Elastomer containing combination of tris(nonyl phenyl) phosphite and tetramethylethylenediamine, preparation and compositions and articles of manufacture thereof

Abstract

This invention relates to compositions comprised of diene-based elastomers containing an antioxidant comprised of a combination of tris(nonyl phenyl) phosphite (TNPP) and tetramethylethylene diamine (TMEDA). The invention further relates a rubber composition and to a polystyrene composite containing such elastomer compositions. The invention additionally relates to articles of manufacture thereof, including tires and polystyrene based articles. In one embodiment, the invention relates to a process of recovery of diene-based elastomer(s) from an organic solvent solution thereof by steam stripping the organic solvent therefrom in the presence of a combination of the TNPP and TMEDA.

Claims

1. A process of preparing a polystyrene composite comprising the step of polymerizing styrene in the presence of an elastomer composite comprised of diene-based elastomer containing an antioxidant comprised of a combination of tris(nonyl phenyl) phosphite (TNPP) and tetramethylethylene diamine (TMEDA) in a weight ratio of TNPP to TMEDA in a range of from about 4/1 to about 50/1.

2. The process of claim 1 wherein said diene-based elastomer is at least one of polybutadiene and polyisoprene.

Description

EXAMPLE I

(1) An evaluation of treatment of tris(nonyl phenyl) phosphite (TNPP) is undertaken to determine if hydrolytic stability of TNPP can be promoted at elevated temperatures.

(2) For such evaluation, tetramethylethylenediamine (TMEDA) is selected for combination with the TNPP to promote the resistance of the TNPP to hydrolysis.

(3) For the evaluation undertaken by this Example, samples comprised of 3.5 grams of TNPP were blended 30 grams of an organic solvent as hexane in small glass bottles.

(4) Sample A was a solvent mixture of the TNPP and organic solvent, provided as hexane.

(5) Sample B was the hexane solvent mixture of the TNPP and 0.3 grams of TMEDA.

(6) Sample C was the hexane solvent mixture of the TNPP and 0.6 grams of TMEDA.

(7) Sample D was the hexane solvent mixture of the TNPP and 0.05 grams of H3PO4

(8) Each Sample also included 40 grams of water to provide exposure of the TNPP to water.

(9) The glass bottles containing the samples were capped and placed in a tumbling water bath held at 90 C. for a period of 6 hours. Aliquots were periodically taken from each of the Samples over a period of about two hours to monitor the extent of degradation of the TNPP by hydrolysis. Degradation of the TNPP by hydrolysis was evidenced to evolution of nonyl phenol as a product of such degradation of the TNPP as analyzed by high performance liquid chromatography (referred to herein as HPLC). The extent of TNPP degradation is relative to the nonyl phenol detected by the analysis. The TNPP is reported herein as being completely hydrolytically degraded if (or when) a quantitative amount or nonyl phenol is detected.

(10) The results of the evaluation are reported in the following Table 1.

(11) TABLE-US-00001 TABLE 1 Samples Comprised of 3.5 g TNPP, 30 g solvent, 40 g water) Added Ingredients Level of Degradation (A) None complete hydrolytic degradation after 2-3 hours (B) 0.3 g TMEDA hydrolytic degradation not observed (N/D) (C) 0.6 g TMEDA hydrolytic degradation not observed (N/D) (D) 0.05 g H.sub.3PO.sub.4 complete hydrolytic degradation after 2-3 hours

(12) It is concluded that this evaluation illustrates that an addition of TMEDA to a solvent and water mixture containing TNPP significantly increased the hydrolytic stability of the TNPP in such medium, particularly for Samples B and C for which hydrolytic degradation was not observed.

EXAMPLE II

(13) After the successful promotion of hydrolytic stability of the TNPP in a solvent/water medium by addition of the TMEDA was observed in Example I, an evaluation of hydrolytic stability of TNPP was undertaken where the TNPP was contained in a polymerizate comprised of polybutadiene rubber and organic solvent, namely hexane, used for its formation by polymerization of 1,3-butadiene monomer in the presence of the solvent and a catalytic initiator from which the polybutadiene rubber is recovered by steam stripping the solvent from the polymerizate.

(14) The polybutadiene rubber was prepared by polymerization of 1,3-butadeiene monomer in the presence of a nickel catalyst in an organic solvent, namely hexane, solution. Exemplary of such polymerization may be found, for example, in U.S. Pat. No. 5,451,646 which illustrates nickel catalyzed polymerization of 1,3-butadiene monomer with a catalyst system comprised of, for example, a combination of an organonickel compound (e.g. nickel salt of a carboxylic acid), organoaluminum compound (e.g. trialkylaluminum) and fluoride containing compound (e.g. hydrogen fluoride or complex thereof).

(15) The polymerization was conducted in a series of continuous polymerization reactors stabilized by an inclusion of 0.7 phr of the TNPP (together with 0.25 phr of a normally included antioxidant for the TNPP) for which it was observed in Example I that the TMEDA provided a suitable hydrolytic stability of TNPP at an elevated temperature.

(16) Steam stripping was utilized to remove the solvent from the resultant polymerizate, which might be referred to as cement, the for recovery of the polybutadiene rubber. For the steam stripping operation, a tank was provided with water which was brought to about 90 C. temperature by steam injection into the water. To the heated water, the polymerizate, or cement, was slowly added. When the cement addition was complete, the steam injection into the water was allowed to continue for about an additional 20 minutes to drive out the solvent and any residual volatiles. The temperature was reduced to about 60 C. to about 70 C. by addition of water at ambient temperature. The polybutadiene in the tank was physically reduced to a form of rubber crumbs by the stripping process. The rubber crumbs were fed to a dewatering apparatus which is similar to a single screw rubber extruder. The resultant moisture content of the rubber crumbs was about 1 to about 5 weight percent. The wet recovered rubber crumbs were placed in a hot air oven for about 24 hours which was maintained at about 60 C. The resulting moisture in the recovered rubber crumbs was about 0.5 weight percent.

(17) A sample of the recovered rubber crumbs was analyzed by HPLC to report residual ingredients reported in the following Table 3 in terms of phr (parts by weight per 100 parts of rubber). The nonyl phenol is a degradation product of hydrolysis of TNPP.

(18) TABLE-US-00002 TABLE 3 phr included in Ingredients phr recovered the polymerization Nonyl phenol 0 (none detected) 0 TNPP 0.52 0.7 Antioxidant for the TNPP.sup.1 0.27 0.25 .sup.1antioxidant for the TNPP as octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl-propionate

(19) It is apparent that some degradation, or loss, of the TNPP occurred since 0.52 phr was recovered from 0.7 phr originally introduced. However, no detectable hydrolysis of the TNPP was observed since the presence of nonyl phenol (a product which would have been resulted from degradation of the TNPP by hydrolysis) was not detected.

(20) Therefore, it is concluded that an inclusion of the of the TMEDA in the TNPP containing solution polymerization of 1,3-butadiene monomer to form the polybutadiene rubber from which the rubber is recovered from its polymerizate (cement) by steam stripping at an elevated temperature (e.g. 98 C.) to remove the solvent provided a hydrolytic stability of the TNPP.

EXAMPLE III

(21) An experiment was undertaken in the manner of Example II to evaluate the hydrolytic stability of the TNPP in the steam stripping operation of the solvent-containing polybutadiene polymerizate at the elevated temperature without the inclusion of the TMEDA. A sample of the recovered rubber crumbs was analyzed by HPLC with residual ingredients reported in the following Table 3 in terms of phr (parts by weight per 100 parts of rubber). The nonyl phenol is a degradation product of hydrolysis of TNPP.

(22) TABLE-US-00003 TABLE 4 phr included in Ingredients phr recovered the polymerization nonylphenol 0.45 0 antioxidant for the TNPP.sup.1 0.19 0.25 TNPP 0.33 0.7 .sup.1Antioxident for the TNPP as octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl-propionate

(23) It is apparent from the indicated formation of the nonyl phenol and significant reduction of the TNPP that that a considerable hydrolysis degradation of the TNPP occurred.

(24) Therefore, it is concluded that it was verified that hydrolytic stability of the TNPP (reported in Example II) is promoted by the inclusion of the of the TMEDA in the TNPP containing solution polymerization of 1,3-butadiene monomer to form the polybutadiene rubber from which the rubber is recovered from its polymerizate (cement) by steam stripping at an elevated temperature (e.g. about 92 C.) to remove the solvent.

(25) While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.