CROSSLINKING AGENTS FOR POLYMERIC SYSTEMS

Abstract

The present invention relates to a crosslinking agent for polymeric systems, which crosslinking agent comprises elemental sulfur, phenolic resin, thiazole disulfide compounds and metal salts based on thiocarbamates, and to the use thereof in vehicle manufacture.

Claims

1. A crosslinking agent for polymeric systems, comprising components: a) elemental sulfur; b) one or more phenolic resins; c) one or more thiazole disulfide compounds; and d) one or more metal salts based on thiocarbamates.

2. The crosslinking agent according to claim 1, wherein the elemental sulfur is present in an amount of 1 to 5 wt. %, based on total weight of the crosslinking agent.

3. The crosslinking agent according to claim 1, wherein component b) the one or more phenolic resins is present in an amount of 0.5 to 4 wt. % based on total weight of the crosslinking agent.

4. The crosslinking agent according to claim 1, wherein at least one of the one or more phenolic resins is obtained by condensation of a mixture comprising formaldehyde and phenol, the mixture having an excess of phenol and a molar ratio of formaldehyde to phenol of less than 1:1.

5. The crosslinking agent according to claim 1, wherein component c) the one or more thiazole disulfide compounds is present in an amount of 0.3 to 7 wt. %, based on total weight of the crosslinking agent.

6. The crosslinking agent according to claim 5, wherein the one or more thiazole disulfide compounds is selected from benzothiazole disulfide (MBTS) and/or zinc benzothiazole disulfide (ZMBT).

7. The crosslinking agent according to claim 1, wherein component d) the one or more metal salts based on thiocarbamates comprises at least zinc dibenzoyldithiocarbamate.

8. The crosslinking agent according to claim 1, wherein component d) the one or more metal salts based on thiocarbamates is present in an amount of 0.2 to 2 wt. % based on total weight of the crosslinking agent.

9. The crosslinking agent according to claim 1, wherein the crosslinking agent further comprises one or more fillers.

10. The crosslinking agent according to claim 9, wherein the one or more fillers are selected from the group consisting of carbon black, calcium carbonate and calcium oxide.

11. The crosslinking agent according to claim 1, further comprising a polymeric component.

12. The crosslinking agent according to claim 11, wherein the polymeric component is present in an amount of 20 to 50 wt. % based on total weight of the crosslinking agent.

13. The crosslinking agent according to claim 11, wherein the polymeric component is selected from polybutadienes.

14. The crosslinking agent according to claim 1, wherein based on total weight of the crosslinking agent: component a) is present in an amount of 1.5 to 4 wt. %; component b) is present in an amount of 0.7 to 3 wt. %; component c) is present in an amount of 0.5 to 5 wt. %; component d) is present in an amount of 0.4 to 1.5 wt. %; and the crosslinking agent optionally comprises a polymeric component.

15. The crosslinking agent according to claim 14, wherein the polymeric component is present in an amount of 25 to 40 wt. % based on the total weight of the crosslinking agent.

16. A process for depositing electrophoretic dip coating and/or liquid applied sound deadener comprising steps of: 1) applying a polymeric system comprising the crosslinking agent according to claim 1, to at least a portion of a vehicle; 2) before or after or both before and after step 1), contacting the portion of the vehicle with an electrophoretic dip coating and/or a liquid applied sound deadener; and 3) heating the portion of the vehicle for a time and temperature sufficient to crosslink the polymeric system and cure the electrophoretic dip coating and/or liquid applied sound deadener.

17. The process according to claim 16, wherein the polymeric system comprising the crosslinking agent is an adhesive system and the crosslinking agent contains no more than 5 wt. % elemental sulfur.

18. The process according to claim 16, performed in the presence of bismuth catalysts.

Description

EXAMPLES

[0028] The compositions summarized in Table 1 were produced, the stated amounts in each case being understood as percent by weight based on the total weight of the composition.

TABLE-US-00001 TABLE 1 Component Example 1 Example 2 Example 3 Polymer 24   24   24   Filler 64.74 63.74 62.74 Phenolic resin 0.9 1.9 2.9 Sulfur 2.5 2.5 2.5 Zinc 1.5 1.5 1.5 dibenzoylthiocarbamate Benzothiazole disulfide 5.0 — 5.0 Zinc benzothiazole — 5.0 — disulfide Additives  1.36  1.36  1.36 Total 100.00  100.00  100.00 

[0029] The compositions of Table 1 were examined for their compatibility with customary electrophoretic coating systems, the bismuth-containing paint CathoGuard 800 from BASF SE, Germany being used as an exemplary coating. The composition was applied to a sample sheet in the form of a drop and coated with the paint. The paint was cured and assessed under the conditions given in Table 2.

[0030] Bismuth-containing Paint Compatibility Testing

TABLE-US-00002 TABLE 2 Cure 10 min; 15 min; 20 min; 5 min; 10 min; Conditions 165° C. 165° C. 165° C. 170° C. 170° C. Rating Result 0 0 0 0 0

TABLE-US-00003 Legend: Rating Evaluation 0 No change in the surface 1 First signs of change 3 Bubble formation on the paint layer; no detachment 5 Detachment of the paint layer from the surface

[0031] As can be seen from the provided data, the compositions according to the invention had excellent compatibility with common coating systems.

Sulfur Emission Testing

[0032] Sulfur emission tests were also carried out. Test results showed the low emission tendency of the above compositions according to the invention. For this purpose, the example compositions were knife-coated onto a metal sheet in a 2 mm thick layer. The metal sheet was placed in a 1 L metal can to harden and sealed with a wet CDC sheet. The test arrangement was cured in a laboratory furnace at 105° C. for 6 minutes and 190° C. for 30 minutes, the outgoing emissions from the curing compositions reacting with the CDC coating. The concentration of sulfur on the contaminated CDC surface was then analyzed using XPS. The measurements showed a concentration of sulfur atoms in the range of 0.5 at. %.