Patent Description:
Conventionally, steel materials are generally used as interior and exterior material for transportation equipment, such as automobiles, trains, and the like. However, as the need for improvement in fuel efficiency has increased in recent years, studies on replacement of the steel materials with lightweight plastic materials have been actively carried out. Materials for transportation equipment are strictly required to have low flammability and flame retardancy, which can prevent or reduce generation of smoke in the event of a fire, low heat generation characteristics, smoke toxicity, and the like in order to ensure passenger safety.

With good properties in terms of formability, mechanical properties such as impact resistance and tensile strength, electric properties, transparency, and the like, a polycarbonate resin is broadly used in automobiles and electronic products. Conventionally, a polycarbonate resin composition prepared by blending an acrylonitrile-butadiene-styrene (ABS) resin with the polycarbonate resin and adding a phosphorus flame retardant to the mixture is generally used. Despite good properties in terms of formability, heat resistance, moisture proofing, impact resistance and flame retardancy, such a polycarbonate resin composition is not suitable for materials for transportation equipment due to generation of an excess of smoke upon combustion. Thus, a polyimide resin or a polyamide resin is generally used in the field of materials for transportation equipment. However, the polyimide resin or the polyamide resin has disadvantages, such as high price, poor formability, and poorer mechanical properties than polycarbonate resins.

Therefore, there is a need for a polycarbonate resin composition that has good properties in terms of flame retardancy, low heat generation characteristics, flame propagation characteristics, and low flammability, and does not have smoke toxicity, while maintaining good impact resistance, heat resistance and formability of the polycarbonate resin.

The background technique of the present invention is disclosed in <CIT>, <CIT> and <CIT>.

It is one aspect of the present invention to provide a polycarbonate resin composition as claimed in any one of claims <NUM> to <NUM> that has good properties in terms of flame retardancy, low heat generation characteristics, flame propagation characteristics, low flammability, and the like, and does not have smoke toxicity.

It is another aspect of the present invention to provide a molded product as claimed in claim <NUM> formed from the polycarbonate resin composition as claimed in any one of claims <NUM> to <NUM>.

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

One aspect of the present invention relates to a polycarbonate resin composition. The polycarbonate resin composition comprises: <NUM> parts by weight of a base resin comprising <NUM> wt% to <NUM> wt% of a polycarbonate resin and <NUM> wt% to <NUM> wt% of a polysiloxane-polycarbonate copolymer resin; <NUM> part by weight to <NUM> parts by weight of silicone gum; <NUM> part by weight to <NUM> parts by weight of an inorganic metal compound; <NUM> parts by weight to <NUM> parts by weight of a phosphorus flame retardant; <NUM> parts by weight to <NUM> parts by weight of and inorganic fillers, wherein the silicone gum and the inorganic metal compound are present in a weight ratio (silicone gum:inorganic metal compound) of <NUM>:<NUM> to <NUM>:<NUM>.

The polysiloxane-polycarbonate copolymer resin may be prepared through reaction of a siloxane compound represented by Formula <NUM>, an aromatic dihydroxy compound, and a carbonate precursor:.

<CHM>
where R<NUM> and R<NUM> are each independently a C<NUM> to C<NUM> alkyl group, a C<NUM> to C<NUM> aryl group, or a halogen atom or alkoxy group-containing C<NUM> to C<NUM> alkyl group or C<NUM> to C<NUM> aryl group; As are each independently a substituted or unsubstituted C<NUM> to C<NUM> hydrocarbon group, or a substituted or unsubstituted C<NUM> to C<NUM> hydrocarbon group having -O- or -S-; Ys are each independently a hydrogen atom, a halogen atom, a C<NUM> to C<NUM> halogenated alkyl group, a cyano group (-CN), or an ester group; and m is an integer of about <NUM> to about <NUM>,<NUM>.

The silicone gum may be a polysiloxane resin represented by Formula <NUM> and have a weight average molecular weight of about <NUM>,<NUM>/mol to about <NUM>,<NUM>,<NUM>/mol and a viscosity of about <NUM>,<NUM> to about <NUM>,<NUM><NUM>/s, as measured at <NUM> using a Brookfield viscometer:.

<CHM>
where R<NUM> is a methyl group, a vinyl group or a hydroxyl group, R<NUM> is a methyl group or a vinyl group, and a and b are a mole ratio of <NUM> to <NUM> and a mole ratio of <NUM> to <NUM>, respectively.

The inorganic metal compound may comprise at least one of zinc borate, zinc borate hydrate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zinc sulfide, zinc oxide, titanium oxide, magnesium calcium carbonate, magnesium carbonate, calcium carbonate, and magnesium sulfate hydrate.

The phosphorus flame retardant may comprise about <NUM> wt% to about <NUM> wt% of bisphenol-A bis(diphenyl phosphate) and about <NUM> wt% to about <NUM> wt% of biphenol bis(diphenyl phosphate).

The inorganic fillers may comprise flake inorganic fillers.

The polycarbonate resin composition may have a flame retardancy of V-<NUM> or higher, as measured on a <NUM> thick specimen in accordance with a UL-<NUM> vertical test method.

The polycarbonate resin composition may have a maximum average rate of heat emission (MARHE) of about <NUM> kW/m<NUM> to about <NUM> kW/m<NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with ISO <NUM>-<NUM>.

The polycarbonate resin composition may have a critical heat flux at extinguishment (CFE) of about <NUM> kW/m<NUM> to about <NUM> kW/m<NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

The polycarbonate resin composition may have a specific optical density at <NUM> (Ds(<NUM>)) of about <NUM> to about <NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

The polycarbonate resin composition may have a cumulative value of specific optical densities in the fires <NUM> of the test (VOF(<NUM>)) of about <NUM> to about <NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

The polycarbonate resin composition may have a conventional index of toxicity (CIT) of about <NUM> to about <NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

Another aspect of the present invention relates to a molded article formed of the polycarbonate resin composition according to any one of claims <NUM> to <NUM>.

The present invention provides a polycarbonate resin composition that has good properties in terms of flame retardancy, low heat generation characteristics, flame propagation characteristics, low flammability, and the like, and does not have smoke toxicity, and a molded article formed of the same.

A thermoplastic resin composition according to the present invention comprises: (A) a polycarbonate resin; (B) a polysiloxane-polycarbonate copolymer resin; (C) silicone gum; (D) an inorganic metal compound; (E) a phosphorus flame retardant; and (F) inorganic fillers.

The polycarbonate resin according to one embodiment of the present invention may comprise any typical polycarbonate resin used for thermoplastic resin compositions. For example, the polycarbonate resin may be an aromatic polycarbonate resin prepared by reacting diphenols (aromatic diol compounds) with a precursor, such as phosgene, halogen formate, carbonate diester, and the like.

In some embodiments, the diphenols may comprise, for example, <NUM>,<NUM>'-biphenol, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)-<NUM>-methylbutane, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)cyclohexane, <NUM>,<NUM>-bis(<NUM>-chloro-<NUM>-hydroxyphenyl)propane, <NUM>,<NUM>-bis(<NUM>,<NUM>-dichloro-<NUM>-hydroxyphenyl)propane, <NUM>,<NUM>-bis(<NUM>-methyl-<NUM>-hydroxyphenyl)propane, and <NUM>,<NUM>-bis(<NUM>,<NUM>-dimethyl-<NUM>-hydroxyphenyl)propane, without being limited thereto. For example, the diphenols may be <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)propane, <NUM>,<NUM>-bis(<NUM>,<NUM>-dichloro-<NUM>-hydroxyphenyl)propane, <NUM>,<NUM>-bis(<NUM>-methyl-<NUM>-hydroxyphenyl)propane, <NUM>,<NUM>-bis(<NUM>,<NUM>-dimethyl-<NUM>-hydroxyphenyl)propane, or <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)cyclohexane, specifically <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)propane, which is also referred to as bisphenol-A.

In some embodiments, the carbonate precursor may comprise dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, carbonyl chloride (phosgene), diphosgene, triphosgene, carbonyl bromide, and bishaloformate. These may be used alone or as a mixture thereof.

The polycarbonate resin may be a branched polycarbonate resin. For example, the polycarbonate resin may be prepared by adding about <NUM> mol% to about <NUM> mol% of a tri- or higher polyfunctional compound, specifically a tri- or higher valent phenol group-containing compound, based on the total number of moles of the diphenols used in polymerization.

The polycarbonate resin may be a homopolycarbonate resin, a copolycarbonate resin, or a blend thereof. In addition, the polycarbonate resin may be partly or completely replaced by an aromatic polyester-carbonate resin obtained by polymerization in the presence of an ester precursor, for example, a bifunctional carboxylic acid.

In some embodiments, the polycarbonate resin may have a weight average molecular weight (Mw) of about <NUM>,<NUM>/mol to about <NUM>,<NUM>/mol, for example, about <NUM>,<NUM>/mol to about <NUM>,<NUM>/mol, as measured by gel permeation chromatography (GPC). Within this range, the thermoplastic resin composition can have good properties in terms of impact resistance, stiffness, heat resistance, and the like.

In the present invention, the polycarbonate resin is present in an amount of about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, based on <NUM> wt% of a base resin (A+B) comprising (A) the polycarbonate resin and (B) the polysiloxane-polycarbonate copolymer resin. Within this range, the polycarbonate resin composition can exhibit good impact resistance, heat resistance, formability (flowability), and the like.

The polysiloxane-polycarbonate copolymer resin according to one embodiment of the invention serves to improve impact resistance, flame retardancy, and weather resistance of the polycarbonate resin composition, and may comprise a polycarbonate block and a polysiloxane block. For example, the polysiloxane-polycarbonate copolymer resin may be a triblock copolymer of polycarbonate/polysiloxane/polycarbonate blocks, without being limited thereto. For example, the polysiloxane-polycarbonate copolymer resin may be prepared by reacting a siloxane compound represented by Formula <NUM>, an aromatic dihydroxy compound, and a carbonate precursor.

<CHM>
where R<NUM> and R<NUM> are each independently a C<NUM> to C<NUM> alkyl group, a C<NUM> to C<NUM> aryl group, or a halogen atom or alkoxy group-containing C<NUM> to C<NUM> alkyl group or C<NUM> to C<NUM> aryl group; As are each independently a substituted or unsubstituted C<NUM> to C<NUM> hydrocarbon group, or a substituted or unsubstituted C<NUM> to C<NUM> hydrocarbon group having -O- or -S-; Ys are each independently a hydrogen atom, a halogen atom, a C<NUM> to C<NUM> halogenated alkyl group, a cyano group (-CN), or an ester group; and m is an integer of about <NUM> to about <NUM>,<NUM>, for example, about <NUM> to about <NUM>, specifically about <NUM> to about <NUM>.

In some embodiments, the aromatic dihydroxy compound (diphenols) may be an aromatic dihydroxy compound used in preparation of a typical polycarbonate resin, and may comprise, for example, <NUM>,<NUM>'-biphenol, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)-<NUM>-methylbutane, <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)cyclohexane, <NUM>,<NUM>-bis(<NUM>-chloro-<NUM>-hydroxyphenyl)propane, and <NUM>,<NUM>-bis(<NUM>,<NUM>-dichloro-<NUM>-hydroxyphenyl)propane, without being limited thereto. Specifically, the aromatic dihydroxy compound may be <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)propane, <NUM>,<NUM>-bis(<NUM>,<NUM>-dichloro-<NUM>-hydroxyphenyl)propane, or <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)cyclohexane, preferably <NUM>,<NUM>-bis(<NUM>-hydroxyphenyl)propane, which is also referred to as bisphenol A.

In some embodiments, the carbonate precursor may comprise phosgene, triphosgene, diaryl carbonate, and mixtures thereof. Examples of the diaryl carbonate may comprise diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis(diphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, and dicyclohexyl carbonate, without being limited thereto. These may be used alone or as a mixture thereof. For example, diphenyl carbonate may be used.

In some embodiments, the polycarbonate-polysiloxane copolymer may comprise about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, of the polycarbonate block derived from the aromatic dihydroxy compound, and about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, of the polysiloxane block derived from the siloxane compound. Within this range, the thermoplastic resin composition can exhibit good impact resistance, flame retardancy, weather resistance, and the like.

In some embodiments, the polycarbonate-polysiloxane copolymer may have a weight average molecular weight (Mw) of about <NUM>,<NUM>/mol to about <NUM>,<NUM>/mol, for example, about <NUM>,<NUM>/mol to about <NUM>,<NUM>/mol, as measured by gel permeation chromatography (GPC). In addition, the polycarbonate-polysiloxane copolymer may have a melt-flow index (MI) of about <NUM>/<NUM> to about <NUM>/<NUM>, for example, about <NUM>/<NUM> to about <NUM>/<NUM>, as measured under conditions of <NUM> and a load of <NUM> in accordance with ISO <NUM>. Within this range, the thermoplastic resin composition can have good mechanical properties, injection flowability, and balance therebetween.

In some embodiments, the polycarbonate-polysiloxane copolymer may be prepared by a typical method. For example, the aromatic dihydroxy compound, the carbonate precursor, and the siloxane compound may be prepared through interface copolymerization, emulsion polymerization, and the like. Alternatively, the polycarbonate-polysiloxane copolymer may be obtained from commercially available products.

In the present invention, the polysiloxane-polycarbonate copolymer resin is present in an amount of about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, based on <NUM> wt% of a base resin (A+B) comprising (A) the polycarbonate resin and (B) the polysiloxane-polycarbonate copolymer resin. Within this range, the polycarbonate resin composition can exhibit good properties in terms of impact resistance, flame retardancy, weather resistance, and the like.

The silicone gum according to one embodiment of the invention serves to improve flame retardancy, low heat generation characteristics, low flammability, flame propagation characteristics and the like of the polycarbonate resin composition together with the inorganic metal compound, and may be a polysiloxane resin represented by Formula <NUM>. <CHM>
where R<NUM> is a methyl group, a vinyl group or a hydroxyl group, R<NUM> is a methyl group or a vinyl group, and a and b are a mole ratio of <NUM> to <NUM> and a mole ratio of <NUM> to <NUM>, for example, a mole ratio of <NUM> to <NUM> and a mole ratio of <NUM> to <NUM>, respectively.

In some embodiments, the silicone gum may have a weight average molecular weight (Mw) of about <NUM>,<NUM>/mol to about <NUM>,<NUM>,<NUM>/mol, for example, about <NUM>,<NUM>/mol to about <NUM>,<NUM>/mol, as measured by gel permeation chromatography (GPC). Within this range, the polycarbonate resin composition can have good properties in terms of flame retardancy, low heat generation characteristics, low flammability, flame propagation characteristics, and the like.

In some embodiments, the silicone gum may have a viscosity of about <NUM>,<NUM><NUM>/s to about <NUM>,<NUM><NUM>/s (centistoke), for example, about <NUM>,<NUM><NUM>/s to about <NUM>,<NUM><NUM>/s, as measured at <NUM> using a Brookfield viscometer. Within this range, the polycarbonate resin composition can have good properties in terms of flame retardancy, low heat generation characteristics, low flammability, flame propagation characteristics, and the like.

In the present invention, the silicone gum is present in an amount of about <NUM> part by weight to about <NUM> parts by weight, for example, about <NUM> parts by weight to about <NUM> parts by weight, relative to about <NUM> parts by weight of the polycarbonate resin. Within this range, the polycarbonate resin composition can have good properties in terms of flame retardancy, low heat generation characteristics, low flammability, flame propagation characteristics, and the like.

The inorganic metal compound according to one embodiment of the invention serves to improve flame retardancy, low heat generation characteristics, flame propagation characteristics, and low flammability of the polycarbonate resin composition together with the silicone gum, and may comprise zinc borate, zinc borate hydrate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zinc sulfide, zinc oxide, titanium oxide, magnesium calcium carbonate, magnesium carbonate, calcium carbonate, magnesium sulfate hydrate, and combinations thereof. For example, the inorganic metal compound may comprise zinc borate, zinc borate hydrate, and combinations thereof.

In some embodiments, the inorganic metal compound may have various shapes and sizes. For example, the inorganic metal compound may have an average particle diameter (D50) of about <NUM> to about <NUM>, for example, about <NUM> to about <NUM>, as measured by a laser diffraction particle size measurement method.

In the present invention, the inorganic metal compound is present in an amount of about <NUM> part by weight to about <NUM> parts by weight, for example, about <NUM> parts by weight to about <NUM> parts by weight, relative to about <NUM> parts by weight of the polycarbonate resin. Within this range, the polycarbonate resin composition can exhibit good properties in terms of flame retardancy, low heat generation characteristics, low flammability, flame propagation characteristics, and the like.

In the present invention, (C) the silicone gum and (D) the inorganic metal compound is present in a weight ratio (C:D) of about <NUM>:<NUM> to about <NUM>:<NUM>. Within this range, the polycarbonate resin composition can exhibit good properties in terms of flame retardancy, low heat generation characteristics, low flammability, flame propagation characteristics, and the like.

The phosphorus flame retardant according to one embodiment of the invention may comprise any typical phosphorus flame retardant used in typical flame retardant thermoplastic resin compositions. For example, the phosphorus flame retardant may comprise a phosphate compound, a phosphonate compound, a phosphinate compound, a phosphine oxide compound, a phosphazene compound, and a metal salt thereof. These compounds may be used alone or as a mixture thereto. Specifically, the phosphorus flame retardant may comprise an aromatic phosphoric ester compound represented by Formula <NUM>. <CHM>
where R<NUM>, R<NUM>, R<NUM> and R<NUM> are each independently a hydrogen atom, a C<NUM> to C<NUM> aryl group, or a C<NUM> to C<NUM> alkyl group-substituted C<NUM> to C<NUM> aryl group; R<NUM> is a C<NUM> to C<NUM> arylene group or a C<NUM> to C<NUM> alkyl group-substituted C<NUM> to C<NUM> arylene group, for example, derivatives of a dialcohol, such as resorcinol, hydroquinone, bisphenol-A, or bisphenol-S; and n is an integer of <NUM> to <NUM>.

In some embodiments, when n is <NUM> in Formula <NUM>, examples of the aromatic phosphoric ester compound may comprise diaryl phosphates, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tri(<NUM>,<NUM>-dimethylphenyl)phosphate, tri(<NUM>,<NUM>,<NUM>-trimethylphenyl)phosphate, tri(<NUM>,<NUM>-di-tert-butylphenyl)phosphate, and tri(<NUM>,<NUM>-dimethylphenyl)phosphate; and when n is <NUM> in Formula <NUM>, examples of the aromatic phosphoric ester compound may comprise bisphenol-A bis(diphenyl phosphate), bisphenol bis(diphenyl phosphate), resorcinol bis(diphenyl phosphate), resorcinol bis[bis(<NUM>,<NUM>-dimethylphenyl)phosphate], resorcinol bis[bis(<NUM>,<NUM>-di-tert-butylphenyl)phosphate], hydroquinone bis[bis(<NUM>,<NUM>-dimethylphenyl)phosphate], and hydroquinone bis[bis(<NUM>,<NUM>-di-tert-butylphenyl)phosphate], without being limited thereto. These the aromatic phosphoric ester compounds may be used alone or as a mixture thereof.

In some embodiments, the phosphorus flame retardant may comprise about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, of bisphenol-A bis(diphenyl phosphate) and about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, of biphenol bis(diphenyl phosphate). Within this range, the phosphorus flame retardant can improve flame retardancy without deterioration in other properties of the polycarbonate resin composition.

In the present invention, the phosphorus flame retardant is present in an amount of about <NUM> parts by weight to about <NUM> parts by weight, for example, about <NUM> parts by weight to about <NUM> parts by weight, relative to about <NUM> parts by weight of the polycarbonate resin. Within this range, the polycarbonate resin composition can have good flame retardancy, low heat generation characteristics, and the like.

The inorganic fillers according to one embodiment of the invention serve to improve flame retardancy, low heat generation and low flammability characteristics while improving stiffness of the polycarbonate resin composition by preventing combustible resin decomposition products from exuding from a resin surface upon combustion of the polycarbonate resin composition, and may comprise typical flake inorganic fillers.

In some embodiments, the flake inorganic fillers may comprise talc, mica, and a combination thereof. For example, typical flake talc may be used. The flake inorganic fillers may have an average particle diameter of about <NUM> to about <NUM>, for example, about <NUM> to about <NUM>. Within this range, the polycarbonate resin composition can exhibit good properties in terms of flame retardancy, stiffness, flowability, external appearance, and the like.

In some embodiments, the inorganic fillers may further comprise typical acicular inorganic fillers, for example, wollastonite, whisker, glass fibers, basalt fibers, and combinations thereof, in addition to the flake inorganic fillers. For example, wollastonite may be used.

In some embodiments, the acicular inorganic fillers may be present in an amount of about <NUM> parts by weight to about <NUM> parts by weight, for example, about <NUM> parts by weight to about <NUM> parts by weight, relative to about <NUM> parts by weight of the flake inorganic fillers. Within this range, the polycarbonate resin composition can have good dimensional stability.

In the present invention, the inorganic fillers are present in an amount of about <NUM> parts by weight to about <NUM> parts by weight, for example, about <NUM> parts by weight to about <NUM> parts by weight, relative to about <NUM> parts by weight of the polycarbonate resin. Within this range, the polycarbonate resin composition can have good properties in terms of flame retardancy, stiffness, dimensional stability, and the like.

In some embodiments, the polycarbonate resin composition may further comprise typical additives, as needed. Examples of the additives may comprise an anti-dripping agent, an antioxidant, a release agent, a lubricant, a nucleating agent, an antistatic agent, a UV stabilizer, pigments, dyes, and a mixture thereof. The additives may be present in an amount of about <NUM> parts by weight to about <NUM> parts by weight relative to about <NUM> parts by weight of the base resin.

The polycarbonate resin composition according to one embodiment of the invention may be prepared by a typical method for preparing a polycarbonate resin composition, known in the art. For example, the aforementioned components and, optionally, other additives are mixed, followed by melt extrusion using a typical twin-screw extruder at about <NUM> to about <NUM>, for example, about <NUM> to about <NUM>, thereby preparing a polycarbonate resin composition in pellet form.

In some embodiments, the polycarbonate resin composition may have a flame retardancy of V-<NUM> or higher, as measured on a <NUM> thick specimen in accordance with the UL-<NUM> vertical test method.

In some embodiments, the polycarbonate resin composition may have a maximum average rate of heat emission (MARHE) of about <NUM> kW/m<NUM> to about <NUM> kW/m<NUM>, for example, about <NUM> kW/m<NUM> to about <NUM> kW/m<NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

In some embodiments, the polycarbonate resin composition may have a critical heat flux at extinguishment (CFE) of about <NUM> kW/m<NUM> to about <NUM> kW/m<NUM>, for example, about <NUM> kW/m<NUM> to about <NUM> kW/m<NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

In some embodiments, the polycarbonate resin composition may have a specific optical density at <NUM> (Ds(<NUM>)) of about <NUM> to about <NUM>, for example, about <NUM> to about <NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

In some embodiments, the polycarbonate resin composition may have a cumulative value of specific optical densities in the fires <NUM> of the test (VOF(<NUM>)) of about <NUM> to about <NUM>, for example, about <NUM> to about <NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

In some embodiments, the polycarbonate resin composition may have a conventional index of toxicity (CIT) of about <NUM> to about <NUM> (a. (unit)), for example, about <NUM> to about <NUM>, as measured on specimens having sizes of <NUM> × <NUM> × <NUM> to <NUM> at a heat quantity of <NUM> kW/m<NUM> in accordance with the ISO <NUM>-<NUM> standard.

In some embodiments, the polycarbonate resin composition may have a notched Izod impact strength of about <NUM> kgf·cm/cm to about <NUM> kgf·cm/cm, for example, about <NUM> kgf·cm/cm to about <NUM> kgf cm/cm, as measured on a <NUM> thick specimen in accordance with ASTM D256.

A molded article according to the present invention is formed of the polycarbonate resin composition set forth above. For example, the polycarbonate resin composition may be produced into various molded articles (products) by various molding methods, such as injection molding, extrusion molding, vacuum molding, and casting. These molding methods are well known to those skilled in the art. The molded product has good flame retardancy, low heat generation characteristics, low flammability, does not have smoke toxicity, satisfies European Union Standard Fire Testing to Railway Vehicle Components EN45545-<NUM> R1HL2, and is particularly useful as a material for interior or exterior materials of transportation equipment, such as automobile component or railway vehicle components.

Next, the present invention will be described in more detail with reference to some examples. It should be understood that these examples are provided for illustration only and are not to be in any way construed as limiting the present invention.

Details of components used in Examples and Comparative Examples are as follows:.

The aforementioned components were mixed in amounts as listed in Table <NUM>, and <NUM> part by weight of an anti-dripping agent, <NUM> parts by weight of an antioxidant agent (Songwon Industry Inc. , SONGNOX-<NUM>, and Miwon Industry Inc. , ALKANOX <NUM>), and <NUM> parts by weight of a release agent (Hengel, LOXIOL EP-<NUM>) relative to <NUM> parts by weight of the components were added to the mixture, followed by extrusion at <NUM>, thereby preparing a polycarbonate resin composition in pellet form. Here, extrusion was performed using a twin-screw extruder (L/D: <NUM>, Φ: <NUM>). The prepared pellets were dried at <NUM> for <NUM> hours or more and then subjected to injection molding using a <NUM> ton injection machine (molding temperature: <NUM>, mold temperature: <NUM>), thereby preparing a specimen. The specimen was evaluated by the following method and results are shown in Table <NUM>.

From the result, it could be seen that the polycarbonate resin composition according to the present invention exhibited good properties in terms of flame retardancy, flame propagation characteristics (CFE), low heat generation characteristics (MARHE), low flammability (DS(<NUM>), VOF(<NUM>)), and smoke toxicity (CIT).

Claim 1:
A polycarbonate resin composition comprising:
<NUM> parts by weight of a base resin comprising <NUM> wt% to <NUM> wt% of a polycarbonate resin and <NUM> wt% to <NUM> wt% of a polysiloxane-polycarbonate copolymer resin;
<NUM> part by weight to <NUM> parts by weight of silicone gum;
<NUM> part by weight to <NUM> parts by weight of an inorganic metal compound;
<NUM> parts by weight to <NUM> parts by weight of a phosphorus flame retardant; and
<NUM> parts by weight to <NUM> parts by weight of inorganic fillers,
wherein the silicone gum and the inorganic metal compound are present in a weight ratio (silicone gum:inorganic metal compound) of <NUM>:<NUM> to <NUM>:<NUM>.