JPS6342642B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel modified liquid isoprene rubber. Maleic anhydride-modified liquid isoprene rubber obtained by reacting maleic anhydride with liquid isoprene rubber such as liquid polyisoprene rubber or liquid isoprene-butadiene copolymer rubber is characterized by the presence of acid anhydride groups. It has the effect of increasing the types of crosslinking agents that can be used because it enables crosslinking reactions using it, and increases adhesiveness with metals, fibers, etc., so it can be used as a sealing material, coating material, or It becomes a useful material as a component of adhesives and adhesives,
It can also be mixed with solid rubber to serve as a modifier for improving adhesive performance. However, despite the maleic anhydride-modified liquid isoprene rubber having the above-mentioned features, the crosslinking reaction using its acid anhydride group does not allow for a well-balanced reaction between curing speed and pot life. It is extremely difficult to do so. That is, for example, typical crosslinking agents include epoxy resins and polyvalent amines, but although the pot life is sufficient in crosslinking reactions using epoxy resins,
Curing takes a long time, and although the curing rate is fast enough in crosslinking reactions using polyvalent amines such as tetraethylenepentamine,
Because of the lack of pot life, it could hardly be put to practical use. Further, such maleic anhydride-modified liquid isoprene rubber has the disadvantage that it is extremely susceptible to scorch when vulcanization with sulfur or peroxide is performed by utilizing the double bonds present therein. Furthermore, when such maleic anhydride-modified liquid isoprene rubber is mixed with solid rubber for the purpose of improving adhesion, it slows down the vulcanization rate, and it also causes crosslinking reactions with compounded chemicals. wake up,
It also had the disadvantage of significantly reducing the processability of solid rubber compounds. The present inventors have conducted extensive studies on the points that should be improved in the maleic anhydride-modified liquid isoprene rubber mentioned above, and have found that the viscosity average molecular weight is
15,000 to 100,000, with a vinyl bond content of 25% or less and a ratio of (weight average molecular weight)/(number average molecular weight) of 4 or less, modified by adding N-hydroxyhydrocarbyl-maleimide. It was discovered that liquid isoprene rubber has a practical curing speed and pot life when a commonly used crosslinking agent such as an epoxy compound, a polyvalent amine, or an isocyanate compound is used, and the present invention has been completed. I reached it. Also, this N-
The modified liquid isoprene-based rubber to which hydroxyhydrocarbyl-maleimide has been added is obtained by adding maleic anhydride to the liquid isoprene-based rubber in an amount of 0.35% per 100 monomer units of the liquid isoprene-based rubber.
After adding ~10.5 mol, and then reacting the obtained product with an amino alcohol represented by the general formula H ₂ N—R—OH (wherein R represents an alkyl group, an aryl group, or an aralkyl group). , produced by dehydration. At this time, the temperature when reacting the amino alcohol is room temperature to 130°C,
The reaction efficiency is highest when the temperature during dehydration is 150 to 220°C. The liquid isoprene rubber used in the present invention means a homopolymer of isoprene or a copolymer of isoprene and butadiene. The above-mentioned copolymer may be a random copolymer or a block copolymer, and the type of bonding thereof is not limited, but it is necessary that the composition of isoprene be at least 20% by weight. If the composition of isoprene is less than 20% by weight, i.e. the composition of butadiene is
If it is 80% by weight or more, gelation tends to occur in the reaction with maleic anhydride, which is not preferable. This liquid isoprene rubber has a molecular weight of 15,000
~100000 is preferably used. molecular weight
If it is smaller than 15,000, when a crosslinking agent is added to the modified liquid isoprene rubber obtained by the present invention to form a crosslinked product, the physical properties of the crosslinked product will no longer be practical. When mixed, the physical properties of the solid rubber may be significantly deteriorated, which is undesirable. On the other hand, if the molecular weight exceeds 100,000, the viscosity will become too high when maleic anhydride or amino alcohol is reacted, and the final modified liquid isoprene rubber will have poor fluidity and poor processability. From this point of view, the molecular weight is preferably in the range of 20,000 to 75,000. Note that molecular weight here means viscosity average molecular weight (M _V ), and according to the intrinsic viscosity ([η]) measured in toluene at 30°C, [η] = 1.21 ×
10 ^-4 M _V ^0.77 . Further, this liquid isoprene rubber having a vinyl bond content of 25% or less is preferably used. If the amount of vinyl bonds exceeds 25%, gelation tends to occur during the reaction with maleic anhydride, and the final crosslinked modified liquid isoprene rubber will have poor rubber elasticity, which is not preferred. Especially in the case of isoprene homopolymer, cis-
Those having a 1,4 bond amount of 75% or more are preferably used. Note that such a microstructure is evaluated by infrared absorption spectroscopy. Furthermore, this liquid isoprene rubber has the following formula: (weight average molecular weight)/(number average molecular weight) (hereinafter,
It is preferable that the value (abbreviated as M _W /M _N ) is 4 or less. If it is larger than 4, it becomes difficult to obtain a modified liquid isoprene rubber with sufficiently satisfactory heat resistance. Note that this M _W /M _N is evaluated by gel permeation chromatography. This liquid isoprene-based rubber is produced by various known methods, but the above-mentioned specific liquid isoprene-based rubber that is particularly preferably used in the present invention is produced by an anionic polymerization method, particularly a living polymerization method using a lithium catalyst. It is manufactured by In this case, the molecular weight can be easily controlled, the amount of vinyl bonds is small, and a product with a small M _W /M _N can be easily obtained. Any known method can be adopted for the reaction between liquid isoprene rubber and maleic anhydride, that is, the maleic anhydride reaction. For example, by heating and stirring the liquid isoprene rubber and maleic anhydride. A method in which the reaction is carried out is preferably employed. For this reaction, it is also possible to use a catalyst such as a peroxide or an azo compound, and it is also possible to use an inert hydrocarbon solvent such as hexane, toluene or benzene. It is also possible to carry out the reaction in the presence of an antigelation agent such as acetylacetone or acetylacetone. The reaction temperature is preferably 100-250℃, and the reaction time is 1-250℃.
20 hours is recommended. The amount of maleic anhydride added is
0.35 per 100 isoprene (or isoprene and butadiene) monomer units of liquid isoprene rubber
~10.5 mol is required. If the amount added is less than 0.35 mol, no improvement effect will be seen in the final modified liquid isoprene rubber, and if it exceeds 10.5 mol, the reaction product, that is, the maleic anhydride modified liquid isoprene rubber, will have a viscosity This is undesirable as it becomes too high and resin-like. The maleic anhydride-modified liquid isoprene rubber thus obtained is subjected to a reaction with an amino alcohol, that is, an amidation reaction and a subsequent dehydration reaction leading to imidization. The amino alcohol used here has the general formula H ₂ N—R—OH
(wherein R represents an alkyl group, aryl group or ararykyl group having 1 to 20 carbon atoms),
Typical examples include ethanolamine, 1-aminopropan-2-ol, and 2-aminopropane-
1-ol, 1-aminobutan-2-ol, 2
-Aminoalkyl alcohols such as aminobutan-1-ol, 3-aminobutan-1-ol, 1-amino-2-methylpropan-2-ol, 1-aminopentan-4-ol or 1-aminopentan-5-ol Alternatively, aminoaralkyl alcohols such as aminophenol, aminocresol, aminoxylenol or aminonaphthol can be mentioned. Among them, aminoalkyl alcohols are preferably used. In carrying out this reaction, it is necessary to pay sufficient attention to the reaction temperature. In other words, the acid anhydride group in the maleic anhydride-modified liquid isoprene rubber easily reacts with the amino alcohol to produce a semi-amidated product;
If the reaction temperature is too high at this time, gelation reactions and other undesirable side reactions occur. Therefore, it is necessary to carry out the reaction at a low temperature, specifically from room temperature to 130°C, particularly preferably from 50 to 100°C, until the addition of the amino alcohol to the amide is completed. on the other hand,
The dehydration reaction of imidization subsequent to amidation needs to be carried out at a higher temperature than the amidation reaction. At this time, if the temperature is too low, imidization will not occur, and carboxyl groups will remain in the modified liquid isoprene rubber finally obtained in the present invention, often resulting in unfavorable reaction with the crosslinking agent. Become. From this point of view, this dehydration reaction is 150 ~
It must be carried out at 220°C, preferably 150-180°C. During this dehydration reaction, a dehydrating agent such as sulfuric acid, phosphoric acid, or phosphorus pentoxide may be used to accelerate the reaction, or a means of distilling off the water produced under reduced pressure may be used. good. The amount of aminoethanol used is in most cases about the same number of moles to three times the number of moles of maleic anhydride added in the maleic anhydride-modified liquid isoprene rubber. The modified liquid isoprene rubber produced by the production method of the present invention is a modified liquid isoprene rubber to which N-hydroxyhydrocarbyl-maleimide is added, and has an N-substituted maleimide group and further a hydroxyl group. have Due to its polarity, the maleimide group gives the modified liquid isoprene rubber excellent adhesion to metals, fibers, glass or concrete. Furthermore, since the hydroxyl group reacts with diisocyanate compounds, epoxy resins, etc., it is very useful for easily providing cured products. Furthermore, this modified liquid isoprene rubber has a double bond in its molecular chain, and can also be subjected to vulcanization with sulfur, peroxide, or the like. Due to these properties, the modified liquid isoprene rubber produced by the production method of the present invention can be used as a sealing material for buildings and automobiles, adhesives, adhesives for adhesive tapes, or reaction raw materials such as cyclized rubber. Furthermore, it is preferably applied to mixing into solid rubber to improve adhesive performance, modifying urethane polymers, asphalt, etc., and modifying epoxy resins and ethylene-vinyl acetate bonds. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 A liquid polyisoprene rubber with a molecular weight of 29,000, a vinyl bond content of 6% (a cis-1,4 bond content of 82%), and a M _W /M _N of 2.0 (Kuraprene LIR manufactured by Kuraray Isoprene Chemical Co., Ltd.) -30) Place 100 parts by weight in an autoclave, add 0.3 parts by weight of acetylacetone, and after purging with nitrogen, heat while stirring until the internal temperature reaches
When the temperature reached 100°C, 3.5 parts by weight of maleic anhydride was added, further heated, and reacted at 200°C for 5 hours (maleation reaction). When a very small portion of it was taken out and subjected to infrared absorption spectrum analysis, the results shown in FIG. 1 were obtained. 1860cm ^-1 and
The absorption around 1780 cm ^-1 corresponds to the carboxyl group of maleic anhydride. The amount of maleic anhydride added by the neutralization method was 2.45 mol per 100 isoprene monomer units of the liquid polyisoprene rubber. The maleation reaction system was cooled to 80°C, and 1
3 parts by weight of -aminopropan-2-ol was added, and stirring was continued for 2 hours at this temperature to carry out a semi-amidation reaction. Subsequently, the temperature was raised again, and a dehydration reaction was performed at 160°C to form an imide ring.
The water produced at this time was distilled out of the system by a reduced pressure operation. The amount of water recovered was 0.62 parts by weight;
It was about 96% of the theoretical value. When the thus obtained modified liquid polyisoprene rubber (A) to which N-(2-hydroxy)propyl maleimide was added was subjected to infrared absorption spectrum analysis, the results shown in Figure 2 were obtained. . As can be seen from Figures 1 and 2,
1860 cm -1 and 1780 cm ^-1 based on the carboxyl group of maleic anhydride found in maleic anhydride modified liquid polyisoprene rubber (B) through imidization reaction
The absorption near cm ^-1 disappears, and new absorption by hydroxyl groups appears near 3400 cm ^-1 and around 1700 cm ^-1 and
Absorption by the carbonyl group of the maleimide ring appears around 1700 cm ^-1 , indicating almost complete imidization. To 100 parts by weight of each of the thus obtained modified polyisoprene rubber (A) and the maleic anhydride-modified liquid polyisoprene rubber (B), 3 parts by weight of an epoxy resin (Epicoat 828 manufactured by Ciel) and tetraethylene pentamine. A composition is prepared by adding 1 part by weight of each, and the pot life characteristics of the composition are determined by the coatability of the composition 15 minutes after production and the cohesive force when the composition is heat-treated at 100°C for 3 minutes. When the curing rate characteristics were qualitatively investigated, the results shown in Table 1 were obtained.

[Table] Example 2 A liquid isoprene-butadiene block copolymer was used as the liquid isoprene rubber. This liquid block copolymer is produced by using sec-butyllithium as a catalyst and adding each monomer of butadiene and isoprene in the order of butadiene-isoprene-butadiene-isoprene-butadiene and weighing them sequentially. , the composition of isoprene is 40%, the molecular weight is 21000, and the amount of vinyl bond is 9.8%.
and M _W /M _N was 3.1. 5 parts by weight of maleic anhydride was added to 100 parts by weight of this liquid block copolymer, and a maleation reaction was carried out in the same manner as in Example 1. 100 after reaction
℃, diluted by adding 30 parts by weight of toluene, added 5 parts by weight of 3-aminobutan-1-ol, continued stirring for 2 hours, and then raised the temperature to 160℃ again to carry out the dehydration reaction. I spent time. The water produced at this time was distilled off together with toluene, and after the toluene was distilled off, residual water was further distilled off by a reduced pressure operation. The amount of water recovered was 0.9 parts by weight;
It was about 90% of the theoretical value. Further, when the product was subjected to infrared absorption spectrum analysis, it was found that, as in Example 1, it was almost completely imidized. This modified liquid isoprene-butadiene block copolymer was subjected to a crosslinking reaction in the same manner as in Example 1.
When the curing speed, pot life and scorch properties were examined, they were found to be as excellent as the modified liquid polyisoprene rubber of Example 1. _{Example 3} Liquid polyisoprene rubber (clareisoprene chemical
A maleation reaction was carried out in the same manner as in Example 1, except that 2 parts by weight of maleic anhydride was used per 100 parts by weight (Kurapren LIR-50). The amount of maleic anhydride added was 1.4 moles per 100 isoprene monomer units. Subsequently, the mixture was cooled to 50°C, and 50 parts by weight of toluene was added for dilution. In this system, 1-
Adding 2.5 parts by weight of aminopentan-4-ol,
Stirred for 2 hours. Thereafter, the temperature was raised to 160°C, and heating was continued for 2 hours while toluene was distilled out little by little. When the obtained product was subjected to infrared absorption spectrum analysis, it was found that a modified liquid polyisoprene rubber that was almost completely imidized was obtained. This modified liquid polyisoprene rubber was prepared in Example 1.
Similar to the modified liquid polyisoprene rubber, it had excellent crosslinking properties. Comparative Example 1 The maleic anhydride-modified liquid polyisoprene rubber obtained in Example 1 was reacted with ethanolamine and subjected to an imidization reaction. When imidizing
When 3 parts by weight of ethanolamine was added to 100 parts by weight of maleic anhydride-modified liquid polyisoprene rubber maintained at 180°C, the system immediately gelled and became unstirable, making it impossible to continue the reaction.

[Brief explanation of the drawing]

Figure 1 shows an infrared absorption spectrum diagram of maleic anhydride-modified polyisoprene rubber (B) prepared in Example 1 to produce a modified liquid polyisoprene rubber to which N-(2-hydroxy)propyl-maleimide was added. Figure 2 shows Example 1.
FIG. 2 shows an infrared absorption spectrum diagram of the modified liquid polyisoprene rubber (A) to which N-(2-hydroxy)propyl maleimide was added obtained in .

Claims (1)

[Scope of Claims] 1. A viscosity average molecular weight of 15,000 to 100,000, a vinyl bond content of 25% or less, and (weight average molecular weight)/
0.35 to 10.5 mol of maleic anhydride per 100 monomer units of the liquid isoprene rubber is added to a liquid isoprene rubber having a ratio of (number average molecular weight) of 4 or less, and then the obtained product has the general formula
N-hydroxyhydrocarbyl, which is characterized by reacting an amino alcohol represented by H ₂ N—R—OH (in the formula, R represents an alkyl group, an aryl group, or an aralkyl group) and then dehydrating it.
A method for producing modified liquid isoprene rubber to which maleimide is added. 2. The manufacturing method according to claim 1, wherein the liquid isoprene rubber is liquid polyisoprene. 3. The manufacturing method according to claim 1, wherein the liquid isoprene rubber is an isoprene-butadiene copolymer containing 20% by weight or more of isoprene. 4 The temperature at which the amino alcohol is reacted is
130℃ or less and the temperature during dehydration is 150-220℃
The manufacturing method according to claim 1, wherein the temperature is .degree.