Adhesive film for protecting photomasks

Abstract

To provide an adhesive film for protecting photomasks that has good release properties from photoresists and excellent scratch resistance of the release layer. [Solution] A protective adhesive film for photomasks, comprising a transparent base film with an adhesive layer on one side and a release layer on the other side, wherein the release layer is a cured product of a release layer composition comprising (A) a hydroxyl group-containing acrylic polymer, (B) a silicone-modified isocyanate containing a reaction product of a specific component, and (C) a silicone-grafted acrylic polymer.

Description

[Technical Field]

[0001] The present invention relates to an adhesive film for protecting a photomask, which is used to protect the surface of an exposure photomask that is in close contact with an adhesive photoresist in the manufacturing process of printed circuit boards, resin relief plates, and the like. [Background technology]

[0002] Typically, printed circuit boards and resin relief plates are manufactured by closely exposing a photomask (exposure template) to an adhesive photoresist, such as a liquid photoresist. Therefore, conventionally, a surface protection film with release properties is provided on the surface of the photomask facing the photoresist to prevent the photoresist from adhering to the photomask. This surface protection film of the photomask has an adhesive layer on one side of the film substrate and a release layer on the other side to prevent the resist 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, and these silicone components migrate to the resist side, causing problems such as 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 the resist 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 resist and foreign matter. The surface protection film of Patent Document 1 suffers from reduced mold release properties to photoresist 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 protection film with improved solvent resistance, having a structure in which a base layer containing a saturated copolymer polyester resin and fine particles, and a resist adhesion prevention layer (release layer) made of a cured product of an addition reaction type silicone composition are sequentially laminated on one side of a base film. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-7121 [Patent Document 2] Japanese Patent Publication No. 2000-273412 [Overview of the project] [Problems that the invention aims to solve]

[0007] Generally, when applying a surface protection 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 protection film, exposure failures will occur due to the foreign matter and the air bubbles around it. In such cases, it is necessary to reapply the surface protection film to remove the foreign matter. However, with photomasks for resin plates, the surface area of ​​the surface protection 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 protection 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, a decrease in the resolution of the resist, and defects.

[0008] The surface protective film described 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] This 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 photoresists and excellent scratch resistance of the release layer. [Means for solving the problem]

[0010] The first invention is an adhesive film for protecting a photomask, comprising a transparent base 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 the following components (A) to (C). (A) Hydroxyl group-containing acrylic polymer (B) Silicone-modified polyisocyanates containing reaction products obtained by reacting an organopolysiloxane having a hydroxyl group at one end with a polyisocyanate compound. (C) Silicone graft acrylic polymer

[0011] The second invention is an adhesive film for protecting a photomask according to the first invention, characterized in that component (A) has a glass transition temperature of 70 to 140°C and a hydroxyl value of 80 to 200 mgKOH / g.

[0012] The third invention is an adhesive film for protecting a photomask according to the first or second invention, characterized in that the polyisocyanate compound is an adduct or isocyanurate of polyisocyanate.

[0013] The fourth invention is an adhesive film for protecting a photomask according to any one of the first to third inventions, characterized in that component (C) is contained in 3 to 20% by mass of the solid content of the release layer composition. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide an adhesive film for protecting photomasks that has good release properties from photoresist, suppresses the migration of silicone components to the photoresist surface, and has excellent scratch resistance of the release layer, as a surface protective film for photomasks.

Brief Description of Drawings

[0015] [Figure 1] It is a schematic cross-sectional view showing one aspect of the adhesive film for photo mask protection of the present invention. [Figure 2] It is a schematic side view showing the installation state of an evaluation sample on a flat abrasion tester in the abrasion resistance evaluation of the present invention. [Figure 3] It is a schematic view showing the width direction and thickness direction of a rubbing indenter in the abrasion resistance evaluation of the present invention.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described.

[0017] FIG. 1 shows a schematic cross-sectional view of an embodiment of the adhesive film for photo mask protection of the present invention. The adhesive film 10 for photo mask protection shown in FIG. 1 has a configuration in which a release layer 11 is provided on one surface of a base film 12, an adhesive layer 13 is provided on the other surface, and a separator film 14 is laminated on the adhesive layer 13. The adhesive film 10 for photo mask protection of the present invention may be provided with an anchor layer, an antistatic layer, etc. between the base film 12 and the release layer 11, and between the base film 12 and the adhesive layer 13. When the adhesive film 10 for photo mask protection is used, the separator film 14 is peeled off, and it becomes a form of release layer 11 / base film 12 / adhesive layer 13.

[0018] <Base Film>[ As the transparent base film used in the present invention, the higher the transmittance of ultraviolet rays used during exposure, the more preferable it is. For example, plastic films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polystyrene, triacetyl cellulose, acrylic, and polyvinyl chloride can be mentioned. Among these, a biaxially stretched polyethylene terephthalate film can be preferably used in terms of excellent mechanical strength and dimensional stability. [[ID= (32)]]

[0019] The base film may be surface-treated. Examples of surface treatments include corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, and primer treatment.

[0020] 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, and even more preferably 4 μm or more. Furthermore, from the viewpoint of light transmittance, it is preferably 50 μm or less, more preferably 25 μm or less, and even more preferably 12 μm or less.

[0021] <Release layer> The release layer of the present invention is composed of a cured product of a release layer composition comprising (A) a hydroxyl group-containing acrylic polymer (hereinafter referred to as component (A)) as a resin component, (B) a silicone-modified polyisocyanate containing a reaction product obtained by reacting an organopolysiloxane having a hydroxyl group at one end with a polyisocyanate compound (hereinafter referred to as component (B)) as a curing agent component, and (C) a silicone-grafted acrylic polymer (hereinafter referred to as component (C)) as a release-improving component. By using a release layer with this configuration, an adhesive film for protecting photomasks with excellent release properties and scratch resistance can be obtained.

[0022] <Component (A): Hydroxyl group-containing acrylic polymer> Component (A) used in the release layer of the present invention can be obtained by a monomer mixture containing a hydroxyl group-containing acrylic monomer by known methods such as radical copolymerization. Examples of hydroxyl group-containing acrylic monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and ε-caprolactone, ethylene oxide, or propylene oxide ring-opening adducts of 2-hydroxyethyl (meth)acrylate. These hydroxyl group-containing acrylic monomers may be used individually or in combination of two or more. (Meth)acrylic means acrylic and / or methacrylic.

[0023] Examples of acrylic monomers copolymerizable with the hydroxyl group-containing acrylic monomer include alkyl esters of (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; as well as (meth)acrylic acid, acrylonitrile, methacrylonitrile, acrylamide, and methacrylamide. These copolymerizable acrylic monomers may be used individually or in combination of two or more with respect to the hydroxyl group-containing acrylic monomer.

[0024] Examples of copolymerizable monomers other than the acrylic monomers mentioned above include maleic acid, fumaric acid, itaconic acid, styrene, α-methylstyrene, and butadiene.

[0025] The glass transition temperature of component (A) is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, from the viewpoint of increasing the hardness of the release layer coating and improving scratch resistance. Furthermore, from the viewpoint of ensuring the formation of a release layer coating and suppressing the hardening of the cured product, it is preferably 140°C or lower, more preferably 120°C or lower, and even more preferably 110°C or lower. Note that the glass transition temperature in this invention is the midpoint glass transition temperature measured by differential scanning calorimetry (DSC) in accordance with JIS K7121:1987.

[0026] The hydroxyl value of component (A) is preferably 80 mg KOH / g or higher, more preferably 90 mg KOH / g or higher, and even more preferably 100 mg KOH / g or higher, from the viewpoint of increasing the crosslinking density of the release layer coating and improving the coating strength. Furthermore, from the viewpoint of ensuring good solubility in organic solvents and compatibility with other components of the release layer composition, it is preferably 200 mg KOH / g or lower, more preferably 190 mg or lower, and even more preferably 180 mg or lower. Note that the hydroxyl value in this invention is a value measured in accordance with JIS K 0070:1992.

[0027] The weight-average molecular weight of component (A) is preferably in the range of 1,000 to 100,000, more preferably in the range of 2,000 to 50,000, and even more preferably in the range of 3,000 to 30,000, from the viewpoint of improving the strength of the release layer coating and ensuring good coating film formation. In this invention, the weight-average molecular weight is the weight-average molecular weight on a polystyrene basis measured by gel permeation chromatography (GPC).

[0028] <Component (B): Silicone-modified polyisocyanate> Component (B) of the present invention is a silicone-modified polyisocyanate containing a reaction product obtained by the reaction of a hydroxyl group of an organopolysiloxane having a hydroxyl group at one end with an isocyanate group of a polyisocyanate compound, wherein the reaction product has an organopolysiloxane (silicone chain) and an isocyanate group in its molecule, and acts as a curing agent for component (A), imparting release properties and sliding properties to the cured product. By using an organopolysiloxane having a hydroxyl group at one end, the silicone chain is particularly easily oriented toward the surface of the cured product, thereby improving the release properties and sliding properties of the cured product and enhancing scratch resistance.

[0029] As an organopolysiloxane having a hydroxyl group at one end of component (B), a linear organopolysiloxane in which an organic group having one hydroxyl group is bonded to a silicon atom at one end of the molecular chain is preferred, for example, a linear organopolysiloxane modified with a carbinol at one end.

[0030] A linear organopolysiloxane modified with a single-terminated carbinol is one in which a carbinol group (a saturated aliphatic monovalent hydrocarbon group such as an alkyl group having a methylol group; -CH2OH at the terminal and which may also have an ether-bonded oxygen atom (-O-)) is bonded to a silicon atom at one end of the organopolysiloxane molecular chain. The carbinol group preferably has about 1 to 6 carbon atoms, and examples include a hydroxymethyl group, a 2-hydroxyethyl group, a 3-hydroxypropyl group, a 3-(2-hydroxyethoxy)propyl group, and a 3-(3-hydroxypropoxy)propyl group.

[0031] The organic group bonded to the silicon atom other than the hydroxyl group of the organopolysiloxane having a hydroxyl group at one end is preferably a hydrocarbon group having 1 to 6 carbon atoms, preferably an alkyl group or phenyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group.

[0032] The weight-average molecular weight of the organopolysiloxane having a hydroxyl group at one end is preferably in the range of 1,000 to 30,000, and more preferably in the range of 1,000 to 20,000, from the viewpoint of release properties.

[0033] The polyisocyanate compounds constituting component (B) are compounds having two or more isocyanate groups in one molecule, and examples include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, and hydrogenated xylylene diisocyanate; and aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. Furthermore, adducts, biurets, and isocyanurates of these polyisocyanates can also be used. These may be used individually or in combination of two or more. Among these, from the viewpoint of improving the scratch resistance of the release layer, it is preferable to use a polyisocyanate adduct or isocyanurate, and it is particularly preferable to use a hexamethylene diisocyanate isocyanurate.

[0034] When reacting an organopolysiloxane having a hydroxyl group at one end of component (B) with a polyisocyanate compound, the molar ratio (NCO / OH) of the hydroxyl group (OH) of the organopolysiloxane having a hydroxyl group at one end to the isocyanate group (NCO) of the polyisocyanate compound is preferably in the range of 500 to 2500, and more preferably in the range of 1000 to 2000, from the viewpoint of compatibility with the release layer composition, film formation, and ensuring curability by sufficiently retaining the isocyanate group.

[0035] Component (B) can be easily obtained by reacting the organopolysiloxane having a hydroxyl group at one end with the polyisocyanate compound in the absence of a solvent or an organic solvent, in or without a conventional urethane catalyst, at a temperature of about 0 to 150°C, preferably 20 to 80°C, for about 4 to 12 hours.

[0036] From the viewpoint of improving the scratch resistance of the cured product, the combination of component (A) and component (B) in the release layer composition is preferably such that the molar ratio (NCO / OH) of hydroxyl groups (OH) of component (A) to isocyanate groups (NCO) of component (B) is in the range of 0.5 to 2.5, and more preferably in the range of 1.0 to 2.0. In this case, the number of moles of isocyanate groups of component (B) is the value obtained by subtracting the number of moles of hydroxyl groups of the organopolysiloxane having hydroxyl groups from the number of moles of isocyanate groups of the polyisocyanate compound constituting component (B) before reaction.

[0037] <Ingredients (C): Silicone graft acrylic polymer> Component (C) of the present invention is obtained by grafting an organopolysiloxane skeleton (silicone skeleton) onto the polymer chain of an acrylic polymer, and is preferably a comb-shaped graft polymer synthesized by copolymerization of a silicone macromonomer and an acrylic monomer. More specifically, it is a comb-shaped graft polymer in which the trunk portion is a (meth)acrylic polymer and the branches are composed of silicone macromonomers accounting for 3 to 60% by mass of the total.

[0038] Examples of silicone macromonomers include monomers having a radically polymerizable unsaturated group at one end of an organopolysiloxane skeleton, and for example, compounds represented by the following formula (1) can be suitably used.

[0039] [ka]

[0040] In formula (1), R 1 R represents an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an n-butyl group. 2 The group represents a monovalent organic group, and -CH=CH2, -C6H4-CH=CH2, -(CH2)3O(CO)CH=CH2, or -(CH2)3O(CO)C(CH3)=CH2 are preferred. 3These may be the same or different, and represent a hydrocarbon group having 1 to 6 carbon atoms, preferably an alkyl group or phenyl group having 1 to 4 carbon atoms, and more preferably a methyl group. Furthermore, the value of n is not particularly limited, for example, the weight-average molecular weight of the silicone macromonomer is preferably in the range of 1000 to 30000, and more preferably in the range of 1000 to 20000.

[0041] Examples of acrylic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. These may be used individually or in combination of two or more.

[0042] In addition to the acrylic monomers mentioned above, functional group-containing monomers can also be copolymerized. Examples of functional group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, acrylic acid, methacrylic acid, itaconic acid, and fumaric acid.

[0043] The method for copolymerizing the above-mentioned silicone macromonomer and acrylic monomer is not particularly limited, and for example, silicone-grafted acrylic polymers can be obtained by known methods such as radical copolymerization.

[0044] The glass transition temperature of the (meth)acrylic polymer, which is the core component of component (C), is preferably 120°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher, from the viewpoint of increasing the hardness of the release layer and improving scratch resistance. Furthermore, from the viewpoint of good coating film formation of the release layer, it is preferably 180°C or lower, more preferably 170°C or lower, and even more preferably 160°C or lower. The higher the glass transition temperature of the (meth)acrylic polymer, which is the core component of component (C), the easier it is to form a coating film with good scratch resistance.

[0045] The weight-average molecular weight of component (C) is preferably in the range of 10,000 to 300,000, and more preferably in the range of 50,000 to 150,000, from the viewpoint of improving the strength of the release layer coating and ensuring good coating film formation.

[0046] From the viewpoint of improving release properties and ensuring scratch resistance, the content of component (C) is preferably in the range of 3 to 20% by mass, and more preferably in the range of 5 to 15% by mass, of the solid content of the release layer composition.

[0047] Component (C) may or may not have a functional group that reacts with the isocyanate group of component (B). Examples of functional groups that react with the isocyanate group include hydroxyl groups and amino groups.

[0048] From the viewpoint of ensuring uniformity and strength of the coating film, the thickness of the release layer of the present invention is preferably 0.05 to 2.0 μm, and more preferably 0.1 to 1.0 μm.

[0049] As a method for forming the release layer of the present invention, the release layer composition is dissolved in a solvent to form a coating solution, which is then uniformly applied to a substrate to a predetermined thickness, and a coating film is formed by heating and drying.

[0050] Examples of coating methods for the release layer composition include gravure coaters, bar coaters, comma knife coaters, die coaters, and reverse coaters.

[0051] <Adhesive layer> The adhesive layer used in the present invention is not particularly limited, but since it is attached to the surface of a photomask (exposure original), it is preferable to use an acrylic adhesive from the viewpoint of transparency. As an 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.

[0052] Examples of (meth)acrylic acid ester monomers include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate, which can be used individually or in combination of two or more. 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.

[0053] 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.

[0054] In the adhesive layer of the present invention, a so-called tackifier component may be incorporated to improve adhesive strength. A tackifier component, also called a tackifier, is a substance that is incorporated into an elastomer to improve its adhesive function. It is typically an amorphous oligomer with a molecular weight of several hundred to several thousand, and is a thermoplastic resin that is liquid or solid at room temperature.

[0055] The types of tackifiers are 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.

[0056] 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.

[0057] The thickness of the adhesive layer of the present invention 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.

[0058] 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.

[0059] Examples of coating methods for the adhesive layer coating liquid of the present invention include gravure coaters, bar coaters, comma knife coaters, die coaters, and reverse coaters.

[0060] <Separator film> Preferably, 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 on which a silicone-based release agent layer or a long-chain alkyl-based release agent layer is formed. This separator film is peeled off when the adhesive film for protecting the photomask of the present invention is attached to the photomask. [Examples]

[0061] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0062] <Release layer coating liquid material> [Hydroxygroup-containing acrylic polymer A1]; Acrylic resin solution manufactured by DIC Corporation, solid content 65%, glass transition temperature 100°C, hydroxyl value of solid content 107 mgKOH / g [Hydroxygroup-containing acrylic polymer A2]; Acrylic resin solution manufactured by DIC Corporation, solids content 60%, glass transition temperature 70°C, hydroxyl value of solids 90 mg KOH / g [Polyisocyanate compound 1]; Asahi Kasei Corporation's isocyanurate form of hexamethylene diisocyanate (HDI), 100% solids content, 12.0% isocyanate group content. [Polyisocyanate compound 2]; Trimethylolpropane (TMP) adduct of xylylene diisocyanate (XDI), manufactured by Mitsui Chemicals, Inc., with a solid content of 75% and isocyanate group content of 11.5%. [Organopolysiloxane 1 with a hydroxyl group at one end]; Carbinol-modified silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd., 100% solids, hydroxyl value 12 mg KOH / g [Silicone grafted acrylic polymer C1]; Natco Co., Ltd. Polyalloy FBR-704, solids content 34%, glass transition temperature 160℃, hydroxyl value 0 mgKOH / g, weight-average molecular weight 98000

[0063] <Adjustment of component (B)> [Silicone-modified polyisocyanate B1]; In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube, 99.15 parts by weight of polyisocyanate compound 1, 0.85 parts by weight of organopolysiloxane 1 having a hydroxyl group at one end, and 900 parts by weight of toluene were charged. The mixture was stirred at 65°C for 5 hours to allow the reaction to proceed, and then cooled to room temperature. The resulting solution containing the reaction product is called silicone-modified polyisocyanate B1 (molar ratio of hydroxyl groups to isocyanate groups (NCO / OH) = 1558, solid content 10%, isocyanate group concentration in solid content 2.831 × 10⁻⁶). -3 (mol / g) [Silicone-modified polyisocyanate B2]; In a reaction vessel similar to that used for silicone-modified isocyanate B1, 99.32 parts by weight of polyisocyanate compound 1, 0.68 parts by weight of organopolysiloxane 1 having a hydroxyl group at one end, and 900 parts by weight of toluene were charged. The mixture was stirred at 65°C for 5 hours to allow the reaction to proceed, and then cooled to room temperature. The resulting solution containing the reaction product is called silicone-modified polyisocyanate B2 (molar ratio of hydroxyl groups to isocyanate groups (NCO / OH) = 1951, solid content 10%, isocyanate group concentration in solid content 2.836 × 10⁻⁶). -3 (mol / g) [Silicone-modified polyisocyanate B3]; In a reaction vessel similar to that used for silicone-modified isocyanate B1, 98.98 parts by weight of polyisocyanate compound 1, 1.02 parts by weight of organopolysiloxane 1 having a hydroxyl group at one end, and 900 parts by weight of toluene were charged. The mixture was stirred at 65°C for 5 hours to allow the reaction to proceed, and then cooled to room temperature. The resulting solution containing the reaction product is called silicone-modified polyisocyanate B3 (molar ratio of hydroxyl groups to isocyanate groups (NCO / OH) = 1296, solid content 10%, isocyanate group concentration in solid content 2.826 × 10⁻⁶). -3 (mol / g) [Silicone-modified polyisocyanate B4]; In a reaction vessel similar to that used for silicone-modified isocyanate B1, 131.6 parts by weight of polyisocyanate compound 2, 1.30 parts by weight of organopolysiloxane 1 having a hydroxyl group at one end, and 867 parts by weight of toluene were charged. The mixture was stirred at 65°C for 5 hours to allow the reaction to proceed, and then cooled to room temperature. The resulting solution containing the reaction product is called silicone-modified polyisocyanate B4 (molar ratio of hydroxyl groups to isocyanate groups (NCO / OH) = 1296, solid content 10%, isocyanate group concentration in solid content 3.601 × 10⁻⁶). -3 (mol / g)

[0064] <Preparation of release layer coating solution> The components (B) prepared above and the release layer coating liquid material were mixed according to the formulations shown in Table 1 to prepare release layer coating liquids 1 to 9.

[0065] [Table 1]

[0066] (Example 1) <Preparation of adhesive film> (Release layer) A release layer coating solution 1 was applied to a 6 μm thick PET (polyethylene terephthalate) film so that the film thickness after drying was 0.2 μm. The film was then heated and dried at 140°C for 1 minute to produce a laminated release layer film. (Adhesive layer) A 25 μm thick separator film (Therapyel® WZ, manufactured by Toray Industries, Inc.) was coated with adhesive coating liquid A, mixed according to the following formulation, so that the film thickness after drying would be 6 μm. The film was then heated and dried at 120°C for 2 minutes to form an adhesive layer. The side of the release layer laminated film that did not have a release layer and the side with the adhesive layer were then laminated together using a laminator to obtain a photomask protective adhesive film having the structure of release layer / PET film / adhesive layer / separator film. (Formulation of adhesive layer coating liquid A) Acrylic adhesive resin (manufactured by Fujikura Chemicals, Inc., weight-average molecular weight 650,000, glass transition temperature -66°C, solids content 40%) 100 parts by weight, isocyanate curing agent (manufactured by Mitsui Chemicals, Inc., TDI-based polyisocyanate, isocyanate group content 9.5%, solids content 50%) 1.3 parts by weight, ethyl acetate 75 parts by weight

[0067] (Example 2) An adhesive film for protecting a photomask of Example 2 was obtained in the same manner as in Example 1, except that release layer coating liquid 1 was changed to release layer coating liquid 2.

[0068] (Example 3) An adhesive film for protecting a photomask of Example 3 was obtained in the same manner as in Example 1, except that the release layer coating liquid 1 was changed to the release layer coating liquid 3.

[0069] (Example 4) An adhesive film for protecting a photomask of Example 4 was obtained in the same manner as in Example 1, except that release layer coating liquid 1 was changed to release layer coating liquid 4.

[0070] (Example 5) An adhesive film for protecting a photomask of Example 5 was obtained in the same manner as in Example 1, except that the release layer coating liquid 1 was changed to release layer coating liquid 5.

[0071] (Example 6) An adhesive film for protecting a photomask of Example 6 was obtained in the same manner as in Example 1, except that the release layer coating liquid 1 was changed to the release layer coating liquid 6.

[0072] (Example 7) An adhesive film for protecting a photomask of Example 7 was obtained in the same manner as in Example 1, except that the release layer coating liquid 1 was changed to the release layer coating liquid 7.

[0073] (Example 8) An adhesive film for protecting a photomask of Example 8 was obtained in the same manner as in Example 1, except that the release layer coating liquid 1 was changed to the release layer coating liquid 8.

[0074] (Example 9) An adhesive film for protecting a photomask of Example 9 was obtained in the same manner as in Example 1, except that release layer coating liquid 1 was changed to release layer coating liquid 9.

[0075] (Comparative Example 1) Comparative Example 1, an adhesive film for protecting a photomask, was obtained in the same manner as in Example 1, except that the release layer coating liquid 1 was changed to a coating liquid prepared by mixing 99 parts by weight of an addition-curing type silicone release agent (KS-776A, manufactured by Shin-Etsu Chemical Co., Ltd., 30% solids), 1 part by weight of a curing catalyst (CAT.PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd., 2% solids), and 500 parts by weight of toluene.

[0076] The following evaluations were performed on each adhesive film prepared in the examples and comparative examples.

[0077] <Mold release properties evaluation> A photosensitive resin layer (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 protective films for photomasks of each example and comparative example were placed on top of the photosensitive resin layer, taking care to avoid air bubbles, and UV (ultraviolet) irradiation was applied from the 100 μm PET film side (high-pressure mercury lamp, cumulative light intensity 400 mJ / cm²). 2 The following steps were performed: the photosensitive resin layer was cured by UV (ultraviolet) irradiation from the adhesive film side of the photomask protection under the same conditions as above, after which the sample was prepared for evaluation. Next, the sample was left to stand for 1 hour in an environment of 23±2°C and 50±5%RH, and a sample measuring 25 mm wide x 150 mm long was cut out. The peel force when peeling the adhesive film for photomask protection from the photosensitive resin layer was measured using a tensile testing machine in an environment of 23±2°C and 50±5%RH at a peel angle of 180° and a peel speed of 300 mm / min, and evaluated according to the following evaluation criteria. The evaluation results for each example and comparative example are shown in Table 2. (Evaluation Criteria) ◎: The peeling force is less than 300 mN / 25 mm. ○: The peeling 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. (Evaluation Criteria)

[0078] <Silicone migration evaluation> The surface of the photosensitive resin layer, after the peeling strength evaluation, was peeled off to detect the Si element using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) analysis with a scanning electron microscope (JEOL Ltd. JSM-IT100), and evaluated according to the following evaluation criteria. The evaluation results for the examples and comparative examples are shown in Table 2. (Evaluation Criteria) ◎: No Si element detected by SEM-EDX (below the detection limit) ×: Si element detected by SEM-EDX.

[0079] <Abrasion resistance evaluation> For the adhesive films for photomask protection in each example and comparative example, test pieces with a width of 25 mm and a length of 50 mm were cut out, the separators of the test pieces were peeled off, and they were pressure-bonded back and forth twice with a 2 kgf rubber roller, and 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 Co., Ltd.), as shown in Fig. 2, the evaluation sample 20 was fixed to the sample fixing table 30 of the tester so that the release layer was on the upper surface, and the rubbing indenter 50 (Nail Color Chart Stick DI-20- P 6H-109 manufactured by Daiwa Sangyo Co., Ltd.) was fixed to the rubbing indenter fixture 40 of the tester. While applying a load of 200 gf of copper 60, a release layer rubbing test was performed 10 times with a rubbing speed of 70 mm / second in the thickness direction of the rubbing indenter 50 (direction B in Fig. 3) and a test distance of 30 mm in the left-right direction of Fig. 2. The rubbed portion of the release layer surface was visually confirmed and evaluated according to the following evaluation criteria. The evaluation results of each example and comparative example are shown in Table 2. (Evaluation Criteria) ◎: No damage ○: Very slightly damaged visually ×: Visible damage, white turbidity, or peeling of the coating film

[0080]

Table 2

Explanation of Symbols

[0081] 10: Adhesive film for photomask protection 11: Release layer 12: Substrate film 13: Adhesive layer 14: Separator film 20: Evaluation sample 30: Sample fixing table 40: Rubbing indenter fixture 50: Rubbing indenter 60: 200 gf of copper A: Width direction of the rubbing indenter B: Thickness direction of the rubbing indenter

Claims

1. A photomask protective adhesive film comprising a transparent base 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 the following components (A) to (C). (A) Hydroxyl group-containing acrylic polymer (B) Silicone-modified polyisocyanate containing a reaction product obtained by reacting an organopolysiloxane having a hydroxyl group at one end with a polyisocyanate compound. (C) Silicone grafted acrylic polymer

2. The adhesive film for protecting a photomask according to claim 1, characterized in that component (A) has a glass transition temperature of 70 to 140°C and a hydroxyl value of 80 to 200 mg KOH / g.

3. The adhesive film for protecting a photomask according to claim 1 or 2, characterized in that the polyisocyanate compound is an adduct or isocyanurate of polyisocyanate.

4. The adhesive film for protecting a photomask according to claim 1 or 2, characterized in that the component (C) is contained in 3 to 20% by weight of the solid content of the release layer composition.

5. The adhesive film for protecting a photomask according to claim 3, characterized in that the component (C) is contained in 3 to 20% by weight of the solid content of the release layer composition.

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