JPS6243409A - Production of thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain the titled resin having improved heat resistance while suppressing formation of low-molecular weight copolymer, by feeding continuously a mixture of alpha-methylstyrene, acrylonitrile and styrene to a completely blending type reactor of single tank and polymerizing it under a specific condition. CONSTITUTION:Firstly, a monomer mixture consisting of (A) 30-60wt% alpha- methylstyrene, (B) 20-40wt% acrylonitrile and (C) 50-5wt% styrene is continuously fed to a completely blending type reactor of single tank. Further, the amount of a radical polymerization initiator (initiator for short) added in the reactor is controlled in such a way that the amount is kept 0.05-0.0015mol% based on the component A which is being fed and the continuous polymerization of the monomer mixture is carried out at 100-130 deg.C while maintianing polymerization conversion ratio in the reactor at 30-60%, to give the aimed resin. Benzoyl peroxide, etc., are preferable as the initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing an α-methylstyrene-acrylonitrile-styrene copolymer.

[Conventional technology]

Conventionally, α-methylstyrene-acrylonitrile-styrene copolymers have been mainly produced batchwise by emulsion polymerization or suspension polymerization. These methods require a long time for polymerization and have low volumetric efficiency, resulting in poor productivity.

On the other hand, bulk polymerization by a batch method has also been attempted (for example, Japanese Patent Publication No. 49-20076), but the polymerization time was also long.

Continuous bulk polymerization has also been proposed as a method to solve these problems (for example, JP-A-59-147037).
.

[Problem that the invention seeks to solve]

Copolymers containing α-methylstyrene have excellent heat resistance, and the heat resistance depends on the content of α-methylstyrene. The continuous bulk polymerization described above is preferable from the viewpoint of production efficiency, but the low molecular weight copolymer is formed during production, and the heat resistance is insufficient even though it contains a sufficient amount of α-methylstyrene. There was a problem.

Unreleased:・Lj (2) Q-wise, the formation of this copolymer of low molecular weight 1i! 11,>-1st generation falsehood:・This is an excellent α-
One methyl styrene = -, 7:) ml ``Nor'' - 7 major methods for producing methyl styrene/copolymers -
There is one particular thing.

Means for Solving the Problem] The present inventors have conducted various studies to achieve the above object 1, and have finally made the invention. I have almost completed it.

"In other words, the present invention uses α-methylstyrene 30 to 60
;゛), a monomer mixture t etc. consisting of 20-40% of acrylonitrile and 59-5% of styrene by weight
Polymerization is carried out by continuously feeding L into a complete mixing type reactor: At this time, L, (]) The amount of radical polymerization initiator during the reaction must be 0.05 to 0.0015 of α-methylstyrene. mole%,
(2) The polymerization temperature is ioo to 130'C, and (3
) A method for producing a thermoplastic resin, characterized in that the polymerization conversion rate in a reaction tank is maintained at 30 to 60% by weight.

Small invention: C: F6, the monomer composition supplied to the reaction tank is α-methylstyrene/N ○~60% by weight T, acrylonitrile 20~40% by weight, and styrene 50~5% by weight
It is important that the amount of α-methylstyrene is 3
Can it be obtained if it is less than 0% by weight? The heat resistance of the tow polymer becomes insufficient, and if it exceeds 60% by weight, the polymerization rate decreases and the molecular weight of the resulting copolymer decreases, which is not preferable. On the other hand, if the amount of acrylonitrile is less than 2% by weight of Clt, the polymerization rate will decrease, and if it exceeds 40% by weight, the copolymer L) will be colored, which is not preferable. Further, since Styrene increases the polymerization rate, it is preferable from an economical point of view to have a large amount, and the optimum amount is 50 to 5% by weight.

The single-vessel complete mixing type reaction vessel used in the present invention refers to a reaction vessel 11.5 in which a mixing state is maintained such that the interior of the reaction system for polymerization is substantially uniform.・For example, Kosho Kaguri 52-4
Examples include those shown in No. 2834.

In the present invention, as the radical polymerization initiation 1, the temperature normally used for polymerization of styrene monomers can be used, and the 10 hour half-life temperature is 6□] to 100'C to initiate radical polymerization. The agent is preferably ℃・. For example, benzoyl peroxide, t-butylperoxyisobutyrate, t-
Butyl peroxy (2-ethyl hegisanoate), cumyl peroxy octoate, lauroyl peroxide, 1,1-bis(t-butyl peroxy)-3,3,5
Examples include -IJ methylcyclohexano, 2,2'-azobisisobutyronitrile, and 2,2'-azobis(2-methylbutyronitrile).

In the present invention, it is important to maintain the above-mentioned radical polymerization initiator at an amount of 0.005 to 0.0015 mol% relative to the continuously supplied α-methylstyrene. If it is less than this, many low molecular weight copolymers will be produced,
The heat resistance of the obtained copolymer will be insufficient, and if it is used in excess of this range, the molecular weight of the obtained copolymer will decrease, which is not preferable.

In addition, the molecular weight is usually dimethylformamide volume Q
(0,51 and 100 - each group) at 30℃ 41
1] It is desirable that the determined reduced viscosity is 045 or higher.

The polymer of the present invention may be diluted with a solvent such as benzene, toluene, ethylbenzene, isopropylbenzene, acetone, methyl ethyl ketone, etc., but if a large amount of solvent is used, the molecular weight of the copolymer obtained will decrease and productivity will also decrease. Therefore, it is usually desirable to limit the amount to 20% by weight or less based on the single-counterfeit composition.

In the present invention, polymerization is carried out at 100-130'C.

If it is less than 100°C, productivity will decrease, so it is not preferable (,
At temperatures higher than 150°C, a large amount of low molecular weight copolymer is produced, and the heat resistance of the resulting copolymer deteriorates.

The average residence time in the reaction tank is usually 1 to 5 hours. If it is shorter than 1 hour, it is not preferable because a large amount of radical polymerization initiator is required to increase the conversion rate, which lowers the molecular weight of the copolymer. On the other hand, if it exceeds 5 hours, productivity will be poor ( It becomes a problem.

In the present invention, it is important to maintain the polymerization conversion rate within the reaction tank at 30 to 60% by weight. If the conversion rate is less than 60% by weight, a large amount of low molecular weight copolymer will be produced, which is undesirable, and productivity will also be low.

In addition, at a conversion rate higher than 60% by weight, the polymerization reaction becomes unstable and a double feeding reaction is likely to occur (unfavorable).

,,i The reaction solution polymerized as described above and discharged from the reaction tank is recovered by removing unreacted monomers (including the solvent), and the copolymer is isolated. There are no particular restrictions on the method for removing this unreacted monomer, but there are
The method described in No. 8-29797 can be applied.

Note that the remaining amount of unreacted monomers and solvents is preferably 0.5% by weight or less, preferably 0.3% by weight or less of the copolymer (particularly desirable from the viewpoint of heat resistance).

In the present invention, the amount of radical polymerization initiator in the reaction tank can be determined by direct analysis, but the decomposition rate equation of the radical 1 polymerization initiator (formula (I) below) and the state equation of the complete mixing type reaction tank (formula (I) below) Find it from the formula (■)). Therefore, the amount of the radical polymerization initiator 4j to be added can be appropriately determined from these formulas, and in the present invention, the amount of the radical polymerization initiator was adjusted by this method.

Kd = Aexp (-E/RT)
(I
) where Kd: Decomposition rate constant (hr) A: Frequency factor (hr') E: Activated engineering energy (Ca11 mol) R: Gas constant T: Temperature inside the reaction tank (0K) C=Co/(Kd・θ+1 ) (
El) [Examples] The present invention will be explained below with reference to Examples.

Examples 1 to 7, Comparative Examples 1 to 7 α-methylstyrene 40% by weight, acrylonitrile 25%
% by weight and 35% by weight of styrene were charged into a tank and polymerized. In addition, the polymerization temperature, average residence time, conversion rate, and concentration of the radical polymerization initiator (1-butylperoxy(2-ethylhexanoate)) (vs. charged α-methylstyrene) were adjusted as shown in Table 1. and polymerized. In addition, a radical polymerization initiator was dissolved in ethylbenzene in a predetermined amount and charged. After removing residual monomers from the continuously obtained polymerization liquid using a volatile matter removal device equipped with a heater and a vacuum chamber, the mixture was extruded using an extruder to obtain copolymer pellets. The heater is heated by a heating medium at 270°C, and the degree of vacuum is 30°C.
Torr.

Amount of low molecular weight copolymer (LMR) in the obtained single copolymer
, reduced viscosity, heat resistance (VSP) and residual monomer content were measured by deletion. The results are shown in Table 1.

LMR: copolymer pellet 12 to methyl ethyl ketone 2
The high molecular weight copolymer is precipitated by dissolving it in 0WLt and gradually adding this solution to 200ml of stirring methanol. Shen ljt? : After removal, the solution is concentrated, the residue is vacuum-dried, and then weighed to determine the low molecular weight copolymer weight A2, which is multiplied by 100 to obtain LMR. (Unit, weight %) Reduced viscosity: Measured at 30°C with a solution of 0.5 f of the copolymer dissolved in 100 ml of dimethylformamide. (Unit, dt/f) VSP: Indicated by Vikanoto softening point according to method A of JIS K7206. (Unit, °C) Residual monomer: The copolymer was dissolved in dimethylformamide and determined by gas chromatographic analysis.

(Unit, weight %) Example 8 Example 1 was repeated except that the degree of vacuum in the devolatilizer was changed to 60 Torr. The results are shown in Table 1.

Example 9, Comparative Examples 8 and 9 A monomer mixture consisting of 60% by weight of α-methylstyrene, 25% by weight of acrylonitrile and 5% by weight of styrene was used, and the polymerization conditions were as shown in Table 1. Polymerization and post-treatment were carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 10 Same as Example 1 except that a monomer mixture consisting of 30% by weight of α-methylstyrene, 25% by weight of acrylonitrile and 45% by weight of styrene was used, and the polymerization conditions were as shown in Table 1. Polymerization and post-treatment were performed. The results are shown in Table 1.

Example 11 Example 1 except that benzoyl peroxide was used as the radical polymerization initiator and the polymerization conditions were as shown in Table 1.
Polymerization and post-treatment were carried out in the same manner as above. The results are shown in Table 1.

〔Effect of the invention〕

As can be seen in Table 1, when the concentration of radical polymerization initiator in the reaction tank is low, the temperature is 5 to 9°C inferior to that obtained by the present invention (Comparative Example 1.2.8); If it is too high, the reduced viscosity is low (unfavorable (Comparative Examples 3, 4.9). If the conversion rate is lower than the range of the present invention, both Ml and VSP are inferior to those of the present invention (Comparative Examples). 5), when it was high, polymerization became impossible (Comparative Examples 6 and 7).

According to the present invention, the formation of low molecular weight copolymers is reduced,
It is possible to easily and continuously obtain an α-methylstyrene-acrylonitrile-styrene copolymer having excellent heat resistance.

Claims (1)

[Claims] 1. 30-60% by weight of α-methylstyrene, 20-40% by weight of acrylonitrile, and 50-5% by weight of styrene.
When a monomer mixture consisting of:
05 to 0.0015 mol%, (2) the polymerization temperature is 100 to 130°C, and (3
) A method for producing a thermoplastic resin, characterized in that the polymerization conversion rate in a reaction tank is maintained at 30 to 60% by weight.