Adhesive composition and adhesive layer

Abstract

Provided is an adhesive composition containing 5-250 parts by mass of liquid farnesene rubber (B) and 10-500 parts by mass of a tackifying resin (C) per 100 parts by mass of at least one solid rubber (A) selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene rubber, and butyl rubber, the liquid farnesene rubber (B) satisfying requirements (I) and (II). (I) The melt viscosity measured at 38°C is within the range of 0.1-3,000 Pa∙s. (II) When measured using gel permeation chromatography (GPC), the maximum peak molecular weight (Mt) is 3,000-200,000, and the molecular weight distribution (Mw / Mn) is 1.0-1.4.

Description

Technical Field

[0001] The present invention relates to an adhesive composition containing a liquid farnesene rubber and an adhesive using the above adhesive composition.

Background Art

[0002] Techniques for using polyfarnesene in an adhesive composition (for example, Patent Document 1), and techniques for using solid rubber and liquid rubber in an adhesive composition are known (for example, Patent Documents 2 and 3). In addition, since an adhesive composition is required to be excellent in processability and handleability in addition to adhesiveness, it is also known to blend a plasticizer or the like. However, when blending process oil, liquid paraffin, etc. generally used as a plasticizer, there are problems that adhesiveness is likely to decrease and bleed-out is likely to occur.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, the above problems caused by a plasticizer or the like have not been studied. In Patent Documents 2 and 3, although adhesiveness and bleed-out resistance are improved, the fact is that further improvement is required. In addition, it is desired that an adhesive composition has various characteristics in addition to adhesiveness and bleed-out resistance. For example, when replacing an adhesive sheet, if the peelability is poor, the adherend will be contaminated with the adhesive. Also, in some cases, it may be required to have the property of transferring the adhesive layer to the adherend like an adhesive transfer sheet. Thus, in some cases, it is desired that the adhesive composition has excellent adhesiveness and bleed-out resistance while having both peelability and transferability.

[0005] Therefore, the present invention provides an adhesive composition that is excellent in adhesiveness and bleed-out resistance and can exhibit peelability and transferability according to temperature conditions.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have conceived the following present invention and found that the problems can be solved. That is, the present invention is as follows.

[0007] [1] With respect to 100 parts by mass of at least one solid rubber (A) selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene rubber, and butyl rubber, it contains 5 to 250 parts by mass of a liquid farnesene-based rubber (B) and 10 to 500 parts by mass of a tackifier resin (C), and the above liquid farnesene-based rubber (B) satisfies the following requirements (I) and (II) in the adhesive composition. (I) The melt viscosity measured at 38 °C is in the range of 0.1 to 3,000 Pa·s. (II) When measured by gel permeation chromatography (GPC), the maximum peak molecular weight (Mt) is 3,000 to 200,000, and the molecular weight distribution (Mw / Mn) is 1.0 to 1.4. [2] The adhesive composition according to the above [1], wherein the amount of catalyst residue derived from the polymerization catalyst used in the production of the liquid farnesene-based rubber (B) in the above liquid farnesene-based rubber (B) is 0 to 200 mass ppm in terms of metal. [3] The pressure-sensitive adhesive composition according to the above [1] or [2], wherein the maximum peak molecular weight (Mt) of the liquid farnesene rubber (B) is 60,000 or more. [4] The pressure-sensitive adhesive composition according to any one of the above [1] to [3], wherein the content of the monomer unit (a) derived from farnesene in the liquid farnesene rubber (B) is 50% by mass or more. [5] Further containing 1 to 200 parts by mass of a plasticizer with respect to 100 parts by mass of the solid rubber (A), the above The pressure-sensitive adhesive composition according to any one of [1] to [4]. [6] The pressure-sensitive adhesive composition according to any one of the above [1] to [5], wherein the solid rubber (A) is natural rubber. [7] The pressure-sensitive adhesive composition according to any one of the above [1] to [5], wherein the solid rubber (A) is at least one selected from the group consisting of polybutadiene rubber and styrene-butadiene copolymer rubber. [8] An adhesive using at least a part of the pressure-sensitive adhesive composition according to any one of the above [1] to [7].

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a pressure-sensitive adhesive composition that is excellent in adhesiveness and bleed-out resistance and can exhibit peelability and transferability according to temperature conditions.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, an example of an embodiment of the present invention will be described. However, the embodiments shown below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following description. In addition, in this specification, although preferred forms of the embodiments are shown, those in which two or more of the individual preferred forms are combined are also preferred forms. For matters indicated by numerical ranges, when there are several numerical ranges, the lower limit value and the upper limit value thereof can be selectively combined to form a preferred form. In this specification, when a numerical range of "XX to YY" is described, it means "XX or more and YY or less".

[0010] <Adhesive Composition> The adhesive composition of this embodiment contains solid rubber (A) (hereinafter, sometimes referred to as “component (A)”), liquid farnesene rubber (B) (hereinafter, sometimes referred to as “component (B)”), and tackifier resin (C) (hereinafter, sometimes referred to as “component (C)”) in specific proportions, and is characterized in that the liquid farnesene rubber (B) satisfies the following requirements (I) and (II). (I) The melt viscosity measured at 38°C is in the range of 0.1 to 3,000 Pa·s. (II) When measured by gel permeation chromatography (GPC), the maximum peak molecular weight (Mt) is 3,000 to 200,000, and the molecular weight distribution (Mw / Mn) is 1.0 to 1.4. (A) Component and (B) component have good compatibility. Good compatibility can be an advantageous factor for achieving an adhesive composition excellent in adhesiveness and bleed-out resistance by a formulation containing (B) component under specific requirements in addition to (A) component and (C) component. Furthermore, by containing (B) component that satisfies the above requirements, there is almost no glue residue at room temperature of about 23°C and the adhesive layer can be peeled off, and the adhesive layer can be transferred to the adherend by heating at about 60°C. That is, the inventors have found that the above formulation is effective for the adhesive composition to be excellent in adhesiveness and bleed-out resistance and exhibit peelability and transferability.

[0011] [Solid Rubber (A)] Solid rubber (A) is rubber that can be handled in a solid state, and is rubber having a Mooney viscosity (ML 1+4 ) at 100°C usually in the range of 20 to 200. (A) component is at least one selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene rubber, and butyl rubber. Among them, from the viewpoints of adhesiveness and bleed-out resistance, the (A) component is preferably natural rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, and styrene-isoprene copolymer rubber (particularly, styrene-isoprene-styrene block copolymer rubber), and more preferably natural rubber, polybutadiene rubber, and styrene-butadiene copolymer rubber.

[0012] From the viewpoint of fully exhibiting the characteristics of the resulting pressure-sensitive adhesive composition, the weight average molecular weight (Mw) of the (A) component is preferably 80,000 or more, and more preferably 100,000 to 3,000,000. The weight average molecular weight in this specification is the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0013] (Natural rubber) Examples of natural rubber include TSR (Technically Specified Rubber) such as SMR (TSR produced in Malaysia), SIR (TSR produced in Indonesia), STR (TSR produced in Thailand), etc., and natural rubber generally used in this technical field such as RSS (Ribbed Smoked Sheet); modified natural rubbers such as high-purity natural rubber, epoxidized natural rubber, hydroxylated natural rubber, hydrogenated natural rubber, and grafted natural rubber. Among them, from the viewpoints of less quality variation and easy availability, SMR20, STR20, and RSS#1 are preferred. These natural rubbers may be used alone or in combination of two or more.

[0014] (Polyisoprene rubber) As the polyisoprene rubber, for example, Ziegler catalysts such as titanium tetrahalide-trialkylaluminum-based, diethylaluminum chloride-cobalt-based, trialkylaluminum-boron trifluoride-nickel-based, diethylaluminum chloride-nickel-based; lanthanoid-based rare earth metal catalysts such as triethylaluminum-neodymium organic acid-Lewis acid-based; or commercially available polyisoprene rubbers polymerized using an organic alkali metal compound in the same manner as solution-polymerized styrene-butadiene copolymer rubber can be used. A polyisoprene rubber polymerized with a Ziegler catalyst is preferred because of its high cis content. Also, a polyisoprene rubber with an ultra-high cis content obtained using a lanthanoid-based rare earth metal catalyst may be used.

[0015] The vinyl content of the polyisoprene rubber is preferably 50 mol% or less, more preferably 40 mol% or less, and still more preferably 30 mol% or less. If the vinyl content is 50 mol% or less, the holding power of the adhesive composition is less likely to decrease. The lower limit of the vinyl content is not particularly limited. Also, the glass transition temperature of the polyisoprene rubber determined by differential thermal analysis varies depending on the vinyl content, but is preferably -20°C or lower, and more preferably -30°C or lower.

[0016] The weight average molecular weight (Mw) of the polyisoprene rubber is preferably from 90,000 to 2,000,000, and more preferably from 150,000 to 1,500,000. When Mw is within the above range, the molding processability and mechanical strength are good.

[0017] The polyisoprene rubber may have a branched structure or a polar functional group by using a modifier such as a polyfunctional modifier, for example, tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an alkoxysilane containing an amino group, as long as the effects of the present invention are not impaired.

[0018] (Polybutadiene rubber) As the polybutadiene rubber, for example, Ziegler catalysts such as titanium tetrahalide-trialkylaluminum-based, diethylaluminum chloride-cobalt-based, trialkylaluminum-boron trifluoride-nickel-based, diethylaluminum chloride-nickel-based; lanthanoid rare earth metal catalysts such as triethylaluminum-neodymium organic acid-Lewis acid-based; or commercially available polybutadiene rubbers polymerized using an organic alkali metal compound in the same manner as solution-polymerized styrene-butadiene copolymer rubber can be used. The polybutadiene rubber polymerized by a Ziegler catalyst is preferably high in cis content. Also, a polybutadiene rubber with an ultra-high cis content obtained using a lanthanoid rare earth metal catalyst may be used.

[0019] The vinyl content of the polybutadiene rubber is preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 30 mol% or less. If the vinyl content is 50 mol% or less, the holding power of the adhesive composition is less likely to decrease. The lower limit of the vinyl content is not particularly limited. Also, the glass transition temperature of the polybutadiene rubber determined by differential thermal analysis varies depending on the vinyl content, but is preferably -40°C or lower, more preferably -50°C or lower.

[0020] The weight average molecular weight (Mw) of the polybutadiene rubber is preferably from 90,000 to 2,000,000, more preferably from 150,000 to 1,500,000. When Mw is within the above range, the molding processability and mechanical strength are good.

[0021] As long as the above polybutadiene rubber does not impair the effects of the present invention, a part thereof may have a branched structure or a polar functional group by using a multifunctional modifier such as tin tetrachloride, silicon tetrachloride, an alkoxysilane having an epoxy group in the molecule, or an alkoxysilane containing an amino group.

[0022] (Styrene-butadiene copolymer rubber) 〈Styrene-butadiene random copolymer rubber〉 As the styrene-butadiene copolymer rubber (hereinafter sometimes referred to as "SBR"), an appropriate one can be used according to the use and the like, and a styrene-butadiene random copolymer rubber is preferable. In SBR, the styrene content is not particularly limited as long as the SBR is solid. On the other hand, from the viewpoints of adhesiveness and moldability, the styrene content in SBR is preferably 0.1 to 70% by mass, more preferably 5 to 50% by mass, and still more preferably 15 to 35% by mass. In SBR, the bonding form of the butadiene unit may be either 1,2-bonding or 1,4-bonding. Further, in SBR, the vinyl content is preferably 0.1 to 60 mol%, more preferably 0.1 to 55 mol%. Here, the "vinyl content" means the content of the 1,2-bonding unit in the case of SBR. In addition, the styrene content in SBR and the vinyl content in the present invention 1 can be determined from the 1H-NMR spectrum.

[0023] The weight average molecular weight (Mw) of SBR is preferably 100,000 to 2,500,000, more preferably 150,000 to 2,000,000, and still more preferably 200,000 to 1,500,000. When it is in the above range, moldability and mechanical strength can be compatible.

[0024] The glass transition temperature of SBR determined by differential thermal analysis used in the present invention is preferably -95 to 0 °C, more preferably -95 to -5 °C. By setting the glass transition temperature within the above range, it is possible to suppress an increase in viscosity and make handling easier.

[0025] The SBR that can be used in the present invention is obtained by copolymerizing styrene and butadiene. There is no particular limitation on the production method of SBR, and any of emulsion polymerization method, solution polymerization method, gas phase polymerization method, and bulk polymerization method can be used. Among these production methods, the emulsion polymerization method and the solution polymerization method are preferable.

[0026] Emulsion-polymerized styrene-butadiene copolymer rubber (hereinafter sometimes referred to as "E-SBR") can be produced by a known or known-equivalent ordinary emulsion polymerization method. For example, it can be obtained by emulsifying and dispersing a predetermined amount of styrene and butadiene monomers in the presence of an emulsifier and subjecting them to emulsion polymerization with a radical polymerization initiator.

[0027] Solution-polymerized styrene-butadiene copolymer rubber (hereinafter sometimes referred to as "S-SBR") can be produced by an ordinary solution polymerization method. For example, it can be obtained by polymerizing styrene and butadiene using an active metal capable of anionic polymerization in a solvent, and if desired, in the presence of a polar compound.

[0028] Examples of the solvent include aliphatic hydrocarbons such as n-butane, n-pentane, isopentane, n-hexane, n-heptane, and isooctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; and aromatic hydrocarbons such as benzene and toluene. These solvents are usually preferably used in a range where the monomer concentration is 1 to 50% by mass.

[0029] Examples of the active metal capable of anionic polymerization include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium, and barium; and lanthanoid rare earth metals such as lanthanum and neodymium. Among these active metals, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred. Among the alkali metals, organic alkali metal compounds are preferred.

[0030] Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; polyfunctional organic lithium compounds such as dilithiomethane, 1,4-dithiobutane, 1,4-dithio-2-ethylcyclohexane, and 1,3,5-trilithiobenzene; and sodium naphthalene, potassium naphthalene, and the like. Among them, organic lithium compounds are preferred, and organic monolithium compounds are more preferred. The amount of the organic alkali metal compound used is appropriately determined according to the required molecular weight of the S-SBR. The organic alkali metal compound can also be reacted with a secondary amine such as dibutylamine, dihexylamine, or dibenzylamine and used as an organic alkali metal amide.

[0031] The polar compound is not particularly limited as long as it is usually used in anionic polymerization to adjust the microstructure of the butadiene moiety and the distribution in the copolymer chain of styrene without deactivating the reaction. Examples include ether compounds such as dibutyl ether, tetrahydrofuran, and ethylene glycol diethyl ether; tertiary amines such as tetramethylethylenediamine and trimethylamine; alkali metal alkoxides, phosphine compounds, and the like.

[0032] The temperature of the polymerization reaction is usually in the range of -80 to 150 °C, preferably 0 to 100 °C, and more preferably 30 to 90 °C. The polymerization mode may be either batch or continuous. Further, in order to improve the random copolymerizability of styrene and butadiene, it is preferable to continuously or intermittently supply styrene and butadiene into the reaction solution so that the composition ratio of styrene and butadiene in the polymerization system is within a specific range.

[0033] The polymerization reaction can be terminated by adding alcohols such as methanol and isopropanol as polymerization terminators. After the polymerization reaction is terminated, the polymerization solution can be separated by direct drying, steam stripping, etc. to recover the target S-SBR. Note that before removing the solvent, the polymerization solution and the extender oil may be mixed in advance and recovered as an oil-extended rubber.

[0034] As the above SBR, as long as the effects of the present invention are not impaired, a modified SBR in which a functional group is introduced into the SBR may be used. Examples of the functional group include an amino group, an alkoxysilyl group, a hydroxyl group, an epoxy group, a carboxyl group, and the like.

[0035] Examples of the method for producing the modified SBR include adding a coupling agent such as tin tetrachloride, tetrachlorosilane, dimethyldichlorosilane, dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bis(aminomethyl)cyclohexane, 2,4-tolylene diisocyanate, etc., a polymerization terminal modifier such as 4,4'-bis(diethylamino)benzophenone, N-vinylpyrrolidone, etc., or other modifiers described in JP-A-2011-132298 before adding the polymerization terminator. In this modified SBR, regarding the position of the polymer into which the functional group is introduced, it may be the polymerization terminal or the side chain of the polymer chain.

[0036] 〈Styrene-butadiene-styrene block copolymer rubber〉 In addition to the styrene-butadiene random copolymer rubber, examples of the SBR include styrene-butadiene-styrene block copolymer rubber (hereinafter sometimes referred to as "SBS"). Examples of SBS include "Clayton (registered trademark) D SBS" (trade name) manufactured by Clayton Polymer Co., Ltd., "Tufprene (registered trademark)" (trade name) and "Asaprene (registered trademark) T" (trade name) manufactured by Asahi Kasei Chemicals Corporation, "JSR TR" (trade name) manufactured by JSR Corporation, and the like.

[0037] (Styrene-isoprene copolymer rubber) Examples of the styrene-isoprene copolymer rubber include styrene-isoprene-styrene block copolymer rubber (hereinafter sometimes referred to as "SIS"). Examples of SIS include "Clayton (registered trademark) D SIS" (trade name) manufactured by Clayton Polymer Co., Ltd., "JSR SIS" (trade name) manufactured by JSR Corporation, "Quintac (registered trademark)" (trade name) manufactured by Nippon Zeon Co., Ltd., and the like.

[0038] In addition, the above-mentioned polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene rubber (EPM, EPDM, etc.) and butyl rubber can be used as commercially available products without particular limitation.

[0039] [Liquid farnesene-based rubber (B)] The liquid farnesene-based rubber (B) is a rubber that can be handled in a liquid state. By including the component (B) in the adhesive composition, excellent adhesiveness and bleed-out resistance, and peelability and transferability depending on temperature conditions can be exhibited. The component (B) may be used alone or in combination of two or more.

[0040] 〈Monomer unit (a)〉 The component (B) is a liquid polymer containing a monomer unit (a) derived from farnesene (hereinafter sometimes simply referred to as "monomer unit (a)"). The monomer unit (a) may be a monomer unit derived from α-farnesene, or may be a monomer unit derived from β-farnesene represented by the following formula (I), or may contain a monomer unit derived from α-farnesene and a monomer unit derived from β-farnesene. From the viewpoint of ease of production, the monomer unit (a) preferably contains a monomer unit derived from β-farnesene. The content of the monomer unit derived from β-farnesene is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 100 mol% in the monomer unit (a) from the viewpoint of ease of production, that is, it is further preferred that all of the monomer unit (a) is a monomer unit derived from β-farnesene. The content of the monomer unit (a) in the component (B) is preferably 50% by mass or more, more preferably 55% by mass or more, still more preferably 60% by mass or more from the viewpoint of further improving the adhesiveness and bleed-out resistance, and the peelability and transferability according to temperature conditions. The upper limit of the content of the monomer unit (a) in the component (B) is not particularly limited, and may be 100% by mass, may be 99% by mass or less, may be 90% by mass or less, or may be 80% by mass or less.

[0041]

Chemical formula

[0042] 〈Monomer unit (b)〉 The component (B) may be a liquid copolymer containing the monomer unit (a) and a monomer unit (b) derived from another monomer other than farnesene (hereinafter, sometimes simply referred to as "monomer unit (b)"). When the component (B) is a copolymer of the monomer unit (a) and the monomer unit (b), the content of the monomer unit (b) in the component (B) is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less. In the above case, the lower limit of the content of the monomer unit (b) in the component (B) is not particularly limited, and may be 1% by mass or more, may be 10% by mass or more, or may be 20% by mass or more.

[0043] Examples of monomers other than farnesene that can form such monomer units (b) are not particularly limited as long as they are copolymerizable with farnesene. Examples of monomers other than farnesene include aromatic vinyl compounds, conjugated diene compounds other than farnesene, acrylic acid and its derivatives, methacrylic acid and its derivatives, acrylamide and its derivatives, methacrylamide and its derivatives, and acrylonitrile. These monomers other than farnesene may be used alone or in combination of two or more.

[0044] Examples of the aromatic vinyl compounds include styrene; styrene derivatives such as α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, N,N-diethyl-4-aminoethylstyrene, 4-methoxystyrene, monochlorostyrene, and dichlorostyrene; 1-vinylnaphthalene; 2-vinylnaphthalene; vinylanthracene; and vinylpyridine. Among these, styrene and its derivatives are preferred, and styrene is more preferred. These aromatic vinyl compounds may be used alone or in combination of two or more.

[0045] Examples of the conjugated diene compounds include butadiene, isoprene, 2,3-dimethylbutadiene, 2-phenylbutadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, and chloroprene. Among these, butadiene, isoprene, and myrcene are preferred, and butadiene is more preferred. These conjugated dienes may be used alone or in combination of two or more.

[0046] Examples of the above-mentioned acrylic acid derivatives include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, isobornyl acrylate, dicyclopentenyl oxyethyl acrylate, tetraethylene glycol acrylate, tripropylene glycol acrylate, 4-hydroxybutyl acrylate, 3-hydroxy-1-adamantyl acrylate, tetrahydrofurfuryl acrylate, methoxyethyl acrylate, N,N-dimethylaminoethyl acrylate, etc. These acrylic acid derivatives may be used alone or in combination of two or more.

[0047] Examples of the above-mentioned methacrylic acid derivatives include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentanyl methacrylate, benzyl methacrylate, dicyclopentenyl oxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxy-1-adamantyl methacrylate, tetrahydrofurfuryl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylamide, etc. These methacrylic acid derivatives may be used alone or in combination of two or more.

[0048] Examples of the acrylamide derivative include dimethylacrylamide, acryloylmorpholine, isopropylacrylamide, diethylacrylamide, dimethylaminopropylacrylamide, dimethylaminopropylacrylamide methyl chloride quaternary salt, hydroxyethylacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and the like. These acrylamide derivatives may be used alone or in combination of two or more.

[0049] Examples of the methacrylamide derivative include dimethylmethacrylamide, methacryloylmorpholine, isopropylmethacrylamide, diethylmethacrylamide, dimethylaminopropylmethacrylamide, hydroxyethylmethacrylamide, and the like. These methacrylamide derivatives may be used alone or in combination of two or more.

[0050] Among the monomers other than the above-mentioned farnesene, aromatic vinyl compounds and conjugated diene compounds other than farnesene are preferable, and conjugated diene compounds are more preferable.

[0051] 〈Melting Viscosity〉 The melting viscosity of component (B) measured at 38°C is in the range of 0.1 to 3,000 Pa·s. When the melting viscosity is within the above range, it can be handled as a liquid. When the melting viscosity is less than 0.1 Pa·s, the adhesiveness decreases. When the melting viscosity exceeds 3,000 Pa·s, the viscosity of the adhesive composition increases, and the handleability and coatability deteriorate. From the viewpoints of facilitating the production of the resulting adhesive composition, improving workability, and further improving adhesiveness, the melting viscosity of component (B) measured at 38°C is preferably 0.8 to 2,000 Pa·s, more preferably 10 to 1,000 Pa·s, and still more preferably 10 to 700 Pa·s. When component (B) does not contain monomer unit (b), the melting viscosity may be 10 to 450 Pa·s, 10 to 300 Pa·s, 10 to 200 Pa·s, or 10 to 100 Pa·s. (B) component's melt viscosity is the value measured by the measurement method described in the examples below.

[0052] 〈Maximum peak molecular weight (Mt)〉 When measured by gel permeation chromatography (GPC), the maximum peak molecular weight (Mt) of the (B) component is 3,000 to 200,000. When the maximum peak molecular weight (Mt) of the (B) component is less than 3,000, the bleed-out resistance deteriorates. When the maximum peak molecular weight (Mt) of the (B) component exceeds 200,000, the viscosity of the adhesive composition increases, and the handleability and coatability deteriorate. From the viewpoint of achieving a low viscosity, facilitating the preparation of the adhesive composition, improving workability, further enhancing adhesiveness, and being excellent in molding processability, the Mt of the (B) component is preferably 10,000 or more, more preferably 30,000 or more, still more preferably 40,000 or more, even more preferably 50,000 or more, particularly preferably 60,000 or more, and most preferably 80,000 or more. Also, from the above viewpoint, the Mt of the (B) component is preferably 180,000 or less, more preferably 170,000 or less, and still more preferably 160,000 or less. The Mt of the (B) component may be 150,000 or less, or may be 100,000 or less. In the present invention, the Mt of the (B) component is GPC the maximum peak molecular weight in terms of polystyrene determined from the measurement of

[0053] 〈Amount of catalyst residue〉 The amount of catalyst residue derived from the polymerization catalyst used in the production of the (B) component in the (B) component is preferably 0 to 200 mass ppm, more preferably 0 to 150 mass ppm, still more preferably 0 to 100 mass ppm, even more preferably 0 to 50 mass ppm, particularly preferably 0 to 10 mass ppm, and closer to 0 mass ppm is more preferable, in terms of metal conversion. For example, when an organic alkali metal compound such as an organolithium compound is used as the polymerization catalyst for producing the component (B), the metal serving as the reference for the amount of catalyst residue is an alkali metal such as lithium. When the amount of catalyst residue is within the above range, the pressure-sensitive adhesive composition is excellent in transparency and further excellent in adhesiveness. The amount of catalyst residue can be measured, for example, by using a polarized Zeeman atomic absorption spectrophotometer.

[0054] Examples of the method for setting the amount of catalyst residue within the above specific range include a method of purifying the component (B) after polymerization to sufficiently remove the catalyst residue. As the method for purifying the component (B), washing with water or warm water, an organic solvent typified by methanol or acetone, or supercritical fluid carbon dioxide is preferable. The number of washing times is preferably 1 to 20 times, more preferably 1 to 10 times, from an economic viewpoint. The washing temperature is preferably 20 to 100°C, more preferably 40 to 90°C. Further, before the polymerization reaction, by removing impurities that inhibit polymerization by distillation or an adsorbent and increasing the purity of the monomer before performing the polymerization, the amount of the required polymerization catalyst can be reduced, and thus the amount of catalyst residue can be reduced.

[0055] 〈Weight-average molecular weight (Mw)〉 The weight-average molecular weight (Mw) of the component (B) is preferably in the range of 2,000 to 500,000, more preferably 4,000 to 300,000, still more preferably 6,000 to 200,000, and even more preferably 8,000 to 150,000. When the weight-average molecular weight (Mw) is within the above range, more excellent peelability, fluidity, and moldability can be obtained.

[0056] 〈Molecular weight distribution (Mw / Mn)〉 (B) component has a molecular weight distribution (Mw / Mn) of 1.0 to 1.4. If the molecular weight distribution of (B) component exceeds 1.4, there is a risk of poor bleed-out resistance. From the perspective of reducing the variation in the viscosity of (B) component and exhibiting more excellent adhesiveness, the molecular weight distribution (Mw / Mn) of (B) component is preferably 1.0 to 1.30, more preferably 1.0 to 1.20. The molecular weight distribution (Mw / Mn) of (B) component may be 1.0 to 1.15. (B) component's weight average molecular weight and molecular weight distribution are based on polystyrene conversion determined by GPC measurement according to the method described in the examples below.

[0057] 〈Glass transition temperature〉 (B) component's glass transition temperature (Tg) varies depending on the bonding mode (microstructure) and the content of monomer unit (a) derived from farnesene and other monomer units (b) other than farnesene used as needed, but is preferably -100 to +10 °C, more preferably -100 to 0 °C, and still more preferably -100 to -5 °C. When the glass transition temperature (Tg) of (B) component is within the above range, a flexible polymer can be obtained, and the molding processability and adhesiveness become even more excellent. (B) component's glass transition temperature is determined by differential scanning calorimetry measurement method, and more specifically, it is determined by the method described in the examples below.

[0058] 〈Content〉 In the adhesive composition, the content of (B) component with respect to 100 parts by mass of (A) component is 5 to 250 parts by mass. If the content of (B) component is less than 5 parts by mass, it becomes difficult for the adhesive composition to be excellent in adhesiveness and peelability. If the content of (B) component exceeds 250 parts by mass, there is a risk of causing a decrease in the molding processability of the adhesive composition and bleed-out. From the viewpoint of further improving the adhesiveness, peelability, and transferability of the pressure-sensitive adhesive composition, the content of component (B) relative to 100 parts by mass of component (A) is preferably 8 parts by mass or more, more preferably 10 parts by mass or more. From the viewpoints of the moldability and bleed-out resistance of the pressure-sensitive adhesive composition, the content of component (B) relative to 100 parts by mass of component (A) is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 100 parts by mass or less, and may be 60 parts by mass or less from the viewpoint of bleed-out resistance.

[0059] [Adhesion-imparting resin (C)] As the adhesion-imparting resin (C) used in the pressure-sensitive adhesive composition of the present invention, adhesion-imparting resins conventionally used for pressure-sensitive adhesives can be used without particular limitation. Examples of component (C) include coumarone resins such as coumarone-indene resins; phenolic resins and terpene resins such as p-t-butylphenol-acetylene resins, phenol-formaldehyde resins, terpene-phenol resins, terpene resins, xylene-formaldehyde resins; petroleum hydrocarbon resins such as synthetic polyterpene resins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aliphatic-alicyclic petroleum resins, aliphatic-aromatic hydrocarbon resins, hydrogenated modified alicyclic hydrocarbon resins, hydrogenated alicyclic hydrocarbon resins, hydrocarbon-based tackifying resins, low molecular weight polybutene, low molecular weight atactic polypropylene; rosin esters represented by pentaerythritol ester of rosin and glycerol ester of rosin, hydrogenated rosin, methyl ester of hydrogenated rosin, pentaerythritol ester of polymerized rosin, hydrogenated rosin ester, high melting point ester-based resins, polymerized rosin, special rosin esters, etc. Among these component (C), terpene resins, hydrogenated alicyclic hydrocarbon resins, and rosin-based resins are preferred. These component (C) may be used alone or in combination of two or more.

[0060] In the pressure-sensitive adhesive composition, the content of component (C) with respect to 100 parts by mass of component (A) is 10 to 500 parts by mass. When the content of component (C) is less than 10 parts by mass, sufficient adhesiveness cannot be obtained. When the content of component (C) exceeds 500 parts by mass, there is a possibility that good transferability cannot be obtained. From the viewpoints of the transfer performance and adhesiveness of the pressure-sensitive adhesive composition, the content of component (C) with respect to 100 parts by mass of component (A) is preferably 20 to 400 parts by mass, more preferably 30 to 300 parts by mass, and still more preferably 40 to 200 parts by mass. Further, the content of component (C) with respect to 100 parts by mass of component (A) may be 50 to 150 parts by mass, or may be 60 to 120 parts by mass.

[0061] [Other components] In the present embodiment, the pressure-sensitive adhesive composition may contain other components such as a plasticizer, an antioxidant, a crosslinking agent, a filler, and a heat stabilizer in addition to components (A) to (C).

[0062] From the viewpoint of exhibiting flexibility and facilitating the imparting of adhesiveness, the pressure-sensitive adhesive composition can contain a plasticizer within a range that does not impair the effects of the present invention. Examples of the plasticizer include paraffinic, naphthenic, and aromatic process oils; phthalic acid derivatives such as dioctyl phthalate and dibutyl phthalate; liquid co-oligomers of ethylene and α-olefin; liquid paraffin; polybutene; low molecular weight polyisobutylene; and the like. Among the above plasticizers, from the viewpoint of compatibility with components (A) and (B), paraffinic process oil; liquid co-oligomer of ethylene and α-olefin; liquid paraffin are preferred, and paraffinic process oil is more preferred. These plasticizers may be used alone or in combination of two or more. When adding a plasticizer to the adhesive composition, the content of the plasticizer relative to 100 parts by mass of the component (A) is preferably 1 to 200 parts by mass, more preferably 2 to 100 parts by mass, and still more preferably 5 to 80 parts by mass. When the content of the plasticizer is within the above range, more excellent adhesiveness, bleed-out resistance, and moldability of the adhesive composition are likely to be exhibited. From the viewpoint of further improving the bleed-out resistance, the above content of the plasticizer may be 50 parts by mass or less, may be 25 parts by mass or less, and may be 15 parts by mass or less.

[0063] Examples of the antioxidant include phenolic compounds, sulfur compounds, amine compounds, phosphorus compounds, amine-ketone compounds, and imidazole compounds. These antioxidants may be used alone or in combination of two or more.

[0064] More specifically, as the antioxidant, phenolic compounds such as 2,6-di-t-butyl-4-methylphenol, n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; sulfur compounds such as dilauryl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, pentaerythritol tetrakis(3-laurylthiopropionate); amine compounds such as octylated diphenylamine; phosphorus compounds such as tris(2,4-di-t-butylphenyl)phosphite; amine-ketone compounds such as 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, the reaction product of diphenylamine and acetone, 2,2,4-trimethyl-1,2-dihydroquinoline polymer; imidazole compounds such as 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole; and the like. Among these antioxidants, phenolic compounds are preferred. When an antioxidant is added to the adhesive composition, the content of the antioxidant relative to 100 parts by mass of the component (A) is usually 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass.

[0065] Examples of the crosslinking agent include metal compounds such as ZnO, CaO, PbO, Zn(OH)2, Ca(OH)2, Zn(OOCH3)2, Mg(OOCH3)2, CH3COONa, calcium-cured rosin (e.g., Lime Resin No. 1: manufactured by Arakawa Chemical Industries, Ltd.), zinc-cured rosin (e.g., Zinc Resin No. 3: manufactured by Arakawa Chemical Industries, Ltd.), organic titanates (e.g., tetraisopropyl titanate (TPT), diisopropoxybis(acetylacetonato)titanium, Titanium Bond T-50 (isopropanol solution of titanium-i-propoxyoctylene glycolate): manufactured by Nippon Soda Co., Ltd., etc.); amino compounds such as triethylenetetramine (TETA), tetraethylenepentamine (TEPA), polyethyleneimine (molecular weight: about 250 to 1,800, e.g., Epomin SP series: manufactured by Nippon Shokubai Co., Ltd.), polyamide resin (molecular weight: about 500 to 1,000); epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin; isocyanate compounds such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI, blocked isocyanate, etc. These crosslinking agents may be used alone or in combination of two or more. When a crosslinking agent is added to the adhesive composition, the content of the crosslinking agent relative to 100 parts by mass of the component (A) is usually 0.001 to 15 parts by mass, preferably 0.01 to 10 parts by mass, more preferably 0.01 to 8 parts by mass.

[0066] When epoxy resins, isocyanate compounds, etc. are used as the crosslinking agent, a crosslinking accelerator may be used in addition to these crosslinking agents. When an epoxy resin is used as the crosslinking agent, examples of the crosslinking accelerator include tris(dimethylaminomethyl)phenyl. When an isocyanate compound is used as the crosslinking agent, examples of the crosslinking accelerator include dibutyltin laurate. When a crosslinking accelerator is added to the pressure-sensitive adhesive composition, the content of the crosslinking accelerator relative to 100 parts by mass of the component (A) is usually 0.001 to 10 parts by mass, preferably 0.01 to 7.5 parts by mass, and more preferably 0.01 to 5 parts by mass.

[0067] Examples of the filler include talc, clay, mica, calcium silicate, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, silica, alumina, titanium oxide, iron oxide, zinc oxide, magnesium oxide, and the like. When a filler is added to the pressure-sensitive adhesive composition, the content of the filler per 100 parts by mass of the pressure-sensitive adhesive composition is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.

[0068] Examples of the heat stabilizer include phosphorus-based heat stabilizers, lactone-based heat stabilizers, hydroxyl-based heat stabilizers, and the like. When a heat stabilizer is added to the pressure-sensitive adhesive composition, from the viewpoint of suppressing bleeding from the pressure-sensitive adhesive composition, the content of the heat stabilizer per 100 parts by mass of the pressure-sensitive adhesive composition is preferably 3 parts by mass or less, and more preferably 2 parts by mass or less.

[0069] In addition, in the present embodiment, the pressure-sensitive adhesive composition may further contain other components such as an ultraviolet absorber, a light stabilizer, a flame retardant, a pigment, a colorant, a lubricant, an antistatic agent, a water repellent, a waterproof agent, a hydrophilicity-imparting agent, a conductivity-imparting agent, a heat conductivity-imparting agent, an electromagnetic wave shielding property-imparting agent, a light transmittance adjusting agent, a fluorescent agent, a slidability-imparting agent, a transparency-imparting agent, an antiblocking agent, a metal deactivator, and an antibacterial agent as long as the effects of the present invention are not impaired.

[0070] In the pressure-sensitive adhesive composition in the present embodiment, the solid rubber (A), liquid -shapedThe total content of the arnesene rubber (B) and the tackifier resin (C) is preferably 50% by mass or more, and may be 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more. The upper limit may be 100% by mass, but may also be 99.9% by mass, 99.8% by mass, or 99.5% by mass. In this embodiment further containing a plasticizer, the solid rubber (A), the liquid -shaped The total content of the arnesene rubber (B) and the tackifier resin (C) is preferably 50% by mass or more, and may be 70% by mass or more, 75% by mass or more, or 85% by mass or more. The upper limit may be 99% by mass, 98% by mass, 97% by mass, or 95% by mass.

[0071] [Manufacturing method] The pressure-sensitive adhesive composition of this embodiment can be preferably produced, for example, by dissolving all components of the pressure-sensitive adhesive composition in an organic solvent or the like and then removing the solvent or the like therefrom. Further, the pressure-sensitive adhesive composition can also be produced by mixing all components of the pressure-sensitive adhesive composition using a mixer or the like and then melt-kneading with a single-screw or twin-screw extruder, kneader, or the like. As the mixer, a Henschel mixer, V blender, ribbon blender, tumbler blender, conical blender, or the like can be used.

[0072] [Pressure-sensitive adhesive] The pressure-sensitive adhesive of this embodiment is a pressure-sensitive adhesive using at least a part of the above pressure-sensitive adhesive composition. The pressure-sensitive adhesive of this embodiment can be used, for example, as a solvent-based pressure-sensitive adhesive, hot mer melt type pressure-sensitive adhesive, heat stretch type pressure-sensitive adhesive, or the like. When the adhesive of this embodiment is used as a solvent-based adhesive, as the organic solvent, aliphatic solvents such as ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, t-butanol, s-butanol, acetone, acetylacetone, cyclohexanone, heptane, isopentane, n-hexane, cyclohexane, etc., aromatic solvents such as benzene, toluene, ethylbenzene, etc. can be used.

[0073] When the adhesive of this embodiment is used as a hot mer When used as a hot melt adhesive, as the solid rubber (A), it is preferable to use a styrene-butadiene-styrene block copolymer rubber or a styrene-isoprene-styrene block copolymer rubber. Among them, a styrene-isoprene-styrene block copolymer rubber is more preferable.

[0074] For example, the adhesive composition can be used as an adhesive and applied to a substrate using a roll coater, calender, etc. to produce an adhesive tape or an adhesive sheet. When producing an adhesive tape or an adhesive sheet, the material of the substrate is, for example, polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, vinyl chloride, vinylidene chloride, polystyrene, polyacrylonitrile, acrylic polymers, polyesters, polyurethanes, polyamides, polycarbonates, polyimides, etc. The substrate may be formed from one of these materials or may be formed from two or more of them. Also, the substrate may be formed of a single layer or may be formed of two or more layers. When it consists of two or more layers, it may be formed of two or more different materials. Also, if necessary, the substrate may be subjected to various treatments, such as perforation treatment.

[0075] In addition, the adhesive of this embodiment has excellent adhesiveness and bleed-out resistance, and further exhibits peelability and transferability depending on temperature conditions. That is, depending on the temperature conditions, it is possible to control so that there is no adhesive residue and it can be peeled off or transferred. Therefore, the adhesive of this embodiment is suitable not only for adhesive tapes and adhesive sheets but also for transfer adhesive tapes and transfer adhesive sheets.

Examples

[0076] Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0077] Each component used in the Examples and Comparative Examples is as follows. 〔Solid rubber (A)〕 Natural rubber: RSS#1 Styrene-butadiene copolymer rubber: SBR1500 (manufactured by JSR Corporation, styrene content 23% by mass, vinyl content 15 mol%, weight average molecular weight (Mw) 340,000, glass transition temperature -53°C) 〔Liquid farnesene rubber (B)〕 The polymers described in Production Examples 1 to 5 below were used. However, the polymer (B'-1) of Production Example 4 and the polymer (B-4) of Production Example 5 are for Comparative Examples. 〔Adhesion-imparting resin (C)〕 Terpene resin: YS resin PX1150 (trade name, manufactured by Yasuhara Chemical Co., Ltd.) 〔Plasticizer〕 Process oil: SUNPURE P100 (trade name, manufactured by Nippon Sun Oil Co., Ltd., paraffin-based process oil) 〔Antioxidant〕 Adekastab AO-60 (trade name, manufactured by ADEKA Corporation, hindered phenol-based compound)

[0078] <Production Example> [Purification procedure of farnesene] β-Farnesene (purity 97.6 mass%, manufactured by Amyris Biotechnology) was purified by distillation under a nitrogen atmosphere after purification with 3 Å molecular sieves to remove hydrocarbon impurities such as zingiberene, bisabolene, farnesene epoxide, farnesol isomers, E,E-farnesol, squalene, ergosterol, and several dimers of farnesene, thereby purifying β-farnesene. Subsequently, the above-purified β-farnesene was used for the polymerization in Production Examples 1, 2, and 3.

[0079] [Production Example 1]: Liquid Polyfarnesene (B-1) Into a pressure-resistant container that had been purged with nitrogen and dried, 274 g of cyclohexane as a solvent and 1.2 g of n-butyllithium (17 mass% hexane solution) as a polymerization initiator were charged. After heating to 50°C, while controlling the polymerization temperature to be 50°C under stirring conditions, 272 g of β-farnesene was added at a rate of 10 mL / min and polymerized for 1 hour (polymerization step). Methanol was added to the obtained polymerization reaction solution to obtain a polymerization solution. To this polymerization solution in the pressure-resistant container, warm water at 60°C was added so that the polymerization solution / warm water (volume ratio) = 2 / 1, and after stirring for 30 minutes and then standing for 30 minutes, after confirming that the polymerization solution phase and the aqueous phase were separated, the aqueous phase was removed (hereinafter, this operation is referred to as washing operation (1)). This washing operation (1) was further repeated, and washing operation (1) was performed a total of 4 times. The polymerization solution that had undergone the washing operation was vacuum-dried at 70°C for 12 hours to produce liquid polyfarnesene (B-1).

[0080] [Production Example 2]: Liquid Polyfarnesene-Butadiene Copolymer (B-2) Into a pressure-resistant container that had been purged with nitrogen and dried, 250 g of cyclohexane as a solvent and 2.2 g of sec-butyllithium (10.5 mass% cyclohexane solution) as a polymerization initiator were charged. After heating to 70°C, while controlling the polymerization temperature to be 70°C under stirring conditions, a previously prepared mixed solution of 150 g of β-farnesene and 100 g of butadiene was added at a rate of 10 mL / min and polymerized for 1 hour (polymerization step). Methanol was added to the obtained polymerization reaction solution to obtain a polymerization solution. Thereafter, the washing operation (1) described in Production Example 1 was performed 4 times. The polymerized solution that had undergone the washing operation was vacuum dried at 70°C for 12 hours to produce a liquid polyfarnesene-butadiene copolymer (B-2).

[0081] [Production Example 3]: Liquid polyfarnesene (B-3) Polymerization was carried out in the same polymerization step as in Production Example 1, and methanol was added to the polymerization reaction solution to terminate the polymerization reaction. The polymerization solution obtained by polymerization was vacuum dried at 70°C for 12 hours without washing to produce liquid polyfarnesene (B-3).

[0082] [Production Example 4]: Liquid polyisoprene (B'-1) 250 g of hexane as a solvent and 1.9 g of n-butyllithium (17% by mass hexane solution) as a polymerization initiator were charged into a pressure-resistant container that had been purged with nitrogen and dried. After heating to 70°C, while controlling the polymerization temperature to 70°C under stirring conditions, 250 g of isoprene was added at 10 mL / min and polymerized for 1 hour (polymerization step). Methanol was added to the obtained polymerization reaction solution to obtain a polymerization solution. Thereafter, the washing operation (1) described in Production Example 1 was performed 4 times. The polymerized solution that had undergone the washing operation was vacuum dried at 70°C for 12 hours to produce liquid polyisoprene (B'-1).

[0083] [Production Example 5]: Liquid polyfarnesene (B-4) 274 g of cyclohexane as a solvent and 1.2 g of n-butyllithium (17% by mass hexane solution) as a polymerization initiator were charged into a pressure-resistant container that had been purged with nitrogen and dried. After heating to 50°C, while controlling the polymerization temperature to 50°C under stirring conditions, 272 g of unpurified β-farnesene was added at 10 mL / min and polymerized for 1 hour (polymerization step). Methanol was added to the obtained polymerization reaction solution to obtain a polymerization solution. Thereafter, the washing operation (1) described in Production Example 1 was performed 4 times. The polymer solution that had undergone the washing operation was vacuum-dried at 70 °C for 12 hours to produce liquid polyfarnesene (B-4).

[0084] [Evaluation of Physical Properties (Production Examples 1 to 5)] The polymers obtained in Production Examples 1 to 5 were evaluated for their physical properties according to the methods shown below. The results are shown in Table 1. [Maximum Peak Molecular Weight (Mt) and Molecular Weight Distribution (Mw / Mn)] The Mt and Mw / Mn of the polymers obtained in Production Examples 1 to 5 were determined in terms of the molecular weight in terms of standard polystyrene by GPC (gel permeation chromatography). The measuring apparatus and conditions are as follows. · Apparatus: GPC apparatus "GPC8020" manufactured by Tosoh Corporation · Separation column: "TSKgel G4000HXL" manufactured by Tosoh Corporation · Detector: "RI-8020" manufactured by Tosoh Corporation · Eluent: Tetrahydrofuran · Eluent flow rate: 1.0 mL / min · Sample concentration: 5 mg / 10 mL · Column temperature: 40 °C

[0085] [Amount of Catalyst Residue (Li Residue Amount)] (1) Preparation of Sample Solution etc. Sample solution: 0.5 to 5.0 g of the polymers obtained in Production Examples 1 to 5 were precisely weighed, pretreated with a small amount of concentrated sulfuric acid, placed in a platinum dish, and gradually heated with an electric stove to incinerate. After cooling, 5 mL of 20% (v / v) hydrochloric acid was added, and ultrapure water was further added to make 50 mL, which was used as the sample solution. Standard solution (a) (blank): 5 mL of 20% (v / v) hydrochloric acid was added with ultrapure water to make 50 mL. Standard solution (b) (Li: 0.1 ppm (w / w)): 5 mL of 20% (v / v) hydrochloric acid and 0.005 mL of lithium standard solution (1000 ppm (w / w)) were accurately taken, and ultrapure water was added to make 50 mL. Standard solution (c) (Li: 2.0 ppm (w / w)): 5 mL of 20% (v / v) hydrochloric acid and 0.10 mL of lithium standard solution (1000 ppm (w / w)) were accurately taken, and ultrapure water was added to make 50 mL. Standard solution (d) (Li: 5.0 ppm (w / w)): 5 mL of 20% (v / v) hydrochloric acid and 0.25 mL of lithium standard solution (1000 ppm (w / w)) were accurately taken, and ultrapure water was added to make 50 mL. (2) Measurement method It was determined by the calibration curve method of the atomic absorption spectrometry flame method (flame: air-acetylene (wavelength: 670.8 nm)). The absorbances of the above standard solutions (a), (b), (c) and (d) were measured in this order to create a calibration curve. Next, the absorbance of the sample solution was measured, and the amount of lithium catalyst residue per 1 g of the polymer obtained in Production Examples 1 to 5 was calculated by the following formula. For the measurement of absorbance, a polarized Zeeman atomic absorption spectrophotometer (model "Z-5010", manufactured by Hitachi High-Technologies Corporation) was used. As the lithium standard solution for atomic absorption, a product manufactured by Wako Pure Chemical Industries, Ltd. was used. Amount of catalyst residue [lithium: ppm (w / w)] = [C / sample collection amount (g)] × 50 (However, C = lithium concentration in the measurement solution (ppm (w / w)))

[0086] [Melt viscosity] The melt viscosity at 38 °C of the polymers obtained in Production Examples 1 to 5 was measured with a Brookfield viscometer (manufactured by BROOKFIELD ENGINEERING LABS. INC.).

[0087] [Glass transition temperature (Tg)] 10 mg of the polymer obtained in Production Examples 1 to 5 was placed in an open pan made of aluminum, covered with a lid made of aluminum, and crimped with a sample sealer. A thermogram was measured by differential scanning calorimetry (DSC) under the condition of a heating rate of 10 °C / min, and the value at the peak top of the DSC was taken as the glass transition temperature (Tg). The measuring apparatus and conditions are as follows. [Measuring apparatus and measuring conditions] · Apparatus: Differential scanning calorimeter "DSC6200" manufactured by Seiko Instruments Inc. · Cooling device: Cooling Controller manufactured by Seiko Instruments Inc. · Detection unit: Heat flow rate type · Sample weight: 10 mg · Heating rate: 10 °C / min · Cooling condition: 10 °C / min, isothermally held at -130 °C for 3 minutes after cooling, and then heating was started. · Reference container: Aluminum · Reference weight: 0 mg

[0088]

Table 1

[0089] <Examples 1 to 6 and Comparative Examples 1 to 6> According to the compounding amounts shown in Tables 2 and 3, all the components were put into a beaker, diluted with toluene, and dissolved while stirring. At this time, the amount was adjusted so that the pressure-sensitive adhesive composition was 20% by mass and toluene was 80% by mass, and a pressure-sensitive adhesive composition solution was prepared. The above pressure-sensitive adhesive composition solution was stirred at 300 rpm using a three-one motor until no undissolved residue was visually observed. Next, the above pressure-sensitive adhesive composition solution was applied onto a PET film (base material) using an applicator with a thickness of 0.5 mm, and dried at room temperature for two days to prepare a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed on the base material.

[0090] [Evaluation method] The pressure-sensitive adhesive sheets obtained in the above Examples and Comparative Examples were evaluated for physical properties according to the method shown below. The results are shown in Tables 2 and 3.

[0091] [Adhesiveness and peel mode evaluation] The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 of the above were attached to an adherend (SUS: BA304, stainless steel plate) so that the pressure-sensitive adhesive layer was in contact with the adherend, and the cut pieces with a width of 24 mm were used as samples. Using the above samples, in accordance with JIS Z 0237 (2009), the 180-degree peel strength between the adhesive sheet and the adherend was measured using the following measurement conditions and measuring device, and the adhesive force (23°C (room temperature) and 60°C), peel mode (23°C and 60°C), and transferability of the adhesive layer (60°C) were evaluated. (Measurement Conditions and Measuring Device) Measurement Conditions: Test Temperature: 23°C, 60°C Test Speed: 300 mm / min Test Piece Width: 24 mm Number of Measurements: N = 5 Measurement Displacement: 23°C, 60°C: 50 mm to 150 mm Measuring Device: 23°C: "Universal Material Testing Machine Model 5966" manufactured by Instron 60°C: "Universal Material Testing Machine Model 59R5582" manufactured by Instron

[0092] In the above evaluation, the adhesive force was the average of 5 measurement times. Also, for the peel mode, interfacial peeling and cohesive failure were visually observed. Further, for the transferability of the adhesive layer, whether the adhesive layer remained on the adherend after peeling was visually observed and evaluated based on the following evaluation criteria. (Evaluation Criteria for Transferability of Adhesive Layer) A: 80% or more of the adhesive area was transferred to the adherend. B: More than 1% and less than 80% of the adhesive area was transferred to the adherend. C: 1% or less of the adhesive area was transferred to the adherend (including the case where the adhesive layer could not be visually observed on the adherend).

[0093] 〔Bleed-out Evaluation〕 (1) Migration Property to Copy Paper The pressure-sensitive adhesive sheets obtained in the above Examples 1 to 6 and Comparative Examples 1 to 6 were cut into strips 25 mm wide and 100 mm long, and in an environment of 23 ± 2°C and a relative humidity of 65 ± 15%, they were pressed onto high-quality paper (Kokuyo KB paper) using a 2-kg roller at a speed of about 50 mm / second for one round trip and left for 30 minutes. The pressure-sensitive adhesive sheet with the high-quality paper adhered thereto was left standing in an environment of 23 ± 2°C and a relative humidity of 65 ± 15% for one week, and visual observation was made to see if the components contained in the pressure-sensitive adhesive composition migrated to the high-quality paper from the pressure-sensitive adhesive. In the above visual observation, when a stain was observed on the high-quality paper, it was evaluated that the above components migrated to the high-quality paper and indicated as "Yes", and when no stain was observed on the high-quality paper, it was evaluated that the above components did not migrate to the high-quality paper and indicated as "No". (2) Change in transfer weight to the EPDM sheet For the EPDM sheet (model number EB270N: thickness 2 mm, width 100 mm, length 300 mm), in order to extract the low-molecular materials contained in the above EPDM sheet, it was previously immersed in toluene solvent for 12 hours and then dried at 100°C for 3 hours. During the toluene immersion, it was fixed with a metal weight so that the EPDM sheet did not float. The pressure-sensitive adhesive sheets obtained in the above Examples 1 to 6 and Comparative Examples 1 to 6 were cut into strips 24 mm wide and 50 mm long. The cut pressure-sensitive adhesive sheets were pressed onto the EPDM sheet using a 2-kg roller at a speed of about 50 mm / second for one round trip in an environment of 23 ± 2°C and a relative humidity of 65 ± 15% and left for 30 minutes. Then, the pressure-sensitive adhesive sheet with the EPDM sheet adhered thereto was heated in a gear oven (heating temperature: 50°C) for 15 hours. After heating, the test piece was left standing at 23°C for 1 hour, then the pressure-sensitive adhesive sheet was peeled off, and the weight change of the EPDM sheet was measured to observe whether the components contained in the pressure-sensitive adhesive composition migrated to the EPDM sheet by the weight change (transfer weight change).

[0094] The above transfer weight change was calculated as follows based on the following <Physical property values of the pressure-sensitive adhesive layer>. When assuming that the total amount of the above component (B) (the polymers obtained in Production Examples 1 to 5) and the plasticizer has bled out, the theoretically calculated weight change amount is 11.05 mg in Examples 1 to 3 and Comparative Examples 1 to 3, and 24.03 mg in Examples 4 to 6 and Comparative Examples 4 to 6. The ratio of the actually measured weight change amount value (migration weight change [mg]) of the EPDM sheet to the above theoretically calculated weight change amount was calculated, and the obtained value was taken as the migration weight change [mass%]. <Physical property values of the adhesive layer> Width: 24 mm Length: 50 mm Thickness: 0.5 mm Volume: 600 mm 3 Density: 0.000923 g / mm 3 (Theoretical value) Weight: 0.11076 g (theoretical value) · The above "density" is a theoretical value calculated by weighted average from the compounding amounts of the respective components in the examples and comparative examples. · The above "weight" is the theoretical value after toluene volatilization (volume × density × 0.2 mass%).

[0095] In the above bleed-out evaluation, the "components contained in the adhesive composition" that migrate are presumed to be the component (B) and the plasticizer, and mean the above component (B) and the plasticizer. Further, when either one of the component (B) and the plasticizer is compounded, it means the migration of the above one, and when both are compounded, it means the migration of both.

[0096] [Table 2]

[0097] Examples 1 to 3 were excellent in adhesiveness at 23°C, and the adhesive layer did not remain on the adherend due to interfacial peeling. Further, when the temperature was raised to 60°C and peeled in Examples 1 to 3, cohesive failure occurred and the adhesive layer could be transferred to the adherend. Thus, it can be seen from Table 2 that the adhesive compositions of the examples can exhibit peelability and transferability depending on the temperature conditions. Also, it can be seen from Table 2 that Examples 1 to 3 are excellent in bleed-out resistance. On the other hand, it can be seen that in Comparative Examples 1 and 2, even when the temperature is raised to 60°C and peeled off, interfacial peeling occurs, and it is difficult to exhibit peelability and transferability depending on the temperature conditions. Further, from Table 2, it can be seen that Comparative Examples 1 and 3 are inferior in bleed-out resistance compared to Examples 1 to 3.

[0098]

Table 3

[0099] From Table 3, it can be seen that Examples 4 to 6 are excellent in bleed-out resistance. On the other hand, it can be seen that Comparative Examples 4 to 6 are inferior in bleed-out resistance compared to Examples 4 to 6.

[0100] <Examples 7 to 9> An adhesive sheet was produced by the same method as in Example 1 above according to the compounding amounts shown in Table 4. The above-mentioned [Adhesiveness and Peel Mode Evaluation] was performed on the obtained adhesive sheet. The results are shown in Table 4.

[0101]

Table 4

[0102] From Table 4, in Examples 7 to 9, interfacial peeling occurred at 23°C and no adhesive layer remained on the adherend. Further, when the temperature was raised to 60°C and peeled off, cohesive failure occurred and the adhesive layer could be transferred to the adherend. Thus, it can be seen that in Table 4, the adhesive compositions of the examples exhibit peelability and transferability depending on the temperature conditions.

Industrial Applicability

[0103] The adhesive composition of the present embodiment has excellent adhesiveness and bleed-out resistance, and can control the transfer conditions of the adhesive layer depending on the temperature conditions. Therefore, the adhesive composition and the adhesive of the present embodiment are suitable for adhesive tapes and adhesive sheets, as well as transfer adhesive tapes and transfer adhesive sheets.

Claims

1. Based on 100 parts by mass of at least one solid rubber (A) selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene rubber, and butyl rubber, it contains 10 to 60 parts by mass of a liquid farnesene-based rubber (B) and 60 to 120 parts by mass of a tackifier resin (C), an adhesive composition in which the liquid farnesene-based rubber (B) satisfies the following requirements (I) and (II). (I) The melt viscosity measured at 38°C is in the range of 10 to 700 Pa·s. (II) When measured by gel permeation chromatography (GPC), the maximum peak molecular weight (Mt) is 80,000 to 160,000, and the molecular weight distribution (Mw / Mn) is 1.0 to 1.

30.

2. The adhesive composition according to claim 1, wherein the metal derived from the polymerization catalyst used in the production of the liquid farnesene-based rubber (B) in the liquid farnesene-based rubber (B) is 0 to 200 mass ppm per 1 g of the liquid farnesene-based rubber (B).

3. The adhesive composition according to claim 1, wherein the maximum peak molecular weight (Mt) of the liquid farnesene-based rubber (B) is 60,000 or more.

4. The adhesive composition according to claim 1, wherein the content of the monomer unit (a) derived from farnesene in the liquid farnesene-based rubber (B) is 50% by mass or more.

5. The adhesive composition according to claim 1, further containing 1 to 200 parts by mass of a plasticizer based on 100 parts by mass of the solid rubber (A).

6. The adhesive composition according to claim 1, wherein the solid rubber (A) is natural rubber.

7. The adhesive composition according to claim 1, wherein the solid rubber (A) is at least one selected from the group consisting of polybutadiene rubber and styrene-butadiene copolymer rubber.

8. The adhesive composition according to any one of claims 1 to 4, 6, and 7, further containing at least one selected from plasticizers, anti-aging agents, crosslinking agents, fillers, and heat stabilizers in addition to the components (A) to (C).

9. Based on 100 parts by mass of at least one solid rubber (A) selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene rubber and butyl rubber, it contains 10 to 60 parts by mass of a liquid farnesene-based rubber (B) and 60 to 120 parts by mass of a tackifier resin (C). The liquid farnesene-based rubber (B) satisfies the following requirements (I) and (II), and the adhesive composition includes an adhesive layer. (I) The melt viscosity measured at 38 °C is in the range of 10 to 700 Pa·s. (II) When measured by gel permeation chromatography (GPC), the maximum peak molecular weight (Mt) is 80,000 to 160,000, and the molecular weight distribution (Mw / Mn) is 1.0 to 1.30.

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