Adhesive film for protecting photomask

Abstract

The purpose of the present invention is to provide an adhesive film for protecting a photomask, the adhesive film having good releasability from a photosensitive resin, being not likely to be scratched even when the surface of a release layer is rubbed with a spatula, a nail, or the like, thereby having excellent scratch resistance, and being free from defects due to migration of a silicone component into the photosensitive resin. Provided is an adhesive film for protecting a photomask, the adhesive film being obtained by providing an adhesive layer on one surface of a transparent base material film and providing a release layer on the other surface. The release layer is a cured product of a release layer composition that is composed of a resin having a ladder type polysilsesquioxane structure and a polyisocyanate.

Description

Adhesive film for protecting photomasks

[0001] The present invention relates to an adhesive film for protecting a photomask, which is used in close contact with an adhesive photosensitive resin in the manufacturing process of printed circuit boards or resin relief plates, etc.

[0002] Typically, printed circuit boards and resin relief plates are manufactured by closely exposing a photomask (exposure original) to an adhesive photosensitive resin, such as a liquid photosensitive resin. Therefore, a surface protection film with release properties has been conventionally provided on the side of the photomask facing the photosensitive resin to prevent the resin from adhering to the photomask. This surface protection film of the photomask has an adhesive layer on one side of a base film and a release layer on the other side to prevent the photosensitive resin from adhering. The release layer of such a surface protection film is generally composed of a mixture of resin and a silicone-based release agent, or a silicone-based resin.

[0003] However, such release layers contain low-molecular-weight silicone components, which migrate to the photosensitive resin surface, causing problems by repelling surface treatment agents and printing inks in subsequent processes. Therefore, additional steps are required to remove the migrated silicone components.

[0004] Patent Document 1 discloses a surface protection film that suppresses the migration of a mold release agent to a photosensitive resin by containing a specific graft polymer as a mold release agent. However, the mold release layer surface of the surface protection film is periodically wiped clean with a solvent to remove the photosensitive resin and foreign matter. The surface protection film of Patent Document 1 suffers from reduced mold release properties to the photosensitive resin after this wiping and cleaning, and its solvent resistance was not satisfactory for use as a surface protection film for photomasks.

[0005] Patent Document 2 discloses a surface protective film with improved solvent resistance, having a structure in which a base film is laminated in sequence with an undercoat layer containing a saturated copolymer polyester resin and fine particles, and a photosensitive resin adhesion prevention layer (release layer) made of a cured product of an addition reaction type silicone composition.

[0006] Japanese Patent Publication No. 11-7121, Japanese Patent Publication No. 2000-273412

[0007] Generally, when applying a surface protective film to a photomask, the process is carried out in a clean environment to prevent foreign matter such as dust from being trapped. However, it is not possible to completely prevent foreign matter from being trapped. If foreign matter is trapped between the photomask and the surface protective film, exposure failures will occur due to the foreign matter and the air bubbles around it. In such cases, it becomes necessary to reapply the surface protective film to remove the foreign matter. However, in the case of photomasks for resin relief printing, the surface area of ​​the surface protective film to be applied is large, so if the trapped foreign matter is minute, instead of reapplying the film, the air bubbles around the foreign matter may be removed by rubbing the surface of the release layer of the surface protective film with a spatula or fingernail. In this case, if the scratch resistance of the release layer is insufficient, scratches may occur on the surface of the release layer, and these scratches will result in exposure failures, leading to a decrease in the resolution or defects of the pattern shape formed on the photosensitive resin.

[0008] The surface protection film in Patent Document 2 suppressed the decrease in release properties after wiping and cleaning with a solvent, but the surface of the release layer could be scratched by rubbing it with a spatula or fingernail, indicating that the scratch resistance of the release layer was insufficient.

[0009] In particular, when used for manufacturing resin relief plates for liquid crystal alignment film printing, where high-definition thin-film printing is required, problems such as exposure failures due to very minor scratches and ink repellency during alignment film printing due to the migration of trace amounts of silicone components could not be completely eliminated.

[0010] The present invention has been made in view of the above circumstances, and aims to provide an adhesive film for protecting photomasks that has good release properties from photosensitive resin, is resistant to scratches even when the surface of the release layer is rubbed with a spatula or fingernail, has excellent scratch resistance, and suppresses problems caused by the migration of silicone components to the photosensitive resin.

[0011] The first invention is an adhesive film for protecting a photomask, comprising a transparent substrate film with an adhesive layer on one side and a release layer on the other side, characterized in that the release layer is a cured product of a release layer composition containing a resin having a ladder-type polysilsesquioxane structure and a polyisocyanate.

[0012] The second invention is an adhesive film for protecting a photomask according to the first invention, characterized in that the hydroxyl value of the resin having the ladder-type polysilsesquioxane structure is 109 to 132 mgKOH / g.

[0013] The third invention is an adhesive film for protecting a photomask according to the first or second invention, characterized in that the coating thickness of the release layer is 0.4 to 0.8 μm.

[0014] The fourth invention is a photomask protective adhesive film according to any one of the first to third inventions, characterized in that the photomask protective adhesive film is for use in photomasks used in the manufacture of resin relief plates for orientation film printing.

[0015] In the present invention, in an adhesive film for protecting a photomask, an adhesive layer is provided on one side of a transparent substrate film, and a release layer is provided on the other side. By making the release layer a cured product of a release layer composition consisting of a resin having a ladder-type polysilsesquioxane structure and polyisocyanate, the migration of silicone components to the photosensitive resin is suppressed, resulting in good release properties from the photosensitive resin and excellent scratch resistance of the release layer.

[0016] This is a schematic cross-sectional view showing one embodiment of the adhesive film for protecting photomasks of the present invention. This is a schematic side view showing the installation of an evaluation sample on a planar abrasion tester in the scratch resistance evaluation of the present invention. This is a schematic view showing the width and thickness directions of the abrasion indenter in the scratch resistance evaluation of the present invention.

[0017] Embodiments of the present invention will be described below.

[0018] Figure 1 shows a schematic cross-sectional view of an embodiment of the adhesive film for protecting photomasks according to the present invention. The adhesive film for protecting photomasks 10 shown in Figure 1 has a release layer 11 provided on one side of a base film 12, an adhesive layer 13 provided on the other side, and a separator film 14 laminated on the adhesive layer 13. The adhesive film for protecting photomasks 10 according to the present invention may have one or more layers selected from anchor layers, antistatic layers, etc., provided between the base film 12 and the release layer 11, and / or between the base film 12 and the adhesive layer 13. When the adhesive film for protecting photomasks 10 is used, the separator film 14 is peeled off, and it becomes in the form of release layer 11 / base film 12 / adhesive layer 13.

[0019] <Base Film> The transparent base film used in the present invention is preferably one with a high transmittance of ultraviolet light used during exposure, and examples of plastic films include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polystyrene, triacetylcellulose, acrylic resin, and polyvinyl chloride. Among these, polyethylene terephthalate film is preferred in terms of its excellent mechanical strength and dimensional stability, and biaxially oriented polyethylene terephthalate film is more preferred.

[0020] The base film may be surface-treated. Examples of surface treatments include corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, and primer treatment.

[0021] From the viewpoint of handling and other factors, the thickness of the base film is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and even more preferably 5 μm or more. From the viewpoint of light transmittance, it is preferably 50 μm or less, more preferably 25 μm or less, even more preferably 12 μm or less, and even more preferably 8 μm or less. Specific ranges for the thickness of the base film include preferably 2 to 50 μm, more preferably 3 to 25 μm, even more preferably 4 to 12 μm, and even more preferably 5 to 8 μm.

[0022] <Release Layer> The release layer of the present invention is composed of a cured product of a release layer composition containing a resin having a ladder-type polysilsesquioxane structure and a polyisocyanate. By using a release layer with this configuration, an adhesive film for protecting photomasks can be obtained that has excellent release properties, scratch resistance, and suppresses the migration of silicone components to the photosensitive resin.

[0023] Polysilsesquioxane is a dehydration condensation polymer of a hydrolyzed silane compound (RSi(OH)3: R is an organic group) having three hydrolyzable functional groups. Polysilsesquioxane exists in various forms, such as cage-type, ladder-type, and random-type. Ladder-type polysilsesquioxane, due to its regular structure, has excellent hardness and heat resistance, as well as many other excellent properties such as mold release, transparency, abrasion resistance, and electrical insulation.

[0024] By using a predetermined reactive group for the organic group other than the hydrolyzable functional group of the silane compound that serves as the raw material for ladder-type polysilsesquioxane, it is possible to impart various reactivity to the ladder-type polysilsesquioxane. Furthermore, by introducing a crosslinking reactive group into the ladder-type polysilsesquioxane, other reactive polymer compounds can be incorporated, and a high-performance resin in which the ladder-type polysilsesquioxane is crosslinked can be obtained.

[0025] The resin having a ladder-type polysilsesquioxane structure used in the release layer of the present invention may be a ladder-type polysilsesquioxane resin, or a ladder-type polysilsesquioxane modified resin obtained by copolymerizing a ladder-type polysilsesquioxane resin with one or more other resins such as acrylic resins, urethane resins, or epoxy resins.

[0026] The basic structure of the ladder-type polysilsesquioxane used in the release layer of the present invention is as shown in formula (1). The side chain represented by R in the formula can be arbitrarily selected from an organic group having a carbon-carbon double bond, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. From the viewpoint of improving the physical properties of the final cured composition (release properties from photosensitive resin, silicone migration inhibition, and / or scratch resistance), it is preferable that the proportion of methyl groups (the smallest organic functional group) in the total R exceeds 50 mol%.

[0027]

[0028] Furthermore, the ladder-type polysilsesquioxane's ladder-end structure, as shown in formula (1) above, has almost all of the hydrogen atoms of the terminal silanol groups X 1 ~X 4 It is a functional group substituted with the one shown by X. 1 ~X 4 The silicon-containing group is represented by formulas (2) and (3), and the silicon in the silicon-containing group is bonded to the terminal oxygen of the structure shown in formula (1), thus sealing it. Each of the two ends of formula (1) is sealed by the silicon-containing group represented by formula (3), and the silicon-containing group contains at least one carbon-carbon double bond, and each of the two ends has at least one carbon-carbon double bond introduced into it. These terminal carbon-carbon double bonds act as crosslinking reactive groups and play a role in intermolecular crosslinking.

[0029]

[0030]

[0031] In formula (1), each of the multiple side chains R is independently an organic group having a carbon-carbon double bond, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and may be the same or different from one another. That is, all of the R groups may have the same substituent, some may be the same, or all may be different. Furthermore, if the R groups are different, one or both of the type of R (the double-bonding organic group, alkyl group, or aryl group) and the number of carbon atoms may be different.

[0032] In formula (1), the number of carbon atoms in the side chain R is preferably 1 to 10, and more preferably 1 to 7. Furthermore, from the viewpoint of achieving both low viscosity of the polysilsesquioxane itself and good curability when a cured resin is formed, it is preferable that more than 50 mol% of the total R are methyl groups.

[0033] In formula (1), X is a terminal substituent. 1 and X 2 One of the two groups is represented by formula (2), and the other is represented by formula (3). 3 and X4 One of them is a group represented by formula (2), and the other is a group represented by formula (3). In formula (3), R 1 ~R 3 Among them, at least one is an organic group having a carbon-carbon double bond, and the others are a methyl group or a trimethylsiloxy group.

[0034] Here, R 1 ~R 3 Among them, it is preferable that one is an organic group having a carbon-carbon double bond, and the other two are each independently a methyl group or a trimethylsiloxy group. Also, from the viewpoint of improving the crosslinking property at the terminal, the number of carbon atoms of the organic group having a carbon-carbon double bond is preferably 2 to 10.

[0035] The ladder-type polysilsesquioxane having the structure represented by formula (1) has a carbon-carbon double bond, which is a crosslinking reactive group, at the terminal site with good crosslinking reactivity. Therefore, a crosslinked cured resin having good physical properties (release property from a photosensitive resin, silicone migration inhibitory property, abrasion resistance) can be formed.

[0036] As a method for producing the ladder-type polysilsesquioxane, a general known method can be used. For example, a method is used in which a trialkoxysilane and / or trichlorosilane (raw material silane), which are raw materials, are dissolved in an organic solvent, water is dropped into the obtained solution under cooling or at room temperature, and after stirring to hydrolyze the raw material silane, it is subjected to polycondensation to obtain the target product.

[0037] Specific examples of raw material silanes include the following: For example, methyltrialkoxysilanes such as methyltrimethoxysilane and methyltriethoxysilane; substituted or unsubstituted aryltrialkoxysilanes such as phenyltrimethoxysilane, phenyltriethoxysilane, p-chlorophenyltrimethoxysilane, and m-tolyltrimethoxysilane. Furthermore, examples of raw material silanes having polymerizable (crosslinkable) functional groups containing carbon-carbon double bonds include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, styryltrimethoxysilane, and styryltriethoxysilane. By selecting the type of substituent on the raw material silane, a desired ladder-type polysilsesquioxane having side chains such as (meth)acrylic groups, alkyl groups, phenyl groups, vinyl groups, epoxy groups, hydroxyl groups, and carboxyl groups can be obtained. (Meth)acrylic refers to acrylic and / or methacrylic.

[0038] Ladder-type polysilsesquioxane-modified resins can be obtained by copolymerizing ladder-type polysilsesquioxane with at least one other resin, such as an acrylic resin, urethane resin, or epoxy resin. This copolymerization may be carried out by addition polymerization or condensation polymerization, and there are no particular limitations on the reaction temperature, time, or catalyst used; any conditions can be adopted. Ladder-type polysilsesquioxane-modified resins may be used alone or in combination of two or more. Among these, ladder-type polysilsesquioxane-modified (meth)acrylic resins are preferred as ladder-type polysilsesquioxane-modified resins because they offer an excellent balance between improved scratch resistance of the release layer coating and release properties from photosensitive resins. Examples of (meth)acrylic acid esters that can be copolymerized with ladder-type polysilsesquioxane include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate.

[0039] The resin having a ladder-type polysilsesquioxane structure of the present invention has a hydroxyl value of 20 to 200 mgKOH / g, preferably 109 to 150 mgKOH / g, 109 to 140 mgKOH / g, or 109 to 132 mgKOH / g from the viewpoints of increasing the crosslink density of the coating film, the releasability from the photosensitive resin, and the abrasion resistance. Further, from the viewpoint of further enhancing the releasability, more preferably 118 to 132 mgKOH / g or 120 to 132 mgKOH / g is mentioned. The hydroxyl value described in this specification is a value measured in accordance with JIS K 0070:1992.

[0040] Incidentally, the resin having the ladder-type polysilsesquioxane structure is commercially available under the SQ series, AS series, etc. manufactured by Toxic Co., Ltd.

[0041] Examples of the polyisocyanate for forming a cured product with the ladder-type polysilsesquioxane include aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate; aliphatic diisocyanates such as butylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 1,2-bis(isocyanatomethyl)cyclohexane, norbornene diisocyanate, and the like. These polyisocyanates may be used alone or in combination of two or more. The types of polyisocyanates are not necessarily limited to these. Among these polyisocyanates, aliphatic diisocyanates are preferred, and hexamethylene diisocyanate is more preferred from the viewpoints of enhancing the releasability from the photosensitive resin, suppressing silicone transfer, and / or enhancing the abrasion resistance.

[0042] The amount of polyisocyanate added to the hydroxyl groups of the ladder-type polysilsesquioxane is preferably 0.2 or more, more preferably 0.4 or more, even more preferably 0.6 or more, and even more preferably 0.8 or more, based on the molar ratio (NCO / OH) of isocyanate groups of the polyisocyanate to the hydroxyl groups of the ladder-type polysilsesquioxane, from the viewpoint of improving the film strength of the release layer, release properties from the photosensitive resin, and / or scratch resistance; and preferably 2.0 or less, more preferably 1.7 or less, even more preferably 1.4 or less, and even more preferably 1.2 or less, from the viewpoint of suppressing brittleness of the release layer by suppressing self-crosslinking of the polyisocyanate during curing, improving release properties, improving scratch resistance, and / or suppressing stickiness of the film by suppressing the remaining unreacted isocyanate groups after heat curing. In other words, the specific range for the molar ratio (NCO / OH) of isocyanate groups of polyisocyanate to hydroxyl groups of ladder-type polysilsesquioxane is preferably 0.2 to 2.0, more preferably 0.4 to 1.7, even more preferably 0.6 to 1.4, and even more preferably 0.8 to 1.2.

[0043] The thickness of the release layer is preferably 0.1 μm or more, more preferably 0.4 μm or more, from the viewpoint of improving release properties and scratch resistance, and more preferably 0.55 μm or more or 0.6 μm or more, from the viewpoint of further improving release properties, and from the viewpoint of improving the resolution of the pattern shape formed on the photosensitive resin during exposure, it is preferably 2.0 μm or less, more preferably 1.5 μm or less, even more preferably 1.0 μm or less, and even more preferably 0.8 μm or less. The specific range of the thickness of the release layer is preferably 0.1 to 2.0 μm, more preferably 0.4 to 1.5 μm, even more preferably 0.55 to 1.0 μm or 0.6 to 1.0 μm, and even more preferably 0.6 to 0.8 μm.

[0044] One method for forming a release layer is to dissolve the release layer composition in a solvent to create a coating solution, uniformly coat it onto a substrate film to a predetermined thickness, and then heat-dry it to form a coating film.

[0045] Examples of known methods for applying the coating liquid to the release layer composition include gravure coaters, bar coaters, comma knife coaters, die coaters, and reverse coaters.

[0046] <Adhesive Layer> The adhesive layer used in the present invention can be made of various adhesives such as acrylic, urethane, polyester, silicone, or rubber. There are no particular restrictions, but since it is attached to the surface of the photomask (exposure original), it is preferable to use an acrylic adhesive from the viewpoint of transparency. As for the acrylic adhesive, it is preferable to use one whose main component is an acrylic polymer consisting of a copolymer of (meth)acrylic acid ester monomer and functional group-containing monomer.

[0047] Examples of (meth)acrylic acid ester monomers include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate, and one or more may be used individually or in combination. Among these, butyl acrylate and 2-ethylhexyl acrylate are preferred from the viewpoint of viscoelasticity due to their low glass transition temperature. Examples of functional group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, acrylic acid, methacrylic acid, itaconic acid, and fumaric acid. There are no particular restrictions on the polymerization method, and they can be obtained by known methods such as radical copolymerization.

[0048] The acrylic adhesive described above is preferably one that has a partially cross-linked structure within the acrylic polymer. The presence of a cross-linked structure enhances the cohesive force of the adhesive, making it less likely to leave adhesive residue when the adhesive film is peeled off. Such a cross-linked structure can be formed by using a cross-linking agent that can react with the functional group-containing monomer, and suitable cross-linking agents include, for example, isocyanate-based cross-linking agents, epoxy-based cross-linking agents, and metal chelate-based cross-linking agents.

[0049] In the adhesive layer, so-called tackifier components can be incorporated to improve adhesion. Tackifier components, also known as tackifiers, are substances that are incorporated into elastomers to improve their adhesive properties. They are typically amorphous oligomers with molecular weights ranging from several hundred to several thousand, and are thermoplastic resins that are liquid or solid at room temperature.

[0050] The type of tackifier is not particularly limited, but examples include natural resins such as rosin resins and terpene resins; petroleum resins such as aliphatic, aromatic, and copolymer resins; and synthetic resins such as phenolic resins and xylene resins. These may be used individually or in combination of two or more types.

[0051] From the viewpoint of cohesive force and adhesive strength of the adhesive layer, the amount of tackifier component added is preferably 5 to 80 parts by weight, more preferably 8 to 50 parts by weight, per 100 parts by weight of the adhesive component.

[0052] The thickness of the adhesive layer is preferably in the range of 1 to 20 μm, more preferably in the range of 2 to 15 μm, and even more preferably in the range of 3 to 10 μm, from the viewpoint of adhesive strength, surface conformability, and transparency.

[0053] Methods for forming the adhesive layer include directly applying the adhesive composition as is, or as a coating liquid with its viscosity adjusted using a solvent, to one side of the base film and then drying it; or first forming an adhesive layer on a separator film using the same method, and then transferring it to one side of the base film.

[0054] <Separator Film> It is preferable that a separator film is laminated on the adhesive layer surface to protect the adhesive layer and facilitate handling. The separator film is not particularly limited, and examples include polyethylene terephthalate film laminated with a silicone-based release agent layer or a long-chain alkyl-based release agent layer. This separator film is peeled off from the adhesive layer surface when the adhesive film for protecting the photomask of the present invention is attached to the photomask.

[0055] Examples of coating methods for the adhesive layer include gravure coaters, bar coaters, comma knife coaters, die coaters, and reverse coaters.

[0056] <Applications> The adhesive film for protecting photomasks of the present invention is used for protecting photomasks. For example, the adhesive film for protecting photomasks of the present invention can be used to protect the surface of an exposure photomask used in close contact with an adhesive photosensitive resin in the manufacturing process of printed circuit boards or resin relief plates. Furthermore, because the adhesive film for protecting photomasks of the present invention has excellent properties in terms of release from photosensitive resin, suppression of silicone migration, and scratch resistance, it is particularly preferred for use as a photomask in the manufacture of resin relief plates for liquid crystal alignment film printing, where high-definition thin-film printing is required.

[0057] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, when the amount of each material is indicated as "parts," it refers to parts by weight unless otherwise specified. Furthermore, the ladder-type polysilsesquioxanes 1 to 4 (specifically, ladder-type polysilsesquioxane-modified acrylic resins) used in Examples 1 to 7 have the structure shown in formula (1) above, and in formula (1), the proportion of methyl groups in the total R is more than 50 mol%, and in formula (3) R 1 ~R 3 One of these is an organic group having a carbon-carbon double bond (2 to 10 carbon atoms), and the other two are independently a methyl group or a trimethylsiloxy group.

[0058] (Example 1) <Preparation of adhesive film for photomask protection> [Release layer] A release layer coating liquid 1, prepared by kneading the materials according to the following formulation, was applied to a 6 μm thick PET (polyethylene terephthalate) film so that the film thickness after drying was 0.6 μm, and a laminated release layer film was prepared by heating and drying at 100°C for 1 minute. (Release layer coating liquid 1) Ladder-type polysilsesquioxane 1 8.72 parts (manufactured by Tokushiki Co., Ltd., ladder-type polysilsesquioxane modified acrylic resin, hydroxyl value of solids 120 mg KOH / g, solids content 40%) Hexamethylene diisocyanate 1.49 parts (manufactured by Tokushiki Co., Ltd., NCO%: 21%, solids content 100%) MEK 89.79 parts [Adhesive layer] Adhesive layer coating liquid A, prepared by kneading the materials according to the following formulation, was applied to the silicone release layer surface of a separator film with a thickness of 25 μm (Therapyle® WZ manufactured by Toray Industries, Inc., a laminated film in which a silicone release layer is provided on one side of a PET film) so that the film thickness after drying was 6 μm, and the adhesive layer was formed by heating and drying at 120°C for 2 minutes. The side of the aforementioned release layer laminated film that does not have a release layer and the adhesive layer side were bonded together using a laminator to obtain an adhesive film having the structure of release layer / PET film / adhesive layer / separator. (Coating liquid A for adhesive layer) Acrylic adhesive resin 100.00 parts (manufactured by Fujikura Chemicals, Inc., weight-average molecular weight 650,000, glass transition temperature -66°C, solids content 40%) Tolylene diisocyanate 1.30 parts (manufactured by Mitsui Chemicals, Inc., NCO%: 9.5%, solids content 50%) Ethyl acetate 75.00 parts

[0059] (Example 2) An adhesive film for protecting a photomask was obtained in the same manner as in Example 1, except that the release layer coating liquid was changed to release layer coating liquid 2 prepared by kneading the materials of the following formulation. (Release layer coating liquid 2) Ladder-type polysilsesquioxane 2 8.97 parts (Manufactured by Tokushiki Co., Ltd., ladder-type polysilsesquioxane-modified acrylic resin, hydroxyl value of solids 132 mg KOH / g, solids 38%) Hexamethylene diisocyanate 1.60 parts (Manufactured by Tokushiki Co., Ltd., NCO%: 21%, solids 100%) MEK 89.49 parts

[0060] (Example 3) An adhesive film for protecting a photomask was obtained in the same manner as in Example 1, except that the release layer coating liquid was changed to release layer coating liquid 3 prepared by kneading the materials of the following formulation. (Release layer coating liquid 3) Ladder-type polysilsesquioxane 3 8.60 parts (Manufactured by Tokushiki Co., Ltd., ladder-type polysilsesquioxane-modified acrylic resin, hydroxyl value of solids 109 mg KOH / g, solids content 42%) Hexamethylene diisocyanate 1.40 parts (Manufactured by Tokushiki Co., Ltd., NCO%: 21%, solids content 100%) MEK 90.00 parts

[0061] (Example 4) An adhesive film for protecting a photomask was obtained in the same manner as in Example 1, except that the release layer coating liquid was changed to release layer coating liquid 4 prepared by kneading the materials of the following formulation. (Release layer coating liquid 4) Ladder-type polysilsesquioxane 4 9.35 parts (Manufactured by Tokushiki Co., Ltd., ladder-type polysilsesquioxane modified acrylic resin, hydroxyl value of solids 20 mg KOH / g, solids 50%) Hexamethylene diisocyanate 0.33 parts (Manufactured by Tokushiki Co., Ltd., NCO%: 21%, solids 100%) MEK 90.32 parts

[0062] (Example 5) An adhesive film for protecting a photomask was obtained in the same manner as in Example 1, except that the film thickness of the release layer after drying was changed to 0.2 μm.

[0063] (Example 6) An adhesive film for protecting a photomask was obtained in the same manner as in Example 1, except that the film thickness of the release layer after drying was changed to 0.4 μm.

[0064] (Example 7) An adhesive film for protecting a photomask was obtained in the same manner as in Example 1, except that the film thickness of the release layer after drying was changed to 0.8 μm.

[0065] (Comparative Example 1) A protective adhesive film for photomasks was obtained in the same manner as in Example 1, except that the release layer coating liquid was changed to a release layer coating liquid 5 prepared by kneading the materials of the following formulation. (Release Layer Coating Liquid 5) Ladder-type polysilsesquioxane 1 12.41 parts (Tokushiki Co., Ltd., ladder-type polysilsesquioxane modified acrylic resin, hydroxyl value of solids 120 mg KOH / g, solids 40%) MEK 87.59 parts

[0066] (Comparative Example 2) A protective adhesive film for photomasks of Comparative Example 2 was obtained in the same manner as in Example 1, except that the release layer coating liquid was changed to release layer coating liquid 6 prepared by kneading the materials of the following formulation, and the film thickness of the release layer after drying was changed to 0.2 μm. (Release Layer Coating Liquid 6) Acrylic-silicone copolymer resin 1 8.90 parts (Polyalloy manufactured by Natco Co., Ltd., block type, hydroxyl value of solids 53.7 mg KOH / g, solids content 27%) Acrylic-silicone copolymer resin 2 5.34 parts (Cymac manufactured by Toagosei Co., Ltd., graft type, hydroxyl value 0 mg KOH / g, solids content 30%) Tolylene diisocyanate 2.00 parts (Manufactured by Mitsui Chemicals, Inc., NCO%: 7.9%, solids content 50%) MEK 75.18 parts PGM-AC 8.57 parts

[0067] (Evaluation) The following evaluations were performed on the adhesive films for photomask protection prepared in each example and comparative example. (1) Release properties <Evaluation of peeling force against photosensitive resin> A photosensitive resin (APR K-11 manufactured by Asahi Kasei Corporation) was coated onto a 100 μm thick PET film to a thickness of 2.3 mm to form a photosensitive resin layer. Next, the release layer surfaces of the adhesive films for photomask protection of each example and comparative example were placed on top of the photosensitive resin layer, taking care not to introduce air bubbles, and UV (ultraviolet) irradiation was performed from the 100 μm PET film side (high-pressure mercury lamp, integrated light amount 400 mJ / cm²). 2 The following tests were conducted: After performing the test and letting the sample stand for 1 minute at a temperature of 23±2°C and a humidity of 50±5%RH, the photosensitive resin layer was cured by UV (ultraviolet) irradiation from the adhesive film side for photomask protection under the same conditions as above, and this was used as an evaluation sample. Next, the evaluation sample was left to stand for 1 hour in an environment of 23±2°C and a humidity of 50±5%RH, and a sample measuring 25 mm wide x 150 mm long was cut out. Using a tensile testing machine in an environment of 23±2°C and 50±5%RH, the peel force when peeling the adhesive film for photomask protection from the photosensitive resin layer was measured at a peel angle of 180° and a peel speed of 300 mm / min, and evaluated according to the following evaluation criteria. The results of the release properties measurement (measured value of peel force) and the evaluation results of the release properties are shown in Table 1. (Evaluation criteria) ◎: The peel force is less than 300 mN / 25 mm. ○: The peel force is 300 mN / 25 mm or more and less than 600 mN / 25 mm. ×: The peeling force is 600 mN / 25 mm or more.

[0068] (2) Silicone migration suppression <Evaluation of component migration suppression to photosensitive resin> After the peeling strength evaluation, the surface of the photosensitive resin layer from which the protective adhesive film for the photomask was peeled off was subjected to scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) analysis using a scanning electron microscope (JEOL Ltd. JSM-IT100) to detect the Si element, and was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation criteria) ◎: No Si element detected (below the detection limit) ×: Si element detected

[0069] (3) Scratch Resistance Test pieces measuring 25 mm wide x 50 mm long were cut from the adhesive film used to protect the photomasks of each example and comparative example to prepare test pieces. The separator was peeled off the test pieces, and after pressing them back and forth twice with a 2 kgf rubber roller, the adhesive layer surface was attached to the photomask to prepare evaluation samples. Next, using a flat abrasion tester (RT-200 manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), the evaluation sample 20 was fixed to the sample fixing stand 30 of the tester with the release layer facing upwards, as shown in Figure 2, and the abrasion indenter 50 (Nail Color Chart Stick DI-20- manufactured by Daiso Sangyo Co., Ltd.) was used. P The 6H-109 was fixed to the abrasive indenter fixing device 40 of the testing machine, and an abrasion test was performed on the release layer while applying a load with a 200gf weight 60. In the abrasion test, the abrasive indenter 50 was moved back and forth in the thickness direction (direction B in Figures 2 and 3) at an abrasion speed of 70 mm / second for a total of 10 back and forth movements over a width of 30 mm in direction B. The abraded areas on the surface of the release layer were visually inspected and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ◎: No scratches ○: Very slight scratches visible to the naked eye ×: Scratches, clouding, or peeling of the coating visible to the naked eye

[0070]

[0071] As shown in Table 1, the adhesive films for protecting photomasks of Examples 1 to 7 exhibited excellent properties in terms of release properties from photosensitive resin, silicone migration suppression, and scratch resistance. In particular, the adhesive films for protecting photomasks of Examples 1 to 3, 6, and 7 (especially Examples 1, 2, and 7) showed superior performance. Furthermore, because the adhesive films for protecting photomasks of Examples 1 to 7 exhibit the above-mentioned excellent properties, they were found to be useful for photomask applications in the manufacturing of resin relief plates for alignment film printing.

[0072] 10: Adhesive film for protecting photomask 11: Release layer 12: Base film 13: Adhesive layer 14: Separator film 20: Evaluation sample 30: Sample holder 40: Scratching indenter holder 50: Scratching indenter 60: 200 gf weight A: Width direction of scratching indenter B: Thickness direction of scratching indenter

Claims

1. A photomask protective adhesive film comprising a transparent substrate film with an adhesive layer on one side and a release layer on the other side, characterized in that the release layer is a cured product of a release layer composition containing a resin having a ladder-type polysilsesquioxane structure and a polyisocyanate.

2. The adhesive film for protecting photomasks according to claim 1, characterized in that the hydroxyl value of the resin having the ladder-type polysilsesquioxane structure is 109 to 132 mgKOH / g.

3. The adhesive film for protecting a photomask according to claim 1, characterized in that the coating thickness of the release layer is 0.4 to 0.8 μm.

4. The adhesive film for protecting a photomask according to any one of claims 1 to 3, characterized in that the adhesive film for protecting the photomask is for use in photomasks used in the manufacture of resin relief plates for orientation film printing.

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