JPH04266980A - Thermosetting type adhesive and its bonding sheet - Google Patents

Abstract

PURPOSE:To obtain a thermosetting type adhesive or a bonding sheet, improved in processability and bonding operation efficiency and capable of developing sufficient adhesive strength by heat treatment in a short time and carrying out the bonding treatment excellent in balance between peel adhesive strength and adhesive strength under shear. CONSTITUTION:A thermosetting type adhesive containing a graft copolymer having <=0 deg.C glass transition temperature of the backbone chain and 30-150 deg.C glass transition temperature of the side chain, a monomer having at least one radical-reactive unsaturated bond in the molecule and a radical reaction initiator as components. Furthermore, a bonding sheet having a layer composed of the aforementioned thermosetting type adhesive on a support is provided.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a thermosetting adhesive that has excellent processability and adhesive workability, and is capable of performing adhesive treatment with an excellent balance between peel adhesive force and shear adhesive force, and the use of the same. Regarding the adhesive sheet used.

0002

[Prior Art] For the purpose of simplifying work and improving safety and health, a method of adhesion using a pre-formed adhesive sheet is often used instead of the conventional method of applying and drying a liquid adhesive. ing. Conventionally, such adhesive sheets include:
Epoxy adhesive sheets were known. However, in order to develop good adhesive strength, heat treatment at a high temperature for a long time is required, resulting in poor working efficiency and the problem that the adherend deteriorates at high temperatures. There are hot-melt adhesive sheets that can be bonded in a short time, but they have the disadvantage of poor adhesive strength at high temperatures.

On the other hand, an adhesive sheet has also been proposed in which an unsaturated compound layer is laminated on a porous sheet impregnated with a radical reaction initiator (Japanese Patent Publication No. 13425/1983). However, there was a problem in that the adhesive layer (unsaturated compound layer) had high fluidity before curing, resulting in poor processability or bonding workability. Although fluidity can be suppressed by partially crosslinking in advance, in that case, the adhesive properties are reduced and a satisfactory adhesive force is not developed, so that the original purpose is not achieved.

0004

Problem to be Solved by the Invention The present invention provides a thermosetting adhesive that has excellent processability or adhesive workability, and is capable of performing adhesive treatment with an excellent balance between peel adhesive strength and shear adhesive strength. The challenge is to obtain an adhesive sheet.

[0005]

[Means for Solving the Problems] The present invention provides that the main chain has a glass transition temperature of 0°C or lower, and the side chain has a glass transition temperature of 30 to 30°C.
A thermosetting adhesive and a support comprising a graft copolymer at 150°C, a monomer having at least one radically reactive unsaturated bond in the molecule, and a radical reaction initiator, and a support. The present invention provides an adhesive sheet having a layer made of the thermosetting adhesive described above on one or both sides of the adhesive sheet.

[0006]

[Function] By using the above-mentioned graft copolymer, cohesive force can be increased, excessive fluidity can be suppressed, and good processability or adhesion workability such as resistance to blocking can be imparted. Further, by heat treatment, the adhesive is cured in a short time via a radical reaction initiator, and adhesive strength with an excellent balance between peel adhesive strength and shear adhesive strength is developed.

[0007]

[Examples of constituent elements of the invention] The thermosetting adhesive of the present invention is
The component is a graft copolymer whose main chain has a glass transition temperature of 0°C or lower and whose side chain has a glass transition temperature of 30 to 150°C. A graft copolymer that can be preferably used from the viewpoint of processability, adhesive workability, and adhesive properties has a side chain portion with a weight fraction of 1.
~25%.

Examples of graft copolymers include acrylic polymers, polyester polymers, and hydrogenated rubber polymers, and two or more of them may be used in combination if necessary. When the glass transition temperature of the main chain of the graft copolymer exceeds 0° C., it is difficult to develop peel adhesive strength. Furthermore, if the glass transition temperature of the side chain is less than 30°C, the workability during production of the adhesive sheet will be poor, and if it exceeds 150°C, the adhesive properties will deteriorate.

The graft copolymer can be prepared by various methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. There are no particular limitations on the method for preparing the graft copolymer used in the present invention.

The thermosetting adhesive of the present invention contains a monomer having at least one radically reactive unsaturated bond in its molecule. Examples include epoxy acrylates, polyester acrylates, urethane acrylates, and vinyl monomers. Generally, those having a molecular weight of 10,000 or less are used, but are not limited thereto.

Examples of epoxy acrylates include V
R-60, VR-90 (product name, manufactured by Showa Kobunshi Co., Ltd.), 3
Examples include 002A, 3002M (trade name, manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.), and Viscoat #540 (trade name, made by Osaka Organic Chemical Industry Co., Ltd.).

Examples of polyester acrylates include Aronix M-6100, M-6300, M-80
30, M-8060, M-5700 (trade name, manufactured by Toagosei Chemical Industry Co., Ltd.), Viscoat #3700, #700 (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), G-201P (trade name, manufactured by Kyoeisha Yushi Chemical Industry Co., Ltd.) (manufactured by a company).

Examples of urethane acrylates include A
H-600 (trade name, manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.), Viscoat #813 (trade name, made by Osaka Organic Chemical Industry Co., Ltd.), N
Examples include K-ester U-108A (trade name, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.).

Examples of vinyl monomers include acrylates or methacrylates having an alkyl group having 1 to 14 carbon atoms, derivatives thereof, divinyl adipate, vinyl 2-ethylhexanoate, divinylbenzene, triallyl cyanurate, etc. It will be done.

[0015] One or more types of monomers having at least one radically reactive unsaturated bond in the molecule may be used. The amount used is 20 parts by weight per 100 parts by weight of the graft copolymer from the viewpoint of processability or adhesive workability and adhesive properties.
~200 parts by weight is preferred.

The thermosetting adhesive of the present invention contains a radical reaction initiator as a component. The radical reaction initiator participates in the curing reaction between the graft copolymer used in combination and the monomer. The curing reaction can be carried out by heat-treating the thermosetting adhesive. The amount of the radical reaction initiator to be used is preferably 0.2 to 5 parts by weight per 100 parts by weight of the graft copolymer from the viewpoint of adhesive storage stability, workability of curing treatment, and adhesive properties.

One or more of various radical reaction initiators may be used. Examples of radical reaction initiators that can be preferably used include lauroyl peroxide, benzoyl peroxide, and 1,1-bis(t-butylperoxy).
-organic peroxides such as 3,3,5-trimethylcyclohexane, 2,2'-azobisisobutyronitrile, 2,
Examples include azo compounds such as 2-azobis(2-methylbutyronitrile).

Additives commonly used in adhesives and pressure-sensitive adhesives, such as fillers such as glass fiber and metal powder, pigments, colorants, and plasticizers, may be added to the thermosetting adhesive of the present invention. be able to.

The adhesive sheet of the present invention has a layer made of the above-mentioned thermosetting adhesive on one or both sides of a support. The thermosetting adhesive layer may be fixed to the support or may be peelable from the support. The releasable type can be formed, for example, by a method using a support treated with a release agent.

[0020] Appropriate materials such as plastic film, paper, nonwoven fabric, and metal foil may be used as the support. The thickness of the thermosetting adhesive layer provided on the support is 1 to 500μ
m is common, but the thickness is not limited to this and may be any appropriate thickness depending on the purpose of use.

The thermosetting adhesive or adhesive sheet of the present invention can be used for various adhesive applications. The adhesion treatment can be carried out, for example, by providing a layer of a thermosetting adhesive on the adherend and curing it by heating it to a temperature higher than the glass transition temperature of the side chain in the graft copolymer. Note that the layer consisting of the thermosetting adhesive of the present invention can also be provided with adhesive strength such as a pressure-sensitive adhesive.

[0022]

[Effects of the Invention] The thermosetting adhesive or adhesive sheet of the present invention has excellent processability and adhesive workability. Also,
Adhesion treatment with an excellent balance between peel adhesion and shear adhesion can be performed with short heat treatment.

[0023]

[Example] Reference Example 1 In a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer, 100 parts of toluene (parts by weight, same hereinafter) was used as a solvent, 100 parts of styrene, 2 parts of 2-mercaptoacetic acid, 4,4
2 parts of '-azobis-4-cyanovaleric acid was added and polymerized in a nitrogen stream to obtain terminally carboxylated polystyrene. Its weight average molecular weight was 10,000 (as calculated by gel permeation chromatography in terms of polystyrene, hereinafter the same). Next, the terminal carboxylated polystyrene and glycidyl methacrylate were mixed in xylene.
The reaction was carried out in the presence of hydroquinone using tri-n-butylamine as a catalyst to obtain a polystyrene macromonomer having a glass transition temperature of 100°C. Then, ethyl acetate 100
and 50 parts of toluene as a solvent, 70 parts of 2-ethylhexyl acrylate, 20 parts of methyl methacrylate, 2 parts of the above polystyrene macromonomer, 8 parts of acrylic acid, 2
, 0.2 parts of 2'-azobisisobutyronitrile to obtain a solution of an acrylic graft copolymer having a weight average molecular weight of 720,000. The glass transition temperature of the main chain in this graft copolymer is -39°C.

Reference Example 2 Using 80 parts of toluene and 20 parts of methanol as a solvent, 70 parts of butyl acrylate, 15 parts of vinyl acetate, 10 parts of acrylamide, and 5 parts of the polystyrene macromonomer used in Reference Example 1 were mixed with 2,2'-azo Bisisobutyronitrile 0.2
A solution of an acrylic graft copolymer having a weight average molecular weight of 480,000 was obtained. The glass transition temperature of the main chain in this graft copolymer is -31°C.

Reference Example 3 Using 100 parts of ethyl acetate and 50 parts of toluene as a solvent, 50 parts of isoamyl acrylate and 25 parts of isobutyl acrylate
1 part, 5 parts of acrylic acid was polymerized using 0.1 part of 2,2'-azobisisobutyronitrile, and then 0.5 part of benzoyl peroxide was added, and 18 parts of methyl methacrylate,
2 parts of methacrylic acid was dropwise polymerized to give a weight average molecular weight of 63.
A solution of 10,000 acrylic graft copolymers was obtained. The glass transition temperature of the main chain in this graft copolymer is -3
3°C, and that of the side chain is 107°C.

Reference Example 4 9 parts of bisphenol A, 29 parts of isophthalic acid, 22 parts of sebacic acid, 35 parts of 1,3-butanediol, a styrene macromonomer having two hydroxyl groups at one end (
5 parts of macromonomer HS-6 (manufactured by Toagosei Kagaku Kogyo Co., Ltd.) was heated in the presence of a small amount of toluene and polymerized by distilling off the water produced to obtain a graft copolymer with a weight average molecular weight of 80,000. A solution was obtained. The glass transition temperature of the main chain in this graft copolymer is -31°C, and that of the side chain is 100°C.

Reference Example 5 Same as Reference Example 2 except that a butyl acrylate macromonomer having a methacryloyl group at one end (Macromonomer AB-6, manufactured by Toagosei Kagaku Kogyo Co., Ltd.) was used instead of the polystyrene macromonomer. A solution of a graft copolymer having a weight average molecular weight of 420,000 was obtained. The glass transition temperature of the main chain in this graft copolymer is -31°C,
That of the side chain is -55°C.

Reference Example 6 Using 100 parts of ethyl acetate and 50 parts of toluene as a solvent, 50 parts of isoamyl acrylate and 25 parts of isobutyl acrylate
5 parts of acrylic acid, 18 parts of methyl methacrylate, and 2 parts of methacrylic acid were polymerized using 0.2 parts of 2,2'-azobisisobutyronitrile to obtain an acrylic copolymer with a weight average molecular weight of 460,000. A combined solution was obtained.

Example 1 30 parts of polyester acrylate (Aronix M-803) was added to the solution obtained in Reference Example 1 per 100 parts of solid content.
0:20 parts, M-6300: 10 parts) and 0.8 parts of lauroyl peroxide were added to prepare an adhesive solution. Next, apply the above adhesive solution on the separator and heat it for 2 hours at 80℃.
A thermosetting adhesive layer having a thickness of 50 μm was formed by drying for a minute to obtain an adhesive sheet.

Example 2 To the solution obtained in Reference Example 1, 40 parts of epoxy acrylate (3002A), 10 parts of trimethylolpropane triacrylate, and 1.2 parts of benzoyl peroxide were added per 100 parts of the solid content to prepare an adhesive. A solution was prepared, and an adhesive sheet was obtained using the solution according to Example 1.

Example 3 The adhesive sheet obtained in Example 1 was attached to both sides of a 25 μm thick polyester film to obtain an adhesive sheet.

Example 4 The adhesive sheet obtained in Example 1 was attached to both sides of a rayon nonwoven fabric having a basis weight of 14 g/m 2 to obtain an adhesive sheet.

Example 5 To the solution obtained in Reference Example 2, 60 parts of polyester acrylate (M-5700: 40 parts,
G-201P: 20 parts), 20 parts of epoxy acrylate (3002A), and 1 part of 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane to prepare an adhesive solution. An adhesive sheet was obtained according to Example 1 using the following.

Example 6 An adhesive sheet was obtained according to Example 5 except that the solution obtained in Reference Example 3 was used.

Example 7 To the solution obtained in Reference Example 4, 40 parts of epoxy acrylate (VR-90: 25 parts, Viscoat #540: 15 parts), 2,2'-azobisisobutylene, per 100 parts of solid content were added. 1 part lonitrile, 0 diphenylmethane diisocyanate
．． An adhesive solution was prepared by adding 5 parts, and an adhesive sheet was obtained according to Example 1 using the solution.

Comparative Example 1 An adhesive sheet was obtained according to Example 5, except that the solution obtained in Reference Example 5 was used.

Comparative Example 2 An adhesive sheet was obtained according to Example 5, except that the solution obtained in Reference Example 6 was used.

Comparative Example 3 An adhesive sheet was obtained in accordance with Comparative Example 2, except that 0.05 part of tetraglycidyl metaxylene diamine was added.

Evaluation test Shear adhesive strength 0.5 x 20 x 1 using an adhesive sheet of 10 x 10 mm
A pair of 00mm aluminum plates were pasted together using the adhesive strength of the thermosetting adhesive layer, and the weight was 120℃ x 0.5kg/
It was cured under heat and pressure bonding under conditions of cm2 x 2 minutes, and after being left for 2 hours, its shear adhesive strength was examined (tensile speed 10 m).
m/min, 23°C, 65% RH).

[0040] Using an adhesive sheet with peel adhesion strength of 10 x 50 mm, 0.5 x 20 x
100mm aluminum plate and 0.1x20x100m
M stainless steel plates (SUS 304) are pasted together using the adhesive strength of a thermosetting adhesive layer, and the temperature is 120℃ x 0.5K.
Cured under heat and pressure bonding under conditions of g/cm2 x 2 minutes,
After leaving it for a while, its peel adhesion strength was examined (tensile speed 1
0 mm/min, 23°C, 65% RH).

[0041] Workability (adhesive workability) Using two 20 x 40 mm adhesive sheets, their long sides were aligned and the top and bottom were sandwiched between 0.5 x 50 x 50 mm aluminum plates (SUS 304). After placing a load of 1 kg on the sample and leaving it at 40° C. for 1 day, the blocking property of the cross section was examined and evaluated as follows. ○: When cross-section blocking is not observed ×: When cross-section is blocked and cannot be separated cleanly

0042
] The above results are shown in Table 1.

[Table 1]

Claims (2)

[Claims] Claim 1: The main chain has a glass transition temperature of 0°C or lower,
It is characterized by comprising a graft copolymer whose side chain has a glass transition temperature of 30 to 150°C, a monomer having at least one radically reactive unsaturated bond in the molecule, and a radical reaction initiator. Thermosetting adhesive. 2. An adhesive sheet comprising a layer comprising the thermosetting adhesive according to claim 1 on one or both sides of a support.