JPS5842634A - Production of high-modulus rubber composition - Google Patents

Abstract

PURPOSE:To produce industrially advantageously a high-modulus rubber compsn., by drying a hydrated rubber contg. a high-melting isotactic poly-alpha-olefin under specified conditions. CONSTITUTION:A hydrated rubber such as polyisoprene rubber contg. a high- melting isotactic poly-alpha-olefin having a m.p. of 150-240 deg.C such as isotactic polypropylene or poly (4-methyl-1-pentene), is extruded through a screw type extruding dryer equipped with a die such as an expansion dryer with heating under pressure, whereby said rubber is ejected through the die and the said pressure is instantaneously reduced to atmospheric pressure to evaporate water and to dry the rubber, thus producing a high-modulus rubber compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION More specifically, the present invention relates to an industrially advantageous method for producing a high elastic modulus rubber composition by drying a hydrous rubber containing a high melting point isotactic polyα-olefin under specific conditions.

In recent years, resource saving and energy saving have become important themes in industry, and the rubber industry is also aiming for lighter weight and higher performance. Therefore, vulcanized rubber having a higher elastic modulus than the commonly used vulcanized rubber has become desired in specific fields. In this case, the physical properties other than the elastic modulus are comparable to those of conventional vulcanized rubber (54%).
2. When manufacturing rubber products, it is frustrating that one case has failed.

High elasticity 4' is a method of increasing the elastic modulus of vulcanized rubber.
A method of mixing substances (carbon black, resin, etc.) with rubber into powder or fiber form is used.

However, with this method, the dispersibility of the high modulus material and the interfacial adhesion between the rubber and the high modulus material are insufficient, so when stress is applied to the vulcanized rubber, the rubber and the high modulus material may Since the interface is destroyed, vulcanized physical properties such as tensile strength, tear resistance, and bending resistance deteriorate. For example, polyisoprene rubber, which has the lowest bending resistance among diene rubbers and is widely used for radial tires, has a high modulus of elasticity by increasing the amount of carbon blank. In particular, there is a problem that the bending resistance decreases.

The present inventors have discovered that -F
As a result of intensive studies on new reinforcing agents and methods for mixing them in order to improve these defects, we found that by micro-dispersing isotactic poly-α-olefin using a specific method, we have found that it has a high modulus of elasticity and excellent fracture properties. The sticky rubber composition is 11
,) (:,, 71. 3゜For example, fine powder high melting point isotactic poly-α-olefin with average particle diameter of 200μ or more is stirred and dispersed in an organic solvent and then suspended. A method of recovering a polymer mixture after mixing a dispersion and a rubber solution (Japanese Patent Application No. 55-69571), a method in which isotactic poly-α-olefin with a high melting point is obtained by applying mechanical shearing force while swollen with an organic solvent. A method of mixing a dispersion liquid and a rubber solution (Japanese Patent Application No. 55-55450), average particle size 1
Powdered high melting point isotactic polyα-
There is a method of mixing olefin with polyisoprene rubber at a temperature higher than its melting point (Japanese Patent Application No. 12430).Furthermore, isotactic polyα-olefin with a melting point of 150°C or higher) is mixed with polyisoprene rubber at a temperature of 1/- $7 A method in which a mixture dispersed in polyinogrene rubber to a diameter of 50μ or less is stretched between a temperature 65°C lower than the melting point of high melting point isotactic polyα-olefin and a temperature 20°C higher than the melting point. 55-103198), it was discovered that a rubber composition with higher elasticity was obtained by 1q. Shikajinaga C) The above power? 1, there is a problem with Vcv ↓ or less, which is produced in an industrially advantageous manner in the current synthetic rubber manufacturing plants. In other words, the average particle diameter of the high melting point α-olefin that is currently available in the industry and can be produced by hand at low cost is 0.0.
It is a powder or pellet-like particle of 2 to 3 pieces. In order to obtain particles with a smaller diameter than this, it is necessary to perform screening using a sieve or special pulverization treatment, which is advantageous in terms of cost.

Furthermore, the method of kneading particles of 1 mm or less at temperatures above their melting point does not necessarily improve the elastic modulus sufficiently.

The present inventors have arrived at the present invention as a result of intensive studies on a method for industrially advantageously producing a high elastic modulus rubber composition in a synthetic rubber manufacturing plant.1 That is, the present invention has a melting point of
2. A water rubber containing a low-tactic polyα-olefin with a high melting point of 10°C is extruded using a screw-type extrusion dryer under heating and pressure, and the high-temperature and high-pressure rubber is ejected from a die instantly. The object of the present invention is to provide a method for industrially and advantageously producing a high elastic modulus rubber composition by evaporating water and drying it while reducing the pressure at atmospheric pressure.

The high melting point isotactic polyα-olefin used in the present invention is an isotactic polyα-olefin having a melting point of 150 to 240°C. If the melting point is less than 150°C, it will melt under the rubber vulcanization conditions and good physical properties will not be obtained.

If the melting point exceeds 240°C, it will be difficult to melt during extrusion drying, making it impossible to obtain good physical properties. Specific examples of isotactic polyα-olefins include polypropylene, poly(4-methyl-1-pentene), polyallylcyclohexane, polyallylbenzene, poly(3-cyclohexyl-1-butene), and poly(3-cyclohexyl-1-butene). Copolymers of α-olefins and other α-olefins, such as (4-phenyl-1-butene), poly(4-methyl-.-hexene), and copolymers of propylene and 4-methyl-1-pentene, Can be mentioned. Among these, polypropylene and poly(4-methyl-1
-pentene) is preferred because it can be easily produced industrially.

Polypropylene is particularly preferred because it has excellent tensile strength and can be used over the entire temperature range during extrusion drying of rubber.

The rubbers used in this 111IC are polyisoprene rubber, natural rubber, polybutadiene 7 coats, 1. Examples include ethylene-butadiene rubber, ethylene-propylene rubber, and butyl rubber. Among these, diene rubber is preferred, and polyisoprene rubber is particularly preferred.

In the present invention, the hydrous rubber containing high melting point isotactic polyα-olefin is produced by (1) mixing polyα-olefin particles-f with a comb bath liquid;

(2) Mixing the organic bath dispersion of polyα-olefin particles with the rubber solution.

(3) Mixing the polyα-olefin solution with the resin solution.

(4) The organic solvent-swollen crushed polyα-olefin is mixed with a rubber solution.

It can be obtained by mixing by a method such as, etc., and then steam-cramming, which is usually carried out industrially.

The water-containing comb after steam cleaning usually contains a considerable amount of water, so first, use a normal steam bath.

Dehydrated using a set of compressed water patterns to remove 5% of the moisture in the hydrous rubber.
The content is preferably 30 to 30% by weight, and more preferably 5 to 25% by weight. If the 5-weight is lower than the tip, the rubber tends to phosphorize, and if the 30-weight ID is lower, the rubber tends to be insufficiently dried.

Among the above-mentioned methods for mixing polyα-olefin and rubber, the industrially available raw materials are used as they are or as a suspension dispersion in the same solvent used for the rubber solution after polymerization reaction. Can be directly mixed with the solution (1), (
Method 2) is preferred. As the isotactic polyα-olefin particles used in methods (1) and (2), pellets or granules that can be used industrially can be used, but those with an average particle size of 4 particles or less are preferable. , is particularly preferred.

The drying method used in the present invention must be a method using a screw type extrusion dryer equipped with a die. The effects of the present invention cannot be obtained with a hot air dryer.

In the present invention, water-containing rubber is extruded under heat and pressure in a screw-type extrusion dryer equipped with a die, and the rubber is ejected from the die at high temperature and high pressure and instantaneously lowered to atmospheric pressure, during which water is evaporated and dried.

At this time, the temperature of the rubber decreases rapidly, but the temperature of the rubber at this time is preferably below the softening point of the polyα-olefin, and for this purpose, it may be further cooled.

A specific example of a screw-type extrusion dryer with a die is an expansion dryer. As for the shape of the die, usually a circular die or a rectangular die is used.

Dryer operating conditions are usually 10 to 100 Ky/c.
td, 150-240°C. If the temperature is less than 150°C, a rubber composition with a high modulus of elasticity cannot be obtained, and drying becomes insufficient. Moreover, when the temperature exceeds 240°C, the rubber deteriorates rapidly.

The water content of the rubber composition after drying is less than 1 inch, preferably 0.
．． 5% or less.

Further, by instantaneously lowering the pressure from a high pressure of 10 Kg or more to atmospheric pressure, adiabatic expansion is performed and moisture vaporizes, so reducing the pressure from a lower pressure than this is insufficient for drying.

The rubber composition of the present invention is extruded from a die under heat and pressure and instantly dried by adiabatic expansion, so that it can be microdispersed with orientation throughout the high melting point isotactic polyα-olefin comb. It has a high elastic modulus and excellent fracture properties.

In the present invention, the content of high melting point isotactic polyα-olefin in the rubber composition is from 2 to 40% by weight, preferably from 3 to 30 grams! %, more preferably 3 to 25% by weight. If it is less than 2% by weight, a high elastic modulus cannot be obtained;
If the weight ratio exceeds 0, workability deteriorates.

The rubber composition obtained in the present invention can be used alone or in combination with other rubbers for rubber applications. Other rubbers include polyisoprene rubber, natural rubber, polybutadiene rubber,
Examples include styrene-butadiene rubber, ethylene-propylene rubber, and acrylic tributadiene rubber, with diene rubber being particularly preferred.

The rubber composition obtained in the present invention is prepared by adding and kneading compounding agents such as inorganic fillers, softeners, plasticizers, colorants, anti-aging agents, vulcanizing agents, and vulcanization accelerators that are normally used in rubber. Vulcanize and mold.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 Isotactic polypropylene with an average particle size of 0.3 m (
melting point 165°C) 2.8Kf 1R2200 (polyisoprene rubber manufactured by Japan Synthetic Rubber Co., Ltd., cis-1,4 content 98%,
yl: 0.0F 82 ) in s-hexane solution (polymer concentration 7%) at 35.4 Kt, stirred at room temperature for 30 minutes, then added a small amount of dispersant with a stripper and steam-stripped by blowing high-temperature steam. The volatile components such as the solvent were removed. The water content of the obtained hydrated rubber is 38
% by weight. This water-containing rubber was dehydrated using a screw-type dehydrator to a weight of 20%, and then
wm, diameter 10a++ length 1.577 with a die with a round hole of length 8 cm at the exit and a breaking bolt
40-50Kg/c in expansion dryer
It was extruded at 190-203°C under a pressure of d and expanded adiabatically in the atmosphere. The temperature of the rubber after exiting the dryer was 90°C. The moisture content in the dried crumb was 0.2% by weight, and the polypropylene content in the rubber was 11% by weight.

The polymer mixture was roll-kneaded at 80° C. according to the formulation shown in Table 1, then vulcanization molded and subjected to a tensile test according to JIS K6301. The results are shown in Table 2.

The vulcanizate has a high modulus of elasticity and excellent tensile strength.

Table 1 Polymer 100 parts by weight Carbon black 18AF 5Q
Aromatic oil JSRAROMA 1
0 Zinc white 5 Stearic acid 1 Anti-aging agent 81
ONA I vulcanization accelerator CZ
1.5 sulfur fi
2.5 Vulcanization conditions 1
45°C x 25 minutes Example 2 In Example 1, the polypropylene content in the polymer was reduced to 5
% by weight.

Example 3 In Example 1, the polypropylene content in the polymer was changed to 1
The content was adjusted to 5% by weight.

Example 4 In Example 1, a 5% hexane dispersion of polypropylene was used instead of polypropylene powder.

Example 5 The polypropylene used in Example 1 was replaced with polypropylene having an average particle size of 2+s.

Example 6 In Example 1, instead of polypropylene, the average particle size was 0,
25 wm poly(4-methyl-1-pentene) (melting point 2
35°C) and extrusion drying using an expansion dryer at 230 to 239°C. Poly(4-
The content of methyl-1-pentene was adjusted to 10% by weight.

Example 7 In Example 1, polybutadiene rubber (Japan Synthetic Rubber Co., Ltd. $1iJs) was used instead of the hexane solution of polyisoprene rubber.
RBRO1, cis-1,4-containing i 9796. M;o+
. 175 to 1 using the 10th scale toluene solution of ``44)
Extrusion drying was carried out using an expansion dryer at 82°C.

The content of polypropylene in the rubber is 10. % by weight.

Comparative Example 1 In Example 1, the content of polypropylene in the rubber was 1
After mixing a solution of polyisoprene rubber in n-hexane to a concentration of 0% by weight, the mixture was steam-crammed using an apron-type hot air dryer at 100°C under normal pressure. The particles were visible as they were.

Comparative Example 2 The polymer mixture obtained in Comparative Example 1 was extruded at 200° C. using a screw extruder without a die. The polymer mixture was a homogeneous dispersion.

Comparative Example 3 Extrusion drying was carried out in the same manner as in Example 1 except that polypropylene was not added and only polyisoprene rubber was treated.

Comparative Example 4 Extrusion drying was carried out in the same manner as in Example 7 except that polypropylene was not added and only polybutadiene rubber was treated.

Example 8 27.6 parts by weight of toluene was added to 1 part by weight of isotactic polypropylene (melting point 165°C) with an average particle size of 4 vm in a 1,5-inch container equipped with a stirrer having a ribbon-type stirring blade and heated. and dissolved. After cooling, the swollen polymer was stirred for 4 hours and crushed by applying shearing force. A predetermined amount of this mixture was added to a JSHIR2200 71-hexane solution (
A predetermined amount of the solution was added at a concentration toL4) and stirred for 3-0 minutes.

This polymer mixture was steam-crammed, dehydrated, and extruded using an expansion dryer in the same manner as in the examples. (The average particle size of the polypropylene in the polymer mixture after steam cracking was 0.2 x 10 m.) Comparative Example 5 The hydrous rubber after steam cracking in Example 6 was dried in the same manner as in Comparative Example 1.

(Blank below) Procedural amendment (voluntary) R. 7, 1980 Commissioner of the Japan Patent Office Shima 1) Haruki Tono 1, Indication of the case 1982 Patent Application No. 141095 2, Name of the invention High elastic modulus rubber composition Manufacturing method 6, relationship with the case of the person making the amendment Ushizaikichi Hideto,! jL & Address: 2-11-24 Tsukiji, Chuo-ku, Tokyo Name: Japan Synthetic Rubber Co., Ltd. Representative: Shinnosuke Katsumoto 4/Agent: 101 Address: 2-42-6, Kanda Jimbocho, Chiyoda-ku, Tokyo
Contents of amendment (1) Specification, page 11, line 10 (7) r35.4Kg
Correct J to F334V41.

Claims (6)

[Claims] (1) Water-containing rubber containing a high melting point isotactic polyα-olefin with a melting point of 150 to 240°C is ejected from an extrusion die under heat and pressure from a screw-type extrusion dryer V equipped with a die, and is instantly lowered to atmospheric pressure. A method for producing a high elastic modulus rubber composition, which comprises drying the composition by evaporating water. (2) High melting point Aitu Takuchi, Kupoly α- in rubber composition
The manufacturing method according to claim (1), wherein the olefin has an h1 of 2 to 40 h1. (3) A patent in which the hydrous rubber is produced by mixing high-melting point isotactic polyα-olefin particles as they are or as an opportunistic solvent dispersion with a rubber solution, followed by steam-cracking. The manufacturing method according to claim (1) item 6. (4) High melting point isotactic polyα-olefin is polypropylene/and poly(4-methyl-1-pe/thene)
Manufacturing method 1゜ according to claim (1), which is any one of (5) Claim No. 1 in which the rubber is a diene rubber
) The manufacturing method described in section 2. (6) The manufacturing method according to claim (1), wherein the rubber is polyisoprene rubber.