阅读说明：本技术 热塑性树脂的制备方法、由其制备的热塑性树脂和包含该热塑性树脂的热塑性树脂组合物 (Method for preparing thermoplastic resin, thermoplastic resin prepared therefrom, and thermoplastic resin composition comprising the same ) 是由 申珉承 朱玟徹 洪晟元 金仁秀 李亨燮 于 2019-07-09 设计创作，主要内容包括：本发明涉及一种热塑性树脂的制备方法、由该制备方法制备的热塑性树脂以及包含该热塑性树脂的热塑性树脂组合物。更具体地,本发明的方法包括：对乳液聚合胶乳进行酸凝结的步骤,用碱处理凝结后的浆料并进行脱水的步骤,和向脱水后的湿粉末中添加金属盐和水以将pH调节至9以上的步骤。根据本发明,所述方法可以提高热塑性树脂的生产率,并且通过所述方法制备的热塑性树脂具有优异的机械强度、热稳定性和外观性能。此外,当在涂层中使用本发明的热塑性树脂时,所述热塑性树脂具有改善涂膜的粘合强度和外观质量的效果。(The present invention relates to a method for preparing a thermoplastic resin, a thermoplastic resin prepared by the method, and a thermoplastic resin composition comprising the thermoplastic resin. More specifically, the method of the present invention comprises: a step of acid coagulation of the emulsion polymerization latex, a step of treating the coagulated slurry with an alkali and dehydrating, and a step of adding a metal salt and water to the dehydrated wet powder to adjust the pH to 9 or more. According to the present invention, the method can improve the productivity of thermoplastic resins, and thermoplastic resins prepared by the method have excellent mechanical strength, thermal stability and appearance properties. Further, when the thermoplastic resin of the present invention is used in a coating layer, the thermoplastic resin has the effect of improving the adhesive strength and appearance quality of the coating film.)

1. A method of preparing a thermoplastic resin comprising:

A) acid coagulating the emulsion polymerized latex;

B) treating the coagulated slurry with alkali and dehydrating; and

C) to the dehydrated wet powder, a metal salt and water are added to adjust the pH to 9 or more.

2. The production method according to claim 1, wherein the emulsion polymerization latex is a vinyl cyanide compound-conjugated diene-aromatic vinyl compound copolymer latex.

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

4. The production method according to claim 1, wherein the content of the acid coagulant is 0.5 to 4.0 parts by weight based on 100 parts by weight of the solid-based emulsion polymerization latex.

5. The production method according to claim 1, wherein the alkali treatment is performed by adding an alkali and mixing.

6. The production method according to claim 1, wherein the base includes one or more selected from sodium hydroxide and potassium hydroxide.

7. The production method according to claim 1, wherein the content of the metal salt is 0.05 to 0.5 parts by weight based on 100 parts by weight of the solid-based emulsion polymerization latex.

8. The production method according to claim 1, wherein the water is contained in an amount of 230 to 570 parts by weight based on 100 parts by weight of the solid-based emulsion polymerization latex.

9. The preparation method according to claim 1, wherein the metal salt includes one or more selected from magnesium sulfate, magnesium chloride, calcium chloride, and aluminum sulfate.

10. The method of claim 1, further comprising aging the coagulated slurry between step a and step B at 85 ℃ to 95 ℃ for 2 minutes to 20 minutes.

11. The production method according to claim 1, wherein the production method further comprises: after step C, the wet powder whose pH has been adjusted to 9 or more is dehydrated and dried to obtain a thermoplastic resin powder.

12. A thermoplastic resin produced by the production method according to any one of claims 1 to 11, wherein the thermoplastic resin has an oxidation induction time of 20 minutes or more.

13. A thermoplastic resin composition comprising 10 to 60% by weight of the thermoplastic resin according to claim 12 and 40 to 90% by weight of an aromatic vinyl compound-vinyl cyan compound copolymer.

14. The thermoplastic resin composition of claim 13, wherein said thermoplastic resin composition has a "b" value of 10 or less as measured using a Color Quest II, Hunter Lab Co.

15. The thermoplastic resin composition of claim 13, wherein the thermoplastic resin composition has a plating adhesion of 15N/cm or more.

Technical Field

[ CROSS-REFERENCE TO RELATED APPLICATIONS ]

The present application claims the priority of korean patent application No.10-2018-0167192 filed by the korean intellectual property office on 21.12.2018 and korean patent application No.10-2019-0078855 filed anew on 1.7.2019 based on the priority of the above-mentioned patents, the respective disclosures of which are incorporated herein by reference.

The present invention relates to a method for preparing a thermoplastic resin, a thermoplastic resin prepared by the method, and a thermoplastic resin composition comprising the thermoplastic resin. More particularly, the present invention relates to a method for preparing a thermoplastic resin having high productivity, a thermoplastic resin having excellent mechanical strength, heat resistance and appearance properties and improved thermal stability, and a thermoplastic resin composition comprising the same. According to the present invention, when the thermoplastic resin of the present invention is used in a coating layer, the thermoplastic resin has an effect of improving the adhesive strength and appearance quality of the coating film.

Background

Generally, when an acrylonitrile-butadiene-styrene (ABS) latex is prepared using emulsion polymerization, an acid or a metal salt is added and coagulation is performed to obtain the ABS latex in a powder form. In this case, the characteristics of the obtained ABS latex depend on the type of coagulant used. When the acid coagulant is used, productivity and thermal stability are improved. However, a large amount of gas is generated during the processing of the product and a yellowing phenomenon occurs, resulting in deterioration of appearance quality. On the other hand, in the case of using the metal salt coagulant, the appearance properties are improved as compared with the case of using the acid coagulant, but the productivity is lowered. For these reasons, there is a need for a process for preparing thermoplastic resins that overcomes the problems encountered with the use of acid coagulants or metal salt coagulants.

In response to this need, a method of treating the slurry resulting from acid coagulation with a base to remove residual emulsifier, which causes gas generation during product processing, has been developed. The method has effect of improving appearance quality. However, when the above method is used, the alkali treatment results in the emulsifier being in the form of a salt (R-COO)^-Na⁺) And remains so that the thermal stability is drastically lowered.

In order to overcome these problems and improve thermal stability, a method of converting the residual emulsifier from a salt form to an R-COO-H form by acid treatment again after alkali treatment has been proposed. The thermoplastic ABS resin prepared by this method has excellent appearance quality compared to conventional resins prepared using acid coagulation agents. However, the appearance quality of the thermoplastic ABS resin is still inferior to that prepared using a metal salt coagulant.

In recent years, ABS resins have been widely used for coatings. When coating is performed using an ABS resin, the adhesion and appearance quality of the coating film are considered to be important requirements. However, the thermoplastic ABS resin prepared by the above method has poor coating properties.

Therefore, it is necessary to develop a method for preparing a thermoplastic resin capable of improving productivity using an acid coagulant and to develop a thermoplastic resin having excellent appearance quality, thermal stability and coating properties.

[ Prior Art document ]

[ patent document ] KR 10-2017-

Disclosure of Invention

Technical problem

Accordingly, the present invention has been made keeping in mind the above problems, and an object of the present invention is to provide a method for preparing a thermoplastic resin having appearance properties equal to or better than those of a resin prepared using a metal salt coagulant, excellent thermal stability and improved coating properties, and high productivity; a thermoplastic resin prepared using the method; and a thermoplastic resin composition comprising the thermoplastic resin.

The above and other objects can be accomplished by the present disclosure described below.

Technical scheme

According to an aspect of the present invention, there is provided a method for preparing a thermoplastic resin, comprising: A) acid coagulating the emulsion polymerized latex; B) treating the coagulated slurry with alkali and dehydrating; and C) adding a metal salt and water to the dehydrated wet powder to adjust the pH to 9 or more.

According to another aspect of the present invention, there is provided a thermoplastic resin produced by the method for producing a thermoplastic resin, wherein the thermoplastic resin has an oxidation induction time of 20 minutes or more.

According to still another aspect of the present invention, there is provided a thermoplastic resin composition comprising 10 to 60% by weight of the thermoplastic resin and 40 to 90% by weight of an aromatic vinyl compound-vinyl cyan compound copolymer.

According to still another aspect of the present invention, there is provided a method for preparing a thermoplastic resin composition, comprising mixing and extruding 10 to 60% by weight of a thermoplastic resin according to the method for preparing a thermoplastic resin and 40 to 90% by weight of an aromatic vinyl compound-vinyl cyan compound copolymer.

Advantageous effects

The process for producing a thermoplastic resin according to the present invention is high in yield. The thermoplastic resin prepared by the method of the present invention has appearance properties equal to or better than those of a resin prepared using a metal salt coagulant, excellent thermal stability and improved coating properties. In addition, due to the improved coating properties, the process efficiency of the coating can be increased and the process cost can be reduced.

In addition, the thermoplastic resin prepared by the method for preparing a thermoplastic resin according to the present invention may be mixed with an aromatic vinyl compound-vinyl cyanide compound copolymer to obtain a thermoplastic resin composition having excellent physical properties, such as appearance properties, heat resistance and impact strength, as well as excellent thermal stability and coating properties. The thermoplastic resin composition of the present invention can be applied to industrial parts, electronic parts, automobile parts, and the like by a paint sprayer.

Detailed Description

Hereinafter, a method for preparing a thermoplastic resin according to the present invention, a thermoplastic resin prepared by the preparation method, and a thermoplastic resin composition comprising the thermoplastic resin will be described in detail.

The present inventors confirmed that, in order to solve the problems of the above-described conventional techniques, when a thermoplastic resin is prepared by a method comprising a step of coagulating an emulsion polymerization latex using an acid coagulating agent, a step of treating the coagulated product with a base, and a step of adding a metal salt and water to adjust the pH to a specific range, the productivity is improved, and the thermal stability, appearance properties, and coating properties of the thermoplastic resin are improved. Based on these findings, the inventors of the present invention have completed the present invention.

For example, the method for preparing a thermoplastic resin according to the present invention comprises: A) a step of acid coagulation of the emulsion polymerization latex; B) treating the coagulated slurry with an alkali and dehydrating; and C) a step of adding a metal salt and water to the dehydrated wet powder to adjust the pH to 9 or more. In this case, the productivity of the thermoplastic resin can be improved, and the thermal stability, appearance properties and coating properties of the thermoplastic resin can be improved.

Hereinafter, the method for preparing the thermoplastic resin of the present invention will be described in detail step by step.

A) Acid coagulation step

In the acid coagulation step of the present invention, an acid coagulant is added to the emulsion polymerization latex to coagulate the emulsion polymerization latex. For example, the acid coagulant may be present in an amount of 0.5 to 4 parts by weight, 0.5 to 3 parts by weight, 0.7 to 2.5 parts by weight, or 1.5 to 2.2 parts by weight, based on 100 parts by weight (based on solids) of the emulsion polymerization latex. Within this range, the productivity of the thermoplastic resin may be improved, and the thermal stability of the thermoplastic resin may be excellent.

For example, the acid may include one or more selected from sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, formic acid, and acetic acid. Preferably, the acid comprises one or more selected from the group consisting of sulfuric acid, hydrochloric acid, formic acid and acetic acid. More preferably, the acid is sulfuric acid.

For example, the acid coagulation step may be carried out at a temperature of 60 ℃ to 90 ℃, preferably 75 ℃ to 85 ℃, more preferably 70 ℃ to 80 ℃. In this temperature range, the coagulation efficiency can be improved, thereby improving the productivity of the thermoplastic resin.

For example, the acid coagulation step may be performed at an agitation speed of 150rpm to 400rpm, 250rpm to 350rpm, or 300rpm to 350rpm for 5 minutes to 20 minutes, or 10 minutes to 15 minutes, without being limited thereto.

For example, in the acid coagulation step, water and acid may be first mixed and the resulting mixture may be added, or water and acid may be added separately. Preferably, the acid coagulant is prepared by mixing acid and water, and the acid coagulant is added in the form of an acidic aqueous solution.

For example, as the acid coagulant, the acidic aqueous solution may be an aqueous solution having a molar concentration of 0.01M to 1M, preferably 0.03M to 0.8M or 0.1M to 0.7M. Further, when the acid and water are separately added, the amount of water to be added is preferably determined so that the molar concentration of the acid coagulation agent is 0.01M to 1M. Within this range, the coagulation efficiency can be improved, thereby improving productivity and thermal stability.

As another example, in an acidic aqueous solution, the concentration of the acid may be 0.1 to 10 wt.%, 1 to 6 wt.%, 1 to 5 wt.%, or 4 to 5 wt.%. Within this range, the coagulation efficiency can be improved, thereby improving the productivity of the resin.

For example, in the acid coagulation step, the pH of the coagulated slurry may be 1 to 4.5, 1.5 to 4, or 2.5 to 4. Within this range, the coagulation efficiency can be improved, thereby improving the productivity of the thermoplastic resin.

For example, the emulsion polymerization latex may be a vinyl cyanide compound-conjugated diene-aromatic vinyl compound copolymer latex (hereinafter referred to as "ABS-based resin latex").

For example, the ABS-based resin latex may be prepared by mixing 100 parts by weight of a monomer mixture comprising 40 to 70% by weight (on a solid basis) of a conjugated diene polymer, 15 to 35% by weight of an aromatic vinyl compound, and 5 to 25% by weight of a vinyl cyanide compound; 0.01 to 5 parts by weight of an emulsifier; and 0.001 to 3 parts by weight of an initiator.

In the present specification, other additives such as polymerization water and electrolyte and polymerization conditions such as reaction temperature and reaction time, which are not specifically mentioned, may be appropriately selected according to need, and the use thereof is not particularly limited as long as the additives and polymerization conditions are within the range generally suitable for the preparation of ABS-based resin latex.

In the present specification, the conjugated diene polymer may include, for example, one or more selected from the group consisting of a butadiene polymer, a butadiene-styrene copolymer, a butadiene-acrylonitrile copolymer, and an ethylene-propylene copolymer. Preferably, the conjugated diene polymer is a butadiene polymer or a butadiene-styrene copolymer.

In the present specification, the aromatic vinyl compound may include, for example, one or more selected from styrene, α -methylstyrene and p-methylstyrene. Preferably, the aromatic vinyl compound is styrene or alpha-methylstyrene. More preferably, the aromatic vinyl compound is styrene.

In the present specification, the vinyl cyanide compound may include, for example, one or more selected from acrylonitrile, methacrylonitrile, and ethacrylonitrile. Preferably, the vinyl cyanide compound is acrylonitrile.

In the present specification, the emulsifier may include, for example, one or more selected from the group consisting of alkyl aryl sulfonates, alkyl sulfates, alkyl ester sulfonates, carboxylates having 10 or more carbon atoms, alkyl (alkenyl) carboxylates, alkyl (alkenyl) succinates, fatty acid salts, rosin acid salts, and oleates, without being limited thereto.

The method of the present invention may further comprise: and a step of aging the coagulated slurry after the step A of acid coagulation. For example, the aging of the coagulated slurry may be performed at 85 ℃ to 95 ℃ or 90 ℃ to 95 ℃ for 2 minutes to 90 minutes or 10 minutes to 60 minutes. In this case, the productivity of the thermoplastic resin can be further improved.

For example, aging can be conducted at a pressure of 0.1MPa or more, 0.15MPa to 0.3MPa, 0.15MPa to 0.25MPa, or 0.22MPa to 0.25 MPa. Within this range, the moisture content of the powder can be reduced.

For example, aging can be performed at a stirring speed of 100rpm to 400rpm, 150rpm to 350rpm, or 200rpm to 300 rpm. Within this range, physical properties of the thermoplastic resin, such as impact strength and heat resistance, can be improved due to the reassembly of component particles (component particles) and increase in particle size.

B) Alkali treatment and dehydration step

In the alkali treatment step, an alkali is added to the coagulated slurry or the coagulated and aged slurry, and mixed. In this case, since the residual acid is not contained, the gloss and whiteness of the thermoplastic resin can be improved, thereby improving the appearance quality of the thermoplastic resin.

For example, the base may include one or more selected from sodium hydroxide and potassium hydroxide. Preferably, the base is sodium hydroxide.

For example, the alkali treatment may be performed at a temperature of 0 ℃ to 100 ℃, preferably 30 ℃ to 90 ℃, more preferably 50 ℃ to 90 ℃ or 70 ℃ to 80 ℃. Within this range, the appearance quality of the thermoplastic resin can be further improved.

For example, the alkali treatment may be performed at a stirring speed of 10rpm to 500rpm or 300rpm to 500rpm for 1 minute to 60 minutes or 30 minutes to 60 minutes. Within this range, a thermoplastic resin having excellent appearance quality can be produced with high productivity.

In the alkali treatment step, water and an alkali may be first mixed, and then the resulting mixture may be added, or water and an alkali may be added separately. Preferably, the base and water are mixed and the mixture is added in the form of an aqueous alkaline solution.

For example, the basic aqueous solution may be an aqueous solution having a molarity of 0.01M to 5M, preferably 0.5M to 4M or 2M to 4M. Further, when the alkali and the water are separately added, the amount of water to be added is preferably determined so that the molar concentration of the alkali is within the concentration range of the alkaline aqueous solution. Within this range, the productivity of the thermoplastic resin can be improved, and the appearance quality thereof can be improved.

As another example, in the basic aqueous solution, the concentration of the base may be 1 to 20 wt%, 5 to 15 wt%, or 8 to 12 wt%. Within this range, productivity and appearance quality can be improved.

For example, the aqueous alkaline solution can be present in an amount of 0.5 to 5 parts by weight, 0.5 to 3 parts by weight, or 1 to 2 parts by weight, based on 100 parts by weight (based on solids) of the emulsion polymerization latex. Within this range, the productivity of the thermoplastic resin can be improved, and the appearance quality thereof can be improved.

In step B, a dehydration method commonly used in the art to which the present invention pertains may be used as the dehydration method of the present invention without particular limitation. For example, the dewatering of the alkali-treated slurry can be performed using a centrifugal dewatering machine or a compression dewatering machine.

For example, the pH of the wet powder obtained after dehydration is 10.5 or more, preferably 11 or more, more preferably 11 to 11.5. Within this range, since the wet powder does not contain residual acid, the gloss and whiteness of the thermoplastic resin can be improved, thereby improving the appearance quality.

In the present specification, pH may be measured using a pH titration method or a pH meter which is generally used in the art to which the present invention pertains. As a specific example, a Mettler Toledo SevenExellencepH meter may be used, and when the sample is a wet powder rather than an aqueous solution, 10g of the wet powder and 100g of distilled water may be mixed and stirred for 10 minutes, and then the pH may be measured.

C) Step of adding metal salt and water to adjust pH to 9 or more

In the method for preparing a thermoplastic resin according to the present invention, in order to solve the problem of lowering thermal stability due to the residual emulsifier in the form of a salt that cannot be removed even by alkali treatment after acid coagulation, a step of adding a metal salt and water to the dehydrated wet powder to adjust the pH to 9 or more (but lower than the pH of the dehydrated wet powder) may be included.

For example, the metal salt may include one or more selected from magnesium sulfate, magnesium chloride, calcium chloride, and aluminum sulfate. Preferably, the metal salt is magnesium sulfate. In this case, the productivity of the thermoplastic resin can be improved, and the appearance properties, thermal stability and coating properties of the thermoplastic resin can be excellent. In particular, the appearance properties and coating properties of the thermoplastic resin can be greatly improved, so that a high-quality thermoplastic resin can be provided.

For example, emulsion polymerization latexes prepared using carboxylate emulsifiers form RCOO-H type compounds in an acid coagulation step by the combination of the emulsifier and acid. In the alkali treatment step, when sodium hydroxide is used as the alkali, the compound of the RCOO-H type reacts with the alkali to form RCOO^-Na⁺A compound of the formula (I). For example, if according to the invention, in step C magnesium sulfate is used as metal salt, form (RCOO)₂A compound of the Mg type. With residual RCOO produced during conventional alkali treatment^-Na⁺Form (RCOO) or treatment with acid^-Na⁺Comparison of the RCOO-H form of the compound formed with (RCOO)₂The Mg type compound has excellent thermal stability, and therefore, a thermoplastic resin having excellent appearance properties and coating properties can be provided.

The metal salt may be present in an amount of 0.05 to 0.5 parts by weight or 0.1 to 0.3 parts by weight, based on 100 parts by weight (on a solids basis) of the emulsion polymerization latex. Within this range, the productivity of the thermoplastic resin can be improved, and the appearance properties and coating properties thereof can be greatly improved.

In step C, water and a metal salt may be first mixed and the resulting mixture added, or water and a metal salt may be added separately.

For example, the amount of water to be added may be determined such that the concentration of solids is 15 to 30 wt% or 15 to 20 wt%. Within this range, the productivity of the thermoplastic resin can be improved, and the appearance properties and coating properties thereof can be improved.

As another example, the water content can be 230 to 570 parts by weight or 400 to 570 parts by weight, based on 100 parts by weight (on a solids basis) of the emulsion polymerization latex. Within this range, the productivity of the thermoplastic resin can be improved, and the appearance properties and coating properties thereof can be greatly improved.

In step C, a metal salt and water are added to the dehydrated wet powder to adjust the pH to 9 or above or 9 to 12, preferably 9 to 11 or 9 to 10.5 (but below the pH of the dehydrated wet powder). Within this range, the thermoplastic resin may be excellent in heat resistance, may be improved in appearance properties such as gloss and whiteness, and, at the same time, may be improved in coating properties.

Further, when the pH of the dehydrated wet powder is adjusted within the above range, there is an advantage of greatly increasing the oxidation induction time (OIP), which is an index representing the thermal stability of the thermoplastic resin. This is because the metal salt introduced in step C reacts with the base remaining after step B to form a compound having a high decomposition point. For example, when magnesium sulfate is added as a metal salt in step C and sodium hydroxide is added as a base in step B, the magnesium sulfate and the sodium hydroxide react with each other to form magnesium hydroxide as shown in the following reaction formula 1. In this case, since magnesium hydroxide has a higher decomposition point than the metal salt, magnesium hydroxide can increase the ignition point, thereby improving the thermal stability of the resin.

[ reaction formula 1]

Mg²⁺(aq)+2OH^-(aq)→Mg(OH)₂(s)

The method for producing a thermoplastic resin according to the present invention may further include, after step C, a step of dehydrating and drying the wet powder whose pH has been adjusted to 9 or more to obtain a thermoplastic resin powder.

In the dehydration process performed after step C, any dehydration method commonly used in the art to which the present invention pertains may be used without particular limitation. For example, the acid-treated slurry may be dewatered using a centrifugal dehydrator or a compressive dehydrator.

For example, the dehydration process performed after step C may be performed by adding 5 to 20 parts by weight, 5 to 15 parts by weight, or 8 to 13 parts by weight of water, based on 100 parts by weight (on a solid basis) of the wet powder whose pH has been adjusted to 9 or more. In this case, the dehydration process can be easily performed.

The moisture content of the wet powder obtained after the dehydration process is preferably 25 wt% or less or 22 wt% or less. In this case, productivity of the resin can be improved.

In this specification, the moisture content was measured using a HR83-P moisture analyzer (Mettler-Toledo Co., Switzerland). In this case, the weight change before and after drying was measured after complete drying at 150 ℃, and the weight loss was expressed as a percentage.

Any known drying method commonly used in the art to which the present invention pertains may be used in the drying process of the present invention without particular limitation. For example, in the drying process, air may be supplied to the dehydrated resin powder using a fluidized bed dryer.

For example, the oxidation induction time of the thermoplastic resin obtained by the method of the present invention may be 20 minutes or more, 25 minutes or more, 20 minutes to 30 minutes, 25 minutes to 35 minutes, or 28 minutes to 32 minutes. Within this range, the thermal stability of the thermoplastic resin can be improved and the appearance properties thereof, such as whiteness, can be improved.

In this specification, unless otherwise specified, oxidation induction times are measured using Differential Scanning Calorimetry (DSC) according to standard measurement ASTM D3895. In this case, thermoplastic resin powder was prepared, and the time when oxidation occurred was measured while supplying oxygen to the thermoplastic resin powder at 50ml per minute under isothermal conditions of 190 ℃.

Hereinafter, a thermoplastic resin prepared by the method for preparing a thermoplastic resin of the present invention, a thermoplastic resin composition comprising the same, and a method for preparing the same will be described in detail. Since the thermoplastic resin of the present invention, the composition comprising the same, and the method for preparing the same share all technical features included in the above-described method for preparing a thermoplastic resin, a repetitive description thereof is omitted.

For example, the thermoplastic resin of the present invention may be prepared by the preparation method of the thermoplastic resin, and may have an oxidation induction time of 20 minutes or more. In this case, the mechanical strength, heat resistance and appearance properties of the thermoplastic resin can be improved. In particular, when the thermoplastic resin is used in a coating layer, the adhesive strength and appearance quality of the coating film can be improved.

For example, the thermoplastic resin composition of the present invention comprises 10 to 60% by weight of the thermoplastic resin and 40 to 90% by weight of the aromatic vinyl compound-vinyl cyan compound copolymer. In this case, the productivity, impact strength, heat resistance, gloss and whiteness of the composition may be excellent.

For example, the method for preparing the thermoplastic resin composition of the present invention may include the steps of mixing 10 to 60% by weight of the thermoplastic resin obtained by the method for preparing the thermoplastic resin and 40 to 90% by weight of the aromatic vinyl compound-vinyl cyan compound copolymer and extruding the mixture. In this case, the impact strength, heat resistance, gloss and whiteness of the obtained composition can be improved. In addition, since the "b" value measured using a color difference meter is low, the appearance quality, thermal stability and coating properties of the composition may be excellent.

As another example, the method for preparing the thermoplastic resin composition of the present invention may include the steps of mixing 20 to 50% by weight of the thermoplastic resin and 50 to 80% by weight of the aromatic vinyl compound-vinyl cyan compound copolymer and extruding the mixture. Within this range, the composition may be excellent in impact strength, heat resistance, gloss and whiteness, and at the same time, the appearance quality, heat stability and coating properties of the composition may be improved.

For example, the aromatic vinyl compound-vinyl cyan compound copolymer may include 50 to 90% by weight of an aromatic vinyl compound and 10 to 50% by weight of a vinyl cyan compound. As another example, the aromatic vinyl compound-vinyl cyan compound copolymer may include 60 to 80% by weight of an aromatic vinyl compound and 20 to 40% by weight of a vinyl cyan compound. Within this range, molding of the composition can be easily performed. In addition, the composition can be excellent in impact strength, heat resistance, gloss and whiteness, while improving appearance quality, heat stability and coating properties.

For example, the aromatic vinyl compound may include one or more selected from styrene, α -methylstyrene and p-methylstyrene. Preferably, the aromatic vinyl compound is styrene or alpha-methylstyrene. More preferably, the aromatic vinyl compound is styrene.

For example, the vinyl cyanide compound may include one or more selected from acrylonitrile, methacrylonitrile, and ethacrylonitrile. Preferably, the vinyl cyanide compound is acrylonitrile.

Optionally, the thermoplastic resin composition may include one or more additives selected from the group consisting of a lubricant, an antioxidant, a heat stabilizer and a light stabilizer. The additive may be added in an amount not to deteriorate the effect of the present invention. Preferably, the additive may be present in an amount of 5 wt% or less, 0.001 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on the total weight of the composition.

For example, the extrusion may be performed at 150 ℃ to 300 ℃ and 100rpm to 500rpm or at 200 ℃ to 300 ℃ and 200rpm to 300rpm, without being limited thereto.

For example, the thermoplastic resin has a "b" value of 10 or less or 9.45 or less, which is measured using a Color difference meter (Color questli, Hunter Lab Co.). This indicates that the appearance quality of the thermoplastic resin is excellent.

In the present specification, the "b" value is measured using a colorimeter (Color Quest II, Hunter Lab Co.). Based on 0, the "b" value can be a positive (+) or negative (-) value. A positive (+) "b" value indicates that the thermoplastic resin is yellow, and a negative (-) "b" value indicates that the thermoplastic resin is blue. When the resin has a positive "b" value, the absolute value of the "b" value is proportional to the degree of yellowing of the resin.

For example, the thermoplastic resin composition may have a plating adhesion of 15N/cm or more, 15N/cm to 20N/cm, 16N/cm to 20N/cm, 16.5N/cm or more, or 16.5N/cm to 20N/cm. Within this range, the coating properties of the thermoplastic resin composition may be excellent.

In the present specification, when the adhesion of the plating layer was measured, a scratch of 10mm width was formed on the front surface of a test piece plated with a thermoplastic resin composition having a length of 100mm, a width of 100mm and a thickness of 3 mm. Then, a value at which the coating film was peeled by 80mm in the vertical direction was measured using a push-pull dynamometer, and the obtained values were averaged to calculate the plating adhesion.

In describing the method for preparing the thermoplastic resin and the method for preparing the thermoplastic resin composition according to the present invention, other additives, conditions, equipment, and the like not specifically described may be appropriately selected for use without particular limitation within the scope of general practice in the art.

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.

The emulsion polymerization latex used in the preparation of the thermoplastic resin was prepared by the following method.

[ preparation example 1]

Emulsion polymerizationPreparation of synthetic latex

90 parts by weight of deionized water, 60 parts by weight (based on solids) of a butadiene polymer latex having an average particle diameter of) 15 parts by weight of styrene, 7.5 parts by weight of acrylonitrile, 0.1 part by weight of potassium alkenylC 16-18 succinate (ELOPLA AS100) and 0.3 part by weight of potassium fatty acid salt AS emulsifiers, 0.04 part by weight of t-butyl hydroperoxide and 0.4 part by weight of t-dodecyl mercaptan AS initiators, 0.05 part by weight of sodium pyrophosphate, 0.05 part by weight of glucose and 0.001 part by weight of ferrous sulfide were added in portions to a nitrogen-purged polymerization reactor, and polymerization was carried out for 1 hour while raising the temperature to 70 ℃. After polymerization, an emulsion containing 10 parts by weight of deionized water, 15 parts by weight of styrene, 7.5 parts by weight of acrylonitrile, 0.1 part by weight of potassium alkenylC 16-18 succinate (ELOPLA AS100), 1.0 part by weight of potassium fatty acid salt, 0.04 part by weight of t-butyl hydroperoxide, 0.05 part by weight of sodium pyrophosphate, 0.05 part by weight of glucose, 0.001 part by weight of ferrous sulfide, and 0.1 part by weight of cumene hydroperoxide was continuously added to the reactor over 60 minutes, heated to 80 ℃ and aged for 1 hour. After aging, the reaction was terminated.