JPS62169811A - Production of nitrile rubber - Google Patents

Abstract

PURPOSE:To obtain a non-exudating nitrile rubber of excellent properties, by emulsion-polymerizing butadiene with acrylonitrile and a specified monomer by using a free radical catalyst. CONSTITUTION:Butadiene (A) is emulsion-polymerized with acrylonitrile (B) and a hydroxyalkyl (meth)acrylate and/or N-methylolacrylamide (C) by using a free radical catalyst. In this way, a rubber-like polymer having a Mooney viscosity of the formula and comprising 40-89wt% component (A), 10-50wt% component (B) and 0.5-20wt% component (C). Examples of component (C) with can be particularly desirably used include beta-hydroxypropyl (meth)acrylate and beta-hydroxyethyl (meth)acrylate.

Description

[Detailed description of the invention] a. Industrial application field The present invention relates to a method for producing modified nitrile rubber.

b. Prior Art Conventionally, butadiene-acrylonitrile copolymer rubber (abbreviated as NBR) has been known as an oil-resistant rubber.
It is used in applications that require oil resistance, such as backing, and as a raw material for adhesives.

Problems to be Solved by the C0 Invention Such NBR is usually used with a plasticizer added to it in order to improve processability during rubber compounding. But is this plasticizer NBI? If you soak it in oil, it will be extracted,
or deteriorate properties suitable for hoses, backings, etc.
Furthermore, the extracted plasticizer adheres to other parts of the device, causing problems such as clogging of filters and deterioration of device performance.

d8 Means for Solving Problems The present invention provides a method for producing nitrile rubber that is non-extractable and has excellent other physical properties in order to solve the above-mentioned problems of conventional 2I-IJ rubber. It is something to do.

That is, the present invention emulsion polymerizes (A) butadiene, (B) acrylonitrile, and (C) hydroxyalkyl (meth)acrylate and/or N-methylol-acrylamide using a free radical catalyst, thereby reducing the Mooney viscosity ML. , and 4. Io. ℃40~90
, (8) butadiene component 40-89% by weight, (B) acrylonitrile component 10-50% by weight, and (C) hydroxyalkyl (meth)acrylate component and/or N-methylol-acrylamide component 0.5-20% by weight. This is a method for producing nitrile rubber, which is characterized by producing a rubbery polymer.

e. Detailed Description of the Invention The monomer (
Examples of hydroxyalkyl (meth)acrylates in component C) include β-hydroxyethyl acrylate, β-hydroxypropyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl methacrylate, β-hydroxyisobutyl acrylate, and β-hydroxypropyl acrylate. -Hydroxy n-butyl acrylate, γ-hydroxy n-butyl acrylate, and the like. Examples of N-methylol-acrylamide include N-methylol-acrylamide and N-methylol-alkylacrylamide in which the alkyl group has 4 or less carbon atoms. Particularly preferred component (C) is β-hydroxypropyl (meth)acrylate or β-hydroxyethyl (meth)acrylate.

The solid nitrile rubber (P) produced by the method for producing nitrile rubber of the present invention can be produced by emulsion polymerization of (A) butadiene, (B) acrylonitrile, and the above-mentioned monomer (C) component. Polymers can be produced, and cannot be produced by solvent polymerization or other polymerization methods.

As polymerization initiators, customary free radical catalysts such as peroxides, redox systems, persulfates and azo systems are used.

Representative examples of molecular weight modifiers include sulfur compounds such as tertiary dodecyl mercaptan, normal dodecyl mercaptan and diisopropylxanthogen disulfite, and halogen compounds such as carbon tetrachloride and carbon tetrabromide.

Polymerization is usually carried out at 0-80°C in an oxygen-free reactor. If the polymerization temperature is less than 0°C, it is difficult to perform stable polymerization, and if it exceeds 80°C, it is difficult to control the polymerization rate, making it extremely difficult to produce nitrile rubber.

Monomers, emulsifiers, initiators, and other polymerization agents may be added in their entirety before the start of the reaction, or may be added in appropriate portions after the start of the reaction, and operating conditions such as temperature and stirring may be changed as appropriate during the reaction. You can also do that. The polymerization method may be continuous, semi-batch or batch.

The polymer composition of the terpolymer constituting the solid nitrile rubber (P) of the present invention is (A): (B): (in weight%).
C) = 40~89: 10~50: 0.5~
It is 20.

If component (A) is less than 40% (by weight, the same applies hereinafter), rubber elasticity is lost. Moreover, if it exceeds 89%, oil resistance will be lost.

If component (B) is less than 10%, oil resistance will be lost. Also 5
If it exceeds 0%, cold resistance will decrease.

When component (C) is less than 0.5%, adhesiveness decreases, and crosslinking becomes insufficient, resulting in a decrease in tensile strength. If it exceeds 20%, the elongation of the crosslinked product will decrease.

Mooney viscosity ML+ of the above terpolymer: 4411°.

C. is 40-90. When it is less than 40, the physical properties of the crosslinked product are generally poor. When it exceeds 90, workability deteriorates.

The solid nitrile rubber CP) obtained by the production method of the present invention is preferably used in combination with a liquid nitrile rubber (Q) of a liquid terpolymer produced by a method similar to the polymerization method described above. . The composition of the liquid terpolymer is 10-85% butadiene, 10-50% acrylonitrile, 5% hydroxyalkyl (meth)acrylate and/or N-methylol-acrylamide in weight percent.
It is preferable that it is 50. [η
) MEK, 30°C is 0.05-0.5.

If it is less than 0.05, non-extractability will not be improved. Moreover, if it exceeds 0.5, the plasticizing effect will be weak.

The blending ratio of liquid nitrile rubber (Q) is (P) + (Q
) is preferably 30% by weight or less.

In addition, solid nitrile rubber CP) and liquid nitrile rubber (Q)
may be mixed in a latinx state or as a rubber.

The solid nitrile rubber (P) or the mixture of solid nitrile rubber and liquid nitrile rubber (P+Q) is a vulcanizing agent, vulcanization accelerator, reinforcing agent, filler, plasticizer, softener, anti-aging agent, and stabilizer. A vulcanized product can be obtained by adding ordinary ingredients such as a blowing agent and heating the mixture to a temperature of up to 160° C. (or by leaving it at room temperature).

It goes without saying that the vulcanizing agent can be appropriately selected from common vulcanizing systems such as sulfur-based, thiuram-based, thiuram/a small amount of sulfur, and organic peroxides.

f. Examples Parts and percentages in the following examples are by weight, unless otherwise stated.

The test method was as follows.

Tensile test JIS K6301-3 hardness test
JIS K6301-5 Type A composition analysis Elemental analysis method (*) Isooctane extractability JIS K6301 (*) Ultraviolet absorption spectrum analysis was used to quantify the hydroxyl group concentration in the copolymer. That is, phenyl isocyanate was reacted with the hydroxyl groups in the polymer to introduce phenyl groups that can be measured in the ultraviolet region, and the absorbance was determined from the absorbance of the phenyl groups at 234 mμ.

In addition, the amount of bound acrylonitrile was determined by Coleman analysis.

Example 1 and Reference Example 1 The polymerization recipe for nitrile rubber is as follows. (Polymerization temperature 5°C) Water
100 parts Butadiene 54 Acrylonitrile 39 Potassium dodecylbenzenesulfonate 6 Ferrous sulfate
0. OO5〃Paramenthane hydroperoxide 0.02〃t-dodecyl mercaptan
0.40 Potassium phosphate 0.
3. After starting polymerization using the above recipe, when the conversion rate reaches 90%, add 0.5% of sodium dimethyldithiocarbamate.
The polymerization was stopped by adding 50% of the solution. After removing unreacted monomers by steam distillation, 1 part of 2,6-ditertiary-butyl cresol was added as a stabilizer, and 1 part of aluminum sulfate was added.
% aqueous solution to coagulate the polymer.

After solidification, the polymer was washed with water and dried at 100°C for 2 hours.

The polymer thus obtained was designated as Sample A, and the composition of this polymer was analyzed and found that butadiene
55% acrylonitrile
40% β-hydroxypropyl methacrylate 5%. Also, Mooney viscosity ML+. 4.1°8°C was 45.

The results are shown in Table-1.

Sample A produced by JIUK Kogyo's above-mentioned nitrile rubber production
Table 2 shows the physical property measurement results of a single blended vulcanizate and a blended vulcanizate obtained by blending Sample A with a hydroxyl group-containing plasticizer.

For comparison, the results of measuring the physical properties of a commercially available vulcanizate of NBR alone and a vulcanizate of a commercially available N[IR blended with a hydroxyl group-containing plasticizer are also listed in Table 2 as Reference Example 1.

From the results in Table 2, the nitrile rubber obtained by the method of the present invention shows almost no difference in physical properties compared to commercially available NBR (Reference Example-1) when blended alone, but when blended with a plasticizer converted, the nitrile rubber has plastic properties. It can be seen that the non-extractability of the agent is significantly improved.

In addition, the adhesive strength of the nitrile rubber produced in Example 1 was measured using commercially available NBR (N220
In order to test it in comparison with S), an adhesive formulation of the following formulation is rolled, cut into pieces and dissolved in methyl ethyl ketone to give a 30% strength solution.

The polymer solution is applied to a soft PVC sheet and an iron plate, and after application, it is left until it dries. After that, they are pasted together and pressed using a hand roller to prevent air bubbles from entering the adhesive layer. The film was left as it was in a room at 20°C and 65% humidity, and after 2 hours, it was peeled off at 200 mm/min in a direction of 180° using a shopper. Write the value on the autograph, and write 5 times per sample.
Take the average value of the samples.

Further, an adhesive force test was conducted in the same manner as in Example 1 using commercially available NBR (N220S). The results are listed in Table 3 together with Example 1.

Table 3 It can be seen that the adhesive containing the nitrile rubber of the present invention has significantly better adhesive strength than that of ordinary NBR.

Measurement of green strength The green strength of a blend of the nitrile rubber produced in the production of nitrile rubber in Example 1 and commercially available NBR (N22OS) was blended in the following formulation and compared. The results are shown in Table 4.

Table 4 It can be seen that the nitrile rubber formulation of the present invention has significantly better green strength than that of ordinary NBR.

Examples 2 to 50 Polymerization was carried out in the same manner as in Example 1 except that the types of monomers shown in Table 1 were changed. The results are summarized in Table 1 together with Example 1.

10 Effects of the Invention The nitrile rubber (P) produced by the method of the present invention has excellent adhesive properties compared to conventional nitrile rubber (for example, NBR), and also has excellent green strength of the rubber compound before vulcanization. There is. Furthermore, processability is improved by blending the liquid nitrile rubber (Q) with the solid nitrile rubber (P). By crosslinking (or vulcanizing) them, the non-extractability by oil can be further improved.

Patent applicant: Japan Synthetic Rubber Co., Ltd. (1 other person)

Claims (1)

[Claims] (A) butadiene, (B) acrylonitrile and (C
) Hydroxyalkyl (meth)acrylate and/or N-methylol-acrylamide are emulsion polymerized using a free radical catalyst to obtain Mooney viscosity ML_1_+_4_,_1_0_0_0℃40-90, (A
) Butadiene component 40 to 89% by weight, (B) acrylonitrile component 10 to 50% by weight, and (C) hydroxyalkyl (meth)acrylate component and/or N-methylol-acrylamide component 0.5 to 20% by weight. A method for producing nitrile rubber, the method comprising producing a polymer.