JPH08127626A - High-nitrile vinylic copolymer and its production - Google Patents

Abstract

PURPOSE: To obtain a high-nitrile vinylic copolymer in which a sequence ratio of a vinyl cyanide monomer is a specific value or below, excellent in heat discoloration stability in melting, having good chemical resistance and useful as a resin material for electric refrigerators. CONSTITUTION: When a monomer component comprising (A) 25-55wt.%, preferably 30-45wt.% of a vinyl cyanide-based monomer, (B) 75-45wt.%, preferably 70-55wt.% of an aromatic vinylic monomer and 0-20wt.% of other vinylic monomer copolymerizable with these components is polymerized, the monomer component is subjected to an aqueous suspension polymerization so that a ratio of the component A in residual monomer is kept to <=95wt.% from start of polymerization to the finish and a ratio of the component A in the residual monomer from start of the polymerization to the point of time when polymerization ratio attain at least 107wt.% is kept to 70-95wt.% to provide the objective copolymer having 10wt.%, preferably <=8wt.% ratio of three series of sequences of the component A e.g. a segment of the formula [R is H or CmHn; (m, n): (1,3)]}, 0.20-0.80dl/g reduced viscosity and <=0.6wt.% ratio of oligomers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high nitrile content vinyl copolymer having excellent thermal coloring stability during melting and good chemical resistance, and a method for producing the same.

[0002]

2. Description of the Related Art Acrylonitrile-butadiene-styrene copolymer resin (ABS resin) has impact resistance, chemical resistance,
It has an excellent balance of molding processability and is widely used as a molding resin. For example, in the case of materials for electric refrigerators, foamed polyurethane is used for the heat insulation layer of the electric refrigerator, and CFC is used as the foaming agent. Therefore, the resin material used in the vicinity of the heat insulating layer is required to have a property not to be attacked by CFC, and ABS resin is often used.

By the way, in recent years, under the regulation of CFC concerning environmental problems, CFC 141b (alternative CFC) is being used as the above-mentioned foaming agent. Since this alternative CFC has a stronger erosion force than conventional CFC, the conventional ABS resin lacks durability, and the resin material used in the vicinity of the heat insulation layer is required to have higher chemical resistance than before. .

Therefore, as a means for improving the chemical resistance of the ABS resin, it is known to increase the content ratio of the vinyl cyanide monomer component in the resin composition, and particularly ABS.
Regarding the acrylonitrile-styrene copolymer, which is the matrix component of the resin, etc., there have been proposed some so-called high nitrile-containing vinyl copolymers in which the content ratio of vinyl cyanide-based monomer components is increased, and a method for producing the same. .

For example, a method of uniformly controlling the composition ratio of the copolymer (Japanese Patent Publication No. 46-27808) to improve chemical resistance and mechanical properties, and chemical resistance,
And in order to obtain a high nitrile-containing vinyl copolymer having an excellent softening point, two specific polymerization initiators are used in combination, and a calculated amount of styrene is continuously added at a relatively high temperature (80 to 100 ° C.), A method of gradually raising the temperature of the polymerization system (Japanese Patent Publication No.
No. 33917), a method of stripping an unreacted monomer containing an unsaturated nitrile monomer as a main component to obtain a high nitrile-containing vinyl copolymer having a small amount of unreacted monomer (Japanese Patent Laid-Open No. 3-227306). )and so on.

However, in the above-mentioned conventional formulation,
By increasing the content ratio of vinyl cyanide-based monomer component in the resin composition, it is possible to obtain a high nitrile content vinyl-based copolymer that has excellent chemical resistance to some extent, but the initial color tone of the resin molded product The egg yolks became stronger and the quality deteriorated. Therefore, a high nitrile-containing vinyl copolymer excellent in both chemical resistance and thermal coloring stability at the time of melting has not yet been obtained, and the impact resistance, chemical resistance, required as a material for electric refrigerators, The present situation is that a resin material that has an excellent balance of molding processability and that sufficiently satisfies the thermal coloring stability during melting has not yet been obtained.

[0007]

Therefore, the present invention is excellent in such a balance of impact resistance, chemical resistance and molding processability, and sufficiently satisfies the thermal coloring stability at the time of melting, and is of high quality ABS. It is an object of the present invention to provide a method for producing a novel high nitrile content vinyl-based copolymer from which a resin is obtained. The present inventors have increased the content ratio of the vinyl cyanide-based monomer component to achieve such an object, so-called high nitrile content vinyl-based copolymer of chemical resistance and thermal coloring stability at the time of melting. As a result of diligent studies on compatibility, a vinyl copolymer with a high nitrile content in which the ratio of triple sequences of vinyl cyanide-based monomers is less than a certain value retains high chemical resistance and is stable in thermal coloring during melting. I found that is good. Further, it was found that this novel high nitrile-containing vinyl-based copolymer can be produced by controlling the ratio of the vinyl cyanide-based monomer component in the residual monomer and carrying out the polymerization, Arrived

[0008]

That is, the present invention is as follows.
(1) 25 to 55% by weight of a vinyl cyanide-based monomer, 75 to 45% by weight of an aromatic vinyl-based monomer, and 0 to 20% by weight of another vinyl-based monomer copolymerizable therewith. Which is a copolymer of vinyl cyanide-based monomer
2. The high nitrile content vinyl copolymer according to claim 1, wherein the proportion of the continuous sequence is 10% by weight or less in the copolymer, wherein (2) vinyl cyanide monomer 2
5-55% by weight, aromatic vinyl-based monomer 75-45% by weight and other vinyl-based monomer copolymerizable with these 0-
When polymerizing a monomer consisting of 20% by weight, the ratio of vinyl cyanide-based monomer component in the residual monomer from the start of polymerization to the end of polymerization is 95% by weight or less, and the polymerization rate is at least 10 from the start of polymerization. % Of the vinyl cyanide-based monomer component in the residual monomer up to the point of time of 70% by weight or more and 95% by weight or less to carry out the aqueous suspension polymerization of the high nitrile-containing vinyl-based copolymer. The present invention relates to a manufacturing method.

In the present invention, the constituent units of the monomer component of the high nitrile content vinyl copolymer are 25 to 55% by weight of the vinyl cyanide monomer and 75 to 75 of the aromatic vinyl monomer.
It should be 45% by weight. It is preferable that the vinyl cyanide monomer content is in the range of 30 to 45% by weight and the aromatic vinyl monomer content in the range of 70 to 55% by weight. If the copolymerization amount of the vinyl cyanide-based monomer is less than 25% by weight, the chemical resistance of the resin composition using the obtained copolymer is insufficient, and if it exceeds 55% by weight, it is obtained. Both the molding processability and the thermal coloration stability during melting of the resin composition using the copolymer are significantly reduced. Further, if necessary, other vinyl-based copolymerizable monomer can be used as a constituent component,
It is preferably 0 to 20% by weight. If it exceeds 20% by weight, it becomes difficult to maintain the chemical resistance of the resin composition using the obtained copolymer.

Examples of the vinyl cyanide-based monomer used in the high nitrile content vinyl-based copolymer of the present invention include acrylonitrile and methacrylonitrile.
One or more kinds can be used. Acrylonitrile is particularly preferred. Examples of the aromatic vinyl-based monomer include styrene, α-methylstyrene, orthomethylstyrene, paramethylstyrene, para-t-butylstyrene and halogenated styrene, and one or more of them may be used. it can. Styrene and α-methylstyrene are particularly preferable, and styrene is more preferable. Other vinyl monomers include unsaturated carboxylic acids such as acrylic acid and methacrylic acid; (meth) acrylic acid esters such as methyl acrylate, methyl methacrylate and butyl acrylate; acrylamide, methacrylamide, N- (Meth) acrylamides such as methylacrylamide and maleimide, N-methylmaleimide, N
Maleimides such as phenylmaleimide; unsaturated carboxylic acid anhydrides such as maleic anhydride, citraconic anhydride, and aconitic anhydride.

The triple sequence of vinyl cyanide-based monomers in the high nitrile content vinyl-based copolymer of the present invention means a segment in the copolymer represented by the following (formula 1). Yes,

Embedded image In the molten state of the copolymer at about 200 ° C., the intramolecular cyclization reaction represented by the following (Formula 2) proceeds and the color changes.

[0012]

Embedded image The high nitrile-containing vinyl-based copolymer of the present invention has a small proportion of the triple sequence of vinyl cyanide-based monomers that inhibit the thermal coloring stability of 10% by weight or less, so that the thermal coloring stability during melting is high. It has excellent properties. More preferably, it is less than 8% by weight. If the weight exceeds 10% by weight, the thermal coloring stability at the time of melting is deteriorated, which is not preferable. The novel high nitrile content vinyl copolymer in which the ratio of the triple sequence of vinyl cyanide monomer in the copolymer is controlled to 10% by weight or less is a cyanide in the residual monomer. It can be produced by controlling the proportion of the vinyl-based monomer component to carry out polymerization.

Further, the reduced viscosity (ηsp / c) of the high nitrile content vinyl copolymer of the present invention is in order to further improve the chemical resistance of the resin composition using the obtained copolymer,
It is preferably 0.20 or more, and more preferably 0.40 or more. Further, in order to further improve the molding processability of the resin composition using the obtained copolymer, 0.8
It is 0 dl / g or less, more preferably 0.70 dl / g or less. The reduced viscosity can be controlled by the amount of chain transfer agent, the amount of initiator, and the polymerization temperature.

Here, the reduced viscosity (ηsp / c) is 50 ml of methyl ethyl ketone based on the high nitrile content vinyl copolymer.
It is a value calculated by the following formula (3) after 0.20 g was dissolved in and the flow-down time was measured at 30 ° C. using a viscosity tube.

Reduced viscosity (ηsp / c) = [(t1 / t0) -1] / C (Equation 3) In the formula, t1: Flow time in sample solution (sec) t0: Flow time of blank solution (sec) C: Resin concentration of measurement sample (g / 100 ml) The amount of the oligomer in the high nitrile content vinyl-based copolymer of the present invention is 0.6% by weight or less in order to reduce mold stain during molding. Preferably there is. This is realized by using the aqueous suspension polymerization method for the production method.

The method for producing the high nitrile content vinyl copolymer of the present invention will be described below. A water-based suspension polymerization is required as a polymerization method for obtaining the high nitrile-containing vinyl copolymer of the present invention. With a polymerization method other than the aqueous suspension polymerization, it is difficult to control the ratio of the vinyl cyanide-based monomer component in the residual monomer, and the ratio of the oligomer cannot be reduced to 0.6% by weight or less. Further, auxiliary materials such as an emulsifier and a solvent remarkably deteriorate the thermal coloring stability during melting.

Examples of the suspension stabilizer used in the above polymerization include inorganic suspension stabilizers such as clay, barium sulfate and magnesium hydroxide, polyvinyl alcohol, carboxymethyl cellulose, polyacrylamide, methyl methacrylate / acrylamide copolymer and the like. And the like. Among them, the organic suspension stabilizer is preferable, and among them, the organic suspension stabilizer is preferable from the viewpoint of thermal coloring stability when the copolymer melts, and more preferably a methyl methacrylate / acrylamide copolymer.

The total amount of water used as the dispersion medium for 100 parts by weight of the total amount of the monomers used in the above-mentioned polymerization is such that good dispersibility of the monomer in water is maintained and a large amount of the vinyl cyanide-based monomer is dissolved in water. From the viewpoint of preventing migration, it is preferable to select from the range of 80 to 350 parts by weight. From the viewpoint of controlling the ratio of the vinyl cyanide-based monomer component in the residual monomer, it is preferably 100 to 200 parts by weight.

The polymerization temperature for obtaining the high nitrile content vinyl copolymer of the present invention is 30 to 160 ° C., preferably 50 to 120 ° C., depending on the monomer species, the initiator species and the chain transfer agent species.
You can choose from the range.

Examples of the polymerization initiator used in the above polymerization include azonitriles such as 2,2'-azobis (2,4-dimethylvaleronitrile) and 2,2'-azobis (2,4,4-trimethylvaleronitrile). Compound and t-butylperoxide, t-butylperoxyneodecanate, t-butylperoxyneosexanoate, t-
Examples thereof include organic peroxides such as butylperoxypivalate, and these can be used alone or in combination of two or more, and among them, an azonitrile compound is particularly preferable.

The chain transfer agent used here is n
-Octyl mercaptan, t-dodecyl mercaptan,
Examples thereof include alkyl mercaptans such as n-dodecyl mercaptan. These chain transfer agents can be used alone or in combination of two or more. The method of use may be any of batch addition, divisional addition, and continuous addition.

In order to obtain the high nitrile content vinyl copolymer of the present invention, the ratio of the vinyl cyanide monomer component in the residual monomer in the polymerization system from the start of polymerization to the end of the polymerization is 95.
% Or less, and at least a polymerization rate of 1 from the start of polymerization
It is necessary that the proportion of vinyl cyanide-based monomer component in the residual monomer before the lapse of 0% is 70% by weight or more and 95% by weight or less. If it exceeds 95%, the proportion of the triple sequence of the vinyl cyanide-based monomer in the copolymer cannot be reduced to 10% by weight or less.

From the start of polymerization, at least a polymerization rate of 10%
If the ratio of the vinyl cyanide-based monomer component in the residual monomer up to the point of time is 70% by weight or less, it becomes difficult to maintain the chemical resistance of the resin composition using the obtained copolymer. Become. This is because the chemical resistance, which is an advantage of the high nitrile content vinyl-based copolymer of the present invention, is a polymerization rate of 10 from the initiation of polymerization.
% High nitrile copolymer component having a high vinyl cyanide monomer content, which is produced by keeping the proportion of vinyl cyanide monomer in the residual monomer up to 70% by weight. It is because it is expressed by. That is, when the vinyl cyanide-based monomer component ratio in the residual monomer is 70% by weight or less from the initiation of polymerization to the point of time when the conversion rate is 10%, the copolymerization ratio of the vinyl cyanide-based monomer content is low. This is because it does not contribute to the chemical resistance because it produces only coalescing components.

The high nitrile copolymer component described herein is
The high nitrile content vinyl copolymer of the present invention is a component re-precipitated by dropping cyclohexane after dissolving it in methyl ethyl ketone, and the ratio of vinyl cyanide monomer component of the precipitate can be quantified by FT-IR analysis. .

The proportion of the vinyl cyanide-based monomer component in the residual monomer is determined by the amount of the polymerization initiator, the addition of the polymerization inhibitor, the removal of the vinyl cyanide-based monomer from the polymerization system by stripping, or It can be controlled by adding a monomer other than the vinyl cyanide-based monomer component into the polymerization system during the polymerization.

[0026]

EXAMPLES In order to describe the present invention more specifically, examples and comparative examples will be described below, but these examples do not limit the present invention. Parts in Tables 1 to 3, FIG. 1, Examples and Comparative Examples, and% are parts by weight, respectively.
Represents% by weight.

The degree of yellowing (YI) was determined by placing 5 g of the high nitrile copolymer in an aluminum dish having a diameter of 50 mm so as to have a substantially uniform thickness, leaving it in a gear oven at 180 ° C. for 60 minutes, and then at 23 ° C. Let stand for 1 hour in an atmosphere of 50% relative humidity, and make a colorimetric color difference meter (ND-1 manufactured by Nippon Denshoku Industries Co., Ltd.).
The tristimulus values X, Y, and Z were measured using a (00 type) and calculated by the following formula 4.

Yellowing Degree (YI) = 100 (1.28X-1.06Z) Y (Equation 4) The reduced viscosity (ηsp / c) uses an Ubbelohde viscometer and the temperature of the water tank (measurement temperature) is 30 ±. It was calculated by the following formula 5 from the flowing time of the measurement sample which was adjusted to 0.1 ° C. and measured. However, in Formula 5, ts is the flow time of the measurement sample, t ₀ is the flow time of the measurement solvent, and C is the resin concentration (g / 100 ml) of the measurement sample. As a sample for measurement, 50 ml of precisely weighed resin of about 0.2 g was used.
・ A measuring flask was used, which was dissolved in methyl ethyl ketone as a measuring solvent. Reduced viscosity (ηsp / c) = [(ts / t ₀ ) -1] / C (Formula 5) The amount of unreacted monomers in the polymerization system and oligomers in the copolymer is gas chromatograph (manufactured by Shimadzu Corporation) GC-
14A type). The vinyl cyanide-based monomer copolymerization amount and the polymerization rate were calculated by the following equations 6 and 7.

Copolymerization amount of vinyl cyanide monomer (% by weight) = (total vinyl cyanide monomer-unreacted vinyl cyanide monomer) / (total charged monomer amount) × 100 (Formula 6) Polymerization Rate (%) = (amount of charged monomer-amount of unreacted monomer) / total amount of monomer × 100 (Formula 7) The ratio of the triple sequence of the vinyl cyanide-based monomer is ¹³
Utilizing the fact that the α-carbon signal shift of the vinyl cyanide-based monomer appearing in C-NMR slightly differs depending on the difference of the adjacent monomer species, the ratio of the triple sequence was quantified from the signal integral value. The measurement conditions are as follows.

Apparatus: JEOL JNM-GSX400 type Observation frequency: 100.5 MHz Solvent: DMSO-d ₆ concentration: 445 mg / 2.5 mL Chemical shift reference: Me ₄ Si temperature: 110 ° C. Observation width: 20000 Hz Data point: 32 K flip angle : 90 ° (21 μs) pulsedelaytime: 5.0 s Cumulative number of times: 7400 or 8400 Decoupling: gated decoupling (without NOE) The content ratio of the high nitrile copolymer component in the copolymer was quantified by the following method. 1 g of the copolymer is dissolved in 40 g of methyl ethyl ketone, and 20 g of cyclohexane is added dropwise thereto little by little. After stirring well at 50 ° C., the mixture was allowed to stand overnight at room temperature, further heated to 30 ° C. in a constant temperature bath, the precipitated copolymer component was centrifuged, and the content ratio was quantified from this dry weight.

The proportion of the vinyl cyanide-based monomer component in the high nitrile copolymer component was determined by the method described below.
The copolymer component which has been subjected to the processing described above, the heating press molding in a 30μm about a film-like, which from the ratio of the baseline level of absorbance peak occurring FT-IR analysis was 2260 cm ^-1 and 1600 cm ^-1 The ratio of vinyl cyanide-based monomer components was quantified using the calibration curve shown in Formula 8.

X = (R + 0.587444823) /0.07396422 (Formula 8) X: Vinyl cyanide-based monomer component ratio (wt%) R: Absorbance peak height ratio {= H (2260) / H (16
00)} The chemical resistance test and the melt flow rate were measured using a molding test piece and a pellet of the thermoplastic resin composition shown below, respectively.

Reference Example (Production of Graft Copolymer) In a reactor purged with nitrogen, 120 parts of pure water, 0.5 part of glucose, 0.5 part of sodium pyrophosphate, 0.005 part of ferrous sulfate and polybutadiene latex ( Rubber particle diameter 0.3 μm, gel content 85
%) 50 parts (in terms of solid content) were charged, and the temperature in the reactor was raised to 65 ° C. while stirring. When the internal temperature reached 65 ° C, the polymerization was started, and a mixture of a monomer (35 parts of styrene and 15 parts of acrylonitrile) and 0.3 part of t-dodecyl mercaptan was continuously added dropwise over 5 hours.
Cumene hydroperoxide 0.25 simultaneously in parallel
Part, 2.5 parts of potassium oleate and 25 parts of pure water were continuously added dropwise over 7 hours to complete the reaction. The resulting graft copolymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered and dried to obtain a powder-like graft copolymer. The graft ratio of this graft copolymer is 45%, and the resinous component ηsp / c is 0.68.
dl / g.

(Production of Thermoplastic Resin Composition) 73 parts by weight of the copolymers produced in the following Examples 1 to 10 and Comparative Examples 1 to 6, 27 parts by weight of the graft copolymer, and ethylenebisstearylamide 0 After kneading 8 parts by weight with a Henschel mixer, the extrusion temperature is 230 with a 40 mmφ extruder.
It was extruded into a gut at 0 ° C and pelletized. The obtained pellets are injection molded at a molding temperature of 230 ° C and a mold temperature of 40 ° C,
A test piece for evaluation was prepared. The chemical resistance test method is a UL test piece obtained by injection molding (a test piece dedicated to the US flammability standard evaluation, width: about 13 mm, length: about 126 mm, thickness: about 1.5 mm).
mm) at 30 ° C in DOP (dioctyl phthalate) 24
After immersing in hr, take out, depending on the condition of alteration of the test piece,
◎: No change, ○: Slightly absorbed, △: Blurred,
X: Visually judged to have significant blistering.

Melt flow rate (hereinafter abbreviated as MFR)
Is in accordance with JIS K 7210 (Japanese Industrial Standards: Thermoplastics Flow Test Method, Method B) at a temperature of 220.
It was carried out at a temperature of 10 ° C. and a load of 10 kgf.

Examples and comparative examples will be shown below. In addition,
Tables 1 and 2 show changes over time (in terms of polymerization rate) in the ratio of vinyl cyanide-based monomer components in the residual monomers from the start of polymerization to the completion of polymerization in Examples and Comparative Examples. It is a graph. In addition, various physical properties of the obtained copolymer and thermoplastic resin composition are summarized in Table 3, respectively.

Example 1 0.05 parts of methyl methacrylate / acrylamide copolymer (Japanese Examined Patent Publication No.
A solution prepared by dissolving 5-24151) in 165 parts of ion-exchanged water was stirred at 400 rpm, and the inside of the system was replaced with nitrogen gas. Then 42 parts of acrylonitrile, 4. O
Of styrene, 0.46 part of t-dodecyl mercaptan, 0.39 part of 2,2'-azobis (2,4-dimethylvaleronitrile), 0.05 part of 2,2'-azobisisobutylnitrile. The mixed solution was added while stirring the reaction system, and the copolymerization reaction was started at 58 ° C. After 15 minutes had passed from the initiation of polymerization, 54 parts of styrene was intermittently added over 110 minutes from a feed pump provided at the top of the autoclave. During this period, the reaction temperature is from 58 ° C at the start of polymerization to
The temperature was raised to 65 ° C. After the intermittent addition of styrene to the reaction system was completed, the temperature was raised to 100 ° C. over 50 minutes. The ratio of the vinyl cyanide-based monomer component in the residual monomer during the polymerization is as shown in FIG. After that, the reaction system was cooled, the polymer was separated, washed, and dried in a usual manner to obtain a beaded copolymer. The final polymerization rate is 95%, and the ratio of vinyl cyanide-based monomer components in the residual monomers at the end of polymerization is 90%.
Met.

Example 2 Of the conditions of Example 1, mixed solution: acrylonitrile 28 parts styrene 12 parts t-dodecyl mercaptan 0.33 parts 2,2'-azobis (2,4-dimethylvaleronitrile) 0 parts 2, 2'-azobisisobutyl nitrile 0.32 part Addition of styrene: 60 parts Reaction temperature from the start of polymerization to the end of additional addition: 65 ° C to 73 ° C, and then polymerization was carried out in the same manner as in Example 1, A beaded copolymer was obtained.

Example 3 Of the conditions of Example 1, mixed solution: acrylonitrile 50 parts styrene 4 parts styrene additional addition: 46 parts, and then polymerization was carried out in the same manner as in Example 1 to obtain a beaded co-polymer. Got united.

Example 4 Of the conditions of Example 1, mixed solution: acrylonitrile 42 parts styrene 4 parts N-phenylmaleimide 5 parts styrene additional addition: 49 parts, and then polymerization was carried out in the same manner as in Example 1. Then, a bead-shaped copolymer was obtained.

Example 5 Of the conditions of Example 1, mixed solution: methacrylonitrile 42 parts styrene 4 parts additional addition of styrene: 54 parts, and polymerization was carried out in the same manner as in Example 1 to form beads. A copolymer was obtained.

Example 6 Of the conditions of Example 2, mixed solution: acrylonitrile 34 parts α-methylstyrene 9 parts styrene additional addition 39 parts α-methylstyrene additional addition: 18 parts and the rest of Example 2 Polymerization was carried out in the same manner to obtain a beaded copolymer.

Example 7 Among the conditions of Example 1, 1.5 parts of t-dodecyl mercaptan was used, and then the polymerization was carried out in the same manner as in Example 1 to obtain a beaded copolymer.

Example 8 Among the conditions of Example 1, 0.3 part of t-dodecyl mercaptan was used, and then the polymerization was carried out in the same manner as in Example 1 to obtain a beaded copolymer.

Example 9 Of the conditions of Example 1, 2,2'-azobis (2,4-dimethylvaleronitrile) 0.39 parts 2,2'-azobisisobutyronitrile 0.05 parts were t. -Butyl peroxypivalate was 0.45 part, and then the polymerization was carried out in the same manner as in Example 1 to obtain a beaded copolymer.

Example 10 Of the conditions of Example 1, 0.05 part of methyl methacrylate / acrylamide copolymer was changed to 1.00 part of barium sulfate, and the polymerization was carried out in the same manner as in Example 1 to obtain beads. A copolymer was obtained.

Comparative Example 1 Among the conditions of Example 2, mixed solution: acrylonitrile 24 parts styrene 76 parts styrene additional addition: 0 part, and then polymerization was carried out in the same manner as in Example 2 to obtain a bead-shaped copolymerization Got united.

Comparative Example 2 Of the conditions of Example 1, mixed solution: acrylonitrile 42 parts styrene 3 parts styrene additional addition: 55 parts. Then, polymerization was carried out in the same manner as in Example 1, and the beaded co-polymerization was carried out. Got united.

Comparative Example 3 Using a known bulk polymerization apparatus, a mixture of 62 parts of styrene, 38 parts of acrylonitrile, 10 parts of toluene, 0.2 part of N-octyl mercaptan and 0.01 part of t-butyl peroxide was added to a polymerization tank. Is continuously supplied to the polymerization rate of 75%
Then, the monomer was removed, and the apparent polymerization rate was set to 99% or more to complete the polymerization to obtain a copolymer.

Comparative Example 4 Polymerization was carried out based on Example 1 in JP-B-46-27808. The polymerization rate was 90%, and the ratio of the vinyl cyanide-based monomer component in the residual monomer at the end of the polymerization was 50% by weight. The ratio of vinyl cyanide-based monomer components in the residual monomers from the start of polymerization to the end of polymerization is shown in FIG. The specific viscosity was 0.354 (ηsp / c = 0.89 dl / g, methyl ethyl ketone 0.4% by weight solution, 30 ° C.), and the vinyl cyanide-based monomer component ratio in the copolymer was 29% by weight. .

Comparative Example 5 Polymerization was carried out based on Example 4 in JP-A-50-33917. The polymerization rate at the end of suspension polymerization was 99%, and the ratio of vinyl cyanide-based monomer components in the residual monomers at the end of polymerization was 6%.
It was 7% by weight. The ratio of vinyl cyanide-based monomer components in the residual monomers from the start of polymerization to the end of polymerization is shown in FIG. ηsp / c is 0.78 dl / g, methyl ethyl ketone is 0.
4% by weight solution, 30 ° C.), and the proportion of vinyl cyanide-based monomer component in the copolymer was 29% by weight.

Comparative Example 6 Polymerization was carried out based on Example 1 in JP-A-3-227306. The polymerization rate at the end of suspension polymerization was 73%, and the vinyl cyanide-based monomer component ratio in the residual monomers at the end of polymerization was 97% by weight. The ratio of vinyl cyanide-based monomer components in the residual monomers from the start of polymerization to the end of polymerization is shown in FIG. ηsp / c is 0.50 dl / g, methyl ethyl ketone 0.4
(Wt% solution, 30 ° C.), and the ratio of vinyl cyanide-based monomer component in the copolymer was 70 wt%.

First, the difference between the examples and the comparative examples of the high nitrile content vinyl copolymer of the present invention will be described. From Examples 1 to 3, it can be seen that the copolymers within the copolymer composition range described in the claims of the present invention are excellent in thermal coloring stability and chemical resistance when the resin is melted. Example 4
It can be seen from the above that the same effect can be obtained when other copolymerizable vinyl-based monomer is used as a constituent component. Example 5,
It can be seen from 6 that similar effects can be obtained when one or more vinyl cyanide-based monomers and aromatic vinyl-based monomers other than acrylonitrile and styrene are used. However, since the copolymers of Comparative Examples 1 and 6 are out of the copolymer composition range described in the claims of the present invention, Comparative Example 1 is inferior in chemical resistance, and Comparative Example 8 is in the case of melting the resin. Poor heat stability. It can be seen from Examples 1, 7 and 8 that the copolymers within the range of ηsp / c described in the claims of the present invention are excellent in thermal coloration stability and chemical resistance when the resin is melted. In Comparative Example 3, the proportion of the oligomer in the copolymer exceeds 0.6% by weight. Therefore, compared to the example
During molding of the resin composition using the copolymer of Comparative Example 3, the mold was markedly soiled, which was not practical in molding.

Next, the difference between the examples and the comparative examples of the method for producing the high nitrile content vinyl copolymer of the present invention will be described. From Examples 1 to 10, it can be seen that the copolymers produced within the production process range described in the claims of the present invention are excellent in thermal coloring stability and chemical resistance when the resin is melted. In Examples 1 to 6 and 9, the monomer constitutional unit, the type and amount of the polymerization initiator were changed. In Examples 7 and 8, ηsp / c was changed by changing the amount of chain transfer agent, and in Example 10, the suspension stabilizer species was changed to an inorganic suspension stabilizer.

In Comparative Example 1, since the ratio of the vinyl cyanide-based monomer component in the residual monomer from the initiation of polymerization to the point of time when the polymerization rate was 10% was less than 70% by weight, the chemical resistance was inferior to that in Examples. ing. In Comparative Example 2, the ratio of the vinyl cyanide-based monomer component in the residual monomer from the start of the polymerization to the completion of the polymerization was 95% by weight or more, and therefore the ratio of the triple sequence of the vinyl cyanide-based monomer was 10%. The content was more than 10% by weight, the YI value after the heat treatment of the resin was remarkably high as compared with the examples, and the thermal coloring stability when the resin was melted was inferior. Since Comparative Example 3 was polymerized by the bulk polymerization method, the proportion of the oligomer in the copolymer was 0.
It exceeds 6% by weight. Therefore, as compared with the examples, when the resin composition using the copolymer of Comparative Example 3 is molded, the mold is significantly soiled, which is not practical in molding. Comparative Example 4 is Comparative Example 1
Similarly to the above, since the ratio of the vinyl cyanide-based monomer component in the residual monomer from the initiation of the polymerization to the point of time when the polymerization rate of 10% has passed is less than 70% by weight, the chemical resistance is inferior to the examples. Further, since ηsp / c of the copolymer exceeds 0.80 dl / g, the MFR is remarkably lower than that of the examples and the moldability is poor. In Comparative Example 5, as in Comparative Example 1, since the ratio of the vinyl cyanide-based monomer component in the residual monomer from the initiation of polymerization to the point of 10% of the polymerization rate is less than 70% by weight,
It is inferior in chemical resistance to the examples. In Comparative Example 6, as in Comparative Example 2, since the ratio of the vinyl cyanide-based monomer component in the residual monomer from the start of the polymerization to the completion of the polymerization was 95% by weight or more, the vinyl cyanide-based monomer was The proportion of the triple sequence was more than 10% by weight, the YI value after the resin heat treatment was remarkably high as compared with the examples, and the thermal coloring stability at the time of melting the resin was poor.

The following is clear from the examples and comparative examples. That is, the resin composition using the copolymer obtained according to the present invention has not only moldability but also less mold stains, excellent chemical resistance, and excellent thermal coloring stability during melting. This is a novel copolymer in which the proportion of vinyl cyanide-based monomers in the residual monomers during polymerization is controlled to carry out aqueous suspension polymerization, and the triple sequence ratio is below a certain value and the amount of oligomers is small. It is first realized by using.

[0057]

[Table 1]

[Table 2]

[Table 3]

[0058]

The high nitrile content vinyl copolymer of the present invention contains a high proportion of vinyl cyanide monomer, has a small amount of oligomer, and has a triple sequence proportion of vinyl cyanide monomer component. Since it is extremely small, the mold stains are small, the thermal coloring stability at the time of melting is good, and the chemical resistance is also excellent. Further, the production method of the present invention, by controlling the ratio of the vinyl cyanide monomer component in the residual monomer from the start of polymerization to the end of the polymerization by a water-based suspension polymerization method to a certain ratio or less, the residual monomer in the first half of the polymerization. The feature is that the medium vinyl cyanide monomer component ratio is maintained at a high ratio. As a result, the above-mentioned vinyl copolymer having a high nitrile content can be produced for the first time. Further, the high nitrile content vinyl-based copolymer of the present invention is used as various impact-resistant thermoplastic resin composition by blending and melt-mixing rubber components, and various molding applications requiring chemical resistance and impact resistance. And is particularly suitable as a resin material for electric refrigerators.

[Brief description of drawings]

FIG. 1 is a graph obtained by converting the change with time of the ratio of vinyl cyanide-based monomer components in the residual monomer from the start of polymerization to the end of polymerization for the examples and comparative examples in terms of the conversion rate.

Claims (8)

[Claims] 1. A vinyl cyanide monomer (A) 25 to 55.
% By Weight, Aromatic Vinyl Monomer (B) 75-45% by Weight
And other vinyl-based monomers (C) copolymerizable therewith
A copolymer having 0 to 20% by weight as a constitutional unit, wherein the proportion of a triple sequence of vinyl cyanide-based monomers is 10% by weight or less in the copolymer, and having a high nitrile content. Vinyl-based copolymer. 2. The high nitrile-containing vinyl copolymer according to claim 1, wherein the proportion of the triple sequence of the vinyl cyanide-based monomer is 8% by weight or less in the copolymer. 3. A vinyl cyanide-based monomer (A) 30 to 45.
% By Weight, Aromatic Vinyl Monomer (B) 70-55% by Weight
The high nitrile content vinyl copolymer according to claim 1 or 2, which is a copolymer having (B) and 0 to 20% by weight of another vinyl monomer (C) copolymerizable therewith as a constitutional unit. . 4. The reduced viscosity of the copolymer is 0.20 to 0.8.
It is 0 dl / g, The high nitrile content vinyl-type copolymer of Claim 1, 2 or 3 characterized by the above-mentioned. 5. The high nitrile content vinyl copolymer according to claim 1, 2, 3 or 4, wherein the oligomer content in the copolymer is 0.6% by weight or less. 6. From 25 to 55% by weight of a vinyl cyanide-based monomer, 75 to 45% by weight of an aromatic vinyl-based monomer, and 0 to 20% by weight of another vinyl-based monomer copolymerizable therewith. In the polymerization of the following monomer, the ratio of vinyl cyanide-based monomer component in the residual monomer from the start of polymerization to the end of the polymerization is set to 95% by weight or less, and at least 10% of the polymerization rate has elapsed from the start of polymerization. The method for producing a vinyl copolymer having a high nitrile content, which comprises subjecting the residual monomer to a vinyl cyanide monomer component ratio of 70% by weight or more and 95% by weight or less to carry out aqueous suspension polymerization. 7. The method for producing a high nitrile-containing vinyl copolymer according to claim 6, wherein an azo polymerization initiator is used as the polymerization initiator. 8. The method for producing a high nitrile content vinyl copolymer according to claim 6, wherein an organic polymer compound is used as the dispersion stabilizer.