KR20200029414A - Release film having excellent peelability - Google Patents

Abstract

The present invention provides a release film with excellent peelability, which has small peel strength, of which the peel strength is difficult to increase even when time elapses in a state of being attached to an adhesive layer, and which does not lower adhesion of the attached adhesive layer since transition of a silicon component to the adhesive layer is low. In addition, the provided release film has a low quantity of charge when being handled, and peeled from an adherend. The release film (5) having, on at least one side surface of a base film (1), a two-layered release agent layer in which a first release agent layer (2) including an antistatic agent but not including particles, and a second release agent layer (4) including particles (3) are stacked in order. The total thickness of the first release agent layer (2) and the second release layer (4) is 0.4-2.0 μm; the protrusion height from the surface of the second release agent layer (4) to the peak of the particle (3) is greater than the above total thickness; and the release agent layers (2, 4) on both side surfaces include a silicon-based release agent.

Description

Release film with excellent peelability {RELEASE FILM HAVING EXCELLENT PEELABILITY}

The present invention relates to a release film used for the protection of an adhesive layer in an optical member having various adhesive products or an adhesive layer. More specifically, since the peeling force is small and the peeling force is difficult to increase even when the adhesive layer is pasted with time, and the migration of the silicone component to the adhesive layer is small, the adhesive force of the bonded adhesive layer is not reduced. It is a release film excellent in peelability, and also relates to a release film with a small amount of charge when handling the release film and when the release film is peeled from the adherend.

Conventionally, a release film (sometimes called a peeling film) is used for various uses. Among them, an optical member having a release film for molding a green sheet used in the manufacture of various ceramic electronic components such as a ceramic multilayer capacitor, a ceramic substrate, a pressure-sensitive adhesive layer used in manufacturing a polarizing plate, an optical filter, a flat panel display, etc. It is widely used for a release film for dragons, a release film for a pressure-sensitive adhesive layer for bonding optical members for bonding a touch panel member or an optical member.

Green sheets used in the manufacture of various ceramic electronic components, such as ceramic multilayer capacitors and ceramic substrates, are becoming thinner with the miniaturization and larger capacity of ceramic multilayer capacitors. When the green sheet is peeled from the release film, a release film having a smaller peel force than the prior art is required in that the green sheet is damaged when the release force of the release film is large.

On the other hand, in optical members, such as polarizing plates and retardation plates, which are members constituting a liquid crystal display, a release film is used to protect the pressure-sensitive adhesive layer for the purpose of bonding optical members formed on the optical member to each other or to other members.

The release film used for this application is required to be able to peel lightly even when the peeling area is large, as the dimensions of the optical member such as a polarizing plate and the release film become large as the display is enlarged. For this reason, there is a demand for a release film having a smaller peel force than conventional ones. In addition, with respect to the pressure-sensitive adhesive layer for optical members for bonding the structural members and the optical members of the touch panel, with the thinning of tablet PCs, tablet terminals, touch panels, etc., even if the pressure-sensitive adhesive layer is a thin film, the step of the optical member (e.g. For example, a pressure-sensitive adhesive layer having a weak cohesive force is used so as to follow the frame printing step used in the cover glass of a portable terminal or the like. However, when a pressure-sensitive adhesive layer having a weak cohesive force is used, a release film having a low peel strength is required compared to the conventional one in that the pressure-sensitive adhesive layer for optical members is deformed when the release force of the release film is too large.

As described above, as a release film for forming a ceramic green sheet and a release film for an optical member having various pressure-sensitive adhesive layers, a release film having a small peel force is required compared to the prior art. Against this background, Patent Document 1 proposes a release film using a cured silicone containing silicone having only one vinyl group in its molecule.

In addition, in Patent Document 2, an anti-precipitation layer of an oligomer is formed on one side of a polyester film, and there is a release layer containing a solvent-free addition-reaction-curable silicone, and the tape peel force is 15 mN / cm or less. Release performance evaluation of silicone-based component A release film having an adhesion rate of 90% or more has been proposed.

In addition, Patent Literature 3 is a release film in which an addition-reactive silicone that does not contain a light-release component such as polydimethylsiloxane having no functional group is added and heat-treated in an environment of 50 to 65 ° C for 20 hours or longer, and an acrylic adhesive. A release film having a peel force of 0.15 N / 50 mm or less and a residual adhesion rate of 90% or more has been proposed.

In Patent Documents 1 to 3, a release film is proposed in which the peeling force is small and the adhesive force of the bonded adhesive layer is not reduced. However, since the release film described in Patent Document 1 uses a cured silicone containing silicone having only one vinyl group in its molecule, if the vinyl group is not completely reacted, silicone having only one vinyl group is transferred to the adhesive layer, and the adhesive layer It is concerned that the adhesive force of.

The release film described in Patent Document 2 is different from the conventional release film in that an oligomer precipitation prevention layer is formed. However, since the solvent-free addition-reaction-curable silicone is used, the peeling performance does not exceed the peeling performance of a conventional release film. In addition, the release film described in patent document 3 was light-released by aging the addition-reactive silicone to which no light-release component was added. In this case, a release film is obtained that does not lower the adhesive strength of the bonded adhesive layer compared to light peeling, but it is difficult to further reduce the peeling force.

In addition, the release film described in Patent Document 4 is obtained by laminating a silicone release layer containing inert particles having a predetermined particle diameter on a polyester film to a predetermined thickness. Blocking that occurs when the silicone release layer is thickened (when the release film is wound in a roll shape, the back surface of the release film and the release layer are similarly adhered, so that it is not well wound) is used to remove the inactive particles having a predetermined particle diameter from the silicone release layer. It was solved by adding to. However, since the silicone release layer is discontinuous due to the inert particles, when the solvent comes in contact, there is a fear that the solvent penetrates into the interface between the inert particles and the silicon, and the silicon may fall off. In addition, since inert particles having a larger particle diameter than the thickness of the silicone release layer are added, when a release film is used to protect the surface of the pressure-sensitive adhesive layer, when the inert particles adhere to the pressure-sensitive adhesive layer side, the adhesion strength of the pressure-sensitive adhesive layer is lowered. There is.

On the other hand, peeling electrification may occur when the release film is peeled from an adherend such as an adhesive layer. For this reason, at the processing site of the optical member, problems such as adhesion or contamination of foreign substances due to peeling charge, as well as problems caused by damage to the electronic elements excreted by static electricity disturbances, and product defects, etc. There was. For this reason, a release film having an antistatic function is required. Against this background, a release film in which an antistatic layer is formed on the surface of a base film and a silicone-based release agent layer is formed on the surface of the base film has been proposed. All of these proposals are both antistatic and releasable by forming an antistatic layer between the base film and the release agent layer, but in terms of peeling performance, there is no significant difference from the peeling performance of a conventional release film, and the prior art It is not a jump.

Japanese Patent Application Publication No. 2008-265227 Japanese Patent Application Publication 2012-136612 Japanese Patent Application Publication No. 2006-007689 Japanese Patent Application Publication No. 2013-208897 Japanese Patent Publication No. 2801436 Japanese Patent Application Publication No. 2005-153250 Japanese Patent Publication No. 2014-024204

In the present invention, since the peeling force is small and the peeling force is difficult to increase even when time elapses while being stuck to the pressure-sensitive adhesive layer, and the migration of the silicone component to the pressure-sensitive adhesive layer is small, peeling does not decrease the adhesive strength of the bonded pressure-sensitive adhesive layer. It is an object of the present invention to provide a release film with a low charge amount when it is a release film having excellent properties, and when the release film is handled and the release film is peeled from the adherend.

As a result of careful examination to solve such a problem, it is necessary that the silicone that releases the silicone-based release agent (sometimes referred to as a peeling agent) used in the release film to the surface of the pressure-sensitive adhesive layer in order not to lower the adhesive force of the pressure-sensitive adhesive layer. It turned out that there was In addition, it has been found that even when a silicone-based release agent having little silicone to migrate to the surface of the pressure-sensitive adhesive layer is used, the peeling force can be reduced by setting the thickness of the release agent layer to a specific thickness or more. However, when the thickness of the release agent layer is thickened, in the manufacturing process of the release film, the release film is wound up in a roll shape, and when the release agent layer is combined with the back side of the release film, blocking occurs to smoothly release the release film into a roll shape. There was a problem that it could not be wound up. In general, the base film used for the release film is formed by containing active particles in the base film to prevent blocking even when the base film is wound in a roll shape in the manufacturing process.

For this reason, since the surface of the base film has a concavo-convex structure by the lubricant particles, it is clear that when the base film single body is wound in a roll shape, the surfaces do not adhere to each other and do not cause blocking. Therefore, on the back surface of the release film, the surface of the base film has an uneven structure, but it is thought that the filling of the uneven structure on the surface of the base film with the release agent layer is the cause of the blocking.

In addition, it was possible to complete the present invention by further examining the method of achieving both the peelability and the blocking resistance. The release film according to the present invention has a total thickness of the two-layered release agent layer of 0.4 µm or more in order to reduce the peeling force even when a release agent having a small amount of silicone is transferred to the surface of the pressure-sensitive adhesive layer. In addition, the release film according to the present invention is formed by forming a concavo-convex shape having a suitable surface roughness on the outermost surface of the release agent layer of the two-layer structure to prevent blocking of the release layer of the two-layer structure and the back side of the release film, so that the release property and the blocking resistance are prevented. Making sex compatible is a technical idea. For this reason, as a means for forming an uneven shape suitable for a release agent layer, the release agent layer contains inorganic fine particles and / or polymer fine particles as fine particles. However, if the solvent is contacted by simply forming a release agent layer containing fine particles in the base film, the solvent may penetrate the interface between the release agent layer and the base film from the gap between the fine particles and the release agent, and the release agent layer may be peeled off the base film. There is. For this reason, the release film according to the present invention is solvent-resistant by forming a first release agent layer containing no fine particles between the substrate film and the second release agent layer containing fine particles so that the solvent does not penetrate to the interface between the release agent layer and the base film. And improves both the peelability and the blocking resistance.

On the other hand, for the method of imparting an antistatic function to the release film, it is sufficient to form an antistatic agent layer between the second release agent layer and the base film (surface of the base film) as described above. However, in this case, (1) the step of processing the antistatic agent layer on the base film, (2) the step of processing the first release agent layer containing no fine particles, and (3) the step of processing the second release agent layer containing fine particles. There is a problem that a three-step process is required and the production cost of the release film increases. As a result of intensive examination to solve this problem, the present invention was completed by finding that a release film having both excellent peeling performance and antistatic performance was obtained by containing an antistatic agent in the first release agent layer containing no particles. Ordered.

In the present invention, the first release agent layer containing an antistatic agent and containing no fine particles on at least one side of the base film and a second release agent layer containing fine particles composed of inorganic fine particles and / or polymer fine particles are stacked in this order. A release film having a release agent layer having a layer structure, wherein the total thickness of the first release agent layer and the second release agent layer is 0.4 to 2.0 µm, and the protrusion height from the surface of the second release agent layer to the apex of the fine particles is the Provided is a release film, wherein the first release agent layer and the second release agent layer contain a silicone-based release agent.

The second release agent layer is one or more inorganic fine particles and / or silicone resin, acrylic resin, polyamide resin, poly, selected from the group of inorganic particles consisting of silica, calcium carbonate, calcium phosphate, barium sulfate, kaolin, glass powder, and talc. It is preferable to contain one or more types of polymer fine particles selected from the group of polymer resin particles consisting of ester-based resin, polyethylene-based resin, polypropylene-based resin, polystyrene-based resin, and epoxy-based resin.

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

Further, a release film having a surface resistivity of 1.0 × 10 ¹³ Ω / □ or less on the outermost surface of the release layer of the two-layer structure is preferable.

In addition, the present invention comprises a laminate having at least one pressure-sensitive adhesive layer with at least one pressure-sensitive adhesive layer laminated on one side, and a release film according to any one of claims 1 to 4, and the surface of the pressure-sensitive adhesive layer of the laminate. It provides a laminated film formed by bonding the second release agent layer of the release film to.

ADVANTAGE OF THE INVENTION According to this invention, the release film for shaping | molding of a ceramic green sheet and the release film excellent in peelability for the optical member which has various adhesive layers can be provided. The release film of the present invention has a small peeling force, and it is difficult to increase the peeling force over time in a state of being bonded to the pressure-sensitive adhesive layer. Also, since the migration of the silicone component to the pressure-sensitive adhesive layer is small, the adhesive force of the bonded pressure-sensitive adhesive layer is improved. It is a release film excellent in peelability that does not deteriorate, and it is also possible to provide a release film with a small amount of charge when handling the release film and when the release film is peeled from the adherend.

1 is a cross-sectional view schematically showing an example of the release film of the present invention.
2 is a cross-sectional view schematically showing an example of the first aspect of the laminated film of the present invention.
3 is a cross-sectional view schematically showing a second embodiment of the laminated film of the present invention.
FIG. 4 is an enlarged view of part A in FIG. 1.

Hereinafter, preferred embodiments of the present invention will be described.

1 is a cross-sectional view schematically showing an example of the release film of the present invention. In Fig. 1, a first release agent layer 2 containing an antistatic agent and containing no fine particles on one side of the base film 1 and a fine particle 3 made of inorganic fine particles and / or polymer fine particles The two release agent layers 4 are stacked in this order to form two release agent layers.

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, but a polyester resin film, a polyamide resin film, a polyimide resin film, a polyolefin resin film, and polychloride And vinyl resin films, polystyrene resin films, acrylic resin films, acetate resin films, and polyphenylene sulfide resin films.

Among them, a polyester resin film is preferable in terms of characteristics such as optical properties, heat resistance properties, price, and appearance quality. Examples of the polyester resin include polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene isophthalate and polyethylene terephthalate, polybutylene terephthalate, and the like. Among these, polyethylene terephthalate (PET) is particularly preferred from the viewpoint of cost and optical properties. Further, from the viewpoint of optical properties, a polyethylene terephthalate film for optics that is uniaxially stretched or biaxially stretched is preferable.

In addition, if necessary, you may perform an adhesive treatment such as plasma discharge, surface modification by corona discharge, and application of an anchor coat agent to the surface of the base film 1.

The thickness of the base film 1 is not particularly limited, but assuming 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 10 to 200 The range of µm is preferable, and the range of 25 to 150 µm is more preferable.

In the release film of the present invention, the first release agent layer 2 containing an antistatic agent and containing no fine particles on at least one side of the base film, and a second containing fine particles 3 composed of inorganic fine particles and / or polymer fine particles The release agent layer 4 is stacked in this order to form two release agent layers.

The first release agent layer 2 has a function of adhering the base film 1 and the second release agent layer 4 containing the fine particles 3 to improve the solvent resistance of the release agent treatment surface of the release film, and as a release agent When the release film is peeled from the pressure-sensitive adhesive layer, which is an adherend, the film of the release agent layer is microscopically deformed as an elastomer due to stress at the time of peeling, so that stress is concentrated at the interface between the pressure-sensitive adhesive layer and the release agent layer.

In addition, the first release agent layer 2 imparts antistatic performance to the release film by containing an antistatic agent. It is preferable that the surface resistivity of the two-layered release agent layers 2 and 4 is 1.0 × 10 ¹³ Ω / □ or less (less than). Here, the surface resistivity of the two-layered release agent layers 2 and 4 is the surface resistivity (also referred to as the surface resistance value) measured with respect to the outermost surface of the two-layered release agent layers 2 and 4 laminated on the release film 5. Do).

As a release agent used for the 1st release agent layer 2, a silicone type release agent is mentioned. As the silicone type release agent, known silicone type release agents such as addition reaction type, condensation reaction type, cationic polymerization type, and radical polymerization type are mentioned. Commercially available products as addition-reactive silicone-based release agents include, for example, KS-776A, KS-776L, KS-847, KS-847T, KS-779H, KS-837, KS-778, KS-830, and 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 Industry 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, And LTC-1056L (manufactured by Toray Dow Corning Co., Ltd.), TPR-6722, TPR-6721, TPR-6702, TPR-6700, TPR-6600, and SL6625 (manufactured by Momentive Performance Materials). Examples of commercially available products as a condensation reaction type include SRX-290, SYLOFF-23 (manufactured by Toray Dow Corning Co., Ltd.), and YSR-3022 (manufactured by Momentive Performance Materials). Products commercially available as cationic polymerization types include, for example, TPR-6501, TPR-6502, TPR-6500, UV9300, UV9315, and UV9430 (manufactured by Momentive Performance Materials, Inc.), X62-7622, and X-62-7660. And X-62-7655 (manufactured by Shin-Etsu Chemical Industry Co., Ltd.). As a product marketed as a radical polymerization type, KF-2005, X62-7205 (made by Shin-Etsu Chemical Industry Co., Ltd.) etc. are mentioned, for example. As a mold release agent with little migration of the silicone component to the pressure-sensitive adhesive layer, a silicone-based mold release agent that does not contain a light peeling additive component (silicone having no organic functional groups involved in the addition reaction, for example, polydimethylsiloxane).

The silicone-based release agent for forming the first release agent layer 2 may be used alone or in combination of a plurality of varieties. In addition, components other than a silicone-based mold release agent such as a silane coupling agent or a wettability improving agent may be added together with the antistatic agent described later, and it may be determined in consideration of peelability, coatability, curability, and the like.

Moreover, it is preferable that the antistatic agent contained in the first release agent layer 2 has good dispersibility or solubility in the release agent solution, and does not inhibit curing of the release agent. Examples of the antistatic agent include one or two or more of ionic compounds, silicate-based compounds, conductive fillers, conductive whiskers, conductive polymers, and various surfactants. From the viewpoint of the solvent resistance of the release agent layer and the compatibility of the silicone release agent, an antistatic agent that does not dissolve in the silicone release agent to generate fine particles is preferable. Among them, an ionic compound, a silicate compound, a silicone surfactant, or an antistatic agent is used in combination. It is preferred.

As an ionic compound, it is an ionic compound having a cation and an anion, and an alkali metal cation, pyridinium cation, imidazolium cation, pyrimidinium cation, pyrazolium cation, pyrrolidinium cation as cation , Nitrogen-containing onium cation such as ammonium cation, phosphonium cation, sulfonium cation, and the like. The nitrogen-containing onium cation may have an organic group such as an alkyl group or a substituent. Preferably it is a quaternary nitrogen onium cation, quaternary pyridinium cations such as 1-alkylpyridinium (the carbon atoms at positions 2 to 6 may have a substituent or may be unsubstituted) or 1,3 -Quaternary imidazolium cations such as dialkylimidazolium (carbon atoms at positions 2, 4, and 5 may have substituents or unsubstituted), N-alkylpyrimidinium (positions 2 and 4 to The carbon atom at the 6-position may have a substituent, or may be unsubstituted) quaternary pyrimidinium cation, 1,2-dialkylpyrazolium (the carbon atom at the 3 to 5-position may have a substituent, Quaternary pyrrolidiniums such as quaternary pyrazolium cations such as unsubstituted) and 1,1-dialkylpyrrolidinium (carbon atoms at positions 2 to 5 may have substituents or unsubstituted). And quaternary ammonium cations such as cation and tetraalkylammonium. Examples of the phosphonium cation include phosphonium cation having an organic group such as tetraalkylphosphonium. Examples of the sulfonium cation include sulfonium cation having an organic group such as trialkylsulfonium.

In addition, the C _n H _{2n + 1} COO as an anion ^{_{-, C n F 2n + 1}} COO -, NO 3 -, C n F 2n + 1 SO 3 -, (C n F 2n + 1 SO 2) 2 N -, (C n F 2n + 1 SO 2 ^{_{) 3 C -, RC 6 H}} 4 SO 3 -, PO 4 3-, AlCl 4 -, Al 2 Cl 7 -, ClO 4 -, BF 4 -, PF 6 -, AsF 6 -, SbF 6 -, SCN - And the like. These ionic compounds may be used alone, or may be used by mixing two or more kinds. For stabilization of the ionic substance, a compound containing a polyoxyalkylene structure may be added.

Especially, an ionic compound (alkali metal salt) which has an alkali metal cation as a cation is preferable. Alkali metal salts may include metal salts formed by lithium, sodium, potassium, specifically, for example, Li ^+, Na ^+, a cation consisting of K ^{+ and, Cl -, Br -, I} -, BF 4 - _{^{, PF 6 -, SCN -,}} ClO 4 -, CF 3 SO 3 -, (FSO 2) 2 N -, (CF 3 SO 2) 2 N -, (C 2 F 5 SO 2) 2 N -, (CF A metal salt composed of anions consisting of ₃ SO ₂ ) ₃ C ^- is preferably used. Among them, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (FSO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) Lithium salts such as ₂ N and Li (CF ₃ SO ₂ ) ₃ C are preferably used. These alkali metal salts may be used alone or in combination of two or more. For stabilization of the ionic substance, a compound containing a polyoxyalkylene structure may be added.

Examples of the silicate-based compound include ethyl silicate, various alkoxysilanes, oligomers (alkoxysiloxanes), and partial hydrolyzates and polycondensation reactants. The silicate-based compound used at the time of coating may be a solution (composition) containing a catalyst such as acid or a solvent such as alcohol. The hydrolysis reaction or polycondensation reaction of the silicate-based compound may proceed after application of the release agent. Silicate-based antistatic agents are preferred because even when the reaction proceeds, a release agent layer having excellent solvent resistance is obtained.

Examples of the conductive filler include carbon-based fillers such as carbon black and graphite, metal fine powders such as silver, copper, and nickel, and metal oxide particles such as zinc oxide and tin oxide.

Examples of the conductive whiskers include graphite whiskers, potassium titanate whiskers, alumina-based whiskers, silicon carbide whiskers, silicon nitride whiskers, magnesium bromide whiskers, zinc oxide whiskers, and titanium bromide whiskers.

Examples of the conductive polymer include polythiophene, polyaniline, and polypyrrole.

Examples of the surfactant include nonionic, cationic, anionic and amphoteric systems. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene fatty acid esters, glycerin fatty acid esters, propylene Glycol fatty acid esters, polyoxyalkylene-modified silicones, and the like. Examples of the cationic surfactant include alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkylbenzyldimethylammonium salts. Examples of the anionic surfactant include monoalkyl sulfates, alkyl polyoxyethylene sulfates, alkylbenzene sulfonates, and monoalkyl phosphates. Examples of the amphoteric surfactant include alkyl dimethylamine oxide and alkyl carboxybetaine.

The amount of the antistatic agent added to the mold release agent varies depending on the type of the antistatic agent or the degree of affinity of the mold release agent, and may be set in consideration of the antistatic performance and the curability and peelability of the mold release agent. Moreover, you may use together antistatic agents of different types.

There are no particular limitations on the method of mixing the mold release agent and the antistatic agent. Method of adding and mixing a catalyst for curing the release agent after adding an antistatic agent to the release agent and mixing, method of adding and mixing an antistatic agent and a catalyst for curing the release agent before diluting the release agent with an organic solvent, and mixing the release agent with an organic solvent in advance After dilution, any method such as a method of adding and mixing a catalyst and then adding and mixing an antistatic agent may be used. Moreover, you may add the adhesion improver, such as a silane coupling agent as needed.

In the release film according to the present invention, the formation of the first release agent layer 2 containing the antistatic agent and not the fine particles may be formed by coating the base film 1 with a release agent containing the antistatic agent. The coating method is not particularly limited, and may be selected from known coating methods in accordance with the viscosity and application amount of the release agent forming the first release agent layer 2 containing no 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. As the curing method of the first release agent layer 2, methods such as heat curing, ultraviolet curing, electron beam curing, and combination of heating and ultraviolet irradiation may be mentioned, but a preferred method may be selected and employed according to the type of the release agent. The thickness of the first release agent layer 2 is not particularly limited, but is preferably 0.1 μm or more in order to sufficiently secure solvent resistance.

As shown in Fig. 4, the thickness h1 [µm] of the first release agent layer 2 containing no fine particles and the thickness h2 [µm] of the second release agent layer 4 containing the fine particles 3 (fine particles ( 3) It is preferable that the total thickness H [µm] (hereinafter referred to as the total thickness of the two layers of release agent layers 2 and 4) summed up within the range of 0.4 to 2.0 µm, which is the sum of the average thickness of the portion without) , 0.5 to 1.8 µm is more preferable.

In the present invention, the first release agent layer 2 containing an antistatic agent and containing no fine particles on at least one side of the base film, and a second release agent layer containing fine particles 3 composed of inorganic fine particles and / or polymer fine particles ( 4) are stacked in this order to form a two-layer release agent layer. Even if the thickness of the second mold release agent layer 4 containing the silicone type mold release agent is thick, the fine particle 3 made of inorganic fine particles and / or polymer is the back side of the release film 5 (base film ( It is used to form a concavo-convex shape on the surface of the second release agent layer 4 so as not to cause blocking when combined with the surface of 1).

Examples of the inorganic fine particles and / or polymer fine particles as the anti-blocking fine particles 3 include inorganic fine particles as the inorganic compound fine particles and polymer fine particles as the polymer resin fine particles. The inorganic fine particles and the polymer fine particles may be used either, or both of them may be used in combination. It is preferable that 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, and talc. Further, it is preferable that the polymer fine particles are at least one selected from the group of polymer resin particles consisting of silicone resin, acrylic resin, polyamide resin, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, and epoxy resin. Do.

The shape of the fine particles 3 is not particularly limited, and may be any of a spherical shape, a rod shape, a scale shape, a hemispherical shape, a convex lens shape, a mushroom shape, an irregular shape, etc., but a spherical shape or a shape close to a spherical shape is prevented from blocking. It is more preferable because the performance is increased.

4, the volume-based average particle diameter of the fine particles 3 is preferably larger than the thickness h2 [µm] of the second release agent layer 4, and fine particles from the surface of the second release agent layer 4 The height T (μm) to the apex of (3) (protrusion height of the fine particles 3) is the thickness h1 [μm] of the first release agent layer 2 and the thickness h2 [μm] of the second release agent layer 4 It is sufficient to select fine particles having a volume-based average particle diameter equal to or greater than the total thickness H [µm]. The apex of the fine particles 3 may be any point that is the most distant from the surface of the second release agent layer 4, and it does not matter whether the apex protrudes or has a round shape.

As a release agent for forming the second release agent layer 4 which also functions as a binder resin for the fine particles 3 composed of inorganic fine particles and / or polymer fine particles, a silicone-based release agent is mentioned. As a silicone type release agent, well-known silicone type release agents, such as addition reaction type, condensation reaction type, cationic polymerization type, and radical polymerization type, are mentioned.

The silicone-based mold release agent may be used alone or in combination of multiple varieties. Moreover, components other than a silicone type release agent, such as a silane coupling agent, an antistatic agent, and a wettability improving agent, may be added, and it may be determined in consideration of peelability, coatability, curability, and the like. The silicone-based release agent forming the second release agent layer 4 may be the same silicone-based release agent as the release agent forming the first release agent layer 2, or may be different.

The fine particles 3 are mixed with a release agent containing a silicone-based release agent forming the second release agent layer 4 and applied over the first release agent layer 2. As shown in Fig. 4, a part (upper part) of the fine particles 3 protrudes from the thickness h2 [µm] of the second release agent layer 4 (the average thickness of the part without the fine particles 3). The release agent of the second release agent layer 4 may be thinly attached to the upper surface of the fine particles 3 or may not be attached. The lower part of the fine particles 3 is filled in the second release agent layer 4 but is not in contact with the base film 1. This is because the first release agent layer 2 containing no fine particles is interposed.

The method for mixing and dispersing the fine particles 3 in the release agent may be carried out by a known method in accordance with the type of the release agent and fine particles. If it is a system in which fine particles are easily dispersed in the mold release agent, it may be stirred and mixed by a manual mechanism such as a spatula. Even if the particles are difficult to disperse in a combination in which the fine particles are difficult to disperse or if they are easily dispersed, the release agent and fine particles may be dispersed and mixed using a disperser such as a homogenizer or a homo mixer. In addition, a colorant, an antistatic agent, a leveling agent, an adhesion improving agent, etc. may be added to the second release agent layer 4 in addition to the fine particles and the release agent.

In the release film according to the present invention, the second release agent layer 4 does not need to contain an antistatic agent. This is because the total thickness of the two-layer release agent layers 2 and 4 is thin in the range of, for example, 0.4 to 2.0 µm, so that the first release agent layer 2 has antistatic performance, the 2 of the release film 5 This is because it is possible to impart antistatic performance to the outermost surfaces of the layer-releasing agent layers 2 and 4. In addition, when an antistatic agent is added to the 2nd release agent layer 4, the antistatic agent similar to that added to the 1st release agent layer 2 is mentioned as the antistatic agent. In addition, when the second release agent layer 4 is laminated on the first release agent layer 2, or after lamination, a part of the antistatic agent contained in the first release agent layer 2 is introduced into the second release agent layer 4. It may be implemented.

The method of forming the second release agent layer 4 containing the fine particles 3 may be formed by coating the release agent containing the fine particles 3 on the first release agent layer 2 formed on the base film 1. The coating method is not particularly limited, and may be selected from known coating methods in accordance with the viscosity and coating amount of the release agent 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 second release agent layer 4 containing the fine particles 3 may be cured or solidified according to the type of release agent. For example, the solvent or water may be removed by heating and drying, or the release agent layer may be cured by ultraviolet irradiation or electron beam irradiation.

Although the thickness of the second release agent layer 4 is not particularly limited, in order to sufficiently secure the function of the fine particles 3 composed of inorganic fine particles and / or polymer fine particles as a binder resin, the average particle diameter based on the volume of the fine particles 3 is 25 % Or more. The average particle diameter based on the volume of the fine particles 3 and the total thickness of the two release layers 2 and 4 (range of 0.4 to 2.0 µm) may be considered and set. When the total thickness of the two-layer release agent layers 2 and 4 is less than 0.4 µm, the peeling force tends to increase. In addition, although the upper limit of the total thickness of the two layers of the release agent layers 2 and 4 is not particularly a problem, when the total thickness of the two layers of the release agent layers 2 and 4 is increased, the cost increases or the fine particles (3 By increasing the average particle diameter based on), there is a problem that the appearance of the release film becomes white. For this reason, it is preferable to suppress the total thickness of the two layers of release agent layers 2 and 4 to 2.0 µm or less, and more preferably 1.8 µm or less.

When the release film 5 of the present invention is used for a release sheet for molding a green sheet used in manufacturing electronic components made of various ceramics, the green sheet is formed by applying and drying a slurry in which ceramic particles are dispersed with an organic solvent. do. The release film 5 used for the purpose of protecting such a green sheet requires solvent resistance to the second release agent layer 4. The release film 5 of the present invention forms the first release agent layer 2 containing no fine particles between the base film 1 and the second release agent layer 4 containing the fine particles 3. For this reason, even if the solvent penetrates the interface between the second release agent layer 4 and the first release agent layer 2 from the gap between the release agent of the second release agent layer 4 and the fine particles 3, the first release agent layer 2 Since the solvent does not reach the interface between the and the base film 1, the first release agent layer 2 does not peel off from the base film 1, has good solvent resistance, and is preferably used for the purpose of protecting the green sheet. You can. Further, the release film 5 of the present invention is not limited to a green sheet, and can be preferably used for the purpose of protecting the surface of a coating film containing a coating film or a solvent in which various powders are dispersed, such as a conductor paste and an insulator paste.

2 is a cross-sectional view schematically showing an example of the first aspect of the laminated film of the present invention. The tackifying optical film 8 in FIG. 2 is used to protect the pressure-sensitive adhesive layer 6 laminated on the optical film 7 with the release film 5 of the present invention. The optical film 7 is pasted to the release film 5 of the present invention in FIG. 1 via the pressure-sensitive adhesive layer 6. The manufacturing method of such a tackifying optical film 8 may apply a solvent-type adhesive to the release film 5, dry it, and may attach the optical film 7 together. In the release film 5 used for the purpose of protecting the pressure-sensitive adhesive layer 6, solvent resistance is required for the release agent layers 2 and 4. The release film 5 of the present invention forms the first release agent layer 2 containing no fine particles between the base film 1 and the second release agent layer 4 containing the fine particles 3. For this reason, even if the solvent penetrates the interface between the second release agent layer 4 and the first release agent layer 2 from the gap between the release agent of the second release agent layer 4 and the fine particles 3, the first release agent layer 2 Since the solvent does not reach the interface between the and the base film 1, the first release agent layer 2 does not peel off from the base film 1, and the solvent resistance is also good. The laminate comprising the pressure-sensitive adhesive layer 6 may include 1 or 2 or more resin films and 1 or 2 or more pressure-sensitive adhesive layers. For example, the pressure-sensitive adhesive layer 6 may be formed on both sides of the optical film 7, and the release film 5 of the present invention may be pasted on each pressure-sensitive adhesive layer 6. As another manufacturing method, the release film 5 of the present invention may be pasted on the laminate 10 in which the pressure-sensitive adhesive layer 6 is formed on one side of the optical film 7. Alternatively, after applying the solvent-free pressure-sensitive adhesive, the pressure-sensitive adhesive layer 6 may be cured between the release film 5 and the optical film 7 by light or heat. In use, the release film 5 is peeled from the tackifying optical film 8 to separate the laminate 10 from the release film 5 to expose the surface (adhesive surface) of the pressure-sensitive adhesive layer 6. In general, the adhesion between the optical film 7 and the pressure-sensitive adhesive layer 6 is greater than that of peeling the release film 5 from the pressure-sensitive adhesive layer 6.

3 is a cross-sectional view schematically showing a second embodiment of the laminated film of the present invention. The optical pressure-sensitive adhesive sheet 9 of FIG. 3 is obtained by bonding the release film 5 of the present invention to the pressure-sensitive adhesive layer 6 used for bonding the touch panel member or the optical member to protect the pressure-sensitive adhesive layer 6. . The optical pressure-sensitive adhesive sheet 9 is in the form of sandwiching the pressure-sensitive adhesive layer 6 with two release films 5. In the manufacturing method of the optical pressure-sensitive adhesive sheet 9, it is common to apply the solvent-type pressure-sensitive adhesive to one release film 5 and dry it, and then bond the other release film 5 to each other. In the release film 5 used for the purpose of protecting the pressure-sensitive adhesive layer 6, solvent resistance is required for the release agent layers 2 and 4. Since the release film 5 of the present invention also has good solvent resistance, it can be preferably used for the purpose of protecting the pressure-sensitive adhesive layer 6.

The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer 6 of the laminated film of the present invention may be water-based or non-aqueous (solvent-based), or may be of a non-solvent type. As the pressure-sensitive adhesive, any of acrylic pressure-sensitive adhesive, silicone pressure-sensitive adhesive, rubber pressure-sensitive adhesive, and urethane-based pressure-sensitive adhesive may be used. Acrylic pressure-sensitive adhesives are preferred because of their excellent 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 anti-glare (anti-glare) film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensating film, a brightness enhancing film, and a high transparency film.

The laminated film of the present invention is a laminated film in which the release agent layer of the release film is affixed to the surface (adhesive surface) of the pressure-sensitive adhesive layer, and as shown in FIG. 3, the laminated film consisting only of the release film 5 and the pressure-sensitive adhesive layer 6 As shown in FIG. 2, a laminated film including a resin film (support of the adhesive layer 6) such as the optical film 7 may be used.

Example

Hereinafter, the present invention will be described in detail through examples.

(Release film of Example 1)

Addition reaction type silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-345) 5 parts by weight, lithium bis (fluorosulfonyl) imide 0.75 parts by weight, 1: 1 mixed solvent of toluene and ethyl acetate 95 parts by weight Part, platinum catalyst (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-212) 0.05 parts by weight of agitation and mixing to form a first release agent layer (hereinafter referred to as release agent layer A) of Example 1 Was adjusted.

The paint forming the release agent layer A of Example 1 was coated on the surface of a polyethylene terephthalate film having a thickness of 38 μm with a Meyer bar so that the thickness after drying became 0.1 μm, followed by heating in a hot air circulation oven at 120 ° C. for 1 minute. A release agent layer A was formed.

Subsequently, 30 parts by weight of an addition-reactive silicone (LTC-1056L manufactured by Toray Dow Corning Co., Ltd.) on the surface of the release agent layer A, 70 parts by weight of a 1: 1 mixed solvent of toluene and ethyl acetate, and a platinum catalyst (Toray Dow Corning Co., Ltd. product name: SRX-212) 1 part by weight, and an average particle diameter (volume-based average particle diameter) of 2 µm silicone resin polymer fine particles (Momentive Performance Materials, Inc., product name: Toss Pearl (Registered trademark) 120) The coating material for forming the second release agent layer of Example 1 (hereinafter referred to as release agent layer B) was adjusted by mixing 0.0166 parts by weight.

The coating material forming the release agent layer B of Example 1 was coated on the surface of the release agent layer A with a Meyer bar so that the thickness after drying of the release agent layer B (additional reaction type silicone-based release agent excluding the protruding height of the fine particles) was 0.9 µm, 120 The release film of Example 1 was obtained by forming the release agent layer B by heating in a hot-air circulating dryer at ℃ for 1 minute.

(Release film of Example 2)

As an antistatic agent contained in the release agent layer A, instead of 0.75 parts by weight of lithium bis (fluorosulfonyl) imide, 20 parts by weight of an ethyl silicate-based antistatic agent (Colcoat (registered trademark) N-103X manufactured by Colcoat Co., Ltd.) The release film of Example 2 was obtained in the same manner as in Example 1 except that 75 parts by weight of a 1: 1 mixed solvent of toluene and ethyl acetate was used as a part.

(Release film of Example 3)

The thickness after drying of the release agent layer A was 0.3 µm, and the thickness after drying of the release agent layer B was 0.7 µm, and silicone-based resin polymer fine particles (manufactured by Momentive Performance Materials, product name: Toss Pearl (registered trademark) 120) Instead, the release film of Example 3 was prepared in the same manner as in Example 2, except that amorphous silica having a volume-based average particle diameter of 2.7 µm (manufactured by Fuji Silicia Chemical Co., Ltd., product name: Silicia (registered trademark) 310P) was used. Got.

(Release film of Example 4)

The release film of Example 4 was obtained in the same manner as in Example 2, except that the thickness after drying of the release agent layer B was 0.4 µm.

(Release film of Example 5)

The thickness after drying of the release agent layer A was 0.3 µm, and the thickness after drying of the release agent layer B was 1.7 µm, and silicone-based resin polymer fine particles (manufactured by Momentive Performance Materials, product name: Toss Pearl (registered trademark) 120) Instead, Example 5 was performed in the same manner as in Example 2, except that the silicon-based resin polymer fine particles having a volume-based average particle diameter of 4.5 µm (manufactured by Momentive Performance Materials, product name: Tos Pearl (registered trademark) 145) were used. A release film was obtained.

(Comparative Example 1)

A release film of Comparative Example 1 was produced in the same manner as in Example 1 except that the release agent layer A was not formed.

(Comparative Example 2)

The release film of Comparative Example 2 was obtained in the same manner as in Example 1, except that the thickness after drying of the release agent layer B was 1.2 µm.

(Comparative Example 3)

The thickness after drying only the solution of the addition-reactive silicone-based release agent and platinum catalyst from which the fine particles were removed from the paint forming the release agent layer B of Example 1 on the corona-treated surface of the polyester film subjected to corona treatment on one side having a thickness of 38 µm was 0.2. After coating with a Meyer bar to be µm, a release film of Comparative Example 3 was obtained by heating in a hot air circulation dryer at 120 ° C. for 1 minute.

(Comparative Example 4)

A release film of Comparative Example 4 was obtained in the same manner as in Example 1 except that the release agent layer A did not contain lithium bis (fluorosulfonyl) imide as an antistatic agent.

(Measurement of surface resistivity of release agent layer)

The surface resistivity (Ω / □) of the outermost surface of the release layer of the two-layer structure of the sample for measurement of the release film is applied using a high-performance high-resistance meter (High-Rester (registered trademark) -UP manufactured by Mitsubishi Chemical Analytics). It measured under the conditions of voltage 100V and measurement time 30 second.

(Confirmation of blocking)

A sample in which three release films are overlapped is prepared, and sandwiched between two sheets of stainless steel plate (SUS304). The sample was allowed to stand for 24 hours in an environment of 23 ° C., 50% RH with a load of 20 g / cm 2 {0.196 N / cm 2} applied. Subsequently, a release state was checked by taking out three overlapping release films and peeling the release films one by one by hand.

As a criterion for determining the blocking state, those with no blocking, and the release film was lightly peeled were considered to have good blocking properties (○) and those having resistance at the time of peeling of the release film were regarded as poor blocking properties (×).

(Measurement of peeling force)

A polyester adhesive tape (manufactured by Nitto Electric Corporation, trade name: Polyester Tape No. 31B) was bonded to the outermost surface of the release layer of the two-layer structure of the release film, and aged at 70 ° C for 20 hours under a load of 20 g / cm 2. Then, the peel strength at the time of peeling at a peeling speed of 300 mm / min and a peeling angle of 180 ° was measured as a peeling force (mN / 50 mm) using a tabletop precision universal testing machine (manufactured by Shimadzu Corporation, Autograph (registered trademark)). Did.

(Measurement of residual adhesion rate)

The pressure-sensitive adhesive tape peeled from the release film after the test by the above (measurement of peeling force) was pressed against a adherend (stainless steel plate) with a roller and left under an environment of 23 ° C and 55% RH for 1 hour, and then used as a tabletop precision universal A peeling force when peeling from the adherend at a peeling speed of 300 mm / min and a peeling angle of 180 ° was measured with a tester (manufactured by Shimadzu Corporation, Autograph (registered trademark)) to determine the residual adhesive strength.

Separately from this, an unused adhesive tape was pressed against an adherend of the same material, and the peeling force when peeling was measured in the same manner as the residual adhesive force, and used as a reference adhesive force.

Residual adhesion ratio was calculated by the formula such as residual adhesion ratio = (residual adhesion) / (reference adhesion) x 100 (%).

(Check the adhesion of the release agent layer)

The outermost surface of the release agent layer having the two-layer structure of the release film after the test by (measurement of peeling force) was rubbed strongly three times with fingertips, and the rubbed portion was visually observed. It was visually confirmed whether or not the release agent layer was removed from the base film, and it was evaluated as (○) that the release agent layer was hardly eliminated and (x) that the release agent layer was remarkable.

(Checking the solvent resistance of the release agent layer)

Using a nonwoven fabric (Bencoat (registered trademark) M-1, manufactured by Asahi Kasei Co., Ltd.) impregnated with ethyl acetate on the outermost surface of the release layer of the two-layer structure of the release film, one round friction was applied with a weight of 200 g. Order. Then, the outermost surface of the release agent layer of the two-layer structure of the release film was visually observed to confirm the solvent resistance of the release agent layer of the two-layer structure of the release film. The outermost surface of the release layer of the two-layer structure was visually observed to determine that there was no change in appearance (○), and that the release agent layer of the two-layer structure was eliminated (×).

(Evaluation results)

Table 1 shows the evaluation results of the release films of Examples 1 to 5 and the release films of Comparative Examples 1 to 4. In Table 1, the meaning of "overrange" means that the measurement range of the surface resistance meter (high-star -UP) was exceeded, that is, the surface resistivity of the outermost surface of the two-layered release agent layer was 1.0 × 10 ¹³ Ω. ／ □ means more than that. In addition, the surface resistivity was expressed by the index expression prescribed | regulated to JISX0210. For example, 3.2E + 11 means 3.2 x 10 11th power.

(theorem)

The release films of Examples 1 to 5 according to the present invention exhibited a low peeling force and a high residual adhesiveness. In addition, the surface resistivity of the outermost surface of the release agent layer having a two-layer structure became a low value. In addition, in the release test of Examples 1 to 5, in the test for the presence or absence of blocking, the second release agent layer and the back surface of the release film did not generate blocking, and the adhesion and solvent resistance of the second release agent layer containing fine particles were good. Did.

On the other hand, since the release film of Comparative Example 1 did not form the first release agent layer containing the antistatic agent and not containing the fine particles, the second release agent layer containing the fine particles became a structure in contact with the base film, resulting in solvent resistance. It was bad, and the antistatic performance was inferior.

In addition, the release film of Comparative Example 2 had a result that the unevenness of the second release agent layer containing fine particles was small, and the release film caused blocking, resulting in a large peeling force.

In addition, the release film of Comparative Example 3 was coated with only a silicone-based release agent layer containing no antistatic agent and fine particles at a general application amount, so that the release agent layer was formed, and thus the peeling force was remarkably higher than that of the release films of Examples 1 to 5 according to the present invention. It was large, and the antistatic performance was inferior.

In addition, since the release film of Comparative Example 4 did not contain an antistatic agent in the first release agent layer and the second release agent layer, the surface resistivity of the outermost surface of the release agent layer of the two-layer configuration was overrange (1.0 × 10 ¹³ Ω / □ or higher), which resulted in poor antistatic performance.

One… Base film, 2 ... First release agent layer, 3 ... Particulate, 4… 2nd release agent layer, 5 ... Release film, 6 ... Adhesive layer, 7 ... Optical film, 8 ... Tackifying optical film, 9 ... Optical adhesive sheet, 10… Laminate

Claims (2)

A laminated film comprising a release film for surface protection, on which a release agent layer is formed, on a surface of the pressure-sensitive adhesive layer of a laminate in which a pressure-sensitive adhesive layer is laminated on one side of a base material, bonded via the release agent layer,
A release film for surface protection obtained by peeling the laminate from the laminated film is used for surface protection of the adherend,
The release film for surface protection includes a first release agent layer containing an antistatic agent and containing no fine particles on at least one side of the base film, and a second release agent layer containing fine particles composed of inorganic fine particles and / or polymer fine particles. It consists of a two-layered release agent layer laminated in order,
The total thickness of the first release agent layer and the second release agent layer is 0.5 to 2.0 μm, and the projecting height from the surface of the second release agent layer to the apex of the fine particles is greater than or equal to the total thickness, and the first release agent is also used. A layered film comprising a layer and the second release agent layer containing a silicone-based release agent that does not contain polydimethylsiloxane. According to claim 1,
One or more inorganic fine particles and / or silicone-based resins, acrylic resins, polyamides selected from the group of inorganic particles in which the fine particles contained in the second release agent layer are composed of silica, calcium carbonate, calcium phosphate, barium sulfate, kaolin, glass powder, and talc. A laminated film, characterized in that it is at least one polymer fine particle selected from the group of polymer resin particles comprising a resin based resin, a polyester based resin, a polyethylene based resin, a polypropylene based resin, a polystyrene based resin, and an epoxy based resin.

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