JPH01299808A - Preparation of acrylic copolymer elastomer - Google Patents

Abstract

PURPOSE:To prepare the title elastomer having excellent fuel oil resistance and freeze resistance, by copolymerizing a specified (meth)acrylate, a crosslinking point forming monomer and a specified unsatd. monomer in the presence of a radical initiator. CONSTITUTION:50-99.5wt.% (meth)acrylate (A) of formula (wherein R1 is H or CH3; n is 1 or larger, the number average value is 1-5), 0.5-10wt.% crosslinking point forming monomer (e.g., vinyl chloroacetate) and 0-50wt.% at least one monomer being copolymerizable with said both components A and B selected from monovinyl or monovinylidene unsatd. monomers besides the components A and B (e.g., ethyl acrylate, acrylonitrile etc.) are copolymerized in the presence of a radical polymn. initiator (e.g., radical initiators of peroxides, redox type etc.) to obtain the title elastomer having excellent fuel oil resistance and freeze resistance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a novel copolymer elastomer, and more specifically to the production of an acrylic copolymer elastomer that has excellent fuel oil resistance and cold resistance. It is about the method.

[Prior Art] Polymers of acrylic acid alkyl esters are known as acrylic rubbers. Acrylic rubber has excellent heat resistance and resistance to lubricating oil, so it is widely used in oil seals and the like.

However, acrylic rubber has no resistance to fuel oils that are harsher than lubricating oils such as gasoline, that is, have low aniline points, and its range of use is limited to lubricating oils.

In order to improve the fuel oil resistance of acrylic rubber, attempts have been made to copolymerize monomers with highly polar functional groups such as cyano groups and fluorine-containing groups as copolymerization components, but it is difficult to introduce these polar groups. This raises the problem that the glass transition point of the copolymer increases and the low-temperature properties of the resulting copolymer elastomer are impaired.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing an acrylic copolymer elastomer having excellent both low-temperature properties and fuel oil resistance. By using an acrylic acid elastomer with a specific structure as one of the monomer components constituting the acrylic elastomer, the present inventors have improved fuel resistance and produced an elastomer with excellent low-temperature properties. This discovery led to the present invention.

[Means for solving the problem] (A) Acrylic ester and/or methacrylic ester having the structure of the following formula (1) 50 to 99.5% by weight (where R1 is hydrogen or a methyl group, and n is 1 or more (B) Crosslinkable monomer 0.5 to 10% by weight (C) (A) and (B) above
Copolymerizing in the presence of a radical initiator 0 to 50% by weight of at least one monomer selected from monovinyl or monovinylidene unsaturated monomers other than (A) and (B) that can be copolymerized with The present invention relates to a method for producing an acrylic copolymer elastomer characterized by the following.

The component (A) is an acrylic ester and/or a methacrylic ester having a structure represented by general formula (I).

(Here, R1 is hydrogen or a methyl group, n is an integer of 1 or more, and its number average value is 1 to 5) The acrylic ester or methacrylic ester of component (A) is usually a general When produced according to the standard production method, it is obtained as a mixture of substances having different molecular weights, that is, different numbers of n in formula (1), but it is possible to use the mixture as it is. Of course, there is no problem in using acrylic ester or methacrylic ester separated by distillation or the like and having no distribution in molecular weight.

In the present invention, the numerical average value of n is 1-5.

If the number average value of n is too large, the degree of unsaturation becomes low, the degree of polymerization decreases, and the effect of improving fuel resistance is also small, which is not preferable. In addition, the acrylic ester or methacrylic ester of component (A) includes 2-cyanoethyl acrylate or 2-cyanoethyl methacrylate represented by the following formula (n).
Cyanoethyl may be mixed in due to the manufacturing method, but 10
There is no particular problem if it is less than % by weight.

(Here, R1 is hydrogen or methyl group) The acrylic ester or methacrylic ester of component (A) has the formula (
Known methods for synthesizing acrylic esters by reacting a compound having the structure represented by III) with acrylic acid or methacrylic acid, or known acrylic acid ester synthesis methods by reacting compound (III) with acryloyl halide or methacryloyl halide. It can be easily synthesized by a method similar to that of esters.

CNCII -CI+ -(-0-C-(CI ≠
→ −011(I!I)22 25n (where n is an integer greater than or equal to 1, and the number average value is 1 to
It is 5. ) The compound having the structure represented by formula (III) is synthesized by a known method of ring-opening addition of ε-caprolactone to ethylene cyanohydrin in the presence of a catalyst. Catalysts used in the ring-opening addition reaction of ε-caprolactone include organic titanium compounds such as tetraethoxytitanium and tetrabutoxytitanium, dibutyltin dilaurate,
Organic tin compounds such as dibutyltin oxide, halogenated tin compounds such as stannous chloride, perchloric acid, and the like are known. Further, the amount of ε-caprolactone added in the above compound, that is, the number average value of n, can be adjusted by changing the molar ratio of ethylene cyanohydrin and ε-caprolactone used in the reaction.

The above component (B) is a unit that acts as a crosslinking point during vulcanization in the copolymer elastomer of the present invention, and is a unit containing an active functional group such as an active halogen group or an epoxy group or a carboxylic acid group in the molecule. Saturated compounds are used. Specific examples of the active halogen-containing unsaturated compound include 2-chloroethyl vinyl ether, vinyl chloroacetate, allyl chloroacetate, chloromethylstyrene, 2-chloroethyl acrylate, and 2-chloroethyl methacrylate. Examples of the epoxy group-containing unsaturated compound include allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate. In addition, unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid,
Examples include itaconic acid. Components in all monomers used (B
) is 0.5 to 10% by weight, preferably 1 to 5% by weight. These crosslinkable monomers can be used alone or in a mixture of two or more. component(
If the amount of B) is small, vulcanization will be sufficient; if it is too large, vulcanization will proceed excessively, making it impossible to obtain a satisfactory vulcanized rubber sheet.

- It is also possible to further add component (C) to the above essential components (A) and (B) within a range that does not impair the effects of the present invention. Component (C) is the above essential component (A) and (B)
At least one monomer selected from monovinyl or monovinylidene unsaturated monomers other than (A) and (B) that can be radically copolymerized with methyl acrylate, ethyl acrylate, etc. , acrylic acid n
- Acrylic acid alkyesters such as butyl and 2-ethylhexyl acrylate, acrylic acid alkoxyalkyl esters such as methoxyethyl acrylate and ethoxyethyl acrylate, methacrylic acid esters such as methyl methacrylate and ethyl methacrylate, vinyl acetate , acrylonitrile, methacrylonitrile, styrene, etc. The maximum amount of component (C) in all the monomers used without impairing the effects of the present invention varies depending on the type of compound, but is at most 50% by weight.

In the present invention, the acrylic copolymer elastomer of the present invention can be produced by using a commonly used radical initiator to form the acrylic copolymer elastomer of the present invention by a known method such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization. It can be easily manufactured. Emulsion polymerization is preferred as the polymerization method.

As the radical polymerization initiator, common radical initiators such as peroxides, redox compounds, persulfates, and azo compounds can be used. Polymerization is possible in the temperature range from 0 to 100°C, preferably from 5 to 80°C.

The co-m6 elastomer obtained by polymerization can be easily isolated by salting out using an aqueous solution of an inorganic salt such as chloride or sodium chloride or by using a polymer-insoluble solvent such as methanol.

The acrylic copolymer elastomer produced by the method of the present invention can be vulcanized by the same method as the commonly known acrylic rubber vulcanization method. Vulcanization is performed by adding a component (B) that acts as a crosslinking point to the copolymer elastomer.
A vulcanizing agent selected depending on the type of vulcanizing agent, and a vulcanizing accelerator if necessary.

This is done by adding reinforcing agents, fillers, plasticizers, anti-aging agents, stabilizers, etc.

[Examples] The present invention will be specifically explained below using Examples, but the scope of the present invention is not limited thereto.

Synthesis Example 1 A three-hole flask equipped with a stirrer and a condenser was charged with 335 parts by weight of ethylene cyanohydrin and 114 parts by weight of ε-caprolactone, and heated while stirring. temperature is 120℃
When the temperature reached 0.075 parts by weight of stannous chloride, the temperature was maintained and the reaction was carried out for about 4 hours under a nitrogen atmosphere. The conversion rates of ethylene cyanohydrin and ε-cabrolactone after the reaction were 12.8% and 98.2%, respectively.
%Met. Further, unreacted ethylene cyanohydrin was removed from the reaction product by heating under reduced pressure to obtain a caprolactone adduct having a hydroxyl group at the end. The average molecular weight of the obtained caprolactone adduct was 252. Here, the conversion rates of ethylene cyanohydrin and ε-caprolactone are determined by using a gas chromatograph, and the average molecular weight of the caprolactone adduct is determined by JIS KOO
It was determined from the KOH value measured according to 70.

250 parts by weight of the obtained caprolactone oligomer,
100 parts by weight of acrylic acid, 10 parts by weight of hydroquinone, 500 parts by weight of toluene, and 3 parts by weight of sulfuric acid were charged into a flask equipped with a stirrer, a condenser, and a separator to carry out an esterification reaction. The water produced by the reaction was distilled and condensed together with the solvent, removed from the thread by a separator, and only the solvent was returned to the reaction system. When no water was produced, the reaction was stopped by cooling.

The resulting reaction solution was neutralized with a 20% aqueous sodium hydroxide solution, washed several times with a 20% aqueous sodium chloride solution,
The solvent was removed under reduced pressure to obtain the desired pale yellow acrylic ester. This one has R1=H- in formula (1)
, corresponds to a compound with an average value of n of 1.6. The content of 2-cyanoethyl acrylate in this acrylic ester was 596.

Here, the terminal unsaturated group was determined by the morpholine method, and the content of 2-cyanoethyl acrylate in the obtained acrylic ester was determined by gas chromatography.

Synthesis Example 2 A caprolactone adduct was synthesized in the same manner as in Synthesis Example 1. The conversion rates of ethylene cyanohydrin and ε-caprolactone after the reaction were 13% and 99%, and the molecular weight of the obtained caprolactone addition compound was 235. An esterification reaction was carried out in the same manner as in Synthesis Example 1 to obtain the desired acrylic ester. This compound corresponds to a compound in which the average value of R1=HSn is 1.5 in formula (1). Also, acrylic acid 2- in this acrylic ester
The content of cyanoethyl was 9%.

Synthesis Example 3 A caprolactone adduct was synthesized in the same manner as in Synthesis Example 1. The conversion rates of ethylene cyanohydrin and ε-caprolactone after the reaction were 12.5% and 100%,
The resulting caprolactone adduct had a molecular weight of 256. Methacrylic acid 125 parts, Hydroquinone 12 parts
．． The esterification reaction was carried out in the same manner as in Synthesis Example 1 except that 5 parts by weight was used to obtain the desired methacrylic acid ester. This compound corresponds to the compound of formula (1) with R-CI+3 and an average value of n of 1.6. The content of 2-cyanoethyl methacrylate in this methacrylic ester was 6%.

Examples 1-7. Comparative Examples 1 to 3 One-fifth of the mixture of the monomer mixture having the composition shown in Table 1 and n-dodecylmercaptan (variable depending on the monomer composition to adjust the molecular weight) was mixed with 4 parts by weight of sodium dodecylbenzenesulfonate and polyoxyethylene lauryl. 2 parts by weight of ether, 1 part by weight of naphthalene sulfonate, 0.2 fffm part of tripotassium phosphate, and 200 fflJ of distilled water.
The mixture was mixed and stirred with an emulsifier solution consisting of 1 part to emulsify. The temperature of this emulsion was 10°C, and 0.01 part by weight of ferrous sulfate was added.

Polymerization was started by adding 0.02 part by weight of disodium ethylenetetraacetate and 0.01 part by weight of paramenthane hydroperoxide.

Thereafter, while maintaining the temperature at 10° C., the remaining monomer mixture was added dropwise over about 6 hours, and at the same time, 0.05 part by weight of para-menthane hydroperoxide was added in portions. After the monomer dropwise addition was completed, the polymerization was continued for another 4 hours, and then an inhibitor was added to terminate the polymerization. Monomer conversion rate is 95-99%
Met. The obtained copolymer latex was poured into an aqueous calcium chloride solution at 80° C. to isolate the copolymer, thoroughly washed with water, and then dried to obtain a copolymer elastomer.

Examples 1-5. The copolymer elastomer obtained in Comparative Example 1 was roll-kneaded according to the formulation shown in Table 2, and then mixed at 170°C for 2 hours.
A vulcanized rubber sheet was prepared by press vulcanization for 0 minutes. This was further heat-treated at 150° C. for 4 hours in a gear oven, and then the physical properties of the vulcanized rubber were evaluated. Further, the copolymer elastomers obtained in Examples 6 and 7 and Comparative Example 23 were roll kneaded according to the formulations shown in Table 3, and press vulcanization was performed at 170° C. for 30 minutes to prepare a vulcanized rubber sheet. This was further heat-treated at 150° C. for 8 hours in a gear oven, and then the physical properties of the vulcanized rubber were evaluated.

Table 4 shows Examples 1 to 7. The physical properties of unvulcanized rubber and the physical properties of vulcanized rubber of Comparative Examples 1 to 3 are shown. Mooney viscosity is JIS K6
300 vulcanized rubber physical properties were evaluated according to JISK6301. Fuel resistance is 72% when vulcanized rubber is placed in fuel oil C at 40°C.
Evaluation was made by measuring the rate of change in volume after being immersed for two hours. Further, the glass transition temperature was measured using an unvulcanized rubber as a sample using a differential scanning calorimeter (DSC) at a heating rate of 10° C. per minute.

Table 2 Acrylic copolymer elastomer 100 parts by weight Stearic acid 1-Bon Black M
AF 50 Sodium Stearate
3 Potassium stearate 0.
5 Sulfur 0. Table 3 Acrylic copolymer elastomer 100 parts by weight Stearic acid 1-Bon Black M
AF 50 Ammonium Benzoate
1 [Effects of the Invention] As is clear from the above description, the present invention provides a novel elastomer that is excellent in both fuel oil resistance and cold resistance.

Claims (1)

[Claims] (1) (A) Acrylic ester and/or methacrylic ester having the structure of the following formula (I) 50 to 99.5% by weight ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (I) (Here, R_1 is hydrogen or Methyl group, n is an integer of 1 or more, and its number average value is 1 to 5) (B) 0.5 to 10% by weight of crosslinkable monomer (C) (A) and (B) above Copolymerizing in the presence of a radical initiator 0 to 50% by weight of at least one monomer selected from monovinyl or monovinylidene unsaturated monomers other than (A) and (B) that can be copolymerized with A method for producing an acrylic copolymer elastomer characterized by: