JPS6377904A - Production of thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain the title resin being excellent in strength, heat resistance and moldability and undergoing no flashing, by feeding a solution or the like of a rubber polymer and a copolymer containing aromatic vinyl monomer residues, unsaturated dicarboxylic acid imide derivative residues, etc. to a specified extruder and extruding it. CONSTITUTION:A copolymer solution of a concentration of 20-80wt%, obtained by copolymerizing 0-20wt% rubbery polymer (A) such as a butadiene polymer with 30-80wt% aromatic vinyl monomer (B) [e.g., (alpha-methyl)styrene], 20-60wt% unsaturated dicarboxylic acid imide derivative monomer (e.g., N- methylmaleimide) and 0-20wt% other copolymerizable vinyl monomer (D) (e.g., methyl methacrylate) in a solvent, etc., such as methyl isobutyl ketone is fed to a multistage vented codirectional twin-screw extruder in which the screws have one or two pairs of left-handed screw threads and extruded by operating this extruder so that the ratio of the polymer discharge quantity Q(kg/hr) to the revolution speed of screw, NS(rpm), may satisfy the relationship of the formula to obtain the title imide group-containing resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a thermoplastic resin having an imide group.

[Conventional technology and problems]

Conventional methods for separating polymers and solvents include (1) a method in which heated polymer is fed into a devolatilizing tank in the form of a thread, and the solvent is removed by keeping the devolatilizing tank under commercial vacuum (falling strand method); ■ A method in which the polymer liquid is fed into a drum in a vacuum system and made into a sheet to remove the solvent, etc. (drum dryer method), and ■ A method in which the solvent, etc. is removed using a thin film evaporator (thin film evaporator method). Are known.

However, for example, in the case of a solution of a copolymer having an aromatic vinyl monomer residue and an unsaturated dicarboxylic acid imide derivative residue, these methods have the following problems.

In the falling strand method, unless the polymer is heated to a sufficiently high temperature and fed to the devolatilization tank, the devolatilized polymer will have a very high viscosity and will be difficult to extract. On the other hand, if the necessary amount of heating is performed, the molecular weight of the polymer will decrease, which is not preferable.

Furthermore, in the case of the drum dryer method, it is difficult to maintain a high vacuum, resulting in a large amount of residual solvent in the polymer.

On the other hand, if the sheet is heated for a long time in order to reduce the amount of residual solvent, the molecular weight will decrease, which is not preferable.

In the case of the thin film evaporator method, if the clearance between the inner wall and the blade is wide, the polymer will adhere to the inner wall, making it impossible to remove the solvent. On the other hand, if the clearance is narrowed, excessive shear will be applied to the polymer, resulting in a decrease in molecular weight, which is not preferable.

As described above, by using the conventional techniques, only resins having poor heat properties and moldability (poor molding) of the above-mentioned copolymers were obtained.

Means for Solving Problem C] As a result of intensive studies to improve these drawbacks, the present inventors have found that by removing the solvent etc. using a specific extruder with a devolatilization device, The amount of residual solvent is small,
This is the first success in obtaining a thermoplastic resin containing imide groups that maintains a high molecular weight and has excellent strength, heat resistance, and moldability. Further, according to the method of the present invention, solvent removal or dehydration can be done in one step, and it is economically superior to other methods.

The method of the present invention can be applied not only to removing the solvent from a polymer solution, but also to obtaining a polymer by dehydrating an aqueous suspension or emulsion of the polymer.

That is, the present invention comprises O to 20% by weight of a rubbery polymer, 30 to 80% by weight of aromatic vinyl monomer residues, 20 to 60% by weight of unsaturated dicarboxylic acid imide derivative residues, and 1% by weight of other vinyl monomers. Co-rotating co-rotating twin-screw extruder with multi-stage vents, in which the number of counterclockwise threads in each screw is 1 or 2 pairs lead to,
Polymer discharge amount (kg/Hr) / Screw rotation speed (
rpm) = Q/NS (kg/Hr-rp
lm) is a method for producing a thermoplastic resin having an imide group, characterized in that the extruder is operated in the range of .lm).

First, the constituent components of the copolymer applied to the method of the present invention will be explained.

Examples of rubbery polymers include butadiene polymers, copolymers of butadiene and vinyl monomers copolymerizable with it, ethylene-propylene copolymers, ethylene-propylene-diene copolymers, butadiene and aromatic Examples include block copolymers with vinyl, acrylic ester polymers, and copolymers of acrylic esters and vinyl monomers copolymerizable therewith.

Further, the content of the rubbery polymer in the copolymer can be selected within the range of 0 to 20% by weight. Rubbery polymers do not need to be present, but if impact resistance is required,
Preferably, it is present in an amount up to 20% by weight. However, if it exceeds 20% by weight, the heat resistance and moldability of the final thermoplastic resin will deteriorate, which is not preferable.

The composition of the monomer residues constituting the copolymer other than the rubbery polymer is 30 to 80% by weight of aromatic vinyl monomer residues, 20 to 60% by weight of unsaturated dicarboxylic acid imide derivative residues, and these. Copolymerizable vinyl monomer residue 0-20% by weight
If the number of aromatic vinyl monomer residues is less than 30 times, moldability and dimensional stability, which are characteristics of aromatic vinyl compounds, will be lost. In addition, if the unsaturated dicarboxylic acid imide derivative residue is less than 20% by weight, the heat resistance will not be sufficient;
If the amount exceeds % by weight, the copolymer becomes brittle and its moldability deteriorates significantly.

Examples of aromatic vinyl monomers include styrene monomers such as styrene, α-methylstyrene, vinyltoluene, L-butylstyrene, and chlorostyrene, and substituted monomers thereof.

Examples of unsaturated dicarboxylic acid imide derivatives include imide derivatives of anhydrides such as maleic acid, itaconic acid, citraconic acid, and aconitic acid.

In addition, vinyl monomers other than these include vinyl cyanide monomers such as acrylonitrile, methacrylonitrile, and α-chloroacrylonitrile, and acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate. Monomers, methacrylic acid ester monomers such as methyl methacrylic acid ester and ethyl methacrylic acid ester, vinyl carboxylic acid monomers such as acrylic acid and methacrylic acid, acrylamide, methacrylic acid amide, acenaphthylene and N-vinylcarbazole , maleic anhydride, etc.

The imide group of the unsaturated dicarboxylic acid imide derivative residue in the present invention includes ammonia and primary amines such as methylamine, ethylamine, N-propylamine, iso-
Bg from alkylamines such as propylamine, butylamine, pentylamine, and cyclohexylamine, and aromatic amines such as these chloro- or bromo-substituted alkylamines, aniline, toluethylamine, and naphthylamine.
5.

As a method for producing a copolymer, for example, (1) an aromatic vinyl monomer and an unsaturated dicarboxylic acid imide derivative monomer such as N-phenylmaleimide, N-cyclohexylmaleimide, N-methylmaleimide, N-ethylmaleimide, etc. (2) an aromatic vinyl monomer and an unsaturated dicarboxylic acid anhydride, such as maleic acid, After copolymerizing anhydrides such as itaconic acid, citraconic acid, and aconitic acid, and optionally a rubbery polymer and other copolymerizable vinyl monomers, the acid anhydride in this copolymer is combined with ammonia or alkyl There is a method of imidization with an amine or a primary amine such as aniline. In the imidization reaction in method (2), 100% of the acid anhydride may be imidized, but unreacted acid anhydride may be left within the scope of the claims.

In the production methods (1) and (2) above, polymerization is carried out by bulk polymerization, solution polymerization, water suspension polymerization, water emulsion polymerization, or the like.

Moreover, the imidization reaction (2) is carried out in the presence or absence of a solvent.

Therefore, depending on the manufacturing process, the imide group-containing copolymer produced by method (11 or (2)) may be dissolved in a solvent, suspended in water, or emulsified in water. obtained in the state.

Although the present invention is a particularly suitable method for obtaining thermoplastic resins from such solutions, aqueous suspensions, or aqueous emulsions, it is of course applicable to copolymers produced by other methods. be.

When the copolymer supplied to the extruder is in a solution state, examples of the solvents included include acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, tetrahydrofuran, dimethylformamide, benzene, toluene, xylene, chlorobenzene, etc. . The copolymer content in the solution is usually 20-80% by weight. In the case of aqueous suspensions, the copolymer content in water is usually 30-70% by weight. In the case of a water emulsion, the copolymer content in water is usually 20 to 50% by weight.

The present invention is a method for producing a thermoplastic resin from a solution, aqueous suspension, or aqueous emulsion of the above copolymer by using a specific extruder and removing solvent or dehydrating the copolymer under specific conditions.

The extruder used has 1 or 2 reverse screws in all screws.
This is a co-rotating twin-screw extruder with twin vents and a multi-stage vent. A reverse thread is also called a reverse thread, and as shown in the drawings, the thread is threaded in the opposite direction to that of a normal thread, that is, a normal thread (forward thread).

When removing solvent or dehydrating without using a reverse screw,
It is not possible to reduce the residual volatile content in the polymer. On the other hand, if you use three or more pairs of reverse screws, the amount of residual solvent will decrease, but
This results in a decrease in the molecular weight of the obtained polymer. Further, the specifications of the main body of the co-rotating twin-screw pusher with multi-stage vents may be normal and are not particularly limited, but preferably the number of barrels is 6 to 12 and the number of vents is 2 to 5. Also, one of the vent holes may be located at the rear side (relative to the tip) of the polymer liquid feed position.

The operating conditions of the extruder are as follows: Polymer discharge N (kg/Hr) / Screw rotation speed (rpm) = Q/NS (kg/Hr - rp
m) must be carried out under the following conditions.

Molecular weight becomes smaller. On the other hand, if the coefficient of A is larger than 0.3, the molecular weight of the polymer will hardly decrease, but the amount of residual volatile matter will increase.

For example, when using the extruder with a screw diameter of 101 m/m, a resin satisfying the molecular weight and residual volatile content can only be obtained under operating conditions of Q/N S =0.83 to 1.67. The barrel temperature of the extruder is 50 to 350.
It is preferable to operate the temperature at a temperature of 300 tor to 5 tor.

The success of the present invention is largely due to the discovery of the screw configuration and operating conditions for the co-rotating twin-screw extruder with multi-stage vents as described above.

In addition, the thermoplastic resin having an imide group obtained by the production method of the present invention has a high molecular weight and a small amount of residual solvent, so it has excellent strength and heat resistance, and has excellent moldability, especially foaming of residual solvent during injection molding. This is excellent because there is no flash phenomenon caused by this.

The thermoplastic resins obtained in this way include styrene-acrylonitrile copolymer (SAN resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-butadiene-styrene-α-methylstyrene copolymer, Acrylonitrile-ethylene, propylene rubber-styrene copolymer, styrene-methyl methacrylate copolymer, methyl methacrylate-butadiene-styrene copolymer, aromatic polycarbonate, aromatic polyester, polyphenylene oxide, polyphenylene sulfide, polyamide, polyurecne It can also be mixed with. Among these, it is particularly compatible with ABS resin, and a mixture thereof is preferable in terms of impact resistance and moldability. In addition, stabilizers, ultraviolet absorbers, flame retardants, plasticizers, lubricants, fibers such as glass, inorganic fillers, coloring agents, and antistatic agents are all expressed as important criteria.

Example-1 Styrene 5 in an 8001 autoclave equipped with a stirrer
8 kg, methyl isobutyl ketone 38 kg.

Polybutadiene cut into small pieces (Diene N manufactured by Asahi Kasei Co., Ltd.)
After charging 20 kg of F55R) and purging the system with nitrogen gas, the mixture was stirred at room temperature all day and night to dissolve the rubber.

After the temperature was brought to 80° C., a solution of 51 kg of anhydrous maleic M and 150 g of benzoyl peroxide dissolved in 300 kg of methyl isobutyl ketone was continuously added over 10 hours. The temperature was maintained at 80° C. for an additional 4 hours after the addition.

After adding 48 kg of aniline to the polymerization solution thus obtained, it was heated to 140° C. and kept at this temperature for 4 hours. As a result, polybutadiene 11.9%, styrene residue 3
A methyl isobutyl ketone solution of a copolymer containing 4.6% and 53.5% of N-phenylmaleimide residues was obtained. This solution is transferred using a gear pump to a four-stage vented co-rotating twin-screw extruder (TEM-50B, screw diameter 57 m/m) consisting of 9 barrels.

(manufactured by Toshiba Machine). As for the screw configuration at this time, one reverse screw was installed at the barrel position 13 in front of the tip barrel and one in the barrel position 3 barrels in front of the tip barrel. Further, Q/NS was carried out under the conditions of 0.2 (discharge amount 50 kg/screw rotation speed 250 rpm).

Also, the temperature of the cylinder is 140℃ from the feed section to the discharge section.
A temperature distribution was provided from ℃ to 300℃.

The degree of vacuum at each vent hole is 30 degrees at the first stage vent hole.
0 mmHg, degree of vacuum at the second stage vent hole 200 mmH
g, third vent hole 100mm 11g, fourth vent hole 50
It was mmHg. The remaining methyl isobutyl ketone in the resulting pellets was 0.1% and the molecular weight was 130,000.

50 parts of the thus obtained thermoplastic resin having an imide group and a styrene resin (H3-300 manufactured by Denki Kagaku Co., Ltd.)
50 parts were blended and extruded into pellets using a single-stage vented extruder. This pelletized product was molded using an injection molding machine, and its physical properties were measured and are shown in Table 1.

Comparative Example-1 Same as Example-1 except that all the reverse screws were removed and replaced with forward screws.

Comparative Example-2 A reverse screw was added to the screw configuration of Example-1 at 2 of the tip barrel.
Everything is the same as in implementation-1 except that it is added at the front.

Comparative Example-3 Same as Example-1 except that Q/N5=0.7.

Comparative Example-4 Same as Example-1 except that Q/N S =0.35.

Example-2 25% N-cyclohexylmaleimide obtained by suspension polymerization in water, 65% styrene, 10% methyl methacrylate
A suspension of a copolymer consisting of (copolymer content 50%)
was dehydrated under the same conditions as in Example 1 to obtain an N-cyclohexylmaleimide-styrene-methyl methacrylate copolymer thermoplastic resin. The water content of the resulting resin is 0
．． 03%, and the molecular weight of the resin was 145,000.

Comparative Example-5 The suspension of the copolymer obtained in Example-2 was dehydrated under the same conditions as in Comparative Example-1 to obtain a thermoplastic resin.

Comparative Example-6 The suspension (of the copolymer obtained in Example-2) was mixed into Comparative Example-2.
A thermoplastic resin was obtained by dehydration under the same conditions as .

Comparative Example-7 The suspension (of the copolymer obtained in Example-2) was added to Comparative Example-3.
A thermoplastic resin was obtained by dehydration under the same conditions as .

Comparative Example-8 The suspension of the copolymer obtained in Example-2 was dehydrated under the same conditions as in Comparative Example-4 to obtain a thermoplastic resin.

The thermoplastic resins having imide groups obtained in Example 1 and Comparative Examples 6 and 7 were molded using an injection molding machine, and their physical properties were measured and shown in Table 2.

From Tables 1 and 2, when using thermoplastic resins having imide groups obtained by the production method of the present invention, impact strength,
A resin with a much better balance of heat resistance and moldability than the comparative example can be obtained. The physical properties were measured by the following method.

(1) Amount of residual solvent: The amount of residual solvent in the belent compound is:
It was measured by gas chromatography (Hitachi 263-80).

(2) Molecular weight: The molecular weight was measured by gel permeation chromatography (HLC-802A manufactured by Toyo Soda).

(3) Heat resistant VSP (Vicat softening point> ,,,,,
.

Load 5kg, ASTM D-152 According to 3.

(4) Impact strength 009. Notched Izont impact strength, according to ASTM D-256.

(5) Molding defect rate 1. The ratio of molded products that have no commercial value due to flash (silver streaks) or cracks to all molded products.

[Brief explanation of the drawing]

The drawings are diagrams for explaining normal threads and reverse threads.

Claims (1)

[Claims] 0 to 20% by weight of a rubbery polymer, 30 to 80% by weight of aromatic vinyl monomer residues, 20 to 60% by weight of unsaturated dicarboxylic acid imide derivative residues, and other vinyl monomers. residues 0-20
A copolymer solution, aqueous suspension, or aqueous emulsion containing % by weight is introduced into a co-rotating twin-screw extruder with a multi-stage vent, in which the number of counterclockwise screws in each screw is 1 or 2, and the polymer output amount is (
kg/Hr)/screw rotation speed (rpm)=Q/NS
(kg/Hr・rpm) is [Screw diameter (mm)/57 (mm)]^3×0.1
5≦Q/NS≦[Screw diameter (mm)/57 (mm)
] A method for producing a thermoplastic resin having an imide group, which comprises operating the extruder in the range of ^3 x 0.3.