Patent Description:
A polypropylene resin has good properties in terms of chemical resistance, weather resistance, and processability to be easily produced into injection-molded products, films, and blow-molded products, and is widely applied to automobiles, building materials, electric parts, and the like.

Since the polypropylene resin is flammable due to the chemical structure thereof, various organic or inorganic flame retardants are added together in order to impart flame retardancy. However, with increasing interest in environmental issues, regulation on existing halogen-based flame retardants has been gradually strengthened. In order to use thermoplastic resin compositions as eco-friendly materials, there is a need for reduction or exclusion of the halogen-based flame retardants.

However, thermoplastic resin compositions prepared using a non-halogen-based flame retardant alone have a problem of significant deterioration in flame retardancy, as compared to thermoplastic resin compositions prepared using a halogen-based flame retardant. Moreover, use of an excess of a flame retardant for improvement in flame retardancy of the thermoplastic resin compositions can cause deterioration in mechanical properties.

Therefore, there is a need for development of a thermoplastic resin composition that exhibits good properties in terms of flame retardancy, impact resistance, balance therebetween, and the like.

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

It is one object of the present invention to provide a thermoplastic resin composition having good properties in terms of flame retardancy, impact resistance, and the like.

It is another object of the present invention to provide a molded product produced from the thermoplastic resin composition.

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

The present invention provides a thermoplastic resin composition having good properties in terms of flame retardancy, impact resistance, and the like, and a molded product produced therefrom.

A thermoplastic resin composition according to the present invention includes: (A) an ethylene-propylene block copolymer; (B) a phosphinate compound; (C) a phosphorus nitrogen-based flame retardant; and (D) a bromine-based flame retardant.

According to the present invention, the ethylene-propylene block copolymer is lightweight and has good mechanical properties, and may be selected from any ethylene-propylene block copolymers (block polypropylene) for typical thermoplastic resin compositions. For example, the ethylene-propylene block copolymer may be obtained through sequential polymerization of a propylene homopolymerization part and an ethylene-propylene copolymerization part in a reactor.

In some embodiments, the ethylene-propylene block copolymer may include about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, of ethylene and about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, of propylene. Within this range, the thermoplastic resin composition can have good moldability, good impact resistance, and the like.

In some embodiments, the ethylene-propylene block copolymer may include about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, of a propylene homopolymer, which is present in a continuous phase (matrix), and about <NUM> wt% to about <NUM> wt%, for example, about <NUM> wt% to about <NUM> wt%, of an ethylene-propylene copolymer, which is a rubber component present in a dispersed phase. Within this range, the thermoplastic resin composition can have good rigidity, good impact resistance, and the like.

In some embodiments, the ethylene-propylene block 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 <NUM> kgf in accordance with ASTM D1238. Within this range, the thermoplastic resin composition can have good impact resistance and the like.

According to the present invention, the metal phosphinate compound can improve flame retardancy and heat resistance of the ethylene-propylene block copolymer (thermoplastic resin) composition even with a small amount together with the phosphorus nitrogen-based flame retardant and the bromine-based flame retardant, and may be a compound represented by Formula <NUM>. <CHM>
where R<NUM> and R<NUM> are each independently a C<NUM> to C<NUM> alkyl group or a C<NUM> to C<NUM> aryl group; M is Al, Zn, Mg, Ca, Sb, Sn, Ge, Ti, Fe, Zr, Ce, Bi, Sr, Mn, Li, or Na; and n is an integer of <NUM> to <NUM>.

In some embodiments, the metal phosphinate compound may be aluminum diethyl phosphinate or zinc diethyl phosphinate.

In some embodiments, the metal phosphinate compound 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 ethylene-propylene block copolymer. If the content of the metal phosphinate compound is less than about <NUM> parts by weight relative to about <NUM> parts by weight of the ethylene-propylene block copolymer, the thermoplastic resin composition can suffer from deterioration in flame retardancy and the like, and if the content of the metal phosphinate compound exceeds about <NUM> parts by weight, the thermoplastic resin composition can suffer from deterioration in impact resistance and the like.

According to the present invention, the phosphorus nitrogen-based flame retardant can improve flame retardancy of the ethylene-propylene block copolymer (thermoplastic resin) composition even with a small amount together with the metal phosphinate compound and the bromine-based flame retardant, and may be selected from any phosphorus nitrogen-based flame retardants for typical thermoplastic resin compositions.

In some embodiments, the phosphorus nitrogen-based flame retardant may include at least one of melamine polyphosphate, melam pyrophosphate, melem pyrophosphate, melon pyrophosphate, melamine pyrophosphate, dimelamine pyrophosphate, melamine polyphosphate, melam polyphosphate, melon polyphosphate, melem polyphosphate, mixed multi-salts thereof, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, and ammonium polyphosphate. For example, the phosphorus nitrogen-based flame retardant may include melamine polyphosphate, ammonium polyphosphate, and the like.

In some embodiments, the phosphorus nitrogen-based flame retardant may be present in an amount of about <NUM> parts by weight to about <NUM> parts by weight, for example, about <NUM> part by weight to about <NUM> parts by weight, relative to about <NUM> parts by weight of the ethylene-propylene block copolymer. If the content of the phosphorus nitrogen-based flame retardant is less than about <NUM> parts by weight relative to about <NUM> parts by weight of the ethylene-propylene block copolymer, the thermoplastic resin composition can suffer from deterioration in flame retardancy and the like, and if the content of the phosphorus nitrogen-based flame retardant exceeds about <NUM> parts by weight, the thermoplastic resin composition can suffer from deterioration in impact resistance and the like.

In some embodiments, the metal phosphinate compound (B) and the phosphorus nitrogen-based flame retardant (C) may be present in a weight ratio (B:C) of about <NUM>:<NUM> to about <NUM>:<NUM>, for example, about <NUM>:<NUM> to about <NUM>:<NUM>. Within this range, the thermoplastic resin composition can have better properties in terms of flame retardancy, impact resistance, and the like.

According to the present invention, the bromine-based flame retardant can improve flame retardancy of the ethylene-propylene block copolymer (thermoplastic resin) composition even with a small amount together with the metal phosphinate compound and the phosphorus nitrogen-based flame retardant, and may be selected from any bromine-based flame retardants for typical thermoplastic resin compositions.

In some embodiments, the bromine-based flame retardant may include tetrabromo bisphenol-A bis(<NUM>,<NUM>-dibromopropyl ether), tetrabromo bisphenol-A, decabromodiphenyl oxide, decabrominated diphenyl ethane, <NUM>,<NUM>-bis(<NUM>,<NUM>,<NUM>-tribromophenyl)ethane, octabromo-<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-phenylindane, and <NUM>,<NUM>,<NUM>-tris(<NUM>,<NUM>,<NUM>-tribromophenoxy)-<NUM>,<NUM>,<NUM>-triazine, combinations thereof, and the like.

In some embodiments, the bromine-based flame retardant 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 ethylene-propylene block copolymer. If the content of the bromine-based flame retardant is less than about <NUM> parts by weight relative to about <NUM> parts by weight of the ethylene-propylene block copolymer, the thermoplastic resin composition can suffer from deterioration in flame retardancy and the like, and if the content of the bromine-based flame retardant exceeds about <NUM> parts by weight, the thermoplastic resin composition has a bromine content of greater than <NUM> ppm, which does not satisfy international environment regulations (RoHS (Restriction of Hazardous Substances)), and can suffer from deterioration in impact resistance and the like.

In some embodiments, the metal phosphinate compound (B) and the bromine-based flame retardant (D) may be present in a weight ratio (B:D) of about <NUM>:<NUM> to about <NUM>:<NUM>, for example, about <NUM>:<NUM> to about <NUM>:<NUM>. Within this range, the thermoplastic resin composition can have better flame retardancy and the like.

In some embodiments, the phosphorus nitrogen-based flame retardant (C) and the bromine-based flame retardant (D) may be present in a weight ratio (C:D) of about <NUM>:<NUM> to about <NUM>:<NUM>, for example, about <NUM>:<NUM> to about <NUM>:<NUM>. Within this range, the thermoplastic resin composition can have better flame retardancy and the like and satisfy the RoHS international environment regulations.

According to one embodiment of the present invention, the thermoplastic resin composition may further include additives for typical thermoplastic resin compositions. Examples of the additives may include impact modifiers, antioxidants, anti-dripping agents, lubricants, release agents, nucleating agents, antistatic agents, stabilizers, pigments, dyes, and mixtures thereof, without being limited thereto. The additives 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 ethylene-propylene block copolymer.

The thermoplastic resin composition according to one embodiment may be prepared in pellet form by mixing the aforementioned components, followed by melt extrusion at about <NUM> to about <NUM>, for example, about <NUM> to about <NUM>, using a typical twin-screw extruder.

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

In some embodiments, the thermoplastic resin composition may have a glow wire ignitability temperature (GWIT) of about <NUM> or more, for example, about <NUM> to about <NUM>, and a glow wire flammability index (GWFI) of about <NUM> or more, for example, about <NUM> to about <NUM>, as measured on a specimen having a size of <NUM> × <NUM> × <NUM> in accordance with UL746A.

In some embodiments, the thermoplastic resin composition may have a halogen content of about <NUM> ppm to about <NUM> ppm, for example, about <NUM> ppm to about <NUM> ppm, in a <NUM> specimen, as measured by ion chromatography in accordance with KS C IEC <NUM>-<NUM>-<NUM>.

In some embodiments, the thermoplastic 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 product according to the present invention is produced from the thermoplastic resin composition as set forth above. The thermoplastic resin composition may be prepared in pellet form. The prepared pellets may be produced into various molded products (articles) 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 products may be produced by vacuum molding and have good properties in terms of flame retardancy, impact resistance, and balance therebetween. In addition, the molded products have a halogen content of <NUM> ppm, which satisfies the RoHS international environment regulations, and thus can be advantageously used in various electric and/or electronic components, particularly connector components.

Next, the present invention will be described in more detail with reference to some examples.

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

The above components were mixed in amounts as listed in Tables <NUM> and <NUM>, and subjected to extrusion at <NUM>, thereby preparing pellets. Here, extrusion was performed using a twin-screw extruder (L/D=<NUM>, Φ: <NUM>) and the prepared pellets were dried at <NUM> for <NUM> hours or more and injection-molded in a <NUM> oz. injection molding machine (molding temperature: <NUM>, mold temperature: <NUM>), thereby preparing specimens. The specimens were evaluated as to the following properties by the following method, and results are shown in Tables <NUM> and <NUM>.

From the above results, it could be seen that the thermoplastic resin composition according to the present invention exhibited good properties in terms of flame retardancy (UL94, GWIT, GWFR) and impact resistance (notched Izod impact strength), and had a halogen content of <NUM> ppm or less satisfying the RoHS international environment regulation.

Claim 1:
A thermoplastic resin composition comprising:
<NUM> parts by weight of an ethylene-propylene block copolymer:
<NUM> parts by weight to <NUM> parts by weight of a metal phosphinate compound;
<NUM> parts by weight to <NUM> parts by weight of a phosphorus nitrogen-based flame retardant; and
<NUM> parts by weight to <NUM> parts by weight of a bromine-based flame retardant.