WO2009082114A1

WO2009082114A1 - Polymer alloy composition

Info

Publication number: WO2009082114A1
Application number: PCT/KR2008/007433
Authority: WO
Inventors: Kyoung Tae Kim; Chang Min Hong
Original assignee: Cheil Industries Inc.
Priority date: 2007-12-21
Filing date: 2008-12-16
Publication date: 2009-07-02

Abstract

Disclosed herein is a polymer alloy composition that has excellent surface ductility along with high impact and flexural strengths. The polymer alloy composition comprises 20-45% by weight of a thermoplastic polyester resin, 55-80% by weight of a thermoplastic elastomer, and 10-120 parts by weight of fibrous fillers with respect to a total amount of 100 parts by weight of the thermoplastic polyester resin and the thermoplastic elastomer. A molded article fabricated from the polymer alloy composition can be usefully applied to various products such as mobile communication devices, precision electronic components, vehicle component, and the like, which require both surface ductility and mechanical strength.

Description

[DESCRIPTION] [Invention Title]

POLYMER ALLOY COMPOSITION

[Technical Field]

The present invention relates to polymer alloy compositions and, more particularly, to polymer alloy compositions that have excellent surface ductility along with high impact and flexural strengths.

[Background Art]

In recent years, studies have been conducted to develop exterior materials for mobile IT devices, which can exhibit excellent surface ductility without urethane painting for providing the ductility to achieve cost reduction and environmental friendliness.

Among these materials, thermoplastic elastomer (TPE) is a possible candidate material with excellent surface ductility, but, disadvantageously, cannot be used alone due to insufficient mechanical strength and thermal properties for use as the exterior material.

To overcome such problems, application of alloys of the TPE and other resins or reinforcement materials has been attempted, but these materials also fail to fulfill the mechanical or thermal properties while losing the advantageous surface ductility of the TPE.

[Disclosure] [Technical Problem] The present invention is conceived to solve the problems as described above, and an aspect of the present invention is to provide a polymer alloy composition and molded article formed using the same, which have excellent surface ductility along with high impact and flexural strengths.

[Technical Solution]

In accordance with an aspect of the present invention, there is provide a polymer alloy composition comprising: (A) 20-45% by weight of a thermoplastic polyester resin; (B) 55-80% by weight of a thermoplastic elastomer; and (C)

10-120 parts by weight of fibrous fillers with respect to a total amount of 100 parts by weight of the thermoplastic polyester resin and the thermoplastic elastomer.

[Advantageous Effects]

When an article is formed using the polymer alloy composition according to an embodiment of the present invention, the article may have excellent surface ductility of rubber along with high impact and flexural strengths. Such an article can be usefully applied to various products such as mobile communication devices, precision electronic components, vehicle component, and the like, which require both surface ductility and mechanical strength.

[Best Mode]

In accordance with an embodiment of the present invention, a polymer alloy composition comprises (A) 20-45% by weight of a thermoplastic polyester resin;

(B) 55-80% by weight of a thermoplastic elastomer; and (C) 10-120 parts by weight of fibrous fillers with respect to a total amount of 100 parts by weight of the thermoplastic polyester resin and the thermoplastic elastomer. [Mode for Invention]

Next, examples of the present invention will be described in detail. However, it should be noted that the examples are given by way of illustration only and that the present invention is not limited to the examples but can be defined only by the accompanying claims as set forth below.

Herein, the term "alkyl group" means an alkyl group having from 1 to 8 carbon atoms; '^valkylene group" means an alkylene group of C1-C20; "cycloalkylene group" means a substituted or non-substituted cycloalkylene group of C3-C18; "alkenylene group" means an alkenylene group of C2-C20; "arylene group" means an arylene group of C6-C30; and "heterocyclic group" means a substituted or non- substituted divalent heterocyclic group comprising at least one selected from the group consisting of oxygen, sulfur, nitrogen, and combinations thereof .

According to an embodiment of the present invention, a polymer alloy composition comprises (A) 20-45% by weight of a thermoplastic polyester resin; (B) 55-80% by weight of a thermoplastic elastomer; and (C) 10-120 parts by weight of fibrous fillers with respect to a total amount of 100 parts by weight of the thermoplastic polyester resin and the thermoplastic elastomer.

Next, the respective components of the polymer alloy composition according to this embodiment will be described in detail.

(A) Thermoplastic polyester resin

The thermoplastic polyester resin may have repeated structures represented by Formula 1 :

[Formula 1]

where A indicates a difunctional group, specifically a substituted or non- substituted alkylene group, a substituted or non-substituted cycloalkylene giOup, a substituted or non-substituted alkenylene group, a substituted or non-substituted arylene group, and a substituted or non-substituted divalent heterocyclic group comprising at least one selected from the group consisting of oxygen, sulfur, nitrogen, and combinations thereof, and preferably indicates a phenyl ene group.

In the difunctional group, at least one hydrogen atom can be substituted with an alkyl group of C1-C4. Each of Ri and R₂ indicate hydrogen or an alkyl group of C1-C4, and preferably hydrogen or a methyl group.

Further, "m" indicates an integer from 2 to 4, and ^un" indicates an integer from 50 to 300.

The thermoplastic polyester resin can be prepared by a typical method for preparation of a polyester resin. One example of the method will now be described in detail.

First, an acid component, a glycol component, and additives such as a catalyst and various stabilizers are charged into a stainless steel autoclave equipped with a stirrer, followed by proceeding an esterification reaction at 200-230 ^°C within the autoclave while removing ester condensation by-products of low molecular weight from the esterification reaction system. The esterification reaction will be finished with reference to a time point where a conversion ratio of the esterification reaction typically reaches 95% or more of a theoretical extraction amount of the low molecular weight ester by-products. When the esterification reaction is finished, condensation polymerization of polyester is induced by decreasing the pressure in the autoclave to 1 mmHg or less while increasing the temperature of the autoclave to 250~280^°C . After advancing the condensation polymerization for a predetermined duration, the reaction is stopped at a suitable stirring load and vacuum is broken by supplying nitrogen to discharge reactants, thereby providing the thermoplastic polyester resin. For the preparation of the thermoplastic polyester resin as described above, the acid component may include terephthalic acid, a lower alkyl ester compound, blends of a small amount of isophthalic acid, orthophthalic acid or aliphatic dicarbon acid therewith, or blends of the lower alkyl ester compounds therewith; and the glycol component may include ethylene glycol, propylene glycol, butylene glycol, blends thereof, or blends of a small amount of 1 ,6-hexanedio or 1 ,4-cyclohexane dimethanol therewith. Further, examples of the catalyst may include antimony oxide, organic titanium compounds, such as tetrabutyl titanate, tetra-isopropyl titanate, and the like, organic tin compounds or blends of the organic titanium compounds with the organic tin compounds, alkaline metal or acetate compounds, and the like. When using the organic titanium compound as the catalysis, magnesium acetate or lithium acetate may be used as a cocatalyst. In addition to these main components and the catalyst, subsidiary materials such as antistatic agents or various additives may be used for the preparation of the thermoplastic polyester resin. Examples of the thermoplastic polyester resin include a polyalkylene terephthalate base resin, and preferably a polybutylene terephthalate base resin.

An example of the polybutylene terephthalate base resin may include polybutylene terephthalate polymer obtained by condensation polymerization through direct esterification or ester interchange reaction of, for example, 1 ,4- butanediol and terephthalic acid or dimethyl terephthalate. Other examples of the polybutylene terephthalate base resin may include copolymers or blends of polybutylene terephthalate and poly(tetramethylene glycol)(PTMG), poly(ethylene glycol)(PEG), poly(propylene glycol)(PPG), low molecular weight aliphatic polyester or aliphatic polyamide. As such, by copolymerizing or mixing such a component for enhancing impact properties with the polybutylene terephthalate, the impact strength of the polybutylene terephthalate base resin can be further enhanced.

Further, the polybutylene terephthalate base resin may have an intrinsic viscosity (η, ) in the range of 0.36-1.60 dl/g at 25 ^°C in o-chlorophenol solvent. With an intrinsic viscosity less than 0.36 dl/g, the polybutylene terephthalate base resin can undergo deterioration in mechanical properties, and with an intrinsic viscosity exceeding 1.60 dl/g, the polybutylene terephthalate base resin can undergo deterioration in formability. Therefore, it is advantageous to use the polybutylene terephthalate base resin having the intrinsic viscosity in the above range in terms of balance of the mechanical properties and the formability.

The thermoplastic polyester resin may be included in an amount of 20-45% by weight (hereinafter, wt%) in the polymer alloy composition with respect to a total amount of (A) the thermoplastic polyester resin and (B) the thermoplastic elastomer.

This content of thermoplastic polyester resin can prevent deterioration of the mechanical properties and surface ductility of the completed composition.

(B) Thermoplastic elastomer

The thermoplastic elastomer (TPE) comprises elastic rubber components (a soft segment) and molecular restriction components (a hard segment) for preventing deformation of thermoplastic properties in molecules of the thermoplastic elastomer. The polymer alloy composition can realize various properties such as strength, thermal resistance, chemical resistance, wear resistance, and the like by varying kinds, molecular weights, and arrangements of the soft and hard segments.

Examples of the thermoplastic elastomer may include an olefin-based elastomer, a styrene-based elastomer, an ester-based elastomer, a polyvinyl chloride

(PVC)-based elastomer, a urethane-based elastomer, an amide-based elastomer, copolymers or blends thereof. Advantageously, the ester-based elastomer is used for the thermoplastic elastomer. Specifically, the ester-based thermoplastic elastomer may have a hardness of 20~60 (shore D). When the hardness of the elastomer is less than 20, the final molded article can undergo deterioration of the mechanical properties. On the other hand, when the hardness of the elastomer exceeds 60, surface ductility cannot be ensured. Thus, it is advantageous to use the ester-based thermoplastic elastomer having the hardness in the above range in terms of balance of mechanical properties and surface ductility. More preferably, the ester-based thermoplastic elastomer has a hardness of 30-50.

The thermoplastic elastomer may be included in an amount of 55-80 wt% in the polymer alloy composition with respect to a total amount of (A) the thermoplastic polyester resin and (B) the thermoplastic elastomer.

With this content of thermoplastic elastomer, the polymer alloy composition may have desired surface ductility while preventing deterioration of the mechanical properties thereof.

(C) Fibrous Fillers

The fibrous fillers serve to enhance the properties, such as strength, rigidity, thermal resistance, and the like, of the polymer alloy composition that comprises (A) the thermoplastic polyester resin and (B) the thermoplastic elastomer. Specifically, although various forms of the fibrous fillers can be applied according to the use of the polymer alloy composition, the fibrous fillers may have a length of 0.1-30 mm. The fibrous fillers with this range of length advantageously ensure excellent flexural strength and productivity of the polymer alloy composition.

Examples of the fibrous fillers may include glass fiber, basalt fiber, metal fiber, boron fiber, aramid fiber, natural fiber, potassium titanate fiber, silicon carbide fiber, Wallostonite, carbon fiber, and the like.

The fibrous fillers may be included in an amount of 10-120 parts by weight in the polymer alloy composition with respect to a total amount of 100 parts by weight of (A) the thermoplastic polyester resin and (B) the thermoplastic elastomer. If the content of fibrous fillers is less than 10 parts by weight, the polymer alloy composition can undergo deterioration in mechanical properties, and if above 120 parts by weight, the polymer alloy composition can undergo deterioration in surface ductility and appearance. Thus, when using this content of fibrous fillers, the polymer alloy composition may have desired properties in terms of balance of surface ductility and mechanical properties.

(D) Additives

In addition to the (A) to (C) components, the polymer alloy composition may further comprise other additives, for example, inorganic fillers, such as talc, silica, mica, alumina, and the like, ultraviolet ray absorbent, thermal stabilizer, antioxidant, flame retardant, lubricant, coloring agent such as dye and pigment, and the like, according to the use of the polymer alloy composition. These additives are well known to those skilled in the art with regard to the amount and method of use thereof.

The polymer alloy composition with the composition as above can be prepared by a typical method of preparing a general resin composition. For example, the polymer alloy composition may be prepared in a pellet shape by simultaneously mixing the aforementioned components and the other additives, and melt-extruding the resultant mixture with an extruder.

The polymer alloy composition according to the embodiment of the invention comprises the thermoplastic polyester resin and fibrous fillers along with the thermoplastic elastomer, thereby exhibiting excellent surface ductility along with high impact strength, flexural strength, and thermal properties. As a result, the polymer alloy composition can be usefully applied to various molded articles, such as housings of mobile communication devices, vehicle components, and the like, which require good surface ductility, high mechanical strength, and high thermal properties. Therefore, according to another embodiment of the present invention, a molded article produced from the polymer alloy composition of the present invention is provided.

Next, examples of the present invention will be described in detail to show advantageous effects of the present invention. It should be noted that these examples are given by way of illustration only and the present invention is not limited to these examples.

1. Examples and Comparative Examples In the following examples and comparative examples were used (A) a thermoplastic polyester resin, (B) a thermoplastic elastomer, and (C) fibrous fillers as follows.

(A) Thermoplastic polyester resin

The thermoplastic polyester resin was polybutylene terephthalate TRIBIT 1700 that was obtained from Samyang Corporation, Korea, and had a specific gravity of 1.31 g/cui , a melting point of 226 ^°C and an inherent viscosity of 1.10.

(B) Thermoplastic elastomer

The thermoplastic elastomer was ester-based thermoplastic elastomer gl30D that was obtained from SK Chemical Industries, Co., Korea, and had a Shore D Hardness of 30.

(C) Fibrous fillers

The fibrous fillers were chop type glass fiber 952 obtained from Saint- Gobain Vetrotex, Ltd., US and filament type fillers SE-8380 obtained from Owens Coming, Ltd., US.

As the thermoplastic polyester resin, polybutylene terephthalate TRIBIT 1700 from Samyang Corporation, Korea was used, and had a specific gravity of 1.31 g/αif, a melting point of 226 ^°C and an inherent viscosity of 1.10. As the thermoplastic elastomer, ester-based thermoplastic elastomer gl30D from SK Chemical Industries Co., Korea was used and had a Shore D Hardness of 30. Further, as the fibrous fillers, chop type glass fiber 952 from Saint-Gobain Vetrotex, Ltd. was used. After mixing these components in a mixer, the resultant mixture was extruded through a twin screw extruder with L/D=35 and φ =45mm under conditions of a fixed temperature of 240 ^°C , a screw rotational speed of 150 rpm, a first vent pressure of about -600 mmHg, and an automatic supply speed of 60 kg/h. Then, the extruded strand was cooled in water, and cut into pellets by a rotating cutter.

Table 1 shows the contents of the thermoplastic polyester resin, thermoplastic elastomer, and fibrous fillers used in preparation of the examples and comparative examples.

Table 1

2. Preparation of samples

After drying the pellets of Examples 1 to 6 and Comparative Examples 1 to 5 at 80 ^°C with hot air for about 5 hours, samples were extruded at a molding temperature of 210-260 ^°C and a mold temperature of 60-90 ^°C from a 10-oz extruder, and tested for property evaluation.

3. Measurement of properties

The properties of the prepared samples were tested as follows, and are listed in Table 2.

(1) Impact strength: Notch Izod impact strength (1/8^" ) was measured according to ASTM D256. (2) Flexural strength: Flexural strength (thickness: 1/4^" ) was measured according to ASTM D790.

(3) Thermal resistance: Thermal resistance was measured according to ASTM D648.

(4) Surface ductility: Surface hardness Shore D was measured according to ASTM D2240.

Table 2

As can be seen from Table 2, the samples prepared from polymer alloy compositions of Examples 1 to 6 had an excellent balance between surface ductility and mechanical-physical properties such as impact strength, flexural strength, and thermal resistance.

Compared with the samples of the inventive examples, Comparative Example 1, where the fibrous fillers were not added, exhibited poor mechanical- physical properties, and Comparative Examples 2 to 4, which had higher amounts of (A) component and lower amounts of (B) component than those of the present invention, exhibited deteriorated surface ductility despite good mechanical properties. Further, Comparative Example 5, which had a lower amount of (A) component and a higher amount of (B) component than those of the present invention, exhibited deteriorated mechanical properties.

Claims

[CLAIMS]

[Claim 1 ]

A polymer alloy composition comprising: (A) 20~45% by weight of a theπnoplastic polyester resin; (B) 55-80% by weight of a thermoplastic elastomer; and

(C) 10-120 parts by weight of fibrous fillers with respect to a total amount of 100 parts by weight of the thermoplastic polyester resin and the thermoplastic elastomer.

[Claim 2]

The polymer alloy composition according to claim 1, wherein the thermoplastic polyester resin has repeated structures represented by Formula 1. [Formula 1]

(where A indicates a substituted or non-substituted alkylene group, a substituted or non-substituted cycloalkylene group, a substituted or non-substituted alkenylene group, a substituted or non-substituted arylene group, and a substituted or non-substituted divalent heterocyclic group comprising at least one selected from the group consisting of oxygen, sulfur, nitrogen, and combinations thereof; each of

Ri and R₂ indicate hydrogen or an alkyl group; "m" indicates an integer from 2 to 4; and "n'' indicates an integer from 50 to 300)

[Claim 3 ] The polymer alloy composition according to claim 1, wherein the thermoplastic polyester resin comprises polyalkylene terephthalate.

[Claim 4]

The polymer alloy composition according to claim 1, wherein the thermoplastic polyester resin comprises one selected from the group consisting of copolymers and blends of polybutylene terephthalate and poly(tetramethylene glycol), poly(ethylene glycol), poly(propylene glycol), aliphatic polyester or aliphatic polyamide.

[Claim 5]

The polymer alloy composition according to claim 1, wherein the thermoplastic polyester resin has an intrinsic viscosity (r\, ) of 0.36-1.60 dl/g at 25 ^°C in o-chlorophenol solvent.

[Claim 6]

The polymer alloy composition according to claim 1, wherein the thermoplastic elastomer is at least one selected from the group consisting of an olefm-based elastomer, a styrene-based elastomer, an ester-based elastomer, a polyvinyl chloride (PVC)-based elastomer, a urethane-based elastomer, and an amide-based elastomer.

[Claim 7] The polymer alloy composition according to claim 1, wherein the thermoplastic elastomer is an ester-based elastomer having a hardness of 20-60 (Shore D).

[Claim 8]

The polymer alloy composition according to claim 1, wherein the fibrous fillers are selected from the group consisting of glass fiber, basalt fiber, metal fiber, boron fiber, aramid fiber, natural fiber, potassium titanate fiber, silicon carbide fiber, Wallostonite, carbon fiber, and combinations thereof.

[Claim 9]

The polymer alloy composition according to claim 1, wherein the fibrous fillers have a length of 0.1~30 mm.

[Claim 10]

The polymer alloy composition according to claim 1 , further comprising: additives selected from the group consisting of inorganic fillers, ultraviolet ray absorbent, thermal stabilizer, antioxidant, flame retardant, lubricant, dye, pigment, and combinations thereof.

[Claim 11 ]

A molded article fabricated from the polymer alloy composition according to any one of claims 1 to 10.