Release sheet

Abstract

[Problem] To provide a release sheet which has a low peeling force at normal temperature, can suppress a decrease in residual adhesion rate, exhibits good release properties even after a high temperature heating step, and exhibits excellent release agent layer strength. [Solution] Provided is a release sheet that is characterized by: having a substrate sheet and a release agent layer formed on at least one surface of the substrate sheet; the release agent layer being formed from an aminoalkyd resin composition containing a (meth)acrylic block copolymer; and the (meth)acrylic block copolymer having a block A having a structural unit (a-1) represented by general formula (1) and a block B having a structural unit (b-1) derived from a (meth)acrylic monomer having a reactive functional group. [In formula (1), R11 denotes an alkyl group having 12-28 carbon atoms. R12 denotes a hydrogen atom or a methyl group.]

Description

[Technical Field]

[0001] The present invention relates to a release sheet. [Background technology]

[0002] Electronic components such as semiconductors, various connectors, capacitors, resistors, and printed wiring boards are widely used in a variety of products. During the assembly process of these components, adhesive tapes and sheet adhesives are used to bond or temporarily fasten the components together. It is common for adhesive tapes and sheet adhesives to have a release sheet placed on the adhesive or adhesive surface to protect it during storage.

[0003] Such release sheets are subjected to a release treatment on the surface that comes into contact with the pressure-sensitive adhesive or adhesive to facilitate release from the pressure-sensitive adhesive or adhesive. For the release treatment, a silicone-based, fluorine-based, long-chain alkyl-based, wax-based, polyolefin-based or other release agent is used.

[0004] However, because silicone-based release agents tend to transfer their silicone components to the object being released, when they are used to bond electronic components or temporarily fasten electronic components during the manufacturing process, they can easily cause malfunctions in the electronic components. For this reason, it has been proposed to use non-silicone release agents (release agents that do not contain silicone compounds), such as polyolefin-based release agents and long-chain alkyl-based release agents, for such applications.

[0005] For example, Patent Document 1 discloses a method of using a non-silicone release agent as a release treatment agent for release paper in a packaging structure for semiconductor chips in which the semiconductor chips are sandwiched between adhesive tape and release paper for packaging (see Patent Document 1 (Claim 1, paragraph 0021)). Also, Patent Document 2 discloses an adhesive film with a separator used for flexible printed wiring boards, in which an alkyd resin-based release agent is used as a separator release agent (see Patent Document 2 (Claim 1, paragraph 0009)). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-196657 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-73971 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, a method has become popular for forming an interphase insulating film on a printed wiring board, in which a sheet-like adhesive is formed on a release sheet and then transferred to an adherend such as a printed wiring board by heat pressing. Furthermore, as the boiling points of the solvents used in the sheet-like adhesive formation process have increased, the drying temperature for removing the solvent has also increased. Furthermore, solder reflow heating following the heat pressing process is sometimes performed with the release sheet still attached. Therefore, the release sheet is required to have heat resistance that allows it to maintain a low peel force even when exposed to a high-temperature atmosphere.

[0008] However, no consideration has been given to the heat resistance of conventional non-silicone release sheets, and as a result, conventional non-silicone release sheets have the problem that when exposed to a high-temperature atmosphere while in contact with a pressure-sensitive adhesive or adhesive, the release force increases, making it difficult to peel the sheet from the pressure-sensitive adhesive or adhesive.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a release sheet which has a small peel force at room temperature, can suppress a decrease in the residual adhesion rate, has good releasability even after undergoing a high-temperature heating step, and has an excellent strength of the release agent layer. [Means for solving the problem]

[0010] The release sheet of the present invention, which has been able to solve the above-mentioned problems, comprises a base sheet and a release agent layer formed on at least one surface of the base sheet, wherein the release agent layer is formed from an aminoalkyd resin composition containing a (meth)acrylic block copolymer, and the (meth)acrylic block copolymer is a block copolymer having an A block having a structural unit (a-1) represented by general formula (1) and a B block having a structural unit (b-1) derived from a (meth)acrylic monomer having a reactive functional group.

[0011] [ka] [In formula (1), R 11 represents an alkyl group having 12 to 28 carbon atoms. 12 represents a hydrogen atom or a methyl group. [Effects of the Invention]

[0012] The release sheet of the present invention has a small peeling force at room temperature, can suppress a decrease in residual adhesion rate, has good releasability even after undergoing a high-temperature heating process, and has excellent strength of the release agent layer. DETAILED DESCRIPTION OF THE INVENTION

[0013] The release sheet according to the present invention comprises a substrate sheet and a release agent layer formed on at least one surface of the substrate sheet. The release agent layer is formed from an aminoalkyd resin composition containing a (meth)acrylic block copolymer. The (meth)acrylic block copolymer is a block copolymer having an A block having a structural unit (a-1) represented by general formula (1) and a B block having a structural unit (b-1) derived from a (meth)acrylic monomer having a reactive functional group. The release agent layer of the release sheet exhibits good releasability even after a heating step (e.g., heating at 100°C or higher), the components of the release agent layer are less likely to migrate to the adherend, and the strength of the release agent layer is excellent. Furthermore, the release sheet according to the present invention has a release agent layer that is substantially free of silicone compounds, thereby suppressing defects that occur in electronic components and in the manufacturing process of electronic components.

[0014] In the present invention, "vinyl monomer" refers to a monomer having a radically polymerizable carbon-carbon double bond in the molecule. "Structural unit derived from vinyl monomer" refers to a structural unit in which the radically polymerizable carbon-carbon double bond of a vinyl monomer is polymerized to form a carbon-carbon single bond. "(Meth)acrylic" refers to "at least one of acrylic and methacrylic". "(Meth)acrylate" refers to "at least one of acrylate and methacrylate".

[0015] The present invention will be described in detail below.

[0016] <Release sheet> The release sheet of the present invention has a base sheet and a release agent layer formed on at least one surface of the base sheet, and the release agent layer is formed from an aminoalkyd resin composition containing a (meth)acrylic block copolymer.

[0017] The aminoalkyd resin composition contains constituent components of an aminoalkyd resin and a (meth)acrylic block copolymer (hereinafter, may be simply referred to as "block copolymer").

[0018] (a component of amino alkyd resin) The aminoalkyd resin components contained in the aminoalkyd resin composition are components that constitute the aminoalkyd resin when the aminoalkyd resin composition is applied and cured. Specific examples include alkyd resins and amino resins. Furthermore, a prepolymerized aminoalkyd resin may also be used as the aminoalkyd resin component.

[0019] The alkyd resin is a condensation product of a polybasic acid and a polyhydric alcohol. The alkyd resin may be a condensation product of a polybasic acid and a polyhydric alcohol that has been modified with a modifying agent such as a fatty oil or a fatty acid.

[0020] Examples of the polybasic acid include saturated polybasic acids such as phthalic anhydride, terephthalic acid, succinic acid, adipic acid, and sebacic acid; unsaturated polybasic acids such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, and citraconic anhydride; and other polybasic acids such as cyclopentadiene-maleic anhydride adduct, terpene-maleic anhydride adduct, and rosin-maleic anhydride adduct. The polybasic acids may be used singly or in combination of two or more.

[0021] Examples of the polyhydric alcohol include dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, and neopentyl glycol; trihydric alcohols such as glycerin, trimethylolethane, and trimethylolpropane; and tetrahydric or higher polyhydric alcohols such as diglycerin, triglycerin, pentaerythritol, pentaerythritol, dipentaerythritol, mannitol, and sorbitol. One type of the polyhydric alcohol may be used alone, or two or more types may be used in combination.

[0022] Examples of the denaturing agent include fatty oils such as soybean oil, linseed oil, tung oil, castor oil, dehydrated castor oil, and coconut oil, and their fatty acids; fats and oil fatty acids such as stearic acid, oleic acid, linoleic acid, linolenic acid, eleostearic acid, ricinoleic acid, and dehydrated ricinoleic acid; natural resins such as rosin, kovar, amber, and shellac; and synthetic resins such as ester gum, phenolic resin, urea resin, and melamine resin. The denaturing agents may be used alone or in combination of two or more.

[0023] The alkyd resin preferably has a long-chain alkyl group, which preferably has 12 or more carbon atoms, more preferably 14 or more carbon atoms, and even more preferably 16 or more carbon atoms, from the viewpoint of releasability from the adherend. Furthermore, from the viewpoint of availability and handling of raw materials, the long-chain alkyl group preferably has 28 or less carbon atoms, more preferably 26 or less carbon atoms, and even more preferably 22 or less carbon atoms.

[0024] The alkyd resin preferably has an acid value of 2 mgKOH / g to 30 mgKOH / g, preferably 4 mgKOH / g to 25 mgKOH / g, and more preferably 6 mgKOH / g to 12 mgKOH / g. The alkyd resin also has a hydroxyl value of 50 mgKOH / g to 300 mgKOH / g, preferably 80 mgKOH / g to 270 mgKOH / g, and more preferably 100 mgKOH / g to 250 mgKOH / g. By setting the acid value and hydroxyl value within these ranges, a cured product with excellent heat resistance and strength can be obtained.

[0025] The amino resin is a resin obtained by a condensation reaction between a compound containing an amino group and an aldehyde. Examples of the amino resin include aniline aldehyde resin, urea resin, and melamine resin, and melamine resin is preferred. The amino resin has an N-methylol group and / or an N-alkoxymethylol group.

[0026] Melamine resin is a general term for compounds in which the amino group of melamine has been modified in various ways, including those in which multiple triazine rings are condensed. As for the type of modification, a methylolated melamine compound in which at least one hydrogen atom of the three amino groups has been methylolated is preferred, and further, an alkyl-etherified melamine compound in which the methylol groups of the methylolated melamine compound have been partially or completely etherified with a lower alcohol having 1 to 4 carbon atoms is preferred.

[0027] The aminoalkyd resin may be a commercially available product, such as Tesfine (registered trademark) 303, 305, or 314 manufactured by Hitachi Chemical Co., Ltd.

[0028] Furthermore, an amino resin may be further added to the amino alkyd resin component. Examples of commercially available amino resins include Nikalac (registered trademark) MW-30M, Nikalac MW-30, Nikalac MW-22, Nikalac MS-11, Nikalac MS-001, Nikalac MX-730, Nikalac MX-750, Nikalac MX-708, Nikalac MX-706, Nikalac MX-035, Nikalac MW-30LF, Nikalac MW-30MLF, Nikalac MW-33LF, and Nikalac MX-035 manufactured by Sanwa Chemical Co., Ltd. Rack MZ-351, Nikalac N-0503, Nikalac N-0504; DIC's Amidea (registered trademark) J-820-60, Amidea L-109-65, Amidea L-117-60, Amidea L-125-60, Amidea L-127-60, Amidea L-150-60, Amidea L-166-608, Amidea L-166-608; Changxing Materials Industries' ETERMINO 9211-60-5, ETERMINO 9212-70, ETERMINO 9215-70, ETERMINO 9216-60-1, ETERMINO 9223-60, ETERMINO 9224-60, ETERMINO 9226-60, ETERMINO 9229-60; U-BAN (registered trademark) 10S60, U-BAN 10R, U-BAN 20SB, U-BAN 20SE60, U-BAN 21R, U-BAN 22R, U-BAN 122, U-BAN 125, U-BAN 128, U-BAN 220, U-BAN 225, U-BAN 228, U-BAN 28-60, U-BAN 2020, U-BAN 132, U-BAN 60R, U-BAN 62, U-BAN 62E, U-BAN 360, U-BAN 165, U-BAN 166-60, U-BAN 169, U-BAN 2061, U-BAN 80S, etc. manufactured by Mitsui Chemicals.

[0029] ((Meth)acrylic block copolymer) The (meth)acrylic block copolymer (hereinafter, sometimes simply referred to as "block copolymer") is a block copolymer having an A block having a structural unit (a-1) represented by general formula (1) and a B block having a structural unit (b-1) derived from a vinyl monomer having a reactive functional group.

[0030] The block copolymer may be a copolymer containing structural units derived from (meth)acrylic monomers as the main component (50% by mass or more), and may contain structural units derived from vinyl monomers other than (meth)acrylic monomers. The content of structural units derived from (meth)acrylic monomers in the block copolymer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on 100% by mass of the entire copolymer. The block copolymer may also be composed solely of structural units derived from (meth)acrylic monomers.

[0031] The content of the structural unit (a-1) in the block copolymer is preferably 40% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and is preferably 99.99% by mass or less, more preferably 99.9% by mass or less, and even more preferably 99.5% by mass or less, based on 100% by mass of the block copolymer. If the content of the structural unit (a-1) is 40% by mass or more, the releasability will be better, and if it is 99.99% by mass or less, the compatibility with aminoalkyd resins will be better.

[0032] The content of the structural unit (b-1) in the block copolymer is preferably 0.01% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.5% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on 100% by mass of the block copolymer. If the content of the structural unit (b-1) is 0.01% by mass or more, the effect of improving the strength of the release layer by crosslinking becomes greater, and if it is 20% by mass or less, an increase in viscosity of the amino alkyd resin composition is suppressed, the coatability is improved, and the appearance of the release agent layer becomes better.

[0033] The total content of the structural unit (a-1) and the structural unit (b-1) in the block copolymer is preferably 40% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on 100% by mass of the block copolymer. The copolymer may be composed only of the structural unit (a-1) and the structural unit (b-1).

[0034] The mass ratio ((a-1) / (b-1)) of the structural unit (a-1) to the structural unit (b-1) in the block copolymer is preferably 4 or more, more preferably 5 or more, even more preferably 10 or more, and is preferably 10,000 or less, more preferably 500 or less, even more preferably 200 or less, particularly preferably 100 or less, and most preferably 25 or less. When the mass ratio ((a-1) / (b-1)) is 4 or more, the appearance of the release agent layer is improved while maintaining releasability, and when it is 10,000 or less, compatibility with the aminoalkyd resin is imparted and strength of the release agent layer can be imparted by crosslinking.

[0035] The structure of the block copolymer is preferably a linear block copolymer. The linear block copolymer may have any structure (arrangement), but from the viewpoint of the physical properties of the linear block copolymer or the physical properties of the composition, when the A block is represented as A and the B block is represented as B, the structure (AB) m Type, (AB) m - Type A, (BA) mPreferably, the block copolymer has at least one structure selected from the group consisting of -B type (m is an integer of 1 or more, for example, an integer of 1 to 3). Among these, AB type diblock copolymers are preferred from the viewpoints of ease of handling during processing and the physical properties of the composition. By forming an AB type diblock copolymer, the structural unit (a-1) in the A block and the structural unit (b-1) in the B block are localized, and the structural unit (a-1) in the A block is efficiently oriented toward the air surface (release surface), thereby improving the release properties. Furthermore, the structural unit (b-1) in the B block is oriented toward the substrate surface, thereby improving crosslinking efficiency and improving the strength of the release agent layer. The block copolymer may have blocks other than the A block and the B block.

[0036] The content of the A block is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on 100% by mass of the entire block copolymer, and is preferably 99.99% by mass or less, more preferably 99.9% by mass or less, and even more preferably 99.5% by mass or less. The content of the B block is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on 100% by mass of the entire block copolymer. If the content of the B block is 0.01% by mass or more, the strength of the release agent layer can be sufficient, and if it is 20% by mass or less, the appearance and peel strength of the release agent layer will be good.

[0037] The mass ratio of the A block to the B block in the block copolymer (A block / B block) is preferably 80 / 20 or more, more preferably 90 / 10 or more, and even more preferably 95 / 5 or more, and is preferably 99.99 / 0.01 or less, more preferably 99.9 / 0.1 or less, and even more preferably 99.5 / 0.5 or less. When the mass ratio of the A block to the B block is within the above range, the compatibility of the block copolymer with the aminoalkyd resin is increased, and the releasability and appearance of the release agent layer are further improved.

[0038] The molecular weight of the block copolymer is measured by gel permeation chromatography (hereinafter referred to as "GPC"). The weight average molecular weight (Mw) of the block copolymer is preferably 5,000 or more, more preferably 15,000 or more, even more preferably 30,000 or more, and is preferably 400,000 or less, more preferably 200,000 or less, even more preferably 70,000 or less, and particularly preferably 60,000 or less. If the weight average molecular weight is 5,000 or more, the strength of the release agent layer can be sufficient, and if it is 400,000 or less, the solubility in solvents can be good.

[0039] The molecular weight distribution (PDI) of the block copolymer is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.6 or less, and particularly preferably 1.5 or less. In this specification, the molecular weight distribution (PDI) is calculated by (weight average molecular weight (Mw) of the copolymer) / (number average molecular weight (Mn) of the copolymer). The smaller the PDI, the narrower the molecular weight distribution, resulting in a copolymer with a uniform molecular weight, and when the PDI value is 1.0, the molecular weight distribution is narrowest. In other words, the lower limit of the PDI is 1.0. If the molecular weight distribution (PDI) of the block copolymer exceeds 3.0, it will contain both low and high molecular weight copolymers.

[0040] The amount of reactive functional groups per 100 g of the block copolymer is preferably 0.05 mmol / 100 g or more, more preferably 0.9 mmol / 100 g or more, even more preferably 1.2 mmol / 100 g or more, particularly preferably 1.8 mmol / 100 g or more, most preferably 3.0 mmol / 100 g or more, and is preferably 120.0 mmol / 100 g or less, more preferably 60.0 mmol / 100 g or less, even more preferably 8.0 mmol / 100 g or less, particularly preferably 7.0 mmol / 100 g or less, most preferably 4.9 mmol / 100 g or less. If the amount of reactive functional groups is 0.05 mmol / 100 g or more, the strength of the release agent layer can be sufficient, and if it is 120.0 mmol / 100 g or less, good peel strength from the adherend can be obtained.

[0041] From the viewpoint of heat resistance, the content of the block copolymer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 4 parts by mass or more, and particularly preferably 7 parts by mass or more, per 100 parts by mass of the constituent components of the amino alkyd resin, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less. If the content of the block copolymer is 1 part by mass or more, excellent releasability and heat resistance can be obtained, and if it is 50 parts by mass or less, whitening of the release agent layer can be suppressed.

[0042] The various constituent components of the copolymer will be explained below.

[0043] (Block A) The A block is a polymer block having a structural unit (a-1) represented by the following general formula (1): The structural unit (a-1) may be of one type, or may have two or more types.

[0044] [ka] [In formula (1), R 11 represents an alkyl group having 12 to 28 carbon atoms. 12 represents a hydrogen atom or a methyl group.

[0045] The A block has an alkyl group introduced by the structural unit (a-1) represented by general formula (1). Therefore, the copolymer is a (meth)acrylic polymer having an alkyl group. When the number of carbon atoms in the alkyl group of the (meth)acrylic polymer having an alkyl group is too small, it is generally difficult to exhibit the peelability (mold releasability) of the (meth)acrylic polymer, and the residual adhesive strength tends to decrease. On the other hand, when the number of carbon atoms in the alkyl group is too large, the peel strength becomes too high due to high crystallinity, etc., and the peel performance decreases. Therefore, in the structural unit (a-1), R 11 By adjusting the carbon number of R to 12 to 28, the release performance becomes excellent. 11 The number of carbon atoms is preferably 14 or more, more preferably 16 or more, and is preferably 26 or less, more preferably 22 or less.

[0046] R 11 Examples of the alkyl group include a linear alkyl group, a branched alkyl group, and a cyclic alkyl group, with a linear alkyl group and / or a branched alkyl group being preferred. Examples of the linear alkyl group include an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group (an n-stearyl group), an n-nonadecyl group, an n-icosyl group, an n-heicosyl group, an n-docosyl group, an n-tricosyl group, an n-tetracosyl group, an n-heptacosyl group, an n-hexacosyl group, an n-heptacosyl group, and an n-octacosyl group. Examples of the branched alkyl group include an isododecyl group, an isotridecyl group, an isotetradecyl group, an isopentadecyl group, an isohexadecyl group, an isooctadecyl group, an isononadecyl group, an isoicosyl group, an isoheicosyl group, an isodocosyl group, an isotricosyl group, an isotetracosyl group, an isoheptacosyl group, an isohexacosyl group, an isoheptacosyl group, and an isooctacosyl group. The cyclic alkyl group may be a cyclic alkyl group having a monocyclic structure (for example, a cycloalkyl group), and specific examples thereof include an n-undecylcyclohexyl group and an n-dodecylcyclohexyl group.

[0047] Specific examples of vinyl monomers forming the structural unit (a-1) represented by general formula (1) include n-dodecyl(meth)acrylate, n-tridecyl(meth)acrylate, n-tetradecyl(meth)acrylate, n-pentadecyl(meth)acrylate, n-hexadecyl(meth)acrylate, n-heptadecyl(meth)acrylate, stearyl(meth)acrylate, n-nonadecyl(meth)acrylate, n-icosyl(meth)acrylate, n-heicosyl(meth)acrylate, n-docosyl(meth)acrylate, n-tricosyl(meth)acrylate, n-tetracosyl(meth)acrylate, n-heptacosyl(meth)acrylate, n-hexacosyl(meth)acrylate, n-heptacosyl(meth)acrylate, n-octacosyl(meth)acrylate, and isododecyl(meth)acrylate. n-Undecylcyclohexyl (meth)acrylate, n-Do ...

[0048] The A block may consist solely of the structural unit (a-1), or may contain other structural units. From the viewpoint of maintaining excellent releasability, the content of the structural unit (a-1) is preferably 40% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on 100% by mass of the A block. Furthermore, it is preferable that the A block does not substantially contain the structural unit (b-1) described below. That is, the content of the structural unit (b-1) is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, based on 100% by mass of the A block.

[0049] The composition of the A block may be adjusted appropriately depending on the pressure-sensitive adhesive layer or adhesive layer to be bonded to the release sheet. When the adhesive layer to be bonded to the release sheet is relatively hard, the A block may have the following structure: 11 In a preferred embodiment, the structural units (a-1) having 14 to 26 (preferably 16 to 22) carbon atoms account for 80% by mass or more (preferably 90% by mass or more, more preferably 95% by mass or more) of 100% by mass of the A block.

[0050] In addition, when the pressure-sensitive adhesive layer or adhesive layer to be attached to the release sheet is relatively soft, the form of the A block is R 11 In a preferred embodiment, the structural unit (a-1) having 12 to 26 (preferably 12 to 15) carbon atoms accounts for 40% by mass or more (preferably 45% by mass or more) of 100% by mass of the A block. In particular, the A block preferably contains a structural unit (a-1-1) represented by formula (1-1) and a structural unit (a-1-2) represented by formula (1-2). In this case, the mass ratio ((a-1-1) / (a-1-2)) of the structural unit (a-1-1) to the structural unit (a-1-2) in the A block is preferably 20 / 80 or more, more preferably 30 / 70 or more, even more preferably 40 / 60 or more, and is preferably 80 / 20 or less, more preferably 70 / 30 or less, even more preferably 60 / 40 or less. The total content of the structural unit (a-1-1) and the structural unit (a-1-2) in the A block is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more.

[0051] [ka] [In formula (1-1), R 13 represents an alkyl group having 12 to 15 carbon atoms. 14 represents a hydrogen atom or a methyl group. In formula (1-2), R 15 represents an alkyl group having 16 to 28 carbon atoms. 16 represents a hydrogen atom or a methyl group.

[0052] Specific examples of vinyl monomers that can form other structural units of the A block include (meth)acrylates having a linear alkyl group with 1 to 11 carbon atoms, (meth)acrylates having a branched alkyl group with 3 to 11 carbon atoms, (meth)acrylates having a cyclic alkyl group with 6 to 11 carbon atoms, (meth)acrylates having an aromatic group, (meth)acrylates having a polyalkylene glycol structural unit, (meth)acrylates having an alkoxy group, (meth)acrylates having an oxygen-containing heterocyclic group, α-olefins, aromatic vinyl monomers, vinyl monomers containing a heterocycle, vinylamides, vinyl carboxylates, and dienes.

[0053] The (meth)acrylate having a linear alkyl group having 1 to 11 carbon atoms is preferably a (meth)acrylate having a linear alkyl group having 1 to 10 carbon atoms, and more preferably a (meth)acrylate having a linear alkyl group having 1 to 5 carbon atoms. Examples of the (meth)acrylate having a linear alkyl group having 1 to 11 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, and decyl (meth)acrylate.

[0054] The (meth)acrylate having a branched chain alkyl group with 3 to 11 carbon atoms is preferably a (meth)acrylate having a branched chain alkyl group with the number of carbon atoms in the branched chain alkyl group being 3 to 10. Examples of the (meth)acrylate having a branched chain alkyl group include isopropyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, and isodecyl (meth)acrylate.

[0055] Examples of the (meth)acrylate having a cyclic alkyl group having 6 to 11 carbon atoms include cyclohexyl (meth)acrylate and methylcyclohexyl (meth)acrylate.

[0056] The (meth)acrylate having an aromatic group is preferably a (meth)acrylate having an aromatic group having 6 to 12 carbon atoms, and more preferably a (meth)acrylate having an aromatic group having 6 to 9 carbon atoms. Examples of the aromatic group include an aryl group, and the aromatic group may have a chain moiety such as an alkylaryl group, an aralkyl group, or an aryloxyalkyl group. Specific examples of the (meth)acrylate having an aromatic group include benzyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate.

[0057] Examples of the (meth)acrylate having a polyalkylene glycol structural unit include (meth)acrylates having a polyethylene glycol structural unit such as polyethylene glycol (degree of polymerization = 2 to 10) methyl ether (meth)acrylate, polyethylene glycol (degree of polymerization = 2 to 10) ethyl ether (meth)acrylate, and polyethylene glycol (degree of polymerization = 2 to 10) propyl ether (meth)acrylate; and (meth)acrylates having a polypropylene glycol structural unit such as polypropylene glycol (degree of polymerization = 2 to 10) methyl ether (meth)acrylate, polypropylene glycol (degree of polymerization = 2 to 10) ethyl ether (meth)acrylate, and polypropylene glycol (degree of polymerization = 2 to 10) propyl ether (meth)acrylate.

[0058] Examples of the (meth)acrylate having an alkoxy group include methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate.

[0059] The (meth)acrylate having an oxygen-containing heterocyclic group is preferably a (meth)acrylate having a 4- to 6-membered oxygen-containing heterocyclic group. Specific examples of the (meth)acrylate having an oxygen-containing heterocyclic group include glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate, and 1,3-dioxane-(meth)acrylate.

[0060] Examples of the α-olefin include 1-hexene, 1-octene, and 1-decene. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene, and 1-vinylnaphthalene. Examples of the vinyl monomer containing a heterocycle include 2-vinylthiophene, N-methyl-2-vinylpyrrole, 1-vinyl-2-pyrrolidone, 2-vinylpyridine, 4-vinylpyridine, N-phenylmaleimide, N-benzylmaleimide, and N-cyclohexylmaleimide. Examples of the vinylamide include N-vinylformamide, N-vinylacetamide, and N-vinyl-ε-caprolactam. Examples of the vinyl carboxylate include vinyl acetate, vinyl pivalate, and vinyl benzoate. Examples of the dienes include butadiene, isoprene, 4-methyl-1,4-hexadiene, and 7-methyl-1,6-octadiene.

[0061] The A block preferably does not have a reactive functional group (hydroxy group, amino group, thiol group, carboxy group, sulfonic acid group, phosphate group, phosphonic acid group, phosphinic acid group). When a release agent layer is formed using the release agent composition, the block copolymer is thought to segregate on the surface of the release agent layer. In this case, the B block of the block copolymer is located on the amino alkyd resin side, and the A block is located on the surface side of the release agent layer. Therefore, if the A block does not have a reactive functional group, no reactive functional group will be present on the surface of the release agent layer. Therefore, even if the release agent layer is exposed to high temperatures (e.g., 100°C or higher) while in contact with a pressure-sensitive adhesive or adhesive, an increase in release force is suppressed.

[0062] When two or more types of structural units are contained in the A block, the various structural units contained in the A block may be contained in the A block in any form, such as random copolymerization or block copolymerization, and from the viewpoint of uniformity, they are preferably contained in the A block in the form of random copolymerization. For example, the A block may be formed from a copolymer of structural units consisting of the a1 block and structural units consisting of the a2 block.

[0063] (Block B) The B block is a polymer block having a structural unit (b-1) derived from a vinyl monomer having a reactive functional group. The structural unit (b-1) may be of one type or may have two or more types.

[0064] The reactive functional group possessed by the structural unit (b-1) is a functional group capable of reacting with a functional group possessed by the aminoalkyd resin and / or the melamine-based crosslinking agent described below. Examples of the vinyl monomer having a reactive functional group that forms the structural unit (b-1) include (meth)acrylic monomers having a reactive functional group and vinyl monomers other than (meth)acrylic monomers having a reactive functional group.

[0065] Examples of the reactive functional group possessed by the structural unit (b-1) include a hydroxy group, an amino group, a carboxy group, a thiol group, etc. Such reactive functional groups may be contained alone or in combination of two or more. Among these reactive functional groups, a hydroxy group or a carboxy group is preferred, and a hydroxy group is more preferred from the viewpoint of reactivity with an aminoalkyd resin and / or a melamine-based crosslinking agent.

[0066] Examples of the vinyl monomer that forms the structural unit (b-1) include (meth)acrylic monomers having a hydroxy group, (meth)acrylic monomers having an amino group, (meth)acrylic monomers having a carboxy group, (meth)acrylic monomers having a thiol group, vinyl monomers other than (meth)acrylic monomers having a hydroxy group, vinyl monomers other than (meth)acrylic monomers having an amino group, vinyl monomers other than (meth)acrylic monomers having a carboxy group, and vinyl monomers other than (meth)acrylic monomers having a thiol group.

[0067] Examples of (meth)acrylic monomers having a hydroxy group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; caprolactone adducts of hydroxyalkyl (meth)acrylates, etc. Among these, hydroxyalkyl (meth)acrylates are preferred, and (meth)acrylates having a hydroxyalkyl group having 1 to 5 carbon atoms are more preferred.

[0068] Examples of the (meth)acrylic monomer having an amino group include aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, and aminobutyl (meth)acrylate.

[0069] Examples of the (meth)acrylic monomer having a carboxy group include monomers obtained by reacting a (meth)acrylate having a hydroxy group, such as 2-(meth)acryloyloxyethyl succinate or 2-(meth)acryloyloxyethyl maleate, with an acid anhydride, such as maleic anhydride or succinic anhydride, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 1,4-di(meth)acryloxyethyl pyromellitic acid, 4-(meth)acryloxyethyl trimellitic acid, and 2-(meth)acryloyloxybenzoic acid.

[0070] Examples of vinyl monomers other than the (meth)acrylic monomer having a hydroxy group include allyl alcohol. Examples of vinyl monomers other than the (meth)acrylic monomer having an amino group include allylamine. Examples of vinyl monomers other than (meth)acrylic monomers having a carboxy group include crotonic acid, maleic acid, itaconic acid, citraconic acid, and cinnamic acid.

[0071] The B block may consist solely of the structural unit (b-1), or may contain other structural units. From the viewpoint of maintaining excellent releasability, the content of the structural unit (b-1) is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more, based on 100% by mass of the B block. It is also preferable that the B block does not substantially contain the structural unit (a-1). That is, the content of the structural unit (a-1) is 50% by mass or less, preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, based on 100% by mass of the B block.

[0072] Specific examples of vinyl monomers that can form other structural units of the B block include the same monomers as those exemplified as specific examples of vinyl monomers that can form other structural units of the A block.

[0073] When two or more types of structural units are contained in the B block, the various structural units contained in the B block may be contained in the B block in any form, such as random copolymerization or block copolymerization, and from the viewpoint of uniformity, they are preferably contained in the B block in the form of random copolymerization. For example, the B block may be formed from a copolymer of structural units consisting of the b1 block and structural units consisting of the b2 block.

[0074] (1-2-3. Method for producing copolymer) Examples of methods for producing the copolymer include a method in which an A block is first produced by a polymerization reaction of a vinyl monomer and then a monomer for a B block is polymerized onto the A block; a method in which a B block is first produced and then a monomer for an A block is polymerized onto the B block; and a method in which the A block and the B block are produced separately and then the A block and the B block are coupled together.

[0075] The polymerization method is not particularly limited, but living radical polymerization is preferred. That is, the copolymer is preferably one polymerized by living radical polymerization. Living radical polymerization is preferred in that it maintains the simplicity and versatility of conventional radical polymerization methods, while being less susceptible to termination reactions and chain transfer, and allows growth without being hindered by side reactions that deactivate the growing ends, making it easy to precisely control the molecular weight distribution and produce polymers with a uniform composition.

[0076] Living radical polymerization methods include those using transition metal catalysts (ATRP), those using sulfur-based reversible chain transfer agents (RAFT), and those using organotellurium compounds (TERP), depending on the method used to stabilize the polymer growing end. Among these, the TERP method is preferred from the viewpoints of the variety of monomers that can be used, molecular weight control in the polymer region, uniform composition, and coloration.

[0077] The TERP method is a method of polymerizing a radically polymerizable compound (vinyl monomer) using an organic tellurium compound as a chain transfer agent, and is a method described, for example, in WO 2004 / 14848, WO 2004 / 14962, WO 2004 / 072126, and WO 2004 / 096870.

[0078] Specific polymerization methods of the TERP method include the following (a) to (d). (a) A method of polymerizing a vinyl monomer using an organotellurium compound represented by the general formula (6). (b) A method of polymerizing a vinyl monomer using a mixture of an organotellurium compound represented by general formula (6) and an azo-based polymerization initiator. (c) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by general formula (6) and an organic ditelluride compound represented by general formula (7). (d) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by general formula (6), an azo-based polymerization initiator, and an organic ditelluride compound represented by general formula (7).

[0079] [ka] [In formula (6), R 61 represents an alkyl group having 1 to 8 carbon atoms, an aryl group, or an aromatic heterocyclic group. 62 and R 63 R each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. 64 represents an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amido group, an oxycarbonyl group, a cyano group, an allyl group, or a propargyl group. In equation (7), R 61 represents an alkyl group having 1 to 8 carbon atoms, an aryl group, or an aromatic heterocyclic group.]

[0080] Specific examples of the organic tellurium compound represented by general formula (6) include ethyl-2-methyl-2-n-butyltellanyl-propionate, ethyl-2-n-butyltellanyl-propionate, (2-hydroxyethyl)-2-methyl-methyltellanyl-propionate, and the organic tellurium compounds described in WO 2004 / 14848, WO 2004 / 14962, WO 2004 / 072126, and WO 2004 / 096870. Specific examples of the organic ditelluride compound represented by general formula (7) include dimethyl ditelluride and dibutyl ditelluride. The azo polymerization initiator can be any azo polymerization initiator used in ordinary radical polymerization without any particular limitation, and examples thereof include 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN), 1,1'-azobis(1-cyclohexanecarbonitrile) (ACHN), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70).

[0081] In the polymerization process, a vinyl monomer and an organotellurium compound of general formula (6) are mixed in a vessel purged with an inert gas, and, depending on the type of vinyl monomer, an azo polymerization initiator and / or an organic ditelluride compound of general formula (7) are further added for the purposes of promoting the reaction and controlling the molecular weight and molecular weight distribution. Examples of inert gases include nitrogen, argon, and helium. Argon and nitrogen are preferred. The amounts of vinyl monomer used in steps (a), (b), (c), and (d) can be adjusted appropriately depending on the physical properties of the desired copolymer.

[0082] The polymerization reaction can be carried out without a solvent, but it can also be carried out by stirring the mixture using an aprotic or protic solvent commonly used in radical polymerization. Examples of aprotic solvents that can be used include anisole, benzene, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, and tetrahydrofuran (THF). Examples of protic solvents include water, methanol, and 1-methoxy-2-propanol. Solvents can be used alone or in combination. The amount of solvent used can be adjusted appropriately, preferably 0.01 ml to 50 ml per gram of vinyl monomer. The reaction temperature and reaction time can be adjusted appropriately depending on the molecular weight or molecular weight distribution of the resulting copolymer. The reaction is typically carried out at 0°C to 150°C and stirred for 1 minute to 100 hours. After completion of the polymerization reaction, the solvent and residual vinyl monomer can be removed from the resulting reaction mixture by conventional separation and purification techniques, and the target copolymer can be isolated.

[0083] The growing end of the copolymer obtained by the polymerization reaction is -TeR derived from the tellurium compound. 61 (In the formula, R 61 is the same as above), and is deactivated by handling in air after the polymerization reaction is completed, but tellurium atoms may remain. A copolymer with tellurium atoms remaining at the end will be colored and have poor thermal stability, so it is preferable to remove the tellurium atoms. Methods for removing tellurium atoms include radical reduction; adsorption with activated carbon, etc.; and metal adsorption with ion exchange resin, etc., and these methods can also be used in combination. The other end of the copolymer obtained by the polymerization reaction (the end opposite to the growing end) is formed from -CR derived from the tellurium compound. 62 R 63 R 64 (In the formula, R 62 , R 63 and R 64 is R in equation (6). 62 , R 63 and R 64 It is the same as ().

[0084] (acidic catalyst) The aminoalkyd resin composition may contain an acidic catalyst, if necessary. Examples of the acidic catalyst include organic acids such as acetic acid and oxalic acid; mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid; organic sulfonic acids such as diethylsulfuric acid, paratoluenesulfonic acid, paraphenolsulfonic acid, benzenesulfonic acid, and methanesulfonic acid; and organic phosphonic acids such as 1-hydroxyethylidene-1,1'-diphosphonic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid. Among these, paratoluenesulfonic acid is preferred. The acidic catalysts may be used alone or in combination of two or more.

[0085] When the acid catalyst is added, the content of the acid catalyst is preferably 0.1 to 15 parts by mass, more preferably 3 to 12 parts by mass, and even more preferably 5 to 10 parts by mass, relative to 100 parts by mass of the total solid content (components other than the solvent) of the aminoalkyd resin composition. If the content of the acid catalyst is within the above range, the strength of the release agent layer is further improved.

[0086] (Other additives) In addition to the above components, other additives can be blended into the aminoalkyd resin composition as needed. Examples of other additives include antioxidants, chlorine absorbers, ultraviolet absorbers, plasticizers, flame retardants, antistatic agents, colorants, and antiblocking agents. These are appropriately selected and blended depending on the application and purpose of the release sheet. The other additives may be used alone or in combination of two or more.

[0087] Examples of the antioxidant include phenol-based antioxidants, hindered amine-based antioxidants, phosphite-based antioxidants, lactone-based antioxidants, tocopherol-based antioxidants, etc. Specific examples include 2,6-di-t-butyl-p-cresol, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxy)benzene, tris(2,4-di-t-butylphenyl)phosphite, etc.

[0088] Examples of the chlorine absorbent include metal soaps such as calcium stearate. Examples of the ultraviolet absorber include benzotriazole, benzophenone, and hydroxybenzoate. Examples of the plasticizer include citrate esters, dibutyl phthalate, polyethylene glycols, propylene glycols, and glycerin. Examples of the flame retardant include phosphazene-based compounds, phosphate esters, condensed phosphate esters, inorganic phosphorus-based, halogen-based, and silicone-based flame retardants, metal oxide-based flame retardants, metal hydroxide-based flame retardants, organic metal salt-based flame retardants, nitrogen-based flame retardants, and boron compound-based flame retardants. Examples of the antistatic agent include glycerin monoesters (such as glycerin monostearate), ethoxylated secondary amines, and the like. Examples of the colorant include various colored dyes, colored pigments, and fluorescent dyes.

[0089] The antiblocking agent is added to prevent blocking and is not particularly limited as long as it functions as a nucleating agent. Examples of antiblocking agents include inorganic particles and organic particles. Examples of inorganic particles include silica, alumina, (synthetic) zeolite, calcium carbonate, kaolin, talc, mica, zinc oxide, magnesium oxide, quartz, magnesium carbonate, barium sulfate, and titanium dioxide. Examples of organic particles include polystyrene resin, polyacrylic resin, polymethyl methacrylate (PMMA) resin, cross-linked polyethylene resin, polyester resin, polyamide resin, polycarbonate resin, polyether resin, polyethersulfone resin, polyetherimide resin, polyphenylene sulfide resin, polyetheretherketone resin, polyamideimide resin, benzoguanamine resin, furan resin, epoxy resin, phenolic resin, unsaturated polyester resin, vinyl ester resin, diallyl phthalate resin, polyimide resin, fatty acid amide resin, and fatty acid glycerin ester compound particles. Among these, PMMA resin particles and silica particles are more preferred because they are excellent in blocking resistance and imparting slip properties.The anti-blocking agent preferably has a particle size of 0.1 μm to 10 μm.

[0090] The aminoalkyd resin composition preferably contains substantially no silicone compounds, which means that the content of silicone compounds in the solid content (components other than the solvent) of the aminoalkyd resin composition is 10% by mass or less, more preferably 5% by mass or less, and most preferably 0% by mass.

[0091] (Method for producing aminoalkyd resin composition) The aminoalkyd resin composition can be produced by mixing the constituent components of the aminoalkyd resin, the block copolymer, and, if necessary, the acidic catalyst and other additives. The aminoalkyd resin composition may contain a solvent derived from the production of the block copolymer, or may be a solution diluted with an appropriate solvent to have a viscosity suitable for forming a release agent layer.

[0092] Examples of solvents used in aminoalkyd resin compositions include organic solvents such as alcohol-based solvents such as ethanol, isopropyl alcohol (IPA), n-butyl alcohol (NBA), ethylene glycol monomethyl ether (EGM), ethylene glycol monoisopropyl ether (IPG), propylene glycol monomethyl ether (PGM), and diethylene glycol monobutyl ether; ketone-based solvents such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone, and acetone; aromatic hydrocarbon-based solvents such as toluene and xylene; ester-based solvents such as ethyl acetate (EtAc), propyl acetate, isopropyl acetate, and butyl acetate (BuAc); and amide-based solvents such as N-methylpyrrolidone, acetamide, and dimethylformamide. These solvents may be used alone or in combination of two or more.

[0093] <Production of release sheets> A release sheet is a general term for sheets that have a so-called "peel-off function," such as release sheets and process sheets, and the release agent layer of which is attached to a pressure-sensitive adhesive or adhesive to protect the adhesive or bonded surface during storage or manufacturing of electronic components.

[0094] (Base sheet) The substrate sheet is not particularly limited, and a commonly used substrate can be used. Examples of the substrate sheet include paper (high-quality paper, dust-free paper, glassine paper, clay-coated paper, resin-coated paper, laminated paper (polyethylene-laminated paper, polypropylene-laminated paper, etc.)), nonwoven fabric, metal foil, polymer sheet, glass sheet, etc.

[0095] Examples of polymer materials constituting the polymer sheet include polyethylene terephthalate resin, polyethylene naphthalate resin, polycarbonate resin, poly(meth)acrylate resin, polystyrene resin, polyamide resin, polyimide resin, polyacrylonitrile resin, polypropylene resin, polyethylene resin, polycycloolefin resin, cycloolefin copolymer resin, polyphenylene sulfide resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, polyether ether ketone resin, etc. Among these, from the viewpoints of heat resistance, strength, adhesion to a release agent, handleability, etc., polyethylene terephthalate resin, polyethylene naphthalate resin, polyimide resin, polycarbonate resin, poly(meth)acrylate resin, polyamide resin, polycycloolefin resin, cycloolefin copolymer resin, and polyether ether ketone resin are preferred as polymer materials. The polymer sheet may be composed of a single layer containing one or more of the polymer materials, or may be composed of two or more layers, such as a layer containing one or more of the polymer materials and a layer containing one or more of the polymer materials different from the layer containing one or more of the polymer materials.

[0096] The thickness of the substrate sheet is not particularly limited, but from the viewpoint of excellent handleability, it is preferably 2 μm to 500 μm, and more preferably 2 μm to 200 μm.

[0097] The substrate sheet may be surface-treated to improve adhesion to the release agent layer. Examples of surface treatments include corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment. An easy-adhesion layer may be provided on the surface of the substrate sheet. Furthermore, various functional layers such as a gas barrier property improving layer, an antistatic layer, and an oligomer block layer may be provided on the surface of the substrate sheet.

[0098] (Release agent layer) The release agent layer is formed on at least one surface of the substrate sheet. The release agent layer can be formed by applying the aminoalkyd resin composition and, if necessary, drying and curing the composition. When the aminoalkyd resin composition is cured, the components of the aminoalkyd resin and the block copolymer are crosslinked by the N-methylol groups and / or N-alkoxymethylol groups contained in the composition, thereby forming an interpenetrating polymer network. Therefore, the release agent layer formed from the aminoalkyd resin composition has excellent strength.

[0099] The method for applying the aminoalkyd resin composition is not particularly limited, and coating methods (reverse gravure coating, direct gravure coating, die coating, bar coating, wire bar coating, roll coating, spin coating, dip coating, spray coating, knife coating, kiss coating, etc.), inkjet methods, and printing methods (offset printing, screen printing, flexographic printing, etc.) can be used.

[0100] From the viewpoint of the curability of the coating film, the aminoalkyl resin composition is dried and cured preferably at 100°C to 170°C for 10 to 60 seconds, more preferably at 140°C to 160°C for 20 to 40 seconds.

[0101] The thickness of the release agent layer is preferably 0.03 μm or more, more preferably 0.05 μm or more, and even more preferably 0.07 μm or more, from the viewpoint of release performance, processability, etc. Also, from the viewpoint of curability, the thickness is preferably 0.5 μm or less, more preferably 0.3 μm or less, and even more preferably 0.2 μm or less.

[0102] The release sheet preferably has a release agent layer that is substantially free of silicone compounds in order to reduce adverse effects on electrical components, etc. "Substantially free of silicone compounds" means that the amount of silicone compounds is preferably 500 μg / g or less, more preferably 100 μg / g or less.

[0103] The release sheet may have a matte surface (the surface that comes into contact with the pressure-sensitive adhesive or adhesive) of the release agent layer. When an adhesive is applied to a release sheet having a matte surface of the release agent layer, the adhesive surface becomes matte. Therefore, for example, when the release sheet is used as an adhesive sheet for an interphase insulating film of a printed wiring board, the adhesive surface of the adhesive sheet becomes matte, which can improve processability in the manufacturing process of the printed wiring board.

[0104] When the surface of the release agent layer is matted, the arithmetic mean roughness Ra (JIS B0601:2013) of the surface of the release agent layer is preferably 0.3 μm to 1.0 μm, more preferably 0.5 μm to 0.8 μm. Furthermore, the maximum height Rz (JIS B0601:2013) of the surface of the release agent layer is preferably 4 μm to 11 μm, more preferably 6 μm to 9 μm. When the arithmetic mean roughness and maximum height of the surface of the release agent layer are within the above ranges, the surface of the adhesive or pressure-sensitive adhesive to be applied can be made sufficiently rough, improving the ease of positioning when bonding printed wiring boards together and facilitating the removal of air bubbles between the adhesive or pressure-sensitive adhesive and the printed wiring board.

[0105] An example of a method for matting the release agent layer is a method of subjecting a substrate sheet on which the release agent layer is formed to a matte treatment. By subjecting the substrate sheet to a matte treatment, the surface of the release agent layer formed on the substrate sheet is also matte. Examples of matte treatment methods include a method of sandblasting the substrate sheet surface, a method of forming a matte layer on the substrate sheet by coating, a method of forming a resin into which inorganic or organic particles have been kneaded, and a method of molding a resin using a matte roll while molding. Among these, the method of forming a matte layer by coating is preferred from the viewpoint of ease of controlling surface roughness.

[0106] The method for forming the matte layer by coating can be the same as the method used for forming the release agent layer. Examples of the method include a method in which a coating agent composition containing a binder resin and particles is applied to a substrate sheet and cured to form the matte layer, and a method in which a matte layer is formed by phase separation of two or more materials.

[0107] The release sheet can be used to protect the adhesive or bonding surface of a pressure-sensitive adhesive tape or a sheet-like adhesive. Furthermore, the release sheet inhibits an increase in peel strength even when exposed to high temperatures while attached to a pressure-sensitive adhesive or adhesive. Therefore, the release sheet is suitable for use in applications where it is exposed to temperatures of 100°C or higher (particularly 150°C or higher) while attached to a pressure-sensitive adhesive or adhesive. Specific examples include release sheets used in the process of forming a sheet-like adhesive or a sheet-like pressure-sensitive adhesive, which are exposed to temperatures of 100°C or higher when forming an adhesive or pressure-sensitive adhesive layer; and release sheets used when hot-press transferring a sheet-like adhesive to an adherend, which are exposed to temperatures of 100°C or higher (particularly 150°C or higher) during hot-pressing. The pressure-sensitive adhesive or adhesive to which the release sheet can be attached is not limited, but examples include pressure-sensitive adhesives or adhesives having a hydroxy group, a carboxy group, or an epoxy group. [Example]

[0108] The present invention will be described in more detail below based on specific examples. The present invention is not limited to the following examples and can be practiced with appropriate modifications within the scope of the present invention. The polymerization rate, weight average molecular weight (Mw), and molecular weight distribution (PDI) of the copolymer, as well as the peel strength, heat resistance, residual adhesion rate, peel strength from the adhesive layer, strength, and appearance of the release layer were evaluated according to the following methods.

[0109] The meanings of the abbreviations are as follows: BTEE: Ethyl 2-methyl-2-n-butyltellanyl propionate AIBN: 2,2'-azobis(isobutyronitrile) SA: Stearyl acrylate SMA: Stearyl methacrylate LA: Lauryl acrylate 4-HBA: 4-hydroxybutyl acrylate 2-HEMA: 2-hydroxyethyl methacrylate AcOEt: ethyl acetate MeOH: Methanol MEK: Methyl ethyl ketone

[0110] [Evaluation method] (Polymerization rate) Using a nuclear magnetic resonance (NMR) measurement device (Bruker Biospin, model: AVANCE500 (frequency 500 MHz)), 1 H-NMR was measured (solvent: CDCl3, internal standard: trimethylsilane). For the obtained NMR spectrum, the integral ratio of the peaks of the vinyl group derived from the monomer and the ester side chain derived from the polymer was calculated, and the polymerization rate of the monomer was calculated. For the NMR spectrum of the final product, the integral ratio of the peaks of the ester side chain of each component was calculated, and the content of each component was calculated.

[0111] (Weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (PDI)) The molecular weights were determined by gel permeation chromatography (GPC) using a high-performance liquid chromatograph (Tosoh Corporation, Model HLC-8320GPC). Two TSKgel Super Multipore HZ-H (Tosoh Corporation) columns were used, the mobile phase was tetrahydrofuran solution, and the detector was a differential refractometer. The measurement conditions were a column temperature of 40°C, a sample concentration of 10 mg / mL, a sample injection volume of 10 μm, and a flow rate of 0.2 mL / min. A calibration curve was prepared using polystyrene standards (molecular weights: 109,000, 775,000, 427,000, 289,000, 190,000, 96,400, 37,900, 10,200, 2,630, and 440), and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured. The molecular weight distribution (PDI = Mw / Mn) was calculated from these measurements.

[0112] (Release agent layer thickness) The thickness of the release agent layer was measured by spectral interferometry using a film thickness measurement system (manufactured by Filmetrics, "Filmetrics F20").

[0113] (Normal peel strength) The release surface (release agent layer) of the release sheet was attached to the adhesive layer surface of polyester base adhesive tape "NO. 31B" (manufactured by Nitto Denko Corporation, tape width 25 mm, adhesive layer thickness 8 μm, total thickness 50 μm), and the bonded body was placed on a glass plate and pressed with a 5 kg roller by rolling it back and forth once. After that, it was aged at room temperature (23 ° C) for 20 hours to prepare a sample for measuring normal peel strength. The peel force of the normal peel force measurement sample was measured using a Shimadzu Corporation precision universal testing machine "Autograph AGS-1kNX, 50N load cell" at a peel speed of 0.3 m / min and a peel angle of 90° in an environment of 23°C and 50% humidity.

[0114] (Heat resistance) The release sheet was placed on a glass plate with the release side facing up and heated in a thermostatic chamber at 150°C for 1 hour. Thereafter, the release force of the release sheet after the heat treatment was measured in the same manner as in the normal release force described above, and the heat resistance of the release sheet was evaluated. If this measured value is large, the peeling force will be large after the heat pressing and reflow process of the adhesive sheet with release sheet, which will result in poor workability or destruction of the release sheet or sheet-like adhesive.

[0115] (Peeling force after heating) The release surface of the release sheet was bonded to the adhesive layer surface of polyester-based adhesive tape "NO. 31B" (manufactured by Nitto Denko, tape width 25 mm, adhesive layer thickness 8 μm, total thickness 50 μm), and the bonded body was placed on a glass plate and pressed with a 5 kg roller by rolling it back and forth once. The bonded body was then sandwiched between two glass plates, a 760 g load was applied, and the body was heated in a thermostatic oven at 100°C for 20 hours to prepare a sample for measuring the peel strength after heating. After heating, the peel force of the sample for peel force measurement was measured using a Shimadzu Corporation precision universal testing machine "Autograph AGS-1kNX, 50N load cell" at a peel speed of 0.3 m / min and a peel angle of 90° in an environment of 23°C and 50% humidity.

[0116] (Residual adhesion rate) The polyester-based adhesive tape "NO. 31B" (Nitto Denko Corporation, tape width 25 mm, adhesive layer thickness 8 μm, total thickness 50 μm) used in the post-heat peel strength test was applied to an aluminum sheet "A1N30-O material" (Tokai Aluminum Co., Ltd., sheet width 50 mm, thickness 0.1 mm), pressed back and forth with a 5 kg roller, and then aged at room temperature (23°C) for 20 hours. The adhesive strength was measured using a Shimadzu Corporation precision universal testing machine "Autograph AGS-1kNX, 50 N load cell" at 23°C and 50% humidity, at a peel speed of 0.3 m / min, and at a peel angle of 180°. Similarly, an unused polyester-based adhesive tape (not attached to a release sheet) was attached to an aluminum sheet, and the initial adhesive strength was measured at a peel angle of 180°. From these measurements, the residual adhesion rate was calculated. Residual adhesion rate (%) = (adhesive strength / initial adhesive strength) × 100

[0117] (peel strength from adhesive layer) Using a Baker applicator, a thermosetting epoxy adhesive "FM-1502" (manufactured by Totoku Toryo Co., Ltd., epoxy resin composition 20% by mass, silicon dioxide 60% by mass, solvent (methyl ethyl ketone), solids concentration 80% by mass) was applied to the release surface of the release sheet so that the film thickness after drying would be 50 μm. After the adhesive was applied, it was dried at 130°C for 5 minutes in a constant temperature dryer to produce a transfer sheet having an adhesive layer on the release sheet. The produced transfer sheet was stored at room temperature (23°C) for 2 weeks. The transfer sheet was cut into a size of 25 x 150 mm, and the adhesive layer surface was placed against the roughened surface of a 30 x 160 mm piece of electrolytic copper foil "CF-T4X-SV-12" (manufactured by Fukuda Metal Foil & Powder Co., Ltd., thickness 12 μm). The foil was then pressed at 100°C and 2 MPa for 5 minutes using an AS ONE high-temperature heat press "H400-15" to prepare a test specimen. The peel strength between the adhesive layer and the release sheet of the test specimen was measured using a Shimadzu Corporation precision universal testing machine "Autograph AGS-1kNX, 50N load cell" at a peel speed of 0.3 m / min and a peel angle of 180° in an environment of 23°C and 50% humidity. Measurements were performed on test specimens that had been left to stand at room temperature (23°C) for 30 minutes after preparation, and on test specimens that had been stored at room temperature (23°C) for 2 weeks after preparation.

[0118] (strength) The release surface (release agent layer) of the release sheet was rubbed strongly with a finger five times, and the rubbed area was visually observed. The evaluation criteria are as follows: ○: No smearing (clouding of the rubbed area) or rub-off (falling off of the rubbed area) occurred. ×: Smear or rub-off occurs.

[0119] (exterior) The release sheet was visually observed immediately after the formation of the release agent layer. Compared to the base sheet before the formation of the release agent layer, those that appeared cloudy were marked with "X", those that appeared slightly cloudy but did not pose a problem in practical use were marked with "Δ", and those that remained unchanged were marked with "◯".

[0120] <Synthesis of copolymer> Copolymer No.1 A flask equipped with an argon gas inlet tube and a stirrer was charged with SA (570.0 g), AIBN (0.433 g), and AcOEt (380.0 g). After replacing the atmosphere with argon, BTEE (3.00 g) was added and the reaction was carried out at 60°C for 24 hours to polymerize the A block. The polymerization rate was 96%.

[0121] A mixture of 4-HBA (30.0 g), AIBN (0.098 g), and AcOEt (20.0 g), which had been previously purged with argon, was added to the reaction solution, and the mixture was reacted at 60°C for 16 hours to polymerize the B block. The conversion was 85%.

[0122] After the reaction was completed, the mixture was poured into stirred MeOH. The precipitated polymer was filtered by suction and dried to obtain Copolymer No. 1. The resulting Copolymer No. 1 had an Mw of 50,770 and a PDI of 1.42. The contents of each component in the polymer were SA 91.1 mol% (95.9 mass%) and 4-HBA 8.9 mol% (4.2 mass%). Toluene was added to the resulting Copolymer No. 1 to adjust the solids concentration to 52.0 mass%.

[0123] Copolymer No.2 SA (19.6 g), 4-HBA (0.4 g), AIBN (13.1 mg), and AcOEt (13.4 g) were placed in a test tube equipped with a stirrer, and after replacing the atmosphere with argon, BTEE (120.0 mg) was added and the reaction was carried out at 60°C for 24 hours. The polymerization rate was 89%.

[0124] After the reaction was completed, the mixture was poured into stirred MeOH. The precipitated polymer was filtered by suction and dried to obtain Copolymer No. 2. The resulting Copolymer No. 2 had an Mw of 46,510 and a PDI of 1.46. The contents of each component in the polymer were SA 95.2 mol% (97.8 mass%) and 4-HBA 4.8 mol% (2.2 mass%). Toluene was added to the resulting Copolymer No. 2 to adjust the solids concentration to 37.5 mass%.

[0125] Copolymer No.3 SA (9.5 g), LA (9.5 g), AIBN (13.1 mg), and AcOEt (12.7 g) were placed in a test tube equipped with a stirrer, and after replacing the atmosphere with argon, BTEE (120.0 mg) was added. The reaction was carried out at 60°C for 20 hours to polymerize the A block. The polymerization rate was 96%.

[0126] A mixture of 4-HBA (1.0 g), AIBN (6.6 mg), and AcOEt (0.7 g), which had been previously purged with argon, was added to the reaction solution, and the mixture was reacted at 60°C for 22 hours to polymerize the B block. The conversion was 81%.

[0127] After the reaction was completed, the mixture was poured into stirred MeOH. The precipitated polymer was filtered by suction and dried to obtain Copolymer No. 3. The resulting Copolymer No. 3 had an Mw of 48,782 and a PDI of 1.44. The contents of each component in the polymer were SA 39.3 mol% (47.9 mass%), LA 53.1 mol% (47.9 mass%), and 4-HBA 7.6 mol% (4.1 mass%). Toluene was added to the resulting Copolymer No. 3 to adjust the solids concentration to 31.2 mass%.

[0128] Copolymer No.4 A test tube equipped with a stirrer was charged with SMA (19.0 g), AIBN (13.1 mg), and AcOEt (12.7 g). After replacing the atmosphere with argon, BTEE (120.0 mg) and DBDT (73.9 mg) were added and the reaction was carried out at 60°C for 21 hours to polymerize the A block. The polymerization rate was 96%. A mixture of 2-HEMA (1.0 g), AIBN (6.6 mg), and AcOEt (0.7 g), which had been previously purged with argon, was added to the reaction solution, and the mixture was reacted at 60°C for 22 hours to polymerize the B block. The conversion was 81%. After the reaction was completed, the mixture was poured into stirred MeOH. The precipitated polymer was filtered by suction and dried to obtain Copolymer No. 4. The resulting Copolymer No. 4 had an Mw of 48,542 and a PDI of 1.21. The contents of each component in the polymer were SMA 89.3 mol% (95.6 mass%) and 2-HEMA 10.7 mol% (4.4 mass%). Toluene was added to the resulting Copolymer No. 4 to adjust the solids concentration to 34.6 mass%.

[0129] <Preparation of Aminoalkyd Resin Composition> The aminoalkyd resin components, copolymer, and acid catalyst were mixed to obtain the formulation (solid content equivalent) shown in Table 1, and then diluted with a solvent (toluene, n-heptane, methyl ethyl ketone) to a solid content of 1% by mass to prepare an aminoalkyd resin composition.

[0130] [Table 1] Tesfine (registered trademark) 305: manufactured by Hitachi Chemical Co., Ltd., a composition containing components of a long-chain alkyl-containing aminoalkyd resin, solvents (toluene, methanol, xylene, isobutanol), solid content concentration 50% by mass U-Ban (registered trademark) 20SE60: manufactured by Mitsui Chemicals, Inc., butylated melamine resin, solvent (n-butanol, xylene, ethylbenzene), solid content concentration 60% by mass Dryer 900: Hitachi Chemical Co., Ltd., acid catalyst (toluene solution of paratoluenesulfonic acid, solid content 50% by mass)

[0131] <Preparation of release sheet> The aminoalkyd resin composition was applied to a PET (polyethylene terephthalate) film "E5100" (manufactured by Toyobo Co., Ltd., thickness 50 μm) using a wire bar so that the thickness after drying would be 0.1 μm, and the composition was dried and cured at 150°C for 30 seconds to produce a release sheet. The evaluation results of the obtained release sheet are shown in Table 1.

[0132] In release sheets Nos. 1 to 7, the release agent layer is formed from an aminoalkyd resin composition containing a block copolymer having an A block having a structural unit (a-1) represented by general formula (1) and a B block having a structural unit (b-1) derived from a (meth)acrylic monomer having a reactive functional group. These release sheets Nos. 1 to 7 have excellent heat resistance, strength, and appearance of the release agent layer, a small normal peel force, and a high residual adhesion rate. Furthermore, these release sheets Nos. 1 to 7 showed a suppressed increase in peel force even when exposed to high temperatures while in contact with a pressure-sensitive adhesive. Furthermore, these release sheets Nos. 1 to 7 were able to be easily peeled from the adhesive layer after transferring the adhesive layer formed on the release sheet to copper foil and storing for 30 minutes or two weeks.

[0133] Release sheet No. 8 has a release agent layer formed from an aminoalkyd resin composition that does not contain a (meth)acrylic copolymer. This release sheet No. 8 has a high normal peel strength and a low residual adhesion rate. Furthermore, after the adhesive layer formed on the release sheet was transferred to copper foil, this release sheet No. 8 could not be easily peeled from the adhesive layer.

[0134] In release sheets Nos. 9 and 10, the release agent layer is formed from a composition that does not contain an aminoalkyd resin component. These release sheets Nos. 9 and 10 have poor release agent layer strength and a low residual adhesion rate. Furthermore, with these release sheets Nos. 9 and 10, after the adhesive layer formed on the release sheet was transferred to the copper foil, it was not easy to peel the adhesive layer from the adhesive layer.

[0135] Release sheet No. 11 is a case in which the (meth)acrylic copolymer blended in the aminoalkyd resin composition that forms the release agent layer is a random copolymer. This release sheet No. 11 has a low normal peel strength but a low residual adhesion rate. Furthermore, when this release sheet No. 11 was exposed to high temperatures while in contact with an adhesive, the peel strength increased significantly.

[0136] The present invention includes the following aspects.

[0137] (Aspect 1) A release sheet comprising a substrate sheet and a release agent layer formed on at least one surface of the substrate sheet, wherein the release agent layer is formed from an aminoalkyd resin composition containing a (meth)acrylic block copolymer, and the (meth)acrylic block copolymer is a block copolymer having an A block having a structural unit (a-1) represented by general formula (1) and a B block having a structural unit (b-1) derived from a (meth)acrylic monomer having a reactive functional group.

[0138] (Aspect 2) 2. The release sheet according to embodiment 1, wherein the content of the structural unit (a-1) is 40% by mass or more in 100% by mass of the A block.

[0139] (Aspect 3) 3. The release sheet according to aspect 1 or 2, wherein the mass ratio of the A block to the B block (A block / B block) in the block copolymer is 80 / 20 to 99.99 / 0.01.

[0140] (Aspect 4) 4. The release sheet according to any one of Aspects 1 to 3, wherein the aminoalkyd resin composition contains a melamine resin as a constituent component of the aminoalkyd resin.

[0141] (Aspect 5) 5. The release sheet according to any one of aspects 1 to 4, wherein the content of the block copolymer in the aminoalkyd resin composition is 1 part by mass to 50 parts by mass per 100 parts by mass of the aminoalkyd resin components.

[0142] (Aspect 6) 6. The release sheet according to any one of Aspects 1 to 5, wherein the aminoalkyd resin composition contains an acidic catalyst.

[0143] (Aspect 7) 7. The release sheet according to any one of aspects 1 to 6, wherein the block copolymer is obtained by living radical polymerization and has a molecular weight distribution (Mw / Mn) of 3.0 or less.

[0144] (Aspect 8) The release sheet according to any one of aspects 1 to 7, which is used in applications where it is exposed to an atmosphere of 100° C. or higher while attached to a pressure-sensitive adhesive layer or an adhesive layer.

[0145] (Aspect 9) R in the formula (1) 11 is an alkyl group having 14 to 26 carbon atoms, 9. The release sheet according to any one of aspects 1 to 8, wherein the content of the structural unit (a-1) is 80% by mass or more in 100% by mass of the A block.

[0146] (Aspect 10) The release sheet according to any one of aspects 1 to 9, wherein the A block contains, as the structural unit (a-1), a structural unit (a-1-1) represented by formula (1-1) and a structural unit (a-1-2) represented by formula (1-2).

Claims

1. A substrate sheet and a release agent layer formed on at least one surface of the substrate sheet, the release agent layer is formed from an aminoalkyd resin composition containing an aminoalkyd resin component and a (meth)acrylic block copolymer, the content of the block copolymer in the aminoalkyd resin composition is 1 part by mass to 50 parts by mass per 100 parts by mass of the aminoalkyd resin components, the (meth)acrylic block copolymer is a block copolymer having an A block having a structural unit (a-1) represented by general formula (1) and a B block having a structural unit (b-1) derived from a (meth)acrylic monomer having a hydroxy group, the content of the structural unit (a-1) is 90% by mass or more and 99.5% by mass or less in 100% by mass of the block copolymer, A release sheet characterized in that the content of the structural unit (b-1) is 0.5% by mass or more and 10% by mass or less in 100% by mass of the block copolymer. 【Chemistry 1】 [In formula (1), R 11 represents an alkyl group having 12 to 28 carbon atoms. 12 represents a hydrogen atom or a methyl group.

2. 2. The release sheet according to claim 1, wherein the content of the structural unit (a-1) is 40% by mass or more in 100% by mass of the A block.

3. 3. The release sheet according to claim 1, wherein the mass ratio of the A block to the B block (A block / B block) in the block copolymer is 80 / 20 to 99.99 / 0.

01.

4. The release sheet according to any one of claims 1 to 3, wherein the aminoalkyd resin composition contains a melamine resin as a constituent component of the aminoalkyd resin.

5. A release sheet described in any one of claims 1 to 4, wherein the weight average molecular weight of the block copolymer is 5,000 or more and 70,000 or less.

6. The release sheet according to any one of claims 1 to 5, wherein the aminoalkyd resin composition contains an acidic catalyst.

7. The release sheet according to any one of claims 1 to 6, wherein the block copolymer is obtained by living radical polymerization and has a molecular weight distribution (Mw / Mn) of 3.0 or less.

8. The release sheet according to any one of claims 1 to 7, which is used in applications where it is exposed to an atmosphere of 100°C or higher while attached to a pressure-sensitive adhesive layer or an adhesive layer.

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