KR101494528B1 - Polypropylene resin composition for conjugated duct having improved resistance at low temperature and molded conjugated duct prepared therefrom - Google Patents

Abstract

An impact block copolymer resin composition which is suitable for use as a flexible wire for industrial use and which has a high bending modulus of elasticity while maintaining a high flexural modulus even during the winter season, and which improves the problem of being broken by impact in the winter season, and a flexible wire tube manufactured therefrom. The present invention relates to a thermoplastic resin composition comprising 0.05 to 1 part by weight of a nucleating agent, 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant, 0.01 to 5 parts by weight of a phenolic antioxidant, (ASTM evaluation method D256) of 6.0 kg · cm / cm or more and an Izod impact strength (-10 ° C) of 0.01 to 0.5 parts by weight and a neutralizing agent, .

Description

TECHNICAL FIELD [0001] The present invention relates to a polypropylene resin composition for a flexible wire tube having improved low-temperature impact resistance and a flexible wire tube made therefrom. BACKGROUND OF THE INVENTION < RTI ID = 0.0 >

More particularly, the present invention relates to an impact block copolymer resin composition for a flexible wire tube for solving the problem of breaking a shock during the winter season while maintaining stiffness even during a summer season, and a flexible cable .

Impact block copolymers are general-purpose olefin resins used in special situations and are used in a wide variety of applications such as food containers, short sheets, household goods, and industrial materials. The reason why the impact block copolymer is used in various ways is that it is less toxic than other plastics and has better physical properties such as low temperature impact strength than polypropylene and good workability. Particularly, since it is not decomposed by an acidic or basic solution (concrete) and has excellent chemical resistance, it is widely used for foods and building materials for various purposes. Among them, it is also used as a material of a flexible conduit (CD tube).

Currently, high density polyethylene (HDPE) and recycled resin are mainly used for flexible cable conduits, but impact block copolymers are in widespread application because they require workability at the construction site as well as flame retardancy and resilience of flexible conduits. However, when the conventional impact block copolymer is used, the low temperature impact strength is so low that the cracking phenomenon frequently occurs at a temperature below freezing in the winter season. Therefore, it is necessary to study an impact block copolymer which is not broken during the winter season.

Further, during the summer season, a phenomenon that the flexural modulus deteriorates due to the occurrence of a phenomenon is caused, which may cause a problem that the restoring force is lowered. Therefore, there is also a need for studies on an impact block copolymer resin composition that maintains a high flexural modulus in the summer.

Open Patent Publication No. 2009-0101038 discloses a polypropylene composition for a flame retardant flexural wire tube comprising a polypropylene block copolymer, a flame retardant, an antimony trioxide, a dispersant, an antioxidant, etc. However, it has an improved flame retardant effect Temperature shock resistance and flexural modulus in addition to the properties exhibited by the present invention.

Patent Publication No. 0997052 discloses a flame retardant flexible wiring board masterbatch composition for polypropylene containing polyethylene as a base resin and containing a flame retardant agent, antimony trioxide, an antioxidant, etc., but also relates to improvement of low temperature impact resistance and flexural modulus But not limited to, masterbatch compositions which are added during molding for the flexible wire tube.

Accordingly, it is an object of the present invention to solve the above-mentioned problems, and an object of the present invention is to provide a flexible cable which is suitable for use as a flexible electric wire for industrial use and which can maintain a high flexural modulus even during the summer, It is an object of the present invention to provide an impact block copolymer resin composition capable of reducing the use of a flame retardant agent rather than a low density polyethylene resin composition used as a raw material and capable of improving the restoring force and improving the workability at the construction site and a flexible conduit made therefrom .

In order to solve the above-described problems, the present invention provides a thermoplastic resin composition comprising 0.05 to 1 part by weight of a nucleating agent, 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant, 0.1 to 5 parts by weight of a phenolic antioxidant per 100 parts by weight of a mixture comprising 90 to 99% by weight of an impact block copolymer and 1 to 10% by weight of high- 0.01 to 0.5 parts by weight of a phenol antioxidant and 0.01 to 0.5 parts by weight of a neutralizing agent and having an IZOD impact strength (-10 占 폚) (ASTM evaluation method D256) of 6.0 kg 占 / m / cm or more, to provide.

Also, the impact block copolymer has an ethylene content of 8 to 12% by weight and a melt index of 0.2 to 1 g / 10 min (230 ° C, 2.16 kg load).

The present invention also provides a polypropylene resin composition for a flexible wire tube, wherein the nucleating agent is zinc and a calcium salt compound.

The present invention also provides a polypropylene resin composition for a flexible wire tube, wherein the phosphorus antioxidant is tris (2,4-di-t-butylphenyl) phosphite.

The polypropylene resin composition for a flexible wire tube characterized in that the phenolic antioxidant is tetrakis [ethylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] to provide.

The present invention also provides a polypropylene resin composition for a flexible wire tube, wherein the neutralizing agent is calcium stearate.

Also, the resin composition has a flexural modulus (ASTM evaluation method D790) of 12,300 kgf / cm < 2 > or more.

In order to solve the above-described problems, the present invention provides a flexible wire tube made of the polypropylene resin composition.

According to the present invention, it is possible to provide a polypropylene resin composition which is not broken during the winter season and which maintains high rigidity during the summer season for the flexible wire tube by mixing the impact block copolymer with the modifier, the nucleating agent, the antioxidant, .

In addition, the polypropylene resin composition according to the present invention can be effectively used for the manufacture of flexible conduits for use in building materials by an extrusion molding process or the like.

1 and 2 are photographs showing the result of low-temperature impact test on a flexible cable manufactured by using the polypropylene resin composition of Example and Comparative Example 5,
Figs. 3 and 4 are electron micrographs showing the shape of the propylene-ethylene rubber in the impact block copolymer in the molded article for Example and Comparative Example 8. Fig.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It is to be understood that various equivalents and modifications may be substituted for those at the time of the present application.

The inventors of the present invention have observed the problem of the cold cracking phenomenon caused by low temperature impact property when manufacturing a flexible cable using a conventional impact block copolymer and have conducted intensive studies. As a result, it has been found that the impact block copolymer, It has been surprisingly found that when a phosphorus antioxidant, a phenol antioxidant and a neutralizing agent are mixed at an optimum amount, they are not broken during the winter season when manufactured for a flexible wire, and that the bending elastic modulus during summer can be lowered. .

Accordingly, the present invention relates to a resin composition comprising 0.05 to 1 part by weight of a nucleating agent, 0.01 to 0.5 part by weight of a phosphorus-based antioxidant, 0.01 to 5 parts by weight of a phenol-based antioxidant, (ASTM evaluation method D256) of 6.0 kg 占 / m / cm or more, wherein the IZOD impact strength (-10 占 폚) (ASTM evaluation method D256) is 0.01 to 0.5 parts by weight and the neutralizer is 0.01 to 0.5 parts by weight. Hereinafter, each constitution of the polypropylene resin composition according to the present invention will be described in detail.

(One) impact  block Copolymer

As the impact block copolymer, those prepared by a conventionally known method can be used. For example, propylene and ethylene may be simultaneously charged into a polymerization reactor, triethylaluminum, a phthalate catalyst and a silane-based electron donor may be introduced, and gas phase polymerization may be carried out at a reaction temperature of 65 to 75 ° C and 32 to 34 atm.

The ethylene content of the impact block copolymer may be 8-12 wt%, preferably 8-10 wt%. When the ethylene content is less than 8% by weight, the low temperature impact strength may be lowered. If the ethylene content is more than 12% by weight, the low temperature impact strength is excellent, but the stiffness is decreased. The impact block copolymer used for the conventional flexible wire has a limited ethylene content of 5 to 7% by weight but is unsatisfactory for improving the low temperature impact strength. In the present invention, the ethylene content is more preferably And the addition of a high-density polyethylene which will later be used as a modifier further improves the low-temperature impact strength.

In addition, the melt index of the impact block copolymer may be 0.2 to 1 g / 10 min (230 ° C, 2.16 kg load), preferably 0.4 to 0.6 g / 10 min. If the melt index is less than 0.2 g / 10 min, production may not be possible due to process problems. If the melt index exceeds 1 g / 10 min, the defect rate in the extrusion process of the product may increase.

(2) High density polyethylene

In the present invention, high-density polyethylene is used as a modifier of an impact block copolymer so as to maintain a low-temperature impact strength at an optimum level for use of an impact block copolymer alone. The density is 0.95 to 0.97 g / cm 3, preferably 0.959 to 0.963 g / cm < 3 > can be used. On the other hand, when linear low density polyethylene having a density of 0.91 to 0.93 g / cm 3 is used as a modifier, the low temperature impact strength is remarkably lowered.

The high-density polyethylene may be used in an amount of 1 to 10 wt% based on the total weight of the impact block copolymer and 3 to 5 wt% optimally to improve the impact strength at low temperatures. When the content of the high-density polyethylene is less than 1% by weight, it may be difficult to exhibit satisfactory low-temperature impact strength characteristics. If the content of the high-density polyethylene exceeds 10% by weight, improvement in the degree of modification relative to the content is limited and moldability may be deteriorated.

(3) Nucleating agent

In the present invention, the nucleating agent is used for the purpose of preventing a decrease in rigidity and a decrease in heat resistance due to a decrease in the heat distortion temperature due to a decrease in the flexural modulus, which can be generated by the addition of the high density polyethylene used as a modifier. The impact block copolymer and the high density polyethylene 0.05 to 1 part by weight, preferably 0.1 to 0.3 part by weight, based on 100 parts by weight of the composition. When the content of the nucleating agent is less than 0.05 part by weight, it is difficult to obtain a sufficient flexural modulus and the crystallization rate effect may be deteriorated. When the amount of the nucleating agent is more than 1 part by weight, low temperature impact strength is lowered and further property improvement in terms of flexural modulus and crystallization speed is expected It can be difficult.

As such a nucleus agent, organic nucleating agents such as zinc and calcium salt compounds, sorbitol compounds, phosphoric acid ester compounds and the like and inorganic nucleating agents such as talc can be used, but the remarkable improvement in rigidity and the rate of crystallization are further shortened, It is most preferable to use zinc and calcium salt compounds in order to maintain an optimum level of zinc and calcium salts.

(4) Other additives

In the polypropylene resin composition for a flexible wire tube according to the present invention, it is necessary to simultaneously add a phosphorus-based antioxidant and a phenol-based antioxidant as additives, and the phosphorus-based antioxidant is added to the impact block copolymer and the high- 0.5 part by weight and the phenolic antioxidant is 0.01 to 0.5 part by weight. Preferably, 0.05 to 0.15 parts by weight of the phosphorus antioxidant and 0.05 to 0.2 parts by weight of the phenolic antioxidant may be included.

If the content of the phosphorus antioxidant is less than 0.01 part by weight, pyrolysis of the polypropylene resin itself may occur during processing, adversely affecting the physical properties. If the content is more than 0.5 parts by weight, the color change after molding may be affected.

When the content of the phenolic antioxidant is less than 0.01 part by weight, the physical properties such as the yield stress may be affected. When the amount of the phenolic antioxidant is more than 0.5 parts by weight, Can affect the color change.

The phosphorus-based antioxidant and the phenol-based antioxidant are not particularly limited, and they may be used alone or in combination of two or more thereof. However, in view of maintaining an optimum level of low-temperature impact strength and flexural modulus, the phosphorus antioxidant is tris (2,4-di-t-butylphenyl) phosphite, the phenolic antioxidant is tetrakis [ Di-t-butyl-4-hydroxyphenyl) propionate] methane.

In order to neutralize the residual catalyst in the polypropylene resin, the polypropylene resin composition for a flexible wire tube according to the present invention may contain 0.01 to 0.5 parts by weight, preferably 0.05 to 5 parts by weight, per 100 parts by weight of the impact block copolymer and high density polyethylene, 0.2 part by weight.

Examples of the neutralizing agent include fatty acid metal salts such as lithium stearate, calcium stearate and sodium stearate, and fatty acid amides such as ethylenebisstearoamide and stearic acid amide. However, It is preferable to use calcium stearate in view of the above.

In addition, the low-temperature impact strength and flexural modulus of the polypropylene resin composition to which the antistatic agent, the anti-blocking agent, the slip agent, the weathering / light stabilizer, the pigment, It can be added within a range that does not deteriorate.

The molded article produced from the polypropylene resin composition according to the present invention has excellent flexural modulus and low temperature impact strength and can be used for food containers and building materials for various purposes and can be effectively used as a material for flexible conduits . Specifically, when the polypropylene resin composition according to the present invention has an IZOD impact strength (-10 ° C) (ASTM evaluation method D256) of 6.0 kg · cm / cm or more and a bending elastic modulus (ASTM evaluation method D790) of 12,300 kg it is possible to provide a polypropylene resin composition for a flexible wire tube having a f / cm < 2 >

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. However, the following examples are illustrative of the present invention, and the present invention is not limited to the examples described below.

Manufacturing example : impact  block Copolymer  Produce

The polymerization reactor was charged with propylene and ethylene simultaneously, and triethylaluminum, a phthalate catalyst and a silane-based electron donor were introduced, and the gas phase polymerization was carried out at a reaction temperature of 65 to 75 ° C and a pressure of 32 to 34 atm. Propylene block copolymer was prepared, and the melt index was adjusted to 0.5 g / 10 min (230 캜, 2.16 kg load) by hydrogen.

Example

0.1 part by weight of a zinc and calcium salt compound (C1) as a nucleating agent was added to 100 parts by weight of a mixture consisting of 95% by weight of an impact block copolymer (A) and 5% by weight of high density polyethylene (B1) (3,5-di-t-butyl-4-hydroxyphenyl) phosphite (D) as a phenolic antioxidant, Propionate] methane (E) and 0.1 part by weight of calcium stearate (F) as a neutralizing agent were mixed in a Henschel mixer for 5 minutes and then extruded by a twin-screw extruder at 180 to 220 ° C to prepare a polypropylene resin composition .

Comparative Example  One

A polypropylene resin composition was prepared in the same manner as in Example except that the impact block copolymer (A) was changed to 100 wt% and the nucleating agent (C1) was not added.

Comparative Example  2

A polypropylene resin composition was prepared in the same manner as in Example except that the nucleating agent (C1) was not added.

Comparative Example  3

A polypropylene resin composition was prepared in the same manner as in Example except that high density polyethylene (B2) having different physical properties was used in the examples and nucleating agent (C1) was not added.

Comparative Example  4

A polypropylene resin composition was prepared in the same manner as in Example except that linear low-density polyethylene (B3) was used instead of high-density polyethylene and nucleating agent (C1) was not added.

Comparative Example  5

Except that the cis-endo-bicyclo [2,2,1] heptane-2,3-dicarboxylic acid (C2) was used instead of the zinc and calcium salt compounds as nucleating agents in the Examples. Thereby preparing a propylene resin composition.

Comparative Example  6

Except that sodium 2,2'-methylre Nevis- (4,6-di-tetra-butylphenyl) phosphplay (C3) was used instead of zinc and calcium salt compounds as nucleating agents in the Examples. Thereby preparing a propylene resin composition.

Comparative Example  7

A polypropylene resin composition was prepared in the same manner as in Example except for using sodium sodium benzoate (C4) as a nucleating agent instead of zinc and calcium salt compound in the examples.

Comparative Example  8

A polypropylene resin composition was prepared in the same manner as in Example except that talc (C5) was used instead of zinc and calcium salt compounds as nucleating agents in Examples.

The composition of the resin compositions prepared according to the above Examples and Comparative Examples is shown in Table 1 below.

Test Example  One

The pellet-shaped polypropylene resin compositions prepared according to the above Examples and Comparative Examples were injected with a molding extruder (Lotte Chemical Co., Ltd.) to prepare specimens for measuring physical properties, and molded flexible conduits were manufactured using an extruder. The properties of each of the prepared specimens were measured in the following manner, and the results are shown in Table 2 below. 1 and 2 show the results of the low-temperature impact test on a flexible cable conduit manufactured using the polypropylene resin composition of Examples and Comparative Example 5. FIG.

[How to measure]

(1) Flexural modulus: The injection specimens were measured at 23 DEG C and 50% relative humidity according to ASTM evaluation method D790.

(2) IZOD impact strength: Notched injection specimens were measured at 23 DEG C and -10 DEG C, 50% relative humidity according to ASTM Evaluation Method D256.

(3) Dupont: According to the self-evaluation method, the molded product of the injection sheet of 2T thickness was allowed to stand in a -10 ° C refrigerator for 4 hours and the impact strength was measured.

(4) Shrinkage (MD direction): The tensile test specimen prepared in accordance with ASTM D638 was measured through a microscope.

(5) Heat distortion temperature: The injection specimen was measured at a load of 4.6 kg · f according to ASTM evaluation method D638.

(6) Low Temperature Impact Test (CD tube molded article): The molded article was allowed to stand in a refrigerator at -10 ° C for 1 day, and whether or not the molded article was broken by a hammer was visually confirmed.

Referring to Table 2, first, in Comparative Examples 2 to 4 in which a modifier was added to the impact block copolymer, the flexural modulus was 10,200 to 11,000 kg / cm 2 at 12,000 kg · f / f / cm < 2 >, but it can be confirmed that the IZOD impact strength (-10 DEG C) increased from 4.5 kg / cm / cm to 5.8 to 6.1 kg / cm / cm. The decrease in flexural modulus means a decrease in rigidity, which is the degree of rigidity, and the increase in IZOD impact strength (-10 ° C) means that the possibility of breakage and breakage of the molded article at low temperature impact is low.

In addition, as a result of conducting a low temperature impact test on the molded articles of Comparative Examples 1 and 2 for evaluating the suitability of the polypropylene resin composition for a flexible wire tube, Comparative Example 1 in which the modifier was not added was judged as not acceptable, In case of 2, it was found that it was accepted. However, in the case of Comparative Example 2, it may be used in the winter season, but it may become too dry during the summer due to a low flexural modulus, so that it may not be used for a flexible wire.

On the other hand, five kinds of nucleating agents were added to the impact block copolymer and the modifier (Examples and Comparative Examples 5 to 8) in order to solve the problem of being retreated due to the low flexural modulus of the summer season. As a result, the flexural modulus was 10,200 to 11,000 kg It can be seen that the IZOD impact strength (-10 ° C) is relatively decreased from 5.8 to 6.1 kg · cm / cm to 5.3 to 6.0 kg · cm / cm, which is increased from 11,300 to 12,500 kg · f / .

As a result of conducting a low-temperature impact test of the molded article on the polypropylene resin composition for the flexible wire tube according to the examples and the comparative example 5, it was found that the content of the nucleus zircis-endo- bicyclo [2,2,1] heptane- When the 3-dicarboxylic acid (C2) was used, it was judged as a failure in the low-temperature impact test as shown in Fig. 2, which is likely to be broken due to impact when used in winter. However, in the case of using the zinc-free zinc and calcium salt compound (C1) as shown in Fig. 1, it was confirmed that the IZOD impact strength (-10 ° C) Cm / cm or more, and it can be said that the use of a specific nucleating agent can satisfy the optimum low temperature impact strength. In addition, since the heat distortion temperature is increased by 20 ° C or more due to the use of a specific nucleating agent, the degree of resistance of the resin composition to heat is improved, and it is confirmed that it is very suitable as a polypropylene resin composition for a flexible wire tube requiring flame retardancy.

Test Example  2

In order to understand the reason why the IZOD impact strength (-10 DEG C) greatly decreased from 6.0 to 5.4 in Test Example 1 using the polypropylene resin composition according to the above Examples and Comparative Example 8, The shapes of the propylene-ethylene rubbers in the impact block copolymer in the molded article were confirmed by the following method, and the results are shown in Figs. 3 and 4, respectively.

[checking way]

According to the self-evaluation method, the 3T molded article was immersed in liquid nitrogen for 5 minutes, and then a hammer was used to obtain a cross-section. The ethylene-propylene rubber was dissolved in a normal hexane solvent and the size and dispersion of the ethylene- Respectively.

3 and 4, in the case of a polypropylene resin composition in which high-density polyethylene as a modifier and zinc-calcium salt compound as a nucleating agent are added to an impact block copolymer according to the present invention. (Example) Mu m, and it can be seen that the rubber is densely dispersed over the entire area (in the figure, the recessed portion represents the rubber). In the case of the polypropylene resin composition (Comparative Example 8) in which high-density polyethylene and nucleus zero talc were added to the impact block copolymer as a modifier, the size of the rubber was irregularly about 0.5 to 1.5 占 퐉 and the spacing of the rubber was wider It can be seen that the part where the nucleus is aggregated is also observed. From this, it can be seen that the cause of the influence on the IZOD impact strength (-10 ° C) is the uniformity and dispersion degree of the propylene-ethylene rubber size.

While the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, Such modifications and changes are to be considered as falling within the scope of the following claims.

Claims (8)

90 to 99% by weight of an impact block copolymer having an ethylene content of 8 to 12% by weight and a melt index of 0.2 to 1 g / 10 min (at 230 DEG C under a load of 2.16 kg) and a high density polyethylene having a density of 0.95 to 0.97 g / 0.05 to 1 part by weight of a nucleating agent composed of zinc and a calcium salt compound, 0.01 to 0.5 parts by weight of a phosphorus-based antioxidant, 0.01 to 0.5 parts by weight of a phenol-based antioxidant and 0.01 to 0.5 parts by weight of a neutralizing agent, including,
Wherein the IZOD impact strength (-10 占 폚) (ASTM evaluation method D256) is 6.0 kg 占 / m / cm or more and the heat distortion temperature (ASTM evaluation method D638) is 122 占 폚 or more. delete delete The method according to claim 1,
Wherein the phosphorus antioxidant is tris (2,4-di-t-butylphenyl) phosphite. The method according to claim 1,
Wherein the phenolic antioxidant is tetrakis [ethylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane. The method according to claim 1,
Wherein the neutralizing agent is calcium stearate. The method according to claim 1,
Wherein the resin composition has a flexural modulus (ASTM evaluation method D790) of 12,300 kgf / cm < 2 > or more. A flexible conduit made of the polypropylene resin composition of any one of claims 1, 4, 5, 6, and 7.

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