JPH06179725A - Styrenic copolymer, thermoplastic resin composition comprising the same copolymer and production thereof - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic resin composition, excellent in molding proessability, impact and heat resistance and surface appearance and useful as automotive parts, etc., by mixing a specific styrenic copolymer with a specified copolymer in a specific proportion. CONSTITUTION:The composition is obtained by mixing (A) a styrenic copolymer composed of (i) 1-50wt.% maleimide-based monomer, (ii) 5-30wt.% vinyl cyanide monomer, (iii) 30-90wt.% styrene and (iv) 1-30wt.% alpha-methylstyrene [the total amount of the components (i) to (iv) is 100wt.%] with (B) a graft copolymer prepared by reacting 30-90 pts.wt. rubber-like elastomer with 70-10 pts.wt. one or monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers and (meth)acrylic acid ester monomers so as to contain 2-35wt.% rubber-like elastomer (based on 100wt.% composition). Furthermore, this composition is obtained by carrying out the emulsion copolymerization of the monomers (i) to (iv) using an emulsifying agent such as an alkali metallic sulfonate, producing the component (A) and mixing the resultant components (A) with (B).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a styrene copolymer which has excellent molding processability and gives a molded article excellent in impact resistance, heat distortion resistance and surface appearance, and a thermoplastic resin containing the same. The present invention relates to a resin composition and a method for producing them.

[0002]

2. Description of the Related Art ABS resin is used for impact resistance, heat distortion resistance, and
Because it has a good balance of molding processability,
It is used in a wide range of applications such as electronic and electrical parts. In recent years, due to miniaturization and weight reduction in these applications,
It is required to improve the balance of moldability. However, for example, when copolymerizing α-methylstyrene, maleimide or the like in order to improve heat distortion resistance, impact resistance, molding processability, etc. are lowered, and in order to improve impact resistance, polybutadiene or the like is used. Increasing the amount of rubber-like elastic material causes a problem that heat resistance, rigidity, etc. are reduced. Further, the copolymerization of α-methylstyrene, maleimide and the like has a problem that the polymerization conversion rate is lowered and steel is generated during the polymerization.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a styrene-based copolymer which has excellent molding processability and gives a molded article excellent in impact resistance, heat resistance and surface appearance, and a thermoplastic resin containing the same. A resin composition is provided.

[0004]

Means for Solving the Problems As a result of intensive studies to overcome such problems, the present inventors have found that a specific styrene-based copolymer and a specific ratio of the copolymer and a specific graft copolymer are contained. It was found that a thermoplastic resin composition excellent in impact resistance, heat distortion resistance and molding processability can be easily obtained by mixing with the above method, and the present invention has been completed. That is, the first of the present invention is (a) 1 to 50% by weight of a maleimide monomer,
(B) 5 to 30% by weight of vinyl cyanide monomer, (c) 30 to 90% by weight of styrene, and (d) 1 to 30% by weight of α-methylstyrene [(a), (b), (c)). And (d)
100% by weight in total], a styrene-based copolymer,
The second aspect of the present invention is (a) maleimide monomer 1 to 50% by weight, (b) vinyl cyanide monomer 5 to 30% by weight, and (c) styrene 30 to 90% by weight. %, And (d) 1 to 30% by weight of α-methylstyrene [(a),
100% by weight of (b), (c) and (d) in total], an aromatic vinyl monomer and a vinyl cyanide monomer in 30 to 90 parts by weight of the rubber-like elastic body. , A graft copolymer (B) prepared by reacting 70 to 10 parts by weight of one or more monomers selected from the group consisting of (meth) acrylic acid ester monomers, and a rubber-like elastic material ~ 35
A thermoplastic resin composition which is mixed so as to contain the resin in an amount of 100% by weight (100% by weight of the entire thermoplastic resin composition),
And its manufacturing method, respectively.

The styrenic copolymer in the present invention is
(A) 1 to 50% by weight, preferably 5 to 40% by weight, more preferably 5 to 30% by weight of a maleimide-based monomer,
(B) Vinyl cyanide monomer 5 to 30% by weight, preferably 10 to 25% by weight, (c) Styrene 30 to 90% by weight, preferably 40 to 80% by weight, more preferably 40.
To 75% by weight, (d) α-methylstyrene 1 to 30% by weight, preferably 3 to 30% by weight, more preferably 5 to 2%
5% by weight (however, (a), (b), (c),
(D) 100% by weight in total]. When the maleimide-based monomer (a) is less than 1% by weight, the heat distortion resistance is lowered, and when it exceeds 50% by weight, impact resistance and molding processability are lowered, the polymerization conversion rate is lowered, and the scale during polymerization is reduced. Will increase. When the vinyl cyanide monomer (b) is less than 5% by weight, impact resistance, rigidity and chemical resistance are deteriorated, and when it exceeds 30% by weight, thermal stability is deteriorated and molding processability is deteriorated. The polymerization conversion rate decreases. If the styrene (c) content is less than 30% by weight, the molding processability will decrease, and if it exceeds 90% by weight, impact resistance and chemical resistance will decrease. If the amount of α-methylstyrene (d) is less than 1% by weight, the heat distortion resistance is reduced, the scale generated during polymerization is increased, and if it exceeds 30% by weight, the thermal stability is reduced and the molding processability is reduced. .

The maleimide type monomer (a) used in the present invention includes maleimide, N-methylmaleimide,
Examples include N-ethylmaleimide, N-phenylmaleimide and its derivatives, N-cyclohexylmaleimide and its derivatives, and these may be used alone or in combination of two or more. As the vinyl cyanide monomer (b),
Acrylonitrile, methacrylonitrile and the like are exemplified,
These are used alone or in combination of two or more. Furthermore, a small amount of other vinyl-based monomers can be used if necessary. Solution viscosity of copolymer (A) (dl / g, 3
0 ° C., N, N′-dimethylformamide solution) has an intrinsic viscosity of preferably 0.25 to 1.5, more preferably 0.1.
It is 5 to 1.2, and more preferably 0.5 to 0.8.
If it is less than 0.25, impact resistance and chemical resistance are lowered, and if it exceeds 1.5, molding processability is deteriorated, which is not preferable.

The method for polymerizing the copolymer in the present invention is not particularly limited, and examples thereof include emulsion polymerization, suspension polymerization, emulsion-suspension polymerization, bulk polymerization and solution polymerization.
The emulsion polymerization method is preferred. The emulsion polymerization method can be carried out by a usual method. For example, the monomer may be reacted in an aqueous dispersion in the presence of a radical initiator.

Examples of the radical initiator include potassium persulfate, ammonium persulfate, cumene hydroperoxide and the like. From the viewpoint of suppressing the generation of scale during polymerization, potassium persulfate and peroxide are preferable. Ammonium sulfate. As the emulsifier, sodium dodecylbenzene sulfonate, sodium alkane sulfonate, an alkyl sulfonic acid-based alkali metal salt such as sodium dialkylsulfosuccinate, an alkyl sulfate-based alkali metal salt such as sodium lauryl sulfate is subjected to polymerization conversion,
It is preferable in terms of suppressing the generation of scale during polymerization. The amount of the emulsifier is preferably 0.5 to 4 parts by weight with respect to 100 parts by weight of the monomer. Outside of this range, the polymerization conversion rate decreases and the heat distortion resistance of the obtained resin decreases, which is not preferable. In addition, polymerization accelerators, polymerization degree regulators, antioxidants, and the like, which have hitherto been generally used in emulsion polymerization, can be appropriately selected and used. PH in the polymerization system is adjusted to preferably 3 to 9, more preferably 4 to 8.
When the pH is less than 3 or more than 9, the maleimide-based monomer is hydrolyzed, the polymerization conversion rate is decreased, and the scale during polymerization is increased, which is not preferable.

The styrene-based copolymer obtained as described above [hereinafter referred to as a copolymer (A)] has excellent heat resistance and molding processability by itself, but a specific graft copolymer ( By mixing with B), it is possible to provide a molded product having excellent molding workability, impact resistance, heat resistance and surface appearance. The graft copolymer (B) in the present invention comprises 30 to 90 parts by weight of a rubber-like elastic material,
Preferably 40 to 80 parts by weight of 70 to 70% of one or more monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers and (meth) acrylic acid ester monomers.
It is formed by reacting 10 parts by weight, preferably 60 to 20 parts by weight. The rubber-like elastic material preferably has a glass transition temperature of 0 ° C.
Or less, more preferably −30 ° C. or less, further preferably −
The thing below 60 degreeC is used. Specifically, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, butyl acrylate-butadiene rubber, diene rubber such as styrene-butadiene-styrene rubber, acrylic rubber such as polybutyl acrylate, ethylene-propylene rubber, Examples include polyolefin rubbers such as ethylene-propylene-non-conjugated diene rubbers, which may be used alone or in combination of two or more.

The aromatic vinyl monomer used is
Examples of styrene, methyl styrene, chlorostyrene, tert-butyl styrene, α-methyl styrene, etc.,
Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and examples of the (meth) acrylic acid ester monomer include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and the like. They may be used alone or in combination of two or more, but styrene and acrylonitrile are more preferable.

Regarding the vinyl cyanide monomer and the maleimide type monomer used in the copolymer (A) and the vinyl cyanide monomer used in the graft copolymer (B),
The weight percentage of the vinyl cyanide monomer used in the graft copolymer (B) is BAN, the weight percentage of the vinyl cyanide monomer used in the copolymer (A) is AAN, and the copolymer (A).
When the weight% of the maleimide-based monomer used for is represented by AMI, it is preferable that the relationship of the following formula (1) is satisfied, and −20 ≦ (AAN + AMI) −BAN ≦ + 20 (1) is more preferable. It is to satisfy the relationship of (2). −10 ≦ (AAN + AMI) −BAN ≦ + 10 (2) Outside the range of the above formula (1), impact resistance and rigidity decrease, which is not preferable.

The graft ratio of the graft copolymer (B) (weight of polymer grafted on rubber-like elastic material / weight of rubber-like elastic material × 100) is preferably 10 to 100%, more preferably 30 to 80%. It is a range. The rubber-like elastic body has an average particle size (weight average particle size observed by a transmission electron microscope) of preferably 0.05 to 3 μm, more preferably 0.1 to 2 μm. If the graft ratio and the rubber-like elastic material are out of these ranges, impact resistance, rigidity, surface property, and moldability are deteriorated, which is not preferable. The graft copolymer (B) can be polymerized by the same method as the copolymer (A).

The physical properties of the thermoplastic resin composition of the present invention depend not only on the respective compositions of the copolymer (A) and the graft copolymer (B) but also on the mixing ratio thereof. Therefore, the mixing ratio may be selected according to the desired physical properties,
In order to preferably achieve the present invention, the rubber-like elastic material is mixed in an amount of 2 to 35% by weight in the composition after mixing. The mixing may be performed by a method known per se. For example,
The latex obtained by emulsion polymerization of each of the copolymer (A) and the graft copolymer (B) may be mixed, salted out, coagulated and dried, and then used. Further, the copolymer (A)
The respective powders or pellets of and the graft copolymer (B) may be kneaded with a roll, a screw, a Banbury mixer, a kneader or the like. If necessary, a commonly used stabilizer,
Pigments, lubricants, light stabilizers, fillers and the like may be added.

[0014]

EXAMPLES The present invention will be described more concretely with reference to the following examples. In the following description, "part" or "%" means "part by weight" or "% by weight", respectively.
Represents Examples and Comparative Examples (1) Production of Copolymer (A) A reactor equipped with a stirrer was charged with 200 parts of ion-exchanged water, the emulsifier shown in Table 1, a polymerization accelerator and an initiator, and sodium hydroxide and hydrochloric acid were used to produce an initial PH. Was adjusted. After deoxidizing the inside of the reactor,
After heating and stirring at 70 ° C. in a nitrogen stream, the monomer mixture shown in Table 1 was continuously added dropwise over 6 hours. 1 at 70 ℃
After continuing stirring for an hour, the polymerization was completed. A small amount of the produced latex was sampled and the final PH and solution viscosity were measured. The copolymer latex was coagulated with magnesium chloride, washed with water, filtered, dried and pelletized to measure its physical properties. In addition, during the polymerization, the latex was filtered through a 100-mesh wire net, the gel was dried, and the amount was measured. The results are shown in Table 1.

[0015]

[Table 1]

DBS: Sodium dodecylbenzene sulfonate * 1 DBS is continuously added together with a monomer mixture PS: Sodium alkane sulfonate having 14 to 18 carbon atoms SFS: Sodium formaldehyde sulfoxylate EDTA: Disodium ethylenediaminetetraacetate Fe : Ferrous sulfate KPS: Potassium persulfate

(2) Preparation of graft copolymer (B) B-1: 12 parts of acrylonitrile in 60 parts (solid dispersion) of polybutadiene latex having an average particle size of 0.35 μm,
Graft-copolymerized 28 parts of styrene (graft ratio 50%, polymerization conversion 96%) B-2: 60 parts of polybutadiene latex having an average particle diameter of 0.35 μm (solid dispersion), 5 parts of acrylonitrile and 35 parts of styrene. Graft-copolymerized (graft rate 52%, polymerization conversion rate 95%)

(3) Production of thermoplastic resin (C) The copolymer (A-1) shown in Table 1 obtained in (1) above.
To (A-8), (A-10) and (A-11), and the graft copolymers (B-1) and (B- obtained in (2) above.
2) and 2) were mixed in a latex state at a ratio shown in Table 2, a phenolic antioxidant was added, and 100 parts of a resin powder obtained by salting out with magnesium sulfate, washing with water and drying, and ethylenebisstearylamide 1.0 The parts were mixed, extruded with a vented extruder at a barrel temperature of 270 ° C. to be pelletized, and subjected to physical property measurement. The results are shown in Table 2.

[0019]

[Table 2]

Izod impact value: ASTM D-25
6, notched, 23 ° C, kgcm / cm Tensile strength: ASTM D-636, 23 ° C, kg / cm ² Heat distortion temperature: ASTM D-648-56, 18.6kg
/ Cm ² load, ℃ Higher type flow value: 260 ℃, 100kg / cm ² load, × 1
0 ^-2 cc / sec Molded product appearance: 10 ounce injection molding machine with a box-shaped molded product of about 100 g, cylinder set temperature 270 ° C, injection pressure 110
Molded with 0 kg, observed the surface appearance, 3 according to the following criteria
Graded. ◯: Almost no defects such as discoloration, flow mark and silver are recognized. Δ: Defects such as discoloration, flow mark and silver are recognized. X: Marked defects such as burns, flow marks, and silver are remarkable.

[0021]

The styrene-based copolymer of the present invention provides a molded article having good molding processability and excellent heat distortion resistance and surface appearance, and the copolymer and the graft copolymer. The resin composition consisting of (3) provides a molded article excellent in impact resistance as well as these physical properties.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08L 25/12 LDW 9166-4J 51/04 LKY 7142-4J 55/02 LME 7142-4J

Claims (6)

[Claims] 1. (a) 1 to 50% by weight of a maleimide monomer, (b) 5 to 30% by weight of a vinyl cyanide monomer,
(C) 30 to 90% by weight of styrene and (d) 1 to 30% by weight of α-methylstyrene [(a), (b), (c) and (d) 100% by weight in total] Polymer. 2. The method for producing a styrene-based copolymer according to claim 1, wherein the styrene-based copolymer is produced by emulsion polymerization. 3. The styrene-based polymer according to claim 2, wherein when the styrene-based copolymer is produced by emulsion polymerization, an alkali metal sulfonate is used as an emulsifier to adjust the PH in the system to the range of 3-9. Method for producing copolymer. 4. (a) 1-50% by weight of a maleimide-based monomer, (b) 5-30% by weight of a vinyl cyanide monomer,
(C) 30 to 90% by weight of styrene and (d) 1 to 30% by weight of α-methylstyrene [(a), (b), (c) and (d) 100% by weight in total] At least one selected from the group consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and a (meth) acrylic acid ester monomer in 30 to 90 parts by weight of the polymer (A) and the rubber-like elastic body. 2 to 35% by weight of a rubber-like elastic body with a graft copolymer (B) obtained by reacting 70 to 10 parts by weight of the above monomer.
A thermoplastic resin composition obtained by mixing so as to contain (100% by weight of the whole thermoplastic resin composition). 5. A method for producing a thermoplastic resin composition, which comprises producing a styrene copolymer (A) by emulsion polymerization and mixing it with a graft copolymer (B). 6. The method according to claim 5, wherein when the styrene copolymer (A) is produced by emulsion polymerization, an alkali metal sulfonate is used as an emulsifier and the pH in the system is adjusted to the range of 3 to 9. Manufacturing method.