Übersetzung für "Scorch time" in Deutsch

Products C and D according to the invention produce virtually no shortening of the scorch time compared with A.

The scorch time (for example t5) is intended to be relatively long, depending on the shaping process.

The scorch time is almost doubled compared with reference mixture 3.

Although these accelerators improve reversion, they undesirably shorten the scorch time.

Another disadvantage is that they limit the scorch time and hence the time available for processing the polymer compounds containing them.

Although the rubber obtained is gel-free and very light in colour, it has the very low scorch time according to Mooney (MS/t5) at 120° C. of 8 minutes.

A further disadvantage is found in the fact that these age protection agents appreciably restrict the scorch time and thereby the processing time of the polymer compositions which contain them.

The vulcanisation behaviour (scorch time t90, maximum torque) was measured using an MDR 2000 Rheometer (supplied by Flexsys).

These results show the excellent effectiveness of the distillation residue from industrial trimethylolpropane production in terms of reducing the mixing viscosity (measured as ML 1+4) and extending the processability (measured as Mooney scorch time) of the rubber mixture while at the same time giving a high level of mechanical properties of the vulcanisates.

The object of the present invention was therefore to find less expensive additives which greatly increase the flowability of rubber mixtures and increase the scorch time without exhibiting the disadvantages of the additives used up to the present, as described above.

In this case, combination with a compound corresponding to formula (II) leads only to an unwanted reduction in the scorch time whereas complete vulcanization is actually extended.

The combination with a compound corresponding to formula (II) (diphenyl guanidine) leads to a further unacceptable reduction in the scorch time (Comparison 5).

Accordingly, the object of the present invention is to provide a vulcanisation system which increases the resistance to reversion of rubber vulcanisates and, at the same time, does not shorten the scorch time during their vulcanisation.

The treated NR contained higher protein content leading to not only the reductions of scorch time and optimum cure time, but also the enhanced mechanical properties of the vulcanizate.

The silica-containing rubber mixture according to claim 1, where a loss factor tan delta of a vulcanizate produced therefrom by heating at 170° C./t95 is less than 0.17 at 60° C., and a scorch time of the vulcanizate is simultaneously greater than 1000 seconds.

The silica-containing rubber mixture according to claim 1, wherein a loss factor tan delta of a vulcanizate produced therefrom by heating at 170° C./t95 is less than 0.17 at 60° C., and its scorch time is simultaneously greater than 1000 seconds.

Emphasis is furthermore placed on the high productivity of the production process due to high polymerization conversions of more than 75%, preferably more than 80%, the high vulcanization rate in the vulcanization with sulphur or peroxides, in particular for NBR-types for injection moulding, a short scorch time of the nitrile rubbers and a high crosslinking density.

The crosslinking of rubbers with use of sulphur-accelerator systems generally has the advantage that processing properties and product properties can be varied widely by using different accelerators and combinations of these, an example being adjustment of induction period (scorch time) and of reaction rate.

The present invention is based on the object of providing substantially diphenylguanidine-free rubber mixtures, where this means mixtures comprising at most 1 phr, preferably less than 0.7 phr, particularly preferably less than 0.4 phr, and very particularly preferably less than 0.1 phr, of diphenylguanidine, where the performance properties, in particular the scorch time (MS-t5), Mooney viscosity, elongation at break, tensile strength, hardness and abrasion are not substantially poorer than those of diphenylguanidine-containing mixtures.

It is preferable that the loss factor tan delta of a vulcanizate produced from the silica-containing rubber mixture by heating at 170° C./t95 is less than 0.17 at 60° C. and that its scorch time is simultaneously greater than 1000 seconds.

It is preferable that the scorch time of a vulcanizate produced from the silica-containing rubber mixture by heating at 170° C./t95 is greater than 1000 seconds and that its full vulcanization time is simultaneously less than 2000 seconds.

In combination therewith, the inventive rubber mixtures can also achieve a vulcanization time of less than 2000 seconds, and particularly preferably a scorch time of from 500 to 1000 seconds.

A scorch time that is advantageous for practical purposes is mostly more than 300 seconds, and when minimization of processing risk and the cost of time are taken into account this should be less than 1000 seconds.

1 — It has been found that additives of the formula (I) lead to rubber mixtures with markedly reduced rubber viscosity (Mooney viscosity), and to vulcanizates with markedly increased scorch time together with reduced full vulcanization time.

For purposes of good processability, a rubber mixture should exhibit not only low viscosity (Mooney viscosity ML 1+4/100° C.) but also a vulcanization process that begins slowly (long scorch time), while the full vulcanization process that follows, with exposure to heat, should proceed as rapidly as possible, so that short production cycles and low energy costs can be achieved.