Rubber compounds containing aromatic ketone polysulfides

Details Rubber compounds containing aromatic ketone polysulfides Rubber compounds containing aromatic ketone polysulfides

1999-11-11

2001-08-21

Henderson, Christopher (Department: 1713)

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

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

Reexamination Certificate

active

06277926

ABSTRACT:

BACKGROUND OF THE INVENTION
U.S. Pat. 4,894,409 discloses the use of 4,4′-bis-(dimethylamino)benzophenone as a polymer terminal molding agent.
U.S. Pat. 4,555,547 relates to a rubber composition containing a polybutadiene rubber that has a benzophenone compound bonded to a carbon atom of the polybutadiene molecular chain. An example of such a benzophenone compound is 4,4′-bis(alkyl-substituted amino)benzophenone.
U.S. Pat. 4,555,548 relates to a rubber composition containing a styrene-butadiene copolymer rubber and having bonded to a carbon atom of the rubber molecular chain a chemical moiety derived from a benzophenone compound. An example of such a benzophenone compound is 4,4′-bis(alkyl-substituted amino)benzophenone.
SUMMARY OF THE INVENTION
The present invention relates aromatic ketone polysulfides of the formula:
wherein R is selected from the group consisting of alkyls having from 1 to 18 carbon atoms and x is an integer of from 2 to 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention also relates to a rubber composition containing from 0.1 to 10 phr of an aromatic ketone polysulfide of the formula:
wherein R is selected from the group consisting of alkyls having from 1 to 18 carbon atoms and x is an integer of from 2 to 8. Preferably, R is an alkyl of from 1 to 2 carbon atoms and x is an integer of from 2 to 4.
In addition, there is disclosed a method for processing rubber comprising mixing with a rubber from 0.1 to 10 phr of an aromatic ketone polysulfide of the formula
wherein R is selected from the group consisting of alkyls having from 1 to 18 carbon atoms and x is an integer of from 2 to 8.
The polysulfides used in the present invention may be present at various levels in the rubber compounds of the present invention. For example, the level may range from about 0.1 to 10.0 parts by weight per 100 parts by weight of rubber (also known as “phr”). Preferably, the level ranges from about 0.5 to about 5.0 phr.
The polysulfides may be prepared by reacting a suitable bis(alkylamino)benzophenone with a sulfur compound. Representative of suitable bis(alkylamino)benzophenone compounds which may be used include the 3,3′, 3,4 and 4,4′ isomers of
bis(dimethylamino)benzophenone,
bis(diethylamino)benzophenone,
bis(dipropylamino)benzophenone,
bis(dibutylamino)benzophenone,
bis(dipentylamino)benzophenone,
bis(dihexylamino)benzophenone,
bis(dihexylamino)benzophenone,
bis(dioctylamino)benzophenone,
bis (dinonylamino)benzophenone
bis(didecylamino)benzophenone,
bis(diundecylamino)benzophenone,
is (didodecylamino)benzophenone
bis(ditridecylamino)benzophenone,
bis(ditetradecylamino)benzophenone,
bis(dipentadecylamino)benzophenone,
is(dihexadecylamino)benzophenone,
bis(diheptadecylamino)benzophenone and
bis(dioctadecylamino)benzophenone.
Representative examples of sulfur compounds which may be used include sulfur monochloride and sulfur dichloride. Preferably, the sulfur compound is sulfur monochloride.
The bis(alkylamino)benzophenone is reacted with a sulfur compound under suitable conditions to form the polysulfide of the formula. The bis(alkylamino)benzophenone may be reacted with sulfur in a variety of mole ratios. Generally, the mole ratio of the bis(alkylamino)benzophenone to the sulfur ranges from about 1.0:0.5 to about 1.0:10.0 with a range of from about 1.0:6.0 to about 1.0:2.0 being preferred.
When the sulfur compound is halogenated, such as sulfur monochloride, it is preferred to conduct the reaction between the sulfur compound and the bis(alkylamino)benzophenone in the presence of a scavenger or “neutralizer” which does not interfere with the polysulfide formation. Representative examples include triethylamine, pyridines such as methyl pyridine and the like.
In accordance with Formula I, x is an integer of from 2 to 8. Preferably, x is an integer of from 2 to 4. When a higher mole ratio of the benzophenone compound to sulfur is used, the lower integers for x are realized. When a lower mole ratio of benzophenone compound to sulfur is used, the higher integers for x are realized.
The reaction conditions conducive to producing polysulfides where x is a lower integer are shorter reaction times and lower reaction temperatures. The reaction conditions conducive to producing polysulfides when x is a higher integer are longer reaction times and higher reaction temperatures.
An organic solvent may be used to dissolve the benzophenone compound. The solvent is preferably inert to the reaction between the bis(alkylamino)benzophenone and the sulfur compound. Illustrative of solvents suitable for use in the practice of this invention include: saturated and aromatic hydrocarbons, e.g., hexane, octane, dodecane, naphtha, decalin, tetrahydronaphthalene, kerosene, mineral oil, cyclohexane, cycloheptane, alkyl cycloalkane, benzene, toluene, xylene, alkyl-naphthalene, and the like; acetone; ethers such as tetrahydrofuran, tetrahydropyran, diethylether, 1,2-dimethoxybenzene, 1,2-diethoxybenzene, the dialkylethers of ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, oxyethyleneoxypropylene glycol, and the like; fluorinated hydrocarbons that are inert under the reaction conditions such as perfluoroethane, monofluorobenzene, and the like. Another class of solvents are sulfones such as dimethylsulfone, diethylsulfone, diphenolsulfone, sulfolane, and the like. Mixtures of the aforementioned solvents may be employed so long as they are compatible with each other under the conditions of the reaction and will adequately dissolve the bis(alkylamino)benzophenone compound and not interfere with the reaction.
The reaction between the bis(alkylamino)benzophenone and the sulfur compound to form the aromatic ketone polysulfides is exothermic and may be conducted over a wide temperature range. The temperature may range from moderate to an elevated temperature. In general, the reaction may be conducted at a temperature of between about 0° C. to 150° C. The preferred temperature range is from about 50° C. to 120° C., while the most preferred temperature range is from about 80° C. to 100° C.
The reaction pressure to form the aromatic ketone polysulfides is not deemed to be critical. Pressures ranging from about 0 kPa to 689 kPa may be used.
The reaction is preferably conducted in a nitrogen atmosphere.
The process for the preparation of the aromatic ketone polysulfides may be carried out in a batch, semi-continuous or continuous manner. The reaction may be conducted in a single reaction zone or in a plurality or reaction zones, in series or in parallel. The reaction may be conducted intermittently or continuously in an elongated tubular zone or in a series of such zones. The material of construction of the equipment should be such as to be inert during the reaction. The equipment should also be able to withstand the reaction temperatures and pressures. The reaction zone can be fitted with internal and/or external heat exchangers to control temperature fluctuations. Preferably, an agitation means is available to ensure the uniform reaction. Mixing induced by vibration, shaker, stirrer, rotating, oscillation, etc. are all illustrative of the types of agitation means which are contemplated for use in preparing the composition of the present invention. Such agitation means are available and well known to those skilled in the art.
Use of the aromatic ketone polysulfides improve the polymer-filler interaction of “elastomers or rubbers.” The term “elastomer or rubber” as used herein embraces both vulcanized forms of natural and all its various raw and reclaim forms as well as various synthetic rubbers. The synthetic elastomers include conjugated diene homopolymers and copolymers and copolymers of at least one conjugated diene and aromatic vinyl compound. Representative synthetic polymers include the homopolymerization products of butadiene and its homologues and derivatives, as for example, methyl-butadiene, dimethylbutadiene and pentadiene as well as copolymers, such as those formed from butadiene or its homologues or derivat

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