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Process for degrading nitrile rubbers in the presence of catalysts having an increased activity

a technology of nitrile rubber and catalyst, which is applied in the direction of physical/chemical process catalyst, organic compound/hydride/coordination complex catalyst, metal/metal-oxide/metal-hydroxide catalyst, etc., can solve the problems of severe restrictions on the processing ability of hnbr, steep increase, and substantial alteration of the microstructure of the polymer, etc., to achieve the effect of increasing the reaction ra

Inactive Publication Date: 2012-05-10
LANXESS DEUTDCHLAND GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The process enables the production of nitrile rubbers with lower molecular weights and narrower distributions, improving processability and reducing catalyst usage, while maintaining comparable noble metal content.

Problems solved by technology

The processability of HNBR is subject to severe restrictions as a result of the relatively high Mooney viscosity.
However, this thermomechanical degradation has the disadvantage that functional groups such as hydroxyl, keto, carboxyl and ester groups, are incorporated into the molecule as a result of partial oxidation and, in addition, the microstructure of the polymer is substantially altered.
The preparation of HNBR having low molar masses corresponding to a Mooney viscosity (ML 1+4 at 100° C.) in the range below 55 or a number average molecular weight of about Mn<200 000 g / mol was for a long time not possible by means of established production processes since, firstly, a steep increase in the Mooney viscosity occurs in the hydrogenation of NBR and, secondly, the molar mass of the NBR feedstock used for the hydrogenation cannot be reduced at will since otherwise the work-up can no longer be carried out in the industrial plants available because the product is too sticky.
However, the catalysts mentioned are not necessarily suitable for carrying out the degradation of nitrile rubber.
However, the amounts of Grubbs (I) catalyst employed for carrying out the metathesis are large.
However, the amounts of ruthenium necessary for this efficient metathetic degradation are still relatively high.

Method used

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  • Process for degrading nitrile rubbers in the presence of catalysts having an increased activity
  • Process for degrading nitrile rubbers in the presence of catalysts having an increased activity
  • Process for degrading nitrile rubbers in the presence of catalysts having an increased activity

Examples

Experimental program
Comparison scheme
Effect test

examples

Metathetic Degradation of Nitrile Rubber in the Presence of Various Ru Catalysts

[0140]In the following examples, it is shown that, in each case at the same amount of ruthenium, the metathesis activity of the catalysts of the general structural formula (I) is higher than when the Grubbs II catalyst is used.

[0141]The following catalysts were used:

“Hoveyda Catalyst” (According to the Invention)

[0142]

[0143]The Hoveyda catalyst was procured from Aldrich under the product number 569755.

“Grela Catalyst” (According to the Invention)

[0144]

[0145]The Grela catalyst was prepared by the method published in J. Org. Chem, 2004, 69, 6894-6896.

Grubbs II Catalyst (Comparison)

[0146]

[0147]The Grubbs II catalyst was procured from Materia (Pasadena / Calif.).

[0148]The degradation reactions described below were carried out using the nitrile rubber Perbunan® NT 3435 from Lanxess Deutschland GmbH. This nitrile rubber had the following characteristic properties:

Acrylonitrile content: 35% by weightMooney viscos...

example series 1-3

Activity Comparison of the “Hoveyda Catalyst” with the “Grubbs II Catalyst” in the Presence of 2 phr of 1-Hexene

[0155]In the example series 1 and 2, the activity of the “Hoveyda catalyst” was compared with that of the “Grubbs II catalyst” at two ruthenium contents (23.8 ppm and 161.4 ppm). These activity comparisons were carried out using 2.0 phr of 1-hexene.

[0156]In example series 3, the metathetic degradation was carried out using the “Hoveyda catalyst” at a ruthenium addition of 8.6 ppm and an amount of 1-hexene of 2.0 phr.

example 1.1 (

According to the Invention)

[0157]

“Hoveyda catalyst” using 161 ppm of ruthenium and 2.0 phr of 1-hexene“Hoveyda catalyst”NBR(MW = 626.14 g / mol)1-HexeneTemper-Amount Amount AmountRuAmountAmountature[g][mg][phr][ppm][g][phr][° C.]40400.1161.40.82.023“Hoveyda catalyst” / Reaction timeAnalytical [min.]data03060185425Mw 24022161413[kg / mol]Mn 10014121010[kg / mol]PDI2.41.571.331.401.30

[0158]The degraded nitrile rubbers obtained in Example 1.1 were gel-free.

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Abstract

A process of degrading nitrile rubbers comprises subjecting them to a metathesis reaction in the presence of specific catalysts with increased activity.

Description

[0001]This application is a continuation of U.S. patent application Ser. No. 11 / 707,423 filed Feb. 16, 2007, pending, incorporated herein by referenceFIELD OF THE INVENTION[0002]The present invention relates to a process for degrading nitrile rubbers by subjecting such nitrile rubbers to a metathesis reaction in the presence of specific catalysts.BACKGROUND OF THE INVENTION[0003]The term nitrile rubber, also referred to as “NBR” for short, refers to rubbers which are copolymers or terpolymers of at least one α-β-unsaturated nitrile, at least one conjugated diene and, if desired, one or more further copolymerizable monomers.[0004]Hydrogenated nitrile rubber, also referred to as “HNBR” for short, is produced by hydrogenation of nitrile rubber. Accordingly, the C═C double bonds of the copolymerized diene units have been completely or partly hydrogenated in HNBR. The degree of hydrogenation of the copolymerized diene units is usually in the range from 50 to 100%.[0005]Hydrogenated nitri...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C08F236/06
CPCC08C19/02C08C2019/09C08C19/08B01J31/22B01J31/02B01J23/46
Inventor OBRECHT, WERNERONG, CHRISTOPHERMULLER, JULIA MARIANUYKEN, OSKAR
Owner LANXESS DEUTDCHLAND GMBH