Adhesive composition and adhesive tape

Abstract

One purpose of the present invention is to provide a compound which is capable of enhancing the bonding strength of an adhesive composition, especially the bonding strength thereof to an adherend with low polarity. Another purpose of the present invention is to provide: a method for producing this compound; an adhesive composition which contains this compound; and an adhesive tape which has an adhesive layer that contains this adhesive composition. The present invention provides a compound which has a constituent unit (A) that is derived from a monomer (a) having a solvation free energy ∆μ of -30 kcal / mole or less with respect to a polytetrafluoroethylene, and a constituent unit (B) that is derived from at least one monomer (b) selected from the group consisting of terpene monomers, vinyl monomers and conjugated diene monomers.

Description

[Technical Field]

[0001] The present invention relates to a compound that can be used in a pressure-sensitive adhesive composition. The present invention also relates to a method for producing the compound, a pressure-sensitive adhesive composition containing the compound, and a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition. [Background technology]

[0002] Conventionally, adhesive tapes have been widely used to fix components in electronic devices. Specifically, adhesive tapes are used, for example, to adhere a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to adhere a touch panel module to a display panel module. Adhesive tapes used to fix such electronic device components are required to have not only high adhesiveness but also functions such as heat resistance, thermal conductivity, and impact resistance depending on the environment of the location where they are used (e.g., Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-052050 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-021067 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-120876 Summary of the Invention [Problem to be solved by the invention]

[0004] PSA compositions in which a tackifier resin is added to a base polymer for the purpose of improving adhesiveness are known. The tackifier resin usually improves adhesive strength by changing the bulk mechanical properties, surface polarity, etc. of the base polymer.

[0005] In recent years, the applications of pressure-sensitive adhesive tapes have expanded, and higher performance is required of pressure-sensitive adhesive compositions. For example, pressure-sensitive adhesive tapes used to fix electronic components have become thinner, and they are required to have high adhesive strength even when they are thinner. In addition, the types of adherends have become more diverse, and more difficult-to-adhere adherends, i.e., adherends with relatively low polarity, such as adherends made of polyolefin resins, are now being used. In such cases, a problem may arise in which conventional pressure-sensitive adhesive compositions are unable to provide sufficient adhesive strength.

[0006] An object of the present invention is to provide a compound that can increase the adhesive strength of a pressure-sensitive adhesive composition, particularly to an adherend with low polarity. Another object of the present invention is to provide a method for producing the compound, a pressure-sensitive adhesive composition containing the compound, and a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition. [Means for solving the problem]

[0007] The present invention relates to a compound having a structural unit (A) derived from a monomer (a) having a solvation free energy Δμ with polytetrafluoroethylene of −30 kcal / mol or less, and a structural unit (B) derived from at least one monomer (b) selected from the group consisting of a terpene monomer, a vinyl monomer, and a conjugated diene monomer. The present invention is described in detail below.

[0008] The present inventors have succeeded in producing a novel compound having a structural unit (A) derived from a monomer (a) having a solvation free energy Δμ with polytetrafluoroethylene of a certain value or less, and a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers, vinyl monomers, and conjugated diene monomers. The present inventors have discovered that by incorporating such a compound as a tackifying resin into a pressure-sensitive adhesive composition, the adhesive strength of the pressure-sensitive adhesive composition can be increased, and in particular, the adhesive strength can be increased even to adherends with low polarity, leading to the completion of the present invention.

[0009] The compound of the present invention has a structural unit (A) derived from a monomer (a) having a solvation free energy Δμ with polytetrafluoroethylene of −30 kcal / mol or less. Hereinafter, polytetrafluoroethylene will also be referred to as “PTFE.” By containing such a structural unit (A), the compound of the present invention can increase the adhesive strength of the pressure-sensitive adhesive composition, and in particular, can significantly improve the interaction with adherends having low polarity, thereby increasing the adhesive strength even to adherends having low polarity. For this reason, the compound of the present invention is suitably used as a tackifying resin to be blended in a pressure-sensitive adhesive composition. Here, the solvation free energy Δμ with polytetrafluoroethylene refers to the change in standard free energy when polytetrafluoroethylene is brought into contact with monomer (a). Therefore, the smaller the solvation free energy Δμ, the stronger the interaction between polytetrafluoroethylene and monomer (a). Furthermore, polytetrafluoroethylene is known to be one of the least polar adherends, and it is thought that strong interaction with such an adherend can greatly improve interaction with all low-polarity adherends. From the above, it is thought that the compound of the present invention can increase adhesive strength to a wide range of low-polarity adherends by having a structural unit (A) derived from monomer (a) whose solvation free energy Δμ with polytetrafluoroethylene is below a certain value.

[0010] The solvation free energy Δμ of the monomer (a) with polytetrafluoroethylene is not particularly limited as long as it is −30 kcal / mol or less, but is preferably −40 kcal / mol or less, more preferably −50 kcal / mol or less, and even more preferably −60 kcal / mol or less. The lower limit of the solvation free energy Δμ of the monomer (a) with polytetrafluoroethylene is not particularly limited, but the substantial lower limit is −300 kcal / mol, preferably −200 kcal / mol, and more preferably −100 kcal / mol.

[0011] The solvation free energy Δμ of monomer (a) with polytetrafluoroethylene can be calculated using molecular dynamics. The specific calculation procedure involves 1) molecular modeling, 2) charge setting, 3) creating a calculation system, 4) molecular dynamics calculation, and 5) calculating the solvation free energy Δμ using the energy representation method.

[0012] 1) Molecular modeling The chemical structures of PTFE and monomer (a) are drawn using molecular modeling software (CrossAbility's Winmostar (ver. 10) or equivalent). At this time, the base material PTFE is considered to be a crystal, and the atomic positions are determined according to the following reference 1. Reference 1: A crystal structure of ultra-dispersed form of polytetrafluoroethylene based on X-ray powder diffraction data, Powder Diffr., Vol. 19, No. 3, September 2004.

[0013] 2) Electric charge setting Calculate the charge of the drawn molecular model as follows: For monomer (a), the RESP charge is calculated using quantum chemistry calculation software (GAMESS (ver. 2018 R1) or equivalent, manufactured by the Gordon Research Group at Iowa State University) through density functional calculations (conditions: functional B3LYP / basis set 6-31G**). For the base material PTFE, an SCF calculation is performed using first-principles calculation software (Quantum ESPRESSO Foundation, Quantum ESPRESSO, or an equivalent product) to calculate the Lowdin charge. The SCF calculation is performed under the following conditions. &system ibrav = 0, nat = 45, nspin = 1, ntyp = 2, ecutwfc = 25., ecutrho = 225., occupations = 'fixed', nosym = .False., noinv = .False., tot_charge = 0., &electrons conv_thr = 1d-6, mixing_beta = 0.3, mixing_mode = 'plain', electron_maxstep = 100, diagonalization = 'david', ATOMIC_SPECIES C 12.011 C.pbe-rrkjus.UPF F 18.9984 F.pbe-n-van.UPF

[0014] 3) Creation of a calculation system For the PTFE molecular model created, a heptamer was used as the basic cell, and 10, 3, and 3 basic cells were arranged in the x-, y-, and z-axis directions, respectively. After that, excess atoms were removed to create a PTFE crystal system with a total of 90 PTFE heptamers. The z-axis direction is the polymer extension direction. A vacuum layer is inserted into the PTFE crystal system, and a model of monomer (a) is placed on the outermost surface of the PTFE XZ plane. At this time, the model of monomer (a) is placed so that the closest distance from the outermost atom of PTFE is 3 Å. For the system used in the calculation of monomer (a) alone (described below), a cube made of a vacuum layer with a cell size of 999 nm on one side is created, and one monomer (a) is placed inside the cube to create the system.

[0015] 4) Molecular dynamics calculation Molecular dynamics calculations (MD calculations) are performed using software (GROMACS (ver. 5.0.7) or equivalent, manufactured by the University of Groningen). The Dreiding force field is used, and energy minimization calculations, equilibration MD calculations, and main calculations are performed to calculate the coordinates, velocities, and energy of each molecular model. MD calculations are performed under the following calculation conditions for three types of systems: the interface system between monomer (a) and PTFE created in 3) System Creation, monomer (a) only, and PTFE crystal system only. [1] In the case of a system consisting only of PTFE crystals and an interface system between monomer (a) and PTFE Step 1: Energy minimization calculation Conditions: Integrator=steep, Emtol=100.0KJ / mol / nm Step2 Equilibration MD calculation Conditions: NVT ensemble (nose-hoover method), temperature: 300K, calculation time: 2000 (ps), Time step dt: 1fs Step3 Main calculation Conditions: NVT ensemble (nose-hoover method), temperature: 300K, calculation time: 500 (ps) Time step dt: 1fs [2] Monomer (a) only system Step 1: Energy minimization calculation Conditions: Integrator=steep, Emtol=100.0KJ / mol / nm Step2 Equilibration MD calculation Conditions: NVT ensemble (nose-hoover method), temperature: 300K, calculation time: 10 (ps) Time step dt: 1fs Step3 Main calculation Conditions: NVT ensemble (nose-hoover method), temperature: 300K, calculation time: 25000 (ps) Time step dt: 1fs

[0016] 5) Calculation of solvation free energy Δμ using the energy representation method For each of the monomer (a) only, the PTFE crystal system only, and the interface system between monomer (a) and PTFE, the solvation free energy Δμ is calculated using the energy representation method using the data obtained from 4) molecular dynamics calculations. The calculation software used is ERmod (ver. 0.3.6) (or equivalent) from the Matsubayashi Laboratory at Osaka University. In 3) creating the system, the PTFE and monomer (a) are arranged in multiple initial configurations, and calculations are performed for each, with the solvation free energy Δμ being calculated as the statistical average.

[0017] The compound of the present invention may have the structural unit (A) in a side chain, or in the main chain skeleton or at an end of the main chain skeleton. In particular, it is preferable that the compound of the present invention have the structural unit (A) in the main chain skeleton or at an end of the main chain skeleton, since this will allow the compound to have suitable physical properties required when used as a tackifying resin.

[0018] Specifically, the structural unit (A) is preferably at least one selected from the group consisting of structural units (A-1) and (A-1′) represented by the following formulas.

[0019] [ka]

[0020] In the formula, R 1 respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group, n represents an integer of 2 or more and 4 or less, and n' represents an integer of 2 or more and 5 or less. Note that * represents a linking portion.

[0021] In the structural unit (A-1) and the structural unit (A-1′), R 1 respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. The aliphatic hydrocarbon group is not particularly limited, and examples thereof include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms. The aromatic hydrocarbon group is not particularly limited, and examples thereof include substituted or unsubstituted aryl groups having 1 to 20 carbon atoms. The polar functional group is not particularly limited, and examples thereof include an amino group, a carboxyl group, a carbonyl group, an alkoxy group, a hydroxyl group, a nitrile group, and a nitro group. The aliphatic hydrocarbon group having the polar functional group is not particularly limited, and for example, a group in which one or more hydrogen atoms in the aliphatic hydrocarbon group described above have been substituted with the polar functional group described above can be used. The aromatic hydrocarbon group having the polar functional group is also not particularly limited, and for example, a group in which one or more hydrogen atoms in the aromatic hydrocarbon group described above have been substituted with the polar functional group described above can be used. In the compound of the present invention, multiple R 1 may be the same or different. 1 Similarly, the multiple R groups contained in one structural unit (A-1′) may be the same or different. 1 may be the same or different. 1 may be the same or different.

[0022] In the structural unit (A-1) and the structural unit (A-1'), n is an integer of 2 or more and 4 or less, and n' is an integer of 2 or more and 5 or less, but from the viewpoint of ease of availability of raw materials, it is preferable that n and n' are 2 or 3. It is more preferable that n and n' are 3, as this allows for further increasing the adhesive strength of the pressure-sensitive adhesive composition, and in particular allows for further increasing the adhesive strength even to adherends with low polarity.

[0023] More specific examples of the structural unit (A-1) and the structural unit (A-1') include a structural unit derived from dihydroxybenzene or a derivative thereof (when n and n' are 2), and a structural unit derived from trihydroxybenzene or a derivative thereof (when n and n' are 3). These structural units may be used alone, or two or more types may be used in combination. The dihydroxybenzene or its derivative is not particularly limited, and examples thereof include resorcinol, pyrocatechol, hydroquinone, dihydroxytoluene, dihydroxyxylene, dihydroxyphenylethylamine hydrochloride, dihydroxybenzoic acid, dihydroxyphenylacetic acid, dihydroxyhydrocinnamic acid, dihydroxyphenylpropionic acid, dihydroxyphenylalanine, dihydroxybenzaldehyde, dihydroxyacetophenone, diacetyldihydroxybenzene, dihydroxyphenyl-2-butanone, dihydroxyphenylmethyl acetate, benzyl dihydroxyphenyl ketone, dihydroxybenzamide, dihydroxymethoxybenzene, dihydroxybenzyl alcohol, dihydroxyphenylethanol, dihydroxyphenyl glycol, dihydroxyphenylacetonitrile, and dihydroxynitrobenzene. These dihydroxybenzenes or their derivatives may be used alone or in combination of two or more. Among them, pyrocatechol is preferred because it has little steric hindrance and easily interacts with the adherend. The trihydroxybenzene or its derivative is not particularly limited, and examples thereof include pyrogallol, 1,2,4-trihydroxybenzene, phloroglucinol, trihydroxytoluene, trihydroxydiphenylmethane, 6-hydroxy-L-dopa, gallic acid, methyl gallate, butyl gallate, isobutyl gallate, isoamyl gallate, hexadecyl gallate, stearyl gallate, trihydroxyacetophenone, trihydroxyphenylethanone, trihydroxyphenylbutanone, trihydroxybenzaldehyde, trihydroxybenzamide, and trihydroxynitrobenzene. These trihydroxybenzenes or their derivatives may be used alone or in combination. Among them, pyrogallol is preferred because it has little steric hindrance and easily interacts with the adherend.

[0024] Furthermore, the structural unit (A) is preferably at least one selected from the group consisting of structural units (A-2), (A-2'), (A-3), (A-3'), (A-4) and (A-4') represented by the following formulas:

[0025] [ka]

[0026] [ka]

[0027] [ka]

[0028] In the formula, R 2 , R 3 and R 5 R represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. 4R represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. 6 and R 7 represents a hydrogen atom or an aliphatic hydrocarbon group. m represents an integer of 1 or more and 4 or less, and m' represents an integer of 1 or more and 5 or less. l represents an integer of 2 or more and 4 or less, and l' represents an integer of 2 or more and 5 or less. k represents an integer of 1 or more and 4 or less, and k' represents an integer of 1 or more and 5 or less. * represents a linking portion.

[0029] In the structural unit (A-2) and the structural unit (A-2′), R 2 respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. The aliphatic hydrocarbon group is not particularly limited, and examples thereof include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms. The aromatic hydrocarbon group is not particularly limited, and examples thereof include substituted or unsubstituted aryl groups having 1 to 20 carbon atoms. The polar functional group is not particularly limited, and examples thereof include an amino group, a carbonyl group, an alkoxy group, a hydroxyl group, a nitrile group, and a nitro group. The aliphatic hydrocarbon group having the polar functional group is not particularly limited, and for example, a group in which one or more hydrogen atoms in the aliphatic hydrocarbon group described above have been substituted with the polar functional group described above can be used. The aromatic hydrocarbon group having the polar functional group is also not particularly limited, and for example, a group in which one or more hydrogen atoms in the aromatic hydrocarbon group described above have been substituted with the polar functional group described above can be used. In the compound of the present invention, multiple R 2 may be the same or different. 2 Similarly, the multiple R 2may be the same or different. 2 may be the same or different.

[0030] In the structural unit (A-2) and the structural unit (A-2'), m is an integer of 1 or more and 4 or less, and m' is an integer of 1 or more and 5 or less, but from the viewpoint of ease of availability of raw materials, it is preferable that m and m' are 1 or 2. It is more preferable that m and m' are 1, as this allows for further increasing the adhesive strength of the pressure-sensitive adhesive composition, and in particular allows for further increasing the adhesive strength even to adherends with low polarity.

[0031] More specifically, examples of the structural unit (A-2) and the structural unit (A-2') include structural units derived from benzoic acid, salicylic acid, dihydroxybenzoic acid, gallic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, 2-ethylbenzoic acid, 3-ethylbenzoic acid, 4-ethylbenzoic acid, 4-tert-butylbenzoic acid, 2-vinylbenzoic acid, 3-vinylbenzoic acid, 4-vinylbenzoic acid, and derivatives thereof. These structural units may be used alone or in combination of two or more. Among these, 4-vinylbenzoic acid is preferred because it has little steric hindrance and easily interacts with the adherend.

[0032] In the structural unit (A-3) and the structural unit (A-3′), R 3 respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. The aliphatic hydrocarbon group is not particularly limited, and examples thereof include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms. The aromatic hydrocarbon group is not particularly limited, and examples thereof include substituted or unsubstituted aryl groups having 1 to 20 carbon atoms. The polar functional group is not particularly limited, and examples thereof include an amino group, a carboxyl group, a carbonyl group, a hydroxyl group, a nitrile group, and a nitro group. The aliphatic hydrocarbon group having the polar functional group is not particularly limited, and for example, a group in which one or more hydrogen atoms in the aliphatic hydrocarbon group described above have been substituted with the polar functional group described above can be used. The aromatic hydrocarbon group having the polar functional group is also not particularly limited, and for example, a group in which one or more hydrogen atoms in the aromatic hydrocarbon group described above have been substituted with the polar functional group described above can be used. In the compound of the present invention, multiple R 3 may be the same or different. 3 Similarly, the multiple R groups contained in one structural unit (A-3′) may be the same or different. 3 may be the same or different. 3 may be the same or different.

[0033] In the structural unit (A-3) and the structural unit (A-3′), R 4 respectively represent an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. The aliphatic hydrocarbon group is not particularly limited, and examples thereof include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms. The aromatic hydrocarbon group is not particularly limited, and examples thereof include substituted or unsubstituted aryl groups having 1 to 20 carbon atoms. In the compound of the present invention, multiple R groups contained in one structural unit (A-3) may be used. 4 may be the same or different. 4 Similarly, the multiple R groups contained in one structural unit (A-3′) may be the same or different. 4 may be the same or different. 4may be the same or different.

[0034] In the structural unit (A-3) and the structural unit (A-3'), l is an integer of 2 or more and 4 or less, and l' is not particularly limited as long as it is an integer of 2 or more and 5 or less, but from the viewpoint of ease of availability of raw materials, it is preferable that l and l' are 2 or 3. It is more preferable that l and l' are 3, as this allows for further increasing the adhesive strength of the pressure-sensitive adhesive composition, and in particular allows for further increasing the adhesive strength even to adherends with low polarity.

[0035] More specifically, examples of the structural unit (A-3) and the structural unit (A-3') include structural units derived from trialkoxybenzene or its derivatives (when l is 3). The trialkoxybenzene or its derivative is not particularly limited, and examples include 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, and 1,3,5-trimethoxybenzene. These trialkoxybenzenes or their derivatives may be used alone or in combination of two or more. Among these, 1,2,3-trimethoxybenzene is preferred because it has little steric hindrance and easily interacts with the adherend.

[0036] In the structural unit (A-4) and the structural unit (A-4′), R 5 respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. The aliphatic hydrocarbon group is not particularly limited, and examples thereof include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms. The aromatic hydrocarbon group is not particularly limited, and examples thereof include substituted or unsubstituted aryl groups having 1 to 20 carbon atoms. The polar functional group is not particularly limited, and examples thereof include a carboxyl group, a carbonyl group, an alkoxy group, a hydroxyl group, a nitrile group, and a nitro group. The aliphatic hydrocarbon group having the polar functional group is not particularly limited, and for example, a group in which one or more hydrogen atoms in the aliphatic hydrocarbon group described above have been substituted with the polar functional group described above can be used. The aromatic hydrocarbon group having the polar functional group is also not particularly limited, and for example, a group in which one or more hydrogen atoms in the aromatic hydrocarbon group described above have been substituted with the polar functional group described above can be used. In the compound of the present invention, multiple R 5 may be the same or different. 5 Similarly, the multiple R groups contained in one structural unit (A-4′) may be the same or different. 5 may be the same or different. 5 may be the same or different.

[0037] In the structural unit (A-4) and the structural unit (A-4′), R 6 and R 7 represents a hydrogen atom or an aliphatic hydrocarbon group. The aliphatic hydrocarbon group is not particularly limited, and examples thereof include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms. In the compound of the present invention, multiple R 6 and R 7 may be the same or different. 6 and R 7 Similarly, the multiple R groups contained in one structural unit (A-4′) may be the same or different. 6 and R 7 may be the same or different. 6 and R 7 may be the same or different.

[0038] In the structural unit (A-4) and the structural unit (A-4'), k is an integer of 1 or more and 4 or less, and k' is an integer of 1 or more and 5 or less, but from the viewpoint of ease of availability of raw materials, it is preferable that k and k' are 1, 2, or 3. It is more preferable that k and k' are 1, as this allows for a further increase in the adhesive strength of the pressure-sensitive adhesive composition, and in particular, allows for a further increase in adhesive strength even to adherends with low polarity.

[0039] More specifically, examples of the structural unit (A-4) and the structural unit (A-4') include structural units derived from aminobenzene or derivatives thereof (when k is 1). The aminobenzene or derivatives thereof are not particularly limited, and examples include aniline, methylaniline, ethylaniline, dimethylaniline, diethylaniline, etc. These aminobenzenes or derivatives thereof may be used alone or in combination of two or more.

[0040] The structural unit (A) may consist solely of petroleum-derived materials, but preferably contains a biologically-derived material. The depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products are becoming increasingly problematic. Therefore, attempts have been made to conserve petroleum resources by using biologically-derived materials instead of petroleum-derived materials. It is preferable for the structural unit (A) to contain a biologically-derived material from the perspective of conserving petroleum resources. Furthermore, if the structural unit (A) contains a biologically-derived material, since biologically-derived materials are originally produced by absorbing carbon dioxide from the atmosphere, it is believed that burning it will not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the perspective of reducing carbon dioxide emissions. Examples of monomers that constitute the structural unit (A) containing a biological material include resorcinol, dihydroxyphenylethylamine hydrochloride, dihydroxyhydrocinnamic acid, dihydroxyphenylalanine, dihydroxybenzaldehyde, dihydroxybenzyl alcohol, pyrogallol, 1,2,4-trihydroxybenzene, phloroglucinol, 6-hydroxy-L-dopa, gallic acid, methyl gallate, butyl gallate, isobutyl gallate, isoamyl gallate, hexadecyl gallate, stearyl gallate, trihydroxyacetophenone, trihydroxybenzaldehyde, trihydroxybenzamide, and trihydroxynitrobenzene.

[0041] The content of the structural unit (A) in the compound of the present invention is not particularly limited, but a preferred lower limit is 1 mol% and a preferred upper limit is 60 mol%. When the content of the structural unit (A) is 1 mol% or more, blending the compound in a pressure-sensitive adhesive composition can further increase the adhesive strength of the pressure-sensitive adhesive composition, and can particularly increase the adhesive strength to adherends with low polarity. When the content of the structural unit (A) is 60 mol% or less, the compound can have suitable physical properties required when used as a tackifying resin. A more preferred lower limit of the content of the structural unit (A) is 5 mol%, a more preferred upper limit is 50 mol%, an even more preferred lower limit is 10 mol%, and an even more preferred upper limit is 30 mol%.

[0042] The compound of the present invention has a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers, vinyl monomers, and conjugated diene monomers. That is, the compound of the present invention has, in addition to the structural unit (A), a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers, vinyl monomers, and conjugated diene monomers. By having the structural unit (B), the compound can have suitable physical properties required when used as a tackifier resin. Among these, constituent units derived from terpene monomers or constituent units derived from vinyl monomers are preferred because blending a compound into a pressure-sensitive adhesive composition can further increase the adhesive strength of the pressure-sensitive adhesive composition, and it is also preferred to use a constituent unit derived from a terpene monomer and a constituent unit derived from a vinyl monomer in combination. Furthermore, from the viewpoint of improving the compatibility between the compound and the base polymer, particularly the compatibility between the compound and a styrene-based elastomer, constituent units derived from terpene monomers or constituent units derived from conjugated diene monomers are preferred. Because these constituent units have an aliphatic hydrocarbon group with an unsaturated double bond, the presence of these constituent units in the compound improves the compatibility between the compound and the base polymer, particularly the compatibility between the compound and a styrene-based elastomer, and can prevent a decrease in the adhesive strength of the pressure-sensitive adhesive composition due to poor compatibility.

[0043] The terpene monomer is not particularly limited, and examples thereof include α-pinene, β-pinene, limonene, dipentene, δ-3-carene, dimethyloctatriene, alloocimene, myrcene, ocimene, linalool, cosmene, etc. Among these, α-pinene, β-pinene, or limonene is preferred because blending such a compound in the pressure-sensitive adhesive composition can further increase the adhesive strength of the pressure-sensitive adhesive composition. The vinyl monomer is not particularly limited, but from the viewpoint of improving the compatibility between the compound and the base polymer, particularly the compatibility between the compound and the acrylic polymer, a vinyl monomer that does not have a structure containing two or more aromatic rings in one molecule (e.g., a naphthalene structure, an anthracene structure, a biphenyl structure, an anthraquinone structure, a benzophenone structure, etc.) is preferred. Examples of the vinyl monomer that does not have a structure containing two or more aromatic rings in one molecule include ethylene, propylene, butylene, hexene, vinyl acetate, vinyl chloride, styrene, α-methylstyrene, coumarone, indene, vinyltoluene, divinylbenzene, divinyltoluene, and 2-phenyl-2-butene. Among these, styrene is preferred because the adhesive strength of the pressure-sensitive adhesive composition can be further increased by incorporating the compound into the pressure-sensitive adhesive composition. The conjugated diene monomer is not particularly limited, and examples thereof include butadiene, isoprene, piperylene, cyclopentadiene, etc. Among these, isoprene is preferred because blending the compound in the pressure-sensitive adhesive composition can further increase the adhesive strength of the pressure-sensitive adhesive composition. These monomers (b) may be used alone or in combination of two or more.

[0044] The structural unit (B) may consist solely of petroleum-derived materials, but preferably contains a biologically-derived material. The depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products are becoming increasingly problematic. Therefore, attempts have been made to conserve petroleum resources by using biologically-derived materials instead of petroleum-derived materials. It is preferable for the structural unit (B) to contain a biologically-derived material from the perspective of conserving petroleum resources. Furthermore, if the structural unit (B) contains a biologically-derived material, since biologically-derived materials are originally produced by absorbing carbon dioxide from the atmosphere, it is believed that burning this material will not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the perspective of reducing carbon dioxide emissions. Examples of the monomer (b) constituting the structural unit (B) containing a biological material include terpene monomers, ethylene, propylene, hexene, butadiene, and isoprene.

[0045] The content of the structural unit (B) in the compound of the present invention is not particularly limited, but a preferred lower limit is 40 mol% and a preferred upper limit is 99 mol%. When the content of the structural unit (B) is 40 mol% or more, the compound can have suitable physical properties required when used as a tackifier resin. When the content of the structural unit (B) is 99 mol% or less, the content of the structural unit (A) can be sufficiently ensured, so that by incorporating the compound into a pressure-sensitive adhesive composition, the adhesive strength of the pressure-sensitive adhesive composition can be further increased, and in particular, the adhesive strength can be further increased even to adherends with low polarity. A more preferred lower limit of the content of the structural unit (B) is 50 mol%, and a more preferred upper limit is 90 mol%.

[0046] The compound of the present invention is not particularly limited as long as it is a compound having the above-mentioned structural unit (A) and the above-mentioned structural unit (B), but is preferably a copolymer having a structure represented by the following formula: A copolymer having such a structure is a copolymer obtained by a method using cationic polymerization as described below, and can further increase the adhesive strength of the pressure-sensitive adhesive composition, and in particular can further increase the adhesive strength even to adherends with low polarity.

[0047] [ka]

[0048] In the formula, A represents the structural unit (A), B represents the structural unit (B), and s and t each represent an integer of 1 or greater. Note that * represents a linking moiety.

[0049] The compound of the present invention is not particularly limited as long as it is a compound having the above-mentioned structural unit (A) and the above-mentioned structural unit (B), but is preferably a copolymer having the above-mentioned structural unit (A) and the above-mentioned structural unit (B), and may further contain other structural units. When it is a copolymer, the above-mentioned structural unit (A) and the above-mentioned structural unit (B) may be copolymerized randomly, or may be copolymerized with regularity or periodicity, for example, when each of them forms a block segment and then the block segments are bonded to each other.

[0050] The compound of the present invention preferably has an aliphatic hydrocarbon group having an unsaturated double bond. The compound of the present invention may have the aliphatic hydrocarbon group having an unsaturated double bond in the structural unit (A) or the structural unit (B), or in another structural unit. Among these, from the viewpoints of ease of synthesis and improving the compatibility of the compound with the base polymer, particularly the compatibility of the compound with a styrene-based elastomer, it is preferable for the aliphatic hydrocarbon group having an unsaturated double bond to be present in the structural unit (B) or another structural unit. While the structural unit (B) or other structural unit having the aliphatic hydrocarbon group having an unsaturated double bond is not particularly limited, a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and conjugated diene monomers is preferred. That is, the compound of the present invention preferably has the aliphatic hydrocarbon group having an unsaturated double bond in the structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and conjugated diene monomers. Among these, it is preferable that the compound be contained in a structural unit derived from a terpene monomer, since the adhesive strength of the pressure-sensitive adhesive composition can be further increased by blending the compound in the pressure-sensitive adhesive composition.

[0051] Furthermore, examples of the other structural units include structural units derived from other phenolic monomers not included in the structural units (A) above, and structural units derived from maleic anhydride. The other phenolic monomer is not particularly limited, and examples thereof include phenol, cresol, xylenol, propylphenol, norylphenol, methoxyphenol, bromophenol, bisphenol A, bisphenol F, bisphenol S, dihydroxynaphthalene, etc. These other phenolic monomers may be used alone or in combination of two or more.

[0052] The molecular weight of the compound of the present invention is not particularly limited, but the preferred lower limit of the weight average molecular weight (Mw) is 400, and the preferred upper limit is 10,000. If the weight average molecular weight (Mw) is within the above range, the compound can have suitable physical properties required when used as a tackifier resin. The more preferred lower limit of the weight average molecular weight (Mw) is 500, and the more preferred upper limit is 5,000, and the even more preferred lower limit is 700, and the even more preferred upper limit is 3,000. The weight average molecular weight (Mw) can be adjusted to fall within the above range by adjusting, for example, the compound composition, polymerization method, polymerization conditions, and the like.

[0053] The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) described below can be measured by the following method. The compound solution is filtered through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm). The resulting filtrate is fed to a gel permeation chromatograph (e.g., Waters, 2690 Separations Model) and subjected to GPC measurement at a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-equivalent molecular weight of the compound is measured, and the weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) are determined. For example, a GPC KF-802.5L (Showa Denko) is used as the column, and a differential refractometer is used as the detector.

[0054] Although the Young's modulus of the compound of the present invention is not particularly limited, a preferred lower limit of the Young's modulus at 25°C is 10 MPa. If the Young's modulus at 25°C is 10 MPa or more, the compound has an appropriate hardness and can have suitable physical properties required when used as a tackifier resin rather than as a pressure-sensitive adhesive. A more preferred lower limit of the Young's modulus at 25°C is 50 MPa, and an even more preferred lower limit is 70 MPa. The upper limit of the Young's modulus at 25°C is not particularly limited, but from the viewpoint of preventing the pressure-sensitive adhesive composition containing the compound from becoming too hard and reducing the adhesive strength, the upper limit is preferably 10,000 MPa, and more preferably 5,000 MPa. The Young's modulus at 25° C. can be adjusted to fall within the above range by adjusting, for example, the molecular weight of the compound, the composition and content of the structural unit (A) and the structural unit (B) in the compound, and the like. The Young's modulus at 25°C can be measured by conducting a tensile test using a tensile testing device (for example, Tensilon manufactured by ORIENTEC) at a tensile speed of 200 mm / min, a gripper distance of 15 mm, and a temperature of 25°C. The measurement sample can be prepared, for example, by filling a 10 x 50 mm mold with the compound and melting it at a temperature 100°C higher than the glass transition temperature to produce a test piece with a thickness of 1 mm.

[0055] The glass transition temperature of the compound of the present invention is not particularly limited, but a preferred lower limit is 0°C and a preferred upper limit is 200°C. If the glass transition temperature is within the above range, the Young's modulus of the compound can be easily adjusted to the above range, and the compound can have suitable physical properties required when used as a tackifier resin. A more preferred lower limit of the glass transition temperature is 10°C and a more preferred upper limit is 150°C. The glass transition temperature can be measured using a differential scanning calorimeter (e.g., SII Exstar 6000 / DSC 6220, manufactured by Hitachi High-Tech Science Corporation) in a nitrogen atmosphere at a heating rate of 10°C / min, and the value obtained in the first run can be used.

[0056] The iodine value of the compound of the present invention is not particularly limited, but a preferred lower limit is 2 g / 100 g and a preferred upper limit is 180 g / 100 g. When the iodine value is 2 g / 100 g or more, it is possible to prevent a decrease in the adhesive strength of the pressure-sensitive adhesive composition due to a deterioration in the compatibility between the compound and the base polymer, particularly between the compound and the styrene-based elastomer. When the iodine value is 180 g / 100 g or less, by incorporating the compound into the pressure-sensitive adhesive composition, the adhesive strength of the pressure-sensitive adhesive composition can be further increased, particularly to adherends with low polarity. A more preferred lower limit of the iodine value is 70 g / 100 g and a more preferred upper limit is 170 g / 100 g. The iodine value is an index showing the amount of unsaturated double bonds (amount of C=C bonds) and refers to a value measured in accordance with the method described in "JIS K 0070:1992".

[0057] Although the content of biologically derived carbon (carbon atoms) in the carbon (carbon atoms) in the compound of the present invention is not particularly limited, it is preferable that the content of biologically derived carbon in the carbon is 10% or more. A biologically derived carbon content of 10% or more is an indicator of a "bio-based product." A content of the biologically derived carbon of 10% or more is preferable from the viewpoint of saving petroleum resources and reducing carbon dioxide emissions. A more preferable lower limit of the biologically derived carbon content is 30%, an even more preferable lower limit is 60%, an even more preferable lower limit is 70%, and an even more preferable lower limit is 90%. The upper limit of the biologically derived carbon content is not particularly limited, and may be 100%. While carbon derived from living organisms contains a certain percentage of the radioactive isotope C-14, petroleum-derived carbon contains almost no C-14. Therefore, the content of carbon derived from living organisms can be calculated by measuring the concentration of C-14 in the compound. Specifically, this can be measured in accordance with ASTM D6866-20, a standard used in many bioplastic industries.

[0058] The compound of the present invention also includes hydrogenated products of the compounds described above. Note that the hydrogenated products are compounds in which the carbon-carbon double bonds present in the compounds described above are saturated by hydrogenation. Even such hydrogenated products are suitably used as tackifying resins to be blended into pressure-sensitive adhesive compositions, and can increase the adhesive strength of the pressure-sensitive adhesive composition, particularly to adherends with low polarity.

[0059] The method for producing the compound of the present invention is not particularly limited, but the following method is preferred, for example. That is, this is a method for producing a compound having a structural unit (A) derived from a monomer (a) having a solvation free energy Δμ with polytetrafluoroethylene of −30 kcal / mol or less, and a structural unit (B) derived from at least one monomer (b) selected from the group consisting of a terpene monomer, a vinyl monomer, and a conjugated diene monomer, in which the monomer (a) and the monomer (b) are copolymerized. Such a method for producing a compound also constitutes one aspect of the present invention.

[0060] The monomer (a) is not particularly limited as long as it has a solvation free energy Δμ with polytetrafluoroethylene of −30 kcal / mol or less, but is preferably at least one selected from the group consisting of monomer (a-1), monomer (a-2), monomer (a-3) and monomer (a-4) represented by the following formula:

[0061] [ka]

[0062] In the formula, R 1 each represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group, and n'' represents an integer of 2 or more and 5 or less. The above n'' is preferably 2 or 3, and more preferably 3.

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] In the formula, R 2 , R 3 and R 5 R represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. 4 R represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. 6 and R 7 each represents a hydrogen atom or an aliphatic hydrocarbon group; m'' represents an integer of 1 or more and 5 or less; l'' represents an integer of 2 or more and 5 or less; and k'' represents an integer of 1 or more and 5 or less.

[0067] In the method for producing the compound of the present invention, it is preferable to copolymerize the above-mentioned monomer (a) and the above-mentioned monomer (b) by cationic polymerization. By using cationic polymerization, the monomer (a) can be copolymerized with the monomer (b) without protecting functional groups such as phenolic hydroxyl groups, carboxyl groups, alkoxy groups, and amino groups of the monomer (a) in advance by chemical modification, and subsequent deprotection is also unnecessary. Therefore, the monomer (a) can be copolymerized with the monomer (b) in a simpler one-step reaction process, which also leads to a reduction in impurities and an improvement in yield.

[0068] A preferred method for copolymerizing the monomer (a) and the monomer (b) by cationic polymerization is to react the monomer (a) and the monomer (b) in the presence of a Lewis acid. This method is believed to generate cations of the monomer (b), allowing the cationic polymerization of the monomers (b) to proceed, while also allowing the Friedel-Crafts alkylation reaction between the monomers (a) and (b). Repeated reactions of this kind can produce a copolymer having the structural unit (A) derived from the monomer (a) and the structural unit (B) derived from the monomer (b). The Lewis acid is not particularly limited, and any conventionally known Lewis acid can be used, such as aluminum chloride (AlCl3), diethylaluminum chloride (Et2AlCl2), tin(IV) chloride (SnCl4), titanium(IV) chloride (TiCl4), boron trichloride (BCl3), boron trifluoride etherate (BF3·EtO), etc. Among these, aluminum chloride (AlCl3) is preferred because it can provide a higher yield.

[0069] More specifically, for example, when pyrogallol is used as the monomer (a) and α-pinene is used as the monomer (b), and these are reacted in the presence of aluminum chloride (AlCl), which is a Lewis acid, the reaction shown in the following scheme is thought to proceed. That is, cations of α-pinene, the monomer (b), are generated, and cationic polymerization of α-pinene proceeds (upper part of the scheme below), while a Friedel-Crafts alkylation reaction between pyrogallol, the monomer (a), and α-pinene, the monomer (b), proceeds (middle part of the scheme below). By repeating these reactions, a copolymer having structural units derived from pyrogallol and structural units derived from α-pinene can be obtained (lower part of the scheme below). Such a copolymer has structural units derived from pyrogallol in the main chain or at the terminal of the main chain.

[0070] [ka]

[0071] In the formula, s and t each represent an integer of 1 or more, and * represents a linking portion.

[0072] The compound of the present invention can be suitably used as a tackifier resin to be blended in a pressure-sensitive adhesive composition. A pressure-sensitive adhesive composition containing a base polymer and the compound (T1) of the present invention also constitutes the present invention. The content of the compound (T1) of the present invention in the pressure-sensitive adhesive composition of the present invention is not particularly limited, but even a small amount compared to conventional tackifier resins can increase the adhesive strength of the pressure-sensitive adhesive composition, and the preferred lower limit is 1 part by weight and the preferred upper limit is 35 parts by weight per 100 parts by weight of base polymer. When the content of the compound (T1) of the present invention is 1 part by weight or more, the adhesive strength of the pressure-sensitive adhesive composition can be further increased, and in particular, the adhesive strength can be further increased even to adherends with low polarity. When the content of the compound (T1) of the present invention is 35 parts by weight or less, the pressure-sensitive adhesive composition can be prevented from becoming too hard and losing its adhesive strength. A more preferred lower limit of the content of the compound (T1) of the present invention is 3 parts by weight, a more preferred upper limit is 30 parts by weight, an even more preferred lower limit is 5 parts by weight, and an even more preferred upper limit is 20 parts by weight.

[0073] The pressure-sensitive adhesive composition of the present invention may further contain at least one tackifying resin (T2) selected from the group consisting of rosin ester resins, terpene resins, and petroleum resins. Of these, rosin ester resins and terpene resins are preferred because they can further increase the adhesive strength of the pressure-sensitive adhesive composition.

[0074] The softening temperature of the tackifier resin (T2) preferably has a lower limit of 70°C and an upper limit of 170°C. If the softening temperature is 70°C or higher, it is possible to prevent the pressure-sensitive adhesive composition from becoming too soft and reducing the adhesive strength. If the softening temperature is 170°C or lower, it is possible to improve the wettability of the interface of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, and to prevent interfacial peeling. A more preferred lower limit of the softening temperature is 120°C. The softening temperature is measured by the ring and ball method according to JIS K2207.

[0075] The tackifier resin (T2) preferably has a hydroxyl value of 25 (lower limit) and 150 (upper limit). When the hydroxyl value is within the above range, the wettability of the interface of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is improved, and interfacial peeling can be suppressed. The hydroxyl value is more preferably 30 (lower limit) and 130 (upper limit). The hydroxyl value can be measured according to JIS K1557 (phthalic anhydride method).

[0076] The content of the tackifier resin (T2) is not particularly limited, but a preferred lower limit is 10 parts by weight and a preferred upper limit is 100 parts by weight per 100 parts by weight of the base polymer. If the content of the tackifier resin (T2) is 10 parts by weight or more, the adhesive strength of the PSA composition can be further increased. If the content of the tackifier resin (T2) is 100 parts by weight or less, the PSA composition can be prevented from becoming too hard and reducing its adhesive strength. A more preferred lower limit of the content of the tackifier resin (T2) is 15 parts by weight, a more preferred upper limit is 60 parts by weight, an even more preferred upper limit is 50 parts by weight, and an even more preferred upper limit is 40 parts by weight.

[0077] The base polymer is not particularly limited, and examples thereof include acrylic polymers, rubber polymers, urethane polymers, and silicone polymers. Among these, acrylic polymers are preferred because they are relatively stable against light, heat, moisture, and the like. Rubber polymers are also preferred because they have low adherend selectivity, can adhere to various adherends, and are resistant to peeling from the adherend even when immersed in an alkaline chemical solution. Among the rubber polymers, styrene elastomers, which are block copolymers having a block derived from a styrene monomer and a block derived from a conjugated diene monomer, or hydrogenated versions thereof, are more preferred.

[0078] From the viewpoint of improving initial tackiness and thus ease of application at low temperatures, the acrylic polymer preferably has a structural unit derived from at least one selected from the group consisting of (meth)acrylic acid alkyl esters having an alkyl group with 1 to 12 carbon atoms and (meth)acrylic acid alkyl esters having an alkyl group with 13 to 18 carbon atoms. Examples of the (meth)acrylic acid alkyl esters having 1 to 12 carbon atoms in the alkyl group include 2-ethylhexyl (meth)acrylate, butyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and isopropyl (meth)acrylate. Examples of the (meth)acrylic acid alkyl esters having 13 to 18 carbon atoms in the alkyl group include tridecyl methacrylate and stearyl (meth)acrylate. Among these, it is preferable to use 2-ethylhexyl (meth)acrylate or butyl (meth)acrylate because the acrylic polymers can exhibit high adhesive strength. The content of structural units derived from at least one selected from the group consisting of (meth)acrylic acid alkyl esters having an alkyl group carbon number of 1 to 12 and (meth)acrylic acid alkyl esters having an alkyl group carbon number of 13 to 18 in the acrylic polymer is not particularly limited. The lower limit of the content is preferably 10 wt%, and the upper limit is preferably 100 wt%, more preferably 30 wt%, more preferably 95 wt%, still more preferably 50 wt%, and still more preferably 90 wt%. By keeping the content within this range, the acrylic polymer can exhibit high adhesive strength.

[0079] The acrylic polymer preferably has a structural unit derived from a monomer having a crosslinkable functional group. Since the acrylic polymer has a structural unit derived from the monomer having the crosslinkable functional group, a crosslinked structure of the acrylic polymer is formed in the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition by adding a crosslinking agent. This increases the gel fraction and bulk strength of the pressure-sensitive adhesive layer, improving adhesive strength. The crosslinkable functional group is not particularly limited, and examples thereof include an amino group, a carboxyl group, a carbonyl group, a hydroxyl group, an epoxy group, and an isocyanate group.

[0080] Specific examples of the monomer having a crosslinkable functional group include hydroxyalkyl (meth)acrylate, glycerin dimethacrylate, glycidyl (meth)acrylate, 2-methacryloyloxyethyl isocyanate, (meth)acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid, and fumaric acid. More specific examples of the hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate. These monomers having a crosslinkable functional group may be used alone, or two or more of them may be used in combination. Of these, from the viewpoint of increasing the gel fraction and bulk strength of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, preferred are monomers having a hydroxyl group, such as hydroxyalkyl (meth)acrylate and glycerin dimethacrylate, or monomers having a carboxyl group, such as (meth)acrylic acid.

[0081] The content of the structural unit derived from the monomer having a crosslinkable functional group in the acrylic polymer is not particularly limited, but a preferred lower limit is 0.01 wt % and a preferred upper limit is 20 wt %. By setting the content of the structural unit derived from the monomer having a crosslinkable functional group within this range, the gel fraction and bulk strength of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition are increased, thereby improving adhesive strength. A more preferred lower limit of the content of the structural unit derived from the monomer having a crosslinkable functional group is 0.05 wt %, and a more preferred upper limit is 5 wt %.

[0082] The acrylic polymer may, as necessary, contain a constituent unit derived from another copolymerizable polymerizable monomer other than the constituent unit derived from the alkyl (meth)acrylate ester as described above and the constituent unit derived from the monomer having a crosslinkable functional group.

[0083] The acrylic polymer can be obtained by subjecting the above-described monomer mixture to a radical reaction in the presence of a polymerization initiator. As a method for subjecting the monomer mixture to a radical reaction, i.e., a polymerization method, a conventionally known method can be used, such as solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc.

[0084] The weight-average molecular weight (Mw) of the acrylic polymer is not particularly limited, but a preferred lower limit is 200,000 and a preferred upper limit is 2,000,000. If the weight-average molecular weight (Mw) is 200,000 or more, the bulk strength of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition increases, improving adhesive strength. If the weight-average molecular weight (Mw) is 2,000,000 or less, the interfacial wettability of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition improves, making it possible to suppress interfacial peeling. A more preferred lower limit of the weight-average molecular weight (Mw) is 400,000 and a more preferred upper limit is 1,500,000.

[0085] The ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the acrylic polymer (molecular weight distribution, Mw / Mn) is not particularly limited, but a preferred lower limit is 1.05 and a preferred upper limit is 5.0. When Mw / Mn is 5.0 or less, the proportion of low-molecular-weight components is suppressed, the bulk strength of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is increased, and the adhesive strength is improved. A more preferred upper limit of Mw / Mn is 4.5, an even more preferred upper limit is 4, and an even more preferred upper limit is 3.5. The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) can be adjusted to fall within the above ranges by, for example, adjusting the composition, polymerization method, polymerization conditions, etc. of the acrylic polymer.

[0086] The styrene-based elastomer may be a block copolymer having rubber elasticity at room temperature and having a hard segment portion and a soft segment portion, where the block derived from the styrene-based monomer is the hard segment portion and the block derived from the conjugated diene-based monomer is the soft segment portion.

[0087] The styrene-based monomer is not particularly limited, and examples thereof include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene. The tertiary amino group-containing diphenylethylene is not particularly limited, and examples thereof include 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene. These styrene-based monomers may be used alone or in combination of two or more.

[0088] The conjugated diene monomer is not particularly limited, and examples thereof include isoprene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-chloro-1,3-butadiene, etc. These conjugated diene monomers may be used alone or in combination of two or more.

[0089] Specific examples of the styrene-based elastomer include styrene-isoprene-styrene (SIS) block copolymers, styrene-butadiene-styrene (SBS) block copolymers, and styrene-chloroprene-styrene block copolymers. Among these, SIS block copolymers and SBS block copolymers are preferred, with SIS block copolymers being more preferred, because they tend to exhibit high adhesive strength and are less likely to peel from the adherend even when immersed in an alkaline chemical solution. These styrene-based elastomers may be used alone or in combination of two or more.

[0090] The styrene-based elastomer may contain a diblock copolymer of a block derived from the styrene-based monomer and a block derived from the conjugated diene-based monomer, in addition to a triblock copolymer of a block derived from the styrene-based monomer and a block derived from the conjugated diene-based monomer. The content of the diblock copolymer in the styrene-based elastomer (hereinafter also referred to as the "diblock ratio") is not particularly limited, but a preferred lower limit is 50% by weight, and a more preferred lower limit is 70% by weight. If the diblock ratio is within the above range, the adhesiveness of the pressure-sensitive adhesive composition to the adherend is enhanced, and the adhesive strength is improved. The upper limit of the diblock ratio is not particularly limited, but from the viewpoint of maintaining the cohesive strength of the pressure-sensitive adhesive composition, a preferred upper limit is 90% by weight. The diblock ratio can be calculated from the peak area ratio of each copolymer measured by gel permeation chromatography (GPC).

[0091] The content of the block derived from the styrene-based monomer in the styrene-based elastomer (hereinafter also referred to as "styrene content") is not particularly limited, but a preferred upper limit is 20% by weight, more preferably 16% by weight. If the styrene content is within the above range, the pressure-sensitive adhesive composition does not become too hard, and the adhesiveness to the adherend is increased, improving the adhesive strength. The lower limit of the styrene content is not particularly limited, but from the viewpoint of maintaining the cohesive strength of the pressure-sensitive adhesive composition, a preferred lower limit is 8% by weight. The styrene content is 1 It can be calculated from the peak area ratio of each block measured by H-NMR.

[0092] The weight-average molecular weight of the styrene-based elastomer is not particularly limited, but a preferred lower limit is 50,000 and a preferred upper limit is 600,000. If the weight-average molecular weight is 50,000 or more, the bulk strength of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition increases, improving adhesive strength. If the weight-average molecular weight is 600,000 or less, excessive deterioration in compatibility between the styrene-based elastomer and other components can be prevented. A more preferred lower limit of the weight-average molecular weight is 100,000 and a more preferred upper limit is 500,000.

[0093] When the base polymer is an acrylic polymer, the pressure-sensitive adhesive composition of the present invention preferably contains a crosslinking agent. By adjusting the type and amount of the crosslinking agent, it becomes easier to adjust the gel fraction of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. The crosslinking agent is not particularly limited, and examples thereof include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents. Among these, isocyanate-based crosslinking agents are preferred. The content of the crosslinking agent is preferably 0.01 parts by weight at the lower limit and 10 parts by weight at the upper limit, more preferably 0.1 parts by weight and 5 parts by weight at the upper limit, per 100 parts by weight of the acrylic polymer.

[0094] The pressure-sensitive adhesive composition of the present invention may contain a silane coupling agent for the purpose of improving adhesive strength. The silane coupling agent is not particularly limited, and examples thereof include epoxy silanes, acrylic silanes, methacrylic silanes, amino silanes, and isocyanate silanes.

[0095] The pressure-sensitive adhesive composition of the present invention may contain a colorant for the purpose of imparting light-blocking properties. The colorant is not particularly limited, and examples thereof include carbon black, aniline black, titanium oxide, etc. Among these, carbon black is preferred because it is relatively inexpensive and chemically stable.

[0096] The pressure-sensitive adhesive composition of the present invention may contain conventionally known fine particles and additives, such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers, as needed.

[0097] The present invention also includes a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition of the present invention. When the base polymer is an acrylic polymer, the gel fraction of the pressure-sensitive adhesive layer is not particularly limited, but a preferred lower limit is 10 wt % and a preferred upper limit is 70 wt %. If the gel fraction is 10 wt % or more, the bulk strength of the pressure-sensitive adhesive layer increases, improving adhesive strength. If the gel fraction is 70 wt % or less, the wettability of the interface of the pressure-sensitive adhesive layer improves, preventing interfacial peeling. A more preferred lower limit of the gel fraction is 15 wt %, a more preferred upper limit is 60 wt %, an even more preferred lower limit is 20 wt %, and an even more preferred upper limit is 50 wt %. The gel fraction of the pressure-sensitive adhesive layer can be adjusted within the above range, for example, by adjusting the composition and weight average molecular weight of the acrylic polymer, or by adjusting the type and amount of the crosslinking agent.

[0098] The gel fraction of the pressure-sensitive adhesive layer can be measured by the following method. The adhesive tape is cut into a flat rectangular shape of 50 mm x 100 mm to prepare a test specimen. The test specimen is immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 110°C for 1 hour. The weight of the dried test specimen is measured, and the gel fraction is calculated using the following formula (1). Note that no release film to protect the adhesive layer is laminated on the test specimen. Gel fraction (wt%) = 100 × (W2 - W0) / (W1 - W0) (1) (W0: weight of substrate, W1: weight of test piece before immersion, W2: weight of test piece after immersion and drying)

[0099] When the base polymer is an acrylic polymer, the preferred lower limit of the shear storage modulus at 25°C measured using a dynamic viscoelasticity measuring device at a measurement frequency of 10 Hz (hereinafter simply referred to as "shear storage modulus") of the pressure-sensitive adhesive layer is 1.0 × 10 4 Pa, the preferred upper limit is 5.0 × 10 5 It is Pa. When the shear storage modulus of the pressure-sensitive adhesive layer is within the above range, the adhesive strength of the pressure-sensitive adhesive layer is further improved. 4 Pa or more is more preferable, and 5.0 × 10 4 More preferably, the saturation temperature is 4.0×10 Pa or more. 5 Pa or less is more preferable, and 3.5 × 10 5 It is more preferably not more than 1 Pa. The shear storage modulus of the pressure-sensitive adhesive layer can be adjusted by the types and polymerization ratios of the monomers constituting the base polymer, the molecular weight of the base polymer, the gel fraction of the pressure-sensitive adhesive layer, the presence or absence of the tackifier resin (T2), and the types and contents of the compound (T1) of the present invention and the tackifier resin (T2), etc.

[0100] The shear storage modulus of the pressure-sensitive adhesive layer can be measured by the following method. First, a measurement sample consisting of only the pressure-sensitive adhesive layer is prepared. The dynamic viscoelasticity spectrum of the obtained measurement sample is measured from -50°C to 200°C using a dynamic viscoelasticity measuring device such as a viscoelasticity spectrometer (for example, IT Measurement Control's DVA-200 or equivalent) in a slow heating shear deformation mode at 5°C / min and a measurement frequency of 10 Hz, and the storage modulus at 25°C is measured.

[0101] When the base polymer is an acrylic polymer, it is preferable that the pressure-sensitive adhesive layer has a loss tangent (tanδ, hereinafter simply referred to as "loss tangent") measured at a measurement frequency of 10 Hz using a dynamic viscoelasticity measuring device, which has a peak at a temperature between -20°C and 20°C. When the loss tangent of the pressure-sensitive adhesive layer has a peak in the above range, it becomes easier to achieve both adhesive strength and holding power of the pressure-sensitive adhesive layer. The loss tangent more preferably has a peak at 15° C. or lower, and even more preferably has a peak at 12° C. or lower. The loss tangent more preferably has a peak at −15° C. or higher, and even more preferably has a peak at −10° C. or higher. The loss tangent of the adhesive layer can be obtained by measuring the dynamic viscoelasticity spectrum from -100°C to 200°C using a viscoelasticity spectrometer (for example, DVA-200 manufactured by IT Measurement & Control Co., Ltd., or an equivalent product) under conditions of a slow heating rate shear deformation mode of 5°C / min and a measurement frequency of 10 Hz.

[0102] The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the lower limit is preferably 20 μm, the upper limit is preferably 100 μm, the lower limit is more preferably 25 μm, and the upper limit is more preferably 80 μm. If the thickness of the pressure-sensitive adhesive layer is within this range, the pressure-sensitive adhesive layer can have sufficient adhesive strength. The thickness of the pressure-sensitive adhesive layer can be measured using a dial thickness meter (for example, "ABS Digimatic Indicator" manufactured by Mitutoyo Corporation).

[0103] The pressure-sensitive adhesive tape of the present invention may have a substrate. In this case, the pressure-sensitive adhesive layer may be laminated on one surface or both surfaces of the substrate. The substrate is not particularly limited, and examples thereof include resin films. The resin film is not particularly limited, and examples thereof include polyolefin resin films such as polyethylene film and polypropylene film, polyester resin films such as polyethylene terephthalate (PET) film, ethylene-vinyl acetate copolymer films, polyvinyl chloride resin films, and polyurethane resin films. Other examples of the substrate include polyolefin foam sheets such as polyethylene foam sheets and polypropylene foam sheets, and polyurethane foam sheets. Of these, PET films are preferred. The thickness of the substrate is not particularly limited, but the lower limit is preferably 5 μm, the upper limit is preferably 30 μm, the lower limit is more preferably 8 μm, and the upper limit is more preferably 20 μm.

[0104] The pressure-sensitive adhesive tape of the present invention may have layers other than the pressure-sensitive adhesive layer and the substrate, if necessary.

[0105] The method for producing the pressure-sensitive adhesive tape of the present invention is not particularly limited, and for example, when the pressure-sensitive adhesive layers are laminated on both sides of the substrate, the following method can be mentioned. First, a solvent is added to the base polymer, the compound (T1) of the present invention, the tackifier resin (T2), the crosslinker, etc. to prepare a solution of PSA composition A, and this solution of PSA composition A is applied to the surface of a substrate, and the solvent in the solution is completely dried and removed to form a PSA layer A. Next, a release film is superimposed on the formed PSA layer A with its release-treated surface facing the PSA layer A. Next, a release film separate from the above release film is prepared, and a solution of PSA composition B is applied to the release-treated surface of this release film. The solvent in the solution is then completely dried and removed to produce a laminate film in which PSA layer B is formed on the surface of the release film. The obtained laminate film is superimposed on the back surface of the substrate on which PSA layer A is formed, with PSA layer B facing the back surface of the substrate, to produce a laminate. The laminate is then pressed with a rubber roller or the like. This produces a double-sided PSA tape having PSA layers on both sides of the substrate, and the surfaces of the PSA layers covered with release films.

[0106] Alternatively, two sets of laminate films may be prepared in a similar manner, and these laminate films may be superimposed on both sides of a substrate with the pressure-sensitive adhesive layers of the laminate films facing the substrate to prepare a laminate, which may then be pressed with a rubber roller, etc. This makes it possible to obtain a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both sides of the substrate, the surfaces of which are covered with release films.

[0107] The uses of the pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive tape of the present invention are not particularly limited, but because they have high adhesive strength, particularly to adherends with low polarity (e.g., adherends that are difficult to adhere, such as adherends made of polyolefin resins or fluororesins), they are used, for example, to fix electronic device parts or vehicle-mounted parts. More specifically, they are used, for example, to fix parts in televisions, monitors, portable electronic devices, vehicle-mounted electronic devices, etc. The shape of the pressure-sensitive adhesive tape of the present invention for these uses is not particularly limited, and examples thereof include square, rectangular, frame-like, circular, oval, and doughnut-like shapes. [Effects of the Invention]

[0108] According to the present invention, it is possible to provide a compound that can increase the adhesive strength of a pressure-sensitive adhesive composition, particularly, that can increase the adhesive strength even to an adherend with low polarity. Furthermore, according to the present invention, it is possible to provide a method for producing the compound, a pressure-sensitive adhesive composition containing the compound, and a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition. DETAILED DESCRIPTION OF THE INVENTION

[0109] The following examples will explain the present invention in more detail, but the present invention is not limited to these examples.

[0110] (Synthesis Example 1) (Preparation of Acrylic Polymer) A reactor equipped with a thermometer, stirrer, and condenser was charged with 100 parts by weight of ethyl acetate. After purging with nitrogen, the reactor was heated to initiate reflux. 30 minutes after the ethyl acetate boiled, 0.08 parts by weight of azobisisobutyronitrile was added as a polymerization initiator. The monomer mixture shown in Table 1 was added dropwise evenly and gradually over 1 hour and 30 minutes, allowing the reaction to proceed. 30 minutes after the addition was complete, 0.1 parts by weight of azobisisobutyronitrile was added, and the polymerization reaction was allowed to proceed for an additional 5 hours. The reactor was then cooled while being diluted with ethyl acetate, yielding an acrylic polymer solution with a solids content of 25% by weight. The resulting acrylic polymer solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The resulting filtrate was fed to a gel permeation chromatograph (Waters, 2690 Separations Model) and subjected to GPC measurement at a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-equivalent molecular weight of the acrylic polymer was measured, and the weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were determined. A GPC KF-806L (Showa Denko KK) column was used, and a differential refractometer was used as the detector.

[0111] (Synthesis Example 2) (Preparation of Acrylic Polymer) An acrylic polymer was obtained in the same manner as in Synthesis Example 1, except that the amount of ethyl acetate added was changed to 50 parts by weight.

[0112] (Synthesis Example 3) (Preparation of Acrylic Polymer) An acrylic polymer was obtained in the same manner as in Synthesis Example 1, except that the monomer mixture was changed as shown in Table 1.

[0113] [Table 1]

[0114] (Synthesis example A) (Preparation of Compound (T1)) A reactor equipped with a thermometer, stirrer, and condenser was charged with 50 parts by weight of toluene. The reactor was then purged with nitrogen and heated to initiate reflux. After 30 minutes, 2 parts by weight of aluminum chloride (AlCl3) was added while maintaining the toluene at 75°C. A solution of 22.3 parts by weight of monomer (a) and 27.7 parts by weight of monomer (b) (molar ratios shown in Table 2) dissolved in 50 parts by weight of toluene was slowly added dropwise over 1 hour and 30 minutes to allow the reaction to proceed. After 4 hours of polymerization, the reactor was cooled while adding 0.1 parts by weight of pyridine to neutralize the hydrochloric acid generated from the aluminum chloride (AlCl3). The precipitate formed during neutralization was filtered, and the resulting filtrate was separated. The toluene was then evaporated to obtain solid compound (T1). The solvation free energy Δμ of monomer (a) with polytetrafluoroethylene was calculated using molecular dynamics simulations. Regarding the obtained compound (T1) l H-NMR measurement confirmed that compound (T1) was a copolymer having a structural unit (A) derived from pyrocatechol, which is monomer (a), and a structural unit (B) derived from α-pinene, which is monomer (b). A solution of the obtained compound (T1) in tetrahydrofuran was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (Waters, 2690 Separations Model) and subjected to GPC measurement under conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-equivalent molecular weight of compound (T1) was measured, and the weight-average molecular weight (Mw) was determined. A GPC KF-802.5L (Showa Denko KK) was used as the column, and a differential refractometer was used as the detector.

[0115] The obtained compound (T1) was measured using a differential scanning calorimeter (Hitachi High-Tech Science Corporation, SII Exstar 6000 / DSC 6220) under a nitrogen atmosphere at a heating rate of 10°C / min. The glass transition temperature was measured using the value obtained in the first run.

[0116] The obtained compound (T1) was filled into a mold measuring 10 × 50 mm and melted at a temperature 100°C higher than the glass transition temperature to prepare a test piece with a thickness of 1 mm. The Young's modulus at 25°C was measured by subjecting this test piece to a tensile test using a tensile testing machine (Tensilon, manufactured by ORIENTEC) at a tensile speed of 200 mm / min, a gripper distance of 15 mm, and a temperature of 25°C.

[0117] 0.250 g of the resulting compound (T1) was weighed and diluted with 50 mL of cyclohexane. Next, 10.0 mL of Wiess's reagent (Wako Pure Chemical Industries, Ltd., 0.1 mol / L iodine chloride-acetic acid solution) was added, shaken well, and left for 30 minutes to allow the reaction to proceed. 10 mL of 15 wt% potassium iodide aqueous solution was added, followed by 30 mL of water and stirring. Further, 0.1 N sodium thiosulfate aqueous solution (Wako Pure Chemical Industries, Ltd.) was slowly added dropwise. When the solution turned pale yellow, three drops of starch solution (10 g / L) were added. Subsequently, 0.1 N sodium thiosulfate aqueous solution (Wako Pure Chemical Industries, Ltd.) was slowly added dropwise (drop volume Y mL) until the blue color of the solution disappeared. Next, the blank drop volume (drop volume Z mL) was calculated in the same manner, except that the sample (compound (T1)) was not added. The iodine value of compound (T1) was measured using the following formula: Iodine value (g / 100g) = (ZY) × 1.269 / 0.250

[0118] The content of bio-derived carbon in the obtained compound (T1) was measured in accordance with ASTM D6866-20.

[0119] (Synthesis Examples B to M and O) (Preparation of Compound (T1)) Compound (T1) was obtained in the same manner as in Synthesis Example A, except that the monomers (a) and (b) were changed as shown in Table 2.

[0120] (Synthesis example N) (Preparation of Compound (T1)) A reactor equipped with a thermometer, stirrer, and condenser was charged with 50 parts by weight of toluene. The atmosphere was then purged with nitrogen, and the reactor was heated to initiate reflux. After 30 minutes, 2 parts by weight of aluminum chloride (AlCl3) was added while maintaining the toluene at 75°C. A solution of 50 parts by weight of monomer (a) and monomer (b) (shown in Table 2, molar ratios shown in Table 2) dissolved in 50 parts by weight of toluene was gradually added dropwise over 1 hour and 30 minutes to allow the reaction to proceed. After 4 hours of polymerization, the reactor was cooled while adding 0.1 parts by weight of pyridine to neutralize the hydrochloric acid generated from the aluminum chloride (AlCl3). The precipitate formed during neutralization was filtered, and the filtrate was separated. The toluene was then evaporated to obtain solid compound (T1). Regarding the obtained compound (T1) l H-NMR measurement confirmed that compound (T1) was a copolymer having structural unit (A-2') derived from monomer (a), 4-vinylbenzoic acid, and structural unit (B) derived from monomer (b), α-pinene.

[0121] [Table 2]

[0122] Example 1 (1) Manufacture of adhesive tapes 30 parts by weight of compound (T1) (Synthesis Example A) was added to 100 parts by weight of the solid content of the acrylic polymer (Synthesis Example 1). Further, 30 parts by weight of ethyl acetate (manufactured by Fuji Chemical Co., Ltd.) and 2.5 parts by weight of an isocyanate crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L45") were added and stirred to obtain a solution of a pressure-sensitive adhesive composition. A 150 μm-thick release film was prepared, and a solution of the adhesive composition was applied to the release-treated surface of this release film. This was followed by drying at 100°C for 5 minutes to form a 50 μm-thick adhesive layer. This adhesive layer was then bonded to the surface of a 50 μm-thick corona-treated PET film substrate. Next, the same adhesive layer was bonded to the opposite surface of the substrate in the same manner. The resulting adhesive tape was then aged by heating at 40°C for 48 hours. This resulted in an adhesive tape in which adhesive layers were laminated on both sides of the substrate and the surfaces of the adhesive layers were covered with release films.

[0123] (2) Measurement of gel fraction The adhesive tape was cut into a 50 mm × 100 mm flat rectangular shape to prepare a test piece. The test piece was immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 110°C for 1 hour. The weight of the dried test piece was measured, and the gel fraction was calculated using the following formula (1). Note that no release film to protect the adhesive layer was laminated on the test piece. Gel fraction (wt%) = 100 × (W2 - W0) / (W1 - W0) (1) (W0: weight of substrate, W1: weight of test piece before immersion, W2: weight of test piece after immersion and drying)

[0124] (3) Measurement of shear storage modulus A measurement sample consisting of only the pressure-sensitive adhesive layer was prepared. The dynamic viscoelasticity spectrum of the obtained measurement sample was measured from -50°C to 200°C using a viscoelasticity spectrometer (IT Measurement & Control Co., Ltd., DVA-200) under conditions of a slow heating rate shear deformation mode of 5°C / min and a measurement frequency of 10 Hz, and the storage modulus at 25°C was measured.

[0125] (4) Measurement of the peak temperature of the loss tangent (tanδ) A measurement sample consisting of only the pressure-sensitive adhesive layer was prepared. The dynamic viscoelasticity spectrum of the obtained measurement sample was measured from -100°C to 200°C using a viscoelasticity spectrometer (IT Measurement & Control, DVA-200) under conditions of a slow heating rate shear deformation mode of 5°C / min and a measurement frequency of 10 Hz, and the peak temperature of the loss tangent (tanδ) was obtained from the obtained dynamic viscoelasticity spectrum.

[0126] (Examples 2 to 25, Comparative Examples 1 and 2) Pressure-sensitive adhesive tapes were obtained in the same manner as in Example 1, except that the types and amounts of the acrylic polymer, compound (T1), tackifier resin (T2), and crosslinker were changed as shown in Table 3. The tackifier resin (T2) and crosslinker used are shown below. Note that for the tackifier resin (T2), the smallest solvation free energy Δμ between the monomer constituting the tackifier resin (T2) and polytetrafluoroethylene is shown.

[0127] Rosin ester resin (manufactured by Arakawa Chemical Industries, Ltd., product name "Pine Crystal KE359", Δμ=-5 kcal / mol) Terpene phenol resin (manufactured by Yasuhara Chemical Co., Ltd., trade name "YS Polystar G150", Δμ = -25 kcal / mol) Isocyanate crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., product name "Coronate L45") Epoxy crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., product name "Tetrad E5XM")

[0128] Example 26 To 100 parts by weight of the solid content of a styrene-based elastomer (SIS block copolymer, Zeon Corporation, Quintac 3520, styrene content: 15 wt%, diblock ratio: 78 wt%), 30 parts by weight of compound (T1) (Synthesis Example A) was added. 30 parts by weight of toluene (Fuji Chemicals Co., Ltd.) was then added and stirred to obtain a solution of a pressure-sensitive adhesive composition. A 150 μm-thick release film was prepared, and a solution of the adhesive composition was applied to the release-treated surface of this release film. This was followed by drying at 100°C for 5 minutes to form a 50 μm-thick adhesive layer. This adhesive layer was then bonded to the surface of a 50 μm-thick corona-treated PET film substrate. Next, the same adhesive layer was bonded to the opposite surface of the substrate in the same manner. The resulting adhesive tape was then aged by heating at 40°C for 48 hours. This resulted in an adhesive tape in which adhesive layers were laminated on both sides of the substrate and the surfaces of the adhesive layers were covered with release films.

[0129] (Examples 27 to 57, Comparative Examples 3 to 4) Pressure-sensitive adhesive tapes were obtained in the same manner as in Example 26, except that the types and amounts of the styrene elastomer, compound (T1), and tackifier resin (T2) were changed as shown in Tables 4 and 5. The styrene elastomers and tackifier resins (T2) used are shown below. Note that for the tackifier resin (T2), the smallest solvation free energy Δμ between the tackifier resin (T2) and polytetrafluoroethylene, a monomer constituting the tackifier resin (T2), is shown.

[0130] Styrene-based elastomer (SIS block copolymer, Zeon Corporation, Quintac 3520, styrene content: 15% by weight, diblock ratio: 78% by weight) Styrene-based elastomer (SIS block copolymer, Zeon Corporation, Quintac 3433N, styrene content: 16% by weight, diblock ratio: 56% by weight) Styrene-based elastomer (SIS block copolymer, Zeon Corporation, Quintac 3421, styrene content: 14% by weight, diblock ratio: 26% by weight) Styrene-based elastomer (SIS block copolymer, Zeon Corporation, Quintac 3450, styrene content: 19% by weight, diblock ratio: 30% by weight) Styrene-based elastomer (SIS block copolymer, Zeon Corporation, Quintac 3280, styrene content: 25% by weight, diblock ratio: 17% by weight) Styrene-based elastomer (SBS block copolymer, Kraton Polymer Japan, Kraton DX410, styrene content: 18% by weight, diblock ratio: 60% by weight) Terpene resin (Yasuhara Chemical Co., Ltd., trade name "YS Resin PX1150", Δμ = -5 kcal / mol)

[0131] <Evaluation> The pressure-sensitive adhesive tapes obtained in the examples and comparative examples were evaluated by the following methods, and the results are shown in Tables 3 to 5.

[0132] (1) 180° peel test The adhesive tape was cut into 25 mm widths to obtain test specimens. The adhesive layer of the obtained test specimen was placed on a stainless steel (SUS304) plate (manufactured by Nippon Test Panel Co., Ltd.), a polypropylene (PP) plate (manufactured by Nippon Test Panel Co., Ltd.), or a polytetrafluoroethylene (PTFE) plate (manufactured by Nippon Test Panel Co., Ltd.). Next, a 2 kg rubber roller was rolled back and forth over the test specimen at a speed of 300 mm / min, bonding the test specimen to the stainless steel (SUS304) plate, the polypropylene (PP) plate, or the polytetrafluoroethylene (PTFE) plate. The test specimen was then left to stand at 23°C for 1 hour to prepare a test sample. After standing, the test sample was subjected to a 180° tensile test at a peel rate of 300 mm / min in accordance with JIS Z0237 to measure the peel strength.

[0133] 180° peel test against SUS ◎: Peeling force is 20N / inch or more ○: Peeling force is 15N / inch or more and less than 20N / inch △: Peeling force is 10N / inch or more and less than 15N / inch ×: Peeling force is less than 10 N / inch

[0134] 180° peel test against PP ◎: Peeling force is 15N / inch or more ○: Peeling force is 10N / inch or more and less than 15N / inch △: Peeling force is 5N / inch or more and less than 10N / inch ×: Peeling force is less than 5 N / inch

[0135] PTFE 180° peel test ◎: Peeling force is 5N / inch or more ○: Peeling force is 3N / inch or more and less than 5N / inch △: Peeling force is 1N / inch or more and less than 3N / inch ×: Peeling force is less than 1 N / inch

[0136] (2) Alkali resistance test A test specimen was prepared by cutting the adhesive tape into a 25 mm x 75 mm piece, peeling off the release film from one side, and attaching it to a 23 μm-thick polyethylene terephthalate (PET) film as a backing. In an environment of 23°C, the release film covering the other adhesive side of the test specimen was peeled off, and the test specimen was pressed against the surface of a stainless steel (SUS304) plate using a 2 kg roller, moving back and forth once, to obtain a test sample before immersion in the chemical solution. Sodium hydroxide was diluted with ion-exchanged water to prepare an alkaline chemical solution with a pH of 12. The test sample before immersion was immersed in the alkaline chemical solution for one day in an atmosphere of 60°C. The test sample was then removed from the alkaline chemical solution, washed with ion-exchanged water, and dried at 23°C for one hour to obtain a test sample after immersion in the chemical solution. The obtained test samples were observed for peeling of the adhesive tape from the stainless steel plate before and after immersion in the chemical solution. ○: The adhesive tape did not peel off. △: Only slight peeling occurred at the edge of the adhesive tape ×: The entire surface was peeled off

[0137] [Table 3]

[0138] [Table 4]

[0139] [Table 5] [Industrial Applicability]

[0140] According to the present invention, it is possible to provide a compound that can increase the adhesive strength of a pressure-sensitive adhesive composition, particularly, that can increase the adhesive strength even to an adherend with low polarity. Furthermore, according to the present invention, it is possible to provide a method for producing the compound, a pressure-sensitive adhesive composition containing the compound, and a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition.

Claims

1. A pressure-sensitive adhesive composition comprising a base polymer and a compound (T1), The compound (T1) is a copolymer having a structural unit (A) and a structural unit (B) represented by the following formula: 【Chemistry 1】 (In the formula, A represents the structural unit (A), B represents the structural unit (B), and s and t each represent an integer of 1 or greater. * represents a linking moiety.) the structural unit (A) is derived from a monomer (a) having a solvation free energy Δμ with polytetrafluoroethylene of −30 kcal / mol or less; The structural unit (B) is derived from a terpene monomer, The structural unit (A) is at least one selected from the group consisting of structural units (A-1), (A-2), (A-3), and (A-4) represented by the following formulas: 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 【Transformation 5】 (In the formula, R １ , R ２ , R ３ and R ５ respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. R ４ respectively represent an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. R ６ and R ７ represents a hydrogen atom or an aliphatic hydrocarbon group. The polar functional group is any one of an amino group, a carboxyl group, a carbonyl group, an alkoxy group, a hydroxyl group, a nitrile group, and a nitro group, and in the case of the structural unit (A-1), a hydroxyl group is not contained, in the case of the structural unit (A-2), a carboxyl group is not contained, in the case of the structural unit (A-3), an alkoxy group is not contained, and in the case of the structural unit (A-4), an amino group is not contained. n represents an integer of 2 or more and 4 or less. m represents an integer of 1 or more and 4 or less. l represents an integer of 2 or more and 4 or less. k represents an integer of 1 or more and 4 or less.

2. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the compound (T1) has a Young's modulus at 25°C of 10 MPa or more.

3. 3. The pressure-sensitive adhesive composition according to claim 1, wherein the compound (T1) further comprises an aliphatic hydrocarbon group having an unsaturated double bond.

4. 4. The pressure-sensitive adhesive composition according to claim 1, wherein the compound (T1) has a content of the structural unit (A) of 1 mol % or more and 60 mol % or less.

5. 5. The pressure-sensitive adhesive composition according to claim 1, wherein the compound (T1) has a weight-average molecular weight of 400 or more and 10,000 or less.

6. 6. The pressure-sensitive adhesive composition according to claim 1, wherein the compound (T1) has a glass transition temperature of 0°C or higher and 200°C or lower.

7. 7. The pressure-sensitive adhesive composition according to claim 1, wherein the content of carbon of biological origin in the carbon of the compound (T1) is 10% or more.

8. The pressure-sensitive adhesive composition according to any one of claims 1 to 7, wherein n is 2 in the structural unit (A-1).

9. The pressure-sensitive adhesive composition according to any one of claims 1 to 7, wherein n is 3 in the structural unit (A-1).

10. 10. The pressure-sensitive adhesive composition according to claim 1, wherein the content of the compound (T1) is 1 part by weight or more and 35 parts by weight or less per 100 parts by weight of the base polymer.

11. The pressure-sensitive adhesive composition according to any one of claims 1 to 10, further comprising at least one tackifying resin (T2) selected from the group consisting of rosin ester-based resins, terpene-based resins, and petroleum-based resins.

12. 12. The pressure-sensitive adhesive composition according to claim 11, wherein the content of the tackifier resin (T2) is 10 parts by weight or more and 100 parts by weight or less per 100 parts by weight of the base polymer.

13. The pressure-sensitive adhesive composition according to any one of claims 1 to 12, wherein the base polymer is an acrylic polymer.

14. The pressure-sensitive adhesive composition according to claim 13, wherein the acrylic polymer has a structural unit derived from a monomer having a crosslinkable functional group.

15. 15. The pressure-sensitive adhesive composition according to claim 14, wherein the acrylic polymer contains 0.01 wt % or more and 20 wt % or less of the structural unit derived from the monomer having a crosslinkable functional group.

16. 16. The pressure-sensitive adhesive composition according to claim 13, 14 or 15, wherein the acrylic polymer has a weight-average molecular weight of 200,000 or more and 2,000,000 or less.

17. The pressure-sensitive adhesive composition according to any one of claims 1 to 12, wherein the base polymer is a block copolymer having a block derived from a styrene-based monomer and a block derived from a conjugated diene-based monomer, or a styrene-based elastomer which is a hydrogenated product thereof.

18. 18. The pressure-sensitive adhesive composition according to claim 17, wherein the styrene-based elastomer is a styrene-isoprene-styrene (SIS) block copolymer or a styrene-butadiene-styrene (SBS) block copolymer.

19. 19. The pressure-sensitive adhesive composition according to claim 17, wherein the styrene-based elastomer has a diblock ratio of 50% by weight or more.

20. 20. The pressure-sensitive adhesive composition according to claim 17, 18 or 19, wherein the styrene elastomer has a styrene content of 20% by weight or less.

21. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to any one of claims 1 to 20.

22. 17. A pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to claim 13, 14, 15 or 16, wherein the pressure-sensitive adhesive layer has a shear storage modulus of 1.0 x 10 at 25°C measured at a measurement frequency of 10 Hz using a dynamic viscoelasticity measuring device. ４ Pa or more, 5.0×10 ５ 22. The adhesive tape according to claim 21, wherein the elastic modulus is 0.05 Pa or less.

23. The pressure-sensitive adhesive tape according to claim 22, wherein the pressure-sensitive adhesive layer has a loss tangent that peaks at a temperature between -20°C and 20°C, as measured at a measurement frequency of 10 Hz using a dynamic viscoelasticity measuring device.

24. 24. The adhesive tape according to claim 21, 22 or 23, which is used for fixing electronic equipment parts or vehicle-mounted parts.

25. A pressure-sensitive adhesive composition comprising a base polymer and a compound (T1), The compound (T1) is a copolymer having a structural unit (A) and a structural unit (B) represented by the following formula: 【Transformation 6】 (In the formula, A represents the structural unit (A), B represents the structural unit (B), and s and t each represent an integer of 1 or greater. * represents a linking moiety.) the structural unit (A) is derived from a monomer (a) having a solvation free energy Δμ with polytetrafluoroethylene of −30 kcal / mol or less; the structural unit (B) is derived from at least one monomer (b) selected from the group consisting of terpene-based monomers, vinyl-based monomers, and conjugated diene-based monomers, The structural unit (A) is at least one selected from the group consisting of structural units (A-2), (A-3), and (A-4) represented by the following formulas: 【Transformation 7】 【Transformation 8】 【Chemistry 9】 (In the formula, R ２ , R ３ and R ５ respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. R ４ respectively represent an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. The polar functional group is any one of an amino group, a carboxyl group, a carbonyl group, an alkoxy group, a hydroxyl group, a nitrile group, and a nitro group, and in the case of the structural unit (A-2), a carboxyl group is not contained, in the case of the structural unit (A-3), an alkoxy group is not contained, and in the case of the structural unit (A-4), an amino group is not contained. R ６ and R ７ represents a hydrogen atom or an aliphatic hydrocarbon group. m represents an integer of 1 or more and 4 or less. l represents an integer of 2 or more and 4 or less. k represents an integer of 1 or more and 4 or less.

26. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to claim 25.

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