CN105950041B

CN105950041B - Release film having excellent releasability

Info

Publication number: CN105950041B
Application number: CN201610059877.7A
Authority: CN
Inventors: 宫坂洋之; 林益史
Original assignee: Fujimori Kogyo Co Ltd
Current assignee: Fujimori Kogyo Co Ltd
Priority date: 2015-03-09
Filing date: 2016-01-28
Publication date: 2020-07-14
Anticipated expiration: 2036-01-28
Also published as: KR20180026696A; TWI681875B; KR101836212B1; CN105950041A; KR101987643B1; TWI778311B; TW201639703A; KR20160110082A; TW202010812A; JP2016165825A; JP6147284B2

Abstract

The invention provides a release film with excellent release performance, which has small release force, is difficult to increase the release force even in a state of being adhered to an adhesive layer after time, has little transfer of organosilicon components to the adhesive layer, and does not reduce the adhesive force of the adhered adhesive layer. The release film having excellent releasability is characterized in that a release film (5) having a release agent layer (4) containing a silicone release agent and having a thickness of 0.4 to 2 [ mu ] m on one surface of a base film (1) and a binder resin layer (2) containing inorganic fine particles and/or polymer fine particles as fine particles (3) on the other surface is provided, and the fine particles (3), the binder resin layer (2), and the release agent layer (4) satisfy the conditions (1) and (2): (1) the volume-based average particle diameter of the fine particles (3) is more than 2 times of 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).

Description

Release film having excellent releasability

Technical Field

The present invention relates to a release film for surface protection of various adhesive articles or objects having adhesive properties. More specifically, the present invention relates to a release film having excellent releasability, which has a low release force, is less likely to increase the release force with time even in a state of being bonded to an adhesive layer, and has little migration of a silicone (silicone) component to the adhesive layer, so that the adhesive force of the bonded adhesive layer is not reduced.

Background

Release films (also sometimes referred to as release films) have long been used for various purposes. For example, it is widely used for: release films for green sheets (green sheets) used in the production of various ceramic electronic components such as multilayer ceramic capacitors and ceramic substrates; a release film for optical parts having an adhesive layer, which is used in the production of polarizing plates, optical filters, flat panel displays, and the like; and release films for adhesive layers for bonding optical members used for bonding touch panel members or optical members to each other.

Green sheets used in the production of various ceramic electronic components such as multilayer ceramic capacitors and ceramic substrates are becoming thinner with the reduction in size and increase in capacitance of multilayer ceramic capacitors. Further, when the green sheet is peeled from the release film, the green sheet is broken when the release film has a large peeling force, and therefore, a release film having a smaller peeling force than the conventional one is desired.

On the other hand, optical members such as polarizing plates and retardation plates, which are members constituting liquid crystal displays, use adhesive layers for bonding the optical members to each other or to other members, and release films for protecting the adhesive layers.

Release films used for this purpose have been increased in size of displays, and optical members such as polarizing plates and release films have been increased in size, and it is necessary to be easily peeled even if the peeling area is large. Therefore, a release film having a lower peeling force than conventional films is desired. In addition, the adhesive layer for an optical member for bonding the components of the touch panel and the optical member to each other is formed of an adhesive layer having a weak cohesive force with the thinning of the tablet PC, the tablet terminal, the touch panel, and the like, so that even a thin adhesive layer can follow the height difference of the optical member (for example, the height difference of frame printing used for a cover glass (cover glass) of a mobile terminal or the like). However, when an adhesive layer having a weak cohesive force is used, the adhesive layer for an optical member is deformed when the peel force of the release film is too large, and thus a release film having a smaller peel force than the conventional release film is desired.

In this way, release films having a lower peeling force than conventional release films have been desired for use in molding of ceramic green sheets and various release films for optical components having an adhesive layer. Against the background of the above-mentioned circumstances, patent document 1 proposes a release film using cured silicon containing silicone having only one vinyl group in the molecule.

Further, patent document 2 proposes a release film in which an anti-settling layer of an oligomer is applied to one surface of a polyester film, and a release layer containing a solventless addition reaction curable silicone is provided thereon, the tape peeling force is 15mN/cm or less, and the transfer evaluation adhesion rate of a silicone component is 90% or more.

Further, patent document 3 proposes a release film obtained by applying heat treatment to a functional group-free polydimethylsiloxane or other addition reaction type silicone without adding a light release component (light peeling component) at 50 to 65 ℃ for 20 hours or more, wherein the release force of an acrylic adhesive is 0.15N/50mm or less, and the residual adhesion rate is 90% or more.

Patent documents 1 to 3 each propose a release film having a small peeling force and not reducing the adhesive force of the pressure-sensitive adhesive layer to be bonded. However, in the release film described in patent document 1, since cured silicon containing silicone having only one vinyl group in the molecule is used, if the vinyl group reaction is incomplete, the silicone having only one vinyl group migrates to the pressure-sensitive adhesive layer, and thus there is a concern that the adhesive strength of the pressure-sensitive adhesive layer is lowered.

The release film described in patent document 2 is different from a conventional release film in that an anti-settling layer of an oligomer is provided. However, since a solventless addition reaction curable silicone is used, the release properties fall into the category of conventional release films.

Further, the release film described in patent document 3 is a release film with light peeling properties obtained by curing (aging) an addition reaction type silicone to which no light peeling component is added. In this case, although a release film that does not reduce the adhesive strength of the pressure-sensitive adhesive layer to be bonded can be obtained by light peeling, it is difficult to further reduce the peeling force.

In addition, the release film described in patent document 4 is formed by forming a silicone release layer containing inert particles (inert particles) having a predetermined particle size in a polyester film into a release film having a predetermined thickness. By adding the inert particles having a predetermined particle size to the silicone release layer, blocking (a phenomenon in which the back surface of the release film is bonded to the release layer in a pseudo manner and the release layer cannot be wound smoothly when the release film is wound in a roll shape) which occurs when the silicone release layer is thickened is solved. However, the silicone release layer becomes discontinuous due to the inert particles, and when the solvent is contacted, the solvent may penetrate into the interface between the inert particles and the silicone, and the silicone may be released. Further, since the inert particles having a particle diameter larger than the thickness of the silicone release layer are added, when the release film is used for surface protection of the pressure-sensitive adhesive layer, the inert particles may adhere to the pressure-sensitive adhesive layer side, and the adhesive force of the pressure-sensitive adhesive layer may be lowered.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2008-265227

Patent document 2: japanese unexamined patent publication No. 2012-136612

Patent document 3: japanese unexamined patent publication No. 2006-007689

Patent document 4: japanese laid-open patent publication No. 2013-208897

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a release film having excellent releasability, which has a low releasability, is less likely to have a large releasability even when the release film is bonded to an adhesive layer over time, and has little silicone component migration to the adhesive layer, and thus does not reduce the adhesive strength of the bonded adhesive layer.

Means for solving the problems

As a result of earnest studies for solving the above problems, it has been found that a release film using a silicone-based release agent (also referred to as a "release agent") needs to be a release film in which silicone is less transferred to an adhesive layer so as not to decrease the adhesive force of the adhesive layer. Further, even when a silicone-based release agent in which silicone is less transferred to the pressure-sensitive adhesive layer is used, it has been found that the release force can be reduced by setting the thickness of the release agent layer to a specific thickness or more. However, it was found that when the thickness of the release agent layer was increased, the release film was wound into a roll shape, and the release agent layer was stuck to the back surface of the release film, and the release film could not be smoothly wound back into a roll shape. In the production process of the base film for the release film, the base film is formed by containing lubricant particles therein so that the base film does not cause blocking even when wound in a roll shape. Therefore, although the surface of the substrate film has an uneven structure on the back surface of the release film, the uneven structure in which the release agent layer fills the surface of the substrate film is considered to be a cause of blocking by increasing the thickness of the release agent layer.

Further, the present invention can be completed by earnest studies on a method of achieving both of the releasability and the blocking resistance. The invention makes the thickness of the release agent layer more than 0.4 μm in order to reduce the peeling force even in the case of using the release agent with little transfer of the organic silicon component to the adhesive layer. In addition, the technical idea of the present invention is to form a concave-convex shape having surface roughness corresponding to the thickness of a release agent layer on the surface of a base material film opposite to the release agent layer in order to prevent blocking between the release agent layer and the back surface of a release film, thereby achieving both peeling property and blocking resistance.

In order to solve the above problems, the present invention provides a release film, comprising a base film, a release agent layer containing a silicone release agent and having a thickness of 0.4 to 2 μm provided on one surface of the base film, and a binder resin layer containing inorganic fine particles and/or polymer fine particles as fine particles provided on the other surface of the base film, wherein the fine particles, the binder resin layer and the release agent layer satisfy (1) that a volume-based average particle diameter of the fine particles is 2 times or more of a thickness of the release agent layer, and (2) that a thickness of the binder resin layer is in a range of 25 to 60% of the volume-based average particle diameter of the fine particles.

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 fine polymer particles are preferably at least one selected from the group of polymer resin particles consisting of silicone resins, acrylic resins, polyamide resins, polyester resins, polyethylene resins, polypropylene resins, polystyrene resins, and epoxy resins.

Further, the substrate film is preferably a polyester resin film.

The present invention also provides a laminated film comprising a laminate or a single adhesive layer in which an adhesive layer is laminated on at least one surface of a resin film, and the release film, wherein the release film is laminated on the surface of the adhesive layer via the release agent layer.

Effects of the invention

According to the present invention, a release film for molding a ceramic green sheet and a release film excellent in releasability from various optical members having an adhesive layer can be provided. Further, the present invention can provide a release film having excellent releasability, which has a low release force, is less likely to increase the release force even after a lapse of time in a state of being bonded to an adhesive layer, and has little migration of a silicone component to the adhesive layer, so that the adhesive force of the bonded adhesive layer is not reduced.

Further, the release film of the present invention does not reduce the adhesive force of the adhesive layer to be bonded, and can be smoothly rolled back without blocking even when wound in a roll shape, so that excellent releasability and blocking resistance are both achieved, and the release film has a high industrial value.

Drawings

FIG. 1 is a sectional view schematically showing an example of a release film of the present invention;

FIG. 2 is a sectional view schematically showing an example of embodiment 1 of the laminated film of the present invention;

fig. 3 is a sectional view schematically showing an example of embodiment 2 of the laminated film of the present invention.

Description of the reference numerals

1 is a substrate film, 2 is an adhesive resin layer, 3 is inorganic fine particles or polymer fine particles, 4 is a release agent layer, 5 is a release film, 6 is an adhesive layer, 7 is an optical film, 8 is a laminate of an optical film and an adhesive layer, 9 is an optical adhesive sheet, and 10 is a tacky optical film.

Detailed Description

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 pressure-sensitive adhesive resin layer 2 is formed on one surface of a base film 1, and a silicone-based release agent layer 4 is formed on the opposite surface of the base film 1.

The binder resin layer 2 contains inorganic fine particles and/or polymer fine particles as the fine particles 3 for preventing adhesion.

In the release film 5 of the present invention, the resin film used as the base film 1 may be selected according to the application, and examples thereof include a polyester resin film, a polyamide resin film, a polyimide resin film, a polyolefin resin film, a polyvinyl chloride resin film, a polystyrene resin film, an acrylic resin film, an acetate resin film, and a polyphenylene sulfide resin film.

Among them, polyester resin films are preferable from the viewpoints of optical properties, heat resistance, and other properties, price, appearance and taste. 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 characteristics. In addition, from the viewpoint of optical properties, polyethylene terephthalate for optical use which is a uniaxially stretched product or a biaxially stretched product is preferable.

Further, if necessary, an easy adhesion treatment such as surface modification by plasma discharge or corona discharge, coating with an anchor coating agent, or the like may be applied to the surface of the base film 1.

The thickness of the base film 1 is not particularly limited, and the thickness of the base film 1 is preferably about 10 to 200 μm in consideration of ease of handling as the release film 5 or ease of winding the release film 5 into a roll.

In the present invention, even if the thickness of the release agent layer containing the silicone-based release agent is increased, the uneven structure conforming to the surface roughness of the release agent layer thickness is formed on the surface of the substrate film 1 opposite to the release agent layer, so that the release agent layer does not stick to the back surface of the release film when bonded thereto. The uneven structure is formed on the surface of the base film 1 by coating the binder resin layer 2 containing inorganic fine particles and/or polymer fine particles as the fine particles 3 for blocking prevention.

Examples of the inorganic fine particles and/or polymer fine particles serving as the fine particles 3 for blocking resistance include inorganic fine particles that are inorganic compound fine particles and polymer fine particles that are polymer resin fine particles. Either one of the inorganic fine particles and the polymer fine particles may be used, or both of them may be used. 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 fine polymer particles are preferably at least one selected from the group of polymer resin particles consisting of silicone resins, acrylic resins, polyamide resins, polyester resins, polyethylene resins, polypropylene resins, polystyrene resins, and epoxy resins.

The shape of the fine particles 3 is not particularly limited, but may be spherical, rod-like, scaly, hemispherical, lenticular, mushroom-like, irregular, etc., and spherical or nearly spherical shapes are more preferable because they easily exhibit anti-blocking performance.

The particle diameter of the fine particles 3 is preferably 2 times or more the thickness of the release agent layer 4 as the volume-based average particle diameter. If the volume-based average particle diameter of the fine particles 3 is less than 2 times the thickness of the release agent layer 4, the anti-blocking property may be reduced. The anti-blocking property can be obtained when the volume-based average particle diameter of the fine particles 3 is 2 times or more the thickness of the release agent layer 4. The upper limit of the volume-based average particle diameter of the fine particles 3 is not particularly problematic, but when the volume-based average particle diameter of the fine particles 3 is increased, the thickness of the binder resin layer 2 needs to be increased, which increases the cost. Therefore, the volume-based average particle diameter of the fine particles 3 is preferably controlled to be about 10 times the thickness of the release agent layer 4. Further, since the particles having a large volume function largely depending on the volume-based average particle diameter and the particles having a small volume have little influence even if mixed therein, the anti-blocking property can be obtained as long as at least a part of the particles have a particle diameter of 2 times or more the thickness of the release agent layer 4.

The resin used for the binder resin layer 2 is not particularly limited as long as the fine particles 3 are dispersed and adhered to the base film 1. Examples of the coating agent include polyester resins, acrylic resins, polyurethane resins, alkyd resins, silicone resins, cellulose resins, polyvinyl alcohol, silane coating agents, and silicate coating agents.

The resin used for the adhesive resin layer 2 may be water-based, non-water-based (solvent-based), or solvent-free. The thickness of the binder resin layer 2 is preferably in the range of 25 to 60% of the volume-based average particle diameter of the fine particles 3. If 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 (anchoring force) of the fine particles 3 is reduced, and the fine particles 3 are likely to fall off. Further, if the thickness of the pressure-sensitive adhesive resin layer 2 exceeds 60% of the volume-based average particle diameter of the fine particles, problems such as a decrease in anti-blocking performance and high cost are caused, which is not preferable.

The fine particles 3 are mixed with the resin forming the binder resin layer 2 and applied to the base film 1. A part (upper part) of the fine particles 3 protrudes from the thickness of the binder resin layer 2 (average thickness of a 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 terms of preventing blocking of the release film, it is important that the microparticles 3, the adhesive 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 2 times or more of 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 method of mixing and dispersing the fine particles 3 in the binder resin may be performed by a known method depending on the types of the binder resin and the fine particles. In the case of a system in which fine particles are easily dispersed in a binder resin, the fine particles may be mixed by stirring with a hand-held device such as a spatula (spatula). Even in a combination in which the fine particles are hardly dispersed in the binder resin or in a system in which the fine particles are easily dispersed, when the binder resin and the fine particles are in a large amount, the dispersion and mixing may be performed by using a disperser such as a homogenizer (homogen) or a homomixer (homomixer). In addition to the fine particles and the binder resin, a surfactant, a coloring agent, an antistatic agent, a lubricant such as paraffin, an antifouling agent such as silicone or fluorine, a leveling agent, a curing agent, an antiseptic, and the like may be added as necessary.

The binder resin layer 2 containing the fine particles 3 may be formed by applying the binder resin containing the fine particles 3 to the base film 1. 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 thereof include a meyer bar method, a gravure method, an inverse roll method, an air knife method, and a multi-stage roll method.

The curing (curing) or solidification (solidifying) of the binder resin layer 2 containing the fine particles 3 may be performed depending on the type of the binder resin. For example, the solvent, water, or the like may be removed by heating and drying, or the binder resin may be cured by ultraviolet irradiation, electron beam irradiation, or the like.

Examples of the silicone release agent used in the release agent layer 4 include known silicone release agents such as addition reaction type, condensation reaction type, cationic polymerization type, and radical polymerization type (radial polymerization type). examples of the silicone release agent commercially available as the addition reaction type silicone release agent include KS-776A, KS-77642, KS-847T, KS-779-637, KS-778, KS-830, KS-774, KS-3565, X-62-2829, KS-3650, KNS-3051, KNS-320-45-316, KNS-3002, X-62-1387 (manufactured by shin chemical industries, Inc. (products), SRX-211, SRX-345, SRX-357, DR7333, Torre 20, SD-300, SD-720-7260-729, SD-659, SD-675, Softhe silicone release agents such as Mortymetrix-675-TPR 675, TPR-659-TPR 675, TPR-659-6520, TPR-80, TPR-5, TPR-5-TPR-659-5, TPR-5, TPR-9-TPR-D-9-TPR-9-No. commercially available as the addition reaction type silicone release agent, TPR-9, TPR-5, TPR-9-TPR-9, TPR-5, TPR-9, TPR-9, TPR-No. commercially available as the addition reaction type silicone release agent, TPR-9, TPR-9, TPR-No. commercially available as the silicone release agent, TPR-No. commercially available as the addition reaction type silicone release agent, TPR-TPR.

The silicone release agent used in the release film of the present invention may be used alone or in combination of a plurality of types. Further, components other than the silicone-based release agent such as a silane coupling agent, an antistatic agent, and a wettability improver may be added, and the components may be determined in consideration of releasability, coatability, curability, and the like. The coating of the release agent can be carried out by a known method, and is not particularly limited, and examples thereof include a meyer bar method, a gravure method, a reverse roll method, an air knife method, a multi-roll method, and the like. Examples of the method for curing the silicone-based release agent include heat curing, ultraviolet curing, electron beam curing, and simultaneous use of heat and ultraviolet irradiation, and an appropriate method may be selected depending on the type of the silicone-based release agent. The thickness of the release agent layer 4 containing the silicone release agent is, for example, 0.4 to 2 μm. If the thickness of the release agent layer 4 is less 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, and when the thickness of the release agent layer 4 is increased, the volume-based average particle diameter of the fine particles 3 needs to be increased and the thickness of the adhesive resin layer 2 needs to be increased, which increases the cost. Therefore, the thickness of the release agent layer 4 is preferably controlled to about 2 μm.

When the release film 5 of the present invention is used for a release sheet for molding green sheets used in the production of various ceramic electronic components, the green sheets are formed by applying and drying a slurry in which ceramic particles are dispersed in an organic solvent. In the release film 5 for green sheet protection, solvent resistance is required for the release agent layer 4. The release agent layer 4 of the present invention does not contain the fine particles 3, is a release agent layer 4 in which a silicone-based release agent is not discontinuous and which has excellent solvent resistance, and can be suitably used for the purpose of protecting green sheets. The present invention can be suitably used not only for green sheets but also for protecting the surface of a coating film containing various powders dispersed therein, such as a conductor paste and an insulating paste, and a coating film containing a solvent.

Fig. 2 is a sectional view schematically showing an example of embodiment 1 of the laminated film of the present invention. The tacky optical film 10 of fig. 2 is an application in which the release film 5 of the present invention is used to protect the adhesive layer 6 laminated on the optical film 7. An optical film 7 is bonded to the release film 5 of the present invention shown in fig. 1 via an adhesive layer 6. The method for producing the adhesive optical film 10 may be to apply a solvent-based adhesive to the release film 5, dry the adhesive, and then attach the optical film 7. In the release film 5 for use in protecting the adhesive layer 6, solvent resistance is required for the release agent layer 4. The release agent layer 4 of the present invention does not contain the fine particles 3, is a release agent layer 4 in which a silicone-based release agent is not discontinuous and which has excellent solvent resistance, and can be suitably used for the purpose of protecting the adhesive layer 6. The laminate containing the adhesive layer 6 may contain 1 or 2 or more resin films and 1 or 2 or more adhesive layers. For example, the pressure-sensitive adhesive layers 6 may be provided on both surfaces of the optical film 7, and the release film 5 may be bonded to each of the pressure-sensitive adhesive layers 6. As another manufacturing method, the release film 5 may be bonded to the laminate 8 having the adhesive layer 6 on one surface of the optical film 7. Alternatively, after the solvent-free adhesive is applied, the adhesive layer 6 can be cured by light, heat, or the like between the release film 5 and the optical film 7.

Fig. 3 is a cross-sectional view schematically showing an example of embodiment 2 of the laminated film of the present invention. The optical adhesive sheet 9 of fig. 3 is formed by bonding the release film 5 of the present invention to the adhesive layer 6 for bonding the touch panel member and the optical member so as to protect the adhesive layer 6. The optical adhesive sheet 9 is in a form in which the adhesive layer 6 is sandwiched between two release films 5. In the method for producing the optical adhesive sheet 9, a solvent-based adhesive is generally applied and dried on one release film 5, and then the sheet is bonded to another release film 5. In the release film 5 for use in protecting the adhesive layer 6, solvent resistance is required for the release agent layer 4. The release agent layer 4 of the present invention does not contain the fine particles 3, is a release agent layer 4 in which a silicone-based release agent is not discontinuous and which has excellent solvent resistance, and can be suitably used for the purpose of protecting the adhesive layer 6.

The adhesive used for the adhesive layer 6 may be water-based, non-water-based (solvent-based), or solvent-free. The pressure-sensitive adhesive may be any of acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, rubber pressure-sensitive adhesives, urethane pressure-sensitive adhesives, and the like. Acrylic adhesives are preferred because they are excellent in transparency and weather resistance.

The resin film used for the laminate film is not limited to the optical film 7 as long as it is an opaque resin film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an anti-glare (anti-glare) film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, a brightness enhancement film, and a high transparency film.

Examples

The present invention will be specifically described below with reference to examples.

(Release film of example 1)

A silicone resin polymer fine particle (product name: ETHOCE L (registered trademark) 100FP, manufactured by DOW Chemical Co., Ltd.) in an amount of 7.5 parts by weight, 0.0375 parts by weight, a silicone resin polymer fine particle (product name: Tospaarl (registered trademark)) having an average particle diameter (volume-based average particle diameter) of 2 μm, and 50/50 mixed solvent of 92.5 parts by weight of toluene/ethyl acetate were charged into a beaker and mixed, and the mixture was stirred until the ethyl cellulose was dissolved to prepare a coating material, then a polyester film having surface irregularities on one surface was obtained by coating a corona-untreated surface of a single-sided corona-treated polyester film having a thickness of 50 μm by a Meyer rod method so that the thickness of the dried binder resin was 1.0 μm, heating for 1 minute by a hot air circulation dryer at 120 ℃ to obtain a polyester film having surface irregularities on one surface, then, coating a release coating material (product name: Dow Corona) having surface irregularities on the opposite surface of the obtained polyester film provided with a corona-treated surface by a Toray rod addition reaction, drying a silicone resin by a Town-type coating material (product name: 120 parts by a Town-dryer, drying temperature: 3670 parts by a Dow hot air dryer, L, drying a silicone resin mixed solvent (Dow) and drying method, wherein Dow mixing a silicone resin is used is added, and the silicone resin is added to obtain a silicone resin coating material (Dow) and the silicone resin mixed solvent, wherein the coating material is added and the silicone resin is added to obtain a silicone resin mixture, and the coating material, and the silicone resin is.

(confirmation of blocking Property)

In example 1, the thickness of the binder resin layer (ethyl cellulose) and the release agent layer and the type of silicone resin polymer microparticles were changed to obtain release films of production examples 1 to 12, and example 1 was production example 5 of table 1.

With respect to the release films of production examples 1 to 12 obtained, a confirmation experiment was conducted on whether or not the release agent layer and the adhesive resin layer were stuck and whether or not particles were detached.

(confirmation of presence or absence of adhesion)

A sample in which 3 sheets of release films were stacked was prepared and sandwiched between two stainless steel plates (SUS 304). On the sample, to apply 20g/cm²{0.196N/cm²The state of the load was left to stand at 23 ℃ and 50% RH for 24 hours, then 3 pieces of the overlapped release films were taken out, and the release films were peeled one by hand to confirm the adhesion state, and no adhesion was observed, the release films were easily peeled off with good adhesion (○), slight poor adhesion (Δ) was observed in the case of slight resistance in the case of peeling the release films, and poor adhesion was observed in the case of significant resistance in the case of peeling the release films (×).

(confirmation of Presence or absence of particle shedding)

The release film was wiped with a nonwoven fabric (bemcot (registered trademark) M-1, manufactured by asahi chemical fiber corporation) in a state of being loaded with a 200g weight, and the coated surface of the release film containing the fine particles was wiped in one reciprocating motion, and then the wiped portion of the sample was observed with a laser microscope, and the number of the remaining portions and the dropped portions of the fine particles was measured at 10 points, and it was found that the dropping of the fine particles was good at less than 30% (○) and the dropping of the fine particles was bad at 30% or more (×).

(confirmation of test results)

The results of the confirmation test are shown in table 1.

[ Table 1]

As is clear from the results of the confirmation tests shown in table 1, as the condition that the release agent layer and the adhesive resin layer do not block, the thicker the release agent layer becomes, the larger the surface roughness (unevenness) of the adhesive resin layer needs to be. Further, as the results of the confirmation test shown in table 1, as the conditions under which the release agent layer and the adhesive resin layer do not block, the following relationship between the volume-based average particle diameter of the fine particles (inorganic fine particles or polymer fine particles) and the thickness of the release agent layer and the relationship between the thickness of the adhesive resin layer and the average particle diameter of the fine particles (inorganic fine particles or polymer fine particles) were obtained:

(i) the average particle diameter of the particles is more than 2 times of the thickness of the release agent layer;

(ii) the thickness of the binder resin layer is less than 75% relative to the average particle diameter of the microparticles.

On the other hand, as a condition for preventing the fine particles from falling off from the binder resin layer containing the fine particles, it is necessary to increase the thickness of the binder resin layer with respect to the average particle diameter of the fine particles. From the results of the confirmation test shown in table 1, the following thickness of the binder resin layer that does not cause the microparticles to fall off from the binder resin layer containing the microparticles was derived:

(iii) the thickness of the binder resin layer is 25% or more of the average particle diameter of the fine particles.

In addition, as is clear from the results of the confirmation tests shown in table 1, in the condition (ii), the release agent layer and the adhesive resin layer do not block if the thickness of the adhesive resin layer is 60% or less with respect to the volume-based average particle diameter of the fine particles, as compared with the production example 6 and the production example 7.

That is, according to the results of the confirmation test shown in table 1, as the conditions under which the release agent layer and the adhesive resin layer do not block and the conditions under which the microparticles do not fall off from the adhesive resin layer containing the microparticles, the following conditions were obtained:

(1) the average particle diameter of the particles is more than 2 times of 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 produced in the same manner as in example 1, except that the thickness of the release agent layer was set to 0.4 μm.

(example 3)

A release film of example 3 was produced in the same manner as in example 1, except that the thickness of the release agent layer was set to 0.5 μm.

(example 4)

A particulate-containing binder resin coating material was prepared by weighing 7.5 parts by weight of polyvinyl alcohol (trade name: POVA L203, manufactured by Colorado) and 92.5 parts by weight of ion-exchanged water, adding the ion-exchanged water to a beaker, heating the beaker to about 80 ℃, adding polyvinyl alcohol while stirring, continuing to stir until the polyvinyl alcohol was completely dissolved, cooling the beaker to room temperature, adding 0.0375 parts by weight of amorphous silica (trade name: sylysia (registered trademark) 310P, manufactured by Fuji Silysia) having a volume-based average particle diameter of 2.7 μm, and stirring and mixing the mixture with a homogenizer until the silica was uniformly dispersed.

Then, a prepared adhesive resin coating material was applied to the corona-treated surface of the polyester film having a thickness of 50 μm and both surfaces corona-treated, the adhesive resin after drying was made to have a thickness of 1 μm, and the polyester film having a surface roughness on one surface was obtained by heating for 3 minutes using a heated air circulation dryer having a set temperature of 120 ℃.

Comparative example 1

A release film of comparative example 1 was produced in the same manner as in example 1, except that the thickness of the release agent layer was set to 0.2 μm.

Comparative example 2

A release film of comparative example 2 was produced in the same manner as in example 1, except that the thickness of the adhesive resin layer (ethyl cellulose) after drying was set to 1.5 μm. Further, comparative example 2 is production example 7 of table 1.

Comparative example 3

A coating material obtained by mixing 5 parts by weight of a light-release addition reaction type silicone release agent (product name: SRX-357, manufactured by Dow Corning Toray) and 95 parts by weight of a 50/50 mixed solvent of toluene/ethyl acetate with 0.05 part by weight of a platinum catalyst (product name: SRX212CATA L YST, manufactured by Dow Corning Toray) was applied to the corona-treated surface of a single-sided corona-treated polyester film having a thickness of 50 μm by the Meyer rod method so that the thickness after drying was 0.2 μm, and the resultant was heated for 1 minute using a hot air circulation dryer set at 120 ℃ to obtain a release film of comparative example 3.

Comparative example 4

1 part by weight of a platinum catalyst (product name: L TC-1056L, manufactured by Dow Corning Toray Co., Ltd.) and 70 parts by weight of a 50/50 mixed solvent of toluene/ethyl acetate were mixed with 30 parts by weight of an addition reaction type silicone release agent (product name: SRX212, manufactured by Dow Corning Toray Co., Ltd.), 0.0375 part by weight of silicone resin polymer fine particles (product name: PETOAR L (registered trademark) 120, manufactured by Momentive Performance Materials Co., Ltd.) having a volume-based average particle diameter of 2 μm was added to the mixed coating material, and the mixture was stirred and mixed to prepare a silicone release agent coating material containing the fine particles, and the coating material was applied onto the corona-treated surface of a single-sided corona-treated polyester film having a thickness of 50 μm by a Meyer rod method so that the dried film has a thickness of 1.0 μm, and was heated for 1 minute by a hot air circulation dryer set at 120 ℃ to obtain a release film of comparative example 4.

Various measurement and confirmation tests were carried out on the release films obtained in examples 1 to 4 and comparative examples 1 to 4. The method of confirming the presence or absence of adhesion is as described above. Other test methods are described below.

(measurement of peeling force)

A polyester adhesive tape (trade name: polyester tape No.31B, manufactured by Ridong electric Co., Ltd.) was bonded to the surface of the release agent layer of the release film at a ratio of 20g/cm²{0.196N/cm²The resin composition was aged at 70 ℃ for 20 hours under a load, and then the peel strength at a peel speed of 300 mm/min and a peel angle of 180 ℃ was measured as a peel force (mN/50mm) using a bench type precision universal tester (Autograph (registered trademark), manufactured by Shimadzu corporation).

(measurement of residual adhesion ratio)

The pressure-sensitive adhesive tape peeled from the release film after the above-described test (measurement of peel force) was pressure-bonded to an adherend (stainless steel plate) with a roller, and after being left for 1 hour in an environment of 23 ℃ and 55% RH, the peel force when peeled from the adherend at a peel speed of 300 mm/min and a peel angle of 180 ° was measured as a residual adhesive force using a bench-top precision universal tester (Autograph (registered trademark), manufactured by shimadzu corporation).

In the same manner, the peel strength when an unused adhesive tape was peeled off by pressure-bonding it to an adherend of the same material was measured as a reference adhesive strength.

The residual adhesion rate was calculated by the formula (residual adhesion force)/(reference adhesion force) × 100 (%).

(confirmation of adhesion of Release agent layer)

The surface of the release agent layer of the release film after the above test (measurement of peeling force) was strongly rubbed 3 times with fingers, and then the rubbed portion was visually observed, and the evaluation of the presence or absence of release agent layer peeling from the substrate film and almost no release agent layer peeling was visually confirmed was (○), the evaluation of the release agent layer slightly peeling was (△), and the evaluation of the release agent layer significantly peeling was (×).

(confirmation of solvent resistance of Release agent layer)

The release agent layer of the release film was wiped back and forth once with a load of 200g weight using a nonwoven fabric impregnated with ethyl acetate (bemcot (registered trademark) M-1, manufactured by asahi chemical fiber corporation) and 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 visually confirmed, the appearance was not changed and the release agent was peeled and evaluated as (○) and (×).

(measurement and confirmation of test results)

The results of various measurement and confirmation tests of the release films obtained in examples 1 to 4 and comparative examples 1 to 4 are shown in table 2.

[ Table 2]

(conclusion)

The release films of examples 1 to 4 had very low peel force and exhibited very high residual adhesion. In addition, the release agent layers of the release films of examples 1 to 4 did not adhere to the adhesive resin layer, and the silicone release agents were also excellent in adhesion and solvent resistance. In contrast, the release film of comparative example 1, in which the thickness of the release agent layer was small, exhibited a heavy peeling force (a large peeling force). Further, the release film of comparative example 2 in which the unevenness of the pressure-sensitive adhesive resin layer containing fine particles on the back side of the release agent was small (the ratio of the thickness of the pressure-sensitive adhesive resin layer to the average particle diameter of the fine particles was large) was blocked, and the release force was also increased. The release film of comparative example 3, which was coated with a light release silicone used in general at a normal coating amount, was heavier in peel than those of examples 1 to 4, and was significantly inferior in residual adhesion rate. The release film of comparative example 4 containing fine particles in the silicone-based release agent also had good results in terms of peel force and residual adhesion rate, but the release agent layer had poor adhesion and solvent resistance.

Claims

1. A release film having excellent releasability, characterized in that a release agent layer having a thickness of 0.4 to 2 [ mu ] m and containing a silicone-based release agent is provided on one surface of a base film, a pressure-sensitive adhesive resin layer containing fine inorganic particles and/or fine polymer particles is provided on the other surface of the base film, the release film is bonded to the surface of the pressure-sensitive adhesive layer via the release agent layer, and the fine particles, the pressure-sensitive adhesive resin layer and the release agent layer satisfy the following conditions (1) and (2) at the same time:

(1) the volume-based average particle diameter of the microparticles is more than 2 times of 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 volume-based average particle diameter of the fine particles.

2. The release film having excellent releasability according to claim 1, wherein the inorganic fine particles are at least one selected from the group consisting of inorganic particles comprising silica, calcium carbonate, calcium phosphate, barium sulfate, kaolin, glass frit and talc, and the polymer fine particles are at least one selected from the group consisting of polymer resin particles comprising silicone resin, acrylic resin, polyamide resin, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin and epoxy resin.

3. The release film excellent in releasability according to claim 1 or 2, wherein the substrate film is a polyester resin film.

4. A laminated film comprising a laminate or a single adhesive layer in which an adhesive layer is laminated on at least one surface of a resin film, and the release film having excellent releasability according to any one of claims 1 to 3, wherein the release film having excellent releasability is formed by bonding the release film having excellent releasability to the surface of the adhesive layer through the release agent layer.