Surface-protective composition and surface-protective film

Abstract

There is provided a surface-protective composition, wherein the difference between a water contact angle X1 measured by the following method 1 and a water contact angle X2 measured by the following method 2 (X1-X2) is 10° or more. (Method 1) A film 1 composed of the surface-protective composition is formed on a substrate. Then, in accordance with JIS R3257:1999, purified water is dropped onto the film 1, and the water contact angle of the film 1 is measured immediately after the dropping and is defined as a water contact angle X1. (Method 2) A film 1 is obtained in the same manner as (Method 1). Light is applied to the obtained film 1 using a high‑pressure mercury lamp under the conditions of an illuminance of 20 mW / cm2, an irradiation time of 150 seconds, and an integrated light dose of 3000 mJ / cm2, thereby obtaining a film 2. Then, in accordance with JIS R 3257:1999, the water contact angle of the film 2 is measured 60 seconds after dropping purified water onto the film 2, and is defined as a water contact angle X2.

Description

Surface protection composition and surface protection film

[0001] This invention relates to a surface protection composition and a surface protection film.

[0002] Examples of surface protective film technologies used in the manufacture of electronic devices include those described in Patent Documents 1 and 2.

[0003] Patent Document 1 describes a semiconductor processing tape comprising a water-soluble film containing a polymer compound with a weight-average molecular weight of 200,000 or more and a low-molecular-weight compound with a molecular weight of 800 or less, laminated with a surface protection tape that protects the circuit surface of a semiconductor wafer. Furthermore, Patent Document 1 describes that it is possible to provide a semiconductor processing tape that achieves both grooving resistance and wafer adhesion while enabling removal by washing with unheated water.

[0004] Patent Document 2 describes a surface protection composition for protecting at least one side of a substrate, comprising a polymer having hydrophilic groups in its molecule and a compound that generates an acid or a base upon heating or irradiation with active energy rays. Furthermore, Patent Document 2 describes that it is possible to provide a surface protection composition for forming a protective layer that covers and protects at least one side of a substrate in a manufactured electronic component device, and which can then be removed relatively easily upon contact with a liquid containing water.

[0005] Japanese Patent Publication No. 2023-043723, International Publication No. 2023 / 195445

[0006] The present invention provides a surface protection composition that is water-resistant and can form a water-washable protective film after at least one treatment selected from light irradiation and heating.

[0007] The inventors diligently conducted research to achieve the above objectives. As a result, they discovered that by setting the difference in water contact angle measured under specific conditions within a predetermined range in a surface protection composition, it is possible to form a protective film that is water-resistant and washable with water after at least one treatment selected from light irradiation and heating.

[0008] [1] A surface protection composition having a water contact angle X measured by the following method 1 ２ and a water contact angle X measured by the following method 2 ２ with a difference (X １ - X ２ ) of 10° or more. (Method 1) A film 1 made of the surface protection composition is formed on a substrate. Then, in accordance with JIS R3257:1999, purified water is dropped onto the film 1, and the water contact angle of the film 1 immediately after dropping is measured to obtain a water contact angle X １ . (Method 2) A film 1 is obtained in the same manner as in (Method 1). The obtained film 1 is irradiated with light using a high-pressure mercury lamp under the conditions of an illuminance of 20 mW / cm ２ , an irradiation time of 150 seconds, and an integrated light amount of 3000 mJ / cm ２ to obtain a film 2. Then, in accordance with JIS R3257:1999, purified water is dropped onto the film 2, and the water contact angle of the film 2 60 seconds after dropping is measured to obtain a water contact angle X ２ . [2] The surface protection composition according to [1], wherein the water contact angle X １ is 60° or more. [3] The surface protection composition according to [1] or [2], wherein the water contact angle X ２ is 75° or less. [4] The surface protection composition according to any one of [1] to [3], wherein the surface protection composition contains a polymer (A) and an acid generator (B) containing at least one selected from a photoacid generator and a thermal acid generator. [5] The surface protection composition according to [4], wherein the acid generator (B) contains a photoacid generator. [6] The surface protection composition according to [5], wherein the photoacid generator contains one or more selected from a sulfonium salt type photoacid generator, an iodonium salt type photoacid generator, and a nonionic type photoacid generator. [7] The surface protection composition according to any one of [4] to [6], wherein the content of the acid generator (B) in the surface protection composition is 1.0 part by mass or more and 50.0 parts by mass or less with respect to 100 parts by mass of the polymer (A). [8] With respect to the film 1, an illuminance of 20 mW / cm ２ , an irradiation time of 150 seconds, and an integrated light amount of 3000 mJ / cm ２A surface protection composition according to any one of [4] to [7], wherein when light is irradiated using a high-pressure mercury lamp under the conditions, the polymer (A) has a hydrophilic group, and the hydrophilic group comprises at least one selected from the group consisting of a hydroxyl group and a carboxyl group. [9] A surface protection composition according to any one of [4] to [8], wherein the polymer (A) comprises one or more selected from the group consisting of a polymer containing a structural unit derived from (meth)acrylate (a), polyvinylpyrrolidone, and polyethylene oxide.

[10] A surface protection composition according to any one of [4] to [9], wherein the polymer (A) comprises a structural unit (a) having one or more degradable groups selected from the group consisting of an acid-degradable group and a base-degradable group.

[11] A surface protection composition according to

[10] , wherein the functional group protected by the degradable group comprises at least one selected from the group consisting of a carboxyl group and a hydroxyl group.

[12] The surface protection composition according to

[10] or

[11] , wherein the degradable group comprises at least one selected from the group consisting of a group comprising an ether bond, a group comprising an ester bond, and an alkyl group.

[13] The surface protection composition according to

[12] , wherein the group comprising an ether bond comprises an alkyl group having 1 to 8 carbon atoms.

[14] The surface protection composition according to any one of [4] to

[13] , wherein the weight-average molecular weight (Mw) of the polymer (A), measured by gel permeation chromatography, is 5,000 to 10,000,000.

[15] The surface protection composition according to any one of [1] to

[14] , wherein, when the following (Method 3) is performed, the film made of the surface protection composition is insoluble in water and adheres closely to the substrate. (Method 3) A film 3 with a thickness of 5 ± 5 μm made of the surface protection composition is formed on the substrate. Next, the laminate consisting of the substrate and the film 3 is immersed in purified water for 10 minutes, then the laminate is removed from the water and the state of the film 3 is observed.

[16] A surface protection composition according to any one of [1] to

[15] , used to form a surface protection film that protects the surface of an electronic component.

[17] The surface protection composition according to

[16] , wherein the surface protection film is a surface protection film that protects the surface of an electronic component and is ultimately removed.

[18] A surface protective film comprising a film formed by any of the surface protective compositions described in [1] to

[17] .

[0009] According to the present invention, a surface protection composition can be provided that has water resistance and can form a protective film that can be washed with water after at least one treatment selected from light irradiation and heating.

[0010] Embodiments of the present invention will be described below. In this specification, unless otherwise specified, "A to B" indicating a numerical range means A or greater and B or less.

[0011] <Surface protection composition> The surface protection composition of this embodiment has a water contact angle X according to the method 1 below. １ And, the water contact angle X by method 2 below ２ The difference (X １ -X ２ The temperature is 10° or higher. According to the surface protection composition of this embodiment, a protective film can be formed that is water-resistant and washable with water after at least one treatment selected from light irradiation and heating.

[0012] (Method 1) A film 1 made of the surface protective composition is formed on the substrate. Then, in accordance with JIS R3257:1999, purified water is dropped onto the film 1, and the water contact angle of the film 1 immediately after dropping is measured, and the water contact angle X １ (Method 2) Obtain film 1 in the same manner as in (Method 1). Apply an illuminance of 20 mW / cm to the obtained film 1. ２ Irradiation time 150 seconds, integrated light intensity 3000 mJ / cm² ２ Under these conditions, light is irradiated using a high-pressure mercury lamp to obtain film 2. Next, in accordance with JIS R3257:1999, purified water is dropped onto film 2 and the water contact angle of film 2 is measured 60 seconds later, and the water contact angle X is obtained. ２ In this embodiment, for example, a glass plate, a silicon wafer, or the like can be used as the substrate.

[0013] The mechanism by which the surface protection composition of this embodiment solves the above-mentioned problems is not clear, but the difference (X １ -X ２It is believed that the wettability of the resulting protective film changes when the value falls within the above numerical range. This is thought to improve the balance between the water resistance and switching water washability of the resulting protective film. In this specification, switching water washability means the characteristic that the resulting protective film can be washed with water after being subjected to at least one treatment selected from light irradiation and heating.

[0014] The difference in water contact angle (X) of the surface protection composition of this embodiment １ -X ２ The difference in the water contact angle (X) of the surface protective composition of this embodiment is 10° or more, and from the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film, it is preferably 13° or more, more preferably 15° or more, even more preferably 17° or more, even more preferably 18° or more, even more preferably 20° or more, and preferably 140° or less, more preferably 120° or less, even more preferably 100° or less, even more preferably 80° or less, and even more preferably 75° or less. １ -X ２ The difference in water contact angle (X) of the surface protection composition is preferably 13° to 140°, more preferably 15° to 120°, even more preferably 17° to 100°, even more preferably 18° to 80°, and even more preferably 20° to 75°, from the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film. １ -X ２ This can be controlled by adjusting the resin composition of the polymer in the surface protective film composition, the type and amount ratio of additives, etc.

[0015] The difference in the water contact angle (X １ -X ２ By having the above numerical range, a surface protection composition can be obtained in which the balance between the water resistance and switching water washability of the resulting film is improved.

[0016] Hereinafter, after performing at least one treatment selected from light irradiation and heating on the obtained protective film, the property that the obtained protective film can be washed with water is called switching water washability.

[0017] The water contact angle X of the surface protection composition of the present embodiment １ From the viewpoint of further improving the water resistance of the obtained protective film, it is preferably 60° or more, more preferably 62° or more, still more preferably 64° or more, and even more preferably 65° or more. The water contact angle X １ There is no particular limitation on the upper limit value, and for example, it may be 140° or less, 120° or less, 100° or less, or 90° or less. The water contact angle X of the surface protection composition of the present embodiment １ From the viewpoint of further improving the water resistance of the obtained protective film, it is preferably 60° or more and 140° or less, more preferably 62° or more and 120° or less, more preferably 64° or more and 100° or less, and even more preferably 65° or more and 90° or less.

[0018] The water contact angle X of the surface protection composition of the present embodiment ２ From the viewpoint of further improving the switching water washability of the obtained protective film, it is preferably 75° or less, more preferably 70° or less, still more preferably 65° or less, even more preferably 60° or less, even more preferably 59.9° or less, even more preferably 59.8° or less, and even more preferably 59.7° or less. Also, from the viewpoint of reliably realizing good switching water washability, it is preferably 52° or less, more preferably 50° or less, still more preferably 45° or less, and most preferably 40° or less. The water contact angle X ２ There is no particular limitation on the lower limit value, and for example, it may be 0° or more, 2° or more, 5° or more, 10° or more, or 20° or more. The water contact angle X of the surface protection composition of the present embodiment ２From the viewpoint of further improving the switching water washability of the resulting protective film, the preferred temperature is 0° to 75°, more preferably 0° to 70°, even more preferably 0° to 65°, even more preferably 0° to 60°, even more preferably 2° to 59.9°, even more preferably 5° to 59.8°, and even more preferably 5° to 59.7°. Furthermore, from the viewpoint of reliably achieving good switching water washability, the preferred temperature is 10° to 52°, more preferably 10° to 50°, even more preferably 10° to 45°, and most preferably 20° to 40°.

[0019] The water used for washing the resulting protective film is preferably one or more selected from the group consisting of ion-exchanged water, pure water, purified water, and distilled water, from the viewpoint of suppressing damage to electronic components. Furthermore, the pH of the water used for washing the resulting protective film, as measured in accordance with JIS Z 8802:2011, is preferably 5.0 to 9.0, more preferably 5.5 to 8.0, even more preferably 6.0 to 7.5, and even more preferably 6.0 to 7.0, from the viewpoint of suppressing damage to electronic components.

[0020] The surface protection composition of this embodiment preferably comprises a polymer (A) and an acid generator (B) containing at least one selected from a photoacid generator and a thermal acid generator, from the viewpoint of further improving the balance between the water resistance and switching water washability of the resulting protective film. By comprising the polymer (A) and the acid generator (B) in the surface protection composition of this embodiment, when the resulting protective film is subjected to at least one treatment selected from light irradiation and heating, the acid generator (B) generates acid, which can decompose the degradable groups in the polymer (A) described later. This further improves the hydrophilicity of the protective film and further improves the water washability of the protective film.

[0021] (Polymer (A)) From the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film, Polymer (A) preferably contains one or more selected from the group consisting of a polymer containing a structural unit derived from (meth)acrylate (a), polyvinylpyrrolidone, and polyethylene oxide, and more preferably contains a polymer containing a structural unit derived from (meth)acrylate (a).

[0022] From the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film, Polymer (A) preferably contains a structural unit (a) having one or more decomposable groups selected from the group consisting of an acid-decomposable group and a base-decomposable group, and more preferably contains a structural unit (a) having an acid-decomposable group. Further, the functional group protected by the decomposable group in Polymer (A) contains at least one selected from the group consisting of a carboxyl group and a hydroxyl group.

[0023] In the surface protective composition of the present embodiment, from the viewpoint of further improving the switching water washability of the resulting protective film, with respect to the film 1 formed on the substrate using the surface protective composition of the present embodiment, at an illuminance of 20 mW / cm ２ , irradiation time of 150 seconds, integrated light amount of 3000 mJ / cm ２ When light is irradiated using a high-pressure mercury lamp under the conditions of, Polymer (A) has a hydrophilic group, and the hydrophilic group contains at least one selected from the group consisting of a hydroxyl group and a carboxyl group.

[0024] The acid-decomposable group in Polymer (A) is preferably decomposed by the acid generated by the acid generator (B) to generate a hydrophilic functional group when at least one treatment selected from light irradiation and heating is performed on the protective film composed of the surface protective composition, from the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film. Thereby, when at least one treatment selected from light irradiation and heating is performed on the protective film composed of the surface protective composition, the acid generator (B) generates an acid, and the acid-decomposable group possessed by Polymer (A) is eliminated, that is, acid-decomposed, to generate a hydrophilic group, and the switching water washability can be improved.

[0025] From the viewpoint of further improving the balance between the water resistance and switching water washability of the resulting protective film, the degradable groups in polymer (A) preferably include at least one selected from the group consisting of a group containing an ether bond, a group containing an ester bond, and an alkyl group, more preferably include at least one selected from the group consisting of a group containing an ether bond and an alkyl group, even more preferably include a group containing an ether bond that includes an alkyl group having 1 to 8 carbon atoms, and even more preferably include a group containing an ether bond that includes an alkyl group having 1 to 4 carbon atoms.

[0026] The degradable groups in polymer (A) preferably include groups containing ether bonds. This ensures that the acid-degradable groups are more reliably deprotected after at least one treatment selected from light irradiation and heating, thereby improving the switching water washability of the resulting protective film. From the viewpoint of further improving the switching water washability of the resulting protective film, the ether-containing group preferably includes one or more selected from the group consisting of ethoxyethyl group, propoxyethyl group, isopropoxyethyl group, butoxyethyl group, isobutoxyethyl group, (cyclohexyloxy)ethyl group, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl group, and tetrahydropyranyl group. More preferably, it includes one or more selected from the group consisting of ethoxyethyl group, propoxyethyl group, isopropoxyethyl group, butoxyethyl group, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl group, and tetrahydropyranyl group. Even more preferably, it includes one or more selected from the group consisting of ethoxyethyl group, propoxyethyl group, isopropoxyethyl group, butoxyethyl group, and (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl group.

[0027] Furthermore, the group containing the ether bond may also be a group containing an ether bond and a cyclic structure, or a group containing an ether bond in a linear or branched structure. The group containing an ether bond in a linear or branched structure preferably contains an alkylene group having 1 to 4 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms, even more preferably an alkylene group having 1 to 2 carbon atoms, even more preferably an ethylene group, and even more preferably a 1,1-ethylene group. The group containing the ether bond and a cyclic structure preferably contains a cyclic structure of 3 to 10 membered rings, more preferably a cyclic structure of 3 to 8 membered rings, and even more preferably a cyclic structure of 3 to 6 membered rings. Furthermore, if the group containing the ether bond and a cyclic structure contains an ether bond in the cyclic structure, the group containing the ether bond and a cyclic structure preferably contains at least one oxygen atom in the cyclic structure, more preferably one or two oxygen atoms in the cyclic structure, and even more preferably at least one cyclic structure selected from the group consisting of dioxolane ring structures and dioxane ring structures.

[0028] A polymer containing structural units derived from (meth)acrylate(a) preferably contains structural units (a) derived from (meth)acrylate(a) that have a degradable group. The content of structural units (a) derived from (meth)acrylate(a) that have a degradable group in a polymer containing structural units derived from (meth)acrylate(a) is preferably 5 mol% to 100 mol%, more preferably 8 mol% to 100 mol%, and even more preferably 10 mol% to 100 mol%, when the total content of structural units in the polymer containing structural units derived from (meth)acrylate(a) is taken as 100 mol%.

[0029] If polymer (A) includes a polymer containing structural units derived from (meth)acrylate (a), the polymer containing structural units derived from (meth)acrylate (a) may further include structural units (b) derived from monomer (b) that does not have a degradable group. From the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film, structural units (b) preferably include structural units derived from one or more monomers (b) selected from the group consisting of monomers containing an amide group, (meth)acrylates containing an ether linkage, (meth)acrylates containing a vinyl ether group, (meth)acrylates containing an amino group, (meth)acrylates containing a carboxyl group, (meth)acrylates containing a ketone group, and (meth)acrylates containing an alkyl group, and more preferably include structural units derived from one or more monomers (b) selected from the group consisting of monomers containing an amide group, (meth)acrylates containing an alkyl group, and (meth)acrylates containing a carboxyl group. The monomer containing the amide group preferably comprises one or more selected from the group consisting of (meth)acrylamide, (meth)acryloylmorpholine, N,N-dimethyl(meth)acrylamide, and N-(2-hydroxyethyl)(meth)acrylamide, more preferably comprising (meth)acryloylmorpholine, and even more preferably comprising acryloylmorpholine. The (meth)acrylate containing the ether linkage preferably comprises 2-[2-(2-methoxyethoxy)ethoxy]ethyl (meth)acrylate. The alkyl group-containing (meth)acrylate preferably comprises one or more selected from the group consisting of isobutyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, isopropyl (meth)acrylate, t-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, more preferably comprising 2-ethylhexyl (meth)acrylate, and even more preferably comprising 2-ethylhexyl acrylate.The (meth)acrylate containing a ketone group preferably comprises one or more selected from the group consisting of 2-(acetoacetyloxy)ethyl (meth)acrylate and diacetone acrylamide, and more preferably comprises 2-(acetoacetyloxy)ethyl (meth)acrylate. The (meth)acrylate containing a carboxyl group preferably comprises one or more selected from the group consisting of (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinic acid, and 2-(meth)acryloyloxyethyl hexahydrophthalic acid, and more preferably comprises (meth)acrylic acid.

[0030] When a polymer containing structural units derived from (meth)acrylate (a) further contains structural units (b) derived from monomer (b), the content of structural units (b) is preferably 1 mol% to 50 mol%, more preferably 2 mol% to 40 mol%, even more preferably 3 mol% to 35 mol%, even more preferably 4 mol% to 30 mol%, and even more preferably 5 mol% to 20 mol%, when the total content of structural units in the polymer containing structural units derived from (meth)acrylate (a) is taken as 100 mol%.

[0031] If the polymer containing structural units derived from (meth)acrylate (a) contains structural units derived from one or more monomers (b) selected from the group consisting of (meth)acrylate containing a vinyl ether group, (meth)acrylate containing an amino group, (meth)acrylate containing a carboxyl group, and (meth)acrylate containing a ketone group, the surface protection composition of this embodiment may also contain an acid-degradable crosslinking agent (C) described later.

[0032] The weight-average molecular weight (Mw) of polymer (A), measured by gel permeation chromatography and converted to polystyrene, is preferably 5,000 to 10,000,000, more preferably 7,500 to 1,000,000, even more preferably 10,000 to 750,000, and even more preferably 12,500 to 500,000, and even more preferably 15,000 to 250,000, more preferably 17,500 to 150,000, and even more preferably 20,000 to 100,000, from the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film.

[0033] The Mw / Mn ratio, calculated from the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymer (A) measured by gel permeation chromatography in polystyrene terms, is preferably 1.0 to 10.0, more preferably 1.2 to 8.0, even more preferably 1.5 to 6.0, and even more preferably 2.0 to 4.5, from the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film, and preferably 2.1 to 3.5 from the viewpoint of further improving the switching water washability of the resulting protective film.

[0034] The weight-average molecular weight (Mw) and Mw / Mn of polymer (A), measured by gel permeation chromatography in terms of polystyrene, can be adjusted in the synthesis of polymer (A) described later by appropriately adjusting conditions such as the type of polymerization initiator, polymerization temperature, polymerization pressure, and polymerization time.

[0035] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymer (A) can be measured, for example, by gel permeation chromatography (GPC) under the following conditions: (Conditions) Detector: Differential refractive index detector Eluent: Tetrahydrofuran Column temperature: 40°C Flow rate: 1.0 mL / min

[0036] (Method for synthesizing polymer (A)) The polymer (A) of this embodiment can be synthesized by any known method. For example, if polymer (A) is a polymer containing structural units derived from (meth)acrylate (a) and structural units (b) derived from monomer (b), it can be obtained by polymerizing (meth)acrylate (a) and monomer (b) in the presence of any known polymerization catalyst or polymerization initiator. As the polymerization initiator, one or more selected from the group consisting of azo compounds, organic peroxides, and photopolymerization initiators can be used. As the azo compound, for example, 2,2'-azobis(isobutyronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile) can be used. When an azo compound is used as the polymerization initiator, for example, the monomer can be polymerized by heating a solution containing (meth)acrylate (a), monomer (b), and azo compound at 50 to 80°C or 50 to 110°C for 1 to 20 hours. Examples of photopolymerization initiators include 1-hydroxycyclohexylphenyl ketone and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. When using a photopolymerization initiator, for example, a solution containing (meth)acrylate (a), monomer (b), and photopolymerization initiator can be exposed to UVA at an intensity of 20-50 mW / cm². ２ By irradiating with UV light for approximately 10 to 60 minutes, monomers can be polymerized. As a commercially available organic peroxide, Perbutyl® O (manufactured by NOF Corporation) can be used.

[0037] (Acid Generator (B)) The acid generator (B) of this embodiment comprises at least one selected from a photoacid generator and a thermal acid generator, and preferably includes a photoacid generator from the viewpoint of reducing thermal damage to the adherend when generating acid from the acid generator.

[0038] The photoacid generator of this embodiment preferably comprises one or more selected from sulfonium salt type photoacid generators, iodonium salt type photoacid generators, and nonionic type photoacid generators, from the viewpoint of further improving the balance of water resistance and switching water washability of the resulting protective film; more preferably comprises one or more selected from sulfonium salt type photoacid generators and nonionic type photoacid generators; even more preferably comprises one or more selected from sulfonium salt type photoacid generators and nonionic type photoacid generators having a diazomethane structure; and even more preferably comprises a sulfonium salt type photoacid generator.

[0039] Examples of sulfonium salt type photoacid generators include triarylsulfonium salts and diarylsulfonium salts, preferably containing a triarylsulfonium salt, more preferably containing a triarylsulfonium salt containing one selected from the group consisting of hexafluorophosphate, hexafluoroantimonic acid, and tetrakis(pentafluorophenyl)borate as an anion, and even more preferably containing a triarylsulfonium salt containing tetrakis(pentafluorophenyl)borate as an anion. Examples of commercially available products include CPI-100B (manufactured by Sunapro Co., Ltd.) and CPI-110B (manufactured by Sunapro Co., Ltd.).

[0040] The content of the acid generator (B) in the surface protection composition of this embodiment is preferably 1.0 part by mass or more and 50.0 parts by mass or less, more preferably 1.5 parts by mass or more and 47.5 parts by mass or less, even more preferably 2.5 parts by mass or more and 45.0 parts by mass or less, even more preferably 3.5 parts by mass or more and 42.5 parts by mass or less, and even more preferably 4.5 parts by mass or more and 40.0 parts by mass or less, per 100 parts by mass of polymer (A).

[0041] (Acid-degradable crosslinking agent (C)) If the polymer containing structural units derived from (meth)acrylate (a) further contains structural units derived from one or more monomers (b) selected from the group consisting of (meth)acrylate containing vinyl ether groups, (meth)acrylate containing amino groups, (meth)acrylate containing carboxyl groups, and (meth)acrylate containing ketone groups, the surface protective composition of this embodiment may also contain an acid-degradable crosslinking agent (C). The acid-degradable crosslinking agent (C) of this embodiment is a crosslinking agent that reacts with carboxyl groups, ketone groups, vinyl ether groups, and amino groups (hereinafter also referred to as crosslinkable groups) contained in the structural units derived from monomer (b) in polymer (A), and can form an acid-degradable crosslinked structure. The acid-degradable crosslinked structure is formed, for example, by a crosslinking reaction between the crosslinkable groups in polymer (A) and the acid-degradable crosslinking agent (C) upon heating. The crosslinking reaction between the crosslinkable groups in polymer (A) and the acid-degradable crosslinking agent (C) may be carried out when forming a protective film using the surface protection composition of this embodiment, by heating the surface protection composition before forming the protective film, or by heating the protective film after forming the protective film. However, if the acid generator (B) in the surface protection composition of this embodiment includes a thermal acid generator, it is preferable to carry out the crosslinking reaction between the crosslinkable groups in polymer (A) and the acid-degradable crosslinking agent (C) at a temperature lower than the heating temperature required for the thermal acid generator to generate acid. The acid-degradable crosslinking agent (C) of this embodiment contains two or more crosslinkable groups selected from the group consisting of vinyl ether groups, amino groups, carboxyl groups, ketone groups, and hydroxyl groups, more preferably two or more crosslinkable groups selected from the group consisting of vinyl ether groups and amino groups, and even more preferably two or more vinyl ether groups.

[0042] <Method for Producing the Surface Protection Composition> The surface protection composition of this embodiment can be produced by any known method. For example, it can be produced by mixing the polymer (A), acid generator (B), and solvent described above using a mixing rotor or the like until homogeneous. Here, an acid-degradable crosslinking agent (C) may be further mixed as needed. As the solvent, one or more selected from the group consisting of water, acetone, ethyl acetate, toluene, ethanol, butanol, propylene carbonate, 1-methoxy-2-propanol, propylene glycol monomethyl ether acetate, isopropyl alcohol (IPA), methyl ethyl ketone (MEK), and butyl acetate can be used. Only one solvent may be used, or two or more may be combined.

[0043] <Formation of surface protection composition into a film> The surface protection composition of this embodiment can be formed into a film by any known method. For example, the surface protection composition can be formed into a film by applying it to a substrate such as glass or a silicon wafer to a thickness of about 1 to 120 μm and then drying it. The drying conditions are preferably a temperature of 30°C to 200°C, more preferably 40°C to 190°C, and preferably for 1 minute to 72 hours, more preferably 3 minutes to 72 hours. If the polymer containing structural units derived from (meth)acrylate (a) further contains a monomer (b) having a crosslinkable group, the crosslinking reaction between the crosslinkable group and the acid-degradable crosslinking agent (C) may occur when the surface protection composition is applied to the substrate and dried to form a film.

[0044] In this embodiment, when the following (Method 3) is performed, it is preferable that the film made from the surface protection composition of this embodiment does not dissolve in water and adheres closely to the substrate. This improves the water resistance of the film made from the surface protection composition.

[0045] (Method 3) A film 3 with a thickness of 5 ± 5 μm made of the surface protective composition is formed on the substrate. Next, the laminate consisting of the substrate and the film 3 is immersed in purified water for 10 minutes, then the laminate is removed from the water and the state of the film 3 is observed.

[0046] The switching cleanability of the surface protection composition of this embodiment can be evaluated, for example, as shown in (Method 4) below.

[0047] (Method 4) A film with a thickness of 5 ± 5 μm made of the surface protection composition of this embodiment is formed on a substrate. Next, the obtained film is irradiated with light according to the following light irradiation conditions. Then, the laminate consisting of the substrate and the film is immersed in purified water, and the time until all of the film dissolves or peels off in the purified water (dissolution time or peeling time (minutes)) is measured. (Light irradiation conditions) The substrate with the obtained film is placed on a SUS stand, and the illuminance is 20 mW / cm². ２ Irradiation time 150 seconds, integrated light intensity 3000 mJ / cm² ２ Under these conditions, a high-pressure mercury lamp (for example, manufactured by Technovision Co., Ltd., product name: UVC-408) is used to irradiate the film-side surface of the substrate with light.

[0048] When the above (Method 4) is performed, the dissolution time or peeling time of the surface protection composition is preferably 30 minutes or less, more preferably 25 minutes or less, even more preferably 20 minutes or less, even more preferably 15 minutes or less, even more preferably 12 minutes or less, and even more preferably 10 minutes or less, from the viewpoint of further improving the switching water washability. There is no lower limit to the dissolution time of the surface protection composition, but it may be, for example, 10 seconds or more, or 30 seconds or more.

[0049] <Surface protective film> The surface protective film of this embodiment includes a film formed by the surface protective composition of this embodiment. The surface protective film of this embodiment may be formed by coating the surface protective composition of this embodiment onto a substrate or the like to form a film, or it may be formed as a film.

[0050] The surface protective film of this embodiment can be used as a surface protective film that protects the surface of electronic components and is ultimately removed during the manufacturing process of electronic devices. Examples of electronic components include semiconductor chips such as ICs, LSIs, discrete components, light-emitting diodes, and photodetectors, as well as semiconductor panels, semiconductor packages, and wafers.

[0051] The thickness of the surface protective film in this embodiment is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, from the viewpoint of further improving the balance between water resistance and surface protection performance, and is 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less, from the viewpoint of further improving switching water washability.

[0052] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted.

[0053] It should be noted that the present invention is not limited to the embodiments described above, and any modifications, improvements, etc., that can achieve the objectives of the present invention are included in the present invention.

[0054] This embodiment will be described in detail below with reference to examples and comparative examples. However, this embodiment is not limited in any way to the descriptions in these examples.

[0055] <Raw Materials> The raw materials used in the examples and comparative examples are as follows: (Polymer (A)) (Structural Unit (a)) ・Structural Unit (a-1): 1-Ethoxyethyl Methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・Structural Unit (a-2): (2-Methyl-2-ethyl-1,3-Dioxolan-4-yl) Methyl Acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., MEDOL-10) (Structural Unit (b)) ・Structural Unit (b-1): Acrylic Acid (manufactured by Fujifilm Wako Pure Chemical Corporation) ・Structural Unit (b-2): Methacrylic Acid (manufactured by Fujifilm Wako Pure Chemical Corporation) ・Structural Unit (b-3): Acryloyl Morpholine (manufactured by Tokyo Chemical Industry Co., Ltd.) ・Structural Unit (b-4): 2-Ethylhexyl Acrylate (manufactured by Fujifilm Wako Pure Chemical Corporation)

[0056] (Acid Generator (B)) ・Acid Generator (B-1): Sulfonium salt type photoacid generator, manufactured by Sunapro Co., Ltd., CPI-100B ・Acid Generator (B-2): Sulfonium salt type photoacid generator, manufactured by Sunapro Co., Ltd., CPI-110B

[0057] (Crosslinking agent (C)) ・Crosslinking agent (C-1): Diethylene glycol divinyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0058] <Synthesis of Polymer (A)> Polymer solutions for each example were synthesized according to the formulations in Table 1 using the following method.

[0059] (Preparation of Polymer (A) Solution 1) 4.0 g of 1-ethoxyethyl methacrylate and 8.5 g of ethyl acetate were mixed to obtain monomer solution 1. 0.30 g of 2,2'-azobis(isobutyronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., AIBN) was dissolved in 6.0 g of ethyl acetate to obtain an initiator solution. Next, 0.49 mL of the initiator solution was added to the monomer solution 1, which had been heated to 65°C under a nitrogen atmosphere. After heating under a nitrogen atmosphere for 1 hour with stirring, another 0.49 mL of the initiator solution was added, and the mixture was heated for a further 7 hours. After allowing it to cool to room temperature and stand for 14 hours or more, it was heated again under a nitrogen atmosphere at 65°C with stirring for 7 hours to obtain polymer (A) solution 1 containing an acrylic polymer.

[0060] (Preparation of Polymer (A) Solution 2) 200 g of 1-ethoxyethyl methacrylate and 113 g of ethyl acetate were mixed to obtain monomer solution 2. Meanwhile, 1.1 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., V-65) was dissolved in 22 g of ethyl acetate to obtain an initiator solution. Then, 11.6 mL of the initiator solution was added to the monomer solution 2, which had been heated to 50°C under a nitrogen atmosphere. After heating under a nitrogen atmosphere for 1 hour with stirring, another 11.6 mL of the initiator solution was added and the mixture was heated for a further 5 hours. After allowing it to cool to room temperature and stand for 14 hours or more, it was heated again under a nitrogen atmosphere at 50°C with stirring for 7 hours. The temperature was further raised to 70°C and heated for 2 hours to obtain polymer (A) solution 2 containing an acrylic polymer.

[0061] (Preparation of Polymer (A) Solution 3) 18 g of 1-ethoxyethyl methacrylate and 11 g of ethyl acetate were mixed to obtain monomer solution 3. Meanwhile, 0.30 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., V-65) was dissolved in 6.0 g of ethyl acetate to obtain an initiator solution. Then, 0.42 mL of the initiator solution was added to the monomer solution 3, which had been heated to 50°C under a nitrogen atmosphere. After heating under a nitrogen atmosphere for 1 hour with stirring, another 0.42 mL of the initiator solution was added, and the mixture was heated for a further 7 hours. After allowing it to cool to room temperature and stand for 14 hours or more, it was heated again under a nitrogen atmosphere at 50°C with stirring for 8 hours. After allowing it to cool to room temperature and stand for 14 hours or more, it was heated again under a nitrogen atmosphere at 80°C with stirring for 2 hours to obtain polymer (A) solution 3 containing an acrylic polymer.

[0062] (Preparation of Polymer (A) Solution 4) 12 g of 1-ethoxyethyl methacrylate, 2.2 g of methacrylic acid, and 27 g of ethyl acetate were mixed to obtain monomer solution 4. In addition, 0.30 g of 2,2'-azobis(isobutyronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., AIBN) was dissolved in 6.0 g of ethyl acetate to obtain an initiator solution. Next, 3.3 mL of the initiator solution was added to the monomer solution 4, which had been heated to 65°C under a nitrogen atmosphere. After heating under a nitrogen atmosphere for 1 hour with stirring, another 3.3 mL of the initiator solution was added and the mixture was heated for a further 7 hours. After allowing it to cool to room temperature and stand for 14 hours or more, it was heated again under a nitrogen atmosphere with stirring at 65°C for 7 hours to obtain polymer (A) solution 4.

[0063] (Preparation of Polymer (A) Solution 5) 4.0 g of 1-ethoxyethyl methacrylate, 1.2 g of acryloylmorpholine, and 10 g of ethyl acetate were mixed to obtain monomer solution 5. In addition, 0.30 g of 2,2'-azobis(isobutyronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., AIBN) was dissolved in 6.0 g of ethyl acetate to obtain an initiator solution. Then, 1.2 mL of the initiator solution was added to the monomer solution 5, which had been heated to 65°C under a nitrogen atmosphere. After heating under a nitrogen atmosphere for 1 hour with stirring, another 1.2 mL of the initiator solution was added and the mixture was heated for a further 7 hours. After cooling to room temperature and standing for 14 hours or more, the mixture was heated again under a nitrogen atmosphere at 65°C with stirring for 7 hours to obtain polymer (A) solution 5.

[0064] (Preparation of Polymer (A) Solution 6) 5.0 g of 1-ethoxyethyl methacrylate, 0.32 g of 2-ethylhexyl acrylate, and 9.9 g of ethyl acetate were mixed to obtain monomer solution 6. In addition, 0.30 g of 2,2'-azobis(isobutyronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., AIBN) was dissolved in 6.0 g of ethyl acetate to obtain an initiator solution. Next, 1.2 mL of the initiator solution was added to the monomer solution 6, which had been heated to 65°C under a nitrogen atmosphere. After heating under a nitrogen atmosphere for 1 hour with stirring, another 1.2 mL of the initiator solution was added and the mixture was heated for a further 7 hours. After cooling to room temperature and standing for 14 hours or more, the mixture was heated again under a nitrogen atmosphere at 65°C for 7 hours with stirring to obtain polymer (A) solution 6.

[0065] (Preparation of Polymer (A) Solution 7) 5.0 g of 1-ethoxyethyl methacrylate, 2.1 g of (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, and 14 g of ethyl acetate were mixed to obtain monomer solution 7. In addition, 0.30 g of 2,2'-azobis(isobutyronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., AIBN) was dissolved in 6.0 g of ethyl acetate to obtain an initiator solution. Next, 1.2 mL of the initiator solution was added to the monomer solution 7, which had been heated to 65°C under a nitrogen atmosphere. After heating under a nitrogen atmosphere for 1 hour with stirring, another 1.2 mL of the initiator solution was added and heated for a further 7 hours. After cooling to room temperature and standing for 14 hours or more, it was heated again under a nitrogen atmosphere at 65°C for 5 hours with stirring, and then heated at 80°C for 2 hours to obtain polymer (A) solution 7.

[0066] (Preparation of Polymer (A) Solution 8) 0.60 g of 1-ethoxyethyl methacrylate, 4.6 g of (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, and 10 g of ethyl acetate were mixed to obtain monomer solution 8. In addition, 0.30 g of 2,2'-azobis(isobutyronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., AIBN) was dissolved in 6.0 g of ethyl acetate to obtain an initiator solution. Next, 1.2 mL of the initiator solution was added to the monomer solution 8, which had been heated to 65°C under a nitrogen atmosphere. After heating under a nitrogen atmosphere for 1 hour with stirring, another 1.2 mL of the initiator solution was added and heated for a further 6 hours. After cooling to room temperature and standing for 14 hours or more, it was heated again under a nitrogen atmosphere at 65°C for 6 hours with stirring, and then heated at 80°C for 2 hours to obtain polymer (A) solution 8.

[0067] (Preparation of Polymer (A) Solution 9) Polymer (A) Solution 9 was obtained in the same manner as Polymer (A) Solution 4, except that 8.0 g of 1-ethoxyethyl methacrylate was added to monomer solution 4, 1.2 g of acrylic acid was added to methacrylic acid, and 18 g of ethyl acetate was added, and the amount of initiator solution added was changed to 2.1 mL each.

[0068] (Preparation of polymer (A) solution 10) 0.50 g of ethylcellulose (Aqualon ＴＭ2.4 g of butanol was added to EC-N14 0100 (manufactured by Ashland), and the mixture was stirred for 24 hours to obtain polymer (A) solution 10.

[0069] (Preparation of polymer (A) solution 11) 0.60 g of polyacrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 1.3 g of ethanol and 4.4 g of water, and stirred for 24 hours to obtain polymer (A) solution 11.

[0070] <Weight-average molecular weight (Mw), number-average molecular weight (Mn), and Mw / Mn> For each example polymer (A), the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured by gel permeation chromatography (GPC) under the following conditions. (Conditions) ・Automatic injection device: Waters Japan, 717plus ・Pump: Fromm, KP-22-13S dual pump ・Column: Agilent Technologies, PLgel 10μ MIXED-B, inner diameter 7.5 mm x 300 mm (3 columns) ・Differential refractive index detector: Resonac Corporation, Shodex RI-101 ・Column calibration: Agilent Technologies, EasiCal PS-1 polystyrene ・Eluent: Fujifilm Wako Pure Chemical Industries, HPLC tetrahydrofuran ・Column temperature: 40℃ ・Flow rate: 1.0 mL / min Mw / Mn were calculated from the obtained values. The results are shown in Table 1.

[0071]

[0072] <Method for producing the surface protective film composition> The obtained polymer (A), acid generator (B), crosslinking agent (C), and solvents are ethyl acetate, propylene carbonate (PC), 1-methoxy-2-propanol (MP), butanol (BuOH), ethanol (EtOH), and H ２ O was mixed using a mixing rotor in the proportions shown in Table 2 until uniform, to obtain the surface protection compositions for each example.

[0073]

[0074] <Coating Conditions> The surface protection composition for each example was applied to a silicon wafer (manufactured by Seiren KST Co., Ltd., 3 cm x 4.5-7.5 cm) as a substrate using a non-wire bar coater OSP-80-L60 (film thickness 80 μm / wet). Then, it was dried on a hot plate at 100°C for 5 minutes (hereinafter referred to as heating condition A), or dried on a hot plate at 120°C for 10 minutes, followed by curing in an oven at 50°C for 48 hours (hereinafter referred to as heating condition B) to obtain a coated film 1 on the substrate. The thickness of the film after drying was within the range of 5 ± 5 μm. The substrates used in each example and the drying conditions (heating conditions) of the film are shown in Table 3. <Light Irradiation Conditions> For film 1 in each example, the irradiance was 20 mW / cm². ２ Irradiation time 150 seconds, integrated light intensity 3000 mJ / cm² ２ Under these conditions, the film-side surface of the substrate was irradiated with light using a high-pressure mercury lamp (manufactured by Technovision Co., Ltd., product name: UVC-408). The film after light irradiation was designated as film 2.

[0075] <Measurement of water contact angle> The water contact angle X is measured using the following method. １ and X ２ Measurements were taken. The results are shown in Table 3. (Water contact angle X １ (Measurement) Using a contact angle meter DMo-502 (manufactured by Kyowa Interface Science Co., Ltd.), the water contact angle X of film 1 in each example was measured in accordance with JIS R3257:1999. １ The following was measured. The measurement was performed immediately after dropping 2 μL of purified water (pH 6.5) onto membrane 1, and the average of the measurements taken at three different locations on membrane 1 was used to determine the water contact angle X. １ (Water contact angle X) ２ Measurement of the water contact angle X) For each example, the timing of the measurement for film 2 was set to 60 seconds after the addition of purified water droplets. １ The measurements were performed in the same manner.

[0076] <Evaluation of Water Resistance> The substrate and film were immersed in purified water (pH 6.5) for 10 minutes. After removing the substrate and film from the water, their condition was observed, and their water resistance was evaluated according to the following criteria. A is considered a pass. The results are shown in Table 3. (Criteria) A: The film did not dissolve and remained in close contact with the substrate. B: The film peeled off the substrate. C: The film dissolved.

[0077] <Evaluation of water washability> The obtained film 1 was irradiated with light according to the following light irradiation conditions. (Light irradiation conditions) The substrate with the obtained film was placed on a stainless steel stand, and the illuminance was 20 mW / cm². ２ Irradiation time 150 seconds, integrated light intensity 3000 mJ / cm² ２ Under these conditions, the film-side surface of the substrate was irradiated with light using a high-pressure mercury lamp (manufactured by Technovision Co., Ltd., product name: UVC-408).

[0078] Next, the substrate and the film were immersed in purified water (pH 6.5), and the time (dissolution time (minutes) or peeling time (minutes)) until the entire film dissolved or peeled off in the purified water was measured. The cleanability was also evaluated according to the following criteria. A and B were considered acceptable. The results are shown in Table 3. (Criteria) A: The film dissolved completely within 30 minutes. B: The film peeled completely off the substrate within 30 minutes. C: The film partially dissolved or peeled off within 30 minutes, but did not completely dissolve or peel completely off the substrate, or the film neither dissolved nor peeled off within 30 minutes.

[0079]

[0080] In Table 3, "(Peeling time 1 minute)" means that, although the film did not completely dissolve during the water washability evaluation, the time it took for the film to completely detach from the substrate was 1 minute.

[0081] This application claims priority based on Japanese Patent Application No. 2024-230735, filed on 26 December 2024, and incorporates all of its disclosures herein.

Claims

1. A surface protection composition, wherein the water contact angle X is determined by the following method 1. １ And, the water contact angle X by method 2 below ２ The difference (X １ -X ２ A surface protection composition having a water contact angle of 10° or more. (Method 1) A film 1 made of the surface protection composition is formed on a substrate. Then, in accordance with JIS R3257:1999, purified water is dropped onto the film 1, and the water contact angle of the film 1 immediately after dropping is measured, and the water contact angle X １ (Method 2) Obtain film 1 in the same manner as in (Method 1). Apply an illuminance of 20 mW / cm to the obtained film 1. ２ Irradiation time 150 seconds, integrated light intensity 3000 mJ / cm² ２ Under these conditions, light is irradiated using a high-pressure mercury lamp to obtain film 2. Next, in accordance with JIS R3257:1999, purified water is dropped onto film 2 and the water contact angle of film 2 is measured 60 seconds later, and the water contact angle X is obtained. ２ Let's assume that.

2. The water contact angle X １ is 60° or more, and the surface protection composition according to claim 1.

3. Said water contact angle X ２ A surface protection composition according to claim 1 or 2, wherein the temperature is 75° or less.

4. The surface protection composition according to any one of claims 1 to 3, comprising a polymer (A) and an acid generator (B) containing at least one selected from a photoacid generator and a thermal acid generator.

5. The surface protection composition according to claim 4, wherein the acid generator (B) comprises a photoacid generator.

6. The surface protection composition according to claim 5, wherein the photoacid generator comprises one or more selected from sulfonium salt type photoacid generators, iodonium salt type photoacid generators, and nonionic type photoacid generators.

7. The surface protection composition according to any one of claims 4 to 6, wherein the content of the acid generator (B) in the surface protection composition is 1.0 part by mass or more and 50.0 parts by mass or less per 100 parts by mass of the polymer (A).

8. Illumination of 20 mW / cm² for the film 1. ２ Irradiation time 150 seconds, integrated light intensity 3000 mJ / cm² ２ The surface protection composition according to any one of claims 4 to 7, wherein when light is irradiated using a high-pressure mercury lamp under the conditions, the polymer (A) has hydrophilic groups, and the hydrophilic groups include at least one selected from the group consisting of hydroxyl groups and carboxyl groups.

9. The surface protection composition according to any one of claims 4 to 8, wherein the polymer (A) comprises one or more selected from the group consisting of polymers containing structural units derived from (meth)acrylate (a), polyvinylpyrrolidone, and polyethylene oxide.

10. The surface protective composition according to any one of claims 4 to 9, wherein the polymer (A) comprises a structural unit (a) having one or more degradable groups selected from the group consisting of acid-degradable groups and base-degradable groups.

11. The surface protective composition according to claim 10, wherein the functional group protected by the degradable group comprises at least one selected from the group consisting of carboxyl groups and hydroxyl groups.

12. The surface protective composition according to claim 10 or 11, wherein the degradable group comprises at least one selected from the group consisting of a group containing an ether bond, a group containing an ester bond, and an alkyl group.

13. The surface protection composition according to claim 12, wherein the group containing the ether bond contains an alkyl group having 1 to 8 carbon atoms.

14. The surface protective composition according to any one of claims 4 to 13, wherein the weight-average molecular weight (Mw) of the polymer (A), measured by gel permeation chromatography, is 5,000 or more and 10,000,000 or less on a polystyrene basis.

15. A surface protective composition according to any one of claims 1 to 14, wherein when the following (Method 3) is performed, the film made of the surface protective composition does not dissolve in water and adheres to the substrate. (Method 3) A film 3 with a thickness of 5 ± 5 μm made of the surface protective composition is formed on the substrate. Next, the laminate consisting of the substrate and the film 3 is immersed in purified water for 10 minutes, then the laminate is removed from the water and the state of the film 3 is observed.

16. A surface protection composition according to any one of claims 1 to 15, used to form a surface protection film that protects the surface of an electronic component.

17. The surface protective composition according to claim 16, wherein the surface protective film is a surface protective film that protects the surface of an electronic component and is ultimately removed.

18. A surface protective film comprising a film formed by the surface protective composition according to any one of claims 1 to 17.

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