Compound, method for manufacturing compound, adhesive composition, and adhesive tape

Abstract

To provide a compound that can increase bond strength of an adhesive composition, particularly can increase bond strength even to an adherend having low polarity, a method for manufacturing the compound, an adhesive composition containing the compound, and an adhesive tape having an adhesive layer containing the adhesive composition.SOLUTION: A compound has at least one kind of constitutional unit (A) selected from the group consisting of constitutional unit (A-1) and constitutional unit (A-1') expressed by the following formula, and a constitutional unit (B) derived from at least one kind monomer (b) selected from the group consisting of terpene-based monomer and vinyl-based monomer. In the formula, R1 severally denotes an aliphatic hydrocarbon group having a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group and a polar functional group, or an aromatic hydrocarbon group having a polar functional group, n denotes an integer of 2 or more and 4 or less, and n' denotes an integer of 2 or more and 5 or less.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Conventionally, when fixing components in electronic devices, adhesive tapes have been widely used. Specifically, for example, an adhesive tape is used 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 and a display panel module. For the adhesive tape used for fixing such electronic device components, in addition to high adhesiveness, functions such as heat resistance, thermal conductivity, and impact resistance are required according to the environment of the site where it is used (for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] An adhesive composition in which an adhesion-imparting resin is added to a base polymer is known for the purpose of improving adhesiveness. The adhesion-imparting resin usually changes the mechanical properties, surface polarity, etc. of the bulk of the base polymer to improve the adhesive strength.

[0005] In recent years, the applications of adhesive tapes have expanded, and higher performance is required for adhesive compositions. For example, the adhesive tapes used for fixing electronic device components are becoming thinner, and it is required to have high adhesive strength even when they are thinner. Also, the adherends have become diversified, and more difficult-to-adhere adherends, that is, relatively low-polarity adherends such as adherends made of polyolefin resins, etc., are also being used. In such cases, there may arise a problem that sufficient adhesive strength cannot be obtained with conventional adhesive compositions.

[0006] An object of the present invention is to provide a compound that can enhance the adhesive strength of an adhesive composition, and in particular, can enhance the adhesive strength even for a low-polarity adherend. Another object of the present invention is to provide a method for producing the compound, an adhesive composition containing the compound, and an adhesive tape having an adhesive layer containing the adhesive composition.

Means for Solving the Problems

[0007] The present invention is a compound having at least one structural unit (A) selected from the group consisting of a structural unit (A-1) and a structural unit (A-1’) represented by the following formula. The present invention will be described in detail below.

[0008]

Chemical formula

[0009] 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, 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.

[0010] The inventors of the present invention have succeeded in producing a novel compound having a specific structural unit (A) having a phenolic hydroxyl group. The inventors have found that by blending such a compound as a tackifying resin into an adhesive composition, the adhesive strength of the adhesive composition can be increased, and in particular, the adhesive strength can be increased even with respect to a substrate having a low polarity, and thus the present invention has been completed.

[0011] The compound of the present invention has at least one structural unit (A) selected from the group consisting of a structural unit (A-1) and a structural unit (A-1') represented by the following formula. By having such a structural unit (A) having a phenolic hydroxyl group, the compound of the present invention can increase the adhesive strength of the adhesive composition, and in particular, since the interaction with a substrate having a low polarity can be greatly improved, the adhesive strength can be increased even with respect to a substrate having a low polarity. Therefore, the compound of the present invention is suitably used as a tackifying resin to be blended into an adhesive composition. The compound of the present invention may have at least one structural unit (A) selected from the group consisting of a structural unit (A-1) and a structural unit (A-1') represented by the following formula in the side chain, or may have it in the main chain skeleton or at the end of the main chain skeleton. Among them, since the compound of the present invention can have suitable physical properties required when used as a tackifying resin, the compound of the present invention preferably has at least one structural unit (A) selected from the group consisting of a structural unit (A-1) and a structural unit (A-1') represented by the following formula in the main chain skeleton or at the end of the main chain skeleton.

[0012]

Chemical formula

[0013] 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, 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 connecting portion.

[0014] In the above structural unit (A), 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. The above aliphatic hydrocarbon group is not particularly limited, and examples thereof include linear, branched or cyclic alkyl groups having 1 to 20 carbon atoms. The above aromatic hydrocarbon group is not particularly limited, and examples thereof include substituted or unsubstituted aryl groups having 1 to 20 carbon atoms. The above 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, a nitro group and the like. The aliphatic hydrocarbon group having the above polar functional group is not particularly limited, and for example, a group in which one or more hydrogens in the above aliphatic hydrocarbon group are substituted with the above polar functional group can be used. The aromatic hydrocarbon group having the above polar functional group is also not particularly limited, and for example, a group in which one or more hydrogens in the above aromatic hydrocarbon group are substituted with the above polar functional group can be used. In the compound of the present invention, the plurality of R 1 contained in one structural unit (A) may be the same or different from each other. Also, the plurality of R 1 contained in different structural units (A) may be the same or different from each other.

[0015] In the above structural unit (A), n is an integer of 2 or more and 4 or less, and n' is not particularly limited as long as it is an integer of 2 or more and 5 or less, but from the viewpoint of easy availability of raw materials, it is preferable that n and n' are 2 or 3. Since the adhesive strength of the adhesive composition can be further increased, and in particular, the adhesive strength can be further increased even for a low-polarity adherend, it is more preferable that n and n' are 3.

[0016] More specifically, examples of the above structural unit (A) include structural units derived from dihydroxybenzene or its derivatives (when n and n' are 2), structural units derived from trihydroxybenzene or its derivatives (when n and n' are 3), and the like. These structural units may be used alone or in combination of two or more. The above dihydroxybenzene or its derivatives are not particularly limited. Examples include resorcinol, pyrocatechol, hydroquinone, dihydroxytoluene, dihydroxyxylene, dihydroxyphenylethylamine hydrochloride, dihydroxybenzoic acid, dihydroxyphenylacetic acid, dihydroxyhydrocinnamic acid, dihydroxyphenylpropionic acid, dihydroxyphenylalanine, dihydroxybenzaldehyde, dihydroxyacetophenone, diacetyldihydroxybenzene, dihydroxyphenyl-2-butanone, methyl dihydroxyphenylacetate, benzyldihydroxyphenylketone, dihydroxybenzamide, dihydroxymethoxybenzene, dihydroxybenzyl alcohol, dihydroxyphenylethanol, dihydroxyphenylglycol, dihydroxyphenylacetonitrile, dihydroxynitrobenzene, and the like. These dihydroxybenzenes or their derivatives may be used alone or in combination of two or more. Among them, pyrocatechol is preferred because it has less steric hindrance and easily interacts with the adherend. The above-mentioned trihydroxybenzene or its derivative is not particularly limited. For example, 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, trihydroxynitrobenzene, etc. may be mentioned. These trihydroxybenzenes or their derivatives may be used alone or two or more of them may be used in combination. Among them, pyrogallol is preferable because it has less steric hindrance and easily interacts with the adherend.

[0017] The above-mentioned structural unit (A) may consist only of petroleum-derived materials, but preferably contains bio-derived materials. The depletion of petroleum resources and the emission of carbon dioxide due to the combustion of petroleum-derived products have been regarded as problems. Therefore, attempts have been made to save petroleum resources by using bio-derived materials instead of petroleum-derived materials. If the above-mentioned structural unit (A) contains bio-derived materials, it is preferable from the viewpoint of saving petroleum resources. In addition, if the above-mentioned structural unit (A) contains bio-derived materials, since bio-derived materials are originally produced by taking in carbon dioxide in the atmosphere, it is considered that even if they are burned, the total amount of carbon dioxide in the atmosphere will not increase, and it is also preferable from the viewpoint of reducing the amount of carbon dioxide emissions. Examples of the monomer constituting the above-mentioned structural unit (A) containing a bio-derived 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, trihydroxynitrobenzene, and the like.

[0018] The content rate of the above-mentioned structural unit (A) in the compound of the present invention is not particularly limited, but the preferable lower limit is 1 mol%, and the preferable upper limit is 60 mol%. If the content rate of the above-mentioned structural unit (A) is 1 mol% or more, the adhesive strength of the adhesive composition can be further increased by blending the compound into the adhesive composition. In particular, the adhesive strength can be further increased even with respect to a substrate having a low polarity. If the content rate of the above-mentioned structural unit (A) is 60 mol% or less, the compound can have suitable physical properties required when used as a tackifying resin. The more preferable lower limit of the content rate of the above-mentioned structural unit (A) is 5 mol%, and the more preferable upper limit is 50 mol%. The further preferable lower limit is 10 mol%, and the further preferable upper limit is 30 mol%.

[0019] The compound of the present invention is not particularly limited as long as it is a compound having the above-mentioned structural unit (A), but is preferably a polymer having the above-mentioned structural unit (A), and more preferably a copolymer having the above-mentioned structural unit (A) and other structural units. In the case of a copolymer, the above-mentioned structural unit (A) and other structural units may be copolymerized randomly, or may be copolymerized regularly or periodically, for example, in such a case that each forms a block segment and then the block segments are bonded to each other. The compound of the present invention preferably further has an aliphatic hydrocarbon group having an unsaturated double bond. In this case, the compound of the present invention may have the aliphatic hydrocarbon group having the unsaturated double bond in the above structural unit (A) or in other structural units. Among them, from the viewpoint of ease of synthesis and the compatibility between the compound and the base polymer, particularly from the viewpoint of improving the compatibility between the compound and the styrene-based elastomer, it is preferable that the aliphatic hydrocarbon group having the unsaturated double bond is contained in other structural units.

[0020] The above other structural units are not particularly limited, but a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene-based monomers, vinyl-based monomers, and conjugated diene-based monomers is preferable. That is, in addition to the above structural unit (A), the compound of the present invention more preferably further has a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene-based monomers, vinyl-based monomers, and conjugated diene-based monomers. By having the above structural unit (B), the compound can have suitable physical properties required when used as a tackifier resin. Among them, since the adhesive strength of the adhesive composition can be further increased by blending the compound into the adhesive composition, a structural unit derived from a terpene-based monomer or a structural unit derived from a vinyl-based monomer is preferable, and it is also preferable to use in combination a structural unit derived from a terpene-based monomer and a structural unit derived from a vinyl-based monomer. Further, from the viewpoint of improving the compatibility between the compound and the base polymer, particularly the compatibility between the compound and the styrene-based elastomer, a structural unit derived from a terpene-based monomer or a structural unit derived from a conjugated diene-based monomer is preferable. Since these structural units have an aliphatic hydrocarbon group having the unsaturated double bond, when the compound has these structural units, the compatibility between the compound and the base polymer, particularly the compatibility between the compound and the styrene-based elastomer, is improved, and it is possible to suppress a decrease in the adhesive strength of the adhesive composition due to deterioration of the compatibility.

[0021] The above terpene monomer is not particularly limited, and examples thereof include α-pinene, β-pinene, limonene, dipentene, δ-3-carene, dimethyloctatriene, alloocimene, myrcene, ocimene, linalool, cosmen, etc. Among them, α-pinene, β-pinene or limonene is preferable because the adhesive strength of the adhesive composition can be further increased by blending the compound into the adhesive composition. The above 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 having no structure containing two or more aromatic rings in one molecule (for example, naphthalene structure, anthracene structure, biphenyl structure, anthraquinone structure, benzophenone structure, etc.) is preferable. Examples of the vinyl monomer having no 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, 2-phenyl-2-butene, etc. Among them, styrene is preferable because the adhesive strength of the adhesive composition can be further increased by blending the compound into the adhesive composition. The above conjugated diene monomer is not particularly limited, and examples thereof include butadiene, isoprene, piperylene, cyclopentadiene, etc. Among them, isoprene is preferable because the adhesive strength of the adhesive composition can be further increased by blending the compound into the adhesive composition. These monomers (b) may be used alone or in combination of two or more.

[0022] The above-mentioned structural unit (B) may consist only of petroleum-derived materials, but preferably contains bio-derived materials. The depletion of petroleum resources and the emission of carbon dioxide due to the combustion of petroleum-derived products are regarded as problems. Therefore, attempts have been made to save petroleum resources by using bio-derived materials instead of petroleum-derived materials. If the above-mentioned structural unit (B) contains bio-derived materials, it is preferable from the viewpoint of saving petroleum resources. In addition, if the above-mentioned structural unit (B) contains bio-derived materials, since bio-derived materials are originally produced by taking in carbon dioxide in the atmosphere, it is considered that even if they are burned, the total amount of carbon dioxide in the atmosphere will not increase, and it is also preferable from the viewpoint of reducing the carbon dioxide emission amount. Examples of the monomer (b) constituting the above-mentioned structural unit (B) containing bio-derived materials include terpene-based monomers, ethylene, propylene, hexene, butadiene, isoprene, and the like.

[0023] The content of the above-mentioned structural unit (B) in the compound of the present invention is not particularly limited, but the preferable lower limit is 40 mol%, and the preferable upper limit is 99 mol%. If the content of the above-mentioned structural unit (B) is 40 mol% or more, the compound can have suitable physical properties required when used as a tackifier resin. If the content of the above-mentioned structural unit (B) is 99 mol% or less, the content of the above-mentioned structural unit (A) can be sufficiently ensured. Therefore, by blending the compound into the adhesive composition, the adhesive strength of the adhesive composition can be further increased. In particular, the adhesive strength can be further increased even for a substrate with low polarity. The more preferable lower limit of the content of the above-mentioned structural unit (B) is 50 mol%, and the more preferable upper limit is 90 mol%.

[0024] When the compound of the present invention has the above-mentioned structural unit (A) and the above-mentioned structural unit (B), it 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 later, and can further increase the adhesive strength of the adhesive composition. In particular, the adhesive strength can be further increased even for a substrate with low polarity.

[0025] [Chemical formula]

[0026] 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 more. Note that * represents the connecting part.

[0027] In addition, examples of the other structural units include structural units derived from other phenolic monomers not included in the above structural unit (A), structural units derived from maleic anhydride, and the like. The other phenolic monomers are not particularly limited. For example, they include phenol, cresol, xylenol, propylphenol, nonylphenol, methoxyphenol, bromophenol, bisphenol A, bisphenol F, bisphenol S, dihydroxynaphthalene, and the like. These other phenolic monomers may be used alone or in combination of two or more.

[0028] The molecular weight of the compound of the present invention is not particularly limited, but the preferable lower limit of the weight average molecular weight (Mw) is 400, and the preferable 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 tackifying resin. The more preferable lower limit of the weight average molecular weight (Mw) is 500, the more preferable upper limit is 5000, the further preferable lower limit is 700, and the further preferable upper limit is 3000. To adjust the weight average molecular weight (Mw) to the above range, for example, the composition of the compound, the polymerization method, the polymerization conditions, etc. may be adjusted.

[0029] Note that the weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) as described later can be measured by the following method. Filter the solution of the compound through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm). Supply the obtained filtrate to a gel permeation chromatograph (for example, Waters 2690 Separations Model), perform GPC measurement under the conditions of a sample flow rate of 1 milliliter / min and a column temperature of 40 °C, measure the polystyrene-reduced molecular weight of the compound, and determine the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn). As the column, for example, GPC KF-802.5L (manufactured by Showa Denko KK) is used, and as the detector, a differential refractometer is used.

[0030] The Young's modulus of the compound of the present invention is not particularly limited, but the preferable 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 appropriate hardness and can have suitable physical properties required when used as a tackifier resin rather than an adhesive. The more preferable lower limit of the Young's modulus at 25 °C is 50 MPa, and the further preferable 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 suppressing the adhesive composition containing the compound from becoming too hard and reducing the adhesive strength, the preferable upper limit is 10,000 MPa, and the more preferable upper limit is 5,000 MPa. In order to adjust the Young's modulus at 25 °C within the above range, for example, the molecular weight of the compound, the composition and content of the above structural unit (A) and the above structural unit (B) in the compound may be adjusted. The Young's modulus at 25 °C can be measured by performing a tensile test using a tensile test apparatus (for example, Tensilon manufactured by ORIENTEC) under the conditions of a tensile speed of 200 mm / min, a distance between grips of 15 mm, and a temperature of 25 °C. The measurement sample at this time can be prepared, for example, by filling the compound into a mold of 10 × 50 mm size, melting it at a temperature 100 °C higher than the glass transition temperature, and producing a test piece with a thickness of 1 mm.

[0031] The glass transition temperature of the compound of the present invention is not particularly limited, but preferably has a lower limit of 0 °C and a upper limit of 200 °C. If the glass transition temperature is within the above range, the compound can easily adjust the Young's modulus within the above range and can have suitable physical properties required when used as a tackifying resin. A more preferable lower limit of the glass transition temperature is 10 °C, and a more preferable upper limit is 150 °C. Note that the glass transition temperature can be the value obtained in the 1st run when measured using a differential scanning calorimeter (for example, SII Exstar 6000 / DSC 6220 manufactured by Hitachi High-Technologies Corporation) under a nitrogen atmosphere at a heating rate of 10 °C / min.

[0032] The iodine value of the compound of the present invention is not particularly limited, but preferably has a lower limit of 2 g / 100 g and an upper limit of 180 g / 100 g. If the iodine value is 2 g / 100 g or more, it is possible to suppress a decrease in the adhesive strength of the adhesive composition due to deterioration in the compatibility between the compound and the base polymer, particularly the compatibility between the compound and the styrene-based elastomer. If the iodine value is 180 g / 100 g or less, the adhesive strength of the adhesive composition can be further increased by blending the compound into the adhesive composition, and in particular, the adhesive strength can be further increased even for a low-polarity adherend. A more preferable lower limit of the iodine value is 70 g / 100 g, and a more preferable upper limit is 170 g / 100 g. Note that the iodine value is an index indicating the amount of unsaturated double bonds (C=C bond amount) and refers to the value measured according to the method described in "JIS K 0070:1992".

[0033] The content ratio of bio-derived carbon (carbon atoms) in the carbon (carbon atoms) in the compound of the present invention is not particularly limited, but preferably the content ratio of bio-derived carbon in the carbon is 10% or more. The content ratio of bio-derived carbon being 10% or more serves as a criterion for a "bio-based product". If the content rate of the carbon derived from the above-mentioned organism is 10% or more, it is preferable from the viewpoints of saving petroleum resources and reducing carbon dioxide emissions. The more preferable lower limit of the content rate of the carbon derived from the above-mentioned organism is 30%, the further preferable lower limit is 60%, the even more preferable lower limit is 70%, and the still more preferable lower limit is 90%. The upper limit of the content rate of the carbon derived from the above-mentioned organism is not particularly limited and may be 100%. In addition, a certain proportion of radioactive isotope (C-14) is contained in the carbon derived from the organism, while the carbon derived from petroleum contains almost no C-14. Therefore, the content rate of the carbon derived from the above-mentioned organism can be calculated by measuring the concentration of C-14 contained in the compound. Specifically, it can be measured according to ASTM D6866-20, which is a standard used in many bioplastic industries.

[0034] The compound of the present invention also includes a hydrogenated product of the compound as described above. The hydrogenated product is a compound in which the carbon-carbon double bond existing in the compound as described above is saturated by hydrogenation. Even such a hydrogenated product is suitably used as a tackifier resin to be blended in the adhesive composition, and can increase the adhesive strength of the adhesive composition. In particular, it can increase the adhesive strength even to a substrate with low polarity.

[0035] The method for producing the compound of the present invention is not particularly limited. For example, the following method is preferable. That is, at least one structural unit (A) selected from the group consisting of the structural unit (A-1) and the structural unit (A-1') represented by the following formula, 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. It is a method for producing a compound having a copolymerization of the monomer (a) represented by the following formula and the monomer (b). Such a method for producing a compound is also one of the present inventions.

[0036]

Chemical formula

[0037] [Chemical formula]

[0038] 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; n represents an integer of 2 or more and 4 or less; n' represents an integer of 2 or more and 5 or less; n'' represents an integer of 2 or more and 5 or less. Here, * represents a connecting part. It is preferable that the above n'' is 2 or 3, and more preferably 3.

[0039] In the method for producing the compound of the present invention, it is preferable to copolymerize the above monomer (a) and the above monomer (b) by cationic polymerization. By using cationic polymerization, the monomer (a) and the monomer (b) can be copolymerized without previously protecting the phenolic hydroxyl group of the monomer (a) by chemical modification, and subsequent deprotection is also unnecessary. Therefore, the monomer (a) and the monomer (b) can be copolymerized by a simpler one-step reaction process, leading to a reduction in impurities and an improvement in yield.

[0040] As a method for copolymerizing the above monomer (a) and the above monomer (b) by cationic polymerization, a method of reacting the above monomer (a) and the above monomer (b) in the presence of a Lewis acid is preferable. According to such a method, it is considered that cations of the monomer (b) are generated, cationic polymerization of the monomer (b) proceeds, and a Friedel-Crafts alkylation reaction between the monomer (a) and the monomer (b) proceeds. By such reactions occurring repeatedly, a copolymer having a structural unit (A) derived from the monomer (a) and a structural unit (B) derived from the monomer (b) can be obtained. The above Lewis acid is not particularly limited, and a conventionally known Lewis acid can be used. For example, aluminum chloride (AlCl 3) Diethylaluminum chloride (Et 2 AlCl 2 ), tin(IV) chloride (SnCl 4 ), titanium(IV) chloride (TiCl 4 ), boron trichloride (BCl 3 ), boron trifluoride ether complex (BF 3 ·EtO), etc. are mentioned. Among them, aluminum chloride (AlCl 3 ) is preferable because a higher yield can be obtained.

[0041] More specifically, for example, when pyrogallol is used as the above monomer (a) and α-pinene is used as the above monomer (b), and these are reacted in the presence of aluminum chloride (AlCl 3 ) which is a Lewis acid, the reaction shown in the following scheme is considered to proceed. That is, a cation of α-pinene which is the above monomer (b) is generated, and cationic polymerization of α-pinene proceeds (upper stage of the following scheme), and at the same time, the Friedel-Crafts alkylation reaction between pyrogallol which is the above monomer (a) and α-pinene which is the above monomer (b) proceeds (middle stage of the following scheme). By such reactions occurring repeatedly, a copolymer having a structural unit derived from pyrogallol and a structural unit derived from α-pinene can be obtained (lower stage of the following scheme). Note that such a copolymer has a structural unit derived from pyrogallol in the main chain skeleton or at the end of the main chain skeleton.

[0042]

Chemical formula

[0043] In the formula, s and t each represent an integer of 1 or more. Note that * represents a connecting part.

[0044] The compound of the present invention can be suitably used as a tackifying resin to be blended in an adhesive composition. An adhesive composition containing a base polymer and the compound (T1) of the present invention is also one of the present inventions. 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 if it is a small amount compared to conventional tackifier resins, the adhesive strength of the pressure-sensitive adhesive composition can be increased. The preferable lower limit with respect to 100 parts by weight of the base polymer is 1 part by weight, and the preferable upper limit is 35 parts by weight. If 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. In particular, the adhesive strength can be further increased even with respect to a substrate having low polarity. If the content of the compound (T1) of the present invention is 35 parts by weight or less, it is possible to suppress the pressure-sensitive adhesive composition from becoming too hard and the adhesive strength from decreasing. The more preferable lower limit of the content of the compound (T1) of the present invention is 3 parts by weight, and the more preferable upper limit is 30 parts by weight. The further preferable lower limit is 5 parts by weight, and the further preferable upper limit is 20 parts by weight.

[0045] The pressure-sensitive adhesive composition of the present invention may further contain at least one tackifier resin (T2) selected from the group consisting of rosin ester resins, terpene resins, and petroleum resins. Among them, a rosin ester resin or a terpene resin is preferable because the adhesive strength of the pressure-sensitive adhesive composition can be further increased.

[0046] The preferable lower limit of the softening temperature of the above-mentioned tackifier resin (T2) is 70°C, and the preferable upper limit is 170°C. If the softening temperature is 70°C or higher, it is possible to suppress the pressure-sensitive adhesive composition from becoming too soft and the adhesive strength from decreasing. If the softening temperature is 170°C or lower, the wettability of the interface of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is improved, and it is possible to suppress interface peeling. The more preferable lower limit of the softening temperature is 120°C. The softening temperature is the softening temperature measured by the JIS K2207 ring method.

[0047] The preferable lower limit of the hydroxyl value of the above-mentioned tackifier resin (T2) is 25, and the preferable upper limit is 150. 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 it is possible to suppress interface peeling. The more preferable lower limit of the hydroxyl value is 30, and the more preferable upper limit is 130. Incidentally, the hydroxyl value can be measured by JIS K1557 (phthalic anhydride method).

[0048] The content of the tackifier resin (T2) is not particularly limited, but the preferable lower limit with respect to 100 parts by weight of the base polymer is 10 parts by weight, and the preferable upper limit is 100 parts by weight. If the content of the tackifier resin (T2) is 10 parts by weight or more, the adhesive strength of the adhesive composition can be further increased. If the content of the tackifier resin (T2) is 100 parts by weight or less, it is possible to suppress the adhesive composition from becoming too hard and the adhesive strength from decreasing. The more preferable lower limit of the content of the tackifier resin (T2) is 15 parts by weight, the more preferable upper limit is 60 parts by weight, the further preferable upper limit is 50 parts by weight, and the even more preferable upper limit is 40 parts by weight.

[0049] The base polymer is not particularly limited, and examples thereof include acrylic polymers, rubber polymers, urethane polymers, and silicone polymers. Among them, acrylic polymers are preferable because they are relatively stable against light, heat, moisture, etc. Also, rubber polymers are preferable because they have little adherend selectivity, can adhere to various adherends, and are difficult to peel from the adherend even when immersed in an alkaline chemical solution. Among the above 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 products thereof, are more preferable.

[0050] 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 1 to 12 carbon atoms in the alkyl group and (meth)acrylic acid alkyl esters having 13 to 18 carbon atoms in the alkyl group from the viewpoint of improving the initial tack and having good adhesiveness at low temperatures. Examples of the (meth)acrylic acid alkyl ester having an alkyl group with 1 to 12 carbon atoms include 2-ethylhexyl (meth)acrylate, butyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and the like. Examples of the (meth)acrylic acid alkyl ester having an alkyl group with 13 to 18 carbon atoms include tridecyl methacrylate, stearyl (meth)acrylate, and the like. Among them, since the acrylic polymer can exhibit high adhesiveness, it is preferable to use 2-ethylhexyl (meth)acrylate or butyl (meth)acrylate. The content of the structural unit derived from at least one selected from the group consisting of the (meth)acrylic acid alkyl ester having an alkyl group with 1 to 12 carbon atoms and the (meth)acrylic acid alkyl ester having an alkyl group with 13 to 18 carbon atoms in the acrylic polymer is not particularly limited. The preferable lower limit of the content is 10% by weight, the preferable upper limit is 100% by weight, the more preferable lower limit is 30% by weight, the more preferable upper limit is 95% by weight, the further preferable lower limit is 50% by weight, and the further preferable upper limit is 90% by weight. By setting the content within such a range, the acrylic polymer can exhibit high adhesiveness.

[0051] The acrylic polymer preferably has a structural unit derived from a monomer having a crosslinkable functional group. When the acrylic polymer has a structural unit derived from a monomer having a crosslinkable functional group, and a crosslinking agent is added, a crosslinked structure of the acrylic polymer is formed in the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. As a result, the gel fraction and bulk strength of the pressure-sensitive adhesive layer increase, and the adhesive strength is improved. 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, an isocyanate group, and the like.

[0052] Specific examples of the monomer having the crosslinkable functional group include, for example, hydroxyalkyl (meth)acrylate, glycerin dimethacrylate, glycidyl (meth)acrylate, 2-methacryloyloxyethyl isocyanate, (meth)acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid, fumaric acid, etc. More specific examples of the hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, etc. These monomers having crosslinkable functional groups may be used alone or in combination of two or more. Among them, from the viewpoint of increasing the gel fraction and bulk strength of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, monomers having a hydroxyl group such as hydroxyalkyl (meth)acrylate and glycerin dimethacrylate, or monomers having a carboxyl group such as (meth)acrylic acid are preferable.

[0053] The content of the structural unit derived from the monomer having the crosslinkable functional group in the acrylic polymer is not particularly limited, but the preferable lower limit is 0.01% by weight and the preferable upper limit is 20% by weight. By setting the content of the structural unit derived from the monomer having the 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 increase, and the adhesive strength improves. The more preferable lower limit of the content of the structural unit derived from the monomer having the crosslinkable functional group is 0.05% by weight, and the more preferable upper limit is 5% by weight.

[0054] The acrylic polymer may optionally contain a structural unit derived from a copolymerizable other polymerizable monomer other than the structural unit derived from the alkyl (meth)acrylate and the structural unit derived from the monomer having the crosslinkable functional group as described above.

[0055] To obtain the above acrylic polymer, a mixture of monomers as described above may be subjected to a radical reaction in the presence of a polymerization initiator. As a method for subjecting the above monomer mixture to a radical reaction, that is, a polymerization method, a conventionally known method is used, and examples thereof include solution polymerization (boiling point polymerization or isothermal polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, and the like.

[0056] The weight average molecular weight (Mw) of the above acrylic polymer is not particularly limited, but the preferable lower limit is 200,000 and the preferable upper limit is 2,000,000. If the above weight average molecular weight (Mw) is 200,000 or more, the strength of the bulk of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition increases, and the adhesive strength improves. If the above weight average molecular weight (Mw) is 2,000,000 or less, the wettability of the interface of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition improves, and it is possible to suppress interface peeling. A more preferable lower limit of the above weight average molecular weight (Mw) is 400,000, and a more preferable upper limit is 1,500,000.

[0057] The ratio (molecular weight distribution, Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the above acrylic polymer is not particularly limited, but the preferable lower limit is 1.05 and the preferable upper limit is 5.0. When Mw / Mn is 5.0 or less, the proportion of low molecular components is suppressed, the strength of the bulk of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition increases, and the adhesive strength improves. A more preferable upper limit of Mw / Mn is 4.5, a further preferable upper limit is 4, and a still more preferable upper limit is 3.5. To adjust the above weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) within the above ranges, for example, the composition, polymerization method, polymerization conditions, etc. of the above acrylic polymer may be adjusted.

[0058] The above styrenic elastomer may be a block copolymer having rubber elasticity at room temperature and having a hard segment portion and a soft segment portion. Note that the block derived from the above styrenic monomer is the hard segment portion, and the block derived from the above conjugated diene monomer is the soft segment portion.

[0059] The above styrene monomers are not particularly limited. For example, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinyl ethylbenzene, 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, tertiary amino group-containing diphenylethylene, etc. may be mentioned. The above tertiary amino group-containing diphenylethylene is not particularly limited. For example, 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene, etc. may be mentioned. These styrene monomers may be used alone or two or more of them may be used in combination.

[0060] The above conjugated diene monomers are not particularly limited. For example, 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. may be mentioned. These conjugated diene monomers may be used alone or two or more of them may be used in combination.

[0061] As the styrenic elastomer, specifically, for example, styrene-isoprene-styrene (SIS) block copolymer, styrene-butadiene-styrene (SBS) block copolymer, styrene-chloroprene-styrene block copolymer, etc. can be mentioned. Among them, since it is easy to exhibit high adhesive strength and is difficult to peel from the adherend even when immersed in an alkaline chemical solution, SIS block copolymer and SBS block copolymer are preferred, and SIS block copolymer is more preferred. These styrenic elastomers may be used alone or in combination of two or more.

[0062] In addition to the triblock copolymer of the block derived from the styrenic monomer and the block derived from the conjugated diene monomer, the styrenic elastomer may contain a diblock copolymer of the block derived from the styrenic monomer and the block derived from the conjugated diene monomer. The content of the diblock copolymer in the styrenic elastomer (hereinafter, also referred to as "diblock ratio") is not particularly limited, but the preferred lower limit is 50% by weight, and the more preferred lower limit is 70% by weight. If the diblock ratio is within the above range, the adhesion of the pressure-sensitive adhesive composition to the adherend becomes high 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 force of the pressure-sensitive adhesive composition, the 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) method.

[0063] The content of the block derived from the styrenic monomer in the styrenic elastomer (hereinafter, also referred to as "styrene content") is not particularly limited, but the preferred upper limit is 20% by weight, and the more preferred upper limit is 16% by weight. If the styrene content is within the above range, the pressure-sensitive adhesive composition does not become too hard, the adhesion to the adherend becomes high, and the adhesive strength is improved. The lower limit of the styrene content is not particularly limited, but from the viewpoint of maintaining the cohesive force of the pressure-sensitive adhesive composition, the preferred lower limit is 8% by weight. The styrene content can be calculated from the peak area ratio of each block measured by 1 1H-NMR.

[0064] The weight average molecular weight of the above styrene-based elastomer is not particularly limited, but the preferable lower limit is 50,000 and the preferable upper limit is 600,000. If the above weight average molecular weight is 50,000 or more, the strength of the bulk of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition increases, and the adhesive strength improves. If the above weight average molecular weight is 600,000 or less, it is possible to prevent the compatibility between the above styrene-based elastomer and other components from decreasing too much. The more preferable lower limit of the above weight average molecular weight is 100,000, and the more preferable upper limit is 500,000.

[0065] When the base polymer of the pressure-sensitive adhesive composition of the present invention is the above acrylic polymer, it is preferable to contain a crosslinking agent. By adjusting the type and amount of the above crosslinking agent, it becomes easier to adjust the gel fraction of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. The above 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-type crosslinking agents. Among them, isocyanate-based crosslinking agents are preferable. The content of the above crosslinking agent has a preferable lower limit of 0.01 part by weight and a preferable upper limit of 10 parts by weight, and a more preferable lower limit of 0.1 part by weight and a more preferable upper limit of 5 parts by weight with respect to 100 parts by weight of the above acrylic polymer.

[0066] The pressure-sensitive adhesive composition of the present invention may contain a silane coupling agent for the purpose of improving the adhesive strength. The above silane coupling agent is not particularly limited, and examples thereof include epoxy silanes, acrylic silanes, methacrylic silanes, amino silanes, and isocyanate silanes.

[0067] The pressure-sensitive adhesive composition of the present invention may contain a coloring material for the purpose of imparting light-shielding properties. The coloring material is not particularly limited, and examples thereof include carbon black, aniline black, titanium oxide, and the like. Among them, carbon black is preferable because it is relatively inexpensive and chemically stable.

[0068] 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, if necessary.

[0069] A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition of the present invention is also one of the present inventions. When the base polymer is the acrylic polymer, the gel fraction of the pressure-sensitive adhesive layer is not particularly limited, but the preferable lower limit is 10% by weight and the preferable upper limit is 70% by weight. If the gel fraction is 10% by weight or more, the strength of the bulk of the pressure-sensitive adhesive layer increases and the adhesive strength improves. If the gel fraction is 70% by weight or less, the wettability of the interface of the pressure-sensitive adhesive layer improves, and it is possible to suppress interface peeling. The more preferable lower limit of the gel fraction is 15% by weight, the more preferable upper limit is 60% by weight, the further preferable lower limit is 20% by weight, and the further preferable upper limit is 50% by weight. The gel fraction of the pressure-sensitive adhesive layer can be adjusted within the above range, for example, by adjusting the composition, weight average molecular weight, etc. of the acrylic polymer, or by adjusting the type and amount of the cross-linking agent.

[0070] The gel fraction of the pressure-sensitive adhesive layer can be measured by the following method. Cut the pressure-sensitive adhesive tape into a flat rectangular shape of 50 mm × 100 mm to prepare a test piece. After immersing the test piece in ethyl acetate at 23°C for 24 hours, take it out from ethyl acetate and dry it under the condition of 110°C for 1 hour. Measure the weight of the dried test piece, and calculate the gel fraction using the following formula (1). Note that the test piece is not laminated with a release film for protecting the pressure-sensitive adhesive layer. Gel fraction (% by weight) = 100 × (W 2 -W 0 ) / (W1 -W 0 ) (1) (W 0 : Weight of the base material, W 1 : Weight of the test piece before immersion, W 2 : Weight of the test piece after immersion and drying)

[0071] When the base polymer is the acrylic polymer, the preferable lower limit of the shear storage modulus (hereinafter simply referred to as "shear storage modulus") at 25°C measured at a measurement frequency of 10 Hz using the dynamic viscoelasticity measuring device for the pressure-sensitive adhesive layer is 1.0×10 4 Pa, and the preferable upper limit is 5.0×10 5 Pa. If 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. The shear storage modulus of the pressure-sensitive adhesive layer is more preferably 3.0×10 4 Pa or more, even more preferably 5.0×10 4 Pa or more, and more preferably 4.0×10 5 Pa or less, and even more preferably 3.5×10 5 Pa or less. The shear storage modulus of the pressure-sensitive adhesive layer can be adjusted by the type and polymerization ratio 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), the types and contents of the compound (T1) of the present invention and the tackifier resin (T2), etc.

[0072] Note that the shear storage modulus of the pressure-sensitive adhesive layer can be measured by the following method. First, a measurement sample consisting only of the pressure-sensitive adhesive layer is prepared. For the obtained measurement sample, using a dynamic viscoelasticity measuring device such as a viscoelastic spectrometer (for example, DVA-200 manufactured by IT Measurement & Control Co., Ltd., or its equivalent), the storage modulus at 25°C when measuring the dynamic viscoelastic spectrum from -50°C to 200°C under the conditions of a slow heating shear deformation mode of 5°C / min and a measurement frequency of 10 Hz is measured.

[0073] When the base polymer is the acrylic polymer, it is preferable that the pressure-sensitive adhesive layer has a peak in the loss tangent (tan δ, hereinafter simply referred to as "loss tangent") measured at a measurement frequency of 10 Hz using a dynamic viscoelasticity measuring device at -20°C or higher and 20°C or lower. When the loss tangent of the pressure-sensitive adhesive layer has a peak within the above range, it becomes easier to balance the adhesive strength and the holding power of the pressure-sensitive adhesive layer. More preferably, the loss tangent has a peak at 15°C or lower, and even more preferably, it has a peak at 12°C or lower. More preferably, the loss tangent has a peak at -15°C or higher, and even more preferably, it has a peak at -10°C or higher. The loss tangent of the pressure-sensitive adhesive layer can be obtained by measuring the dynamic viscoelastic spectrum from -100°C to 200°C using a viscoelastic spectrometer (for example, DVA-200 manufactured by IT Measurement & Control Co., Ltd. or its equivalent) under the conditions of a slow heating rate of 5°C / min in a shear deformation mode and a measurement frequency of 10 Hz.

[0074] The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the preferable lower limit is 20 μm, and the preferable upper limit is 100 μm. More preferably, the lower limit is 25 μm, and the upper limit is 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 gauge (for example, "ABS Digital Indicator" manufactured by Mitutoyo Corporation).

[0075] 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 side of the substrate or on both sides of the substrate. The above-mentioned base material is not particularly limited, and examples thereof include resin films and the like. The above-mentioned resin film is not particularly limited, and examples thereof include polyolefin resin films such as polyethylene films and polypropylene films, polyester resin films such as polyethylene terephthalate (PET) films, ethylene-vinyl acetate copolymer films, polyvinyl chloride resin films, and polyurethane resin films. Further, as the above-mentioned base material, polyolefin foam sheets such as polyethylene foam sheets and polypropylene foam sheets, and polyurethane foam sheets are also included. Among them, a PET film is preferred. The thickness of the above-mentioned base material is not particularly limited, but the preferred lower limit is 5 μm, the preferred upper limit is 30 μm, the more preferred lower limit is 8 μm, and the more preferred upper limit is 20 μm.

[0076] The pressure-sensitive adhesive tape of the present invention may have other layers other than the above-mentioned pressure-sensitive adhesive layer and the above-mentioned base material, if necessary.

[0077] The method for producing the pressure-sensitive adhesive tape of the present invention is not particularly limited. For example, when the above-mentioned pressure-sensitive adhesive layer is laminated on both sides of the above-mentioned base material, the following methods can be mentioned. First, a solvent is added to a base polymer, the compound (T1) of the present invention, a tackifier resin (T2), a crosslinking agent, etc. to prepare a solution of the pressure-sensitive adhesive composition A, and this solution of the pressure-sensitive adhesive composition A is applied to the surface of the base material, and the solvent in the solution is completely dried and removed to form a pressure-sensitive adhesive layer A. Next, a release film is superposed on the formed pressure-sensitive adhesive layer A in a state where its release-treated surface faces the pressure-sensitive adhesive layer A. Next, a release film different from the above-mentioned release film is prepared, and a solution of the pressure-sensitive adhesive composition B is applied to the release-treated surface of this release film, and the solvent in the solution is completely dried and removed, whereby a laminated film having a pressure-sensitive adhesive layer B formed on the surface of the release film is produced. The obtained laminated film is superposed on the back surface of the base material on which the pressure-sensitive adhesive layer A is formed in a state where the pressure-sensitive adhesive layer B faces the back surface of the base material to produce a laminate. Then, the above laminate is pressurized by a rubber roller or the like. Thereby, a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both sides of the base material and the surfaces of the pressure-sensitive adhesive layers covered with release films can be obtained.

[0078] Also, two sets of laminated films are produced in the same manner, and these laminated films are superposed on each of both surfaces of the base material with the adhesive layers of the laminated films facing the base material to produce a laminate, and this laminate may be pressed by a rubber roller or the like. Thereby, a double-sided adhesive tape having adhesive layers on both surfaces of the base material and the surfaces of the adhesive layers covered with release films can be obtained.

[0079] The use of the adhesive composition of the present invention and the adhesive tape of the present invention is not particularly limited. However, since the adhesive strength is high, especially for adherends with low polarity (for example, difficult-to-adhere adherends such as adherends made of polyolefin resin and fluororesin), it is used, for example, for fixing electronic device parts or in-vehicle parts. More specifically, for example, it is used for fixing parts in televisions, monitors, portable electronic devices, in-vehicle electronic devices, and the like. The shape of the adhesive tape of the present invention in these uses is not particularly limited, and examples thereof include a square, a rectangle, a frame shape, a circle, an ellipse, a donut shape, and the like.

Effects of the Invention

[0080] According to the present invention, it is possible to provide a compound capable of increasing the adhesive strength of the adhesive composition, and in particular, capable of increasing the adhesive strength even for an adherend with low polarity. Further, according to the present invention, it is possible to provide a method for producing the compound, an adhesive composition containing the compound, and an adhesive tape having an adhesive layer containing the adhesive composition.

Modes for Carrying Out the Invention

[0081] Examples will be given below to explain the aspects of the present invention in more detail, but the present invention is not limited only to these examples.

[0082] (Synthesis Example 1) (Preparation of Acrylic Polymer) 100 parts by weight of ethyl acetate was placed in a reactor equipped with a thermometer, a stirrer, and a cooling tube. After purging with nitrogen, the reactor was heated to initiate reflux. After ethyl acetate started to boil, 0.08 part by weight of azobisisobutyronitrile was added as a polymerization initiator 30 minutes later. The monomer mixture shown in Table 1 was added dropwise evenly and gradually over 1 hour and 30 minutes for reaction. 30 minutes after the completion of the dropwise addition, 0.1 part by weight of azobisisobutyronitrile was added, and the polymerization reaction was carried out for another 5 hours. By adding ethyl acetate to the reactor and cooling while diluting, a solution of an acrylic polymer with a solid content of 25% by weight was obtained. The obtained solution of the acrylic polymer was filtered through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (Waters, 2690 Separations Model), and GPC measurement was carried out under the conditions of a sample flow rate of 1 milliliter / min and a column temperature of 40 °C to measure the polystyrene-equivalent molecular weight of the acrylic polymer, and the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were determined. As the column, GPC KF-806L (manufactured by Showa Denko KK) was used, and as the detector, a differential refractometer was used.

[0083] (Synthesis Example 2) (Preparation of Acrylic Polymer) An acrylic polymer was obtained in the same manner as in Synthesis Example 1 except that the addition amount of ethyl acetate was changed to 50 parts by weight.

[0084] (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.

[0085]

Table 1

[0086] (Synthesis Example A) (Preparation of Compound (T1)) 50 parts by weight of toluene was placed in a reactor equipped with a thermometer, a stirrer, and a cooling pipe. After purging with nitrogen, the reactor was heated to start refluxing. After 30 minutes, while maintaining the toluene at 75 °C, 2 parts by weight of aluminum chloride (AlCl 3 ) was added. Here, a solution prepared by dissolving 22.3 parts by weight of monomer (a) and 27.7 parts by weight of monomer (b) (the molar ratio is as shown in Table 2) in 50 parts by weight of toluene was gradually added dropwise over 1 hour and 30 minutes for reaction. After a 4-hour polymerization reaction, while adding 0.1 part by weight of pyridine to the reactor, cooling was carried out to neutralize the hydrochloric acid generated from aluminum chloride (AlCl 3 ). The precipitate formed by neutralization was filtered, and after performing a liquid separation operation on the obtained filtrate, toluene was volatilized to obtain a solid compound (T1). Regarding the obtained compound (T1) l 1H-NMR measurement was performed, and it was confirmed that compound (T1) is 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 prepared by dissolving the obtained compound (T1) in tetrahydrofuran was filtered through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (manufactured by Waters, 2690 Separations Model), and GPC measurement was performed under the conditions of a sample flow rate of 1 milliliter / min and a column temperature of 40 °C to measure the polystyrene-reduced molecular weight of compound (T1) and determine the weight-average molecular weight (Mw). As the column, GPC KF-802.5L (manufactured by Showa Denko KK) was used, and as the detector, a differential refractometer was used.

[0087] Regarding the obtained compound (T1), measurement was performed using a differential scanning calorimeter (manufactured by 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 1st run.

[0088] The obtained compound (T1) was filled into a mold with a size of 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. For this test piece, using a tensile testing apparatus (Tensilon, manufactured by ORIENTEC), a tensile test was conducted under the conditions of a tensile speed of 200 mm / min, a distance between grips of 15 mm, and a temperature of 25 °C to measure the Young's modulus at 25 °C.

[0089] 0.250 g of the obtained compound (T1) was weighed and diluted by adding 50 mL of cyclohexane. Next, 10.0 mL of Wijs reagent (manufactured by Wako Pure Chemical Industries, Ltd., 0.1 mol / L iodine chloride - acetic acid solution) was added, shaken well, and left to stand for 30 minutes to allow the reaction to proceed. 10 mL of a 15 wt% aqueous potassium iodide solution was added thereto, 30 mL of water was added, and the mixture was stirred. Further, an aqueous 0.1 N sodium thiosulfate solution (manufactured by Wako Pure Chemical Industries, Ltd.) was gradually added dropwise. When the solution turned pale yellow, 3 drops of starch solution (10 g / L) were added. Thereafter, the aqueous 0.1 N sodium thiosulfate solution (manufactured by Wako Pure Chemical Industries, Ltd.) was gradually added dropwise until the blue color of the solution disappeared (the added amount was Y mL). Next, except for not adding the sample (compound (T1)), in the same manner, the blank added amount (added amount Z mL) was determined. The iodine value of compound (T1) was measured by the following formula. Iodine value (g / 100 g) = (Z - Y) × 1.269 / 0.250

[0090] For the obtained compound (T1), the content rate of bio-derived carbon was measured in accordance with ASTM D6866 - 20.

[0091] (Synthesis Examples B to M) (Preparation of Compound (T1)) Compound (T1) was obtained in the same manner as in Synthesis Example A except that monomers (a) and (b) were changed as shown in Table 2.

[0092]

Table 2

[0093] (Example 1) (1) Manufacture of Adhesive Tape To 100 parts by weight of the solid content of the acrylic polymer (Synthesis Example 1), 30 parts by weight of the compound (T1) (Synthesis Example A) was added. Further, 30 parts by weight of ethyl acetate (manufactured by Fuji Chemical Industries Co., Ltd.) and 2.5 parts by weight of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L45") were added and stirred to obtain a solution of the adhesive composition. A release film with a thickness of 150 μm was prepared, and the solution of the adhesive composition was applied to the release-treated surface of this release film and dried at 100 °C for 5 minutes to form an adhesive layer with a thickness of 50 μm. This adhesive layer was bonded to the surface of a corona-treated PET film with a thickness of 50 μm serving as a base material. Next, in the same manner, the same adhesive layer as above was also bonded to the opposite surface of the base material. Then, curing was carried out by heating at 40 °C for 48 hours. As a result, an adhesive tape was obtained in which the adhesive layers were laminated on both sides of the base material and the surface of the adhesive layer was covered with a release film.

[0094] (2) Measurement of Gel Fraction The adhesive tape was cut into test pieces in a flat rectangular shape of 50 mm × 100 mm. After immersing the test pieces in ethyl acetate at 23 °C for 24 hours, they were taken out from ethyl acetate and dried at 110 °C for 1 hour. The weight of the dried test pieces was measured, and the gel fraction was calculated using the following formula (1). Note that no release film for protecting the adhesive layer was laminated on the test pieces. Gel fraction (weight %) = 100 × (W 2 - W 0 ) / (W 1 - W 0 ) (1) (W 0 : Weight of the base material, W 1 : Weight of the test piece before immersion, W 2 : Weight of the test piece after immersion and drying)

[0095] (3) Measurement of Shear Storage Modulus A measurement sample consisting only of an adhesive layer was prepared. For the obtained measurement sample, using a viscoelastic spectrometer (manufactured by IT Measurement Control Co., Ltd., DVA-200), the storage elastic modulus at 25°C was measured when measuring the dynamic viscoelastic spectrum from -50°C to 200°C under the conditions of a slow heating rate of 5°C / min in the shear deformation mode and a measurement frequency of 10 Hz.

[0096] (4) Measurement of the peak temperature of the loss tangent (tanδ) A measurement sample consisting only of an adhesive layer was prepared. For the obtained measurement sample, using a viscoelastic spectrometer (manufactured by IT Measurement Control Co., Ltd., DVA-200), the dynamic viscoelastic spectrum from -100°C to 200°C was measured under the conditions of a slow heating rate of 5°C / min in the shear deformation mode and a measurement frequency of 10 Hz, and the peak temperature of the loss tangent (tanδ) was obtained from the obtained dynamic viscoelastic spectrum.

[0097] (Examples 2 to 23, Comparative Examples 1 to 2) An adhesive tape was obtained in the same manner as in Example 1 except that the types and amounts of the acrylic polymer, compound (T1), tackifying resin (T2), and crosslinking agent were changed as shown in Table 3. The tackifying resin (T2) and crosslinking agent used are shown below.

[0098] Rosin ester resin (manufactured by Arakawa Chemical Industries, Ltd., trade name "Pink Crystal KE359") Terpene phenol resin (manufactured by Yasuhara Chemical Co., Ltd., trade name "YS Polyster G150") Isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L45") Epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad E5XM")

[0099] (Example 24) To 100 parts by weight of the solid content of a styrene-based elastomer (SIS block copolymer, manufactured by Nippon Zeon Co., Ltd., Quintac 3520, styrene content: 15% by weight, diblock ratio: 78% by weight), 30 parts by weight of compound (T1) (Synthesis Example A) was added. Further, 30 parts by weight of toluene (manufactured by Fuji Chemical Industries Co., Ltd.) was added and stirred to obtain a solution of the pressure-sensitive adhesive composition. A release film with a thickness of 150 μm was prepared, and the solution of the pressure-sensitive adhesive composition was applied to the release-treated surface of this release film and dried at 100 °C for 5 minutes to form a pressure-sensitive adhesive layer with a thickness of 50 μm. This pressure-sensitive adhesive layer was bonded to the surface of a corona-treated PET film with a thickness of 50 μm serving as a base material. Next, in the same manner, the same pressure-sensitive adhesive layer as above was also bonded to the opposite surface of the base material. Then, it was cured by heating at 40 °C for 48 hours. As a result, a pressure-sensitive adhesive tape was obtained in which the pressure-sensitive adhesive layers were laminated on both sides of the base material and the surface of the pressure-sensitive adhesive layer was covered with a release film.

[0100] (Examples 25 to 53, Comparative Examples 3 to 4) A pressure-sensitive adhesive tape was obtained in the same manner as in Example 24, except that the types and amounts of the styrene-based elastomer, compound (T1), and tackifier resin (T2) were changed as shown in Tables 4 to 5. The styrene-based elastomers and tackifier resins (T2) used are shown below.

[0101] Styrene-based elastomer (SIS block copolymer, manufactured by Nippon Zeon Co., Ltd., Quintac 3520, styrene content: 15% by weight, diblock ratio: 78% by weight) Styrene-based elastomer (SIS block copolymer, manufactured by Nippon Zeon Co., Ltd., Quintac 3433N, styrene content: 16% by weight, diblock ratio: 56% by weight) Styrene-based elastomer (SIS block copolymer, manufactured by Nippon Zeon Co., Ltd., Quintac 3421, styrene content: 14% by weight, diblock ratio: 26% by weight) Styrene-based elastomer (SIS block copolymer, manufactured by Nippon Zeon Co., Ltd., Quintac 3450, styrene content: 19% by weight, diblock ratio: 30% by weight) Styrene-based elastomer (SIS block copolymer, manufactured by Nippon Zeon Co., Ltd., Quintac 3280, styrene content: 25% by weight, diblock ratio: 17% by weight) Styrene-based elastomer (SBS block copolymer, manufactured by Kraton Polymer Japan Co., Ltd., Kraton DX410, styrene content: 18% by weight, diblock ratio: 60% by weight) Terpene resin (manufactured by Yasuhara Chemical Co., Ltd., trade name "YS Resin PX1150")

[0102] <Evaluation> The pressure-sensitive adhesive tapes obtained in the examples and comparative examples were evaluated by the following methods. The results are shown in Tables 3 to 5.

[0103] (1) 180° peel test The pressure-sensitive adhesive tape was cut into a width of 25 mm to obtain test pieces. The adhesive layer of the obtained test pieces 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.). Then, a 2 kg rubber roller was reciprocated once at a speed of 300 mm / min on the test piece to bond the test piece to the stainless steel (SUS304) plate, the polypropylene (PP) plate or the polytetrafluoroethylene (PTFE) plate. Thereafter, the test samples were left standing at 23°C for 1 hour to prepare test samples. For the test samples after standing, a tensile test in the 180° direction was carried out at a peeling speed of 300 mm / min in accordance with JIS Z0237, and the peeling force was measured.

[0104] 180° peel test against SUS ◎: Peeling force is 20 N / inch or more ○: Peeling force is 15 N / inch or more and less than 20 N / inch △: Peeling force is 10 N / inch or more and less than 15 N / inch ×: Peeling force is less than 10 N / inch

[0105] 180° peel test against PP ◎: Peeling force is 15 N / inch or more ○: Peel strength is 10 N / inch or more and less than 15 N / inch △: Peel strength is 5 N / inch or more and less than 10 N / inch ×: Peel strength is less than 5 N / inch

[0106] For PTFE 180° peel test ◎: Peel strength is 5 N / inch or more ○: Peel strength is 3 N / inch or more and less than 5 N / inch △: Peel strength is 1 N / inch or more and less than 3 N / inch ×: Peel strength is less than 1 N / inch

[0107] (2) Alkaline resistance test The adhesive tape was cut into pieces of 25 mm × 75 mm. The release film on one side was peeled off, and the test piece was prepared by pasting it onto a polyethylene terephthalate (PET) film with a thickness of 23 μm for backing. In an environment of 23°C, the release film covering the other adhesive surface of the test piece was peeled off, and the test piece was pressure-bonded to the surface of a stainless steel (SUS304) plate with a 2 kg roller for one round trip to obtain a test sample before chemical solution immersion. Sodium hydroxide was diluted with ion-exchanged water to prepare an alkaline chemical solution with a pH of 12. The test sample before chemical solution immersion was immersed in the alkaline chemical solution in an atmosphere of 60°C for 1 day. Then, the test sample was taken out from the alkaline chemical solution, washed with ion-exchanged water, and dried at 23°C for 1 hour to obtain a test sample after chemical solution immersion. For the obtained test samples before and after chemical solution immersion, the presence or absence of peeling of the adhesive tape from the stainless steel plate was observed. ○: There was no peeling of the adhesive tape △: There was only slight peeling at the end of the adhesive tape ×: The entire surface was peeled off

[0108]

Table 3

[0109]

Table 4

[0110]

Table 5

Industrial Applicability

[0111] According to the present invention, it is possible to provide a compound capable of enhancing the adhesive strength of an adhesive composition, and in particular, capable of enhancing the adhesive strength even to a low-polarity adherend. Further, according to the present invention, it is possible to provide a method for producing the compound, an adhesive composition containing the compound, and an adhesive tape having an adhesive layer containing the adhesive composition.

Claims

1. A compound characterized by having at least one structural unit (A) selected from the group consisting of structural units (A-1) and structural units (A-1') represented by the following formulas: 【Chemistry 1】 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; 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.

2. 2. The compound according to claim 1, characterized in that the compound has a Young's modulus at 25° C. of 10 MPa or more.

3. 3. The compound according to claim 1 or 2, further comprising an aliphatic hydrocarbon group having an unsaturated double bond.

4. The compound according to claim 1, 2 or 3, further comprising 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.

5. 5. The compound according to claim 1, 2, 3 or 4, wherein the content of the structural unit (A) is 1 mol % or more and 60 mol % or less.

6. 6. The compound according to claim 1, 2, 3, 4 or 5, characterized in that the weight average molecular weight is 400 or more and 10,000 or less.

7. 7. The compound according to claim 1, 2, 3, 4, 5 or 6, which has a glass transition temperature of 0° C. or higher and 200° C. or lower.

8. 8. The compound according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the content of carbon of biological origin in the carbon of the compound is 10% or more.

9. 9. The compound according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein n and n′ in the structural unit (A) are 2.

10. 9. The compound according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein n and n′ in the structural unit (A) are 3.

11. 11. The compound according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, which has the structural unit (A) in the main chain or at an end of the main chain.

12. A method for producing a compound having at least one structural unit (A) selected from the group consisting of structural units (A-1) and structural units (A-1′) represented by the following formulas, 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, comprising: The monomer (a) represented by the following formula is copolymerized with the monomer (b): A method for producing a compound comprising the steps of: 【Chemistry 2】 【Chemistry 3】 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; n represents an integer of 2 or more and 4 or less; n' represents an integer of 2 or more and 5 or less; and n'' represents an integer of 2 or more and 5 or less.

13. The method for producing a compound according to claim 12, characterized in that the monomer (a) and the monomer (b) are copolymerized by cationic polymerization.

14. 12. A pressure-sensitive adhesive composition comprising a base polymer and the compound (T1) according to claim 1 .

15. The pressure-sensitive adhesive composition according to claim 14, characterized in that the content of the compound (T1) according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 is 1 part by weight or more and 35 parts by weight or less per 100 parts by weight of the base polymer.

16. 16. The pressure-sensitive adhesive composition according to claim 14 or 15, further comprising at least one tackifier resin (T2) selected from the group consisting of rosin ester resins, terpene resins and petroleum resins.

17. 17. The pressure-sensitive adhesive composition according to claim 16, wherein the content of the tackifier resin (T2) is 10 parts by weight or more and 100 parts by weight or less based on 100 parts by weight of the base polymer.

18. 18. The pressure-sensitive adhesive composition according to claim 17, wherein the content of the tackifier resin (T2) is 10 parts by weight or more and 50 parts by weight or less based on 100 parts by weight of the base polymer.

19. 19. The pressure-sensitive adhesive composition according to claim 14, 15, 16, 17 or 18, wherein the base polymer is an acrylic polymer.

20. 20. The pressure-sensitive adhesive composition according to claim 19, wherein the acrylic polymer has a structural unit derived from a monomer having a crosslinkable functional group.

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

22. 22. The pressure-sensitive adhesive composition according to claim 19, 20 or 21, wherein the acrylic polymer has a weight average molecular weight of 200,000 or more and 2,000,000 or less.

23. The pressure-sensitive adhesive composition according to claim 14, 15, 16, 17 or 18, characterized in that 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.

24. 24. The pressure-sensitive adhesive composition according to claim 23, wherein the styrene-based elastomer is a styrene-isoprene-styrene (SIS) block copolymer or a styrene-butadiene-styrene (SBS) block copolymer.

25. 25. The pressure-sensitive adhesive composition according to claim 23, wherein the styrene-based elastomer has a diblock ratio of 50% by weight or more.

26. 26. The pressure-sensitive adhesive composition according to claim 23, 24 or 25, wherein the styrene-based elastomer has a styrene content of 20% by weight or less.

27. 27. An adhesive tape comprising an adhesive layer containing the adhesive composition according to claim 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26.

28. 23. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to claim 19, 20, 21 or 22, wherein the pressure-sensitive adhesive layer has a gel fraction of 10% by weight or more and 70% by weight or less.

29. The pressure-sensitive adhesive layer has a shear storage modulus of 1.0×10 at 25° C. measured using a dynamic viscoelasticity measuring device at a measurement frequency of 10 Hz. ４ Pa or more, 5.0×10 ５ 29. The adhesive tape according to claim 28, wherein the viscosity is 0.1 Pa or less.

30. 30. The pressure-sensitive adhesive tape according to claim 28, wherein the pressure-sensitive adhesive layer has a loss tangent, measured at a measurement frequency of 10 Hz using a dynamic viscoelasticity measuring device, that has a peak at a temperature between -20°C and 20°C.

31. 31. The adhesive tape according to claim 27, 28, 29 or 30, which is used for fixing electronic equipment parts or vehicle-mounted parts.

Images