TW202140585A - Adhesive tape - Google Patents

Abstract

Disclosed is an adhesive tape in which is used, as an adhesive agent, an adhesive agent composition containing an acrylic copolymer which contains not less than 20 parts by mass and less than 40 parts by mass of a (meth)acrylic acid alkoxyalkyl ester, not less than 10 parts by mass and less than 25 parts by mass of a carboxylic acid group-containing (meth)acrylic monomer, not less than 5 parts by mass and less than 20 parts by mass of a (meth)acrylic acid alkyl ester having an alkyl group with 1-3 carbon atoms, a cyclohexyl group or an isobornyl group and not less than 30 parts by mass and less than 50 parts by mass of a (meth)acrylic acid alkyl ester having an alkyl group with 4-12 carbon atoms (the total amount of the monomers is 100 parts by mass), in which a crosslinked structure is formed using an isocyanate-based crosslinking agent and/or an epoxy-based crosslinking agent, and which has a weight average molecular weight of not less than 200,000 and less than 450,000. This adhesive tape exhibits high durability against oil/fat components such as sebum, sweat, foods and cosmetics, and exhibits an appropriate adhesive strength when bonded to an adherend.

Description

Adhesive tape

The present invention relates to an adhesive tape that has high durability to oil components such as sebum, sweat, food, cosmetics, and the like, and has a moderate adhesive force when adhered to an adherend.

In recent years, small mobile electronic devices such as smart phones and tablet computers have been rapidly spreading. Most of these are used to join the display panel and the frame using an acrylic adhesive or double-sided adhesive tape. However, most of the mobile electronic devices are equipped with a touch panel, which may be touched by a human finger or touch a human face when making a call.

If a person’s hand or face touches the touchpad, oils such as sebum or finger oil will adhere to the touchpad. The grease contains oleic acid and other ingredients, because the SP value (solubility parameter) of the grease is close to industrial organic solvents, and it will dissolve general acrylic resins.

The general industrial organic solvents vaporize in a short time due to their low boiling point, which is not easy to cause damage to the adhesives and adhesives. On the other hand, due to the high boiling point of oil components such as oleic acid, they will not vaporize in the living environment and remain in the electronic equipment, which will damage the adhesive and adhesive tape, causing the parts in the electronic equipment to float and peel off. , And shorten the life of electronic equipment.

Small mobile electronic devices such as smart phones have been held for a long time, and they may touch the face during a call. Therefore, oils such as sebum, sweat, food, cosmetics, etc. are likely to adhere to small mobile electronic devices. If these oils reach the adhesive or adhesive tape, the adhesive force may decrease. In addition, when the adhesive layer of the adhesive tape is softened due to grease, the adhesive may leak from the side of the adhesive tape, causing damage to the internal design and function of the machine. In addition, pressure applied to the outside due to the swelling of the adhesive layer may also cause the screen display of the electronic device to fail to operate normally.

Furthermore, as the screens of small mobile electronic devices such as smart phones have expanded, internal parts have become narrower and thinner, and small wearable devices have become practical. The adhesive tapes used inside such electronic devices have also become narrower and more compact. , Judging that bad situations such as the above are more likely to occur.

Patent Document 1 discloses a double-sided adhesive tape used for fixing parts of mobile electronic devices. Even if oily ingredients such as sebum permeate, the adhesive is not easy to soften or swell, and the adhesive does not ooze out. However, the invention of Patent Document 1 has not reviewed the situation in which the adhesive force is directly related to the occurrence of the adhesive and the floating or peeling of the adhesive tape inside the electronic device. In addition, when the durability of the oil and fat component is improved, the adhesive force when the adhesive tape is attached to the adherend is reduced, and the issues of improving durability and maintaining adhesive force cannot be considered. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2009-215355

(The problem to be solved by the invention)

For this reason, the purpose of the present invention is to provide an adhesive tape that has high durability against oil components such as sebum, sweat, food, cosmetics, and the like, and has a moderate adhesive force when sticking to an adherend. (Technical means to solve the problem)

In the adhesive tape of the present invention, the adhesive composition used as an adhesive contains an acrylic copolymer, and the monomer composition of the acrylic copolymer contains 20 parts by mass or more of alkoxyalkyl (meth)acrylate and Less than 40 parts by mass, 10 parts by mass or more and less than 25 parts by mass of carboxylic acid group-containing (meth)acrylic monomer, and 5 parts by mass or more and less than 20 parts by mass of the alkyl (meth)acrylate shown in the following formula 1 Parts by mass and the alkyl (meth)acrylate represented by formula 2 below 30 parts by mass and less than 50 parts by mass (the total of the above monomers is set to 100 parts by mass); wherein, the above-mentioned acrylic copolymerization system is obtained by Use one or both of isocyanate group-containing compounds with more than difunctional groups and epoxypropyl group-containing compounds with more than difunctional groups as crosslinking agents to form a crosslinked structure, and the weight average molecular weight is more than 200,000 and less than 450,000.

(式1中，R¹ 係表示CH₂ =CH-或CH₂ =C(CH₃ )-；R² 係表示碳原子數1~3之烷基、環己基或異𦯉基。)[化1]

(In formula 1, R ¹ represents CH ₂ =CH- or CH ₂ =C(CH ₃ )-; R ² represents an alkyl group with 1 to 3 carbon atoms, a cyclohexyl group or an isopropyl group.)

(式2中、R³ 係表示CH₂ =CH-或CH₂ =C(CH₃ )-；R⁴ 係表示碳原子數4~12之烷基。)[化2]

(In formula 2, R ³ represents CH ₂ =CH- or CH ₂ =C(CH ₃ )-; R ⁴ represents an alkyl group with 4 to 12 carbon atoms.)

The adhesive composition of the adhesive tape of the present invention may further contain an adhesive resin.

The adhesive composition of the adhesive tape of the present invention may further contain a silane coupling agent.

The adhesive composition of the adhesive tape of the present invention may further contain an antioxidant.

The adhesive tape of the present invention may further have a base material, and an adhesive composition may be used to form an adhesive layer on one or both sides of the base material. (Compared with the effect of previous technology)

The adhesive tape of the present invention has high durability against oil components such as sebum, sweat, food, cosmetics, etc., and specifically, has oil resistance that can maintain a certain adhesive force even if the oil components are adhered. In addition, the adhesive tape of the present invention has a moderate adhesive force when it is adhered to an adherend, and has excellent adhesive force maintenance performance when it adheres to a grease component. Therefore, the adhesive tape of the present invention is quite suitable for, for example, the joining of the display panel and the frame of small mobile electronic devices such as smart phones, and the fixing of parts inside the frame.

＜Acrylic copolymer＞ The monomer composition of the acrylic copolymer system of the present invention contains: (meth)acrylic acid alkoxyalkyl ester, carboxylic acid group-containing (meth)acrylic monomer, and (meth)acrylic acid alkyl ester represented by formula 1 above , And the (meth)acrylic acid alkyl ester represented by the above formula 2, by using an isocyanate group-containing compound with a difunctional group or more or a glycidyl group-containing compound with a difunctional group or more as a cross-linking agent, a cross-linked structure is formed , And the weight average molecular weight is more than 200,000 but less than 450,000.

The alkoxyalkyl (meth)acrylate system can be used, for example: methoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, (meth)acrylate Ethoxy ethyl acrylate, ethoxy propyl (meth) acrylate, ethoxy butyl (meth) acrylate, etc. In consideration of the stability of the polymerization reaction and the ease of acquisition, it is preferable to use methoxyethyl (meth)acrylate.

Relative to alkoxyalkyl (meth)acrylate, carboxylic acid group-containing (meth)acrylic monomer, alkyl (meth)acrylate represented by formula 1 above, and (meth)acrylate represented by formula 2 above The alkyl acrylate (hereinafter referred to as the "four monomers") totals 100 parts by mass, and the content of the alkoxyalkyl (meth)acrylate is 20 parts by mass or more and less than 40 parts by mass. If the content is less than 20 parts by mass, the monomer units with higher SP values in the acrylic copolymer of the present invention will decrease, and the durability against oil components will decrease. When sebum, sweat, food, cosmetics and other oil components adhere At this time, the adhesive force will be significantly reduced, and it will not be possible to maintain the necessary adhesive force for purposes such as fixing the internal parts of the electronic device. In addition, if the content is 40 parts by mass or more, the initial adhesive force of the adhesive is reduced, and the workability at the time of fixing parts inside electronic equipment, etc., is reduced. The content is more preferably 25 parts by mass or more and less than 40 parts by mass.

The single system of (meth)acrylic acid containing carboxylic acid group can use for example: (meth)acrylic acid, β-carboxyethyl (meth)acrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid Acrylic acid, citraconic acid, glutaconic acid, 2-propenyloxyethyl succinic acid, 2-propenyloxyethyl phthalic acid, etc. Among them, in consideration of the crosslinking density and the ease of obtaining the obtained adhesive, it is preferable to use (meth)acrylic acid.

The content of the carboxylic acid group-containing (meth)acrylic monomer is 10 parts by mass or more and less than 25 parts by mass with respect to 100 parts by mass of the above-mentioned 4 kinds of monomers in total. If the content is less than 10 parts by mass, the crosslinking density of the adhesive decreases, and the adhesive swells due to oil components such as sebum, sweat, food, and cosmetics. In addition, if the content is 25 parts by mass or more, the initial adhesive force of the adhesive decreases, resulting in a decrease in workability at the time of parts fixing work in electronic equipment. The content is more preferably 10 parts by mass or more and 23 parts by mass or less.

The alkyl (meth)acrylate system represented by the above formula 1 can be used, for example: methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, cyclohexyl (meth)acrylate, isopropyl (meth)acrylate 𦯉Ester etc. In consideration of ease of acquisition, it is best to use methyl acrylate.

The content of the alkyl (meth)acrylate represented by the above formula 1 is 5 parts by mass or more and less than 20 parts by mass with respect to 100 parts by mass of the total of the 4 types of monomers. If the content is less than 5 parts by mass, the backlash resistance of the adhesive is reduced, and the adhesive force required for the fixing of parts in electronic equipment cannot be satisfied. In addition, if the content is 20 parts by mass or more, the initial adhesive force of the adhesive decreases, leading to a decrease in workability at the time of parts fixing work in electronic equipment. The content is more preferably 5 parts by mass or more and 15 parts by mass or less.

The alkyl (meth)acrylate system represented by the above formula 2 can be used, for example: butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, (meth)acrylic acid Hexyl ester, isohexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, ( Isononyl meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isododecyl (meth)acrylate, and the like. In order to maintain the viscosity when the acrylic copolymer is used as an adhesive, it is best to use 2-ethylhexyl (meth)acrylate with a low Tg (glass transition point).

The content of the alkyl (meth)acrylate represented by the above formula 2 is 30 parts by mass or more and less than 50 parts by mass relative to 100 parts by mass of the total of the 4 types of monomers. If the content is less than 30 parts by mass, the initial adhesive force of the adhesive will decrease, resulting in a decrease in workability at the time of parts fixing work in electronic equipment. If the content is more than 50 parts by mass, the durability to oil components will be reduced. When oil components such as sebum, sweat, food, cosmetics, etc. adhere, the adhesive force will be significantly reduced, making it impossible to maintain the internal parts of the electronic device. Adhesion necessary for other purposes. The content is more preferably 30 parts by mass or more and 45 parts by mass or less.

Compounds containing isocyanate groups with more than bifunctional groups (hereinafter also referred to as "isocyanate-based crosslinking agents") can be used, for example: toluene diisocyanate, xylene diisocyanate, chlorophenylene diisocyanate, and hexamethylene Methyl diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, etc.

Epoxy propyl compound containing more than bifunctional groups (hereinafter also referred to as "epoxy crosslinking agent"), for example: 1,3-bis(N,N-diglycidylaminomethyl) Cyclohexane, N,N,N',N'-tetraepoxypropyl m-xylene diamine, N,N,N',N'-tetraepoxypropylaminophenylmethane, isocyanuric acid Triglycidyl acid, mN,N-diglycidylamino phenylglycidyl ether, N,N-diglycidyl toluidine, N,N-diglycidylaniline, pentaerythritol poly Glycidyl ether, 1,6-hexanediol diglycidyl ether, etc.

The addition amount of the isocyanate group-containing compound having a bifunctional group or more and the glycidyl group-containing compound having a bifunctional group or more used as a crosslinking agent is not particularly limited. The swelling degree of the adhesive composition can be adapted to the use environment of the adhesive tape of the present invention, and then the addition amount of the crosslinking agent can be adjusted.

The acrylic copolymer system of the present invention can be produced by polymerizing these monomers by various polymerization methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. For example, in a reaction vessel, the monomers and polymerization initiator are dissolved in a solvent such as ethyl acetate, and stirred for a certain period of time at a constant temperature to obtain an acrylic copolymer.

Furthermore, the above-mentioned acrylic copolymer system can generate an acrylic copolymer with a crosslinked structure by adding a crosslinking agent alone (or adding it together with a polymerization initiator) and stirring.

The weight average molecular weight of the acrylic copolymer of the present invention is 200,000 or more but less than 450,000. When the weight average molecular weight is less than 200,000, the cohesive force necessary for the adhesive cannot be obtained, which causes the adhesive to ooze out when the adhesive tape is stuck to the adherend. In addition, when the weight average molecular weight is 450,000 or more, the tracking property of the adhesive tape to the adherend is reduced, and the necessary adhesive force for fixing the internal parts of the electronic device cannot be obtained. The weight average molecular weight is more preferably 250,000 or more but less than 450,000.

In the acrylic copolymer of the present invention, optional components such as a tackifier resin, a silane coupling agent, and an antioxidant may be added as necessary.

Tackifying resins can be used, for example: rosin ester resins (rosin esters, disproportionated rosin esters, hydrogenated rosin esters, etc.), terpene resins (terpene resins, aromatic modified terpene resins, hydrogenated terpene resins, terpenes) Phenols, etc.), petroleum resins (aliphatic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, aliphatic petroleum resins, etc.), pure single-system resins (coumarone, indene resin, styrene resin, etc.) Etc.), condensed resins (phenolic resins, xylene resins, etc.), etc. By adding a tackifying resin, the hardness of the adhesive can be reduced and the initial adhesion to the adherend can be improved.

Silane coupling agents can be used, for example: 2-(3,4-epoxycyclohexyl) ethyl trimethoxy silane, 3-glycidoxy propyl trimethoxy silane, 3-glycidoxy propyl Methyldiethoxysilane, 3-glycidoxypropyl triethoxysilane, tris(trimethoxysilylpropyl) isocyanurate, etc. Two or more silane coupling agents can also be used in combination. By using silane coupling agent, the backlash resistance of the adhesive can be improved, and the resistance to humidity and heat load, which has been reduced due to the narrowing and fine processing of the adhesive tape, can be improved.

For the antioxidant system, for example, hindered phenol antioxidants and the like can be used. By adding antioxidants, the backlash resistance of the adhesive can be improved, and the resistance to heat and humidity, which has been reduced due to the narrowing and fine processing of the adhesive tape, can be improved.

＜Adhesive tape＞ The adhesive tape of the present invention uses an adhesive composition containing the acrylic copolymer (and optional components as necessary) described above as an adhesive. The so-called "adhesive tape using an adhesive composition as an adhesive" refers to, for example, a sheet-like adhesive tape formed from the adhesive composition (the so-called "baseless adhesive tape"), or the use of the adhesive composition on the base An adhesive tape with an adhesive layer formed on one or both sides of the material.

The baseless adhesive tape is formed by coating an acrylic copolymer on a support such as release paper, and then drying it. On the other hand, the adhesive tape with a base material can also be coated with acrylic copolymer on the base material, and then dried to form an adhesive layer, and the acrylic copolymer can be coated on a support such as release paper to form an adhesive. After layering, the adhesive layer is attached to one or both sides of the substrate. The adhesive layer of the baseless adhesive tape and the adhesive tape provided with a substrate may be a single layer or a laminate of multiple layers.

The thickness of the adhesive layer of the adhesive tape provided with the substrate is preferably 1 to 200 μm, more preferably 5 to 100 μm. The thickness of the baseless adhesive tape is preferably 1 to 200 μm, more preferably 5 to 100 μm.

The method of coating the acrylic copolymer on a support such as a substrate or release paper is not particularly limited, and a known method may be used. Specific examples include, for example, methods using roll coaters, die coaters, lip coaters, dip roll coaters, bar coaters, knife coaters, spray roll coaters, and the like.

When the adhesive tape has a substrate, the substrate is not particularly limited, as long as a known substrate is used. Specific examples of the substrate include fiber-based substrates such as paper, cloth, nonwoven fabric, and netting; olefin-based resins, polyester-based resins, polyvinyl chloride-based resins, vinyl acetate-based resins, polyamide-based resins, Polyimide resin, polyether ether ketone (PEEK), polyphenylene sulfide (PPS) and other resin substrates (resin film or resin sheet); rubber sheet, foam sheet (foam substrate), metal foil, Metal plate. In addition, these laminated bodies may be, for example, a laminated body of a resin base material and a base material other than resin, or a laminated body between a resin base material. The substrate system may be a single layer or a multiple layer. The substrate is provided with one side of the adhesive layer, and various treatments such as backside treatment, antistatic treatment, and primer treatment can also be performed as needed. The thickness of the substrate is preferably 5 to 500 μm, more preferably 10 to 200 μm.

The adhesive tape can also be protected by release paper or other films. Release paper or other films are not particularly limited, and known materials can be used as needed. [Example]

Hereinafter, the present invention will be described in more detail using examples and comparative examples.

(Weight average molecular weight) The weight average molecular weight (Mw) of the acrylic copolymer is measured by the GPC method in accordance with the following measuring equipment and conditions, and the molecular weight value of the acrylic copolymer in terms of standard polystyrene is measured. ・Device: LC-2000 series (manufactured by JASCO Corporation) ・Pipe column: Shodex KF-806M×2, Shodex KF-802×1 ・Precipitate liquid: Tetrahydrofuran (THF) ・Flow rate: 1.0mL/min ・Column temperature: 40℃ ・Injection volume: 100μL ・Detector: Refractometer (RI)

(Initial adhesion) The case of using base material A: On a SUS304 board polished with No. 280 water-resistant abrasive paper, a 2.0kg roller is used to perform 1 reciprocation, and a sample of a 10mm wide double-sided adhesive tape with a thickness of 25μm polyester film backing is applied under pressure. , After 20 minutes of pressure bonding, the 180° pull-peel adhesive force (N/10mm width) was measured according to the method described in JIS Z 0237:2000.

The case of using base material B: On a SUS304 board polished with No. 280 water-resistant abrasive paper, a 2.0kg roller is used to perform 1 reciprocation, and a sample of a 10mm wide double-sided adhesive tape with a thickness of 50μm polyester film backing is applied under pressure. , After 20 minutes of pressure bonding, the 180° pull-peel adhesive force (N/10mm width) was measured according to the method described in JIS Z 0237:2000.

(Adhesion with time) The case of using base material A: On a SUS304 board polished with No. 280 water-resistant abrasive paper, a 2.0kg roller is used to perform 1 reciprocation, and a sample of a 10mm wide double-sided adhesive tape with a thickness of 25μm polyester film backing is applied under pressure. , After 72 hours of pressure bonding, the 180° pull-peel adhesion (N/10mm width) was measured according to the method described in JIS Z 0237:2000.

The case of using base material B: On a SUS304 board polished with No. 280 water-resistant abrasive paper, a 2.0kg roller is used to perform 2.5 reciprocation, and a sample of a 10mm wide double-sided adhesive tape with a thickness of 50μm polyester film backing is applied under pressure. , After 72 hours of pressure bonding, the 180° pull-peel adhesion (N/10mm width) was measured according to the method described in JIS Z 0237:2000.

(Adhesion after promotion: Na) The case of using base material A: On a SUS304 board polished with No. 280 water-resistant abrasive paper, a 2.0kg roller is used to perform 1 reciprocation, and a sample of a 10mm wide double-sided adhesive tape with a thickness of 25μm polyester film backing is applied under pressure. , Place for 72 hours in an environment with a temperature of 65±5°C and a humidity of 90±10%. Then, place it in an environment with a temperature of 23±5°C and a humidity of 50±5% for 2 hours. The 180° peel adhesion (N/10mm width) of the sample was measured according to the method described in JIS Z 0237:2000.

The case of using base material B: On the SUS304 board polished with 280 water-resistant abrasive paper, a 2.0kg roller is used for 2.5 reciprocation, and a sample of a 10mm wide double-sided adhesive tape with a thickness of 50μm SUS film backing is pressed. Place for 72 hours in an environment with a temperature of 65±5°C and a humidity of 90±10%. Then, place it in an environment with a temperature of 23±5°C and a humidity of 50±5% for 2 hours. The 180° peel adhesion (N/10mm width) of the sample was measured according to the method described in JIS Z 0237:2000.

(Adhesion after immersion in oleic acid: Nb) The case of using base material A: On a SUS304 board polished with No. 280 water-resistant abrasive paper, a 2.0kg roller is used to perform 1 reciprocation, and a sample of a 10mm wide double-sided adhesive tape with a thickness of 25μm polyester film backing is applied under pressure. . The sample was immersed in oleic acid, and placed in an environment with a temperature of 65±5°C and a humidity of 90±10% for 72 hours. Then, take the sample out of the container and wipe off the oleic acid with pure water. After wiping off the water droplets, place it in an environment with a temperature of 23±5°C and a humidity of 50±5% for 2 hours. The 180° peel adhesion (N/10mm width) of the sample was measured according to the method described in JIS Z 0237:2000.

The case of using base material B: On a SUS304 plate polished with No. 280 water-resistant abrasive paper, a 2.0 kg roller is used to perform 2.5 reciprocation, and a sample of a double-sided adhesive tape with a width of 10 mm with a thickness of 50 μm SUS film backing is adhered under pressure. The sample was immersed in oleic acid, and placed in an environment with a temperature of 60±5°C and a humidity of 90±10% for 72 hours. Then, take the sample out of the container and wipe off the oleic acid with pure water. After wiping off the water droplets, place it in an environment with a temperature of 23±5°C and a humidity of 50±5% for 2 hours. The 180° peel adhesion (N/10mm width) of the sample was measured according to the method described in JIS Z 0237:2000.

(Adhesive force retention rate after oleic acid immersion: X) Obtain according to the following formula: X=100×Nb/Na

(Destruction mode) For the sample after the promotion of adhesion (Na) measurement and the sample after oleic acid immersion, the adhesion (Nb) was measured, and the damaged parts were observed respectively. The case where the adhesive is damaged is rated as "cohesion failure" ("cohesion" in Tables 2 to 4), and the case where there is damage between the adhesive and the adherend is rated as "interface failure", and the substrate has occurred The damage was rated as "substrate damage" ("substrate" in Tables 2 to 4).

[Example 1] (Preparation of acrylic copolymer) In a reaction device equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen introduction tube, it is filled with: the monomers that constitute the copolymer, ethyl acetate, and the n-dodecyl group of the chain transfer agent as shown in Table 1 0.03 parts by mass of mercaptan and 0.05 parts by mass of lauryl peroxide, which is a radical polymerization initiator, were sealed in nitrogen, and the reaction was carried out at 67°C for 3 hours under a nitrogen stream while stirring. Then, the reaction was carried out at 82°C for 3 hours. After the reaction is over, it is cooled to room temperature, and ethyl acetate is added. In this way, a copolymer with a solid content of 30% is obtained. The weight average molecular weight of the acrylic copolymer prepared in Example 1 was 420,000.

(Adhesive preparation) With respect to 100 parts by mass of the solid content of the copolymer, 1.8 parts by mass of an isocyanate-based crosslinking agent (crosslinking agent A) (manufactured by Tosoh Corporation, trade name L-45E) as a crosslinking agent was added to prepare an adhesive.

(Manufacturing of double-sided adhesive tape) On both sides of a polyethylene terephthalate film (substrate A) with a thickness of 12μm that has been treated by double-sided corona discharge, a separately prepared primer is applied and dried at 120°C. A primer layer is formed on A. The primer layer on the first surface of the substrate A was smoothly coated on the entire surface with the prepared adhesive, and heated and dried at 100°C to form an adhesive layer with a thickness of 19 μm. In addition, a release paper treated with silicone is pasted on the adhesive layer. Then, the primer layer on the second side was also coated with the prepared adhesive and dried in the same manner, then the release paper was laminated, and after curing at 40°C for 3 days, a double-sided layer with a total thickness of 50μm was obtained. Adhesive tape.

[Example 2] Except that the crosslinking agent was changed to an epoxy-based crosslinking agent (crosslinking agent B) (manufactured by Soken Chemical Co., Ltd., trade name E-5CM) when the adhesive was formulated, the rest were made in the same manner as in Example 1. Double-sided adhesive tape.

[Example 3] Except for the production of double-sided adhesive tapes, the adhesive formulated in the same manner as in Example 1 was smoothly coated on the silicone-treated release paper and heated and dried at 90°C to form an adhesive with a thickness of 50μm. Floor. Then, the adhesive on the release paper was pasted on both sides of the substrate (substrate B) with a thickness of 100μm composed of polyethylene (PE) foam and was treated by corona discharge on both sides. After curing for 3 days at 40°C, a double-sided adhesive tape with a total thickness of 200 μm was obtained.

[Example 4] Except when the adhesive is formulated, 8 parts by mass of D-6011 (trade name) manufactured by Arakawa Chemical Industry Co., Ltd. manufactured by Arakawa Chemical Industry Co., Ltd. (trade name) is added to the tackifying resin system by using ethyl acetate to form a 50% dilution, and the silane coupling agent system is added by using ethyl acetate. 2 parts by mass of KBM-403 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. of the ester formed as a 5% dilution, antioxidant system added with IRGANOX (registered trademark) 1010 manufactured by BASF Japan Co., Ltd.: 0.2 parts by mass, the rest are all In the same manner as in Example 3, a double-sided adhesive tape was produced.

[Comparative Example 1] (Preparation of acrylic copolymer) Except that methyl acrylate was not used, 50 parts by mass of methoxyethyl acrylate, 10 parts by mass of acrylic acid, and 40 parts by mass of 2-ethylhexyl acrylate were used instead, and the amount of crosslinking agent added was changed to 1.2 parts by mass Other than that, in the same manner as in Example 1, a copolymer with a solid content concentration of 30% was obtained. The weight average molecular weight of the acrylic copolymer prepared in Comparative Example 1 was 750,000.

(Adhesive preparation) With respect to 100 parts by mass of the solid content of the copolymer, add 1.2 parts by mass of isocyanate-based crosslinking agent (crosslinking agent A) (manufactured by Tosoh Corporation, trade name L-45E) of the crosslinking agent, and the use of tackifying resin 8 parts by mass of D-6011 (trade name) manufactured by Arakawa Chemical Industry Co., Ltd. manufactured by ethyl acetate as a 50% dilution, KBM manufactured by Shin-Etsu Chemical Co., Ltd. manufactured by Shin-Etsu Chemical Co., Ltd. by using ethyl acetate to form a 5% dilution of silane coupling agent 2 parts by mass of 403 (trade name), IRGANOX (registered trademark) 1010 manufactured by BASF Japan Co., Ltd., an antioxidant: 0.2 parts by mass, to prepare an adhesive.

(Manufacturing of double-sided adhesive tape) Except for using this adhesive, the double-sided adhesive tape was obtained in the same manner as in Example 1.

[Comparative Example 2] Except for the preparation of acrylic copolymers, methyl acrylate was not used, but 86 parts by mass of methoxyethyl acrylate, 10 parts by mass of acrylic acid, and 4 parts by mass of 2-ethylhexyl acrylate were used instead, and the crosslinking agent The double-sided adhesive tape was produced in the same manner as in Example 1, except that the addition amount of was changed to 1.2 parts by mass. The weight average molecular weight of the acrylic copolymer prepared in Comparative Example 2 was 1.05 million.

[Comparative Example 3] Except that during the preparation of the acrylic copolymer, the addition amount of n-dodecyl mercaptan of the chain transfer agent was changed to 0.06 parts by mass and the addition amount of crosslinking agent A was changed to 2.4 parts by mass, the rest were all in accordance with In Comparative Example 2, a double-sided adhesive tape was produced in the same manner. The weight average molecular weight of the acrylic copolymer prepared in Comparative Example 3 was 340,000.

[Comparative Example 4] Except that methoxyethyl acrylate was not used in the preparation of acrylic copolymers, and 86 parts by mass of 2-(ethoxyethoxy) ethyl acrylate (EOEOEA) were used instead, the rest were all in accordance with the comparison In Example 2, a double-sided adhesive tape was produced in the same manner. The weight average molecular weight of the acrylic copolymer prepared in Comparative Example 4 could not be measured.

[Comparative Example 5] Except for the production of double-sided adhesive tapes, the adhesive prepared in the same manner as in Comparative Example 1 was smoothly coated on the silicone-treated release paper and heated and dried at 90°C to form an adhesive with a thickness of 50μm. Floor. Then, the adhesive on the release paper was pasted on both sides of the base material (substrate B) with a thickness of 100 μm composed of polyethylene (PE) foam and was treated by corona discharge on both sides. After curing for 3 days at 40°C, a double-sided adhesive tape with a total thickness of 200 μm was obtained.

[Comparative Example 6] Except for the production of double-sided adhesive tapes, the adhesive formulated in the same manner as in Comparative Example 2 was smoothly coated on the silicone-treated release paper and heated and dried at 90°C to form an adhesive with a thickness of 50μm. Floor. Then, the adhesive on the release paper was pasted on both sides of the substrate (substrate B) with a thickness of 100μm composed of polyethylene (PE) foam and was treated by corona discharge on both sides. After curing for 3 days at 40°C, a double-sided adhesive tape with a total thickness of 200 μm was obtained.

[Comparative Example 7] Except for the production of double-sided adhesive tapes, the adhesive formulated in the same manner as in Comparative Example 3 was smoothly coated on the silicone-treated release paper and heated and dried at 90°C to form an adhesive with a thickness of 50μm. Floor. Then, the adhesive on the release paper was pasted on both sides of the substrate (substrate B) with a thickness of 100μm composed of polyethylene (PE) foam and was treated by corona discharge on both sides. After curing for 3 days at 40°C, a double-sided adhesive tape with a total thickness of 200 μm was obtained.

[Comparative Example 8] In the preparation of the acrylic copolymer, the double-sided adhesive tape was produced in the same manner as in Comparative Example 2, except that 10 parts by mass of acrylic acid was substituted for 10 parts by mass of 4-hydroxybutyl acrylate. The weight average molecular weight of the acrylic copolymer prepared in Comparative Example 8 was 730,000.

The formulations of Example 1 to Example 4 and Comparative Example 1 to Comparative Example 8, the weight average molecular weight of the acrylic copolymer, and the substrate used when forming the double-sided adhesive tape are shown in Table 1. In addition, the initial adhesive force, time-dependent adhesive force, accelerated adhesive force Na, adhesive force Nb after oleic acid immersion, adhesive force retention rate X after oleic acid immersion, and failure mode measured for each double-sided adhesive tape are as follows As shown in Table 2~Table 4.

The abbreviations used in Table 1 are as follows: AME=Methoxyethyl acrylate EOEOEA=-2-(2-ethoxyethoxy) ethyl acrylate AA=Acrylic 4-HBA=-4-hydroxybutyl acrylate MA=methyl acrylate 2-EHA=-2-ethylhexyl acrylate

[Table 1] Table 1 Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Comparative example 8 AME 30 30 30 30 50 86 86 - 50 86 86 86 EOEOEA - - - - - - - 86 - - - - AA 20 20 20 20 10 10 10 10 10 10 10 - 4-HBA - - - - - - - - - - - 10 MA 10 10 10 10 - - - - - - - - 2-EHA 40 40 40 40 40 4 4 4 40 4 4 4 Crosslinker A 1.8 - 1.8 1.8 1.2 1.2 2.4 1.2 1.2 1.2 2.4 1.2 Crosslinking agent B - 1.8 - - - - - - - - - - Tackifying resin - - - 8 8 - - - 8 - - - Silane coupling agent - - - 2 2 - - - 2 - - - Antioxidants - - - 0.2 0.2 - - - 0.2 - - - Weight average molecular weight 420,000 420,000 420,000 420,000 750,000 1.05 million 340,000 Unable to determine 750,000 1.05 million 340,000 730,000 Substrate A A B B A A A A B B B A

[Table 2] Table 2 Example 1 Example 2 Example 3 Example 4 Initial adhesion N/10mm width 9.1 8.0 20.7 16.1 Adhesion over time N/10mm width 12.5 12.0 15.8 17.3 Promote post-adhesive force Na N/10mm width 13.6 13.0 22.4 21.1 Adhesion Nb after immersion in oleic acid N/10mm width 3.6 3.2 6.3 11.1 Adhesion retention rate after oleic acid immersion X % 26 25 28 53 Destruction mode (Na) - - Substrate Substrate Failure mode (Nb) - - Cohesion Substrate + Cohesion

[table 3] table 3 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Initial adhesion N/10mm width 6.0 4.6 3.8 8.1 Adhesion over time N/10mm width 11.0 6.1 8.9 8.3 Promote post-adhesive force Na N/10mm width 8.9 7.1 10.7 7.1 Adhesion Nb after immersion in oleic acid N/10mm width 1.3 5.1 7.7 0.5 Adhesion retention rate after oleic acid immersion X % 15 72 72 7 Destruction mode (Na) - - - - Failure mode (Nb) - - - -

[Table 4] Table 4 Comparative example 5 Comparative example 6 Comparative example 7 Comparative example 8 Initial adhesion N/10mm width 12.3 10.2 14.2 0.1 Adhesion over time N/10mm width 20.0 19.8 17.5 0.5 Promote post-adhesive force Na N/10mm width 21.8 23.6 28.0 2.2 Adhesion Nb after immersion in oleic acid N/10mm width 4.4 19.0 22.1 0.1 Adhesion retention rate after oleic acid immersion X N/10mm width 20 81 79 4 Destruction mode (Na) Cohesion Cohesion - - Failure mode (Nb) Cohesion Cohesion Cohesion -

As shown in Tables 2 to 4, the double-sided adhesive tapes of Examples 1 to 4 have high initial adhesion and temporal adhesion, and maintain moderate adhesion after being immersed in oleic acid. Therefore, it is known that the double-sided adhesive tapes are adhesive tapes that have high durability against oil components such as sebum, sweat, food, cosmetics, etc., and have a moderate adhesive force when adhered to an adherend. In addition, if Example 3 is compared with Example 4, the initial adhesion value of Example 4 with the addition of tackifying resin is smaller, because Example 3 exhibits cohesion failure, while Example 4 exhibits substrate failure, so it is judged There was no decrease in adhesion.

On the other hand, the monomer composition of the acrylic copolymer used in Comparative Examples 1 to 4 and 8 (the thickness of each adhesive layer is 19 μm, the substrate A) is different from that of Examples 1 and 2 (the thickness of each adhesive layer) 19μm, base material A) The monomer composition of the acrylic copolymer used. In addition, the weight average molecular weight of the acrylic copolymer used in Comparative Examples 1, 2, 4, and 8 was larger than the weight average molecular weight of the acrylic copolymer used in Examples 1 and 2.

As a result, the double-sided adhesive tapes of Comparative Examples 1 and 8 are compared with the double-sided adhesive tapes of Examples 1 and 2, in terms of initial adhesion, adhesion with time, adhesion after promotion Na, and adhesion after oleic acid immersion Nb , And adhesion retention rate X after immersion in oleic acid is poor.

Compared with the double-sided adhesive tapes of Examples 1 and 2, the double-sided adhesive tape of Comparative Example 2 has inferior initial adhesive force, adhesive force over time, and adhesive force Na after promotion.

The weight average molecular weight of the acrylic polymer of Comparative Example 3 is lower than that of Comparative Example 2. As a result, Comparative Example 3 has several items improved compared to Comparative Example 2. However, the initial adhesion, the adhesion with time, and the adhesion Na after promotion were inferior to those of Examples 1 and 2.

Compared with the double-sided adhesive tapes of Examples 1 and 2, the double-sided adhesive tape of Comparative Example 4 maintains the adhesive force over time, the post-promoting adhesive force Na, the adhesive force after oleic acid immersion Nb, and the adhesive force after oleic acid immersion. The rate X is poor.

The double-sided adhesive tapes of Comparative Examples 5 to 7 (the thickness of each adhesive layer is 50μm, the base material B) are based on the monomer composition of the acrylic copolymer, which is different from Examples 3 and 4 (the thickness of each adhesive layer) 50μm, base material B) The monomer composition of the acrylic copolymer used. In addition, the weight average molecular weight of the acrylic copolymer used in Comparative Examples 5 and 6 is larger than the weight average molecular weight of the acrylic copolymer used in Examples 3 and 4.

As a result, the double-sided adhesive tape of Comparative Example 5 was inferior to the double-sided adhesive tapes of Examples 3 and 4 in terms of initial adhesive force, adhesive force Nb after oleic acid immersion, and adhesive force retention rate X after oleic acid immersion. In addition, the failure modes (Na) and (Nb) are both cohesive failure, and the cohesive force of the adhesive layer is poor.

Compared with the double-sided adhesive tapes of Examples 3 and 4, the double-sided adhesive tape of Comparative Example 6 has poor initial adhesion. In addition, the failure modes (Na) and (Nb) are both cohesive failure, and the cohesive force of the adhesive layer is poor.

Comparative Example 7 is an example in which the adhesive of Comparative Example 3 is used for the substrate B. As a result, in Comparative Example 7, compared with Comparative Example 6, several items were improved. However, the initial adhesion is worse than that of Examples 3 and 4. (Industrial availability)

The adhesive tape of the present invention is quite suitable for, for example, the display panel of small mobile electronic devices such as smart phones, the connection with the frame, and the fixing of parts inside the frame.

Claims (5)

An adhesive tape that uses the following adhesive composition as an adhesive: the adhesive composition contains an acrylic copolymer, and the monomer composition of the acrylic copolymer contains: (meth)acrylic acid alkoxyalkyl ester 20 parts by mass or more and less than 40 parts by mass, 10 parts by mass or more and less than 25 parts by mass of carboxylic acid group-containing (meth)acrylic monomer, 5 parts by mass of alkyl (meth)acrylate represented by the following formula 1 Above and less than 20 parts by mass, and 30 parts by mass or more and less than 50 parts by mass of the alkyl (meth)acrylate represented by the following formula 2 (the total of the above monomers is set to 100 parts by mass); wherein, the above-mentioned acrylic The copolymerization system uses one or both of isocyanate group-containing compounds with more than difunctional groups and glycidyl group-containing compounds with more than difunctional groups as crosslinking agents to form a crosslinked structure with a weight average molecular weight of 20 More than 10,000 and less than 450,000; [化1]

(In formula 1, R ¹ represents CH ₂ =CH- or CH ₂ =C(CH ₃ )-; R ² represents an alkyl group with 1 to 3 carbon atoms, a cyclohexyl group or an isopropyl group); ]

(In formula 2, R ³ represents CH ₂ =CH- or CH ₂ =C(CH ₃ )-; R ⁴ represents an alkyl group with 4 to 12 carbon atoms). The adhesive tape of claim 1, wherein the adhesive composition system further contains an adhesive resin. The adhesive tape of claim 1, wherein the adhesive composition system further contains a silane coupling agent. The adhesive tape of claim 1, wherein the adhesive composition system further contains an antioxidant. The adhesive tape of claim 1, wherein the adhesive tape system further has a substrate, and the adhesive composition is used to form an adhesive layer on one or both sides of the substrate.