FORMULATIONS WITH HIGH GLASS TRANSITION TEMPERATURES, FOR LAMINATES

Abstract

The present invention relates to curable resin compositions, to methods for producing cured compositions using said curable resin compositions, and to items, in particular molded parts, produced by means of such methods.

Claims

1. A resin composition comprising at least one epoxy resin component at least one curing component and based on the total weight thereof, (A) 1-30 wt. % particles having a core-shell structure, and (B) 1-10 wt. % inorganic particles.

2. The resin composition according to claim 1, characterized in that the at least one epoxy resin component comprises a cycloaliphatic epoxy resin.

3. The resin composition according to claim 1, characterized in that (a) the total amount of particles (A) and particles (B) is in the range of from 1 to 30 wt. % based in each case on the total weight of the resin composition; and/or (b) the amount of inorganic particles (B) is in the range of from 4-8 wt. %; and/or (c) the particles (A) and the particles (B) are contained in the epoxy resin component.

4. The resin composition according to claim 1, characterized in that the at least one epoxy resin component is an epoxy compound selected from the group consisting of bis-(3,4-epoxycyclohexylmethyl) oxalate, bis-(3,4-epoxycyclohexylmethyl) adipate, bis-(3,4-epoxy-6-methylcyclohexylmethyl) adipate, bis-(3,4-epoxycyclohexylmethyl) pimelate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, bis-(3,4-epoxycyclohexyl) adipate, 3,4-epoxy-1-methylcyclohexylmethyl-3,4-epoxy-1-methylcyclohexane carboxylate, and mixtures thereof.

5. The resin composition according to claim 1, characterized in that the at least one curing component comprises at least one anhydride curing agent.

6. The resin composition according to claim 5, characterized in that the at least one anhydride curing agent is selected from bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic acid anhydride, bicyclo[2.2.1]methylhept-5-ene-2,3-dicarboxylic acid anhydride, and mixtures thereof.

7. A method for producing a cured composition comprising the steps of: (1) providing a resin composition according to claim 1; and (2) curing the resin composition in order to obtain a cured composition.

8. The method according to claim 7, characterized in that the method is a transfer molding (RTM) method and the resin composition is a reactive injection resin.

9. The method according to claim 7, characterized in that step (1) comprises injecting the resin composition into a die in which fibers or semi-finished fiber products (prewovens/preforms) are placed.

10. The method according to claim 7, characterized in that (a) the resin composition in step (2) is cured at a temperature of between 100° C. and 240° C., for 0.01 to 10 hours; or (b) the resin composition in step (2) is first pre-cured at a temperature of between 70° C. and 150° C., for 0.1 to 3 hours and is then post-cured at least once, in each case at a temperature of between 110° C. and 260° C., in each case for 0.1 to 3 hours.

11. A cured composition obtainable according to a method to claim 7.

12. The cured composition according to claim 11, characterized in that the K1c value of the cured composition is at least 0.8.

13. The cured composition according to claim 11, characterized in that the cured composition has a glass transition temperature T.sub.g≥250° C.

14. The cured composition according to claim 11, characterized in that the cured composition is a molded part, in particular a fiber-reinforced molded part.

Description

EXAMPLES

Example Formulation 1

[0071] Epoxy Resin Component:

97.7 g cycloaliphatic epoxy having 30% organic core-shell structure particles
4.1 g organic core-shell structure particles
42.5 g cycloaliphatic epoxy having 40% SiO.sub.2 particles
3.0 g multi-functional fatty acid ester (release agent)

[0072] Curing Component:

132.0 g mixture of bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic acid anhydride and bicyclo[2.2.1]methylhept-5-ene-2,3-dicarboxylic acid anhydride
2.0 g 1-methylimidazole

[0073] The epoxy resin component and the curing component were homogenized and then poured into a steel mold. The pre-curing took place at 130° C. over a period of 30 minutes. The mixture was then post-cured for one hour at 180° C., for one hour at 200° C., for one hour at 220° C. and finally for one hour at 240° C. in order to ensure complete cross-linking. In this way, polymer plates approximately 4 mm thick with an area of 20 cm×20 cm were produced.

[0074] The total amount of organic particles was approximately 12%; the total amount of inorganic particles was approximately 6%. The physical properties of the plate produced in this way are clearly summarized in the table below.

TABLE-US-00001 TABLE 1 Physical properties of example composition 1 Flexural modulus [MPa] 2,159 Flexural strength [MPa] 96 K1c [MPa*m½] 1.0 Tg DMA tan delta [° C.] 280 Tg DMA E′ onset [° C.] 255

Example Formulation 2

[0075] Epoxy Resin Component:

81.6 g cycloaliphatic epoxy having 30% core-shell structure particles
3.4 g core-shell structure particles
60.0 g cycloaliphatic epoxy having 40% SiO.sub.2 particles
3.0 g multi-functional fatty acid ester (release agent)

[0076] Curing Component:

132.0 g mixture of bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic acid anhydride and bicyclo[2.2.1]methylhept-5-ene-2,3-dicarboxylic acid anhydride
2.0 g 1-methylimidazole

[0077] The epoxy resin component and the curing component were homogenized and then poured into a steel mold. The pre-curing took place at 130° C. over a period of 30 minutes. The mixture was then post-cured for one hour at 180° C., for one hour at 200° C., for one hour at 220° C. and finally for one hour at 240° C. in order to ensure complete cross-linking. In this way, polymer plates approximately 4 mm thick with an area of 20 cm×20 cm were produced.

[0078] The total amount of organic particles was approximately 10%; the total amount of inorganic particles was approximately 8%. The physical properties of the plate produced in this way are clearly summarized in the table below.

TABLE-US-00002 TABLE 2 Physical properties of example composition 2 Flexural modulus [MPa] 2,400 Flexural strength [MPa] 96 K1c [MPa*m½] 0.9 Tg DMA tan delta [° C.] 275 Tg DMA E′ onset [° C.] 250

Comparative Example

[0079] Epoxy Resin Component:

137.0 g cycloaliphatic epoxy with 30% core-shell structure particles
3.0 g multi-functional fatty acid ester (release agent)

[0080] Curing Component:

137.0 g mixture of bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic acid anhydride and bicyclo[2.2.1]methylhept-5-ene-2,3-dicarboxylic acid anhydride
2.0 g 1-methylimidazole

[0081] The epoxy resin component and the curing component were homogenized and then poured into a steel mold. The pre-curing took place at 130° C. over a period of 30 minutes. The mixture was then post-cured for one hour at 180° C., for one hour at 200° C., for one hour at 220° C. and finally for one hour at 240° C. in order to ensure complete cross-linking. In this way, polymer plates approximately 4 mm thick with an area of 20 cm×20 cm were produced.

[0082] The total amount of organic particles was approximately 15%. The physical properties of the plate produced in this way are clearly summarized in the table below.

TABLE-US-00003 TABLE 3 Physical properties of the comparative example composition Flexural modulus [MPa] 2,182 Flexural strength [MPa] 79 K1c [MPa*m½] 0.7 Tg DMA tan delta [° C.] 281 Tg DMA E′ onset [° C.] 252

[0083] The direct comparison of the two example formulations 1 and 2 according to the present invention with the formulation of the comparative example shows that a combination of organic core-shell structural particles and inorganic particles in cycloaliphatic epoxy resin compositions results in an increase in the K1c value, without the glass transition temperature of the cured composition being lowered.