JPH10330439A - Thermoplastic resin composition and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition in a high yield without deteriorating the impact strengths of molded products, etc., by blending a styrenic resin, etc., with a graft polymer containing a rubbery polymer in a high content and controlled in a graft efficiency. SOLUTION: This thermoplastic resin composition comprises (A) a graft copolymer composition having a graft efficiency of 60-80% and obtained by graft-copolymerizing (ii) 50-99 wt.% of an aromatic vinyl monomer, 1-50 wt.% of a vinyl cyanide monomer and 0-50 wt.% of one or more other vinylic monomers copolymerizable with the monomers in the presence of (i) 65-85 pts.wt. of a dienic rubbery polymer and (B) a polymer obtained by copolymerizing an aromatic vinyl monomer, a vinyl cyanide monomer and one or more monomers selected from other vinylic monomer copolymerizable with the monomers. The components A and B are preferably contained in amounts of 10-90 pts.wt. and 10-90 pts.wt., respectively, in the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a graft polymer containing a rubbery polymer and a thermoplastic resin composition containing the graft polymer and having excellent impact resistance and excellent surface appearance of a molded article. It is about.

[0002]

2. Description of the Related Art An acrylonitrile-butadiene-styrene copolymer (ABS resin) is known as a resin having excellent impact resistance, and this effect is obtained by dispersing rubbery polymer particles in a matrix resin (AS resin). Is expressed by Here, since the rubber polymer and the matrix resin are essentially incompatible, it is necessary to graft a component compatible with the matrix resin to the rubber polymer.

[0003] In addition, ABS resins are generally produced by a process of separately producing a graft polymer having a high rubbery polymer composition and a matrix resin and then blending the two. Productivity and economic efficiency are much higher than the production process obtained by polymerizing all monomer components in the presence of coalescence, and the physical properties of the resin composition, especially impact properties, fluidity and mechanical properties are well balanced. This is because there is an advantage that it can be set.

[0004]

Generally, the higher the rubbery polymer content of the graft polymer blended with the matrix resin, the higher the productivity and economic efficiency. However, as the content of the rubbery polymer in the graft polymer increases, the surface appearance of a molded article of the resin composition decreases, and it becomes difficult to set the physical properties in a well-balanced manner. In particular, when the content of the rubbery polymer is 65% by weight or more, the surface appearance and impact properties of the molded product observed in fish eyes are significantly reduced.

[0005] This is considered to be because the rubbery polymer aggregated and the dispersibility in the matrix resin was reduced. This aggregation is particularly remarkable when the content of the rubbery polymer is 65% by weight or more, and is considered to be caused by a decrease in the compatibility between the matrix resin and the graft polymer due to a relative decrease in the graft component and an aggregation between the graft polymers. Can be

[0006]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, the rubbery polymer content was 65 to 8%.
In producing a 5% by weight graft polymer, polymerization is performed without grafting a part of a monomer component used for a graft reaction in order to suppress agglomeration between rubbery polymers. That is, the graft efficiency in the graft polymerization is specified. It has been found that it is effective to control it within the range.

That is, the present invention provides: "In the presence of 65 to 85 parts by weight of a diene rubbery polymer, 50 to 99% by weight of an aromatic vinyl monomer, 1 to 50% by weight of a vinyl cyanide monomer, and others copolymerizable therewith. Which is obtained by graft polymerization of 15 to 35 parts by weight of a monomer mixture consisting of 0 to 50% by weight of a vinyl monomer having a graft efficiency of 60 to 8 as defined by the formula (1).
0% graft copolymer composition. 1. Grafting efficiency = (weight of grafted monomer) / (total weight of monomer) (1) ", "Reaction of graft-polymerizing a diene rubber polymer with a monomer mixture consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and another vinyl monomer copolymerizable therewith. Is carried out by emulsion polymerization. ", 2. A method for producing the graft polymer (A),""When graft polymerizing a diene rubber polymer with a monomer mixture consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and another vinyl monomer copolymerizable therewith. 3. The graft polymer of any of the above, wherein the non-grafted polymer (non-grafted polymer) formed in the above has an intrinsic viscosity of 0.05 to 0.35 dl / g measured at 30 ° C. in a methyl ethyl ketone solvent. ” "Any of the above graft polymers (A) 10 to 90
Parts by weight, aromatic vinyl monomer, vinyl cyanide monomer and at least one monomer selected from the group consisting of other vinyl monomers copolymerizable therewith. A thermoplastic resin composition comprising 10 to 90 parts by weight of a polymer (B). ”, 5. "Polymer (B) is an aromatic vinyl monomer unit 50
Wherein the heat is comprised of about 100 to 99% by weight, 1 to 50% by weight of a vinyl cyanide monomer unit, and 0 to 50% by weight of another vinyl monomer unit copolymerizable therewith. Plastic resin composition. ”, 6. "Methyl ethyl ketone solvent for polymer (B), 30 ° C
Any one of the above thermoplastic resin compositions having an intrinsic viscosity of 0.3 to 1 dl / g measured in the above. ”.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. In the present invention, weight means mass.

First, the graft polymer (A) of the present invention is a copolymer of 50 to 99% by weight of an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of 65 to 85 parts by weight of a diene rubbery polymer. 1 to 50% by weight of a polymer and 0 to 50% by weight of another vinyl monomer copolymerizable therewith
It is obtained by graft polymerization of 5 to 35 parts by weight.

As the diene rubbery polymer used for this, a polymer or copolymer containing a conjugated diene as a main component is preferable. Among them, the content of the conjugated diene is preferably at least 75% by weight, particularly preferably at least 85% by weight. Specifically, polybutadiene, styrene-butadiene copolymer,
Acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, isoprene rubber and the like can be used.

The average particle diameter of these diene rubbery polymers is preferably from 0.1 to 0.6 μm, more preferably from 0.2 to 0.4 μm. The particle size distribution is not particularly limited.
Use of a rubbery polymer having a peak distribution can improve impact resistance and the like.

In the present invention, the monomers to be graft-polymerized in the presence of the rubbery polymer include an aromatic vinyl monomer, a vinyl cyanide monomer and, if necessary, a copolymerizable with them. It is a mixture of other vinyl monomers.

As the aromatic vinyl monomer, styrene,
α-methylstyrene, p-methylstyrene, vinyltoluene, t-butylstyrene, o-ethylstyrene, o-
Chlorostyrene, p-chlorostyrene, o, p-dichlorostyrene and the like can be mentioned, but styrene is particularly preferably used. These may be used alone or in combination of two or more.

Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile and ethacrylonitrile, and acrylonitrile is particularly preferred.

Other monomers copolymerizable therewith include unsaturated carboxylic acid monomers, unsaturated carboxylic acid anhydride monomers, unsaturated carboxylic acid ester monomers, and the like.
Alternatively, a maleimide-based monomer or the like can be used.
Specifically, (meth) acrylic acid, maleic anhydride,
Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, Cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, benzyl (meth) acrylate, N-methylmaleimide, N-
Ethyl maleimide, N-cyclohexyl maleimide, N
-Phenylmaleimide, N-2,3-dimethylphenylmaleimide, N-2,4-dimethylphenylmaleimide, N-2,6-dimethylphenylmaleimide, N-
2,3-Dichlorophenylmaleimide and N-2,3-dibromophenylmaleimide can be used.

The graft polymer (A) of the present invention comprises 65 to 85 parts by weight, preferably 70 to 80 parts by weight of a diene rubbery polymer.
It is obtained by graft polymerization of 15 to 35 parts by weight, preferably 20 to 30 parts by weight, of the monomer mixture with respect to parts by weight. When the amount of the rubbery polymer exceeds 85 parts by weight, the surface appearance characteristics and impact resistance of the resin are significantly reduced due to the relative decrease of the monomer mixture. On the other hand, if the amount is less than 65 parts by weight, productivity and economy are remarkably inferior.

The proportion of the aromatic vinyl monomer among the monomers subjected to the graft polymerization reaction is 50 to 99% by weight, preferably 60 to 90% by weight, and more preferably 70 to 90% by weight.
If it is less than 50% by weight, a good dispersion state of the rubber particles in the matrix resin cannot be obtained, which is not preferable.

The proportion of the vinyl cyanide monomer is from 1 to 50% by weight, preferably from 10 to 40% by weight of all the monomers,
The content is more preferably 20 to 30% by weight, and if it exceeds 50% by weight, the impact properties and surface appearance of the resin composition are undesirably reduced.

The object of the present invention can be achieved by using other vinyl monomers copolymerizable with these at 50% by weight or less.

Regarding the method for producing the graft polymer,
Emulsion polymerization is preferred. Monomer mixture in emulsion polymerization,
Various methods can be adopted as a method for adding components such as an emulsifier, a polymerization initiator, and a chain transfer agent. That is, there are a method of adding the whole amount at the initial stage of polymerization, a method of adding a part at an initial stage and adding the remainder continuously, a method of adding the whole amount continuously, and a method of adding two or more times.

The types of the emulsifier, polymerization initiator and chain transfer agent used are not particularly limited, and reagents used in ordinary emulsion polymerization can be used. Typical emulsifiers include potassium rosinate, potassium stearate, potassium oleate, and the like, and polymerization initiators include a combination of organic hydroperoxide and sugar-containing pyrophosphate-ferrous sulfate and a peracid salt. Examples of the chain transfer agent include alkylthiol compounds.

In order to achieve the object of the present invention, in the above graft polymerization, it is necessary that the grafting efficiency defined by the formula (1) be in the range of 60 to 80%. Grafting efficiency = (weight of grafted monomer) / (total weight of monomer) (1)

If the grafting efficiency exceeds 80%, it is considered that this is due to a decrease in the dispersibility of the graft rubber due to a shortage of the ungrafted polymer. Further, even if the grafting efficiency is less than 60%, the surface appearance and impact properties of the molded product are undesirably reduced. This is presumed to be due to a decrease in the graft component.

The ungrafted polymer can be easily separated from the graft polymer by extraction with acetone. The intrinsic viscosity of the ungrafted polymer measured at 30 ° C. in a methyl ethyl ketone solvent is 0.05 to 0.35 dl / g, preferably 0.1 to 0.30 dl / g. 0.35dl / g
Exceeding the range is not preferred because the dispersibility of the graft rubber decreases. If it is less than 0.05 dl / g, sufficient impact strength cannot be obtained, which is not preferable.

The grafting efficiency and the intrinsic viscosity of the ungrafted polymer can be controlled by adjusting the ratio of the rubbery polymer to the monomer mixture and the types and amounts of the polymerization initiator, the chain transfer agent and the emulsifier. .

In the present invention, the graft polymer (A)
10 to 90 parts by weight and at least one monomer selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers and other vinyl monomers copolymerizable therewith. A thermoplastic resin composition comprising 10 to 90 parts by weight of a polymer (B) obtained by polymerization is provided.

Hereinafter, the polymer (B) will be specifically described.

The polymer (B) is characterized by comprising an aromatic vinyl monomer unit, a vinyl cyanide monomer unit and another vinyl monomer unit copolymerizable therewith. It is a thermoplastic polymer, and aromatic vinyl monomers include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, t-butylstyrene, o-ethylstyrene, o-chlorostyrene, and p-chlorostyrene. Styrene and o, p-dichlorostyrene are exemplified, and styrene is particularly preferably used. These are one or two
More than one species may be used in combination.

Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, and ethacrylonitrile, and acrylonitrile is particularly preferable.

Other monomers copolymerizable therewith include unsaturated carboxylic acid monomers, unsaturated carboxylic acid anhydride monomers, unsaturated carboxylic acid ester monomers, and the like.
Alternatively, a maleimide-based monomer or the like can be used.
Specifically, (meth) acrylic acid, maleic anhydride,
Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, Cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, benzyl (meth) acrylate, N-methylmaleimide, N-
Ethyl maleimide, N-cyclohexyl maleimide, N
-Phenylmaleimide, N-2,3-dimethylphenylmaleimide, N-2,4-dimethylphenylmaleimide, N-2,6-dimethylphenylmaleimide, N-
2,3-Dichlorophenylmaleimide and N-2,3-dibromophenylmaleimide can be used.

The proportion of the aromatic vinyl monomer is from 50 to 99% by weight, preferably from 60 to 90% by weight, based on all monomers.
It is more preferably 70 to 80% by weight, and the ratio of the vinyl cyanide monomer is 1 to 50% by weight, preferably 10 to 50% by weight.
It is 40% by weight, more preferably 20 to 30% by weight.
Even if the proportion of the aromatic vinyl monomer exceeds 99% by weight, 5
If the amount is less than 0% by weight, the balance of physical properties of the resin composition is undesirably reduced. Further, other monomers copolymerizable therewith can be blended for various purposes, but are not essential components, and 50% by weight to maintain the effect of the present invention.
The following amounts can be blended.

Specifically, the polymer (B) used in the present invention includes polystyrene, SAN (styrene-acrylonitrile copolymer) resin, styrene-methyl (meth) acrylate copolymer, styrene-acrylonitrile- Methyl (meth) acrylate copolymer, styrene- (meth) acrylic acid copolymer, styrene-acrylonitrile- (meth) acrylic acid, styrene-α-methylstyrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer Styrene-acrylonitrile-maleic anhydride copolymer, styrene-N-phenylmaleimide copolymer, styrene-acrylonitrile-N-phenylmaleimide copolymer, and the like, and two or more of these may be used in combination. .

The polymer (B) selected from the above is polymerized by a known method such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization. The intrinsic viscosity of the obtained polymer measured in a methyl ethyl ketone solvent at 30 ° C. is 0.3 to 1 dl / g, preferably 0.4 to 0.8 dl / g.
dl / g. If it exceeds 1 dl / g, the moldability of the thermoplastic resin is impaired, and if it is less than 0.3 dl / g, the impact and mechanical properties are not sufficient, which is not preferable.

The method for melt-kneading the graft polymer (A) and the polymer (B) is not particularly limited, and can be easily produced using, for example, a single screw extruder.

The graft polymer (A) of the present invention and the resin composition comprising the graft polymer (A) and the polymer (B) may be provided with carbon black, a titanium compound and various dyes according to the purpose. Pigments and dyes, phosphorus-based, phenol-based stabilizers, halogen-based compounds, antimony compounds, flame retardants such as metal hydroxides, phenol-based, phosphite-based and sulfur-based antioxidants, hindered phenol-based, Benzotriazole, benzophenone, benzoate and cyanoacrylate UV absorbers, waxes, lubricants and plasticizers such as higher fatty acids, acid esters and acid amides, higher alcohols, amines, sulfonic acids, polyethers System, etc., and fillers such as glass fiber, talc, and minerals. That.

The graft polymer (A) and the resin composition comprising the graft polymer (A) and the polymer (B) are used as a molded article by a method such as injection molding or extrusion molding.

[0037]

The present invention will be described in more detail with reference to the following examples.

The method for analyzing the graft copolymer of the present invention is described below.

(1) Graft ratio Acetone was added to a predetermined amount M (g) of the graft polymer, and
Refluxed for hours. After the solution was centrifuged at 9,000 rpm for 30 minutes, insoluble components were filtered. This insoluble matter was dried under reduced pressure at 60 ° C. for 5 hours, and the weight N (g) was measured. The graft ratio was calculated by the following equation. G = (N−M × L) / (M × L) Here, L represents the content of the rubbery polymer in the graft polymer.

(2) Graft Efficiency From the graft ratio G determined above, the graft efficiency Fg can be calculated by the following equation. Fg = (G × L) / (1-L)

(3) Intrinsic viscosity of ungrafted polymer After filtering the insoluble matter from the acetone solution used for the measurement of the graft ratio, acetone was evaporated from the filtrate, and methanol was added to the residue to remove the non-grafted polymer. Extracted. After the extract was dried under reduced pressure at 60 ° C. for 3 hours, it was dissolved in methyl ethyl ketone, and the intrinsic viscosity of this solution was measured in a thermostat at 30 ° C.

Next, the method for evaluating the physical properties of the resin composition will be described below.

(1) Izod impact strength Measured according to ASTM D-256 (1/2 inch, notched, 23 ° C.).

(2) Drop Weight Impact Strength The measurement was performed according to JJSK 6745.

(3) Fish Eye Approximately 10 g of resin pellets before molding were heated and pressed at 250 ° C. and stretched to form a 10 μm thick film. The number of rubber-like lumps (bubbles) contained in the film 100 × 200 mm was visually measured. A film with a smooth surface is a case where the number of spots is 1 or less per 100 mm ² , and at this time, the surface appearance of the molded product is good. On the other hand, if the number of bumps exceeds 5 per 100 mm ² , the appearance of the molded product is significantly impaired.

[Production Method of Graft Polymer (A)] Table 1
A latex of a diene rubbery polymer (PBD) was charged into a glass reactor with the composition described in (1), and glucose, sodium pyrophosphate, and ferrous sulfate dissolved in ion-exchanged water were further charged with stirring, and the container was charged with nitrogen. After replacing the inside, the temperature in the reaction vessel was raised to 65 ° C.

A predetermined monomer (ST, A) is added to this mixture.
A mixed solution of N) and tert-dodecyl mercaptan and an aqueous solution of cumene hydroperoxide in potassium oleate were continuously dropped. The time required for continuous dropping is described in Table 1 as the polymerization time. After completion of the dropwise addition, stirring was continued for another hour to complete the reaction, and 2,6-di-tert-butylparacresol was added as an antioxidant. All conversions ranged from 95 to 99%.

The obtained graft copolymer latex was coagulated with sulfuric acid, neutralized with sodium hydroxide, washed with water, dehydrated and dried to obtain a graft polymer. Table 1 summarizes the graft ratio, graft efficiency, and intrinsic viscosity of methyl ethyl ketone-soluble components of each graft polymer.

[0049]

[Table 1]

[Production of polymer (B)] 70% of styrene,
A monomer mixture composed of 30% of acrylonitrile was subjected to suspension polymerization to produce a SAN resin. The intrinsic viscosity of the polymer (B) soluble in methyl ethyl ketone was 0.49 dl / g.

[Examples 1 to 3 and Comparative Examples 1 to 7] The graft polymer (A) and the polymer (B) prepared above were mixed in the proportions shown in Table 2, and 1 part of a lubricant was added. ,
Mix with a Henschel mixer. The PBD content of the resin composition was evaluated at 12% by weight and 24% by weight.
Next, the mixture was extruded at a kneading temperature of 220 ° C. using a 40 mmφ single screw extruder, and each was pelletized. In order to evaluate the physical properties, injection molding was performed under the conditions of a molding temperature of 230 ° C. and a mold temperature of 60 ° C. to produce each test piece. Table 2 shows the evaluation results of fish eyes and physical properties of each resin composition.

[0052]

[Table 2]

The following is clear from the examples and comparative examples.

The rubber content within the scope of the present invention is 65 to 85.
In the resin compositions (Examples 1 to 3) in which the graft polymer was blended in which the graft efficiency was 60 to 80% by weight%, a smooth film could be produced, and the number of bumps per 100 mm ² was less than 1. . On the other hand, in the resin composition (Comparative Examples 1 to 7) in which the graft efficiency was out of the above range, many fish eyes appeared, and the film surface was uneven. At the same time, the impact strength of the resin composition in which fish eyes have occurred is reduced. This tendency is particularly apparent in the falling weight impact strength. This tendency was similarly confirmed when the content of the rubbery polymer in the resin composition was 12% by weight or 24% by weight.

The higher the PBD content of the graft polymer, the shorter the polymerization time, which is advantageous in terms of productivity.
At 0% by weight, even if the grafting efficiency is controlled within the above range, the surface appearance and impact properties of the resin composition are not improved. This is because the compatibility between the graft rubber and the matrix resin was significantly reduced.

[0056]

The thermoplastic resin of the present invention is obtained by blending a graft polymer containing a rubbery polymer with a styrene resin represented by SAN or the like. Productivity without sacrificing technical characteristics,
This makes it possible to increase the economic efficiency, and this effect is exhibited by using a graft polymer having a very high content of a rubbery polymer and controlling the grafting efficiency.

Claims (7)

[Claims] In the presence of 65 to 85 parts by weight of a diene rubbery polymer, 50 to 99% by weight of an aromatic vinyl monomer, 1 to 50% by weight of a vinyl cyanide monomer, and It is obtained by graft-polymerizing 15 to 35 parts by weight of a monomer mixture comprising 0 to 50% by weight of another polymerizable vinyl monomer, and the graft efficiency defined by the formula (1) is 60.
A graft copolymer composition of about 80%. Grafting efficiency = (weight of grafted monomer) / (total weight of monomer) (1) 2. A monomer mixture comprising an aromatic vinyl monomer, a vinyl cyanide monomer, and another vinyl monomer copolymerizable therewith with a diene rubber polymer. The method for producing a graft polymer (A) according to claim 1, wherein the reaction for graft polymerization is carried out by emulsion polymerization. 3. A monomer mixture comprising an aromatic vinyl monomer, a vinyl cyanide monomer, and another vinyl monomer copolymerizable therewith with a diene rubber polymer. The intrinsic viscosity of the non-grafted polymer (ungrafted polymer) formed at the time of graft polymerization measured at 30 ° C. in a methyl ethyl ketone solvent is 0.05 to 0.35 dl / g. Graft polymer. 4. The graft polymer (A) according to claim 1
10 to 90 parts by weight and at least one monomer selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers and other vinyl monomers copolymerizable therewith. A thermoplastic resin composition comprising 10 to 90 parts by weight of a polymer (B) obtained by polymerization. 5. A polymer (B) comprising 50 to 99% by weight of an aromatic vinyl monomer unit and 1 to 4 vinyl cyanide monomer units.
The thermoplastic resin composition according to claim 4, comprising 50% by weight and 0 to 50% by weight of another vinyl monomer unit copolymerizable therewith. 6. A methyl ethyl ketone solvent for the polymer (B),
The thermoplastic resin composition according to any one of claims 4 to 5, wherein the intrinsic viscosity measured at 30 ° C is 0.3 to 1 dl / g. 7. The graft polymer (A) and the polymer (B)
7. The process for producing a thermoplastic resin composition according to claim 4, which is obtained by melt-kneading