Rubber compounds containing polymeric bis-succinimide...

Details Rubber compounds containing polymeric bis-succinimide... Rubber compounds containing polymeric bis-succinimide...

1999-06-25

2001-01-16

Short, Patricia A. (Department: 1712)

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

Synthetic resins

From carboxylic acid or derivative thereof

C528S322000, C528S389000, C548S544000, C548S545000

Reexamination Certificate

active

06174989

ABSTRACT:

BACKGROUND OF THE INVENTION
Monosuccinimide derivatives have been used as additives in the sulfur vulcanization of rubber. Such monosuccinimide derivatives are disclosed as imparting anti-reversion and antifatigue properties in the rubber. See CA 96-483926/48, Sep. 20, 1996.
PCT/EP95/05177, International Publication Number WO 96/20246 discloses sulfur-vulcanized rubber. compositions containing bis-succinimide compounds. Use of these bis-succinimide compounds impart antireversion and/or accelerating properties in the rubber.
SUMMARY OF THE INVENTION
The present invention relates compounds containing polymeric bis-succinimide polysulfides of the formula:
wherein R is selected from the group consisting of phenylene and xylylene; R
1
is selected from the group consisting hydrogen and alkyls having from 1 to 18 carbon atoms; x is an integer of from 2 to 8 and y is an integer of from 2 to 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention also relates to a vulcanized rubber composition comprising a sulfur-vulcanized rubber and from 0.1 to 10 phr of a polymeric bis-succinimide polysulfide of the formula:
wherein R is selected from the group consisting of phenylene and xylylene; R
1
is selected from the group consisting hydrogen and alkyls having from 1 to 18 carbon atoms; x is an integer of from 2 to 8 and y is an integer of from 2 to 10.
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 “imide” compound with sulfur. Representative of suitable “imide” compounds which may be used include N,N′-o-phenylenedicitraconamide;
N,N′-m-phenylenedicitraconamide;
N,N′-p-phenylenedicitraconamide;
N,N′-o-xylylenedicitraconamide;
N,N′-m-xylylenedicitraconamide;
N,N′-p-xylylenedicitraconamide; and the ortho, meta and para isomers of N,N′-phenylenedimethylmaleimide;
N,N′-xylylenedimethylmaleimide;
N,N′-phenylenediethylmaleimide;
N,N′-xylylenediethylmaleimide;
N,N′-phenylenedipropylmaleimide;
N,N′-xylylenedipropylmaleimide;
N,N′-phenylenedibutylmaleimide;
N,N′-xylyenedibutylmaleimnide;
N,N′-phenylenedipentylmaleimide;
N,N′-xylylenedipentylmaleimide;
N,N′-phenylenedihexylmaleimide;
N,N′-xylylenedihexylmaleimide;
N,N′-phenylenediheptylmaleimide;
N,N′-xylylenediheptylmaleimide;
N,N′-phenylenedioctylmaleimide;
N,N′-xylylenedioctylmaleimide;
N,N′-phenylenedinonylmaleimide;
N,N′-xylylenedinonylmaleimide;
N,N′-phenylenedidecylmaleimide;
N,N′-xylylenedidecylmaleimide;
N,N′-phenylenediundecylmaleimide;
N,N′-xylylenediundecylmaleimide;
N,N′-phenylenedidodecylmaleimide;
N,N′-xylylenedidodecylmaleimide;
N,N′-phenyleneditridecylmaleimide;
N,N′-xylyleneditridecylmaleimide;
N,N′-phenylenedetetradecylmaleimide;
N,N′-xylyleneditetradecylmaleimide;
N,N′-phenylenedipentadecylmaleimide;
N,N′-xylylenedipentadecylmaleimide;
N,N′-phenylenedihexadecylmaleimide;
N,N′-xylylenedihexadecylmaleimide;
N,N′-phenylenediheptadecylmaleimide;
N,N′-xylylenediheptadecylmaleimide;
N,N′-phenylenedioctadecyl; and
N,N′-xylylenedioctadecylmaleimide.
The preferred imides are the N,N′-xylenedicitraconamides.
The imide is reacted with sulfur, S
8
, under suitable conditions to form the polymeric bis-succinimide polysulfide. The imide may be reacted with sulfur in a variety of mole ratios. Generally, the mole ratio of the imide to the sulfur ranges from about 1:1 to about 1:10 with a range of from about 1:2 to about 1:4 being preferred.
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 imide to sulfur is used, the lower integers for x are realized. When a lower mole ratio of imide to sulfur is used, the higher integers for x are realized.
In accordance with Formula I, y is an integer of from 2 to 10. The term “polymeric” is used herein to describe the “polymeric” bis-succinimide polysulfides where y is at least 2 (namely, the unit defined within the brackets of Formula I), repeat at least twice with a sulfur bridge (S
2
to S
8
), linking the repeating units. Preferably, y is from 2 to 4. The reaction conditions conducive to producing polysulfides where y is a lower integer are shorter reaction times and lower reaction temperatures. The reaction conditions conducive to producing polysulfides when y is a higher integer are longer reaction times and higher reaction temperatures.
An organic solvent may be used to dissolve the imide. The solvent is preferably inert to the reaction between the imide and the sulfur. 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 tetrahydropyran, diethylether, 1,2-dimethoxybenzene, 1,2-diethoxybenzene, the mono- and 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 imide compound and not interfere with the reaction.
The reaction between the imide and the sulfur to form the polymeric bis-succimide polysulfides 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 50° C. to 200° C. The preferred temperature range is from about 120° C. to 150° C., while the most preferred temperature range is from about 135° C. to 145° C.
The reaction pressure to form the polymeric bis-succimide polysulfides is not deemed to be critical. Pressures ranging from about 0 kPa to 689 kPa may be used.
The process for the preparation of the polymeric bis-succimide 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 polymeric bis-succinimide polysulfides improve the rheometer antireversion properties of “sulfur-vulcanized elastomers or rubbers.” The term “sulfur-vulcanized 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 homopolyme

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