JPH0578563B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing epoxidized polymers. More specifically, the present invention relates to a method for producing an epoxidized polymer by reacting a hydrogenated polyisoprene with an epoxidizing agent.

Conventional technology Conventionally, some of the carbon-carbon double bonds in polyisoprene are converted to epoxy groups using an epoxidizing agent, and the resulting epoxidized polymer is heated using a heterogeneous compound such as Raney nickel or carbon-supported platinum catalyst. system catalyst,
Alternatively, hydrogenation using a homogeneous catalyst such as a Ziegler catalyst is known, for example, from JP-A-56-127641.

Problems to be Solved by the Invention However, when a hydrogenation reaction is performed after epoxidation as described above, when a heterogeneous catalyst is used as a catalyst in the hydrogenation reaction, the epoxidized polymer is adsorbed on the catalyst surface, and the hydrogen The reaction rate of addition is extremely slow and it is extremely difficult to remove the catalyst from the reaction solution. In addition, when a homogeneous catalyst is used, the epoxy groups in the epoxidized polymer react with each other during the hydrogenation reaction, resulting in a significant increase in the viscosity of the reaction system or, in severe cases, gelation, resulting in the hydrogenation reaction. does not proceed.

An object of the present invention is to provide a method for producing an epoxidized polymer from polyisoprene in high yield without involving side reactions such as gelation.

Another object of the present invention is to provide a method for producing an epoxidized polymer that has excellent weather resistance and heat resistance without impairing the inherent properties of the epoxidized polymer.

Means for Solving the Problems According to the present invention, the above object is to produce an epoxidized polymer by reacting polyisoprene with an epoxidizing agent. This is achieved by using isoprene hydrogenate.

The hydrogenated polyisoprene used in the production method of the present invention can be obtained by hydrogenating polyisoprene by a conventional method.

The above polyisoprene before hydrogenation (hereinafter sometimes referred to as unmodified polyisoprene)
Desirably has a molecular weight within the range of 5,000 to 150,000. If the molecular weight is too small, the final epoxidized polymer will not have sufficient strength when used as an adhesive or coating material. On the other hand, if the molecular weight is too large, the viscosity of the reaction system during the hydrogenation reaction and epoxidation reaction will become too large, making it difficult for the reaction to proceed, and the viscosity of the epoxidized polymer ultimately obtained will become too high. This may cause inconvenience when handling or using it. In addition, the molecular weight here means the viscosity average molecular weight (v), and the intrinsic viscosity ([η]) at 30°C in a toluene solution is measured, and the formula [η] = 1.21 ×
10 ^-4 v ^0.77
(See Publication No. 102938).

Further, it is desirable that the unmodified polyisoprene has a vinyl bond content of 50% or less. If the vinyl bond content exceeds 50%, it becomes impossible to produce a flexible molded article using the epoxidized polymer finally obtained, which is not preferable.

Such unmodified polyisoprene can be obtained by polymerizing isoprene monomers or by decomposing high molecular weight polyisoprene. Among these methods, anionic polymerization using an anionic polymerization initiator, especially living polymerization using a lithium polymerization initiator, is the most preferred because the molecular weight can be easily adjusted, and the vinyl bond content of the polyisoprene obtained falls within the above-mentioned desirable range. Preferably adopted.

The gist of the present invention is to hydrogenate the double bonds of the polyisoprene and then subject it to an epoxidation reaction.

Hydrogenation of polyisoprene includes a method in which molecular hydrogen is brought into contact with polyisoprene in the presence of an insoluble solvent using a heterogeneous catalyst made of a metal such as nickel, platinum, or palladium or a homogeneous Ziegler catalyst. The reaction temperature at that time is 0~
The temperature is 300℃ and the pressure of hydrogen is 1 to 500 atm. The reaction time for hydrogenation reaction under these conditions is
It is 0.1 to 10 hours. Examples of the solvent used in the reaction include hexane, heptane, toluene, xylene, and the like. The concentration of polyisoprene is 30
It can be as high as 5% to 20% by weight, but typically
Weight percent is preferred.

In the present invention, the hydrogenation rate in the hydrogenated product of polyisoprene, that is, the ratio of hydrogenated double bonds to carbon-carbon unsaturated double bonds in unmodified polyisoprene is in the range of 50 to 95%. If the hydrogenation rate is too low, the proportion of remaining double bonds will be too large, and when an epoxidized polymer is formed, the weather resistance and heat resistance will not be improved sufficiently, which is not preferable. On the other hand, if the hydrogenation rate is too large, the reaction rate during the epoxidation reaction becomes extremely slow, and the amount of epoxy groups introduced into the molecule becomes too small. Furthermore, the effect of improving physical properties based on the epoxy groups of the resulting epoxidized polymer becomes insufficient.

The epoxidation reaction is carried out by adding an epoxidizing agent to polyisoprene and heating it, or by using a combination of compounds that can act as an epoxidizing agent in the reaction system.
This is done by heating. Typical epoxidizing agents include organic peracids such as peracetic acid, perpropionic acid, and perbenzoic acid, and organic hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, and di-isopropenylbenzene peroxide. etc. Two compounds that can be used as epoxidizing agents are formic acid, acetic acid,
There are combinations of carboxylic acids such as propionic acid and hydrogen peroxide. Although this reaction can be carried out in the absence of a solvent, it is preferably carried out in the presence of a solvent that is inert to the epoxidizing agent and the like. The solvent is preferably an aliphatic hydrocarbon such as hexane or heptane, an aromatic hydrocarbon such as benzene or xylene, or a halogenated hydrocarbon such as chloroform or carbon tetrachloride.

The amount of the epoxidizing agent used in the above reaction varies depending on the degree of epoxidation and reaction conditions, but is preferably within the range of 0.1 to 10 equivalents relative to the double bond in the hydrogenated polyisoprene. .
The reaction temperature is preferably within the range of 0 to 20°C, but when using organic peroxides as the epoxidizing agent, a higher temperature is required;
The temperature is preferably within the range of 180°C, and in the case of using other epoxidizing agents, the temperature is preferably within the range of 20 to 120°C.

The reaction time varies depending on the amount of epoxidizing agent used, reaction temperature, etc., but is usually within the range of 0.5 to 10 hours.

The ratio of epoxy groups converted from carbon-carbon unsaturated double bonds in the epoxidized polymer of the present invention is the molar ratio to the carbon-carbon unsaturated double bonds in unmodified polyisoprene (hereinafter referred to as epoxidation rate). ) is within the range of 0.2 to 70%. If the epoxidation rate is too low, sufficient crosslinking will not be formed when the epoxidized polymer is crosslinked with a crosslinking agent, making it impossible to use it as a sealing material, coating material, etc. On the other hand, the epoxidation rate does not exceed 70% due to the relationship with the hydrogenation rate. From this point of view, the epoxidation rate is preferably 5 to 50%.

Effect In the present invention, how the polyisoprene hydrogenated product and the epoxidizing agent act in the reaction system, and the mechanism of action itself is not clear. However, as shown in JP-A-56-127641 mentioned above, when a hydrogenation reaction is performed after an epoxidation reaction, the catalyst used for hydrogenation and the epoxy group in the epoxidized polymer are reacts in a complex manner to form intramolecular or intermolecular crosslinks in the epoxidized polymer, but in the case of the present invention, first, a state in which there are no active groups other than carbon-carbon unsaturated double bonds is used. The hydrogenation reaction is carried out in the epoxidation reaction, and the epoxidation reaction is easy because there are few carbon-carbon unsaturated double bonds and there are no other groups that can easily react with the epoxidation agent. It is expected that this will progress.

Effects of the Invention In the production method of the present invention, the hydrogenation reaction and the epoxidation reaction proceed without side reactions such as gelation. Therefore, combined with a high reaction rate, an epoxidized polymer can be easily obtained at a high yield.

In addition, the resulting epoxidized polymer does not contain gels or impurities, and has few residual double bonds.
It has excellent weather resistance and heat resistance, and shows high reactivity due to the introduced epoxy group. Therefore, as well as polyepoxy compounds with low molecular weight and low epoxy value, amines such as diethylenetriamine, metaphenylenediamine, and tris(dimethylaminomethyl)phenol, carboxylic acids such as phthalic acid, succinic acid, and their anhydrides, and their Crosslink with anhydride, polyamide resin, boron trifluoride complex, etc. Taking advantage of these characteristics, it is suitable for use in applications such as adhesives, sealants, coating materials, and paints.

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

Example 1 Molecular weight 19000, vinyl bond content 21% obtained by solution polymerization using n-butyllithium as a catalyst
After dissolving 100 g of low molecular weight polyisoprene and 400 g of cyclohexane in an autoclave, a carbon-supported palladium catalyst (palladium:
Add 2g of 5% by weight), disperse, and add 35
The pressure was increased to Kg/cm ² . Next, a hydrogenation reaction was carried out at 50° C. while stirring. After 1 hour of reaction, the mixture was cooled to room temperature, residual hydrogen was released, and the reaction was stopped. The catalyst was removed from the reaction mixture by filtration and dried under vacuum to obtain a hydrogenated product of polyisoprene. The hydrogenation rate determined by infrared spectroscopy was 59%. Dissolve 60g of the hydrogenated material in 100g of toluene,
Add 10g of formic acid, raise the temperature to 50℃, and while keeping it at this temperature, add 100g of 30% by weight hydrogen peroxide solution to approx.
The mixture was added dropwise over time to carry out the epoxidation reaction. After the dropwise addition was completed, the mixture was kept at 50° C. for 1 hour, and then the aqueous layer was separated, the organic layer was washed with water, and the product was taken out by vacuum drying. The product was examined by infrared spectroscopy and was found to be modified polyisoprene with an epoxidation rate of 32 mol% and a hydrogenation rate of 59%.

5 parts by weight of tris(dimethylaminomethyl)phenol was added to 100 parts by weight of the above modified polyisoprene, and then the mixture was applied to a glass plate so that the thickness after drying and curing was 1 mm.
A cured film was created by heating for a period of time. The weather resistance of the cured film was examined using a xenon weather meter, and no change was observed in the cured film even after 500 hours of irradiation.

In addition, 100 parts by weight of the above modified polyisoprene, 30 parts by weight of methylnadic anhydride and 1 part by weight of tris(dimethylaminomethyl)phenol were mixed, and the mixture was poured into a Teflon-coated metal frame and heated at 150°C.
A cured molded product was created by heating for 30 minutes. The molded product was heated in a gear oven at 180°C for 1 hour,
No change was observed in the surface condition or shape of the molded product.

Comparative Example 1 In the epoxidation reaction of Example 1, the epoxidation rate was adjusted in the same manner as in Example 1 except that the unmodified polyisoprene before hydrogenation used in Example 1 was used instead of the hydrogenated polyisoprene. 36 mol%
of epoxidized polyisoprene was obtained. This reaction was repeated twice and approximately 325% of epoxidized polyisoprene was obtained.
I got g.

The hydrogenation reaction of Example 1 was carried out in the same manner as in Example 1, except that the above epoxidized polyisoprene was used in place of the non-hydrogenated unmodified polyisoprene, and the reaction time was changed to 2 hours. However, hydrogen absorption was extremely slow, and the hydrogen pressure in the system stopped decreasing one hour after the start of the reaction. I tried to stop the reaction 2 hours after starting the reaction and separate the catalyst from the reaction mixture, but
The reaction mixture was viscous and extremely difficult to filter. When we examined the barely obtained reaction product, we found that the residual rate of double bonds was 45%, the hydrogenation rate was 19%,
It was a modified polyisoprene with an epoxidation rate of 36 mol%.

A cured film and a cured molded product were made from the above modified polyisoprene in the same manner as in Example 1, and the weather resistance of each was examined using a xenon weather meter and the heat resistance was tested using a gear oven at 180°C. A thin cured film separated from the surface, and cracks appeared on the surface after 500 hours of irradiation. Also,
The surface of the cured molded product appeared sticky after 30 minutes of heating, and the surface was washed away after 1 hour of heating.

Example 2 100 g of polyisoprene with a molecular weight of 52,000 and a vinyl bond content of 16% was dissolved in hexane and charged into an autoclave, followed by a hydrogenation catalyst prepared by mixing cobalt naphthenate and triethylaluminum at a molar ratio of 1:5. A hexane solution containing cobalt per 100 isoprene monomer units in polyisoprene.
Add to make 0.1 mol, and add 10Kg/ with hydrogen.
The hydrogenation reaction was carried out at 50° C. under pressure of cm ² . After the reaction was completed, the obtained product was examined by infrared spectroscopy, and it was found that a polyisoprene hydrogenated product with a hydrogenation rate of 72% had been obtained.

Dissolve 60g of the above hydrogenated material in 100g of toluene,
10 g of formic acid was added, the temperature was raised to 50° C., and while maintaining this temperature, 100 g of 30% by weight hydrogen peroxide solution was added dropwise over about 1 hour to carry out an epoxidation reaction.
After the dropwise addition was completed, the mixture was kept at 50° C. for 1 hour, and then the aqueous layer was separated, the organic layer was washed with water, and the product was taken out by vacuum drying. When the product was examined by infrared spectroscopy, the hydrogenation rate was 72% and the epoxidation rate was 21%.
% of modified polyisoprene was obtained.

When the weather resistance of the modified polyisoprene was examined in the same manner as in Example 1, no change in condition was observed even after 500 hours of irradiation using a xenon weather meter.

Claims (1)

[Claims] 1. In producing an epoxidized polymer by reacting polyisoprene with an epoxidizing agent, a hydrogenated polyisoprene with a hydrogenation rate of 30 to 95% is used as the polyisoprene. A method for producing an epoxidized polymer. 2. The manufacturing method according to claim 1, wherein the polyisoprene has a molecular weight of 5,000 to 150,000 before hydrogenation.