JPS58132034A - Stabilized synthetic rubber composition - Google Patents

Abstract

PURPOSE:The titled composition excellent in heat stability, oxidation stability and thermal discoloration resistance, prepared by adding a specified phenolic compound and sulfur compound to a synthetic rubber. CONSTITUTION:An antioxidant is obtained by mixing a phenolic compound of formula III, prepared by reacting a compound of formulaI(wherein R1 is a 1- 4C alkyl) with a phosphite compound of formula II (wherein R2 is a 1-8C alkyl or phenyl) with a sulfur compound of formula IV (Wherein R is a 4-20C alkyl) in a weight ratio of 2:1-20. Then, 0.1-2pts.wt. above antioxidant is added to 100pts.wt. synthetic rubber (e.g., solution-polymerized polybutadiene).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to synthetic rubber compositions having excellent thermal and oxidative stability.

Synthetic rubber deteriorates due to the action of heat and oxygen during manufacturing, storage, processing, or use, resulting in a severe deterioration of its physical properties accompanied by phenomena such as discoloration, softening, gelation, changes in Mooney viscosity, or exfoliation. Yes (known)

In order to prevent such a phenomenon, various phenol-based, phosphorus-based, sulfur-based, and other antioxidants have been added singly or in combination during the production and processing steps of synthetic rubber.

For example, styrenated phenol, 2,6-di-t-butyl-4-methylphenol, n-octadecyl-β-(
3,5-di-t-butyl-4-hydroxyphenyl)propionate, pentaerythritol-tetrakis [β
-(8゜6-di-t-butyl-4-and-d-b-xyphenyl)propionate] may be used alone, or M and tris(nonylphenyl) phosphorite, di- A combination of phosphorus-based antioxidants such as stearyl pentaerythritol diphosph and aitate, or a combination of the above-mentioned phenolic antioxidants and sulfur-based antioxidants such as dilaurylthiodipropionate and distearylthiodipropionate. A method of using both is known.

However, these methods are still not fully satisfactory in terms of thermal and oxidative stability, thermal discoloration resistance, evaporation resistance, etc.

As a result of various studies in order to solve these problems, the present inventors found that by blending a specific phenolic compound and a specific sulfur compound into synthetic rubber, the present inventors could overcome the conventional combination technology of antioxidants. It has been discovered that a completely unexpected and surprising synergistic effect can be obtained, and what is even more surprising is that it has extremely superior thermal and oxidative stability compared to conventional technology, and is extremely superior in resistance to thermal discoloration. This heading led to the present invention.

That is, the present invention provides synthetic rubber with a compound of the following general formula (1) and a compound of the general formula (I): billion) = 2 = 1 to 20 (I
The object of the present invention is to provide a synthetic rubber composition characterized in that it is blended within the range of ji ratio).

0 (wherein, R1 represents an alkyl group having 1 to 4 carbon atoms, and R
g represents an alkyl group having 1 to 8 carbon atoms or a phenyl group. ) (R-SHIN*OHs -C-0-CHEGYA C(2) (in the formula, represents an alkyl group having 4 to 2 carbon atoms) Oite, R
1 represents an alkyl group having 1 to 4 carbon atoms, and methyl and ethyl groups are preferred from the viewpoint of performance as an antioxidant, with methyl being particularly preferred. Further, ``S'' represents an alkyl group having 1 to 8 carbon atoms or a phenyl group, and preferably an alkyl group having 1 to 4 carbon atoms or a phenyl group. In addition, in the compound (general formula value), a represents an alkyl group having 4 to 20 carbon atoms, preferably an alkyl group having 6 to 18 carbon atoms in terms of its performance as an antioxidant, and particularly an alkyl group having 1 g of carbon atoms. Most preferred.

Next, representative examples of compounds of general formula (11) and compounds of general formula (1) used in the present invention are shown in Table-1 and Table-2.

Wheat-1 jlLI jlLI Table-2 Such compounds of general formula (I) are compounds represented by the following general formula (2) O 1 (wherein, R1 represents an alkyl group having 1 to 4 carbon atoms) and the following compounds. General formula (transformed) HO-P-(-
0shi) Mayuzumi (3) (in the formula, shi has a carbon number of 1 to 8
represents an alkyl group or a phenyl group. ) can be produced by reacting with a phosphite compound represented by the following by a known method.

In the synthetic rubber composition of the present invention, a compound of formula (!) and (2
) The total amount of the compound added is usually 0.1 to 2 weight units per 100 weight units of synthetic rubber, preferably O, S to t,
S weight m. Further, the weight ratio of the compound of the formula (!) to the compound of the formula (!) is usually particularly preferably the formula (1).

In the present invention, the compound of formula (!) and the compound of formula (billion) can be added to the synthetic rubber by an ordinary method, such as preparing an emulsion in advance and adding it to the synthetic rubber latex, or dissolving it in a suitable organic solvent in advance. There are no particular limitations, and a method may be used, such as adding it to the rubber cement of solution-polymerized synthetic rubber.

Synthetic rubbers stabilized by the present invention include solution polymerized polybutadiene rubber, solution polymerized polyisoprene rubber, bottom liquor polymerized styrene-butadiene co-densed rubber, ethylene-propylene terpolymer rubber, Isoprene-isobutylene copolymer rubber, emulsion polymerization method styrene-butadiene copolymerization: 'A', chemical method method acrylonitrile-butadiene copolymer rubber, etc., especially solution polymerization method l liptadiene rubber, solution polymerization method glyisoprene rubber, etc. Rubber, styrene-butadiene rubber produced by solution a polymerization, etc. 1ζ are effective.

Next, the present invention will be explained in detail with reference to Reference Examples and Examples, but the present invention is not limited thereto.

Reference Example 1 2.2'-methylenebis(6-t-butyl-4-methylphenol') 8101 (0,241
mol) toluene 200I and triethylamine 28.
91 (0J90 mol), the air in the container was replaced with nitrogen, and the mixture was cooled to 1°C. A solution of acryloyl chloride 251 (0,276 mol) and toluene 6 ol was added dropwise from the dropping funnel over a period of 2 hours. After the addition, excess triethylamine was neutralized with S-hydrochloric acid. The filtrate was washed with water and separated, and 180f of toluene was distilled off from the toluene layer, and 50g of n-hexane was added to recrystallize to give 90.Of (yield: 9
5%) as white crystals with a melting point of 188-184°C 2.2
'-Methylenebis(6-tert-butyl-4-methylphenol) sonoacrylate was obtained.

Elemental analysis Cultim40m Ci 79.84% (79,15), H+ 8.86
% (8,69) Reference Example 2 2.2'-methylenebis(6-t-butyl-4
-methylphenol) sonoacrylate 7.901 (
0,020 mol), diethyl phosphite 2.761
(0,020 mol) and chloroform 801 were charged, and the air in the container was replaced with nitrogen. Pour 0.81% 28% sodium methoxide methanol solution and raise the humidity to about 6
Allow to react under reflux for an hour. After cooling to 80°C, neutralize with dilute hydrochloric acid, wash with water, dry with anhydrous sodium sulfate, distill chloroform, add n-hexane 51, and recrystallize to obtain 9.
．． Diethyl (1)-1 shown in Table 1 as white crystals with 02IC yield 88cX) and melting point 129-181°C.
2-t-butyl-6-(8-1-phthyl-2-hydroquine-5-methylbenzyl)-4-methylphenoxycarbonylethylphosphonite was obtained.

Original thread analysis Caokl*aOaF () Calculated value C; 70.4% (70,6%) H poison 4.7% (4,5%) P-6,0% (6,1%) Infrared absorption Spectrum (unit α-1) (liquid paraffin) 8180 (shi 0-H), 1755 (shi c: o), 12
60 out-of-plane (ν2=o), 1050 (νF −0), 860 (δ
) arosuat+cc-H Reference Example 3 Into a 200 ml four-neck flask equipped with a thermometer, a stirrer, and a cooling tube, 2#2'-methylenebis(6-t-butyl-
4-methylphenol) monoacrylate 8.569
(0,022 mol), diphenyl phosphite 5.08
f (0,022 mol) and chloroform 70F are charged, and the air in the container is replaced with nitrogen. 0.8 g of 28% sodium methoxide methanol solution was charged, the temperature was raised, and the reaction was carried out under reflux for about 10 hours.

After cooling to 80℃, neutralizing with dilute hydrochloric acid, washing with water, drying with anhydrous sodium sulfate, and distilling chloroform, 18.81
A colorless transparent oil with a yield of 98X and a purity of 90X was obtained.

This crude product was purified by silica gel column chromatography (
Separation and purification using silica gel manufactured by Merck & Co., Ltd. (N-hexane-ethyl acetate) yielded 9.51 (yield 70%) of diphenyl 2-t, a white glassy substance (melting point 58-68°C).
-butyl-6-(8-1-butyl-2-hydroxy-5
-methylbenzyl)-4-methylphenoxycarbonylethylphosphonite was obtained.

Death ticket analysis Cm Hata ■4 OsP () Calculated value C
Curtain 72.5% (72.8%) Hl 7.1% (6.9%) P stem 5.0% (4.9%) Infrared absorption spectrum (unit, -1) (liquid paraffin) 8480, 8800 (ν04'), 1740 (νC
==O), 1595(ν, 21mC+=C), 1140
(SiF-0), 860 (δ mustache, C-H) Example 1 Solution polymerized polybutadiene rubber containing no antioxidant (
The test compounds shown in Table 1 were roll-kneaded into the rubber obtained by extracting the antioxidant from JARBR-01 with acetone. I did it.

The results are shown in Table-1.

Thermal and oxidation stability is determined by heat aging the test rubber in a gear oven at 100°C, measuring the gel content (toluene insoluble content) at each IIS interval, and calculating the time required for the gel content to reach 10% by weight. (referred to as GelI, P).

In addition, heat discoloration resistance is 15% in a gear oven at 100°C.
The rubber hue after heat aging for 60 hours and 120 hours was evaluated.

In addition, in the table, Mu o-1 to Mu O-5 indicate the following compounds.

O-12,6-di-t-butyl-4-methylphenol 0-2 n-octadecyl-β-(8゜6-di-t
-Butyl-4-hydroxyphenyl)propionate AO-8 Pentaerythritol-tetrakis[β-(8,5-di-t-butyl-4-hydroxyphenyl)propionate 0-4 Dilaurylthiodipropionate 0 -5 Nonylphenyl phosphite table -1 (1) Addition amount (PIiR) and test results Addition amount (PH1) and test result table -1 (8) Addition amount (PER) and test result table -1 (4) Addition amount (PHIL) and test results table-1 [5) Addition amount (PIIIR) and test results Example 2 Solution polymerized polyisoprene com containing no antioxidant (
The test compounds shown in Table 2 were added to a 5% toluene solution of J8RIR-2200 Color fa (using rubber from which the tlJFj inhibitor was extracted with acetone), stirred to make a homogeneous solution, and the toluene was removed. A test rubber was used to test its thermal and oxidative stability and heat discoloration resistance.

The results are shown in Table-2.

The thermal and oxidative stability was determined by heat aging the sample rubber in a gear oven at 70°C for 7 days, measuring the plasticity using a Wallace Labid plastimometer, and calculating the plasticity retention rate (PRI) using the following formula. sought and evaluated.

Further, heat discoloration resistance was evaluated by the rubber hue after heat aging for 7 days in a 70° C. gear oven.

Table-2 (1) Addition amount (PER) and test results Table-2 (2) Added Jl(P]EIR) and test results Table-2 (8) Addition amount (PER) and test results Addition amount (PH1) and test results Table-2 (6) Addition jl (PER) and test results

Claims (1)

[Claims] A compound of the following general formula (2) and a compound of general formula (2) are blended into synthetic rubber in a weight ratio of (I):(1)-!:1 to 20 (weight ratio). A stabilized synthetic rubber composition having the following formula. 8-CIIs(mis-c-o-CXHs-'
17cl) (In the formula, 凰 represents an alkyl group having 4 to 20 carbon atoms.)