JPS6262805A - Production of alpha-methylstyrene copolymer - Google Patents

Abstract

PURPOSE:To obtain the titled easily decomposable compound useful as an optical recording material, etc., in high yield, by adding an anionic polymerization initiator to the reaction system under a specific condition and polymerizing alpha-methylstyrene and an unsaturated carboxylic acid in the system at a low temperature. CONSTITUTION:A mixture of starting compounds consisting of (A) alpha- methylstyrene and (B) an unsaturated carboxylic acid (derivative) is added with (C) an anionic polymerization initiator (preferably an organolithium compound such as n-butyllithium) at 0-50 deg.C. The amount of the lithium compound is >=1.5X10<-3>mol per 1mol of the component A and selected to give a colored mixture which does not discolor immediately after the addition of the initiator C. After the completion of the addition of the initiator C, the polymerization reaction is carried out at -100-0 deg.C, preferably -50--5 deg.C to obtain the objective copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for copolymerizing α-methylstyrene. Specifically, the present invention relates to a method for obtaining a copolymer of α-methylstyrene and an unsaturated carboxylic acid or a derivative thereof in high yield.

[Conventional technology]

Since α-methylstyrene polymers are easily decomposable polymers that are easily decomposed into monomers by light, heat, etc., they are expected to be used as binders for ceramics or optical recording materials. As a method for obtaining a high polymer of α-methylstyrene, a low temperature cationic polymerization method or a low temperature anionic polymerization method is known. However, since α-methylstyrene polymers are not compatible with ceramics, etc., improvements are desired, and attempts have been made to copolymerize them with unsaturated carboxylic acids and their derivatives.

[Problem that the invention seeks to solve]

However, when the above-mentioned low-temperature anionic polymerization is performed to obtain a copolymer of α-methylstyrene and an unsaturated carboxylic acid or its derivative, almost no copolymer can be obtained even if an extremely large amount of anionic polymerization initiator is used. There was a problem.

[Means for solving problems]

The present inventors have conducted intensive studies on methods for solving the above problems, and have arrived at the present invention.

That is, the present invention provides a method for polymerizing α-methylstyrene and an unsaturated carboxylic acid or a derivative thereof using an anionic polymerization initiator.
It is added to a mixture of α-methylstyrene and an unsaturated carboxylic acid or its derivative at a temperature range of °C. -1.5X1 of methylstyrene
This is a method for producing a copolymer of α-methylstyrene, which is characterized in that a copolymer of α-methylstyrene is added in a molar ratio of 0 or more and a polymerization reaction is carried out at a temperature of -100 to 0°C.

In the present invention, it is possible to replace the α-methylstyrene portion with styrene or its nuclear substituted derivative, and the proportion thereof is preferably less than 30% by weight of α-methylstyrene. Above this level, the decomposability becomes poor, which is not preferable.

In the present invention, the ratio of unsaturated carboxylic acid and/or its derivative to α-methylstyrene is 0.
01 to 30% by weight, preferably 0.1 to 10% by weight. If it is less than 0.01% by weight, the compatibility with ceramics etc. will hardly be improved, and if it exceeds 3C1ffi, the decomposition properties of poly-α-methylstyrene will be lost, which is not preferable.

Preferred examples of unsaturated carboxylic acids or derivatives thereof used in the present invention include unsaturated carboxylic acids and/or esters and amides thereof; more specifically, acrylic acid, methacrylic acid, acrylamide, methacrylamide, Examples include N-substituted acrylamide, N-substituted methacrylamide, acrylic acid alkyl ester, and methacrylic acid alkyl ester.

The anionic polymerization initiator used in the present invention includes:
Preferably, organic lithium is used, and among them, alkyl lithiums, specifically n-butyl lithium, 5ec-butyl lithium and the like are commercially available.

In the present invention, the amount of the anionic polymerization initiator used varies depending on the molecular weight of the copolymer to be obtained, and also varies depending on the composition of the monomer, but the important thing is that the lower limit of the amount used is the amount of the polymerization initiator used. Add 1.5X of α-methylstyrene to an amount that does not cause the coloring to disappear instantly after mixing.
The molar ratio is 10-3 or more. Here, the amount by which the coloring after addition and mixing of the polymerization initiator does not disappear instantly means that the coloring does not disappear completely even 10 seconds after the red to reddish brown coloring when the anionic polymerization initiator is added is uniformly dispersed throughout. Indicates a state where does not disappear. This coloring can be confirmed visually or by measuring the visible absorption spectrum of the reaction solution.

The amount of addition needed to reach this state varies depending on the amount of unsaturated carboxylic acid and/or its derivative used, the amount of impurities in the monomer, and the amount of organic aluminum used together, but it is important. The key is to further add an anionic polymerization initiator with a molar ratio of α-methylstyrene of 1.5×10” or more, particularly preferably 1.5×10”.
It is to add an anionic polymerization initiator in a molar ratio of 10-3 to 10XIO' molar ratio.

In the present invention, ethers such as ethylene glycol sialkyl ether, diethylene glycol dialkyl ether, and tetrahydrofuran can also be used as the activator.

In the present invention, the polymerization medium includes α-methylstyrene itself, benzene, l-luene, ethylbenzene,
Inert solvents such as hexane, heptane, methylcyclohexane, decalin, tetralin, etc. can also be used.

What is important about the polymerization reaction temperature is that when adding the anionic polymerization initiator, the temperature is 0 to 50°C, and after the addition is completed, the polymerization temperature is 0°C or lower. The temperature when adding the anionic polymerization initiator is lower than 0℃ or 5
If the temperature is higher than 0°C, almost no polymer will be obtained no matter how the temperature is set thereafter. Furthermore, by controlling the polymerization temperature to 0° C. or lower after adding an anionic polymerization initiator, it becomes possible to significantly improve the yield based on the monomers used.

The preferred polymerization temperature after adding the anionic polymerization initiator is -100 to 0°C, particularly -50 to -5°C.

Even if it is below -100°C, there is no particular effect on improving the yield, and if it is higher than 0°C, the yield decreases, which is not preferable.

In the present invention, after the polymerization reaction, the anionic polymerization initiator is deactivated, and then, if necessary, unreacted monomers and/or inert solvents are removed by distillation or steam distillation, or they are poured into a large amount of methanol. Separate the copolymer by sedimentation.

〔Effect of the invention〕

By carrying out the method of the present invention, it is possible to obtain in good yield a copolymer of α-methylstyrene that maintains the degradability of polyα-methylstyrene itself and is compatible with ceramics, substrates, etc. It is extremely valuable industrially.

〔Example〕

Hereinafter, the present invention will be further explained with reference to Examples.

Example 1 α-methylstyrene 20ml 1. Toluene 8Qm/.

Diethylene glycol dimethyl ether 0.041rl
l.

Add 0.2 ml of N,N-dimethylacrylamide and 0.04 ml of methacrylic acid, stir while maintaining the temperature at 20°C, add butyllithium (15 wt% hexa/solution), and the mixture remains lightly colored even after 10 seconds of dispersion. After confirming this, 5 mmol of butyllithium Q (3.0 x 10 to 3 moles of α-methylstyrene) was added, and after 2 minutes, the temperature was raised to -30°C and polymerized for 2 hours. Next, a small amount of methanol was added to inactivate the mixture at °C, and then the copolymer was separated by pouring into a large amount of methanol. The obtained copolymer has a molecular weight of 17.77, the contents of N, N-dimethylacrylamide, and methacrylic acid are 1.5 wt% and 0.3 wt%, respectively, and the intrinsic viscosity measured in a toluene solution at 30°C is 1.0
It was 4. Therefore, the yield for α-methylstyrene is 97
%.

Also, the additional amount of butyllithium was added to α-methylstyrene by 1.
0X10. 1.5X10. When the mole was changed to 2×10, the yield and intrinsic viscosity were 35% and 1, respectively.
．． 07.96%, 1.09.96%, and 1.09.

Comparative Example 1.2 Example 1 except that butyllithium was added at -30°C
I did the same thing. However, in Comparative Example 1, the amount of butyllithium added after the coloring stopped disappearing was the same, and in Comparative Example 2, the amount of all butyllithium used was the same. In either case, substantially no methanol-insoluble polymer was obtained.

Comparative Example 3 The procedure was the same as in Example 1 except that the polymerization temperature after the additional addition of butyllithium was 20°C. The yield was only 28 wt%.

Example 2 The same procedure as Example 1 was carried out except that 0.02 mA' of acrylic acid and 0.02 ml of hydroxymethacrylic acid were used instead of methacrylic acid. The yield for α-methylstyrene is 98
wt%, and the intrinsic viscosity of the obtained copolymer is 1.0
It was 9. Further, the contents of N,N-dimethylacrylamide, acrylic acid, and hydroxyethylmethacrylic acid in the copolymer were 1.8.0.2.0.1 wt%, respectively.

Example 3 The amount of butyllithium added after coloring was 1.0 mmol (
Example 1 except that the amount of α-methylstyrene was increased by 6 × 10-' mole times) and the subsequent polymerization temperature was -10°C.
I did the same thing. The yield was 93 wt%.

In addition, the intrinsic viscosity is 0.96, and the N and N in the copolymer
-The contents of dimethylacrylamide and methacrylic acid were 1 and 6.0.3 wt%, respectively.

Comparative Example 4 The amount of butyllithium added after coloring was 0.2 mmol (
The procedure was the same as in Example 1, except that the molar ratio was reduced to 1.2 x 10'' (3 times molar ratio to α-methylstyrene) and the subsequent polymerization temperature was set to -1'O'C. The yield was only 45 wt%. In addition, the intrinsic viscosity is 0.95, and N, N-
The contents of dimethylacrylamide and methacrylic acid were 1.6 and 0.3 wt%, respectively.

Reference Example Each of the copolymers of Examples 1 to 3 was mixed with 101% of the copolymer and 3% of toluene.
When it was dissolved in 0ml and kneaded with alumina (particle size: 2 μm) 309-, everything was well dispersed to form a uniform slurry.

Claims (1)

[Claims] 1. In a method of polymerizing α-methylstyrene and an unsaturated carboxylic acid or its derivative using an anionic polymerization initiator, the anionic polymerization initiator is
1.5 x 10 of α-methylstyrene is added to the mixture of methylstyrene and unsaturated carboxylic acid or its derivative, and the amount added is such that the coloring does not disappear instantly after adding and mixing the anionic polymerization initiator. A method for producing a copolymer of α-methylstyrene, characterized in that the copolymer is added in a molar ratio of ^-^3 or more and a polymerization reaction is carried out at a temperature of -100 to 0°C.