CROSS-LINKING AGENT COMPOSITION FOR ELASTOMERS

Abstract

A cross-linking agent composition including a diamine cross-linking agent, which composition achieves comparable or better values in the ratio of the maximum achievable elongation at break to the heat compression set level in comparison to cross-linking agent compositions having a guanidine accelerator, even with high filler contents of the elastomer materials, includes a diamine cross-linking agent, an accelerator of the type of the 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU), an activator of the pyrrolidone type, as well as a secondary aliphatic amine and/or a tertiary aliphatic amine.

Claims

1. A cross-linking agent composition for elastomer materials, comprising a diamine cross-linking agent, an accelerator of the type of the 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU), an activator of the pyrrolidone type, as well as a secondary aliphatic amine and/or a tertiary aliphatic amine.

2. The cross-linking agent composition in accordance with claim 1, wherein the composition additionally comprises an aldehydic amine, wherein the weight ratio of the accelerator of the DBU type to the sum of the amounts of the aliphatic and, optionally, aldehydic amines in the cross-linking agent composition is preferably about 25:75 to about 99:1.

3. The cross-linking agent composition in accordance with claim 1, wherein the diamine cross-linking agent is selected from hexamethylene diamine carbamate, N,N-dicinnamylidene diamine carbamate, 4,4-diaminodicyclohexylmethane, m-xylylenediamine, 4,4-diaminodiphenylmethane, 4,4-diaminodiphenylether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, as well as hexamethylenediamine.

4. The cross-linking agent composition in accordance with claim 1, wherein the amount by weight of the activator of the pyrrolidone type in relation to the amount of the accelerator of the DBU type in the cross-linking agent composition is about 15% by weight to about 50% by weight.

5. The cross-linking agent composition in accordance with claim 1, wherein the aliphatic amine is selected from secondary amines, in particular secondary fatty acid alkyl amines, preferably di-coco-alkylamine (DCAA), di-(hydrogenated tallow fat)-amine, bis(hydrogenated tallow alkyl) amine (BHTAA), and di-stearylamine, as well as tertiary amines, in particular behenyl-dimethylamine, octadecyl-dimethylamine, di-coco-alkyl methylamine (DCMAA), di-hydrogenated tallow fat methyl amine (BHTMAA), di-hydrogenated tallow fat-secondary-alkylamine (BHTAsA), tri-hexadecylamine, or mixtures of the aforementioned amines.

6. The cross-linking agent composition in accordance with claim 2, wherein the aldehydic amine is selected from 3,5-diethyl-1,2-dihydro-1-phenyl-2-propyl-pyridine (PDHP), condensation products from butyraldehyde and aniline and condensation products from butyraldehyde and butylamine.

7. An elastomer material comprising one or more of the elastomers of the group HNBR, ACM, EACM, DENKA, and FKM, as well as a cross-linking agent composition according claim 1.

8. The elastomer material in accordance with claim 7, wherein the amount of the accelerator of the DBU type in the elastomer material is about 1 phr to about 10 phr, preferably about 2 phr to about 4 phr.

9. The elastomer material in accordance with claim 7, wherein the diamine cross-linking agent in the elastomer material is present in an amount of about 1 phr to about 4 phr, preferably about 1.5 phr to about 2.5 phr.

10. The elastomer material in accordance with claim 7, wherein the amount of the secondary aliphatic and/or tertiary aliphatic amine or the amines in the elastomer material is about 0.1 phr to about 2.9 phr, preferably about 1 phr to about 1.5 phr.

11. The elastomer material in accordance with claim 7, wherein the elastomer material contains one or more fillers, wherein the filler or fillers are preferably selected from inactive to active carbon black types or light fillers, in particular silicas, kaolins, mica, feldspar, talc, calcium carbonate, quartz, diatomaceous earth, cristobalite, barium sulfate (in naturally occurring or precipitated form).

12. The elastomer material in accordance with claim 11, wherein the amount of the filler or fillers in the elastomer material is about 50 phr or more, preferably less than about 120 phr.

13. A gasket comprising an elastomer gasket element produced using an elastomer material in accordance with claim 7.

14. The gasket in accordance with claim 13, wherein the gasket comprises a support on which the elastomer gasket element is arranged.

15. The gasket in accordance with claim 13, wherein the gasket comprises a support which is partially or entirely enclosed by the elastomer gasket element.

16. The gasket in accordance with claim 13, wherein the gasket substantially consists of the elastomer gasket element.

17. The gasket in accordance with claim 13, wherein the gasket is configured as an oil pan gasket or as an exhaust gas gasket.

18. A fuel line produced using an elastomer material in accordance with claim 7.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0043] FIG. 1 shows heat compression sets for Example 2A and Example 2B as a function of the storage time.

DETAILED DESCRIPTION OF THE INVENTION

Examples

Example 1

[0044] According to a first example, various exemplary compositions are used on the basis of an AEM elastomer of 50 parts by weight Vamac G and 50 parts by weight Vamac ULTRA IP (=together 100 parts by weight elastomer; both materials obtainable from DuPont) with 55 phr filler in the form of carbon black N772 as well as various cross-linking agent compositions as listed in detail in the following Table 1.

[0045] Further, all exemplary formulas contain the following additives:

[0046] 1 phr stearic acid as processing aid

[0047] 15 phr plasticiser (Bisoflex T810T, trimellitic acid ester CAS 67989-23-5),

[0048] 1 phr polyoxyethylene octadecyletherphosphate (VANFRE VAM; CAS 62362-49-6) as internal release agent,

[0049] 0.5 phr octadecylamine as flow aid, and

[0050] 2 phr dicumyl diphenylamine (CAS 10081-67-1; obtainable as Dusantox 86 from Duslo a.s.) as antioxidant.

[0051] The Vulcofac ACT66 (obtainable from Safic-Alcan) contains, in addition to the accelerator DBU (amount by weight 52.5%) 2-pyrrolidone as an activator in an amount of 17.5% by weight.

TABLE-US-00001 TABLE 1 Example 1A 1B 1C 1D Vulcofac ACT66 [phr] 1.5 2.0 3.0 (DBU content) [phr] () (0.788) (1.05) (1.575) (2-pyrrolidone content) [phr] () (0.263) (0.35) (0.525) Aliphatic amine 6.0 3.0 2.0 BHTAA 50% [phr] (BHTAA content) [phr] (3.0) (1.5) (1.0) () HMDC 70% by weight [phr] 2.3 2.3 2.3 2.3 (HMDC content) [phr] (1.61) (1.61) (1.61) (1.61)

[0052] After mixing the composition ingredients, the elastomer materials thus obtained were subject to cross-linking on a test plate press at 180 C. for 10 min and a pressure of 180 bar and then a pressureless post-tempering in the convection oven at 185 C. for 3 h and processed to test pieces.

[0053] The measurement values for the Shore hardness A, the elongation at break, and the heat compression set were determined and are contained in the following Table 2.

TABLE-US-00002 TABLE 2 Example 1A 1B 1C 1D Shore hardness A 53.8 56.9 57.3 59.2 Elongation at break [%] 385 327 311 271 Heat compression set [%] 30.2 26.8 25.0 26.0

[0054] The shore hardness A was determined according to DIN EN ISO 868 and the elongation at break in accordance with DIN 53504S2.

[0055] The heat compression set was measured according to ISO 815, Part 1 and 2 (test piece type B) after storage for 24 h at 150 C. in hot air with a compressive deformation path of 25% (in relation to the test piece thickness) after demolding in the cold state at 23 C. The measurement of the thickness of the test pieces took place 30 min after the demolding.

[0056] As the comparison of the data from Examples 1A and 1D (reference) to the data from the Examples 1B and 1C in accordance with the invention shows, good, balanced data both for the elongation at break and for the heat compression set result in the case of cross-linking agent compositions in accordance with the invention, while with the Reference Example 1A, one does indeed observe a very good elongation at break, but a higher heat compression set as well as a lower Shore hardness A.

Example 2

[0057] According to a second example, the exemplary compositions contain an AEM elastomer of 100 parts by weight Vamac G and a high filler amount in the form of carbon black N772 (75 phr) and carbon black N550 (15 phr), i.e., in the sum of in total 90 phr, as well as cross-linking agent compositions as listed in detail in the following Table 3.

[0058] Further, all exemplary formulations contain the following additives:

[0059] 2 phr stearic acid as processing aid,

[0060] 15 phr plasticiser (Bisoflex T810T, trimellitic acid ester CAS 67989-23-5),

[0061] 1 phr polyoxyethylene octadecyletherphosphate (VANFRE VAM; CAS 62362-49-6) as internal release agent,

[0062] 0.5 phr octadecylamine as flow aid, and

[0063] 2 phr dicumyl diphenylamine (CAS 10081-67-1; obtainable as Dusantox 86 from Duslo a.s.) as antioxidant.

[0064] The Vulcofac ACT66 (obtainable from Safic-Alcan) contains, in addition to the accelerator DBU (amount by weight 52.5%), 2-pyrrolidone as an activator in an amount of 17.5% by weight.

[0065] After mixing the composition ingredients, the elastomer materials thus obtained were subject to cross-linking on a test plate press at 180 C. for 10 min and a pressure of 180 bar and then a pressureless post-tempering at 185 C. for 3h in the convection oven and processed to test pieces.

TABLE-US-00003 TABLE 3 Example 2A 2B Vulcofac ACT66 [phr] 3 (DBU content) [phr] (1.575) () (2-pyrrolidone content) [phr] (0.525) () Aliphatic amine BHTAA 50% [phr] 6.0 (BHTAA content) [phr] () (3.0) HMDC 70% [phr] 2.5 2.5 (HMDC content) [phr] (1.75) (1.75) Shore hardness A 78.1 70.5 Elongation at break [%] 164 239

[0066] The data for the Shore hardness A and the elongation at break are specified in Table 3. The Shore hardness A was again determined in accordance with DIN EN ISO 868 and the elongation at break in accordance with DIN 53504S2.

[0067] The heat compression set was determined in accordance with ISO 815, Part 1 and 2 (test piece type B) after a storage at 175 C. in hot air with a compressive deformation path of 25% (in relation to the test piece thickness) after the demolding in the hot state. The measurement of the thickness of the test pieces took place 30 min after the demolding at 23 C. The values for the heat compression sets thus achieved in the long-term test are depicted in FIG. 1 as a function of the storage time.

[0068] In the reference composition 2A, the heat compression set is significantly and, above all, long-lastingly lower than in the reference composition 2B, wherein the reference formulation 2B has a significantly higher elongation at break.

[0069] This shows, as Examples 1A to 1D have already shown, the advantages of compositions balanced in accordance with the invention, which contain both a secondary and/or tertiary aliphatic amine (e.g. BHTAA) and an accelerator of the DBU type together with the pyrrolidone activator (e.g. in the form of Vulcofac ACT 66). For the data regarding the Shore hardness A, the elongation at break, and the heat compression set are between the extremes of the Examples 2A and 2B in formulas in accordance with the invention.

[0070] Example 2 shows that even if very high filler contents are present in the elastomer material (presently 90 phr), advantageously balanced properties are achievable. As expected, these advantages are also given for the compression set in the case of a demolding in the hot state.

[0071] The smaller elongation at break values in the case of composition 2A are able to be compensated by a convergence of the composition with the composition 2B through the addition in accordance with the invention of an amount of a secondary and/or tertiary amine (e.g. BHTAA). For this purpose, the secondary and/or tertiary amine is preferably used in the elastomer material in an amount of about 0.1 phr to about 2.9 phr, further preferably of about 1 phr to about 1.5 phr.

[0072] A balanced ratio of, e.g., BHTAA as aliphatic amine, on the one hand, and, e.g., ACT66 (DBU amount and pyrrolidone component), on the other hand, lead to the optimal compromise of low heat compression set values and high elongation at break values, as is apparent from Examples 1B and 1C. Such optimal results are, in accordance with the invention, also achievable with the high filler contents and the correspondingly high Shore hardness A values of Examples 2A and 2B with corresponding amounts of the DBU accelerator, the pyrrolidone activator, and the aliphatic amine component.