine particles and / or polymer fine particles is applied as the fine particles 3 for preventing blocking.

Examples of the inorganic fine particles and / or polymer fine particles that are the fine particles 3 for blocking prevention include inorganic fine particles that are fine particles of an inorganic compound and polymer fine particles that are fine particles of a polymer resin. Either inorganic fine particles or polymer fine particles may be used, or both may be used in combination. The inorganic fine particles are preferably at least one selected from the group of inorganic particles consisting of silica, calcium carbonate, calcium phosphate, barium sulfate, kaolin, glass powder, and talc. In addition, the polymer fine particles are selected from a group of polymer resin particles composed of silicone resin, acrylic resin, polyamide resin, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, and epoxy resin. The above is preferable.
The shape of the fine particles 3 is not particularly limited, and may be any of spherical, rod-like, scale-like, hemispherical, convex lens-like, mushroom-like, and indeterminate shapes. Since the performance is easy to come out, it is more preferable.
The particle diameter of the fine particles 3 is preferably not less than twice the thickness of the release agent layer 4 as a volume-based average particle diameter. If the volume-based average particle diameter of the fine particles 3 is less than twice the thickness of the release agent layer 4, the anti-blocking performance may be lowered. If the volume-based average particle diameter of the fine particles 3 is at least twice the thickness of the release agent layer 4, anti-blocking performance can be obtained. The upper limit of the volume-based average particle diameter of the fine particles 3 is not particularly problematic. However, when the volume-based average particle diameter of the fine particles 3 is increased, it is necessary to increase the thickness of the binder resin layer 2 and the cost is high. Become. For this reason, the volume-based average particle diameter of the fine particles 3 is preferably suppressed to about 10 times the thickness of the release agent layer 4. According to the volume-based average particle diameter, the contribution of the large volume particles is large, and even if the small volume particles are mixed, the influence is small. Therefore, at least some of the particles have the thickness of the release agent layer 4. If the particle diameter is twice or more, anti-blocking performance can be obtained.

The resin used for the binder resin layer 2 is not particularly limited as long as the fine particles 3 are dispersed and are in close contact with the base film 1. Examples thereof include polyester resins, acrylic resins, polyurethane resins, alkyd resins, silicone resins, cellulose resins, polyvinyl alcohol, silane coating agents, silicate coating agents, and the like.
The resin used for the binder resin layer 2 may be an aqueous, non-aqueous (solvent) or solvent-free type. The thickness of the binder resin layer 2 is desirably in the range of 25 to 60% of the volume-based average particle diameter of the fine particles 3. When the thickness of the binder resin layer 2 is less than 25% of the volume-based average particle diameter of the fine particles 3, the anchoring force of the fine particles 3 is reduced, and the fine particles 3 are likely to fall off. On the other hand, when the thickness of the binder resin layer 2 exceeds 60% of the volume-based average particle diameter of the fine particles, problems such as a decrease in blocking prevention performance and an increase in cost are undesirable.

  The fine particles 3 are mixed in the resin forming the binder resin layer 2 and applied onto the base film 1. A part (upper part) of the fine particles 3 protrudes from the thickness of the binder resin layer 2 (the average thickness of the part without the fine particles 3). The resin of the binder resin layer 2 may be thinly attached to the upper surface of the fine particles 3 or may not be attached.

In order to prevent blocking of the release film, it is important that the fine particles 3, the binder resin layer 2, and the release agent layer 4 satisfy the following two conditions.
(1) The volume-based average particle diameter of the fine particles 3 is at least twice the thickness of the release agent layer 4.
(2) The thickness of the binder resin layer 2 is in the range of 25 to 60% of the volume-based average particle diameter of the fine particles 3.

  The mixing / dispersing method of the fine particles 3 in the binder resin may be performed by a known method according to the kind of the binder resin and fine particles. If it is a system in which fine particles are easily dispersed in the binder resin, stirring and mixing may be performed with a manual instrument such as a spatula. Even a combination in which the fine particles are difficult to disperse in the binder resin or a system in which the fine particles are easy to disperse may be dispersed and mixed using a disperser such as a homogenizer or a homomixer when the amount of the binder resin and fine particles is large. In addition to fine particles and binder resin, surfactants, colorants, antistatic agents, lubricants such as wax, antifouling agents such as silicone and fluorine, leveling agents, curing agents, preservatives, etc. It may be added.

  The binder resin layer 2 containing the fine particles 3 may be formed by coating the base film 1 with a binder resin containing the fine particles 3. The coating method is not particularly limited, and may be selected from known coating methods according to the viscosity and the coating amount of the binder resin containing the fine particles 3. Examples include the Mayer bar method, the gravure method, the reverse roll method, the air knife method, and the multi-stage roll method.

  The binder resin layer 2 containing the fine particles 3 may be cured or solidified according to the type of the binder resin. For example, the solvent or water may be removed by heat drying, or the binder resin may be cured by ultraviolet irradiation or electron beam irradiation.

  Examples of the release agent used for the release agent layer 4 include silicone release agents. Examples of the silicone release agent include known silicone release agents such as an addition reaction type, a condensation reaction type, a cationic polymerization type, and a radical polymerization type. Examples of products that are commercially available as addition reaction type silicone release agents include KS-776A, KS-776L, KS-847, KS-847T, KS-779H, KS-837, KS-778, and KS-830. , KS-774, KS-3565, X-62-2829, KS-3650, KNS-3051, KNS-320A, KNS-316, KNS-3002, X-62-1387 (manufactured by Shin-Etsu Chemical Co., Ltd.), SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310, LTC-750A, SP-7025, SP-7248S, SP-7015, SP-7259, LTC-1006L, LTC-1056L (manufactured by Toray Dow Corning Co., Ltd.), TP -6722, TPR-6721, TPR-6702, TPR-6700, TPR-6600, SL6625 (manufactured by Momentive performance Materials, Inc.) and the like. Examples of the products marketed as the condensation reaction type include SRX-290, SYLOFF-23 (manufactured by Toray Dow Corning Co., Ltd.), YSR-3022 (manufactured by Momentive Performance Materials). Examples of products marketed as a cationic polymerization type include TPR-6501, TPR-6502, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials), X62-7622, X-62. -7660, X-62-7655 (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. Examples of products marketed as radical polymerization types include KF-2005, X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like. Silicone mold release agent that does not contain a light release additive component (silicone that does not have an organic functional group involved in an addition reaction, such as polydimethylsiloxane) as a mold release agent with little migration of the silicone component to the adhesive layer Is mentioned.

  One type of silicone release agent used for the release film of the present invention may be used alone, or a plurality of types may be mixed and used. In addition, components other than silicone release agents such as a silane coupling agent, an antistatic agent, and a wettability improver may be added, and may be determined in consideration of releasability, coatability, curability, and the like. The release agent may be applied by a known method and is not particularly limited, and examples thereof include a Mayer bar method, a gravure method, a reverse roll method, an air knife method, and a multistage roll method. Examples of curing methods for silicone mold release agents include methods such as heat curing, ultraviolet curing, electron beam curing, and combined use of heating and ultraviolet irradiation. Select a suitable method according to the type of silicone mold release agent. And adopt it. The thickness of the release agent layer 4 containing a silicone release agent is, for example, 0.4 to 2 μm. If the thickness of the release agent layer 4 is smaller than 0.4 μm, the peeling force tends to increase. The upper limit of the thickness of the release agent layer 4 is not particularly problematic. However, when the thickness of the release agent layer 4 is increased, the volume-based average particle diameter of the fine particles 3 is increased and the binder resin is increased. It is necessary to increase the thickness of the layer 2, and the cost increases. For this reason, it is preferable to suppress the thickness of the release agent layer 4 to about 2 μm.

  When the release film 5 of the present invention is used as a release sheet for forming a green sheet used in the production of various ceramic electronic parts, the green sheet is coated with a slurry in which ceramic particles are dispersed in an organic solvent, and dried. It is formed by. In the release film 5 used for the purpose of protecting the green sheet, solvent resistance is required for the release agent layer 4. In the present invention, since the release agent layer 4 does not contain the fine particles 3, the silicone release agent is not discontinuous and the release agent layer 4 has good solvent resistance, and is used for protecting the green sheet. It can be used suitably. Moreover, it can use suitably for the use which protects the surface of the coating film which disperse | distributed various powders, such as not only a green sheet but conductor paste, an insulator paste, and a solvent.

  FIG. 2 is a cross-sectional view schematically showing a first embodiment of the laminated film of the present invention. The optical film with adhesive 10 in FIG. 2 is used for protecting the adhesive layer 6 in which the release film 5 of the present invention is laminated on the optical film 7. An optical film 7 is bonded to the release film 5 of the present invention shown in FIG. In such a method for producing the optical film 10 with pressure-sensitive adhesive, the optical film 7 may be bonded after the solvent-type pressure-sensitive adhesive is applied to the release film 5 and dried. In such a release film 5 used for protecting the pressure-sensitive adhesive layer 6, solvent resistance is required for the release agent layer 4. In the present invention, since the release agent layer 4 does not contain the fine particles 3, the silicone release agent is not discontinuous and the release agent layer 4 has good solvent resistance, and protects the adhesive layer 6. It can be suitably used for applications. The laminate including the pressure-sensitive adhesive layer 6 can include one or more resin films and one or more pressure-sensitive adhesive layers. For example, the adhesive layer 6 may be provided on both surfaces of the optical film 7, and the release film 5 may be bonded to each adhesive layer 6. As another manufacturing method, you may bond the release film 5 to the laminated body 8 which provided the adhesive layer 6 in the single side | surface of the optical film 7. FIG. Alternatively, the adhesive layer 6 can be cured between the release film 5 and the optical film 7 by light, heat, or the like after applying the solventless adhesive.

  Moreover, FIG. 3 is sectional drawing which shows typically the 2nd form example of the laminated | multilayer film of this invention. The optical pressure-sensitive adhesive sheet 9 in FIG. 3 is obtained by bonding the release film 5 of the present invention to the pressure-sensitive adhesive layer 6 used for bonding a touch panel member or an optical member in order to protect the pressure-sensitive adhesive layer 6. is there. The optical adhesive sheet 9 has a form in which the adhesive layer 6 is sandwiched between two release films 5. In such a method for producing the optical pressure-sensitive adhesive sheet 9, a solvent-type pressure-sensitive adhesive is applied to one release film 5 and dried, and then the other release film 5 is bonded. In such a release film 5 used for protecting the pressure-sensitive adhesive layer 6, solvent resistance is required for the release agent layer 4. In the present invention, since the release agent layer 4 does not contain the fine particles 3, the silicone release agent is not discontinuous and the release agent layer 4 has good solvent resistance, and protects the adhesive layer 6. It can be suitably used for applications.

The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 6 may be water-based, non-aqueous (solvent-based) or solvent-free. As the pressure-sensitive adhesive, any of an acrylic pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, and the like may be used. An acrylic pressure-sensitive adhesive is preferable because it is excellent in transparency and weather resistance.
The resin film used for the laminated film is not limited to the optical film 7 and may be an opaque resin film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an antiglare (antiglare) film, an ultraviolet absorption film, an infrared absorption film, an optical compensation film, a brightness enhancement film, and a highly transparent film.

  Hereinafter, the present invention will be specifically described with reference to examples.

(Release film of Example 1)
In a beaker, 7.5 parts by weight of ethyl cellulose (manufactured by Dow Chemical Co., Ltd., product name: Etocel (registered trademark) 100FP), and a silicone resin polymer fine particle (momentive performance) having an average particle diameter (volume-based average particle diameter) of 2 μm Materials Co., Ltd., product name: Tospearl (registered trademark) 120) 0.0375 parts by weight, toluene / ethyl acetate 50/50 mixed solvent 92.5 parts by weight, mixed and stirred until ethylcellulose is dissolved And created a paint. Next, after applying to the uncorona-treated surface of the single-sided corona-treated polyester film having a thickness of 50 μm so that the thickness of the binder resin after drying is 1.0 μm, circulating hot air at 120 ° C. It heated for 1 minute with the type | formula dryer, and obtained the polyester film which provided the surface uneven | corrugated shape on the single side | surface. Next, 30 parts by weight of an addition reaction type silicone release agent (product name: LTC-1056L, manufactured by Toray Dow Corning Co., Ltd.) on the surface (corona-treated surface) opposite to the surface provided with the uneven shape of the obtained polyester film. In contrast, 1 part by weight of platinum catalyst (product name: SRX212 catalyst manufactured by Toray Dow Corning Co., Ltd.) and 70 parts by weight of a 50/50 mixed solvent of toluene / ethyl acetate were mixed, and the mixed paint was dried. After coating with a Meyer bar method so that the thickness was 1.0 μm, the film was heated for 1 minute in a hot air circulation drier at a preset temperature of 120 ° C. to obtain a release film of Example 1.

(Confirmation of blocking properties)
In Example 1, the thicknesses of the binder resin layer (ethyl cellulose) and the release agent layer, and the types of silicone resin polymer fine particles were changed, and release films of Production Examples 1 to 12 were obtained. In addition, said Example 1 is the manufacture example 5 of Table 1. FIG.
About the release film of the obtained manufacture examples 1-12, the confirmation test was done about the presence or absence of blocking of a mold release agent layer and a binder resin layer, and the presence or absence of fine particle fall-off.

(Check for blocking)
A sample in which three release films are stacked is prepared and sandwiched between two stainless plates (SUS304). The sample is allowed to stand in an environment of 23 ° C. and 50% RH for 24 hours under a load of 20 g / cm ² {0.196 N / cm ² }. Then, the release film which overlapped 3 sheets was taken out, and the blocking state was confirmed by peeling off one release film at a time. There was no blocking, the release film was lightly peeled off, the blocking property was good (◯), the release film was slightly resistant when the release film was peeled off, and the blocking property was slightly poor (△), and the release film was markedly peeled off The thing was set as the poor blocking property (x).

(Confirmation of the absence of fine particles)
The fine particle-containing binder resin-coated surface of the release film is rubbed once with a non-woven fabric (Bencot (registered trademark) M-1 manufactured by Asahi Kasei Corporation) with a weight of 200 g. Thereafter, the rubbed portion of the sample was observed with a laser microscope. The number of the remaining and falling parts of the fine particles was measured at 10 places, and the case where the fine particles dropped off was less than 30% was judged as good (◯), and the fine particles dropped off at 30% or more was judged as poor (x).

(Result of confirmation test)
The results of the confirmation test are shown in Table 1.

From the results of the confirmation test shown in Table 1, as the condition that the release agent layer and the binder resin layer do not block, the surface roughness (unevenness) of the binder resin layer increases as the thickness of the release agent layer increases. It turns out that it is necessary to enlarge. Further, from the results of the confirmation test shown in Table 1, the volume-based average particle diameter of the fine particles (inorganic fine particles or polymer fine particles) and the release agent are set as conditions under which the release agent layer and the binder resin layer do not block. The relationship with the thickness of the layer and the relationship with the thickness of the binder resin layer with respect to the average particle diameter of the fine particles (inorganic fine particles or polymer fine particles) were obtained as follows.
(I) The average particle diameter of the fine particles is at least twice the thickness of the release agent layer.
(Ii) The thickness of the binder resin layer with respect to the average particle diameter of the fine particles is lower than 75%.
On the other hand, it can be seen that it is necessary to increase the thickness of the binder resin layer relative to the average particle diameter of the fine particles as a condition for preventing the fine particles from falling off from the binder resin layer containing the fine particles. From the results of the confirmation test shown in Table 1, the thickness of the binder resin layer that does not cause the fine particles to fall off was derived from the binder resin layer containing the fine particles as follows.
(Iii) The thickness of the binder resin layer with respect to the average particle diameter of the fine particles is 25% or more.
Moreover, in the result of the confirmation test shown in Table 1, from the comparison between Production Example 6 and Production Example 7, the condition (ii) indicates that the thickness of the binder resin layer with respect to the volume-based average particle diameter of fine particles is 60% or less. If it is, it turns out that a mold release agent layer and a binder resin layer do not raise | generate blocking.

That is, from the results of the confirmation test shown in Table 1, the following conditions were set as conditions under which the release agent layer and the binder resin layer do not cause blocking, and conditions under which the fine particles do not fall off from the binder resin layer containing fine particles: was gotten.
(1) The average particle diameter of the fine particles is at least twice the thickness of the release agent layer.
(2) The thickness of the binder resin layer is in the range of 25 to 60% of the average particle diameter of the fine particles.

(Example 2)
A release film of Example 2 was prepared in the same manner as in Example 1 except that the thickness of the release agent layer was 0.4 μm.

(Example 3)
A release film of Example 3 was prepared in the same manner as in Example 1 except that the thickness of the binder resin layer was changed to 0.5 μm.

Example 4
Polyvinyl alcohol (manufactured by Kuraray Co., Ltd., product name: Poval 203) was weighed to 7.5 parts by weight and ion-exchanged water to 92.5 parts by weight. After ion-exchanged water was put into a beaker and heated to about 80 ° C., polyvinyl alcohol was added with stirring, and stirring was continued until the polyvinyl alcohol was completely dissolved. After cooling to room temperature, 0.0375 parts by weight of amorphous silica with a volume-based average particle size of 2.7 μm (manufactured by Fuji Cynthia Co., Ltd., product name: Cylicia (registered trademark) 310P) is added, and the silica is evenly mixed with a homogenizer. The mixture was stirred and mixed until dispersed to prepare a binder resin paint containing fine particles.
Next, the prepared binder resin coating is applied to the corona-treated surface of the double-sided corona-treated polyester film having a thickness of 50 μm by the Mayer bar method so that the thickness of the binder resin after drying becomes 1 μm, and the set temperature is set. Was heated for 3 minutes with a hot-air circulating dryer at 120 ° C. to obtain a polyester film having a surface irregularity on one side. Next, an addition reaction type silicone release agent (product name: LTC-1056L manufactured by Toray Dow Corning Co., Ltd., 18 parts by weight, manufactured by Shin-Etsu Chemical Co., Ltd.) is formed on the opposite surface (corona-treated surface) of the obtained polyester film. Product name: 40 parts by weight of KS-847T), 1 part by weight of platinum catalyst (manufactured by Toray Dow Corning, product name: SRX212 Catalyst), and 42 parts by weight of a 50/50 mixed solvent of toluene / ethyl acetate were mixed and mixed. The coating material was applied by the Mayer bar method so that the thickness after drying was 1.0 μm, and then heated for 1 minute in a hot air circulation dryer having a set temperature of 120 ° C. A release film was obtained.

(Comparative Example 1)
A release film of Comparative Example 1 was prepared in the same manner as in Example 1 except that the thickness of the release agent layer was 0.2 μm.

(Comparative Example 2)
A release film of Comparative Example 2 was obtained in the same manner as Example 1 except that the thickness after drying of the binder resin layer (ethylcellulose) was 1.5 μm. Comparative Example 2 is Production Example 7 in Table 1.

(Comparative Example 3)
On the corona-treated surface of a single-sided corona-treated polyester film having a thickness of 50 μm, platinum is added to 5 parts by weight of a light release type addition reaction type silicone release agent (product name: SRX-357, manufactured by Toray Dow Corning). A catalyst (manufactured by Dow Corning Toray, product name: SRX212 Catalyst) 0.05 parts by weight and 95 parts by weight of a 50/50 mixed solvent of toluene / ethyl acetate were mixed, and the mixed paint had a thickness of 0. After coating by the Mayer bar method so as to be 2 μm, it was heated for 1 minute in a hot-air circulating drier at a preset temperature of 120 ° C. to obtain a release film of Comparative Example 3.

(Comparative Example 4)
1 part by weight of platinum catalyst (product name: SRX212, manufactured by Toray Dow Corning Co., Ltd.) with respect to 30 parts by weight of addition reaction type silicone release agent (product of Toray Dow Corning Co., Ltd., product name: LTC-1056L), toluene / 70 parts by weight of a 50/50 mixed solvent of ethyl acetate was mixed, and the mixed resin was mixed with a silicone resin polymer fine particle having a volume-based average particle diameter of 2 μm (product name: Tospearl (registered trademark) 120 manufactured by Momentive Performance Materials). ) 0.0375 parts by weight were added and stirred and mixed to prepare a silicone release agent paint containing fine particles. Hot air circulation with a set temperature of 120 ° C by coating the prepared paint on the corona-treated surface of a single-sided corona-treated polyester film with a thickness of 50 µm using the Meyer bar method so that the thickness after drying is 1.0 µm. The mold release film of Comparative Example 4 was obtained by heating for 1 minute in an oven-type dryer.

  Various measurements and confirmation tests were performed on the release films obtained in Examples 1 to 4 and Comparative Examples 1 to 4. The method for confirming the presence or absence of blocking is as described above. Other test methods are as follows.

(Measurement of peel force)
A polyester adhesive tape (manufactured by Nitto Denko Corporation, product name: polyester tape No. 31B) is bonded to the surface of the release agent layer of the release film, and a load of 20 g / cm ² {0.196 N / cm ² } is applied. After aging at 70 ° C. for 20 hours, the peel strength when peeled at a peeling speed of 300 mm / min and a peeling angle of 180 ° with a desktop precision universal testing machine (manufactured by Shimadzu Corporation, Autograph (registered trademark)) The peeling force (mN / 50 mm) was measured.

(Measurement of residual adhesion rate)
The pressure-sensitive adhesive tape peeled off from the release film after the test according to the above (measurement of peel force) was pressure-bonded to the adherend (stainless steel plate) with a roller, and left for 1 hour in an environment of 23 ° C. and 55% RH. Then, the peeling force when peeling from the adherend was measured at a peeling speed of 300 mm / min and a peeling angle of 180 ° with a desktop precision universal testing machine (manufactured by Shimadzu Corporation, Autograph (registered trademark)). It was set as the residual adhesive force.
Separately from this, the peeling force when an unused pressure-sensitive adhesive tape was pressure-bonded to an adherend of the same material and peeled was measured in the same manner as a reference pressure-sensitive adhesive force.
The residual adhesive rate was calculated by the formula of (residual adhesive strength) / (reference adhesive strength) × 100 (%).

(Confirmation of adhesion of release agent layer)
After the test according to the above (measurement of peel force), the surface of the release agent layer of the release film was strongly rubbed with the belly of the finger three times, and then the rubbed portion was visually observed. From the base film, the presence or absence of the release agent layer was visually confirmed, and the release agent layer had almost no dropout (O), and the release agent layer had fallen off slightly. The case was evaluated as (Δ), and the case where the release agent layer was markedly dropped was determined as (×).

(Confirmation of solvent resistance of release agent layer)
The release agent layer of the release film is rubbed once and back in a state where a load is applied with a weight of 200 g using a non-woven fabric impregnated with ethyl acetate (Bencot (registered trademark) M-1 manufactured by Asahi Kasei Corporation). Then, the solvent resistance of the release agent layer of the release film was confirmed by visually observing the release agent layer of the release film. The surface of the release agent layer was confirmed with the naked eye, and it was determined that the appearance did not change (O), and the release agent dropped off (X).

(Measurement and confirmation test results)
Table 2 shows the results of various measurements and confirmation tests of the release films obtained in Examples 1 to 4 and Comparative Examples 1 to 4.

(Summary)
The release films of Examples 1 to 4 exhibited numerical values with very low peel force and very high residual adhesion. Further, in the release films of Examples 1 to 4, the release agent layer and the binder resin layer did not cause blocking, and the adhesiveness and solvent resistance of the silicone release agent were good. In contrast, the release film of Comparative Example 1 in which the release agent layer was thin resulted in heavy peeling (high peeling force). Further, the release film of Comparative Example 2 in which the unevenness of the fine particle-containing binder resin layer on the back side of the release agent is small (the ratio of the thickness of the binder resin layer to the average particle diameter of the fine particles is large) causes blocking. The peel strength also increased. The release film of Comparative Example 3 in which a commonly used light release type silicone was applied with a general coating amount was heavier than Examples 1 to 4 and had a remarkable residual adhesion rate. It was a bad result. The release film of Comparative Example 4 in which fine particles were contained in the silicone release agent gave good results in both the peeling force and the residual adhesion rate, but the result was poor adhesion and solvent resistance of the release agent layer. Met.

DESCRIPTION OF SYMBOLS 1 ... Base film, 2 ... Binder resin layer, 3 ... Inorganic fine particle or polymer fine particle, 4 ... Release agent layer, 5 ... Release film, 6 ... Adhesive layer, 7 ... Optical film, 8 ... Optical film and adhesion Laminated body with agent layer, 9 ... optical adhesive sheet, 10 ... optical film with adhesive.

Claims (4)

A release agent layer containing a silicone release agent is provided on one surface of the base film in a thickness of 0.4 to 2 μm, and the other surface contains inorganic fine particles and / or polymer fine particles as fine particles. A release film provided with a binder resin layer, wherein the fine particles, the binder resin layer, and the release agent layer satisfy the following conditions (1) and (2): Release film with excellent properties.
(1) The volume-based average particle diameter of the fine particles is at least twice the thickness of the release agent layer.
(2) The binder resin layer has a thickness in the range of 25 to 60% of the volume-based average particle diameter of the fine particles.   The inorganic fine particles are at least one selected from the group of inorganic particles consisting of silica, calcium carbonate, calcium phosphate, barium sulfate, kaolin, glass powder, talc, and the polymer fine particles are silicone resin, acrylic resin, polyamide The release according to claim 1, wherein the release agent is at least one selected from a group of polymer resin particles composed of a polymer resin, a polyester resin, a polyethylene resin, a polypropylene resin, a polystyrene resin, and an epoxy resin. Release film with excellent properties.   The release film according to claim 1 or 2, wherein the base film is a polyester resin film.   A laminate comprising a pressure-sensitive adhesive layer laminated on at least one surface of a resin film, or a single piece of the pressure-sensitive adhesive layer, and a release film excellent in peelability according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive is provided. A laminated film obtained by laminating a release film excellent in peelability on the surface of a layer via the release agent layer.

Images