Adhesive, adhesive tape, electrical appliance, in-vehicle component, and fixing method

Abstract

Provided is a pressure-sensitive adhesive sheet that has a high bio content while exhibiting good holding power at high temperatures, good adhesion at low temperatures, and good adhesion to low-polarity adherends. [Solution] The adhesive contains a polymer (X1) containing 48 mass% or more of structural units derived from at least one monomer (Y) selected from the group consisting of a monomer (A1) represented by the following general formula (1) and a monomer (B1) represented by the following general formula (2), and has a tan δ(23°C) of 0.8 to 1.3, calculated by G"(23°C) / G'(23°C), where G'(23°C) is the storage modulus at 23°C and G"(23°C) is the loss modulus. JPEG2023036859000011.jpg4066 In formula (1), R 1 represents H or CH3, and R 2 Ga-C n H 2n+1 and n represents an integer of 7 to 14. In formula (2), R 3 is -C(=O)C m H 2m+1 and m represents an integer of 7 to 13.

Description

[Technical Field]

[0001] The present invention relates to an adhesive, an adhesive tape, an adhesive sheet, an electrical appliance and an in-vehicle member having the adhesive, adhesive tape or adhesive sheet, and a fixing method using the adhesive or adhesive tape. [Background technology]

[0002] Conventionally, pressure-sensitive adhesive tapes having a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive have been widely used to fix various parts in electrical appliances, vehicles, houses, building materials, etc. Known pressure-sensitive adhesives include those containing an acrylic polymer whose main component is a structural unit derived from acrylic (meth)acrylate, such as 2-ethylhexyl acrylate or n-butyl acrylate (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

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

[0004] In recent years, with the globalization of each company's production bases, assembly using adhesive tape has come to be carried out in a variety of environments. For example, products that require performance in high-temperature environments, such as electrical appliances and automotive components, may be assembled in cold regions, and the adhesive may be required to have high holding power at high temperatures and low-temperature adhesion that allows it to be easily attached to the adherend even at low temperatures.

[0005] While low-temperature adhesion requires high fluidity in low-temperature environments, improving holding power at high temperatures requires cohesive strength in high-temperature environments, but it can be difficult for general pressure-sensitive adhesives to satisfy both of these properties. Furthermore, while pressure-sensitive adhesives generally have difficulty increasing adhesive strength to adherends with low polarity, low-polarity resins such as polyolefin resins, typified by polypropylene resins, are often used for in-vehicle components and electrical appliance parts, and these applications require high adhesive strength to adherends with low polarity.

[0006] On the other hand, the depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products are becoming problems. Therefore, efforts are being made to conserve petroleum resources by replacing petroleum-derived materials with bio-derived materials, primarily in the medical and packaging fields. These efforts are spreading to all fields, and the use of bio-derived materials is also being sought in the fields of adhesives and adhesive tapes.

[0007] According to the research of the present inventors, it has been found that conventionally widely used acrylic pressure-sensitive adhesives mainly composed of structural units derived from n-butyl acrylate can provide good holding power at high temperatures, good low-temperature adhesion, and good adhesion to low-polarity adherends such as polyolefin resins. However, alkyl (meth)acrylates with a small number of carbon atoms, such as n-butyl acrylate, are produced from petroleum and are unable to sufficiently increase the content of biologically derived carbon (i.e., the bio-fraction).

[0008] Therefore, an object of the present invention is to provide an adhesive and an adhesive sheet that have a high bio content while maintaining good holding power at high temperatures, good low-temperature adhesion, and good adhesion to low-polarity substrates such as polyolefin resins. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the above problems can be solved by using a predetermined monomer component of a polymer used in a pressure-sensitive adhesive and by controlling tan δ (23°C) within a specific range, and have completed the present invention as described below. That is, the present invention is summarized as follows: [1] to

[32] [1] A polymer (X1) containing 48 mass% or more of structural units derived from at least one monomer (Y) selected from the group consisting of a monomer (A1) represented by the following general formula (1) and a monomer (B1) represented by the following general formula (2), A pressure-sensitive adhesive having a tan δ(23°C) of 0.8 to 1.3, calculated by G"(23°C) / G'(23°C), where G'(23°C) is the storage modulus at 23°C and G"(23°C) is the loss modulus. [ka] In formula (1), R 1 represents H or CH3, and R 2 Ga-C n H 2n+1 and n represents an integer of 7 to 14. In formula (2), R 3 is -C(=O)C m H 2m+1 and m represents an integer of 6 to 13. [2] The pressure-sensitive adhesive according to the above [1], wherein the polymer (X1) has a weight-average molecular weight of 200,000 to 1,000,000. [3] The pressure-sensitive adhesive according to the above [1] or [2], which has a degree of crosslinking of 10 to 70%. [4] The pressure-sensitive adhesive according to any one of the above [1] to [3], wherein log G'(0°C) [Pa] is 5.0 to 6.5, where G'(0°C) is the storage modulus at 0°C. [5] The pressure-sensitive adhesive according to any one of the above [1] to [4], wherein log G'(23°C) [Pa] is 4.8 to 5.5, where G'(23°C) is the storage modulus at 23°C. [6] The pressure-sensitive adhesive according to any one of the above [1] to [5], wherein log G'(80°C) [Pa] is 4.1 to 4.8, where G'(80°C) is the storage modulus at 80°C. [7] The pressure-sensitive adhesive according to any one of the above [1] to [6], which has a glass transition temperature (Tg) of 15°C or lower. [8] The adhesive according to any one of the above [1] to [7], wherein the content of bio-derived carbon is 40% by mass or more. [9] The pressure-sensitive adhesive according to any one of the above [1] to [8], further comprising a tackifier.

[10] An adhesive tape comprising an adhesive layer made of the adhesive according to any one of the above [1] to [9].

[11] The pressure-sensitive adhesive tape according to the above

[10] , further comprising a substrate, the pressure-sensitive adhesive layer being provided on at least one surface of the substrate.

[12] The pressure-sensitive adhesive tape according to the above

[11] , wherein the substrate is any one selected from the group consisting of a nonwoven fabric, a polyethylene terephthalate film, and a foam.

[13] A method for fixing a component constituting an electrical appliance or an in-vehicle member using the pressure-sensitive adhesive according to any one of the above [1] to [9] or the pressure-sensitive adhesive tape according to any one of the above

[10] to

[12] .

[14] A pressure-sensitive adhesive according to any one of [1] to [9] above, wherein the peak top molecular weight (Mtp) of the sol fraction of the pressure-sensitive adhesive measured by gel permeation chromatography (GPC) is 137,000 or more and 300,000 or less, and the sol fraction (R sol ) is 90% by mass or less, and the glass transition temperature (Tg) of the adhesive is 5°C or less.

[15] The pressure-sensitive adhesive sheet according to the above

[14] , wherein the pressure-sensitive adhesive has a hardness (S) represented by the following general formula (3) of 50,000 or more and 180,000 or less. S=Mw×R sol / D (3) In formula (3), Mw represents the weight average molecular weight of the sol component of the PSA by GPC, and R sol represents the sol fraction in the pressure-sensitive adhesive, and D represents the dispersibility of the sol fraction in the pressure-sensitive adhesive as determined by GPC.

[16] The pressure-sensitive adhesive sheet according to the above

[14] or

[15] , wherein the dispersity (D) of the sol fraction of the pressure-sensitive adhesive as measured by GPC is 1.6 or more and less than 3.

[17] The pressure-sensitive adhesive sheet according to any one of the above

[14] to

[16] , wherein the weight average molecular weight (Mw) of the sol portion of the pressure-sensitive adhesive measured by GPC is 190,000 or more and 700,000 or less.

[18] Sol fraction of the adhesive (R sol The pressure-sensitive adhesive sheet according to any one of the above

[14] to

[17] , wherein the content of the polymerizable monomer is 45% by mass or more and 75% by mass or less.

[19] The pressure-sensitive adhesive sheet according to any one of the above

[14] to

[18] , wherein the pressure-sensitive adhesive has a glass transition temperature (Tg) of 2.5°C or lower.

[20] The adhesive sheet according to any one of the above

[14] to

[19] , wherein the bio content of the adhesive is 51% or more.

[21] The pressure-sensitive adhesive sheet according to the above

[20] , wherein the content of structural units derived from n-heptyl (meth)acrylate in the polymer (X1) is 48 mass % or more.

[22] A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive containing a biological component, wherein the peak top molecular weight (Mtp) of the sol fraction of the pressure-sensitive adhesive measured by gel permeation chromatography (GPC) is 137,000 or more and 300,000 or less, and the sol fraction (R sol ) is 90% by mass or less, and the glass transition temperature (Tg) of the adhesive is 5°C or less.

[23] The pressure-sensitive adhesive sheet according to

[22] above, wherein the pressure-sensitive adhesive has a hardness (S) represented by the following general formula (3) of 50,000 or more and 180,000 or less. S=Mw×R sol / D (3) In formula (3), Mw represents the weight average molecular weight of the sol component of the PSA by GPC, and R sol represents the sol fraction in the pressure-sensitive adhesive, and D represents the dispersibility of the sol fraction in the pressure-sensitive adhesive as determined by GPC.

[24] The pressure-sensitive adhesive sheet according to the above

[22] or

[23] , wherein the dispersity (D) of the sol fraction of the pressure-sensitive adhesive as measured by GPC is 1.6 or more and less than 3.

[25] The pressure-sensitive adhesive sheet according to any one of the above

[22] to

[24] , wherein the weight average molecular weight (Mw) of the sol portion of the pressure-sensitive adhesive measured by GPC is 190,000 or more and 700,000 or less.

[26] Sol fraction of the adhesive (Rsol The pressure-sensitive adhesive sheet according to any one of the above

[22] to

[25] , wherein the content of the polymerizable monomer is 45% by mass or more and 75% by mass or less.

[27] The pressure-sensitive adhesive sheet according to any one of the above

[22] to

[26] , wherein the pressure-sensitive adhesive has a glass transition temperature (Tg) of 2.5°C or lower.

[28] The adhesive sheet according to any one of claims 22 to 27 above

[22] to

[27] , wherein the adhesive has a bio-content of 51% or more.

[29] The pressure-sensitive adhesive sheet according to any one of the above

[22] to

[28] , wherein the pressure-sensitive adhesive contains a polymer (X2) containing 48 mass % or more of structural units derived from at least one monomer (Y2) selected from the group consisting of a monomer (A2) represented by the following general formula (4) and a monomer (B2) represented by the following general formula (5): [ka] In formula (4), R 4 represents H or CH3, and R 5 Ga-C n H 2n+1 wherein n represents an integer of 7 to 20, and in formula (5), R 6 is -C(=O)C m H 2m+1 and m represents an integer of 6 to 13.

[30] The pressure-sensitive adhesive sheet according to the above

[29] , wherein the content of structural units derived from n-heptyl (meth)acrylate in the polymer (X2) is 48 mass % or more.

[31] An electrical appliance comprising the adhesive according to any one of the above [1] to [9], or the adhesive tape according to any one of the above

[10] to

[12] , or the adhesive sheet according to any one of the above

[14] to

[30] .

[32] An in-vehicle member comprising the pressure-sensitive adhesive according to any one of the above [1] to [9], the pressure-sensitive adhesive tape according to any one of the above

[10] to

[12] , or the pressure-sensitive adhesive sheet according to any one of the above

[14] to

[30] . [Effects of the Invention]

[0010] The pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention have a high bio content, while also exhibiting good holding power at high temperatures, good low-temperature adhesion, and good adhesion to low-polarity adherends. [Brief explanation of the drawings]

[0011] [Figure 1] An outline of the cohesion strength test using the micro shear displacement measurement test device and an enlarged view of part A are shown. DETAILED DESCRIPTION OF THE INVENTION

[0012] <<First Invention>> The first aspect of the present invention will be described in detail below using an embodiment. <Adhesive> Polymer (X1) The pressure-sensitive adhesive of the present invention contains a polymer (X1). The polymer (X1) contains a structural unit derived from at least one monomer (Y1) selected from the group consisting of a monomer (A1) represented by the following general formula (1) and a monomer (B1) represented by the following general formula (2). In this specification, the term "monomer (Y1)" is also used to collectively describe the monomer (A1) and the monomer (B1).

[0013] [ka] In formula (1), R 1 represents H or CH3, R 2 Ha-C n H 2n+1 and n represents an integer of 7 to 14. In formula (2), R 3 is -C(=O)C m H 2m+1 and m represents an integer of 6 to 13.

[0014] In the present invention, by containing at least one of structural units derived from monomer (A1) and monomer (B1), it becomes easier to adjust the tan δ (23°C) described below within an appropriate range, and it becomes easier to improve the holding power at high temperatures, the low-temperature adhesion, and the adhesion to low-polarity substrates. Furthermore, monomer (A1) and monomer (B1) can be easily produced from biologically derived raw materials, making it easier to increase the bio-content described below.

[0015] The polymer (X1) may contain structural units derived from one or both of the monomers (A1) and (B1), but preferably contains structural units derived from the monomer (A1). When the polymer (X1) contains structural units derived from the monomer (A1), it becomes easier to adjust the tan δ (23°C) within the desired range, and it also becomes easier to improve the holding power at high temperatures, the low-temperature adhesion, and the adhesion to low-polarity adherends.

[0016] R in Equation (1) 2 Alkyl groups (-C n H 2n+1 ), and R in Eq. (2) 3 Alkyl groups (-C m H 2m+1 ) may be linear or branched, but linear is preferred from the viewpoint of making it easier to keep tan δ (23°C) in an appropriate range. 2 In the formula (1), n ​​is preferably 7 to 10, and more preferably 7. In addition, from the viewpoint of improving adhesive properties, 1 is preferably H. Therefore, the polymer (X1) is a polymer having n of 7 to 10 in the general formula (1) and R 2 It is preferable that the copolymer contains a structural unit derived from a monomer (A1) in which n is 7 and R 2 It is more preferable that the monomer (A1) contains a structural unit derived from a linear monomer (A1), and in this case, the monomer (A1) is 1 It is more preferred that is H.

[0017] Specific examples of the monomer (A1) include n-heptyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, n-decyl (meth)acrylate, 2-octyl (meth)acrylate, n-nonyl (meth)acrylate, undecyl (meth)acrylate, tetradecyl (meth)acrylate, myristyl (meth)acrylate, etc. These monomers (A1) may be used alone or in combination of two or more. Specific examples of the monomer (B1) include vinyl caprate, vinyl laurate, vinyl caprylate, vinyl nonanoate, etc. These monomers (B1) may be used alone or in combination of two or more. Among the monomers (A1) and (B1), n-heptyl (meth)acrylate is preferred, and n-heptyl acrylate is more preferred. Use of n-heptyl (meth)acrylate makes it possible to adjust tan δ (23°C) within an appropriate range, thereby improving the holding power at high temperatures, the low-temperature adhesion, and the adhesion to low-polarity substrates. In this specification, the term "(meth)acrylate" is used to mean either or both of acrylate and methacrylate, and the same applies to other similar terms.

[0018] In addition, in the above general formulas (1) and (2), R 2 and R 3 is preferably carbon of biological origin. 2 and R 3 By using carbon derived from living organisms, the bio-ratio, which will be described later, can be increased. 2 and R 3 Monomers (A1) and (B1), each of which is made of carbon derived from living organisms, can be obtained cheaply and easily by alcoholizing and esterifying saturated fatty acids and unsaturated fatty acids extracted from plants and animals.

[0019] In the present invention, the content of structural units derived from monomer (Y1) (i.e., at least one monomer selected from monomer (A1) and monomer (B1)) in polymer (X1) is 48% by mass or more. If this content is less than 48% by mass, it becomes difficult to adjust tan δ (23°C) within an appropriate range. In addition, it becomes difficult to improve all of the holding power at high temperatures, low-temperature adhesion, and adhesion to low-polarity adherends while increasing the bio content. From the viewpoint of adjusting tan δ (23°C) within a desired range and improving the various performances described above while increasing the bio content, the content of the structural units derived from monomer (Y1) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. Furthermore, the content of the structural units derived from monomer (Y1) is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97.5% by mass or less, for example, to contain a predetermined amount of a functional group-containing monomer described below.

[0020] Furthermore, as described above, the monomer (A1) preferably contains n-heptyl (meth)acrylate. From the viewpoint of tan δ (23°C) and from the viewpoint of increasing the bio content and improving the various performances described above, the content of the n-heptyl (meth)acrylate-derived structural units in the polymer (X1) is preferably 48% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Furthermore, the content of the n-heptyl (meth)acrylate-derived structural units is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97.5% by mass or less.

[0021] The polymer (X1) preferably contains a structural unit derived from a monomer other than the above-mentioned monomer (A1) and monomer (B1). The other monomer may be a monomer having a polymerizable carbon-carbon double bond, such as a vinyl group or a (meth)acryloyl group. The other monomer is preferably a monomer containing a polar group (hereinafter also referred to as "polar group-containing monomer (C)"). When the polymer (X1) contains a structural unit derived from the polar group-containing monomer (C), the adhesive strength of the pressure-sensitive adhesive is easily increased, and the holding power at high temperatures, low-temperature adhesion, and adhesion to low-polarity adherends are also easily improved. The polar group is a functional group having active hydrogen, and specific examples thereof include a carboxyl group, a hydroxyl group, an amino group, and an amide group. The polar group may be a functional group capable of reacting with a crosslinking agent, which will be described later. The polar group-containing monomer (C) may be used alone or in combination of two or more. The polar group-containing monomer (C) preferably contains either a monomer containing a carboxy group (hereinafter also referred to as "carboxy group-containing monomer (C1)") or a monomer containing a hydroxy group (hereinafter also referred to as "hydroxy group-containing monomer (C2)"), and more preferably uses these in combination.

[0022] Examples of the carboxy group-containing monomer (C1) include acrylic acid, methacrylic acid, crotonic acid, etc. Among these, at least one selected from the group consisting of acrylic acid and methacrylic acid is preferred, and acrylic acid is more preferred. The content of the structural units derived from the carboxyl group-containing monomer (C1) in the polymer (X1) is preferably 0.5 to 10% by mass. By setting the content of the structural units derived from (C1) within the above range, the adhesive strength of the PSA is appropriately increased, and it becomes easier to improve the holding power at high temperatures, the low-temperature adhesion property, and the adhesion to low-polarity adherends. From these viewpoints, the content of the structural units derived from the carboxyl group-containing monomer (C1) is more preferably 1 to 8% by mass, and even more preferably 2 to 6% by mass.

[0023] Examples of the hydroxyl group-containing monomer (C2) include (meth)acrylates having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate, and allyl alcohol. Among these, (meth)acrylates having a hydroxyl group are preferred, and 2-hydroxyethyl (meth)acrylate is more preferred.

[0024] From the viewpoint of improving various performance properties of the PSA, the content of the structural units derived from the hydroxyl group-containing monomer (C2) in the polymer (X1) is preferably 0.1 to 15% by mass, more preferably 0.05 to 10% by mass, and more preferably 0.1 to 5% by mass. Furthermore, the hydroxyl group-containing monomer (C2) is preferably used in combination with a carboxy group-containing monomer (C1). When used in combination, the content of the structural units derived from the hydroxyl group-containing monomer (C2) is preferably 0.01 to 5% by mass, more preferably 0.05 to 2% by mass, and even more preferably 0.1 to 0.9% by mass. When used in combination with the carboxy group-containing monomer (C1), even a small amount improves the adhesive strength of the PSA, and facilitates improvements in holding power at high temperatures, low-temperature adhesion, and adhesion to low-polarity adherends.

[0025] Examples of the monomer containing an amide group include isopropyl(meth)acrylamide and dimethylaminopropyl(meth)acrylamide. Monomers other than the monomers (A1) and (B1) may be monomers other than functional group-containing monomers, and examples of such alkyl (meth)acrylates include alkyl (meth)acrylates having an alkyl group of 1 to 6 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, and n-hexyl (meth)acrylate, as well as alkyl (meth)acrylates having about 15 to 24 carbon atoms, such as cetyl (meth)acrylate, stearyl (meth)acrylate, esters of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)octanol-1 and (meth)acrylic acid, behenyl (meth)acrylate, and arachidyl (meth)acrylate. Examples of other monomers include (meth)acrylates having an alicyclic structure such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate, (meth)acrylates having an aromatic ring such as benzyl (meth)acrylate and 2-phenoxyethyl (meth)acrylate, monomers having an epoxy group such as glycidyl (meth)acrylate, monomers having a nitrile group such as (meth)acrylonitrile, 2-butoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and styrene. Monomers other than the polar group-containing monomer may be used alone or in combination of two or more kinds. The other monomer preferably contains carbon derived from living organisms, from the viewpoint of increasing the bio content, as will be described later, but may also be a petroleum-derived monomer that does not contain carbon derived from living organisms.

[0026] The weight average molecular weight (Mw) of the polymer (X1) is preferably 200,000 to 1,000,000. A weight-average molecular weight (Mw) of 200,000 or more increases the shear strength of the adhesive, making it possible to increase the adhesive's holding power at high temperatures. On the other hand, a weight-average molecular weight of 1,000,000 or less improves the adhesive strength of the adhesive, making it easier to improve low-temperature application properties and adhesion to low-polarity adherends. From these viewpoints, the weight average molecular weight (Mw) is more preferably 300,000 or more, and even more preferably 400,000 or more, and is more preferably 900,000 or less, and even more preferably 800,000 or less. The weight average molecular weight (Mw) can be adjusted appropriately by appropriately selecting the amount of polymerization initiator used, polymerization conditions such as polymerization temperature, polymerization method, and the like. The weight average molecular weight is a weight average molecular weight measured by gel permeation chromatography (GPC) and converted into standard polystyrene.

[0027] The polymer (X1) is the main component of the PSA. To provide adequate adhesive performance, the content of the polymer (X1) in the PSA is, for example, 50% by mass or more, preferably 60% by mass or more, and more preferably 65% ​​by mass or more. Furthermore, to allow for the blending of predetermined amounts of components other than the polymer (X1), such as a tackifier and a crosslinking agent, in the PSA, the content of the polymer (X1) in the PSA is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 92% by mass or less.

[0028] (Method for producing polymer (X1)) The polymer (X1) can be obtained by subjecting a mixture of the above-mentioned raw material monomers to a radical reaction in the presence of a polymerization initiator. The radical reaction method is not particularly limited, and examples thereof include living radical polymerization and free radical polymerization. Living radical polymerization produces copolymers with more uniform molecular weight and composition than free radical polymerization, and can suppress the generation of low molecular weight components, etc., thereby increasing the cohesive strength of the pressure-sensitive adhesive. The polymerization method is not particularly limited, and conventionally known methods can be used. Examples include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc. Among these, solution polymerization is preferred because of its ease of synthesis.

[0029] When solution polymerization is used as the polymerization method, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, diethyl ether, etc. These reaction solvents may be used alone or in combination.

[0030] The polymerization initiator is not particularly limited, and examples thereof include organic peroxides and azo compounds. Examples of the organic peroxides include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of the azo compounds include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators may be used alone or in combination.

[0031] In the case of living radical polymerization, the polymerization initiator may be, for example, an organic tellurium polymerization initiator. The organic tellurium polymerization initiator is not particularly limited as long as it is one that is generally used in living radical polymerization, and examples thereof include organic tellurium compounds, organic telluride compounds, etc. In addition to the organic tellurium polymerization initiator, an azo compound may also be used as the polymerization initiator in living radical polymerization in order to accelerate the polymerization rate.

[0032] [Tackifier] The pressure-sensitive adhesive of the present invention preferably contains a tackifier in addition to the polymer (X1). The inclusion of a tackifier improves the adhesiveness of the pressure-sensitive adhesive. It also facilitates improving adhesion to low-polarity adherends. Furthermore, for example, by adding a tackifier so that the glass transition temperature (Tg) is equal to or lower than the upper limit described below, low-temperature application properties are improved. Examples of tackifiers include rosin-based tackifiers such as rosin-based resins, rosin ester-based resins such as polymerized rosin ester resins, and hydrogenated rosin-based resins, as well as terpene-based tackifiers such as terpene-based resins and terpene-phenol-based resins, coumarone-indene resins, alicyclic saturated hydrocarbon-based resins, C5 petroleum resins, C9 petroleum resins, and C5-C9 copolymer petroleum resins. These tackifier resins may be used alone or in combination of two or more.

[0033] Among the above, rosin-based tackifiers and terpene-based tackifiers are preferred. These tackifiers can be easily synthesized from biologically derived raw materials, making it easier to increase the bio content. For example, rosin-based tackifiers are derived from natural resins such as pine resin, and terpene-based tackifiers are derived from plant essential oils, etc. Furthermore, rosin-based tackifiers are particularly suitable as tackifiers. The use of a rosin-based tackifier makes it easier to achieve excellent adhesion to low-polarity adherends such as polyolefin-based resins, typified by polypropylene resin.

[0034] The softening point of the tackifier is preferably 120°C or higher. The above-mentioned polymer (X1) tends to have a relatively low glass transition temperature, which makes it easy for the holding power at high temperatures to decrease. However, by using it in combination with a tackifier having a relatively high softening point, it is possible to prevent the holding power at high temperatures from decreasing. From this viewpoint, the softening point of the tackifier is more preferably 130°C or higher, and even more preferably 140°C or higher. Furthermore, from the viewpoint of imparting appropriate adhesive performance to the PSA, the softening point of the tackifier is preferably 165°C or lower, more preferably 160°C or lower, and even more preferably 155°C or lower. The softening point can be measured in accordance with JIS K2207.

[0035] When the pressure-sensitive adhesive contains a tackifier, the content of the tackifier is not particularly limited, but is preferably 10 to 50 parts by mass per 100 parts by mass of polymer (X1). When the content of the tackifier is at least the above-mentioned lower limit, low-temperature application property and adhesion to low-polarity adherends tend to be improved. Furthermore, when the content is at most the above-mentioned upper limit, a decrease in holding power at high temperatures can be prevented. From the above viewpoints, the content of the tackifier is more preferably 12 to 40 parts by mass, even more preferably 15 to 35 parts by mass, and particularly preferably 18 to 30 parts by mass.

[0036] [Crosslinking agent] The pressure-sensitive adhesive of the present invention is preferably crosslinked by blending a crosslinking agent. That is, the pressure-sensitive adhesive is preferably a crosslinked pressure-sensitive adhesive composition containing the above-mentioned polymer (X1), or the polymer (X1) and a tackifier, as well as a crosslinking agent. The crosslinking agent may crosslink the pressure-sensitive adhesive, for example, by reacting with a polar group of the polymer (X1). Examples of the crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, a metal chelate-based crosslinking agent, etc. Among these, at least one selected from the group consisting of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent is preferred, and an isocyanate-based crosslinking agent is more preferred.

[0037] The isocyanate crosslinking agent is not particularly limited as long as it is a compound having two or more isocyanate groups in one molecule, and examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, xylene diisocyanate, a tolylene diisocyanate adduct of trimethylolpropane, etc. Among these, tolylene diisocyanate and a tolylene diisocyanate adduct of trimethylolpropane are preferred. Commercially available isocyanate crosslinking agents include various polyisocyanate compounds such as Coronate L-45 and Coronate L-55E (manufactured by Tosoh Corporation), biuret polyisocyanate compounds such as Sumidur N (manufactured by Sumitomo Bayer Urethanes), polyisocyanate compounds having an isocyanurate ring such as Desmodur IL and HL (manufactured by Bayer AG) and Coronate EH (manufactured by Nippon Polyurethanes), and adduct polyisocyanate compounds such as Sumidur L (manufactured by Sumitomo Bayer Urethanes), Coronate L and Coronate HL (manufactured by Nippon Polyurethanes).

[0038] The epoxy crosslinking agent is not particularly limited as long as it is a compound having two or more epoxy groups in one molecule, and examples thereof include diglycidyl aniline, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, 1,3-bis(N,N-diglycidylaminoethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-xylylenediamine. Commercially available epoxy crosslinking agents include, for example, E-AX and E-5C (manufactured by Soken Chemical & Engineering Co., Ltd.). The crosslinking agent may be used alone or in combination of two or more kinds.

[0039] The amount of crosslinking agent in the pressure-sensitive adhesive may be appropriately changed depending on the type of polymer (X1), the desired physical properties such as the degree of crosslinking, and the like, but is, for example, 0.1 to 20 parts by mass, preferably 0.4 to 8 parts by mass, and more preferably 0.7 to 4 parts by mass relative to 100 parts by mass of polymer (X1).

[0040] (degree of crosslinking) The degree of crosslinking of the pressure-sensitive adhesive of the present invention is preferably 10 to 70%. By setting the degree of crosslinking within the above range, it becomes easier to improve the holding power at high temperatures, the low-temperature adhesion property, and the adhesion to low-polarity adherends. From this perspective, the degree of crosslinking of the pressure-sensitive adhesive is more preferably 20% or more, even more preferably 30% or more, and is preferably 60% or less, even more preferably 50% or less. The degree of crosslinking of the pressure-sensitive adhesive is represented by the gel fraction, and the method for measuring it is as shown in the Examples. The degree of crosslinking of the pressure-sensitive adhesive can be appropriately adjusted by changing the amount of crosslinking agent added, etc.

[0041] [Other additives] The pressure-sensitive adhesive of the present invention may contain additives such as a silane coupling agent, an antioxidant, an ultraviolet protection agent, a plasticizer, an emulsifier, a softener, a filler, a pigment, a dye, etc. From the viewpoint of increasing the bio content, it is preferable to select biologically derived materials as much as possible for these additives.

[0042] <Storage modulus> (tanδ(23℃)) The pressure-sensitive adhesive of the present invention has a tan δ(23°C) of 0.8 to 1.3, expressed as G"(23°C) / G'(23°C), where G'(23°C) is the storage modulus at 23°C and G"(23°C) is the loss modulus at 23°C. If tan δ(23°C) is less than 0.8 or exceeds 1.3, it becomes difficult to satisfy all of the requirements for holding power at high temperatures, low-temperature adhesion, and adhesion to low-polarity adherends such as polyolefin resins. From these viewpoints, tan δ(23°C) is preferably 0.85 or more, more preferably 0.88 or more, and preferably 1.2 or less, more preferably 1.1 or less, and even more preferably 1.0 or less.

[0043] Tan δ (23°C) can be adjusted by the type and amount of the monomer component used in the polymer (X1). For example, R 2 , R 3 By linearizing the polymer (X1) or reducing the values ​​of n and m, tan δ (23°C) tends to increase. Furthermore, by adjusting the tackifier resin and monomer blend and setting the glass transition temperature (Tg) within the range of -255 to 15°C, tan δ (23°C) can be easily adjusted to fall within the desired range. Tan δ can also be adjusted by the molecular weight of polymer (X1); for example, reducing the molecular weight of polymer (X1) tends to decrease the value of tan δ (23°C).

[0044] (Storage modulus at 23°C) If the storage modulus at 23°C is G'(23°C), then logG'(23°C) [Pa] is preferably 4.8 to 5.5. By setting logG'(23°C) [Pa] within the above range, the adhesive properties at room temperature are improved, and for example, adhesion to low-polarity adherends at room temperature is more likely to be improved. From this perspective, logG'(23°C) [Pa] is more preferably 4.85 to 5.4, and even more preferably 4.9 to 5.3.

[0045] (Storage modulus at 80°C) When the storage modulus at 80°C is G'(80°C), logG'(80°C) [Pa] is preferably 4.1 to 4.8. By setting logG'(80°C) [Pa] within the above range, the cohesive strength at high temperatures is improved, and the adhesiveness and holding power at high temperatures can be improved. From this perspective, logG'(80°C) [Pa] is more preferably 4.15 to 4.75, and even more preferably 4.2 to 4.7.

[0046] (Storage modulus at 0°C) When the storage modulus at 0°C is G'(0°C), logG'(0°C) [Pa] is preferably 5.0 to 6.5. By setting logG'(0°C) [Pa] within the above range, it becomes easier to improve the low-temperature adhesion. From this viewpoint, logG'(0°C) [Pa] is more preferably 5.4 to 6.4, and even more preferably 5.5 to 6.3. Note that logG'(0°C) [Pa] means the logarithm of the storage modulus expressed in the unit "Pa." Other similar expressions have the same meaning.

[0047] The storage modulus G' at 0°C, 23°C, and 80°C can be adjusted by the type and amount of the monomer components used in the polymer (X1). For example, by setting the type and content of the monomer (A1) and the monomer (B1) as described above, it can be easily adjusted to within the above range. The storage modulus G' at each temperature can also be adjusted by the weight-average molecular weight and the degree of crosslinking. For example, increasing the weight-average molecular weight or the degree of crosslinking tends to increase the storage modulus G' at each temperature. Furthermore, it can also be adjusted by the molecular weight distribution. For example, the storage modulus G' tends to increase when the molecular weight distribution is narrowed and decrease when it is broadened.

[0048] (glass transition temperature (Tg)) The glass transition temperature (Tg) of the pressure-sensitive adhesive of the present invention is preferably 15°C or lower. By setting the temperature to 15°C or lower, it becomes easier to increase tan δ (23°C), and the holding power at high temperatures and low-temperature application properties tend to be good. From these viewpoints, the glass transition temperature (Tg) is preferably 10°C or lower, more preferably 5°C or lower. The glass transition temperature (Tg) of the pressure-sensitive adhesive is not particularly limited, but from the viewpoint of improving the holding power at high temperatures, it is, for example, -40°C or higher, preferably -28°C or higher, more preferably -25°C or higher, and even more preferably -20°C or higher. The glass transition temperature (Tg) can be adjusted by the type and amount of the monomers constituting the polymer (X1). It can also be adjusted by the type and amount of the tackifier. For example, the glass transition temperature (Tg) tends to be higher by using a tackifier with a high softening point or by increasing the amount of the tackifier. The glass transition temperature (Tg) can also be adjusted by adding fine particles or the like.

[0049] The storage modulus G' and loss modulus G" at each temperature are values ​​obtained by measurement using a polymer dynamic viscoelasticity measuring device under the measurement conditions described in the Examples below. Tan δ (23°C) is a value calculated from the storage modulus G' (23°C) and loss modulus G" (23°C) measured at 23°C. The glass transition temperature (Tg) is measured using a polymer dynamic viscoelasticity measuring device under the measurement conditions described in the Examples below.

[0050] (bio rate) The adhesive of the present invention preferably has a biological carbon content (hereinafter also referred to as "bio-ratio") of 40% by mass or more. A bio-ratio of 40% by mass or more is generally considered to be a "bio-based product." Bio-based products can conserve petroleum resources by using renewable organic resources, and can also reduce carbon dioxide emissions from the combustion of petroleum-derived products, thereby reducing the burden on the environment. From these perspectives, a bio-ratio of 50% by mass or more is more preferable, and 60% by mass or more is even more preferable. Furthermore, the higher the bio-ratio, the better, and it is sufficient if it is 100% by mass or less. 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 bio-content can be calculated by measuring the concentration of C-14 in the adhesive or adhesive tape described below. Specifically, this can be measured in accordance with ASTM D6866, a standard used in many bioplastic industries.

[0051] (tack value) The adhesive of the present invention preferably has a peel limit value of 400 gf·s or more of an adhesive tape measured by a tack test at 23° C. The tack test is carried out as follows. First, an adhesive tape is placed with the adhesive layer facing up on the plate of a tack tester (e.g., Rhesca TAC-1000) set to 23°C. The non-measurement side of the adhesive tape is backed with a film such as polyethylene terephthalate (PET) film. Next, a cylindrical stainless steel probe with a diameter of 5 mm is pressed against the adhesive tape at a probe temperature of 23°C, a pressing speed of 2 mm / s, and a pressing load of 100 gf, and held in this state for 0.1 seconds. The probe is then pulled up at a pulling speed of 0.2 mm / s. The force applied to the adhesive tape during this period is measured. The above explanation has been given on an example where the adhesive constitutes an adhesive tape, but even if it does not constitute an adhesive tape, the adhesive can be placed on a plate of a tack tester set to 23°C and measured in the same manner.

[0052] The peel limit value means the integral value from time T1, when the force is 0, to the time when the maximum force (peak top) is reached in the force-time curve showing the force applied to the adhesive tape at 23°C measured by the tack test. In the tack test, when the probe is pressed against the adhesive tape, the force-time curve descends, and then when the probe begins to be pulled up, the force-time curve ascends. The integral value from time T1, when the force is 0, to time T2, when the maximum force (peak top) is reached is calculated, and this is defined as the peel limit value. By adjusting the peel strength within the above range, peeling of the adhesive tape can be suppressed even under conditions of high temperature and high humidity and a restoring force. A preferred lower limit of the peel strength is 450 gf·s, and a more preferred lower limit is 500 gf·s. There are no particular limitations on the upper limit of the peel strength.

[0053] (Preparation of adhesive) The pressure-sensitive adhesive of the present invention may be formed, for example, by preparing a pressure-sensitive adhesive composition and using the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition comprises components for forming a pressure-sensitive adhesive, specifically, in addition to the polymer (X1), a tackifier, a crosslinking agent, and other additives that are blended as needed. The pressure-sensitive adhesive composition may be diluted with a diluent such as an organic solvent. The diluent may be the solvent used in synthesizing the polymer (X1), or may be added after synthesizing the polymer (X1). The pressure-sensitive adhesive composition may be crosslinked by heating and drying as necessary to form a pressure-sensitive adhesive. The pressure-sensitive adhesive is typically used in pressure-sensitive adhesive tapes and the like, and may constitute a pressure-sensitive adhesive layer.

[0054] <Adhesive tape> The pressure-sensitive adhesive tape of the present invention is a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer made of the above-mentioned pressure-sensitive adhesive. The pressure-sensitive adhesive tape may be a non-supported tape that does not have a substrate, or may be a pressure-sensitive adhesive tape that has a substrate, but is preferably a pressure-sensitive adhesive tape that has a substrate. Note that the pressure-sensitive adhesive tape may also be referred to as a pressure-sensitive adhesive sheet, as described below. A non-supported tape is a double-sided adhesive tape that does not have a substrate and is used in the state of a single adhesive layer. An adhesive tape with a substrate comprises a substrate and an adhesive layer provided on at least one side of the substrate. In this case, the adhesive tape may be used as a double-sided adhesive tape with an adhesive layer provided on both sides of the substrate, or as a single-sided adhesive tape with an adhesive layer provided on only one side of the substrate. In each adhesive tape, the exposed surface of the adhesive layer may be protected by an appropriate release sheet. The release sheet is formed by applying a release agent to at least one side of the release sheet substrate to form the release surface, and is preferably attached so that the release surface comes into contact with the adhesive layer. In a double-sided adhesive tape having adhesive layers on both sides of a substrate, at least one of the adhesive layers may be made of the above-described adhesive of the present invention.

[0055] [Base material] The substrate used for the pressure-sensitive adhesive tape is not particularly limited, but is preferably any one of a resin film, a nonwoven fabric, or a foam. Specific examples of resin components constituting the resin film include polyesters (PES) such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS); polyolefins such as polyethylene (PE), polypropylene (PP), and ethylene vinyl acetate copolymer (EVA); polyurethane (PU), triacetyl cellulose (TAC), and polyamide (PA). These resin components may be used alone or in combination of two or more. Among the above, polyethylene terephthalate film (PET film) is preferred as the resin film. PET film has good mechanical strength and can adequately support the adhesive layer. Furthermore, PET film products with a high biocontent are commercially available, making it easy to increase the biocontent of adhesive tapes.

[0056] The nonwoven fabric may be made of a resin component, or may be made of fibers other than the resin component, such as pulp. The nonwoven fabric made of fibers other than the resin component may be made of fibers other than the resin component alone, or may be made of both fibers other than the resin component and resin fibers. The resin component may be appropriately selected from, for example, those listed as resin components constituting the resin film described above. Furthermore, nonwoven fabrics made of pulp are commercially available in products with a high bio content, which makes it easier to increase the bio content of the adhesive tape. When a foam is used as the substrate, examples of the foam include polyolefin resin foams using polyolefin resins such as PE, PP, and EVA as the resin component, and polyurethane foams using polyurethane resins.

[0057] The resin components constituting the resin film, nonwoven fabric, and foam may be, for example, petroleum-derived resins, animal and plant-derived resins, or resins derived from both petroleum and animals and plants. However, to make the pressure-sensitive adhesive tape a bio-based product, it is preferable to contain at least an animal and plant-derived resin. For example, when the substrate is a PET film, animal and plant-derived PET may be used. Furthermore, when a polyolefin resin foam or the like is used as the substrate, the polyolefin resin constituting the foam may be one derived from animals and plants.

[0058] In each pressure-sensitive adhesive tape, the thickness of the substrate is not particularly limited, but may be, for example, 1 to 2000 μm. The preferred range of the substrate thickness varies depending on the type of substrate used; for example, when the substrate is a resin film or nonwoven fabric, the preferred range is 1 to 100 μm, more preferably 5 to 50 μm. By setting the thickness of these substrates to 5 to 100 μm, a certain level of mechanical strength can be imparted to the pressure-sensitive adhesive tape without impairing flexibility. When the substrate is a foam, the thickness of the substrate is preferably 50 to 2000 μm. By keeping the thickness within this range, high impact resistance can be exhibited, while high flexibility can be exhibited, allowing the substrate to be adhered closely to the shape of the adherend.

[0059] In each pressure-sensitive adhesive tape, the thickness of the pressure-sensitive adhesive layer is not particularly limited, but may be, for example, about 5 to 200 μm, and preferably 10 to 100 μm. When the thickness of the pressure-sensitive adhesive layer is within this range, the resulting pressure-sensitive adhesive tape can exhibit sufficient adhesive strength. The total thickness of the adhesive tape (total thickness of the substrate and adhesive layer) is preferably 10 to 400 μm. When the total thickness of the adhesive tape is within this range, the resulting adhesive tape can exhibit sufficient adhesive strength.

[0060] (cohesion) The pressure-sensitive adhesive tape of the present invention preferably exhibits a slippage of 500 μm or less, more preferably 400 μm or less, even more preferably 300 μm or less, and particularly preferably 250 μm or less, at 23° C., as measured by a cohesive strength test. Furthermore, the pressure-sensitive adhesive of the present invention preferably exhibits a slippage of 1200 μm or less, more preferably 1000 μm or less, and even more preferably 800 μm or less, at 80° C., as measured by a cohesive strength test. When the slippages at 23° C. and 80° C. are reduced as described above, the cohesive strength of the pressure-sensitive adhesive layer increases, improving the holding power at room temperature and at high temperatures. The above-mentioned amount of displacement is the amount of displacement that occurs when a predetermined load is applied in the shear direction for 3 minutes, and the detailed measurement method will be described later.

[0061] Furthermore, after applying a load in the shear direction for 3 minutes as described above, the ratio of the amount of displacement recovered after the load is removed (the amount of displacement after the load is removed) to the amount of displacement (the amount of displacement before the load is removed) is defined as the shear displacement recovery rate (%). The shear displacement recovery rate (%) is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less, and is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. When the recovery rate is within the above range, the adhesive tape will conform well to the adherend when pressed, improving the application properties and adhesive strength.

[0062] The amount of displacement can be measured by a cohesive strength test using a micro shear displacement measurement test device (Asahi Seiko Co., Ltd., shear creep measurement device, NST1) shown in Figure 1. Specifically, the procedure is as follows. First, the release sheet on one side of the double-sided adhesive tape to be tested was peeled off, and a corona-treated polyethylene terephthalate (PET) film was attached to the exposed surface of one side of the adhesive layer of the double-sided adhesive tape. The tape was then cut to a size of 1 cm wide x 12 cm long to prepare test piece 5. The temperature controller 4 of the device was set to 23°C or 80°C, and the device was left to stand until the set temperature stabilized. Two or more temperature controllers may be used in combination as the temperature controller 4. The other release sheet of test piece 5 is peeled off and removed by about 3 cm from its end, and the exposed pressure-sensitive adhesive layer is attached to adherend 3 so that the adhesive area is 5 mm x 20 mm. At this time, release sheet 8 remains attached to pressure-sensitive adhesive layer 7 in areas other than the end. The other exposed surface of pressure-sensitive adhesive layer 7 of test piece 5 is attached to adherend 3 so that the adhesive area is 5 mm x 20 mm. Adherend 3 is made of SUS. A quartz block 2 (chromium-deposited quartz glass) with a mirror-finished end surface is placed on the attachment surface. The mirror-finished end surface 10 of the block 2 is irradiated with laser light from a laser interferometer 1 (for example, the Keyence "SI-F1"). Test piece 5 is attached to a wire connected to a 200 g weight 6, and left in that state to be kept at a constant temperature for 5 minutes. After 5 minutes, the weight 6 is applied to test piece 5, applying a horizontal shear load to test piece 5. Three minutes after the load is applied, the displacement of block 2 on test piece 5 is detected by laser interferometer 1, and the detected value is taken as the amount of displacement of the adhesive.

[0063] Furthermore, the load is applied as described above, the load is removed after 3 minutes, and the displacement (after load removal) is measured 3 minutes after the load is removed. The displacement measured before the load is removed as described above is defined as the displacement (before load removal), and the displacement recovery rate (%) is calculated as displacement (after load removal) / displacement (before load removal) × 100 (%). The displacement (after load removal) is measured with the laser interferometer 1 in the same way as the displacement (before load removal). The specific method for calculating the displacement recovery rate (%) is as follows: Slippage recovery rate (%) = (slippage (μm) 3 minutes after load removal) / (slippage (μm) 3 minutes after load application) × 100 The above explanation has shown a method for measuring the amount of slippage in double-sided adhesive tape, but the same method can be used with single-sided adhesive tape, except that the PET film attached to one of the adhesive layer surfaces is omitted. The same measurement can also be used with double-sided adhesive tape that does not have a substrate, such as a non-support tape. In addition, if a double-sided adhesive tape does not have a release sheet attached to the adhesive layer, the same method can be used, omitting the peeling process.

[0064] (Bio-ratio of adhesive tape) From the same viewpoint as the pressure-sensitive adhesive described above, the pressure-sensitive adhesive tape of the present invention preferably has a bio content of 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. The higher the bio content, the better, provided that it is 100% by mass or less. Generally, the bio content of a pressure-sensitive adhesive tape differs depending on the constituent components (e.g., the pressure-sensitive adhesive layer and the substrate). Therefore, the bio content may be calculated by determining the bio content of each constituent component and averaging the weighted average using the mass of each constituent component as a weight.

[0065] (Method of manufacturing adhesive tape) The method for producing the pressure-sensitive adhesive tape is not particularly limited, and the tape can be produced by a conventionally known production method. For example, first, a pressure-sensitive adhesive composition diluted with an organic solvent or the like as needed is prepared, and the pressure-sensitive adhesive composition is applied to a support such as a release sheet, and heated and dried as needed to form a pressure-sensitive adhesive layer. When the pressure-sensitive adhesive composition is applied to a release sheet, it is preferable to apply it to the release surface of the release sheet. The pressure-sensitive adhesive layer formed on a support such as a release sheet is further laminated to a substrate to obtain a pressure-sensitive adhesive tape having a substrate. Alternatively, a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer provided on a substrate may be obtained by directly applying the pressure-sensitive adhesive composition to a substrate and heating and drying as needed. When a double-sided adhesive tape is produced, an adhesive layer may be formed on each side of the substrate by any of the above methods. In addition, when producing a non-supported tape, the adhesive composition can be applied to a release sheet, and if necessary, heated and dried to form an adhesive layer. In this case, a release sheet may be further attached to the formed adhesive layer to protect the adhesive layer. In the case of a non-supported tape, the adhesive layer is preferably peeled off from the release sheet before use.

[0066] (Adhesive applications) The applications of the pressure-sensitive adhesive and pressure-sensitive adhesive tape of the present invention are not particularly limited, but are preferably used in electrical appliances and vehicle applications. For example, in electrical appliances, they are preferably used to fasten components constituting the electrical appliance. Specifically, in electrical appliances, components may be fastened to one another using the pressure-sensitive adhesive or pressure-sensitive adhesive tape. Therefore, the present invention also provides electrical appliances comprising the pressure-sensitive adhesive or pressure-sensitive adhesive tape. Examples of electrical appliances include, but are not limited to, portable electronic devices, various displays such as televisions, washing machines, refrigerators, dishwashers, vacuum cleaners, printers, and various audio devices.

[0067] In vehicle applications, the adhesive is preferably used to fasten vehicle-mounted components. Examples of vehicle-mounted components include interior materials for vehicles, such as vehicle panels such as ceiling panels, door panels, and instrument panels, car air conditioners, door trims, vibration-damping components, emblems, decorative films, and water-stopping components. The vehicle-mounted components may be fastened to the vehicle via, for example, an adhesive or adhesive tape. Therefore, the present invention also provides vehicle-mounted components comprising the above-mentioned adhesive or adhesive tape.

[0068] Electrical appliances and the interior of vehicles are sometimes exposed to high temperatures, but the pressure-sensitive adhesive of the present invention exhibits high holding power even in high-temperature environments, allowing electrical appliance parts and on-board components to be stably fixed. Meanwhile, electrical appliances and vehicles are sometimes assembled in cold regions, and even in cold regions, the pressure-sensitive adhesive or adhesive tape can be easily attached to electrical appliance parts or on-board components, resulting in good assembling properties. Furthermore, electrical appliance parts or on-board components may be made of polyolefin resins, such as polypropylene resins, and have low polarity. However, even if these have low polarity, the pressure-sensitive adhesive or adhesive tape of the present invention can be used to attach them with high adhesive strength.

[0069] <<Second Invention>> The second aspect of the present invention will be described in detail below using an embodiment.

[0070] [Adhesive sheet] The pressure-sensitive adhesive sheet of the present invention comprises a pressure-sensitive adhesive containing a plant-derived component. For example, as described below, the polymer (X2) contained in the pressure-sensitive adhesive may contain a plant-derived monomer component as a constituent unit. Furthermore, components other than the polymer (X2), such as a tackifier, may also contain a plant-derived component. Without a pressure-sensitive adhesive containing a plant-derived component, it is difficult to increase the bio-content of the pressure-sensitive adhesive sheet.

[0071] (adhesive) The pressure-sensitive adhesive sheet of the present invention has a peak top molecular weight (Mtp) of 137,000 or more and 300,000 or less of the sol fraction of the pressure-sensitive adhesive as determined by gel permeation chromatography (GPC), and the sol fraction (R sol ) is 90 mass % or less, and the glass transition temperature (Tg) of the pressure-sensitive adhesive is 5° C. or less. This increases the bio content of the pressure-sensitive adhesive sheet and improves low-temperature application properties, while also improving both the holding power at high temperatures and the adhesion to low-polarity adherends.

[0072] <Peak top molecular weight of sol component (Mtp)> The peak top molecular weight (Mtp) of the sol fraction of the PSA in the PSA sheet of the present invention measured by GPC is 137,000 or more and 300,000 or less. If the peak top molecular weight is less than 137,000, the holding power at high temperatures and adhesion to low-polarity adherends may deteriorate. If the peak top molecular weight is greater than 300,000, adhesion to low-polarity adherends may deteriorate. From this perspective, the peak top molecular weight is preferably 138,000 or more and 220,000 or less, and more preferably 138,000 or more and 200,000 or less. The peak top molecular weight of the sol fraction of the PSA measured by GPC is the molecular weight value at the peak top in the molecular weight distribution obtained by GPC measurement, and can be measured by the method described in the Examples below. The peak top molecular weight (Mtp) of the sol fraction measured by GPC is the peak top molecular weight of the sol fraction of the polymer, which is the main component, measured by GPC, and does not include the peak derived from the tackifier (TF). The peak top molecular weight of the sol portion of the adhesive measured by GPC can be adjusted by changing the molecular weight and molecular weight distribution of the polymer constituting the adhesive through the polymerization method, by changing the amount of crosslinking agent blended, or by blending low molecular weight components such as oligomers.

[0073] <Sol fraction (R sol )> The sol fraction (R sol The sol fraction (R sol If the sol fraction (R sol The sol fraction (R ) is preferably 45% by mass or more and 75% by mass or less. sol When the sol fraction (R ) is 45% by mass or more, the adhesiveness to an adherend having low polarity can be further improved while increasing the bio content. sol When the sol fraction (R ) is 75 mass % or less, the bio content can be increased and the retention force at high temperatures can be further improved. sol ) is more preferably 50% by mass or more and 70% by mass or less, even more preferably 55% by mass or more and 70% by mass or less, and even more preferably 58% by mass or more and 70% by mass or less. sol ) can be measured by the method described in the Examples below. sol ) can be adjusted by changing the molecular weight and molecular weight distribution of the polymer constituting the adhesive by the polymerization method, by changing the amount of crosslinking agent blended, or by blending a low molecular weight component such as an oligomer.

[0074] <Glass transition temperature (Tg)> The glass transition temperature (Tg) of the pressure-sensitive adhesive in the pressure-sensitive adhesive sheet of the present invention is 5°C or lower. If the glass transition temperature (Tg) is higher than 5°C, low-temperature adhesion may be impaired. From this perspective, the glass transition temperature (Tg) is preferably 2.5°C or lower, more preferably 0°C or lower, and even more preferably -1°C or lower. The upper limit of the glass transition temperature (Tg) range is not particularly limited, but from the perspective of improving holding power at high temperatures, it is preferably -20°C or higher, more preferably -18°C or higher, and even more preferably -17°C or higher. The glass transition temperature (Tg) can be measured by the method described in the Examples below. The glass transition temperature (Tg) can also be adjusted by the type and amount of monomers constituting the pressure-sensitive adhesive polymer. The glass transition temperature (Tg) can also be adjusted by the type and amount of tackifier. For example, the glass transition temperature (Tg) is likely to be higher by using a tackifier with a high softening point or by increasing the amount of the tackifier. The glass transition temperature (Tg) can also be adjusted by adding fine particles, etc.

[0075] <Hardness (S)> The adhesive of the adhesive sheet of the present invention preferably has a hardness (S) represented by the following general formula (3) of 50,000 or more and 180,000 or less. The hardness (S) is a parameter that indicates the softness of an adhesive. When the hardness (S) is within the specified range, the adhesive is neither too soft nor too hard and exhibits excellent adhesive performance. S=Mw×R sol / D (3) In formula (3), Mw represents the weight average molecular weight of the sol component of the PSA by GPC, and R sol represents the sol fraction in the pressure-sensitive adhesive, and D represents the dispersibility of the sol fraction in the pressure-sensitive adhesive as determined by GPC. When the hardness (S) is 50,000 or more, the holding power at high temperatures and adhesion to low-polarity adherends can be further improved while increasing the bio content. Furthermore, when the hardness (S) is 180,000 or less, the holding power at high temperatures can be further improved while increasing the bio content. From this perspective, the hardness (S) is more preferably 55,000 or more and 120,000 or less, and even more preferably 60,000 or more and 112,000 or less. The hardness (S) can be measured by the method described in the Examples below. The hardness (S) can also be adjusted by changing the molecular weight and molecular weight distribution of the polymer constituting the pressure-sensitive adhesive by the polymerization method, by changing the amount of crosslinking agent added, or by adding a low-molecular-weight component such as an oligomer.

[0076] <Degree of dispersion (D)> The dispersity (D) of the sol fraction in the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet of the present invention, as measured by GPC, is preferably 1.6 or more and less than 3. A dispersity (D) of 1.6 or more can increase the bio content while further improving adhesion to low-polarity adherends. A dispersity (D) of less than 3 can increase the bio content while further improving holding power at high temperatures. From this perspective, the dispersity (D) is more preferably 1.8 or more and less than 3, even more preferably 1.9 or more and less than 3, and even more preferably 2.0 or more and less than 3. The dispersity (D) can be measured by the method described in the Examples below. The dispersity (D) of the sol fraction, as measured by GPC, is the dispersity of the sol fraction of the polymer, which is the main component, as measured by GPC, and does not include the molecular weight due to the peak derived from the tackifier (TF). The dispersity (D) can be adjusted by changing the molecular weight of the polymer constituting the pressure-sensitive adhesive through the polymerization method, by changing the amount of crosslinking agent added, or by adding a low molecular weight component such as an oligomer.

[0077] <Weight average molecular weight (Mw)> The weight-average molecular weight (Mw) of the sol fraction of the PSA in the PSA sheet of the present invention, as measured by GPC, is preferably 190,000 or more and 700,000 or less. When the weight-average molecular weight (Mw) is 190,000 or more and 700,000 or less, the holding power at high temperatures and adhesion to low-polarity adherends can be further improved while increasing the bio content. From this perspective, the weight-average molecular weight (Mw) is more preferably 200,000 or more and 600,000 or less, even more preferably 220,000 or more and 550,000 or less, and even more preferably 240,000 or more and 460,000 or less. The weight-average molecular weight (Mw) can be measured by the method described in the Examples below. The weight-average molecular weight (Mw) of the sol fraction, as measured by GPC, is the weight-average molecular weight of the sol fraction of the polymer, which is the main component, as measured by GPC, and does not include the molecular weight due to the peak derived from the tackifier (TF). The weight average molecular weight (Mw) can be adjusted by changing the molecular weight and molecular weight distribution of the polymer that constitutes the adhesive through the polymerization method, by changing the amount of crosslinking agent added, or by adding low molecular weight components such as oligomers.

[0078] <Bio rate> The adhesive in the adhesive sheet of the present invention preferably has a biological carbon content (hereinafter also referred to as "bio-ratio") of 51% by mass or more. A bio-ratio of 51% by mass or more enables the adhesive to be a "bio-based product." Bio-based products can conserve petroleum resources by using renewable organic resources, and can also reduce carbon dioxide emissions from the combustion of petroleum-derived products, thereby mitigating the burden on the environment. From these perspectives, a bio-ratio of 55% by mass or more is more preferable, and 60% by mass or more is even more preferable. Furthermore, the higher the bio-ratio, the better, and it is sufficient if it is 100% by mass or less. Note that the method for measuring the bio-ratio has been explained in the section on the first invention, so it will not be explained here.

[0079] <Polymer (X2)> The pressure-sensitive adhesive in the pressure-sensitive adhesive sheet of the present invention preferably contains a polymer (X2). The polymer (X2) contains a structural unit derived from at least one monomer (Y2) selected from the group consisting of a monomer (A2) represented by the following general formula (4) and a monomer (B2) represented by the following general formula (5). In this specification, the term "monomer (Y2)" is also used to collectively describe the monomer (A2) and the monomer (B2).

[0080] [ka] In formula (4), R 4 represents H or CH3, R 5 Ha-C n H 2n+1 and n represents an integer of 7 to 20. In formula (5), R 6 is -C(=O)C m H 2m+1 where m is an integer of 6 to 13. The monomer (A2) represented by the general formula (4) differs from the monomer (A1) represented by the general formula (1) in that n is an integer of 7 to 20, and the monomer (B2) represented by the general formula (5) is the same as the monomer (B1) represented by the general formula (2).

[0081] In the present invention, the inclusion of at least one of structural units derived from monomer (A2) and monomer (B2) facilitates improving holding power at high temperatures, low-temperature adhesion, and adhesion to low-polarity substrates. Furthermore, monomer (A2) and monomer (B2) can be easily produced from biologically derived raw materials, making it easier to increase the bio-content, as described below.

[0082] The polymer (X2) may contain structural units derived from one or both of the monomers (A2) and (B2), but preferably contains structural units derived from the monomer (A2). When the polymer (X2) contains structural units derived from the monomer (A2), it is easier to improve the holding power at high temperatures, the low-temperature adhesion, and the adhesion to low-polarity adherends.

[0083] R in Equation (4) 5 Alkyl groups (-C n H 2n+1 ), and R in Eq. (4) 6 Alkyl groups (-C m H 2m+1 ) may be linear or branched, but linear is preferred from the viewpoints of holding power at high temperatures, low-temperature adhesion, and adhesion to low-polarity adherends. Also, from the viewpoint of easily improving holding power at high temperatures, low-temperature adhesion, and adhesion to low-polarity adherends, R 5 In the formula (4), n is preferably 7 to 18, more preferably 7 to 14, and even more preferably 7. In order to improve the adhesive performance, 4 is preferably H. Therefore, the polymer (X2) is a polymer having n of 7 to 18 in the general formula (4) and R 5 It is preferable that the copolymer contains a structural unit derived from a monomer (A2) in which n is 7 and R 5 It is more preferable that the monomer (A2) contains a structural unit derived from a linear monomer (A2), and in this case, the monomer (A2) is R 4 It is more preferred that is H.

[0084] Specific examples of the monomer (A2) include n-heptyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, n-decyl (meth)acrylate, 2-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-undecyl (meth)acrylate, n-tetradecyl (meth)acrylate (myristyl (meth)acrylate), n-octadecyl (meth)acrylate, etc. These monomers (A2) may be used alone or in combination of two or more. Specific examples of the monomer (B2) include vinyl caprate, vinyl laurate, vinyl caprylate, vinyl nonanoate, etc. These monomers (B2) may be used alone or in combination of two or more. Among the above-mentioned monomers (A2) and (B2), n-heptyl (meth)acrylate, n-tetradecyl (meth)acrylate, and n-octadecyl (meth)acrylate are preferred, and among these, n-heptyl (meth)acrylate is more preferred, and n-heptyl acrylate is even more preferred. Use of n-heptyl (meth)acrylate, n-tetradecyl (meth)acrylate, and n-octadecyl (meth)acrylate facilitates improvement of holding power at high temperatures, low-temperature adhesion, and adhesion to low-polarity adherends. In this specification, the term "(meth)acrylate" is used to mean either or both of acrylate and methacrylate, and the same applies to other similar terms.

[0085] In addition, in the above general formulas (4) and (5), R 5 and R 6 Preferably, R is carbon derived from a living organism, particularly a plant. 5 and R 6 By using carbon derived from living organisms, the bio-ratio, which will be described later, can be increased. 5 and R 6 Monomers (A2) and (B2), each of which is made of carbon derived from living organisms, can be obtained cheaply and easily by alcoholizing and esterifying saturated fatty acids and unsaturated fatty acids extracted from plants and animals.

[0086] In the present invention, the content of structural units derived from monomer (Y2) (i.e., at least one monomer selected from monomer (A2) and monomer (B2)) in polymer (X2) is preferably 48 mass% or more. When this content is 48 mass% or more, it becomes easy to improve the holding power at high temperatures, the low-temperature adhesion, and the adhesion to low-polarity adherends while increasing the bio content. From the viewpoint of improving the various performances described above while increasing the bio content, the content of the structural units derived from monomer (Y2) is more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. Furthermore, the content of the structural units derived from monomer (Y2) is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97.5% by mass or less, for example, to contain a predetermined amount of a functional group-containing monomer described later.

[0087] As described above, the monomer (A2) preferably contains at least one (meth)acrylate selected from the group consisting of n-heptyl (meth)acrylate, n-tetradecyl (meth)acrylate, and n-octadecyl (meth)acrylate. From the viewpoint of increasing the bio content and improving the various performance characteristics described above, the content of structural units derived from these (meth)acrylates in the polymer (X2) is preferably 48% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. The content of structural units derived from these (meth)acrylates is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97.5% by mass or less.

[0088] Furthermore, the monomer (A2) preferably contains n-heptyl (meth)acrylate, and more preferably contains n-heptyl (meth)acrylate as the main monomer from the viewpoint of tan δ (23°C) and from the viewpoint of increasing the bio content and improving the various performances described above. Specifically, the content of the n-heptyl (meth)acrylate-derived structural unit in the polymer (X2) is preferably 48% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Furthermore, the content of the n-heptyl (meth)acrylate-derived structural unit is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97.5% by mass or less. The n-heptyl (meth)acrylate is preferably n-heptyl acrylate.

[0089] The polymer (X2) preferably contains a structural unit derived from a monomer other than the above-mentioned monomer (A2) and monomer (B2). The other monomer may be a monomer having a polymerizable carbon-carbon double bond, such as a vinyl group or a (meth)acryloyl group. The other monomer is preferably a monomer containing a polar group (hereinafter also referred to as "polar group-containing monomer (C)"). When the polymer (X2) contains a structural unit derived from the polar group-containing monomer (C), the adhesive strength of the pressure-sensitive adhesive is easily increased, and the holding power at high temperatures, the adhesiveness at low temperatures, and the adhesion to low-polarity adherends are also easily improved. The polar group is a functional group having active hydrogen, and specific examples thereof include a carboxyl group, a hydroxyl group, an amino group, and an amide group. The polar group may be a functional group capable of reacting with a crosslinking agent, which will be described later. The polar group-containing monomer (C) may be used alone or in combination of two or more types. The polar group-containing monomer (C) is the same as that described in the first aspect of the invention, and therefore a detailed description thereof will be omitted.

[0090] The weight-average molecular weight (Mw) of the polymer (X2) is preferably 200,000 or more and 1,100,000 or less. When the weight-average molecular weight (Mw) is 200,000 or more, the shear strength of the adhesive can be increased, and the adhesive's holding power at high temperatures can be increased. When the weight-average molecular weight (Mw) is 1,100,000 or less, the adhesive strength of the adhesive can be improved, and low-temperature application properties and adhesion to low-polarity adherends can be easily improved. From these viewpoints, the weight average molecular weight (Mw) is more preferably 300,000 or more, and even more preferably 400,000 or more, and is more preferably 1,050,000 or less, and even more preferably 1,000,000 or less. The weight average molecular weight (Mw) can be adjusted appropriately by appropriately selecting the amount of polymerization initiator used, polymerization conditions such as polymerization temperature, polymerization method, and the like. The weight average molecular weight is a weight average molecular weight measured by gel permeation chromatography (GPC) and converted into standard polystyrene.

[0091] The polymer (X2) is the main component of the PSA. To provide suitable adhesive performance, the content of the polymer (X2) in the PSA is, for example, 50% by mass or more, preferably 60% by mass or more, and more preferably 65% ​​by mass or more. Furthermore, to allow for the blending of predetermined amounts of components other than the polymer (X2), such as a tackifier and a crosslinking agent, in the PSA, the content of the polymer (X2) in the PSA is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 92% by mass or less.

[0092] Since the low molecular weight components of polymer (X2) become the sol component, the above-mentioned properties of the sol component of the PSA can be adjusted by changing the molecular weight and molecular weight distribution of polymer (X2) through the polymerization method. Furthermore, since the low molecular weight components of polymer (X2) remain in the PSA without being crosslinked by changing the amount of crosslinking agent, the above-mentioned properties of the sol component of the PSA can be adjusted by changing the amount of crosslinking agent. Examples of the low molecular weight components of polymer (X2) include oligomers derived from the monomers that are raw materials for polymer (X2).

[0093] <Method for producing polymer (X2)> The polymer (X2) can be obtained by subjecting a mixture of the above-mentioned raw monomers to a radical reaction in the presence of a polymerization initiator, which allows the molecular weight distribution of the polymer (X2) to be significantly broadened and the sol fraction to be increased. The radical reaction method is not particularly limited, and examples include free radical polymerization and living radical polymerization. Free radical polymerization can broaden the molecular weight distribution compared to living radical polymerization, thereby increasing the amount of low-molecular-weight components produced. As a result, the sol content of the pressure-sensitive adhesive can be increased, and while increasing the bio-content, the adhesive can further improve its holding power at high temperatures, its low-temperature adhesion, and its adhesion to low-polarity substrates. The polymerization method is not particularly limited, and conventionally known methods can be used. Examples include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization. Among these, solution polymerization is preferred due to its ease of synthesis. The method for producing polymer (X2) is similar to the method for producing polymer (X1) described in the first invention section, and therefore a detailed description is omitted.

[0094] In the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet of the present invention, a low-molecular-weight component (Z) may be added to the polymer obtained by the above-mentioned production method to form polymer (X2). As described above, by changing the molecular weight and molecular weight distribution of polymer (X2) using a polymerization method, the above-mentioned properties of the sol component of the pressure-sensitive adhesive in the pressure-sensitive adhesive sheet of the present invention can be adjusted to fall within the above-mentioned ranges. However, even if a low-molecular-weight component (Z) is used, the above-mentioned properties of the sol component of the pressure-sensitive adhesive in the pressure-sensitive adhesive sheet of the present invention can be adjusted to fall within the above-mentioned ranges. In addition, the low-molecular-weight component (Z) also functions as a tackifier. The low-molecular-weight component (Z) is preferably an oligomer of a monomer that serves as a raw material for the polymer (X2). Therefore, the low-molecular-weight component (Z) is preferably an oligomer containing a structural unit derived from at least one monomer (Y2) selected from the group consisting of the monomer (A2) represented by the general formula (4) and the monomer (B2) represented by the general formula (5). The monomers used for the low-molecular-weight component (Z) have already been described in the section on the polymer (X2), and therefore further description of the monomers used for the low-molecular-weight component (Z) is omitted here.

[0095] As with the polymer (X2), among the above-mentioned monomers (A2) and (B2), n-heptyl(meth)acrylate, tetradecyl(meth)acrylate, and octadecyl(meth)acrylate are preferred, with n-heptyl(meth)acrylate being more preferred and n-heptylacrylate being even more preferred. Therefore, the low-molecular-weight component (Z) is preferably an n-heptyl(meth)acrylate oligomer, a tetradecyl(meth)acrylate oligomer, or an octadecyl(meth)acrylate oligomer, with n-heptyl(meth)acrylate oligomer being more preferred and n-heptylacrylate oligomer being even more preferred. The content of the low-molecular-weight component (Z) in the polymer (X2) is not particularly limited, and may be adjusted appropriately so that the various properties of the gel fraction fall within the above ranges.

[0096] <Tackifier> The pressure-sensitive adhesive in the pressure-sensitive adhesive sheet of the present invention preferably contains a tackifier in addition to the polymer (X2). Note that the tackifier added to the polymer (X2) is the same as the tackifier added to the polymer (X1) described in the first aspect of the invention, except for the content, as described below, and therefore further description is omitted.

[0097] When the PSA contains a tackifier, the content of the tackifier is not particularly limited, but is preferably 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of polymer (X2). Setting the content of the tackifier to be equal to or more than the above-mentioned lower limit facilitates improving low-temperature application properties and adhesion to low-polarity adherends. Setting the content to be equal to or less than the above-mentioned upper limit prevents a decrease in holding power at high temperatures. From these viewpoints, in the second invention, the content of the tackifier is more preferably 12 parts by mass or more and 40 parts by mass or less, and even more preferably 14 parts by mass or more and 30 parts by mass or less.

[0098] <Crosslinking agent> The PSA in the PSA sheet of the present invention is preferably crosslinked by blending a crosslinking agent. That is, the PSA is preferably a crosslinked PSA composition containing the above-mentioned polymer (X2), or the polymer (X2) and a tackifier, as well as a crosslinking agent. The crosslinking agent added to the polymer (X2) is the same as the crosslinking agent added to the polymer (X1) described in the first invention section, except for the blending amount, as described below, so further explanation is omitted.

[0099] The amount of crosslinking agent in the pressure-sensitive adhesive may be appropriately changed depending on the type of polymer (X2), the desired physical properties such as the degree of crosslinking, etc., but in the second invention, the amount is, for example, from 0.1 to 20 parts by mass, preferably from 0.5 to 8 parts by mass, and more preferably from 0.6 to 4 parts by mass, per 100 parts by mass of polymer (X2).

[0100] <Other additives> The pressure-sensitive adhesive in the pressure-sensitive adhesive sheet of the present invention may contain additives such as a silane coupling agent, an antioxidant, an ultraviolet protection agent, a plasticizer, an emulsifier, a softener, a filler, a pigment, a dye, etc. From the viewpoint of increasing the bio content, it is preferable to select biologically derived materials as much as possible for these additives.

[0101] <Preparation of adhesive> The adhesive in the pressure-sensitive adhesive sheet of the present invention may be formed, for example, by preparing a pressure-sensitive adhesive composition and using the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition is composed of components for forming a pressure-sensitive adhesive. The pressure-sensitive adhesive composition preferably contains the above-mentioned polymer (X2). The pressure-sensitive adhesive composition may further contain a tackifier, a crosslinking agent, other additives, etc., as necessary. The pressure-sensitive adhesive composition may be diluted with a diluent such as an organic solvent. The diluent may be the solvent used when synthesizing the polymer (X2), or may be added after the synthesis of the polymer (X2). The pressure-sensitive adhesive composition may be crosslinked by heating and drying as needed to form a pressure-sensitive adhesive. The pressure-sensitive adhesive is used in the pressure-sensitive adhesive sheet of the present invention. By appropriately setting the heating temperature during crosslinking, the peak top molecular weight of the sol component can be appropriately adjusted. The heating temperature during crosslinking is not particularly limited, but is, for example, 90°C to 130°C, preferably 100°C to 120°C. The heating time is, for example, 30 seconds to 10 minutes, preferably 1 minute to 5 minutes. In order to further promote the crosslinking reaction, it is preferable to cure the pressure-sensitive adhesive after drying. The curing temperature is preferably 20°C to 60°C, more preferably 30°C to 50°C. The curing time is preferably 1 day to 10 days, more preferably 2 days to 5 days.

[0102] <Adhesive sheet> The pressure-sensitive adhesive sheet of the present invention comprises the pressure-sensitive adhesive described above, specifically, comprises a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive described above. The pressure-sensitive adhesive sheet may be a pressure-sensitive adhesive sheet without a substrate or a pressure-sensitive adhesive sheet with a substrate, but is preferably a pressure-sensitive adhesive sheet with a substrate. An example of a pressure-sensitive adhesive sheet that does not have a substrate is a non-supported tape. A non-supported tape is a double-sided pressure-sensitive adhesive tape that does not have a substrate and is used in the state of a single pressure-sensitive adhesive layer. An example of a pressure-sensitive adhesive sheet that has a substrate is a pressure-sensitive adhesive tape. The pressure-sensitive adhesive tape comprises a substrate and a pressure-sensitive adhesive layer provided on at least one side of the substrate. In this case, the pressure-sensitive adhesive tape may be a double-sided pressure-sensitive adhesive tape in which the pressure-sensitive adhesive layer is provided on both sides of the substrate, or a single-sided pressure-sensitive adhesive tape in which the pressure-sensitive adhesive layer is provided on only one side of the substrate. In a double-sided adhesive tape having adhesive layers on both sides of a substrate, at least one of the adhesive layers may be made of the adhesive described above.

[0103] In the pressure-sensitive adhesive sheet, the exposed surface of the pressure-sensitive adhesive layer may be protected by an appropriate release sheet. The release sheet is a release sheet substrate having at least one surface coated with a release agent to form a release surface, and is preferably attached so that the release surface comes into contact with the pressure-sensitive adhesive layer.

[0104] [Base material] The substrate used in the pressure-sensitive adhesive sheet is not particularly limited, but is preferably a resin film, a nonwoven fabric, or a foam. Note that the substrate used in the pressure-sensitive adhesive sheet is the same as the substrate of the pressure-sensitive adhesive tape described in the first invention, and therefore a description thereof will be omitted.

[0105] In the pressure-sensitive adhesive sheet, the thickness of the pressure-sensitive adhesive layer is not particularly limited, but may be, for example, about 5 μm to 200 μm, preferably 10 μm to 100 μm. When the thickness of the pressure-sensitive adhesive layer is within this range, the resulting pressure-sensitive adhesive sheet can exhibit sufficient adhesive strength. The total thickness of the pressure-sensitive adhesive sheet (the sum of the thicknesses of the substrate and the pressure-sensitive adhesive layer) is preferably 10 μm or more and 2200 μm or less. When the total thickness of the pressure-sensitive adhesive sheet is within this range, the resulting pressure-sensitive adhesive sheet can exhibit sufficient adhesive strength.

[0106] (tack value) The adhesive of the adhesive sheet of the present invention preferably has a peel limit of 90 gf·s or more at 23° C. as measured by a tack test. The tack test is carried out as follows. First, a 50μm thick adhesive layer is applied to a 23μm thick PET substrate and an adhesive tape is placed on the plate of a tack tester (such as the Rhesca TAC-1000) set to 23°C. The adhesive layer is then placed on top. The tape is secured from above with the sample holder attached to the tack tester. Next, a 5mm diameter cylindrical stainless steel probe is pressed against the adhesive tape at a probe temperature of 23°C, a pressing speed of 5mm / s, and a pressing load of 100gf, and held in this position for 10 seconds. The probe is then pulled up at a lifting speed of 5mm / s. The force applied to the adhesive tape during this period is measured. The above explanation has been given on an example where the adhesive constitutes an adhesive tape, but even if it does not constitute an adhesive tape, the adhesive can be placed on a plate of a tack tester set to 23°C and measured in the same manner.

[0107] The peel limit value means the integral value from time T1, when the force is 0, to the time when the maximum force (peak top) is reached in the force-time curve showing the force applied to the adhesive tape at 23°C measured by the tack test. In the tack test, when the probe is pressed against the adhesive tape, the force-time curve descends, and then when the probe begins to be pulled up, the force-time curve ascends. The integral value from time T1, when the force is 0, to time T2, when the maximum force (peak top) is reached is calculated, and this is defined as the peel limit value. By adjusting the peel strength within the above range, peeling of the adhesive tape can be suppressed even under conditions of high temperature and high humidity and a restoring force. The lower limit of the peel strength is preferably 100 gf·s, and more preferably 110 gf·s. The upper limit of the peel strength is not particularly limited.

[0108] <Bio rate> From the same viewpoint as the pressure-sensitive adhesive described above, the pressure-sensitive adhesive sheet of the present invention preferably has a bio content of 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. The higher the bio content, the better, provided that it is 100% by mass or less. Generally, the bio content of a pressure-sensitive adhesive sheet differs depending on the components (e.g., the pressure-sensitive adhesive layer and the substrate). Therefore, the bio content may be calculated by determining the bio content of each component and calculating a weighted average using the mass of each component as a weight.

[0109] (Method of manufacturing pressure-sensitive adhesive sheet) The method for producing the pressure-sensitive adhesive sheet is not particularly limited, and the sheet can be produced by a conventionally known production method. Note that the method for producing the pressure-sensitive adhesive sheet is the same as the method for producing the pressure-sensitive adhesive tape described in the first aspect of the invention, and therefore a description thereof will be omitted.

[0110] (Applications of adhesive sheets) The use of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but it is preferably used in electrical appliances and vehicles. Note that the method for producing the pressure-sensitive adhesive sheet is the same as the use of the pressure-sensitive adhesive and pressure-sensitive adhesive tape described in the first invention, so a description thereof will be omitted.

[0111] The present invention may be a combination of the first and second inventions. [Example]

[0112] The present invention will be described below with reference to examples, but the present invention is not limited to the scope of the examples.

[0113] <<First Example>> [Measurement and evaluation methods] Measurement and evaluation of each physical property was carried out as follows. <Elastic modulus> The storage modulus G', loss modulus G'', and glass transition temperature (Tg) at each temperature were measured under the following conditions using a polymer dynamic viscoelasticity measuring device "itkDVA-200" (manufactured by IT Measurement Control Co., Ltd.). Measurement mode: Shear Heating rate: 5°C / min Measurement temperature range: -30 to 150°C Setting distortion: 0.1% Frequency: 10Hz In the present Examples and Comparative Examples, the measurement samples were prepared by molding the pressure-sensitive adhesive composition solutions prepared in each Example so that the final sample shape was 0.1 mm in thickness, 0.6 mm in width, and 10 mm in length, and then heating and drying under the same conditions as those used for forming the pressure-sensitive adhesive layer in each Example.

[0114] <Weight average molecular weight> The weight-average molecular weight (Mw) of polymer (X1) was measured using a GPC apparatus "HLC822GPC" (manufactured by Tosoh Corporation) and calculated as a polystyrene equivalent value. Specifically, the obtained polymer (X1) was diluted 50 times with tetrahydrofuran (THF), and the resulting diluted solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare a measurement sample. This measurement sample was supplied to a gel permeation chromatograph (manufactured by 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 polymer (X1) was measured, and the weight-average molecular weight was calculated.

[0115] <Crosslinking degree> W1 (g) of pressure-sensitive adhesive (sample) was collected, and the collected sample was immersed in ethyl acetate at 23°C for 24 hours. The insoluble matter was filtered through a 200-mesh wire netting. The residue on the wire netting was dried at 110°C for 1 hour, and the mass after drying, W2 (g), was measured. The gel fraction (degree of cross-linking) was calculated using the following formula: Gel fraction (mass%) = 100 × W2 / W1 <Bio rate> The bio-content of the adhesive was measured in accordance with ASTM 6866.

[0116] <Low temperature adhesion> According to JIS Z-1528 "Double-Sided Adhesive Tape," one side of a double-sided adhesive tape cut to a width of 25 mm and a length of 100 mm was bonded to a 2 mm thick, 50 mm wide, and 100 mm long polypropylene plate (Takiron Co., Ltd., PP1300) at 0°C, resulting in a 75 mm adhesive length. The other side of the double-sided adhesive tape was backed with a PET film and then pressed back and forth with a 2 kg roller at 0°C to create an adhesion test specimen. The resulting adhesion test specimen was then left in a 0°C atmosphere for 60 minutes. After that, the specimen was peeled from the polypropylene plate at a 0°C environment using an Instron testing machine at a pulling rate of 200 mm / min and a peel angle of 180° to measure the peel strength (N / 25 mm). Based on the peel strength results, low-temperature adhesion was evaluated according to the following criteria. A: The peel strength is 5 N / 25 mm or more. B: The peel strength is 3 N / 25 mm or more and less than 5 N / 25 mm. C: Less than 3 N / 25 mm.

[0117] <PP Adhesive Strength> In accordance with JIS Z-1528 "Double-sided Adhesive Tape", one side of a double-sided adhesive tape cut to a width of 25 mm and a length of 100 mm was bonded to a polypropylene plate (manufactured by Takiron Co., Ltd., PP1300) with a thickness of 2 mm, a width of 50 mm, and a length of 100 mm at 23°C and 50% RH so that the bonding length was 75 mm. After backing the other side of the double-sided adhesive tape with a PET film, a bonding test piece was prepared by pressing it once back and forth with a 2 kg roller at 23°C and 50% RH. After leaving the obtained bonding test piece in an atmosphere of 23°C and 50% RH for 20 minutes, it was pulled using an Instron testing machine at a pulling speed of 200 mm / min and peeled from the polypropylene plate at a peeling angle of 180°, and the peel strength (N / 25 mm) was measured at 23°C. Based on the results of the peel strength, the PP adhesive strength was evaluated according to the following evaluation criteria. A: The peel strength is 15 N / 25 mm or more. B: The peel strength is 10 N / 25 mm or more and less than 15 N / 25 mm. C: The peel strength is less than 10 N / 25 mm.

[0118] <Retention Force at High Temperature> In accordance with JISZ-1528, one side of a double-sided adhesive tape cut to a width of 25 mm and a length of 100 mm was bonded to a cold-rolled stainless steel plate (SUS304 plate) with a thickness of 1.5 mm, a width of 25 mm, and a length of 100 mm at 23°C so that the bonding length was 25 mm, and the double-sided adhesive tape with a length of 75 mm protruded from the end of the SUS304 plate and was bonded by shifting it in the length direction. Then, after backing the other side of the double-sided adhesive tape with a PET film, a bonding test piece was prepared by pressing it once back and forth with a 2 kg roller. <The resulting adhesive test piece was left in an atmosphere of 23°C and 50% RH for 20 minutes, and then hung vertically in a thermostatic oven at 40°C for 1 hour with the protruding double-sided adhesive tape side facing downwards. Next, a 1 kg load was placed on the bottom end of the double-sided adhesive tape, and the test piece was hung vertically at 40°C for 24 hours. After 1 hour, the slippage distance (mm) of the adhesive portion was measured. Evaluation was based on the slippage distance and using the following criteria. A: The deviation distance is less than 0.5 mm. B: The deviation distance is 0.5 mm or more and less than 2 mm. C: The deviation distance is 2 mm or more.

[0119] The components used in the examples and comparative examples are as follows. <Monomer (A1)> (Main monomer) n-Heptyl acrylate (HA(C7)): n-Heptyl acrylate is represented by the general formula (1) 2 It is a compound containing carbon derived from living organisms, and was prepared by the esterification reaction of acrylic acid with n-heptyl alcohol. n-Heptyl alcohol was prepared by cracking ricinoleic acid derived from castor oil. (comonomer) 2-Ethylhexyl acrylate (2EHA): Mitsubishi Chemical Corporation <Other Monomers> Butyl acrylate (BA): Mitsubishi Chemical Corporation Acrylic acid (AAc): Nippon Shokubai Co., Ltd. 2-Hydroxyethyl acrylate (HEA): manufactured by Osaka Organic Chemical Industry Co., Ltd. <Tackifier (TF)> Polymerized rosin ester resin, hydroxyl value 46, softening point 150°C, bio-derived carbon content 95% by mass <Crosslinking agent> Polyisocyanate crosslinking agent, Tosoh Corporation's "Coronate L-45"

[0120] Example 1 [Synthesis of polymer (X1)] Ethyl acetate was added as a polymerization solvent to a reaction vessel, and nitrogen was bubbled through. The reaction vessel was then heated while nitrogen was flowing in to initiate reflux. Next, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile 10 times with ethyl acetate was added to the reaction vessel, and 96.9 parts by mass of n-heptyl acrylate (HA(C7)), 2.9 parts by mass of acrylic acid (AAc), and 0.2 parts by mass of 2-hydroxyethyl acrylate (HEA) were added dropwise over two hours. After the dropwise addition, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile 10 times with ethyl acetate was added again to the reaction vessel, and the polymerization reaction was carried out for four hours to obtain a solution containing polymer (X1). The weight-average molecular weight of the resulting polymer (X1) was measured and found to be 600,000.

[0121] [Preparation of double-sided adhesive tape] To the obtained polymer (X1)-containing solution, 0.8 parts by mass of a crosslinker and 15 parts by mass of a tackifier were added per 100 parts by mass of polymer (X1), to prepare a pressure-sensitive adhesive composition solution. This pressure-sensitive adhesive composition solution was applied to the release surface of a release sheet, one side of which had been release-treated, and then heated and dried to form a pressure-sensitive adhesive layer. The obtained pressure-sensitive adhesive layer was transferred to both sides of a nonwoven fabric substrate, to obtain a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both sides of the substrate. The adhesive was sampled from the adhesive layer of the obtained double-sided adhesive tape, and the degree of crosslinking and bio-ratio were measured. In addition, measurement samples were prepared from the adhesive composition solution, and the storage modulus G', loss modulus G", and glass transition temperature (Tg) were measured. Furthermore, the double-sided adhesive tape was used to evaluate the low-temperature adhesion, PP adhesive strength, and holding power at high temperatures. The evaluation results are shown in Table 2.

[0122] (Examples 2 and 3) The same procedure as in Example 1 was carried out except that the blending amounts of the tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1.

[0123] Example 4 The same procedure as in Example 1 was carried out, except that the polymerization reaction time in the production of polymer (X1) was changed to 5 hours.

[0124] Example 5 The same procedures as in Example 1 were carried out except that the polymerization reaction time in the production of polymer (X1) was changed to 5.5 hours and the amount of crosslinking agent added was changed to the parts by mass shown in Table 1.

[0125] Example 6 The same procedure as in Example 1 was carried out except that the amounts of the monomers used to prepare the polymer (X1) were changed to the proportions shown in Table 1, and the amounts of the tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1.

[0126] (Comparative Example 1) The same procedure as in Example 1 was carried out except that the polymerization reaction time in the production of polymer (X1) was changed to 7 hours, and the amounts of tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1.

[0127] (Comparative Example 2) The same procedure as in Example 1 was carried out except that the polymerization reaction time in the production of polymer (X1) was changed to 2.5 hours, and the amounts of the tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1.

[0128] (Comparative Example 3) The same procedure as in Example 1 was carried out except that the types and amounts of monomers used to prepare the polymer (X1) were changed as shown in Table 1, and the amounts of tackifier (TF) and crosslinker were changed to the parts by mass shown in Table 1.

[0129] [Table 1] *Molecular weight is the weight average molecular weight (Mw). *The parts by mass of the monomers are values ​​when the total amount of the monomers blended when synthesizing polymer (X1) is taken as 100 parts by mass. Polymer (X1) can be considered to contain the constituent units derived from each monomer listed in Table 1 in the amounts listed in Table 1. *The blending amounts of tackifier (TF) and crosslinking agent are in parts by mass relative to 100 parts by mass of polymer (X1).

[0130] [Table 2]

[0131] In each of the above Examples, the PSA contained polymer (X1) containing a predetermined amount or more of structural units derived from monomer (A1) and had a tan δ (23°C) of 0.8 to 1.3, thereby achieving good holding power at high temperatures, good low-temperature adhesion, and good adhesion to low-polarity adherends (polypropylene resins). In contrast, in each of the Comparative Examples, the polymer (X1) did not contain a predetermined amount or more of structural units derived from monomer (A1), or the tan δ (23°C) was outside the range, so it was not possible to achieve good holding power at high temperatures, good low-temperature adhesion, and good adhesion to low-polarity adherends (polypropylene resins) while increasing the bio content.

[0132] <<Second Example>> [Measurement and evaluation methods] Measurement and evaluation of each physical property was carried out as follows. <Peak top molecular weight (Mtp)> The adhesive sample collected from the adhesive tape was immersed in tetrahydrofuran (THF) and left to soak for 24 hours with shaking at room temperature. A sample of the adhesive was then removed using a 200-mesh filter, and the immersion liquid was filtered through the filter. The resulting filtrate was used as a sample solution containing the sol fraction of the adhesive. The resulting sample solution was fed to a gel permeation chromatography (GPC, e.g., Waters "e2695") and subjected to GPC measurement using tetrahydrofuran (THF) as the mobile phase at a sample flow rate of 1 mL / min and a column temperature of 40°C to measure the molecular weight distribution (Mp) in terms of polystyrene. For example, two Shodex "GPC KF-806L" columns connected in series were used. The peak top molecular weight (Mtp) of the adhesive sol fraction was calculated from the resulting molecular weight distribution curve. Note that the GPC peak derived from the tackifier (TF) was not included. Therefore, the peak top molecular weight (Mtp) of the sol fraction of the adhesive measured by GPC is the peak top molecular weight of the sol fraction of the polymer that is the main component of the adhesive measured by GPC.

[0133] Weight average molecular weight (Mw), dispersity (D), sol fraction (R sol ) and hardness (S), > In the same manner as in the measurement of the peak top molecular weight (Mtp) described above, the weight average molecular weight and number average molecular weight of the sol component of the pressure-sensitive adhesive were measured using GPC. The obtained weight average molecular weight was then divided by the number average molecular weight to calculate the dispersity (D) of the sol component. The gel fraction was also measured using the following method, and the gel fraction was subtracted from 100% by mass to obtain the sol fraction (R sol The weight average molecular weight (Mw), dispersity (D) and sol fraction (R sol ) and calculated the hardness (S). Note that the peaks by GPC derived from the tackifier (TF) were not included. Therefore, the weight average molecular weight (Mw) and dispersity (D) of the sol component of the PSA are the weight average molecular weight and dispersity of the sol component of the polymer, which is the main component of the PSA.

[0134] An adhesive (sample) was taken in an amount of W1 (g), and when the taken sample was immersed in THF at 23°C for 24 hours, the insoluble matter was filtered through a 200-mesh wire mesh. The residue on the wire mesh was dried at 110°C for 1 hour, and the mass W2 (g) after drying was measured, and the gel fraction was calculated by the following formula. Gel fraction (mass %) = 100 × W2 / W1

[0135] <Glass transition temperature (Tg)> The glass transition temperature (Tg) was measured in the same manner as the measurement method of the glass transition temperature (Tg) in the first embodiment.

[0136] <Bio-based ratio> The bio-based ratio of the adhesive was measured in accordance with ASTM 6866.

[0137] <Elastic modulus> The storage elastic modulus G' and the loss elastic modulus G'' at each temperature were measured under the same conditions as the measurement method of the elastic modulus in the first embodiment. Note that the storage elastic modulus G', the loss elastic modulus G'', and tanδ at each temperature are shown only for the results of some of the embodiments and comparative examples.

[0138] <PP adhesion> The peel strength (N / 25 mm) at 23°C was measured in the same manner as the PP adhesion in the first embodiment. Based on the results of the peel strength, the PP adhesion was evaluated according to the following evaluation criteria. A: The peel strength is 13 N / 25 mm or more. B: The peel strength is 10 N / 25 mm or more and less than 13 N / 25 mm. C: The peel strength is less than 10 N / 25 mm.

[0139] [[ID=:36]]<Retention force at high temperature> The displacement distance (mm) of the bonded part after 1 hour was measured in the same manner as the retention force at high temperature in the first embodiment. Based on the displacement distance, the following evaluation criteria were used for evaluation. A: The displacement distance is 0.5 mm or less. B: The displacement distance is more than 0.5 mm and less than 1 mm. C: The displacement distance is 1 mm or more.

[0140] <Low temperature adhesion> The low-temperature adhesion was evaluated in the same manner as in the first example.

[0141] The components used in the examples and comparative examples are as follows. <Monomer (A2)> (Main monomer) n-Heptyl acrylate (HA(C7)): n-Heptyl acrylate is represented by the general formula (2) R 5 It is a plant-derived compound, prepared by the esterification of acrylic acid with n-heptyl alcohol, which was prepared by cracking ricinoleic acid derived from castor oil. <Other Monomers> Acrylic acid (AAc): Nippon Shokubai Co., Ltd. 2-Hydroxyethyl acrylate (HEA): manufactured by Osaka Organic Chemical Industry Co., Ltd. <Tackifier (TF)> Polymerized rosin ester resin, hydroxyl value 46, softening point 150°C, plant-derived carbon content 95% by mass <Crosslinking agent> Polyisocyanate crosslinking agent

[0142] Example 7 [Synthesis of polymer (X2)] Ethyl acetate was added to the reaction vessel as the polymerization solvent, and nitrogen was bubbled through. The reaction vessel was then heated while nitrogen was flowing in to initiate reflux. Next, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile 10 times with ethyl acetate was added to the reaction vessel, and 96.9 parts by mass of n-heptyl acrylate (HA(C7)), 2.9 parts by mass of acrylic acid (AAc), and 0.2 parts by mass of 2-hydroxyethyl acrylate (HEA) were added dropwise over 2 hours. After the dropwise addition, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile 10 times with ethyl acetate was added again to the reaction vessel, and the polymerization reaction was carried out for 3.5 hours to obtain a solution containing polymer (X2). The weight-average molecular weight of the resulting polymer (X2) was measured and found to be 500,000.

[0143] [Preparation of double-sided adhesive tape] To the obtained polymer (X2)-containing solution, 25 parts by mass of a tackifier and 2.4 parts by mass of a crosslinker were added per 100 parts by mass of polymer (X2), to prepare a pressure-sensitive adhesive composition solution. This pressure-sensitive adhesive composition solution was applied to the release surface of a release sheet, one side of which had been release-treated, and heated and dried at 100°C for 3 minutes to form a pressure-sensitive adhesive layer. The obtained pressure-sensitive adhesive layer was transferred to both sides of a nonwoven fabric substrate, to obtain a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both sides of the substrate. The adhesive was collected from the adhesive layer of the obtained double-sided adhesive tape, and the peak top molecular weight (Mtp), weight average molecular weight (Mw), dispersity (D), sol fraction (R sol The adhesive strength, hardness (S), hardness / softness (S), and bio content were measured. Measurement samples were also prepared from the pressure-sensitive adhesive composition solution and the glass transition temperature (Tg) was measured. Furthermore, double-sided pressure-sensitive adhesive tape was used to evaluate the PP adhesive strength, holding power at high temperatures, and low-temperature adhesion. The evaluation results are shown in Table 2.

[0144] (Examples 8 and 9) The same procedure as in Example 1 was carried out except that the blending amounts of the tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1.

[0145] Examples 10 to 14 In the production of polymer (X2), the polymerization reaction time was changed to change the weight average molecular weight of polymer (X2) from 500,000 to 800,000. Furthermore, the blending amounts of tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1. Other than that, the same procedure as in Example 1 was carried out.

[0146] (Examples 15 to 17) In the production of polymer (X2), the polymerization reaction time was changed to change the weight average molecular weight of polymer (X2) from 500,000 to 1,000,000. Furthermore, the blending amounts of tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1. Other than that, the same procedure as in Example 1 was carried out.

[0147] Comparative Example 4 In the production of polymer (X2), the polymerization reaction time was changed to change the weight average molecular weight of polymer (X2) from 500,000 to 800,000. Furthermore, the amount of tackifier (TF) added was changed to the parts by mass shown in Table 1. Other than that, the same procedures as in Example 1 were carried out.

[0148] (Comparative Example 5) The same procedure as in Example 1 was carried out except that the blending amounts of the tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1.

[0149] (Comparative Example 6) In the production of polymer (X2), the polymerization reaction time was changed to change the weight average molecular weight of polymer (X2) from 500,000 to 1,200,000. Furthermore, the blending amounts of tackifier (TF) and crosslinking agent were changed to the parts by mass shown in Table 1. Other than that, the same procedure as in Example 1 was carried out.

[0150] (Comparative Example 7) The same procedure as in Example 1 was carried out except that the amount of crosslinking agent was changed to the parts by mass shown in Table 3.

[0151] [Table 3] *Molecular weight is the weight average molecular weight (Mw). *The parts by mass of the monomers are values ​​when the total amount of the monomers blended when synthesizing polymer (X2) is taken as 100 parts by mass. Polymer (X2) can be considered to contain the constituent units derived from each monomer listed in Table 1 in the amounts listed in Table 1. *The blending amounts of tackifier (TF) and crosslinking agent are in parts by mass per 100 parts by mass of polymer (X2).

[0152] [Table 4]

[0153] In each of the above examples, the peak top molecular weight (Mtp) of the sol fraction of the adhesive by gel permeation chromatography (GPC) was 137,000 or more and 300,000 or less, and the sol fraction (R sol ) was 90% by mass or less, and the glass transition temperature (Tg) of the adhesive was 5°C or less. As a result, the adhesiveness to a low-polarity adherend (polypropylene resin), the holding power at high temperatures, and the low-temperature adhesion were all good. In contrast, in each of the comparative examples, the peak top molecular weight (Mtp) of the sol fraction of the adhesive measured by gel permeation chromatography (GPC) was outside the range of 137,000 or more and 300,000 or less, or the sol fraction (R sol ) was higher than 90% by mass, or the glass transition temperature (Tg) of the adhesive was higher than 5°C. For this reason, it was not possible to increase the bio content while improving all of the following: adhesion to a low-polarity adherend (polypropylene resin), holding power at high temperatures, and low-temperature adhesion.

Claims

1. The polymer (X1) contains 70 mass % or more of structural units derived from a monomer (Y) composed of a monomer (A1) represented by the following general formula (1), When the storage modulus at 23°C and a measurement frequency of 10 Hz is G'(23°C) and the loss modulus at 23°C and a measurement frequency of 10 Hz is G"(23°C), tan δ(23°C) calculated by G"(23°C) / G'(23°C) is 0.8 to 1.3, The content of biological carbon is 60% by mass or more, the monomer (A1) is n-heptyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, n-decyl (meth)acrylate, 2-octyl (meth)acrylate, n-nonyl (meth)acrylate, undecyl (meth)acrylate, tetradecyl (meth)acrylate, or myristyl (meth)acrylate; When the storage modulus at 0°C and a measurement frequency of 10 Hz is G'(0°C), log G'(0°C) [Pa] is 5.0 to 6.5, When the storage modulus at 80°C and a measurement frequency of 10 Hz is G'(80°C), log G'(80°C) [Pa] is 4.1 to 4.8, An adhesive having a glass transition temperature (Tg) of 15°C or lower (excluding adhesives containing a crosslinking monomer having a (meth)acrylate group and a C6 to C20 olefin group, and adhesives containing epoxidized vegetable oil). 【Chemical 1】 In formula (1), R １ is H or CH ３ represents R ２ Ga-C ｎ H ２ｎ＋１ and n is an integer of 7 to 14.

2. The pressure-sensitive adhesive according to claim 1, wherein the polymer (X1) has a weight-average molecular weight of 200,000 to 1,000,000.

3. The pressure-sensitive adhesive according to claim 1 or 2, wherein the degree of crosslinking is 10 to 70%.

4. The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein log G'(23°C) [Pa] is 4.8 to 5.5, where G'(23°C) is the storage modulus at 23°C and a measurement frequency of 10 Hz.

5. The pressure-sensitive adhesive according to any one of claims 1 to 4, further comprising a tackifier.

6. An adhesive tape comprising an adhesive layer made of the adhesive according to any one of claims 1 to 5.

7. The adhesive tape according to claim 6 , further comprising a substrate, the adhesive layer being provided on at least one surface of the substrate.

8. The pressure-sensitive adhesive tape according to claim 7, wherein the substrate is any one selected from the group consisting of a nonwoven fabric, a polyethylene terephthalate film, and a foam.

9. A method for fixing a component constituting an electrical appliance or an in-vehicle member using the adhesive according to any one of claims 1 to 5 or the adhesive tape according to any one of claims 6 to 8.

10. The adhesive according to any one of claims 1 to 5 is provided, The peak top molecular weight (Mtp) of the sol fraction of the pressure-sensitive adhesive as determined by gel permeation chromatography (GPC) is 137,000 or more and 300,000 or less, The sol fraction (R ｓｏｌ ) is 90% by mass or less, The pressure-sensitive adhesive sheet has a glass transition temperature (Tg) of 5°C or less.

11. An adhesive sheet comprising an adhesive containing a biological component, The peak top molecular weight (Mtp) of the sol fraction of the pressure-sensitive adhesive as determined by gel permeation chromatography (GPC) is 137,000 or more and 300,000 or less, The sol fraction (R ｓｏｌ ) is 90% by mass or less, The pressure-sensitive adhesive has a glass transition temperature (Tg) of 5°C or less, the pressure-sensitive adhesive contains a polymer (X2) containing 70 mass % or more of structural units derived from a monomer (Y2) composed of a monomer (A2) represented by the following general formula (4), The adhesive has a bio-derived carbon content of 60% by mass or more, The monomer (A2) is n-heptyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, n-decyl (meth)acrylate, 2-octyl (meth)acrylate, n-nonyl (meth)acrylate, undecyl (meth)acrylate, tetradecyl (meth)acrylate, myristyl (meth)acrylate, When the storage modulus at 0°C and a measurement frequency of 10 Hz is G'(0°C), log G'(0°C) [Pa] is 5.0 to 6.5, When the storage modulus at 80°C and a measurement frequency of 10 Hz is G'(80°C), log G'(80°C) [Pa] is 4.1 to 4.8, A pressure-sensitive adhesive sheet in which the dispersity (D) of the sol fraction of the pressure-sensitive adhesive as measured by GPC is 1.6 or more and less than 3 (excluding pressure-sensitive adhesive sheets containing a crosslinking monomer having a (meth)acrylate group and a C6 to C20 olefin group, and pressure-sensitive adhesive sheets containing epoxidized vegetable oil). 【Chemistry 2】 In formula (4), R ４ is H or CH ３ represents R ５ Ga-C ｎ H ２ｎ＋１ Represents.

12. The pressure-sensitive adhesive sheet according to claim 11, wherein the pressure-sensitive adhesive has a hardness (S) represented by the following general formula (3) of 50,000 or more and 180,000 or less: S=Mw×R ｓｏｌ / D (3) In formula (3), Mw represents the weight average molecular weight of the sol component of the PSA by GPC, and R ｓｏｌ represents the sol fraction in the pressure-sensitive adhesive, and D represents the dispersity of the sol fraction in the pressure-sensitive adhesive as determined by GPC.

13. The pressure-sensitive adhesive sheet according to claim 11 or 12, wherein the weight average molecular weight (Mw) of the sol fraction of the pressure-sensitive adhesive measured by GPC is 190,000 or more and 700,000 or less.

14. The sol fraction (R ｓｏｌ 14. The pressure-sensitive adhesive sheet according to claim 11, wherein the content of the polymerizable monomer is 45% by mass or more and 75% by mass or less.

15. The pressure-sensitive adhesive sheet according to any one of claims 11 to 14, wherein the pressure-sensitive adhesive has a glass transition temperature (Tg) of 2.5°C or lower.

16. The pressure-sensitive adhesive sheet according to any one of claims 11 to 15, wherein the pressure-sensitive adhesive has a bio-content of 51% or more.

17. The pressure-sensitive adhesive sheet according to any one of claims 11 to 16, wherein the content of structural units derived from n-heptyl (meth)acrylate in the polymer (X2) is 48 mass% or more.

18. An electrical appliance comprising the adhesive according to any one of claims 1 to 5, the adhesive tape according to any one of claims 6 to 8, or the adhesive sheet according to any one of claims 10 to 17.

19. An in-vehicle member comprising the pressure-sensitive adhesive according to any one of claims 1 to 5, the pressure-sensitive adhesive tape according to any one of claims 6 to 8, or the pressure-sensitive adhesive sheet according to any one of claims 10 to 17.

Images