JPS639522B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a thermoplastic elastomer using an ethylene/α-olefin copolymer rubber or an ethylene/α-olefin/diene terpolymer rubber as a raw material. It is known that ethylene/α-olefin copolymer rubber and ethylene/α-olefin/diene terpolymer rubber each have low tensile strength and large permanent strain in an unvulcanized state. Therefore, in their current state,
Since it cannot be used in applications that require rubber elasticity, various processing treatments are carried out for the purpose of use in such applications. For example, for the processing of ethylene/α-olefin copolymer rubber and ethylene/α-olefin/diene terpolymer rubber, graft copolymerization with maleic acid or maleic anhydride, etc.
Furthermore, a method is known in which a compound such as a polyvalent metal oxide (e.g. zinc oxide) is added to form salt bridges between polymer chains (Japanese Patent Publication No.
11679). In addition, we limited the ethylene/α-olefin copolymer rubber to those with specific properties,
A method is also known in which a specific amount of alkyl peroxide and unsaturated dicarboxylic acid or its anhydride is added to the mixture and heat-kneaded (Japanese Patent Laid-Open No. 52-49289
Publication No.). Among these methods, the former method of forming salt bridges is said to have a problem in that the fluidity of the product is insufficient and the processing method is severely restricted (Japanese Patent Application Laid-Open No. 52-49289, cited above). Public bulletin). On the other hand, the latter method, in which the copolymer rubber is processed by limiting the reaction raw materials and reactants to a specific range,
There is a problem in that the raw material is limited to ethylene/α-olefin copolymer rubber having a relatively low molecular weight, and the properties of the product cannot be said to be fully satisfactory. As mentioned above, conventional thermoplastic elastomers mainly composed of ethylene/α-olefin copolymer rubber are difficult to use alone; for example, copolymer rubber and resin (polyethylene, polypropylene, etc.)
It is generally used in the form of a mixture (blended product) with a copolymer rubber partially crosslinked with a peroxide and a resin. However, since these mixtures only exhibit properties intermediate between those of copolymer rubber and resin, they cannot be said to be practically advantageous. It also appears in mixtures, so it cannot be said to be satisfactory as an elastomer. The present invention is based on the conventional ethylene α-
Olefin copolymer rubber or ethylene α-
Compared to thermoplastic elastomers obtained by processing olefin-diene terpolymer rubber,
Furthermore, the present invention provides a method for producing a thermoplastic elastomer with improved various properties. The present invention provides an ethylene/α-olefin copolymer rubber or ethylene/α-olefin copolymer rubber having a weight average molecular weight in the range of 20,000 to 300,000 and comprising an α-olefin content of 20 to 50 mol% and a diene content of 0 to 15 mol%. The olefin-diene terpolymer rubber is added to the rubber in the presence of an organic peroxide.
20% by weight of maleic anhydride is graft copolymerized, and the resulting graft copolymer is treated with a compound having 0.1 mole or more of alcoholic hydroxyl groups per mole of maleic anhydride groups in the graft copolymer, Next, the obtained treated polymer is added to
A method for producing a thermoplastic elastomer characterized by ionic crosslinking with 0.1 to 0.4 moles of metal ions. The thermoplastic elastomer obtained by the production method of the present invention has good thermoplasticity, tensile strength,
Physical properties such as permanent elongation are extremely similar to vulcanized rubber, so
Rubber products that can be used for various purposes without requiring the addition of resin as mentioned above, and are intended for use under harsh conditions, such as tires for various vehicles such as automobiles. It is particularly useful as a material for The copolymer rubber used as a raw material in the method of the present invention is an ethylene/α-olefin copolymer rubber having an α-olefin content in the range of 20 to 50 mol%;
Alternatively, it is an ethylene/α-olefin/diene terpolymer rubber having an α-olefin content in the range of 20 to 50 mol% and a diene content of 15 mol% or less. Moreover, these copolymer rubbers having a weight average molecular weight in the range of 20,000 to 300,000 are used. Examples of α-olefins include propylene, 1-butene, 1-hexene, 4-methyl-
Examples of the diene include dicyclopentadiene, 1,4-hexane diene, cyclooctadiene, methylene norbornene, and ethylidene norbornene. Maleic anhydride is graft copolymerized to the above copolymer rubber in the presence of an organic peroxide.
Examples of organic peroxides include dicumyl peroxide, di-tert-butyl peroxide, tert-butylcumyl peroxide, 2,5-dimethyl-2,
Mention may be made of 5-di(tert-butylperoxy)hexane and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane-3. The organic peroxide is usually 0.02-10 milliequivalents (preferably 1-10 milliequivalents)/100g of copolymer rubber.
Use at a ratio of Examples of maleic anhydride include maleic anhydride,
Unsaturated dicarboxylic acid anhydrides such as citraconic anhydride and nadicic anhydride are used. The maleic anhydride must be graft copolymerized in a proportion within the range of 3 to 20% by weight based on the copolymer rubber. If this ratio is less than 3% by weight, even if the copolymer rubber is subjected to ionic crosslinking in a later step, the effect of improving the strength of the copolymer rubber, which is one of the objectives of the present invention, will be difficult to appear, which is undesirable. . Also the ratio is 20% by weight
Even if the value exceeds this value, the effect of improving the strength of the copolymer rubber cannot be obtained compared to a value less than that value. Other reaction conditions and specific reaction operations regarding the graft copolymerization reaction in the method of the present invention can be easily set according to the descriptions in the aforementioned Japanese Patent Publication No. 35-11679, Japanese Patent Application Laid-Open No. 52-49289, etc. be able to. After the graft copolymerization reaction is completed, a graft copolymer can be obtained by a method known per se. In the method of the present invention, the graft copolymer obtained as described above is treated with a compound having an alcoholic hydroxyl group. This treatment is based on the maleic anhydride group of the graft copolymer (i.e.
0.1 mole or more per mole of dicarboxylic acid anhydride group),
Preferably, a compound having an alcoholic hydroxyl group in an amount of 1 mole or more is used. If the amount of the compound having an alcoholic hydroxyl group used is less than the above lower limit, it will be difficult to achieve the treatment effect. The above-mentioned compounds having an alcoholic hydroxyl group include methanol, ethanol, n-propanol, iso-propanol, n-butanol, t-
Butanol, ethylene glycol, propylene glycol, phenol, butylated hydroxytoluene (BHT), etc. are used. The above treatment usually involves adding the graft copolymer to a solution state by adding it to a suitable solvent that dissolves the copolymer rubber and does not inhibit the graft copolymerization reaction, such as benzene, toluene, xylene, chlorobenzene, hexane, etc. Add the above-mentioned compound having an alcoholic hydroxyl group to this to form a solution or slurry, and if necessary, mix the mixture further for 10 to 10 minutes.
This is carried out by stirring and mixing at 80°C, usually at room temperature, for 0.1 to 30 minutes. The graft copolymer may contain a large amount of gel. Moreover, a compound having an alcoholic hydroxyl group can also be used as a solvent. In the method of the present invention, by treating the graft copolymer with a compound having an alcoholic hydroxyl group, a thermoplastic elastomer having excellent strength properties and thermal fluidity (thermoformability) can be obtained upon ionic crosslinking. . After the graft copolymer is treated with a compound having an alcoholic hydroxyl group as described above, in the method of the present invention, the obtained treated polymer is subjected to ionic crosslinking. This ionic crosslinking is achieved by 0.1 to 0.4 mol of sodium per 1 mol of maleic anhydride groups in the treated polymer (total of dicarboxylic acid anhydride groups ring-opened by the above treatment and those not ring-opened). ion, potassium ion, zinc ion,
This is carried out using metal ions such as calcium ions, magnesium ions, and copper ions. In the ionic crosslinking reaction, sodium,
The reaction is carried out by adding an aqueous or alcoholic solution of a compound or salt of a metal such as potassium, zinc, calcium, magnesium, or copper, such as a hydroxide, formate, acetate, or alkoxide. It is also possible to carry out the ionic crosslinking reaction without using a solvent. The metal ions are introduced into the treated polymer and crosslinked in an amount of 0.1 to 0.4 mol per 1 mol of maleic anhydride groups in the treated polymer. If the amount of metal ions introduced is less than 0.1 mol, the strength improvement effect due to ionic crosslinking will not be sufficiently achieved, and if it exceeds 0.4 mol, the thermal fluidity of the resulting ionically crosslinked copolymer rubber will be impaired, so it is preferable. do not have. Since the reaction mode of the ionic crosslinking reaction is based on an ionic reaction, it is carried out quickly and is not subject to any particular restrictions on the reaction temperature. However, in consideration of ease of reaction operation, the reaction temperature is preferably in the range of 10 to 80°C, and it is particularly preferable to carry out the reaction at room temperature. The reaction time depends on the treated polymer and
This is the time required to achieve uniform contact with metal ions, and 30 to 60 minutes is usually sufficient. Next, Examples and Comparative Examples of the present invention will be shown. Example 1 Propylene content 30 mol%, weight average molecular weight
20g of 120000 ethylene-propylene copolymer rubber
was dissolved in 200 ml of orthodichlorobenzene. Next, 2 g of maleic anhydride and 0.18 g of dicumyl peroxide were added at 80°C, stirred for 30 minutes in a nitrogen atmosphere to uniformly dissolve and mix, and then the temperature of the reaction system was raised to 135°C. Anhydrous maleation reaction (graft copolymerization reaction) was carried out for 4 hours. After cooling the reaction mixture, rubber components were precipitated, washed, and collected using 500 ml of acetone. After drying under reduced pressure at 40°C overnight, the maleic anhydride content of the rubber was 4.00% by weight, and the Soxhlet extraction residue (gel content) using toluene as a solvent was 1.8% by weight. Next, when 20 g of the anhydrous maleated rubber (graft copolymer) was dissolved in 200 ml of benzene at 60°C, some insoluble matter was observed, but methanol
When 1.0 ml was added, it quickly became a homogeneous solution. To this homogeneous solution was added 5 ml of an aqueous solution in which 0.082 g of sodium chloride (0.25 mol per 1 mol of maleic anhydride groups in total) was dissolved, and after stirring for 60 minutes, 500 g of acetone was added.
ml was used to recover the ionically crosslinked rubber. The ionically crosslinked rubber flows easily in a hot press at 180°C to form a uniform sheet. Test pieces were punched out from this sheet and tested for physical properties at 23°C. 100% elongation modulus (M ₁₀₀ ): 13.3 Kg/cm ² Strength at break (T _B ): 234.2 Kg/cm ² Elongation at break (E _Lb ): 740% Permanent elongation (E _Le ): 2.25%. However, the tensile test was conducted using a JIS No. 3 dumbbell at a tensile speed of 50 mm/min. Permanent elongation test is performed by holding 100% elongation for 10 minutes and removing tension.
This was done by measuring the elongation after 10 minutes. Comparative Example 1 An ionically crosslinked rubber having the following physical properties was obtained by carrying out exactly the same operation as in Example 1, except that the methanol treatment was not performed before the ionic crosslinking step using sodium chloride. M ₁₀₀ : 13.6Kg/cm ² T _B : 105.9Kg/cm ² E _Lb : 655% E _Le : 2.50% Example 2 A maleic anhydride reaction similar to that in Example 1 was carried out (using 3.5 g of maleic anhydride). ) A maleic anhydride copolymer having a maleic anhydride content of 5.40wt% (weight%, same hereinafter) was obtained. When the rubber was subjected to Soxhlet extraction using toluene as a solvent, it was found to be 3.8wt%.
There was an extraction residue (gel fraction). Next, when 20 g of the anhydrous maleated rubber was dissolved in 200 ml of benzene at 40°C, a considerable amount of insoluble matter was observed, but 6.1 ml of ethylene glycol (10 times the mole based on the maleic anhydride group) was added. The solution quickly became a homogeneous solution. Add 0.132g of possible soda to this homogenized solution.
(0.3 mol per 1 mol of maleic anhydride groups) was added to the mixture and stirred for 30 minutes to form ionic crosslinks, and then 500 ml of acetone was added to recover the ionically crosslinked rubber. The ionically crosslinked rubber flows easily even in a heat press at 160°C.
Form a uniform sheet. The following results were obtained by measuring physical properties at 23°C. M ₁₀₀ : 15.0Kg/cm ² T _B : 206.5Kg/cm ² E _Lb : 680% E _Le : 3.0% Comparative Example 2 Completely the same operation as Example 2 except that the homogenization operation by adding ethylene glycol was not performed. An ionically crosslinked rubber having the following physical properties was obtained. M ₁₀₀ : 14.5Kg/cm ² T _B : 63.5Kg/cm ² E _Lb : 525% E _Le : 3.3% Example 3 Maleic anhydride was obtained by carrying out the same graft reaction as in Example 1 (using 6 g of maleic anhydride). acid content
6.96wt% of anhydrous maleated copolymer was obtained. Soxhlet extraction residue (gel fraction) with toluene solvent
was 6.6wt%. Next, 20g of the anhydrous maleated rubber was added to toluene.
When dissolved in 200ml at 60℃, it only swelled.
It was virtually insoluble. Methanol 5.7 to this system
ml (10 times the mole relative to the maleic anhydride group), a homogeneous solution was quickly obtained. To this homogenized solution, 5 ml of an aqueous solution containing 0.114 g of sodium chloride (0.2 mol per 1 mol of maleic anhydride group) was added and stirred at 60°C for 30 minutes to form ionic crosslinks. 500 ml of ion crosslinked rubber was collected. The rubber flows easily even in a hot press at 160°C to form a uniform sheet. The following results were obtained by measuring physical properties at 23°C. M ₁₀₀ : 13.9Kg/cm ² T _B : 224.4Kg/cm ² E _Lb : 650% E _Le : 2.00% Comparative Example 3 In the method of Example 3, it was possible to maintain the heterogeneity without methanol treatment. Aqueous soda solution was added. The resulting sample did not flow even when hot pressed at 180°C, and it was not possible to form a sheet for measuring physical properties. Examples 4 to 11, Comparative Examples 4 to 6 The graft copolymers shown in Table 1 were synthesized by changing the amount of maleic anhydride used, and the types and amounts of alcohol and the types and amounts of metal compounds were shown in Table 1. Example 1 was carried out in the same manner as in Example 1 except for the changes shown in . The results are summarized in Table 1. 【table】

Claims (1)

[Claims] 1 Ethylene/α-olefin copolymer rubber or ethylene/α-olefin/diene having a weight average molecular weight in the range of 20,000 to 300,000 and containing 20 to 50 mol% of α-olefin and 0 to 15 mol% of diene. The terpolymer rubber is graft copolymerized with 3 to 20% by weight of maleic anhydride based on the rubber in the presence of an organic peroxide, and the resulting graft copolymer is The treated polymer is treated with a compound having 0.1 mole or more of alcoholic hydroxyl groups per mole of maleic anhydride groups, and then the treated polymer is treated with a compound having alcoholic hydroxyl groups of 0.1 to 0.1 mole or more per mole of maleic anhydride groups in the treated polymer. A method for producing a thermoplastic elastomer, characterized by ionic crosslinking with 0.4 moles of metal ions.