JPS6259138B2 - - Google Patents

Description

[Detailed description of the invention]

a. Field of Industrial Application The present invention relates to a modified nitrile rubber composition, and particularly to a modified nitrile rubber composition containing a modified nitrile rubber modified with hydroxyalkyl (meth)acrylate. b. Conventional technology Conventionally, butadiene-acrylonitrile copolymer rubber (abbreviated as NBR) has been known as an oil-resistant rubber, and NBR is used in applications that require oil resistance such as hoses and packing, and as a raw material for adhesives. There is. c Problems to be Solved by the Invention Such NBR is usually used with a plasticizer added to it to improve processability during rubber compounding. However, this plasticizer is extracted when NBR is immersed in oil, which deteriorates its properties suitable for hoses, packing, etc. Also, the extracted plasticizer adheres to equipment parts, clogging filters, etc. This has become a problem because it causes deterioration of equipment performance. Therefore, it is non-extractable to plasticizers,
Furthermore, there was a strong demand for the development of nitrile rubber with excellent other physical properties. d Means for Solving the Problems In order to meet these demands, the present invention has made an improvement by using hydroxyalkyl (meth)acrylate as a component of the third monomer, as a result of intensive research on nitrile rubber. The object of the present invention is to provide a rubber composition containing a solid modified nitrile rubber based on nitrile rubber. That is, in the present invention, the monomer components are 40 to 89% by weight of butadiene component, 10 to 50% by weight of acrylonitrile component, and 0.5% by weight of hydroxyalkyl (meth)acrylate component.
~20% by weight, and Mooney viscosity
ML ₁₊₄ , modified nitrile rubber with a temperature of 40 to 90 at 100℃,
The present invention relates to a modified nitrile rubber composition containing a vulcanizing agent and/or a crosslinking agent. e Specific description of the invention Since the modified nitrile rubber constituting the modified nitrile rubber composition of the present invention contains a hydroxyl group,
It is possible to crosslink with a compound having at least two isocyanate groups, and when this is used in combination with sulfur vulcanization, these characteristics can be further exhibited. Examples of the hydroxyalkyl (meth)acrylate as component (C) contained in the modified nitrile rubber in the present invention include β-hydroxyethyl acrylate, β-hydroxypropyl acrylate,
β-hydroxyethyl methacrylate, β-hydroxypropyl methacrylate, β-hydroxyisobutyl acrylate, β-hydroxy n
-Butyl acrylate, γ-hydroxy n-butyl acrylate, etc. Particularly preferred as component (C) are β-hydroxypropyl (meth)acrylate or β-hydroxyethyl (meth)acrylate. The terpolymer constituting the modified nitrile rubber (P) in the present invention can be produced by emulsion polymerization of (A) butadiene, (B) acrylonitrile, and the above-mentioned (C) hydroxyalkyl (meth)acrylate. Can be done. As polymerization initiators used in emulsion polymerization, conventional free radical catalysts such as peroxides, redoxes, persulfates and azos can be used. Representative examples of molecular weight modifiers include sulfur compounds such as tertiary dodecyl mercaptan and 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. 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.
Further, operating conditions such as temperature and stirring can be changed as appropriate during the reaction. The polymerization method may be continuous, semi-batch, or batch. The polymer composition of the terpolymer constituting the modified nitrile rubber (P) of the present invention is (A):(B):(C)=
40-89: 10-50: 0.5-20. If the content of component (A) is less than 40% (by weight, the same applies hereinafter), rubber elasticity will be lost. Moreover, if it exceeds 89%, oil resistance will be lost. If the (B) component is less than 10%, oil resistance will be lost. Moreover, when it exceeds 50%, cold resistance decreases. When the content of component (C) is less than 0.5%, adhesiveness decreases, and crosslinking becomes insufficient, resulting in a decrease in tensile strength. Moreover, when it exceeds 20%, the elongation of the crosslinked product decreases. Mooney viscosity ML of the above terpolymer ₁₊₄ , 100
°C is 40-90. When the Mooney viscosity is less than 40, the physical properties of the vulcanized product or crosslinked product are generally poor. Furthermore, if the Mooney viscosity exceeds 90, processability will deteriorate. Solid modified nitrile rubber (P) in the present invention
Liquid nitrile rubber can be blended with the material for the purpose of improving processability. Such liquid nitrile rubber (Q) has an intrinsic viscosity [η] MEK of 30°C.
It is preferred to use a terpolymer of (A) butadiene, (B) acrylonitrile and (C) hydroxyalkyl (meth)acrylate in an amount of 0.05 to 0.5. The terpolymer can also be produced by the polymerization method described above. The composition of this liquid terpolymer is preferably 10 to 80% butadiene, 10 to 50% acrylonitrile, and 5 to 50% hydroxyalkyl (meth)acrylate in weight percent. Outside this range, the effects of the present invention may not be sufficiently obtained. Intrinsic viscosity of liquid terpolymer [η]
MEK30℃ is 0.05~0.5, it is 0.05
If it is less than that, it is difficult to improve the non-extractability to plasticizers. Moreover, if it exceeds 0.5, the plasticizing effect will be weak. The composition ratio of (P)/(Q) is from 95/5 to 95/5 in weight%.
It is desirable to use a range of 70/30. The solid modified nitrile rubber (P) and the liquid nitrile rubber (Q) may be mixed in a latex state or as a rubber. The above (P) or (P+Q) is formulated with common ingredients such as vulcanizing agents, vulcanization accelerators, reinforcing agents, fillers, plasticizers, softeners, anti-aging agents, stabilizers and blowing agents. A vulcanizate can be obtained by heating to temperatures up to °C (or by leaving it at room temperature). The vulcanizate can be selected as appropriate from general vulcanization systems such as sulfur-based, thiuram-based, thiuram/small amount of sulfur, and organic peroxide, and the blending amount can also be selected as appropriate in general NBR formulations depending on the application etc. . The solid modified nitrile rubber (P) or the mixture of solid modified nitrile rubber and liquid nitrile rubber (P+Q) of the present invention can be further subjected to isocyanate crosslinking. The crosslinking agent used for the crosslinking is a compound having at least two isocyanate groups, and the amount used depends on the type of the crosslinking agent and the reaction conditions with the hydroxyalkyl (meth)acrylate contained in the terpolymer. Different, but 0.5 per 100 parts by weight of (P) or (P+Q)
~20 parts by weight, preferably 5 to 15 parts by weight. If the amount of isocyanate is less than 0.5 parts by weight, the crosslinking rate will be too low. Moreover, if the amount exceeds 20 parts by weight, the crosslinking speed becomes too high and premature crosslinking tends to occur, and the physical properties generally deteriorate. Further, examples of compounds having at least two isocyanate groups used for isocyanate crosslinking include 2,4-tolylene diisocyanate, 2,6
-tolylene diisocyanate, isomer mixture consisting of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate (hereinafter abbreviated as "tolylene diisocyanate"), 4,4-diphenylmethane Diisocyanate, isoppyrrolidenbis(4-cyclohexyl isocyanate) hexamethylene diisocyanate, methylcyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl diisocyanate, 2,4,6-trimethyl-1,3-phenylene diisocyanate ,1,
2-ethane diisocyanate, 1,3-propane diisocyanate, 1,4-butane diisocyanate, 1,5-propane diisocyanate, 1,
6-hexane diisocyanate, 1,4-cyclohexane diisocyanate, 2,4-bis(4-
Examples include one type or a mixture of two or more types of isocyanate such as cyclohexyl isocyanate (cyclohexyl methyl) cyclohexyl isocyanate. These isocyanate compounds may be used as they are, or may be used after being dissolved in a solvent that is inert to these isocyanate compounds. Such solvents include those that do not easily dissolve the polymer, such as acetone, methyl ethyl ketone,
Ethyl acetate, methyl acetate, etc. can be used. Crosslinking using isocyanate compounds can be very effective even at relatively low temperatures. The crosslinking temperature is usually -50 to 200°C, preferably 0 to 200°C.
The temperature is 120°C, and the crosslinking time varies depending on the type of isocyanate compound, crosslinking temperature, etc., but can vary from several seconds to about one month or more.
When crosslinking is carried out at a high temperature, it can be instantaneously crosslinked, and in the case of in-die extraction, crosslinking can be effected simply by the heat of the in-die extension treatment without any particular heating. For the above-mentioned isocyanate crosslinking, it may be combined with a vulcanization system such as a usual sulfur vulcanization accelerating compound or a 2-mercaptoimidazoline-lead compound. Further, crosslinking may be carried out in the presence of a filler such as carbon black, which is used for the purpose of reinforcing or increasing the weight of the polymer. f Examples "Parts" and "%" in the following examples are by weight unless otherwise specified. 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. In other words, phenyl isocyanate is reacted with the hydroxyl groups in the polymer to introduce phenyl groups that can be measured in the ultraviolet region.
It was determined from the absorbance of phenyl group at 234 mμ. In addition, the amount of bound acrylonitrile was determined by Coleman analysis. Example 1 Production of modified nitrile rubber The polymerization recipe is as follows. (Polymerization temperature 5
℃） Water 100 parts Butadiene 54〃 Acrylonitrile 39〃 β-Hydroxypropyl methacrylate 7〃 Potassium dodecylbenzenesulfonate 6〃 Ferrous sulfate 0.005〃 Para-menthane hydroperoxide 0.02〃 t-Dodecyl mercaptan 0.40〃 Potassium phosphate 0.3〃 Above After starting polymerization using the recipe, when the conversion rate reaches 90%, add sodium dimethylthiocarbamate.
Polymerization was stopped by adding 0.5 part. After removing unreacted monomers by steam distillation, 1 part of 2,6-di-tert-butylcresol was added as a stabilizer, and the latex was poured into a 1% aqueous solution of aluminum sulfate to coagulate the polymer. After solidification, the polymer was washed with water and dried at 100°C for 2 hours. The thus obtained polymer was designated as Sample A, and the composition of this polymer was analyzed and found to be 55% butadiene, 40% acrylonitrile, and 5% β-hydroxypropyl methacrylate. Also, Mooney viscosity ML ₁₊₄ , 100℃ is 45
It was hot. The results are shown in Table-1.

【table】

[Table] Vulcanized physical property test A blended vulcanizate of sample A alone produced by the production of the modified nitrile rubber described above, and a blended vulcanizate made by blending sample A and sample B described below with a hydroxyl group-containing plasticizer. The measurement results of physical properties are shown in Table 2 as Test Examples 1 to 3. For comparison, the measurement results of the physical properties of a commercially available NBR single blend and a blended vulcanizate obtained by blending a hydroxyl group-containing plasticizer with commercially available NBR are also listed in Table 2 as Reference Examples 1 and 2. From the results shown in Table 2, the modified nitrile rubber compound of the present invention has almost no difference in physical properties compared to commercially available NBR compounds when blended alone, but when blended with a plasticizer, the plasticizer is not extracted. It can be seen that the properties have been significantly improved.

【table】

【table】

[Table] Adhesive strength test Furthermore, the adhesive strength of the rubber composition blended with the modified nitrile rubber (sample A) produced by the production of the modified nitrile rubber in Example 1 was compared to the commercially available
To test in comparison with NBR (N220S), an adhesive formulation with the following formulation was kneaded in a roll, cut into pieces, and dissolved in methyl ethyl ketone to make a 30% solution. The polymer solution is applied to a flexible polyvinyl chloride sheet and an iron plate, and left until almost dry after application. After that, they are pasted together and pressed using a hand roller to prevent air bubbles from entering the adhesive layer. Leave it at 20℃, 65
% humidity in a room, and after 2 hours, peel it off with a shovel in a direction of 180°C at a rate of 200mm/min. Write the values on an autograph, and take the average value of 5 samples for each sample. In addition, an adhesion test was conducted in the same manner as in Example 1 using commercially available NBR (N220S; the same as in Reference Example 1 in Table 2). The results are listed in Table 3 along with Example 1.

【table】

[Table] It can be seen that the adhesive containing the modified nitrile rubber composition 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 modified nitrile rubber (sample A) produced in the production of modified nitrile rubber in Example 1 and commercially available NBR (N220S) was blended in the following formulation. I compared it. The results are shown in Table 4.

[Table] It can be seen that the blend of the modified nitrile rubber composition of the present invention has significantly better green strength than that of ordinary NBR. (Examples 2 to 4) Polymerization was carried out in the same manner as in Example 1 except that the types of monomers shown in Table 1 were changed to obtain modified nitrile rubbers according to the present invention. The results are summarized in Table 1 together with Example 1. Example 5 Production of solid modified nitrile rubber The butadiene-acrylonitrile-hydroxyalkyl (meth)acrylate copolymerization recipe and polymerization conditions were as follows. Water 180 parts Butadiene 60 parts Acrylonitrile 35 parts 2-hydroxypropyl methacrylate 5 parts Potassium dodensylbenzenesulfonate 6 parts Potassium phosphate 0.3 parts Ferrous sulfate 0.007 parts Para-menthane hydroperoxide 0.03 parts T-dodecyl mercaptan 0.4 parts Polymerization Temperature: 5°C, conversion rate: 90% When a predetermined conversion rate was reached, 0.5 part of sodium dimethyldiocarbamate was added as a polymerization terminator to terminate the polymerization. Next, 1 part of 2,6-di-t-butylcresol was added as an anti-aging agent,
Unreacted monomers were recovered by steam distillation, and calcium chloride was added to precipitate the polymer. The precipitated polymer was washed with water and dried at 100°C for 1.5 hours. Table 5 shows the Mooney viscosity of the copolymer and the polymer composition ratio of the copolymer.

【table】

[Table] Production of liquid nitrile rubber Polymerization was carried out using the following copolymerization recipe under the same polymerization conditions as the solid modified nitrile rubber. Water 180 parts Butadiene 55 parts Acrylonitrile 35 parts 2-Hydroxypropyl methacrylate 10 parts Hydrogenated fatty acid potassium 6 parts Potassium phosphate 0.3 parts Ferrous sulfate 0.007 parts Para-menthane hydroperoxide 0.03 parts T-dodecyl mercaptan 9 parts Polymerization temperature 5 C. Addition rate: 90% When a predetermined conversion rate was reached, 0.5 part of N,N-diethylhydroxylamine was added as a polymerization terminator to terminate the polymerization. Next, 1 part of 2,6-di-t-butylcresol was added as an anti-aging agent,
Unreacted monomers were recovered by steam distillation, and calcium chloride was added to precipitate a polymer. The precipitated polymer was washed with water and dried under reduced pressure at 80°C for 2 hours to dehydrate it. Table 6 shows the viscosity and polymer composition ratio of the copolymer.

[Table] Isocyanate crosslinking 80 parts of the solid modified nitrile rubber produced in the production of modified nitrile rubber in Example 5 and 20 parts of the liquid nitrile rubber for a total of 100 parts, 50 parts of carbon black, 2,4- Tolylene diisocyanate
After adding and kneading 14 parts of ethylene glycol, 1.86 parts of ethylene glycol, and 0.14 parts of dibutyltin dilaurate, hot pressing was performed at 130°C for 40 minutes. Table 7 shows the formulation and physical properties of the obtained vulcanized rubber.

[Table] Example 6 Polymerization was carried out in the same manner as in Example 5, except that the types of monomers shown in Table 5 were changed, to obtain a modified nitrile rubber according to the present invention. The results are shown in Table 5 together with Example 5. In addition, liquid nitrile rubber was produced by polymerization in the same manner as in Example 5, except that the types of monomers shown in Table 6 were changed. Using 80 parts of these modified nitrile rubber and 20 parts of liquid nitrile rubber, isocyanate crosslinking was carried out in the same manner as in Example 5 using the formulation shown in Table 7, and the physical properties of the vulcanized rubber were determined. The results are also listed in Table 7. Comparative Example 1 An acrylonitrile-butadiene copolymer was obtained in the same manner as in Example 5, except that butadiene and acrylonitrile having the composition shown in Table 5 were used as monomers, and the hydroxyalkyl (meth)acrylate component was not used. Using this copolymer, a compound was prepared by vulcanizing and compounding the commonly used nitrile rubber shown below, and press vulcanization was performed at 160° C. and 150 kg/cm ² . A tensile test was conducted on the vulcanized rubber, and the physical properties were compared with those of Examples, and the results are also listed in Table 7. Copolymer 100 parts Carbon black 50 Stearic acid 1 Dioctyl phthalate 15 Sulfur 2 ZnO 5 N-cyclohexylbenzothiazole sulfenamide 1.5 g Effects of the invention The solid modified nitrile rubber in the present invention is a conventional nitrile rubber (for example, NBR). It has superior adhesive properties compared to vulcanized rubber compounds, and the green strength of the rubber compound before vulcanization. Furthermore, processability is improved by blending liquid nitrile rubber with the solid modified nitrile rubber. By crosslinking or vulcanizing them, the non-extractability of plasticizers by oil can be further improved.

Claims (1)

[Claims] 1 The monomer components are (A) butadiene component 40 to 89% by weight, (B) acrylonitrile component 10 to 50% by weight, and
(C)Hydroxyalkyl (meth)acrylate component
Consisting of 0.5 to 20% by weight, and Mooney viscosity
ML ₁₊₄ , modified nitrile rubber with a temperature of 40 to 90 at 100℃,
A modified nitrile rubber composition comprising a vulcanizing agent and/or a crosslinking agent.