ADHESIVE TAPE, METHOD FOR IMMOBILIZING ELECTRONIC DEVICE COMPONENT OR ON-VEHICLE DEVICE COMPONENT, METHOD FOR MANUFACTURING ELECTRONIC DEVICE OR ON-VEHICLE DEVICE

Abstract

The present invention aims to provide an adhesive tape capable of exhibiting excellent adhesion to rough surfaces. The present invention also aims to provide a method for fixing an electronic device component or an in-vehicle device component using the adhesive tape and a method for producing an electronic device or an in-vehicle device. Provided is an adhesive tape including an adhesive layer containing an acrylic copolymer, the acrylic copolymer containing 30% by weight or more of a structural unit derived from n-heptyl (meth)acrylate and 0.01% by weight or more and 30% by weight or less of a structural unit derived from 1-methylheptyl (meth)acrylate.

Claims

1. An adhesive tape comprising an adhesive layer containing an acrylic copolymer, the acrylic copolymer containing 30% by weight or more of a structural unit derived from n-heptyl (meth)acrylate and 0.01% by weight or more and 30% by weight or less of a structural unit derived from 1-methylheptyl (meth)acrylate.

2. The adhesive tape according to claim 1, wherein the acrylic copolymer contains more than 50% by weight of the structural unit derived from n-heptyl (meth)acrylate.

3. The adhesive tape according to claim 2, wherein the acrylic copolymer contains 70% by weight or more of the structural unit derived from n-heptyl (meth)acrylate.

4. The adhesive tape according to claim 1, wherein the acrylic copolymer contains more than 50% by weight of structural units derived from an alkyl (meth)acrylate, including the structural unit derived from n-heptyl (meth)acrylate and the structural unit derived from 1-methylheptyl (meth)acrylate.

5. The adhesive tape according to claim 1, wherein in the acrylic copolymer, an amount of a structural unit derived from a (meth)acrylate containing an alkyl group having a carbon number of 8 or greater is 50% by weight or less.

6. The adhesive tape according to claim 1, wherein the acrylic copolymer further contains a structural unit derived from a monomer having a glass transition temperature of −35° C. or higher.

7. The adhesive tape according to claim 6, wherein the acrylic copolymer contains 5% by weight or more and 70% by weight or less of the structural unit derived from a monomer having a glass transition temperature of −35° C. or higher.

8. The adhesive tape according to claim 1, wherein the acrylic copolymer further contains a structural unit derived from a monomer containing a crosslinkable functional group.

9. The adhesive tape according to claim 8, wherein the acrylic copolymer contains 0.01% by weight or more and 20% by weight or less of the structural unit derived from a monomer containing a crosslinkable functional group.

10. The adhesive tape according to claim 8, wherein the monomer containing a crosslinkable functional group comprises a monomer containing a hydroxy group, and the acrylic copolymer contains 0.01% by weight or more and 20% by weight or less of a structural unit derived from the monomer containing a hydroxy group.

11. The adhesive tape according to claim 1, wherein the acrylic copolymer has a weight average molecular weight of 200,000 or greater and 2,000,000 or less.

12. The adhesive tape according to claim 1, wherein the adhesive layer further contains a tackifier resin.

13. The adhesive tape according to claim 1, wherein the adhesive layer does not contain a surfactant.

14. The adhesive tape according to claim 1, wherein the adhesive layer has a gel fraction of 10% by weight or more and 70% by weight or less.

15. The adhesive tape according to claim 1, wherein the adhesive layer has a bio-derived carbon content of 10% by weight or more.

16. The adhesive tape according to claim 1, used for fixing an electronic device component or an in-vehicle device component.

17. A method for fixing an electronic device component or an in-vehicle device component, comprising fixing an electronic device component or an in-vehicle device component using the adhesive tape according to claim 1.

18. A method for producing an electronic device or an in-vehicle device, comprising the method for fixing an electronic device component or an in-vehicle device component according to claim 17.

Description

DESCRIPTION OF EMBODIMENTS

[0117] The embodiments of the present invention are more specifically described in the following with reference to examples. These examples are not intended to limit the present invention.

Example 1

(1) Production of Acrylic Copolymer

[0118] Ethyl acetate as a polymerization solvent was added into a reaction vessel and bubbled with nitrogen. Subsequently, with nitrogen flowing into the reaction vessel, the reaction vessel was heated to start reflux. A polymerization initiator solution obtained by diluting 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator 10-fold with ethyl acetate was added into the reaction vessel. Subsequently, 30 parts by weight of n-heptyl acrylate (C7), 1 part by weight of 1-methylheptyl acrylate, 63.9 parts by weight of 2-ethylhexyl acrylate (2-EHA, produced by Mitsubishi Chemical Corporation), 5 parts by weight of acrylic acid (AAc, produced by Nippon Shokubai Co., Ltd.), and 0.1 parts by weight of 2-hydroxyethyl acrylate (2-HEA, produced by Osaka Organic Chemical Industry Ltd.) were dripped over two hours. After dripping was complete, the polymerization initiator solution obtained by diluting 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator 10-fold with ethyl acetate was added into the reaction vessel again. Polymerization reaction was performed for four hours to give a solution containing an acrylic copolymer.

[0119] Here, n-heptyl acrylate (C7) was prepared by esterifying n-heptyl alcohol (produced by Tokyo Chemical Industry Co., Ltd.) with acrylic acid (AAc, produced by Nippon Shokubai Co., Ltd.). 1-Methylheptyl acrylate was prepared by esterifying 1-methylheptyl alcohol (produced by Tokyo Chemical Industry Co., Ltd.) and acrylic acid (AAc, produced by Nippon Shokubai Co., Ltd.).

[0120] The obtained acrylic copolymer was diluted 50-fold with tetrahydrofuran (THF). The obtained dilution was filtered through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm) to prepare a measurement sample. This measurement sample was fed to a gel permeation chromatograph (produced by Waters Corporation, 2690 Separations Model) and subjected to GPC measurement at a sample flow rate of 1 mL/min and a column temperature of 40° C. to measure the polystyrene equivalent molecular weight of the acrylic copolymer. Thus, the weight average molecular weight was determined.

(2) Production of Adhesive Tape

[0121] An isocyanate crosslinking agent (produced by Tosoh Corporation, CoronateL-45) was added to the obtained solution containing the acrylic copolymer such that the amount of the solids of the crosslinking agent was 0.5 parts by weight relative to 100 parts by weight of the acrylic copolymer, whereby an adhesive solution was prepared. The adhesive solution was applied to the release-treated surface of a release-treated PET film having a thickness of 75 μm such that the adhesive layer after drying would have a thickness of 50 μm, and then dried at 110° C. for five minutes. This adhesive layer was placed on the release-treated surface of a release-treated PET film having a thickness of 75 μm and left to stand at 40° C. for 48 hours, whereby an adhesive tape (non-support type) was obtained.

(3) Measurement of Gel Fraction of Adhesive Layer

[0122] The release film on one surface of the obtained adhesive tape was removed. The adhesive tape was attached to a PET film having a thickness of 23 μm (produced by Futamura Chemical Co., Ltd., FE2002) and cut to a 20 mm×40 mm flat rectangular shape. The release film on the other surface of the adhesive tape was removed, whereby a specimen was prepared. The weight of the specimen was measured. The specimen was immersed in ethyl acetate at 23° C. for 24 hours, taken out of the ethyl acetate, and dried at 110° C. for 1 hour. The weight of the specimen after drying was measured, and the gel fraction was calculated by the following equation (1).

Gel fraction (% by weight)=100×(W.sub.2−W.sub.0)/(W.sub.2−W.sub.0)  (1)

(W.sub.0: the weight of the substrate (PET film), W.sub.1: the weight of the specimen before immersion, W.sub.2: the weight of the specimen after immersion and drying)

Examples 2 to 11 and Comparative Examples 1 to 7

[0123] An adhesive tape was obtained as in Example 1 except that the type and compounding amount of the acrylic monomers constituting the acrylic copolymer and the compounding amount and type of the tackifier resins and the crosslinking agents were changed as shown in Table 1.

[0124] In Comparative Example 2, n-butyl acrylate (BA, produced by Mitsubishi Chemical Corporation) was used. In Example 7, 10 parts by weight of a terpene phenolic resin A, 10 parts by weight of a polymerized rosin ester resin B, and 10 parts by weight of a hydrogenated rosin ester resin C were used as tackifier resins. The tackifier resins used were the following bio-derived tackifier resins.

[0125] Terpene phenolic resin A (produced by Yasuhara Chemical Co., Ltd., G150, softening point: 150° C., bio-derived carbon content 67% by weight)

[0126] Polymerized rosin ester resin B (hydroxy value: 46, softening point: 152° C., bio-derived carbon content 95% by weight)

[0127] Hydrogenated rosin ester resin C (produced by Arakawa Chemical Industries Ltd., KE359, hydroxy value: 40, softening point: 100° C., bio-derived carbon content 95% by weight)

Examples 12 and 13

[0128] An adhesive tape was obtained as in Example 1 except that the weight average molecular weight of the acrylic copolymer was changed as shown in Table 2.

<Evaluation>

[0129] The adhesive tapes obtained in the examples and the comparative examples were evaluated by the following methods. Tables 1 and 2 show the results.

(1) Peeling Force for Rough Surfaces

[0130] The 180° peeling force of each of the adhesive tapes for water-proof abrasive paper (produced by Noritake Coated Abrasive Co., Ltd., C947H, grain size 360, surface roughness Ra=10.8 μm) as a rough surface was measured in conformity with JIS Z 0237:2009.

[0131] Specifically, first, the back surface of the water-proof abrasive paper was bonded to a SUS304 plate using an adhesive tape for measurement (produced by Sekisui Chemical Co., Ltd., #560). Next, one surface (the side not to be measured) of the adhesive tape was backed with a polyethylene terephthalate film having a thickness of 23 μm (produced by Futamura Chemical Co., Ltd., FE2002) and then the backed adhesive tape was cut to a size of 25 mm wide×75 mm long to prepare a specimen. This specimen was placed on the abrasive surface of the water-proof abrasive paper bonded to the SUS304 plate, with its adhesive layer (the side to be measured) facing the abrasive surface. A 2-kg rubber roller was then moved back and forth once on the specimen at a speed of 300 mm/min to bond the specimen and the abrasive paper. The specimen was then left to stand at 23° C. and a humidity of 50% for 20 minutes to prepare a test sample. The adhesive tape and the SUS plate of the test sample were peeled apart in the 180° direction at a tensile speed of 300 mm/min in conformity with JIS Z 0237:2009 at 23° C. and a humidity of 50%, and the peeling force (N/25 mm) was measured.

[0132] The peeling force for rough surfaces was evaluated as “∘” (Good) when the peeling force was 10 N/25 mm or greater. The peeling force for rough surfaces was evaluated as “x” (Poor) when the peeling force was less than 10 N/25 mm.

[0133] The surface roughness Ra of the water-proof abrasive paper was measured using a laser microscope (produced by KEYENCE, Color 3D Laser Microscope, VK-8710).

(2) Shear Holding Power at High Temperature

[0134] The holding power of the adhesive tapes according to Examples 1, 12, and 13 was measured. Table 2 shows the results. The shear holding power of each adhesive tape at high temperature was measured in conformity with JIS Z 0237:2009.

[0135] Specifically, first, one surface (the side not to be measured) of the adhesive tape was backed with a polyethylene terephthalate film (produced by Futamura Chemical Co., Ltd., FE2002) having a thickness of 23 μm. The adhesive tape was then cut to a size of 25 mm wide×75 mm long to prepare a specimen. This specimen was placed on a SUS304-2B plate (2 mm thick, 50 mm wide, and 80 mm long) with the adhesive layer (the side to be measured) facing the SUS304-2B plate. Then, a 2-kg rubber roller was moved back and forth once on the specimen at a speed of 300 mm/min to bond the specimen to the SUS304-2B plate. The specimen was then left to stand for 20 minutes at 23° C. and a humidity of 50%. Thus, a test sample was produced. This test sample was placed in an environment at 80° C. and a humidity of 50% and left to stand for 15 minutes. A 1-kg weight was then attached to the polyethylene terephthalate film of the test sample such that a load in a shear direction was applied in conformity with JIS Z 0237:2009. One hour after the weight was attached, the amount of slippage of the adhesive layer in the shear direction from the position where it was bonded to the SUS304-2B plate was measured.

[0136] The shear holding power at high temperature was evaluated as “∘” (Good) when the amount of slippage was 0.5 mm or less. The shear holding power at high temperature was evaluated as “Δ” (Fair) when the amount of slippage was greater than 0.5 mm.

TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 8 9 Adhesive Acrylic n-Heptyl acrylate (C7) 30 93.9 94.89 84.9 74.9 64.9 93.9 74 65 layer copolymer 1-Methylheptyl acrylate 1 1 0.01 10 20 30 1 20 20 [parts by n-Butyl acrylate (BA) — — — — — — — — — weight] 2-Ethylhexyl acrylate (2-EHA) 63.9 — — — — — — — — Isobornyl acrylate (IBOA) — — — — — — — — — Acrylic acid (AAc) 5 5 5 5 5 5 5 1 5 2-Hydroxyethyl acrylate (2-HEA) 0.1 0.1 0.1 0.1 0.1 0.1 0.1 5 10 Tackifier resin (TF) [parts by weight] — — — — — — 30 — — Crosslinking agent [parts by weight] 0.5 0.5 0.5 0.5 0.5 0.5 2 0.5 0.5 Weight average molecular weight of 96 112 115 107 105 103 112 102 99 acrylic copolymer (Mw) [×10.sup.4] Gel fraction of adhesive layer [% by weight] 32 35 36 35 34 33 33 47 55 Evaluation Adhesion to N/25 mm 10.2 10.9 10.3 11.3 13.7 10.1 16.2 11.5 10.6 surfaces rough Rating ○ ○ ○ ○ ○ ○ ○ ○ ○ Example Comparative Example 10 11 1 2 3 4 5 6 7 Adhesive Acrylic n-Heptyl acrylate (C7) 55 57 — — 54.9 — 94.9 54.9 — layer copolymer 1-Methylheptyl acrylate 20 1 — — 40 94.9 — 40 10 [parts by n-Butyl acrylate (BA) — — — 94.9 — — — — — weight] 2-Ethylhexyl acrylate (2-EHA) — — 94.9 — — — — — 84.9 Isobornyl acrylate (IBOA) — 40 — — — — — — — Acrylic acid (AAc) 5 1 5 5 5 5 5 5 5 2-Hydroxyethyl acrylate (2-HEA) 20 1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Tackifier resin (TF) [parts by weight] — — — — — — — — — Crosslinking agent [parts by weight] 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Weight average molecular weight of 105 91 92 121 99 101 118 100 78 acrylic copolymer (Mw) [×10.sup.4] Gel fraction of adhesive layer [% by weight] 68 44 31 38 33 32 33 35 31 Evaluation Adhesion to N/25 mm 10.2 12.6 9.3 8.7 9.0 8.9 9.1 8.8 9.1 surfaces rough Rating ○ ○ x x x x x x x

TABLE-US-00002 TABLE 2 Example 1 12 13 Adhesive Acrylic n-Heptyl acrylate (C7) 30 30 30 layer copolymer 1-Methylheptyl 1 1 1 [parts acrylate by weight] n-Butyl acrylate (BA) — — — 2-Ethylhexyl acrylate 63.9 63.9 63.9 (2-EHA) Isobornyl acrylate — — — (IBOA) Acrylic acid (AAc) 5 5 5 2-Hydroxyethyl 0.1 0.1 0.1 acrylate (2-HEA) Tackifier resin (TF) [parts by weight] — — — Crosslinking agent [parts by weight] 0.5 0.5 0.5 Weight average molecular weight of acrylic 96 40 50 copolymer (Mw) [×10.sup.4] Gel fraction of adhesive layer [% by weight] 32 21 24 Evaluation Adhesion to N/25 mm 10.2 11.5 11.2 rough Rating ◯ ◯ ◯ surfaces Shear holding Amount of slippage 0.2 0.7 0.5 power at high [mm] temperature Rating ◯ Δ ◯

INDUSTRIAL APPLICABILITY

[0137] The present invention can provide an adhesive tape capable of exhibiting excellent adhesion to rough surfaces. The present invention can also provide a method for fixing an electronic device component or an in-vehicle device component using the adhesive tape and a method for producing an electronic device or an in-vehicle device.