JPH0617393B2 - Chlorosulfonated copolymer for extrusion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a chlorosulfonated polymer (hereinafter abbreviated as CSM).
Is related to the use of. The CSM of the present invention is used for weather strips such as automobile hoses and door gaskets, oil-resistant and chemical-resistant hoses, and their cover materials. It is also used for wire coverings, drawing cloths, packings, gaskets and rolls where conventional CSM is used.

[Conventional technology]

CSM is similar to chloroprene rubber in its properties and fields of use as a halogenated elastomer, as represented by chlorosulfonated polyethylene. However, in terms of weather resistance, ozone resistance, heat resistance, bright color, etc., it is positioned as a special rubber that is one rank higher in performance than chloroprene rubber. However, since CSM has a high glass transition point and a large compression set at low temperature, it has poor cold resistance, and its use is greatly restricted.

In particular, low temperature properties of oil hoses and chemical resistant hoses such as automobile hoses and weather strips for automobiles are important. That is, when a hose or gasket in cold regions or in winter is lowered to a temperature near or below the glass transition point of the material, elasticity is lost, and, for example, oil or chemicals leak at the caulked portion of the hose end, or the gasket is In such cases, brittle fracture occurs when a strong impact or bending stress is applied. The following two methods have been taken as means for solving this. One is a modification method by the polymer itself. The glass transition point of CSM greatly changes depending on the amount of chlorine, and the glass transition point decreases as the amount of chlorine decreases. The modification by the polymer itself is to lower the glass transition point, but merely lowering the chlorine content does not improve the cold resistance of CSM. This is because the CSM changes from an amorphous one to a crystalline polymer due to a decrease in the amount of chlorine, and the hardness and the compression set increase due to crystallization. Also,
There is also a method of chlorosulfonation of low density polyethylene such as low density polyethylene which is amorphized to some extent with a hydrocarbon branch having a low cohesive force of about 1 to 4 carbon atoms.
Although this method improves the low temperature properties to some extent, it cannot be used because of poor workability. That is, when a hose, which is used for molding CSM by extrusion, is used for weather strips, it is difficult to apply since it has a large adhesion in the extruder.

On the other hand, if an amorphous polymer is chlorosulfonated, an amorphous chlorosulfonated product can be easily obtained. However, the glass transition point of such CSM is high and the purpose cannot be achieved.

On the other hand, a method is known in which a crystalline polymer obtained by copolymerizing ethylene with an α-olefin composed of a hydrocarbon having 3 to 8 carbon atoms is used as a raw material polymer for CSM. For example, an ethylene / butene-1 copolymer having a density of less than 0.90 can be mixed with chlorine 10
Those chlorosulfonated to about 30 wt% have a glass transition point significantly lowered, and the low temperature compression set is also improved. However, when this CSM was applied to extrusion molding, the surface condition of the extrudate was not good. Generally, CSM is kneaded with a roll, Banbury, or other kneading machine, vulcanizing agent, vulcanization accelerator, reinforcing agent, filler, plasticizer, anti-aging agent, etc., and then vulcanized into a product. . The molding methods are roughly divided into the following three. One is a method of putting the above kneaded product before vulcanization in a mold of the desired shape and compression molding with a hydraulic press, the second is a method of dispensing into a thin sheet shape with a calendar roll and processing into a waterproof sheet,
The third is an extrusion molding method in which the kneaded product is put into an extruder and extruded into a shape such as a hose. There is also a special method of coating by dissolving in a solvent. Among these, in extrusion molding, the quality of the surface state of the extrudate is an important issue that leads to performance defects such as easy occurrence of cracks due to ozone as well as aesthetic product value. Doing well is an essential requirement.

On the other hand, attempts have been made to improve cold resistance and extrudability by compounding. For example, it is a method of improving cold resistance and extrusion moldability by adding an ester plasticizer and oil. But,
If a small amount is used, a sufficient effect cannot be obtained, and if a large amount is added, phenomena such as deterioration of mechanical strength and bleeding of filler occur. In addition, there are restrictions on the composition, and the performance required for the final product cannot be satisfied.

[Problems to be solved by the invention]

Thus, the present invention aims to enable the use of CSM for extrusion molding which simultaneously satisfies the requirements of lowering the glass transition point and improving the compression set at low temperature, which were difficult by the conventional methods.

[Means for solving problems]

The gist of the present invention is that the glass transition temperature is −30 ° C. or lower, the chlorine content is 20 to 32 wt%, the sulfur content is 0.3 to 3.0 wt%, and the ratio of the weight average molecular weight Mw to the number average molecular weight _MN is 3.5 or more and 5.0 or less. Chlorosulfonated ethylene with excellent cold resistance
The purpose is to use the α-olefin copolymer for extrusion molding.

The details will be described below.

In order to obtain the target CSM in the present invention, the raw material polymer must be a crystalline polymer as described above. When the crystalline polymer is subjected to chlorosulfonation, the CSM having the best cold resistance is the one having the minimum amount of chlorine required for breaking the crystal and amorphizing it. here,
This is called the optimum chlorine amount. Here, the introduction of the chlorosulfone group was intended to give a cross-linking point as a rubber, and is determined in consideration of the vulcanization behavior of rubber, mechanical properties, storage stability, etc. Has no significant effect. The cold resistance is largely controlled by the chlorine content, and those with less than the optimum chlorine content lower the low temperature compression set due to the effect of crystals, and those with more than this have a glass transition point due to an increase in intermolecular cohesive energy due to the polarity of chlorine. Cold resistance is poor due to the rise. Generally, the optimum chlorine amount range is about ± 2%. This optimum chlorine amount is DSC
(Differential scanning calorimeter).

On the other hand, the crystalline polymer used as a raw material has ethylene with 3
It must be a crystalline polymer obtained by copolymerizing an α-olefin consisting of 8 hydrocarbons. The reason for this is that in order to lower the glass transition point of CSM, it is important to reduce the polarity of the constituent molecules to reduce the intermolecular cohesive force.

A crystalline ethylene / α-olefin copolymer is a linear ethylene / propylene copolymer or a linear ethylene / α-olefin copolymer.
Butene-1 copolymer is preferred.

A typical example will be described in detail below.

The raw material copolymer is ethylene propylene or ethylene
When it is a butene-1 copolymer, the content of propylene or butene-1 is 4 to 37 mol%. The density of such a copolymer is less than 0.90 g / cm ² . A melt index of 0.1 g / 10 min to 100 g / 10 min is preferable, but considering the viscosity in the reactor, 0.1 g / 10 min to 15 g /
It is preferably 10 minutes. These copolymers have a chlorine content of 2
0 to 32 wt%, sulfur content 0.3 to 3.0 wt% chlorosulfonated to give the optimum chlorine content, glass transition point is -30
The ratio of the weight average molecular weight Mw to the number average molecular weight M _N is not higher than ° C.
Those of 3.5 to 5.0 give the desired chlorosulfonated copolymer having excellent cold resistance.

In the present invention, the chlorine content of the resulting chlorosulfonated copolymer should be 20 to 32 wt%. If it exceeds 32 wt%, the effect of improving the cold resistance is not sufficient, and if it is less than 20 wt%, the oil resistance, chemical resistance, and liquid resistance that should be originally provided as CSM deteriorate. As mentioned above, CSM is a kneading machine such as roll, Banbury, etc.
Reinforcing agents, fillers, plasticizers, anti-aging agents, etc. are kneaded and vulcanized after molding in a molding machine, but when the sulfur content in the chlorosulfonated copolymer of the present invention is less than 0.3 wt%, it is added. 3.0 wt% due to insufficient sulphurization, resulting in reduced mechanical strength
If it exceeds the range, scorch, which is an undesired vulcanization, is not good during kneading or between kneading and molding.

The chlorosulfonated copolymer in the present invention is amorphous,
And the glass transition point must be -30 ° C or lower.

In terms of crystallinity, as described above, even if the glass transition point is low, the effect of improving the compression set at low temperature is not sufficient. If the glass transition point exceeds -30 ° C, the effect of improving the compression set at low temperature is also sufficient. Not.

In the present invention, the ratio of the weight average molecular weight Mw and the number average molecular weight M _N of the chlorosulfonated copolymer produced is 3.5 or more and 5.0 or more.
Must be: When Mw / M _N exceeds this range, the extrusion moldability, which is essential for extrusion molding, deteriorates, which is not preferable. That is, when the Mw / M _N is less than 3.5, the surface condition of the extrudate becomes poor, and when the Mw / M _N exceeds 5.0, the C to the processing machine at the time of kneading with a roll or Banbury, or in the extruder
It is not preferable because the SM compound has a large tackiness. For the chlorosulfonated copolymer in the present invention, the same compounding, molding, and processing methods as in ordinary CSM can be applied. White fillers such as carbon, calcium carbide, clay and silica, mineralizers and vegetable oils, plasticizers typified by various esters, vulcanizing agents such as metal oxides and epoxy compounds, dipentamethylene, thiuram and tetrasulfide. In some cases, antioxidants and various processing aids are added to vulcanization aids such as dibenzothiazyl and disulfide, and the mixture is uniformly kneaded by a mixing roll and a Banbury mixer. After this, the kneaded product is subjected to a vulcanization step in which it is put into an extruder to obtain a product.
The vulcanization may be any of a vulcanization can using steam as a heat medium, UHF vulcanization, fluidized bed vulcanization, etc., and is not particularly limited.

The method for producing the chlorosulfonated copolymer in the present invention is not particularly limited, but usually, the raw material polymer is dissolved in carbon tetrachloride to obtain α, α′-azobisisobutyronitrile as a radical generator. It is prepared by injecting sulfuryl chloride using an amine compound as a cocatalyst.

〔Example〕

 The present invention will be described below with reference to examples.

The numerical values used in the present invention are based on the following measuring methods.

Melt index: JIS K 7210 (190 ℃, 2160 g load) Density: JIS K 7112 Copolymerization composition: Presence or absence of glass transition point crystal by ¹³ C-NMR: By differential scanning calorimeter Model SSC / Daini Seikosha Co., Ltd. 560S Sample amount about 15 mg Temperature rising rate 10 ° C / min Determination method 1. Glass transition point: The base line of the glass region and the straight line portion of the glass transition region are extrapolated intersection points (see Fig. 1a). Presence or absence: With or without melting point (see Fig. 1b) Molecular weight distribution: According to GPC (HLC802 manufactured by Toyo Soda Kogyo Co., Ltd.) (Chlorosulfonate) 0.15wt% (THF) Flow rate 1cc / min Mooney Viscosity: JIS K 6300 compliant Scorch time Extrudability: ASTM D 2230-77 compliant Garbage die attached to Brabender Plastograph. Maximum 4 points, bottom 1 point (L / d = 10, screw diameter 19 mm, rotation speed 80 rpm, cylinder and head temperature 70 ° C, 90 ° C) Chlorine and sulfur content: by blast combustion method Vulcanized rubber test: JIS Compliant with K6301 Compressed at -20 ℃ and compressed at 23 ℃, 2 at -20 ℃
After standing for 2 hours, the load is removed at this temperature and the thickness after 30 minutes is measured. Chemical resistance is 60% H ₂ SO ₄ and 50% NaO at 70 ℃
It was immersed in H for 168 hours and judged from the rate of change in volume and the appearance.

Molecular weight distribution: GPC (ALC150C manufactured by Waters) (ethylene copolymer) Solvent ODCD, 140 ° C. Example 1 Ratio of weight average molecular weight Mw to number average molecular weight _MN is 4.3, melt index 1.9, butene-1 content 7.5 mol Chlorosulfonation of 1% ethylene-butene-1 copolymer
A chlorosulfonated copolymer having 29.8 wt% and a sulfur content of 0.89% was obtained. The reaction is carried out in carbon tetrachloride and α,
Pyridyl was charged as a cocatalyst using α'-azobisisobutyronitrile, and sulfuryl chloride was injected. The reaction temperature is 100 ° C. As a result of analysis by DSC (differential scanning calorimeter), CSM was amorphous and had a glass transition point of -32.
It was found to be ° C. Further, the Mw / M _N of this CSM was calculated by GPC, and it was 4.2. This CSM is shown in Table 1.
Roll kneading was performed according to the formulation shown in. In the kneading procedure, after winding the CSM around a roll, a metal oxide is added, and then a white filler such as carbon or calcium carbonate and an auxiliary agent are added. A softening agent and a plasticizer are added to this, and finally a vulcanization accelerator is added and kneaded. A part of the kneaded dough was press-vulcanized to be used as a sample for evaluation of mechanical properties and cold resistance, and a part was used for determination of extrusion moldability. The results are shown in Table 3.

Example 2 The weight average molecular weight Mw and a ratio Mw / M _N of the number average molecular weight M _N of 4.0
Then, an ethylene / butene-1 copolymer having a melt index of 4.0 and a butene-1 content of 8.0 mol% was chlorosulfonated to obtain a CSM having a chlorine content of 30.5 wt% and a sulfur content of 0.99 wt%. reaction,
The kneading and sample preparation methods were the same as in Example 1. The results are shown in Table 3.

Example 3 An ethylene / propylene copolymer having a Mw / M _N of 4.1, a melt index of 2.9 and a propylene content of 34 mol% was chlorosulfonated to obtain a CSM having a chlorine content of 22.5 wt% and a sulfur content of 1.05 wt%. The reaction, kneading, and sample preparation methods were the same as in Example 1. The results are shown in Table 3.

Comparative Example 1 Mw / M _N is 2.7, Melt Index is 1.05, Butene-1 Content
The same procedure as in Example 1 was performed except that 8.0 mol% of ethylene / butene-1 copolymer was used as a raw material. The results are shown in Table 3.

Comparative Example 2 Mw / M _N of 2.7, melt index of 7.0, butene-1 content
Same as Example 1 except that 8.0 mol% of the copolymer was used. The results are shown in Table 3.

Comparative Example 3 Mw / M _N is 2.7 and melt index is 4.5 Propylene content 3
Example 1 was repeated except that 4.5 mol% of ethylene / propylene copolymer was used. The results are shown in Table 3.

Comparative Example 4 The same procedure as in Example 1 was carried out except that low pressure high density polyethylene having a melt index of 7 was used as a raw material for CSM. The results are shown in Table 3.

Comparative Example 5 The procedure of Example 1 was repeated except that high pressure low density polyethylene having a melt index of 10.9 was used as a raw material for CSM. The results are shown in Table 3.

Comparative Example 6 Butene with a melt index of 4.0 as a raw material for CSM
Example 1 was repeated except that so-called linear low density polyethylene having a content of 3.5 mol% was used. The results are shown in Table 3.

Comparative Example 7 The CSM used in Comparative Example 4 was kneaded with the composition shown in Table 2. The kneading procedure and sample preparation method are the same as in Example 1.

As can be seen from Table 3, except for the case of the present invention, the CSM excellent in cold resistance and suitable for extrusion molding cannot be obtained.

Example 4 The same chlorosulfonated copolymer as in Example 3 was used, and the formulation shown in Table 4 was used. The kneading, sample preparation method and the like are the same as in Example 1. The results are shown in Table 5.

Comparative Example 8 The same chlorosulfonated polymer as in Comparative Example 3 was used and the composition was as shown in Table 4, and kneading, sample preparation, etc. were the same as in Example 1. The results are shown in Table 4.

As can be seen from Table 4, the present invention is effective even if the composition is changed.

Table 1 (Compounds of Examples 1 to 3 and Comparative Examples 1 to 6) Formulation Chlorosulfonated polymer 100 phr MgO # 150 5 SRF carbon 45 Dioctyl sebacate 25 Silver W (Shiroishi Kogyo Co., Ltd.) 40 Dipentamethylene thiuram -Tetrasulfide 2 Pentaerythritol 3 Table 2 (Compound of Comparative Example 7) Blend Chlorosulfonated polymer 100 phr MgO # 150 5 SRF carbon 45 Dioctyl sebacate 35 Silver W (Shiroishi Kogyo Co., Ltd.) 40 Dipentamethylene thiuram- Tetrasulfide 2 Pentaerythritol 3 [Effects of the Invention] As described above, the CSM having the specific requirements of the present invention can be an extrusion-molded product having characteristics suitable for the intended use.

[Brief description of drawings]

FIG. 1a shows the glass transition point defined in the text and FIG.
Indicates the melting point.

Claims (1)

[Claims] 1. A glass transition point of -30 ° C. or lower and a chlorine content of 20.
~ 32wt%, sulfur amount 0.3 ~ 3.0wt% and weight average molecular weight M
Chlorosulfonated ethylene / α for extrusion, characterized in that the ratio of w and number average molecular weight _MN is 3.5 or more and 5.0 or less.
-Olefin copolymers.