KR20240023019A - adhesive tape - Google Patents

Abstract

일반식 (A) 및 (B) 중, R¹ 및 R² 는, 탄소수 4 ∼ 12 의 알킬기를 나타낸다.The present invention provides an adhesive tape that has a high content of biologically derived carbon and is excellent in shear holding power at high temperatures. The present invention is an adhesive tape having an adhesive layer containing an acrylic copolymer, wherein the acrylic copolymer contains a structural unit derived from an alkyl (meth)acrylate containing carbon of biological origin, and the adhesive layer It is an adhesive tape in which the total content of a compound having a structure represented by the following general formula (A) and a compound having a structure shown by the following general formula (B) is 2% by weight or less.
[Formula 1]

In general formulas (A) and (B), R ¹ and R ² represent an alkyl group having 4 to 12 carbon atoms.

Description

adhesive tape

The present invention relates to adhesive tapes.

Conventionally, when fixing components in electronic components, vehicles, houses, and building materials, adhesive tapes having an adhesive layer containing an adhesive have been widely used (for example, Patent Documents 1 to 3). Specifically, for example, adhesive tapes are used to adhere a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to adhere a touch panel module and a display panel module.

Japanese Patent Publication No. 2015-052050 Japanese Patent Publication No. 2015-021067 Japanese Patent Publication No. 2015-120876

Recently, the depletion of petroleum resources and the emission of carbon dioxide from combustion of petroleum-derived products have been raised as problems. Therefore, attempts have been made to save petroleum resources by using biologically derived materials instead of petroleum derived materials, mainly in the medical and packaging material fields. Such attempts have spread to all fields, and the use of biologically derived materials has come to be required even in the field of adhesives and adhesive tapes.

The purpose of the present invention is to provide an adhesive tape that has a high content of biologically derived carbon and has excellent shear holding power at high temperatures.

This disclosure 1 is an adhesive tape having an adhesive layer containing an acrylic copolymer, wherein the acrylic copolymer contains a structural unit derived from an alkyl (meth)acrylate containing carbon of biological origin, and the adhesive layer is an adhesive tape in which the total content of a compound having a structure represented by the following general formula (A) and a compound having a structure shown by the following general formula (B) is 2% by weight or less.

[Formula 1]

In general formulas (A) and (B), R ¹ and R ² represent an alkyl group having 4 to 12 carbon atoms.

This disclosure 2 provides that the pressure-sensitive adhesive layer includes a compound having a structure represented by the general formula (A), a compound having a structure represented by the general formula (B), and a compound having a structure represented by the following general formula (C). It is the adhesive tape of this disclosure 1 whose total content is 2 weight% or less.

[Formula 2]

In general formula (C), R ¹ and R ² represent an alkyl group having 4 to 12 carbon atoms.

This disclosure 3 is the adhesive tape of this disclosure 1 or 2, in which the adhesive layer has a content of less than 1% by weight of a compound having a structure represented by the general formula (A).

This disclosure 4 is the adhesive tape of this disclosure 1, 2, or 3, wherein the compound having a structure represented by the general formula (A) is a compound having a structure represented by the following formula (a1).

[Formula 3]

This disclosure 5 is the adhesive tape of this disclosure 1, 2, 3 or 4, in which the adhesive layer has a content of less than 1% by weight of a compound having a structure represented by the general formula (B).

This disclosure 6 is the adhesive tape of this disclosure 2, 3, 4 or 5, in which the adhesive layer has a content of less than 1% by weight of a compound having a structure represented by the general formula (C).

This disclosure 7 is the adhesive tape of this disclosure 1, 2, 3, 4, 5 or 6, wherein the compound having a structure represented by the general formula (B) is a compound having a structure represented by the following formula (b1).

[Formula 4]

This disclosure 8 is the adhesive tape of this disclosure 2, 3, 4, 5, 6 or 7, wherein the compound having a structure represented by the general formula (C) is a compound having a structure represented by the following formula (c1).

[Formula 5]

This disclosure 9 refers to present disclosure 1, 2, 3, 4, 5, 6, 7 or 8 in which the alkyl (meth)acrylate containing carbon derived from the organism contains n-heptyl (meth)acrylate. It is an adhesive tape.

The present disclosure 10 refers to the present disclosure 1, 2, 3, 4, 5, wherein the acrylic copolymer has a content of structural units derived from an alkyl (meth)acrylate containing carbon derived from the biological organism of 85% by weight or more. It is a 6, 7, 8 or 9 adhesive tape.

This disclosure 11 is the adhesive tape of this disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, in which the adhesive layer further contains a tackifying resin.

This disclosure 12 is the adhesive tape of this disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, in which the adhesive layer has a biologically derived carbon content of 10% by weight or more.

This disclosure 13 is the adhesive tape of this disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, which is used for fixing electronic device components or vehicle components.

In addition, in this specification, (meth)acrylate means acrylate or methacrylate, and (meth)acrylic means acrylic or methacrylic. The acrylic copolymer may be a methacrylic copolymer.

The present invention is described in detail below.

The present inventors studied the use of an alkyl (meth)acrylate containing biologically derived carbon as an acrylic monomer constituting the acrylic copolymer in an adhesive tape having an adhesive layer containing an acrylic copolymer. However, when alkyl (meth)acrylate containing biologically derived carbon was used, sufficient adhesive strength was not obtained, and for example, shear holding power at high temperatures was sometimes reduced.

As a result of examining the reason why sufficient adhesive strength was not obtained, the present inventors found that the cause was that alkyl (meth)acrylate containing carbon of biological origin contained impurities because it was of biological origin.

In particular, when a (meth)acrylate containing an alkyl group with a relatively large number of carbon atoms is used as an alkyl (meth)acrylate containing biologically derived carbon, the glass transition temperature (Tg) of the acrylic copolymer is sufficiently lowered, Excellent adhesion can be expected. However, (meth)acrylate containing biologically derived carbon and having an alkyl group with a relatively large carbon number contains dialkyl ethers and ether esters with an alkyl group with a relatively large carbon number as impurities. The present inventors have found that since these impurities remain even in the adhesive layer, when exposed to high temperatures, it is conceivable that, for example, the impurities bleed out and reduce cohesion, leading to a decrease in adhesive strength. I paid it.

In contrast, the present inventors adjusted the total content of specific compounds corresponding to impurities of alkyl (meth)acrylate containing biologically derived carbon in the adhesive layer to a certain value or less, thereby increasing the shear holding power at high temperature. It was discovered that an excellent adhesive tape could be obtained, and the present invention was completed.

The adhesive tape of the present invention has an adhesive layer containing an acrylic copolymer.

The acrylic copolymer contains structural units derived from alkyl (meth)acrylate containing carbon of biological origin. As a result, the adhesive tape of the present invention can exhibit excellent adhesive strength while increasing the content of biologically derived carbon, making it an adhesive tape with excellent shear holding power at high temperatures.

The alkyl (meth)acrylate containing the biologically derived carbon is not particularly limited, but has 7 to 12 carbon atoms because the glass transition temperature (Tg) of the acrylic copolymer is sufficiently lowered and the adhesive strength of the adhesive layer is higher. (meth)acrylates having an alkyl group are preferred.

As the (meth)acrylate having an alkyl group having 7 to 12 carbon atoms, for example, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, lauryl ( Meth)acrylate, etc. can be mentioned. These alkyl (meth)acrylates containing carbon derived from living organisms may be used individually, or two or more types may be used in combination. Among them, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, and lauryl (meth)acrylate are preferred because the adhesive strength of the adhesive layer is higher, and n-heptyl (meth)acrylate is preferred. ) Acrylate is more preferable.

The alkyl (meth)acrylate containing biologically derived carbon is not particularly limited as long as it contains biologically derived carbon, but is synthesized by esterification of alcohol, which is a biologically derived material, and (meth)acrylic acid, or is of biological origin. It is preferable to synthesize it through a transesterification reaction between alcohol, which is a material, and (meth)acrylic acid ester.

For example, n-heptyl alcohol, a biological material, is made inexpensively and easily by cracking it using materials collected from animals and plants (for example, ricinoleic acid derived from castor oil, etc.). It can be easily obtained. In addition, n-octyl alcohol, which is a biological material, can be obtained inexpensively and easily by using materials collected from animals and plants (for example, caprylic acid derived from palm oil, etc.) as raw materials and reducing them. In addition, lauryl alcohol, a biologically derived material, can be obtained inexpensively and easily by using materials collected from animals and plants (for example, palm oil or lauric acid derived from palm kernel oil, etc.) as a raw material and reducing it. there is.

The content of the structural unit derived from the alkyl (meth)acrylate containing the biologically derived carbon in the acrylic copolymer is not particularly limited, but is preferably greater than 50% by weight, and a more preferable lower limit is 60% by weight. %, a more preferable lower limit is 70 weight%, and a particularly preferable lower limit is 85 weight%. When the content of the structural unit is 85% by weight or more, the content of biologically derived carbon in the entire adhesive tape increases, the adhesive strength of the adhesive layer increases, and the shear holding power of the adhesive tape at high temperature becomes higher. The most preferable lower limit of the content of the structural unit is 90% by weight. The upper limit of the content of the structural unit derived from the alkyl (meth)acrylate containing carbon of biological origin is not particularly limited, but from the viewpoint of controlling the gel fraction of the adhesive layer, the preferable upper limit is 99% by weight, more preferable. The upper limit is 97% by weight.

Among them, the content of the structural unit derived from the n-heptyl (meth)acrylate in the acrylic copolymer is more than 50% by weight, more preferably 60% by weight, still more preferably 70% by weight, especially preferably. When it is 85% by weight or more, the adhesive strength of the adhesive layer becomes higher.

The content of structural units derived from the alkyl (meth)acrylate containing the biologically derived carbon in the acrylic copolymer was determined from each monomer by mass spectrometry and ¹ H-NMR measurement of the acrylic copolymer. It can be calculated from the integrated intensity ratio of the hydrogen peak.

The acrylic copolymer preferably further contains a structural unit derived from a monomer having a crosslinkable functional group.

When the acrylic copolymer contains a structural unit derived from a monomer having the crosslinkable functional group, the cohesive force of the adhesive layer increases and the adhesive force becomes higher.

The monomer having the crosslinkable functional group is not particularly limited, and examples include a monomer having a hydroxyl group, a monomer having a carboxyl group, a monomer having a glycidyl group, a monomer having an amide group, and a monomer having a nitrile group. The monomers having these crosslinkable functional groups may be used individually, or two or more types may be used in combination. Among them, a monomer having a hydroxyl group and a monomer having a carboxyl group are preferable, and a monomer having a hydroxyl group is more preferable because it is easy to control the gel fraction of the pressure-sensitive adhesive layer.

Examples of the monomer having a hydroxyl group include acrylic monomers having a hydroxyl group such as 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate.

Examples of the monomer having a carboxyl group include acrylic monomers having a carboxyl group such as (meth)acrylic acid.

Examples of the monomer having a glycidyl group include acrylic monomers having a glycidyl group such as glycidyl (meth)acrylate.

As monomers having the amide group, for example, (meth)acrylamide, dimethyl (meth)acrylamide, diethyl (meth)acrylamide, isopropyl (meth)acrylamide, t-butyl (meth)acrylamide, meth) Acrylic monomers having an amide group such as toxymethyl (meth)acrylamide and butoxymethyl (meth)acrylamide can be mentioned.

Examples of the monomer having a nitrile group include acrylic monomers having a nitrile group such as (meth)acrylonitrile.

The content of the structural unit derived from the monomer having the crosslinkable functional group in the acrylic copolymer is not particularly limited, but the preferable lower limit is 0.01% by weight and the preferable upper limit is 15% by weight. If the content of the structural unit derived from the monomer having the crosslinkable functional group is within the above range, the cohesive force of the pressure-sensitive adhesive layer increases further, and the adhesive strength further increases. The more preferable lower limit of the content of the structural unit derived from the monomer having the crosslinkable functional group is 0.1% by weight, the more preferable upper limit is 10% by weight, the more preferable lower limit is 0.5% by weight, and the more preferable upper limit is 5% by weight.

The content of the structural unit derived from the monomer having the crosslinkable functional group in the acrylic copolymer is determined by performing mass spectrometry and ¹ H-NMR measurement of the acrylic copolymer and determining the integrated intensity of the hydrogen peak derived from each monomer. It can be calculated from rain.

The acrylic copolymer has structural units derived from other monomers other than the structural units derived from the alkyl (meth)acrylate containing carbon of biological origin and the structural units derived from the monomer having the crosslinkable functional group. You can stay.

The other monomers are not particularly limited, and examples include (meth)acrylate (petroleum-derived monomer) and alkyl (meth)acrylate having an alkyl group of 7 to 12 carbon atoms that does not contain carbon of biological origin. there is.

Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and tert-butyl (meth)acrylate. Latex, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)octanol-1 and Ester of (meth)acrylic acid, ester of (meth)acrylic acid with an alcohol with 18 total carbon atoms having 1 or 2 methyl groups in the straight main chain, behenyl (meth)acrylate, arachidyl (meth)acrylate, etc. can be mentioned. These (meth)acrylic acid alkyl esters may be used individually, or two or more types may be used in combination.

Additionally, examples of the other monomers include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, and 2-phenoxy. Ethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, polypropylene glycol mono(meth)acrylate, etc. are also mentioned, and isobornyl (meth)acrylate is preferable from the viewpoint of excellent repellency resistance. . In addition, as the other monomer, for example, vinyl carboxylate such as vinyl acetate, and various monomers used in general acrylic polymers such as styrene can also be used. When the acrylic copolymer is produced by UV polymerization, polyfunctional monomers such as 1,6-hexanediol di(meth)acrylate can also be used as the other monomer. These other monomers may be used individually, or two or more types may be used together.

The content of structural units derived from the other monomers in the acrylic copolymer can be calculated from the integrated intensity ratio of the hydrogen peak derived from each monomer by performing mass spectrometry and ¹ H-NMR measurement on the acrylic copolymer. You can.

The monomer having the crosslinkable functional group and the other monomers preferably contain biologically derived carbon, but may not contain biologically derived carbon and may be made of only petroleum-derived materials. Theoretically, it is also possible to use all acrylic monomers constituting the acrylic copolymer as monomers containing carbon of biological origin. From the viewpoint of cost and productivity of the adhesive tape, a monomer containing carbon of biological origin, which is relatively inexpensive and easy to obtain, may be employed, and a monomer consisting only of petroleum-derived materials may be combined with this.

The glass transition temperature (Tg) of the acrylic copolymer is not particularly limited, but is preferably -20°C or lower. If the glass transition temperature (Tg) of the acrylic copolymer is -20°C or lower, the adhesion of the adhesive layer to the adherend improves, and the adhesive strength becomes higher. The glass transition temperature (Tg) of the acrylic copolymer is more preferably -30°C or lower, more preferably -40°C or lower, and even more preferably -50°C or lower. The lower limit of the glass transition temperature (Tg) of the acrylic copolymer is not particularly limited and is usually -90°C or higher, preferably -80°C or higher.

The glass transition temperature (Tg) of the acrylic copolymer can be determined, for example, by differential scanning calorimetry.

The weight average molecular weight (Mw) of the acrylic copolymer is not particularly limited, but the preferred lower limit is 200,000 and the preferred upper limit is 2 million. If the weight average molecular weight of the acrylic copolymer is within the above range, the adhesive strength of the adhesive layer becomes higher. The more preferable lower limit of the weight average molecular weight of the acrylic copolymer is 400,000, the more preferable upper limit is 1.8 million, the more preferable lower limit is 500,000, and the more preferable upper limit is 1.5 million.

In addition, the weight average molecular weight (Mw) is the weight average molecular weight converted to standard polystyrene as measured by GPC (Gel Permeation Chromatography). Specifically, the acrylic copolymer is diluted 50-fold with tetrahydrofuran (THF), and the resulting dilution is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare a measurement sample. Next, this measurement sample is supplied to a gel permission chromatograph (manufactured by Waters, brand name "2690 Separations Module" or its equivalent), and GPC measurement is performed under the conditions of a sample flow rate of 1 milliliter/min and a column temperature of 40°C. The polystyrene equivalent molecular weight of the acrylic copolymer is measured, and this value is taken as the weight average molecular weight of the acrylic copolymer.

The acrylic copolymer can be obtained by subjecting a monomer mixture serving as a raw material to a radical reaction in the presence of a radical polymerization initiator.

The radical reaction method is not particularly limited, and examples include living radical polymerization and free radical polymerization. According to living radical polymerization, a copolymer with a more uniform molecular weight and composition is obtained compared to free radical polymerization, and since the production of low molecular weight components, etc. can be suppressed, the cohesive force of the adhesive layer is increased, and the adhesive force is more. It gets higher.

The polymerization method is not particularly limited, and conventionally known methods can be used. Examples of polymerization methods include solution polymerization (boiling point polymerization or constant temperature polymerization), UV polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization. Among them, solution polymerization and UV polymerization are preferable because the adhesive strength of the pressure-sensitive adhesive layer is higher. In addition, solution polymerization is more preferable because it is easy to mix the tackifying resin with the obtained acrylic copolymer and the adhesive strength of the adhesive layer can be further increased.

When solution polymerization is used as the polymerization method, examples of reaction solvents include ethyl acetate, toluene, methyl ethyl ketone, dimethyl sulfoxide, ethanol, acetone, diethyl ether, etc. These reaction solvents may be used individually, or two or more types may be used in combination.

The radical polymerization initiator is not particularly limited, and examples include organic peroxides and azo compounds. As the organic peroxide, for example, 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-butylperoxy Oxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, etc. are mentioned. Examples of the azo compound include azobisisobutyronitrile, azobiscyclohexanecarbonitrile, and the like. These radical polymerization initiators may be used individually, or two or more types may be used in combination.

Moreover, in the case of living radical polymerization, examples of the radical polymerization initiator include an organic tellurium polymerization initiator. The organic tellurium polymerization initiator is not particularly limited as long as it is generally used in living radical polymerization, and examples include organic tellurium compounds and organic telluride compounds. Also, in living radical polymerization, in addition to the organic tellurium polymerization initiator, an azo compound may be used as the radical polymerization initiator for the purpose of promoting the polymerization rate.

It is preferable that the adhesive layer does not contain a surfactant.

Because the adhesive layer does not contain a surfactant, the adhesive strength of the adhesive tape, especially at high temperatures, is higher. In addition, that the adhesive layer does not contain a surfactant means that the content of the surfactant in the adhesive layer is 3% by weight or less, and is preferably 1% by weight or less.

In order for the adhesive layer not to contain a surfactant, it is preferable not to use a surfactant when obtaining the acrylic copolymer. To achieve this, for example, solution polymerization, UV polymerization, etc. may be adopted as a polymerization method for obtaining the acrylic copolymer.

The content of the surfactant can be determined, for example, by measuring the adhesive layer using a liquid chromatography mass spectrometer (e.g., NEXCERA manufactured by Shimadzu Corporation, Exactive manufactured by Thermo Fisher Scientific, etc.). More specifically, the ethyl acetate solution of the adhesive layer is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). Approximately 10 μL of the obtained filtrate was injected into a liquid chromatography mass spectrometer and analyzed under the following conditions. The content of the surfactant can be determined from the area ratio of the peak corresponding to the surfactant occupied in the adhesive layer. In addition, it is preferable to prepare a sample for each surfactant species in which the content of the surfactant in the adhesive layer is already known, prepare a calibration curve showing the relationship between the surfactant content and the peak area ratio, and analyze it.

Column manufactured by Thermo Fisher Scientific, Hypersil GOLD (2.1 × 150 ㎜)

Mobile phase acetonitrile

Column temperature 40℃

Flow rate 1.0 mL/min

Ionization method ESI

Capillary temperature 350℃

It is preferable that the adhesive layer further contains a crosslinking agent from the viewpoint of being able to appropriately control the gel fraction.

The cross-linking agent is not particularly limited, and examples include an isocyanate-based cross-linking agent, an aziridine-based cross-linking agent, an epoxy-based cross-linking agent, and a metal chelate-type cross-linking agent. Among them, an isocyanate-based crosslinking agent is preferable because the adhesive layer has excellent adhesion to the adherend.

The molecular weight of the crosslinking agent is not particularly limited, but from a manufacturing viewpoint, the molecular weight is preferably less than 2000 and more preferably 100 or more.

The content of the crosslinking agent in the adhesive layer is not particularly limited, but the preferred lower limit is 0.05 parts by weight and the preferred upper limit is 7 parts by weight based on 100 parts by weight of the acrylic copolymer. If the content of the cross-linking agent is within the above range, the gel fraction of the pressure-sensitive adhesive layer is appropriately adjusted, and the adhesive strength becomes higher. The more preferable lower limit of the content of the crosslinking agent is 0.1 parts by weight, and the more preferable upper limit is 5 parts by weight.

In addition, the content of the cross-linking agent represents the amount of solid content of the cross-linking agent.

It is preferable that the adhesive layer further contains a tackifying resin. As a result, the adhesive strength of the adhesive layer becomes higher, and the shear holding power of the adhesive tape at high temperatures becomes higher.

Specific examples of the tackifying resin include rosin ester-based tackifying resin, terpene-based tackifying resin, coumarone-indene-based tackifying resin, alicyclic saturated hydrocarbon-based tackifying resin, and C5-based petroleum tackifying resin. Examples include C9-based petroleum tackifier resin and C5-C9 copolymer petroleum tackifier resin. These tackifying resins may be used individually, or two or more types may be used in combination. Among them, at least one selected from the group consisting of rosin ester-based tackifying resins and terpene-based tackifying resins is preferable.

Examples of the rosin ester-based tackifying resin include polymerized rosin ester-based resin and hydrogenated rosin ester-based resin. Examples of the terpene-based tackifying resin include terpene-based resins and terpene-phenol-based resins.

It is preferable that the rosin ester-based tackifying resin and the terpene-based tackifying resin are of biological origin. Examples of biologically derived rosin ester-based tackifying resins include rosin ester-based tackifying resins derived from natural resins such as pine resin. Examples of biologically derived terpene-based tackifying resins include terpene-based tackifying resins derived from plant essential oils, etc.

The content of the tackifying resin in the adhesive layer is not particularly limited, but the preferable lower limit is 10 parts by weight and the preferable upper limit is 60 parts by weight relative to 100 parts by weight of the acrylic copolymer. When the content of the tackifying resin is within the above range, the adhesive strength of the adhesive layer becomes higher, and the shear holding power of the adhesive tape at high temperature becomes higher. The more preferable lower limit of the content of the tackifying resin is 15 parts by weight, the more preferable upper limit is 50 parts by weight, and the more preferable upper limit is 35 parts by weight.

The adhesive layer may contain additives such as a silane coupling agent, plasticizer, softener, filler, pigment, dye, etc. as needed.

The adhesive layer has a total content of a compound having a structure represented by the following general formula (A) and a compound having a structure shown by the following general formula (B) of 2% by weight or less.

[Formula 6]

In general formulas (A) and (B), R ¹ and R ² represent an alkyl group having 4 to 12 carbon atoms.

The adhesive layer has a total content of 2% by weight of a compound having a structure represented by the general formula (A), a compound having a structure represented by the general formula (B), and a compound having a structure represented by the following general formula (C). It is preferable that it is below.

[Formula 7]

In general formula (C), R ¹ and R ² represent an alkyl group having 4 to 12 carbon atoms.

The compound having the structure represented by the general formula (A) and the compound having the structure represented by the general formula (B) are compounds corresponding to impurities of the alkyl (meth)acrylate containing carbon of biological origin. Therefore, the alkyl groups (R ¹ and R ² ) of the compound having the structure represented by the general formula (A) and the compound having the structure represented by the general formula (B) are alkyl (meth) containing carbon derived from the above-described organism. It is preferable that it is the same as the alkyl group of the acrylate. However, the alkyl groups (R ¹ and R ² ) may be different from the alkyl groups of the alkyl (meth)acrylate containing carbon derived from the organism.

The compound having the structure represented by the general formula (C) is a compound corresponding to an impurity of the alkyl (meth)acrylate containing carbon derived from the biological organism. Therefore, it is preferable that the alkyl groups (R ¹ and R ² ) of the compound having the structure represented by the general formula (C) are the same as the alkyl groups of the alkyl (meth)acrylate containing carbon of biological origin. However, the alkyl groups (R ¹ and R ² ) may be different from the alkyl groups of the alkyl (meth)acrylate containing carbon derived from the organism.

The alkyl group (R ¹ and R ² ) is not particularly limited as long as it is an alkyl group with 4 to 12 carbon atoms, but is preferably an alkyl group with 7 to 12 carbon atoms. Specific examples of the alkyl groups (R ^{1 and} R ² ) include n-heptyl group, n-octyl group, n-decyl group, and lauryl group. In the general formula (A) and (B), R ¹ and R ² may be the same or different, but are preferably the same. In the general formulas (A) to (C), R ¹ and R ² may be the same or different, but are preferably the same.

In addition, the compound having the structure represented by the general formula (A) may be composed of only one compound having the structure represented by the general formula (A), or a plurality of compounds having the structure represented by the general formula (A). These may be used together. Similarly, the compound having the structure represented by the general formula (B) may be composed of only one compound having the structure represented by the general formula (B), or may have a plurality of structures represented by the general formula (B). The compounds may be used together. Similarly, the compound having the structure represented by the general formula (C) may be composed of only one compound having the structure represented by the general formula (C), or may have a plurality of structures represented by the general formula (C). The compounds may be used together.

More specifically, the compound having the structure represented by the general formula (A) is preferably, for example, a compound having the structure represented by the following formula (a1).

[Formula 8]

More specifically, the compound having the structure represented by the general formula (B) is preferably, for example, a compound having the structure represented by the following formula (b1).

[Formula 9]

More specifically, the compound having the structure represented by the general formula (C) is preferably, for example, a compound having the structure represented by the following formula (c1).

[Formula 10]

If the total content of the compound having the structure represented by the general formula (A) and the compound having the structure represented by the general formula (B) is 2% by weight or less, the decrease in adhesive strength due to bleed out of these compounds, etc. can be suppressed. This increases the shear holding power of the adhesive tape at high temperatures. The total content of the compound having the structure represented by the general formula (A) and the compound having the structure represented by the general formula (B) is preferably 1% by weight or less, and more preferably 0.1% by weight or less.

The lower limit of the total content of the compound having the structure represented by the general formula (A) and the compound having the structure represented by the general formula (B) is not particularly limited, and the closer to 0% by weight is preferable, and may be 0% by weight. . That is, the adhesive layer does not need to contain a compound having a structure represented by the general formula (A) and a compound having a structure represented by the general formula (B).

It is preferable that the total content of the compound having the structure represented by the formula (A), the compound having the structure represented by the formula (B), and the compound having the structure represented by the formula (C) is 2% by weight or less. If it is below the above upper limit, the decline in adhesive strength resulting from bleed-out of these compounds can be more effectively suppressed, and the shear holding power of the adhesive tape at high temperature is increased. It is more preferable that the total content of the compound having the structure represented by the formula (A), the compound having the structure represented by the formula (B), and the compound having the structure represented by the formula (C) is 1% by weight or less, , it is more preferable that it is 0.1% by weight or less.

The lower limit of the total content of the compound having the structure represented by the formula (A), the compound having the structure represented by the formula (B), and the compound having the structure represented by the formula (C) is not particularly limited, and is 0. The closer it is to weight%, the more preferable it is, and 0 weight% may be sufficient. That is, the pressure-sensitive adhesive layer does not need to contain a compound having a structure represented by the general formula (A), a compound having a structure represented by the general formula (B), and a compound having a structure represented by the general formula (C). do.

The total content of a compound having a structure represented by the formula (A) and a compound having a structure represented by the formula (B), or a compound having a structure represented by the formula (A), the formula (B) The total content of the compound having the structure represented by and the compound having the structure represented by the general formula (C) is calculated as follows.

Using toluene, the sol powder of the adhesive layer in the adhesive tape is extracted and dried. The obtained sol powder was dissolved in deuterated chloroform, and ¹ H-NMR measurement and ¹³ C-NMR measurement were performed to determine the content of the compound having the structure represented by the general formula (A) and the compound having the structure represented by the general formula (B). Calculate each. By adding these together, the total content can be calculated.

Methods for adjusting the total content of the compound having the structure represented by the general formula (A) and the compound having the structure represented by the general formula (B) to the above range include, for example, the following method. That is, when using an alkyl (meth)acrylate containing carbon derived from a specific organism as the acrylic monomer constituting the acrylic copolymer, the alkyl (meth)acrylate containing carbon derived from the specific organism is purified to remove impurities. This is a method of reducing the content of the above compound contained as. In addition, the content of the above-mentioned compounds contained as impurities may be reduced by purifying the obtained acrylic copolymer, and by adjusting the heating and drying conditions when producing the adhesive tape (for example, when forming the adhesive layer), The content of the compound may be reduced. Among these, it is preferable to purify alkyl (meth)acrylates containing carbon derived from specific organisms.

The purification method of the alkyl (meth)acrylate and acrylic copolymer is not particularly limited, and conventionally known methods can be used, for example, distillation, reprecipitation, preparative liquid chromatography, column chromatography, etc. there is.

Distillation, preparative liquid chromatography, and column chromatography are preferred methods for purifying alkyl (meth)acrylates, and reprecipitation, preparative liquid chromatography, and column chromatography are preferred methods for purifying acrylic copolymers.

The content of the compound having the structure represented by the general formula (A) in the adhesive layer is not particularly limited as long as the total content can be adjusted to the above range, but is preferably less than 1% by weight. If the content of the compound having the structure represented by the general formula (A) is less than 1% by weight, the shear holding power of the adhesive tape at high temperature becomes higher. The lower limit of the content of the compound having the structure represented by the general formula (A) is not particularly limited, and the closer to 0% by weight is preferable, and 0% by weight may be sufficient.

The content of the compound having the structure represented by the general formula (B) in the adhesive layer is not particularly limited as long as the total content can be adjusted to the above range, but is preferably less than 1% by weight and less than 0.01% by weight. It is more desirable. If the content of the compound having the structure represented by the general formula (B) is within the above range, the shear holding power of the adhesive tape at high temperature becomes higher. The lower limit of the content of the compound having the structure represented by the general formula (B) is not particularly limited, and the closer to 0% by weight is preferable, and 0% by weight may be sufficient.

The gel fraction of the pressure-sensitive adhesive layer is not particularly limited, but the preferable lower limit is 10% by weight and the preferable upper limit is 70% by weight. When the gel fraction of the pressure-sensitive adhesive layer is within the above range, the adhesive strength of the pressure-sensitive adhesive layer becomes higher. The more preferable lower limit of the gel fraction of the pressure-sensitive adhesive layer is 20% by weight, and the more preferable upper limit is 50% by weight.

The gel fraction of the adhesive layer is measured as follows.

First, the adhesive tape was cut into a flat rectangular shape of 20 mm . The weight of the test piece after drying is measured, and the gel fraction is calculated using the following formula (1). In addition, the release film for protecting the adhesive layer is not laminated on the test piece.

Gel fraction (% by weight) = 100 × (W ₂ - W ₀ )/(W ₁ - W ₀ ) (1)

(W ₀ : Weight of substrate, W ₁ : Weight of test piece before immersion, W ₂ : Weight of test piece after immersion and drying)

The method of adjusting the gel fraction of the adhesive layer to the above range is not particularly limited, but a method of adjusting the composition and weight average molecular weight of the acrylic copolymer and the type and amount of the crosslinking agent as described above is preferred. .

The adhesive layer preferably has a content of biologically derived carbon of 10% by weight or more. The standard for a “bio-based product” is that the carbon content of biological origin is 10% by weight or more.

If the content of biologically derived carbon is 10% by weight or more, it is preferable from the viewpoint of saving petroleum resources and reducing carbon dioxide emissions. The more preferable lower limit of the biologically derived carbon content is 30% by weight, and the more preferable lower limit is 60% by weight. The upper limit of the carbon content of biological origin is not particularly limited, and may be 100% by weight.

In addition, while biologically derived carbon contains a certain percentage of radioactive isotope (C-14), petroleum derived carbon contains almost no C-14. Therefore, the content of biologically derived carbon can be calculated by measuring the concentration of C-14 contained in the adhesive layer. Specifically, it can be measured according to ASTM D6866-20, a standard used in many bioplastics industries.

The thickness of the adhesive layer is not particularly limited, but the preferred lower limit is 3 μm and the preferred upper limit is 300 μm. When the thickness of the adhesive layer is within the above range, the adhesive strength of the adhesive layer becomes higher. A more preferable lower limit of the thickness of the adhesive layer is 5 μm, and a more preferable lower limit is 10 μm. A more preferable upper limit of the thickness of the adhesive layer is 200 μm, and a more preferable upper limit is 100 μm.

The adhesive tape of the present invention may be a non-support tape having no base material, a single-sided adhesive tape having an adhesive layer on one side of the base material, or a double-sided adhesive tape having an adhesive layer on both sides of the base material.

The substrate is not particularly limited, and conventionally known substrates can be used. However, in order to increase the content of biologically derived carbon in the adhesive tape as a whole, it is preferable to use a biologically derived substrate.

Examples of the biologically derived base material include plant-derived polyethylene terephthalate (PET), polyethylene terephthalate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), and polybutylene terephthalate ( Films and non-woven fabrics made of polyester (PES) such as PBT) and polybutylene succinate (PBS) can be mentioned. In addition, films and non-woven fabrics made of plant-derived polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetylcellulose (TAC), cellulose, polyamide (PA), etc. are also included.

From the viewpoint of substrate strength, the substrate is preferably a film made of PES or a film made of PA. Additionally, from the viewpoint of heat resistance and oil resistance, a film made of PA is preferable.

Examples of the components of the film made of PA include nylon 11, nylon 1010, nylon 610, nylon 510, nylon 410, etc., which are made from castor oil, and nylon 56, which is made from cellulose.

Additionally, from the viewpoint of reducing the environmental load by reducing the use of new petroleum resources and suppressing carbon dioxide emissions, a base material using renewable resources may be used. As a method of recycling resources, for example, waste from packaging containers, home appliances, automobiles, construction materials, food, etc. or waste generated during the manufacturing process is recovered, and the removed materials are cleaned, decontaminated, or heated. A method of using it again as a raw material through decomposition by fermentation is an example. Examples of substrates using recycled resources include films and non-woven fabrics made of PET, PBT, PE, PP, PA, etc., which are made by re-resinizing recovered plastics as raw materials. In addition, the recovered waste may be burned and used as heat energy related to the production of base material or its raw materials, or the fats and oils contained in the recovered waste may be mixed with petroleum, and the classified and refined product may be used as a raw material.

The base material may be a foam base material from the viewpoint of improving compression properties.

As the foam base material, a foam base material made of PE, PP and/or PU is preferable, and a foam base material made of PE is more preferable from the viewpoint of achieving a high degree of both flexibility and strength. Examples of foam-based components made of PE include PE made from sugarcane as a raw material.

The manufacturing method of the foam base material is not particularly limited, but for example, prepare a foamable resin composition containing a PE resin containing PE made from sugar cane as a raw material and a foaming agent, and use an extruder to form the foamable resin composition into a sheet. A preferred method is to foam a foaming agent during extrusion processing and crosslink the obtained polyolefin foam as necessary.

The thickness of the foam base material is not particularly limited, but the preferred lower limit is 50 µm and the preferred upper limit is 5000 µm. If the thickness of the foam base material is within this range, it can exhibit high impact resistance and high flexibility to adhere and bond along the shape of the adherend. A more preferable upper limit of the thickness of the foam substrate is 1000 μm, and a more preferable upper limit is 300 μm.

The adhesive tape of the present invention has a preferred lower limit of the total thickness of the adhesive tape (sum of the thickness of the base material and the adhesive layer) of 3 µm and a preferred upper limit of 6000 µm. If the total thickness of the adhesive tape is within the above range, the adhesive strength becomes higher. A more preferable upper limit of the total thickness of the adhesive tape is 1200 μm, and a more preferable upper limit is 500 μm.

The manufacturing method of the adhesive tape of the present invention is not particularly limited, and it can be manufactured by a conventionally known manufacturing method. For example, in the case of double-sided adhesive tape, the following methods can be used.

First, a solution of adhesive A is prepared by adding a solvent to the acrylic copolymer, a radical scavenging agent, and, if necessary, a crosslinking agent or tackifying resin. This solution of adhesive A is applied to the surface of the substrate, and the solvent in the solution is completely removed. Dry and remove to form adhesive layer A. Next, the release film is superimposed on the formed adhesive layer A with its release-treated surface facing the adhesive layer A.

Next, a release film separate from the above-described release film is prepared, and a solution of adhesive B prepared in the same manner as above is applied to the release-treated surface of this release film, and the solvent in the solution is completely dried and removed to form a release film. A laminated film with adhesive layer B formed on the surface is manufactured. The obtained laminated film is overlapped on the back side of the base material on which the pressure-sensitive adhesive layer A is formed, with the pressure-sensitive adhesive layer B facing the back side of the base material, to produce a laminated body. Then, by pressing the laminate with a rubber roller or the like, a double-sided adhesive tape having an adhesive layer on both sides of the base material and the surface of the adhesive layer covered with a release film can be obtained.

Additionally, two sets of laminated films were manufactured in the same manner, and these laminated films were overlapped on each of both sides of the base material with the adhesive layer of the laminated film facing the base material to produce a laminated body, and this laminated body was placed on a rubber roller. By pressing with, for example, a double-sided adhesive tape having an adhesive layer on both sides of the base material and the surface of the adhesive layer covered with a release film may be obtained.

The use of the adhesive tape of the present invention is not particularly limited, but it is preferably used for fixing electronic device parts or vehicle parts because it has a high content of biologically derived carbon and is excellent in shear holding power at high temperatures. Specifically, the adhesive tape of the present invention can be suitably used for adhesive fixation of electronic device components in large portable electronic devices, adhesive fixation of vehicle components (for example, vehicle panels), etc.

According to the present invention, it is possible to provide an adhesive tape that has a high content of biologically derived carbon and is excellent in shear holding power at high temperatures.

The embodiments of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

<Lauryl acrylate containing carbon of biological origin>

Lauryl acrylate was prepared by esterifying lauryl alcohol (manufactured by Kao Corporation) containing biologically derived carbon and acrylic acid (manufactured by Nippon Catalyst Corporation).

<n-octylacrylate containing carbon of biological origin>

n-octylacrylate was prepared by esterifying n-octyl alcohol (manufactured by Kao Corporation) containing biologically derived carbon and acrylic acid (manufactured by Nippon Catalyst Corporation).

<n-heptyl acrylate containing carbon of biological origin>

Ricinoleic acid derived from castor oil was cracked to obtain a mixture containing undecylenic acid and heptyl alcohol. Next, it was separated from undecylenic acid by distillation to obtain n-heptyl alcohol containing carbon of biological origin. n-heptyl acrylate was prepared by esterifying n-heptyl alcohol containing biologically derived carbon and acrylic acid (manufactured by Nippon Catalysis Co., Ltd.).

Additionally, at this time, the content of impurities was reduced by distilling n-heptyl acrylate.

＜Other acrylic monomers＞

2-Ethylhexyl acrylate (manufactured by Mitsubishi Chemical)

Acrylic acid (manufactured by Nippon Catalyst Co., Ltd.)

・2-Hydroxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.)

＜Cross-linking agent＞

·Isocyanate-based crosslinking agent (Tosoh Corporation, Coronate L-45)

＜Tackifying resin＞

·Terpene phenol (Terpene phenol G-150, manufactured by Yasuhara Chemical Co., Ltd.)

(Example 1)

(1) Preparation of acrylic copolymer (solution polymerization)

In the reaction vessel, ethyl acetate was added as a polymerization solvent, and after bubbling with nitrogen, the reaction vessel was heated while nitrogen was introduced to initiate reflux. Subsequently, as a radical polymerization initiator, a radical polymerization initiator solution containing 0.1 part by weight of azobisisobutyronitrile diluted 10 times with ethyl acetate was added into the reaction vessel, and a predetermined amount of n-heptyl acrylate, acrylic acid, and 2-hydroxylethyl Acrylate was added dropwise over 2 hours. After completion of the dropwise addition, a radical polymerization initiator solution containing 0.1 part by weight of azobisisobutyronitrile as a radical polymerization initiator diluted 10 times with ethyl acetate was added back into the reaction vessel, and a polymerization reaction was performed for 4 hours to obtain a solution containing an acrylic copolymer. .

Mass spectrometry and ¹ H-NMR measurement were performed on the obtained acrylic copolymer, and the content of structural units derived from each monomer was calculated from the integrated intensity ratio of the hydrogen peak derived from each monomer.

The obtained acrylic copolymer was diluted 50-fold with tetrahydrofuran (THF), and the resulting dilution 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 permission chromatograph (2690 Separations Module, manufactured by Waters), GPC measurement was performed under the conditions of a sample flow rate of 1 mL/min and a column temperature of 40°C, and the polystyrene equivalent molecular weight of the acrylic copolymer was measured. , the weight average molecular weight was obtained.

Additionally, differential scanning calorimetry was performed on the obtained acrylic copolymer using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Co., Ltd.) to determine the glass transition temperature (Tg). Specifically, about 2 mg of the acrylic copolymer was weighed into an aluminum pan, and the aluminum pan was measured under a nitrogen atmosphere at a temperature increase of 10°C/min. The obtained chart was read to determine the glass transition point.

(2) Manufacturing of adhesive tape

An adhesive solution was prepared by adding an isocyanate-based crosslinking agent (Coronate L-45, manufactured by Tosoh Corporation) to a solid content of 0.5 parts by weight based on 100 parts by weight of the acrylic copolymer to the obtained acrylic copolymer-containing solution. This adhesive solution was applied to the release-treated surface of a PET film with a thickness of 75 μm so that the thickness of the adhesive layer after drying was 50 μm, and then dried at 110°C for 5 minutes. This adhesive layer was overlaid on the release-treated surface of a PET film with a thickness of 75 μm and cured at 40°C for 48 hours to obtain an adhesive tape (non-support type).

(3) Total content of the compound having the structure represented by general formula (A) and the compound having the structure represented by general formula (B)

Using toluene, the sol powder of the adhesive layer in the adhesive tape was extracted and dried. The obtained sol powder was dissolved in deuterated chloroform, and ¹ H-NMR measurement and ¹³ C-NMR measurement were performed to determine the total content of the compound having the structure represented by general formula (A) and the compound having the structure represented by general formula (B). Calculated.

In addition, in Tables 1 and 2, compound a1 is a compound having a structure represented by general formula (A) (R ¹ and R ² are n-heptyl groups), and compound a2 has a structure represented by general formula (A). Compound a3 is a compound (R ¹ and R ² are n-octyl groups), and compound a3 is a compound (R ¹ and R ² are lauryl groups) having a structure represented by general formula (A). Compound b1 is a compound having a structure represented by general formula (B) (R ¹ and R ² are n-heptyl groups), and compound b2 is a compound having a structure represented by general formula (B) (R ¹ and R ² is an n-octyl group), and compound b3 is a compound (R ¹ and R ² are lauryl groups) having a structure represented by general formula (B).

(4) Total content of the compound having the structure represented by general formula (A), the compound having the structure represented by general formula (B), and the compound having the structure represented by general formula (C)

Using toluene, the sol powder of the adhesive layer in the adhesive tape was extracted and dried. The obtained sol powder was dissolved in deuterated chloroform, and ¹ H-NMR measurement and ¹³ C-NMR measurement were performed to obtain a compound having a structure represented by general formula (A), a compound having a structure represented by general formula (B), and general formula ( C) The total content was calculated.

In addition, in Tables 1 and 2, compound c1 is a compound having a structure represented by general formula (C) (R ¹ and R ² are n-heptyl groups), and compound c2 has a structure represented by general formula (C). Compound c3 is a compound (R ¹ and R ² are n-octyl groups), and compound c3 is a compound (R ¹ and R ² are lauryl groups) having a structure represented by general formula (C).

(5) Measurement of gel fraction

The release film on one side of the adhesive tape was peeled off, bonded to a 23-μm-thick PET film (FE2002, manufactured by Futamura Chemical Co., Ltd.), and cut into a flat rectangular shape of 20 mm x 40 mm. Additionally, the release film on the other side of the adhesive tape was peeled off, a test piece was prepared, and the weight was measured. The test piece was immersed in ethyl acetate at 23°C for 24 hours, then taken out from the ethyl acetate and dried under conditions of 110°C for 1 hour. The weight of the test piece after drying was measured, and the gel fraction was calculated using (1) below.

Gel fraction (% by weight) = 100 × (W ₂ - W ₀ )/(W ₁ - W ₀ ) (1)

(W ₀ : Weight of the substrate (PET film), W ₁ : Weight of the test piece before immersion, W ₂ : Weight of the test piece after immersion and drying)

(Examples 2 to 15, Comparative Examples 1 to 4)

The type and amount of acrylic monomer constituting the acrylic copolymer, the weight average molecular weight of the acrylic copolymer, the amount of tackifying resin, and the amount of crosslinking agent are changed as shown in Tables 1 to 2, and the adhesive tape is manufactured. An adhesive tape was obtained in the same manner as in Example 1 except that the method was changed as shown below.

In Examples 3 to 10 and 15, the alkyl (meth)acrylate containing biologically derived carbon was not purified by distillation to reduce the content of impurities, but instead, an ethyl acetate solution of the obtained acrylic copolymer was used. Reprecipitation was performed by dropping it into methanol. After that, an adhesive tape was manufactured using the reprecipitated acrylic copolymer.

In Example 11, the adhesive solution was applied to the release-treated surface of the PET film, and then dried at 110°C for 20 minutes instead of dried at 110°C for 5 minutes.

- In Example 12, after applying the adhesive solution to the release-treated surface of the PET film, it was dried at 110°C for 10 minutes instead of drying at 110°C for 5 minutes.

In Example 13, n-heptyl acrylate was not distilled after synthesis, but a part of the fraction containing compound a1 was removed using a preparative HPLC (liquid chromatography) device (Inertsil SIL-150A, manufactured by GL Science). used.

In Example 14, n-heptyl acrylate was not distilled after synthesis, but a part of the fraction containing compound b1 was removed using a preparative HPLC (liquid chromatography) device (Inertsil SIL-150A, manufactured by GL Science). used.

In Comparative Examples 1 to 2, the content of impurities in alkyl (meth)acrylate containing biologically derived carbon was not reduced by purification using distillation or preparative HPLC equipment, nor was the obtained acrylic copolymer reprecipitated. .

In Comparative Example 3, part of the fraction containing compound a3 was removed and used.

In Comparative Example 4, part of the fraction containing compound b1 was removed and used.

＜Evaluation＞

The adhesive tapes obtained in Examples and Comparative Examples were evaluated by the following method. The results are shown in Tables 1 and 2.

(1) Shear holding capacity at high temperature (85℃)

The adhesive tape was cut to 25 mm in width and 100 mm in length. In accordance with JIS Z-1528, one side of the adhesive tape 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. At this time, the adhesive tape was bonded with the adhesive tape being shifted in the longitudinal direction so that the adhesive tape had an adhesive length of 25 mm and a 75 mm long portion of the adhesive tape protruded from the end of the SUS304 plate. After backing the other side of the adhesive tape with PET film, it was pressed together with a 2 kg rubber roller in one reciprocation, and an adhesive test piece was produced.

The adhesion test piece was left in an atmosphere of 23°C and 50% humidity for 20 minutes. In an environment of 85°C, a weight of 1 kg was attached to the portion where the adhesive tape protruded so that a load was applied in the shear direction to the obtained adhesive test piece. The time from when the load was applied until the adhesive tape peeled off and fell was marked as ◎, when it was 1 hour or more and less than 24 hours, it was marked as ○, and when it took less than 1 hour, it was marked as ×.

(2) Carbon content of biological origin

For the adhesive tape, the content of biologically derived carbon was measured according to ASTM D6866-20.

According to the present invention, it is possible to provide an adhesive tape that has a high content of biologically derived carbon and is excellent in shear holding power at high temperatures.

Claims (13)

An adhesive tape having an adhesive layer containing an acrylic copolymer,
The acrylic copolymer contains structural units derived from alkyl (meth)acrylate containing carbon of biological origin,
An adhesive tape characterized in that the adhesive layer has a total content of a compound having a structure represented by the following general formula (A) and a compound having a structure represented by the following general formula (B) of 2% by weight or less.

In general formulas (A) and (B), R ¹ and R ² represent an alkyl group having 4 to 12 carbon atoms. According to claim 1,
The adhesive layer has a total content of 2% by weight of a compound having a structure represented by the general formula (A), a compound having a structure represented by the general formula (B), and a compound having a structure represented by the following general formula (C). An adhesive tape characterized in that it is % or less.

In general formula (C), R ¹ and R ² represent an alkyl group having 4 to 12 carbon atoms. The method of claim 1 or 2,
An adhesive tape, characterized in that the adhesive layer contains less than 1% by weight of a compound having a structure represented by the general formula (A). The method of claim 1, 2 or 3,
An adhesive tape characterized in that the compound having a structure represented by the general formula (A) is a compound having a structure represented by the following formula (a1).

The method of claim 1, 2, 3 or 4,
An adhesive tape, characterized in that the adhesive layer contains less than 1% by weight of a compound having a structure represented by the general formula (B). The method of claim 2, 3, 4 or 5,
An adhesive tape, characterized in that the adhesive layer contains less than 1% by weight of a compound having a structure represented by the general formula (C). The method of claim 1, 2, 3, 4, 5 or 6,
An adhesive tape characterized in that the compound having a structure represented by the general formula (B) is a compound having a structure represented by the following formula (b1).

The method of claim 2, 3, 4, 5, 6 or 7,
An adhesive tape characterized in that the compound having a structure represented by the general formula (C) is a compound having a structure represented by the following formula (c1).

The method of claim 1, 2, 3, 4, 5, 6, 7 or 8,
An adhesive tape characterized in that the alkyl (meth)acrylate containing biologically derived carbon contains n-heptyl (meth)acrylate. The method of claim 1, 2, 3, 4, 5, 6, 7, 8 or 9,
An adhesive tape characterized in that the acrylic copolymer has a content of structural units derived from alkyl (meth)acrylate containing carbon of biological origin in an amount of 85% by weight or more. The method of claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10,
An adhesive tape characterized in that the adhesive layer further contains a tackifying resin. The method of claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11,
An adhesive tape, wherein the adhesive layer has a content of biologically derived carbon of 10% by weight or more. The method of claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12,
An adhesive tape characterized by being used for fixing electronic device parts or vehicle parts.