JP7570928B2 - Reinforcement laminate film - Google Patents

Description

The present invention relates to a reinforcing laminated film.

In order to impart rigidity and impact resistance to optical components, electronic components, etc., a reinforcing film (a reinforcing substrate provided with an adhesive layer) may be attached in advance to the exposed surface of the optical components, electronic components, etc. to reinforce them (Patent Document 1). Such reinforcing films usually have an adhesive layer for attachment, and a separator is usually provided on the surface of the adhesive layer to protect the surface of the adhesive layer until it is used.

Furthermore, in order to prevent the surface of the reinforcing film from being scratched during processing, assembly, inspection, transportation, etc., the reinforcing film may be processed, assembled, inspected, transported, etc. with a surface protective film attached in advance to the exposed surface of the reinforcing film. Such a surface protective film is peeled off from the reinforcing film when surface protection is no longer necessary (Patent Document 2).

In a reinforcing laminate film having such a surface protective film and a separator, it is important that when peeling the separator from the surface of the adhesive layer, the separator can be peeled off smoothly from the surface of the adhesive layer without peeling off at the interface between the surface protective film and the reinforcing film, etc.

Patent No. 6366199 JP 2016-17109 A

The objective of the present invention is to provide a reinforcing laminate film having a surface protective film and a separator, in which the separator can be smoothly peeled off from the surface of the adhesive layer.

The reinforcing laminate film of the present invention is
A reinforcing laminate film having a separator, a pressure-sensitive adhesive layer (1), a reinforcing substrate, and a surface protective film in this order,
the separator and the pressure-sensitive adhesive layer (1) are directly laminated together,
The reinforcing base material and the surface protective film are directly laminated together,
The separator includes a substrate layer (1),
The surface protective film comprises a substrate layer (2) and a pressure-sensitive adhesive layer (2), and the pressure-sensitive adhesive layer (2) is directly laminated onto the reinforcing substrate;
The initial peel strength P of the reinforcing substrate in the reinforcing laminate film is greater than the initial peel strength Q of the separator in the reinforcing laminate film.

In one embodiment, the reinforcing substrate is a plastic film.

In one embodiment, the thickness of the reinforcing substrate is 25 μm to 500 μm.

In one embodiment, the thickness of the separator is 1 μm to 100 μm.

In one embodiment, the thickness of the surface protection film is 5 μm to 500 μm.

In one embodiment, the adhesive layer (1) is composed of at least one adhesive selected from the group consisting of acrylic adhesives, urethane adhesives, rubber adhesives, and silicone adhesives.

In one embodiment, the acrylic adhesive is formed from an acrylic adhesive composition, and the acrylic adhesive composition comprises: (a) an acrylic polymer formed by polymerization from composition (A) containing: (a) an alkyl (meth)acrylate ester in which the alkyl group in the alkyl ester moiety has 4 to 12 carbon atoms; (b) at least one selected from the group consisting of an OH-group-containing (meth)acrylate ester and (meth)acrylic acid; and (c) at least one selected from the group consisting of a polyfunctional isocyanate-based crosslinking agent and an epoxy-based crosslinking agent.

In one embodiment, the adhesive layer (2) is composed of at least one adhesive selected from the group consisting of acrylic adhesives, urethane adhesives, rubber adhesives, and silicone adhesives.

In one embodiment, the adhesive layer (2) is composed of at least one adhesive selected from the group consisting of acrylic adhesives and urethane adhesives.

In one embodiment, the acrylic adhesive is formed from an acrylic adhesive composition for adhesive layer (2), and the acrylic adhesive composition for adhesive layer (2) comprises: (p component) an acrylic polymer formed by polymerization from composition (B) containing at least one selected from the group consisting of a (meth)acrylic acid alkyl ester in which the alkyl group in the alkyl ester moiety has 4 to 12 carbon atoms; (q component) a (meth)acrylic acid ester having an OH group; and (meth)acrylic acid; and (r component) at least one selected from the group consisting of a polyfunctional isocyanate-based crosslinking agent and an epoxy-based crosslinking agent.

In one embodiment, the (p component) is 2-ethylhexyl acrylate, the (q component) is 2-hydroxyethyl acrylate, and the (r component) is a polyfunctional isocyanate-based crosslinking agent.

In one embodiment, the above (r component) is a trimethylolpropane/tolylene diisocyanate adduct.

In one embodiment, the adhesive layer (1) exposed by peeling off the separator at a temperature of 23°C, a humidity of 50% RH, a peel angle of 150°C, and a peel speed of 10 m/min has an initial adhesive strength to a glass plate of 1.0 N/25 mm or more at a temperature of 23°C, a humidity of 50% RH, a peel angle of 180°C, and a peel speed of 300 mm/min.

According to the present invention, it is possible to provide a reinforcing laminate film having a surface protective film and a separator, in which the separator can be smoothly peeled off from the surface of the adhesive layer.

1 is a schematic cross-sectional view of one embodiment of a reinforcing laminate film of the present invention.

When the term "weight" appears in this specification, it may be read as "mass," which is the commonly used SI unit of weight.

In this specification, the term "(meth)acrylic" means "acrylic and/or methacrylic", the term "(meth)acrylate" means "acrylate and/or methacrylate", the term "(meth)allyl" means "allyl and/or methallyl", and the term "(meth)acrolein" means "acrolein and/or methacrolein".

<<Reinforcing laminated film>>
The reinforcing laminate film of the present invention has a separator, a pressure-sensitive adhesive layer (1), a reinforcing substrate, and a surface protective film in this order. The reinforcing laminate film of the present invention may have any appropriate other layer as long as it has a separator, a pressure-sensitive adhesive layer (1), a reinforcing substrate, and a surface protective film in this order, as long as the effect of the present invention is not impaired.

In the reinforcing laminate film of the present invention, the separator and the adhesive layer (1) are directly laminated together.

In the reinforcing laminate film of the present invention, the reinforcing substrate and the surface protective film are directly laminated together.

In the reinforcing laminate film of the present invention, the separator includes a substrate layer (1).

In the reinforcing laminate film of the present invention, the surface protection film comprises a substrate layer (2) and an adhesive layer (2), and the adhesive layer (2) is laminated directly onto the reinforcing substrate.

The overall thickness of the reinforcing laminate film of the present invention is preferably 80 μm to 600 μm, more preferably 90 μm to 500 μm, even more preferably 95 μm to 400 μm, and particularly preferably 100 μm to 300 μm, in order to better express the effects of the present invention.

Figure 1 is a schematic cross-sectional view of one embodiment of the reinforcing laminate film of the present invention. In Figure 1, the reinforcing laminate film 1000 of the present invention has a separator 100, a pressure-sensitive adhesive layer (1) 200, a reinforcing substrate 300, and a surface protective film 400 in this order, and the surface protective film 400 includes a substrate layer (2) 410 and a pressure-sensitive adhesive layer (2) 420.

Taking Figure 1 as an example, one embodiment of the method of using the reinforcing laminate film 1000 of the present invention is to first peel off the separator 100 to expose the adhesive layer (1) 200, and then attach it to the exposed surface side of an optical component or electronic component to reinforce the optical component or electronic component. The surface protection film 400 is attached to the product in this state to prevent the surface of the reinforcing base material 300 from being scratched during processing, assembly, inspection, transportation, etc., and is peeled off from the reinforcing base material 300 when surface protection is no longer necessary.

In the reinforcing laminate film of the present invention, the separator can be smoothly peeled off from the surface of the adhesive layer by appropriately designing the difference in the magnitude of the initial peel force when attempting to peel off the two components that can be peeled off during use, i.e., the separator and the surface protective film. Without such design, there is a risk that peeling will occur singly or in combination at unintended locations, such as peeling at the interface between the surface protective film and the reinforcing substrate, when the separator is peeled off from the surface of the adhesive layer.

As the above design, in the reinforcing laminate film of the present invention, the trigger peel force P of the reinforcing substrate in the reinforcing laminate film is greater than the trigger peel force Q of the separator in the reinforcing laminate film. Details of the measurement method of the trigger peel force P and the trigger peel force Q will be described later.

The trigger peel force P is preferably 0.1 N/25 mm to 20 N/25 mm, more preferably 0.5 N/25 mm to 15 N/25 mm, even more preferably 1.0 N/25 mm to 10 N/25 mm, and particularly preferably 1.0 N/25 mm to 8 N/25 mm, in order to better express the effects of the present invention.

The trigger peel force Q is preferably 0.1 N/25 mm to 10 N/25 mm, more preferably 0.3 N/25 mm to 7 N/25 mm, even more preferably 0.5 N/25 mm to 5 N/25 mm, and particularly preferably 0.7 N/25 mm to 3 N/25 mm, in order to better express the effects of the present invention.

The difference between the trigger peel force P and the trigger peel force Q (P-Q) is preferably 0.001 N/25 mm to 10 N/25 mm, more preferably 0.005 N/25 mm to 8 N/25 mm, even more preferably 0.01 N/25 mm to 6 N/25 mm, and particularly preferably 0.05 N/25 mm to 5 N/25 mm, in order to better express the effects of the present invention.

The reinforcing laminate film of the present invention can be produced by any suitable method as long as the effects of the present invention are not impaired. For example, it can be produced by forming a pressure-sensitive adhesive layer (1) on a reinforcing substrate, laminating a separator on the formed pressure-sensitive adhesive layer (1), and laminating a surface protective film on the opposite side of the pressure-sensitive adhesive layer (1) of the reinforcing substrate.

<Separator>
The separator is laminated directly on the pressure-sensitive adhesive layer 1. When using the reinforcing laminate film of the present invention, the separator is preferably first peeled off to expose the pressure-sensitive adhesive layer 1, and the reinforcing laminate film is then attached to the exposed surface side of an optical member or an electronic member to reinforce the optical member or the electronic member.

The thickness of the separator is preferably 1 μm to 100 μm, more preferably 5 μm to 90 μm, even more preferably 10 μm to 80 μm, and particularly preferably 20 μm to 75 μm, in order to better express the effects of the present invention.

The separator preferably includes a substrate layer (1). In addition to the substrate layer (1), the separator may include any other appropriate layers depending on the purpose, as long as the effects of the present invention are not impaired.

<Base layer (1)>
As the substrate layer (1), a substrate layer formed from any appropriate material can be used as long as the effects of the present invention are not impaired. Examples of such materials include plastic films, nonwoven fabrics, paper, metal foils, woven fabrics, rubber sheets, foam sheets, and laminates thereof (particularly laminates containing plastic films).

Examples of plastic films include plastic films made of polyester-based resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); plastic films made of olefin-based resins containing α-olefins as monomer components, such as polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer (EVA); plastic films made of polyvinyl chloride (PVC); plastic films made of vinyl acetate-based resins; plastic films made of polycarbonate (PC); and plastic films made of polyphenylene sulfide (PPS). plastic films made of amide-based resins such as polyamide (nylon) and wholly aromatic polyamide (aramid); plastic films made of polyimide-based resins; plastic films made of polyether ether ketone (PEEK); plastic films made of olefin-based resins such as polyethylene (PE) and polypropylene (PP); plastic films made of fluorine-based resins such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer; and the like.

Examples of nonwoven fabrics include nonwoven fabrics made from heat-resistant natural fibers, such as nonwoven fabrics containing Manila hemp; synthetic resin nonwoven fabrics, such as polypropylene resin nonwoven fabrics, polyethylene resin nonwoven fabrics, and ester resin nonwoven fabrics; and the like.

The substrate layer (1) may consist of only one layer or two or more layers.

The thickness of the base layer (1) is preferably 4 μm to 500 μm, more preferably 10 μm to 400 μm, even more preferably 15 μm to 350 μm, and particularly preferably 20 μm to 300 μm, in order to better exhibit the effects of the present invention.

The substrate layer (1) may be subjected to a surface treatment. Examples of the surface treatment include corona treatment, plasma treatment, chromate treatment, ozone exposure, flame exposure, high-voltage shock exposure, ionizing radiation treatment, and coating with a primer.

The substrate layer (1) may contain any other suitable additives as long as they do not impair the effects of the present invention.

<Release Layer>
The separator may have a release layer to improve peelability from the pressure-sensitive adhesive layer (1). When the separator has a release layer, the release layer side of the separator is directly laminated on the pressure-sensitive adhesive layer (1).

Any suitable forming material may be used for the release layer as long as it does not impair the effects of the present invention. Examples of such forming materials include silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, and fatty acid amide-based release agents. Among these, silicone-based release agents are preferred. The release layer can be formed as a coating layer.

The thickness of the release layer may be any appropriate thickness depending on the purpose, as long as it does not impair the effects of the present invention. Such a thickness is preferably 10 nm to 2000 nm, more preferably 10 nm to 1500 nm, even more preferably 10 nm to 1000 nm, and particularly preferably 10 nm to 500 nm.

The release layer may consist of only one layer or two or more layers.

Examples of the silicone-based release layer include addition reaction type silicone resins. Specific examples of the addition reaction type silicone resins include KS-774, KS-775, KS-778, KS-779H, KS-847H, and KS-847T manufactured by Shin-Etsu Chemical Co., Ltd.; TPR-6700, TPR-6710, and TPR-6721 manufactured by Toshiba Silicone; and SD7220 and SD7226 manufactured by Toray Dow Corning Co., Ltd. The coating amount (after drying) of the silicone-based release layer is preferably 0.01 g/m ² to 2 g/m ² , more preferably 0.01 g/m ² to 1 g/m ² , and even more preferably 0.01 g/m ² to 0.5 g/m ² .

The release layer can be formed, for example, by applying the above-mentioned forming material onto any suitable layer by a conventionally known application method such as reverse gravure coating, bar coating, or die coating, and then curing the applied material by heat treatment, usually at about 120 to 200°C. If necessary, heat treatment and irradiation with active energy rays such as ultraviolet light may be used in combination.

<Adhesive layer (1)>
Any appropriate pressure-sensitive adhesive layer can be adopted as the pressure-sensitive adhesive layer (1) as long as the effects of the present invention are not impaired. The pressure-sensitive adhesive layer (1) may be a single layer or may be two or more layers.

The thickness of the adhesive layer (1) is preferably 0.5 μm to 150 μm, more preferably 1 μm to 100 μm, even more preferably 3 μm to 80 μm, particularly preferably 5 μm to 50 μm, and most preferably 10 μm to 30 μm, in order to better exhibit the effects of the present invention.

When using the reinforcing laminate film of the present invention, the pressure-sensitive adhesive layer (1) is preferably peeled off to expose the pressure-sensitive adhesive layer (1) and then attached to the exposed surface side of an optical component or electronic component to reinforce the optical component or electronic component. In other words, it is not assumed that the pressure-sensitive adhesive layer (1) will be peeled off like a surface protection film after being attached to the exposed surface side of an optical component or electronic component. For this reason, the pressure-sensitive adhesive layer (1) is preferably designed to have an adhesive strength of a certain level or more. Specifically, the pressure-sensitive adhesive layer (1) exposed by peeling off the separator at a temperature of 23° C., a humidity of 50% RH, a peel angle of 150° C., and a peel speed of 10 m/min has an initial adhesive strength to a glass plate at a temperature of 23° C., a humidity of 50% RH, a peel angle of 180° C., and a peel speed of 300 mm/min of preferably 1.0 N/25 mm or more, more preferably 2.0 N/25 mm or more, even more preferably 3.0 N/25 mm or more, particularly preferably 4.0 N/25 mm or more, and most preferably 4.5 N/25 mm or more. In reality, the upper limit of the initial adhesive strength is preferably 5.0 N/25 mm or less.

The adhesive layer (1) is preferably composed of at least one type selected from the group consisting of acrylic adhesives, urethane adhesives, rubber adhesives, and silicone adhesives.

The adhesive layer (1) may be formed by any suitable method. For example, an adhesive composition (at least one selected from the group consisting of an acrylic adhesive composition, a urethane adhesive composition, a rubber adhesive composition, and a silicone adhesive composition) may be applied to any suitable substrate, heated and dried as necessary, and cured as necessary to form an adhesive layer on the substrate. Examples of such application methods include gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, air knife coaters, spray coaters, comma coaters, direct coaters, and roll brush coaters.

<Acrylic adhesive>
The acrylic pressure-sensitive adhesive is formed from an acrylic pressure-sensitive adhesive composition.

The acrylic adhesive composition preferably contains an acrylic polymer and a crosslinking agent, which can further enhance the effects of the present invention.

The acrylic polymer is what can be called a base polymer in the field of acrylic adhesives. The acrylic polymer may be of only one type or of two or more types.

The content of the acrylic polymer in the acrylic adhesive composition, calculated as solid content, is preferably 50% by weight to 100% by weight, more preferably 60% by weight to 100% by weight, even more preferably 70% by weight to 100% by weight, particularly preferably 80% by weight to 100% by weight, and most preferably 90% by weight to 100% by weight.

Any suitable acrylic polymer may be used as the acrylic polymer as long as it does not impair the effects of the present invention.

The weight average molecular weight of the acrylic polymer is preferably 100,000 to 3,000,000, more preferably 150,000 to 2,000,000, even more preferably 200,000 to 1,500,000, and particularly preferably 250,000 to 1,000,000, in order to better express the effects of the present invention.

The acrylic polymer is preferably an acrylic polymer formed by polymerization from a composition (A) containing (component a) an alkyl (meth)acrylate ester having an alkyl group of 4 to 12 carbon atoms in the alkyl ester moiety, and (component b) at least one selected from the group consisting of an OH-group-containing (meth)acrylate ester and (meth)acrylic acid. Each of (component a) and (component b) may independently be one type or two or more types.

Examples of (meth)acrylic acid alkyl esters (component a) in which the alkyl group of the alkyl ester portion has 4 to 12 carbon atoms include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. Among these, in terms of being able to more effectively exert the effects of the present invention, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred, and n-butyl acrylate and 2-ethylhexyl acrylate are more preferred.

At least one type (component b) selected from the group consisting of (meth)acrylic acid esters having an OH group and (meth)acrylic acid, includes, for example, (meth)acrylic acid esters having an OH group, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate, and (meth)acrylic acid. Among these, in terms of being able to more effectively exert the effects of the present invention, 2-hydroxyethyl (meth)acrylate and (meth)acrylic acid are preferred, and 2-hydroxyethyl acrylate and acrylic acid are more preferred.

The composition (A) may contain a copolymerizable monomer other than the components (a) and (b). The copolymerizable monomer may be one type only, or two or more types. Examples of such copolymerizable monomers include carboxyl group-containing monomers (excluding (meth)acrylic acid) such as itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and acid anhydrides thereof (e.g., acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride); (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-butyl ... Amide group-containing monomers such as acrylamide; amino group-containing monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinyl-2-pyrrolidone, (meth)acryloylmorpholine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, and N-vinyl isopropyl alcohol. heterocyclic ring-containing vinyl monomers such as midazole, vinylpyridine, vinylpyrimidine, and vinyloxazole; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide; isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate; (meth)acrylic acid esters having alicyclic hydrocarbon groups such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid esters having aromatic hydrocarbon groups such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyl toluene; olefins and dienes such as ethylene, butadiene, isoprene, and isobutylene; vinyl ethers such as vinyl alkyl ethers; and vinyl chloride.

As the copolymerizable monomer, a polyfunctional monomer may also be used. A polyfunctional monomer refers to a monomer having two or more ethylenically unsaturated groups in one molecule. As the ethylenically unsaturated group, any appropriate ethylenically unsaturated group may be used as long as it does not impair the effects of the present invention. Examples of such ethylenically unsaturated groups include radically polymerizable functional groups such as vinyl groups, propenyl groups, isopropenyl groups, vinyl ether groups (vinyloxy groups), and allyl ether groups (allyloxy groups). Examples of the polyfunctional monomer include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, etc. Such polyfunctional monomers may be used alone or in combination of two or more kinds.

As the copolymerizable monomer, (meth)acrylic acid alkoxyalkyl esters may also be used. Examples of (meth)acrylic acid alkoxyalkyl esters include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate. The (meth)acrylic acid alkoxyalkyl esters may be of one type or two or more types.

The content of the (meth)acrylic acid alkyl ester (component a) in which the alkyl group in the alkyl ester portion has 4 to 12 carbon atoms is preferably 50% by weight or more, more preferably 60% by weight to 100% by weight, even more preferably 70% by weight to 100% by weight, and particularly preferably 80% by weight to 100% by weight, relative to the total amount (100% by weight) of the monomer components constituting the acrylic polymer, in order to better exert the effects of the present invention.

The content of at least one type (component b) selected from the group consisting of (meth)acrylic acid esters having an OH group and (meth)acrylic acid is preferably 0.1% by weight or more, more preferably 1.0% by weight to 50% by weight, even more preferably 1.5% by weight to 40% by weight, and particularly preferably 2.0% by weight to 30% by weight, relative to the total amount (100% by weight) of the monomer components constituting the acrylic polymer, in order to further exert the effects of the present invention.

Composition (A) may contain any appropriate other components as long as the effects of the present invention are not impaired. Examples of such other components include a polymerization initiator, a chain transfer agent, and a solvent. The content of these other components may be any appropriate content as long as the effects of the present invention are not impaired.

Depending on the type of polymerization reaction, a thermal polymerization initiator or a photopolymerization initiator (photoinitiator) may be used as the polymerization initiator. There may be only one type of polymerization initiator or two or more types.

A thermal polymerization initiator may be preferably used when obtaining an acrylic polymer by solution polymerization. Examples of such thermal polymerization initiators include azo-based polymerization initiators, peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), and redox-based polymerization initiators. Among these thermal polymerization initiators, the azo-based initiators disclosed in JP-A-2002-69411 are particularly preferred. Such azo-based polymerization initiators are preferred in that decomposition products of the polymerization initiator are unlikely to remain in the acrylic polymer as a portion that causes heat-generated gas (outgassing). Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile (hereinafter sometimes referred to as AIBN), 2,2'-azobis-2-methylbutyronitrile (hereinafter sometimes referred to as AMBN), 2,2'-azobis(2-methylpropionate)dimethyl, 4,4'-azobis-4-cyanovaleric acid, etc. The amount of the azo polymerization initiator used is preferably 0.01 to 5.0 parts by weight, more preferably 0.05 to 4.0 parts by weight, even more preferably 0.1 to 3.0 parts by weight, particularly preferably 0.15 to 3.0 parts by weight, and most preferably 0.20 to 2.0 parts by weight, relative to the total amount (100 parts by weight) of the monomer components constituting the acrylic polymer.

The photopolymerization initiator may be preferably used when obtaining an acrylic polymer by active energy ray polymerization. Examples of the photopolymerization initiator include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators.

Examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole methyl ether. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. Examples of benzoin-based photopolymerization initiators include benzoin. Examples of benzyl-based photopolymerization initiators include benzyl. Examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone. Examples of ketal-based photopolymerization initiators include benzyl dimethyl ketal. Examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

The amount of photopolymerization initiator used is preferably 0.01 to 3.0 parts by weight, more preferably 0.015 to 2.0 parts by weight, even more preferably 0.02 to 1.5 parts by weight, particularly preferably 0.025 to 1.0 parts by weight, and most preferably 0.03 to 0.50 parts by weight, relative to the total amount (100 parts by weight) of the monomer components constituting the acrylic polymer.

The acrylic adhesive composition may contain a crosslinking agent. By using a crosslinking agent, the cohesive strength of the acrylic adhesive can be improved, and the effects of the present invention can be more effectively achieved. The crosslinking agent may be one type or two or more types.

Examples of crosslinking agents include polyfunctional isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Among these, at least one type (component c) selected from the group consisting of polyfunctional isocyanate-based crosslinking agents and epoxy-based crosslinking agents is preferred in terms of being able to further exert the effects of the present invention.

Examples of polyfunctional isocyanate crosslinking agents include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Examples of polyfunctional isocyanate crosslinking agents include commercially available products such as trimethylolpropane/tolylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate HL"), product name "Coronate HX" (Nippon Polyurethane Industry Co., Ltd.), and trimethylolpropane/xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., product name "Takenate 110N").

Examples of epoxy crosslinking agents (multifunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, and ethylene glycol diglycidyl ether. Examples of the epoxy crosslinking agent include diglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. Examples of the epoxy crosslinking agent include commercially available products such as "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.).

The content of the crosslinking agent in the acrylic pressure-sensitive adhesive composition may be any appropriate content within the range that does not impair the effects of the present invention. For example, such a content is preferably 0.1 to 5.0 parts by weight, more preferably 0.2 to 4.5 parts by weight, even more preferably 0.3 to 4.0 parts by weight, and particularly preferably 0.4 to 3.5 parts by weight, relative to the solid content (100 parts by weight) of the acrylic polymer, in terms of being able to further exhibit the effects of the present invention.

The acrylic adhesive composition may contain any other appropriate components as long as the effects of the present invention are not impaired. Examples of such other components include polymer components other than acrylic polymers, crosslinking accelerators, crosslinking catalysts, silane coupling agents, tackifier resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), anti-aging agents, inorganic fillers, organic fillers, metal powders, colorants (pigments, dyes, etc.), foil-like materials, UV absorbers, antioxidants, light stabilizers, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, conductive agents, stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, lubricants, solvents, catalysts, etc.

<Urethane-based adhesive>
The urethane-based pressure-sensitive adhesive is formed from a urethane-based pressure-sensitive adhesive composition.

The urethane-based adhesive composition preferably contains at least one selected from the group consisting of urethane prepolymers and polyols, and a crosslinking agent, in order to further exert the effects of the present invention.

At least one selected from the group consisting of urethane prepolymers and polyols can be called a base polymer in the field of urethane-based adhesives. The urethane prepolymer may be of only one type or of two or more types. The polyol may be of only one type or of two or more types.

[Urethane prepolymer]
The urethane prepolymer is preferably a polyurethane polyol, and more preferably is obtained by reacting a polyester polyol (a1) or a polyether polyol (a2), either alone or in the form of a mixture of (a1) and (a2), with an organic polyisocyanate compound (a3) in the presence or absence of a catalyst.

Any suitable polyester polyol may be used as the polyester polyol (a1). Examples of such polyester polyols (a1) include polyester polyols obtained by reacting an acid component with a glycol component. Examples of the acid component include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, and trimellitic acid. Examples of the glycol component include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, and butylethylpentanediol. Examples of the polyol component include glycerin, trimethylolpropane, and pentaerythritol. Other examples of the polyester polyol (a1) include polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly(β-methyl-γ-valerolactone) and polyvalerolactone.

The molecular weight of polyester polyol (a1) can range from low to high. The molecular weight of polyester polyol (a1) is preferably 100 to 100,000 in terms of the effect of the present invention. If the number average molecular weight is less than 100, the reactivity may be high and gelation may occur easily. If the number average molecular weight exceeds 100,000, the reactivity may be low and the cohesive force of the polyurethane polyol itself may be reduced. The amount of polyester polyol (a1) used is preferably 0 mol% to 90 mol% of the polyol constituting the polyurethane polyol in terms of the effect of the present invention.

Any suitable polyether polyol may be used as the polyether polyol (a2). Examples of such polyether polyols (a2) include polyether polyols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran using low molecular weight polyols such as water, propylene glycol, ethylene glycol, glycerin, and trimethylolpropane as initiators. Specific examples of such polyether polyols (a2) include polyether polyols having two or more functional groups, such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol.

The molecular weight of the polyether polyol (a2) can range from low to high. The molecular weight of the polyether polyol (a2) is preferably 100 to 100,000 in terms of the effect of the present invention. If the number average molecular weight is less than 100, the reactivity may be high and the polyurethane polyol may be easily gelled. If the number average molecular weight exceeds 100,000, the reactivity may be low and the cohesive force of the polyurethane polyol itself may be small. The amount of polyether polyol (a2) used is preferably 0 mol% to 90 mol% of the polyol constituting the polyurethane polyol in terms of the effect of the present invention.

If necessary, polyether polyol (a2) can be used in combination by replacing a portion of it with glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, pentaerythritol, etc., or polyvalent amines such as ethylenediamine, N-aminoethylethanolamine, isophoronediamine, xylylenediamine, etc.

As the polyether polyol (a2), only bifunctional polyether polyols may be used, or a polyether polyol having a number average molecular weight of 100 to 100,000 and at least three or more hydroxyl groups in one molecule may be used in part or in whole. If a polyether polyol having a number average molecular weight of 100 to 100,000 and at least three or more hydroxyl groups in one molecule is used in part or in whole as the polyether polyol (a2), the effects of the present invention can be more effectively expressed, and the balance between adhesion and peelability can be improved. In such polyether polyols, if the number average molecular weight is less than 100, the reactivity may be high and the product may be easily gelled. In addition, in such polyether polyols, if the number average molecular weight exceeds 100,000, the reactivity may be low, and the cohesive force of the polyurethane polyol itself may be reduced. The number average molecular weight of such polyether polyols is more preferably 100 to 10,000 in that the effects of the present invention can be more effectively expressed.

As the organic polyisocyanate compound (a3), any suitable organic polyisocyanate compound can be used. Examples of such organic polyisocyanate compounds (a3) include aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates.

Examples of aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4"-triphenylmethane triisocyanate.

Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

Examples of aromatic aliphatic polyisocyanates include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.

Examples of alicyclic polyisocyanates include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, and 1,4-bis(isocyanatomethyl)cyclohexane.

As the organic polyisocyanate compound (a3), trimethylolpropane adducts, biuret products reacted with water, trimers having an isocyanurate ring, etc. can be used in combination.

Any suitable catalyst may be used to obtain the polyurethane polyol. Examples of such catalysts include tertiary amine compounds and organometallic compounds.

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

Examples of organometallic compounds include tin-based compounds and non-tin-based compounds.

Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

Examples of non-tin-based compounds include titanium-based compounds such as dibutyltitanium dichloride, tetrabutyltitanium trichloride, and butoxytitanium trichloride; lead-based compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; iron-based compounds such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt-based compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc-based compounds such as zinc naphthenate and zinc 2-ethylhexanoate; and zirconium-based compounds such as zirconium naphthenate.

When using a catalyst to obtain polyurethane polyol, in a system in which two types of polyols, polyester polyol and polyether polyol, exist, problems such as gelation or clouding of the reaction solution are likely to occur in a system using a single catalyst due to the difference in reactivity between the two polyols. Therefore, by using two types of catalysts to obtain polyurethane polyol, it becomes easier to control the reaction rate and catalyst selectivity, and these problems can be solved. Examples of such combinations of two types of catalysts include tertiary amine/organic metal system, tin/non-tin system, and tin/tin system, and preferably tin/tin system, and more preferably a combination of dibutyltin dilaurate and tin 2-ethylhexanoate. The blending ratio of tin 2-ethylhexanoate/dibutyltin dilaurate is preferably less than 1, more preferably 0.2 to 0.6, by weight. If the blending ratio is 1 or more, gelation may occur easily due to the balance of the catalytic activity.

When a catalyst is used to obtain polyurethane polyol, the amount of catalyst used is preferably 0.01% by weight to 1.0% by weight based on the total amount of polyester polyol (a1), polyether polyol (a2), and organic polyisocyanate compound (a3).

When a catalyst is used to obtain polyurethane polyol, the reaction temperature is preferably less than 100°C, and more preferably 85°C to 95°C. If the temperature is above 100°C, it may become difficult to control the reaction rate and crosslinking structure, and it may become difficult to obtain a polyurethane polyol having the specified molecular weight.

When obtaining polyurethane polyol, it is not necessary to use a catalyst. In that case, the reaction temperature is preferably 100°C or higher, more preferably 110°C or higher. When obtaining polyurethane polyol without a catalyst, it is preferable to carry out the reaction for 3 hours or more.

Methods for obtaining polyurethane polyol include, for example, 1) a method in which polyester polyol, polyether polyol, catalyst, and organic polyisocyanate are all charged into a flask, and 2) a method in which polyester polyol, polyether polyol, and catalyst are charged into a flask and then organic polyisocyanate is added. As a method for obtaining polyurethane polyol, method 2) is preferred in terms of controlling the reaction.

Any suitable solvent may be used to obtain the polyurethane polyol. Examples of such solvents include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Of these solvents, toluene is preferred.

[Polyol]

Examples of preferred polyols include polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil polyols. More preferred polyols are polyether polyols.

Polyester polyols can be obtained, for example, by an esterification reaction between a polyol component and an acid component.

Examples of polyol components include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol. Examples of the acid component include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and acid anhydrides thereof.

Examples of polyether polyols include polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide using water, low molecular weight polyols (propylene glycol, ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc.), bisphenols (bisphenol A, etc.), and dihydroxybenzenes (catechol, resorcin, hydroquinone, etc.) as initiators. Specific examples include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Examples of polycaprolactone polyols include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and σ-valerolactone.

Examples of polycarbonate polyols include polycarbonate polyols obtained by polycondensation reaction of the above polyol components with phosgene; polycarbonate polyols obtained by transesterification condensation of the above polyol components with carbonate diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethyl butyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, and dibenzyl carbonate; copolymer polycarbonate polyols obtained by using two or more of the above polyol components in combination; polycarbonate polyols obtained by esterification reaction of the above various polycarbonate polyols with carboxyl group-containing compounds; Examples of the polycarbonate polyol include polycarbonate polyols obtained by subjecting a recarbonate polyol to an etherification reaction with a hydroxyl group-containing compound; polycarbonate polyols obtained by subjecting the above-mentioned various polycarbonate polyols to an ester exchange reaction with an ester compound; polycarbonate polyols obtained by subjecting the above-mentioned various polycarbonate polyols to an ester exchange reaction with a hydroxyl group-containing compound; polyester-based polycarbonate polyols obtained by subjecting the above-mentioned various polycarbonate polyols to a polycondensation reaction with a dicarboxylic acid compound; and copolymerized polyether-based polycarbonate polyols obtained by copolymerizing the above-mentioned various polycarbonate polyols with an alkylene oxide.

Examples of castor oil-based polyols include castor oil-based polyols obtained by reacting castor oil fatty acids with the above-mentioned polyol components. Specifically, examples of castor oil-based polyols include castor oil-based polyols obtained by reacting castor oil fatty acids with polypropylene glycol.

The number average molecular weight Mn of the polyol is preferably 300 to 100,000, more preferably 400 to 75,000, even more preferably 450 to 50,000, and particularly preferably 500 to 30,000, in order to better express the effects of the present invention.

The polyol preferably contains a polyol (A1) having three OH groups and a number average molecular weight Mn of 300 to 100,000, in order to further exert the effects of the present invention. The polyol (A1) may be one type or two or more types.

The content of polyol (A1) in the polyol is preferably 5% by weight or more, more preferably 25% by weight to 100% by weight, and even more preferably 50% by weight to 100% by weight, in order to better exhibit the effects of the present invention.

The number average molecular weight Mn of polyol (A1) is preferably 1,000 to 100,000, more preferably more than 1,000 and not more than 80,000, even more preferably 1,100 to 70,000, even more preferably 1,200 to 60,000, even more preferably 1,300 to 50,000, even more preferably 1,400 to 40,000, even more preferably 1,500 to 35,000, particularly preferably 1,700 to 32,000, and most preferably 2,000 to 30,000, in order to better express the effects of the present invention.

The polyol may contain a polyol (A2) having three or more OH groups and a number average molecular weight Mn of 20,000 or less. The polyol (A2) may be one type or two or more types. The number average molecular weight Mn of the polyol (A2) is preferably 100 to 20,000, more preferably 150 to 10,000, even more preferably 200 to 7,500, particularly preferably 300 to 6,000, and most preferably 300 to 5,000, in terms of being able to further express the effects of the present invention. As the polyol (A2), a polyol (triol) having three OH groups, a polyol (tetraol) having four OH groups, a polyol (pentaol) having five OH groups, and a polyol (hexaol) having six OH groups are preferably used in terms of being able to further express the effects of the present invention.

The total amount of polyol (A2) having four OH groups (tetraol), polyol (pentaol) having five OH groups, and polyol (hexaol) having six OH groups is preferably 70% by weight or less, more preferably 60% by weight or less, even more preferably 40% by weight or less, and particularly preferably 30% by weight or less, in terms of the content in the polyol, in order to better express the effects of the present invention.

The content of polyol (A2) in the polyol is preferably 95% by weight or less, and more preferably 0% by weight to 75% by weight, in order to better exhibit the effects of the present invention.

The content of polyol (A2) having 4 or more OH groups and a number average molecular weight Mn of 20,000 or less is preferably less than 70% by weight, more preferably 60% by weight or less, even more preferably 50% by weight or less, particularly preferably 40% by weight or less, and most preferably 30% by weight or less, relative to the total weight of the polyol, in order to better express the effects of the present invention.

[Crosslinking Agent]
The urethane-based pressure-sensitive adhesive composition preferably contains a crosslinking agent, in that the effects of the present invention can be more effectively exhibited.

The urethane prepolymer and polyol as base polymers can each be combined with a crosslinking agent to form a component of a urethane-based adhesive composition.

As a crosslinking agent to be combined with the urethane prepolymer and polyol as the base polymer, a multifunctional isocyanate-based crosslinking agent is preferred, as it can further exert the effects of the present invention.

As the polyfunctional isocyanate crosslinking agent, any suitable polyfunctional isocyanate crosslinking agent that can be used in the urethane reaction can be used. Examples of such polyfunctional isocyanate crosslinking agents include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Examples of polyfunctional isocyanate crosslinking agents include commercially available products such as trimethylolpropane/tolylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate HL"), product name "Coronate HX" (Nippon Polyurethane Industry Co., Ltd.), and trimethylolpropane/xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., product name "Takenate 110N").

[Urethane-based adhesive composition]
The urethane-based adhesive composition can contain any other suitable components within the scope that does not impair the effect of the present invention.Such other components include, for example, polymer components other than urethane prepolymer and polyol, crosslinking accelerator, crosslinking catalyst, silane coupling agent, tackifier resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), antiaging agent, inorganic filler, organic filler, metal powder, colorant (pigment, dye, etc.), foil-like material, deterioration inhibitor, chain transfer agent, plasticizer, softener, surfactant, antistatic agent, conductive agent, stabilizer, surface lubricant, leveling agent, corrosion inhibitor, heat resistance stabilizer, polymerization inhibitor, lubricant, solvent, catalyst, etc.

The urethane-based adhesive composition preferably contains an anti-deterioration agent, in order to further exert the effects of the present invention. The anti-deterioration agent may be of only one type, or may be of two or more types.

As anti-deterioration agents, preferred examples include antioxidants, ultraviolet absorbers, and light stabilizers, as they can further enhance the effects of the present invention.

Examples of antioxidants include radical chain inhibitors and peroxide decomposers.

Examples of radical chain inhibitors include phenol-based antioxidants and amine-based antioxidants.

Examples of phenolic antioxidants include monophenolic antioxidants, bisphenolic antioxidants, polymeric phenolic antioxidants, etc. Examples of monophenolic antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearin-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, etc. Examples of bisphenol-based antioxidants include 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, and the like. Examples of polymeric phenolic antioxidants include 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol.

Examples of peroxide decomposers include sulfur-based antioxidants and phosphorus-based antioxidants. Examples of sulfur-based antioxidants include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and distearyl 3,3'-thiodipropionate. Examples of phosphorus-based antioxidants include triphenyl phosphite, diphenyl isodecyl phosphite, and phenyl diisodecyl phosphite.

Examples of ultraviolet absorbers include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, anilide oxalate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

Benzophenone-based UV absorbers include, for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, and bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane.

Examples of benzotriazole-based ultraviolet absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, 2-[2'-hydroxy-3'-(3",4",5",6",tetrahydrophthalimidomethyl)-5'-methylphenyl]benzotriazole, 2,2'methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(2'-hydroxy-5'-methacryloxyphenyl)-2H-benzotriazole, and the like.

Examples of salicylic acid-based ultraviolet absorbers include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate.

Examples of cyanoacrylate-based ultraviolet absorbers include 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3'-diphenylacrylate, etc.

Examples of light stabilizers include hindered amine light stabilizers and ultraviolet stabilizers. Examples of hindered amine light stabilizers include bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, and methyl-1,2,2,6,6-pentamethyl-4-piperidylsebacate. Examples of ultraviolet stabilizers include nickel bis(octylphenyl)sulfide, [2,2'-thiobis(4-tert-octylphenolate)]-n-butylamine nickel, nickel complex-3,5-di-tert-butyl-4-hydroxybenzyl-phosphate monoethylate, benzoate type quencher, and nickel-dibutyldithiocarbamate.

[Urethane-based polymer formed from a urethane-based pressure-sensitive adhesive composition containing a urethane prepolymer and a polyfunctional isocyanate-based crosslinking agent]
The urethane prepolymer may be of only one type or may be of two or more types. The polyfunctional isocyanate crosslinking agent may be of only one type or may be of two or more types.

As a method for forming a urethane-based polymer from a urethane-based pressure-sensitive adhesive composition containing a urethane prepolymer and a polyfunctional isocyanate-based crosslinking agent, any appropriate manufacturing method may be used as long as it is a method for producing a urethane-based polymer using a so-called "urethane prepolymer" as a raw material.

The number average molecular weight Mn of the urethane prepolymer is preferably 3,000 to 1,000,000 in order to better express the effects of the present invention.

In order to further exert the effects of the present invention, the equivalent ratio of NCO groups to OH groups in the urethane prepolymer and polyfunctional isocyanate crosslinking agent is preferably 5.0 or less, more preferably 0.01 to 4.75, even more preferably 0.02 to 4.5, particularly preferably 0.03 to 4.25, and most preferably 0.05 to 4.0, in terms of NCO groups/OH groups.

The content of the polyfunctional isocyanate-based crosslinking agent is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 25 parts by weight, even more preferably 0.1 to 20 parts by weight, particularly preferably 0.5 to 17.5 parts by weight, and most preferably 1 to 15 parts by weight, per 100 parts by weight of the urethane prepolymer, in order to further exert the effects of the present invention.

[Urethane-based polymer formed from a urethane-based pressure-sensitive adhesive composition containing a polyol and a polyfunctional isocyanate-based crosslinking agent]
The polyol may be of only one type or of two or more types. The polyfunctional isocyanate-based crosslinking agent may be of only one type or of two or more types.

In order to further exert the effects of the present invention, the equivalent ratio of NCO groups to OH groups in the polyol and polyfunctional isocyanate crosslinking agent is preferably 5.0 or less, more preferably 0.1 to 3.0, even more preferably 0.2 to 2.5, particularly preferably 0.3 to 2.25, and most preferably 0.5 to 2.0, in terms of NCO groups/OH groups.

The content of the polyfunctional isocyanate-based crosslinking agent is preferably 1.0 to 30 parts by weight, more preferably 1.5 to 27 parts by weight, even more preferably 2.0 to 25 parts by weight, particularly preferably 2.3 to 23 parts by weight, and most preferably 2.5 to 20 parts by weight, per 100 parts by weight of polyol, in order to further exert the effects of the present invention.

The urethane polymer formed from the urethane adhesive composition containing a polyol and a polyfunctional isocyanate crosslinking agent is preferably formed by curing the urethane adhesive composition containing a polyol and a polyfunctional isocyanate crosslinking agent. As a method for forming a urethane polymer by curing the urethane adhesive composition containing a polyol and a polyfunctional isocyanate crosslinking agent, any appropriate method may be used as long as it does not impair the effects of the present invention, such as a urethane reaction method using bulk polymerization or solution polymerization.

A catalyst is preferably used to cure the urethane-based adhesive composition containing a polyol and a polyfunctional isocyanate-based crosslinking agent. Examples of such catalysts include organometallic compounds and tertiary amine compounds.

Examples of organometallic compounds include iron-based compounds, tin-based compounds, titanium-based compounds, zirconium-based compounds, lead-based compounds, cobalt-based compounds, zinc-based compounds, etc. Among these, iron-based compounds and tin-based compounds are preferred in terms of reaction rate and pot life of the adhesive layer.

Examples of iron-based compounds include iron acetylacetonate, iron 2-ethylhexanoate, and ferric nurseate.

Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, tributyltin methoxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, dioctyltin dilaurate, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

Examples of titanium compounds include dibutyltitanium dichloride, tetrabutyltitanium, and butoxytitanium trichloride.

Examples of zirconium compounds include zirconium naphthenate and zirconium acetylacetonate.

Examples of lead-based compounds include lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate.

Examples of cobalt-based compounds include cobalt 2-ethylhexanoate and cobalt benzoate.

Examples of zinc-based compounds include zinc naphthenate and zinc 2-ethylhexanoate.

Examples of tertiary amine compounds include triethylamine, triethylenediamine, and 1,8-diazabis(5,4,0)-undecene-7-ene.

The catalyst may be one type or two or more types. A catalyst may be used in combination with a crosslinking retarder or the like. The amount of catalyst is preferably 0.005 to 1.00 parts by weight, more preferably 0.01 to 0.75 parts by weight, even more preferably 0.01 to 0.50 parts by weight, and particularly preferably 0.01 to 0.20 parts by weight, relative to 100 parts by weight of polyol, in order to further exert the effects of the present invention.

<Rubber-based adhesive>
As the rubber-based adhesive, any appropriate rubber-based adhesive may be used, such as the known rubber-based adhesives described in JP-A-2015-074771, etc., as long as the effects of the present invention are not impaired. These may be one type only, or two or more types. The rubber-based adhesive may contain any appropriate component as long as the effects of the present invention are not impaired.

<Silicone-based adhesive>
As the silicone-based adhesive, any appropriate silicone-based adhesive may be used, for example, a known silicone-based adhesive described in JP-A-2014-047280, etc., as long as it does not impair the effects of the present invention. These may be one type only, or two or more types. The silicone-based adhesive may contain any appropriate component as long as it does not impair the effects of the present invention.

<Reinforcing base material>
The reinforcing substrate may be made of any suitable material, as long as it does not impair the effects of the present invention. Examples of such materials include plastic films, nonwoven fabrics, paper, metal foils, woven fabrics, rubber sheets, foam sheets, and laminates thereof (particularly laminates containing plastic films).

As the reinforcing substrate, a plastic film is preferred, as this can better express the effects of the present invention.

Examples of plastic films include plastic films made of polyester-based resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); plastic films made of olefin-based resins containing α-olefins as monomer components, such as polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer (EVA); plastic films made of polyvinyl chloride (PVC); plastic films made of vinyl acetate-based resins; plastic films made of polycarbonate (PC); and plastic films made of polyphenylene sulfide (PPS). plastic films made of amide-based resins such as polyamide (nylon) and wholly aromatic polyamide (aramid); plastic films made of polyimide-based resins; plastic films made of polyether ether ketone (PEEK); plastic films made of olefin-based resins such as polyethylene (PE) and polypropylene (PP); plastic films made of fluorine-based resins such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer; and the like.

As the thickness of the reinforcing substrate, any appropriate thickness may be adopted depending on the purpose, as long as it does not impair the effects of the present invention. Such a thickness is preferably 25 μm to 500 μm, more preferably 25 μm to 400 μm, even more preferably 25 μm to 300 μm, even more preferably 25 μm to 200 μm, even more preferably 25 μm to 150 μm, even more preferably 25 μm to 100 μm, and particularly preferably 25 μm to 75 μm, in terms of being able to further express the effects of the present invention. Note that the thinner the thickness of the reinforcing substrate, the more likely it is that interfacial peeling will occur at an unintended location (typically, the interface between the surface protective film and the reinforcing film) when attempting to peel the separator from the reinforcing laminate film. Specifically, even if the trigger peel force P of the reinforcing substrate is greater than the trigger peel force Q of the separator, if the thickness of the reinforcing substrate is too thin, there is a high risk of interfacial peeling occurring at an unintended location when attempting to peel the separator from the reinforcing laminate film, and this risk is particularly high when the trigger peel force P is small. When it is desired to design the reinforcing laminate film of the present invention by employing a thin reinforcing substrate, it is preferable to employ a surface protective film having an adhesive layer composed of a specific acrylic adhesive, as described below.

The reinforcing substrate may consist of only one layer or two or more layers.

The reinforcing substrate may be surface-treated. Examples of surface treatments include corona treatment, plasma treatment, chromate treatment, ozone exposure, flame exposure, high-voltage shock exposure, ionizing radiation treatment, and coating with a primer.

The reinforcing base material may contain any suitable additive depending on the purpose, as long as it does not impair the effects of the present invention.

<Surface protection film>
The surface protective film includes a substrate layer (2) and a pressure-sensitive adhesive layer (2), and the pressure-sensitive adhesive layer (2) is directly laminated on the reinforcing substrate. As long as the surface protective film includes the substrate layer (2) and the pressure-sensitive adhesive layer (2), it may include any other appropriate member within a range that does not impair the effects of the present invention. Typically, the surface protective film is composed of the substrate layer (2) and the pressure-sensitive adhesive layer (2).

The thickness of the surface protective film is preferably 5 μm to 500 μm, more preferably 10 μm to 400 μm, even more preferably 20 μm to 300 μm, particularly preferably 30 μm to 200 μm, and most preferably 40 μm to 100 μm, in order to better express the effects of the present invention.

The surface protection film can be produced by any suitable method. Examples of such a production method include
(1) A method of applying a solution or a hot melt of a material for forming the pressure-sensitive adhesive layer (2) onto a substrate layer (2);
(2) A method of transferring the adhesive layer (2) formed by applying a solution or a hot melt of a material for forming the adhesive layer (2) onto a separator onto a substrate layer (2);
(3) A method of forming and coating the pressure-sensitive adhesive layer (2) on the base material layer (2) by extrusion;
(4) A method of extruding a substrate layer (2) and a pressure-sensitive adhesive layer (2) in a two-layer or multi-layer structure,
(5) A method of laminating a single layer of a pressure-sensitive adhesive layer (2) on a substrate layer (2) or a method of laminating a double layer of the pressure-sensitive adhesive layer (2) together with a laminate layer;
(6) A method of laminating the pressure-sensitive adhesive layer (2) with a material for forming the base layer (2) such as a film or a laminate layer into a two-layer or multi-layer structure;
The above-mentioned manufacturing method can be used in accordance with any suitable manufacturing method.

Coating methods that can be used include, for example, the roll coater method, the comma coater method, the die coater method, the reverse coater method, the silk screen method, and the gravure coater method.

<Base layer (2)>
The base layer (2) may be a single layer or may be two or more layers. The base layer (2) may be a stretched layer.

The thickness of the base layer (2) is preferably 4 μm to 450 μm, more preferably 8 μm to 350 μm, even more preferably 12 μm to 250 μm, particularly preferably 16 μm to 150 μm, and most preferably 20 μm to 100 μm, in order to better exhibit the effects of the present invention.

For the surface of the base layer (2) on which the adhesive layer (2) is not applied, a release treatment may be performed by adding, for example, fatty acid amide, polyethyleneimine, long-chain alkyl additives, etc. to the base layer (2) in order to form a roll that is easy to unwind, or a coating layer made of any suitable release agent, such as a silicone-based, long-chain alkyl-based, or fluorine-based release agent, may be provided.

As the substrate layer (2), a substrate layer formed from any suitable material may be used as long as the effects of the present invention are not impaired. Examples of such materials include plastic films, nonwoven fabrics, paper, metal foils, woven fabrics, rubber sheets, foam sheets, and laminates thereof (particularly laminates containing plastic films).

The base layer (2) is preferably a plastic film, as this can better exert the effects of the present invention.

Examples of plastic films include plastic films made of polyester-based resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); plastic films made of olefin-based resins containing α-olefins as monomer components, such as polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer (EVA); plastic films made of polyvinyl chloride (PVC); plastic films made of vinyl acetate-based resins; plastic films made of polycarbonate (PC); and plastic films made of polyphenylene sulfide (PPS). plastic films made of amide-based resins such as polyamide (nylon) and wholly aromatic polyamide (aramid); plastic films made of polyimide-based resins; plastic films made of polyether ether ketone (PEEK); plastic films made of olefin-based resins such as polyethylene (PE) and polypropylene (PP); plastic films made of fluorine-based resins such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer; and the like.

The substrate layer (2) may contain any suitable additive depending on the purpose, as long as it does not impair the effects of the present invention.

<Pressure-sensitive adhesive layer (2)>
Any appropriate pressure-sensitive adhesive layer may be adopted as the pressure-sensitive adhesive layer (2) as long as the effects of the present invention are not impaired. The pressure-sensitive adhesive layer (2) may be a single layer or may be two or more layers.

The thickness of the adhesive layer (2) is preferably 0.5 μm to 150 μm, more preferably 1 μm to 100 μm, even more preferably 3 μm to 80 μm, particularly preferably 5 μm to 50 μm, and most preferably 10 μm to 30 μm, in order to better exhibit the effects of the present invention.

The adhesive layer (2) is preferably composed of at least one selected from the group consisting of an acrylic adhesive, a urethane adhesive, a rubber adhesive, and a silicone adhesive, and is more preferably composed of at least one selected from the group consisting of an acrylic adhesive and a urethane adhesive, and is even more preferably composed of an acrylic adhesive, in that the effects of the present invention can be more effectively exhibited. By making the adhesive layer (2) composed of at least one selected from the group consisting of an acrylic adhesive and a urethane adhesive, the trigger peel force P tends to be greater than the trigger peel force Q, and by making the adhesive layer (2) composed of an acrylic adhesive, the trigger peel force P tends to be greater than the trigger peel force Q (i.e., the value of (P-Q) may tend to be greater).

The adhesive layer (2) may be formed by any suitable method. For example, an adhesive composition (at least one selected from the group consisting of an acrylic adhesive composition, a urethane adhesive composition, a rubber adhesive composition, and a silicone adhesive composition) may be applied to any suitable substrate, heated and dried as necessary, and cured as necessary to form an adhesive layer on the substrate. Examples of such application methods include gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, air knife coaters, spray coaters, comma coaters, direct coaters, and roll brush coaters.

For detailed explanations of the acrylic adhesive, urethane adhesive, rubber adhesive, and silicone adhesive, the detailed explanations of the acrylic adhesive, urethane adhesive, rubber adhesive, and silicone adhesive in the explanation of the adhesive layer (1) above may be directly used. However, with regard to the acrylic adhesive that may constitute the adhesive layer (2), the following "acrylic adhesive for adhesive layer (2)" is preferred in that it can better exert the effects of the present invention.

The acrylic adhesive for the adhesive layer (2) is formed from an acrylic adhesive composition for the adhesive layer (2).

The acrylic adhesive composition for the adhesive layer (2) preferably contains an acrylic polymer and a crosslinking agent, in order to better exert the effects of the present invention.

The acrylic polymer is what can be called a base polymer in the field of acrylic adhesives. The acrylic polymer may be of only one type or of two or more types.

The content of the acrylic polymer in the acrylic adhesive composition for the adhesive layer (2), calculated as solid content, is preferably 50% by weight to 100% by weight, more preferably 60% by weight to 100% by weight, even more preferably 70% by weight to 100% by weight, particularly preferably 80% by weight to 100% by weight, and most preferably 90% by weight to 100% by weight.

Any suitable acrylic polymer may be used as the acrylic polymer as long as it does not impair the effects of the present invention.

The weight average molecular weight of the acrylic polymer is preferably 100,000 to 3,000,000, more preferably 150,000 to 2,000,000, even more preferably 200,000 to 1,500,000, and particularly preferably 250,000 to 1,000,000, in order to better express the effects of the present invention.

The acrylic polymer is preferably an acrylic polymer formed by polymerization from a composition (B) containing (p component) a (meth)acrylic acid alkyl ester in which the alkyl group in the alkyl ester portion has 4 to 12 carbon atoms, and (q component) at least one selected from the group consisting of a (meth)acrylic acid ester having an OH group and (meth)acrylic acid, in order to more effectively exert the effects of the present invention. (p component) and (q component) may each independently be only one type or two or more types.

Examples of (meth)acrylic acid alkyl esters (p components) in which the alkyl group of the alkyl ester portion has 4 to 12 carbon atoms include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. Among these, in terms of being able to more effectively exhibit the effects of the present invention, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred, more preferably n-butyl acrylate and 2-ethylhexyl acrylate, and even more preferably 2-ethylhexyl acrylate.

At least one type (q component) selected from the group consisting of (meth)acrylic acid esters having an OH group and (meth)acrylic acid, includes, for example, (meth)acrylic acid esters having an OH group, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate, and (meth)acrylic acid. Among these, in terms of being able to further exert the effects of the present invention, 2-hydroxyethyl (meth)acrylate and (meth)acrylic acid are preferred, 2-hydroxyethyl acrylate and acrylic acid are more preferred, and 2-hydroxyethyl acrylate is even more preferred.

Composition (B) may contain a copolymerizable monomer other than the components (p) and (q). The copolymerizable monomer may be one type only, or two or more types. Examples of such copolymerizable monomers include carboxyl group-containing monomers (excluding (meth)acrylic acid) such as itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and acid anhydrides thereof (e.g., acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride); (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-butyl ... Amide group-containing monomers such as acrylamide; amino group-containing monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinyl-2-pyrrolidone, (meth)acryloylmorpholine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, and N-vinyl isopropyl alcohol. heterocyclic ring-containing vinyl monomers such as midazole, vinylpyridine, vinylpyrimidine, and vinyloxazole; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide; isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate; (meth)acrylic acid esters having alicyclic hydrocarbon groups such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid esters having aromatic hydrocarbon groups such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyl toluene; olefins and dienes such as ethylene, butadiene, isoprene, and isobutylene; vinyl ethers such as vinyl alkyl ethers; and vinyl chloride.

As the copolymerizable monomer, a polyfunctional monomer may also be used. A polyfunctional monomer refers to a monomer having two or more ethylenically unsaturated groups in one molecule. As the ethylenically unsaturated group, any appropriate ethylenically unsaturated group may be used as long as it does not impair the effects of the present invention. Examples of such ethylenically unsaturated groups include radically polymerizable functional groups such as vinyl groups, propenyl groups, isopropenyl groups, vinyl ether groups (vinyloxy groups), and allyl ether groups (allyloxy groups). Examples of the polyfunctional monomer include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, etc. Such polyfunctional monomers may be used alone or in combination of two or more kinds.

As the copolymerizable monomer, (meth)acrylic acid alkoxyalkyl esters may also be used. Examples of (meth)acrylic acid alkoxyalkyl esters include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate. The (meth)acrylic acid alkoxyalkyl esters may be of one type or two or more types.

The content of the (meth)acrylic acid alkyl ester (p component) in which the alkyl group in the alkyl ester portion has 4 to 12 carbon atoms is preferably 50% by weight or more, more preferably 60% by weight to 100% by weight, even more preferably 70% by weight to 100% by weight, and particularly preferably 80% by weight to 100% by weight, relative to the total amount (100% by weight) of the monomer components constituting the acrylic polymer, in order to better exert the effects of the present invention.

The content of at least one type (q component) selected from the group consisting of (meth)acrylic acid esters having an OH group and (meth)acrylic acid is preferably 0.1% by weight or more, more preferably 1.0% by weight to 50% by weight, even more preferably 1.5% by weight to 40% by weight, even more preferably 2.0% by weight to 30% by weight, even more preferably 2.0% by weight to 20% by weight, particularly preferably 2.0% by weight to 10% by weight, and most preferably 2.0% by weight to 5% by weight, relative to the total amount (100% by weight) of the monomer components constituting the acrylic polymer, in order to further exert the effects of the present invention.

Composition (B) may contain any appropriate other components as long as the effects of the present invention are not impaired. Examples of such other components include a polymerization initiator, a chain transfer agent, and a solvent. The content of these other components may be any appropriate content as long as the effects of the present invention are not impaired. For these other components, the explanation in "Composition (A)" in the section "Adhesive Layer (1)" may be used as is.

The acrylic adhesive composition for the adhesive layer (2) may contain a crosslinking agent. By using a crosslinking agent, the cohesive strength of the acrylic adhesive can be improved, and the effects of the present invention can be further exerted. The crosslinking agent may be one type only, or two or more types.

Examples of crosslinking agents include polyfunctional isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Among these, at least one type (r component) selected from the group consisting of polyfunctional isocyanate-based crosslinking agents and epoxy-based crosslinking agents is preferred, and a polyfunctional isocyanate-based crosslinking agent is more preferred, in terms of being able to further exhibit the effects of the present invention.

Examples of polyfunctional isocyanate crosslinking agents include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Examples of polyfunctional isocyanate crosslinking agents include commercially available products such as trimethylolpropane/tolylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate HL"), product name "Coronate HX" (Nippon Polyurethane Industry Co., Ltd.), and trimethylolpropane/xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., product name "Takenate 110N"). Among these, in terms of being able to further exert the effects of the present invention, at least one selected from trimethylolpropane/tolylene diisocyanate adduct and trimethylolpropane/hexamethylene diisocyanate adduct is preferable, and trimethylolpropane/tolylene diisocyanate adduct is more preferable. By using at least one selected from a trimethylolpropane/tolylene diisocyanate adduct and a trimethylolpropane/hexamethylene diisocyanate adduct as the crosslinking agent, the trigger peel force P tends to be greater than the trigger peel force Q, and by using a trimethylolpropane/tolylene diisocyanate adduct as the crosslinking agent, the trigger peel force P tends to be greater than the trigger peel force Q (i.e., the value of (P-Q) may tend to be greater).

Examples of epoxy crosslinking agents (multifunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, and ethylene glycol diglycidyl ether. Examples of the epoxy crosslinking agent include diglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. Examples of the epoxy crosslinking agent include commercially available products such as "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.).

The content of the crosslinking agent in the acrylic adhesive composition for the adhesive layer (2) may be any appropriate content within the range that does not impair the effects of the present invention. For example, in order to further exhibit the effects of the present invention, the content is preferably 0.1 to 10.0 parts by weight, more preferably 0.2 to 8.0 parts by weight, even more preferably 0.3 to 6.0 parts by weight, particularly preferably 0.4 to 5.0 parts by weight, and most preferably 0.5 to 4.5 parts by weight relative to the solid content (100 parts by weight) of the acrylic polymer.

The acrylic adhesive composition for the adhesive layer (2) may contain any other appropriate components within the scope of not impairing the effects of the present invention. Examples of such other components include polymer components other than acrylic polymers, crosslinking accelerators, crosslinking catalysts, silane coupling agents, tackifier resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), anti-aging agents, inorganic fillers, organic fillers, metal powders, colorants (pigments, dyes, etc.), foil-like materials, ultraviolet absorbers, antioxidants, light stabilizers, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, conductive agents, stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, lubricants, solvents, catalysts, etc.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples in any way. The test and evaluation methods in the examples are as follows. Note that "parts" means "parts by weight" unless otherwise specified, and "%" means "% by weight" unless otherwise specified.

<Measurement of weight average molecular weight>
The weight average molecular weight was measured by gel permeation chromatography (GPC). Specifically, the measurement was performed using a GPC measuring device (trade name: HLC-8120GPC, manufactured by Tosoh Corporation) under the following conditions, and the weight average molecular weight was calculated based on the standard polystyrene equivalent value.
(Molecular weight measurement conditions)
Sample concentration: 0.2% by weight (tetrahydrofuran solution)
Sample injection volume: 10 μL
Column: Product name "TSKguard column Super HZ-H (1 column) + TSKgel Super HZM-H (2 columns)" (manufactured by Tosoh Corporation)
Reference column: Product name "TSKgel Super H-RC (1 piece)" (manufactured by Tosoh Corporation)
Eluent: tetrahydrofuran (THF)
・Flow rate: 0.6mL/min
Detector: differential refractometer (RI)
Column temperature (measurement temperature): 40°C

<Measurement of Trigger Peel Force P>
The reinforcing laminate film was cut to a size of 25 mm in width and 80 mm in length.
After leaving it in an environment of 23°C x 50% RH for 24 hours, the separator was peeled off to expose the pressure-sensitive adhesive layer (1). Next, a single-sided pressure-sensitive adhesive tape (manufactured by Nichiban Co., Ltd., product name "Cellotape (registered trademark)") cut to a size of 25 mm width and 50 mm length was pressure-bonded to the surface of the pressure-sensitive adhesive layer (1) of the reinforcing laminate film so that the end face was 1 mm protruding, and left for about 10 seconds.
Thereafter, the single-sided adhesive tape was peeled at a peel speed of 300 mm/min and a peel angle of 180 degrees using a universal tensile tester (manufactured by Minebea Co., Ltd., product name: TCM-1kNB), and the maximum stress applied at the initial stage of peeling was recorded as the initial peel force P (N/25 mm). The measurement was performed in an environment of 23°C x 50% RH.

<Measurement of Trigger Peel Force Q>
The reinforcing laminate film was cut to a size of 25 mm in width and 80 mm in length.
After leaving it in an environment of 23°C x 50% RH for 24 hours, a single-sided adhesive tape (manufactured by Nichiban Co., Ltd., product name "Cellotape (registered trademark)") cut to a size of 25 mm width and 50 mm length was pressed onto the surface of the separator of the reinforcing laminate film so that the end surface was 1 mm protruding, and left for approximately 10 seconds.
Thereafter, the single-sided adhesive tape was peeled at a peel speed of 300 mm/min and a peel angle of 180 degrees using a universal tensile tester (manufactured by Minebea Co., Ltd., product name: TCM-1kNB), and the maximum stress applied at the initial stage of peeling was recorded as the initial peel force Q (N/25 mm). The measurement was performed in an environment of 23°C x 50% RH.

<Measurement of initial adhesive strength of pressure-sensitive adhesive layer (1) to glass plate>
The reinforcing laminate film was cut into a width of 25 mm and a length of 150 mm to prepare a sample for evaluation.
In an environment of 23°C x 50% RH, the adhesive layer surface of the evaluation sample was attached to a glass plate (manufactured by Matsunami Glass Industrial Co., Ltd., product name: Microslide Glass S) with one reciprocating motion of a 2.0 kg roller. After curing for 30 minutes in an environment of 23°C x 50% RH, the sample was peeled off at a peel angle of 180° and a pulling speed of 300 mm/min using a universal tensile tester (manufactured by Minebea Co., Ltd., product name: TCM-1kNB) to measure the adhesive strength.

<Evaluation of Separator Peelability>
In a reinforcing laminate film having a surface protective film and a separator, an evaluation was performed to determine whether the separator could be peeled off smoothly from the surface of the adhesive layer without peeling at the interface between the surface protective film and the reinforcing film, etc., when peeling the separator from the surface of the adhesive layer.
◯: When the separator was peeled off from the surface of the pressure-sensitive adhesive layer (1), the separator could be peeled off smoothly from the surface of the pressure-sensitive adhesive layer (1) without peeling off at unintended locations such as the interface between the surface protective film and the reinforcing film.
×: When the separator was peeled off from the surface of the pressure-sensitive adhesive layer (1), it peeled off at an unintended location such as the interface between the surface protective film and the reinforcing film.

[Production Example 1]: Production of acrylic pressure-sensitive adhesive composition (1) Into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, 95 parts by weight of butyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 5 parts by weight of acrylic acid (manufactured by Toa Gosei Co., Ltd.), 0.2 parts by weight of 2,2'-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, and 156 parts by weight of ethyl acetate were charged, and nitrogen gas was introduced while gently stirring. The liquid temperature in the flask was kept at around 63°C and a polymerization reaction was carried out for 10 hours to prepare a solution (40% by weight) of an acrylic polymer having a weight average molecular weight of 700,000.
Next, 0.1 parts by weight, calculated as solid content, of TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a crosslinking agent was added to the obtained acrylic polymer solution relative to 100 parts by weight of the solid content thereof, and the solution was diluted with ethyl acetate so that the total solid content became 25% by weight, and stirred with a disperser to obtain an acrylic pressure-sensitive adhesive composition (1).

[Production Example 2]: Production of acrylic pressure-sensitive adhesive composition (2) Into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, 100 parts by weight of 2-ethylhexyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 4 parts by weight of 2-hydroxyethyl acrylate (manufactured by Toa Gosei Co., Ltd.), 0.2 parts by weight of 2,2'-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, and 156 parts by weight of ethyl acetate were charged, and nitrogen gas was introduced while gently stirring. The liquid temperature in the flask was kept at around 65°C and a polymerization reaction was carried out for 6 hours to prepare a solution (40% by weight) of an acrylic polymer having a weight average molecular weight of 550,000.
Next, to the obtained acrylic polymer solution, 4 parts by weight, calculated as solid content, of Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent and 0.03 parts by weight, calculated as solid content, of Envirizer OL-1 (manufactured by Tokyo Fine Chemical Co., Ltd.) as a crosslinking catalyst were added relative to 100 parts by weight of the solid content, and the mixture was diluted with ethyl acetate so that the total solid content became 25% by weight, and stirred with a disperser to obtain an acrylic pressure-sensitive adhesive composition (2).

[Production Example 3]: Production of acrylic pressure-sensitive adhesive composition (3) Into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, 100 parts by weight of 2-ethylhexyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 4 parts by weight of 2-hydroxyethyl acrylate (manufactured by Toagosei Co., Ltd.), 0.2 parts by weight of 2,2'-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, and 156 parts by weight of ethyl acetate were charged, and nitrogen gas was introduced while gently stirring. The liquid temperature in the flask was kept at around 65°C and a polymerization reaction was carried out for 6 hours to prepare a solution (40% by weight) of an acrylic polymer having a weight average molecular weight of 550,000.
Next, to the obtained acrylic polymer solution, 4 parts by weight, calculated as solid content, of Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent and 0.03 parts by weight, calculated as solid content, of Envirizer OL-1 (manufactured by Tokyo Fine Chemical Co., Ltd.) as a crosslinking catalyst were added relative to 100 parts by weight of the solid content, and the mixture was diluted with ethyl acetate so that the total solid content became 25% by weight, and stirred with a disperser to obtain an acrylic pressure-sensitive adhesive composition (3).

[Production Example 4]: Production of urethane-based adhesive composition (4) As a polyfunctional polyol, 100 parts by weight of Preminol S3011 (manufactured by Asahi Glass Co., Ltd., Mn = 10000) was used in terms of solid content, 18 parts by weight of Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.) was used in terms of solid content as a crosslinking agent, 0.04 parts by weight of Nursem Ferric (manufactured by Nippon Chemical Industry Co., Ltd.) was used in terms of solid content as a crosslinking catalyst, and 0.5 parts by weight of Irganox 1010 (manufactured by BASF) was used in terms of solid content as a deterioration inhibitor. The mixture was diluted with ethyl acetate so that the total solid content became 35% by weight, and the mixture was stirred with a disperser to obtain a urethane-based adhesive composition (4).

[Production Example 5]: Production of Surface Protection Film (A) The acrylic adhesive composition (2) obtained in Production Example 2 was applied to a polyester resin substrate "Lumirror S10" (thickness 38 μm, manufactured by Toray Industries, Inc.) using a fountain roll so that the thickness after drying was 23 μm, and the coating was cured and dried under conditions of a drying temperature of 130° C. and a drying time of 30 seconds. In this manner, an adhesive layer was produced on the substrate. Next, the silicone-treated surface of a 25 μm thick polyester resin substrate, one side of which had been silicone-treated, was bonded to the surface of the adhesive layer to obtain a surface protection film (A).

[Production Example 6]: Production of Surface Protection Film (B) The acrylic pressure-sensitive adhesive composition (3) obtained in Production Example 3 was applied to a polyester resin substrate "Lumirror S10" (thickness 38 μm, manufactured by Toray Industries, Inc.) using a fountain roll so that the thickness after drying was 21 μm, and the coating was cured and dried under conditions of a drying temperature of 130° C. and a drying time of 30 seconds. In this manner, a pressure-sensitive adhesive layer was produced on the substrate. Next, the silicone-treated surface of a 25 μm thick polyester resin substrate, one side of which had been silicone-treated, was bonded to the surface of the pressure-sensitive adhesive layer to obtain a surface protection film (B).

[Production Example 7]: Production of Surface Protection Film (C) The urethane-based adhesive composition (4) obtained in Production Example 4 was applied to a polyester resin substrate "Lumirror S10" (thickness 38 μm, manufactured by Toray Industries, Inc.) using a fountain roll so that the thickness after drying was 12 μm, and the coating was cured and dried under conditions of a drying temperature of 130° C. and a drying time of 30 seconds. In this way, an adhesive layer was produced on the substrate. Next, the silicone-treated surface of a 25 μm thick polyester resin substrate, one side of which was silicone-treated, was bonded to the surface of the adhesive layer to obtain a surface protection film (C).

Example 1
The acrylic pressure-sensitive adhesive composition (1) obtained in Production Example 1 was applied to a 125 μm-thick "Lumirror S10" (manufactured by Toray Industries, Inc.) reinforcing substrate made of polyester resin with a fountain roll so that the thickness after drying would be 25 μm, and the coating was cured and dried under conditions of a drying temperature of 130° C. and a drying time of 30 seconds. In this manner, a pressure-sensitive adhesive layer was formed on the reinforcing substrate.
Next, the silicone-treated surface of a separator made of polyester resin having a thickness of 75 μm and one side of which had been silicone-treated was attached to the surface of the pressure-sensitive adhesive layer, to obtain a reinforcing film with separator (1).
Next, the pressure-sensitive adhesive layer side of the surface protection film (A) obtained in Production Example 5 was attached to the reinforcing substrate surface of the separator-attached reinforcing film (1) to obtain a reinforcing laminate film (1).
The results are shown in Table 1.

[Examples 2 to 12, Comparative Examples 1 and 2]
Except for changing the thickness of the "Lumirror S10" (manufactured by Toray Industries, Inc.) as the reinforcing base material, the thickness of the pressure-sensitive adhesive layer formed on the reinforcing base material, and the thickness of the separator as shown in Table 1, the same procedure as in Example 1 was carried out to obtain reinforcing laminate films (2) to (12), (C1) to (C2).
The results are shown in Table 1.

Example 13
The acrylic pressure-sensitive adhesive composition (1) obtained in Production Example 1 was applied to a 125 μm-thick "Lumirror S10" (manufactured by Toray Industries, Inc.) reinforcing substrate made of polyester resin with a fountain roll so that the thickness after drying would be 25 μm, and the coating was cured and dried under conditions of a drying temperature of 130° C. and a drying time of 30 seconds. In this manner, a pressure-sensitive adhesive layer was formed on the reinforcing substrate.
Next, the silicone-treated surface of a separator made of polyester resin having a thickness of 75 μm and one side of which had been silicone-treated was attached to the surface of the pressure-sensitive adhesive layer, to obtain a reinforcing film with separator (1).
Next, the pressure-sensitive adhesive layer side of the surface protection film (B) obtained in Production Example 6 was attached to the reinforcing substrate surface of the separator-attached reinforcing film (1) to obtain a reinforcing laminate film (13).
The results are shown in Table 2.

[Examples 14 to 24, Comparative Examples 3 to 4]
Except for changing the thickness of the "Lumirror S10" (manufactured by Toray Industries, Inc.) as the reinforcing base material, the thickness of the pressure-sensitive adhesive layer formed on the reinforcing base material, and the thickness of the separator as shown in Table 2, the same procedure as in Example 13 was performed to obtain reinforcing laminate films (14) to (24), (C3) to (C4).
The results are shown in Table 2.

Example 25
The acrylic pressure-sensitive adhesive composition (1) obtained in Production Example 1 was applied to a 125 μm-thick "Lumirror S10" (manufactured by Toray Industries, Inc.) reinforcing substrate made of polyester resin with a fountain roll so that the thickness after drying would be 25 μm, and the coating was cured and dried under conditions of a drying temperature of 130° C. and a drying time of 30 seconds. In this manner, a pressure-sensitive adhesive layer was formed on the reinforcing substrate.
Next, the silicone-treated surface of a separator made of polyester resin having a thickness of 75 μm and one side of which had been silicone-treated was attached to the surface of the pressure-sensitive adhesive layer, to obtain a reinforcing film with separator (1).
Next, the pressure-sensitive adhesive layer side of the surface protection film (C) obtained in Production Example 7 was attached to the reinforcing substrate surface of the separator-attached reinforcing film (1) to obtain a reinforcing laminate film (25).
The results are shown in Table 3.

[Examples 26 to 36, Comparative Examples 5 to 6]
Except for changing the thickness of the "Lumirror S10" (manufactured by Toray Industries, Inc.) as the reinforcing base material, the thickness of the pressure-sensitive adhesive layer formed on the reinforcing base material, and the thickness of the separator as shown in Table 3, the same procedure as in Example 25 was performed to obtain reinforcing laminate films (26) to (36), (C5) to (C6).
The results are shown in Table 3.

From Tables 1 to 3, it can be seen that when the initial peel force P of the reinforcing substrate in the reinforcing laminate film is greater than the initial peel force Q of the separator, the separator can be smoothly peeled from the surface of the adhesive layer.

Furthermore, when comparing the surface protection films used, there is a tendency for the (P-Q) value to increase in the order of surface protection film (C), surface protection film (B), and surface protection film (A). This shows that the surface protection films used can peel the separator from the surface of the adhesive layer more smoothly in the order of surface protection film (C), surface protection film (B), and surface protection film (A). In other words, it can be seen that when a surface protection film having an adhesive layer composed of a specific acrylic adhesive is used as the surface protection film, the separator can be peeled from the surface of the adhesive layer more smoothly.

Furthermore, as mentioned above, the thinner the thickness of the reinforcing substrate, the more likely it is that interfacial peeling will occur at an unintended location (typically, at the interface between the surface protective film and the reinforcing film) when attempting to peel the separator from the reinforcing laminate film. Specifically, even if the trigger peel force P of the reinforcing substrate is greater than the trigger peel force Q of the separator, if the thickness of the reinforcing substrate is too thin, there is a high risk of interfacial peeling occurring at an unintended location when attempting to peel the separator from the reinforcing laminate film, and this risk is particularly high when the trigger peel force P is small. Therefore, when designing the reinforcing laminate film of the present invention by reducing the thickness of the reinforcing substrate, in order to reduce the above-mentioned risk as much as possible, it is preferable to adopt a surface protective film having an adhesive layer composed of a specific acrylic adhesive, as seen in the surface protective film (A) and surface protective film (B) as described above.

The reinforcing laminate film of the present invention can be suitably used to impart rigidity and impact resistance to optical components, electronic components, etc.

Reinforcement laminate film 1000
Separator 100
Pressure-sensitive adhesive layer (1) 200
Reinforcing base material 300
Surface protection film 400
Base layer (2) 410
Pressure sensitive adhesive layer (2) 420

Claims (7)

A reinforcing laminate film having a separator, a pressure-sensitive adhesive layer (1), a reinforcing substrate, and a surface protective film in this order,
the separator and the pressure-sensitive adhesive layer (1) are directly laminated together,
The reinforcing base material and the surface protective film are directly laminated together,
The separator includes a substrate layer (1),
The surface protective film comprises a substrate layer (2) and a pressure-sensitive adhesive layer (2), and the pressure-sensitive adhesive layer (2) is directly laminated onto the reinforcing substrate;
the pressure-sensitive adhesive layer (1) is composed of an acrylic pressure-sensitive adhesive, the acrylic pressure-sensitive adhesive being formed from an acrylic pressure-sensitive adhesive composition, the acrylic pressure-sensitive adhesive composition comprising an acrylic polymer formed by polymerization of a composition (A) containing a (meth)acrylic acid alkyl ester, the alkyl group of which has 4 to 12 carbon atoms, and (meth)acrylic acid, and at least one member selected from the group consisting of a polyfunctional isocyanate-based crosslinking agent and an epoxy-based crosslinking agent;
the pressure-sensitive adhesive layer (2) is made of an acrylic pressure-sensitive adhesive,
the reinforcing substrate is a plastic film,
The thickness of the reinforcing base material is 25 μm to 500 μm,
The initial peel strength P of the reinforcing substrate in the reinforcing laminate film is greater than the initial peel strength Q of the separator in the reinforcing laminate film.
Reinforcing laminated film. The reinforcing laminate film according to claim 1 , wherein the separator has a thickness of 1 μm to 100 μm. The reinforcing laminate film according to claim 1 or 2 , wherein the thickness of the surface protective film is 5 μm to 500 μm. The reinforcing laminate film according to any one of claims 1 to 3, wherein the acrylic adhesive constituting the pressure-sensitive adhesive layer (2) is formed from an acrylic adhesive composition for the pressure-sensitive adhesive layer (2), and the acrylic adhesive composition for the pressure-sensitive adhesive layer (2) comprises: (p component) an acrylic polymer formed by polymerization from a composition (B) containing at least one member selected from the group consisting of a (meth)acrylic acid alkyl ester in which the alkyl group in the alkyl ester moiety has 4 to 12 carbon atoms, (q component) a (meth)acrylic acid ester having an OH group, and (meth)acrylic acid; and (r component) at least one member selected from the group consisting of a polyfunctional isocyanate-based crosslinking agent and an epoxy-based crosslinking agent. The reinforcing laminate film according to claim 4 , wherein the (p component) is 2-ethylhexyl acrylate, the (q component) is 2-hydroxyethyl acrylate, and the (r component) is a polyfunctional isocyanate-based crosslinking agent. The reinforcing laminate film according to claim 5 , wherein the (r component) is a trimethylolpropane/tolylene diisocyanate adduct. 7. The reinforcing laminate film according to claim 1, wherein the pressure-sensitive adhesive layer (1) exposed by peeling off the separator at a temperature of 23° C., a humidity of 50% RH, a peel angle of 150° C., and a peel speed of 10 m/min has an initial adhesive strength to a glass plate of 1.0 N/25 mm or more at a temperature of 23° C., a humidity of 50% RH, a peel angle of 180° C., and a peel speed of 300 mm/ min .

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