Use of substituted benzyl alcohols in reactive epoxy systems

Abstract

The present invention relates to the use of substituted benzyl alcohols as modifiers in epoxy systems.

Claims

1. A composition comprising: A) at least one resin having epoxy groups, B) at least one amine hardener, C) at least one modifier in the form of a benzyl alcohol further substituted on a carbon atom of the aromatic ring with a ring substituent, wherein the ring substituent is selected from the group consisting of an alkoxy group, a dialkylamino group, a linear alkyl having at least four carbon atoms, a, branched alkyl having at least four carbon atoms, and a cyclic alkyl group having at least four carbon atoms, and, optionally, D) at least one auxiliary, wherein said composition excludes an epoxy novolac, and, wherein in component C), only one other ring substituent is present alongside hydroxymethyl group of the benzyl alcohol.

2. The composition according to claim 1, wherein component A) comprises glycidyl ethers which derive from polyhydric phenols and which have molar masses, based on the number of the epoxy groups, of from 100 to 500 g/mol.

3. The composition according to claim 1, wherein component A) comprises at least one monoepoxide as a reactive diluent.

4. The composition according to claim 1, wherein the component B) comprises at least one selected from the group consisting of aliphatic amines, oxyalkylenepolyamines, cycloaliphatic amines, araliphatic amines, aromatic amines, adduct hardeners, these being reaction products of epoxy compounds with excess amine, polyamidoamine hardeners obtained via condensation of mono- and polycarboxylic acids with polyamines, Mannich-base hardeners obtained via reaction of mono- or polyhydric phenols with aldehydes and with polyamines, or phenalkamines.

5. The composition according to claim 1, wherein component C) comprises a benzyl alcohol selected from the group consisting of 4-methoxybenzyl alcohol and 3-dimethylaminobenzyl alcohol.

6. The composition according to claim 1, wherein an amount of the at least one modifier C) is from 5 to 20% by weight, based on the sum of the masses of the compounds A), B) and C).

7. A coating composition, a sealant, a composite or an adhesive comprising the composition of claim 1.

8. The coating composition according to claim 7 which has a curing temperature ranging from 5 to 260 C.

9. A reactive epoxy system comprising the composition according to claim 1.

10. An adhesive comprising the reactive epoxy system according to claim 9.

11. A coating comprising the reactive epoxy system according to claim 9.

12. The coating of claim 11 which has been cured.

13. A coating composition, a sealant, a composite or an adhesive comprising: the composition of claim 1, wherein an amount of the at least one modifier C) is from 5 to 20% by weight, based on the sum of the masses of the compounds A), B) and C), and wherein the coating composition has a curing temperature of from 5 to 260 C.

14. The composition according to claim 1, wherein said at least one auxiliary is present and is at least one auxiliary selected from the group consisting of an accelerator, a further hardener, an additional curable resin, an extender resin, a pigment, a pigment paste, a dye, an antioxidant, a stabilizer a thickener, an antifoam, a wetting agent, a reactive diluent, a filler, a plasticizer or a flame-retardant material.

15. The composition according to claim 1, wherein said ting substituent is selected from the group consisting of alkoxy group(s) and dialkylamino group(s).

16. A method of coating an object comprising applying the coating composition according to claim 1 to said object and, optionally, curing the composition.

17. A method for bonding objects together comprising applying the coating composition according to claim 1 to at least one object and curing the composition.

18. A composition comprising: A) at least one resin having epoxy groups, B) at least one amine hardener, C) at least one modifier in the form of a benzyl alcohol further substituted on at least one carbon atom of the aromatic ring with at least one ring substituent, wherein the ring substituent(s) are selected from the group consisting of alkoxy group(s), dialkylamino group(s), linear alkyl having at least four carbon atoms, branched alkyl having at least four carbon atoms, and cyclic alkyl having at least four carbon atoms, and, optionally, D) at least one auxiliary, wherein said composition excludes an epoxy novolac, and wherein a boiling point of the at least one modifier is at least 240 C., and wherein the composition is capable of curing to produce a cured coating with a heat resistance of more than 30 C. after one day.

19. A coating composition, sealant, composite or adhesive, comprising: a composition, which comprises: A) at least one resin having epoxy groups, B) at least one amine hardener, C) at least one modifier in the form of a benzyl alcohol further substituted on at least one carbon atom of the aromatic ring with at least one ring substituent, wherein the ring substituent(s) are selected from the group consisting of alkoxy group(s), dialkylamino group(s), linear alkyl having at least four carbon atoms, branched alkyl having at least four carbon atoms, and cyclic alkyl groups having at least four carbon atoms, and, optionally, D) at least one auxiliary, wherein said composition excludes an epoxy novolac, wherein an amount of the at least one modifier C) is from 5 to 20% by weight, based on the sum of the masses of the compounds A), B) and C), wherein the coating composition, sealant, composite or adhesive has a curing temperature of from 5 to 260 C., wherein a boiling point of the at least one modifier is at least 240 C., and wherein the composition is capable of curing to produce a cured coating with a heat resistance of more than 30 C. after one day.

20. The coating composition of claim 19, wherein the viscosity of the composition is at most 5000 mPa.Math.s.

Description

EXAMPLES

(1) In order to determine and compare the properties of the modifiers, standard epoxy formulations are prepared. To this end, 100 parts of isophoronediamine (Vestamin IPD from Evonik Industries AG) as component B) are mixed with 441 parts of Epikote 828 (bisphenol A diglicidyl ether from Momentive) as component A) with use of 88 parts of modifier (component C).

(2) Table 1 shows the results.

(3) TABLE-US-00001 TABLE 1 Example 2) 3) 4) 1*) 4-Methoxy- 4-Isopropyl- 3-Dimethyl- Benzyl benzyl benzyl amino-benzyl alcohol alcohol alcohol alcohol Vestamin % by 100 100 100 100 IPD wt. Epikote % by 441 441 441 441 828 wt. Modifier % by 88 88 88 88 wt. Boiling point [ C.] 206 258 249 282 of modifier Viscosity [mPas] 1100 1500 1350 1960 Heat resistance (HDT) DIN EN ISO 75-1 - curing: 23 C./50% H after 1 day C. 38 36 34 35 after 2 days C. 48 41 42 43 after 7 days C. 58 47 48 51 Example 5*) 6*) 8*) Methoxy- Propoxy- 7*) Benzyltoluene propanol ethanol Isophorone (Marlotherm LH) Vestamin % by 100 100 100 100 IPD wt. Epikote % by 441 441 441 441 828 wt. Modifier % by 88 88 88 88 wt. Boiling point [ C.] 119-122 150-153 215 278-282 of modifier Viscosity [mPas] n.d. n.d. n.d. n.d. Heat resistance (HDT) DIN EN ISO 75-1 - curing: 23 C./50% H after 1 day C. <20 <20 brittle brittle after 2 days C. 35 30 brittle brittle after 7 days C. 50 50 brittle brittle *Comparative Examples not according to the invention H: humidity

(4) From these data it can be seen that only the Examples according to the invention exhibit advantageous technical properties, in particular adequate heat resistance (30 C. after one day, and also 40 C. after 7 days), initial viscosity below 5000 mPas and boiling point above 240 C. The boiling point of benzyl alcohol (Example 1) is too low, while the remaining Comparative Examples (Examples 5-8) exhibit inadequate heat resistance.