Radical-curable adhesive composition and adhesive

Abstract

A radical-curable adhesive composition containing a rubber (a) having one or more (meth)acryloyl groups within a single molecular chain, a polymerizable monomer (b) having both an epoxy group and a (meth)acryloyloxy group in the molecule, and a radical polymerization initiator (c). The rubber (a) is preferably a polymer of a monomer containing at least acrylonitrile.

Claims

1. A radical-curable adhesive composition comprising: a rubber (a) having one or more (meth)acryloyl groups within a single molecular chain, a polymerizable monomer (b) having both an epoxy group and a (meth)acryloyloxy group in each molecule, a radical polymerization initiator (c), a polymerizable monomer (d) other than the polymerizable monomer (b) and excluding (meth)acrylic acid, and a vinyl ester compound (e), wherein the vinyl ester compound (e) is one or more compounds selected from the group consisting of bisphenol vinyl ester resins and novolak vinyl ester resins.

2. The radical-curable adhesive composition according to claim 1, wherein the rubber (a) is a polymer of a monomer comprising at least acrylonitrile.

3. The radical-curable adhesive composition according to claim 1, wherein the main chain of the rubber (a) is a copolymer of acrylonitrile and butadiene.

4. The radical-curable adhesive composition according to claim 1, wherein the polymerizable monomer (b) comprises glycidyl (meth)acrylate.

5. The radical-curable adhesive composition according to claim 1, wherein a total amount of the polymerizable monomer (b) and the polymerizable monomer (d) other than the polymerizable monomer (b) and excluding (meth)acrylic acid is from 20 to 200 parts by mass per 100 parts by mass of the rubber (a).

6. The radical-curable adhesive composition according to claim 1, wherein an amount of the polymerizable monomer (b) is from 10 to 100 parts by mass per 100 parts by mass of a total amount of the polymerizable monomer (b) and the polymerizable monomer (d) other than the polymerizable monomer (b) and excluding (meth)acrylic acid.

7. The radical-curable adhesive composition according to claim 1, wherein a total amount of the rubber (a) and the vinyl ester compound (e) is from 105 to 200 parts by mass per 100 parts by mass of the rubber (a).

8. The radical-curable adhesive composition according to claim 1, further comprising an inorganic filler (f).

9. The radical-curable adhesive composition according to claim 8, comprising 3 to 1,000 parts by mass of the inorganic filler (f) per 100 parts by mass of a total amount of the rubber (a), the polymerizable monomer (b), the radical polymerization initiator (c), the polymerizable monomer (d) other than the polymerizable monomer (b) and excluding (meth)acrylic acid, and the vinyl ester compound (e).

10. The radical-curable adhesive composition according to claim 1, wherein a cured product of the adhesive composition has insulating properties.

11. An adhesive comprising the radical-curable adhesive composition according to claim 1.

12. An electrical or electronic component in which a component has been bonded and/or encapsulated using a cured product of the radical-curable adhesive composition according to claim 1.

13. A transportation device in which a component has been bonded using a cured product of the radical-curable adhesive composition according to claim 1.

Description

EXAMPLES

(1) The present invention is described below in further detail using a series of examples and comparative examples. However, the present invention is in no way limited by the following examples.

(2) [Preparation of Adhesive Compositions]

(3) Using the method described below, adhesive compositions of Examples 1 to 8 and Comparative Examples 1 to 6 were prepared containing the materials shown in Table 1 in the mass ratios shown in Table 2 and Table 3.

(4) The numerical values shown for the components (a) to (f) in Table 2 and Table 3 represent mass (g) values.

(5) Moreover, Table 2 and Table 3 also show the total amount (parts by mass) of the component (b) and the component (d) per 100 parts by mass of the component (a), the amount (parts by mass) of the component (b) per 100 parts by mass of the total of the component (b) and the component (d), the total amount (parts by mass) of the component (a) and the component (e) per 100 parts by mass of the component (a), the amount (parts by mass) of the component (c) per 100 parts by mass of the total of the components (a), (b), (d) and (e), the amount (parts by mass) of the component (f) per 100 parts by mass of the total of the components (a) to (e), and the amount (parts by mass) of the thixotropic agent per 100 parts by mass of the total of the components (a) to (f).

(6) TABLE-US-00001 TABLE 1 Name Manufacturer Product name • remarks Acrylate-modified rubber Showa Denko K.K. RIPOXY EFN-1000 (molecular weight: 3400), main chain is an acrylonitrile- butadiene copolymer having terminals modified with (meth)acrylate, liquid at 25° C., viscosity at 27° C.: 500 Pa .Math. s Bisphenol A vinyl ester resin Showa Denko K.K. RIPOXY VR-77 Phenol novolac vinyl ester resin Showa Denko K.K. RIPOXY H-600 Glycidyl methacrylate Showa Denko K.K. BLENMER G Acrylonitrile Showa Denko K.K. Acrylonitrile Ethylene glycol dimethacrylate Kyoeisha Chemical Co., Ltd. LIGHT ESTER EG Isobornyl methacrylate Kyoeisha Chemical Co., Ltd. LIGHT ESTER IBX Isobornyl acrylate Kyoeisha Chemical Co., Ltd. LIGHT ESTER IBXA Curing agent 1 NOF Corporation PERHEXA HC: 1,1-di(t- hexylperoxy)cyclohexane (one-hour half-life temperature: 107° C.) Curing agent 2 NOF Corporation PERBUTYL O: t-butyl peroxy-2- ethylhexanoate (one-hour half-life temperature: 92° C.) Silane coupling agent Shoko High Polymer Co., SCA-503 Ltd. Glass fiber Central Glass Co., Ltd. Milled fiber Glass flakes NSG Group Glass flakes RCF-015 Hydrous magnesium silicate Fuji Talc Industrial Co., Ltd. Talc MS410 Thixotropic agent Cabot Corporation CAB-O-SIL TS-720 fumed silica Additive (silane coupling agent) Shin-Etsu Chemical Co., Ltd. KBM-503 Methacrylic acid Kuraray Corporation Methacrylic acid

(7) TABLE-US-00002 TABLE 2 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Component Name ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 8 (a) Acrylate-modified 70 70 70 70 70 60 60 60 rubber (g) (b) Glycidyl 30 30 20 20 20 30 30 30 methacrylate (g) (c) Curing agent 1 (g) 2 2 2 2 2 2 2 Curing agent 2 (g) 2 (d) Acrylonitrile (g) Ethylene glycol 10 10 10 dimethacrylate (g) Isobornyl 10 methacrylate (g) Isobornyl acrylate (g) (e) Bisphenol A vinyl 10 ester resin (g) Phenol novolac 10 vinyl ester resin (g) (f) Glass fiber (g) 30 30 30 30 30 Glass flakes (g) 40 40 40 40 Hydrous 30 30 30 30 70 magnesium silicate (g) Thixotropic agent (g) 3 5 3 3 2 Additive (silane coupling 1 1 1 1 1 agent) (g) Methacrylic acid (g) Total amount (parts by mass) 43 43 43 43 43 50 50 67 of (b) and (d) per 100 parts by mass of (a) Amount (parts by mass) of (b) 100 100 67 67 67 100 100 75 per 100 parts by mass of total amount of (b) and (d) Total amount (parts by mass) 100 100 100 100 100 117 117 100 of (a) and (e) per 100 parts by mass of (a) Amount (parts by mass) of (c) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 per 100 parts by mass of (a) + (b) + (d) + (e) Amount (parts by mass) of (f) 0 0 0 98 98 98 98 98 per 100 parts by mass of (a) to (e) Amount (parts by mass) of 0.0 0.0 0.0 1.5 2.5 1.5 1.5 1.0 thixotropic agent per 100 parts by mass of (a) to (f)

(8) TABLE-US-00003 TABLE 3 Compar- Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative ative Exam- Exam- Exam- Exam- Exam- Exam- Component Name ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 (a) Acrylate-modified 70 70 60 70 rubber (g) (b) Glycidyl 30 30 methacrylate (g) (c) Curing agent 1 (g) 2 2 2 2 2 Curing agent 2 (g) 2 (d) Acrylonitrile (g) 30 Ethylene glycol 30 dimethacrylate (g) Isobornyl methacrylate (g) Isobornyl 40 acrylate (g) (e) Bisphenol A vinyl 70 ester resin (g) Phenol novolac 70 vinyl ester resin (g) (f) Glass fiber (g) Glass flakes (g) Hydrous magnesium silicate (g) Thixotropic agent (g) 2 Additive (silane coupling agent) (g) Methacrylic acid (g) 20 Total amount (parts by mass) 43 43 67 0 — — of (b) and (d) per 100 parts by mass of (a) Amount (parts by mass) of (b) 0 0 0 — 100 100 per 100 parts by mass of total amount of (b) and (d) Total amount (parts by mass) 100 100 100 100 — — of (a) and (e) per 100 parts by mass of (a) Amount (parts by mass) of (c) 2.0 2.0 2.0 2.9 2.0 2.0 per 100 parts by mass of (a) + (b) + (d) + (e) Amount (parts by mass) of (f) 0 0 0 0 0 0 per 100 parts by mass of (a) to (e) Amount (parts by mass) of 2.0 0.0 0.0 0.0 0.0 0.0 thixotropic agent per 100 parts by mass of (a) to (f)

Examples 1 to 3, Comparative Examples 2, 3, 5 and 6

(9) The components (a) to (e) were placed in disposable cups in the mass ratios shown in Table 2 and Table 3, and a Disper (manufactured by Primix Corporation) was used to mix the components for 10 minutes at 25° C. thus obtaining a series of adhesive compositions.

Examples 4 to 8, Comparative Example 1

(10) The components (a) to (e) were placed in disposable cups in the mass ratios shown in Table 2 and Table 3, and a Disper (manufactured by Primix Corporation) was used to mix the components for 10 minutes at 25° C., thus obtaining a series of mixtures. The component (f), the thixotropic agent and the silane coupling agent were then added to these mixtures in the mass ratios shown in Table 2 and Table 3, and the Disper was used to performed mixing for 10 minutes at 25° C., thus obtaining a series of adhesive compositions.

Comparative Example 4

(11) The component (a), the component (c) and methacrylic acid were placed in a disposable cup in the mass ratio shown in Table 3, and a Disper (manufactured by Primix Corporation) was used to mix the components for 10 minutes at 25° C., thus obtaining an adhesive composition.

(12) Cured products of the adhesive compositions of Examples 1 to 8 and Comparative Examples 1 to 6 obtained in the manner described above were measured for insulation resistance and adhesive strength using the methods described below.

(13) <Insulation Resistance Measurement>

(14) A 2 mm spacer was inserted between two glass substrates to which a PET film had been adhered, the adhesive composition was injected into the 2 mm space, and the adhesive composition was cured by heating for 30 minutes in a 150° C. thermostatic chamber, thus forming a plate. A circular test piece for measuring insulation resistance having a diameter of about 100 mm and a thickness of 2 mm was prepared from the above molded plate. Based on the test for “5.13 Resistivity” disclosed in Japanese Industrial Standard JIS K-6911 “Testing Methods for Thermosetting Plastics”, the insulation resistance of the cured product (test piece) of each adhesive composition was measured.

(15) The results of measuring the insulation resistance in this manner revealed that the insulation resistance of the cured products of the adhesive compositions of Examples 1 to 8 and Comparative Examples 1 to 6 were within a range from 1×10.sup.13 Ωcm.sup.2 to 1×10.sup.16 Ωcm.sup.2, and exhibited high insulation resistance.

(16) <Adhesive Strength Measurement>

(17) Using the method described below, a test piece for measuring the adhesive strength was prepared from each of the materials described below, and the adhesive strength of the cured product of each adhesive composition was measured based on Japanese Industrial Standard JIS K-6850: 1999 “Adhesives—Determination of tensile lap-shear strength of rigid-to-rigid bonded assemblies”.

(18) In the adhesive strength measurement, the test speed was set to 5 mm/min, and the temperature of the test environment was set to either 23° C. or 200° C. When nylon 66 was used as the material for the test piece, the temperature of the test environment was set to either 23° C. or 140° C. The value obtained by dividing the maximum stress by the adhesion surface area was recorded as the adhesive strength (MPa). The results of the measurements are shown in Table 4 and Table 5.

(19) The materials used for the test pieces were sheets of 2 mm×25 mm×100 mm formed from iron (rolled steel for general-purpose structures, SS400, no surface treatment), aluminum (5000 series alloy, A5052, no surface treatment), polyphenylene sulfide (PPS) (a molded item of Susteel GS 40-11, manufactured by Tosoh Corporation, no surface treatment), or nylon 66 (N66, manufactured by Toray Plastics Precision Co., Ltd., no surface treatment).

(20) The adhesive composition was applied to the bonding surface of one test piece to form a coating film, and the bonding surface of the other test piece was then superimposed on the first test piece with the coating film disposed therebetween. Subsequently, the adhesive composition was cured using the method described below to prepare a test piece for measuring the adhesive strength. The thickness of the coating film following curing (the thickness of the cured product) was 0.1 to 0.2 mm.

(21) In Examples 1 and 3 to 8, and Comparative Examples 2 to 6, the adhesive composition was cured by heating for 30 minutes in a 150° C. thermostatic chamber.

(22) In Example 2 and Comparative Example 1, the adhesive composition was cured by heating for 30 minutes in a 120° C. oven.

(23) TABLE-US-00004 TABLE 4 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Test ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 8 Adhesive  23° C. Iron 18 20 13 12 16 20 14 16 strength Aluminum 14 15 10 11 14 16 1.3 13 (MPa) PPS 6.0 3.7 5.6 7.2 3.1 5.6 4.6 2.9 Nylon 3.0 4.6 5.2 6.9 3.0 3.3 3.8 4.1 200° C. Iron 1.5 1.0 1.9 3.4 4.6 2.4 1.5 2.5 Aluminum 1.4 1.2 1.9 2.7 3.4 3.3 1.7 3.0 PPS 1.6 1.0 1.4 1.6 1.1 1.7 1.4 1.8 140° C. Nylon 1.0 1.4 1.4 1.1 1.2 1.6 1.4 1.5

(24) TABLE-US-00005 TABLE 5 Compar- Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative ative Exam- Exam- Exam- Exam- Exam- Exam- Test ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 Adhesive  23° C. Iron 0.2 0.1 18 18 0.6 1.1 strength Aluminum 0.1 0.1 19 15 0.3 1.2 (MPa) PPS 3.6 0.0 0.7 7.0 0.3 0.5 Nylon 1.6 0.1 0.6 5.0 0.1 0.0 200° C. Iron 0.0 0.0 1.2 1.7 0.1 0.1 Aluminum — 0.0 1.3 1.0 0.0 0.1 PPS 0.2 — 0.1 0.3 — — 140° C. Nylon 0.1 — — 0.0 — — — indicates that detachment occurred during heating of the test piece

(25) As shown in Table 4, the cured products of the adhesive compositions of Examples 1 to 8 had good adhesive strength to iron, aluminum and polyphenylene sulfide (PPS) at both 23° C. and high-temperature conditions of 200° C. Further, the cured products of the adhesive compositions of Examples 1 to 8 also had good adhesive strength to nylon 66 at both 23° C. and high-temperature conditions of 140° C.

(26) In contrast, as shown in Table 5, Comparative Examples 1 to 6 did not have satisfactory adhesive strength to all of iron, aluminum and PPS under high-temperature conditions of 200° C., as well as nylon under high-temperature conditions of 140° C.

(27) In particular, in Comparative Example 1, when aluminum was used for the test pieces, detachment occurred during heating when attempting to measure the adhesive strength at 200° C. Further, in Comparative Examples 2, 3, 5 and 6, when polyphenylene sulfide (PPS) was used for the test pieces, detachment occurred during heating when attempting to measure the adhesive strength at 200° C. Furthermore, in Comparative Examples 2, 3, 5 and 6, when nylon 66 was used for the test pieces, detachment occurred during heating when attempting to measure the adhesive strength at 140° C. Moreover, in Comparative Example 4, when nylon 66 was used for the test pieces, the adhesive strength at 140° C. was 0.0 MPa.