Adhesive tape for protecting photomasks

Abstract

To provide an adhesive tape for protecting photomasks used in resin relief printing, which prevents air bubbles from forming when applied to the photomask even when it is a thin film, and facilitates repair work in the event of foreign matter contamination. [Solution] A photomask protective adhesive tape comprising a transparent base film with an adhesive layer on one side and a release layer on the other side, wherein the adhesive layer is a cured product of an adhesive layer composition containing (A) an acrylic acid ester polymer, (B) a crosslinking agent, and (C) an oil having trimethylolpropane fatty acid triester, and the solid content of the adhesive layer contains 0.1 to 5% by weight of component (C).

Description

Technical Field

[0001] The present invention relates to an adhesive tape for protecting the surface of a photomask used in close contact with a photosensitive resin having adhesiveness in the process of manufacturing a resin relief plate.

Background Art

[0002] Generally, when forming a resin relief plate, there is a step of irradiating light from above with a photomask (exposure original) in close contact with a liquid photosensitive resin that is cured by ionizing radiation to cure the liquid photosensitive resin. In this step, if the photomask is directly brought into close contact with the liquid photosensitive resin, when peeling off the liquid photosensitive resin after the exposure is completed, the adhesiveness between the liquid photosensitive resin and the surface of the photomask may be too high to be peeled off. Therefore, conventionally, a protective adhesive tape having an adhesive layer provided on one side of a base film and a release layer provided on the other side to prevent adhesion of the liquid photosensitive resin is attached to the surface of the photoresist of the liquid photosensitive resin to ensure the releasability between the photomask and the liquid photosensitive resin. Such an adhesive layer of the protective adhesive tape is generally composed of an acrylic resin excellent in transparency and durability.

[0003] The pattern of the printing plate is imprinted on the surface of the photomask. Since the photomask is a silver halide film, silver crystals are clustered along the pattern, creating convex areas where they are clustered and concave areas where they are not. To transfer the pattern of the printing plate clearly, the protective adhesive tape needs to be as thin as possible. If it is too thick, the exposure spreads out, causing the pattern to blur. On the other hand, if the protective adhesive tape is too thin, air bubbles are more likely to get trapped when the tape is attached to the photomask. During exposure, these bubbles act as lenses, causing scattering and reducing resolution, which can prevent the pattern of the printing plate from being transferred clearly. Also, if foreign matter gets trapped during attachment, and it is small, the area containing the foreign matter is pressed with a fingernail or spatula to crush the surrounding air bubbles (repair). While thicker protective adhesive tape makes repairs easier, it suffers from the aforementioned problem of reduced resolution during exposure. Conversely, thin protective adhesive tape makes repairs difficult.

[0004] Patent Document 1 discloses a photomask protective adhesive tape having an adhesive layer that leaves little adhesive residue when peeled off from a photomask, and that minimizes air bubble entrapment when applied to photomasks with complex patterns, small dots, thin lines, and closely spaced lines, in which the adhesive layer consists of a specific acrylic acid ester resin and a crosslinking agent, and the tensile shear displacement of the adhesive layer is within a specific range. Patent Document 2 discloses a surface protective adhesive sheet having an adhesive layer made of an adhesive composition containing a specific acrylic acid ester resin. Patent Document 3 discloses a surface protective adhesive sheet using an adhesive in which the adhesive layer consists of a specific acrylic acid ester resin and a crosslinking agent, and the gel fraction is within a specific range.

[0005] However, when used in photomasks for manufacturing resin relief plates for liquid crystal alignment films, where high-resolution thin-film printing is required, even tiny bubbles can cause a decrease in resolution during exposure, and none of the adhesive tapes for protecting photomasks described in the aforementioned patent documents were entirely satisfactory. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-116170 [Patent Document 2] Japanese Patent Publication No. 2010-189605 [Patent Document 3] WO2009 / 37990 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This invention has been made in view of the above circumstances, and aims to provide an adhesive tape for protecting photomasks used in resin relief printing, which prevents air bubbles from forming when attached to the photomask even when it is a thin film, and facilitates repair work in the event of foreign matter contamination. [Means for solving the problem]

[0008] The first invention is a photomask protective adhesive tape comprising a transparent base film with an adhesive layer on one side and a release layer on the other side, wherein the adhesive layer is a cured product of an adhesive layer composition containing the following components (A) to (C), and the solid content of the adhesive layer contains 0.1 to 5% by weight of component (C). (A) Acrylate ester polymer (B) Crosslinking agent (C) Oil containing trimethylolpropane fatty acid triester

[0009] The second invention is an adhesive tape for protecting a photomask according to the first invention, characterized in that the thickness of the adhesive layer is 3 to 9 μm.

[0010] The third invention is an adhesive tape for protecting photomasks according to the first or second invention, characterized in that component (B) contains both a metal chelating crosslinking agent and an isocyanate crosslinking agent.

[0011] The fourth invention is an adhesive tape for protecting a photomask according to the third invention, characterized in that the component (A) is 2-ethylhexyl acrylate and is contained in the solid content of the adhesive layer at a concentration of 90% by weight or more. [Effects of the Invention]

[0012] In this invention, we have made it possible to provide an adhesive tape for protecting photomasks used in resin relief printing, which has an adhesive layer on one side of a transparent base film and a release layer on the other side, that prevents air bubbles from forming when the tape is applied to the photomask even when it is a thin film, and allows for easy repair work in the event of foreign matter contamination. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view showing one embodiment of the adhesive tape for protecting photomasks according to the present invention. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below.

[0015] Figure 1 shows a schematic cross-sectional view of an embodiment of the adhesive tape for protecting photomasks according to the present invention. The adhesive tape 10 for protecting photomasks according to the present invention has a structure in which at least an adhesive layer 11 is provided on one surface of a base film 12, and a release layer 13 is provided on the other surface of the base film 12. The adhesive layer 11 is provided in a state in which a separator film 14, which is a polyester resin film that has been subjected to a silicone release treatment or the like, is laminated. The adhesive tape 10 for protecting photomasks according to the present invention may have an anchor layer or the like provided between the base film 12 and the adhesive layer 11, and between the base film 12 and the release layer 13. When the adhesive tape 10 for protecting photomasks is used, the separator film 14 is peeled off, and it becomes in the form of adhesive layer 11 / base film 12 / release layer 13.

[0016] <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. 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.

[0017] The base film may be subjected to surface treatment. Examples of the surface treatment include corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, primer treatment, and the like.

[0018] From the viewpoint of handleability and the like, 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. 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.

[0019] <Adhesive layer> The adhesive layer of the photomask protection adhesive tape is attached to the surface of the photomask. From the viewpoint of transparency, it is preferable to use an acrylic adhesive. The adhesive layer used in the present invention is composed of a cured product of an adhesive layer composition containing (A) an acrylate polymer (hereinafter referred to as component (A)) as a resin component, (B) a crosslinking agent (hereinafter referred to as component (B)) as a curing agent component, and (C) an oil containing trimethylolpropane fatty acid triester (hereinafter referred to as component (C)) as a flexibility improving component, and contains 0.1 to 5% by weight of component (C) in the solid content of the adhesive layer. By using an adhesive layer having this configuration, it is possible to obtain a photomask protection adhesive tape for resin relief printing plate formation that does not allow air bubbles to enter when attached to a photomask even with a thin film and enables easy repair work in the case of foreign matter contamination.

[0020] <Component (A): Acrylate polymer> Component (A) used in the adhesive layer of the present invention preferably mainly comprises an acrylic polymer composed of a copolymer of an alkyl (meth)acrylate monomer and a functional group-containing monomer. In the present invention, (meth)acrylic means acrylic and / or methacrylic.

[0021] As the alkyl (meth)acrylate monomer, the number of carbon atoms in the alkyl group is 1 to 20, preferably 4 to 12, more preferably 4 to 8. For example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, stearyl (meth)acrylate, etc. can be mentioned. It can be used alone or in combination of two or more. Among these, butyl acrylate and 2-ethylhexyl acrylate are preferable in terms of low glass transition temperature and viscoelasticity, and 2-ethylhexyl acrylate is particularly preferable. Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, an acetoacetyl group-containing monomer, etc. Among these, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferable in terms of enabling an efficient crosslinking reaction. For example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, (meth)acrylic acid, itaconic acid, fumaric acid, etc. can be mentioned. It can be used alone or in combination of two or more. There is no particular limitation on the polymerization method, and it can be obtained by a known method such as radical copolymerization.

[0022] Component (A), which consists of a copolymer of the (meth)acrylate alkyl ester monomer and a functional group-containing monomer, preferably has a weight-average molecular weight of 100,000 to 1,000,000, more preferably 200,000 to 800,000. If the weight-average molecular weight is less than 100,000, the adhesive strength becomes high, making it difficult to peel off the photomask. If the weight-average molecular weight exceeds 1,000,000, the solution viscosity becomes high, causing problems such as difficulty in obtaining a smooth adhesive layer during coating. The weight-average molecular weight is the polystyrene equivalent value measured by gel permeation chromatography (GPC). Furthermore, the glass transition temperature (Tg) of component (A) is preferably -20°C or lower. If the Tg is higher than -20°C, the adhesive hardens, and adequate adhesive strength to the photomask cannot be obtained.

[0023] Component (A) is the main component of the adhesive layer of the present invention, and it is preferable that it be contained in the solid content of the adhesive layer at a concentration of 90% by weight or more.

[0024] <Component (B): Crosslinking agent> The adhesive layer of the present invention contains a component (B): a crosslinking agent that can react with the functional groups derived from the functional group-containing monomer of component (A). By forming a partially crosslinked structure within the acrylic polymer, the cohesive force of the adhesive is enhanced, making it less likely for adhesive residue to remain when the adhesive tape is peeled off. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents. In particular, in the present invention, it is more preferable to use an isocyanate-based crosslinking agent and a metal chelate-based crosslinking agent in combination. When only an isocyanate-based crosslinking agent is used, the crosslinking strength is strong and flexibility is insufficient, which tends to lead to the entrapment of air bubbles when bonding with a photomask, reduced performance in removing air bubbles during repair work, and difficulty in ensuring adhesion between the adhesive layer and the base film. When only a metal chelate-based crosslinking agent is used, the crosslinking strength of the adhesive layer tends to be weak due to the ionic bonding properties unique to metal chelate crosslinking, resulting in reduced adhesive residue performance.

[0025] Examples of isocyanate-based crosslinking agents include compounds having two or more isocyanate groups in one molecule, such as aromatic polyisocyanates like tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; alicyclic polyisocyanates like cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, and hydrogenated xylylene diisocyanate; and aliphatic polyisocyanates like hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. Adducts, biuretes, 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 cohesive strength of the adhesive layer, it is preferable to use the adduct or isocyanurate of polyisocyanate, and particularly preferable to use the isocyanurate of tolylene diisocyanate.

[0026] Examples of metal chelating crosslinking agents include those in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Among these, Al (aluminum) and Ti (titanium) are preferred, with Al (aluminum) being particularly preferred. Examples of atoms in the organic compound that form covalent or coordinate bonds include oxygen atoms, and examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds. Specifically, aluminum tris(acetylacetonate), which is particularly stable and easy to handle, is preferably used. Furthermore, metal chelating crosslinking agents may be used alone or in combination of two or more types.

[0027] From the viewpoint of adhesive strength and cohesive force of the adhesive layer, the amount of isocyanate-based crosslinking agent is preferably 0.1 to 5 parts by weight in the solid content of the adhesive layer, and the amount of metal chelate-based crosslinking agent is preferably 0.1 to 5 parts by weight in the solid content of the adhesive layer.

[0028] <Ingredients (C): Oil containing trimethylolpropane fatty acid triester> The adhesive layer of the present invention contains a plasticizer. The inclusion of a plasticizer provides good flexibility to the adhesive layer, and the reduced surface energy of the adhesive layer improves air release properties. This allows it to follow the surface irregularities when applied to a photomask for resin relief printing, preventing air bubbles from being trapped. Furthermore, if foreign matter is present, the air bubbles can be removed from the adhesive layer by repair work using a fingernail or spatula.

[0029] Examples of plasticizers include hydrocarbon plasticizers, such as process oils, liquid polybutadiene, liquid polyisobutylene, liquid polyisoprene, liquid paraffin, paraffin wax, copolymer oligomers of ethylene and α-olefins (Mw 5,000-100,000), copolymer oligomers of propylene and α-olefins excluding ethylene (Mw 5,000-100,000); ester plasticizers, such as phthalate esters (diethyl phthalate, dibutyl phthalate, dioctyl phthalate, didecyl phthalate, dilauryl phthalate, distearyl phthalate, diisononyl phthalate, etc.), and adipate esters (dioctyl adipate, diisononyl adipate). Examples include: esters (dibutyl sebacate, dioctyl sebacate, etc.), trimethylolpropane fatty acid triesters (trimethylolpropane laurate triester, trimethylolpropane laurate stearic acid mixed triester, trimethylolpropane isostearate triester, trimethylolpropane capric acid triester, trimethylolpropane-2-ethylhexanoate triester, etc.); animal and vegetable oils and fats (e.g., linoleic acid, linolenic acid), and, among these, hydrogenated versions thereof of those having hydrogenable unsaturated double bonds. These may be used alone or in combination of two or more. Among these, ester-based plasticizers are preferred, and oils having component (C): trimethylolpropane fatty acid triester, which is a polyhydric alcohol fatty acid ester, are more preferred because they have low viscosity and good fluidity, and it is easy to obtain a good balance between the flexibility, air release and adhesive strength of the adhesive layer. Furthermore, having a moderately long carbon chain improves the flexibility and air release properties of the adhesive layer, so among the trimethylolpropane fatty acid triesters, those with 8 to 18 carbon atoms in the fatty acid are particularly preferred.

[0030] The amount of component (C) is 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, in the solid content of the adhesive layer. If the amount of (C) is less than 0.05 parts by weight, it is difficult to obtain flexibility and good air release properties in the adhesive layer, the effect of following the irregularities on the surface of the photomask decreases, and as a result the effect of preventing air bubbles from being incorporated decreases. On the other hand, if the amount of (C) exceeds 10 parts by weight, there is a problem that the adhesive strength decreases due to a decrease in cohesive force.

[0031] 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.

[0032] 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.

[0033] The adhesive layer of the present invention may contain various additives as needed, such as antioxidants, antistatic agents, leveling agents, and defoaming agents.

[0034] 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 9 μm, from the viewpoint of adhesive strength, surface conformability, and transparency.

[0035] 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.

[0036] 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.

[0037] <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.

[0038] <Release layer> The adhesive tape for protecting photomasks of the present invention has a release layer on the side opposite to the adhesive layer. The release layer is not particularly limited as long as it has release properties, and examples include a mixture of a resin and a silicone-based release agent, or a silicone-based resin. In particular, it is preferable to use a release layer composed of (1) a cured product of a release layer composition consisting of a resin having a ladder-type polysilsesquioxane structure and a polyisocyanate, or (2) a cured product of a release layer composition containing (A) a hydroxyl group-containing acrylic polymer, (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, and (C) a silicone-grafted acrylic polymer. Furthermore, an antistatic agent may be added to the release layer to provide an antistatic function.

[0039] The thickness of the release layer is preferably in the range of 0.05 to 2.0 μm, from the viewpoint of ensuring functions such as uniformity of the coating film, release properties, scratch resistance, and no decrease in the resolution of the pattern shape formed on the photosensitive resin during exposure.

[0040] 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 base film to a predetermined thickness, and the coating film is formed by heating and drying.

[0041] 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. [Examples]

[0042] 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 proportions of each material are indicated in parts, it refers to parts by weight unless otherwise specified.

[0043] (Example 1) <Preparation of adhesive tape for protecting photomasks> (Adhesive layer) An adhesive layer coating liquid 1, prepared by kneading materials according to the following formulation, was applied to the silicone release surface of a 25 μm thick separator film (Therapyel® WZ, manufactured by Toray Industries, Inc.) so that the thickness after drying was 6 μm. The adhesive layer was then formed by heating and drying at 120°C for 2 minutes. A 6 μm thick PET (polyethylene terephthalate) film and the adhesive layer surface were laminated using a laminator to obtain an adhesive layer laminated film with the configuration of PET film / adhesive layer / separator. [Adhesive layer coating liquid 1] Acrylic acid ester polymer 55.79 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Isocyanate crosslinking agent 0.50 parts (Manufactured by Mitsui Chemicals, Inc., isocyanurate of TDI-based polyisocyanate, isocyanate group content 7.5%, solids content 50%) Metal chelate crosslinking agent 1.14 parts (Manufactured by Fujikura Chemical Co., Ltd., aluminum acetylacetonate, solids content 10%) 0.02 parts of oil containing trimethylolpropane fatty acid triester (Manufactured by NOF Corporation, Trimethylolpropane Lauric Acid Stearic Acid Mixture Tryester, 100% Solids) Ethyl acetate 42.55 parts (Release layer) A release layer coating liquid 1, prepared by kneading materials according to the following formulation, was applied to the surface of the aforementioned adhesive layer laminated film opposite to the surface where the adhesive layer of the PET film was bonded, so that the thickness after drying was 0.6 μm. The film was then heated and dried at 100°C for 1 minute to obtain a photomask protective adhesive tape having the structure of release layer / PET film / adhesive layer / separator. [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 (NCO%: 21%, Solids content 100%) MEK 89.79 parts

[0044] (Example 2) An adhesive tape for protecting a photomask of Example 2 was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid was changed to adhesive layer coating liquid 2, which was prepared by kneading the materials according to the formulation below. [Adhesive layer coating liquid 2] Acrylic acid ester polymer 54.14 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Isocyanate crosslinking agent 0.50 parts (Manufactured by Mitsui Chemicals, Inc., isocyanurate of TDI-based polyisocyanate, isocyanate group content 7.5%, solids content 50%) Metal chelate crosslinking agent 1.14 parts (Manufactured by Fujikura Chemical Co., Ltd., aluminum acetylacetonate, solids content 10%) 0.68 parts of oil containing trimethylolpropane fatty acid triester (Manufactured by NOF Corporation, Trimethylolpropane Lauric Acid Stearic Acid Mixture Tryester, 100% Solids) 43.54 parts of ethyl acetate

[0045] (Example 3) An adhesive tape for protecting a photomask of Example 3 was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid was changed to adhesive layer coating liquid 3, which was prepared by kneading the materials of the following formulation. [Adhesive layer coating liquid 3] Acrylic ester polymer 53.00 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Isocyanate crosslinking agent 0.50 parts (Manufactured by Mitsui Chemicals, Inc., isocyanurate of TDI-based polyisocyanate, isocyanate group content 7.5%, solids content 50%) Metal chelate crosslinking agent 1.14 parts (Manufactured by Fujikura Chemical Co., Ltd., aluminum acetylacetonate, solids content 10%) 1.14 parts of oil containing trimethylolpropane fatty acid triester (Manufactured by NOF Corporation, Trimethylolpropane Lauric Acid Stearic Acid Mixture Tryester, 100% Solids) Ethyl acetate 44.22 parts

[0046] (Example 4) An adhesive tape for protecting a photomask of Example 4 was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid was changed to adhesive layer coating liquid 4, which was prepared by kneading the materials of the following formulation. [Adhesive layer coating liquid 4] Acrylic acid ester polymer 54.37 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Isocyanate crosslinking agent 0.50 parts (Manufactured by Mitsui Chemicals, Inc., isocyanurate of TDI-based polyisocyanate, isocyanate group content 7.5%, solids content 50%) Metal chelate crosslinking agent 0.23 parts (Manufactured by Fujikura Chemical Co., Ltd., aluminum acetylacetonate, solids content 10%) 0.68 parts of oil containing trimethylolpropane fatty acid triester (Manufactured by NOF Corporation, Trimethylolpropane Lauric Acid Stearic Acid Mixture Tryester, 100% Solids) Ethyl acetate 44.22 parts

[0047] (Example 5) An adhesive tape for protecting a photomask of Example 5 was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid was changed to adhesive layer coating liquid 5, which was prepared by kneading the materials of the following formulation. [Adhesive layer coating liquid 5] Acrylic acid ester polymer 53.52 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Isocyanate crosslinking agent 0.50 parts (Manufactured by Mitsui Chemicals, Inc., isocyanurate of TDI-based polyisocyanate, isocyanate group content 7.5%, solids content 50%) Metal chelate crosslinking agent 3.63 parts (Manufactured by Fujikura Chemical Co., Ltd., aluminum acetylacetonate, solids content 10%) 0.68 parts of oil containing trimethylolpropane fatty acid triester (Manufactured by NOF Corporation, Trimethylolpropane Lauric Acid Stearic Acid Mixture Tryester, 100% Solids) 41.67 parts ethyl acetate

[0048] (Example 6) The adhesive tape for protecting the photomask of Example 6 was obtained in the same manner as in Example 2, except that the thickness of the adhesive layer after drying was changed to 3 μm.

[0049] (Example 7) The adhesive tape for protecting the photomask of Example 7 was obtained in the same manner as in Example 2, except that the thickness of the adhesive layer after drying was changed to 9 μm.

[0050] (Example 8) An adhesive tape for protecting a photomask of Example 8 was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid was changed to adhesive layer coating liquid 6, which was prepared by kneading the materials of the following formulation. [Adhesive layer coating liquid 6] Acrylic acid ester polymer 54.76 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Metal chelate crosslinking agent 1.14 parts (Manufactured by Fujikura Chemical Co., Ltd., aluminum acetylacetonate, solids content 10%) 0.68 parts of oil containing trimethylolpropane fatty acid triester (Manufactured by NOF Corporation, Trimethylolpropane Lauric Acid Stearic Acid Mixture Tryester, 100% Solids) 43.42 parts of ethyl acetate

[0051] (Example 9) An adhesive tape for protecting a photomask of Example 9 was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid was changed to adhesive layer coating liquid 7, which was prepared by kneading the materials of the following formulation. [Adhesive layer coating liquid 7] Acrylic acid ester polymer 54.42 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Isocyanate crosslinking agent 0.50 parts (Manufactured by Mitsui Chemicals, Inc., isocyanurate of TDI-based polyisocyanate, isocyanate group content 7.5%, solids content 50%) 0.68 parts of oil containing trimethylolpropane fatty acid triester (Manufactured by NOF Corporation, Trimethylolpropane Lauric Acid Stearic Acid Mixture Tryester, 100% Solids) 44.40 parts of ethyl acetate

[0052] (Comparative Example 1) Comparative Example 1, a photomask protective adhesive tape, was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid was changed to adhesive layer coating liquid 8, which was prepared by kneading the materials according to the formulation below. [Adhesive layer coating liquid 8] Acrylic acid ester polymer 55.84 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Isocyanate crosslinking agent 0.50 parts (Manufactured by Mitsui Chemicals, Inc., isocyanurate of TDI-based polyisocyanate, isocyanate group content 7.5%, solids content 50%) Metal chelate crosslinking agent 1.14 parts (Manufactured by Fujikura Chemical Co., Ltd., aluminum acetylacetonate, solids content 10%) Ethyl acetate 42.52 parts

[0053] (Comparative Example 2) Comparative Example 2, a photomask protective adhesive tape, was obtained in the same manner as in Example 1, except that the adhesive layer coating liquid was changed to adhesive layer coating liquid 9, which was prepared by kneading the materials according to the following formulation. [Adhesive layer coating liquid 9] Acrylic acid ester polymer 50.17 parts (Manufactured by Fujikura Chemical Co., Ltd., weight-average molecular weight 650,000, glass transition temperature -66°C, hydroxyl value of solids 2.25 mg KOH / g, solids content 40%) Isocyanate crosslinking agent 0.50 parts (Manufactured by Mitsui Chemicals, Inc., isocyanurate of TDI-based polyisocyanate, isocyanate group content 7.5%, solids content 50%) Metal chelate crosslinking agent 1.14 parts (Manufactured by Fujikura Chemical Co., Ltd., aluminum acetylacetonate, solids content 10%) 2.27 parts of oil containing trimethylolpropane fatty acid triester (Manufactured by NOF Corporation, Trimethylolpropane Lauric Acid Stearic Acid Mixture Tryester, 100% Solids) 45.93 parts of ethyl acetate

[0054] (evaluation) The adhesive tapes for protecting photomasks prepared in each example and comparative example were evaluated as follows. Unless otherwise specified, the evaluations were performed under conditions of 23±2°C and 50±5%RH.

[0055] (1) Adhesive strength <Evaluation of peeling force on photomasks> For each example and comparative example of the adhesive tape used to protect the photomask, the separator on the adhesive layer was peeled off, and the adhesive layer was pressed onto the photomask twice using a 2kgf rubber roller to prepare evaluation samples. After the evaluation samples were left to stand for 30 minutes, samples measuring 25mm wide x 60mm long were cut out, and the peeling force when peeling the adhesive tape from the photomask was measured using a tensile testing machine at a peeling angle of 180° and a peeling speed of 300mm / min. The samples were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ◎: 1500mN / 25mm or more, and less than 2000mN / 25mm. ○: 1000mN / 25mm or more, less than 1500mN / 25mm, or 2000mN / 25mm or more, less than 2500mN / 25mm. ×: Less than 1000 mN / 25 mm, or 2500 mN / 25 mm or more.

[0056] (2) Air release properties <Evaluation of resistance to air bubbles during bonding> Double-sided tape was attached to a glass plate, and the adhesive tape for protecting the photomask of each example and comparative example was then attached on top of the tape with the adhesive layer facing upwards to prepare an evaluation sample. Next, a 100 μm thick PET film was prepared, cut to a size of 25 mm wide x 50 mm long. Only 2 mm of one end of the 50 mm length was attached to the adhesive layer of the evaluation sample. The other end of the PET film was then lifted to a position where the adhesive layer of the PET film and the evaluation sample were perpendicular, and then released. The time it took for the PET film to adhere to the adhesive layer of the evaluation sample was measured and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ◎: Sticks in less than 1 minute 30 seconds with over 90% effectiveness. ○: Sticks for 90% or more of the time between 1 minute 30 seconds and 3 minutes. ×: Less than 90% sticks even after more than 3 minutes.

[0057] (3) Repairability <Evaluation of whether air bubbles can be removed by crushing them> For each example and comparative example, the separator on the adhesive tape used to protect the photomask was peeled off, and the tape was applied to the photomask intentionally to create air bubbles. Evaluation samples were prepared, and the size of the air bubbles immediately after application was checked using an optical microscope. Immediately afterward, the air bubbles were removed by pressing them down with a fingernail. The state of the air bubbles in the evaluation samples was then observed and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ◎: Can crush bubbles with a size of 20 μm or more but less than 50 μm. ○: Can crush bubbles smaller than 20 μm in size. ×: It cannot pop bubbles smaller than 20 μm.

[0058] (4) Peelability evaluation <Evaluation of adhesive residue and ease of removal> For each example and comparative example of the adhesive tape for protecting the photomask, the separator on the adhesive layer surface was peeled off, and the adhesive layer surface was pressed twice back and forth with a 2kgf rubber roller to attach it to a 100μm thick PET film. A sample measuring 25mm wide x 100mm long was cut out to prepare an evaluation sample. Immediately afterward, the adhesive tape for protecting the photomask was peeled off from the PET film to a distance of approximately 50mm at a peeling angle of 180° and a peeling speed of 10m / min, and then stopped. The adhesive layer surface of the photomask protective adhesive tape that had been peeled off was then pressed again with a 2kgf rubber roller twice back and forth to return it to its pre-peeling state. Immediately afterward, the adhesive tape for protecting the photomask was completely peeled off from the PET film at a peeling angle of 180° and a peeling speed of 10m / min. The peeling process and the surface condition of the PET film were observed visually and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. (Evaluation Criteria) ◎: Leaves no adhesive residue and peels off smoothly. ○: There is no adhesive residue, but the peeling sound is loud and it lacks a bit of smoothness. ×: There is glue residue.

[0059] (Table 1) TIFF2026111086000002.tif91169 [Explanation of Symbols]

[0060] 10: Adhesive tape for protecting photomasks 11: Adhesive layer 12: Base film 13: Release layer 14: Separator film

Claims

1. A photomask protective adhesive tape comprising a transparent base film with an adhesive layer on one side and a release layer on the other side, wherein the adhesive layer is a cured product of an adhesive layer composition containing the following components (A) to (C), and the solid content of the adhesive layer contains 0.1 to 5% by weight of component (C). (A) Acrylic ester polymers (B) Crosslinking agent (C) Oil containing trimethylolpropane fatty acid triesters

2. The adhesive tape for protecting photomasks according to claim 1, characterized in that the thickness of the adhesive layer is 3 to 9 μm.

3. The adhesive tape for protecting photomasks according to claim 1 or 2, characterized in that the component (B) contains both a metal chelating crosslinking agent and an isocyanate crosslinking agent.

4. The adhesive tape for protecting photomasks according to claim 3, characterized in that the component (A) is 2-ethylhexyl acrylate and is contained in the solid content of the adhesive layer in an amount of 90% by weight or more.

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