Polycarbonate resin composition with excellent light reflection and light shielding properties and automotive molded part manufactured using the same

Abstract

Polycarbonate resin composition, comprising: 60 to 70 wt.% of a polycarbonate resin; 4 to 10 wt% of a rubber-modified vinyl-based graft copolymer; 3 to 11 wt% of a styrene-based copolymer; 15 to 25 wt% titanium dioxide; and 2 to 3 wt.% of a mineral filler.

Description

Background area

[0001] Exemplary embodiments of the present disclosure relate to a polycarbonate resin composition having excellent light reflection and light shielding properties and an automotive molded part produced using the same. Discussion of the background

[0002] In-vehicle infotainment (IVI) devices, which control the function of obtaining information such as vehicle status and navigation, and entertainment functions such as music and video playback, are attracting attention. In recent years, with the increasing popularity of smartphones and tablets and the development of information technology (IT), a wider variety of infotainment services have been enabled by combining functions such as in-vehicle navigation, audio / video output, and internet access with personal IT devices. These IVI devices (products) include audio-video navigation (AVN), integrated center console (ICS), and the like.

[0003] In recent years, the production of IVI devices with a dead-front design has expanded, and in response to this expansion, a gray-colored material is required for the button housing of the IVI device. However, the use of this gray-colored material poses the problem of reduced light transmittance, thus reducing the luminosity of the button. Therefore, there is a need to improve the luminosity of the button housing material.

[0004] The technical background of the present disclosure is disclosed in Korean Patent Application Laid-Open No. KR 10-2008-0061310 A (published on July 2, 2008, entitled "Polycarbonate Resin Composition Having Excellent Yellowing Resistance and Flame Retardancy"). EP 2 115 064 B1 discloses thermoplastic compositions containing an aromatic polycarbonate. US Pat. No. 6,133,360 A discloses polycarbonate blends containing titanium dioxide. Short description

[0005] An object of the present disclosure is to provide a polycarbonate resin composition having excellent light reflection and light shielding properties.

[0006] Another object of the present disclosure is to provide a polycarbonate resin composition having excellent appearance, heat resistance, impact resistance and mechanical strength.

[0007] Yet another object of the present disclosure is to provide a polycarbonate resin composition having excellent processability, moldability and dimensional stability.

[0008] Yet another object of the present disclosure is to provide an automotive molded part produced using the polycarbonate resin composition.

[0009] One aspect of the present disclosure relates to a polycarbonate resin composition. In one embodiment, the polycarbonate resin composition comprises 60 to 70 wt.% of a polycarbonate resin, 4 to 10 wt.% of a rubber-modified vinyl-based graft copolymer, 3 to 11 wt.% of a styrene-based copolymer, 15 to 25 wt.% of titanium dioxide, and 2 to 3 wt.% of a mineral filler.

[0010] In one embodiment, the polycarbonate resin may have a melt index of 2 to 30 g / 10 min, measured according to ASTM D 1238 (at 300°C under 1.2 kiloponds), and a weight average molecular weight of 20,000 to 80,000 g / mol.

[0011] In one embodiment, the rubber-modified vinyl-based graft copolymer may have a structure comprising a rubbery polymer core and a shell formed by graft polymerization of an aromatic vinyl-based monomer and a vinyl cyanide-based monomer on the core.

[0012] In one embodiment, the styrene-based copolymer may comprise a copolymer of a styrene-based monomer and a vinyl cyanide-based monomer.

[0013] In one embodiment, the rubber-modified vinyl-based graft copolymer and the styrene-based copolymer may be present in a weight ratio of 1:1 to 1:2.

[0014] In one embodiment, the sum of the rubber-modified vinyl-based graft copolymer and the styrene-based copolymer and the titanium dioxide may be present in a weight ratio of 1:1 to 1:3.

[0015] In one embodiment, the titanium oxide may have an average size of 0.1 to 0.3 µm and a rutile phase.

[0016] In one embodiment, the titanium oxide may be surface treated.

[0017] In one embodiment, the mineral filler may comprise one or more of talc, mica, and wollastonite.

[0018] In one embodiment, the talc may have an average size of 3 to 10 µm, and the wollastonite may have an average size of 5 to 30 µm.

[0019] In one embodiment, the polycarbonate resin composition may further comprise an additive in an amount of 0.01 to 5 wt% based on the total weight of the composition, and the additive may comprise one or more of a heat stabilizer, a lubricant, and a light stabilizer.

[0020] In one embodiment, the polycarbonate resin composition may have a light reflectance of 95% or more at a wavelength of 400 to 700 nm and a light transmittance of 0% at a wavelength of 400 to 700 nm.

[0021] In one embodiment, the polycarbonate resin composition may have a melt index measured according to ISO 1133 (at 260°C under 5 kg) of 10 to 16 g / 10 min, a notched impact strength measured according to ISO 179 of 34 kJ / m 2 or more at room temperature (23°C) and a heat deflection temperature (HDT) of 105°C or higher as measured according to ISO 75.

[0022] Another aspect of the present disclosure relates to an automotive molded part produced using the polycarbonate resin composition. In one embodiment, the automotive molded part may be a button housing, a button holder, an interior trim, or a multi-terminal housing.

[0023] The polycarbonate resin composition according to the present disclosure and the automotive molded part produced using the same can completely shield light due to their excellent light reflection and light shielding properties, and can have excellent appearance, heat resistance, impact resistance and mechanical strength, and can also have excellent processability, moldability and dimensional stability. Detailed description of the illustrated embodiments

[0024] In the following description, the detailed description of related known technology or configuration is omitted if doing so might unnecessarily obscure the subject matter of the present disclosure.

[0025] Furthermore, the terms used in the following description are terms defined in consideration of the functions obtained according to embodiments of the present disclosure, and may be optionally changed by a user or operator or according to custom. Accordingly, the definition of the terms throughout the description should be based on the contents. Polycarbonate resin composition

[0026] One aspect of the present disclosure relates to a polycarbonate resin composition. In one embodiment, the polycarbonate resin composition comprises a polycarbonate resin, a rubber-modified vinyl-based graft copolymer, a styrene-based copolymer, titanium dioxide, and a mineral filler.

[0027] The components of the composition are described in detail below. (A) Polycarbonate resin

[0028] The polycarbonate resin can be prepared by copolymerizing a bisphenol-based monomer and a carbonate precursor.

[0029] For example, the bisphenol-based monomer may be one or more selected from the group consisting of bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)ketone, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A; BPA), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z; BPZ), 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane and α,ω-bis[3-(o-hydroxyphenyl)propyl]polydimethylsiloxane.

[0030] For example, the carbonate precursor may be one or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis(diphenyl) carbonate, carbonyl chloride (phosgene), triphosgene, diphosgene, carbonyl bromide, and bishaloformate.

[0031] In one embodiment, the polycarbonate resin may have a melt index of 2 to 30 g / 10 min, measured according to ASTM D 1238 (at 300°C under 1.2 kiloponds). Under this condition, the composition may exhibit excellent processability and compatibility. For example, the melt index may be 5 to 25 g / 10 min. For example, the melt index may be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 g / 10 min.

[0032] In one embodiment, the polycarbonate resin may have a weight-average molecular weight of 20,000 to 80,000 g / mol. Under this condition, the composition may exhibit excellent mechanical properties, such as miscibility and impact resistance.

[0033] In one embodiment, the polycarbonate resin is contained in an amount of 60 to 70 wt% based on the total weight of the polycarbonate resin composition. If the polycarbonate resin is contained in an amount of less than 60 wt%, the appearance, impact resistance, and heat resistance of the composition may be impaired, and if the polycarbonate resin is contained in an amount of more than 70 wt%, the light-reflecting or light-shielding property of the composition may be impaired. For example, the polycarbonate resin may be contained in an amount of 63 to 67 wt%. For example, the polycarbonate resin may be contained in an amount of 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70 wt% based on the total weight of the polycarbonate resin composition. (B) Rubber-modified vinyl-based graft copolymer

[0034] The rubber-modified vinyl-based graft copolymer may have a structure in which an aromatic vinyl-based monomer and a monomer copolymerizable with the aromatic vinyl-based monomer are graft-polymerized onto a rubbery polymer.

[0035] For example, the rubber-modified vinyl-based graft copolymer can be obtained by adding an aromatic vinyl-based monomer, a monomer copolymerizable with the aromatic vinyl-based monomer, etc., to a rubber-like polymer, and then polymerizing these monomers. For example, if necessary, the rubber-modified vinyl-based graft copolymer may further comprise a monomer to impart processability and heat resistance. The polymerization can be carried out by a well-known polymerization method such as emulsion polymerization, suspension polymerization, bulk polymerization, or the like.

[0036] In one embodiment, examples of the rubbery polymer include a diene-based rubber such as polybutadiene, poly(styrene-butadiene), and poly(acrylonitrile-butadiene); saturated rubber obtained by adding hydrogen to the diene-based rubber; acrylic rubber such as isoprene rubber and polybutyl acrylate; and an ethylene-propylene-diene monomer terpolymer (EPDM). These polymers can be used alone or as a mixture of two or more thereof. For example, a diene-based rubber can be used, and in particular, polybutadiene rubber can be used. The content of the rubbery polymer can be 5 to 65% by weight, for example, 10 to 60% by weight, based on 100% by weight of the rubber-modified vinyl-based graft copolymer.Within this content range, the polycarbonate resin composition comprising the rubber-modified vinyl-based graft copolymer can exhibit excellent mechanical properties such as impact resistance, heat resistance, flowability, and the like.

[0037] In one embodiment, the average particle size (Z-average) of the rubbery polymer (rubber particles) may be 0.05 to 6 µm, for example, 0.15 to 4 µm. Within this range, the polycarbonate resin composition can exhibit excellent mechanical properties such as impact resistance, heat resistance, flowability, and the like.

[0038] In one embodiment, the rubbery polymer can be obtained by swelling and polymerizing an aromatic vinyl-based monomer and a vinyl cyanide-based monomer in the rubbery polymer. For example, the rubbery polymer used in the present disclosure can be prepared by adding a mixture of an aromatic vinyl-based monomer, a vinyl cyanide-based monomer, and a polymerization initiator to the rubbery polymer, adding an emulsifier, a molecular weight regulator, and water, stirring the mixture so that the aromatic vinyl-based monomer and the vinyl cyanide-based monomer swell into the rubbery polymer, and then polymerizing these monomers. The method for preparing this rubbery polymer is known in the art and can be easily carried out by those skilled in the art.

[0039] In one embodiment, the aromatic vinyl-based monomer is a monomer that can be graft-copolymerized onto the rubbery copolymer, and examples thereof include styrene, α-methylstyrene, β-methylstyrene, p-methylstyrene, pt-butylstyrene, ethylstyrene, vinylxylene, monochlorostyrene, dichlorostyrene, dibromostyrene, vinylnaphthalene, and the like. These monomers can be used alone or as a mixture of two or more. The content of the aromatic vinyl-based monomer can be 15 to 95 wt%, for example, 20 to 80 wt%, based on 100 wt% of the rubber-modified vinyl-based graft copolymer. Within this content range, the polycarbonate resin composition can exhibit excellent mechanical properties such as impact resistance, heat resistance, flowability, and the like.

[0040] In one embodiment, examples of the monomer copolymerizable with the aromatic vinyl-based monomer include vinyl cyanide-based monomers such as acrylonitrile, methacrylonitrile, ethacrylonitrile, phenylacrylonitrile, α-chloroacrylonitrile, and fumaronitrile. These monomers can be used alone or as a mixture of two or more. Specifically, acrylonitrile and methacrylonitrile can be used. The content of the monomer copolymerizable with the aromatic vinyl-based monomer can be 1 to 50 wt%, for example, 5 to 45 wt%, based on 100 wt% of the rubber-modified vinyl-based graft copolymer. Within this content range, the polycarbonate resin composition can exhibit excellent mechanical properties such as impact resistance, heat resistance, flowability, and the like.

[0041] In one embodiment, examples of the monomer for imparting processability and heat resistance include, but are not limited to, acrylic acid, methacrylic acid, alkyl acrylate, alkyl methacrylate, maleic anhydride, maleimide-based compounds (N-substituted maleimide), and mixtures thereof. The content of the monomer for imparting processability and heat resistance may be 15 wt% or less, for example, 10 wt% or less, based on 100 wt% of the rubber-modified vinyl-based graft copolymer. Within this content range, the monomer can improve the processability and heat resistance of the rubber-modified vinyl-based graft copolymer without affecting other physical properties.

[0042] In one embodiment, the rubber-modified vinyl-based graft copolymer may have a structure comprising a rubbery polymer core and a shell formed by graft polymerization of an aromatic vinyl-based monomer and a vinyl cyanide-based monomer on the core.

[0043] In one embodiment, the rubber-modified vinyl-based graft copolymer may comprise a copolymer (g-ABS) comprising a rubbery polybutadiene polymer core and a shell formed by graft polymerization of the aromatic vinyl-based monomer styrene and the vinyl cyanide-based monomer acrylonitrile on the core.

[0044] In one embodiment, the rubber-modified vinyl-based graft copolymer is contained in an amount of 4 to 10 wt.% based on the total weight of the polycarbonate resin composition. When the rubber-modified vinyl-based graft copolymer is contained in an amount of less than 4 wt.%, the impact resistance and the light-reflecting and light-shielding properties of the resin composition according to the present disclosure may be reduced, and when the rubber-modified vinyl-based graft copolymer is contained in an amount of more than 10 wt.%, the melt index of the resin composition may be reduced, and thus its miscibility, moldability, or mechanical properties may be deteriorated. For example, the rubber-modified vinyl-based graft copolymer may be contained in an amount of 5 to 8 wt.%. For example, the rubber-modified vinyl-based graft copolymer may be contained in an amount of 4, 5, 6, 7, 8, 9, or 10 wt.-%, based on the total weight of the polycarbonate resin composition. (C) Styrene-based copolymer

[0045] The styrene-based copolymer may comprise a copolymer of a styrene-based monomer and a vinyl cyanide-based monomer.

[0046] In one embodiment, the styrene-based monomer used in the present disclosure may be selected from the group consisting of styrene; divinylbenzene; vinyltoluene; alkyl-substituted styrenes such as α-methylstyrene, pt-butylstyrene, and 2,4-dimethylstyrene; halogen-substituted styrenes; and combinations thereof, wherein "alkyl" means C1 to C8 alkyl.

[0047] In one embodiment, the vinyl cyanide-based monomer may be, but is not limited to, acrylonitrile, methacrylonitrile, fumaronitrile, or a combination of two or more thereof.

[0048] In one embodiment, the copolymer of the styrene-based monomer and the vinyl cyanide-based monomer can be prepared by emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, or the like.

[0049] In one embodiment, the copolymer of the styrene-based monomer and the vinyl cyanide-based monomer may comprise 10 wt.% to 40 wt.% of the vinyl cyanide-based monomer and 60 wt.% to 90 wt.% of the styrene-based monomer, based on 100 wt.% of the copolymer.

[0050] When the content of the vinyl cyanide-based monomer and the styrene-based monomer each falls within the above-described range, the polycarbonate resin composition comprising the copolymer of these monomers can exhibit excellent physical properties such as impact resistance, flowability, heat resistance and hardness.

[0051] In one embodiment, the weight-average molecular weight of the styrene-based copolymer may be 40,000 g / mol to 500,000 g / mol. Within this range, the polycarbonate resin composition of the present disclosure may exhibit excellent mechanical properties.

[0052] In one embodiment, the styrene-based copolymer is present in an amount of 3 to 11 wt.% based on the total weight of the polycarbonate resin composition. If the styrene-based copolymer is present in an amount of less than 3 wt.%, the melt index of the resin composition may be reduced, and thus its moldability may be impaired. If the styrene-based copolymer is present in an amount of more than 11 wt.%, the miscibility of the resin composition may be impaired, or its mechanical properties, such as impact resistance, may be impaired. For example, the styrene-based copolymer may be present in an amount of 6 to 9 wt.%. In one embodiment, the styrene-based copolymer may be present in an amount of 3, 4, 5, 6, 7, 8, 9, 10, or 11 wt.% based on the total weight of the polycarbonate resin composition.

[0053] In one embodiment, the rubber-modified vinyl-based graft copolymer and the styrene-based copolymer may be contained in a weight ratio of 1:1 to 1:2. Under this weight ratio condition, the miscibility, compatibility, and mechanical properties of the resin composition can all be excellent. For example, the rubber-modified vinyl-based graft copolymer and the styrene-based copolymer may be contained in a weight ratio of 1.1 to 1.5. (D) Titanium dioxide

[0054] The titanium dioxide is included to impart light reflecting and light shielding properties to the resin composition.

[0055] The titanium dioxide used in the present disclosure may be, but is not limited to, spherical, elliptical, platelet-like, or amorphous titanium dioxide. In one embodiment, the titanium dioxide (TiO2) may have an average size of 0.1 to 0.3 µm. The term "size" may refer to the diameter or maximum length of the titanium dioxide. Within this range of average sizes, the miscibility and dispersibility of the resin composition may be excellent.

[0056] In one embodiment, the titanium dioxide may have a rutile phase. In this case, the titanium dioxide may exhibit excellent thermal stability and weather resistance.

[0057] In one embodiment, the titanium dioxide may be surface-treated. For example, the surface of the titanium dioxide may be coated and treated with a surface-treating agent. The surface-treating agent may comprise one or more of an inorganic surface-treating agent and an organic surface-treating agent.

[0058] In one embodiment, the inorganic surface treatment agent may comprise one or more of alumina (Al2O3), silicon dioxide (SiO2), zirconium oxide (ZrO2), sodium silicate, sodium aluminate, sodium aluminum silicate, zinc oxide, and mica.

[0059] In one embodiment, the organic surface treatment agent may comprise one or more of polydimethylsiloxane, trimethylpropane, and pentaerythritol. For example, the surface treatment may be performed by coating 100 parts by weight of the titanium dioxide with 0.01 to 10 parts by weight of the surface treatment agent.

[0060] In one embodiment, the titanium dioxide is contained in an amount of 15 to 25 wt.% based on the total weight of the polycarbonate resin composition. If the titanium dioxide is contained in an amount of less than 15 wt.%, the light-reflecting and light-shielding properties of the resin composition may be impaired, and if the titanium dioxide is contained in an amount of more than 25 wt.%, the mechanical properties of the resin composition of the present disclosure, such as impact resistance, may be impaired. For example, the titanium dioxide may be contained in an amount of 18 to 22 wt.%. For example, the titanium dioxide may be contained in an amount of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 wt.% based on the total weight of the polycarbonate resin composition.

[0061] In one embodiment, the sum of the rubber-modified vinyl-based graft copolymer and the styrene-based copolymer and the titanium dioxide may be contained in a weight ratio of 1:1 to 1:3. Under this weight ratio condition, the resin composition can exhibit excellent light reflection and light-shielding properties and mechanical properties such as impact resistance, while exhibiting excellent miscibility. For example, they may be contained in a weight ratio of 1:1 to 1:1.6. For example, the sum of the rubber-modified vinyl-based graft copolymer and the styrene-based copolymer and the titanium dioxide may be contained in a weight ratio of 1:1 to 1:1.5. (E) Mineral filler

[0062] The mineral filler is included to ensure complete light-shielding properties without significantly reducing impact strength. In one embodiment, the mineral filler may comprise one or more of talc, mica, and wollastonite.

[0063] The mineral filler used in the present disclosure may be, but is not limited to, a spherical, elliptical, platelet-like, or amorphous mineral filler.

[0064] In one embodiment, the talc may have an average size of 3 to 10 µm, and the wollastonite may have an average size of 5 to 30 µm. The term "size" may refer to the diameter or maximum length of the talc or wollastonite. Under this condition, the resin composition of the present disclosure may exhibit excellent miscibility, dispersibility, and heat resistance.

[0065] In one embodiment, the mineral filler is contained in an amount of 2 to 3 wt% based on the total weight of the polycarbonate resin composition. If the mineral filler is contained in an amount of less than 2 wt%, it may be difficult to ensure complete light-shielding properties, and if the mineral filler is contained in an amount of more than 3 wt%, the impact resistance of the resin composition may be reduced. The mineral filler may be contained in an amount of 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3 wt% based on the total weight of the polycarbonate resin composition. (F) Additive

[0066] In one embodiment, the polycarbonate resin composition may further contain an additive in an amount of 0.01 to 5 wt.% based on the total weight of the composition. The additive may include, but is not limited to, one or more of a thermal stabilizer, a lubricant, and a light stabilizer. For example, the additive may be contained in an amount of 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, or 5 wt.% based on the total weight of the polycarbonate resin composition.

[0067] In one embodiment, the polycarbonate resin composition may have a light reflectance of 95% or more at a wavelength of 400 to 700 nm. Furthermore, the polycarbonate resin composition may have a light transmittance of 0% (or a light shielding rate of 100%) at a wavelength of 400 to 700 nm. For example, the polycarbonate resin composition may have a light reflectance of 95 to 99.99% at a wavelength of 400 to 700 nm.

[0068] Light reflectance (%) and light transmittance (%) were measured using a measuring device (manufactured by Hunter Lab; model: ColorQUEST XE) in RSIN mode. Light reflectance and light transmittance can also be measured using the SCI measurement method.

[0069] In one embodiment, the polycarbonate resin composition may have a melt index measured according to ISO 1133 (at 260°C under 5 kg) of 10 to 16 g / 10 min, a notched impact strength measured according to ISO 179 of 34 kJ / m 2 or more at room temperature (23°C) and a heat deflection temperature (HDT) of 105°C or higher as measured according to ISO 75.

[0070] For example, the polycarbonate resin composition can have a notched impact strength of 34 to 40 kJ / m 2 at room temperature (23°C) and a heat deflection temperature (HDT) of 105 to 115 °C measured according to ISO 75. Automotive molded part made using the polycarbonate resin composition

[0071] Another aspect of the present disclosure relates to an automotive molded part produced using the polycarbonate resin composition.

[0072] In one embodiment, the automotive molded part can be used for in-vehicle infotainment (IVI) applications. For example, the automotive molded part can be a knob housing, a knob holder, an interior trim panel, or a multi-terminal housing for audio-video navigation (AVN) and integrated center console (ICS).

[0073] The polycarbonate resin composition according to the present disclosure and the molded article produced using the same can completely shield light due to their excellent light reflection and light shielding properties, and can have excellent appearance, excellent heat resistance, impact resistance and mechanical strength, and can also have excellent processability, moldability and dimensional stability.

[0074] Below, the configuration and effect of the present disclosure will be described in more detail with reference to preferred examples. However, these examples are presented as preferred examples of the present disclosure and should not be construed as limiting the present disclosure in any way. The contents not described here can be sufficiently and technically conceived by those skilled in the art, and therefore, their description is omitted here.

[0075] Unless otherwise stated, all standards referenced herein, such as ASTM, ISO, etc., are the current versions of the respective standard as of the day before the priority date.

[0076] Unless otherwise stated, all particle sizes were determined by measurement using a field emission scanning electron microscope (FE-SEM). Examples and comparison examples

[0077] The components used in the examples and comparative examples are as follows. (A) Polycarbonate resin: a polycarbonate resin (LG Chem Ltd., PC 1300-15) with a melt flow index of 15 g / 10 min (measured according to ASTM D1238 at 300°C under a load of 1.2 kilopond) was used. (B) Rubber-modified vinyl-based graft copolymer: an acrylonitrile-butadiene-styrene graft copolymer (LG Chem Ltd., DP270E) was used. (C) Styrene-based copolymer: a copolymer of a styrene-based monomer and a vinyl cyanide-based monomer (SAN, LG Chem Ltd., 80HF) was used. (D) Titanium dioxide: TiO2 of the rutile phase with an average diameter of 0.1 to 0.3 µm was used. (E) Inorganic filler: (E1) Talc with a mean diameter of 3 to 10 µm was used. (E2) Wollastonite with a mean diameter of 5 to 30 µm was used. (F) Additive: a thermal stabilizer, a lubricant or a light stabilizer was used. Examples 1 to 4 and Comparative Examples 1 to 9

[0078] According to the compositions shown in Table 1 below, blends were prepared by mixing components using a known method. Each of the blends was placed in a twin-screw extruder (L / D = 29, Φ = 45 mm), melted, kneaded, and then extruded to produce pellet-type polycarbonate resin compositions. The resulting pellets were dried at 80°C for 2 hours and then injection molded using an injection molding machine set at a cylinder temperature of 180 to 220°C and a mold temperature of 60°C, thereby preparing test specimens. Assessment of physical properties

[0079] The physical properties of the specimens of Examples 1 to 4 and Comparative Examples 1 to 9 were evaluated as follows, and the evaluation results are shown in Table 2 below. (1) The melt flow index (g / 10 min) was measured according to ISO 1133 (at 260°C under 5 kg). (2) Room temperature impact strength (kJ / m 2 ): The notched impact strength at room temperature (23 °C) was measured according to ISO 179. (3) Heat deflection temperature (HDT, °C) was measured according to ISO 75. (4) The light reflectance (%) and light transmittance (%) were measured using a measuring instrument (manufactured by HUNTER LAB, Model: ColorQUEST XE) in RSIN mode. The light reflectance and light transmittance were measured using the SCI measurement method.

[0080] From the results in Table 2 above, it was seen that Examples 1 to 4 according to the present disclosure had a light reflectance of 95% or more and a light transmittance of 0%, indicating that they can completely shield light. However, it was seen that Comparative Examples 1 to 9, which did not satisfy the conditions of the present disclosure, exhibited inferior miscibility and mechanical properties, or inferior light reflecting and light-shielding properties, than Examples 1 to 4.

[0081] Simple modifications or variations of the present disclosure may be readily made by those skilled in the art, and all such modifications or variations are to be considered as being within the scope of the present disclosure.

Claims

[1] A polycarbonate resin composition comprising: 60 to 70 wt.% of a polycarbonate resin; 4 to 10 wt.% of a rubber-modified vinyl-based graft copolymer; 3 to 11 wt.% of a styrene-based copolymer; 15 to 25 wt% titanium dioxide; and 2 to 3 wt.% of a mineral filler. [2] The polycarbonate resin composition according to claim 1, wherein the polycarbonate resin has a melt flow rate of 2 to 30 g / 10 min as measured according to ASTM D 1238 (at 300°C under 1.2 kilopond) and a weight average molecular weight of 20,000 to 80,000 g / mol. [3] The polycarbonate resin composition according to claim 1, wherein the rubber-modified vinyl-based graft copolymer has a structure comprising a rubber-like polymer core and a shell formed by graft polymerizing an aromatic vinyl-based monomer and a vinyl cyanide-based monomer on the core. [4] The polycarbonate resin composition according to claim 1, wherein the styrene-based copolymer comprises a copolymer of a styrene-based monomer and a vinyl cyanide-based monomer. [5] The polycarbonate resin composition according to claim 1, wherein the rubber-modified vinyl-based graft copolymer and the styrene-based copolymer are contained in a weight ratio of 1:1 to 1:

2. [6] The polycarbonate resin composition according to claim 1, wherein the sum of the rubber-modified vinyl-based graft copolymer and the styrene-based copolymer and the titanium dioxide are contained in a weight ratio of 1:1 to 1:

3. [7] The polycarbonate resin composition according to claim 1, wherein the titanium oxide has an average size of 0.1 to 0.3 µm and a rutile phase. [8] The polycarbonate resin composition according to claim 7, wherein the titanium oxide is surface-treated. [9] The polycarbonate resin composition according to claim 1, wherein the mineral filler comprises one or more of talc, mica and wollastonite. [10] The polycarbonate resin composition according to claim 9, wherein the talc has an average size of 3 to 10 µm and the wollastonite has an average size of 5 to 30 µm. [11] The polycarbonate resin composition according to claim 1, further comprising an additive in an amount of 0.01 to 5% by weight based on the total weight of the composition, wherein the additive comprises one or more of a heat stabilizer, a lubricant and a light stabilizer. [12] The polycarbonate resin composition according to claim 1, which has a light reflectance of 95% or more at a wavelength of 400 to 700 nm and a light transmittance of 0% at a wavelength of 400 to 700 nm. [13] Polycarbonate resin composition according to claim 1, which has a melt flow index of 10 to 16 g / 10 min measured according to ISO 1133 (at 260°C under 5 kg), a notched impact strength of 34 kJ / m 2 or more at room temperature (23 °C) and a heat deflection temperature (HDT) of 105 °C or more as measured according to ISO 75. [14] An automotive molded part produced using the polycarbonate resin composition according to any one of claims 1 to 13. [15] A molded automotive part according to claim 14, which is a button housing, a button holder, an interior trim or a multi-terminal housing.