JP3413285B2 - Epoxy resin composition and film adhesive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent storage stability at room temperature and good handleability at 80 ° C.
In about extremely useful epoxy resin composition as a film-like adhesive of the available low-temperature curing type.

[0002]

2. Description of the Related Art A film adhesive is easier to handle than a two-component adhesive or a one-component paste adhesive and is often excellent in performance, so that it is a honeycomb material in the fields of aircraft and construction materials. It is used for the adhesion of the surface material.
However, it is difficult to balance handling properties (tack, fluidity, etc.) with curing characteristics and storage stability due to the constraint that it must be processed into a film, and there are few materials that satisfy a wide variety of user requirements.

This is not only because the curing property and the storage stability are contradictory to each other, but in order to produce a film adhesive having excellent storage stability, a film is formed at a temperature sufficiently lower than the curing temperature. The difference between the film forming temperature and the temperature handled as an adhesive becomes smaller,
This is because the handling property as a film adhesive is lowered. Further, in the case of a film adhesive having excellent curing characteristics, fluidity during curing is often not sufficiently secured, and as a result, sufficient adhesive characteristics are often not obtained.

In addition, when a high molecular weight epoxy resin is added in order to improve handleability in a material which cures at a relatively low temperature of around 80 ° C., the mobility of the epoxy resin at the curing temperature decreases and the reactivity becomes low. And the curing reaction does not proceed and sufficient adhesive strength cannot be obtained. On the other hand, as a method of ensuring handleability and fluidity, there are a method of adding an inorganic filler to a resin and a method of adding a rubber component. The former lowers the adhesive strength and the latter improves handleability. However, the Tg is lowered and the use temperature of the adhesive is limited. Since these problems have not been solved yet, it has been cured so far at 100 ° C or lower, and further, handleability, storage stability,
No film adhesive having excellent adhesive strength has been developed.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and achieves low-temperature curing type usable at 80 ° C. by satisfying both curing characteristics at low temperature, handleability, storage stability and adhesive strength. in in which the adhesive material is an object to provide a very useful epoxy resin composition as a film-like adhesive that can be used in the vicinity of the curing temperature.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have devised a structure of an epoxy resin composition serving as a base as well as optimizing a structure and a compounding amount of a curing agent. It has been found that the above problems can be solved by doing so. That is, the present invention relates to an epoxy resin (A) containing a non-crosslinked thermoplastic elastomer component.
100 parts by weight of a resin composition containing 0 to 60 parts by weight, 5 to 40 parts by weight of an epoxy resin (B) containing a crosslinked rubber component, and 20 to 70 parts by weight of a solid epoxy resin (C) having a softening point of 50 ° C. or higher. 3 to 15 parts by weight of a urea-based epoxy resin curing agent (D) and 3 to 20 parts by weight of a latent curing catalyst (E) which is stable at 40 ° C. and can be activated at a temperature of 80 ° C. or less. The epoxy resin composition solves the above problems.

An important constituent of the present invention is the combined use of an epoxy resin containing a non-crosslinked thermoplastic elastomer component (A) and an epoxy resin (B) containing a crosslinked rubber component. When an epoxy resin containing a non-crosslinked thermoplastic elastomer component is used as a main component, addition of the required amount of the thermoplastic elastomer component to obtain a certain degree of adhesive strength results in a marked decrease in Tg. On the other hand, when an epoxy resin containing a crosslinked rubber component is used as a main component, the Tg as much as that of a thermoplastic elastomer is not significantly lowered, but sufficient adhesive strength cannot be obtained. As a result of intensive studies, the ratio of the epoxy resin containing the non-crosslinked thermoplastic elastomer component and the epoxy resin containing the crosslinked rubber component is preferably 30/70 to 80/20, more preferably 40/60 to 70/30. It was found that it is possible to obtain an epoxy resin composition having a well-balanced adhesive strength and heat resistance when used in combination at a ratio of 1) and reached the present invention.

The epoxy resin containing the non-crosslinked thermoplastic elastomer as the component (A) is a non-crosslinked thermoplastic elastomer such as a butadiene / acrylonitrile copolymer having a terminal group capable of reacting with the epoxy resin and a styrene / butadiene elastomer. It is obtained by dispersing and reacting a plastic elastomer component in an epoxy resin, and it is preferable from the viewpoint of performance stability that the terminal groups of these elastomer components partially react with the epoxy resin.

The epoxy resin containing the crosslinked rubber as the component (B) is obtained by dispersing a crosslinked rubber component such as butadiene rubber and acrylic rubber in the epoxy resin and then reacting them. These rubber components are used. Similarly to the above-mentioned thermoplastic elastomer component, it is preferable that the terminal group partially reacts with the epoxy resin.

The epoxy resin which is reacted with the non-crosslinked thermoplastic elastomer component or the crosslinked rubber component of the components (A) and (B) is not particularly limited, but is a liquid bisphenol A type epoxy resin or bisphenol F type epoxy resin, bisphenol. The S-type epoxy resin and the novolak-type epoxy resin are particularly preferable from the viewpoint of handleability. An epoxy resin containing such a non-crosslinked thermoplastic elastomer or a crosslinked rubber is a non-crosslinked elastomer component or crosslinked rubber component having an end group capable of reacting with the epoxy resin and the epoxy resin at a temperature of 100 to 180 ° C. It can be easily obtained by adding a catalyst if necessary and reacting it, but it is possible to use a commercially available resin.

As a modified epoxy resin containing a non-crosslinked thermoplastic elastomer that is commercially available or available as a sample, Epiclon T manufactured by Dainippon Ink and Chemicals, Inc.
SR-960, TSR-930, TSR-601, Epicoat YL-6308, Y of Yuka Shell Epoxy Co., Ltd.
L6347 can be illustrated. Examples of the crosslinked rubber-modified epoxy resin include CX-MN series of Nippon Shokubai Co., Ltd. and crosslinked rubber-modified epoxy resin of Nippon Synthetic Rubber Co., Ltd.

The ratio of the elastomer component and the crosslinked rubber component in these components (A) or (B) is 5 to 50 in each case.
The weight% is suitable, and if necessary, a commercially available modified resin may be diluted with an epoxy resin containing no elastomer component or crosslinked rubber component. Further, the ratio of the elastomer component and the crosslinked rubber component in the epoxy resin component in the present invention is appropriately 3 to 30% by weight,
Weight percent is more preferred.

As the component (C) in the present invention, an epoxy resin having a softening point of 50 ° C. or higher is used. By using such an epoxy resin, it becomes possible to control the handleability and fluidity of the entire resin composition without sacrificing the curing characteristics at low temperatures. When the softening point of the epoxy resin as the component (C) is less than 50 ° C., it is difficult to control the handleability of the entire composition at room temperature, which is not preferable.

The epoxy resin used as the component (C) is 1
Although it may be of any kind, two or more kinds of epoxy resins may be mixed and used as required. At this time, the softening points of all the epoxy resins to be mixed do not have to be 50 ° C. or higher, and even if the epoxy resin to be mixed contains an epoxy resin having a softening point of 50 ° C. or lower, the epoxy used as the component (C) It does not matter if the softening point of the resin composition is 50 ° C. or higher. Further, the epoxy equivalent of the entire component (C) is
Considering curability, 200 to 650 g / eq is preferable. Particularly preferable epoxy equivalent is 250 to 500 g /
It is in the range of eq.

Examples of the epoxy resin usable as the component (C) include high molecular weight bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, and the like. It is not limited to. The following are examples of particularly preferable epoxy resins. Dainippon Ink and Chemicals, Inc .: EXA-1514 [Epoxy equivalent = 300 g / eq. , Softening point = 75 ° C.] Dainippon Ink and Chemicals, Inc .: HP-4032H [epoxy equivalent = 250 g / eq. , Softening point = 70 ° C.] Dainippon Ink and Chemicals, Inc .: EPICLON 152 [epoxy equivalent = 360 g / eq. , Softening point = 60 ° C.] Dainippon Ink and Chemicals, Inc .: EXA-1857 [Epoxy equivalent = 250 g / eq. , Softening point = 80 ° C.] Nippon Kayaku (Ltd.): EBPS-300 [epoxy equivalent = 260 g / eq. , Softening point = 65 ° C.] Dainippon Ink and Chemicals, Inc .: LS-120 [Epoxy equivalent = 335 g / eq. , Softening point = 80 ° C.] Oiled shell epoxy: Ep-1001 [Epoxy equivalent = 450 g / eq. , Softening point = 64 ℃]

The base epoxy resin in the epoxy resin composition of the present invention contains the above-mentioned three components as essential components, and the ratio thereof is 20 to 60% by weight of the component (A) and that of the component (B). 5-40% by weight, component (C) is 20
Is about 70% by weight. When the amount of the component (A) is less than 20% by weight, sufficient adhesive properties cannot be obtained, and when it exceeds 60% by weight, the adhesive strength is lowered and the Tg is remarkably lowered. (B)
If the amount of the component is less than 5% by weight, a synergistic effect with respect to the component (A) cannot be obtained and sufficient adhesive strength cannot be obtained. (B) component is 4
If it exceeds 0% by weight, not only the synergistic effect with respect to the added amount decreases but also the adhesive strength decreases. (C) component is 2
If it is less than 0% by weight, the handleability of the resin composition is poor, and 7
If it exceeds 0% by weight, the mobility of the resin composition decreases and
Curability at 0 ° C deteriorates.

The base epoxy resin in the present invention contains the components (A), (B) and (C) as essential components, but other epoxy resins may be used in combination. As the other epoxy resin, it is possible to use an epoxy resin such as an bisphenol A type epoxy resin which is not modified with a crosslinked rubber, a bisphenol F type epoxy resin or a glycidyl amine type epoxy resin. Although it can be appropriately used according to the purpose, its ratio is preferably within 30% of the whole epoxy resin composition in the present invention.

As the curing component in the present invention, a urea type epoxy resin curing agent (D) and a latent curing catalyst (E) are used in combination. As the urea-based epoxy resin curing agent (D), those represented by the following structural formulas [1] and [2] can be exemplified.

[0019]

[Chemical 2]

The latent hardener (E) which is stable at 40 ° C. and can be activated at a temperature of 80 ° C. or lower is stable at 40 ° C. among latent hardeners such as microcapsule type and amine adduct type. What can be activated at a temperature of 80 ° C. or lower is used. Commercially available latent hardeners that meet these conditions alone are PN of Ajinomoto Co., Inc.
-23, HX-3721, HX-372 of Asahi Kasei Corporation
2, H3615, 4003, 4070 of ACR Co. can be exemplified. These may be used alone or in combination of two or more.

The mixing ratio of these curing agents is 3 to 15 parts by weight of (D) and (E) based on 100 parts by weight of the epoxy resin composition (A) + (B) + (C) as the base. 3 to 20
Parts by weight. If the amount used is less than this range, the curing reaction will not proceed sufficiently when it is cured at 80 ° C, and the adhesive strength will not be obtained. Moreover, if the amount of use exceeds this range, the curing characteristics will reach a ceiling and storage will not be possible. Stability and adhesive strength are reduced, which is not preferable. A more preferable amount of the curing agent system is 5 to 10 parts by weight of (D) and 5 to 15 parts by weight of (E).

The use of the component (D) and the component (E) together is the second important requirement of the present invention. If the curing catalyst is simply cured at 80 ° C., even if the latent curing catalyst is used alone, it is possible if the epoxy equivalent is sufficiently used, but sufficient strength cannot be obtained in terms of adhesive strength. On the other hand, when the urea-based epoxy resin curing agent is used in combination, sufficient adhesive strength can be obtained even with a smaller amount of the curing agent used. The mechanism of this combined curing has not been fully clarified yet, but it is presumed that the crosslinked structure formed by the combined use of the curing agents is different from that of the latent catalyst alone.

Further, a promoter may be added to the above epoxy resin curing agent system. In particular, the aromatic amine compound can accelerate the curing reaction when used in combination with the latent curing agent. Examples of the amine compound acting as a cocatalyst include aromatic diamines such as metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and diaminodiethyldiphenylmethane, but are not limited thereto.

In the epoxy resin composition of the present invention, in addition to the above components, fillers such as calcium carbonate and talc, flame retardants, pigments and the like can be appropriately used according to the purpose.
Further, when used as a film adhesive, glass, polyester, nylon or other non-woven fabric, woven material or the like used as a carrier material may of course be contained.

[0025]

EXAMPLES The present invention will be described in more detail by way of examples. All parts in the examples are parts by weight, and the abbreviations used are as follows. TSR960; a reaction product of a carboxyl group-terminated butadiene / acrylonitrile copolymer and a liquid epoxy resin.
Elastomer content = 10% (Dainippon Ink and Chemicals) TSR601; same as above Estimated elastomer content = 50%
(Dainippon Ink and Chemicals) YL6308; reaction product of styrene / butadiene elastomer and bisphenol A type liquid epoxy resin. Estimated elastomer content = 10% (Okaka Shell Epoxy Co., Ltd.) XER; reaction product of butadiene-based rubber having a crosslinked structure and bisphenol A type liquid epoxy resin. Estimated crosslinked rubber content = 20% (Japan Synthetic Rubber) CX-MN; CX-77, a reaction product of an acrylic rubber having a crosslinked structure and a bisphenol A type liquid epoxy resin.
Estimated crosslinked rubber content = 20% (Nippon Shokubai Co., Ltd.) CX-MN; CX-204, a reaction product of an acrylic rubber having a crosslinked structure and a bisphenol A type solid epoxy resin. Estimated cross-linked rubber content = 14% (Nippon Shokubai Co., Ltd.) Ep828; Epicoat 828 bisphenol A type epoxy resin (Oilized Shell Epoxy Co., Ltd.) Ep807; Epicoat 828 bisphenol F type epoxy resin (Oyuka Shell Epoxy Co., Ltd.) ) N740; EPICLON N-740 phenol novolac type epoxy resin, semi-solid (Dainippon Ink and Chemicals) Ep1001; Epicoat 1001 solid epoxy resin,
Softening point = 70 ° C., epoxy equivalent = 480 g / eq (Okaka Shell Epoxy Co., Ltd.) EXA1514; Bisphenol S type epoxy resin, softening point = 75 ° C. Epoxy equivalent = 300 g / eq (Dainippon Ink and Chemicals Incorporated) 152; EPICLON 152, brominated epoxy resin, softening point = 60 ° C., epoxy equivalent = 360 g / eq
(Dainippon Ink and Chemicals) LS-120; solid epoxy resin, softening point = 77 ° C. (Dainippon Ink and Chemicals) PN-23; amine adduct type latent curing agent (Ajinomoto) HX-3722; microcapsule type latent Hardener (Asahi Kasei Co., Ltd.) Aerosil; Aerosil # 300, fine powder silica (Japan Aerosil)

Example 1 30 parts of TSR960 as the component (A), 20 parts of XER as the component (B), and EXA-151 as the component (C).
4, Ep1001 20 parts each and Ep828 10 parts premixed resin was mixed at 140 ° C. and then cooled to 50 ° C.,
5 parts of PDMU, 10 parts of HX3722, and 2 parts of Aerosil were added and mixed with stirring until uniform to obtain an epoxy resin composition of the present invention. Then, a film having a thickness of 150 μm was prepared from this epoxy resin composition,
The polyethylene nonwoven fabric of g / m ² was laminated to form a film-like adhesive, and the handling property and the adhesive strength were evaluated.
Curing was carried out at 80 ° C. for 3 hours. The results are shown below. Evaluation results Handleability ○ (Good) Storage stability 3 weeks Tensile shear strength 183 kg / cm ²

[Example 2] The components of the epoxy resin and the curing agent used and the compounding ratios thereof were changed as shown in Table 1 and evaluated in the same manner as in Example 1. The evaluation results are also shown in Table 1. ○ in the column of handleability in Table 1
The mark means good.

[0028]

[Table 1]

[Comparative Examples 1 to 8] Epoxy resin components used and their compounding ratios were changed as shown in Table 2 and evaluated in the same manner as in Example 1. The evaluation results are also shown in Table 2. In the column of handleability in Table 2, Δ indicates a little defective, and X indicates a defective. In Comparative Example 1, the handleability and storage stability were good, but the adhesive strength was insufficient due to the low rubber content. In Comparative Examples 2 and 6, tackiness was manageable and manageability was good, and storage stability was good, but resin flow during curing was large, resulting in insufficient adhesive strength. In Comparative Example 3, the tack was tight and it was manageable, and the storage stability was good, but it did not cure under the curing conditions of 80 ° C. * 3 hours. The compositions of Comparative Examples 4, 5, 7, and 8 were too tacky at room temperature and were difficult to handle as a film. It was unsuitable as a film adhesive.

[0030]

[Table 2]

[0031]

The epoxy resin composition of the present invention has a temperature of 80 ° C.
It cures below, and is excellent in handleability, storage stability and adhesive strength, and is extremely useful as a film adhesive.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-7-157534 (JP, A) JP-A-60-141712 (JP, A) JP-A-59-215313 (JP, A) JP-A-58- 47051 (JP, A) JP-A-4-136083 (JP, A) JP-A-2-222444 (JP, A) JP-A-7-157535 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 59/00-59/72 C08L 63/00-63/10 C09J 163/00-163/10

Claims (7)

(57) [Claims] 1. An epoxy resin (A) containing a non-crosslinked thermoplastic elastomer component, 20 to 60 parts by weight, an epoxy resin (B) containing a crosslinked rubber component, 5 to 40 parts by weight, and a softening point of 50. Solid epoxy resin (C) above ℃
To 100 parts by weight of a resin composition containing 20 to 70 parts by weight, 3 to 15 parts by weight of a urea-based epoxy resin curing agent (D) and a latent curing catalyst that is stable at 40 ° C. and can be activated at a temperature of 80 ° C. or less. (E) An epoxy resin composition containing 3 to 20 parts by weight. 2. An elastomer component obtained by dispersing and reacting a butadiene / acrylonitrile copolymer or a styrene / butadiene elastomer in an epoxy resin (A) containing a non-crosslinked thermoplastic elastomer component. The epoxy resin composition according to claim 1, which is an epoxy resin in which an end group and an epoxy resin are partially reacted. 3. The epoxy resin (B) containing a crosslinked rubber component is obtained by dispersing a butadiene-based crosslinked rubber or an acrylic crosslinked rubber in an epoxy resin and reacting the epoxy resin (B). The epoxy resin composition according to claim 1 or 2, which is an epoxy resin that is reactive. 4. The epoxy resin composition according to claim 1, 2 or 3, wherein the solid epoxy resin (C) having a softening point of 50 ° C. or higher has an epoxy equivalent of 200 to 650 g / eq . 5. A urea-based epoxy resin curing agent (D) is
A contract which is a compound represented by the structural formula [1] or [2]
The epoxy resin composition according to any one of claims 1 to 4. [Chemical 1] 6. A film adhesive comprising the epoxy resin composition according to any one of claims 1 to 5 . 7. A non-woven fabric comprising polyethylene.
6. The film adhesive according to 6.