JPH0617417B2 - Method for producing α-methylstyrene copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a copolymer of α-methylstyrene. More specifically, the present invention relates to a method for producing a copolymer of α-methylstyrene which is suitable as a ceramic binder and has excellent decomposability and compatibility.

[Conventional technology]

A polymer of α-methylstyrene is extremely easily decomposed to form a low molecular weight monomer or the like and easily scattered, so that it is expected to be used as a ceramic binder, an optical recording material, or the like. However, since α-methylstyrene has a low ceiling temperature, and low-temperature anionic polymerization needs to be performed to obtain a high molecular weight substance, a copolymer containing α-methylstyrene as a main component was hardly known. .

[Problems to be solved by the invention]

The homopolymer of α-methylstyrene is an excellent polymer that is easily decomposed by heat, light, etc. and becomes a monomer, but when it is used as a ceramic binder or an optical recording material, it is alumina, silica, or silicon. It is not suitable as a ceramic powder such as carbide, silicon nitride, boron carbide, boron nitride, etc., it is not suitable as a binder, and also as an optical recording material, it is not compatible with the substrate after it is dried and peeled off. There was a problem such as. On the other hand, it may be possible to copolymerize with a monomer having a polar group such as carboxylic acid, carboxylic acid amide, and carboxylic acid ester. It is not easy to copolymerize with the polar group-containing monomer, and development of a copolymer obtained by copolymerizing α-methylstyrene and the polar group-containing monomer has been desired.

[Means for solving problems]

The present inventors have earnestly studied a method for solving the above problems and arrived at the present invention.

That is, in the present invention, an unsaturated group-containing copolymer of α-methylstyrene and divinylbenzene and / or diisopropenylbenzene, an unsaturated carboxylic acid and / or its derivative, and a radical polymerization initiator are dissolved in an organic solvent. The method for producing an α-methylstyrene copolymer is characterized in that the copolymerization is carried out in the absence of water.

The unsaturated group-containing copolymer used in the present invention is a copolymer of α-methylstyrene and divinylbenzene and / or diisopropenylbenzene. At this time, styrene or its derivative may be used in about 30% by weight of α-methylstyrene. However, if it exceeds 30% by weight, decomposability becomes poor, which is not preferable.

The copolymer of α-methylstyrene and divinylbenzene and / or diisopropenylbenzene can be produced by a radical polymerization method or an anionic polymerization method, and α-methylstyrene and divinylbenzene and / or diisopropenylbenzene can be produced. The proportion of divinylbenzene and / or isopropenylbenzene with respect to the total amount of is 2 to 30% by weight, so that there are few problems during the production of the copolymer, and it is also preferable for the next reaction.

In the above-mentioned polymerization, it is possible to use a known radical polymerization initiator such as peroxide or azobisnitrile and / or a known anionic polymerization initiator such as alkyllithium or sodium naphthalene, and the polymerization conditions are special. However, the method described in JP-A-59-207905 or the like can also be used.

The copolymer obtained by the above method is separated from the unreacted monomer to obtain a vinyl group- and / or isopropenyl group-containing copolymer (hereinafter abbreviated as polymer A). This is used in the reaction described below.

Examples of the unsaturated carboxylic acid and / or its derivative used in the present invention include acrylic acid, methacrylic acid, acrylamide, N, N-dimethylacrylamide, methacrylamide, N, N-dimethylmethacrylamide, acrylic acid ester, and methacrylic acid ester. Kind of things.

These unsaturated carboxylic acids and / or their derivatives are used in the resulting α-methylstyrene copolymer in an amount of 0.01 to 30% by weight. If it is less than 0.01% by weight, the compatibility with ceramics is hardly improved, or 3
When it exceeds 0% by weight, the characteristics of poly-α-methylstyrene are lost, which is not preferable.

The copolymerization method of the polymer A and the unsaturated carboxylic acid and / or its derivative is not particularly limited as long as it is carried out in the presence of a radical polymerization initiator, but it is usually radical polymerization in a solution in which the polymer A is dissolved. It is carried out by adding an initiator (the above-mentioned ones can be used) and an unsaturated carboxylic acid and / or a derivative thereof and keeping the conditions (heating, light irradiation, etc.) under which the radical polymerization initiator acts. At this time, the normal polymer A
It is preferable to maintain the concentration of 5 to 60% by weight, the concentration of unsaturated carboxylic acid and / or its derivative is 0.05 to 20% by weight, and the concentration of the radical polymerization initiator is 0.001 to 1% by weight. The reaction temperature is -30 ° C to 150 ° C, preferably 0 ° C to 100 ° C.

In the present invention, the copolymerization is carried out in the absence of water.

〔Example〕

 Hereinafter, the present invention will be further described with reference to examples.

The intrinsic viscosity number of the polymer was measured with a 30 ° toluene solution.

Example 1 α-Methylstyrene (10 vol%) and divinylbenzene (0.5 vol%) were polymerized at −10 ° C. with an anionic polymerization initiator butyllithium (15 wt% hexane solution, 0.15 vol%) in a toluene solvent, and then a large amount. Α-methylstyrene-divinylbenzene copolymer obtained by throwing it in methanol (containing an intrinsic viscosity of 0.19 and divinylbenzene of 5.2 wt%)
5 g was dissolved in 90 ml of toluene, 0.5 ml of N, N-dimethylacrylamide, 0.1 ml of acrylic acid and 0.25 g of benzoyl peroxide as a polymerization initiator were added, reacted at 80 ° C. for 5 hours, and then poured into a large amount of methanol. . The intrinsic viscosity of the obtained polymer (copolymer 1) was 0.21, and the contents of N, N-dimethylacrylamide and acrylic acid calculated by elemental analysis and infrared absorption spectrum were 2.5 wt.
% And 0.8 wt%.

Example 2 A polymer (copolymer 2) was obtained in the same manner as in Example 1 except that 0.1 ml of hydroxyethyl methacrylic acid ester was used instead of acrylic acid. The intrinsic viscosity of the obtained copolymer was 0.20, and the contents of N, N-dimethylacrylamide and hydroxyethyl methacrylate were respectively
It was 2.4 wt% and 0.7 wt%.

Example 3 α-methylstyrene (20 vol%) in a toluene solvent,
Diisopropenylbenzene (1vol%) was added to -10 ℃ with butyllithium (10wt% hexane solution, 0.2vol%).
Polymerization was carried out for 0.5 hours at room temperature, and the mixture was poured into a large amount of methanol and separated in the same manner as in Example 1. The copolymer obtained has an intrinsic viscosity of 1.6.
3. The diisopropenylbenzene content was 5.7 wt%.

10 g of this copolymer was dissolved in 100 ml of dimethylformamide, 0.5 g of acrylamide and 0.5 g of azobisisobutyronitrile were added, and polymerization was carried out at 70 ° C. for 10 hours. The copolymer 3 thus obtained contained 3 wt% of acrylamide by elemental analysis.
%, And the intrinsic viscosity was 1.72.

Using the copolymers 1 to 3 obtained in Examples 1 to 3 and the copolymers of α-methylstyrene and divinylbenzene or diisopropenylbenzene obtained in Examples 1 and 3, 10 g of each was added to 30 ml. 30 g of alumina (particle size: 2 μm) was added to the solution prepared by dissolving in toluene and kneaded, and the dispersibility was examined.

In the case of using the copolymers 1 to 3, a slurry in which alumina was uniformly dispersed was obtained, but when a polymer in which the unsaturated carboxylic acid and / or its derivative was not copolymerized was used, the alumina was uniform. Did not disperse in.

〔The invention's effect〕

By carrying out the method of the present invention, the degradability possessed by poly-α-methylstyrene itself is retained, and ceramic,
It is possible to obtain a copolymer of α-methylstyrene that is well compatible with substrates and the like, which is extremely valuable industrially.

Claims (1)

[Claims] 1. An unsaturated group-containing copolymer of α-methylstyrene and divinylbenzene and / or diisopropenylbenzene, an unsaturated carboxylic acid and / or its derivative, and a radical polymerization initiator are dissolved in an organic solvent, A method for producing an α-methylstyrene copolymer, which comprises copolymerizing in the absence of water.