JPH03143939A - Chlorosulfonated polyolefin composition - Google Patents

Abstract

PURPOSE:To prepare a vulcanized product excellent in the compression set and resistance to flex crack growth by compounding a chlorosulfonated polyethylene contg. a specified amt. of sulfur with a specific vulcanizing agent and a specific accelerator. CONSTITUTION:A chlorosulfonated polyolefin compsn., useful for automotive boots, belts, hoses, etc., is prepd. by compounding: 100 pts.wt. chlorosulfonated polyolefin contg. sulfur derived from SO3Cl group of 0.75wt.% or lower; 0.5-8 pts.wt. vulcanizing agent comprising a bismaleimide, e.g. N,N'-m- phenylenediaminebismaleimide; and 0.5-5 pts.wt. accelerator comprising an amine, e.g. 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a chlorosulfonated polyolefin composition that has excellent physical properties of a vulcanizate, particularly compression set and flex crack growth resistance.

(Prior art) Chlorosulfonated polyolefins, represented by chlorosulfonated polyethylene, are known as elastomer materials with excellent weather resistance, ozone resistance, heat resistance, chemical resistance, and coloring properties, and are used in various automotive applications. It is used in a wide range of fields such as hose covers, electric wire coatings, acid-resistant hoses, covering cloth, gas hose covers, boots, belts, sheets, paints, solution coatings, and roofing materials, but in recent years, the performance requirements have increased, including in the automobile industry. It has become sophisticated.

However, when compared to chloroprene rubber, which is the same chlorine-based elastomer, chlorosulfonated polyolefin has the drawbacks of inferior compression set and flex crack growth resistance for boat fishing, and improvements are desired. ing.

As a method for improving the compression set of chlorosulfonated polyolefins, a method using an organic peroxide or maleimide as a vulcanizing agent is conventionally known. However, none of the above methods has solved the problem of flex crack growth resistance, and in the method using an organic peroxide as a vulcanizing agent, it is difficult to obtain sufficient crosslink density.
In addition, an acid acceptor such as magnesium oxide or calcium hydroxide is required to prevent foaming during vulcanization, which causes problems such as deterioration of water resistance. Furthermore, organic peroxides have the risk of ignition and explosion, and it is necessary to take care in storing and handling them, which may pose an obstacle when put into practical use.

On the other hand, a method for improving the mechanical fatigue properties of elastomers including flex crack growth resistance includes adding a plasticizer. By adding mineral-based oils such as naphthenic and paraffinic oils, or vegetable-based oils such as rapeseed oil, castor oil, and soybean oil to the composition, fillers such as carbon black and silica, which are commonly used in rubber, can be dispersed. It is known that fatigue properties are improved. However, the method of adding plasticizers to elastomers, not just chlorosulfonated polyolefins, has little effect unless a certain amount of plasticizer is added, and this has the problem of reducing the strength and hardness of the vulcanized product. .

(Problems to be Solved by the Invention) The present invention has been made in view of the above points, and its purpose is to provide a vulcanizate with excellent compression set and also excellent flexural crack growth properties. An object of the present invention is to provide a chlorosulfonated polyolefin composition.

(Means and effects for solving the problem) In order to solve the problems of the above-mentioned prior art, the present inventor focused on the molecular structure and vulcanization system of chlorosulfonated polyolefin, and determined the degree of crosslinking of chlorosulfonated polyolefin. The amount of chlorosulfone groups (-3O□ci>, i.e., the sulfur content is 0.7
We discovered that a composition containing 5% by weight or less of chlorosulfonated polyolefin, a bismaleimide as a vulcanizing agent, and an amine compound as a vulcanization accelerator has very good compression set and resistance to flex crack growth. invention has been achieved. That is, the present invention comprises blending bismaleimides as a vulcanizing agent and an amine compound as a vulcanization accelerator into a chlorosulfonated polyolefin in which the content of sulfur derived from chlorosulfone groups is 0.75% by weight or less. The present invention relates to a chlorosulfonated polyolefin composition.

The chlorosulfonated polyolefin used in the composition of the present invention includes polyethylene, ethylene-propylene copolymer,
Among those obtained by chlorosulfonating olefin polymers or copolymers such as ethylene-α olefin copolymer, ethylene-vinyl acetate copolymer, and polypropylene, the sulfur content derived from chlorosulfone groups (hereinafter simply " 0.75% by weight or less, preferably 0.
．． It is 25 to 0.65% by weight.

Those with an S amount exceeding 0.75% by weight, for example, have been considered ideal in terms of vulcanization density, vulcanization speed, or vulcanization physical properties, and the most commonly commercially available S amount is about 1. When using 0% by weight of chlorosulfonated polyethylene,
Sufficient flex crack growth resistance cannot be obtained. Conversely, if the amount of S is 0.
If it is less than 25% by weight, the vulcanization rate may be slow and the compression set may be poor.

-4. There is no particular restriction on the chlorine content of the chlorosulfonated polyolefin, but it is generally 20 to 50% by weight. Although the present invention does not specify the method for producing chlorosulfonated polyolefin, the chlorosulfonation reaction involves dissolving an olefin (co)polymer in a solvent such as carbon tetrachloride, It is carried out by reacting chlorine, sulfur dioxide gas and/or sulfuryl chloride in the presence of a radical catalyst and a co-catalyst such as pyridine, and the amount of S is adjusted by the amount of the co-catalyst pyridine etc. added and the reaction temperature. Can be adjusted.

In the composition of the present invention, bismaleimides are used as the vulcanizing agent. Specific examples of bismaleimides include N,
N'-m-phenylenediamine bismaleimide, N,N
'-p-phenylenediamine bismaleimide, N, N'
-ethylenediamine bismaleimide, N,N'-propylene diamine bismaleimide, and the like.

The amount of bismaleimide used is preferably 0 parts by weight per 100 parts by weight of the chlorosulfonated polyolefin.
．． If the amount used is less than 0.5 parts by weight, the compression set value will increase, and if it exceeds 8 parts by weight, the hardness will become too high or the ozone resistance will decrease. There is a fear.

Further, in the composition of the present invention, an amine compound is used as a vulcanization accelerator. Examples of the amine compound include 6-nitoxy-2.2.4-trimethyl-1,2-dihydroquinoline, poly(2,2,4-trimethyl-1,2-dihydroquinoline), and N.

N'-diphenylethylenediamine, 4.4゛bis(α
, α-dimethylbenzyl)diphenylamine, a condensate of n-butyraldehyde and aniline, and the like. The amount of the amine compound used is preferably 0.5 to 5 parts by weight; if it is less than 0.5 parts by weight, vulcanization will be slow, and if it is more than 5 parts by weight, the scorch resistance may decrease.

In addition to the above-mentioned essential ingredients, the composition of the present invention contains various compounding agents commonly used in the rubber industry or resin industry, such as magnesium oxide, zinc oxide, arsenic acid, hydrotalcite, calcium hydroxide, sulfur, Vulcanizing agents or acid acceptors such as pentaerythritol, vulcanization accelerators such as dipentamethylenethiuram tetrasulfide, fillers and reinforcing agents such as carbon black, silica, clay carbon, processing aids, plasticizers, softeners. , anti-aging agents, stabilizers, pigments, flame retardants, etc. can be appropriately selected and used within the range that does not impair the purpose of the present invention.

Furthermore, there are no particular restrictions on the blending method, and any method commonly used in the field of polymer processing can be applied. For example, a mixing roll, a Banbury mixer, an internal mixer, various kneaders, an extruder having a kneading action, etc. can be used.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples. In the specification, "parts" and "%" are all by weight, except for the values of elongation and compression set in Table 2. Show standards.

Examples 1 to 3 and Comparative Examples 1 to 3 Using linear polyethylene with a density of 0.92 g/CC as shown in Table 1 as a raw material, chlorosulfonated polyethylene ( C3M-A,B
, C, D, E) were produced. Next, according to Table 2, an acid compound of the present invention and a comparative composition were prepared. The blending was carried out using a mixing roll.

Various tests shown in Table 2 were conducted using these compositions, and the test methods were as follows.

(1) Vulcanization test: Japan Rubber Association Standard 5RIS/31
The vulcanization time (T2O) at 160''C was measured using an oscillation disc rheometer (manufactured by Toyo Seiki) in accordance with 02-1977.

(2) Mooney scorch test: According to JIS K 6300, the rotor used was L type,
The scorch time (t,) was measured at a test temperature of 125°C.

(3) Physical properties of vulcanized product: Various physical property tests were conducted in accordance with JIS K 6301. The vulcanization was performed using a press vulcanizer at 160'C for the vulcanization time determined in (1) above, and the heat treatment conditions for the compression set test were ioo''C x 22 hours.Furthermore, the bending test measured the number of times an initial crack (2 mm in length) was bent until it grew to 6rH1.

(Effects of the Invention) As explained above, the composition of the present invention simultaneously solves the problems of compression set and flex crack growth resistance, which were conventionally considered drawbacks of chlorosulfonated polyolefins. It is extremely useful and can be applied to various rubber products used in the automobile industry, such as boots, belts, various hoses, etc., which require durability.

Claims (1)

[Claims] (1) Sulfur content derived from chlorosulfone group is 0
．． A chlorosulfonated polyolefin composition comprising 75% by weight or less of a chlorosulfonated polyolefin, a bismaleimide as a vulcanizing agent, and an amine compound as a vulcanization accelerator.