Surface protection film

Abstract

A surface protective film is provided, which is a surface protective film including an adhesive layer. It exhibits sufficient strong adhesion to the adherend before ultraviolet (UV) irradiation and excellent easy peelability after UV irradiation, allowing for smooth removal from the adherend. Furthermore, it maintains sufficient strong adhesion even after long-term storage following manufacturing, and suppresses the generation of static electricity when peeling from the adherend after UV irradiation. Optical and electronic devices incorporating such a surface protective film are also provided. The surface protective film of an embodiment of the present invention is a surface protective film including an adhesive layer. The adhesive constituting the adhesive layer is formed from an adhesive composition comprising a urethane prepolymer (A), a crosslinking agent (B), a photopolymerization initiator (C), and an ionic compound (D). The urethane prepolymer (A) has polymerizable unsaturated double bonds, and the ionic compound (D) is an ionic compound composed of cations selected from the group consisting of ononium cations and metal cations, and anions that are not borate anions.

Description

Technical Field

[0001] This invention relates to a surface protective film. Background Technology

[0002] In the manufacturing process of optical and electronic devices, during processing, assembly, inspection, and transportation, a surface protective film is usually attached to the exposed surface of the optical or electronic components to prevent surface damage. This surface protective film is peeled off from the optical or electronic components at a point when surface protection is no longer required (Patent Document 1).

[0003] For surface protective films attached to the exposed surfaces of optical and electronic components, sufficient strong adhesion is required to prevent peeling during periods when surface protection is needed. Conversely, excellent peelability is required to facilitate easy removal of the protective film from the optical and electronic components without causing contamination or damage when surface protection is no longer required. In other words, a balance must be struck between sufficient strong adhesion during periods when surface protection is needed and excellent peelability when surface protection is not required.

[0004] As a technique for adjusting adhesive strength, a surface protective sheet for optical components whose adhesive strength is reduced by irradiation with ultraviolet light has been reported (Patent Document 2). Additionally, a surface protective sheet for optical components exhibiting light peelability due to reduced adhesive strength caused by ultraviolet irradiation has been reported (Patent Document 3). However, the adhesive reported in Patent Document 2 cannot sufficiently increase the adhesive strength before ultraviolet irradiation, nor can it sufficiently reduce the adhesive strength after ultraviolet irradiation. Furthermore, the adhesive reported in Patent Document 3 cannot sufficiently reduce the adhesive strength. Therefore, it is impossible to achieve both sufficient strong adhesive strength during periods when surface protection is required and excellent light peelability at times when surface protection is not needed.

[0005] As another technique for adjusting adhesive strength, adhesives obtained by adding specific radical polymerizable monomers containing (meth)acryloyl groups and active hydrogen groups to specific urethane prepolymers have been reported (Patent Document 4). However, the adhesives reported in Patent Document 4 have the problem of low adhesive strength before UV irradiation and easy peeling during periods when surface protection is required.

[0006] As another technique for adjusting adhesion, an adhesive (Patent Document 5) has been reported, which is an adhesive composition obtained by adding a polyfunctional (meth)acrylate to a urethane prepolymer having two or more hydroxyl groups and (meth)acryloyloxy groups. However, the adhesive reported in Patent Document 5 also has the problem of low adhesion before UV irradiation and easy peeling during periods when surface protection is required.

[0007] In the manufacturing processes of optical and electronic components, it is also important to prevent damage caused by static electricity. For example, techniques for adding antistatic agents to adhesives have been reported (Patent Documents 5-7). However, when antistatic agents are added, sometimes sufficient strong adhesion cannot be maintained during periods when surface protection is required, especially when the surface protective film is manufactured and used after long-term storage, the adhesion can be significantly reduced during the period when surface protection is needed.

[0008] Existing technical documents Patent documents Patent Document 1: Japanese Patent No. 6613516 Patent Document 2: Japanese Patent Application Publication No. 2019-116609 Patent Document 3: Japanese Patent Application Publication No. 2019-116610 Patent Document 4: Japanese Patent No. 6769503 Patent Document 5: Japanese Patent No. 7285072 Patent Document 6: Japanese Patent No. 6896927 Patent Document 7: Japanese Patent Application Publication No. 9-165460 Summary of the Invention

[0009] The problem that the invention aims to solve The present invention aims to provide a surface protective film comprising an adhesive layer. The primary use of this surface protective film is to adhere it to exposed surfaces during the manufacturing processes of optical and electronic components to prevent damage during processing, assembly, inspection, and transportation. The surface protective film exhibits sufficiently strong adhesion to the adhered object before ultraviolet (UV) irradiation and excellent easy peelability after UV irradiation, allowing for smooth removal from the adhered object. Furthermore, it maintains sufficient strong adhesion even after long-term storage following manufacturing, and suppresses the generation of static electricity when peeling from the adhered object after UV irradiation. Optical and electronic devices incorporating such a surface protective film are also provided.

[0010] Solution for solving the problem [1] The surface protective film of the present invention is a surface protective film comprising an adhesive layer, wherein the adhesive constituting the adhesive layer is formed by an adhesive composition comprising a urethane prepolymer (A), a crosslinking agent (B), a photopolymerization initiator (C), and an ionic compound (D). The urethane prepolymer (A) has polymerizable unsaturated double bonds, and the ionic compound (D) is an ionic compound composed of cations selected from the group consisting of onion cations and metal cations and anions that are not borate anions.

[0011] [2] In the surface protective film described in [1] above, the ionic compound (D) can be in a liquid state at 23°C and atmospheric pressure.

[0012] [3] In the surface protective film described in [1] or [2] above, the content of the above ionic compound (D) relative to 100 parts by weight of the above urethane prepolymer (A) can be 0.1 parts by weight to 3.0 parts by weight.

[0013] [4] In any one of the above [1] to [3] surface protective films, the above adhesive composition may contain urethane (meth) acrylate (E).

[0014] [5] The optical device of the embodiments of the present invention includes the surface protective film described in any one of [1] to [4] above.

[0015] [6] The electronic device of the embodiments of the present invention includes the surface protective film described in any one of [1] to [4] above.

[0016] Invention Effects According to the present invention, a surface protective film comprising an adhesive layer can be provided. The main purpose of this surface protective film is to be adhered to exposed surfaces of optical and electronic components during manufacturing processes to prevent damage to the surfaces of these components during processing, assembly, inspection, and transportation. The surface protective film exhibits sufficiently strong adhesion to the adherend before ultraviolet irradiation and excellent easy peelability after ultraviolet irradiation, allowing for smooth removal from the adherend. Furthermore, even after manufacturing and long-term storage, the sufficient strong adhesion before ultraviolet irradiation is maintained. Additionally, the generation of static electricity during peeling from the adherend after ultraviolet irradiation can be suppressed. Furthermore, optical and electronic devices incorporating such a surface protective film can be provided. Attached Figure Description

[0017] Figure 1 This is a schematic cross-sectional view of a surface protective film according to one embodiment of the present invention. Detailed Implementation

[0018] Where the term "weight" is used in this specification, it may be replaced with "mass," which is the SI unit commonly used to express weight.

[0019] In this specification, when "(meth)acrylic acid" is used, it means "acrylic acid and / or methacrylic acid"; when "(meth)acrylate" is used, it means "acrylate and / or methacrylate"; when "(meth)acryloyl" is used, it means "acryloyl and / or methacryloyl"; when "(meth)allyl" is used, it means "allyl and / or methylallyl"; and when "(meth)acrylaldehyde" is used, it means "acrylaldehyde and / or methacrolein".

[0020] 《A. Surface Protective Film》 The surface protective film in embodiments of the present invention includes an adhesive layer. The adhesive layer may be a single layer or a layer consisting of two or more layers.

[0021] The surface protective film of embodiments of the present invention, as long as it contains an adhesive layer, may include any suitable other layers (components) without impairing the effects of the present invention. Such other layers may be only one layer or two or more layers. Examples of such other layers include, for instance, a substrate layer and a release liner (sometimes also called a release tab or spacer). Typically, the surface protective film of the present invention comprises a substrate layer and an adhesive layer.

[0022] Figure 1 This is a schematic cross-sectional view of a surface protective film according to one embodiment of the present invention. Figure 1 In the process, the surface protective film 10 has a substrate layer 1 and an adhesive layer 2. Figure 1 In this process, the substrate layer 1 and the adhesive layer 2 are directly laminated. Figure 1 In the adhesive layer 2, on the surface opposite to the substrate layer 1, for protection until use, any suitable release liner (sometimes called a release tab or spacer) may be provided (not shown).

[0023] As described above, the surface protective film, as one embodiment of the present invention, has a laminated structure in which a substrate layer, an adhesive layer, and a release liner are sequentially stacked, with the release liner being the outermost layer. The surface protective film, as another embodiment of the present invention, has a laminated structure in which a substrate layer and an adhesive layer are sequentially stacked, with the adhesive layer being the outermost layer.

[0024] The thickness of the surface protective film in the embodiments of the present invention is preferably 5μm~500μm, can be 10μm~450μm, can be 15μm~400μm, or can be 20μm~300μm.

[0025] For the surface protective film of the embodiments of the present invention, after the adhesive layer contained in the surface protective film is adhered to the surface of a glass plate and placed in an environment of 23°C and 55%RH for 30 minutes, the adhesive force (hereinafter sometimes referred to as "initial adhesive force before UV irradiation of the glass plate") when the surface protective film is peeled from the surface of the glass plate at a peel angle of 180 degrees and a peel speed of 300 mm / min in the same environment is preferably 500 gf / 25 mm or more, and can be 1000 gf / 25 mm or more, 1300 gf / 25 mm or more, 1500 gf / 25 mm or more, 1800 gf / 25 mm or more, or 2000 gf / 25 mm or more. The higher the initial adhesive force before UV irradiation of the glass plate, the better; however, if it is too high, it may not exhibit sufficient easy peelability even when irradiated with ultraviolet light. Therefore, as an upper limit, it is preferably 5000 gf / 25 mm or less, but can be 4000 gf / 25 mm or less, 3500 gf / 25 mm or less, or 3000 gf / 25 mm or less. If the initial adhesion force before UV irradiation of the glass plate is within the above range, the surface protective film of the embodiment of the present invention can, for example, exhibit sufficiently strong adhesion to the adhered object before UV irradiation. If the initial adhesion force before UV irradiation of the glass plate deviates from the above range and is too low, it may peel off from the adhered object before UV irradiation. It should be noted that the details of the method for measuring the initial adhesion force before UV irradiation of the glass plate are described below.

[0026] For the surface protective film of the embodiment of the present invention, the adhesive layer contained in the surface protective film is adhered to the surface of a glass plate, and the cumulative light intensity is 700mJ / cm² when irradiated by an LED light source with a wavelength of 365nm. 2The surface protective film is exposed to ultraviolet light, and then placed in an environment of 23°C and 55%RH for 30 minutes. The adhesion force (hereinafter sometimes referred to as "initial adhesion force after UV irradiation of the glass plate") when the protective film is peeled off from the surface of the glass plate at a peel angle of 180 degrees and a peel speed of 300 mm / min in the same environment is preferably 20.00 gf / 25 mm or less, and can be 16.00 gf / 25 mm or less, 12.00 gf / 25 mm or less, 10.00 gf / 25 mm or less, 8.00 gf / 25 mm or less, 7.00 gf / 25 mm or less, 6.00 gf / 25 mm or less, 5.50 gf / 25 mm or less, 5.00 gf / 25 mm or less, or less than 5.00 gf / 25 mm. The lower the initial adhesion force after UV irradiation of the glass plate, the better. However, if it is too low, it may peel off from the adhered object unexpectedly. Therefore, as a lower limit, it is preferably 1.00 gf / 25 mm or more, and can be 2.00 gf / 25 mm or more, 2.50 gf / 25 mm or more, or 3.00 gf / 25 mm or more. If the initial adhesion force after UV irradiation of the glass plate is within the above range, the adhesion force becomes very low. Therefore, the surface protective film of the embodiment of the present invention can exhibit excellent easy peelability, for example, enabling it to be easily peeled off from the adhered object after UV irradiation. If the initial adhesion force after UV irradiation of the glass plate deviates from the above range and is too high, it may cause contamination or damage to the adhered object when peeling it off after UV irradiation. It should be noted that the details of the method for measuring the initial adhesion force after UV irradiation of the glass plate are described below.

[0027] In the surface protective film of the embodiments of the present invention, the ratio of the change in initial adhesion force to the glass plate before UV irradiation to the initial adhesion force to the glass plate after UV irradiation (initial adhesion force to the glass plate before UV irradiation / initial adhesion force to the glass plate after UV irradiation) (times referred to as "change ratio of initial adhesion force to the glass plate before / after UV irradiation") is preferably 5 times or more, can be 10 times or more, can be 100 times or more, can be 200 times or more, can be 300 times or more, and can be 400 times or more. The higher the change ratio, the better, but considering ease of operation, the upper limit is preferably, for example, 10,000 times or less, can be 5,000 times or less, can be 2,000 times or less, can be 1,500 times or less, or can be 1,000 times or less. If the change ratio is within the above range, the effects of the present invention can be further demonstrated, for example, it can exhibit a stronger adhesion force to the adhered object before UV irradiation, and can exhibit better easy peelability after UV irradiation, allowing for smooth peeling from the adhered object.

[0028] For the surface protective film of the embodiments of the present invention, after the surface protective film is manufactured and stored in an environment of 23°C and 55%RH for one week, the adhesive layer contained in the surface protective film is adhered to the surface of a glass plate and placed in an environment of 23°C and 55%RH for 30 minutes. The adhesion force when the surface protective film is peeled from the surface of the glass plate at a peel angle of 180 degrees and a peel speed of 300 mm / min in an environment of 23°C and 55%RH (hereinafter sometimes referred to as "initial adhesion force before UV irradiation of the glass plate after one week of storage") is preferably 500 gf / 25 mm or more, and can be 1000 gf / 25 mm or more, 1300 gf / 25 mm or more, 1500 gf / 25 mm or more, 1800 gf / 25 mm or more, or 2000 gf / 25 mm or more. A higher initial adhesion force before UV irradiation of the glass plate after one week of storage is better, but if it is too high, it may not exhibit sufficient easy peelability even when irradiated with ultraviolet light. Therefore, as an upper limit, it is preferably 5000 gf / 25 mm or less, but can be 4000 gf / 25 mm or less, 3500 gf / 25 mm or less, or 3000 gf / 25 mm or less. If the initial adhesion to the glass plate before UV irradiation after one week of storage is within the above range, the surface protective film of the embodiment of the present invention can maintain sufficient strong adhesion before UV irradiation, even if it is used after manufacturing the surface protective film and storing it for a long time. If the initial adhesion to the glass plate before UV irradiation after one week of storage deviates from the above range and is too low, for example, in the case of manufacturing the surface protective film and storing it for a long time, the surface protective film may peel off from the adhered object before UV irradiation. It should be noted that the details of the method for measuring the initial adhesion to the glass plate before UV irradiation after one week of storage are described below.

[0029] In the surface protective film of the embodiments of the present invention, the rate of increase of the initial adhesion to the glass plate before UV irradiation after one week of storage relative to the initial adhesion to the glass plate before UV irradiation ((initial adhesion to the glass plate before UV irradiation after one week of storage / initial adhesion to the glass plate before UV irradiation) × 100% (sometimes referred to as "adhesion increase rate before UV irradiation") is preferably 110% or less, and can be 108% or less, 106% or less, 104% or less, or 102% or less. The lower the rate of increase, the better, but if it is excessively lower than 100%, it may peel off naturally from the adhered object under unexpected circumstances. Therefore, the lower limit value is preferably 95% or more, and can be 98% or more, 99% or more, or 100% or more. If the rate of increase is within the above range, for example, even after manufacturing the surface protective film and storing it for a long time, sufficient strong adhesion before UV irradiation can be maintained. When the aforementioned rate of increase exceeds the aforementioned range and is too high, for example, in the case of manufacturing a surface protective film and using it after long-term storage, the surface protective film may peel off from the adhered object before ultraviolet radiation.

[0030] The residual adhesion rate of the surface protective film of the present invention after UV irradiation of a glass plate, measured in an environment of 23°C and 55%RH, is preferably 50% or more, and can be 70% or more, 80% or more, 85% or more, 90% or more, or 95% or more. The upper limit of the residual adhesion rate after UV irradiation of the glass plate is, for example, 100% or less. If the residual adhesion rate after UV irradiation of the glass plate is within the above range, the surface protective film of the present invention can, for example, suppress contamination of the adhered object. It should be noted that the details of the measurement and calculation method of the residual adhesion rate after UV irradiation of the glass plate are described later.

[0031] For the surface protective film in the embodiments of the present invention, the cumulative light intensity is 700 mJ / cm when irradiated by an LED light source with a wavelength of 365 nm. 2 After the adhesive layer is cured by ultraviolet light, the release liner is peeled off to expose the adhesive layer. The surface resistivity of the adhesive layer, measured at 23°C and 55%RH, is preferably less than 1.0 × 10⁻⁶. 11 Ω can be 5.0 × 10 10 For values ​​below Ω, 1.0 × 10⁻⁶ can be used. 10 For values ​​below Ω, it can be 5.0 × 10. 9 For values ​​below Ω, a value of 3.0 × 10⁻⁶ is acceptable. 9 Below Ω. The lower the surface resistivity value mentioned above, the better; the lower limit is preferably, for example, 1.0 × 10 Ω. 4Ω or higher. If the surface resistance value is within the above range, the surface protective film of the embodiment of the present invention can, for example, suppress the generation of static electricity when peeling off from the adhered object.

[0032] For the surface protective film of the embodiments of the present invention, after manufacturing the surface protective film, it is stored at a temperature of 23°C and a humidity of 55%RH for one week, and then irradiated with an LED light source with a cumulative light intensity of 700mJ / cm² using a wavelength of 365nm. 2 After the adhesive layer is cured by ultraviolet light, the release liner is peeled off to expose the adhesive layer. The surface resistivity of the adhesive layer, measured at 23°C and 55%RH, is preferably less than 1.0 × 10⁻⁶. 11 Ω can be 5.0 × 10 10 For values ​​below Ω, 1.0 × 10⁻⁶ can be used. 10 For values ​​below Ω, it can be 5.0 × 10. 9 For values ​​below Ω, a value of 3.0 × 10⁻⁶ is acceptable. 9 Below Ω. The lower the surface resistivity value mentioned above, the better; the lower limit is preferably, for example, 1.0 × 10 Ω. 4 Ω or higher. If the surface resistance value is within the above range, the surface protective film of the embodiment of the present invention can, for example, suppress the generation of static electricity when peeling off from the adhered object.

[0033] The surface protective film of the embodiments of the present invention can be manufactured by any suitable method. For example, a known method for manufacturing a surface protective film comprising a substrate layer and an adhesive layer can be used.

[0034] The adhesive layer contained in the surface protective film of embodiments of the present invention can be formed by a formation method commonly known as the "direct method" or by a formation method commonly known as the "transfer method". The direct method involves coating an adhesive composition onto a substrate layer, subjecting it to heating, irradiation with active energy rays (such as ultraviolet light), drying, etc., as needed, to form an adhesive layer. The transfer method involves coating an adhesive composition onto a release liner or similar material, subjecting it to heating, irradiation with active energy rays (such as ultraviolet light), drying, etc., as needed, thereby forming an adhesive layer, and then transferring the formed adhesive layer to a substrate layer.

[0035] Examples of coating methods include gravure roller coating machines, reverse roller coating machines, licking roller coating machines, dip roller coating machines, bar coating machines, doctor blade coating machines, air knife coating machines, spray coating machines, comma coating machines, direct coating machines, and roller brush coating machines.

[0036] The heating and drying conditions described above can be appropriately applied using methods commonly known for forming the adhesive layer.

[0037] A-1. Peeling the Liner As the release liner, any appropriate release liner can be adopted within the range that does not impair the effects of the present invention. As such a release liner, for example, a known release liner that is adhered to the surface of the adhesive layer contained in the surface protective film can be adopted. As such a release liner, for example, a release liner in which the surface of a base material (liner base material) such as paper or a plastic film is silicone-treated, or a release liner in which the surface of a base material (liner base material) such as paper or a plastic film is laminated with a polyolefin-based resin can be cited.

[0038] As the plastic film serving as the liner base material, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate copolymer film can be cited.

[0039] The thickness of the release liner is preferably 1 μm to 500 μm, can be 3 μm to 450 μm, can be 5 μm to 400 μm, and can also be 10 μm to 300 μm.

[0040] <<A-2. Adhesive Layer>> The adhesive layer is composed of an adhesive. The adhesive is formed from an adhesive composition. That is, the adhesive layer is composed of an adhesive, and this adhesive is formed from an adhesive composition. In other words, the adhesive formed from the adhesive composition becomes the adhesive layer by forming a layer shape.

[0041] From the aspect of being able to further exhibit the effects of the present invention, the thickness of the adhesive layer is preferably 5 μm to 150 μm, can be 10 μm to 130 μm, can be 30 μm to 120 μm, can be 50 μm to 100 μm, and can also be 60 μm to 90 μm.

[0042] The adhesive composition contains a urethane prepolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C). In an embodiment of the present invention, by combining and using the urethane prepolymer (A), the crosslinking agent (B), and the photopolymerization initiator (C) as the components contained in the adhesive composition, preferably by respectively selecting the types as described below or adjusting the usage amounts, the effects of the present invention can be exhibited.

[0043] <<A-2-1. Urethane Prepolymer (A)>> The urethane prepolymer (A) corresponds to the polymer component that is generally referred to as the base polymer as a component of the adhesive composition.

[0044] The urethane prepolymer (A) can be only one type, or can be two or more types.

[0045] The proportion of urethane prepolymer (A) in the adhesive composition, converted from solids, is preferably 50% to 99.9% by weight, can be 55% to 97% by weight, or can be 60% to 95% by weight. When the proportion of urethane prepolymer (A) in the adhesive composition, converted from solids, is within the above range, the effects of the present invention can be further demonstrated.

[0046] The urethane prepolymer (A) can typically react with a crosslinking agent (B) (preferably a polyfunctional isocyanate compound) to form a urethane resin. More specifically, it is preferable that a urethane resin can be formed from an adhesive composition containing the urethane prepolymer (A) and the crosslinking agent (B). More specifically, the urethane resin can be formed by curing the adhesive composition containing the urethane prepolymer (A) and the crosslinking agent (B). As a method for curing the adhesive composition containing the urethane prepolymer (A) and the crosslinking agent (B) to form a urethane resin, any suitable method, such as a urethane esterification reaction method using bulk polymerization or solution polymerization, can be used within the scope of not impairing the effects of the present invention.

[0047] As is generally known, there are two main methods for manufacturing urethane resins: a "one-step method" in which a polyol is directly reacted with a crosslinking agent (preferably a polyfunctional isocyanate compound) without using a urethane prepolymer, and a "prepolymer method" in which a urethane prepolymer is reacted with a crosslinking agent (preferably a polyfunctional isocyanate compound) to manufacture the urethane resin. The urethane prepolymer (A) used as the base polymer in this invention is equivalent to the urethane prepolymer reacted with a crosslinking agent (preferably a polyfunctional isocyanate compound) in the aforementioned "prepolymer method," and differs from the polyol reacted with a polyfunctional isocyanate in the aforementioned "one-step method."

[0048] The number average molecular weight Mn of the urethane prepolymer (A) is preferably 3,000 to 1,000,000.

[0049] The urethane prepolymer (A) may have polymerizable unsaturated double bonds. The presence of polymerizable unsaturated double bonds in the urethane prepolymer (A) further enhances the effects of the present invention. Examples of polymerizable unsaturated double bonds include, for example, commonly known polymerizable unsaturated double bonds such as vinyl, (meth)allyl, and (meth)acryloyl; from the perspective of further enhancing the effects of the present invention, (meth)acryloyl is preferred. The (meth)acryloyl group is at least one selected from the group consisting of acryloyl and methacryloyl groups.

[0050] The urethane prepolymer (A) is preferably a polyurethane polyol.

[0051] The urethane prepolymer (A) is preferably a polymer obtained by reacting a composition comprising a polyol, a compound having polymerizable unsaturated double bonds, and a crosslinking agent (preferably a polyfunctional isocyanate compound). This reaction can be carried out in the presence of a catalyst or in the absence of a catalyst.

[0052] It should be noted that, in the description of the embodiments of the present invention, the term "polyol" refers to a polyol that does not contain polymerizable unsaturated double bonds. Therefore, compounds having polymerizable unsaturated double bonds and multiple hydroxyl groups are not considered "polyols" in the description of the embodiments of the present invention, but rather belong to "compounds having polymerizable unsaturated double bonds".

[0053] The polyol preferably includes at least one selected from the group consisting of polyester polyol (a1) and polyether polyol (a2).

[0054] Polyester polyol (a1) can be only one type or two or more types.

[0055] The polyether polyol (a2) can be a single type or two or more types.

[0056] The polyol content in the above composition (composition comprising a polyol, a compound having polymerizable unsaturated double bonds and a crosslinking agent) used to prepare urethane prepolymer (A) is preferably 50% to 99% by weight, can be 55% to 95% by weight, or can be 60% to 90% by weight, converted from solid content.

[0057] The proportion of at least one of the polyols selected from the group consisting of polyester polyol (a1) and polyether polyol (a2) is preferably 50% to 100% by weight, can be 70% to 100% by weight, can be 80% to 100% by weight, can be 90% to 100% by weight, or can be 95% to 100% by weight.

[0058] As the polyester polyol (a1), polyester polyols commonly used in the manufacture of urethane prepolymers may be appropriately employed. Examples of such polyester polyols (a1) include those obtained by reacting an acid component with a diol component. Examples of acid components include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, and trimellitic acid. Examples of diol components include ethylene glycol, propylene glycol, diethylene glycol, butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerol, trimethylolpropane, and pentaerythritol. In addition to these, polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly(β-methyl-γ-valerol), and polyvalerol may also be included.

[0059] The molecular weight of the polyester polyol (a1) can range from low to high. The number average molecular weight Mn of the polyester polyol (a1) is preferably 100 to 100,000, or it can be 100 to 10,000.

[0060] As the polyether polyol (a2), polyether polyols commonly used in the manufacture of urethane prepolymers may be appropriately employed. Examples of such polyether polyols (a2) include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol (sometimes also called polytetramethylene ether glycol), which contain two or more functional groups. Representative examples include polyether polyols containing at least one group selected from the group consisting of methylene (-CH2-) and methine (-CH(CH3)-). A portion of the polyether polyol may be replaced with glycols such as ethylene glycol, polyamines such as ethylenediamine, etc., as needed.

[0061] The molecular weight of the polyether polyol (a2) can range from low to high. The number average molecular weight Mn of the polyether polyol (a2) is preferably 100 to 100,000, or it can be 100 to 10,000.

[0062] As a polyether polyol (a2), only difunctional polyether polyols can be used, or polyether polyols with a number average molecular weight Mn of 100 to 100,000 and having at least 3 hydroxyl groups in one molecule can be used in whole or in part.

[0063] One embodiment of the polyol is embodiment (A) which includes both polyester polyol (a1) and polyether polyol (a2).

[0064] In embodiment (A), the polyether polyol (a2) is typically a polyether polyol containing at least one group selected from the group consisting of methylene and methine, for example, it can be one or more polyether polyols (a2-1) containing at least one group selected from the group consisting of methylene and methine, or it can be one or more polyether polyols (a2-2) containing at least one group selected from the group consisting of methylene and methine, or it can be a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2).

[0065] In embodiment (A), when the polyether polyol (a2) is a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2), from the perspective of further demonstrating the effects of the present invention, the weight ratio of polyether polyol (a2-2) to 100 parts by weight of polyether polyol (a2-1) is preferably 1 part by weight to 10,000 parts by weight, can be 5 parts by weight to 1,000 parts by weight, can be 8 parts by weight to 150 parts by weight, or can be 10 parts by weight to 100 parts by weight.

[0066] Polyether polyols (a2-1) that contain at least one group selected from the group consisting of methylene and methine are, for example, polyethylene glycol and polypropylene glycol.

[0067] As a polyether polyol (a2-2) comprising at least one group selected from the group consisting of methylene and methine, polytetramethylenediol can be listed as an example.

[0068] In embodiment (A), when the polyether polyol (a2) is one or more of the polyether polyol (a2-1), the urethane prepolymer (A) typically comprises an alkylene oxide backbone containing at least one of two groups selected from the group consisting of methylene and methine.

[0069] In embodiment (A), when the polyether polyol (a2) is one or more of the polyether polyol (a2-2), the urethane prepolymer (A) typically comprises an alkylene oxide backbone containing at least one of three or more groups selected from the group consisting of methylene and methine.

[0070] In embodiment (A), when the polyether polyol (a2) is a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2), the urethane prepolymer (A) typically comprises: an alkylene oxide backbone comprising at least one group selected from the group consisting of methylene and methine; and an alkylene oxide backbone comprising at least one group selected from the group consisting of methylene and methine.

[0071] In embodiment (A), the content of polyester polyol (a1) in the polyol is preferably 0.1% to 99.9% by weight, can be 1% to 80% by weight, can be 5% to 60% by weight, can be 10% to 55% by weight, can be 20% to 50% by weight, or can be 25% to 45% by weight.

[0072] In embodiment (A), the content of polyether polyol (a2) in the polyol is preferably 0.1% to 99.9% by weight, can be 20% to 99% by weight, can be 40% to 95% by weight, can be 45% to 90% by weight, can be 50% to 80% by weight, or can be 55% to 75% by weight.

[0073] Another embodiment of the polyol is embodiment (B), which contains a polyether polyol (a2) but not a polyester polyol (a1). In embodiment (B), the polyol is typically composed of a polyether polyol (a2).

[0074] In embodiment (B), the content of polyether polyol (a2) in the polyol is preferably 50% to 100% by weight, can be 70% to 100% by weight, can be 90% to 100% by weight, can be 95% to 100% by weight, or can be 98% to 100% by weight.

[0075] In embodiment (B), the polyether polyol (a2) is typically a polyether polyol containing at least one group selected from the group consisting of methylene and methine. For example, it can be one or more polyether polyols (a2-1) containing at least one group selected from the group consisting of methylene and methine, or it can be one or more polyether polyols (a2-2) containing at least one group selected from the group consisting of methylene and methine, or it can be a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2).

[0076] Polyether polyols (a2-1) that contain at least one group selected from the group consisting of methylene and methine are, for example, polyethylene glycol and polypropylene glycol.

[0077] As a polyether polyol (a2-2) comprising at least one group selected from the group consisting of methylene and methine, polytetramethylenediol can be listed as an example.

[0078] In embodiment (B), when the polyether polyol (a2) is one or more of the polyether polyol (a2-1), the urethane prepolymer (A) typically comprises an alkylene oxide backbone containing at least one of two groups selected from the group consisting of methylene and methine.

[0079] In embodiment (B), when the polyether polyol (a2) is one or more of the polyether polyol (a2-2), the urethane prepolymer (A) typically comprises an alkylene oxide backbone containing at least one group selected from the group consisting of methylene and methine.

[0080] In embodiment (B), when the polyether polyol (a2) is a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2), the urethane prepolymer (A) typically comprises: an alkylene oxide backbone comprising at least one group selected from the group consisting of methylene and methine; and an alkylene oxide backbone comprising at least one group selected from the group consisting of methylene and methine.

[0081] As a compound having polymerizable unsaturated double bonds, any suitable compound may be used within the scope of not impairing the effects of the present invention, as long as it has polymerizable unsaturated double bonds. The compound having polymerizable unsaturated double bonds may be only one type or may be two or more types.

[0082] Examples of compounds having polymerizable unsaturated double bonds include compounds having vinyl groups, compounds having (meth)allyl groups, and compounds having (meth)acryloyl groups. From the perspective of further demonstrating the effects of the present invention, compounds having (meth)acryloyl groups are preferred. The number of polymerizable unsaturated double bonds in a compound can be one or more.

[0083] The content of the compound having polymerizable unsaturated double bonds in the above composition (composition comprising a polyol, a compound having polymerizable unsaturated double bonds, and a crosslinking agent) is preferably 0.01 to 50 parts by weight relative to 100 parts by weight of the polyol, but can be 0.1 to 30 parts by weight, 0.5 to 25 parts by weight, 1.0 to 20 parts by weight, or 1.5 to 15 parts by weight, from the perspective of further demonstrating the effects of the present invention.

[0084] Examples of compounds having a (meth)acryloyl group include (meth)acrylates. Examples of (meth)acrylates include alkyl (meth)acrylates, hydroxyl-containing (meth)acrylates, and nitrogen-containing (meth)acrylates. From the perspective of further demonstrating the effects of the present invention, hydroxyl-containing (meth)acrylates are preferred.

[0085] Examples of hydroxyl-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2,3-hydroxypropyl (meth)acrylate, glyceryl mono(meth)acrylate, glyceryl di(meth)acrylate, cyclohexanediethanol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl acrylate, isocyanuric acid EO or PO modified (meth)acrylate, isocyanuric acid EO or PO modified di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, polypentaerythritol penta(meth)acrylate, dipentaerythritol EO or PO modified penta(meth)acrylate, dipentaerythritol caprolactone modified penta(meth)acrylate, and epoxy (meth)acrylates formed by reacting the epoxy group of an epoxy compound with the carboxyl group of (meth)acrylate.

[0086] Among hydroxyl-containing (meth)acrylates, those having two or more hydroxyl groups are preferred from the perspective of further demonstrating the effects of the present invention. Examples of hydroxyl-containing (meth)acrylates having two or more hydroxyl groups include glycerol mono(meth)acrylate and glycerol di(meth)acrylate. Commercially available examples include those with trade names such as "BLEMMER GLM" (manufactured by Nippon Yuko Co., Ltd.), "BLEMMER GLM-R" (manufactured by Nippon Yuko Co., Ltd.), "BLEMMER GMR-M" (manufactured by Nippon Yuko Co., Ltd.), and "BLEMMER GMR-R" (manufactured by Nippon Yuko Co., Ltd.).

[0087] As a crosslinking agent, any suitable crosslinking agent that can be used to manufacture urethane prepolymers can be used without impairing the effects of the present invention. Polyfunctional isocyanate compounds are preferred as such crosslinking agents. There may be only one type of polyfunctional isocyanate compound, or there may be two or more types.

[0088] As a polyfunctional isocyanate compound, any suitable polyfunctional isocyanate compound may be used without impairing the effects of the present invention. Examples of such polyfunctional isocyanate compounds include polyfunctional aliphatic isocyanate compounds, polyfunctional alicyclic isocyanate compounds, polyfunctional aromatic isocyanate compounds, and polyfunctional aromatic aliphatic isocyanate compounds.

[0089] Examples of multifunctional aliphatic isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylidene diisocyanate, 1,3-butylidene diisocyanate, 2,3-butylidene diisocyanate, dodecamethyl diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0090] Examples of polyfunctional alicyclic isocyanate compounds include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylene bis(cyclohexyl isocyanate), 1,4-bis(isocyanate methyl)cyclohexane, hydrogenated diphenylmethane diisocyanate, hydrogenated phenyl diisocyanate, hydrogenated methyl phenylene diisocyanate, and hydrogenated tetramethylphenyl diisocyanate.

[0091] Examples of polyfunctional aromatic isocyanate compounds include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-methylphenylene diisocyanate, 2,6-methylphenylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4',4”-triphenylmethane triisocyanate, bianisidine diisocyanate, and phenyl dimethyl diisocyanate.

[0092] Examples of polyfunctional aromatic aliphatic isocyanate compounds include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylbenzene dimethyl diisocyanate, and 1,3-tetramethylbenzene dimethyl diisocyanate.

[0093] Examples of polyfunctional isocyanate compounds include trimethylolpropane adducts, biuret forms formed by the reaction with water, and trimers containing isocyanurate rings, as described above. Furthermore, they can be used in combination.

[0094] The amount of crosslinking agent that can be used to obtain the urethane prepolymer (A) is preferably 0.001 to 50 parts by weight relative to 100 parts by weight of the polyol, and can be 0.01 to 40 parts by weight, 0.1 to 35 parts by weight, 1 to 35 parts by weight, 5 to 35 parts by weight, or 10 to 35 parts by weight.

[0095] A catalyst can be used in the preparation of urethane prepolymer (A). Any suitable catalyst can be used as the catalyst for preparing urethane prepolymer (A). Examples of such catalysts include tertiary amine compounds and organometallic compounds. There can be only one catalyst or two or more catalysts.

[0096] Examples of tertiary amine compounds include triethylamine, triethylenediamine, and 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU).

[0097] As organometallic compounds, examples include bismuth catalysts such as bismuth octanoate, bismuth neodecanoate, bismuth naphthenate, and bismuth rosinate; tin catalysts such as dibutyltin dilaurate (DBTDL) and dioctyltin dilaurate (DOTDL); titanium catalysts such as dibutyltitanium dichloride, tetrabutyl titanate, butoxytitanium trichloride, and tetraacetylacetone titanium; iron catalysts such as ferric 2-ethylhexanoate and ferric acetylacetone; cobalt catalysts such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc catalysts such as zinc octanoate, zinc naphthenate, and zinc 2-ethylhexanoate; and zirconium catalysts such as zirconium naphthenate.

[0098] When a catalyst is used in the preparation of urethane prepolymer (A), the amount of catalyst used relative to the total amount of polyol, compound having polymerizable unsaturated double bond and crosslinking agent is preferably 0.0001 wt% to 1.0 wt%, can be 0.001 wt% to 1.0 wt%, can be 0.003 wt% to 1.0 wt%, or can be 0.005 wt% to 1.0 wt%.

[0099] When a catalyst is used in the preparation of urethane prepolymer (A), the reaction temperature is preferably below 100°C, and can be 60°C to 90°C. If the temperature reaches above 100°C, it may be difficult to control the reaction rate and crosslinking structure.

[0100] When preparing the urethane prepolymer (A), a catalyst may not be used. In this case, the reaction temperature can be 100 °C or higher.

[0101] As a method for preparing the urethane prepolymer (A), for example, the following can be cited: 1) a method of putting all of a polyol, a compound having a polymerizable unsaturated double bond, a crosslinking agent, and a catalyst into a flask; 2) a method of putting a part or all of the polyol, a part or all of the compound having a polymerizable unsaturated double bond, and a catalyst into a flask, and adding a part or all of the crosslinking agent. In the method of 2), after adding a part or all of the crosslinking agent, the remaining amount of the polyol, the remaining amount of the compound having a polymerizable unsaturated double bond, and the remaining amount of the crosslinking agent can be additionally added.

[0102] When preparing the urethane prepolymer (A), any suitable solvent can be used. As such a solvent, for example, methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone can be cited. Among these solvents, toluene is preferred.

[0103] When preparing the urethane prepolymer (A), any suitable other components can be used in any suitable amount within the range that does not impair the effects of the present invention. As other components, for example, a crosslinking accelerator, a silane coupling agent, an antistatic agent, an antioxidant, an ultraviolet absorber, a light stabilizer, other resin components, a tackifier, a crosslinking retarder, an inorganic filler, an organic filler, a colorant (such as a pigment, a dye, etc.), a chain transfer agent, a plasticizer, a softening agent, an anti-aging agent, a conductive agent, a foil, a surface lubricant, a leveling agent, a corrosion inhibitor, a heat stabilizer, an inhibitor, and a lubricant can be cited. The other components can be only one kind or two or more kinds.

[0104] <A-2-2. Crosslinking agent (B)> The urethane prepolymer (A) typically reacts with the crosslinking agent (B) to form a urethane-based resin. The crosslinking agent (B) can be only one kind or two or more kinds.

[0105] As the crosslinking agent (B), as long as it is a crosslinking agent that can be used for manufacturing a urethane-based resin, any suitable crosslinking agent can be adopted within the range that does not impair the effects of the present invention. As such a crosslinking agent, a polyfunctional isocyanate compound is preferred. The polyfunctional isocyanate compound can be only one kind or two or more kinds.

[0106] As the polyfunctional isocyanate compound, any suitable polyfunctional isocyanate compound that can be used in the urethanization reaction can be employed. As such a polyfunctional isocyanate compound, for example, the polyfunctional isocyanate compound described above that can react with a polyol to obtain the urethane prepolymer (A) can be used. The polyfunctional isocyanate compound that reacts with the urethane prepolymer (A) to form a urethane-based resin can be the same as or different from the polyfunctional isocyanate compound described above that can react with a polyol to obtain the urethane prepolymer (A).

[0107] The equivalent ratio of the NCO group in the polyfunctional isocyanate compound to the OH group in the urethane prepolymer (A), expressed as NCO group / OH group, is preferably 0.2 to 1.8, can be 0.2 to 1.6, can be 0.3 to 1.4, can be 0.3 to 1.2, can be 0.4 to 1.1, can be 0.4 to 0.8. If the equivalent ratio of the NCO group / OH group is within the above range, the effects of the present invention can be further exhibited.

[0108] The content of the crosslinking agent (B) in the adhesive composition can be any appropriate amount within the range that does not impair the effects of the present invention. The content of such a crosslinking agent (B) is preferably 0.4 parts by weight to 13 parts by weight, can be 0.5 parts by weight to 11 parts by weight, can be 0.6 parts by weight to 9.0 parts by weight, can be 0.7 parts by weight to 7.0 parts by weight, can be 0.8 parts by weight to 5.0 parts by weight, can be 0.9 parts by weight to 3.0 parts by weight, relative to 100 parts by weight of the urethane prepolymer (A). When the content of the crosslinking agent (B) relative to 100 parts by weight of the urethane prepolymer (A) is within the above range, the effects of the present invention can be further exhibited.

[0109] <A-2-3. Photoinitiator (C)> The adhesive composition contains a photoinitiator (C). The photoinitiator (C) can be only one kind or two or more kinds.

[0110] As the photoinitiator (C), any suitable photoinitiator can be employed within the range that does not impair the effects of the present invention. As such a photoinitiator (C), for example, benzoin ether-based photoinitiators, acetophenone-based photoinitiators, α-ketol-based photoinitiators, aromatic sulfonyl chloride-based photoinitiators, photoactive oxime-based photoinitiators, benzoin-based photoinitiators, benzil-based photoinitiators, benzophenone-based photoinitiators, ketal-based photoinitiators, thioxanthone-based photoinitiators can be cited.

[0111] As benzoin ether-based photoinitiators, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenyl-ethan-1-one, anisic methyl ether can be cited. As acetophenone-based photoinitiators, for example, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-(tert-butyl)dichloroacetophenone can be cited. As α-ketol-based photoinitiators, for example, 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one can be cited. As aromatic sulfonyl chloride-based photoinitiators, for example, 2-naphthalenesulfonyl chloride can be cited. As photoactive oxime-based photoinitiators, for example, 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime can be cited. As benzoin-based photoinitiators, for example, benzoin can be cited. As benzil-based photoinitiators, for example, benzil can be cited. As benzophenone-based photoinitiators, for example, benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone can be cited. As ketal-based photoinitiators, for example, benzil dimethyl ketal can be cited. As thioxanthone-based photoinitiators, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone can be cited.

[0112] The content of the photoinitiator (C) in the adhesive composition can be any appropriate amount within the range that does not impair the effects of the present invention. The content of such a photoinitiator (C) is preferably 0.001 parts by weight to 20 parts by weight, can be 0.01 parts by weight to 10 parts by weight, and can also be 0.1 parts by weight to 5 parts by weight with respect to 100 parts by weight of the urethane prepolymer (A).

[0113] <A-2-4. Ionic compound (D)> The adhesive composition contains an ionic compound (D). The ionic compound (D) can be only 1 type or 2 or more types.

[0114] As the ionic compound (D), a representative one is an ionic compound composed of a cation species selected from the group consisting of onium cations and metal cations and an anion species other than a borate anion.

[0115] From the perspective of further demonstrating the effects of the present invention, the ionic compound (D) is preferably in a liquid state at 23°C and atmospheric pressure. When the ionic compound (D) is not in a liquid state at 23°C and atmospheric pressure (e.g., in powder form), it may not be able to fully demonstrate the effects of the present invention. For example, it may not exhibit sufficient strong adhesion to the adhered object before ultraviolet irradiation, and it may not exhibit excellent easy peelability that allows it to be easily peeled off from the adhered object after ultraviolet irradiation. In addition, when using it after manufacturing a surface protective film and storing it for a long time, it may not be able to maintain the sufficient strong adhesion before ultraviolet irradiation.

[0116] Regarding the ionic compound (D), from the perspective of being able to further demonstrate the effects of the present invention, as a cation type, it is preferable to use a cation type selected from the group consisting of onium cations and metal cations.

[0117] As the onium cation, any suitable onium cation can be used within the scope of not impairing the effects of the present invention. From the perspective of further demonstrating the effects of the present invention, at least one onium cation selected from nitrogen-containing onium cations, sulfur-containing onium cations, and phosphorus-containing onium cations can be cited as examples.

[0118] Representative embodiments of onium cations are those represented by general formulas (A) to (E). In formula (A), R a R represents a hydrocarbon group with 4 to 20 carbon atoms. b R c Each can independently represent a hydrogen or a hydrocarbon group with 1 to 16 carbon atoms. It should be noted that R... a R b R c It can contain heteroatoms. Additionally, if the nitrogen atom is bonded via a double bond, there is no R. c .

[0119] In equation (B), R d R represents a hydrocarbon group with 2 to 20 carbon atoms. e R f R g Each can independently represent a hydrogen or a hydrocarbon group with 1 to 16 carbon atoms. R d R e R f R g It can contain heteroatoms.

[0120] In equation (C), R h R represents a hydrocarbon group with 2 to 20 carbon atoms. i R j R kEach can independently represent a hydrogen or a hydrocarbon group with 1 to 16 carbon atoms. R h R i R j R k It can contain heteroatoms.

[0121] In formula (D), Z represents nitrogen, sulfur, or phosphorus atoms, and R l R m R n R o Each group independently represents a hydrocarbon group with 1 to 20 carbon atoms and may contain heteroatoms. When Z represents a sulfur atom, R is absent. o .

[0122] In equation (E), R p A hydrocarbon group representing 1 to 18 carbon atoms, which may contain heteroatoms.

[0123] Examples of cations represented by formula (A) include pyridinium cations, piperidinium cations, pyrrolidineium cations, cations with a pyrrololine skeleton, and cations with a pyrrole skeleton.

[0124] Specific examples of pyridinium cations include 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-ethyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl-3-methylpyridinium cation, 1-octyl-4-methylpyridinium cation, and 1-butyl-3,4-dimethylpyridinium cation.

[0125] Specific examples of piperidinium cations include 1-propylpiperidinium cation, 1-pentylpiperidinium cation, 1,1-dimethylpiperidinium cation, 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-propylpiperidinium cation, 1-methyl-1-butylpiperidinium cation, 1-methyl-1-pentylpiperidinium cation, 1-methyl-1-hexylpiperidinium cation, and 1- Methyl-1-heptylpiperidinium cation, 1-ethyl-1-propylpiperidinium cation, 1-ethyl-1-butylpiperidinium cation, 1-ethyl-1-pentylpiperidinium cation, 1-ethyl-1-hexylpiperidinium cation, 1-ethyl-1-heptylpiperidinium cation, 1,1-dipropylpiperidinium cation, 1-propyl-1-butylpiperidinium cation, 1,1-dibutylpiperidinium cation.

[0126] Specific examples of pyrrolidine-onium cations include 1,1-dimethylpyrrolidine-onium cation, 1-methyl-1-ethylpyrrolidine-onium cation, 1-methyl-1-propylpyrrolidine-onium cation, 1-methyl-1-butylpyrrolidine-onium cation, 1-methyl-1-pentylpyrrolidine-onium cation, 1-methyl-1-hexylpyrrolidine-onium cation, and 1-methyl-1-heptylpyrrolidine-onium cation. Ions, 1-ethyl-1-propylpyrrolidineonium cation, 1-ethyl-1-butylpyrrolidineonium cation, 1-ethyl-1-pentylpyrrolidineonium cation, 1-ethyl-1-hexylpyrrolidineonium cation, 1-ethyl-1-heptylpyrrolidineonium cation, 1,1-dipropylpyrrolidineonium cation, 1-propyl-1-butylpyrrolidineonium cation, 1,1-dibutylpyrrolidineonium cation.

[0127] Examples of cations represented by formula (B) include imidazolium cation, tetrahydropyrimidineonium cation, and dihydropyrimidineonium cation.

[0128] Specific examples of imidazolium cations include 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, and 1-hexyl-2,3-dimethylimidazolium cation.

[0129] Specific examples of tetrahydropyrimidine-onium cations include 1,3-dimethyl-1,4,5,6-tetrahydropyrimidine-onium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidine-onium cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidine-onium cation, and 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidine-onium cation.

[0130] Specific examples of dihydropyrimidine-onium cations include 1,3-dimethyl-1,4-dihydropyrimidine-onium cation, 1,3-dimethyl-1,6-dihydropyrimidine-onium cation, 1,2,3-trimethyl-1,4-dihydropyrimidine-onium cation, 1,2,3-trimethyl-1,6-dihydropyrimidine-onium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidine-onium cation, and 1,2,3,4-tetramethyl-1,6-dihydropyrimidine-onium cation.

[0131] Examples of cations represented by formula (C) include pyrazolium cation and dihydropyrazolium cation.

[0132] Specific examples of the cations represented by formula (C) include, for example, 1-methylpyrazolium cation, 3-methylpyrazolium cation, and 1-ethyl-2-methyldihydropyrazolium cation.

[0133] Examples of cations represented by formula (D) include tetraalkylammonium cations, trialkylsulfonium cations, and tetraalkylphosphonium cations. Alternatively, cations in which a portion of the alkyl group is substituted with an alkenyl, alkoxy, or epoxy group can also be used. Additionally, R... l R m R n R o As described above, it is a hydrocarbon group with 1 to 20 carbon atoms, preferably an alkyl group with 1 to 20 carbon atoms. Additionally, R... l R m R n R o It can be an aromatic cyclic group or an aliphatic cyclic group.

[0134] Specific examples of cations represented by formula (D) include N,N-dimethyl-N-ethyl-N-propylammonium cation, N,N-dimethyl-N-ethyl-N-butylammonium cation, N,N-dimethyl-N-ethyl-N-pentylammonium cation, N,N-dimethyl-N-ethyl-N-hexylammonium cation, N,N-dimethyl-N-ethyl-N-heptylammonium cation, N,N-dimethyl-N-ethyl-N-nonylammonium cation, N,N-dimethyl-N,N-dipropylammonium cation, N,N-dimethyl-N-propyl-N-butylammonium cation, N,N-dimethyl-N-propyl-N-pentylammonium cation, N,N-dimethyl-N-propyl -N-hexylammonium cation, N,N-dimethyl-N-propyl-N-heptylammonium cation, N,N-dimethyl-N-butyl-N-hexylammonium cation, N,N-dimethyl-N-butyl-N-heptylammonium cation, N,N-dimethyl-N-pentyl-N-hexylammonium cation, N,N-dimethyl-N,N-dihexylammonium cation, trimethylheptylammonium cation, N,N-diethyl-N-methyl-N-propylammonium cation, N,N-diethyl-N-methyl-N-pentylammonium cation, N,N-diethyl-N-methyl-N-heptylammonium cation, N,N-diethyl-N-propyl-N-pentylammonium cation, triethylmethylammonium cation Triethylpropylammonium cation, Triethylpentylammonium cation, Triethylheptylammonium cation, N,N-dipropyl-N-methyl-N-ethylammonium cation, N,N-dipropyl-N-methyl-N-pentylammonium cation, N,N-dipropyl-N-butyl-N-hexylammonium cation, N,N-dipropyl-N,N-dihexylammonium cation, N,N-dibutyl-N-methyl-N-pentylammonium cation, N,N-dibutyl-N-methyl-N-hexylammonium cation, Trioctylmethylammonium cation, N-methyl-N-ethyl-N-propyl-N-pentylammonium cation, Tetramethylammonium cation, Tetraethylammonium cation, Tetrabutylammonium cation, Tetrahexylammonium cation Tetraalkylammonium cations include tributylethylammonium cation, trimethyldecylammonium cation, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, etc.; trialkylsulfonium cations include trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, trihexylsulfonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation, etc.; tetraalkylphosphonium cations include tetramethylphosphonium cation, tetraethylphosphonium cation, tetrabutylphosphonium cation, tetrahexylphosphonium cation, phosphonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, etc.

[0135] Specific examples of the cation represented by formula (E) include alkyl groups having 1 to 18 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl, octyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl, and octadecyl, as R. p Sulfonate.

[0136] As the metal cation, any suitable metal cation can be used within the scope of not impairing the effects of the present invention. From the perspective of further demonstrating the effects of the present invention, alkali metal cations such as Li cation, Na cation, and K cation are preferred as such metal cations.

[0137] Regarding the ionic compound (D), from the perspective of further demonstrating the effects of the present invention, it is preferable to use an anion type that is not a borate anion. When a borate anion is used as the anion type, the effects of the present invention may not be manifested. In particular, when a borate anion is used as the anion type, even if the generation of static electricity when peeling the surface protective film from the adhered object can be suppressed, when the surface protective film is manufactured and stored for a long period of time, it may not be able to maintain sufficient strong adhesion during the period when surface protection is required. Examples of such borate anions include, for example, bis(oxalate)borate anion, bis(mandelato)borate anion, bis(salicylate)borate anion, bis(malonate)borate anion, bis(succinate)borate anion, bis(glutarate)borate anion, and bis(adipate)borate anion.

[0138] As an anion that is not a borate anion, any suitable anion that is not a borate anion can be used without impairing the effects of the present invention. From the perspective of further demonstrating the effects of the present invention, examples of anions that are not such borate anions include, for example, fluoride-containing anions.

[0139] As a fluorinated anion, any suitable fluorinated anion may be used within the scope of not impairing the effects of the present invention.

[0140] Examples of such fluorinated anions include fluorinated aryl sulfonates, perfluoroalkane sulfonates, bis(fluorosulfonyl)imides, bis(perfluoroalkane sulfonyl)imides, cyanoperfluoroalkane sulfonyl amides, bis(cyano)perfluoroalkane sulfonyl methylates, cyano-bis-(perfluoroalkane sulfonyl)methylates, tri(perfluoroalkane sulfonyl)methylates, trifluoroacetates, perfluoroalkylates, tri(perfluoroalkane sulfonyl)methylates, and (perfluoroalkane sulfonyl)trifluoroacetamide. Specifically, examples include trifluoromethane sulfonates, pentafluoroethane sulfonates, heptafluoropropane sulfonates, nonafluorobutane sulfonates, bis(fluorosulfonyl)imides, and bis(trifluoromethane sulfonyl)imides.

[0141] As ionic compounds (D), from the perspective of further demonstrating the effects of the present invention, the following are preferably included: 1-hexylpyridinium bis(fluorosulfonyl)imide, 1-ethyl-3-methylpyridinium trifluoromethane sulfonate, 1-ethyl-3-methylpyridinium pentafluoroethane sulfonate, 1-ethyl-3-methylpyridinium heptafluoropropane sulfonate, 1-ethyl-3-methylpyridinium nonafluorobutane sulfonate, 1-butyl-3-methylpyridinium trifluoromethane sulfonate, etc. Fluoromethane sulfonate, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpyrrolidine bis(fluorosulfonyl)imide, 1-methyl-1-propylpiperidine bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpiperidine bis(fluorosulfonyl)imide Imide, 1-Ethyl-3-methylimidazolium trifluoromethane sulfonate, 1-Ethyl-3-methylimidazolium heptafluoropropane sulfonate, 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-Hexyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-Octyl-3-methylimidazolium bis(fluorosulfonyl)imide, Methyltrioctylammonium bis(trifluoromethanesulfonyl)imide Sulfonyl)imide, trimethylpropylammonium bis(trifluoromethanesulfonyl)imide, 1-allyl-3-methyl-imidazolium trifluoromethanesulfonate, 1-allyl-3-methyl-imidazolium heptafluoropropanesulfonate, 1-allyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide, 1-allyl-3-methyl-imidazolium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide.

[0142] Regarding the content ratio of the ionic compound (D) relative to 100 parts by weight of the urethane prepolymer (A), from the aspect of being able to further exhibit the effects of the present invention, it is preferably 0.01 part by weight to 10 parts by weight, may be 0.03 part by weight to 7.0 parts by weight, may be 0.05 part by weight to 5.0 parts by weight, may be 0.1 part by weight to 3.0 parts by weight, may be 0.3 part by weight to 2.5 parts by weight, may be 0.5 part by weight to 2.0 parts by weight, may be 0.5 part by weight to 1.5 parts by weight. When the content ratio of the ionic compound (D) relative to 100 parts by weight of the urethane prepolymer (A) is too small and deviates from the above range, it may be impossible to exhibit the effects of the present invention. For example, it may not be able to exhibit sufficient strong adhesive force to the adherend before ultraviolet irradiation, may not be able to exhibit excellent light peelability that can be smoothly peeled from the adherend after ultraviolet irradiation, may not be able to maintain sufficient strong adhesive force before ultraviolet irradiation when manufacturing a surface protective film and using it after long-term storage, and may generate obvious static electricity when peeling from the adherend. When the content ratio of the ionic compound (D) relative to 100 parts by weight of the urethane prepolymer (A) is too large and exceeds the above range, it may contaminate the adherend.

[0143] Commercially available products can be used as the ionic compound, or substances synthesized by any appropriate method can also be used. For example, ionic liquids can be synthesized by the halide method, hydroxide method, acid ester method, complex formation method, and neutralization method described in "Ionic Liquids - The Frontiers and Future of Development -" (published by CMC).

[0144] <A-2-5. Urethane (meth)acrylate (E)> The adhesive composition may contain urethane (meth)acrylate (E). When the adhesive composition contains urethane (meth)acrylate (E), the effects of the present invention can be further exhibited. For example, it can exhibit more sufficient strong adhesive force to the adherend before ultraviolet irradiation and more excellent light peelability that can be smoothly peeled from the adherend after ultraviolet irradiation.

[0145] The urethane (meth)acrylate (E) may be only one kind or two or more kinds.

[0146] From the perspective of further demonstrating the effects of the present invention, the content of urethane (meth)acrylate (E) in the adhesive composition is preferably 0.5 parts by weight to 50 parts by weight relative to 100 parts by weight of urethane prepolymer (A), and can be 1.0 parts by weight to 40 parts by weight, 1.5 parts by weight to 30 parts by weight, 2.0 parts by weight to 20 parts by weight, 2.5 parts by weight to 15 parts by weight, 3.0 parts by weight to 10 parts by weight, or 3.0 parts by weight to 8.0 parts by weight.

[0147] Regarding the number of functional groups in urethane (meth)acrylate (E), from the perspective of further demonstrating the effects of the present invention, it is preferably 2 or more, can be 3 or more, can be 3 to 20, can be 4 to 10, can be 4 to 8, or can be 6. If the number of functional groups in urethane (meth)acrylate (E) is set within the above range, the effects of the present invention can be further demonstrated.

[0148] From the perspective of further demonstrating the effects of the present invention, urethane (meth)acrylate (E) preferably has the structure shown in the following general formula (1). If urethane (meth)acrylate (E) has the structure shown in the following general formula (1), the effects of the present invention can be further demonstrated, for example, it can exhibit more sufficient strong adhesion to the adherend before ultraviolet irradiation, and can exhibit more excellent light peelability after ultraviolet irradiation, which allows for smooth peeling from the adherend. From the perspective of further demonstrating the effects of the present invention, urethane (meth)acrylate (E) preferably has the structure shown in the following general formula (1a). If urethane (meth)acrylate (E) has the structure shown in the following general formula (1a), the effects of the present invention can be further demonstrated, for example, it can exhibit more sufficient strong adhesion to the adherend before ultraviolet irradiation, and can exhibit more excellent light peelability after ultraviolet irradiation, which allows for smooth peeling from the adherend. From the perspective of further demonstrating the effects of the present invention, urethane (meth)acrylate (E) preferably has the structure shown in the following general formula (2). If urethane (meth)acrylate (E) has the structure shown in the following general formula (2), the effects of the present invention can be further demonstrated, for example, it can exhibit more sufficient strong adhesion to the adherend before ultraviolet irradiation, and can exhibit more excellent light peelability after ultraviolet irradiation, which allows for smooth peeling from the adherend. In general formula (2), X is a divalent aromatic group or a divalent aliphatic group.

[0149] As a divalent aromatic group, any suitable divalent aromatic group can be used without impairing the effects of the present invention. Examples of divalent aromatic groups include phenyl-1,4-diyl, phenyl-1,3-diyl, phenyl-1,2-diyl, toluene-2,4-diyl, toluene-2,5-diyl, toluene-2,6-diyl, 4,6-dimethylphenyl-1,3-diyl, 2,5-dimethylphenyl-1,4-diyl, 2,6-dimethylphenyl-1,4-diyl, 2,4,6-trimethylphenyl-1,3-diyl, 2,3,5,6-tetramethylphenyl-1,4-diyl, m-phenylenedimethyl-diyl, p-phenylenedimethyl-diyl, naphthalene-1,2-diyl, naphthalene-1,3-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-1,6-diyl, naphthalene-1,7-diyl, naphthalene-1,8-diyl, naphthalene-2,3-diyl, and naphthalene-2,6-diyl.

[0150] As a divalent aliphatic group, any suitable divalent aliphatic group can be used without impairing the effects of the present invention. Examples of divalent aliphatic groups include divalent chain aliphatic groups and divalent aliphatic groups containing cyclic structures.

[0151] As a divalent chain aliphatic group, it can be either straight-chain or branched. Examples of divalent chain aliphatic groups include methylene, ethane-1,1-diyl, ethane-1,2-diyl, propane-1,1-diyl, propane-1,3-diyl, propane-2,2-diyl, pentane-1,5-diyl, and hexane-1,6-diyl.

[0152] Examples of divalent aliphatic groups with cyclic structures include those with cycloalkane ring structures (e.g., cyclohexyl ring structures). Examples of divalent aliphatic groups with cyclic structures include those represented by the general formula (3) below. It should be noted that the two bonds marked with * in general formula (3) are the bonds that function as divalent groups. From the perspective of further demonstrating the effects of the present invention, the urethane (meth)acrylate (E) preferably has a molecular weight of less than 1000. If the molecular weight of the urethane (meth)acrylate (E) is 1000 or higher, the effects of the present invention may not be manifested.

[0153] As urethane (meth)acrylates (E), for example, compounds having the structure represented by the following general formula (4) can be listed. In the general formula (4), X is as described above.

[0154] <A-2-6. Other components> Within the range not impairing the effects of the present invention, the adhesive composition may contain any appropriate other components. Examples of such other components include solvents, catalysts, crosslinking accelerators, silane coupling agents, antioxidants, ultraviolet absorbers, light stabilizers, other resin components, tackifiers, crosslinking retarders, inorganic fillers, organic fillers, metal powders, colorants (pigments, dyes, etc.), chain transfer agents, plasticizers, softeners, anti-aging agents, conductive agents, foils, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, lubricants. The other components may be only one kind, or two or more kinds.

[0155] 《A-3. Substrate layer》 The substrate layer may be only one layer, or two or more layers. The substrate layer may be a stretched substrate layer.

[0156] The thickness of the substrate layer is preferably 4 μm to 450 μm, may be 8 μm to 400 μm, may be 12 μm to 350 μm, or may be 16 μm to 250 μm.

[0157] For the surface of the substrate layer where the adhesive layer is not attached, in order to form a winding body that is easy to unwind, etc., for example, fatty acid amides, polyethyleneimine, long-chain alkyl-based additives, etc. may be added to the substrate layer for release treatment, or a coating formed of any appropriate release agent such as silicone-based, long-chain alkyl-based, fluorine-based, etc. may be provided.

[0158] An antistatic layer may be provided on one side of the substrate layer where the adhesive layer is not attached. As the antistatic layer, any appropriate antistatic layer may be adopted within the range not impairing the effects of the present invention. Such an antistatic layer may contain, for example, antistatic agents. As the antistatic agent, any appropriate antistatic agent may be adopted within the range not impairing the effects of the present invention. Examples of such antistatic agents include conductive polymers, carbon nanotubes, ionic compounds, carbon, surfactants, alkali metal salts, metal oxides, and metal fine particles.

[0159] As the material of the substrate layer, any appropriate material may be adopted according to the use. For example, plastics, paper, metal films, non-woven fabrics, etc. may be mentioned. Plastics are preferred. That is, the substrate layer is preferably a plastic film. The substrate layer may be composed of one kind of material, or two or more kinds of materials. For example, it may also be composed of two or more kinds of plastics.

[0160] Examples of the aforementioned plastics include polyester resins, polyamide resins, and polyolefin resins. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0161] The substrate layer may contain any suitable additives as needed. Examples of additives that may be included in the substrate layer include antioxidants, UV absorbers, light stabilizers, antistatic agents, fillers, and pigments. The type, quantity, and amount of additives that may be included in the substrate layer can be appropriately determined according to the purpose. In particular, when the substrate layer material is plastic, it is preferable to include some of the above-mentioned additives to prevent deterioration. From the viewpoint of improving weather resistance, antioxidants, UV absorbers, light stabilizers, and fillers are particularly preferred as additives.

[0162] 《B. Application》 The surface protective film of embodiments of the present invention is typically applied to the exposed surface of optical components or electronic components during the manufacturing process of optical or electronic components to prevent damage to the surface of the components during processing, assembly, inspection, and transportation. It is suitable for surface protection of optical or electronic components. Optical devices according to embodiments of the present invention include the adhesive film of embodiments of the present invention. Electronic devices according to embodiments of the present invention include the adhesive film of embodiments of the present invention.

[0163] [Examples] Hereinafter, the present invention will be specifically described through examples, but the present invention is not limited to these examples in any way. It should be noted that the testing and evaluation methods in the examples, etc., are as follows. It should be noted that when recorded as "parts", unless otherwise specified, it refers to "parts by weight", and when recorded as "%", unless otherwise specified, it refers to "% by weight".

[0164] Initial adhesion of glass plates before UV irradiation The protective film (25mm wide x 140mm long) with the release liner removed was adhered to a glass plate (soda-lime glass, manufactured by Matsunami Glass Industry Co., Ltd.) by pressing it once with a 2kg hand roller. Then, it was placed in an environment of 23°C and 55%RH for 30 minutes to obtain an evaluation sample.

[0165] The obtained evaluation samples were tested using a tensile testing machine at a temperature of 23°C and a humidity of 55%RH. The tensile testing machine used was the Shimadzu Autograph AG-Xplus HS 6000mm / min high-speed mode (AG-50NX plus). The evaluation samples were placed on the tensile testing machine, and the tensile test was started. The tensile test conditions were set as follows: peel angle: 180 degrees; peel speed (tensile speed): 300mm / min. The load at which the surface protective film was peeled from the glass plate was measured, and the average load at this point was taken as the initial adhesion force of the surface protective film to the glass plate before UV irradiation.

[0166] Initial adhesion of glass plate before UV irradiation after 1 week of storage After manufacturing the surface protective film, it was stored at 23°C and 55%RH for one week. Then, the surface protective film (25mm wide × 140mm long) with the release liner removed was adhered to a glass plate (soda-lime glass, manufactured by Matsunami Glass Industry Co., Ltd.) by pressing it once with a 2kg hand roller. The sample was then placed at 23°C and 55%RH for 30 minutes to obtain the evaluation sample.

[0167] The obtained evaluation samples were tested using a tensile testing machine at a temperature of 23°C and a humidity of 55%RH. The tensile testing machine used was the Shimadzu Autograph AG-Xplus HS 6000mm / min high-speed mode (AG-50NX plus). The evaluation samples were placed on the tensile testing machine, and the tensile test was started. The tensile test conditions were set as follows: peel angle: 180 degrees, peel speed (tensile speed): 300mm / min. The load at which the surface protective film was peeled from the glass plate was measured, and the average load at this point was taken as the initial adhesion force of the surface protective film before UV irradiation of the glass plate after one week of storage.

[0168] Initial adhesion strength of glass plates after UV irradiation The protective film (25mm wide x 140mm long) with the release liner removed was adhered to the glass plate (soda-lime glass, manufactured by Matsunami Glass Industry Co., Ltd.) by pressing it once with a 2kg hand roller. Then, it was irradiated with a cumulative light intensity of 700mJ / cm² using an LED light source with a wavelength of 365nm. 2 The adhesive layer is light-cured by ultraviolet light, and then placed in an environment of 23°C and 55%RH for 30 minutes to obtain the evaluation sample.

[0169] The obtained evaluation samples were tested using a tensile testing machine at a temperature of 23°C and a humidity of 55%RH. The tensile testing machine used was the Shimadzu Autograph AG-Xplus HS 6000mm / min high-speed mode (AG-50NX plus). The evaluation samples were placed on the tensile testing machine, and the tensile test was started. The tensile test conditions were set as follows: peel angle: 180 degrees; peel speed (tensile speed): 300mm / min. The load at which the surface protective film was peeled from the glass plate was measured, and the average load at this point was taken as the initial adhesion force of the surface protective film to the glass plate after UV irradiation.

[0170] <Increase in adhesion strength of glass plates before UV irradiation> The rate of increase in the initial adhesive force of the glass plate before UV irradiation after one week of storage is taken as the rate of increase in the adhesive force of the glass plate before UV irradiation, and is calculated by the following formula.

[0171] Increase rate of adhesion strength of glass plate before UV irradiation (%) = (Initial adhesion strength of glass plate before UV irradiation after 1 week of storage / Initial adhesion strength of glass plate before UV irradiation) × 100 (%) <Change in initial adhesive strength of glass plate before / after UV irradiation> The ratio of the change in initial adhesive force of the glass plate before UV irradiation to the change in initial adhesive force of the glass plate after UV irradiation is set as the ratio of the change in initial adhesive force of the glass plate before / after UV irradiation, and is calculated by the following formula.

[0172] Change in initial adhesion strength of glass plate before / after UV irradiation (times) = Initial adhesion strength of glass plate before UV irradiation / Initial adhesion strength of glass plate after UV irradiation <Residual adhesion rate of glass plate after UV irradiation> The protective film (25mm wide x 140mm long) with the release liner removed was adhered to the glass plate (soda-lime glass, manufactured by Matsunami Glass Industry Co., Ltd.) by pressing it once with a 2kg hand roller. Then, it was irradiated with a cumulative light intensity of 700mJ / cm² using an LED light source with a wavelength of 365nm. 2 The adhesive layer is photocured by ultraviolet light to produce an evaluation sample.

[0173] After the obtained evaluation samples were placed in an environment of 23°C and 55%RH for 24 hours, the surface protective film was peeled off using a tensile testing machine under the conditions of peel angle: 180 degrees and peel speed (tensile speed): 300 mm / min.

[0174] Then, on the peeling surface of the glass plate, in an environment of temperature 23°C and humidity 55%RH, a No. 31B tape with a width of 19 mm and a length of 150 mm (manufactured by Nitto Denko Corporation, base material thickness = 25 μm, total thickness = 53 μm) is attached by reciprocating a 2 kg hand roller once, and after being left for 30 minutes in an environment of temperature 23°C and humidity 55%RH, in an environment of temperature 23°C and humidity 55%RH, using a tensile testing machine, the No. 31B tape is peeled under the conditions of peeling angle: 180 degrees, peeling speed (tensile speed): 300 mm / min, and the peeling force (A) is measured.

[0175] For the glass plate without pasting and peeling the surface protective film as described above, a No. 31B tape with a width of 19 mm and a length of 150 mm (manufactured by Nitto Denko Corporation, base material thickness = 25 μm, total thickness = 53 μm) is similarly attached and cut, and after being left for 30 minutes in an environment of temperature 23°C and humidity 55%RH, in an environment of temperature 23°C and humidity 55%RH, using a tensile testing machine, the No. 31B tape is peeled under the conditions of peeling angle: 180 degrees, peeling speed (tensile speed): 300 mm / min, and the peeling force (B) is measured.

[0176] The residual adhesion rate to the glass plate is calculated by the following formula.

[0177] Residual adhesion rate to the glass plate (%) = (Peeling force (A) / Peeling force (B)) × 100 (%) It should be noted that as the tensile testing machine, the product named "Autograph AG-Xplus HS 6000mm / min high-speed mode (AG-50NX plus)" manufactured by Shimadzu Corporation is used.

[0178] The residual adhesion rate after UV irradiation on the glass plate becomes the following index: an index of the degree to which the components contained in the adhesive layer of the surface protective film are transferred to the surface of the adherend and cause contamination. The higher the value of the residual adhesion rate after UV irradiation on the glass plate, the less likely it is that the surface protective film contaminates the surface of the adherend. The lower the value of the residual adhesion rate, the more likely it is that the surface protective film contaminates the surface of the adherend.

[0179] <Surface resistance value of the adhesive surface after UV irradiation> The surface protective film is cut into a size of 50 mm in length and 50 mm in width. Then, ultraviolet rays with an accumulated light amount of 700 mJ / cm are irradiated by an LED light source with a wavelength of 365 nm 2 to photocure the adhesive layer and make a sample for evaluation.

[0180] Under conditions of 23°C and 55%RH, the release liner was peeled off from the obtained evaluation sample to expose the adhesive layer. Using a Trek Japan "Model 152P-2P" instrument, the terminals were pressed at 10V for 10 seconds, and the surface resistivity was measured. It should be noted that the surface resistivity value is sometimes expressed as "x×10". y (Ω)” is marked as “xE+y(Ω)”.

[0181] <Surface resistivity of adhesive surface after UV irradiation after 1 week of storage> The surface protective film, which had been stored at 23°C and 55%RH for one week after manufacturing, was cut into dimensions of 50mm x 50mm. Then, it was irradiated with a 365nm LED light source, accumulating a light intensity of 700mJ / cm². 2 Ultraviolet light is used to photocur the adhesive layer, which is then used to prepare evaluation samples.

[0182] Under conditions of 23°C and 55%RH, the release liner was peeled off from the obtained evaluation sample to expose the adhesive layer. Using a Trek Japan "Model 152P-2P" instrument, the terminals were pressed at 10V for 10 seconds, and the surface resistivity was measured. It should be noted that the surface resistivity value is sometimes expressed as "x×10". y (Ω)” is marked as “xE+y(Ω)”.

[0183] <Abbreviations for ionic compounds used in the examples and comparative examples> • EMI-FSI: 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. • HMI-FSI: 1-Hexyl-3-methylimidazolium bis(fluorosulfonyl)imide. • OMI-FSI: 1-Octyl-3-methylimidazolium bis(fluorosulfonyl)imide. • BMP-TFMSI: 1-Butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide. • Li-TFSI: Lithium bis(trifluoromethanesulfonyl)imide. • HMI-BOB: 1-Hexyl-3-methylimidazolium bis(oxalate)borate. • OMI-BOB: 1-Octyl-3-methylimidazolium bis(oxalate)borate. • Li-BOB: Lithium bis(oxalate)borate.

[0184] [Manufacturing Example 1] Carbamate Prepolymer A In a polymerization experimental apparatus equipped with a 1L round-bottom detachable flask, a detachable cap, a separatory funnel, a thermometer, a dry air inlet tube, a Liebig condenser, a vacuum sealer, a stirring rod, and stirring blades, 39.1g of polytetramethylene glycol (product name "PTMG3000", manufactured by Mitsubishi Chemical Co., Ltd.), 111.9g of polyester polyol (product name "Kuraray Polyol P-2010", manufactured by Kuraray Co., Ltd.), 39.1g of a compound with polymerizable unsaturated double bonds (product name "Blemmer GLM", manufactured by Nippon Oil Co., Ltd.), and 190g of toluene (manufactured by Tosoh Co., Ltd.) as a solvent were added while stirring. 0.09g of bismuth octanoate (manufactured by Nippon Chemical Industry Co., Ltd.) as a catalyst was added, and the mixture was subjected to dry air replacement at room temperature for 2 hours. Then, 60.5 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosoh Co., Ltd.) was added. With dry air flowing in, the solution temperature in the experimental apparatus was controlled at 80±2℃ using a water bath and maintained for 5 hours. Next, 183.8 g of polypropylene glycol (product name "SANNIX GP-1500", manufactured by Sanyo Chemical Co., Ltd.) was added. After the solution temperature in the experimental apparatus was controlled at 80±2℃ using a water bath and maintained for 2 hours, 15.4 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosoh Co., Ltd.) was added. The solution temperature in the experimental apparatus was controlled at 80±2℃ using a water bath and maintained for 2 hours, yielding a solution of urethane prepolymer A. It should be noted that during polymerization, toluene was added dropwise as needed to control the temperature and prevent a decrease in agitation due to increased viscosity. The solids content of the urethane prepolymer A solution was 60% by weight.

[0185] [Example 1] The urethane prepolymer A obtained in Manufacturing Example 1: 100 parts by weight, the isocyanate compound (Coronate HX: C / HX, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent: 1.4 parts by weight, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide as an ionic compound: 0.05 parts by weight, Irganox 1010 (manufactured by BASF) as an antioxidant: 1.0 parts by weight, Omnirad 651 (manufactured by IGM Resins BV) as a photopolymerization initiator: 1.0 parts by weight, and EMBILIZER OL-1 (manufactured by Tokyo Fine Chemicals Co., Ltd.) as a catalyst: 0.03 parts by weight were diluted with ethyl acetate in such a manner that the total solid content was 50% by weight, to obtain a urethane-based adhesive composition (1).

[0186] The obtained urethane-based adhesive composition (1) was coated onto a polyester resin substrate (trade name "T100-75S", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) with a dried thickness of 75 μm. The substrate was then cured at a drying temperature of 110°C for 3 minutes to form an adhesive layer (1). Next, a silicone-treated release liner (trade name "MRF25", manufactured by Mitsubishi Chemical Corporation, thickness 25 μm) made of polyester resin was bonded to the surface of the adhesive layer (1) to obtain a surface protective film (1) consisting of a release liner (thickness 25 μm), adhesive layer (1) (thickness 75 μm), and substrate (thickness 75 μm). The obtained surface protective film (1) was aged at room temperature for 5 days for evaluation. The results are shown in Table 1.

[0187] [Example 2] The amount of ionic compound was changed to 0.1 parts by weight, and otherwise the same procedure was followed as in Example 1 to obtain a surface protective film (2) consisting of a urethane adhesive composition (2), a release liner (25 μm thick), an adhesive layer (2) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (2) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0188] [Example 3] The amount of ionic compound was changed to 0.3 parts by weight, and otherwise the same procedure as in Example 1 was followed to obtain a surface protective film (3) consisting of a urethane adhesive composition (3), a release liner (25 μm thick), an adhesive layer (3) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (3) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0189] [Example 4] The amount of ionic compound was changed to 1.0 parts by weight, and otherwise the same procedure was followed as in Example 1 to obtain a surface protective film (4) consisting of a urethane adhesive composition (4), a release liner (25 μm thick), an adhesive layer (4) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (4) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0190] [Example 5] The amount of ionic compound was changed to 5.0 parts by weight, and otherwise the same procedure as in Example 1 was followed to obtain a surface protective film (5) consisting of a urethane adhesive composition (5), a release liner (25 μm thick), an adhesive layer (5) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (5) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0191] [Example 6] As an ionic compound, 1.0 part by weight of 1-hexyl-3-methylimidazolium bis(fluorosulfonyl)imide was used instead of 0.05 parts by weight of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. Otherwise, the procedure was the same as in Example 1 to obtain a surface protective film (6) consisting of a urethane adhesive composition (6), a release liner (25 μm thick), an adhesive layer (6) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (6) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0192] [Example 7] As an ionic compound, 1.0 part by weight of 1-octyl-3-methylimidazolium bis(fluorosulfonyl)imide was used instead of 0.05 parts by weight of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. Otherwise, the process was the same as in Example 1 to obtain a surface protective film (7) consisting of a urethane adhesive composition (7), a release liner (25 μm thick), an adhesive layer (7) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (7) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0193] [Example 8] As an ionic compound, 1.0 part by weight of 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide was used instead of 0.05 parts by weight of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. Otherwise, the procedure was the same as in Example 1 to obtain a surface protective film (8) consisting of a urethane adhesive composition (8), a release liner (25 μm thick), an adhesive layer (8) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (8) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0194] [Example 9] As an ionic compound, lithium bis(trifluoromethanesulfonyl)imide: 1.0 parts by weight was used instead of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide: 0.05 parts by weight. Otherwise, the process was the same as in Example 1 to obtain a surface protective film (9) consisting of a urethane adhesive composition (9), a release liner (25 μm thick), an adhesive layer (9) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (9) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0195] [Example 10] The urethane prepolymer A obtained in Manufacturing Example 1: 100 parts by weight, the isocyanate compound (Coronate HX: C / HX, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent: 1.4 parts by weight, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide as an ionic compound: 1.0 parts by weight, UA-1100H (manufactured by Shin-Nakamura Chemical Co., Ltd.) as a urethane (meth)acrylate: 5.0 parts by weight, Irganox1010 (manufactured by BASF) as an antioxidant: 1.0 parts by weight, Omnirad651 (manufactured by IGM Resins BV) as a photopolymerization initiator: 1.0 parts by weight, and EMBILIZER OL-1 (manufactured by Tokyo Fine Chemical Co., Ltd.) as a catalyst: 0.03 parts by weight were diluted with ethyl acetate to obtain a urethane-based adhesive composition (10) with a total solid content of 50% by weight.

[0196] The obtained urethane-based adhesive composition (10) was coated onto a polyester resin substrate (trade name "T100-75S", manufactured by Mitsubishi Chemical Corporation, thickness 75 μm) with a dried thickness of 75 μm. The substrate was then cured at a drying temperature of 110°C for 3 minutes to form an adhesive layer (10). Next, a silicone-treated release liner (trade name "MRF25", manufactured by Mitsubishi Chemical Corporation, thickness 25 μm) made of polyester resin was bonded to the surface of the adhesive layer (10) to obtain a surface protective film (10) consisting of a release liner (25 μm thickness), an adhesive layer (10) (75 μm thickness), and a substrate (75 μm thickness). The obtained surface protective film (10) was aged at room temperature for 5 days for evaluation. The results are shown in Table 1.

[0197] [Comparative Example 1] As an ionic compound, 1.0 parts by weight of 1-hexyl-3-methylimidazolium bis(oxalate)borate was used instead of 0.05 parts by weight of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. Otherwise, the process was the same as in Example 1, yielding a surface protective film (C1) consisting of a urethane-based adhesive composition (C1), a release liner (25 μm thick), an adhesive layer (C1) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (C1) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0198] [Comparative Example 2] As an ionic compound, 1.0 parts by weight of 1-octyl-3-methylimidazolium bis(oxalate)borate was used instead of 0.05 parts by weight of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. Otherwise, the process was the same as in Example 1, yielding a surface protective film (C2) consisting of a urethane-based adhesive composition (C2), a release liner (25 μm thick), an adhesive layer (C2) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (C2) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0199] [Comparative Example 3] As an ionic compound, lithium bis(oxalate)borate: 1.0 parts by weight was used instead of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide: 0.05 parts by weight. Otherwise, the procedure was the same as in Example 1, and a surface protective film (C3) consisting of a urethane-based adhesive composition (C3), a release liner (thickness 25 μm), an adhesive layer (C3) (thickness 75 μm), and a substrate (thickness 75 μm) was obtained. The obtained surface protective film (C3) was aged at room temperature for 5 days and evaluated. The results are shown in Table 1.

[0200] [Comparative Example 4] Except for the absence of ionic compounds, the procedure was the same as in Example 1 to obtain a surface protective film (C4) consisting of a urethane-based adhesive composition (C4), a release liner (25 μm thick), an adhesive layer (C4) (75 μm thick), and a substrate (75 μm thick). The obtained surface protective film (C4) was aged at room temperature for 5 days for evaluation. The results are shown in Table 1.

[0201] [Table 1] Industrial availability The surface protective film of the present invention can be used for any suitable application. The surface protective film of the present invention is preferably used in the fields of optical devices and electronic devices.

[0202] Explanation of reference numerals in the attached figures 1: Substrate layer. 2: Adhesive layer. 10: Surface protective film.

Claims

1. A surface protective film, wherein, The surface protective film includes an adhesive layer, the adhesive constituting the adhesive layer being formed by an adhesive composition comprising a urethane prepolymer A, a crosslinking agent B, a photopolymerization initiator C, and an ionic compound D. The urethane prepolymer A has polymerizable unsaturated double bonds, and the ionic compound D is an ionic compound composed of cations selected from the group consisting of onion cations and metal cations and anions that are not borate anions.

2. The surface protective film according to claim 1, wherein, The ionic compound D is liquid at 23°C and atmospheric pressure.

3. The surface protection film of claim 1, wherein, The content of the ionic compound D relative to 100 parts by weight of the urethane prepolymer A is 0.1 parts by weight to 3.0 parts by weight.

4. The surface protection film of claim 1, wherein, The adhesive composition contains urethane (meth)acrylate E.

5. An optical device, wherein, The surface protective film comprising any one of claims 1 to 4.

6. An electronic device, wherein, The surface protective film comprising any one of claims 1 to 4.

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