阅读说明：本技术 乙烯基氰化合物-共轭二烯化合物-芳香族乙烯基化合物接枝共聚物的制备方法和组合物 (Process for producing vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer and composition ) 是由 石宰旼 金由彬 金英玟 李镇衡 韩受静 郑荣焕 朴昶弘 许宰源 于 2019-10-21 设计创作，主要内容包括：本发明涉及一种接枝共聚物的制备方法和包含该接枝共聚物的热塑性树脂组合物。更具体地,本发明涉及一种接枝共聚物的制备方法,该制备方法包括：通过将酸凝结剂加入到100重量份(基于固体)的通过将芳香族乙烯基化合物和乙烯基氰化合物接枝聚合到共轭二烯橡胶胶乳上而制备的接枝共聚物胶乳中来进行凝结的步骤；和通过向其中加入盐凝结剂再次进行凝结的步骤。根据本发明,当使用所述制备方法制备接枝共聚物时,可以提高凝结效率,并且可以提高制备的接枝共聚物的光泽度。此外,由于使用Hunter Lab色度计测量的b值和在250℃下放置15分钟之后测量的b值低,因此,所述接枝共聚物可以具有优异的颜色特性。此外,由于加热损失低并且焦烧时间长,因此,所述接枝共聚物可以具有优异的加工特性。(The present invention relates to a method for preparing a graft copolymer and a thermoplastic resin composition comprising the same. More specifically, the present invention relates to a method for preparing a graft copolymer, comprising: a step of coagulation by adding an acid coagulant to 100 parts by weight (on a solid basis) of a graft copolymer latex prepared by graft polymerizing an aromatic vinyl compound and a vinyl cyanide compound onto a conjugated diene rubber latex; and a step of coagulation again by adding a salt coagulant thereto. According to the present invention, when a graft copolymer is prepared using the preparation method, coagulation efficiency can be improved, and gloss of the prepared graft copolymer can be improved. In addition, the graft copolymer may have excellent color characteristics because the b-value measured using a Hunter Lab colorimeter and the b-value measured after being left at 250 ℃ for 15 minutes are low. In addition, the graft copolymer may have excellent processing characteristics because of low heating loss and long scorch time.)

1. A method for preparing a vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer, the method comprising:

preparing a graft copolymer latex by graft polymerizing 20 to 40% by weight of an aromatic vinyl compound and 1 to 20% by weight of a vinyl cyanide compound onto 50 to 70% by weight of a conjugated diene rubber latex having a solid content of 30 to 65% by weight;

a first coagulation step of coagulating by adding 0.10 to 0.80 parts by weight of an acid coagulant, based on 100 parts by weight (on a solid basis) of the graft copolymer latex; and

a second coagulation step of performing coagulation by adding 0.96 to 1.85 parts by weight of a salt coagulant after the first coagulation step,

wherein the total weight of the acid coagulant and the salt coagulant is 1.66 parts by weight to 2.20 parts by weight.

2. The production method according to claim 1, wherein the acid coagulant includes one or more selected from sulfuric acid, hydrochloric acid, formic acid, and acetic acid.

3. The preparation method according to claim 1, wherein the salt coagulant comprises one or more selected from magnesium sulfate, calcium sulfate, aluminum sulfate, magnesium chloride, calcium chloride, and aluminum chloride.

4. The production method according to claim 1, wherein, in the first coagulation step, the acid coagulant is added at a temperature of 75 to 85 ℃, and heating is performed to raise the temperature by 5 to 10 ℃ over 5 to 35 minutes.

5. The production method according to claim 1, wherein, in the second coagulation step, the salt coagulant is added at a temperature of 80 ℃ to 95 ℃, and heating is performed to raise the temperature by 5 ℃ to 10 ℃ over 5 minutes to 35 minutes.

6. The production method according to claim 1, wherein in the production of the graft copolymer latex, 70 to 200 parts by weight of deionized water, 0.1 to 2 parts by weight of an initiator, 0.1 to 2 parts by weight of an emulsifier, and 0.05 to 1.5 parts by weight of a molecular weight modifier are added to 100 parts by weight in total of the conjugated diene rubber latex, the aromatic vinyl compound, and the vinyl cyanide compound to carry out polymerization, and the polymerization is terminated when a polymerization conversion rate is 93 to 99%.

7. The production method according to claim 1, wherein the production of the graft copolymer latex comprises: the conjugated diene rubber latex is prepared by adding 30 to 100 parts by weight of deionized water, 0.5 to 3 parts by weight of an emulsifier, 0.01 to 0.5 parts by weight of an electrolyte, 0.1 to 0.5 parts by weight of a molecular weight regulator, and 0.1 to 1 part by weight of an initiator to 100 parts by weight of the conjugated diene compound and performing polymerization.

8. The method of claim 1, comprising a dehydration and drying step after the coagulation step.

9. A vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer prepared using the preparation method according to any one of claims 1 to 8.

10. A thermoplastic resin composition comprising:

20 to 40% by weight of the vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer of claim 9; and

60 to 80% by weight of an aromatic vinyl compound-vinyl cyan compound copolymer.

11. The thermoplastic resin composition of claim 10, wherein the thermoplastic resin composition has a b-value of 9 or less when measured using a Hunter Lab colorimeter after being left at 250 ℃ for 15 minutes.

12. The thermoplastic resin composition of claim 10, wherein the thermoplastic resin composition has a gloss of 90 or more when measured at an angle of 45 ° using a gloss meter according to ASTM D523.

13. The thermoplastic resin composition according to claim 10, wherein when a thermoplastic resin composition powder having a moisture content of 1% by weight or less is placed on an aluminum foil in contact with oxygen in the air, is placed in a hot air oven at 190 ℃, and a scorch test is performed to measure a time to start carbonization, the scorch time of the thermoplastic resin composition is 60 minutes or more.

Technical Field

[ Cross-reference to related applications ]

The present application claims the priority of korean patent application No. 10-2018-.

The present invention relates to a method for preparing a graft copolymer and a thermoplastic resin composition comprising the same. According to the preparation method of the present invention, a graft copolymer latex prepared by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound onto a conjugated diene rubber latex is coagulated using an acid coagulant, and then the graft copolymer latex is coagulated again using a salt coagulant. Accordingly, coagulation efficiency can be improved, and a graft copolymer having excellent gloss, color properties, and processability, and a thermoplastic resin composition comprising the same can be provided.

Background

An acrylonitrile-butadiene-styrene copolymer (hereinafter referred to as "ABS copolymer") represented by a vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer has good physical properties such as impact resistance, mechanical strength, moldability and gloss, and thus is widely used in various fields such as electric parts, electronic parts, office equipment and automobile parts.

In general, ABS copolymers prepared by grafting aromatic vinyl compound monomers and vinyl cyan compound monomers onto a conjugated diene rubber latex using emulsion polymerization show a good balance in physical properties and have excellent gloss, compared to ABS copolymers prepared using bulk polymerization. Therefore, emulsion polymerization is mainly used to prepare ABS copolymers.

In addition, in order to reduce volume, improve applicability, and facilitate handling, it is preferable to form the ABS copolymer latex prepared using emulsion polymerization into a powder form. The ABS resin powder may be obtained by coagulating, aging, dehydrating and drying the ABS resin latex according to a conventional method.

When coagulation of an ABS copolymer latex prepared using emulsion polymerization is performed, various coagulants may be used to chemically coagulate latex particles stabilized by an emulsifier used in emulsion polymerization. In this case, an acid or a metal salt may be used as the coagulant. When acid is used to coagulate the latex, the residual amount of acid may decrease the thermal stability of the ABS resin, and the amount of gas generated during thermoforming may increase, thereby increasing the yellowness index of the resin. Further, when the metal salt is used to coagulate the latex, the amount of gas generated and the yellowness index are relatively low, but productivity may be reduced.

Therefore, it is required to develop a method for preparing an ABS copolymer, which enables the ABS copolymer latex to be coagulated efficiently and to prepare an ABS copolymer having excellent color characteristics.

[ Prior art documents ]

[ patent document ] (patent document 1) KR 10-0463482B 1

Disclosure of Invention

Technical problem

Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a method for preparing a graft copolymer, the method comprising: a first coagulation step of coagulating by adding 0.10 to 0.80 parts by weight of an acid coagulant based on 100 parts by weight (on a solid basis) of a graft copolymer latex prepared by graft polymerizing an aromatic vinyl compound and a vinyl cyanide compound onto a conjugated diene rubber latex; and a second coagulation step of performing coagulation by adding 0.96 to 1.85 parts by weight of a salt coagulant after the first coagulation step, wherein the total weight of the acid coagulant and the salt coagulant is adjusted to 1.66 to 2.20 parts by weight. According to the present invention, coagulation efficiency and glossiness can be improved. Further, the graft copolymer has excellent color characteristics in view of low measurement results of the b value measured using a Hunter Lab colorimeter and the b value measured after being left in an injection molding machine at 250 ℃ for 15 minutes. In addition, the graft copolymer has excellent processing characteristics in view of the measurement results of low heating loss and long scorch time.

The above and other objects of the present invention can be achieved by the present invention described below.

Technical scheme

According to an aspect of the present invention, there is provided a method for preparing a vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer, the method comprising: preparing a graft copolymer latex by graft polymerizing 20 to 40% by weight of an aromatic vinyl compound and 1 to 20% by weight of a vinyl cyanide compound onto 50 to 70% by weight of a conjugated diene rubber latex having a solid content of 30 to 65% by weight; a first coagulation step of coagulating by adding 0.10 to 0.80 parts by weight of an acid coagulant, based on 100 parts by weight (on a solid basis) of the graft copolymer latex; and a second coagulation step of coagulating by adding 0.96 to 1.85 parts by weight of a salt coagulant after the first coagulation step, wherein the total weight of the acid coagulant and the salt coagulant is 1.66 to 2.20 parts by weight.

According to another aspect of the present invention, there is provided a vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer prepared using the preparation method.

According to still another aspect of the present invention, there is provided a thermoplastic resin composition comprising: 20 to 40% by weight of the vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer and 60 to 80% by weight of an aromatic vinyl compound-vinyl cyanide compound copolymer.

Advantageous effects

According to the present invention, when a graft copolymer latex prepared by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound onto a conjugated diene rubber latex is coagulated using 0.10 to 0.80 parts by weight of an acid coagulant and then the graft copolymer latex is again coagulated using 0.96 to 1.85 parts by weight of a salt coagulant, and when the total weight of the acid coagulant and the salt coagulant is 1.66 to 2.20 parts by weight, coagulation efficiency and gloss can be improved. Further, the graft copolymer of the present invention has excellent color characteristics in view of low measurement results of the b value measured using a HunterLab colorimeter and the b value measured after being left in an injection molding machine at 250 ℃ for 15 minutes. In addition, the graft copolymer has excellent processing characteristics in view of the measurement results of low heating loss and long scorch time.

Detailed Description

The present inventors confirmed that when a vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer latex is coagulated using an acid coagulant and coagulated again using a salt coagulant under the condition that the acid coagulant and the salt coagulant are used in specific contents, gloss, color property and processability are improved. Based on these results, the present inventors further studied to complete the present invention.

Hereinafter, the preparation method of the vinylcyan compound-conjugated diene compound-aromatic vinyl compound graft copolymer according to the present invention will be described in detail.

The method for preparing the vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer according to the present invention comprises: a step of preparing a graft copolymer latex by graft polymerizing 20 to 40% by weight of an aromatic vinyl compound and 1 to 20% by weight of a vinyl cyanide compound onto 50 to 70% by weight of a conjugated diene rubber latex having a solid content of 30 to 65% by weight; a first coagulation step of coagulating by adding 0.10 to 0.80 parts by weight of an acid coagulant, based on 100 parts by weight (on a solid basis) of the prepared graft copolymer latex; and a second coagulation step of performing coagulation by adding 0.96 to 1.85 parts by weight of a salt coagulant after the first coagulation step. In this case, the total weight of the acid coagulant and the salt coagulant is 1.66 parts by weight to 2.20 parts by weight. According to the production method of the present invention, the coagulation efficiency is improved. Further, since the b-value measured using a Hunter Lab colorimeter and the b-value measured after being left at 250 ℃ for 15 minutes are low and the glossiness is high, the color characteristics are excellent.

The production method of the present invention will be described step by step in detail.

Step of preparing conjugated diene rubber latex

For example, the method for preparing the conjugated diene rubber latex may include the steps of: the conjugated diene rubber latex is prepared by adding 30 to 100 parts by weight of deionized water, 0.5 to 3 parts by weight of an emulsifier, 0.01 to 0.5 parts by weight of an electrolyte, 0.1 to 0.5 parts by weight of a molecular weight regulator, and 0.1 to 1 part by weight of an initiator to 100 parts by weight of a conjugated diene compound and performing polymerization. In this case, the impact resistance may be excellent.

As another example, the method for preparing the conjugated diene rubber latex may include the steps of: the conjugated diene rubber latex is prepared by adding 40 to 70 parts by weight of deionized water, 1 to 2.5 parts by weight of an emulsifier, 0.05 to 0.3 parts by weight of an electrolyte, 0.2 to 0.4 parts by weight of a molecular weight regulator, and 0.3 to 0.8 parts by weight of an initiator to 100 parts by weight of a conjugated diene compound and polymerizing. In this case, the impact resistance may be excellent.

As a specific example, the method of preparing the conjugated diene rubber latex may include: a first polymerization step of adding 30 to 100 parts by weight of deionized water, 0.3 to 2 parts by weight of an emulsifier, 0.01 to 0.5 parts by weight of an electrolyte, 0.1 to 0.5 parts by weight of a molecular weight modifier, and 0.05 to 0.5 parts by weight of an initiator to 75 to 90 parts by weight of 100 parts by weight of a conjugated diene compound and performing polymerization; a second polymerization step of adding 0.05 to 0.5 parts by weight of an initiator when the polymerization conversion rate reaches 35 to 45% after the first polymerization step, continuously adding 10 to 25 parts by weight of the conjugated diene compound, and performing polymerization; a third polymerization step of adding 0.2 to 1 part by weight of an emulsifier when the polymerization conversion rate reaches 70 to 80% after the second polymerization, and performing polymerization; and a step of terminating the polymerization when the polymerization conversion rate reaches 93% to 99% after the third polymerization. In this case, the impact resistance may be excellent.

In the present invention, the polymerization conversion rate may be defined as the weight percentage of the monomer converted into the polymer based on 100% of the total monomer added up to the polymerization end point. Any polymerization conversion rate measuring method performed according to this definition can be used as the polymerization conversion rate measuring method of the present invention without limitation. As a specific example, 1.5g of the prepared latex was dried in a hot air dryer at 150 ℃ for 15 minutes, the weight thereof was measured, the Total Solid Content (TSC) thereof was calculated using the following equation 1, and the polymerization conversion was calculated by substituting the total solid content into the following equation 2. In equation 2, the total weight of the added monomers is set to 100 parts by weight.

[ equation 1]

Total solid content (TSC,%) (weight after drying/weight before drying) × 100

[ equation 2]

Polymerization conversion (%) [ Total Solid Content (TSC) × (total weight of monomer, deionized water and auxiliary raw material added)/100 ] - (weight of auxiliary raw material added in addition to monomer and deionized water)

In equation 2, the auxiliary raw materials include an initiator, an emulsifier, an electrolyte, and a molecular weight regulator.

The monomer to be added means a conjugated diene compound.

For example, the conjugated diene compound may include one or more selected from the group consisting of 1, 3-butadiene, 2, 3-dimethyl-1, 3-butadiene, 2-ethyl-1, 3-butadiene, 1, 3-pentadiene, and isoprene.

For example, the emulsifier may include one or more selected from the group consisting of alkyl aryl sulfonates, alkaline methyl alkyl sulfates, sulfonated alkyl esters, fatty acid soaps, and alkali salts of rosin acids.

For example, the electrolyte may include one or more selected from KCl, NaCl, KHCO₃、NaHCO₃、K₂CO₃、Na₂CO₃、KHSO₃、NaHSO₃、K₄P₂O₇、Na₄P₂O₇、K₃PO₄、Na₃PO₄、K₂HPO₄And Na₂HPO₄One or more of (a).

For example, a water-soluble persulfate polymerization initiator, a fat-soluble polymerization initiator, a redox system catalyst, or the like can be used as the initiator. For example, the water-soluble persulfate polymerization initiator may include one or more selected from the group consisting of potassium persulfate, sodium persulfate, and ammonium persulfate; the fat-soluble polymerization initiator may include one or more selected from cumene hydroperoxide, diisopropylbenzene hydroperoxide, azobisisobutyronitrile, t-butyl hydroperoxide, p-menthane hydroperoxide, and benzoyl peroxide; the redox system catalyst may include one or more selected from the group consisting of sodium formaldehyde sulfoxylate, sodium ethylenediaminetetraacetate, ferrous sulfate, glucose, sodium pyrrolide, and sodium sulfite.

Most preferably, when the conjugated diene rubber latex is prepared, potassium persulfate is used as the initiator.

For example, a thiol-based molecular weight modifier may be used as the molecular weight modifier. Preferably, tert-dodecyl mercaptan is used as molecular weight regulator.

For example, the average particle diameter of the conjugated diene rubber latex of the present invention may beToPreferably, it isToMore preferablyToWithin the range, the impact resistance may be excellent.

In the present invention, a sample for measuring the average particle diameter may be prepared by diluting the conjugated diene rubber latex so that the Total Solid Content (TSC) of the conjugated diene rubber latex is 1% or less, and Nicomp may be used as the average particle diameter of the conjugated diene rubber latex^TM380 instruments (PSS Nicomp Co., USA) according to the dynamic laser light scattering methodAmount of the compound (A).

Step of preparing graft copolymer latex

For example, in the step of preparing the graft copolymer latex, 20 to 40% by weight of an aromatic vinyl compound and 1 to 20% by weight of a vinyl cyanide compound may be graft-polymerized onto 50 to 70% by weight of a conjugated diene rubber latex having a solid content of 30 to 65% by weight. Preferably, 25 to 35% by weight of an aromatic vinyl compound and 5 to 15% by weight of a vinyl cyanide compound are graft-polymerized onto 55 to 65% by weight of a conjugated diene rubber latex having a solid content of 30 to 65% by weight. Within the range, impact resistance, mechanical strength and moldability may be excellent.

In the present invention, the solids content is defined as the amount of active ingredient remaining when all the water present in the latex evaporates. When the solid content was measured, the latex was placed on an aluminum pan, 2.5g of the latex was prepared using a balance, and the prepared latex was held at 150 ℃ for 5 minutes, so that all water in the latex was evaporated. Then, the weight of the latex powder is measured, and the measured value is substituted into equation 3 to calculate the solid content of the latex.

[ equation 3]

Solid content (% by weight) 100- [ (weight of latex before water evaporation (g) — weight of powder remaining after water evaporation (g))/weight of latex before water evaporation (g) × 100]

For example, in the step of preparing the graft copolymer latex, 70 to 200 parts by weight of deionized water, 0.1 to 2 parts by weight of an initiator, 0.1 to 2 parts by weight of an emulsifier, and 0.05 to 1.5 parts by weight of a molecular weight regulator may be added to 100 parts by weight of the total of the conjugated diene rubber latex, the aromatic vinyl compound, and the vinyl cyanide compound to perform polymerization, and the polymerization may be terminated when the polymerization conversion rate is 93 to 99%.

In this step, the polymerization conversion is the same as defined for the polymerization conversion described in the step of preparing the conjugated diene rubber latex, and the measurement is performed using the same measurement method as that of the step of preparing the conjugated diene rubber latex. The monomers added are a conjugated diene compound, an aromatic vinyl compound and a vinyl cyanide compound contained in the rubber latex.

As another example, in the step of preparing the graft copolymer latex, 100 parts by weight to 170 parts by weight of deionized water, 0.3 parts by weight to 1 part by weight of an initiator, 0.5 parts by weight to 1.5 parts by weight of an emulsifier, and 0.1 parts by weight to 1.0 part by weight of a molecular weight regulator may be added to 100 parts by weight in total of the conjugated diene rubber latex, the aromatic vinyl compound, and the vinyl cyanide compound to perform polymerization, and the polymerization may be terminated when the polymerization conversion rate is 95% to 98%.

As a specific example, in the step of preparing the graft copolymer latex, a mixed solution containing 20 to 40% by weight of an aromatic vinyl compound, 1 to 20% by weight of a vinyl cyanide compound, 10 to 50 parts by weight of deionized water, 0.09 to 1.5 parts by weight of an initiator, 0.1 to 2 parts by weight of an emulsifier, and 0.05 to 1.5 parts by weight of a molecular weight regulator, mixed in separate mixing devices, is added to 50 to 70% by weight of a conjugated diene rubber latex having a solid content of 30 to 65% by weight, and 60 to 150 parts by weight of deionized water at 65 to 75 ℃ over 2 to 4 hours; adding 0.01 to 0.5 parts by weight of an initiator thereto; heating is carried out such that the temperature is raised to 75 ℃ to 80 ℃ over 30 minutes to 90 minutes; when the polymerization conversion rate reached 93% to 99%, the graft polymerization was terminated. In this case, impact resistance, mechanical strength and moldability may be excellent.

For example, the solid content of the conjugated diene rubber latex may be 30 to 65% by weight, preferably 40 to 60% by weight, and more preferably 55 to 60% by weight. In this case, the polymerization can be uniformly carried out.

For example, the aromatic vinyl compound may include one or more selected from the group consisting of styrene, α -methylstyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, ethylstyrene, isobutyl styrene, tert-butylstyrene, o-bromostyrene, p-bromostyrene, m-bromostyrene, o-chlorostyrene, p-chlorostyrene, m-chlorostyrene, vinyltoluene, vinylxylene, fluorostyrene and vinylnaphthalene.

For example, the vinyl cyanide compound may be acrylonitrile, methacrylonitrile, or a mixture thereof.

For example, the emulsifier, the initiator, and the molecular weight regulator may be used in amounts within the ranges described in the step of preparing the conjugated diene rubber latex.

According to the present invention, other additives not specifically mentioned in the present invention such as an electrolyte may be appropriately selected according to need, and additives generally used in the preparation of a vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer latex may be used without particular limitation.

In addition to the above reaction conditions, other reaction conditions generally used in the art to which the present invention pertains, such as reaction time, reaction temperature, pressure, and addition time of reactants, may be appropriately selected and used as needed without particular limitation.

Step of coagulating the graft copolymer latex

The prepared graft copolymer latex is coagulated by using a coagulant to form a graft copolymer slurry.

For example, the condensing step may include: a first coagulation step of coagulating by adding 0.10 to 0.80 parts by weight of an acid coagulant, based on 100 parts by weight (on a solid basis) of the prepared graft copolymer latex; and a second coagulation step of performing coagulation by adding 0.96 to 1.85 parts by weight of a salt coagulant after the first coagulation step. In this case, the total weight of the acid coagulant and the salt coagulant may be 1.66 parts by weight to 2.20 parts by weight. When coagulation is performed in this manner, coagulation efficiency can be improved, and glossiness can be increased. Further, since the b-value measured using a Hunter Lab colorimeter and the b-value measured after being left at 250 ℃ for 15 minutes are low, the color characteristics can be excellent. Further, since the heating loss is low and the scorch time is long, the processing characteristics can be excellent.

For example, the first coagulation step may be a step of adding an acid coagulant to the graft copolymer latex at a temperature of 75 to 85 ℃ and increasing the temperature by 5 to 10 ℃ over 5 to 35 minutes. Preferably, the first coagulation step is a step of adding an acid coagulant at a temperature of 78 ℃ to 82 ℃ and raising the temperature to 6 ℃ to 8 ℃ over 10 minutes to 30 minutes. In this case, the condensation can be uniformly performed, and the condensation efficiency can be improved.

For example, in the second coagulation step, the salt coagulant may be added at a temperature of 80 ℃ to 95 ℃, and the temperature may be increased by 5 ℃ to 10 ℃ over 5 minutes to 35 minutes. Preferably, the salt coagulant is added at a temperature of 84 ℃ to 90 ℃ and the temperature is raised 6 ℃ to 8 ℃ over 10 minutes to 30 minutes. In this case, the condensation can be uniformly performed, and the condensation efficiency can be improved. Furthermore, an aging effect can be obtained.

As a specific example, the temperature at the completion of the first condensation step and the temperature at the beginning of the second condensation step may be the same.

For example, the first and second coagulation steps may be performed at an agitation speed of 5 to 450rpm or 10 to 400rpm, preferably 30 to 300rpm, more preferably 30 to 100rpm, but not limited thereto. Within the range, productivity and coagulation efficiency can be improved, and the balance of physical properties can be excellent.

For example, when coagulation is performed, the acid coagulant may be used in an amount of 0.10 to 0.80 parts by weight, preferably 0.15 to 0.75 parts by weight, more preferably 0.20 to 0.70 parts by weight, and most preferably 0.20 to 0.50 parts by weight or 0.50 to 0.70 parts by weight, based on 100 parts by weight (based on solids) of the graft copolymer latex. Within the range, the coagulation efficiency can be improved, and the gloss can be increased. Further, since the b-value measured using a Hunter Lab colorimeter and the b-value measured after being left at 250 ℃ for 15 minutes are low, the color characteristics can be excellent. Further, since the heating loss is low and the scorch time is long, the processing characteristics can be excellent.

For example, when coagulation is performed, the salt coagulant may be used in an amount of 0.96 to 1.85 parts by weight or 0.96 to 1.80 parts by weight, preferably 1.00 to 1.80 parts by weight, more preferably 1.25 to 1.80 parts by weight, most preferably 1.30 to 1.50 parts by weight, based on 100 parts by weight (based on solids) of the graft copolymer latex. Within the range, the gloss may be excellent. Further, since the heating loss is low and the scorch time is long, the processing characteristics can be excellent.

For example, the total weight of acid coagulant and salt coagulant may be 1.66 parts by weight to 2.20 parts by weight or 1.70 parts by weight to 2.10 parts by weight, preferably 1.70 parts by weight to 2.00 parts by weight, more preferably 1.75 parts by weight to 2.00 parts by weight, based on 100 parts by weight (on a solid basis) of the graft copolymer latex. Within the range, the coagulation efficiency can be improved, and the gloss can be increased. Further, since the b-value measured using a HunterLab colorimeter and the b-value measured after being left at 250 ℃ for 15 minutes are low, the color characteristics can be excellent. Further, since the heating loss is low and the scorch time is long, the processing characteristics can be excellent.

For example, the acid coagulant may include one or more selected from sulfuric acid, hydrochloric acid, formic acid, and acetic acid. Preferably, the acid coagulant is sulfuric acid. In this case, since the b-value measured using a Hunter Lab colorimeter and the b-value measured after being left at 250 ℃ for 15 minutes are low, the color characteristics can be excellent.

For example, the salt coagulant may include one or more selected from magnesium sulfate, calcium sulfate, aluminum sulfate, magnesium chloride, calcium chloride, and aluminum chloride. Preferably, the salt coagulant is magnesium sulfate. In this case, the coagulation efficiency can be improved, and the glossiness can be excellent.

When the acid coagulant and the salt coagulant contain a solvent such as water, the weight thereof means the weight excluding the solvent.

For example, an antioxidant, a stabilizer, or a mixture thereof may be added in the coagulation step. In this case, the physical property balance may be excellent after extrusion.

The coagulated graft copolymer latex may be dehydrated and dried to obtain graft copolymer powder.

In the present invention, the powder refers to an object composed of a plurality of solid particles. For example, the powder may be an object composed of a plurality of solid particles having an average particle diameter of 1 μm to 10,000 μm or 10 μm to 2,000 μm.

In the present invention, the average particle diameter of the powder can be measured using the DP blocking test. Specifically, according to the DP caking test, 10g of the powder was pressed for 10 minutes using a weight of 20kg, screens of #8 mesh (2,380 μm) to #625 mesh (20 μm) were stacked in a screen shaker (analystte 3, Fritsch co., germany), a stainless steel container for collecting the powder passing through the #625 mesh was placed at the bottom of the #625 mesh, vibration was applied to the screen shaker for 20 minutes, and the particle size distribution of the powder remaining in the screen was confirmed. In the particle size distribution, the diameter of particles whose cumulative weight was 50 wt% was used as the average particle diameter of the powder.

The dehydration and drying method generally used in the art may be used without particular limitation.

For example, the slurry obtained after coagulation may be dehydrated using a centrifugal dehydrator, a pressure-type dehydrator, or the like to obtain the graft copolymer in the form of a wet powder.

For example, the dehydration may be performed at least once, preferably 1 to 3 times, more preferably 2 to 3 times. In this case, the content of the residual emulsifier can be reduced, thereby improving surface characteristics such as glossiness.

For example, the moisture content of the graft copolymer in the form of a wet powder obtained after dehydration may be 40% by weight or less, preferably 10% by weight to 40% by weight, more preferably 10% by weight to 35% by weight or 10% by weight to 30% by weight. In this case, in the drying step as a subsequent process, efficiency can be improved, thereby improving productivity.

A drying process generally applied in the art to which the present invention pertains may be used without particular limitation. For example, the graft copolymer in wet powder form may be dried by air supplied from a fluidized bed dryer to obtain a graft copolymer powder.

In addition, the moisture content of the graft copolymer powder obtained by drying the graft copolymer in the form of wet powder may be, for example, 2% by weight or less, preferably 0.1 to 2% by weight, more preferably 0.1 to 1% by weight. Within the range, the productivity of the copolymer may be improved, and physical properties such as mechanical strength, heat resistance, and surface gloss may be excellent.

In the present invention, a moisture analyzer may be used to measure the moisture content. As a specific example, a moisture analyzer (Mettler Toledo co., Switzerland) may be used.

For example, the graft copolymer powder and the aromatic vinyl compound-vinyl cyan compound copolymer may be melt-kneaded and extruded. In this case, impact resistance, chemical resistance, moldability and gloss may be excellent. Further, since the b-value measured using a Hunter Lab colorimeter and the b-value measured after being left at 250 ℃ for 15 minutes are low, a thermoplastic resin composition having aesthetic properties can be prepared.

For example, the melt-kneading and extruding step may be performed at 220 ℃ to 240 ℃ and 250rpm to 400rpm, preferably at 225 ℃ to 235 ℃ and 300rpm to 400rpm, but is not limited thereto.

For example, melt-kneading may be performed using a banbury mixer, a single-screw extruder, a twin-screw extruder, a kneader, or the like, but is not limited thereto.

For example, when melt-mixing is performed, one or more additives selected from the group consisting of a colorant, a heat stabilizer, a light stabilizer, a reinforcing agent, a filler, a flame retardant, a lubricant, a plasticizer, an antistatic agent, and a processing aid may be added in an amount of 0.1 to 10 parts by weight or 0.1 to 5 parts by weight.

In addition, the vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer of the present invention is prepared by the above-described preparation method. In this case, since the b-value measured using a Hunter Lab colorimeter and the b-value measured after being left at 250 ℃ for 15 minutes are low and the glossiness is high, the color characteristics may be excellent.

In addition, the thermoplastic resin composition of the present invention comprises 20 to 40% by weight, preferably 25 to 35% by weight of the vinyl cyanide compound-conjugated diene compound-aromatic vinyl compound graft copolymer, and 60 to 80% by weight, preferably 65 to 75% by weight of the aromatic vinyl compound-vinyl cyanide compound copolymer. In this case, impact resistance, chemical resistance, moldability and gloss may be excellent. Further, since the b value measured using a Hunter Lab colorimeter and the b value measured after being left at 250 ℃ for 15 minutes are low, the aesthetic property can be achieved.

For example, when a test specimen having a thickness of 1/8 inches (3.2mm) is prepared from the thermoplastic resin composition, and the gloss of the test specimen is measured at an angle of 45 ° using a gloss meter according to ASTM D523, the gloss of the thermoplastic resin composition may be 90 or more, or 90 to 110, preferably 92 to 102, more preferably 96 to 100. Within the range, the physical property balance and color characteristics may be excellent.

For example, when the b value is measured using a Hunter Lab colorimeter, the b value of the thermoplastic resin composition may be 3.6 or less, preferably 3.0 to 3.6, more preferably 3.2 to 3.5. Within the range, the physical property balance and color characteristics may be excellent.

For example, when the b value is measured using a Hunter Lab colorimeter after being left at 250 ℃ for 15 minutes, the b value of the thermoplastic resin composition may be 9 or less, preferably 3 to 9, more preferably 5 to 9, most preferably 5 to 8. Within the range, the physical property balance and color characteristics may be excellent.

For example, when the scorch time is measured at 190 ℃ according to the scorch test, the scorch time of the thermoplastic resin composition may be 60 minutes or more, or 80 minutes or more, preferably 80 minutes to 180 minutes, more preferably 80 minutes to 150 minutes. Within the range, the processing characteristics and the physical property balance may be excellent.

In the present invention, scorch time is defined as the time when flow stops in the mold and rubber begins to cure. When the scorch time is short, the unvulcanized mixture is vulcanized during molding at a high temperature, increasing the occurrence of molding failure.

In the present invention, when the scorch time was measured, the thermoplastic resin composition powder having a moisture content of 1 wt% or less was placed on an aluminum foil in contact with oxygen in the air, which was placed in a hot air oven at 190 ℃, and the time when carbonization started, i.e., the scorch time was measured. The scorch time is proportional to the degree of thermal stability.

In the present invention, the moisture content may be measured using a moisture analyzer. As a specific example, a moisture analyzer (Mettler Toledo co., Switzerland) may be used.

For example, the heat loss of the thermoplastic resin composition may be 0.8% by weight or less, or 0.1 to 0.8% by weight, preferably 0.1 to 0.6% by weight, more preferably 0.4 to 0.6% by weight. Within the range, the processing characteristics and the physical property balance may be excellent.

In the present invention, the loss of heat is defined as the weight loss that occurs when a substance is heated under specific conditions. When the loss of heat was measured, heating was performed at a rate of 20 ℃/min under a nitrogen atmosphere so that the temperature was increased from 80 ℃ to 250 ℃, and then heating was continued to maintain the temperature of 250 ℃ for 60 minutes. Then, the weight of the resin before and after heating was measured, and the measured value was substituted into equation 4 to calculate the heating loss. Further, the weight of the resin before and after heating can be measured by thermogravimetric analysis (TGA). Low heating loss indicates excellent processing characteristics.

[ equation 4]

Heating loss (% by weight) { (weight before heating-weight after heating)/weight before heating } × 100

Hereinafter, the present invention will be described in more detail with reference to the following preferred examples. However, these examples are provided for illustrative purposes only, and should not be construed as limiting the scope and spirit of the present invention. Further, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention, and these changes and modifications are also within the scope of the appended claims.