Patent Description:
An acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) resin is applied to various products, such as automobile appliances, electric and electronic products, and office equipment, due to stiffness and chemical resistance of acrylonitrile therein and processability, mechanical strength and beautiful appearance of butadiene and styrene therein.

Such an ABS resin is generally subjected to post-processing. As a representative post-processing step, there is a painting process. In this painting process, a chemical solvent, such as a thinner, is used to properly coat a paint on an ABS resin. However, when such a chemical solvent is used, the chemical solvent chemically attacks the ABS resin, whereby problems, such as crack generation in the ABS resin, may occur. In addition, such minute cracks eventually cause defects, such as pinholes and stains, in the paint.

Accordingly, methods, such as rubber content increase, rubber size increase, acrylonitrile content increase, and resin molecular weight increase, have been mainly used to reinforce chemical resistance against a chemical solvent. However, these methods eventually lower fluidity of an ABS resin, whereby residual stress of a molded article prior to painting increases. Accordingly, problems, such as pinhole generation in paint, are still present. Therefore, there is an urgent need for chemical resistance increase and paintability improvement of an ABS resin.

[Patent Document] (Patent Document <NUM>) <CIT>
<CIT>, <CIT> and <CIT> disclose a thermoplastic resin composition, comprising: <NUM> parts by weight of a base resin comprising (a) an aromatic vinyl compound-conjugated diene-based compound-vinyl cyan compound copolymer and (b)an aromatic vinyl compound-vinyl cyan compound copolymer; and (c) greater than <NUM> parts by weight and less than <NUM> parts by weight of a polyolefin oxide-based triblock copolymer.

<CIT> discloses compositions comprising ABS, SAN and an EO/PO triblock copolymer, said compositions also comprising a major amount of polycarbonate.

Therefore, the present disclosure has been made in view of the above problems, and it is one object of the present disclosure to provide a thermoplastic resin composition having superior chemical resistance and paintability with identical or superior impact strength, fluidity, and heat resistance, to conventional thermoplastic resin compositions.

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

In accordance with one aspect of the present disclosure, provided is a thermoplastic resin composition comprising: <NUM> parts by weight of a base resin comprising (a) <NUM>% by weight of a styrene-butadiene-acrylonitrile graft copolymer, in which the average particle diameter of the butadiene rubber is <NUM>, and (b) <NUM>% by weight of an alpha-methylstyrene-acrylonitrile copolymer; and (c) <NUM> part by weight of a polyolefin oxide-based triblock copolymer,.

wherein (c) the polyolefin oxide-based triblock copolymer is a polyethylene oxide-polypropylene oxide triblock copolymer, the polyethylene oxide is comprised in an amount of <NUM> % by weight with respect to (c) the polyolefin oxide-based triblock copolymer, and a number average molecular weight (Mn) of the polypropylene oxide is <NUM>,<NUM>/mol.

As apparent from the foregoing, the present disclosure advantageously provides a thermoplastic resin composition having superior chemical resistance and paintability with identical or superior impact strength, fluidity, and heat resistance, to conventional thermoplastic resin compositions.

Hereinafter, the present disclosure is described in detail.

The present inventors confirmed that, when a polyolefin oxide-based triblock copolymer is included in a predetermined amount in a thermoplastic resin composition, the thermoplastic resin composition exhibits increased chemical resistance and improved paintability, thus completing the present invention.

Hereinafter, the thermoplastic resin composition according to the present invention is described in detail. The thermoplastic resin composition includes: <NUM> parts by weight of a base resin comprising (a) <NUM>% by weight of a styrene-butadiene-acrylonitrile graft copolymer, in which the average particle diameter of the butadiene rubber is <NUM>, and (b) <NUM>% by weight of an alpha-methylstyrene-acrylonitrile copolymer; and (c) <NUM> part by weight of a polyolefin oxide-based triblock copolymer,.

The butadiene of (a) the styrene-butadiene-acrylonitrile graft copolymermay be included in an amount of, for example, <NUM> to <NUM> % by weight, <NUM> to <NUM> % by weight, or <NUM> to <NUM> % by weight with respect to (a) the styrene-butadiene-acrylonitrile graft copolymer. Within this range, excellent mechanical properties are provided.

The styrene included in (a) the styrene-butadiene-acrylonitrile graft copolymer may be included in an amount of, for example, <NUM> to <NUM> % by weight, <NUM> to <NUM> % by weight, or <NUM> to <NUM> % by weight with respect to (a) the styrene-butadiene-acrylonitrile graft copolymer. Within this range, superior fluidity and property balance are provided.

The alpha-methyl styrene included in (b) the alpha-methylstyrene-acrylonitrile copolymer may be included in an amount of, for example, <NUM> to <NUM> % by weight, <NUM> to <NUM> % by weight, or <NUM> to <NUM> % by weight with respect to (b) the alpha-methylstyrene-acrylonitrile copolymer. Within this range, superior mechanical properties and property balance are provided.

The acrylonitrile included in (a) the styrene-butadiene-acrylonitrile graft copolymer may be included in an amount of, for example, <NUM> to <NUM> % by weight, <NUM> to <NUM> % by weight, or <NUM> to <NUM> % by weight with respect to with respect to (b) the alpha-methylstyrene-acrylonitrile copolymer. Within this range, superior chemical resistance and heat resistance are provided.

The acrylonitrile included in (b) the alpha-methylstyrene-acrylonitrile copolymer may be included in an amount, for example, <NUM> to <NUM> % by weight, <NUM> to <NUM> % by weight, or <NUM> to <NUM> % by weight with respect to (b) the alpha-methylstyrene-acrylonitrile copolymer. Within this range, superior mechanical properties and chemical resistance are provided.

(a) The styrene-butadiene-acrylonitrile graft copolymer may be prepared, for example, through emulsion polymerization, bulk polymerization, solution polymerization or suspension polymerization. Preferably, (a) the styrene-butadiene-acrylonitrile graft copolymer is prepared through emulsion polymerization. In this case, it is easy to control reaction, whereby desired molecular weight distribution may be accomplished.

In the present disclosure, an average particle diameter was measured by a dynamic laser light scattering method using a Nicomp 370HPL instrument (manufactured by Nicomp, US).

The polyethylene oxide-polypropylene oxide triblock copolymer may be represented by, for example, Formula <NUM> or <NUM> below;
<CHM>
<CHM>.

In Formulas <NUM> and <NUM>, R1 and R2 are each independently hydrogen, an alkyl group having a carbon number of <NUM> to <NUM>, a cycloalkyl group having a carbon number of <NUM> to <NUM>, an aryl group having a carbon number of <NUM> to <NUM>, or an alkylaryl group having a carbon number of <NUM> to <NUM>, and x, y, z, l, m, and n are each independently an integer of <NUM> to <NUM>.

R1 and R2 may be, for example, hydrogen, and x, y, z, <NUM>, m, and n may be each independently, for example, an integer of <NUM> to <NUM>, or <NUM> to <NUM>.

The polyethylene oxide is includedin an amount of <NUM> % by weight with respect to the polyolefin oxide-based triblock copolymer. Within this range, superior chemical resistance and paintability are provided.

The polypropylene oxide has a number average molecular weight (Mnof <NUM>,<NUM>/mol. Within this range, superior heat resistance, chemical resistance, and paintability are provided.

The polyolefin oxide-based triblock copolymer may have a number average molecular weight (Mn) of, for example, <NUM>,<NUM> to <NUM>,<NUM>/mol, <NUM>,<NUM> to <NUM>,<NUM>/mol, or <NUM>,<NUM> to <NUM>,<NUM>/mol. Within this range, superior heat resistance, chemical resistance, and paintability are provided.

In the present disclosure, a number average molecular weight may be measured by GPC analysis.

The polyolefin oxide-based triblock copolymer is included in an amount of <NUM> part by weight with respect to the thermoplastic resin composition. Within this range, superior heat resistance, chemical resistance, and paintability are provided.

The thermoplastic resin composition may have, for example, a chemical resistance of greater than <NUM> sec, <NUM> sec or more, or <NUM> to <NUM> sec. Within this range, superior chemical resistance against a chemical solvent is provided, whereby pinholes are not generated during painting.

The thermoplastic resin composition might not exhibit pinholes, for example, after a paintability test (drying in an <NUM> oven).

A molded article includes the thermoplastic resin composition.

The molded article may be, for example, an injection-molded article. Particularly, the molded article may be an automobile interior material or an automobile exterior material.

Now, the present invention will be described in more detail with reference to the following preferred examples.

<NUM> parts by weight of a base resin, which included <NUM> % by weight of an ABS graft copolymer (product name: DP270, manufactured by LG Chemical), in which the average particle diameter of butadiene rubber was <NUM>, and <NUM> % by weight of an AMSAN copolymer (product name: 100UH, manufactured by LG Chemical); and <NUM> part by weight of a polyethylene oxide-polypropylene oxide triblock copolymer (<NUM>), in which the number average molecular weight of the polypropylene oxide was <NUM>,<NUM>/mol and the polyethylene oxide was included in a content of <NUM> % by weight, were fed into an extruder, followed by melting and kneading at <NUM>. As a result, a pellet-type resin composition was prepared. The prepared pellet-type resin composition was injected to produce a specimen for property measurement.

An experiment was carried out in the same manner as in Example <NUM>, except that the polyethylene oxide-polypropylene oxide triblock copolymer (<NUM>) was added in an amount of <NUM> parts by weight.

An experiment was carried out in the same manner as in Example <NUM>, except that a base resin including <NUM> % by weight of an ABS graft copolymer and <NUM> % by weight of an AMSAN copolymer was used.

<NUM> parts by weight of a base resin, which included <NUM> % by weight of an ABS graft copolymer (product name: DP270, manufactured by LG Chemical) and <NUM> % by weight of an SAN copolymer (product name: 92HR, manufactured by LG Chemical); and <NUM> part by weight of a polyethylene oxide-polypropylene oxide triblock copolymer (<NUM>), in which the number average molecular weight of the polypropylene oxide was <NUM>,<NUM>/mol and the polyethylene oxide was included in a content of <NUM> % by weight, were fed into an extruder, followed by melting and kneading at <NUM>. As a result, a pellet-type resin composition was prepared. The prepared pellet-type resin composition was injected to produce a specimen for property measurement.

An experiment was carried out in the same manner as in Example <NUM>, except that a base resin including <NUM> % by weight of an ABS graft copolymer and <NUM> % by weight of an SAN copolymer was used.

<NUM> parts by weight of a base resin, which included <NUM> % by weight of an ABS graft copolymer (product name: DP270, manufactured by LG Chemical), in which the average particle diameter of butadiene rubber was <NUM>, <NUM> % by weight of an ABS graft copolymer (manufactured by LG Chemical), in which the average particle diameter of butadiene rubber was <NUM>, and <NUM> % by weight of an AMSAN copolymer (product name: 100UH, manufactured by LG Chemical); and <NUM> part by weight of a polyethylene oxide-polypropylene oxide triblock copolymer (<NUM>), in which the number average molecular weight of the polypropylene oxide was <NUM>,<NUM>/mol and the polyethylene oxide was included in a content of <NUM> % by weight, were fed into an extruder, followed by melting and kneading at <NUM>. As a result, a pellet-type resin composition was prepared. The prepared pellet-type resin composition was injected to produce a specimen for property measurement.

<NUM> parts by weight of a base resin, which included <NUM> % by weight of an ABS graft copolymer (product name: DP270, manufactured by LG Chemical), <NUM> % by weight of an AMSAN copolymer (product name: 100UH, manufactured by LG Chemical), and <NUM> % by weight of an SAN copolymer (product name: 92HR, manufactured by LG Chemical); and <NUM> parts by weight of a polyethylene oxide-polypropylene oxide triblock copolymer (<NUM>), in which the number average molecular weight of the polypropylene oxide was <NUM>,<NUM>/mol and the polyethylene oxide was included in a content of <NUM> % by weight, were fed into an extruder, followed by melting and kneading at <NUM>. As a result, a pellet-type resin composition was prepared. The prepared pellet-type resin composition was injected to produce a specimen for property measurement.

An experiment was carried out in the same manner as in Example <NUM>, except that the polyethylene oxide-polypropylene oxide triblock copolymer was not added.

An experiment was carried out in the same manner as in Example <NUM>, except that the polyethylene oxide-polypropylene oxide triblock copolymer was added in an amount of <NUM> parts by weight.

An experiment was carried out in the same manner as in Comparative Example <NUM>, except that the ABS graft copolymer was added in an amount of <NUM> % by weight instead of the amount of <NUM> % by weight, and the AMSAN copolymer was added in an amount of <NUM> % by weight instead of the amount of <NUM> % by weight.

The properties of the thermoplastic resin composition specimen obtained according to each of Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> were measured according to the following methods. Results are summarized in Table <NUM> below.

As summarized in Table <NUM>, it can be confirmed that, in the cases of the specimens of Example <NUM> to <NUM> prepared according to the present invention, all of impact strength, fluidity, and heat deflection temperature are superior, chemical resistance is excellent, and pinholes are not generated in the painted surfaces. In addition, it can be confirmed that, in the cases of the specimens of Examples <NUM> and <NUM> including the SAN copolymer instead of the heat-resistant AMSAN copolymer, chemical resistance is remarkably improved and pinholes are not generated in the painted surfaces.

In addition, it can be confirmed that, in the case of the specimen of Example <NUM> in which the ABS graft copolymer having a small particle size was applied, heat deflection temperature is superior. Further, it can be confirmed that, in the case of the specimen of Example <NUM> in which general SAN and AMSAN resins were used together, superior chemical resistance, impact strength, and fluidity are exhibited despite application of a small amount of triblock copolymer.

On the other hand, it can be confirmed that, in the cases of the specimen of Comparative Example <NUM>, in which the polyethylene oxide-polypropylene oxide triblock copolymer was not added, and Comparative Examples <NUM> and <NUM>, in which the polyethylene oxide-polypropylene oxide triblock copolymer was added in a small amount, chemical resistance is very poor and a large number of pinholes is formed. In addition, it can be confirmed that, in the case of the specimen of Comparative Example <NUM> in which the polyethylene oxide-polypropylene oxide triblock copolymer was added in a large amount, all of impact strength, heat deflection temperature, chemical resistance, and paintability are decreased. Further, it can be confirmed that, in the case of the specimen of Comparative Example <NUM>, in which a rubber content is increased instead of addition of the polyethylene oxide-polypropylene oxide triblock copolymer, fluidity and heat deflection temperature are decreased, chemical resistance is poor, and a large number of pinholes is formed.

In addition, it can be confirmed that, in the case of the specimen of Comparative Example <NUM> in which an SAN copolymer is included instead of the heat-resistant AMSAN copolymer and the polyethylene oxide-polypropylene oxide triblock copolymer is not included, overall properties are decreased and paintability is very poor.

An experiment was carried out in the same manner as in Example <NUM>, except that a polyethylene oxide-polypropylene oxide triblock copolymer in which the number average molecular weight of polypropylene oxide was <NUM>/mol and a polyethylene oxide content was <NUM> % by weight was added, in the same amount, instead of the polyethylene oxide-polypropylene oxide triblock copolymer in which the number average molecular weight of polypropylene oxide was <NUM>,<NUM>/mol and a polyethylene oxide content was <NUM> % by weight. As a result, an impact strength of <NUM> kgf·cm/cm, a fluidity of <NUM>/<NUM>, a heat deflection temperature of <NUM>, a chemical resistance of <NUM> sec, and paintability of △ were observed.

An experiment was carried out in the same manner as in Example <NUM>, except that a polyethylene oxide-polypropylene oxide triblock copolymer (<NUM>), in which a polyethylene oxide content was <NUM>% and a number average molecular weight was <NUM>,<NUM>, was added instead of the polyethylene oxide-polypropylene oxide triblock copolymer. As a result, an impact strength of <NUM> kgf·cm/cm, a fluidity of <NUM>/<NUM>, a heat deflection temperature of <NUM>, a chemical resistance of <NUM> sec, and a paintability of X were observed.

From the results of Reference Examples <NUM> and <NUM>, it can be confirmed that the number average molecular weight of the polypropylene oxide and the polyethylene oxide content considerably affect the properties of the thermoplastic resin composition of the present disclosure.

Claim 1:
A thermoplastic resin composition comprising: <NUM> parts by weight of a base resin comprising (a) <NUM>% by weight of a styrene-butadiene-acrylonitrile graft copolymer, in which the average particle diameter, as measured by dynamic laser light scattering method, of the butadiene rubber is <NUM>, and (b) <NUM>% by weight of an alpha-methylstyrene-acrylonitrile copolymer; and (c) <NUM> part by weight of a polyolefin oxide-based triblock copolymer,
wherein (c) the polyolefin oxide-based triblock copolymer is a polyethylene oxide-polypropylene oxide triblock copolymer, the polyethylene oxide is comprised in an amount of <NUM> % by weight with respect to (c) the polyolefin oxide-based triblock copolymer, and a number average molecular weight (Mn), as measured by GPC analysis, of the polypropylene oxide is <NUM>,<NUM>/mol.