JPS61130357A - Rubber processing aid - Google Patents

Abstract

PURPOSE:To yield a rubber processing aid effective against natural rubber, styrene/butadiene or polyisoprene rubber, by incorporating a fatty acid having a hydroxyl group in the molecule and a salt thereof with a divalent metal as a principal ingredient. CONSTITUTION:A rubber processing aid consisting principally of a fatty acid having one or more hydroxyl groups in the molecule, a salt thereof with a divalent metal, or a mixture of these. 8-22C monobasic fatty acid is adequate as said fatty acid and 12-hydroxystearic acid is particularly pref. for fatty acids having one or more hydroxyl groups. By adding the rubber processing aid to a rubber in advance or together with a filler, is persion of the filler in the rubber proceeds with ease and the filler is dispersed rapidly and uniformly in the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a rubber processing aid that promotes the incorporation and dispersion of fillers into rubber during cross-wire processing of rubber, and at the same time contributes to improving the physical properties of rubber. It is related to.

Prior Art The present inventors have previously developed a polybasic acid in which two or more carboxyl groups are introduced into a hydrocarbon having four or more carbon atoms, a salt of the polybasic acid with a divalent metal, or a mixture thereof. Invented a rubber processing aid mainly composed of
A patent application was filed as Application No. 6.

Problems to be Solved by the Invention However, these rubber processing aids have been effective for synthetic rubbers such as styrene/butadiene rubber, chloroprene rubber, ethylene/propylene rubber, butadiene rubber, etc. Natural rubber with high properties has
It didn't have much effect.

Means to Solve the Problems The inventors have conducted intensive research to provide an effective rubber processing aid for natural rubber. It was discovered that salts with metals, or mixtures thereof, are effective as rubber processing aids for natural rubber, styrene-butadiene or polyisoprene rubber, leading to the completion of the present invention.

The fatty acid used in the present invention has 8 carbon atoms.
~22-m base acids are suitable, and those into which at least one hydroxyl group has been introduced can be used as the rubber processing aid of the present invention.
Hydroxystearic acid is preferred.

Effects of the Invention By adding the rubber processing aid of the present invention to rubber in advance or adding it together with a filler, the filler can be easily mixed and dispersed into the rubber, and the filler can be added quickly and uniformly. Dispersed in rubber. Therefore, the time for rubber cross-crossing is short, the physical properties of the rubber are less likely to deteriorate due to long-term cross-wires, and the reinforcing effect is enhanced because the filler is well dispersed. Therefore, a rubber compound using the rubber processing aid of the present invention has significantly improved vulcanization properties such as modulus and tensile strength.

The rubber processing aid of the present invention is effective when used on natural rubber, but it also provides sufficient effects when used on other synthetic rubbers.

Examples Example 1 Acid 1 [il 79, hydroxyl group ff1i157, iodine value 3
Commercially available 12-hydroxystearic acid.

Example 2 Acid value 150, obtained by hydroxylating unsaturated fatty acids,
Hydroxytol oil fatty acid with a hydroxyl value of 210 and an iodine value of 20.

Example 3 Calcium salt of 12-hydroxystearic acid formed from the 12-hydroxystearic acid of Example 1 by metathesis.

Example 4 A calcium salt of hydroxytol oil fatty acid formed from the hydroxytol oil fatty acid of Example 2 by a metathesis process.

Comparative example 1 Commercially available stearic acid.

Comparative example 2 Commercially available calcium stearate.

Carbon black dispersibility test Natural rubber: When the substances of each example and comparative example were blended with natural rubber, the effect on the dispersibility of carbon black in the natural rubber was investigated.

Test method 100 parts of masticated natural rubber of Mooney viscosity 185,
The roll a distance was adjusted to 1.5111C, and the roll was wound on a 10-inch diameter kneading roll machine with a surface temperature of 50°C, and then 5 parts of zinc white and the above-mentioned Examples and Comparative Examples were rolled for 3 minutes. 2 parts of material were added.

Next, 10 parts of HAF carbon black was added, and after 2 minutes, turning was performed twice on each side. This operation was repeated five times, and a total of 50 parts of HAF carbon black was added.

In the process of adding carbon black, the carbon black that fell from the roll onto the pan will not be re-added onto the roll, but will be left on the pan, and after all the above operations are completed, the tray will be placed on the pan. The amount of carbon black that had fallen was measured, and the amount of carbon black mixed into the natural rubber was calculated.

result The test results are shown in the table below.

Styrene-butadiene rubber: The effects of the compounding agents of Example 4 and Comparative Example 2 on the dispersibility of carbon black in the styrene-butadiene rubber when they were blended into the styrene-butadiene rubber were investigated.

Test method Equipped with Banbury type blade, blade 95 rpa
Pour 100 parts of S B R1502 into a plastometer driven by + and set the circulating water temperature to 40°C.
Subsequently, 5 parts of zinc white was added. After 1 minute, 2 parts of the compounding agent was added and kneaded for 2 minutes.

Next, 80 parts of HAF carbon black was added, and BT was determined from the torque required for crosstalk per hour. The filling rate of the blast meter is 78%.

1-The torque-hour relationship obtained after adding IAF carbon black is as follows: First, by adding IAF carbon black, the occupied volume inside the plastometer increases and the torque increases. Next, the viscosity of the rubber decreases due to the temperature generated by the crosstalk, carbon black is mixed into the rubber, and the occupied volume within the plus meter begins to decrease, causing the torque to begin to decrease. This torque peak is defined as the first peak. Furthermore, as carbon black is mixed into the rubber, the viscosity of the rubber increases and the torque increases again. When the carbon black is sufficiently mixed and dispersed, the compound progresses to plasticization and the torque decreases again. The torque peak at this time is defined as a second peak. B T
(B 1ack incorporationTi
me).

result The results of the test were as follows.

Basic physical property test of compounded rubber Rubber compositions containing the substances of Examples 1 and 4 above.
Basic physical properties were measured.

Compound Natural rubber compound R8S#3 100 Stearic acid 1 Zinc white No. 1 5 Rubber processing aid 2 HAF carbon black 50 Sulfur 2 Thiazole vulcanization accelerator 1 Polyisoprene compound 1R2200100 Stearin ill 1 Zinc white No. 1
5 Rubber processing aid 2 Naphthenic oil 20 HAF black 50 Sulfur 2 Thiazole vulcanization accelerator 1 The above formulation uses the substances of Examples 1 and 4 as a rubber processing aid, and rubber processing of these A blank containing no auxiliary agent was kneaded using a kneading roll machine to prepare an unvulcanized rubber composition.

Unvulcanized Rubber Test The Mooney viscosity of the unvulcanized rubber composition roll-kneaded according to the above formulation was measured according to JIS-6300.

Using a sample plate molding machine with a 2 mm thick vulcanization mold, 150°C, approx.
Vulcanization was carried out at 0 Icg-d for 10 minutes, 15 minutes and 20 minutes to obtain a press vulcanizate.

Vulcanized material physical property test The hardness was measured using a JIS hardness meter (spring type A type).

Modulus, tensile strength and elongation were measured using a Schopper tensile tester. The test piece is dumbbell JIS
-3@ type was used, the tensile speed was 500 mm/sin, and the measurement temperature was 20°C.

Test results The results of the test were as follows.

Claims (1)

[Claims] 1. A rubber processing aid whose main component is a fatty acid having one or more hydroxyl groups in the molecule, a salt of the fatty acid and a divalent metal, or a mixture thereof.