TW202309228A - Adhesive tape - Google Patents

Abstract

The present invention provides an adhesive tape that has a high content of organism-derived carbon, that can exhibit excellent adhesion, and that has reduced odor generation. The present invention is an adhesive tape that has an adhesive layer containing an acrylic copolymer, wherein: the acrylic copolymer contains a structural unit derived from an alkyl (meth)acrylate containing organism-derived carbon; and, in the acrylic copolymer, the content of a structural unit derived from a (meth)acrylate that has a branched alkyl group having 8 or less carbon atoms is less than 0.5 weight%.

Description

Adhesive tape

The invention relates to an adhesive tape.

Conventionally, adhesive tapes having an adhesive layer containing an adhesive have been widely used when fixing components to electronic components, vehicles, houses, and building materials (for example, Patent Documents 1 to 3). Specifically, for example, in order to attach a cover for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to attach a touch panel module to a display panel module, an adhesive is used. bring. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2015-052050 [Patent Document 2] Japanese Patent Laid-Open No. 2015-021067 [Patent Document 3] Japanese Patent Laid-Open No. 2015-120876

[Problem to be Solved by the Invention]

In recent years, depletion of petroleum resources and emission of carbon dioxide caused by combustion of products derived from petroleum have been regarded as problems. Therefore, centering on the medical field and the packaging material field, attempts are being made to save petroleum resources by using bio-derived materials instead of petroleum-derived materials. Such attempts have been extended to various fields, and even in the field of adhesives and adhesive tapes, the use of bio-derived materials has begun to be required.

The object of the present invention is to provide an adhesive tape, which has a high content of bio-derived carbon, can exert excellent adhesive force, and can reduce the generation of odor. [Technical means to solve the problem]

The present invention 1 is an adhesive tape having an adhesive layer containing an acrylic copolymer, wherein the acrylic copolymer contains a constituent unit derived from an alkyl (meth)acrylate containing Bio-carbon, in the above-mentioned acrylic copolymer, the content of the structural unit derived from (meth)acrylate having a branched chain alkyl group having 8 or less carbon atoms is less than 0.5% by weight. The present invention 2 is the adhesive tape according to the present invention 1, wherein the above-mentioned alkyl (meth)acrylate containing bio-derived carbon contains n-heptyl (meth)acrylate. The present invention 3 is the adhesive tape according to the present invention 1 or 2, wherein the (meth)acrylate having a branched chain alkyl group having 8 or less carbon atoms contains 1-methylheptyl (meth)acrylate. This invention 4 is the adhesive tape of this invention 1, 2, or 3 whose content of the structural unit derived from the said n-heptyl (meth)acrylate in the said acrylic copolymer is 85 weight% or more. The present invention 5 is the adhesive tape according to the present invention 1, 2, 3 or 4, wherein the adhesive layer further contains an adhesive resin. This invention 6 is the adhesive tape of this invention 1, 2, 3, 4, or 5 whose total amount of the volatile organic compound calculated by toluene of the said adhesive agent layer is less than 1000 ppm. Invention 7 is the adhesive tape according to Invention 1, 2, 3, 4, 5 or 6, wherein the content of bio-derived carbon in the adhesive layer is 10% by weight or more. The present invention 8 is the adhesive tape according to the present invention 1, 2, 3, 4, 5, 6 or 7, which is used for fixing electronic equipment parts or vehicle parts. In addition, (meth)acrylate in this specification means acrylate or methacrylate, and (meth)acryl means acryl or methacryl. The acrylic acid copolymer may also be a methacrylic acid copolymer. Hereinafter, the present invention will be described in detail.

The inventors of the present invention conducted research on using an alkyl (meth)acrylate containing bio-derived carbon as the constituent acrylic copolymer in an adhesive tape having an adhesive layer containing an acrylic copolymer. Acrylic monomers. However, when an alkyl (meth)acrylate containing bio-derived carbon is used, although the adhesive tape exhibits excellent adhesive force, a new problem of "odor generation" arises.

The inventors of the present invention conducted research on the cause of the odor, and found that the alkyl (meth)acrylate containing biologically derived carbon contains impurities, especially in the form of impurities with branched chains. Alkyl (meth)acrylates. Alkyl (meth)acrylates containing bio-derived carbon are mainly obtained by esterification of (meth)acrylic acid with alcohols having bio-derived alkyl groups, or (meth)acrylates such as (meth)acrylic acid ) Methyl acrylate) is obtained by the transesterification reaction of an alcohol having a biologically derived alkyl group. Alcohols having a biologically derived alkyl group can be obtained, for example, by cleavage or reduction of biologically derived fatty acids or their esters. These alcohols contain alcohols having branched alkyl groups in the form of impurities. Therefore, bio-derived carbon-containing alkyl (meth)acrylates obtained from these alcohols sometimes also contain (meth)acrylates having branched or unsaturated alkyl groups as impurities. Such (meth)acrylates with branched alkyl groups are copolymerized into acrylic acid copolymers. In the case of copolymerization of (meth)acrylate having a branched alkyl group, since the branched alkyl group is easily broken by hydrolysis or the like over time, it has been found that: stench. Among them, (meth)acrylates having a branched chain alkyl group having 8 or less carbon atoms were found to easily cause odor. The inventors of the present invention have found that by suppressing the content of constituent units derived from (meth)acrylic acid esters having a branched chain alkyl group having 8 or less carbon atoms in an acrylic copolymer to a certain value or less, biologically derived The present invention has been accomplished by providing an adhesive tape that has a high carbon content, can reduce the generation of odor and exhibit excellent adhesive force at the same time.

The adhesive tape of the present invention has an adhesive layer containing an acrylic copolymer. The above-mentioned acrylic copolymer contains a structural unit derived from an alkyl (meth)acrylate containing bio-derived carbon. Thereby, the adhesive tape of this invention becomes high biogenic carbon content rate, and can exhibit the outstanding adhesive force.

The above-mentioned alkyl (meth)acrylate containing bio-derived carbon is not particularly limited, but the glass transition temperature (Tg) of the above-mentioned acrylic copolymer is sufficiently lowered, and the adhesiveness of the above-mentioned adhesive layer to the adherend In terms of improvement, it is preferably a (meth)acrylate having an alkyl group having 7 to 12 carbon atoms. More preferably, it is a (meth)acrylate which further has a linear alkyl group with 7-12 carbon atoms. Examples of (meth)acrylates having a linear alkyl group having 7 to 12 carbon atoms include n-heptyl (meth)acrylate, n-octyl (meth)acrylate, and n-decyl (meth)acrylate. esters, lauryl (meth)acrylate, etc. These (meth)acrylates which have a straight-chain alkyl group having 7 to 12 carbon atoms may be used alone or in combination of two or more. Among them, n-heptyl (meth)acrylate and n-octyl (meth)acrylate are preferred, and (meth) n-heptyl acrylate.

The above-mentioned alkyl (meth)acrylate containing bio-derived carbon is not particularly limited as long as it contains bio-derived carbon, but it is preferably obtained by combining alcohol, which is a bio-derived material, with (meth)acrylic acid. synthesized by esterification. For example, n-heptanol, which is a biologically derived material, can be obtained cheaply and easily by cracking a material such as collected automata (for example, ricinoleic acid derived from castor oil, etc.) as a raw material. In addition, n-octanol, which is a biologically derived material, can be obtained cheaply and easily by reducing it from materials such as collected autobots (for example, caprylic acid derived from coconut oil, etc.) as raw materials. In addition, lauryl alcohol, which is a biologically derived material, can be reduced cheaply and easily by using materials such as collected automata (for example, lauric acid derived from palm oil or palm kernel oil, etc.) as raw materials and reducing them. get.

In the above-mentioned acrylic copolymer, the content of the constituent units derived from the above-mentioned alkyl (meth)acrylate containing bio-derived carbon is not particularly limited, but it is preferably more than 50% by weight, more preferably the lower limit is 60% by weight, and further A preferable lower limit is 70% by weight, and a more preferable lower limit is 85% by weight. When the content of the above-mentioned structural units is 85% by weight or more, the bio-derived carbon content of the entire adhesive tape increases, and the adhesive force of the above-mentioned adhesive layer increases. The optimum lower limit of the content of the above structural units is 90% by weight. The upper limit of the content of the constituent unit derived from the alkyl (meth)acrylate containing bio-derived carbon is not particularly limited, but from the viewpoint of adjusting the gel fraction of the above-mentioned adhesive layer, a preferable upper limit is 99% by weight, more preferably the upper limit is 97% by weight. Among them, in the above-mentioned acrylic copolymer, the content of the constituent units derived from the above-mentioned n-heptyl (meth)acrylate is more than 50% by weight, more preferably at least 60% by weight, further preferably at least 70% by weight, and especially preferably at least 70% by weight. 85% by weight or more, thereby further improving the adhesive force of the above-mentioned adhesive layer.

Regarding the content of the constituent units derived from the above-mentioned alkyl (meth)acrylate containing bio-derived carbon in the above-mentioned acrylic copolymer, the mass analysis and ¹ H-NMR measurement of the above-mentioned acrylic copolymer can be performed, and the content of the above-mentioned acrylic copolymer derived from each Calculated from the integral intensity ratio of the hydrogen peak of the monomer.

Regarding the aforementioned acrylic copolymer, the content of constituent units derived from (meth)acrylate having a branched alkyl group having 8 or less carbon atoms is less than 0.5% by weight, preferably derived from (meth)acrylic acid ester having a branched alkyl group. ) The content of the structural unit of acrylate is less than 0.5% by weight. Here, the (meth)acrylate having a branched alkyl group having 8 or less carbon atoms means a (meth)acrylate having 8 or less carbon atoms in the branched alkyl group. The so-called (meth)acrylate having a branched alkyl group may also be produced as an impurity in the preparation of a specific alkyl (meth)acrylate containing bio-derived carbon. That is, those belonging to the above-mentioned alkyl (meth)acrylates containing bio-derived carbon may also be used. Also, the (meth)acrylate having a branched alkyl group may be one other than the above-mentioned alkyl (meth)acrylate containing bio-derived carbon. When the content of the structural unit derived from the (meth)acrylic acid ester having the branched chain alkyl group having 8 or less carbon atoms in the acrylic copolymer is less than 0.5% by weight, the generation of odor of the adhesive tape is reduced. The content of the above structural units is preferably at most 0.1% by weight, more preferably less than 0.1% by weight, and still more preferably at most 0.05% by weight. The lower limit of the content of the constituent unit derived from the (meth)acrylate having a branched chain alkyl group having 8 or less carbon atoms is not particularly limited, and the closer to 0% by weight, the better, and 0% by weight is also acceptable. That is, the above-mentioned acrylic copolymer may not contain the above-mentioned constituent unit derived from (meth)acrylate having a branched chain alkyl group having 8 or less carbon atoms, and may not contain the above-mentioned (meth)acrylic acid ester derived from a branched chain alkyl group. The building block of acrylate.

The above-mentioned (meth)acrylate having a branched chain alkyl group having 8 or less carbon atoms is not particularly limited, for example: (meth)acrylate-1-methylheptyl, (meth)acrylate-2-ethylheptyl Hexyl (meth)acrylate, 1-methyloctyl (meth)acrylate, isooctyl (meth)acrylate, 1-methyldodecyl (meth)acrylate, isododecyl (meth)acrylate, etc. . These (meth)acrylates having a branched alkyl group having 8 or less carbon atoms may be used alone or in combination of two or more. More specifically, for example, when the above-mentioned alkyl (meth)acrylate containing carbon derived from organisms contains n-heptyl (meth)acrylate, as the above-mentioned branched alkyl group having a carbon number of 8 or less As (meth)acrylate, 1-methylheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. are mentioned, for example. Also, when the above-mentioned alkyl (meth)acrylate containing carbon derived from organisms contains n-octyl (meth)acrylate, as the above-mentioned (methyl) having a branched chain alkyl group having 8 or less carbon atoms, ) acrylate, for example, 1-methyloctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, etc. are mentioned. In addition, when the above-mentioned alkyl (meth)acrylate containing carbon derived from organisms contains lauryl (meth)acrylate, as the above-mentioned (meth)acrylic acid having a branched chain alkyl group having 8 or less carbon atoms Examples of esters include 1-methyldodecyl (meth)acrylate, isododecyl (meth)acrylate, and the like.

As a method of adjusting the content of the constituent unit derived from the (meth)acrylate having a branched chain alkyl group having 8 or less carbon atoms in the above-mentioned acrylic copolymer to the above-mentioned range, for example, it is possible to select and use the constituents of the above-mentioned Method for acrylic monomers of acrylic copolymers. In addition, when using a specific alkyl (meth)acrylate containing bio-derived carbon as the acrylic monomer constituting the above-mentioned acrylic copolymer, the following method can also be cited: by purifying the specific alkyl (meth)acrylate containing carbon derived from Alkyl (meth)acrylates of bio-carbon, reducing the content of (meth)acrylates with specific branched alkyl groups contained in the form of impurities. As said purification method, separation HPLC (liquid chromatography) etc. are mentioned, for example.

Regarding the content of the constituent unit derived from the (meth)acrylic ester having a branched chain alkyl group having 8 or less carbon atoms in the above-mentioned acrylic copolymer, mass analysis and ¹ H-NMR measurement of the above-mentioned acrylic copolymer can be performed. Calculated from the ratio of the integrated intensity of the hydrogen peak derived from each monomer.

It is preferable that the said acrylic copolymer further contains the structural unit derived from the monomer which has a crosslinkable functional group. When the said acrylic copolymer contains the said structural unit derived from the monomer which has a crosslinkable functional group, the cohesive force of the said adhesive agent layer improves, and adhesive force improves further.

The above-mentioned monomers having cross-linkable functional groups are not particularly limited, and examples include: monomers having hydroxyl groups, monomers having carboxyl groups, monomers having glycidyl groups, monomers having amide groups, monomers having nitrile groups, The monomer of the base, etc. These monomers having a crosslinkable functional group may be used alone or in combination of two or more. Among these, monomers having a hydroxyl group and monomers having a carboxyl group are preferred, and monomers having a hydroxyl group are more preferred from the viewpoint of easy adjustment of the gel fraction of the 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. As a monomer which has the said carboxyl group, the acrylic-type monomer which has a carboxyl group, such as (meth)acrylic acid, is mentioned, for example. As a monomer which has the said glycidyl group, the acrylic-type monomer which has a glycidyl group, such as glycidyl (meth)acrylate, is mentioned, for example. Examples of the monomer having an amide group include: (meth)acrylamide, dimethyl(meth)acrylamide, diethyl(meth)acrylamide, isopropyl(methyl)acrylamide, ) acrylamide, tertiary butyl (meth)acrylamide, methoxymethyl (meth)acrylamide, butoxymethyl (meth)acrylamide and other acrylic series with amide groups monomer. As a monomer which has the said nitrile group, the acrylic-type monomer which has a nitrile group, such as (meth)acrylonitrile, is mentioned, for example.

The content of the constituent unit derived from the monomer having a crosslinkable functional group in the acrylic copolymer is not particularly limited, but the lower limit is preferably 0.01% by weight, and the upper limit is 15% by weight. If the content of the constituent unit derived from the monomer having a crosslinkable functional group is within the above range, the cohesive force of the adhesive layer will be further improved, and the adhesive force will be further improved. The more preferable lower limit of the content of the constituent units derived from the monomer having a 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 %.

Regarding the content of the constituent units derived from the above-mentioned monomer having a crosslinkable functional group in the above-mentioned acrylic copolymer, the mass analysis and ¹ H-NMR measurement of the above-mentioned acrylic copolymer can be performed, and the hydrogen peaks derived from each monomer can be obtained. Calculated from the integral intensity ratio.

The above-mentioned acrylic copolymer may have a constitutional unit derived from the above-mentioned (meth)acrylate-derived (meth)acrylate having a branched alkyl group in addition to the constitutional unit derived from , and the structural unit of other monomers other than the above-mentioned structural unit derived from a monomer having a crosslinkable functional group". The above-mentioned other monomers are not particularly limited, and examples thereof include: alkyl (meth)acrylates (petroleum-derived monomers) containing alkyl groups with 7 to 12 carbons that do not contain bio-derived carbon, (meth)acrylates, base) alkyl acrylate, etc. Examples of the above-mentioned alkyl (meth)acrylate include: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, (meth)acrylate base) tert-butyl acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, 5,7,7-trimethyl-2-(1, 3,3-Trimethylbutyl) octan-1-ol and (meth)acrylic acid ester, alcohol with 18 total carbons and (methyl) having 1 or 2 methyl groups in the linear main chain Acrylic acid ester, behenyl (meth)acrylate, peanut (meth)acrylate, etc. These alkyl (meth)acrylates may be used alone or in combination of two or more.

In addition, examples of the above-mentioned other monomers include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-butoxy (meth)acrylate Ethyl ester, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, polypropylene glycol mono(meth)acrylate, etc. are preferable from the viewpoint of excellent rebound resistance Isocamphoryl (meth)acrylate. Furthermore, various monomers generally used for acrylic polymers, such as vinyl carboxylate, such as vinyl acetate, and styrene, can also be used as said other monomer. When producing the above-mentioned acrylic copolymer by UV polymerization, as the above-mentioned other monomers, for example, polyfunctional monomers such as 1,6-hexanediol di(meth)acrylate can also be used. These other monomers may be used alone or in combination of two or more.

The content of the constituent units derived from the other monomers in the acrylic copolymer can be calculated from the integrated intensity ratio of the hydrogen peaks derived from the respective monomers by mass analysis and ¹ H-NMR measurement of the acrylic copolymer.

The above-mentioned monomer having a crosslinkable functional group and the above-mentioned other monomers preferably contain bio-derived carbon, but may be composed of only petroleum-derived materials without bio-derived carbon. Theoretically, the above acrylic monomer constituting the acrylic copolymer can also be made into a monomer containing all bio-derived carbon. From the standpoint of cost or productivity of the adhesive tape, relatively inexpensive and readily available monomers containing bio-derived carbon can be used and combined with monomers composed only of petroleum-derived materials.

The glass transition temperature (Tg) of the above-mentioned acrylic copolymer is not particularly limited, but is preferably -20°C or lower. When the glass transition temperature (Tg) of the said acrylic copolymer is -20 degreeC or less, the adhesiveness of the said adhesive agent layer with respect to an adherend improves, and adhesive force improves further. The glass transition temperature (Tg) of the said acrylic copolymer is more preferably -30 degreeC or less, More preferably, it is -40 degreeC or less, Still more preferably, it is -50 degreeC or less. The lower limit of the glass transition temperature (Tg) of the acrylic copolymer is not particularly limited, but it is usually -90°C or higher, preferably -80°C or higher. The glass transition temperature (Tg) of the said acrylic copolymer can be calculated|required by differential scanning thermal analysis, for example.

The weight average molecular weight (Mw) of the above-mentioned acrylic copolymer is not particularly limited, but the lower limit is preferably 200,000, and the upper limit is 2 million. When the weight average molecular weight of the said acrylic copolymer exists in the said range, the adhesive force of the said adhesive agent layer will improve further. The weight average molecular weight of the said acrylic copolymer has a more preferable lower limit of 400,000, a more preferable upper limit of 1.8 million, a more preferable lower limit of 500,000, and a more preferable upper limit of 1.5 million. In addition, weight average molecular weight (Mw) means the weight average molecular weight in conversion of standard polyethylene measured by GPC (Gel Permeation Chromatography, gel permeation chromatography). Specifically, a measurement sample was prepared by diluting the acrylic copolymer 50 times with tetrahydrofuran (THF), and filtering the resulting dilution with a filter (material: polytetrafluoroethylene, pore size: 0.2 μm). Next, this measurement sample was supplied to a gel permeation chromatograph (manufactured by Waters, trade name "2690 Separations Module" or its equivalent), and GPC measurement was performed at a sample flow rate of 1 ml/min and a column temperature of 40°C. . The polystyrene conversion molecular weight of an acrylic copolymer was measured, and this value was made into the weight average molecular weight of an acrylic copolymer.

The above-mentioned acrylic copolymer can be obtained by subjecting a monomer mixture as a raw material to a radical reaction in the presence of a radical polymerization initiator. The form of the radical reaction is not particularly limited, and examples thereof include living radical polymerization (living radical polymerization), free radical polymerization (free radical polymerization), and the like. If living radical polymerization is used, compared with radical polymerization, a copolymer with a more uniform molecular weight and composition can be obtained, and the formation of low molecular weight components can be suppressed. power is further improved. The polymerization method is not particularly limited, and a previously known method can be used. Examples of the polymerization method include solution polymerization (boiling point polymerization or constant temperature polymerization), UV polymerization, emulsion polymerization, suspension polymerization, block polymerization, and the like. Among them, solution polymerization and UV polymerization are preferable from the point of further improving the adhesive force of the above-mentioned adhesive layer. Furthermore, solution polymerization is more preferable at the point which can mix the tackifying resin with the obtained acrylic copolymer easily, and the adhesive force of the said adhesive agent layer improves further.

When solution polymerization is used as a polymerization method, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, dimethylsulfoxide, ethanol, acetone, diethyl ether, and the like. These reaction solvents may be used alone or in combination of two or more.

The said radical polymerization initiator is not specifically limited, For example, an organic peroxide, an azo compound, etc. are mentioned. Examples of the aforementioned organic peroxides include 1,1-bis(tertiary hexyl peroxide)-3,3,5-trimethylcyclohexane, trimethyl peroxytrihexyl acetate, peroxide tert-butyl trimethylacetate, 2,5-dimethyl-2,5-bis(2-ethylhexyl peroxide) hexane, tert-hexyl 2-ethylhexanoate peroxide, peroxide Tert-butyl 2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl 3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, etc. As said azo compound, azobisisobutyronitrile, azobiscyclohexanecarbonitrile, etc. are mentioned, for example. These radical polymerization initiators may be used alone or in combination of two or more. Moreover, in the case of living radical polymerization, as said radical polymerization initiator, an organic tellurium polymerization initiator is mentioned, for example. The above-mentioned organotellurium polymerization initiator is not particularly limited as long as it is generally used in living radical polymerization, and examples thereof include organotellurium compounds, organotellurides, and the like. In addition, in living radical polymerization, in addition to the above-mentioned organic tellurium polymerization initiator, an azo compound can also be used as the above-mentioned radical polymerization initiator for the purpose of accelerating the polymerization rate.

The adhesive layer described above preferably does not contain a surfactant. Since the above-mentioned adhesive layer does not contain a surfactant, the adhesive force of the adhesive tape, especially the adhesive force at high temperature, is further improved. Furthermore, the above-mentioned adhesive layer does not contain a surfactant means that the content of the surfactant in the above-mentioned adhesive layer is 3% by weight or less, preferably 1% by weight or less. In order that the said adhesive agent layer does not contain a surfactant, it is preferable not to use a surfactant when obtaining the said acrylic copolymer. For this purpose, for example, solution polymerization, UV polymerization, or the like may be employed as a polymerization method for obtaining the above-mentioned acrylic copolymer. The content of the surfactant can be determined, for example, by measuring the adhesive layer using a liquid chromatography mass spectrometer (for example, NEXCERA manufactured by Shimadzu Corporation, Exactive manufactured by Thermo Fisher Scientific, etc.). More specifically, a filter (material: polytetrafluoroethylene, pore size: 0.2 μm) was used to filter the ethyl acetate solution of the adhesive layer. About 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 calculated from the area ratio of the peak corresponding to the surfactant in the adhesive layer. Furthermore, it is preferable to prepare a sample of known content of the above-mentioned surfactant in the above-mentioned adhesive layer for each type of surfactant, and make a calibration curve representing the relationship between the content of the surfactant and the peak area ratio. for analysis. Column Manufactured by Thermo Fisher Scientific, Hypersil GOLD (2.1×150 mm) Mobile phase Acetonitrile Column temperature 40°C Flow rate 1.0 mL/min Ionization method ESI Capillary temperature 350°C

It is preferable that the said adhesive agent layer further contains a crosslinking agent from a viewpoint which can moderately adjust a gel fraction. The said crosslinking agent is not specifically limited, For example, an isocyanate type crosslinking agent, an aziridine type crosslinking agent, an epoxy type crosslinking agent, a metal chelate type crosslinking agent etc. are mentioned. Among them, an isocyanate-based crosslinking agent is preferable from the point that the above-mentioned adhesive layer has excellent adhesion to an adherend. The molecular weight of the above-mentioned crosslinking agent is not particularly limited, but the molecular weight is preferably less than 2,000, and is preferably 100 or more from the viewpoint of production.

The content of the crosslinking agent in the adhesive layer is not particularly limited, but the lower limit is preferably 0.05 parts by weight and the upper limit is 7 parts by weight relative to 100 parts by weight of the acrylic copolymer. If the content of the above-mentioned crosslinking agent is within the above-mentioned range, the gel fraction of the above-mentioned adhesive layer is moderately adjusted, and the adhesive force is further improved. A more preferable lower limit of the content of the above-mentioned crosslinking agent is 0.1 parts by weight, and a more preferable upper limit is 5 parts by weight. In addition, the content of the said crosslinking agent means the quantity of the solid content of the said crosslinking agent.

It is preferable that the said adhesive agent layer further contains an tackifying resin. Thereby, the adhesive force of the above-mentioned adhesive layer is further improved. Specific examples of the aforementioned tackifying resins include: pine ester-based tackifying resins, terpene-based tackifying resins, furan-indene-based tackifying resins, alicyclic saturated hydrocarbon-based tackifying resins, C5-based Petroleum tackifying resin, C9 series petroleum tackifying resin, C5～C9 copolymerized petroleum tackifying resin, etc. These tackifying resins may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of pine ester-based tackifying resins and terpene-based tackifying resins is preferable.

As said pine ester type tackifying resin, polymerized pine ester type resin, hydrogenated pine ester type resin, etc. are mentioned, for example. As said terpene type tackifying resin, a terpene type resin, a terpene phenol type resin, etc. are mentioned, for example. The aforementioned pine ester-based tackifying resin and the aforementioned terpene-based tackifying resin are preferably biologically derived. Examples of the bio-derived pine ester-based tackifying resins include pine ester-based tackifying resins derived from natural resins such as pine resin. Examples of the bio-derived terpene-based tackifying resin include terpene-based tackifying resins derived from plant-derived essential oils and the like.

The content of the above-mentioned tackifying resin in the above-mentioned adhesive agent layer is not particularly limited, with respect to 100 parts by weight of the above-mentioned acrylic copolymer, the lower limit is preferably 10 parts by weight, and the upper limit is 60 parts by weight. If content of the said tackifying resin is in the said range, the adhesive force of the said adhesive agent layer will improve further. A more preferable lower limit of the content of the above-mentioned tackifying resin is 15 parts by weight, a more preferable upper limit is 50 parts by weight, and a more preferable upper limit is 35 parts by weight.

The above adhesive layer may optionally contain additives such as silane coupling agents, plasticizers, softeners, fillers, pigments, and dyes.

The total amount of volatile organic compounds in terms of toluene in the adhesive layer is preferably less than 1000 ppm. If the total amount of the above-mentioned volatile organic compounds is less than 1000 ppm, the generation of the odor of the adhesive tape will be further reduced. The total amount of the above-mentioned volatile organic compounds is more preferably less than 900 ppm. It is preferable that the total amount of the volatile organic compound measured immediately after manufacture of the said adhesive layer in terms of toluene is less than 1000 ppm. If the total amount of volatile organic compounds immediately after manufacture is less than 1000 ppm, the generation of odor of the adhesive tape will be further reduced. The total amount of the volatile organic compounds immediately after the above-mentioned production is more preferably less than 900 ppm. Moreover, it is preferable that the total amount of the volatile organic compound in conversion of toluene measured after 60 days or more from manufacture of the said adhesive agent layer is less than 1000 ppm. If the total amount of volatile organic compounds after 60 days or more from manufacture is less than 1000 ppm, the generation of odor of the adhesive tape will be further reduced. The total amount of volatile organic compounds after 60 days or more from the production is more preferably less than 900 ppm. In addition, "immediately after manufacture" means the period of less than 7 days from the time point of manufacture of the adhesive tape, and "after 60 days or more since manufacture" means after 60 days or more have elapsed from the time point of manufacture of the adhesive tape.

As a method of adjusting the total amount of volatile organic compounds to the above-mentioned range, for example, a method of appropriately selecting and using the acrylic monomer constituting the above-mentioned acrylic copolymer, or adjusting the heating and drying temperature in the production process of the adhesive tape, or The method of time, the method of storing in a well-ventilated warehouse, etc. In addition, when using a specific alkyl (meth)acrylate containing bio-derived carbon as the acrylic monomer constituting the above-mentioned acrylic copolymer, the following method can also be cited: by purifying the specific bio-derived carbon-containing Alkyl (meth)acrylates with carbon atoms, reducing the content of (meth)acrylates with specific branched alkyl groups contained in the form of impurities. As said purification method, separation HPLC (liquid chromatography) etc. are mentioned, for example.

The total amount of volatile organic compounds in terms of toluene in the above-mentioned adhesive layer can be measured as follows. Using a thermal desorption device (for example, ATD-400, manufactured by PerkinElmer), the weighed adhesive layer was heated at 90° C. for 30 minutes. Use a GC-MS device (for example, AutomassII-15, manufactured by JEOL Ltd.) to measure the amount of volatile components X (μg) (toluene conversion) released at this time, and calculate the total amount of volatile organic compounds using the following formula (1): Quantity (ppm). The total amount of volatile organic compounds (ppm) = the amount of volatile components X (μg) / the weight of the adhesive layer before heating (g) (1)

The gel fraction of the adhesive layer is not particularly limited, but the lower limit is preferably 10% by weight, and the upper limit is 70% by weight. When the gel fraction of the said adhesive layer is in the said range, the adhesiveness of the said adhesive layer with respect to an adherend improves, and adhesive force improves further. The more preferable lower limit of the gel fraction of the said adhesive layer is 20 weight%, and the more preferable upper limit is 50 weight%. The gel fraction of the above-mentioned adhesive layer can be measured in the following manner. First, cut the adhesive tape into a rectangular shape of 20 mm×40 mm to make a test piece. After immersing the test piece in ethyl acetate at 23°C for 24 hours, take it out from the ethyl acetate, and store it at 110°C. Dry for 1 hour. The weight of the test piece after drying was measured, and the gel fraction was calculated using the following formula (2). Furthermore, it is assumed that the release film for protecting the adhesive layer is not laminated on the test piece. Gel fraction (weight %)=100×(W ₂ -W ₀ )/(W ₁ -W ₀ ) (2) (W ₀ : weight of substrate, W ₁ : weight of test piece before dipping, W ₂ : The weight of the test piece after dipping and drying).

The method for adjusting the gel fraction of the above-mentioned adhesive layer to the above-mentioned range is not particularly limited, and it is preferable to adjust the composition and weight average molecular weight of the above-mentioned acrylic copolymer, and the type and type of the above-mentioned crosslinking agent as described above. Quantitative method.

In the above-mentioned adhesive layer, the content of bio-derived carbon is preferably 10% by weight or more. The content of bio-derived carbon of 10% by weight or more is based on the criteria of "bio-based products". It is preferable from the viewpoint of saving petroleum resources or reducing the emission of carbon dioxide that the content rate of the above-mentioned biogenic carbon is 10% by weight or more. A more preferable lower limit of the content rate of the above-mentioned biogenic carbon is 30% by weight, and a more preferable lower limit is 60% by weight. The upper limit of the content of the above-mentioned biogenic carbon is not particularly limited, and may be 100% by weight. Furthermore, bio-derived carbon contains a certain ratio of radioactive isotopes (C-14), whereas petroleum-derived carbon contains almost no C-14. Therefore, the biogenic carbon content can be calculated by measuring the concentration of C-14 contained in the adhesive layer. Specifically, it can be measured in accordance with ASTM D6866-20, which is a standard used by many bioplastic industries.

The thickness of the adhesive layer is not particularly limited, the lower limit is preferably 3 μm, and the upper limit is 300 μm. When the thickness of the said adhesive agent layer exists in the said range, the adhesive force of the said adhesive agent layer will improve further. 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 glass transition temperature (Tg) of the above-mentioned adhesive layer is not particularly limited, but is preferably below 10°C. When the glass transition temperature (Tg) of the said adhesive agent layer is 10 degreeC or less, the adhesiveness with respect to an adherend improves, and adhesive force improves further. The glass transition temperature (Tg) of the said adhesive layer is more preferably 5 degrees C or less, More preferably, it is 3 degrees C or less, More preferably, it is 0 degrees C or less. The lower limit of the glass transition temperature (Tg) of the above-mentioned adhesive layer is not particularly limited, but it is usually above -90°C, preferably above -80°C. The glass transition temperature (Tg) of the said adhesive layer can be calculated|required with the polymer dynamic viscoelasticity measurement apparatus "itkDVA-200" (manufactured by IT Meter. and Control Co., Ltd.), for example.

The adhesive tape of the present invention can be an unsupported tape without a base material, a single-sided adhesive tape with an adhesive layer on one side of the base material, or a double-sided adhesive tape with an adhesive layer on both sides of the base material. The substrate is not particularly limited, and conventionally known substrates can be used. In order to increase the biogenic carbon content of the adhesive tape as a whole, it is preferable to use a biogenic substrate. As the above-mentioned bio-derived base materials, for example, polyethylene terephthalate (PET), polyethylene furandicarboxylate (PEF, polyethylene furanoate), polylactic acid (PLA), polylactic acid (PLA), Films and non-woven fabrics made of polyester (PES) such as polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc. In addition, it is also exemplified: composed of plant-derived polyethylene (PE), polypropylene (PP), polyurethane (PU, polyurethane), triacetyl cellulose (TAC), cellulose, polyamide (PA), etc. film and non-woven fabrics, etc.

From the viewpoint of base material strength, the base material is preferably a film made of PES or a film made of PA. Furthermore, from the viewpoint of heat resistance or oil resistance, a film made of PA is preferable. Examples of the constituents of the film made of PA include nylon 11, nylon 1010, nylon 610, nylon 510, and nylon 410 made of castor oil, and nylon 56 made of cellulose.

In addition, from the viewpoint of reducing the use of new petroleum resources and reducing the emission of carbon dioxide to reduce the environmental load, it is also possible to use "a base material using renewable resources". As a recycling method of resources, for example, recycling of wastes such as packaging containers, home appliances, automobiles, building materials, food, etc., or wastes generated in the manufacturing process, by using washing, decontamination, or heating or fermentation Decomposition, the method of using the extracted materials again as raw materials. Examples of substrates using recycled resources include films or non-woven fabrics made of PET, PBT, PE, PP, PA, etc., which are obtained by re-resinizing recycled plastics. In addition, the recovered waste can be burned and used as heat energy related to the manufacture of the substrate or its raw materials, or the oil contained in the recovered waste can be mixed with petroleum, and obtained by fractional distillation and purification for raw materials.

From the viewpoint of improving compression characteristics, the above-mentioned base material may be a foam base material. As the above-mentioned foam substrate, a foam substrate composed of PE, PP and/or PU is preferable, and a foam composed of PE is more preferable from the viewpoint of achieving both high flexibility and strength. body substrate. As a structure of the foam base material which consists of PE, PE etc. which use sugarcane as a raw material are mentioned, for example.

The manufacturing method of the above-mentioned foam base material is not particularly limited, for example, the following method is preferred, that is, to prepare a foamable resin composition containing a PE resin containing sugar cane as a raw material and a foaming agent. PE, when the foamable resin composition is extruded into a sheet form using an extruder, the foaming agent is foamed, and the obtained polyolefin foam is cross-linked if necessary.

The thickness of the above-mentioned foam substrate is not particularly limited, but the lower limit is preferably 50 μm, and the upper limit is 5000 μm. If the thickness of the above-mentioned foam base material is within this range, high impact resistance can be exhibited, and at the same time, high flexibility that can be adhered closely along the shape of the adherend can be exhibited. A more preferable upper limit of the thickness of the above-mentioned foamed substrate is 1000 μm, and a more preferable upper limit is 300 μm.

Regarding the adhesive tape of the present invention, the preferable lower limit of the total thickness of the adhesive tape (the total thickness of the base material and the adhesive layer) is 3 μm, and the preferable upper limit is 6000 μm. When the total thickness of an adhesive tape exists in the said range, adhesive force will improve further. 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 this invention is not specifically limited. It can be produced by a previously known production method. For example, in the case of double-sided adhesive tape, the following method can be mentioned. First, add acrylic acid copolymer, and if necessary, a crosslinking agent or tackifying resin to a solvent to make a solution of adhesive A, apply this solution of adhesive A to the surface of the substrate, and completely dry the solvent in the solution Removed to form the adhesive layer A. Then, the release film was superimposed on the formed adhesive layer A in the state where the release process surface faced the adhesive layer A. Next, prepare a release film different from the above release film, apply the solution of adhesive B prepared in the same manner as above on the release surface of the release film, and dry completely to remove the solvent in the solution. This is a laminated film in which the adhesive layer B is formed on the surface of the release film. The obtained laminated film was laminated|stacked on the back surface of the base material in which the adhesive agent layer A was formed in the state which faced the adhesive agent layer B and the back surface of a base material, and the laminated body was produced. And by pressing the said laminated body with a rubber roller etc., the double-sided adhesive tape which has an adhesive layer on both surfaces of a base material, and the surface of this adhesive layer is covered with a release film is obtained.

In addition, it is also possible to produce two sets of laminated films in the same manner, so that the adhesive layer of the laminated film faces the substrate, and the laminated films are respectively laminated on both sides of the substrate to produce a laminated body. Rollers or the like press this laminate to obtain a double-sided adhesive tape having an adhesive layer on both surfaces of the substrate, and the surface of the adhesive layer is covered with a release film.

The application of the adhesive tape of the present invention is not particularly limited, but it is preferably used for electronic equipment parts in terms of the high content of bio-derived carbon, excellent adhesive force, and reduced odor generation. Or the fixing of vehicle parts. Specifically, the adhesive tape of the present invention can be preferably used for adhesion and fixation of electronic equipment parts in large portable electronic devices, adhesion and fixation of vehicle-mounted parts (for example, panels for vehicles), and the like. [Effect of Invention]

According to the present invention, it is possible to provide an adhesive tape which has a high content of bio-derived carbon, exhibits excellent adhesive force, and reduces the generation of odor.

Hereinafter, examples are given to further describe aspects of the present invention in detail, but the present invention is not limited to these examples.

＜N-octyl acrylate containing bio-derived carbon＞ n-Octyl acrylate was prepared by esterifying bio-derived carbon-containing n-octanol (manufactured by Kao Corporation) with acrylic acid (manufactured by Nippon Shokubai). In addition, at this time, the content of impurities was reduced by purifying n-octyl acrylate using a separation HPLC (liquid chromatography) apparatus (manufactured by GL Sciences, Inertsil SIL-150A).

＜N-heptyl acrylate containing bio-derived carbon＞ Cleavage of ricinoleic acid derived from castor oil yields a mixture comprising undecylenic acid and heptanol. Then, it was separated from undecylenic acid by distillation, whereby n-heptanol containing biogenic carbon was obtained. n-heptyl acrylate was prepared by esterifying the obtained n-heptanol with acrylic acid (manufactured by Nippon Shokubai). In addition, at this time, the content of impurities was reduced by purifying n-heptyl acrylate using a separation HPLC (liquid chromatography) apparatus (manufactured by GL Sciences, Inertsil SIL-150A).

＜Lauryl acrylate containing bio-derived carbon＞ Fatty acids are obtained by hydrolyzing the fat contained in palm kernel oil. Subsequently, lauric acid is extracted by fractionation of fatty acids, and lauryl alcohol is obtained by subjecting it to hydrogen reduction. Lauryl acrylate was prepared by esterifying the obtained lauryl alcohol with acrylic acid (manufactured by Nippon Shokubai). In addition, at this time, the content of impurities was reduced by purifying lauryl acrylate using a separation HPLC (liquid chromatography) apparatus (manufactured by GL Sciences, Inertsil SIL-150A).

＜Other acrylic monomers＞ ‧Acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) ‧2-Hydroxyethyl Acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.)

＜Crosslinking agent＞ ‧Isocyanate-based crosslinking agent (Coronate L-45, manufactured by Tosoh Corporation)

＜Tackifying resin＞ ‧Terpene phenol (Terpene phenol G-150, manufactured by Yasuhara Chemical Co., Ltd.) ‧Terpene resin (YS Resin PX1000, manufactured by Yasuhara Chemical Co., Ltd.)

(Example 1) (1) Manufacture of acrylic acid copolymer Ethyl acetate as a polymerization solvent was put into the reaction container, and nitrogen gas was used for foaming. Then, nitrogen gas was flowed in and the reaction container was heated to start reflux. Then, as a radical polymerization initiator, a radical polymerization initiator solution obtained by diluting 0.1 parts by weight of azobisisobutyronitrile 10 times with ethyl acetate was put into the reaction vessel, and the specific solution was added dropwise over 2 hours. Quantities of n-octyl acrylate, acrylic acid and 2-hydroxyethyl acrylate. After the dropwise addition, the radical polymerization initiator solution obtained by diluting 0.1 parts by weight of azobisisobutyronitrile 10 times with ethyl acetate as a radical polymerization initiator was put into the reaction vessel again, and carried out for 4 Hours of polymerization to obtain a solution containing acrylic acid copolymer.

The mass analysis and ¹ H-NMR measurement of the obtained acrylic copolymer were performed, and the content (% by weight) of the structural unit originating in each monomer was computed from the integrated intensity ratio of the hydrogen peak originating in each monomer.

A dilution solution obtained by diluting the obtained acrylic copolymer 50 times with tetrahydrofuran (THF) was filtered through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm), and a measurement sample was prepared. This measurement sample was supplied to a gel permeation chromatography (manufactured by Waters, 2690 Separations Module), and GPC measurement was performed at a sample flow rate of 1 ml/min and a column temperature of 40°C to measure the polystyrene conversion of the acrylic copolymer. Molecular weight to find the weight average molecular weight.

Also, the glass transition temperature (Tg) of the obtained acrylic copolymer was measured at each temperature under the following conditions by using a polymer dynamic viscoelasticity measuring device "itkDVA-200" (manufactured by IT Meter. and Control Co., Ltd.) The elastic modulus G' and the loss elastic modulus G'' were used to calculate tan δ at each temperature, and Tg, which was the peak value of tan δ, was measured. Measuring method: shear Heating rate: 5°C/min Measuring temperature range: -30～150℃ Set Distortion: 0.1% Frequency: 10Hz As for the measurement sample, a solution containing an acrylic copolymer is molded so that the final shape of the sample is 0.1 mm in thickness, 0.6 mm in width, and 10 mm in length, and it is heated and dried under the same conditions as when forming the adhesive layer. make.

(2) Manufacture of adhesive tape An isocyanate crosslinking agent (Coronate L-45 manufactured by Tosoh Corporation) was added to the obtained solution containing an acrylic copolymer so that the solid content became 0.5 parts by weight with respect to 100 parts by weight of the acrylic copolymer to prepare an adhesive solution. This adhesive solution was applied to the release-treated surface of a release-treated PET film having a thickness of 75 μm so that the thickness of the dried adhesive layer became 50 μm, and then dried at 110° C. for 5 minutes. The adhesive layer was superimposed on the release-treated surface of the release-treated PET film with a thickness of 75 μm, and cured at 40°C for 48 hours to obtain an adhesive tape (unsupported type).

(3) Determination of the total amount of volatile organic compounds Using a thermal desorption device (ATD-400, manufactured by PerkinElmer), the weighed adhesive layer was heated at 90° C. for 30 minutes. Measure the amount of volatile components X (μg) (toluene conversion) released at this time using a GC-MS device (AutomassII-15, manufactured by JEOL Ltd.), and calculate the total amount of volatile organic compounds using the following formula (1) ( ppm). The total amount of volatile organic compounds (ppm) = the amount of volatile components X (μg) / the weight of the adhesive layer before heating (g) (1). Furthermore, the total amount of volatile organic compounds was measured immediately after manufacture (initial stage) and after 60 days or more from manufacture.

(4) Measurement of Gel Fraction The release film on one side of the adhesive tape was peeled off, and a PET film (manufactured by FUTAMURA CHEMICAL, FE2002) with a thickness of 23 μm was attached, and cut into a rectangular shape of 20 mm×40 mm. Furthermore, the release film on the other side of the adhesive tape was peeled off, a test piece was produced, and the weight was measured. After immersing the test piece in ethyl acetate at 23°C for 24 hours, it was taken out from the ethyl acetate and dried at 110°C for 1 hour. The weight of the test piece after drying was measured, and the gel fraction was calculated using the following formula (2). Gel fraction (weight %)=100×(W ₂ -W ₀ )/(W ₁ -W ₀ ) (2) (W ₀ : weight of substrate (PET film), W ₁ : test piece before immersion weight, W ₂ : the weight of the test piece after dipping and drying).

(5) Determination of the glass transition temperature (Tg) of the adhesive layer Regarding the glass transition temperature (Tg) of the obtained adhesive layer, the storage elastic modulus at each temperature was measured under the following conditions with a polymer dynamic viscoelasticity measuring device "itkDVA-200" (manufactured by IT Meter. and Control Co., Ltd.) The number G' and the loss elastic modulus G'' were used to calculate tan δ at each temperature and measure Tg as the peak value of tan δ. Measuring method: shear Heating rate: 5°C/min Measuring temperature range: -30～150℃ Set Distortion: 0.1% Frequency: 10Hz As for the measurement sample, the adhesive solution was molded so that the final sample shape was 0.1 mm in thickness, 0.6 mm in width, and 10 mm in length, and it was produced by heating and drying under the same conditions as when forming the adhesive layer.

(Examples 2, 3, 5-11) As shown in Table 1, the type and amount of the acrylic monomer constituting the acrylic copolymer, the weight average molecular weight of the acrylic copolymer, the type and amount of the tackifying resin, and the amount of the crosslinking agent were changed. An adhesive tape was obtained in the same manner as in Example 1.

(Example 4) An adhesive tape was obtained in the same manner as in Example 3 except that a separation HPLC (liquid chromatography) device (manufactured by GL Sciences, Inertsil SIL-150A) was used for purification of n-heptyl acrylate.

(comparative example 1) An adhesive tape was obtained in the same manner as in Example 1 except that n-octyl acrylate was not used for separation HPLC purification.

(comparative example 2) An adhesive tape was obtained in the same manner as in Example 1 except that a specific amount of 1-methylheptyl acrylate was further added to the monomer mixture as a raw material.

(comparative example 3) An adhesive tape was obtained in the same manner as in Example 3 except that a specific amount of 2-ethylhexyl acrylate was further added to the monomer mixture as a raw material.

(comparative example 4) An adhesive tape was obtained in the same manner as in Example 3 except that n-heptyl acrylate was not used for separation HPLC purification.

＜Evaluation＞ The adhesive tapes obtained in Examples and Comparative Examples were evaluated by the following methods. The results are shown in Table 1.

(1) 180° peel force for SUS board A polyethylene terephthalate film (manufactured by FUTAMURA CHEMICAL, FE2002) with a thickness of 23 μm was lined on one side (unmeasured side) of the adhesive tape, cut into a width of 25 mm x length of 75 mm, and prepared as a test piece . After placing the test piece on the SUS plate with its adhesive layer (measurement side) facing the SUS plate, move a 2 kg rubber roller back and forth at a speed of 300 mm/min once to attach it to the SUS plate. on the test piece. Thereafter, curing was carried out at 23°C and 50% humidity for 20 minutes to prepare test samples. In accordance with JIS Z 0237:2009, under the conditions of 23°C and 50% humidity, the test sample was peeled off in a direction of 180° at a tensile speed of 300 mm/min, and the adhesive force (N/25 mm) was measured. When the measured 180° peel force exceeds 20 N/25 mm, it is set as ◎, when it exceeds 10 N/25mm but is less than 20 N/25 mm, it is set as ○, and when it is less than 10 N/25 mm When set to ×.

(2) Odor generation (sensory evaluation) Odor generation was evaluated in accordance with VDA270. Seal 50 cm ² of the adhesive tape into a 1 L glass bottle and place it at 40°C for 24 hours. After standing still for 24 hours, the odor immediately after taking out the adhesive tape was evaluated by the following 6-point method. Three or more sensory inspectors performed evaluations respectively, and calculated the average value. When the average value was 1, it was made into ○, when the average value was 2-3, it was made into Δ, and when the average value was 4-6, it was made into x. 1: Undetectable 2: Perceptible, but no discomfort 3: Obvious perceptible, but no obvious discomfort 4: Discomfort 5: Very uncomfortable 6: Unbearable

(3) Content rate of biogenic carbon For the adhesive tape, the biogenic carbon content was measured in accordance with ASTM D6866-20.

[Table 1] Example comparative example 1 2 3 4 5 6 7 8 9 10 11 1 2 3 4 adhesive layer Acrylic copolymer [wt%] Biologically derived Straight n-octyl acrylate 96.8 96.8 - - - 11.8 16.8 - - - - 96.4 96.3 - - n-heptyl acrylate - - 96.8 96.85 96.8 85 80 - 96.8 96.8 96.5 - - 96.3 96.4 lauryl acrylate - - - - - - - 96.6 - - - - - - - Branched 2-Ethylhexyl Acrylate 0.1 0.1 - - - 0.01 0.02 0.1 - - - 0.5 0.1 0.5 - 1-methylheptyl acrylate - - 0.1 0.05 0.1 0.1 0.1 - 0.1 0.1 0.4 - 0.5 0.1 0.5 non-biological - acrylic acid 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 - 2-Hydroxyethyl Acrylate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.3 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Weight average molecular weight of acrylic acid copolymer (Mw) 1.02 million 1.02 million 1.02 million 1.02 million 1.02 million 1.02 million 1.02 million 620,000 1.02 million 1.02 million 1.02 million 1.02 million 1.02 million 1.02 million 1.02 million Tg of acrylic acid copolymer[℃] -twenty four -twenty four -27 -27 -27 -27 -27 -twenty two -27 -27 -27 -twenty four -twenty four -27 -27 Tackifying resin (TF) [parts by weight] Terpene phenols - 30 - - 30 - - - 10 20 - - - - - Terpene resin 30 - - - Crosslinking agent [weight part] 0.5 1.5 0.5 0.5 1.5 0.5 0.5 0.5 0.9 1.2 0.5 0.5 0.5 0.5 0.5 Total amount of volatile organic compounds (toluene conversion) Immediately after manufacture (initial stage) [ppm] 800 940 780 680 860 820 880 770 730 790 720 860 1040 780 700 After more than 60 days since manufacture [ppm] 820 950 790 680 870 840 900 780 740 800 980 1290 1560 1170 1120 Gel fraction [wt%] 34 36 35 37 37 35 36 31 38 35 33 31 33 33 36 Tg of adhesive layer[℃] -twenty four 3 -27 -27 0 -27 -27 2 -16 -8 -26 -twenty four -twenty four -27 -27 evaluate 180° peeling force for SUS board [N/25 mm] 〇 〇 〇 〇 ◎ ◎ 〇 〇 〇 〇 〇 〇 〇 〇 〇 Odor generation 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 △ x x x x Biogenic carbon content [% by weight] 71 70 68 68 68 68 68 80 68 68 68 71 71 68 68 [Industrial availability]

According to the present invention, it is possible to provide an adhesive tape which has a high content of bio-derived carbon, exhibits excellent adhesive force, and reduces the generation of odor.

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Claims (8)

An adhesive tape having an adhesive layer containing an acrylic copolymer, characterized in that: The above-mentioned acrylic copolymer contains a constituent unit derived from an alkyl (meth)acrylate containing bio-derived carbon, In the said acrylic copolymer, content of the structural unit derived from the (meth)acrylate which has a branched chain alkyl group with 8 or less carbon atoms is less than 0.5 weight%. The adhesive tape according to claim 1, wherein the alkyl (meth)acrylate containing bio-derived carbon contains n-heptyl (meth)acrylate. The adhesive tape according to claim 1 or 2, wherein the (meth)acrylate having a branched alkyl group having 8 or less carbon atoms contains 1-methylheptyl (meth)acrylate. The adhesive tape according to claim 1, 2, or 3, wherein the content of the structural unit derived from the n-heptyl (meth)acrylate in the acrylic copolymer is 85% by weight or more. The adhesive tape according to claim 1, 2, 3 or 4, wherein the adhesive layer further contains an adhesive resin. The adhesive tape according to claim 1, 2, 3, 4, or 5, wherein the total amount of volatile organic compounds in the adhesive layer in terms of toluene is less than 1000 ppm. The adhesive tape according to claim 1, 2, 3, 4, 5, or 6, wherein the content of biogenic carbon in the adhesive layer is 10% by weight or more. The adhesive tape according to claim 1, 2, 3, 4, 5, 6 or 7, which is used for fixing electronic equipment parts or vehicle parts.