Reinforcement additives

Details Reinforcement additives Reinforcement additives

1996-10-02

2001-07-31

Dawson, Robert (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C524S261000, C524S265000, C524S420000, C423S449700

Reexamination Certificate

active

06268421

ABSTRACT:

TECHNICAL FIELD
The invention concerns reinforcement additives consisting of oligomeric or polymeric sulfur-containing organoorganooxysilanes, perhaps other unsaturated hydrocarbon-containing organoorganooxysilanes, reinforcing, semiactive, active, and/or highly active carbon blacks, which are common in rubber, and perhaps other known additives, and the preparation and use of the additives in accordance with the invention in vulcanizable, perhaps silicatically [sic] filled rubber mixtures and compositions, and in plastic mixtures, or in carbon black dispersions.
STATE OF THE ART
The use of sulfur-containing organosilanes in silica-filled rubbers to establish a chemical bond between rubber helices and a silica surface has been known for a long time.
Thus, a number of compounds in pure form have been proposed for these uses—for example, 3-mercaptopropyltrimethoxysilane (U.S. Pat. No. 5,126,510; West German Patent No. 2,524,863);, 3-(triethoxysilyl)propylthiocyanate (West German Patent Nos. 2,035,778 and 4,100,217); bis[3-(triethoxysilyl)propyl]tetrasulfide (West German Patent Nos. 2,255,577, 2,447,614, and, 3,305,373; Japanese Patent No. 6 10 04 742), or oligo[(triethoxysilyl)organo]bisoligosulfides (East German Patent No. 299,187; European Patent No. 466,066).
The disadvantage in using these pure silanes is either the insufficient processing reliability due to increased mixing viscosities and the greatly reduced starting and completing vulcanization times or an insufficient reinforcer effect due to excessively low crosslinking densities. Another disadvantage is the difficult metering of the liquid additives and their susceptibility to hydrolysis, which has a negative effect, especially in processing in the rubber industry.
Experiments to use the aforementioned monomeric silanes as mixtures or preparations with silicatic fillers in the rubber, tire, and plastic industries, described, for example, in West German Patent Nos. 2,528,134, 3,314,742, and 3,437,473, fail due to the susceptibility to hydrolysis, instability, or excessively low effectiveness of these mixtures.
A storage-stable silane-silica preparation based on bis[3-(triethoxysilyl) propyl]tetrasulfide is described in European Patent No. 442,143. For the preparation of this mixture, containing only 5 to 15 parts by weight silane, however, long mixing times (>2) and high temperatures (>100° C.) are required.
Furthermore, mixtures of bis[3-(triethoxysilyl)propyl]tetrasulfides and carbon blacks and their use in rubbers have been described in the past. Simple mixtures in the weight ratio of 50 to 50, cited, for example, in West German Patent No. 2,747,277 and U.S. Pat. No. 5,227,425, exhibit rather good reinforcing effects in silica-filled rubber mixtures, but at the same time lead to an impairment of the tear propagation resistance of the vulcanized materials and to a strong decline of the elongation at break due to a more rapid strengthening of the rubber. Furthermore, the silane fraction can be dissolved away completely from the carbon black by extraction, for example, with diethyl ether, which has a negative effect on the stability and effectiveness of the silane-carbon black mixtures.
Silane-carbon black preparations whose silane fraction cannot be dissolved away by extraction are presented in West German Patent Nos. 4,043,537 and 4,119,959. They are suitable only for purely carbon blackfilled rubber mixtures, however, because of their low silane-content (0.4 to 5.5 parts by weight) and are prepared according to an expensive method (temperature>120° C.). Even more expensive methods for the fixing of the monomeric silane bis[3-(triethoxysilyl)propyl]tetrasulfide on carbon blacks by upstream oxidation processes on the carbon black (plasma method, oxidation agents such as H
2
O
2
, nitric acid, ozone) are described in Japanese Patent No. 88 31796 and West German Patent No. 3,813,678. Here too, only one extractable silane fraction of 1 to 5 parts by weight is attained.
All these attempts to improve the rubber-technological characteristics begin with a variation of the carbon black or the treatment of its surface.
DESCRIPTION OF THE INVENTION
The goal of the invention was to prepare new, flowable, odorless, and dust-free reinforcement additives based on oligomeric and/or polymeric, sulfur-containing organoorganooxysilanes and reinforcing, semiactive, active, and/or highly active carbon blacks, common in the rubber, tire, and plastic industries, and a simple method for their preparation.
Another goal of the invention was the implementing of the use of additives in accordance with the invention in vulcanizable, perhaps silicatically filled rubber mixtures and compositions and in plastic mixtures or in carbon black dispersions.
Surprisingly, it was discovered that the aforementioned disadvantages can be overcome if the reinforcement additives consist of oligomeric and/or polymeric sulfur-containing organoorganooxysilanes, perhaps other unsaturated hydrocarbon-containing organoorganooxysilanes, reinforcing semiactive, active, and/or highly active carbon blacks common in rubber, and perhaps other known additives.
The object of the invention concerns reinforcement additives, consisting of
a) 5 to 70, preferably 40 to 60, parts by weight of one or more oligomeric and/or polymeric sulfur-containing organoorganooxysilanes of the following general formula:
wherein R
1
represents saturated and/or unsaturated, branched, and/or unbranched, substituted and /or unsubstituted, at least trivalent hydrocarbons with 2 to 20 carbon atoms, provided that at least two carbon-sulfur bonds are contained; R
2
and R
3
denote, independent of one another, saturated and/or unsaturated, branched and/or unbranched, substituted and/or unsubstituted hydrocarbons with 1 to 20 carbon atoms, halogen, hydroxy, hydrogen, and groups of the following general formula:
wherein R
2
has the definition indicated above and n=1 to 3, m=1 to 1,000, p=1 to 5, q=1 to 3, and x=1 to 8; and
b) 30 to 95, preferably 40 to 60, parts by weight of one or more of the common reinforcing semiactive, active, and/or highly active carbon blacks.
Oligo/poly[4-(2-trialkoxysilylethyl)cyclohexane-1,2-diyl]bisoligosulfides of the following general formula:
wherein R
2
, m, and x have the definitions indicated above, are preferably used as sulfur-containing organoorganooxysilanes.
Moreover, a number of other oligomeric and polymeric, sulfur-containing organoorganooxysilanes can, of course, be used.
Examples of such compounds are the following:
oligo/poly[5-triethoxysilyl)bicyclo[2.2.1]heptane-2, 3-diyl]bisoligosulfides of the following general formula:
oligo/poly[8,9-bis(triethoxysilyl)-endo-tricyclo [5.2.1.0
2.6
]decane-3,4-diyl]bisoligosulfides of the following general formula:
oligo/poly[trialkoxysilyl)alkane-1,2-diyl]bisoligosulfides of the following general formula:
oligo/poly[1-(trimethoxyethoxysilyl)ethane-1,2-diyl]bisoligosulfides of the general formula:
oligo/poly[3,3,5,5-tetraethoxy-4-oxa-3,5-disilaheptane-1,2,6,7-tetrayl]tetrakisoligosulfides of the following general formula:
The values for x are 1 to 8, those for m=1 to 200.
The reinforcement additives in accordance with the invention can contain up to 20 parts by weight of one or more organoorganooxysilanes of the following general formula:
R
4
—Si(OR
2
)
n
R
3
(3−n)
  (V),
wherein R
2
, R
3
, and n have the aforementioned definitions and R
4
represents unsaturated, branched, and/or unbranched, substituted and/or unsubstituted hydrocarbons with 2 to 20 carbon atoms and with at least one double bond of an olefinic or aromatic character.
Compounds of general formula (IV) are, for example, the following:
2-[(3-cyclohexen-1-yl)ethyl]trialkoxysilane,
2-(phenylethyl)trialkoxysilane, and/or,
alkenyltrialkoxysilanes with up to 20 carbon atoms in the alkenyl group,wherein alkoxy=OR
2
with R
2
having the

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