KR20000014171A - Process for preparing thermoplastic resin latex - Google Patents

Abstract

PURPOSE: A thermoplastic resin latex is prepared which has a good impact resistance, whiteness and detained brightness. CONSTITUTION: A rubber latex having 0.2-0.4 micrometer of average particle size is prepared by acid coagulating small diameter of rubber latex having 0.05-0.2 micrometer of particle size and more than 85 % of gel content, and the other rubber latex having 0.2-0.4 micrometer of particle size and 60-80 % of gel content is prepared by emulsion polymerization. 20-40 Weight % of cyanated vinyl compound and 60-80 weight % of aromatic vinyl compound are graft-copolymerized at 50-80 degree C in the presence of 0.1-0.7 weight part of water soluble initiator and 20-70 weight parts of a mixed rubber latex of 32-80 weight % of rubber latex having more than 85 % of gel content and 20-68 weight % of rubber latex having 60- 80 % of gel content.

Description

Thermoplastic resin latex manufacturing method excellent in impact resistance, whiteness and retention gloss

The present invention relates to a method of manufacturing a thermoplastic resin having high impact strength and excellent whiteness and retention gloss at a high speed. More specifically, the vinyl cyanide compound is controlled while controlling the ratio of rubbery polymer latex having a similar particle size and different gel contents. The present invention relates to a method for producing a thermoplastic resin having a high impact strength and excellent whiteness and retention gloss by graft copolymerization of an aromatic vinyl compound with a short time.

Generally in the production of ABS or similar resins, thermoplastic resins such as styrene-acrylonitrile copolymer, polystyrene, polymethyl methacrylate and the like are used in the diene rubber component, i.e., polybutadiene, styrene-butadiene copolymer, acrylonitrile- It is well known to graft copolymer rubber latex such as butadiene copolymer and then add it to the thermoplastic resin to improve impact resistance.

However, it is known that it is difficult to improve whiteness and retention gloss at the same time when improving impact resistance in general ABS manufacturing. On the contrary, in order to enhance whiteness and retention gloss, it is known that the impact resistance is inevitably reduced.

As described above, the graft polymerization is performed by emulsion polymerization. In the conventional method, it takes about 5 hours in total, and when the polymerization time is shorter than this, sufficient graft rate is not achieved. It may be slightly improved, but the whiteness is lowered and the retention gloss is also reduced during processing.

Accordingly, an object of the present invention is to provide a method for producing a thermoplastic resin latex having excellent impact strength, whiteness and retention gloss at high speed without the above problems.

Therefore, the present inventors earnestly studied to achieve the above object, and the water-soluble catalyst was used for about 4 hours or so while appropriately controlling the ratio of two types of mixed rubbery latex having a gel content of 85% or more and 60-80%. By graft copolymerization of vinyl cyanide compound and aromatic vinyl compound for a short time, the rubber latex occlusion resin and surface grafting are appropriately distributed, so the impact strength and whiteness are very high, and the degradation of retention gloss during processing can be minimized. It has been found that the thermoplastic latex can be prepared to complete the present invention.

Specifically, the present invention relates to a vinyl cyanide compound and an aromatic vinyl compound (20-40 wt%, 60-80 wt%, respectively) in the presence of a mixed rubber latex of a rubber latex having a gel content of 85% or more and a rubber latex having a gel content of 60-80%. The present invention relates to a thermoplastic resin latex having a property of graft copolymerization within 4 hours using a water-soluble initiator, thereby improving impact resistance and whiteness while minimizing a decrease in retention gloss during processing.

Rubber latex of the present invention is a rubber latex and gel prepared by the emulsion polymerization method having a gel content of more than 85% and a small diameter rubber latex having a particle diameter of 0.05-0.2 μm by coagulation with acid average particle diameter of 0.2-0.4 μm A mixture of rubber latexes prepared by emulsion polymerization with a content of 60-80% and a particle diameter of 0.2-0.4 μm is used.

The vinyl cyanide compound and the aromatic vinyl in the presence of 32 to 80% by weight of the rubber latex having a gel content of 85% or more and 20 to 70% by weight of the mixed rubber latex of the rubber latex having a gel content of 60 to 80% 30-60 parts by weight of the compounds (20-40% by weight, 60-80% by weight), respectively, are graft copolymerized.

At this time, the water-soluble initiator is used 0.1 to 0.7 parts by weight and the appropriate reaction temperature is about 50 ℃-80 ℃.

The method of the present invention can be divided into two types of rubber latex production process and graft copolymerization process.

Hereinafter, the present invention will be described in detail.

1) rubber latex manufacturer

When a small-diameter rubber latex having a particle diameter of 0.05-0.2 μm is prepared by a reaction conversion ratio of 90% or more by a conventional emulsion polymerization method, its gel content is 85% or more, and the swelling index is generally 20 or less. In addition, administration of a gel content modifier (eg, dodecyl mercaptan) and butadiene can lower the gel content and increase the particle size. In the present invention, in order to properly control the degree of internal penetration of the resin during graft polymerization, a rubber latex having a gel content of 85% or more and a swelling index of 20 or less and a rubber content of 60-80% or more of a rubber latex having a swelling index of 24 or more, Used by mixing.

The measurement of the swelling index and the gel content defined in the present invention, after coagulating and washing rubber latex, dried in a vacuum oven at 40 ℃ for one day, 1 g of rubber in 100 g of toluene and left for 48 hours, Measure the weight of the part and the insoluble part.

The rubber latex having a gel content of 85% or more used in the present invention is prepared in two steps to prepare a small diameter rubber latex by a common emulsion polymerization method and agglomerate it with an acid to produce a large diameter rubber latex. Examples of the small-diameter rubber latex include a copolymer of polybutadiene, butadiene and a copolymerizable monomer (butadiene content in the copolymer of 50% by weight or more), and a specific example of a monomer copolymerizable with butadiene is styrene. Aromatic compounds, such as (alpha) -methylstyrene and vinyltoluene, and vinyl cyanide compounds, such as an acrylonitrile and methacrylonitrile, etc. are mentioned. The large-diameter rubber latex having a particle size of 0.2 to 0.4 µm can be obtained using the above-mentioned small-diameter rubber latex using an agglomeration method with an acid. In this case, generally, the factors governing the aggregation include the amount of emulsifier, pH, temperature, amount of solids, and the like, and the desired particle size can be obtained by controlling these factors well.

The rubber latex having a gel content of 85% or more is prepared by adding butadiene and a gel content regulator in a conventional emulsion polymerization method for preparing small diameter rubber latex.

2) Graft Copolymerization Process

Graft copolymerization in this invention is performed using a conventional emulsifier, a molecular weight modifier, etc.

Examples of the emulsifier include rosin salts of potassium rosin and sodium rosin, fatty acid salts such as potassium oleate and sodium stearate, and alkyl aryl sulfonates.

Examples of the molecular weight regulator include mercaptans of t-dodecyl mercaptan and n-dodecyl mercaptan or terpins such as tabinolten, dipentene and t-terpiene, and halogenated hydrocarbons such as chloroform and carbon tetrachloride. Can be used.

Examples of the aromatic vinyl compound used in the graft copolymerization include styrene, α-methylstyrene, and vinyl toluene. Acrylonitrile and methacrylonitrile may be used as the vinyl cyanide compound.

As an initiator, oil-soluble organic oxides, such as cumene hydroperoxide and diisopropyl benzene hydroperoxide, and pivalate type, such as t-butyl peroxy pivalate, potassium persulfate, ammonium persulfate, and alkyl hydroperoxide A redox catalyst of a water-soluble catalyst such as water and a reducing agent can be used.

Oil-soluble organic oxides cause excessive penetration into rubber particles during graft polymerization, and the use of a persulfate system makes it difficult to achieve a sufficient graft rate when the graft polymerization time is short. Therefore, in the present invention, an initiator having a moderate water solubility property is used. Was appropriate.

As the method of adding each component during graft copolymerization, a method of administering the total amount of each component at once, a method of divided administration, a method of continuously administering the total amount or part thereof, and the like can be used. Partial division of the vinyl cyanide compound resulted in 25-35% by weight relative to the weight of the monomer to be batch administered.

In the present invention, it is used by dividing into two stages or three stages. In the first stage, all the components are added in a batch, and in the second stage, the emulsifier, the monomer, the molecular weight regulator, and the water are made into an emulsion and continuously added. The initiator is also added continuously. In step 3, the temperature is raised by 5 ° C. higher than step 2 in order to increase the reaction conversion rate. After the reaction is completed, the latex is solidified with 5-10% sulfuric acid, washed and dried to obtain a graft copolymer of powder.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. In Examples and Comparative Examples, parts and% means parts by weight and weight%. The physical properties measured in Examples and Comparative Examples of the present invention were performed by the following method.

A. Izod Impact Strength

It measured according to the method of ASTMDZ56. Specimen thickness is 1/4 ".

B. Melt fIow index (MI)

It measured by the ASTMD638 method under the conditions of 220 degreeC and 10 kg.

C. Surface Gloss

It was measured by the ASTMD528 method at a 60 degree angle.

D. Stay Gloss

Measured by the ASTM method as described above C, but in order to observe the degradation of the surface gloss during processing, stayed in the injection molding machine 230 ℃, 15 minutes and then injected to measure the surface gloss.

E. Graft Rate

The graft copolymer powder obtained above was dissolved in acetone and calculated according to the following formula. The graft ratio ranges from 20 to 35% to suit the purpose of the present invention.

F. White Index: WI

Whiteness was measured for the specimens after injection by the ASTME313-73 method.

G. Coagulum%

After the reaction was completed, the manure was filtered through a 50 mesh net and dried to express the weight percent based on the total solids and monomers administered during the reaction.

The specimen used in the measurement of the physical properties was produced by injection molding at 230 ℃.

<Example 1>

1) Preparation of rubber latex with gel content of 85% or more

100 parts by weight of 1,3-butadiene, 6 parts by weight of potassium oleate, 1 part of potassium persulfate, 0.5 part of tertiary dodecyl mercaptan, and 100 parts of water were placed in a nitrogen-substituted reactor, and the reaction temperature was raised to 50 ° C. to proceed with the reaction. I was. When the conversion reached 30-40%, 0.5 parts by weight of tertiary dodecyl mercaptan was added and the reaction temperature was raised to 65 ° C. After the conversion reached 85-95%, the reaction was stopped by administration of diethylhydroxy amine, and the unreacted monomer was recovered to obtain a small diameter rubber latex having an average particle diameter of 0.09 μm, a gel content of 85%, and a swelling index of 20. Got. A rubber latex having an average particle diameter of 0.29 µm was prepared using this small-diameter rubber latex using an agglomeration method with an acid.

2) Preparation of rubber latex with gel content of 60-80% or more

100 parts by weight of 1,3-butadiene, 0.3 parts by weight of potassium rosin acid salt, 0.4 parts by weight of potassium oleate salt, 0.7 parts by weight of potassium persulfate, 0.7 parts by weight of tertiary dodecyl mercaptan, 0.2 parts by weight of sodium carbonate and 0.2 parts of potassium hydrogencarbonate By weight, 100 parts by weight of water was put in a nitrogen-substituted reactor, the reaction was carried out for 30-60 hours at a reaction temperature of 55-85 ℃ to prepare a rubber latex with a gel content of 66%, an average particle diameter of 0.28 μm.

3) Preparation of Graft Copolymer

Stage 1

Ingredient amount

1) 30 parts rubber latex

2) 17 parts of rubber latex

0.3 parts of potassium rosin

100 parts of water

Styrene Part 15.9

Acrylonitrile 6.2 parts

α-dodecyl mercaptan0.1part

Dextrose 0.035 Part

Sodium pyrrolate 0.03parts

Ferrous Sulfate 0.001 parts

Alkylhydroperoxide 0.04 parts

The rubber latex and the reaction components were collectively administered in a semi-aperture, and polymerization was carried out for 1 hour while the reaction temperature was raised to 55 ° C.

Tier 2

Ingredient amount

Potassium Rosinate0.8part

10 parts water

Styrene Part 2.2

Acrylonitrile 8.7 parts

Dextrose 0.072 Part

Sodium pyrrolate 0.059 parts

Ferrous Sulfate 0.001 parts

Alkyl hydroperoxide side 0.023 parts

The monomer and water in the above components were made into an emulsion and continuously administered over 1 hour and 30 minutes, and an aqueous reducing agent solution and an initiator were continuously administered over 1 hour and 30 minutes. At this time, the reaction temperature was 65 ° C.

Tier 3

Amount

3.5 parts water

Dextrose 0.067 Part

Sodium pyrrolate 0.049 parts

Ferrous Sulfate 0.001 parts

Alkyl hydroperoxide side 0.020 parts

After the completion of the two-step reaction, all of the above components were collectively administered to the reactor and heated to 70 ° C. for 30 minutes to terminate the reaction. The reaction rate at this time was 98.7%. An antioxidant was added thereto, followed by coagulation with an aqueous 5-10% sulfuric acid solution, followed by washing and drying to obtain a graft copolymer of powder.

The graft copolymer of the obtained powder was mixed with a styrene-acrylonitrile co-polymer (SAN) having a weight average molecular weight of about 130,000 and an acrylonitrile content of about 24%, and an external lubricant and a heat stabilizer were added to give a final rubber content of 16 The specimen was prepared by extrusion molding at 220 ° C. and then injection molded at 230 ° C., and the retention specimen was prepared by dwelling at that temperature for 15 minutes.

<Example 2>

1) Preparation of rubber latex with gel content of 85% or more

2) Preparation of rubber latex with gel content of 60-80%

It carried out similarly to Example l.

3) Preparation of Graft Copolymer

Prepared in the same manner as in Example 1 but in step 1 1) the amount of rubber latex was adjusted from 30 to 20 2) the amount of rubber latex was adjusted from 17 to 27. Post-processing and specimen preparation were also performed in the same manner as in Example 1, and the physical properties thereof are shown in Table 1.

Comparative Example 1

Prepared in the same manner as in Example 1 but in step 1 1) without administering the rubber latex 2) was administered only 47 parts rubber latex.

Post-processing and specimen preparation were also performed in the same manner as in Example 1, and the physical properties thereof are shown in Table 1.

Comparative Example 2

Prepared in the same manner as in Example 1 except that in step 1 1) only 47 parts of rubber latex and 2) was not administered rubber latex.

Post-processing and specimen preparation were also performed in the same manner as in Example 1, and the physical properties thereof are shown in Table 1.

Comparative Example 3

In the same manner as in Example 1, but in step 1 1) the amount of rubber latex from 30 to 10 2) the amount of rubber latex was adjusted from 17 to 37.

Post-processing and specimen preparation were also performed in the same manner as in Example 1, and the physical properties thereof are shown in Table 1.

<Comparative Example 4>

Prepared in the same manner as in Example 1, but in step 1 the amount of rubber latex was adjusted from 30 to 42 2) the amount of rubber latex from 17 to 5.

Post-processing and specimen preparation were also performed in the same manner as in Example 1, and the physical properties thereof are shown in Table 1.

Example Comparative Example One 2 One 2 3 4 Izod notch, impact strength, 20 ℃ (kg cm / cm) 31 30 22 31 23 29 Liquidity Index (MI) 17.9 17.0 15.3 17.9 15.3 17.6 Surface gloss (60 degrees) 101 102 97 95 97 95 Retention gloss (60 degrees) (230 ℃, 15 minutes) 98 97 96 85 95 88 Whiteness 54 55 50 43 50 44 Graft Rate ^* 28 27 30 25 28 25 Conversion rate ^* 98.7 98.9 97.7 98.9 98.7 98.7 Coagulant after reaction 0.005 0.005 0.01 0.04 0.02 0.04

* Characteristics of the graft polymer produced in each example

Using a water soluble catalyst, graft copolymerization of vinyl cyanide compound and aromatic vinyl compound in a short time of about 4 hours using a water-soluble catalyst while controlling the ratio of the rubber latex having a gel content of 85% or more and the rubber latex of 60-80% into the rubber latex of the resin The thermoplastic latex prepared by controlling the penetration and surface grafting of the resin is improved in impact strength and excellent in whiteness and retention gloss.

Claims (11)

In preparing the thermoplastic resin composition, 40 to 70 parts by weight of a mixture of rubber latex with a gel content of 85% or more and a rubber latex with a gel content of 60 to 80% and 30 to 60 parts by weight of a vinyl cyanide compound and an aromatic vinyl compound within 4 hours in a reaction solution containing a water-soluble initiator. The manufacturing method of the thermoplastic resin composition which makes graft copolymerization. The method of claim 1, wherein Preparation of a thermoplastic resin composition comprising a mixture of rubber latex having an average particle diameter of 0.2-0.4 μm, 32-80% by weight rubber latex having a gel content of 85% or more and 20-68% by weight rubber latex having a gel content of 60-80% Way. The method of claim 1, Rubber latex is a copolymer having a butadiene content of at least 50% by weight in a copolymer of polybutadiene or butadiene with a monomer copolymerizable therewith. A method for producing a thermoplastic resin composition selected from the group consisting of acrylonitrile and methacrylonitrile. The method of claim 1, wherein A method for producing a thermoplastic resin composition, wherein the vinyl cyanide compound and the aromatic vinyl compound are 20-40 wt% and 60-80 wt%, respectively. The method of claim 1, A method for producing a thermoplastic resin composition wherein the aromatic vinyl compound is selected from the group consisting of styrene, α-methylstyrene and vinyltoluene. The method of claim 1, A method for producing a thermoplastic resin composition, wherein the vinyl cyanide compound is selected from the group comprising acrylonitrile and methacrylonitrile. The method of claim 1, A method for producing a thermoplastic resin composition, wherein the water-soluble initiator is selected from the group consisting of potassium persulfate, sodium persulfate, ammonium persulfate and alkyl hydroperoxide. The method of claim 1, A method for producing a thermoplastic resin composition having a reaction temperature of 50 to 80 ° C. during graft co-polymerization. The method of claim 1, A method for producing a thermoplastic resin composition in which a total amount of the aromatic vinyl compound and the vinyl cyanide compound are administered once, in a divided dose, or continuously or entirely or partially. The method of claim 9, A method for producing a thermoplastic resin composition in which the content of a vinyl cyanide compound is 25 to 35% by weight relative to the total monomers to which the vinyl cyanide compound is administered when the aromatic vinyl compound and the vinyl cyanide compound are administered. In preparing the thermoplastic resin, a) 15-37 parts by weight of polybutadiene rubber having a gel content of at least 85% and an average particle diameter of 0.2-0.4 μm; Ii) 10-32 parts by weight of polybutadiene rubber having a gel content of 60-80% and an average particle diameter of 0.2-0.4 μm; Viii) 5.5 to 7.7 parts by weight of acrylonitrile and Iii) 14.3-16.5 parts by weight of styrene Reacting for about 1 hour while increasing the temperature to 55 ° C. after the batch administration to a reaction solution containing alkyl hydroperoxide as a polymerization initiator; b) continuously administering a reaction solution containing 7.8-10.8 parts by weight of acrylonitrile, 20.2-23.2 parts by weight of styrene and an alkyl hydroperoxide for about 1 hour and 30 minutes at a temperature of 65 ° C; c) reacting the reaction solution containing alkyl hydroperoxide for about 30 minutes at a temperature about 5 ° C. higher than step b) after the batch administration. Method for producing a thermoplastic resin composition comprising a.