GB2232158A - Two-pack epoxy resin compositions - Google Patents

Description

1 - TWO-PACK EPOXY RESIN COMPOSITIONS The present invention relates to a

novel two-pack epoxy resin composition, more particularly, to a two-pack epoxy resin composition comprising an epoxy resin as a main constituent and a curing agent.

A two-pack epoxy resin composition generally comprises an epoxy resin as a main constituent with a curing agent and is used as an adhesive or a sealant. It is known that there are various kinds of curing agents such as an amine, amide, polysulfide or thiourea type, from which the most suitable curing agent is selected for use in the two pack epoxy resin composition in accordance with the field of application thereof. However, certain curing agents, especially aliphatic polyamines and polyamidoamine type agents, are hydrophilic and tend to absorb water in the air during the storage thereof. When the epoxy resin and the curing agent are mixed together, this absorbed water accelerates the curing of the composition to shorten the gelation time or working life of the composition and affects adversely the initial characteristics of the composition such as increase of viscosity of the composition with the lapse of time, increase of viscosity during mixing of main constituent/curing agent and decrease of the curability, i.e. decrease of hardness.

Thus we address the task of providing a twopack epoxv resin composition which reduces water absorption of the curing agent and the shortening of gelation time and working life of the composition.

The present inventors have found that an addition of a specific amount of a hygroscopic substance (viz. a hydrolyzable silane compound) to the curing agent can be used to inhibit the shortening of gelation time and working life of the composition without affecting the properties of the curing agent.

In particular we provide a two-pack epoxy resin composition comprising an epoxy resin as a main constituent and a curing agent wherein said composition is further incorporated with a hydrolyzable silane compound in an amount of 0.5 to 5 % (% by weight, hereinafter the same) based on the weight of the curing agent.

The epoxy resin used as a main constituent in the composition of the present invention may be a conventional bisphenol type, a urethane modified bisphenol type, a brominated bisphenol type, a novolac type, an aliphatic type, an alicyclic type and the like,or a combination thereof. An epoxy resin which is liquid at an ordinary temperature is preferably used but a solid type may also be used if it is used together with a liquid type.

The curing agent in the composition of the present invention may be conventional hydrophilic curing agents such as a polyamide resin prepared by reacting a dimer acid with an aliphatic amine; a polyamidoamine; an aliphatic polyamine [e.g. diethylenetriamine (DETA), triethylenetetramine (TETA), diethylaminopropylamine (DEAPA), mxylenediamine (MXDA)I; a modified aliphatic polyamine including an alipha-tic polyamine (e.g. mxylenediamine) modified by addition of a monoepoxy compound or a diepoxy compound, by addition of a unsaturated compound (e.g. acrylonitrile) (Mickel reaction), by reaction with phenol or formaline (Mannich react. ion), by reaction with a dimer acid or tall oil fatty acid, by reaction with a ketone compound (e.g. methyl ethyl ketone), by reaction with a thiourea (a thiourea modified polyamine), or by reaction with 1 4 epichlorohydrin; an alicyclic polyamine [e.g. isOPhoronediamine, bis(aminomethyl)cyclohexane]; an amine adduct, etc. or a combination thereof (c.f. KIRK-OTHMER ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, A WILEYINTERSCIENCE PUBLICATION, John Wiley & Sons, New York, Second Edition, Vol. 8, pp. 302-305, Third Edition, Vol. 9, pp. 278-281, Ullmann's Encyclopedia of Industrial Chemistry, Fifth, Completely Revised Edition, Weinheim; New York, NY: VCH, Vol. A9, pp. 554-557, ENCYCLOPEDIA OF POLYMER SCICENCE AND TECHNOLOGY, Interscience Publishers, John Wiley & Sons, Inc., Vol. 6, pp. 222-235).

The hydrolyzable silane compound used in the invention may be, for example, an alkoxysilane compound such as tetramethoxysilane, tetraethoxysilane, methyltri methoxysilane, methyltriethoxysilane, phenyltrimethoxy silane, phenyltriethoxysilane; a vinylsilane compound such as vinyltrichlorosilane, vinyltrimethoxysilane, vinyltri ethoxysilane, vinyltris(B-methoxyethoxy)silane, vinyltri acetoxysilane; an aminosilane compound such as y-amino propylt riethyoxysilane; a mercaptosilane compound such as y-mercaptopropyltrimethoxysilane, and the like.- These hydrolyzable silane compounds may be used alone or in a mixture thereof. Among hese, hydrolyzable alkoxysilane compounds are highly hygroscopic, and hence, are preferred for use in the Dresent invention.

The hydrolyzable silane compound is used in the composition of the present invention in an amount of 0.5 to 5 %, preferably 0.8 to 3 %, based on the weight of the curing agent. When the amount is less than 0.5 %, the water absorption of the curing agent is not effectively avoided, and when the amount is more than 5 %, the curing is detrimentally delayed and the time for gelation and working life of the composition tends to be prolonged. Further, the hydrolyzable silane compound may also reduce a tendency for precipitation of a filler incorporated in the curing agent with the lapse of time without undesirable deterioration of the properties of the composition such as curability (hardness) and adhesiveness during the storage of the composition.

The two-pack epoxy resin composition of the present invention comprises the epoxy resin as a main constituent and the curing agent incorporated with the hydrolyzable silane compound as mentioned above. optionally, either the above epoxy resin or the curing agent or both may further be incorporated with a conventional filler (e.g. calcium carbonate, clay, talc, barium sulfate, mica, colloidal silica, etc.), a plasticizer, a diluent and the like in an suitable amount.

The present invention is further illustrated by the following nonlimitative Examples and Comparative Examples.

Examples 1 to 8 and Comparative Examples 1 to 2 The main constituent and the curing agent constituent were prepared separately using the amount (parts by weight) of the components listed in Table 1.

The thus prepared main constituent and the curing agent constituent were mixed together to produce an adhesive agent. This adhesive was tested as to the gelation time and working life of the composition immediately after mixing the above two constituents and after storage under conditions of 350C, 90M for 30 days. In addition, the curability and the adhesion of the adhesive were evaluated after storage as mentioned above. The results are shown in Table 1.

v Tah' e---' Example Comp. Ex.

2 3 4 5 6 7 8 1 2 l Epikote 828 100 100 100 100 100 100 100 100 100 100 Filler 40 40 40 40 40 40 60 60 40 60 Luckamide EA 631 21 21 21 21 21 21 - 21 - Luckamide EA 140 21 21 21 21 21 21 21 Ancamide 506 21 21 21 21 21 21 21 Adeka Hardner EH 231 35 35 35 2 Ethyl silicate 28 0.5 2 3 0.5 1.5 A-162 - 2 - - A-163 - 2 - - - S-210 - - - - - 2' - - - - Filler 77 '77 77 77 77 77 - - 77 - immediately after 300 300 300 300 300 300 - - 300 - 3 mixing After storage 300 300 300 275 260 275 - - 210 - Immediately after - - - - - 240 245 - 240 4 mixing After storage - - - 240 245 Curability 5 62 57 57 60 58 61 66 61 63 61 Adhesion 6 I-C-F TC7 C7 CF CF C7 CP CP CP CF 1 --j 1 1 [Note] 1: Main constituent:

Epikote 828 is a bisphenol A type epoxy resin (manufactured by Shell Chemical K.K.t Japan).

The filler is calcium carbonate, clay, talc, barium sulfate, mica and the like.

2: Curing agent constituent:

Luckamide EA 631 is a polyamidoamine 'manufactured by Dainippon Ink Kagaku Kogyo K.K., Japan).

Luckamide EA 140 is a polyamidoamine (manufactured by Dainippon Ink Kagaku Kogyo K.K., Japan).

Ancamide 506 is a polyamidoamine (manufactured by A.C.I.Japan K.K., Japan).

Adeka Hardner EH 231 is a modified aliphatic polyamine (modified by addition of acrylonitrile) (manufactured by Asahi Denka Kogyo K.K., Japan).

Ethyl silicate 28 is tetraethoxysilane (manufactured by Colcote Co., Ltd. ).

A-162 is methyltriethoxysilane (manufactured by Nippon Yuniker K.K., Japan).

A-163 is inethyltrimethoxysilane (manufactured by Nippon Yuniker K.K., Japan).

S-210 is vinyltriethoxysilane (manufactured by Chisso Corporation, Japan).

The filler is the same as those used in the main constituent.

3: Working life of the adhesive:

Each 200 g of the adhesives of Examples 1 to 6 and Comparative Example 1 were tested for time (minute) required for reaching 1 x 105 cps of a viscosity at 200C.

4: Time for gelation:

Each 100 g of the adhesives of Examples 7 and 8 and Comparative Example 2 were tested for time (minute) required for gelation at 200C.

5: The adhesives were cured by heating (Examples 1 to 6 and Comparative Example 1: 6011C x 180 minutes; Examples 9 - 7 7 and 8 and Comparative Example 2: 500C x 90 minutes) and then Shore D h ardness was measured after cooling.

6: The adhesive was applied to a textile and the textile was then piled on a steel plate (as defined in JIS G 3141). After curing the adhesive by heating the piled material in the same manner as in 5, the adhesion strength was evaluated by manually peeling off the piled material. CF: Cohesive failure As is clear from the results shown in Table 1, the adhesive of Comparative Examples showed significant shortening of the working life of the adhesive (Comparative Example 1) and the gelation time (Comparative Example 2) after storage while the adhesives embodying the invention showed almost no change in both the working life and gelation time. Further, the addition of the hydrolyzable silane compound did not affect the curability.and the adhesion adversely.

1 1.

Claims (12)

1. A two-pack epoxy resin composition comprising an epoxy resin as a main constituent and a curing agent, wherein said composition further comprises a hydrolyzable silane compound in an amount of 0.5 to 5 by weight based on the weight of the curing agent.

2. A composition according to claim 1, wherein the epoxy resin is bisphenol type, a urethane modified bisphenol type, a brominated bisphenol type, a novolac type, an aliphatic type or an alicyclic type.

3. A composition of claim 1 or claim 2, wherein the epoxy resin Is a liquid type epoxy resin.

4. A composition of any preceding claim, wherein the curing agent is a hydrophilic, curing agent.

5. A composition according to claim 4, wherein the curing agent Is a polyamide resin prepared by reacting a dimer acid with an aliphatic amine, a polyamidoamine, an aliphatic polyamine, a modified aliphatic polyamine, a thiourea modified pol-yamine, an allcyclic polyamine or an amine adduct. -

6. A composition of any preceding claim, wherein the hydrolyzable silane compound is an alkoxysilane compound, vinylsilane compound, an aminosilane compound or a mercaptosilane compound.

7. A composition according to claim 6, wherein the silane compound is tetramethoxysilane, tetra- 11 ethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethdkysilane, phenyltriethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(p- methoxyethoxy)silane, vinyltriacetoxysilane, yaminopropyltriethyoxysilane or Y-mercaptopropyltrimethoxysilane.

A composition of any preceding claim, wherein the composition further comprises a filler, plasticizer or diluent or any combination of these.

9. A composition of any preceding claim, wherein the amount of the hydrolyzable silane compound is 0.8 to 3%by weight based on the weight of the curing agent.

10. A method comprising the preparation of a composition according to any one of claims 1 to 9.

11. Use of a hydrolyzable silane compound to prolong working life of an epoxy rdsin composition comprising an epoxy resin main constituent and a curing agent, wherein the silane compound is mixed with the composition in an amount of 0.5 to 5t by weight based on the amount of curing agent.

12. An epoxy composition substantially as described herein with reference to the Examples, but not the Comparative Examples.

Published 1990at The Patent Office. State House, 66'71 High Holborn. London WCIR 4TP. Further copies maybeobtainedfrom The Patent Office. Sales Branch, St Mary Cray, Orpington, Kent BRS 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1/87