Patent Description:
Recently, thermoplastic resins, which have been widely applied to electric and electronic, automobile, building materials, and leisure products, are rapidly replacing existing glass or metal fields. Accordingly, there is an increasing demand for a thermoplastic resin capable of realizing improved impact resistance, weather resistance, molding processability, and high quality appearance.

In general, when an acrylonitrile-butadiene-styrene resin (hereinafter referred to as ABS resin) is used as a thermoplastic resin, there is a problem that an unsaturated double bond of the butadiene-based rubbery polymer is stimulated and decomposed by UV. This problem causes discoloration or cracking of the product made of ABS resin. On the other hand, an acrylonitrile-styrene-acrylate resin (hereinafter referred to as ASA resin) that use an acrylate-based rubbery polymer instead of a butadiene-based rubbery polymer may is known as an alternative to solve the problem of decomposition due to UV because the acrylate-based rubbery polymer does not have unsaturated double bonds. In addition, an ASA resin has a lower specific gravity than glass or metal, and has excellent advantages such as moldability, chemical resistance, and thermal stability.

According to the recent environmental trend, there is an increasing demand for uncoated resin that does not undergo a painting process. Since the surface of the molded product using the uncoated resin is not covered by painting, it is necessary to implement improved appearance characteristics of the uncoated resin itself.

In order to improve the appearance characteristics of the uncoated resin, it is necessary to suppress a generation of flow marks on the surface of the molded product using the uncoated resin. For this purpose, attempts have been made to use a small particle-diameter impact-reinforcing agent or to improve fluidity of the resin, but the impact resistance of the resin may be significantly reduced.

<CIT> discloses a thermoplastic acrylic resin having improved coloring property and heat resistance by comprising an acrylic graft copolymer, an aromatic vinyl-cyano vinyl-based copolymer and an acrylic resin, and thus is suitable for an automotive exterior material.

<CIT> discloses a low gloss ASA-based resin having excellent weatherability and heat resistance is provided. It is obtained by blending a general SAN copolymer, a heat-resistant SAN copolymer, a crosslinked aromatic vinyl compound-cyanide vinyl compound copolymer, and an amorphous inorganic material with large diameter and extra-large diameter ASA graft copolymers at a predetermined composition ratio.

<CIT> discloses a thermoplastic resin having improved adhesive strength and weather resistance, said resin comprising <NUM> parts by weight of an acrylic graft copolymer; and <NUM>-<NUM> parts by weight of a cyanovinyl compound-aromatic vinyl compound copolymer having a weight average molecular weight of <NUM>,<NUM>,<NUM>-<NUM>,<NUM>,<NUM>.

<CIT> discloses a thermoplastic resin having excellent weather resistance, impact resistance, and coloring properties, which includes (A) a first rubber-modified acryl-based graft copolymer having average particle diameter of <NUM> or more and <NUM> or less; (B) a second rubber-modified acryl-based graft copolymer having average particle diameter of <NUM> or more and <NUM> or less; (C) a first vinyl-based copolymer having an aromatic vinyl monomer and an unsaturated nitrile monomer copolymerized; and (D) a second vinyl-based copolymer having an alkyl(meth)acrylate monomer, an aromatic vinyl monomer, and an unsaturated nitrile monomer copolymerized,.

Therefore, it is necessary to develop a thermoplastic resin composition capable of realizing improved appearance characteristics while maintaining improved impact resistance and fluidity.

An embodiment provides a thermoplastic resin composition capable of realizing improved appearance characteristics while maintaining improved impact resistance and fluidity.

Another embodiment provides a molded product using the thermoplastic resin composition.

According to the invention, a thermoplastic resin composition includes a base resin including (A-<NUM>) <NUM> wt% to <NUM> wt% of a first acrylate-based graft copolymer having an acrylate-based rubbery polymer with an average particle diameter of <NUM> to <NUM>; (A-<NUM>) <NUM> wt% to <NUM> wt% of a second acrylate-based graft copolymer having an acrylate-based rubbery polymer with an average particle diameter of <NUM> to <NUM>; (B) <NUM> wt% to <NUM> wt% of an aromatic vinyl compound-vinyl cyanide compound copolymer; and (C) <NUM> wt% to <NUM> wt% of α-methylstyrene-based copolymer, and (D) <NUM> to <NUM> parts by weight of an ultrahigh molecular weight styrene-acrylonitrile copolymer having a weight average molecular weight of greater than or equal to <NUM>,<NUM>,<NUM>/mol, based on <NUM> parts by weight of the base resin.

At least one of the first acrylate-based graft copolymer (A-<NUM>) and the second acrylate-based graft copolymer (A-<NUM>) may be a graft copolymer of <NUM> wt% to <NUM> wt% of a mixture of an aromatic vinyl compound and a vinyl cyanide compound onto <NUM> wt% to <NUM> wt% of the acrylate-based rubbery polymer.

At least one of the first acrylate-based graft copolymer (A-<NUM>) and the second acrylate-based graft copolymer (A-<NUM>) may be an acrylonitrile-styrene-acrylate graft copolymer.

The aromatic vinyl compound-vinyl cyanide compound copolymer (B) may have a weight average molecular weight of <NUM>,<NUM>/mol to <NUM>,<NUM>/mol.

In the aromatic vinyl compound-vinyl cyanide compound copolymer (B), the aromatic vinyl compound may include styrene unsubstituted or substituted with a halogen or a C1 to C10 alkyl group (but not including α-methylstyrene), or a combination thereof.

In the aromatic vinyl compound-vinyl cyanide compound copolymer (B), the vinyl cyanide compound may include acrylonitrile, methacrylonitrile, fumaronitrile, or a combination thereof.

In the α-methylstyrene-based copolymer (C), the aromatic vinyl compound may include styrene unsubstituted or substituted with a halogen or a C1 to C10 alkyl group (but not including α-methylstyrene), or a combination thereof and the vinyl cyanide compound may include acrylonitrile, methacrylonitrile, fumaronitrile, or a combination thereof.

The thermoplastic resin composition may further include at least one additive selected from an ultraviolet (UV) stabilizer, a fluorescent whitening agent, a releasing agent, a nucleating agent, an inorganic material, a lubricant, an antistatic agent, a heat stabilizer, an impact-reinforcing agent, a pigment, and a dye.

Meanwhile, according to another embodiment, a molded product using the aforementioned thermoplastic resin composition is provided.

The thermoplastic resin composition may be capable of realizing improved appearance characteristics while maintaining improved impact resistance and fluidity.

Hereinafter, embodiments of the present invention are described in detail.

In the present invention, unless otherwise described, the average particle diameter means a Z-average particle diameter measured using a dynamic light scattering analyzer.

The thermoplastic resin composition may include a base resin including (A-<NUM>) <NUM> wt% to <NUM> wt% of a first acrylate-based graft copolymer having an acrylate-based rubbery polymer with an average particle diameter of <NUM> to <NUM>, (A-<NUM>) <NUM> wt% to <NUM> wt% of a second acrylate-based graft copolymer having an acrylate-based rubbery polymer with an average particle diameter of <NUM> to <NUM>, (B) <NUM> wt% to <NUM> wt% of an aromatic vinyl compound-vinyl cyanide compound copolymer, and (C) <NUM> wt% to <NUM> wt% of α-methylstyrene-based copolymer, and (D) <NUM> to <NUM> parts by weight of an ultrahigh molecular weight styrene-acrylonitrile copolymer having a weight average molecular weight of greater than or equal to <NUM>,<NUM>,<NUM>/mol, based on <NUM> parts by weight of the base resin.

Hereinafter, each component included in the thermoplastic resin composition is described in detail.

The thermoplastic resin composition according to an embodiment includes a first acrylate-based graft copolymer (A-<NUM>) and a second acrylate-based graft copolymer (A-<NUM>) having different average particle diameters. When the acrylate-based graft copolymers having different average particle diameters are used together, the thermoplastic resin composition including the same may realize improved appearance characteristics while maintaining improved impact resistance and fluidity.

In an embodiment, at least one of the first acrylate-based graft copolymer (A-<NUM>) and the second acrylate-based graft copolymer (A-<NUM>) may be a graft copolymer of <NUM> wt% to <NUM> wt% of a monomer mixture of an aromatic vinyl compound and a vinyl cyanide compound onto <NUM> wt% to <NUM> wt% of the acrylate-based rubbery polymer.

In an embodiment, each of the first acrylate-based graft copolymer (A-<NUM>) and the second acrylate-based graft copolymer (A-<NUM>) is prepared by graft polymerization of a monomer mixture including an aromatic vinyl compound and a vinyl cyanide compound onto the aforementioned acrylate-based rubbery polymer.

The polymerization method may be a conventional production method, for example, emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization. The first acrylate-based graft copolymer (A-<NUM>) and the second acrylate-based graft copolymer (A-<NUM>) may be formed using the same polymerization method, or may be formed using different polymerization methods.

The acrylate-based rubbery polymer may be an alkyl acrylate-based rubber, for example, C2 to C10 alkyl acrylate-containing rubber. The C2 to C10 alkyl acrylate may be, for example, butyl acrylate, ethyl hexyl acrylate, or a mixture thereof.

The acrylate-based rubbery polymer may be included in an amount of <NUM> wt% to <NUM> wt% based on <NUM> wt% of the first acrylate-based graft copolymer (A-<NUM>) or the second acrylate-based graft copolymer (A-<NUM>).

The monomer mixture of the aromatic vinyl compound and the vinyl cyanide compound grafted onto the acrylate-based rubbery polymer may be composed of <NUM> wt% to <NUM> wt% of the aromatic vinyl compound and <NUM> wt% to <NUM> wt% of the vinyl cyanide compound.

In addition, a component derived from the aromatic vinyl compound and a component derived from the vinyl cyanide compound may be included in an amount of <NUM> wt% to <NUM> wt% based on <NUM> wt% of the first acrylate-based graft copolymer (A-<NUM>) or the second acrylate-based graft copolymer (A-<NUM>).

The aromatic vinyl compound may include styrene, α-methylstyrene, p-methylstyrene, p-t-butylstyrene, <NUM>,<NUM>-dimethylstyrene, chlorostyrene, vinyltoluene, vinyl naphthalene, which may be used alone or in a mixture. Among these, styrene may be preferably used.

Examples of the vinyl cyanide compound may include acrylonitrile, methacrylonitrile, and fumaronitrile, which may be used alone or in a mixture. Among them, acrylonitrile may be preferably used.

At least one of the first acrylate-based graft copolymer (A-<NUM>) and the second acrylate-based graft copolymer (A-<NUM>) may be an acrylonitrile-styrene-acrylate graft copolymer (g-ASA). In an embodiment, each of the first acrylate-based graft copolymer (A-<NUM>) and the second acrylate-based graft copolymer (A-<NUM>) may be an acrylonitrile-styrene-acrylate graft copolymer (g-ASA).

The acrylonitrile-styrene-acrylate graft copolymer (g-ASA) may be prepared through a graft polymerization reaction onto an alkyl acrylate-based rubber by adding acrylonitrile and styrene to the alkyl acrylate-based rubber.

In an embodiment, the first acrylate-based graft copolymer (A-<NUM>) may be an acrylonitrile-styrene-acrylate graft copolymer (g-ASA) in which the acrylate-based rubbery polymer has an average particle diameter of greater than or equal to <NUM>, greater than or equal to <NUM>, less than or equal to <NUM>, less than or equal to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>.

In an embodiment, the first acrylate-based graft copolymer (A-<NUM>) may be included in an amount of greater than or equal to <NUM> wt%, greater than or equal to <NUM> wt%, less than or equal to <NUM> wt%, less than or equal to <NUM> wt%, less than or equal to <NUM> wt%, less than or equal to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt%, based on <NUM> wt% of the base resin.

When the amount of the first acrylate-based graft copolymer (A-<NUM>) in the base resin is less than <NUM> wt%, the impact resistance of the thermoplastic resin composition may be deteriorated, and when it exceeds <NUM> wt%, the fluidity and coloring properties of the thermoplastic resin composition may be deteriorated.

In an embodiment, the second acrylate-based graft copolymer (A-<NUM>) may be an acrylonitrile-styrene-acrylate graft copolymer (g-ASA) in which the acrylate-based rubbery polymer has an average particle diameter of greater than or equal to <NUM>, greater than or equal to <NUM>, greater than or equal to <NUM>, less than or equal to <NUM>, less than or equal to <NUM>, less than or equal to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>.

In an embodiment, the second acrylate-based graft copolymer (A-<NUM>) may be included in an amount of greater than or equal to <NUM> wt%, greater than or equal to <NUM> wt%, greater than or equal to <NUM> wt%, greater than or equal to <NUM> wt%, less than or equal to <NUM> wt%, less than or equal to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on <NUM> wt% of the base resin.

When the amount of the second acrylate-based graft copolymer (A-<NUM>) in the base resin is less than <NUM> wt%, coloring properties of the thermoplastic resin composition may be deteriorated, and when it exceeds <NUM> wt%, fluidity of the thermoplastic resin composition may be deteriorated.

In an embodiment, the aromatic vinyl compound-vinyl cyanide compound copolymer (B) may be a copolymer of an aromatic vinyl compound and a vinyl cyanide compound. The aromatic vinyl compound-vinyl cyanide compound copolymer may have a weight average molecular weight of greater than or equal to <NUM>,<NUM>/mol, greater than or equal to <NUM>,<NUM>/mol, greater than or equal to <NUM>,<NUM>/mol, less than or equal to <NUM>,<NUM>/mol, greater than or equal to <NUM>,<NUM>/mol, <NUM>,<NUM>/mol to <NUM>,<NUM>/mol, or <NUM>,<NUM>/mol to <NUM>,<NUM>/mol.

In the present invention, the weight average molecular weight is measured using a gel permeation chromatography (GPC; Agilent Technologies <NUM> series) after dissolving a particulate sample in tetrahydrofuran (THF) (column is Shodex LF-<NUM> and the standard sample made of Shodex polystyrene is used). The aromatic vinyl compound may include styrene unsubstituted or substituted with halogen or a C1 to C10 alkyl group (but not including α-methylstyrene), or a combination thereof. Specific examples of the aromatic vinyl compound may include any one or more selected from styrene, C1 to C10 alkyl-substituted styrene (but not including α-methylstyrene), halogen-substituted styrene, vinyltoluene, vinylnaphthalene, and a mixture thereof. Specific examples of the alkyl-substituted styrene may include p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, p-t-butylstyrene, and <NUM>,<NUM>-dimethylstyrene.

The vinyl cyanide compound may include acrylonitrile, methacrylonitrile, fumaronitrile, or a mixture thereof.

In one embodiment, the aromatic vinyl compound-vinyl cyanide compound copolymer (B) may be a styrene-acrylonitrile copolymer (SAN) having a weight average molecular weight of <NUM>,<NUM>/mol to <NUM>,<NUM>/mol.

In an embodiment, the aromatic vinyl compound-vinyl cyanide compound copolymer (B) may be included in an amount of greater than or equal to <NUM> wt%, greater than or equal to <NUM> wt%, less than or equal to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on <NUM> wt% of the base resin.

When the amount of the aromatic vinyl compound-vinyl cyanide compound copolymer (B) is less than <NUM> wt%, coloring properties and heat resistance of the thermoplastic resin composition may be deteriorated, and when it exceeds <NUM> wt%, the impact resistance of the thermoplastic resin composition may be deteriorated.

In an embodiment, the α-methyl styrene-based copolymer (C) functions to improve heat resistance and impact resistance of the thermoplastic resin composition.

In an embodiment, the α-methyl styrene-based copolymer may be a copolymer of a monomer mixture including <NUM> wt% to <NUM> wt% of α-methylstyrene. In an embodiment, the α-methylstyrene-based copolymer (C) may be a copolymer of a monomer mixture including <NUM> wt% to <NUM> wt% of α-methylstyrene, <NUM> wt% to <NUM> wt% of a vinyl cyanide compound, and <NUM> wt% to <NUM> wt% of an aromatic vinyl compound.

In an embodiment, the α-methylstyrene-based copolymer (C) may be a copolymer of a monomer mixture of <NUM> wt% to <NUM> wt% of α-methylstyrene, <NUM> wt% to <NUM> wt% of acrylonitrile, and <NUM> wt% to <NUM> wt% of styrene.

In one embodiment, the α-methylstyrene-based copolymer (C) may be prepared using a conventional manufacturing method, for example, emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization.

In an embodiment, the α-methylstyrene-based copolymer (C) may be included in an amount of greater than or equal to <NUM> wt%, greater than or equal to <NUM> wt%, less than or equal to <NUM> wt%, less than or equal to <NUM> wt%, <NUM> wt% to <NUM> wt%, or <NUM> wt% to <NUM> wt% based on <NUM> wt% of the base resin.

When the amount of the α-methylstyrene-based copolymer (C) is less than <NUM> wt%, the heat resistance of the thermoplastic resin composition may be lowered, and when it exceeds <NUM> wt%, the impact resistance and appearance characteristics of the thermoplastic resin composition may be lowered.

In an embodiment, the ultrahigh molecular weight styrene-acrylonitrile copolymer (D) functions to improve appearance characteristics of the thermoplastic resin composition.

The ultrahigh molecular weight styrene-acrylonitrile copolymer (D) according to an embodiment refers to a styrene-acrylonitrile copolymer having a weight average molecular weight of greater than or equal to at least <NUM>,<NUM>,<NUM>/mol, <NUM>,<NUM>,<NUM>/mol to <NUM>,<NUM>,<NUM>/mol, <NUM>,<NUM>,<NUM>/mol to <NUM>,<NUM>,<NUM>/mol, <NUM>,<NUM>,<NUM>/mol to <NUM>,<NUM>,<NUM>/mol, or <NUM>,<NUM>,<NUM>/mol to <NUM>,<NUM>,<NUM>/mol.

Therefore, the ultrahigh molecular weight styrene-acrylonitrile copolymer according to an embodiment may be, for example, included in an amount of <NUM> to <NUM> parts by weight, <NUM> to <NUM> parts by weight, or <NUM> to <NUM> parts by weight, based on <NUM> parts by weight of the base resin.

If the ultrahigh molecular weight styrene-acrylonitrile copolymer (D) is not included or is included in too small amount, appearance characteristics of the thermoplastic resin composition may not be improved, and if the amount is too high at a level exceeding <NUM> parts by weight, moldability and processability of the thermoplastic resin composition may be deteriorated.

The thermoplastic resin composition according to the embodiment may further include at least one additive selected from an ultraviolet (UV) stabilizer, a fluorescent whitening agent, a releasing agent, a nucleating agent, an inorganic material, a lubricant, an antistatic agent, a heat stabilizer, an impact-reinforcing agent, a pigment, and a dye, as necessary, within a range not departing from the object of the present invention.

Meanwhile, the thermoplastic resin composition according to an embodiment may be mixed with other resins or other rubber components and used together.

Hereinafter, preferred embodiments of the present invention are described.

<NUM> parts by weight of metal stearate, <NUM> parts by weight of silicone oil, <NUM> parts by weight of a hindered amine-based ultraviolet (UV) stabilizer, and <NUM> parts by weight of carbon black were commonly added as other additives to the components shown in Table <NUM> and then, mixed in a conventional mixer and extruded with a twin-screw extruder having L/D = <NUM> and Φ = <NUM> at <NUM> to manufacture pellets.

The pellets were dried in a dehumidifying drier set at <NUM> for <NUM> hours and injection-molded by using a <NUM> oz injection molding machine at a cylinder temperature of <NUM> and a molding temperature of <NUM> to manufacture specimens for measuring properties and appearance, and the measured properties are shown in Table <NUM>.

The specimens according to Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> were measured with respect to impact resistance, fluidity, coloring properties, and appearance characteristics in the following method, and the results are shown in Table <NUM>.

Izod impact strength of <NUM>-thick notched specimens was measured according to ASTM D256.

A melt flow index (MI) was measured at <NUM> under a <NUM> load according to ASTM D1238.

Lightness (L) of the specimens was measured by using a color difference meter CM-3700d, Konica Minolta, Inc. The lightness was evaluated by using the number of <NUM> to <NUM>, wherein as the number is closer to <NUM>, it denotes black, and as the number is closer to <NUM>, it denotes white. As the lightness was lower, the specimens looked stronger black and thus had excellent coloring properties about a pigment.

A mold having a pinpoint gate structure was used to injection-mold the specimens having a size of <NUM> x <NUM> x <NUM> according to Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM> at a high speed, and then, each specimen was examined with naked eyes to check whether or not flow marks were generated or not and then, evaluated into o (generated, clearly appear), △ (generated, rather blurry), and X (not generated).

On the other hand, appearance images of the specimens according to Example <NUM> and Comparative Example <NUM> are respectively shown in <FIG> and <FIG>.

Referring to Table <NUM>, the specimens formed of the thermoplastic resin compositions according to Examples <NUM> to <NUM> exhibited excellent impact resistance, fluidity, and coloring properties.

In addition, referring to Table <NUM> and <FIG>, the appearance of the specimen formed of the thermoplastic resin composition according to Example <NUM> did not have a flow mark at all (<FIG>), but the appearance of the specimen formed of the thermoplastic resin composition according to Comparative Example <NUM> had a flow mark (<FIG>).

Claim 1:
A thermoplastic resin composition, comprising
a base resin comprising
(A-<NUM>) <NUM> wt% to <NUM> wt% of a first acrylate-based graft copolymer having an acrylate-based rubbery polymer with an average particle diameter of <NUM> to <NUM>;
(A-<NUM>) <NUM> wt% to <NUM> wt% of a second acrylate-based graft copolymer having an acrylate-based rubbery polymer with an average particle diameter of <NUM> to <NUM>;
(B) <NUM> wt% to <NUM> wt% of an aromatic vinyl compound-vinyl cyanide compound copolymer;
(C) <NUM> wt% to <NUM> wt% of α-methylstyrene-based copolymer, and
(D) <NUM> to <NUM> parts by weight of an ultrahigh molecular weight styrene-acrylonitrile copolymer having a weight average molecular weight of greater than or equal to <NUM>,<NUM>,<NUM>/mol, based on <NUM> parts by weight of the base resin,
wherein the α-methylstyrene-based copolymer (C) is a copolymer of a monomer mixture including <NUM> wt% to <NUM> wt% of α-methylstyrene, <NUM> wt% to <NUM> wt% of a vinyl cyanide compound, and <NUM> wt% to <NUM> wt% of an aromatic vinyl compound, and the aromatic vinyl compound-vinyl cyanide compound copolymer (B) is a copolymer of a monomer mixture including <NUM> wt% to <NUM> wt% of an aromatic vinyl compound and <NUM> wt% to <NUM> wt% of a vinyl cyanide compound, and
wherein the average particle diameter is a Z-average particle diameter measured using a dynamic light scattering analyzer.