JP3270154B2 - Thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition having excellent impact strength, moldability, surface hardness and chemical resistance.

[0002]

2. Description of the Related Art In general, styrene resins represented by ABS resins are widely used in electric and electronic equipment parts, OA equipment and the like, and are required to have various properties such as impact resistance and moldability. Also, for the inner box and suitcase exterior of electric refrigerators, sheet-formed ABS resin is vacuum-formed and used, but these molded products are not limited to deformation but crack or break when subjected to impact. May be reached,
Higher impact resistance and elongation are required. Further, molded articles are required to have surface scratch resistance and chemical resistance.

[0003] In order to impart high impact resistance and elongation of the ABS resin, a technique of increasing the amount of a rubber component added or increasing the molecular weight of the AS resin as a matrix component is generally employed. However, these methods are not preferable because the high impact resistance and elongation are improved, but the moldability, rigidity and surface hardness of the molded product are reduced.

[0004]

SUMMARY OF THE INVENTION Under such circumstances,
An object of the present invention is to provide a thermoplastic resin composition having excellent sheet moldability, impact resistance, chemical resistance and surface hardness by improving the resin composition without impairing the properties of the styrene resin.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies for this purpose and have found that a vinyl-based graft copolymer having a specific composition ratio and a weight-average molecular weight and a vinyl-based graft copolymer having a specific composition ratio and a relative viscosity are obtained. It has been found that the above-mentioned thermoplastic resin composition can be obtained by the resin composition obtained from the copolymer.

That is, the present invention relates to (A) a copolymer of 50 to 70% by weight of an aromatic vinyl monomer and 30 to 30% by weight of a vinyl cyanide monomer in the presence of 10 to 60 parts by weight of a diene rubber polymer. 50 wt% and optionally obtained by graft-polymerizing the following 90 parts by weight exceeds the monomer mixture 40 parts by weight consisting of these copolymerizable vinyl monomer 0 to 20 wt%, and diene rubber Exists in the copolymer component and ungrafted monomer mixture consisting of aromatic vinyl monomer, vinyl cyanide monomer and, if necessary, copolymerizable vinyl monomer grafted to the polymer Copolymer composition consisting of copolymer components of these monomer mixtures
The weight average molecular weight of min is greater than 120,000 20
Graft copolymer 20 to 8 in the range of not more than 000
0% by weight, and (Component B) an aromatic vinyl monomer 50 to 70
%, 30 to 50% by weight of a vinyl cyanide monomer, and 0 to 2 of a vinyl monomer copolymerizable therewith if necessary.
The relative viscosity ηrel obtained by copolymerizing 0% by weight is 1.45.
≦ ηrel ≦ 1.65 Copolymer in the range of 20 to 80
It is a thermoplastic resin composition characterized by comprising by weight.

Hereinafter, the present invention will be described in detail. About the component A The diene rubber polymer used in the component A is a homopolymer or a copolymer of a conjugated diene monomer, or a copolymer of a conjugated diene monomer and another copolymerizable monomer. It is united.

The conjugated diene monomer described herein includes butadiene, isoprene, dimethylbutadiene, chloroprene and the like.

The other copolymerizable monomers include styrene,
Examples thereof include aromatic vinyl monomers such as α-methylstyrene and vinyltoluene, vinyl cyanide monomers such as acrylonitrile, and (meth) acrylate monomers such as methyl methacrylate and butyl acrylate.

Further, as the diene rubber polymer used in the present invention, a copolymer obtained by copolymerizing a polyfunctional vinyl monomer as a crosslinking monomer can be used.

[0011] Polyfunctional vinyl monomers that can be used include:
Examples include divinylbenzene, ethylene glycol dimethacrylate, triallyl cyanurate, allyl acrylate, and vinyl acrylate.

As a method for producing the graft copolymer of the component A, known graft polymerization techniques are possible. In the presence of the rubber polymer latex, a vinyl cyanide monomer and an aromatic vinyl monomer, Alternatively, it can be obtained by further adding a monomer copolymerizable with these monomers to these monomers, if necessary, and copolymerizing them.

The vinyl cyanide monomer used for producing the graft copolymer includes, for example, acrylonitrile, methacrylonitrile and the like.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, dimethylstyrene, chlorostyrene and the like.

The above monomers can be used alone or in combination of two or more.

The monomers copolymerizable with these monomer components include acrylic acid esters, methacrylic acid esters, acrylic acid, methacrylic acid, acrylamide, methacrylamide, and the like.

The graft copolymerization is preferably emulsion polymerization.
Emulsifiers used in emulsion polymerization include fatty acid soaps such as sodium stearate and potassium oleate, and organic sulfonic acids such as disproportionated potassium rosinate and sodium dodecylbenzenesulfonate.

As a method of adding the monomer mixture for graft polymerization, there are methods such as batch addition, partial division addition, and continuous division addition of all the graft polymerization monomers.

In order to carry out graft copolymerization effectively,
Continuous split addition is preferred. The polymerization temperature is preferably in the range of 40 to 90 ° C.

As the polymerization initiator, a redox system using a polyfunctional radical initiator and a metal salt such as ferrous sulfate or a chelating agent such as pyrophosphoric acid or disodium ethylenediaminetetraacetate in combination is preferable.

The amount of the initiator used may be 0.05 to 1.0 part by weight based on 100 parts by weight of the polymerizable monomer.

The amount of the diene rubber polymer contained in the component A is 10 to 80 parts by weight. If the amount is less than 10 parts by weight, the impact strength is low. .

The aromatic vinyl monomer accounts for 50 to 70 of the total monomers.
When the content is less than 50% by weight, the moldability and dimensional stability characteristic of the aromatic vinyl compound are impaired.

The vinyl cyanide monomer accounts for 30 to 30% of all monomers.
If it is 50% by weight and less than 30% by weight, the chemical resistance and surface hardness are insufficient, and if it exceeds 50% by weight, the moldability decreases.

In the graft copolymer as the component A,
The weight average molecular weight of the copolymer component of the monomer mixture grafted on the diene rubber polymer and the copolymer component of the monomer mixture which is not grafted is 120,000 to 20.
When it is less than 120,000, the impact strength and elongation are insufficient, and when it exceeds 200,000, the moldability is remarkably deteriorated.

Component B The aromatic vinyl monomer used for the component B includes, for example, styrene, α-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylvinyltoluene,
Examples thereof include dimethylstyrene, chlorostyrene, and vinylnaphthalene.

As the vinyl cyanide monomer, for example,
Acrylonitrile, methacrylonitrile and the like can be mentioned.

The monomers copolymerizable with these monomer components include acrylic acid ester monomers, methacrylic acid ester monomers, vinyl carboxylic acid monomers such as acrylic acid and methacrylic acid, and acrylic acid monomers. Amide, methacrylamide and the like.

[0029] Among the monomers used for the component B, the amount of the aromatic vinyl monomer is 50 to 70% by weight.
Moldability and dimensional stability, which are characteristics of aromatic vinyl compounds, are impaired.

In the monomers used for the component B, the content of the vinyl cyanide monomer is 30 to 50% by weight. If the amount is less than 30% by weight, the chemical resistance and the surface hardness are insufficient. If it exceeds, the moldability decreases, which is not preferable.

The relative viscosity η _{rel of the} component B is 1.45 ≦ η
_rel ≤ 1.65, and if η _rel is less than 1.45,
If the strength is reduced, and if it exceeds 1.65, the moldability is undesirably reduced.

In order to obtain a molded article using the thermoplastic resin composition of the present invention, it is necessary to mix the above-mentioned component A and component B at a desired ratio. A thermoplastic resin composition can be easily obtained by blending both components in an emulsified state, a particle state, or a molten state, and melt-kneading.

In the thermoplastic resin composition of the present invention, it is necessary to mix the (A component) vinyl-based graft copolymer and the (B component) vinyl-based copolymer. The composition can be easily obtained by blending both components in an emulsified state, a particle state or a molten state, and melt-kneading.

Generally, a dry blend obtained by mixing with a mixer such as a tumbler or a Henschel mixer can be obtained by melting, kneading and extruding with an extruder.

Further, the thermoplastic resin composition of the present invention may contain a stabilizer, a plasticizer, a lubricant, a coloring agent, and the like, if necessary.

[0036]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention unless it departs from the gist of the invention. Hereinafter, “%” and “parts” are based on weight unless otherwise specified.

Examples 1-5 Preparation of Component A Graft Copolymer A-1 A polybutadiene latex (solid content: 30%) was placed in an autoclave.
%, Weight average particle size 0.35 μm) 333 parts, and then 234 parts of pure water, 0.005 parts of ferrous sulfate, 0.01 parts of disodium ethylenediaminetetraacetate and 0.3 parts of sodium aldehyde sulfoxylate are added, and the mixture is added under a nitrogen atmosphere. The stirred contents were kept at 50 ° C., and a monomer mixture consisting of 33 parts of acrylonitrile, 67 parts of styrene, 0.5 part of α-methylstyrene dimer and 0.2 part of benzoyl peroxide was continuously added to the latex over 5 hours. After the addition of the monomer mixture, 0.1 part of benzoyl peroxide was added, and further
The polymerization was completed by stirring at 70 ° C. for 2 hours.

The obtained latex was octadecyl-3
After adding 1.0 part of-(3,5-di-t-butyl-4-hydroxyphenyl) propionate (manufactured by Ciba Geigy, trade name: Irganox 1076), an aqueous solution containing 8 parts of calcium chloride was added, and the mixture was heated to 95 ° C. By stirring for 3 minutes to obtain a slurry. This slurry was dehydrated, washed with water, and dried to obtain a graft copolymer (A component).

The weight average molecular weight in this graft copolymer was 140,000. The weight average molecular weight as used herein refers to a single monomer comprising an aromatic vinyl monomer, a vinyl cyanide monomer and, if necessary, a vinyl monomer copolymerizable with the diene rubber polymer. Weight average molecular weight of the copolymer component of the monomer mixture and the copolymer component of the monomer mixture present in an ungrafted state. Specifically, the graft copolymer is represented by tetrahydrofuran (hereinafter referred to as T
HF) and left over night for 30 minutes in an ultrasonic cleaner to completely elute the ungrafted copolymer and then centrifuge at 12,000 rp.
The solution was centrifuged at 1 m for 1 hour to obtain a soluble matter, which was evaporated to dryness and dissolved in THF to prepare a THF solution (a). On the other hand, the THF-insoluble matter was dispersed in chloroform, the rubber was decomposed by ozonolysis, the graft chain was recovered, evaporated to dryness, and a solution (b) of this dissolved in THF was obtained. Then, the solution (c) obtained by mixing the solution (a) and the solution (b) is subjected to gel permeation chromatography (GP).
It is the molecular weight in terms of styrene measured in C). The ratio of acrylonitrile to styrene was 32/68 as measured by pyrolysis gas chromatography (PGC).

A-2 α-methylstyrene dimer used in A-1
A graft copolymer (A-2) was produced in the same manner except that 0.5 part of terpinolene was used instead of 0.5 part. The ratio of acrylonitrile to styrene in this graft copolymer was 31/69, and the weight average molecular weight was 180,00.
It was 0.

Preparation of Component B Copolymer B-1 100 parts of pure water, 2.5 parts of a 0.2% aqueous solution of potassium persulfate, 0.07 parts of tribasic calcium phosphate, and 24 parts of styrene were placed in an autoclave.
Parts, acrylonitrile 35 parts, t-dodecyl mercaptan
Add 0.6 parts and 0.1 parts of benzoyl peroxide and stir the contents in a nitrogen atmosphere at 100 ° C.
41 parts were continuously added over 2 hours at 100 ° C., 2 hours at 103 ° C., and 3 hours at 107 ° C. over a total of 7 hours.

After completion of the addition, the temperature was raised to 117 ° C. and the mixture was stirred for 2 hours to complete the polymerization. After cooling, hydrochloric acid was added to the polymerization solution, neutralized, dehydrated, and dried to obtain copolymer beads (component B). I got

The relative viscosity ηrel of this copolymer is 1.
47, and the ratio of acrylonitrile to styrene is 34
/ 66.Note that the relative viscosity ηrel is
When a fixed volume of sample solution is
The time required for flowing is measured at a temperature of 23 ° C.
To determine the relative viscosity ηrel. ηrel = t / t ₀ t: Resin test using methyl ethyl ketone (MEK) as solvent
Time when the 1% by weight solution flowed down t ₀ : Time during which the solvent MEK flows down

B-2 In B-1, 24 parts of styrene initially charged to the autoclave were changed to 22 parts, 35 parts of acrylonitrile were changed to 42 parts, and 0.6 part of t-dodecylmercaptan was changed to 0.3 part, respectively. Then, a copolymer (B-2) was produced in the same manner as in B-1 except that polymerization was performed by changing 41 parts of styrene added during the polymerization to 38 parts.

The relative viscosity η _rel of this copolymer is 1.60
And the ratio of acrylonitrile to styrene was 40/60.

Comparative Examples 1-3 Preparation of Component A Graft Copolymer A-3 α-methylstyrene dimer used in A-1
A graft copolymer (A-3) was produced in the same manner except that 0.5 part of t-dodecyl mercaptan was used instead of 0.5 part. The ratio of acrylonitrile to styrene in this graft copolymer is 31/69, and the weight average molecular weight is
80,000.

Preparation of Component B Copolymer B-3 In B-1, 24 parts of styrene initially charged in the autoclave were changed to 27 parts, 35 parts of acrylonitrile were changed to 25 parts, and styrene 41 added during the polymerization was added. The copolymer (B) was prepared in the same manner as in B-1 except that the polymerization was carried out by changing the part to 48 parts.
-3) was produced.

The relative viscosity η _rel of this copolymer is 1.47
And the ratio of acrylonitrile to styrene was 25/75.

B-4 In B-3, 0.6 part of t-dodecyl mercaptan was added to 0.9 part.
A copolymer (B-4) was produced in the same manner as in B-3, except that the polymerization was carried out in place of the parts.

The relative viscosity η _rel of this copolymer is 1.42
And the ratio of acrylonitrile to styrene was 25/75.

The A-component graft copolymer and B-component copolymer obtained by the above method were mixed in a Henschel mixer according to the formulation shown in Table 1, and then 230 ° C. using a 40 mm extruder.
And melted and kneaded to prepare pellets. Table 1 was evaluated using the obtained pellets.

[0052]

[Table 1]

The physical properties were measured by the following methods. (1) Izod (Izod) Impact Strength A sample pellet was molded at 220 ° C. using an injection molding machine (IS-80CNV) manufactured by Toshiba Machine Co., Ltd. to produce a test piece. ASTM D-
The Izod impact strength was measured according to 256.

(2) Tensile Elongation Using an injection molding machine (IS-80CNV) manufactured by Toshiba Machine Co., Ltd., a sample pellet was molded at 220 ° C. to produce a test piece. ASTM D-
A tensile test was performed according to 638 to measure elongation.

(3) Melt flow rate (MFR) The melt flow rate was measured using sample pellets in accordance with JIS K-6874.

(4) Drop Weight Impact Strength Using an injection molding machine (IS-80CNV) manufactured by Toshiba Machine Co., Ltd., the sample pellet was molded at 230 ° C., and 2 mm × 90 mm.
A 90 mm square plate was prepared. JIS using this square plate
The falling weight impact strength was measured according to K-7211.

(5) Surface Hardness The surface hardness was measured according to JIS D-0202 (scratch hardness test method).

(6) Chemical resistance JIS K-7113 No. 1 type test piece was given a 50 mm bend and fixed to a jig, and then dioctyl phthalate (DOP)
Was applied, and the time until breakage when left at a temperature of 23 ° C. was expressed in minutes.

[0059]

As described above, the thermoplastic resin composition of the present invention is a resin composition having excellent impact strength, moldability, rigidity, surface hardness and chemical resistance. It has the feature that it can be widely used as a sheet material for equipment cases such as electronics and OA, and inner boxes for electric refrigerators.

Claims (1)

(57) [Claims] 1. A component (A) 10 parts by weight of a diene rubber polymer
In the presence of at least 60 parts by weight , the aromatic vinyl monomer 5
0 to 70% by weight, 30 to 50% by weight of a vinyl cyanide monomer, and, if necessary, more than 40 parts by weight of a monomer mixture composed of 0 to 20% by weight of a vinyl monomer copolymerizable therewith.
For example the following 90 parts by weight obtained by graft-polymerizing, and diene rubber polymer grafted aromatic vinyl monomer, a
A copolymer component of these monomer mixture is present in the copolymer component, and the ungrafted monomer mixture consisting thereof with copolymerizable vinyl monomer optionally vinyl cyanide monomer and requires a graft copolymer of 20 to 80% by weight is a weight average molecular weight ranging from greater than 200,000 than 120,000 total copolymer component, (B component) aromatic vinyl monomer 50 to 70 wt%, The relative viscosity ηrel obtained by copolymerizing 30 to 50% by weight of a vinyl cyanide monomer and, if necessary, 0 to 20% by weight of a vinyl monomer copolymerizable therewith is 1.45 ≦ ηrel ≦
A thermoplastic resin composition comprising 20 to 80% by weight of a copolymer having a range of 1.65.