JPS63182309A - Production of thermoplastic heat-resistant resin - Google Patents

Abstract

PURPOSE:To obtain the title resin excellent in heat resistance, weathering resistance and impact resistance, by suspension-polymerizing a mixture comprising specified proportions of an aromatic vinyl monomer, vinyl cyanide monomer, a maleimide monomer and a copolymerizable monomer. CONSTITUTION:3-97wt.% aromatic vinyl monomer (A) at least partially consisting of styrene is mixed with 0-35wt.% vinyl cyanide monomer (B) (e.g., acrylonitrile), 3-50wt.% maleimide monomer (C) (e.g., N-methylmaleimide) and 0-3wt.% monomer (D) copolymerizable therewith (e.g., methyl metacrylate) so that the molar ratio of component C to styrene may be 1:1-1:5, and the resulting mixture is suspension-polymerized at 40-140 deg.C for 4-20hr in the presence of a suspending agent (e.g., PVA), a dispersion aid (e.g., polyoxyethylenemonostearyl) and a polymerization initiator (e.g., t-butylperoxy 2-ethylhexanoate).

Description

Detailed Description of the Invention [Field of Application in Industry A] The present invention relates to a method for producing a thermoplastic heat-resistant resin, and in particular to a method for producing a thermoplastic heat-resistant resin, in particular, by introducing a maleimide monomer into an aromatic vinyl monomer etc. This invention relates to an industrially advantageous method for producing thermoplastic resins with excellent heat resistance, impact resistance, etc. by legally synthesizing copolymers.

[Prior Art] In recent years, molding materials with high heat resistance and excellent moldability have been required in various fields, and copolymers containing α-methylstyrene as a main component have been developed as heat-resistant materials. Proposed.

Conventionally, copolymers whose main component is α-methylstyrene are
Generally, it is synthesized by emulsion polymerization method or suspension polymerization method.

[Problems to be Solved by the Invention] However, when a copolymer containing α-methylstyrene as a main component is synthesized by an emulsion polymerization method, as a matter of course, the glass transition point ( Powder granulation is difficult due to the high Tg), and moreover, the emulsifier used during emulsion polymerization and the granulating agent used during the granulation process remain in the heat-resistant copolymer mainly composed of α-methylstyrene. Therefore, when the copolymer obtained by such a method is blended with ABS resin, AES resin, AAS resin, etc. and molded, it will be difficult to mold the copolymer due to the influence of residual emulsifier and residual granulating agent during molding at a high temperature of 280°C or higher. , silver streaks may occur, or heat discoloration may occur.

On the other hand, when a copolymer mainly composed of α-methylstyrene is synthesized by a suspension polymerization method, the above-mentioned problems such as silver streaks and thermal coloring are greatly improved;
- Since methylstyrene has poor reactivity, it takes a long time to polymerize the copolymer, resulting in poor productivity. In this case, in order to improve the polymerization yield of the copolymer and shorten the polymerization time, it is necessary to perform the polymerization at a high temperature and at a high addition ratio of the initiator. However, when a copolymer containing α-methylstyrene as a main component is polymerized at high temperature and with the addition of a large amount of initiator, it becomes difficult to adjust the molecular weight, and low molecular weight products are produced, resulting in the copolymer There is a problem in that the heat resistance and impact resistance of the combination are reduced.

[Means for Solving the Problems] The present invention solves the problems in synthesizing the above-mentioned copolymer mainly composed of α-methylstyrene, and makes it possible to industrially produce styrenic resins with excellent heat resistance etc. The present invention provides an advantageous method for producing aromatic vinyl monomers from 3 to 97% by weight, vinyl cyanide monomers from 0 to 35% by weight, and maleimide monomers from 3 to 50% by weight. and 0 to 30% by weight of a vinyl monomer copolymerizable with these (however, the total amount of the above monomers is ioo% by weight) to produce a thermoplastic heat-resistant resin, A thermoplastic characterized by using styrene as at least a part of the aromatic vinyl monomer and blending the maleimide monomer and styrene in a molar ratio of 1:1 to 1:5. The gist of this paper is a method for producing heat-resistant resin.

That is, as a result of intensive studies to solve the above-mentioned conventional problems, the present inventors introduced a maleimide monomer into a styrene resin and synthesized a copolymer using a suspension polymerization method. It has been found that productivity and low molecular weight product production can be significantly improved. However, when trying to synthesize a copolymer containing maleimide monomers by suspension polymerization, as the composition ratio of maleimide monomers increases, the suspension polymerization system becomes unstable and the system becomes unstable. Polymerization-
Or, even if they do not coalesce, the diameters of the beads become uneven and aggregation occurs, which greatly impedes stability and productivity.

In view of these circumstances, the present inventors conducted further research and found that when synthesizing a heat-resistant copolymer using a maleimide monomer as an essential component by a suspension polymerization method, the maleimide monomer and By setting the molar ratio of styrene selected from aromatic vinyl monomers to 1=1 to 1:5, we not only aim for the stability of the maleimide monomer in the suspension polymerization system, but also The disadvantages of heat-resistant copolymers mainly composed of aromatic vinyl monomers such as α-methylstyrene include suppression of low molecular weight formation, significant shortening of polymerization time, thermal discoloration during molding, and silver streaks. The present invention has been completed by discovering that the present invention has excellent effects such as suppressing the amount of gas, solves all the conventional problems, and can be manufactured with industrial advantage.

The present invention will be explained in detail below.

In the method of the present invention, aromatic vinyl monomers 3 to 9
7% by weight, vinyl cyanide monomer O~35r! i amount%
, 3 to 50% by weight of a maleimide monomer and O to 3011% by weight of a vinyl monomer copolymerizable with these monomers (however, the total amount of the above monomers is 100% by weight) are subjected to suspension polymerization. At this time, styrene is used as at least a part of the aromatic vinyl monomer, and the maleimide monomer and the styrene are blended in a molar ratio of 1=1 to 1:5 for suspension polymerization.

In the polymerization reaction of the present invention, aromatic vinyl monomers other than styrene used as raw materials include α-methylstyrene, t-butylstyrene, p-methylstyrene, chlorostyrene, and bromustyrene. Examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile. Examples of maleimide monomers include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, and the like. Can be mentioned.

In addition, vinyl monomers that can be copolymerized with these include:
Examples include methyl methacrylate, methyl acrylate, isopropyl fumarate, and the like.

The blending amount of each of the above monomers is 3 to 9 aromatic vinyl monomers.
7% by weight, 0 to 35% by weight of vinyl cyanide monomer, 3 to 50% by weight of maleimide monomer, and 0 to 30% by weight of vinyl monomer copolymerizable with these monomers. The total amount of polymers is 100% by weight, that is, the total amount of monomers other than maleimide monomers is 50 to 97% by weight.

Among these monomers, if the amount of maleimide monomer used is less than 3% by weight, sufficient heat resistance will not be imparted to the resulting copolymer, and if it exceeds 50% by weight, the resulting copolymer will not have sufficient heat resistance. Such copolymers are undesirable because they reduce moldability and impact resistance. The preferred amount of maleimide monomer used is 5 to 30% by weight.

In the present invention, the molar ratio of the maleimide monomer to styrene as the aromatic vinyl monomer in the suspension polymerization system is 1:1 to 1:5, preferably 1:1 to 1:3. Its major feature is that it polymerizes. If the molar ratio of maleimide monomer to styrene is less than 1=1, the suspension polymerization system will become unstable, and the polymerization system may wash out, leading to serious situations such as runaway reactions. . On the other hand, if this molar ratio exceeds 1=5, this is not preferable because it causes a decrease in the heat resistance of the resulting copolymer.

The suspension polymerization reaction of the present invention is produced using the above monomer as a raw material, and the present invention is preferably carried out by the following method.

That is, the monomer, dispersant, and dispersion aid are charged into a reaction tank, an appropriate polymerization initiator is added at the same time, and the mixture is heated at a temperature of 40 to 140° C. for 4 to 20 hours with stirring at 350 rpm. Polymerization is carried out by After the reaction is completed, the resulting slurry polymer is treated to dissolve the dispersant by adding IN dilute sulfuric acid, followed by thorough dehydration, washing, and drying to obtain the desired maleimide copolymer.

In the present invention, any commonly used dispersing agents and dispersing aids can be effectively used as the suspending dispersing agent and dispersing aid. Examples of the suspending and dispersing agent include polyvinyl alcohol, partially saponified polymethyl methacrylate, hydrophilic polymer compounds such as polyacrylamide, calcium phosphate compounds, calcium carbonate compounds, kaolin, talc, etc.
Among these, when calcium phosphate compounds are used as dispersants, fatty acid soaps such as sodium oleate and sodium stearate, anionic surfactants such as sodium dodecylbenzenesulfonate and sodium dodecylsulfonate, and polyoxyethylene It is preferable to use a nonionic surfactant such as monostearyl or polyoxyethylene monooleyl ester as a dispersion aid.

On the other hand, as a polymerization initiator for synthesizing a copolymer, t-butylperoxy-2-
Peroxy esters such as ethylhexanoate and t-butyl peroxybenzoate, diacyl peroxides such as lauroyl peroxide and octanoyl peroxide, 1.1-bis(t-butylperoxy)-
Examples include peroxyketals such as 3,3,5-trimethylcyclohexane and 2,2-bis(t-butylperoxy)butane. In addition, as azo compounds,
2-t-butylazo-2-cyano-4-methylpentane, 2-t-butylazo-2,2-cyanopropane, 2-
Examples include t-butylazo-2-cyanobutane,
It is not limited to these.

The copolymer produced by the present invention has high heat resistance,
It is resistant to discoloration and thermal decomposition during high-temperature molding, and also has excellent impact resistance. Such a copolymer obtained by the present invention may be used alone, but such copolymer and ABS resin, AES resin, AAS resin and P
V.C., P.C.

By blending with nylon, etc., it is possible to create a resin composition with excellent heat resistance, weather resistance, impact resistance, low water absorption, etc., and it can be used in various fields such as automobile parts, electrical equipment parts, and building materials. It is extremely effective in

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

In addition, in the following, "1 part" means "part by weight" and "%"
” indicates “% by weight”, respectively.

The evaluation method for each side is as follows.

■ Suspension polymerization stability: Presence or absence of embedding in the polymerization system and one hour of polymerization (if embedding is present) ■ Thermal stability and physical property test 30 parts by weight of the copolymer particles obtained on each side were 70 parts by weight of the ABS copolymer produced by the method shown in Production Example 1 above was blended, kneaded in a Banbury mixer, and pelletized. This pellet was molded using a 202 horizontal injection molding machine under the following conditions to prepare a test piece.

[Conditions] Cylinder temperature 280℃ (setting) Injection speed
10 seconds Mold temperature 50℃ Molding cycle 30 seconds [Test piece] A: 1" x 81 x 1/8" (flat plate) B: 4" x
1/2" x 1/2" (flat plate) C: 2.5" x
The obtained molded product (1/2" x 1/8" (flat plate)) was evaluated according to the following evaluation criteria.

■ Silver Streaks (Test Piece A) All over the molded product × Partial occurrence Δ No occurrence ○ ■ Thermal coloring (visual judgment) (Test Piece A) Almost no change 0 Slight change Δ Change × ■ Heat resistance: Heat deformation Temperature (test piece B) ASTM
(D648) 18.6kg/C load test piece width 1
/21 ■ Endurance? fI Impact (Test Piece C) ASTM (D256) Notched Izot (kg-cm/cm) Measurement Temperature 23
℃ ■ Water Absorption (Test Piece C) Discoloration after 60 minutes in boiling water (almost no change) O - Slight change △ Changed × Production Example 1 An ABS copolymer was synthesized using the emulsion polymerization method using the following formulation. did.

[Formulation] Styrene (ST) 35 parts Acrylonitrile (AN) 15 parts PB=D (average particle size 3000A) 50 parts disproportionated potassium rosinate
1 part potassium hydroxide 0.03 parts tertiary dodecyl mercaptan (t-DM) 0.1 part cumene hydroperoxide 0.3 parts ferrous sulfate
0.007 parts sodium birophosphate
0.1 part Crystal Grape II O
, 3 parts Distilled water 190 parts Distilled water, disproportionated potassium rosin acid, potassium hydroxide and PB-D were placed in an autoclave, and after heating to 60°C, ferrous sulfate, sodium birophosphate and crystalline glucose were added,
While maintaining the temperature at 60°C, ST, AN% t-DM, cumenha, and hydroba-oxide were continuously added over 2 hours, and then the temperature was raised to 70°C and maintained for 1 hour to complete the reaction. An antioxidant was added to the ABS latex obtained by this reaction, which was then coagulated with sulfuric acid, thoroughly washed with water, and dried to obtain an ABS powder.

Example 1 The interior of a 20JZ autoclave equipped with a stirrer was sufficiently purged with N2, and raw materials were charged in the proportions shown in Table 1 (the molar ratio of N-phenylmaleimide and styrene was 1:1).

After keeping the inside of the autoclave under stirring at 35 rpm for 5 hours, the internal temperature was raised to 80°C to start polymerization, and 1
After maintaining this temperature for 2 hours, the temperature was raised to 120° C. over 2 hours, and the reaction was completed after 30 minutes. In addition, in this reaction, the polymerization system did not wash or the formation of II beads did not occur.

After adding IN dilute sulfuric acid to the obtained slurry polymer and dissolving the calcium phosphate, it was thoroughly washed and dehydrated and dried in a hot air dryer to obtain a copolymer with a particle size of 150 μm, which is the thermoplastic heat-resistant resin of the present invention. I got it.

Table 2 shows the results of various evaluation tests.

Example 2 Example except that the raw material composition was as shown in Table 1 (N-phenylmaleimide: styrene =!:1) and the time to start heating up to 120°C was 3 hours earlier and the reaction was completed in 12 hours. Polymerization was carried out in the same manner as in 1. In addition, in this reaction, the polymerization system did not wash out or the formation of aggregated beads did not occur.

Next, copolymer beads were produced in the same manner as in Example 1. The particle size of the beads obtained was 160 μm, and the particle size of the beads was 160 μm.
It was a little more yellowish than the original.

Table 2 shows the results of various evaluation tests.

Example 3 Example except that the raw material composition was as shown in Table 1 (N-phenylmaleimide: styrene = 1:1), and the time to start heating up to 120°C was 5 hours earlier and the reaction was completed in 10 hours. Polymerization was carried out in the same manner as in 1. In addition, in this reaction, the polymerization system did not wash out or the formation of aggregated beads did not occur.

Next, copolymer beads were produced in the same manner as in Example 1. The particle size of the beads obtained was 190 μm, and the particle size of the beads was 190 μm.
It was a little more yellowish than the original.

Table 2 shows the results of various evaluation tests.

Example 4 Example except that the raw material composition was as shown in Table 1 (N-phenylmaleimide: styrene-1=1) and the time to start heating up to 120°C was advanced by 7 hours and the reaction was completed in 8 hours. Polymerization was carried out in the same manner as in 1. In addition, in this reaction, the polymerization system did not wash out or the formation of aggregated beads did not occur.

Next, copolymer beads were produced in the same manner as in Example 1. The particle size of the obtained beads was 200 μm, and the particle size of the beads was 200 μm.
It was a little more yellowish than the original.

Table 2 shows the results of various evaluation tests.

Example 5 Example except that the raw material composition was as shown in Table 1 (N-phenylmaleimide: styrene - 1:2) and the time to start heating up to 120°C was advanced by 3 hours and the reaction was completed in 7 hours. Polymerization was carried out in the same manner as in 3. In addition, in this reaction, the polymerization system did not wash out or the formation of aggregated beads did not occur.

Next, copolymer beads were produced in the same manner as in Example 1. The particle size of the beads obtained was 160 μm, and the diameter of the beads was 160 μm.
It was slightly smaller than the one.

Table 2 shows the results of various evaluation tests.

Example 6 Example except that the raw material composition was as shown in Table 1 (N-phenylmaleimide: styrene = 1:3) and the time to start heating up to 120°C was advanced by 6 hours and the reaction was completed in 4 hours. Polymerization was carried out in the same manner as in 3. In addition, in this reaction, the polymerization system did not wash out or the formation of aggregated beads did not occur.

Next, copolymer beads were produced in the same manner as in Example 1. The particle size of the beads obtained was 160 μm, and the diameter of the beads was 160 μm.
It was slightly smaller than the one.

Table 2 shows the results of various evaluation tests.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1, except that the raw materials were mixed as shown in Table 1 (N-phenylmaleimide: styrene = 1:0). As a result, the polymerization system was washed 8 hours after the start of polymerization, so the polymerization was stopped urgently.

In Example 1, extremely good polymerization stability was shown, but it was found that the polymerization system was washable when the monomer composition did not contain styrene. In this example, since the copolymer was washed, further evaluation was discontinued.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that the raw materials were mixed as shown in Table 1 (N-phenylmaleimide: styrene = 1:0.5). As a result, the polymerization system was washed out 9 hours after the start of polymerization, so the polymerization was stopped urgently.

Example 1 showed extremely good polymerization stability, but when the molar ratio of N-phenylmaleimide and styrene was 1:
It was found that a monomer composition of less than 1 caused the polymerization system to wash. In this example, the copolymer washed, so further evaluation was discontinued.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 2, except that the raw materials were mixed as shown in Table 1 (N-phenylmaleimide:styrene-1:O). As a result, the polymerization system was flushed 3 hours after the start of polymerization, so the polymerization was stopped urgently.

In Example 2, extremely good polymerization stability was shown, but it was found that the polymerization system was washable when the monomer composition did not contain styrene. In this example, since the copolymer was washed, further evaluation was discontinued.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 2, except that the raw materials were mixed as shown in Table 1 (N-phenylmaleimide: styrene-tit) and the amount of acrylonitrile was increased.

The reaction was completed in 12 hours. In addition, in this reaction, the polymerization system did not wash out or the formation of aggregated beads did not occur.

Next, copolymer beads were produced in the same manner as in Example 2.

The bead particle size of the obtained copolymer was 170 μm and was considerably yellower than that of Example 2.

Table 2 shows the results of various evaluation tests.

As is clear from the results in Table 2, the copolymer of this example exhibits extremely large thermal coloring during molding.

Comparative Example 5 Example except that the raw material composition was as shown in Table 1 (N-phenylmaleimide and styrene were not used), the start time of heating to 120°C was delayed by 7 hours, and the reaction was completed in 22 hours. Polymerization was carried out in the same manner as in 1. In addition, in this reaction, the polymerization system did not wash out or agglomerated beads were generated.

Next, copolymer beads were produced in the same manner as in Example 1. The particle size of the beads obtained was 160 μm, and the particle size of the beads was 160 μm.
It had a slightly less yellow tinge than that of .

Table 2 shows the results of various evaluation tests.

Comparative example 6 Emulsion polymerization was carried out using the raw material formulations shown in Table 1.

First, distilled water, sodium alkylbenzenesulfonate, potassium persulfate, and potassium chloride were placed in an autoclave, and the temperature was maintained at 72°C with stirring at 350 rpm.
, AMS, and t-DM were added continuously over 4 hours, and then the temperature was raised to 80°C and maintained for 2 hours to complete the reaction.

The emulsified latex obtained by this reaction was coagulated with calcium chloride, thoroughly washed with water, and then dried to obtain a powder.

Table 2 shows the results of various evaluation tests.

From Table 2, it is clear that according to the present invention, the polymerization reaction can be carried out in a short time with good stability of the polymerization system, and the resulting copolymer has extremely excellent properties.

[Effects of the Invention] As detailed above, according to the method for producing a thermoplastic heat-resistant resin of the present invention, the stability of the polymerization system is significantly improved, the reaction time is significantly shortened, and productivity is improved. Therefore, the maleimide copolymer obtained by the present invention suppresses the generation of silver streaks during high temperature molding, has excellent thermal coloring properties, and also has excellent heat resistance, impact resistance, low water absorption, etc. It becomes a thermoplastic resin.

The maleimide copolymer obtained by the present invention can be used alone, blended with ABS resin,
S @ fat, AAS resin, pvc,.

By blending with PC, nylon, etc., it can be widely used in various applications, and is extremely useful industrially.

Claims (1)

[Claims] (1) Aromatic vinyl monomer 3 to 97% by weight, vinyl cyanide monomer 0 to 35% by weight, maleimide monomer 3
-50% by weight and 0-30% by weight of vinyl monomers copolymerizable with these (however, the total amount of the above monomers is 100% by weight)
% by weight) to produce a thermoplastic heat-resistant resin, styrene is used as at least a part of the aromatic vinyl monomer, and the molar ratio of the maleimide monomer to styrene is 1: A method for producing a thermoplastic heat-resistant resin, characterized by blending the resins in a ratio of 1 to 1:5.