KR960016593B1 - Method for manufacturing thermoplastic resin powder - Google Patents

Abstract

The resin powder is prepared by the method of the 1, 2 stages emulsion polymerizing a rubber polymer, unsaturated nitrile monomer and vinyl aromatic compound monomer and after treatment process to give a thermoplastic resin. Especially, an ion exchange water is introduced before carrying out after-treatment process toward the thermoplastic resin latex obtained by 1,2 stages to coagulate it. The thermoplastic resin powder has a good appearance and shock resistance.

Description

Manufacturing method of thermoplastic resin powder

The present invention relates to a method for producing a thermoplastic resin powder, and more particularly, to a method for producing a thermoplastic resin powder having good appearance and impact resistance.

In the manufacturing method of a resin obtained by graft polymerization of an unsaturated nitrile monomer to a rubber polymer and a vinylaromatic compound monomer copolymerizable therein (hereinafter referred to as "ABS resin"), in order to obtain a thermoplastic resin having excellent appearance in general, when producing ABS resin Although a small particle size rubber polymer having a very small particle size is used, this has a problem in that impact strength is lowered.

Such resins can be used in products requiring only excellent appearance of molded articles, but cannot be used in telephones, electrical and electronic products, and office equipment that require excellent appearance and impact resistance at the same time. As a method for compensating for this, Japanese Laid-Open Patent Publication No. 58-147414 proposes a method of controlling pH when coagulating latex of graft thermoplastic resin (hereinafter referred to as "ABS latex"). However, this technique can improve the impact resistance, but the coagulation particles are enlarged, so the appearance of the molded product is poor, and phosphoric acid should be used instead of inexpensive sulfuric acid to control the pH, thereby increasing the manufacturing cost.

The present inventors found that a thermoplastic resin having excellent impact and appearance can be obtained by adjusting the concentration of ion-exchanged water into the ABS latex and then adding it to the coagulating liquid before solidifying the ABS latex without damaging the physical properties of the ABS latex. The invention has been completed.

That is, the present invention is an initiator within 100 parts by weight of the monomer mixture of vinyl aromatic compound monomer copolymerizable with an unsaturated nitrile monomer 100 parts by weight of rubber polymer latex (solid content) having a solid content of 50% by weight or more and an average particle diameter of 0.1 to 1.0 micron. Add with chain transfer regulator.

At this time, the first step of graft polymerization by an emulsion polymerization method in which 0.2-2.0 parts by weight of an emulsifier (solid content) is added to the latex collectively before starting the graft polymerization, and then 50 to 150 parts by weight of mixed monomers in the polymerization system. And a second step of completing the graft polymerization by an emulsion polymerization method while adding an initiator and a chain transfer regulator, and a post process of solidifying, dehydrating, washing and drying the ABS latex obtained in the second step. It depends on the manufacturing method of a thermoplastic resin.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Rubbery polymers of rubber latex that can be used in the present invention include polybutadiene, acrylonitrile-butadiene copolymer, styrene-butadiene copolymer, isoprene rubber, chloroprene rubber, acrylic rubber, ethylene-propylene-diene rubber, and the like. These are used alone or in combination of two or more.

The monomers used to prepare the graft polymers of the present invention are unsaturated nitrile monomers and vinylaromatic compound monomers. As unsaturated nitriles, for example, acryronitrile, methacrylonitrile and the like are used. Examples of vinylaromatic compound monomers that may be used include styrene, alpha-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, chlorostyrene, vinylnaphthalene and mixtures thereof, which may be It can be used in combination of 2 or more types.

As radical polymerization initiator used in the graft polymerization, 2,4-dichlorobenzoyl peroxide, isobutyl peroxide, benzoyl peroxide, di-n-propyl peroxycarbonate, silical hydroperoxide, t-butyl hydroperoxide, di t-butyl hydroperoxide, t-butyl peroxy acetate and the like and compounds thereof. In addition, compounds composed of iron salts such as ferrous sulfate, and reducing agents such as tetralium pyrophosphate, sodium aldehyde sulfoxynate, textose, anhydrous crystalline glucose, and ethylene diamine tetrasodium acetate can be used. Merpentanes such as t-dodecylmercaptan, n-dodecylmercaptan and tert-dodecylmercaptan, mercaptan ethanol or the like, halogenated hydrocarbons such as terpenes and chloroform and carbon tetrachloride and the like This can be used.

In addition, when the monomer is used in the range of 50 to 150 parts by weight based on 100 parts by weight of the rubber polymer latex (solid content), the ratio of the polymer or copolymer grafted to the rubber polymer becomes very good. Suitable.

If the amount of the monomer is 150 parts by weight or more, a resin material excellent in impact resistance cannot be obtained. If the amount of the monomer is 50 parts by weight or less, particles of the thermoplastic resin powder are solidly formed during solidification, resulting in poor appearance of the molded product.

In the present invention, the monomer is divided into 100 parts by weight in the first step, within 50 to 150 parts by weight in the second step, and added to the polymerization system, but the total amount is adjusted to 50 to 150 parts by weight.

In the method of the present invention, the first step and the second step are all based on the emulsion polymerization method, but the emulsifiers which can be used at this time include sodium dodecyl sulfate, sodium ole sulfate, sodium dodecyl benzene sulfate, fatty acid alkali metal salts and fatty acid sulfate esters. Phosphorus alkali metal salts, potassium octadecyl sulfate, potassium dodecyl sulfate, potassium dodecyl benzene sulfate, potassium stearate sodium stearate, potassium rosinate sodium rosinate, rosin-so-off, fatty acid salts, etc. 2.0 parts by weight.

Solidification conditions for effectively achieving the object of the present invention is subjected to a pretreatment process to adjust the concentration by adding 20 to 200 parts by weight of ion-exchanged water to 100 parts by weight of the ABS latex prepared by the above method. In 20 parts by weight or less of ion-exchanged water, the appearance improvement effect is very small, and in 200 parts by weight or more, the bulk density of the ABS resin is low, resulting in poor workability. 100 to 500 parts by weight of a coagulant solution having a sulfuric acid concentration of 0.2 to 5% by weight was placed in a tank equipped with a stirrer, a heating heater and a thermometer, and started to be heated at room temperature at 100 to 500 rpm. Drop and start to solidify.

After completing the addition of ABS latex, the stirring rpm was raised to 150 to 350, and the temperature was raised to 70 ° C, stirred for 10 minutes, and then heated to 85 ° C for 20 minutes to firm the solidified ABS latex particles. It should be 0.8% or less.

Examples and Comparative Examples of the present invention are as follows. In the following examples, parts and percentages are based on weight.

Example 1

First step: The following material was filled in a reactor equipped with a cooler, a thermometer, a dropwise addition filter, a stirrer nitrogen gas inlet and a monomer, an emulsifier, and a polymerization initiator, and heated to 60 ° C.

Polybutadiene Latex (Solid) 50.0Parts

Styrene Part 18.1

Acrylonitrile 7.4 parts

0.8 parts of sodium oleate

0.02 parts potassium hydroxide

Textose Part 0.15

t-dodecyl mercaptan 0.27parts

0.10 part benzoyl peroxide

140.0 parts of ion-exchanged water

Here, the average particle size of the polybutadiene latex is 0.3 microns.

Furthermore, after stirring at 60 degreeC for 20 minutes, the following component was added and superposition | polymerization was performed for 1 hour.

Ferrous sulfate (FeSO ₄ · 7H ₂ O) 17.4 parts

Tetrasodium pyrophosphate 0.34part

0.05 parts of ion-exchanged water

Second step: After cooling the rubber latex to 65 to 63 ° C. in the first step, the graft polymerization additive component shown below is mixed, and one third thereof is continuously added to the rubber latex obtained in the first step for 15 minutes. It cooled to 62-58 degreeC, adding.

Styrene Part 17.4

7.1 parts acrylonitrile

Subsequently, after adding the following component, superposition | polymerization was performed, adding 2/3 of said remainder graft polymerization addition components continuously for 30 minutes.

t-docesil mercaptan 0.12part

Cumene Hydroperoxide 0.15part

0.25 parts benzoyl peroxide

When the polymerization proceeded to completion, the following components were added as antioxidants when the temperature reached 60 ° C. while cooling and stirring.

2-2 methylle-bis (4-methyl-6-phen-butylphenol) 0.28 parts

Sodium oleate 0.07parts

Deponex 702 (brand name) 0.02 part

1.70 parts of ion-exchanged water

After the completion of the polymerization was treated as follows.

* Post treatment process

Add 60 parts by weight of ion-exchanged water to 100 parts by weight of ABS latex, adjust the concentration, mix it for 20 minutes, and pre-treat. Then, add 90 parts by weight of coagulant solution containing 1.0% by weight of concentrated sulfuric acid to a coagulation bath, heat stir and reach 65 ℃ Pretreated ABS latex is added to solidify the latex, and then the temperature is raised to hold at 85 ° C. for 20 minutes to form particles in suspension state firmly. Then, dehydrated in a centrifuge, washed and dried. Drying was dried for 1 hour at 80 ° C speed dryer.

In order to evaluate general physical properties and appearance when mixed with AS resin, 33 parts of BS resin, 67 parts of AS resin (high viscosity 0.61 dl / g), 0.4 parts of magnesium stearate and 0.4 parts of ethylene-bis-steraroamide The pellets were prepared using a single screw extruder at 210 ° C., and the test specimens were prepared using a 5.3 oz. Injection machine, and the physical properties were measured by the following evaluation method.

[Assessment Methods]

1) Graft rate (wt%) of ABS latex; ABS latex was dissolved in isopropyl alcohol treated acetone and separated into soluble and insoluble parts after centrifugation. The insoluble parts were washed, and the graft ratio was calculated after dry basis weight.

2) Intrinsic Viscosity of ABS Latex (dl / g): Isopropyl alcohol is added to ABS Latex to make a solid, and after adding acetone to it, centrifugation extracts FREE AS polymer, removes the grafted part and evaporates acetone. The extracted FREE AS polymer was dissolved in a solvent (DMF) and the viscosity was measured using a Uberode viscometer at 25 ° C.

3) BULK DENSETY of thermoplastic resin powder; POWDER obtained by dehydrating, washing and drying ABS latex was measured by the method of ASTM D1895.

4) IZOD impact strength; NOTCHED impact specimens of 1/4 "thickness were measured by ASTM D256 method.

5) MELT FLOW INDEX; It was measured by ASTM D1238 method.

6) tensile strength and elongation; It was measured by ASTM D638 method.

7) VICAT softening temperature; It was measured by ASTM D15-25 method.

8) glossiness; It was measured by ASTM D15-253 method.

9) appearance; Appearance score was calculated by adding the total number of pinholes shown on the surface of five test specimens of size 4 inches x 4 inches x 1/8 inch to the scores of the five test specimens based on Table 1.

TABLE 1

Example 2

In the post-treatment process of Example 1, except that 40 parts by weight of ion-exchanged water was pretreated with ABS latex, the post-treatment process was performed in the same manner as in Example 1, and the results were evaluated in the same manner as in Example 1, and the results are shown in Table 2. It was.

Comparative Example 1

In the post-treatment process of Example 1, 150 parts by weight of a concentrated sulfuric acid 1.0% by weight coagulating solution was heated and stirred, and the temperature was reached to 60 ° C., except that ABS latex was added without pretreatment to solidify ABS latex, Evaluation in the same manner as in the same example is shown in Table 2.

Comparative Example 2

Except for using polybutadiene latex having a mean particle diameter of 0.1 micron in the first step of Example 1, it was evaluated in the same manner as in Example 1 and the results are shown in Table 2. It was.

TABLE 2

Claims (4)

The thermoplastic resin latex obtained by the first and second processes in the method for producing a thermoplastic resin obtained by the first step, the second step, and the post-treatment step of the rubber polymer, the unsaturated nitrile monomer, and the vinyl aromatic compound monomer by the emulsion polymerization method. A method for producing a thermoplastic resin powder, wherein the ion-exchanged water is added and solidified before the post-treatment step is performed. The method for producing a thermoplastic resin powder according to claim 1, wherein the ion-exchanged water is added in an amount of 20-200 parts by weight based on 100 parts by weight of the thermoplastic resin obtained through the first and second processes. The method for preparing a thermoplastic resin powder according to claim 1, wherein the method of solidifying the thermoplastic resin latex comprises introducing a thermoplastic resin into a coagulating solution in which sulfuric acid or an alkaline earth metal salt is adjusted to 0.5 to 2.0% by weight. The method for producing a thermoplastic resin powder according to claim 3, wherein the coagulating solution uses 50 to 300 parts by weight based on 100 parts by weight of the thermoplastic resin.