METHOD OF PREPARING GRAFT COPOLYMER AND METHOD OF PREPARING THERMOPLASTIC RESIN COMPOSITION INCLUDING THE SAME

Abstract

Disclosed is a method of preparing a graft copolymer and a method of preparing a thermoplastic resin composition including the prepared graft copolymer. Also disclosed is a method of preparing a graft copolymer including a process of adding an aromatic vinyl monomer and a vinyl cyanide monomer to a conjugated diene rubber latex that is enlarged with a polymer particle diameter control agent that has a specific glass transition temperature and an average particle diameter in a specific ratio to an average particle diameter of a conjugated diene rubber latex, and graft-polymerizing the same; and a method of preparing a thermoplastic resin composition including the prepared graft copolymer.

Also disclosed is a graft copolymer prepared using the conjugated diene rubber latex enlarged with the polymer particle diameter control agent exhibiting the synergistic effect of improving both impact strength and fluidity.

Claims

1. A method of preparing a graft copolymer, the method comprising: adding a polymer particle diameter control agent to a conjugated diene rubber latex to prepare an enlarged conjugated diene rubber latex; and graft-polymerizing the enlarged conjugated diene rubber latex with an aromatic vinyl compound and a vinyl cyanide compound to prepare a vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer, wherein the polymer particle diameter control agent is a copolymer comprising 82 to 99% by weight of an alkyl acrylate and 1 to 18% by weight of an unsaturated acid compound and has a glass transition temperature of 0 to 10.5° C., and a ratio (PS.sub.1/PS.sub.2) of an average particle diameter (PS.sub.1) of the polymer particle diameter control agent to an average particle diameter (PS.sub.2) of the conjugated diene rubber latex is 0.85 to 1.13.

2. The method according to claim 1, wherein the polymer particle diameter control agent has an average particle diameter of 500 to 2,000 Å.

3. The method according to claim 1, wherein the polymer particle diameter control agent has single glass transition temperature.

4. The method according to claim 1, wherein the polymer particle diameter control agent is added in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the conjugated diene rubber latex based on a solid.

5. The method according to claim 1, wherein the alkyl acrylate is one or more selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylbutyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, heptyl acrylate, n-pentyl acrylate, and lauryl acrylate.

6. The method according to claim 1, wherein the unsaturated acid compound is one or more selected from the group consisting of (meth)acrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, citraconic acid, and anhydrides thereof.

7. The method according to claim 1, wherein the conjugated diene rubber latex has an average particle diameter of 500 to 1,500 Å.

8. The method according to claim 1, wherein, in the step of adding a polymer particle diameter control agent, the conjugated diene rubber latex is elevated to a temperature of 45 to 55° C., and then the polymer particle diameter control agent is added thereto, followed by stirring for 20 to 40 minutes.

9. The method according to claim 1, wherein the enlarged conjugated diene rubber latex has an average particle diameter of 2,500 to 4,500 Å.

10. The method according to claim 1, wherein, in the step of graft-polymerizing, 40 to 70% by weight (based on a solid) of the enlarged conjugated diene rubber latex based on a solid is graft-polymerized with 5 to 20% by weight of the vinyl cyanide compound and 17 to 40% by weight of the aromatic vinyl compound.

11. The method according to claim 1, further comprising a step of agglomerating the vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer.

12. A method of preparing a thermoplastic resin composition, the method comprising: adding a polymer particle diameter control agent to a conjugated diene rubber latex to prepare an enlarged conjugated diene rubber latex; graft-polymerizing the enlarged conjugated diene rubber latex with an aromatic vinyl compound and a vinyl cyanide compound to prepare a vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer; and feeding the prepared vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer and an aromatic vinyl compound-vinyl cyanide compound copolymer into an extruder and melt-kneading the same, followed by extrusion, wherein the polymer particle diameter control agent is a copolymer comprising 82 to 99% by weight of an alkyl acrylate and 1 to 18% by weight of an unsaturated acid compound and has a glass transition temperature of 0 to 10.5° C., and a ratio (PS.sub.1/PS.sub.2) of an average particle diameter (PS.sub.1) of the polymer particle diameter control agent to an average particle diameter (PS.sub.2) of the conjugated diene rubber latex is 0.85 to 1.13.

13. A thermoplastic resin composition, prepared by the method according to claim 11, wherein an impact strength of the thermoplastic resin composition measured according to ASTM D1238 using a specimen of the thermoplastic resin composition with a thickness of ¼″ is 27 kgf.Math.cm/cm or more.

Description

EXAMPLE

[0089] Preparation Example A-1: Polymer Particle Diameter Control Agent Preparation

[0090] 98.3 parts by weight of distilled water, 0.05 parts by weight of sodium dioctyl sulfosuccinate as an emulsifier, and 0.6 parts by weight of potassium persulfate as an initiator were fed into a reactor, and temperature was elevated to 80° C. while stirring, followed by allowing to stand for 3 minutes.

[0091] Meanwhile, 47.5 parts by weight of deionized water, 1 part by weight of sodium dioctyl sulfosuccinate, 2 parts by weight of methyl acrylate (MA), 1.0 part by weight of ethyl acrylate (EA), 80.9 parts by weight of butyl acrylate (BA), and 16.1 parts by weight of methacrylic acid (MAA) were fed and uniformly mixed to prepare a reaction solution.

[0092] Polymerization was carried out while continuously feeding the reaction solution into the reactor over 5 hours. The polymerization was terminated when a polymerization con version rate was 98%. Finally, a polymer particle diameter control agent having an average particle diameter of 1,100 Åwas obtained. Here, a glass transition temperature was 0.5° C.

[0093] <Preparation Examples A-2 to A-11: Polymer Particle Diameter Control Agent Preparation >

[0094] Experiments were carried out in the same manner as in Preparation Example A-1, except that the components and contents summarized in Tables 1 and 2 were used to prepare polymer particle diameter control agents.

[0095] <Preparation Example A-12: Polymer Particle Diameter Control Agent Preparation >

[0096] 98.3 parts by weight of distilled water, 0.05 parts by weight of sodium dioctyl sulfosuccinate as an emulsifier, and 0.6 parts by weight of potassium persulfate as an initiator were fed into a reactor, and temperature was elevated to 80° C. while stirring, followed by allowing to stand for 3 minutes. Meanwhile, 14.3 parts by weight of deionized water, 0.3 parts by weight of sodium dioctyl sulfosuccinate, 29.7 parts by weight of methyl acrylate (MA), 0.2 parts by weight of ethyl acrylate (EA), and 0.1 parts by weight of butyl acrylate (BA) were uniformly mixed to prepare Reaction Solution 1. The prepared Reaction Solution 1 was continuously fed into the reactor over 90 minutes. Next, 33.2 parts by weight of deionized water, 0.7 parts by weight of sodium dioctyl sulfosuccinate, 67.3 parts by weight of methyl acrylate (MA), and 2.7 parts by weight of methacrylic acid (MAA) were uniformly mixed to prepare Reaction Solution 2. Polymerization was carried out while continuously feeding the prepared Reaction Solution 2 into the reactor over 3 hours and 30 minutes. The polymerization was terminated when the polymerization conversion rate was 98%.

[0097] Finally, a polymer particle diameter control agent having an average particle diameter of 1,100 Å was obtained.

[0098] The resultant polymer particle diameter control agent had a core-shell structure and two glass transition temperatures of 1.2° C. and 9.7° C.

[0099] <Preparation Example B-1: Conjugated Diene Rubber Latex Preparation >

[0100] 75 parts by weight of deionized water, 90 parts by weight of 1,3-butadiene as a monomer, 2.7 parts by weight of a dimer acid potassium salt (Cas No. 67701-19-3) as an emulsifier, 0.08 parts by weight of potassium carbonate (K.sub.2CO.sub.3) as an electrolyte, 0.1 parts by weight of tertiary dodecyl mercaptan (TDDM) as a molecular weight regulator, 0.15 parts by weight of tertiary butyl hydroperoxide as an initiator, 0.06 parts by weight of dextrose, 0.005 parts by weight of sodium pyrophosphate, and 0.0025 parts by weight of ferrous sulfate were fed batchwise into a polymerization reactor filled with nitrogen, and polymerization was initiated at 55° C. 0.25 parts by weight of potassium persulfate was fed batchwise at a polymerization conversion rate of 30 to 40% into the polymerization reactor, and then polymerization was performed while elevating the temperature up to 72° C. Next, 10 parts by weight of 1,3-butadiene were fed batchwise into the polymerization reactor at a polymerization conversion rate 60 to 70% of, and then the polymerization was terminated at a polymerization conversion rate of 95%. Here, the average particle diameter of the conjugated diene rubber latex was 1,250 Å.

[0101] <Preparation Example B-2: Conjugated Diene Rubber Latex Preparation >

[0102] 75 parts by weight of deionized water, 90 parts by weight of 1,3-butadiene as a monomer, 3 parts by weight of a dimer acid potassium salt (Cas No. 67701-19-3) as an emulsifier, 0.15 parts by weight of potassium carbonate (K.sub.2CO.sub.3) as an electrolyte, 0.1 parts by weight of tertiary dodecyl mercaptan (TDDM) as a molecular weight regulator, 0.15 parts by weight of tertiary butyl hydroperoxide as an initiator, 0.06 parts by weight of dextrose, 0.005 parts by weight of sodium pyrophosphate, and 0.0025 parts by weight of ferrous sulfate were fed batchwise into a polymerization reactor filled with nitrogen, and polymerization was initiated at 55° C. 0.3 parts by weight of potassium persulfate was fed batchwise at a polymerization conversion rate of 30 to 40% into the polymerization reactor, and then polymerization was performed while elevating the temperature up to 72° C. Next, 10 parts by weight of 1,3-butadiene were fed batchwise into the polymerization reactor at a polymerization conversion rate 60 to 70% of, and then the polymerization was terminated at a polymerization conversion rate of 95%. Here, the average particle diameter of the conjugated diene rubber latex was 1,060 Å.

[0103] <Preparation Example B-3: Conjugated Diene Rubber Latex Preparation >

[0104] 75 parts by weight of deionized water, 90 parts by weight of 1,3-butadiene as a monomer, 2.9 parts by weight of a dimer acid potassium salt (Cas No. 67701-19-3) as an emulsifier, 0.1 parts by weight of potassium carbonate (K.sub.2CO.sub.3) as an electrolyte, 0.1 parts by weight of tertiary dodecyl mercaptan (TDDM) as a molecular weight regulator, 0.15 parts by weight of tertiary butyl hydroperoxide as an initiator, 0.06 parts by weight of dextrose, 0.005 parts by weight of sodium pyrophosphate, and 0.0025 parts by weight of ferrous sulfate were fed batchwise into a polymerization reactor filled with nitrogen, and polymerization was initiated at 55° C. 0.3 parts by weight of potassium persulfate was fed batchwise at a polymerization conversion rate of 30 to 40% into the polymerization reactor, and then polymerization was performed while elevating the temperature up to 72° C. Next, 10 parts by weight of 1,3-butadiene were fed batchwise into the polymerization reactor at a polymerization conversion rate 60 to 70% of, and then the polymerization was terminated at a polymerization conversion rate of 95%. Here, the average particle diameter of the small-diameter rubber latex was 1,180 Å.

[0105] <Preparation Example B-4: Conjugated Diene Rubber Latex Preparation >

[0106] 75 parts by weight of deionized water, 92 parts by weight of 1,3-butadiene as a monomer, 2.3 parts by weight of a dimer acid potassium salt (Cas No.67701-19-3) as an emulsifier, 0.08 parts by weight of potassium carbonate (K.sub.2CO.sub.3) as an electrolyte, 0.1 parts by weight of tertiary dodecyl mercaptan (TDDM) as a molecular weight regulator, 0.15 parts by weight of tertiary butyl hydroperoxide as an initiator, 0.06 parts by weight of dextrose, 0.005 parts by weight of sodium pyrophosphate, and 0.0025 parts by weight of ferrous sulfate were fed batchwise into a polymerization reactor filled with nitrogen, and polymerization was initiated at 55° C. 0.31 parts by weight of potassium persulfate was fed batchwise at a polymerization conversion rate of 30 to 40% into the polymerization reactor, and then polymerization was performed while elevating the temperature up to 72° C. Next, 8 parts by weight of 1,3-butadiene were fed batchwise into the polymerization reactor at a polymerization conversion rate 60 to 70% of, and then the polymerization was terminated at a polymerization conversion rate of 95%. Here, the average particle diameter of the small-diameter rubber latex was 1,310 Å.

Example 1

[0107] <Preparation of Rubber Latex Enlarged with Polymer Particle Diameter Control Agent >

[0108] 100 parts by weight (based on a solid) of the conjugated diene rubber latex (average particle diameter: 1,250 Å) prepared according to Preparation Example B-1 was stirred in a reactor while elevating the temperature to 50° C., and then 2.0 parts by weight of the polymer particle diameter control agent prepared according to Preparation Example A-1 were added thereto, followed by stirring for 15 minutes to be enlarged. The average particle diameter of the enlarged rubber latex was 3780 Å.

[0109] <Preparation of graft copolymer and thermoplastic resin composition >

[0110] 30 parts by weight of styrene, 10 parts by weight of acrylonitrile, and 0.34 parts by weight of t-dodecyl mercaptan

[0111] (TDDM) were mixed, and then were continuously fed into 60 parts by weight (based on a solid) of the prepared enlarged rubber latex over 3 hours to be graft-polymerized, thereby obtaining an ABS graft copolymer latex. 0.5 parts by weight of an emulsion (average particle diameter: 0.9 pm) prepared by mixing Wingstay-L (LATON KOREA CO., LTD.), with IR107 (LATON KOREA CO., LTD.) as an antioxidant in a weight ratio of 0.8:0.2 were fed into the obtained ABS graft copolymer latex, and then the temperature was elevated to 84° C., followed by feeding 3.0 parts by weight of magnesium sulfate (MgSO.sub.4) thereto to be agglomerated. Next, the temperature was elevated to 98° C. over 10 minutes, and then dehydration was performed in a dehydrator, followed by drying. As a result, a powder was obtained.

[0112] Next, 25% by weight of the ABS graft copolymer powder and 75% by weight of an acrylonitrile-styrene copolymer were fed into and mixed in a mixer, followed by pelletizing using a twin-screw extruder. Next, a specimen for property measurement was manufactured using an injection machine. The weight-average molecular weight of the acrylonitrile-styrene copolymer was 140,000 g/mol and included 24% by weight of acrylonitrile and 76% by weight of styrene.

Examples 2 to 6, Comparative Examples 1 to 6, and Reference Example 1

[0113] <Preparation of Rubber Latex Enlarged with Polymer Particle Diameter Control Agent >

[0114] Experiments were carried out in the same manner as in Example 1, except that a conjugated diene rubber latex and a polymer particle diameter control agent were used as summarized in Tables 1 and 2.

[0115] <Preparation of Graft Copolymer and Thermoplastic Resin Composition >

[0116] Experiments were carried out in the same manner as in Example 1, except that the enlarged rubber latex prepared as described above was used.

Test Example

[0117] The properties of the specimens manufactured according to Examples 1 to 6, Comparative Examples 1 to 6, and Reference Example 1 were measured according to the following methods. Results are summarized in Tables 1 and 2 below.

[0118] Measurement Methods

[0119] Average particle diameter (Å): Measured using a particle size analyzer (NICOMP 380).

[0120] Izod impact strength (kgf.Math.cm/cm): Measured according to ASTM D256 using a specimen with a thickness of ¼″.

[0121] Melt flow index (MI; g/10 minutes) : Measured according to ASTM D1238 at 220° C.

[0122] Gloss: Measured at an angle of 45° according to ASTM D523 using a specimen with a thickness of ¼″ (6.4 mm).

TABLE-US-00001 TABLE 1 Classification Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Polymer Type Preparation Preparation Preparation Preparation Preparation Preparation particle Example A-1 Example A-2 Example A-3 Example A-4 Example A-3 Example A-5 diameter MA (% by 2.0 — 97.8 3.8 97.8 0.1 control weight) agent EA (% by 1.0 90.2 — 1.0 — 89.9 weight) BA (% by 80.9 1.0 — 79.0 — 1.5 weight) MMA (% by 16.1 8.8 2.2 16.2 2.2 8.5 weight) Tg 0.5 4.2 9.6 1.0 9.6 3.9 (° C.) Average 1100 1200 1180 1250 1180 1140 particle diameter (Å) (PS.sub.1) Conjugated Type Preparation Preparation Preparation Preparation Preparation Preparation diene Example B-1 Example B-2 Example B-3 Example B-1 Example B-4 Example B-2 rubber Average 1250 1060 1170 1250 1310 1060 latex particle diameter (Å) (PS.sub.2) Enlarged Average 3780 3880 3560 3980 3700 3630 rubber particle latex diameter (Å) PS.sub.1/PS.sub.2 0.88 1.13 1.01 1.00 0.90 1.08 Thermoplastic Impact 30.2 33.6 31.9 30.9 31.4 30.0 resin strength composition MI 23.0 22.5 22.8 23.1 22.7 22.6 Gloss 99.7 99.9 100.1 99.1 98.9 99.4

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Comparative Comparative Reference Classification Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 1 Polymer Type Preparation Preparation Preparation Preparation Preparation Preparation Preparation particle Example A-6 Example A-7 Example A-8 Example A-9 Example A-10 Example A-8 Example A-11 diameter MA (% by 0.5 — 96.4 — 96.2 — 97 control weight) agent EA (% by — — — 93.0 0.4 3.5 0.2 weight) BA (% by 82.5 82.1 0.5 — — 75.0 0.1 weight) MMA (% by 16.0 17.9 3.1 7.0 3.4 21.5 2.7 weight) Tg −2.7 −11.1 12.3 0.7 8.9 8.3 1.2/9.7 (° C.) Average 1140 1060 1300 1220 990 1200 1070 particle diameter (Å) (PS.sub.1) Conjugated Type Preparation Preparation Preparation Preparation Preparation Preparation Preparation diene Example B-1 Example B-2 Example B-3 Example B-2 Example B-1 Example B-2 Example B-2 rubber Average 1250 1060 1170 1060 1250 1170 1060 latex particle diameter (Å) (PS.sub.2) Enlarged Average 3700 3450 4210 4050 3860 4900 4030 rubber particle latex diameter (Å) PS.sub.1/PS.sub.2 0.91 1.00 1.11 1.15 0.8 1.03 1.01 Thermoplastic Impact 20.0 21.1 17.8 17.9 22.0 15.4 23.1 resin strength composition MI 19.0 18.9 20.6 22.0 21.5 21.5 19.7 Gloss 97.0 96.4 91.0 89.7 95.9 88.5 90.7

[0123] As shown in Tables 1 and 2, the thermoplastic resin compositions of Examples 1 to 6 including the polymer particle diameter control agent according to the present invention exhibited the synergistic effect of improving both impact strength and fluidity, compared to Comparative Examples 1 to 6.

[0124] In particular, in the case of Comparative Examples 1 to 3 wherein the glass transition temperature of the polymer particle diameter control agent was outside of the range of the present invention, impact strength was poor. In addition, in the case of Comparative Examples 4 and 5 wherein a ratio (PS.sub.1/PS.sub.2) of the average particle diameter (PS.sub.1) of the polymer particle diameter control agent to the average particle diameter (PS.sub.2) of the conjugated diene rubber latex was outside of the range of the present invention, impact strength was greatly decreased.

[0125] In addition, in the case of Comparative Example 6 wherein the content of the unsaturated acid compound in the polymer particle diameter control agent was outside of the range of the present invention, impact strength and gloss were greatly decreased.

[0126] Further, in the case of Reference Example 1 wherein the polymer particle diameter control agent had a core-shell structure and two glass transition temperatures, the PS.sub.1/PS.sub.2 ratio was included within the range of the present invention, but impact strength was low compared to Examples 1 to 6.