Composition for an adhesive material

Abstract

A composition for an adhesive material, comprising at least one epoxide resin mixture and a hardening accelerator, in which the epoxide resin mixture has 25 to 80% by weight of a first epoxide resinwhereby the first epoxide resin is a bifunctional aliphatic, cycloaliphatic or aromatic epoxide resinand 12.5 to 40% by weight of a second epoxide resinwhereby the second epoxide resin is a polyfunctional aliphatic or aromatic epoxide resinand in which the hardening accelerator is an imidazole derivative, which is not soluble in the epoxide resin mixture at temperatures of below 50 C.

Claims

1. A composition for an adhesive material, comprising an epoxide resin mixture and an imidazole derivative component wherein the epoxide resin mixture comprises: (a) 25 to 75% by weight of a first epoxide resin, wherein the first epoxide resin is a bifunctional aliphatic, cycloaliphatic or aromatic epoxide resin; (b) 12.5 to 40% by weight of a second epoxide resin, wherein the second epoxide resin is a polyfunctional aliphatic or aromatic epoxide resin; (c) 12.5 to 40% by weight of an epoxidized rubber, wherein the sum of (a), (b), and (c) yields 100% by weight; and wherein the imidazole derivative component initiates homopolymerization of the epoxy resin mixture and is one or more imidazole derivatives, the imidazole derivative component is not soluble in the epoxide resin mixture at temperatures of below 50 C., and the imidazole derivative component is the only hardener present in the composition; and wherein the composition forms a hardened adhesive material having a polyether structure and a creepage current resistance value of greater than 600 V.

2. The composition according to claim 1, wherein the first epoxide resin is a liquid epoxide resin with an epoxide group content of 0.1 to 0.9 mol/100 g of the first epoxide resin.

3. The composition according to claim 1, wherein the first epoxide resin is selected from the group consisting of epoxide resins of the bisphenol A type, epoxide resins of the bisphenol F type, epoxide resins based on bis-(epoxycyclohexyl)methylcarboxylate, epoxide resins based on hydrophthalic acid diglycidyl ester, and mixtures thereof.

4. The composition according to claim 1, wherein the first epoxide resin has an epoxide group content of 0.4 to 0.7 mol/100 g of the first epoxide resin.

5. The composition according to claim 1, wherein the second epoxide resin is an epoxide resin with an epoxide group content of 0.3 to 1.0 mol/100 g of the second epoxide resin or an epoxy functionality of 2 to 10 epoxide resin groups per molecule, or both.

6. The composition according to claim 1, wherein the second epoxide resin is selected from the group consisting of epoxy phenol novolacs, epoxy cresol novolacs, and polyfunctional epoxide resin derivatives of aromatic amines or phenols.

7. The composition according to claim 1, wherein the second epoxide resin is 4,4-methylene-bis(N,N-diglycidylaniline), N,N-diglycidyl-4-glycidyloxyaniline, a polyglycidyl diaminodiphenyl ether or a polyglycidyl diaminodiphenyl sulfone.

8. The composition according to claim 1, wherein the second epoxide resin is liquid, semi-solid or solid.

9. The composition according to claim 1, wherein the epoxidized rubber is an epoxidized nitrile rubber.

10. The composition according to claim 9, in which the epoxidized nitrile rubber is a liquid epoxidized nitrile rubber with at least one of the following features: an epoxide group content of 0.1 to 0.5 mol/100 g of epoxidized nitrile rubber; a viscosity of greater than 10,000 mPa.Math.s; a proportion of nitrile rubber in the epoxidized nitrile rubber of at least 5% by weight.

11. The composition according to claim 9, wherein the epoxidized nitrile rubber is a liquid epoxidized nitrile rubber with at least one of the following features: an epoxide group content of 0.2 to 0.4 mol/100 g of epoxidized nitrile rubber, a viscosity of 40,000 to 600,000 mPa.Math.s, a proportion of nitrile rubber in the epoxidized nitrile rubber of 20 to 50% by weight.

12. The composition according to claim 1, wherein the imidazole derivative component is present in the composition in an amount of 2 to 10% by weight, relative to the epoxide resin mixture.

13. The composition according to claim 1, wherein the imidazole derivative component is selected from the group consisting of 2-phenyl-4,5-dihydroxymethyl imidazole, 2-phenyl-4-methyl-5-hydroxymethyl imidazole, and mixtures thereof.

14. An adhesive for electric and electronic components, comprising a composition according to claim 1.

Description

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

First Epoxide Resin

(1) The first epoxide resin is a bifunctional aliphatic, cycloaliphatic or aromatic epoxide resin. For example, the first epoxide resin is an epoxide resin that is liquid at room temperature.

(2) In one embodiment, the first epoxide resin is selected from the group that consists of epoxide resins of the bisphenol A type, epoxide resins of the bisphenol F type, epoxide resins based on bis-(epoxycyclohexyl)methylcarboxylate, epoxide resins based on hydrophthalic acid diglycidyl ester, and mixtures thereof. For example, epoxide resins based on bisphenol A and/or bisphenol F have an average molecular weight of <700 g/mol.

(3) The first epoxide resin has, for example, an epoxide group content of 0.1 to 0.9 mol/100 g of the first epoxide resin. For example, if the first epoxide resin is an epoxide resin based on bisphenol A and/or bisphenol F, the first epoxide resin can have an epoxide group content of 0.4 to 0.7 mol/100 g of the first epoxide resin.

(4) Second Epoxide

(5) The second epoxide resin is a polyfunctional aliphatic or aromatic epoxide resin. This component provides for a sufficiently high thermal resistance and bonding strength of the epoxide resin mixture at elevated temperatures.

(6) The second epoxide resin is soluble, for example, in the first epoxide resin. It is, for example, an epoxide resin that is solid, or semi-solid, or liquid at room temperature.

(7) In another embodiment, the second epoxide resin is selected from the group that consists of epoxy phenol novolacs, epoxy cresol novolacs, or polyfunctional epoxide resin derivatives of aromatic amines or phenols. Representative examples of the second epoxide resin are 4,4-methylene-bis(N,N-diglycidylaniline) (CAS No. 28768-32-3), N,N-diglycidyl-4-glycidyloxyaniline (CAS No. 5026-74-4), polyglycidyl diaminodiphenyl ethers, and polyglycidyl diaminodiphenyl sulfones. If the second epoxides are epoxy phenol novolacs and/or epoxy cresol novolacs, these novolacs have, for example, an epoxy functionality of greater than 2. Also, as second epoxides, comparable polyfunctional resins can be used, which are used for increasing the cross-linking density of the first epoxide resin.

(8) In another embodiment, the second epoxide resin is an epoxide resin with an epoxide group content of 0.3 to 1.0 mol/100 g of the second epoxide resin. In another embodiment, the second epoxide resin has an epoxy functionality of 2 to 10 epoxide resin groups per molecule.

(9) Epoxidized Rubber

(10) Moreover, the epoxide resin mixture can comprise an epoxidized rubber. Such a rubber is a bifunctional resin that contains epoxidized, flexible chain segments. By means of such an epoxidized rubber, a marked improvement of the adhesion of the adhesive material, for example to polyamide, can be achieved. In addition, the impact resistance of the hardened adhesive material can be improved.

(11) The epoxidized rubber is, for example, an epoxidized acrylonitrile-butadiene rubber, for example an epoxidized nitrile rubber (also referred to as epoxidized NBR rubber), and, for example, an epoxidized nitrile rubber that is liquid at room temperature. An exemplary liquid nitrile rubber has at least one of the following features:

(12) An epoxide group content of 0.1 to 0.5 mol/100 g of epoxidized nitrile rubber, for example 0.2 to 0.4 mol/100 g of epoxidized nitrile rubber;

(13) A viscosity of greater than 10,000 mPa.Math.s, for example 40,000 to 600,000 mPa.Math.s;

(14) A proportion of nitrile rubber in the epoxidized nitrile rubber of at least 5% by weight, for example 20 to 50% by weight.

(15) Hardening Accelerator

(16) The provided hardening accelerator is an imidazole derivative, which is not soluble in the epoxide resin mixture at temperatures of below 50 C. For example, the hardening accelerator is solid at temperatures of below 50 C.

(17) Exemplary imidazole derivatives are selected from the group that consists of 2-phenyl-4,5-dihydroxymethyl imidazole, 2-phenyl-4-methyl-5-hydroxymethyl imidazole, and mixtures thereof.

(18) For example, the hardening accelerator is present in the composition in an amount of 2 to 10% by weight, relative to the epoxide resin mixture. The hardening accelerator is present in the composition, for example, in the form of a micronized solid.

(19) Optional Additional Components of the Composition

(20) Optionally, the composition presented herein can comprise additional components. Thus, the composition can contain rheological additives known to one skilled in the art, e.g., layer silicates (bentonite) or pyrogenic silicic acid, for adjusting the desired paste-like properties. For reduction of the thermal expansion, the composition can contain the conventional mineral additives based on oxide, hydroxide, carbonate, or silicate, such as, for example, silicon dioxide, calcium carbonate, aluminum oxide, magnesium silicate, aluminum silicate, calcium silicate, or fillers that have a similar effect and that are known to one skilled in the art.

(21) The invention is explained in more detail below based on the embodiments (examples) and comparison examples.

Example 1

(22) A composition with the following components was produced:

(23) 30 g of DOW 331 (bisphenol A standard resin, supplier DOW Chemicals)

(24) 30 g of Polydis 3614 (epoxidized NBR rubber, supplier Schill+Seilacher)

(25) 30 g of Tetraglycidyl methylenedianiline

(26) 4 g of 2-Phenyl-4,5-dihydroxymethyl imidazole

(27) 10 g of Bentone 27 (rheological additive, supplier Elementis)

(28) After mixing and homogenizing the individual components together, a paste-like composition that has a long shelf life of more than 5 months at room temperature and that can harden in one hour at 120 C. was obtained for use as an adhesive material. The composition filled gaps up to 5 mm wide. The hardened adhesive material had a creepage current resistance value of greater than 600 V and a glass transition temperature of 132 C. (measured with Mettler DCS).

Example 2

(29) A composition with the following components was produced:

(30) 50 g of CHS 590 (bisphenol F standard resin, supplier SPOL Chemie)

(31) 25 g of Polydis 3615 (epoxidized NBR rubber, supplier Schill+Seilacher)

(32) 25 g of Tetraglycidyl-4,4-diaminodiphenyl ether

(33) 6 g of 2-Phenyl-4,5-dihydroxymethyl imidazole

(34) 10 g of Bentone 27 (rheological additive, supplier Elementis)

(35) After mixing and homogenizing the individual components together, a paste-like composition that has a long shelf life of more than 5 months at room temperature and that can harden in three hours at 100 C. was obtained for use as an adhesive material. The composition filled gaps up to 5 mm wide. The hardened adhesive material had a creepage current resistance value of greater than 600V and a glass transition temperature of 121 C. (measured with Mettler DCS).

Example 3

(36) A composition with the following components was produced:

(37) 50 g of CHS 590 (bisphenol F standard resin, supplier SPOL Chemie)

(38) 25 g of Polydis 3615 (epoxidized NBR rubber, supplier Schill+Seilacher)

(39) 25 g of Araldite EPN 1138 (epoxidized phenol novolac, supplier Huntsman)

(40) 8 g of 2-Phenyl-4-methyl-5-hydroxymethyl imidazole

(41) 10 g of Bentone 27 (rheological additive, supplier Elementis)

(42) 100 g of Martinal ON-320 (aluminum hydroxide, supplier Albemarle)

(43) After dissolving, mixing and homogenizing the individual components together, a paste-like composition that has a long shelf life of more than 5 months at room temperature and that can harden in one hour at 120 C. was obtained for use as an adhesive material. The composition filled gaps up to 5 mm wide. The hardened adhesive material had a creepage current resistance value of greater than 600 V and a glass transition temperature of 128 C. (measured with Mettler DCS).

Example 4

(44) A composition with the following components was produced:

(45) 45 g of CHS 590 (bisphenol F standard resin, supplier SPOL Chemie)

(46) 35 g of Polydis 3614 (epoxidized NBR rubber, supplier Schill+Seilacher)

(47) 20 g of Araldite ECN 1299 (epoxidized cresol novolac, supplier Huntsman)

(48) 7 g of 2-Phenyl-4-methyl-5-hydroxymethyl imidazole

(49) 10 g of Bentone 27 (rheological additive, supplier Elementis)

(50) 70 g of Martinal ON 320 (aluminum hydroxide, supplier Albemarle)

(51) 20 g of Tremin 939 (wollastonite, supplier Quarzwerke)

(52) After dissolving, mixing and homogenizing the individual components together, a paste-like composition that has a long shelf life of more than 5 months at room temperature and that can harden in one hour at 120 C. was obtained for an adhesive material. The composition filled gaps up to 5 mm wide. The hardened adhesive material had a creepage current resistance value of greater than 600 V and a glass transition temperature of 122 C. (measured with Mettler DCS).

Comparison Example 1

(53) A composition with the following components was produced:

(54) 50 g of CHS 590 (bisphenol F standard resin, supplier SPOL Chemie)

(55) 25 g of Polydis 3615 (epoxidized NBR rubber, supplier Schill+Seilacher)

(56) 25 g of Tetraglycidyl-4,4-diaminodiphenyl ether

(57) 2 g of 1-Cyanoethyl-2-ethyl-4-methylimidazole

(58) 10 g of Bentone 27 (rheological additive, supplier Elementis)

(59) The composition hardened for an hour at 120 C. and filled gaps up to 5 mm wide. The hardened adhesive material had a creepage current resistance, value of greater than 600 V and a glass transition temperature of 124 C. (measured with Mettler DCS).

(60) In Comparison Example 1, an imidazole derivative that is soluble in resin at room temperature was used as hardening accelerator instead of the solid imidazole derivatives that are described in the examples and that are not soluble in the resin matrix at room temperature. In this case, in the hardened state, adhesive materials with properties comparable to those in the examples were obtained; however, the paste-like adhesive material had a service life of only 3 to 5 days at room temperature.

Comparison Example 2

(61) A composition with the following components was produced:

(62) 50 g of Araldite GY 285 (bisphenol F standard resin, supplier Huntsman)

(63) 40 g of Polydis 3615 (epoxidized NBR rubber, supplier Schill+Seilacher)

(64) 3.5 g of 2-Phenyl-4-methyl-5-hydroxymethyl imidazole

(65) 10 g of Bentone 27 (rheological additive, supplier Elementis)

(66) After mixing and homogenizing the individual components, a paste-like composition that has a long shelf life of more than 5 months at room temperature and that can harden in one hour at 120 C. was obtained for an adhesive material. The composition filled gaps up to 5 mm wide. The hardened adhesive material had a creepage current resistance value of greater than 600 V and a glass transition temperature of 82 C. (measured with Mettler DCS).

(67) In Comparison Example 2, the addition of the polyfunctional resin components was eliminated. Adhesive materials with a considerably lower glass transition temperature and thus considerably reduced adhesive strength at elevated ambient temperatures were thus obtained. All other properties, such as, for example, the creepage current resistance, remain unchanged, however.

(68) Thus a composition or adhesive materialwhich can be formulated as a single-component composition, can harden even at temperatures starting from 100 C., and has a shelf life of at least three months at room temperatureis indicated.

(69) The invention having been thus described by reference to certain specific embodiments and examples, it will be understood that these specific embodiments and examples are illustrative, and not limiting, of the invention recited in the appended claims.