JPH04198310A - Acrylic copolymer elastomer containing cyano group - Google Patents

Abstract

PURPOSE:To obtain the subject elastomer having excellent fuel oil resistance, freeze resistance and thermal aging resistance and useful for automobile part, etc., by copolymerizing a mixture of specific cyano-containing (meth)acrylates, ethyl acrylate, etc., and allyl glycidyl ether, etc. CONSTITUTION:The objective elastomer having a Mooney viscosity [ML1+4(10 deg.C)] of >=10 can be produced by copolymerizing (A) 5-50wt.% of a cyano-containing (meth)acrylic acid ester mixture consisting of a 2-(2- cyanoethoxy)ethyl (meth)acrylate of formula I (R is H or methyl) and a (meth) acrylic acid ester of a cyano-containing epsilon-caprolactone oligomer of formula II (n is 1-10), (B) 94.5-50wt.% of ethyl acrylate which may contain <=50wt.% of n-butyl acrylate and (C) 0.5-10wt.% of vinyl chloroacetate or one or more compounds selected from allyl glycidyl ether and glycidyl methacrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a new copolymer elastomer, and more particularly to a novel acrylic copolymer elastomer with excellent fuel oil resistance.

[Prior Art] Special rubber is widely used as automobile parts. In recent years, with the increasing performance of automobiles, there has been a demand for high-performance special rubbers, especially special rubbers with a good balance of heat resistance, oil resistance, and cold resistance.

However, since oil resistance and cold resistance are contradictory properties, it has been difficult to improve both of them. For example, in order to improve oil resistance, a method is usually used to copolymerize monomers such as ethyl acrylate and tolyl methacrylate containing polar groups such as cyano groups; As a result of increased polarity, the glass transition point increases and cold resistance deteriorates.

Examples of cyano group-containing copolymer elastomers with well-balanced oil resistance and cold resistance include acrylic elastomers containing (meth)acrylic acid esters of cyano group-containing ε-caprolactone oligomers as a copolymerization component (JP-A-2-1).
No. 64860, etc.) is known.

[Problems to be Solved by the Invention] However, while the above-mentioned cyano group-containing copolymer elastomer exhibits excellent oil resistance and cold resistance, the reactivity of the terminal ester group is relatively high, and the copolymer elastomer obtained There was a problem in that there was a limit to the heat aging resistance of the combination.

[Means for Solving the Problems] In view of the above-mentioned problems, an object of the present invention is to provide an acrylic elastomer that does not impair oil resistance, fuel oil resistance, or cold resistance and has excellent heat aging resistance. be.

By using an acrylic acid ester having a specific structure as a component of the monomer constituting the acrylic elastomer, the present inventors have achieved a method that does not impair the oil resistance, fuel oil resistance, and cold resistance of the acrylic elastomer. The inventors have discovered that heat aging resistance is improved and have arrived at the present invention.

The present invention provides (A) 2-(2-cyanoethoxy)ethyl (meth)acrylate represented by the following general formula (I) and a cyano group-containing ε-caprolactone oligomer represented by the following general formula (II). Cyano group-containing (meth)acrylic acid ester mixture consisting of (meth)acrylic acid ester, 5 to 50% by weight (R is common in formulas (I) and (II) and represents hydrogen or a methyl group. Also, formula ( n in II) is ε-
(B) Ethyl acrylate or ethyl acrylate containing up to 50% by weight of n-butyl acrylate, 94.5
~50% by weight (C) At least one of allyl glycidyl ether and glycidyl methacrylate, or vinyl chloroacetate, has a composition of 0.5 to 10% by weight, and has a Mooney viscosity [ML1+4 (100 ° C.)] of 10 or more. This invention relates to an acrylic copolymer elastomer.

In the cyano group-containing (meth)acrylic acid ester mixture of component (A) of the present invention, (meth) represented by formula (I)
The amount of 2-(2-cyanoethoxy)ethyl acrylate is 7
It is 0% by weight or less, preferably 50% by weight or less. If the amount of 2-(2-cyanoethoxy)ethyl (meth)acrylate is too large, the effect of lowering the glass transition point of the resulting polymer will be undesirably reduced.

Further, the compound represented by formula (II) is an acrylic acid or methacrylic acid ester of a cyano group-terminated ε-caprolactone oligomer, and is a mixture of compounds having different amounts of ε-caprolactone added. n in formula (n) represents the number average value of addition 2 of ε-caprolactone.

The value of n in the cyano group-containing (meth)acrylic acid ester mixture of component (A) of the present invention is from 1 to 10, preferably from 1 to 5. If n is too large, the effect of improving the oil resistance of the resulting polymer will decrease, which is not preferable.

The cyano group-containing (meth)acrylic acid ester mixture of the present invention can be easily synthesized, for example, by the method described below.

[1] Cyanoengineering reaction In the presence of a basic catalyst such as an alkali-11 metal hydroxide,
(2-cyanoethoxy)ethanol is synthesized by a known method of reacting ethylene glycol and acrylonitrile.

[2] ε-caprolactone addition reaction (2-cyanoethoxy) Using ethanol as an initiator, a ring-opening addition reaction is carried out in the presence of a catalyst to produce ε-caprolactone, which has a hydroxyl group at the terminal represented by formula (m). A cyano group-containing ε-caprolactone oligomer is synthesized. Here, n represents the average value of the amount of ε-caprolactone added, and the value is 1 to
It is 10.

Catalysts used in the ring-opening addition reaction of ε-caprolactone include organic titanium compounds such as tetraethoxytitanium and tetrabutoxytitanium, organic tin compounds such as dibutyltin dilaurate and dibutyltin oxide, tin halide compounds such as stannous chloride, Commonly known catalysts such as perchloric acid can be used. Also, the above formula (
The size of n in III) can be adjusted by changing the quantitative ratio of (2-cyanoethoxy)ethanol and ε-caprolactone used in the reaction.

The reaction is carried out at a molar ratio of (2-cyanoethoxy)ethanol and ε-caprolactone of 571 to 1/10, preferably 2.
/1 to 115. Unreacted (2-cyanoethoxy)ethanol remains in the ε-caprolactone oligomer (■) obtained by the reaction. It is possible to remove unreacted (2-cyanoethoxy)ethanol by distillation under reduced pressure or the like, or it is usually used in the next reaction without being removed.

[3] Engineering esterification reaction ε-caprolactone oligomer (m
) and (2-cyanoethoxy)ethanol, and an esterification reaction with acrylic acid or methacrylic acid, or a derivative thereof, to synthesize the cyano group-containing (meth)acrylic ester mixture of the present invention. Here, the derivatives of acrylic acid or methacrylic acid include acryloyl halides or methacryloyl halides such as acryloyl chloride and methacryloyl chloride, or acrylic acids or methacrylic acids such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate. Examples include lower alcohol esters of acids.

To give an example, ε-caprolactone oligomer (m
) and (2-cyanoethoxy)ethanol, and acrylic acid or methacrylic acid are dissolved in an organic solvent such as benzene, toluene, xylene, or cyclohexane, and heated in the presence of an acid catalyst such as sulfuric acid or para-toluenesulfonic acid. The desired cyano group-containing (meth)acrylic acid ester mixture represented by formula (I) can be synthesized by carrying out the reaction, neutralizing and washing, and then removing the solvent.

In the present invention, component (B) is ethyl acrylate or 5
Ethyl acrylate containing 0% or less n-butyl acrylate. In the case of a mixture of ethyl acrylate and n-butyl acrylate, the amount of n-butyl acrylate in the mixture is not more than 50% by weight. Acrylic acid n- in the mixture
If the amount of butyl exceeds 50% by weight, the fuel oil resistance will deteriorate, which is not preferable. Its amount in the total monomers used is 9
It is 4.5 to 50% by weight. If component (B) is less than 50% by weight, the heat resistance and mechanical strength of the resulting copolymer elastomer are undesirably reduced.

The component (C) is a unit that acts as a crosslinking point during vulcanization in the copolymer elastomer of the present invention. Specifically, it is at least one of allyl glycidyl ether and glycidyl methacrylate, or vinyl chloroacetate.

The amount of component (C) in the total monomers used is 0.5 to 10% by weight.
It is. These crosslinking monomers can be used alone or in a mixture of two or more. If the amount of component (C) is too small, vulcanization cannot be performed sufficiently, and if it is too large, vulcanization proceeds excessively, making it impossible to obtain a satisfactory vulcanized sheet.

The acrylic elastomer of the present invention can be easily produced by copolymerizing a mixture of the above monomers in the presence of a radical initiator using known methods such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. can. Emulsion polymerization is particularly 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. The polymerization temperature ranges from 0 to 100°C, preferably from 5 to 80°C.

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

The acrylic copolymer elastomer of the present invention preferably has a Mooney viscosity [ML1+4 (100°C)] of 10 or more for ease of processing.

Preferably it is in the range of 20-80.

The acrylic copolymer elastomer of the present invention can be vulcanized by the same method as the commonly known acrylic rubber vulcanization method. Vulcanization is performed by using a vulcanizing agent selected depending on the type of component (C) that acts as a crosslinking point for the copolymerized elastomer, and adding vulcanization accelerators, reinforcing agents, fillers, plasticizers, and anti-aging agents as necessary. Vulcanized rubber can be easily obtained by blending agents, stabilizers, etc. For example, when component (C) is vinyl chloroacetate, the vulcanizing agent is a combination system of metal soap such as sodium stearate or potassium stearate and sulfur, a combination system of metal soap and pentamethylene thiuram polysulfide (TRA), ammonium Organic carboxylic acid ammonium salts such as benzoate and ammonium adipate are used. When component (C) is at least one of glycidyl methacrylate and allyl glycidyl ether, carbamate compounds such as hexamethylene diamine caramate, ammonium benzoate, polyamines, etc. are used as the vulcanizing agent.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the scope of the present invention is not limited thereto.

[Example] In the following description, parts represent parts by weight. Furthermore, the measurement method and conditions for the measured values described in the examples are as follows.

・Infrared absorption spectrum: A small amount of sample is
Measurements were made between plates at room temperature under a nitrogen atmosphere.

・Double bond amount: Morpholine method (225 in ``Monomer I'', Volume 2 of ``Experimental Polymer Science'', edited by the Editorial Committee of Experimental Polymer Science, Japan Society of Polymer Science)
Quantification was carried out according to the method described on page 1). However, in the case of methacrylic acid ester, acetic acid is used instead of methanol as a solvent during the morpholine addition reaction, and 100%
The reaction was carried out at ℃ for 2 hours.

・Conversion rate of 2-(2-cyanoethoxy)ethanol and ε-caprolactone and (meth)acrylic acid 2-(2-
Cyanoethoxy)ethyl content: Measured by internal standard method using a gas chromatograph.

-Glass transition point, using unvulcanized rubber as a sample, was measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C.・Vulcanized rubber physical properties: 11 according to JIS K6301
Established. -Fuel oil resistance: Evaluated by volume change after immersing vulcanized rubber in fuel oil C at 40°C for 72 hours.

Synthesis Example 1 (1) Cyanoethylation Reaction 1240 parts of ethylene glycol and 40 parts of a 40% by weight aqueous potassium hydroxide solution were charged into a reactor equipped with a stirrer, a dropping funnel and a condenser, and the mixture was heated at a temperature of 25° C. with stirring.
30 parts of acrylonitrile was added dropwise over about 2 hours to carry out the reaction. After the completion of dropping acrylonitrile, at 30”C
A time reaction was performed.

After neutralizing with a 25% by weight aqueous sulfuric acid solution, 2-(2-cyanoethoxy)ethanol was separated and recovered from the reaction product by distillation under reduced pressure.

(2) 2-(2-cyanoethoxy)ethanol 920 obtained from ε-caprolactone addition reaction
A reactor was charged with 912 parts of ε-caprolactone, and 0.916 parts of tetrabutoxytitanium, and the reaction was carried out at 130°C under a nitrogen atmosphere for about 5 hours to form 2-(2-cyanoethoxy)ethanol and cyano group-containing ε- A mixture of caprolactone oligomers was obtained. The conversion rates of 2-(2-cyanoethoxy)ethanol and ε-caprolactone after the reaction were 41.3% and 99.5%, respectively.

(3) Mixture of 2-(2-cyanoethoxy)ethanol obtained by esterification reaction and cyano group-containing ε-caprolactone oligomer 700
330 parts of acrylic acid, 650 parts of toluene, 30 parts of hydroquinone, and 40 parts of para-toluenesulfonic acid were charged into a reactor equipped with a stirrer, a condenser, and a separator, and an esterification reaction was carried out. Water produced as a by-product in the reaction was distilled and condensed together with toluene and removed from the thread using a separator, and only toluene was returned to the reaction system. When no water was produced, the reaction was stopped by cooling. After neutralizing the obtained reaction solution with a 10% by weight aqueous sodium hydroxide solution, 20% by weight
The mixture was washed several times with an aqueous sodium chloride solution, and the solvent was removed under reduced pressure to obtain the desired pale yellow cyano group-containing ε-caprolactone oligomer acrylic ester mixture.

The infrared absorption spectrum of the obtained cyano group-containing ε-caprolactone oligomer acrylic ester mixture revealed that cyano group (2250 cm"-1) and ether group (1130 cm"-1)
cm-”), y-stell groups (1730 cm-1) and acryloyl groups (1620 and 1640 cm-1)
The existence of was confirmed.

The average molecular weight of the acrylic ester mixture calculated from the amount of double bonds was 295, and the content of (2-cyanoethoxy)ethyl acrylate was 30% by weight. The value of n in formula (II) calculated from these results is 1.6. Table 1 shows the contents of carbon, hydrogen, and nitrogen calculated from the elemental analysis results and the amount of double bonds. Both values were almost the same.

From the above results, it is clear that the desired cyano group-containing ε-caprolactone oligomer acrylic ester mixture was obtained.

Synthesis Example 2 The reaction was carried out in the same manner as in Synthesis Example 1, except that 1270 parts of 2-(2-cyanoethoxy)ethanol and 627 parts of ε-caprolactone were used in the ε-caprolactone addition reaction, and 440 parts of acrylic acid was used in the esterification reaction. A cyano group-containing ε-caprolactone oligomer acrylic ester mixture was synthesized. The conversion rates of 2-(2-cyanoethoxy)ethanol and ε-caprolactone after the reaction were 28.7% and 9960%, respectively.

The infrared absorption spectrum of the obtained cyano group-containing ε-caprolactone oligomer acrylic ester mixture revealed cyano groups (2250 cm) and 1-thyl groups (1130 cm).
m-''), ester groups (1730 cm'') and acryloyl groups (1620 and 1640 cm-1) were confirmed.

The average molecular weight of the acrylic ester mixture calculated from the amount of double bonds was 240, and the content of (2-cyanoethoxy)ethyl acrylate was 47% by weight. The value of n in equation (n) calculated from these results is 1.2. Table 1 shows the contents of carbon, hydrogen, and nitrogen calculated from the elemental analysis results and the amount of double bonds. Both values were almost the same.

From the above results, it is clear that the desired cyano group-containing ε-caprolactone oligomer acrylic ester mixture was obtained.

Synthesis Example 3 In ε-caprolactone addition reaction, 632 parts of 2-(2-cyanoethoxy)ethanol, 1 part of ε-caprolactone
A cyano group-containing ε-caprolactone oligomer acrylic ester mixture was synthesized by carrying out the reaction in the same manner as in Synthesis Example 1 except that 220 parts of acrylic acid was used in the esterification reaction. The conversion rates of 2-[2-cyanoethoxycoethanol and ε-caprolactone after the reaction were 60.5% and 99.5%, respectively.

The infrared absorption spectrum of the obtained cyano group-containing ε-caprolactone oligomer acrylic ester mixture revealed cyano groups (2250 cm) and ether groups (1130 cm).
-1), ester group (1730 cm''1) and acryloyl group (1620 and 1640 cm-1) were confirmed.

The average molecular weight of the acrylic ester mixture calculated from the amount of double bonds was 414, and the content of (2-cyanoethoxy)ethyl acrylate was 12.5% by weight. The value of n in equation (n) calculated from these results is 2.5. Table 1 shows the contents of carbon, hydrogen, and nitrogen calculated from the elemental analysis results and the amount of double bonds. Both values were almost the same.

From the above results, it is clear that the desired cyano group-containing ε-caprolactone oligomer acrylic ester mixture was obtained.

A reaction was carried out in the same manner as in Synthesis Example, except that 395 parts of methacrylic acid was used instead of acrylic acid in the esterification reaction, to synthesize a cyano group-containing ε-caprolactone oligomer methacrylic ester mixture.

The infrared absorption of the obtained cyano group-containing ε-caprolactone oligomer methacrylic acid ester mixture is determined from the vector of cyano group (2250 cm), ether group (1130 cm-1), and x stellate group (1730 cm-1).
1), and the presence of a methacryloyl group (1640 cm-1) was confirmed.

The average molecular weight of the methacrylic acid ester mixture calculated from the amount of double bonds was 3 U2, and the content of (2-cyanoethoxy)ethyl methacrylate was 25% by weight. The value of n in equation (n) calculated from these results is 1.5. Table 1 shows the contents of carbon, hydrogen, and nitrogen calculated from the elemental analysis results and the amount of double bonds. Both values were almost the same.

From the above results, it is clear that the desired cyano group-containing methacrylic acid ester mixture was obtained.

Comparative Synthesis Example 355 parts of ethylene cyanohydrin, 114 parts of ε-caprolactone, and 0.075 parts of tetrabutoxytitanium were charged into a reactor, and a reaction was carried out at 150°C under a nitrogen atmosphere for about 5 hours. The conversion rates of ethylene cyanohydrin and ε-caprolactone after the reaction were 12.8% and 10096%, respectively. Further, unreacted ethylene cyanohydrin was removed from the reaction product by heating under reduced pressure to obtain a cyano group-containing ε-caprolactone oligomer. A cyano group-containing ε-caprolactone oligomer acrylic ester was obtained by carrying out the same reaction as in Synthesis Example 1, except that 855 parts of the cyano group-containing ε-caprolactone oligomer was used in the esterification reaction. The average molecular weight of the acrylic ester calculated from the amount of double bonds was 308.

Examples 1 to 4, Comparative Examples 1 to 4 Cyano group-containing ε-caprolactone oligomer (meth)acrylic acid ester mixture synthesized in Synthesis Examples 1 to 4 and acrylic cyano group-containing ε-caprolactone oligomer synthesized in Synthesis Comparative Example Copolymer rubber was produced using acid ester and its physical properties were evaluated. One-fifth of a mixture of 100 parts by weight of a monomer mixture having the composition shown in Table 2 and an appropriate amount of n-dodecyl mercaptan was mixed with 1 part by weight of polyethylene lauryl ether, 3 parts by weight of sodium lauryl sulfate, and 1 part by weight of polyethylene ethylene sorbitan tristearate. 1 part by weight, 0.15 parts by weight of the sodium salt of β-naphthalenesulfonic acid formalin condensate, 0.7 parts by weight of disodium hydrogen phosphate, 0.3 parts by weight of sodium dihydrogen phosphate, and 200 parts by weight of distilled water. One-half of the mixture was charged into a reactor, mixed and stirred to emulsify. This emulsion was maintained at 15°C, sodium ethylenediaminetetraacetate iron (If) 0.005 double double ethylenediaminetetraacetic acid tetrasodium 0.02 parts by weight, Rongalite 0.
．． 02 parts by weight and 0 sodium hydrosulfide
．． After adding 2 parts of tert-butyl hydroperoxide, a 0.2% by weight aqueous solution of tert-butyl hydroperoxide was added dropwise at a rate of 1.5 parts by weight per hour to initiate polymerization. Then increase the temperature to 15℃
While keeping the temperature at
It dripped in time. After the emulsifier was added dropwise, polymerization was continued for another 2 hours, and 2,2-methylenebis=(4-methyl-6
-tert-butylphenol) was added to complete the polymerization. The monomer conversion rate calculated from the solid content of the latex was 96 to 99%. The obtained copolymer latex was poured into an aqueous calcium chloride solution at 85° C. to isolate the copolymer, thoroughly washed with water, and then dried to obtain the desired copolymer rubber.

The obtained copolymer had a polymer composition shown in Table 3. Here, the polymer composition was calculated from the contents of nitrogen, chlorine, and carbon in the polymer by elemental analysis, and from the analysis results of unreacted monomers in the latex after polymerization by gas chromatography. Example 1 and Example 4 and Comparative Examples 1 to 4
The copolymer elastomer obtained was roll kneaded according to the formulation shown in Table 4, and press vulcanization was performed at 170° C. for 20 minutes to prepare a vulcanized rubber sheet. 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. The physical properties of the vulcanized rubber were evaluated by producing a vulcanized rubber sheet using the formulation and vulcanization conditions shown in Table 3.
Further, the copolymer elastomers obtained in Example 2 and Example 3 were roll-kneaded according to the formulations shown in Table 5, and
A vulcanized rubber sheet was created by performing 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.

These results show that by using the cyano group-containing (meth)acrylic acid ester of the present invention as a copolymer component, a rubber with an excellent balance of fuel oil resistance and cold resistance and good heat aging resistance can be obtained. It is obvious.

Table 4 Acrylic copolymer elastomer 100 Parts by weight Stearic acid 1 MAF carbon 50 Sodium stearate 3 Potassium stearate
0.5 sulfur
0.3 Table 5 Acrylic copolymer elastomer 100 Parts by weight Stearic acid 1 MAF carbon 50 Ammonium benzoate 1 [Effects of the invention From the above results, the present invention has improved fuel oil resistance and cold resistance with improved heat aging resistance. It is clear that an excellent acrylic copolymer elastomer is provided.

Claims (2)

[Claims] (1) (A) The following general formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ 2-(2-cyanoethoxy)ethyl (meth)acrylate represented by (I) and the following general formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II)
meth)acrylic acid ester mixture, 5 to 50% by weight (R is common in formulas (I) and (II) and represents hydrogen or a methyl group. In addition, n in formula (II) represents the amount of ε-caprolactone added. It represents the average value, and its value is 1
(B) Ethyl acrylate or ethyl acrylate containing up to 50% by weight of n-butyl acrylate, 94.5
~50% by weight and (C) at least one of allyl glycidyl ether and glycidyl methacrylate, or vinyl chloroacetate, having a composition of 0.5 to 10% by weight, and has a Mooney viscosity [ML_1_+_4 (100°C)] of 10 or more. An acrylic copolymer elastomer. (2) (Meth)acrylic acid 2-( in the component (A) mixture
The cyano group-containing acrylic copolymer elastomer according to claim 1, wherein the amount of 2-cyanoethoxy)ethyl is 70% by weight or less.