Adhesive composition, and adhesive, adhesive sheet and laminate obtained using the same

Abstract

To provide an adhesive composition capable of obtaining an adhesive having good hot-melt coating properties and high heat resistance, when coated onto a polyvinyl chloride (PVC) substrate sheet to form an adhesive sheet, the adhesive layer of the adhesive sheet having excellent adhesiveness to the PVC substrate sheet, having high adhesive strength to a hard-to-adhere olefin adherend in addition to having excellent transparency of the adhesive sheet.SOLUTION: There is provided an adhesive composition comprising a (meth)acrylic resin (A) and a chlorinated polyolefin (B), wherein the (meth)acrylic resin (A) contains a structural unit derived from a monomer (a1) having an active energy ray-active site, the chlorine content of the chlorinated polyolefin (B) is more than 25 wt.% and less than 36 wt.% of the total chlorinated polyolefin (B).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive composition and uses thereof, and more particularly to a pressure-sensitive adhesive composition that can be used for pressure-sensitive adhesive sheets for hot melt coating, laminates, etc., and a pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and laminate made using the same. [Background technology]

[0002] Olefins such as polypropylene are used in a wide variety of applications, including automotive parts, building materials, electronic components, and office equipment, and are used in a wide range of environments. Despite their versatility, olefins are difficult to bond to due to their low surface energy.

[0003] In recent years, as an adhesive capable of adhering to poorly adhesive olefins, for example, Patent Document 1 describes a pressure-sensitive adhesive containing an acrylic polymer having a specific structure and a chlorinated polyolefin having a heat of fusion of 0 to 5 J / g and a chlorine content of 16 to 25 mass %. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-151485 [Patent Document 2] International Publication No. 2020 / 158475 Summary of the Invention [Problem to be solved by the invention]

[0005] Meanwhile, in recent years, with the diversification of consumer preferences, there has been a trend toward more aesthetically pleasing designs for automotive parts, building materials, electronic components, office automation equipment, and other components. Furthermore, adhesive sheets using transparent polyvinyl chloride as the substrate for automotive and other applications are often used. Therefore, the adhesive layer must have high adhesion to the polyvinyl chloride substrate, high adhesion to poorly adhesive substrates such as olefins, and transparency.

[0006] Furthermore, with the recent increase in environmental concerns, attention has been focused on pressure-sensitive adhesive compositions that do not use organic solvents. For example, Patent Document 2 describes an acrylic hot-melt pressure-sensitive adhesive composition that can be heated and melted without a solvent and applied to a substrate. Hot-melt pressure-sensitive adhesive compositions are characterized by the need for low melt viscosity and high heat resistance of the pressure-sensitive adhesive composition itself, since they can be heated and melted for application.

[0007] An object of the present invention is to provide a pressure-sensitive adhesive composition that has good hot-melt coatability and high heat resistance. Another object of the present invention is to provide a pressure-sensitive adhesive composition that, when coated on a polyvinyl chloride (PVC) substrate sheet to produce a pressure-sensitive adhesive sheet, provides a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet that exhibits excellent adhesion to the PVC substrate sheet, high adhesion to poorly adhesive olefin adherends, and excellent transparency. Another object of the present invention is to provide a pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive, and a laminate in which the pressure-sensitive adhesive layer is laminated with another substrate. [Means for solving the problem]

[0008] However, the present inventors have conducted extensive research in light of these circumstances and have found that a pressure-sensitive adhesive composition comprising a (meth)acrylic resin (A) containing a structural unit derived from a monomer (a1) having an active energy ray-active site and a chlorinated polyolefin (B) having a specific chlorine content has good hot-melt coatability and high heat resistance. Furthermore, they have found that when a pressure-sensitive adhesive sheet is prepared by coating the pressure-sensitive adhesive composition on a PVC substrate sheet, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet has excellent adhesion to the PVC substrate sheet, high adhesion to poorly adhesive olefin adherends, and also has excellent transparency, thereby completing the present invention.

[0009] That is, the present invention includes the following aspects. Aspect (1) of the present invention is a pressure-sensitive adhesive composition comprising a (meth)acrylic resin (A) and a chlorinated polyolefin (B), wherein the (meth)acrylic resin (A) contains a structural unit derived from a monomer (a1) having an active energy ray-active site, and the chlorine content of the chlorinated polyolefin (B) is more than 25% by weight and less than 36% by weight of the total weight of the chlorinated polyolefin (B).

[0010] Aspect (2) of the present invention is the pressure-sensitive adhesive composition of aspect (1), wherein the (meth)acrylic resin (A) has a structural unit derived from a polar group-containing ethylenically unsaturated monomer (a3).

[0011] In an aspect (3) of the present invention, in the pressure-sensitive adhesive composition of the aspect (1) or (2), the weight-average molecular weight of the chlorinated polyolefin (B) is 30,000 or less.

[0012] Aspect (4) of the present invention is the pressure-sensitive adhesive composition of any one of aspects (1) to (3), further comprising a tackifier (C).

[0013] In an aspect (5) of the present invention, in the pressure-sensitive adhesive composition of any one of aspects (1) to (4), the content of the thermal crosslinking agent (D) is less than 0.05 mass %.

[0014] Aspect (6) of the present invention is a pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition of any one of aspects (1) to (5).

[0015] A seventh aspect of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive of the sixth aspect.

[0016] An embodiment (8) of the present invention is a pressure-sensitive adhesive sheet having a polyvinyl chloride substrate sheet and a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive of embodiment (6).

[0017] Aspect (9) of the present invention is a laminate in which a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive of aspect (6) and a member are laminated together.

[0018] In this specification, the term "(meth)acrylic resin" refers to an acrylic resin or a methacrylic resin. Furthermore, "(meth)acrylic" refers to "acrylic" or "methacrylic," "(meth)acryloyl" refers to "acryloyl" or "methacryloyl," and "(meth)acrylate" refers to "acrylate" or "methacrylate." [Effects of the Invention]

[0019] The pressure-sensitive adhesive obtained using the pressure-sensitive adhesive composition of the present invention has good hot-melt coatability and high heat resistance. Furthermore, when a pressure-sensitive adhesive sheet is produced by coating the pressure-sensitive adhesive composition of the present invention on a PVC substrate sheet, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet has excellent adhesion to the PVC substrate sheet, high adhesive strength to poorly adhesive olefin adherends, and also has excellent transparency. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail below. In this specification, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more, Y or less," as well as "preferably larger than X" or "preferably smaller than Y." Furthermore, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also means that "it is preferably greater than X" or "it is preferably less than Y." In this specification, in multiple numerical ranges described in stages, each upper limit and each lower limit can be the upper limit or lower limit of any combined numerical range. For example, when the content of a certain component is described as "5 to 20 wt %, 10 to 15 wt %, "it can constitute each of the numerical ranges of "5 to 15 wt %, " "10 to 20 wt %, " "5 to 10 wt %, " and "15 to 20 wt %.

[0021] (1) Pressure-sensitive adhesive composition The pressure-sensitive adhesive composition of the present invention contains, as essential components, a (meth)acrylic resin (A) and a chlorinated polyolefin (B). First, these essential components will be described in order.

[0022] <(Meth)acrylic resin (A)> The (meth)acrylic resin (A) used in the present invention is a polymer obtained by polymerizing a copolymerization component (a), and the copolymerization component (a) contains a monomer (a1) having an active energy ray-active site, and further contains an alkyl (meth)acrylate (a2), a polar group-containing ethylenically unsaturated monomer (a3), and other copolymerizable monomers (a4), as necessary.

[0023] [Monomer (a1) having an active energy ray-active site] The active energy ray active site refers to a site that can form a crosslinked structure with another site in the same molecule or with another molecule when irradiated with active energy rays, and the monomer (a1) having an active energy ray active site is a monomer having such an active site in its molecule. The monomer (a1) having an active energy ray active site can be used alone or in combination of two or more. The monomer (a1) having an active energy ray active site is not limited, but for example, a (meth)acrylate having such an active site can be used.

[0024] Examples of active energy ray-active moieties include a benzophenone structure, a benzyl structure, an o-benzoylbenzoic acid ester structure, a thioxanthone structure, a 3-ketocoumarin structure, a 2-ethylanthraquinone structure, and a camphorquinone structure. Each of these structures can be excited by irradiation with active energy rays, and in the excited state, it can abstract hydrogen radicals from the (meth)acrylic resin (A) molecules. In this way, radicals are generated on the (meth)acrylic resin (A) molecules. Various reactions occur in the system, such as the formation of crosslinked structures by the generated radicals bonding with each other, the generation of peroxide radicals by reaction with oxygen molecules, the formation of crosslinked structures via the generated peroxide radicals, and the abstraction of other hydrogen radicals by the generated radicals, ultimately resulting in crosslinking of the (meth)acrylic resin (A).

[0025] Among the above structures, a benzophenone structure is preferred in consideration of transparency, reactivity, etc. Examples of (meth)acrylates having such a benzophenone structure include, but are not limited to, 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone, and mixtures thereof.

[0026] The content of the monomer (a1) having an active energy ray-active site is usually 0.05 to 5 wt %, preferably 0.1 to 3 wt %, and more preferably 0.2 to 2 wt %, based on the copolymerization component (a). If the content is too low, the curability upon irradiation with active energy rays tends to be low, while if the content is too high, the gel fraction increases too much, which tends to reduce the adhesive strength to olefins.

[0027] The content of each monomer relative to the entire copolymerization component (a) can be considered as the content of structural units derived from that monomer in all structural units constituting the (meth)acrylic resin (A) which is a copolymer.

[0028] [Alkyl (meth)acrylate (a2)] The alkyl(meth)acrylate (a2) does not have an active energy ray active site or a polar group, has 1 to 20 carbon atoms, preferably 2 to 12 carbon atoms, and has a linear or branched alkyl group. Examples of the alkyl(meth)acrylate (a2) include methyl(meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, iso-butyl(meth)acrylate, tert-butyl(meth)acrylate, n-propyl(meth)acrylate, n-hexyl(meth)acrylate, n-octyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, isodecyl(meth)acrylate, lauryl(meth)acrylate, cetyl(meth)acrylate, and stearyl(meth)acrylate. Among these, n-butyl(meth)acrylate and ethyl(meth)acrylate are preferred from the viewpoint of adhesive strength. The alkyl(meth)acrylate (a2) can be used alone or in combination of two or more.

[0029] The alkyl(meth)acrylate (a2) preferably contains at least one monomer having a glass transition temperature of −30° C. or higher. Examples of the monomer (a2-1) having a glass transition temperature of −30° C. or higher include ethyl(meth)acrylate and methyl(meth)acrylate. The content of the alkyl (meth)acrylate (a2-1) having a glass transition temperature of -30°C or higher is 0 to 75% by weight, preferably 10 to 60% by weight, and more preferably 20 to 40% by weight, relative to the alkyl (meth)acrylate (a2). If the content is too low, the plasticizer resistance of the polyvinyl chloride substrate tends to decrease, while if the content is too high, the adhesive properties tend to decrease, the glass transition temperature increases, and the melt viscosity increases, which tends to decrease hot-melt coatability. The glass transition temperature of the alkyl (meth)acrylate (a2) is the glass transition temperature of a homopolymer prepared from the monomer (a2), and is usually a value measured by a differential scanning calorimeter (DSC) according to a method in accordance with JIS K7121-1987 or JIS K6240, or a value listed in a catalog.

[0030] The content of the alkyl (meth)acrylate (a2) relative to the copolymerization component (a) is usually 1 to 99 wt%, preferably 50 to 97 wt%, more preferably 70 to 95 wt%. If the content is too low, the glass transition temperature will increase, and the adhesive properties of the resulting adhesive will tend to deteriorate overall, while if the content is too high, the holding power of the resulting adhesive will tend to deteriorate.

[0031] [Polar Group-Containing Ethylenically Unsaturated Monomer (a3)] The polar group-containing ethylenically unsaturated monomer (a3) ​​is an ethylenically unsaturated monomer containing a polar group other than an active energy ray-active site, excluding the monomer (a1) having an active energy ray-active site and alkyl (meth)acrylate (a2). Examples of the polar group-containing ethylenically unsaturated monomer (a3) ​​include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, amide group-containing monomers, and cyano group-containing monomers. The polar group-containing ethylenically unsaturated monomer (a3) ​​can be used alone or in combination of two or more. Among these, monomers having at least one of a carboxyl group, a hydroxyl group, and an amide group are preferred, and carboxyl group-containing monomers are more preferred, in terms of excellent adhesive strength of the (meth)acrylic resin (A) obtained by copolymerization.

[0032] The hydroxyl group-containing monomers include primary hydroxyl group-containing monomers, secondary hydroxyl group-containing monomers, and tertiary hydroxyl group-containing monomers. Examples of primary hydroxyl group-containing monomers include (meth)acrylic acid hydroxyalkyl ester monomers such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth)acrylate; oxyalkylene-modified monomers such as diethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate; and others such as 2-acryloyloxyethyl-2-hydroxyethyl phthalate, N-methylol (meth)acrylamide, and hydroxyethyl acrylamide. Examples of the secondary hydroxyl group-containing monomer include 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-chloro 2-hydroxypropyl (meth)acrylate. Examples of the tertiary hydroxyl group-containing monomer include 2,2-dimethyl 2-hydroxyethyl (meth)acrylate.

[0033] Examples of the carboxy group-containing monomer include (meth)acrylic acid, β-carboxyethyl (meth)acrylate, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, N-glycolic acid, cinnamic acid, etc. Among these, acrylic acid is more preferred because of its high versatility.

[0034] Examples of the amino group-containing monomer include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and quaternized products thereof.

[0035] Examples of the amide group-containing monomer include (meth)acrylamide, N-(n-butoxyalkyl)(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, vinylpyrrolidone, and acryloylmorpholine.

[0036] Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

[0037] The content of the polar group-containing ethylenically unsaturated monomer (a3) ​​is usually 20% by weight or less, preferably 0.1% by weight or more and 15% by weight or less, more preferably 0.5% by weight or more and 10% by weight or less, even more preferably 1% by weight or more and 8% by weight or less, and particularly preferably 2% by weight or more and 7% by weight or less, based on the copolymerization component (a) in order to achieve both thermal stability and adhesive properties of the resin. If the content is too high, the thermal stability of the (meth)acrylic resin (A) obtained by copolymerization tends to decrease. If the content is too low, the adhesive strength of the adhesive obtained by crosslinking tends to decrease.

[0038] [Other polymerizable monomers (a4)] The other polymerizable monomer (a4) may be any polymerizable monomer other than the above (a1), (a2), and (a3), and examples thereof include alicyclic structure-containing monomers, aromatic monomers, alkoxy group-containing monomers, vinyl monomers, etc. These may be used alone or in combination of two or more.

[0039] Examples of the alicyclic structure-containing monomer include (meth)acrylates having an alicyclic structure, such as cyclohexyl (meth)acrylate, isobornyl acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and 2-adamantyl (meth)acrylate.

[0040] Examples of the aromatic monomer include (meth)acrylates having one aromatic ring, such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxydipropylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, and phenoxypolypropylene glycol (meth)acrylate; and (meth)acrylates having two aromatic rings, such as phenoxybenzyl (meth)acrylate and ethoxylated o-phenylphenol (meth)acrylate.

[0041] Examples of the alkoxy group-containing monomer include alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, and 2-butoxyethyl (meth)acrylate.

[0042] Examples of the vinyl monomer include vinyl propionate, vinyl stearate, vinyl acetate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, methyl vinyl ketone, and dimethyl allyl vinyl ketone.

[0043] The other polymerizable monomers (a4) may be contained within a range that does not impair the effects of the present invention, but the amount is preferably 20% by weight or less, more preferably 15% by weight or less, based on the total copolymerization component (a).

[0044] <Method for producing (meth)acrylic resin (A)> The method for producing the (meth)acrylic resin (A) is not particularly limited, and known polymerization methods using the copolymerization component (a) can be used, such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. For example, a method in which an appropriately selected copolymerization component (a) and a polymerization initiator are mixed or dropped into an organic solvent and polymerized under predetermined polymerization conditions can be used. Among the above polymerization methods, solution radical polymerization and bulk polymerization are preferred, and solution radical polymerization is more preferred because it allows the stable production of the (meth)acrylic resin (A).

[0045] Examples of organic solvents used in the above polymerization method include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. These organic solvents can be used alone or in combination of two or more.

[0046] Among these organic solvents, esters such as ethyl acetate and butyl acetate, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone are preferred from the standpoints of ease of polymerization reaction, chain transfer effect, ease of drying when the pressure-sensitive adhesive composition is applied, and safety, with ethyl acetate being particularly preferred. These may be used alone or in combination of two or more. The amount of the organic solvent used is usually 10 to 900 parts by weight per 100 parts by weight of the copolymerization component (a).

[0047] In addition, a conventional radical polymerization initiator can be used for such solution radical polymerization. Examples of radical polymerization initiators include azo-based initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 4,4'-azobis(4-cyanovaleric acid), and 2,2'-azobis(methylpropionic acid); organic peroxides such as benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, and cumene hydroperoxide; and the like. These polymerization initiators can be appropriately selected and used depending on the monomer used. These polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator used is usually 0.01 to 10 parts by weight based on 100 parts by weight of the copolymerization component (a).

[0048] In this way, the (meth)acrylic resin (A) used in the present invention is obtained.

[0049] <Physical properties of (meth)acrylic resin (A)> The weight-average molecular weight (Mw) of the (meth)acrylic resin (A) is preferably from 30,000 to 1,500,000, more preferably from 50,000 to 1,000,000, particularly preferably from 70,000 to 500,000, and even more preferably from 100,000 to 300,000. If the weight-average molecular weight is too small, the cohesive strength tends to be low and the adhesiveness tends to decrease, whereas if it is too large, the melt viscosity tends to be too high and the resin tends to be unsuitable for hot-melt coating.

[0050] The dispersity of the (meth)acrylic resin (A) [weight average molecular weight (Mw) / number average molecular weight (Mn)] is preferably 10 or less, more preferably 7 or less. If the dispersity is too high, the cohesive force tends to decrease. The lower limit of the dispersity is usually 1.

[0051] The weight-average molecular weight of the (meth)acrylic resin (A) is a weight-average molecular weight converted into a standard polystyrene molecular weight. The weight-average molecular weight was measured using a high-performance liquid chromatograph (manufactured by Japan Waters, Inc., "Waters 2695 (main body)" and "Waters 2414 (detector)") with a column: Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 7 Separation range: 100 to 2 × 10 7 The molecular weight can be measured using a system in which three columns (theoretical plate number: 10,000 columns / column, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm) are connected in series, and the number average molecular weight can also be measured in a similar manner. The dispersity can also be determined from the measured values ​​of the weight average molecular weight and number average molecular weight.

[0052] The glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably −85° C. or higher, more preferably −80 to 20° C., particularly preferably −70 to 0° C., even more preferably −60 to −10° C., and especially preferably −50 to −20° C. If the glass transition temperature is too low, the adhesive strength of the pressure-sensitive adhesive sheet after curing tends to decrease, leading to peeling, whereas if the glass transition temperature is too high, the tack before curing tends to decrease, making it difficult to apply to the adherend.

[0053] The glass transition temperature is calculated by the following Fox formula.

[0054]

number

[0055] That is, it is a value calculated by applying the glass transition temperature and weight fraction of a homopolymer prepared from each of the monomers constituting the (meth)acrylic resin (A) to Fox's formula. The glass transition temperature of the homopolymer prepared from the monomers constituting the (meth)acrylic resin (A) is usually a value measured by a differential scanning calorimeter (DSC) according to a method in accordance with JIS K7121-1987 or JIS K6240, or a value listed in a catalog.

[0056] The (meth)acrylic resin (A) is the main component of the pressure-sensitive adhesive composition, and its content in the pressure-sensitive adhesive composition is preferably 50% by weight or more, more preferably 60 to 98% by weight, particularly preferably 70 to 95% by weight, and even more preferably 80 to 92% by weight. If the content is outside this range, the effects of the present invention tend to be difficult to achieve.

[0057] The (meth)acrylic resin (A) obtained by the above-described production method contains an organic solvent, and its solids concentration is usually 10 to 80% by weight, preferably 30 to 70% by weight. When the solids concentration is within the range of 10 to 80% by weight, the viscosity of the diluted (meth)acrylic resin (A) is preferably 500 to 30,000 mPa·s / 25°C, more preferably 1,000 to 10,000 mPa·s / 25°C. If the viscosity is too low, when a component with a high specific gravity is used as the chlorinated polyolefin (B) or tackifier (C) described below, the component tends to settle, resulting in a non-uniform concentration of the component in the (meth)acrylic resin (A).

[0058] <Chlorinated polyolefin (B)> The chlorinated polyolefin (B) used in the present invention is not particularly limited, and examples thereof include polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, polybutene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, natural rubber, and olefin-based rubber, as well as chlorinated polyolefin resins obtained by chlorinating modified polyolefins in which a carboxyl group, a hydroxyl group, an acid anhydride group, or the like has been introduced into these polyolefins.

[0059] The method for producing the chlorinated polyolefin (B) is not particularly limited. For example, the desired chlorinated polyolefin resin can be easily obtained by dissolving or dispersing the above-mentioned polyolefins or modified polyolefins in a suitable medium and then reacting the resulting mixture with chlorine gas. The chlorinated polyolefin (B) is preferably a chlorinated polyolefin resin obtained by chlorinating polypropylene and / or polyethylene.

[0060] The form of the chlorinated polyolefin (B) is not particularly limited, and it can be used in various forms such as a solid, a solution, a dispersion, etc. Examples thereof include a chlorinated polyolefin resin solution obtained by dissolving a solid chlorinated polyolefin in a soluble medium, and a chlorinated polyolefin emulsion obtained by dispersing the solid chlorinated polyolefin in an aqueous medium.

[0061] The chlorine content in the chlorinated polyolefin (B) is more than 25% by weight and less than 36% by weight, preferably 26 to 34% by weight, and more preferably 28 to 32% by weight. If the chlorine content is too low, the thermal stability, adhesion to the PVC substrate sheet, and transparency of the pressure-sensitive adhesive sheet tend to be poor, while if the chlorine content is too high, the transparency of the pressure-sensitive adhesive sheet tends to be poor. The chlorine content in the chlorinated polyolefin (B) is measured in accordance with JIS-K7229 or a value listed in a catalog. For example, the chlorine content can be measured by the oxygen flask combustion method, in which a chlorine-containing resin is burned in an oxygen atmosphere, the generated chlorine gas is absorbed with water, and the amount is determined by titration.

[0062] The weight-average molecular weight of the chlorinated polyolefin (B) is not particularly limited, but is preferably not more than 30,000, more preferably not more than 10,000. If the weight-average molecular weight is within the above range, compatibility with the (meth)acrylic resin (A) will be improved, and adhesion to the PVC substrate sheet and transparency of the pressure-sensitive adhesive sheet will tend to be improved.

[0063] The weight-average molecular weight of the chlorinated polyolefin (B) can be measured in the same manner as the weight-average molecular weight of the (meth)acrylic resin (A) described above. Specifically, it is the weight-average molecular weight converted into the molecular weight of standard polystyrene, and is measured using a high-performance liquid chromatograph (manufactured by Japan Waters, "Waters 2695 (main body)" and "Waters 2414 (detector)") with a column: Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 7 Separation range: 100 to 2 × 10 7 The molecular weight can be measured using a system in which three columns (theoretical plate number: 10,000 columns / column, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm) are connected in series, and the number average molecular weight can also be measured in a similar manner. The dispersity can also be determined from the measured values ​​of the weight average molecular weight and number average molecular weight.

[0064] Commercially available chlorinated polyolefins (B) include the Superchlorine (registered trademark) series (manufactured by Nippon Paper Industries Co., Ltd.), the Hardlen (registered trademark) series (manufactured by Toyobo MC Co., Ltd.), and the Elaslen (registered trademark) series (manufactured by Resonac Co., Ltd.). More specifically, the Superchlorine (registered trademark) series includes 813A (chlorine content 30%, weight average molecular weight 8000), 390S (chlorine content 36%, weight average molecular weight 39400), 822S (chlorine content 24.5%, weight average molecular weight 74000), 773H, 892L, 832L, 803L, L, 803MW, E, 803M, 813A, 803H, 804M, C, 814HS, L-206, A, B, and BX. Examples of the Hardlen (registered trademark) series include 13-LP, 13-LLP, 14-LWP, 15-LP, 15-LLP, DX-526P, CY-9122P, CY-9124P, HM-21P, M-28P, F-2P, and F-6P. Examples of the Elaslen (registered trademark) series include 301MA, 301A, 351A, 401A, 302NA-XS, 402NA-XS, 303JA, 252B, 303JB, 301MB, 352GB-X5, 402B, and 404FB. These may be used alone or in combination of two or more.

[0065] <Tackifier (C)> The pressure-sensitive adhesive composition of the present invention may further contain a tackifier (C). Examples of the tackifier (C) include rosin-based resins, phenol-based resins, terpene-based resins, modified terpene-based resins, hydrocarbon-based resins, epoxy-based resins, polyamide-based resins, elastomer-based resins, and ketone-based resins. From the viewpoint of adhesive strength to low-polarity adherends such as polyethylene (PE), rosin-based resins and hydrocarbon-based resins are preferred. Examples of rosin resins include modified rosin resins such as hydrogenated rosin, disproportionated rosin, and polymerized rosin; and rosin esters obtained by esterifying unmodified rosin with alcohols. Examples of hydrocarbon resins include C5 petroleum resins, C9 petroleum resins, alicyclic petroleum resins, styrene resins, and styrene-aliphatic monomer copolymer resins. The tackifier (C) can be used alone or in combination of two or more.

[0066] The softening point of the tackifier (C) is preferably 20 to 180° C., more preferably 50 to 160° C., and particularly preferably 70 to 130° C. If the softening point is too high or too low, the adhesive properties of the pressure-sensitive adhesive composition tend to decrease. Furthermore, if the softening point is too high, the melt viscosity of the pressure-sensitive adhesive composition increases, which tends to decrease hot-melt coatability. The softening point of the tackifier (C) is determined by the R&B (ring and ball) method in accordance with JIS K59025.3 (1969). The softening point can be measured, for example, using an automatic softening point measuring device (manufactured by Elex Scientific Co., Ltd.) that automates heating and softening point measurement. When the softening point has a range, the average value of the sum of the upper and lower limits is taken as the softening point.

[0067] When the pressure-sensitive adhesive composition of the present invention contains a tackifier (C), the content of the tackifier (C) is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, particularly preferably 30 parts by weight or less, and even more preferably 20 parts by weight or less, relative to 100 parts by weight (solid content) of the (meth)acrylic resin (A). If the content is too high, the effects of the present invention tend to be difficult to achieve.

[0068] <Thermal crosslinking agent (D)> The pressure-sensitive adhesive composition of the present invention may contain a thermal crosslinking agent (D), and in such a case, the content of the thermal crosslinking agent (D) is preferably less than 0.05% by weight, more preferably less than 0.01% by mass, of the total pressure-sensitive adhesive composition. Most preferably, the pressure-sensitive adhesive composition does not contain a thermal crosslinking agent (D).

[0069] Examples of the thermal crosslinking agent (D) include isocyanate-based curing agents, epoxy-based curing agents, metal chelate curing agents, and aziridine-based curing agents.

[0070] <Optional ingredients> In addition to the above components, the pressure-sensitive adhesive composition of the present invention may also contain various additives as optional components, such as conductive agents such as carbon and metals, inorganic fillers such as metal particles and glass particles, bulking agents, antioxidants, ultraviolet absorbers, crosslinking accelerators such as ionic compounds, peroxides, silane coupling agents, and urethane catalysts, crosslinking retarders such as acetylacetone, monofunctional monomers, and polyfunctional monomers. These may be used alone or in combination of two or more.

[0071] In addition to the optional components described above, the pressure-sensitive adhesive composition of the present invention may contain impurities contained in the raw materials for producing the components of the pressure-sensitive adhesive composition, to the extent that the effects of the present invention are not impaired.

[0072] When the optional components are used, the content thereof is preferably 5 parts by weight or less, more preferably 1 part by weight or less, and even more preferably 0.5 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic resin (A). If the content is too high, the effects of the present invention tend to be impaired.

[0073] <Method of manufacturing pressure-sensitive adhesive composition> The pressure-sensitive adhesive composition of the present invention can be obtained by mixing at least the (meth)acrylic resin (A) and the chlorinated polyolefin (B), and, if necessary, further mixing optional components such as the tackifier (C).

[0074] The method for mixing these components is not particularly limited, and various methods can be used, such as a method in which the components are mixed all at once, or a method in which any component is mixed and then the remaining components are mixed all at once or sequentially.

[0075] The total content of the (meth)acrylic resin (A) and the chlorinated polyolefin (B) in the pressure-sensitive adhesive composition is preferably 80% by weight or more, more preferably 85% by weight or more, and particularly preferably 90% by weight or more.

[0076] The pressure-sensitive adhesive composition of the present invention is useful as a pressure-sensitive adhesive component, particularly as a hot-melt pressure-sensitive adhesive component. When used for hot-melt applications, the above components are blended to obtain a pressure-sensitive adhesive composition solution, and then the organic solvent (hereinafter sometimes simply referred to as "solvent") is distilled off.

[0077] The step of distilling off the solvent from the solution of the PSA composition obtained by blending can be carried out by a known method. Methods for distilling off the solvent include a method of distilling off the solvent by heating and a method of distilling off the solvent by reducing pressure, but from the viewpoint of efficiently distilling off the solvent, a method of distilling off the solvent by heating under reduced pressure is preferred.

[0078] The temperature when distilling off the solvent by heating is preferably 60 to 150° C. In particular, it is preferable to hold the reaction solution after polymerizing the (meth)acrylic resin (A) at 60 to 80° C. to distill off the solvent, and then distill off the solvent at 80 to 150° C., in order to minimize the amount of remaining solvent. Note that in order to prevent gelation of the (meth)acrylic resin (A), it is preferable that the temperature during solvent distillation is not 150° C. or higher.

[0079] The pressure when distilling off the solvent under reduced pressure is preferably 20 to 101.3 kPa. In particular, it is preferred to maintain the pressure in the range of 50 to 101.3 kPa to distill off the solvent in the reaction solution, and then distill off the remaining solvent at 0 to 50 kPa, in order to minimize the amount of remaining solvent. Thus, the pressure-sensitive adhesive composition of the present invention can be produced.

[0080] The pressure-sensitive adhesive composition of the present invention preferably contains substantially no solvent, and more preferably the solvent content of the pressure-sensitive adhesive composition is 2 wt % or less, particularly preferably 0.00001 to 2 wt %, further preferably 0.0001 to 1 wt %, and most preferably 0.001 to 0.1 wt %. If the solvent content is too high, bubbles tend to form and the physical properties after curing with active energy rays tend to deteriorate.

[0081] The melt viscosity of the pressure-sensitive adhesive composition of the present invention is preferably 1 to 1500 Pa·s, more preferably 2 to 500 Pa·s, particularly preferably 3 to 90 Pa·s, even more preferably 4 to 60 Pa·s, and most preferably 5 to 30 Pa·s. If the melt viscosity of the pressure-sensitive adhesive composition is too high, the coatability during hot-melt coating tends to decrease. On the other hand, if the melt viscosity of the pressure-sensitive adhesive composition is too low, the adhesive properties after curing with active energy rays tend to decrease due to a decrease in molecular weight.

[0082] The melt viscosity of the pressure-sensitive adhesive composition is measured using a solvent-free pressure-sensitive adhesive composition obtained by distilling off the solvent, with a rotational rheometer under the following conditions. Measuring equipment: MCR301 (manufactured by Anton Paar) Cone plate diameter: 25mm Measurement distance: 0.5mm Measurement shear rate: 0.002 (1 / S) ·Measurement temperature: 150℃

[0083] <Adhesive, adhesive sheet, and laminate> The pressure-sensitive adhesive composition of the present invention can be made into a pressure-sensitive adhesive by crosslinking the (meth)acrylic resin (A). Furthermore, by laminating a pressure-sensitive adhesive layer containing this pressure-sensitive adhesive onto a substrate sheet such as a plastic film, a pressure-sensitive adhesive sheet having a substrate sheet / pressure-sensitive adhesive layer laminate structure can be obtained. Furthermore, by laminating this pressure-sensitive adhesive layer onto an adherend, a laminate having an adherend / pressure-sensitive adhesive layer laminate structure can be obtained. Hereinafter, the substrate sheet and adherend will be collectively referred to as "members." In other words, the concept of a laminate encompasses the concept of a pressure-sensitive adhesive sheet.

[0084] The pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer laminated on a substrate sheet, as well as a substrate-less double-sided pressure-sensitive adhesive sheet having separators (release sheets) laminated on both sides of the pressure-sensitive adhesive layer, with the double-sided pressure-sensitive adhesive sheet being preferred from the viewpoint of ease of handling. When using the pressure-sensitive adhesive sheet or double-sided pressure-sensitive adhesive sheet, the release sheet is peeled off from the pressure-sensitive adhesive layer before use.

[0085] The pressure-sensitive adhesive layer may be the pressure-sensitive adhesive composition of the present invention itself, or may be obtained by curing (crosslinking) the pressure-sensitive adhesive composition of the present invention. Examples of the curing method include a method of curing by irradiation with active energy rays, a method of curing by crosslinking using a crosslinking agent, and a combination of these methods.

[0086] The pressure-sensitive adhesive sheet can be produced, for example, as follows. In this specification, the term "sheet" is not particularly distinguished from "film" or "tape" and is used to include these terms.

[0087] First, a pressure-sensitive adhesive layer having a predetermined thickness is formed on one or both sides of a substrate sheet by a method such as coating the pressure-sensitive adhesive composition in a melted state by heating onto one or both sides of a substrate sheet and then cooling, or by melting the pressure-sensitive adhesive composition by heating and extruding it onto the substrate sheet using a T-die or the like and laminating it, or by drying the solvent after coating if a solvent is contained in the composition, etc. Next, a pressure-sensitive adhesive sheet can be produced by laminating a release sheet to the surface of the pressure-sensitive adhesive layer, if necessary.

[0088] Furthermore, after forming the adhesive layer on the base sheet, if necessary, an active energy ray irradiation treatment is carried out, followed by an aging treatment, whereby an adhesive sheet having an adhesive layer in which the adhesive composition is cured (crosslinked) can be produced.

[0089] Examples of substrate sheets include polyester-based resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin-based resins such as polyethylene, polypropylene (PP), and polymethylpentene; polyethylene fluoride resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose-based resins such as cellulose triacetate and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; polystyrene; polycarbonate; polyarylate; and synthetic resin sheets such as polyimide; metal foils such as aluminum, copper, and iron; paper such as fine paper and glassine paper; and woven and nonwoven fabrics made of glass fiber, natural fiber, synthetic fiber, etc. These substrate sheets can be used as a single layer or as a multi-layered body in which two or more types are laminated together. Among these, synthetic resin sheets are preferred from the viewpoint of weight reduction and the like.

[0090] As the release sheet, for example, a release-treated synthetic resin sheet, paper, cloth, nonwoven fabric, etc., exemplified above as the base sheet, can be used. As the release sheet, it is preferable to use a silicone-based release sheet.

[0091] As a method for applying the pressure-sensitive adhesive composition, a general application method can be adopted, and examples thereof include roll coating, die coating, gravure coating, comma coating, and screen printing.

[0092] By irradiating the pressure-sensitive adhesive composition with active energy rays, the (meth)acrylic resin (A) in the pressure-sensitive adhesive composition forms intramolecular and / or intermolecular crosslinked structures.

[0093] When irradiating with active energy rays, light rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X-rays and gamma rays, as well as electron beams, proton beams, neutron beams, etc. can be used. However, curing by ultraviolet irradiation is advantageous in terms of curing speed, ease of obtaining irradiation equipment, cost, etc.

[0094] The aging treatment is preferably carried out particularly when the pressure-sensitive adhesive composition contains a thermal crosslinking agent (D), and the conditions for the aging treatment are typically room temperature (25°C) to 100°C and typically 1 to 30 days. Specifically, the aging treatment can be carried out, for example, at 23°C for 1 to 20 days, preferably at 23°C for 3 to 10 days, or at 40°C for 1 to 7 days.

[0095] The gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is preferably 10 to 90%, more preferably 20 to 80%, and particularly preferably 40 to 60%, from the viewpoint of the balance of physical properties such as adhesive strength, holding power, and adhesion to PVC substrates. If the gel fraction is too low, the holding power tends to decrease due to a decrease in cohesive strength. On the other hand, if the gel fraction is too high, the adhesive strength tends to decrease due to an increase in cohesive strength.

[0096] The gel fraction can be adjusted to fall within the above range by, for example, adjusting the active energy ray irradiation dose or the type and amount of the monomer (a1) having an active energy ray-active site, or, when a thermal crosslinking agent (D) is used, adjusting the type and amount of the thermal crosslinking agent (D).

[0097] The gel fraction is a measure of the degree of crosslinking (degree of cure) and is calculated, for example, by the following method. A pressure-sensitive adhesive sheet (without a separator) consisting of a substrate polymer sheet (e.g., polyethylene terephthalate (PET) film, etc.) on which a pressure-sensitive adhesive layer is formed is wrapped in a 200-mesh SUS wire netting and immersed in toluene at 23°C for 24 hours, and the weight percentage of the undissolved pressure-sensitive adhesive component remaining in the wire netting is taken as the gel fraction. The weight of the pressure-sensitive adhesive component is calculated by subtracting the weight of the substrate from the weight of the pressure-sensitive adhesive sheet.

[0098] The thickness of the adhesive layer of the adhesive sheet is preferably 5 to 2000 μm, more preferably 10 to 100 μm, and particularly preferably 20 to 30 μm. If the thickness of the adhesive layer is too thin, the adhesiveness tends to decrease, and if it is too thick, the adhesive tends to overflow when used as an adhesive label.

[0099] The thickness of the adhesive layer was determined by subtracting the measured thickness of the components other than the adhesive layer from the measured thickness of the entire adhesive sheet containing the adhesive layer using a Mitutoyo ID-C112B.

[0100] The adhesive composition of the present invention provides an adhesive that has excellent hot-melt coatability, high heat resistance, and in which the adhesive layer of an adhesive sheet using a polyvinyl chloride (PVC) substrate sheet has excellent adhesion to the PVC substrate sheet, and which has excellent adhesive properties such as adhesive strength and holding power to poorly adhesive olefin adherends, and in which the adhesive sheet also has excellent transparency.

[0101] Therefore, the pressure-sensitive adhesive composition of the present invention is useful for various applications, even among hot melt coatings, such as adhesive applications for caution labels, labels for frozen foods, building materials, automobile parts, electronic parts, heat dissipation sheets, FPC manufacturing, semiconductor manufacturing processes, component sealing, aircraft parts, and sporting goods, and is particularly suitable for use in automobile parts and marking films (pressure-sensitive adhesive sheets and pressure-sensitive adhesive tapes). [Example]

[0102] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by weight. The weight average molecular weight, dispersity, and glass transition temperature (Tg) of the (meth)acrylic resin (A) in the following examples were measured according to the methods described above. The viscosity was measured according to JIS K5400 (1990) 4.5.3 Rotational Viscosity Method. First, prior to the examples, the following components were prepared.

[0103] <(Meth)acrylic resin (A)> The following were used as raw material monomers for the (meth)acrylic resin. Monomer (a1) having an active energy ray active site MBP: 4-methacryloyloxybenzophenone (Tg = 118°C, manufactured by Shinryo Corporation) Alkyl (meth)acrylate (a2) BA: normal butyl acrylate (Tg = -55°C, manufactured by Mitsubishi Chemical Corporation) EA: Ethyl acrylate (Tg = -22°C, manufactured by Mitsubishi Chemical Corporation) Polar group-containing ethylenically unsaturated monomer (a3) Aac: acrylic acid (Tg = 106°C, manufactured by Nippon Shokubai Co., Ltd.)

[0104] [Production of (meth)acrylic resin (A-1)] A four-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer was charged with 42.9 parts of methyl ethyl ketone (MEK) and 0.007 parts of azobis(2,4-dimethylvaleronitrile) (ADVN) as a polymerization initiator. After heating and refluxing in the flask, a mixed solution of 64.7 parts of BA, 30 parts of EA, 0.3 parts of MBP, 5 parts of Aac, 2.9 parts of MEK, and 0.093 parts of ADVN was added dropwise over 2 hours. One hour after the monomer addition was completed, 0.057 parts of polymerization initiator (ADVN) and 2.9 parts of MEK were added and the reaction was continued for 1 hour. After that, 0.057 parts of polymerization initiator (ADVN) and 2.9 parts of MEK were added and the reaction was continued for 1 hour. Further, 0.029 parts of a polymerization initiator (ADVN) and 2.9 parts of methyl ethyl ketone were added, and the mixture was allowed to react for 2 hours to obtain a (meth)acrylic resin (A-1) solution [solids concentration 59.4%, viscosity 2520 mPa s, weight average molecular weight (Mw) 150,000, dispersity 2.73 (Mw / Mn), calculated Tg = -40.6°C].

[0105] [Table 1]

[0106] <Chlorinated polyolefin (B)> The following chlorinated polyolefins (B) were prepared. (B-1) Superchlorine 813A (manufactured by Nippon Paper Industries Co., Ltd., chlorine content 30%, weight average molecular weight 8000) (B'-1) Superchlorine 390S (manufactured by Nippon Paper Industries Co., Ltd., chlorine content 36%, weight average molecular weight 39,400) (B'-2) Superchlorine 822S (manufactured by Nippon Paper Industries Co., Ltd., chlorine content 24.5%, weight average molecular weight 74,000)

[0107] <Tackifier (C)> (C-1) Pine Crystal KE100 (Arakawa Chemical Industries, ultra-light-colored rosin, softening point 95-105°C (catalog value), acid value 2-10 (catalog value)) (C-2) FTR6100 (Mitsui Chemicals, aromatic hydrocarbon resin, melting point 95°C, acid value 0.1 or less)

[0108] <Examples 1 to 3, Comparative Examples 1 to 3> The above (meth)acrylic resin (A), chlorinated polyolefin (B), and tackifier (C) were blended according to Table 2. All blending amounts are solid contents. The blended solution was placed in a flask equipped with a T-shaped connecting tube so that the solvent could be distilled out of the system, and the mixture was left at a jacket temperature of 80°C for 1 hour, and then reduced to 10 kPa and left at a jacket temperature of 90°C for 2 hours to distill off the solvent, thereby obtaining pressure-sensitive adhesive compositions as described in Examples 1 to 3 and Comparative Examples 1 to 3. The resulting pressure-sensitive adhesive compositions were evaluated for hot-melt coatability and thermal stability as described below.

[0109] <Hot melt coatability> The melt viscosity of the pressure-sensitive adhesive composition was measured to evaluate whether it could be applied in a molten state as follows. (Melt viscosity measurement) The pressure-sensitive adhesive composition obtained by distilling off the solvent as described above and becoming solvent-free was measured using a rotational rheometer under the following conditions. Measuring equipment: MCR301 (manufactured by Anton Paar) Cone plate diameter: 25mm Measurement distance: 0.5mm Measurement shear rate: 0.002 (1 / S) ·Measurement temperature: 150℃ The evaluation was carried out according to the following criteria, and the results are summarized in Table 2.

[0110] (Evaluation criteria) ◎··30Pa·s or less ○ More than 30 Pa·s and less than 60 Pa·s △: More than 60 Pa·s and less than 90 Pa·s ×··Greater than 90 Pa·s

[0111] <Thermal stability> The adhesive composition obtained by distilling off the solvent as described above was subjected to melt viscosity measurement using a rotational rheometer. (150℃, 8 hours) As shown in the following formula 1, the melt viscosity of the pressure-sensitive adhesive composition after heat treatment at 150°C for 8 hours was defined as M2, and the melt viscosity of the pressure-sensitive adhesive composition before the heat treatment was defined as M1. The melt viscosity change rate M (%) was calculated and evaluated according to the following evaluation criteria. The results are summarized in Table 2.

[0112] [Formula 1] M(%) = (|M2-M1| / M1) × 100 M2: Melt viscosity of the adhesive composition after heat treatment at 150°C for 8 hours M1: Melt viscosity of the pressure-sensitive adhesive composition before the heat treatment

[0113] (Evaluation criteria, thermal stability) ◎ M is less than 10% ○··M is less than 10% or 20% × M is 20% or more

[0114] [Table 2]

[0115] [Preparation of adhesive sheet (PVC substrate)] The adhesive compositions of Examples 1 to 3 and Comparative Examples 1 to 3 were blended with ethyl acetate and diluted until the solid content concentration reached 50%. Then, using an applicator, they were applied to a light release silicon separator (manufactured by Mitsui Chemicals Toagosei Co., Ltd., "SPPET01 38BU") with a thickness of 38 μm so that the thickness after drying would be 25 μm, forming a layer of the adhesive composition. Using a UV irradiation device with a high-pressure mercury lamp, ultraviolet irradiation was performed at a predetermined dose (130 mW / cm 2 , X mJ / cm 2 , where X is the value described in the column of irradiation conditions in Table 3) to form an adhesive layer. By laminating a soft PVC film with a thickness of 8 μm from the surface of the adhesive layer, an adhesive sheet was produced (a laminate of soft PVC film / adhesive layer / light release silicon separator).

[0116] <Adhesion to PVC substrate> After aging the adhesive sheet with the PVC substrate obtained above for 1 day, the separator was peeled off, and the adhesive adhered to the PVC film was rubbed 10 times with a silicon stopper. The state was confirmed and evaluated as follows. The results are summarized in Table 3.

[0117] (Evaluation criteria) 〇··No peeling ×··Peeling occurred

[0118] <Adhesive strength> A test piece with a width of 25 mm × 200 mm was prepared from the above adhesive sheet having a PVC substrate. After peeling off the separator, it was pressure-bonded to adherends [PE plate and PP plate] with a 2 kg rubber roller reciprocated twice in an atmosphere of 23°C and 50% RH, and left standing at 23°C for 30 minutes. Then, in accordance with JIS Z 0237, the 180° peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min and evaluated as follows. The results are summarized in Table 3.

[0119] (Evaluation criteria, for PE plate and PP plate) ◎··12.0 N / 25 mm or more and peeling at the adherend interface ○··8.0 N / 25 mm or more, less than 12.0 N / 25 mm and peeling at the adherend interface △ 8.0N / 25mm or more and cohesive peeling, substrate interface peeling or zipping × Less than 8.0N / 25mm

[0120] <Holding power> A 25mm x 25mm test piece was prepared from the PVC-backed adhesive sheet. After removing the separator, the test piece was pressed against a sandpaper-polished stainless steel plate (SUS304) using a 2kg roller back and forth (25mm x 25mm area). The holding strength was measured using a creep tester (Tester Sangyo Co., Ltd., BE-501 high-temperature, constant-humidity chamber-equipped holding strength tester) under a 1kg load in a 40°C atmosphere for 24 hours. The holding strength was evaluated using the following criteria. The results are summarized in Table 3. The values ​​in Table 3 indicate the distance (mm) the test piece was rubbed, and "NC" indicates no slippage.

[0121] (Evaluation criteria) ◎ Maintains for 1440 minutes or more without misalignment ○··Maintained for 1440 minutes or more, but there was a discrepancy △··Maintained for 30 minutes or more and less than 1440 minutes ×: held for less than 30 minutes

[0122] [Preparation of adhesive sheet (heavy release separator / adhesive / light release separator)] Each of the pressure-sensitive adhesive compositions of Examples 1 to 3 and Comparative Examples 1 to 3 was mixed with ethyl acetate and diluted to a solids concentration of 50%, after which it was applied to a 38 μm-thick easy-release silicone separator (Mitsui Chemicals Tohcello, Inc., "SPPET01 38BU") using an applicator so that the thickness after drying would be 25 μm, forming a layer of the pressure-sensitive adhesive composition. A UV irradiation device using a high-pressure mercury lamp was used to apply the composition at a predetermined dose (130 mW / cm 2 , XmJ / cm 2where X is the value listed in the irradiation conditions column in Table 3), to form a pressure-sensitive adhesive layer. A 38 μm-thick heavy release silicone separator (manufactured by Mitsui Chemicals Tocello, Inc., "SPPET03 38BU") was attached to the surface of the pressure-sensitive adhesive layer to produce a pressure-sensitive adhesive sheet (a laminate of heavy release separator / pressure-sensitive adhesive layer / light release separator).

[0123] <Gel fraction> The adhesive was picked from the heavy release separator / adhesive layer / light release separator configuration obtained above, wrapped in a 200-mesh SUS wire mesh, and immersed in toluene adjusted to 23°C for 24 hours. The weight of the adhesive before immersion in toluene and the undissolved adhesive components remaining in the wire mesh after immersion were weighed, and the weight of the undissolved adhesive components divided by the weight of the adhesive before immersion was taken as the gel fraction (%). The results are summarized in Table 3.

[0124] [Preparation of test specimen (alkali-free glass / adhesive layer)] After peeling the light release separator from the heavy release separator / adhesive layer / light release separator sheet obtained above, the sheet was pressed and attached to alkali-free glass (Corning Eagle XG, 1.1 mm thick) using a 2 kg rubber roller that was rolled back and forth twice, and then allowed to stand for 30 minutes at 23° C. The remaining release sheet was peeled off to produce a test piece with an alkali-free glass / adhesive layer structure.

[0125] The haze value was measured using the test piece obtained above, and evaluated according to the following evaluation criteria. <Haze> The haze value was calculated by measuring the diffuse transmittance and total luminous transmittance using a HAZE MATER NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.) and substituting the obtained diffuse transmittance (DT) and total luminous transmittance (TT) values ​​into the following formula 2. This machine complies with JIS K7361-1. (Formula 2) Haze value (%) = (DT / TT) x 100

[0126] (Evaluation criteria) ◎ 1.0% or less ○ More than 1.0% and 2.0% or less △: More than 2.0% and 4.0% or less × Exceeds 4.0%

[0127] [Table 3]

[0128] Examples 1 to 3, which used the pressure-sensitive adhesive composition of the present invention, contained a (meth)acrylic resin (A) containing a structural unit derived from a monomer having an active energy active site and a chlorinated polyolefin (B) having a chlorine content of more than 25% by weight and less than 36% by weight, and therefore resulted in excellent hot-melt coatability, thermal stability of the composition, adhesion of the pressure-sensitive adhesive sheet to a PVC substrate, adhesion to olefins (PE board and PP board), and transparency.

[0129] On the other hand, the adhesive composition of Comparative Example 1 did not contain chlorinated polyolefin (B), and therefore showed poor adhesive strength to olefin (PP plate). Furthermore, the adhesive compositions of Comparative Examples 2 and 3 contained chlorinated polyolefin (B), but the chlorine content was 25% by weight or less or 36% by weight or more, resulting in poor compatibility with the (meth)acrylic resin (A), high sheet haze values, and poor adhesive strength to olefin (PP plate). Furthermore, Comparative Example 3 showed poor adhesion of the adhesive sheet to a PVC substrate. [Industrial Applicability]

[0130] The adhesive obtained using the adhesive composition of the present invention has good hot-melt coatability, so that the organic solvent is less likely to volatilize after use, reducing harmfulness to humans and animals. Furthermore, the adhesive of the present invention has high adhesion to polyolefins, which are difficult to adhere to, and excellent holding power, and also has excellent transparency of the adhesive sheet, so that it can be used in various applications such as automobile parts, building materials, electronic parts, and office automation equipment.

Claims

1. A pressure-sensitive adhesive composition comprising a (meth)acrylic resin (A) and a chlorinated polyolefin (B), the (meth)acrylic resin (A) contains a structural unit derived from a monomer (a1) having an active energy ray-active site, A pressure-sensitive adhesive composition, wherein the chlorine content of the chlorinated polyolefin (B) is more than 25% by weight and less than 36% by weight of the total chlorinated polyolefin (B).

2. The pressure-sensitive adhesive composition according to claim 1 , wherein the (meth)acrylic resin (A) has a structural unit derived from a polar group-containing ethylenically unsaturated monomer (a3).

3. 3. The pressure-sensitive adhesive composition according to claim 1, wherein the weight-average molecular weight of the chlorinated polyolefin (B) is 30,000 or less.

4. The pressure-sensitive adhesive composition according to claim 1 or 2, further comprising a tackifier (C).

5. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the content of the thermal crosslinking agent (D) is less than 0.05% by mass.

6. A pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to claim 1 or 2.

7. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to claim 6.

8. A pressure-sensitive adhesive sheet comprising a polyvinyl chloride substrate sheet and a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to claim 6.

9. A laminate comprising a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive according to claim 6 and a member laminated thereon.

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