KR101501835B1 - Polypropylene resin composition having high impact resistance and stress whitening resistance - Google Patents

Abstract

The polypropylene resin composition excellent in whitening resistance and impact resistance according to the present invention comprises 75 to 95% by weight of an ethylene-propylene-alphaolefin random copolymer and 5 to 25% by weight of an ethylene-propylene block copolymer having an ethylene content of 20 to 50% %, And an intrinsic viscosity ratio of the ethylene-propylene-alphaolefin random copolymer to the ethylene-propylene block copolymer is 0.3 to 1. The ratio of the intrinsic viscosity to the ethylene- And exhibits excellent effects.

Description

TECHNICAL FIELD [0001] The present invention relates to a polypropylene resin composition having high whitening resistance and high impact resistance,

The polypropylene resin composition excellent in whitening resistance and impact resistance according to the present invention comprises 75 to 95% by weight of an ethylene-propylene-alphaolefin random copolymer and 5 to 25% by weight of an ethylene-propylene block copolymer having an ethylene content of 20 to 50% %, And an intrinsic viscosity ratio of the ethylene-propylene-alphaolefin random copolymer to the ethylene-propylene block copolymer is 0.3 to 1. The ratio of the intrinsic viscosity to the ethylene- And exhibits excellent effects.

In general, the polypropylene resin composition is lightweight and has excellent mechanical and mechanical properties at a low cost, and is widely used as a material for injection molding products. In recent years, the use of polypropylene products has been expanding from film packaging materials or small injection containers to large injection products such as automobile bumpers. In particular, products are made thinner to reduce weight due to product enlargement, There is a weak point that it is easily broken by impact, and a higher level of impact resistance is required with high rigidity. However, in the development of materials using polypropylene, the impact resistance and stiffness tend to be inversely proportional, and there is also a problem in that the bending property or the external whitening property due to external impact deteriorates in terms of molecular structure.

Since the polypropylene homopolymer is weak against impact, a method of adding an impact modifier to the polypropylene homopolymer is used in order to increase the impact resistance. The introduction of such an impact modifier has a disadvantage in that the rigidity is rapidly lowered as the content of the modifier is increased, and in particular, the rubber-elastic material is expensive and the production cost is increased. In addition, the rubber-elastic material effective for improving impact resistance has a high viscosity, so that the addition of the rubber-elastic material to the polypropylene has a disadvantage that the processability during injection molding is lowered and the whitening phenomenon due to the difference in shrinkage ratio between the composition and the modifying material occurs severely.

US Pat. Nos. 5,285,464, 4,734,459 and 5,272-744-6 / 77 disclose a method of adding styrene-ethylene-butylene-styrene (SEBS) rubber or blending high-density polyethylene, Rigidity and heat resistance are deteriorated.

An object of the present invention is to provide a polypropylene resin composition which solves the above problems and is excellent in whitening resistance and impact resistance.

To achieve the above object, the present invention provides a polypropylene random block copolymer comprising 75 to 95% by weight of an ethylene-propylene-alphaolefin random copolymer and 5 to 25% by weight of an ethylene-propylene block copolymer having an ethylene content of 20 to 50% ≪ / RTI >

Wherein the intrinsic viscosity ratio of the ethylene-propylene-alphaolefin random copolymer to the ethylene-propylene block copolymer is from 0.3 to 1. The present invention also provides a polypropylene resin composition.

According to a preferred feature of the present invention, the ethylene-propylene-alpha olefin random copolymer comprises 0.5 to 7% by weight of ethylene and 1 to 15% by weight of an alpha olefin having 4 to 5 carbon atoms.

According to a preferred feature of the present invention, the alpha olefin is butene.

According to a further preferred feature of the present invention, the polypropylene resin composition further comprises at least one additive selected from a nucleating agent, a colorant, an MI synergist, an antioxidant and a catalyst neutralizer.

According to a more preferred feature of the present invention, the nucleating agent is at least one selected from the group consisting of an organometallic nucleating agent, a sorbitol nucleating agent, and a non-toxic nucleating agent.

According to a further preferred feature of the present invention, the coloring agent is at least one selected from among titanium-based oxides.

According to an even more preferred feature of the present invention, the MI synergist is at least one selected from organic peroxides.

According to a further preferred feature of the present invention, the antioxidant is at least one selected from the group consisting of a phenolic antioxidant and a phosphite antioxidant.

According to a further preferred feature of the present invention, the catalyst neutralizing agent is at least one selected from an organic catalyst neutralizing agent and an inorganic catalyst neutralizing agent.

According to a still further preferred feature of the present invention, the polypropylene resin composition has a molten resin of 1 to 50 g / 10 min (230 DEG C / 2.16 kg).

Another aspect of the present invention relates to a process for the preparation of ethylene-propylene-alphaolefin random copolymers, comprising the first polymerization step of polymerizing an ethylene-propylene-alphaolefin random copolymer and the addition of ethylene and propylene in the presence of the ethylene- And a second polymerization step of polymerizing the ethylene-propylene block copolymer to obtain a polypropylene resin composition.

According to a preferred feature of the present invention, the method further comprises a mixing step of adding and mixing at least one additive selected from a nucleating agent, a colorant, an MI enhancer, an antioxidant and a catalyst neutralizer after the second polymerization step.

According to a further preferred feature of the present invention, the first polymerization step and the second polymerization step are gas phase polymerization or bulk polymerization.

INDUSTRIAL APPLICABILITY The polypropylene resin composition excellent in whitening resistance and impact resistance according to the present invention has excellent whitening resistance and impact resistance and is excellent in providing a polypropylene resin composition which can be applied to various molded articles such as automobile interior / Effect.

Hereinafter, preferred embodiments of the present invention and physical properties of the respective components will be described in detail with reference to the accompanying drawings. However, the present invention is not limited thereto, And this does not mean that the technical idea and scope of the present invention are limited.

The polypropylene resin composition excellent in whitening resistance and impact resistance according to the present invention comprises 75 to 95% by weight of an ethylene-propylene-alphaolefin random copolymer and 5 to 25% by weight of an ethylene-propylene block copolymer having an ethylene content of 20 to 50% %, And the intrinsic viscosity ratio of the ethylene-propylene-alpha olefin random copolymer to the above-mentioned ethylene-propylene block copolymer is 0.3 to 1.

1. Polypropylene random block copolymer

The above-mentioned polypropylene random block copolymer is preferably 75 to 95% by weight of the ethylene-propylene-alphaolefin random copolymer and 5 to 25% by weight of the ethylene-propylene block copolymer. The ethylene- When the random copolymer is less than 75% by weight, the stiffness is deteriorated. If the random copolymer is more than 95% by weight, the impact resistance is decreased. When the random copolymer is less than 5% by weight, If it exceeds, rigidity decreases.

The polypropylene random block copolymer preferably has an intrinsic viscosity ratio of 0.3 to 1 in the ethylene-propylene-alphaolefin random copolymer to the ethylene-propylene block copolymer. When the ethylene-propylene random copolymer is less than 0.3, The molecular weight is relatively lower than that of the ethylene-propylene-alpha olefin random copolymer, which makes it difficult to absorb the impact. When the molecular weight exceeds 1, the size of the dispersed phase of the ethylene-propylene block copolymer increases and the whitening resistance may be lowered.

The above-mentioned ethylene-propylene-alpha olefin random copolymer comprises 0.5 to 7% by weight of ethylene and 1 to 15% by weight of an alpha-olefin having 4 to 5 carbon atoms and improves mechanical stiffness and heat resistance of the polypropylene resin composition, It plays an effective role in maintaining Mars. The ethylene content is preferably from 0.5 to 5% by weight, more preferably from 1 to 3% by weight. When the content is less than 0.5% by weight, the whitening resistance is deteriorated. When the content is more than 7% by weight, .

The above-mentioned alpha olefins refer to any alpha olefin except ethylene and propylene, preferably butene. When the number of carbon atoms is less than 4 or more than 5, the reactivity of the alpha-olefin with the comonomer is low during the production of the random copolymer, making it difficult to produce the copolymer. Further, it may contain 1 to 15% by weight, preferably 1 to 10% by weight, and more preferably 3 to 9% by weight of the above-mentioned alpha olefin. If the amount of the above-mentioned alpha-olefin is less than 1 wt%, the degree of crystallization becomes higher than necessary and the transparency lowers. When the amount of the alpha-olefin exceeds 15 wt%, the crystallinity and rigidity are lowered and the heat resistance is remarkably lowered.

The above-mentioned ethylene-propylene block copolymer contains 20 to 50% by weight of ethylene, and imparts impact resistance to the polypropylene resin composition and enables finely dispersing, thereby imparting both whitening resistance and transparency. The ethylene content may preferably be 20 to 40% by weight, and if it is less than 20% by weight, the impact resistance is deteriorated. If it exceeds 50% by weight, the impact resistance and whitening resistance may be deteriorated.

2. Additives

The above-mentioned polypropylene resin composition preferably further comprises at least one additive selected from a nucleating agent, a colorant, an MI synergist, an antioxidant and a catalyst neutralizer.

If the amount of the nucleating agent is less than 0.07% by weight, the nucleophilic nucleating agent becomes insufficient and the rigidity, heat resistance and transparency of the nucleating agent become insufficient. When the amount of the nucleating agent exceeds 0.5% by weight, . ≪ / RTI >

More specifically, the above-mentioned nucleating agent is an organometallic nucleating agent such as aluminum paracetylbutylbenzoic acid, sodium benzoic acid, calcium benzoic acid, etc., benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, 3,4-dimethylbenzylidene Sorbitol-based nucleating agents such as sorbitol and the like, and nonitol-based nucleating agents such as 1,2,3-trideoxy-4,6: 5,7-bis-O - [(4-propylphenyl) methylene] It may be at least one selected.

The above-mentioned coloring agent is preferably contained in an amount of 0.01 to 1% by weight, and if it is less than 0.01% by weight, it is difficult to ensure the coloring property of the resin composition, and if it exceeds 1% by weight, economical efficiency of the resin composition may be lowered. More specifically, the above-mentioned colorant may be at least one selected from the group consisting of titanium-based oxides such as titanium and dioxide.

It is preferable that the above-mentioned MI (Melt Index) elevating agent is contained in an amount of 0.003 to 0.08% by weight, and if it is less than 0.003% by weight, the dispersibility in the resin is inferior and the MI synergistic effect is lowered. The intrinsic viscosity ratio of the block copolymer increases, the transparency may be lowered due to an increase in the dispersed phase size of the ethylene-propylene block copolymer after molding, and the impact resistance may be lowered due to an increase in crystallinity. More specifically, at least one selected from the group consisting of organic peroxides such as bis (t-butylperoxyisopropyl) benzene and the like can be used as the above-mentioned MI-elevating agent.

The antioxidant preferably contains 0.1 to 0.5% by weight, and if it is less than 0.1% by weight, it is difficult to secure the stability of the resin composition by oxidation. When the amount of the antioxidant exceeds 0.5% by weight, Economy can be lowered. More specifically, The aforementioned antioxidants include tetrakis (methylene (3,5-di-t-butyl-4-hydroxy) hydrosilylate) and 1,3,5-trimethyl-tris (3,5- Phenoxy antioxidants such as 4-hydroxybenzene) and phosphite antioxidants such as tris (2,4-di-t-butylphenol) phosphite and the like.

It is preferable that the catalyst neutralizing agent is contained in an amount of 0.01 to 0.5% by weight, and if it is less than 0.01% by weight, the remaining catalyst can not be sufficiently neutralized. If the amount exceeds 0.5% by weight, The elution and economical efficiency of the resin composition may be lowered. More specifically, the above-mentioned catalyst neutralizing agent is at least one selected from an organic catalyst neutralizing agent and an inorganic catalyst neutralizing agent, and is preferably calcium stearate or hydrotalcite.

The polypropylene resin composition excellent in whitening resistance and impact resistance according to the present invention can contain pigments, dispersants, endurance agents, antistatic agents, UV stabilizers, antistatic agents, antistatic agents, Slip agents, anti-blocking agents, and talc.

The polypropylene resin composition having excellent whitening resistance and impact resistance according to the present invention preferably has a melt index of 1 to 50 g / 10 min (230 캜 / 2.16 kg), and if it is less than 1 g / 10 min, And the above-mentioned intrinsic viscosity ratio of 0.3 to 1 is difficult to maintain. If it exceeds 50 g / 10 min, the molecular weight is lowered and the impact resistance characteristic may be deteriorated.

3. Preparation of polypropylene resin composition

The polypropylene resin composition according to the present invention comprises a first polymerization step of polymerizing the ethylene-propylene-alphaolefin random copolymer and a second polymerization step of polymerizing the ethylene and the propylene-alpha olefin random copolymer in the presence of the ethylene- And a second polymerization step of polymerizing the ethylene-propylene block copolymer by additionally introducing propylene.

Further, the polypropylene resin composition according to the present invention preferably further comprises a mixing step of adding and mixing at least one additive selected from a nucleating agent, a colorant, an MI synergist, an antioxidant and a catalyst neutralizing agent after the second polymerization step .

(a) a first polymerization step

It is preferable to prepare an ethylene-propylene-alpha olefin random copolymer by simultaneously introducing ethylene, propylene and alpha olefin in the presence of a catalyst and performing virtual polymerization or bulk polymerization. The catalyst may be a catalyst prepared by reacting a dialkoxymagnesium carrier with a titanium compound and a phthalate internal electron donor. The catalyst may be an organoaluminum compound and an external A catalyst containing an electron donor may further be used.

(b) a second polymerization step

It is preferable to add ethylene and propylene in the presence of the ethylene-propylene-alpha olefin random copolymer prepared through the above-mentioned first polymerization step and to conduct the virtual polymerization or the bulk polymerization to prepare an ethylene-propylene block copolymer, 1 The same catalyst as the catalyst used in the polymerization step can be used.

(c) mixing step

The step of adding and mixing the additives after the second polymerization step described above is conducted by stirring for 1 to 30 minutes and then melting and kneading at 180 to 230 ° C using a rolling mill or an extruder to produce a polypropylene resin composition .

The molded article manufactured from the polypropylene resin composition according to the present invention may be manufactured by molding by extrusion, blow molding, film molding, injection molding, vacuum molding or the like, but is not limited thereto, and may be applied to automobile interior / exterior materials, Refrigerated / frozen food storage products, transparent sheets, food and beverage storage, and the like.

Hereinafter, physical properties of a polypropylene resin composition having excellent whitening resistance and impact resistance according to the present invention will be described with reference to examples.

≪ Example 1 >

(a) a first polymerization step

Propylene and 1-butene are simultaneously injected in the presence of a catalyst prepared by reacting a dialkoxy magnesium carrier with a titanium compound and a phthalate-based internal electron donor, and the bulk polymerization is carried out. The ethylene content in the resulting copolymer is 2% by weight Butene was 6% by weight to prepare an ethylene-propylene-butene random copolymer.

(b) a second polymerization step

Ethylene and propylene were further added in the presence of the ethylene-propylene-butene random copolymer prepared through the first polymerization step to prepare an ethylene-propylene block copolymer having an ethylene content of 32% by weight. The ethylene- Propylene random block copolymer was prepared by adjusting the amount of polymerization such that 88 wt% of the butene random copolymer and 12 wt% of the ethylene-propylene block copolymer had an intrinsic viscosity ratio of 0.85.

(c) mixing step

0.2 wt% of a nucleating agent (NX8000, MILLIKEN), 0.1 wt% of a phenolic antioxidant (SONGNOX1010, Songwon Industry), a phosphate-based antioxidant (SONGNOX 168, manufactured by Songwon Industrial Co., ), 0.05% by weight of calcium stearate and 0.05% by weight of titanium dioxide, and melt-mixed at 220 캜 using a twin-screw extruder and pelletized to prepare a polypropylene resin composition.

≪ Examples 2 to 7 >

The contents of the respective components are shown in Table 1 below. (However, the MI enhancer used was PK010 (POLYMODIFIER), and the melt flow rate before addition of the MI enhancer was 4 to 5 g / min.)

division Component (% by weight) Example One 2 3 4 5 6 7 The first polymerization step Propylene 92 93 89.5 91 93 90.5 92 Ethylene 2 2.5 1.5 2 2.5 1.5 2 Butene 6 4.5 9 7 4.5 8 6 Second polymerization step Propylene 68 63 69 60 63 68 68 Ethylene 32 37 31 40 37 32 32 Ethylene-propylene-butene random copolymer 88 89 89 88 89 88 88 Ethylene-propylene block copolymer 12 11 11 12 11 12 12 Intrinsic viscosity ratio 0.85 0.9 0.9 0.8 0.9 0.8 0.85 mix
step Nucleating agent 0.2 0.2 0.2 0.2 0.2 0.05 - Phenolic antioxidant 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Phosphate-based antioxidant 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Catalyst neutralizer 0.05 0.05 0.05 0.05 0.05 0.05 0.05 MI elevator - - 0.01 0.04 0.1 0.01 - Colorant 0.05 0.05 0.05 0.01 0.05 0.05 - Melt Index 12 13 13 32 70 12 5

≪ Comparative Examples 1 to 4 >

The contents of the respective components are shown in Table 2 below.

division Component (% by weight) Comparative Example One 2 3 4 The first polymerization step Propylene 100 91 92 91.5 Ethylene 0 2 2 1.5 Butene 0 7 6 7 Second polymerization step Propylene 70 61 31 59 Ethylene 30 39 69 41 Propylene random copolymer 88 - - - Ethylene-propylene-butene random copolymer - 87.5 89 89 Ethylene-propylene block copolymer 12 12.5 11 11 Intrinsic viscosity ratio 0.95 2.4 0.85 0.1 mix
step Nucleating agent 0.2 0.2 0.2 0.2 Phenolic antioxidant 0.1 0.1 0.1 0.1 Phosphate-based antioxidant 0.1 0.1 0.1 0.1 Catalyst neutralizer 0.05 0.05 0.05 0.05 MI elevator 0 0 0 0 Colorant 0.05 0.05 0.05 0.05 Melt Index 15 13 14 13

<Test Example>

A sheet having a width of 120 mm x 120 mm x 2 mm thick was produced using the polypropylene resin composition prepared in Examples 1 to 7 and Comparative Examples 1 to 4, The Izod impact strength was measured and the results are shown in Table 3 below.

In each of Examples 1 to 7 and Comparative Examples 1 to 4, measurement / evaluation items of physical properties and measurement methods thereof are as follows.

(1) Ethylene content: Ethylene content was measured using a characteristic peak at 720, 740 cm &lt; -1 &gt; using an infrared absorption spectrum (FT-IR).

(2) Butene content: The content of butene was measured using an infrared absorption spectrum (FT-IR) using a characteristic peak of 771 cm &lt; -1 &gt;.

(3) Intrinsic viscosity ratio: The intrinsic viscosity was measured using a viscosity meter under a decalin solution at 135 캜. The solvent extract of the ethylene-propylene block copolymer shows the components solubilized at 150 ° C using a xylene solvent. The intrinsic viscosity ratio was calculated as follows.

(Intrinsic viscosity ratio of ethylene-propylene block copolymer / ethylene-propylene-alpha olefin-containing random copolymer)

(4) Melt index: Measured under a load of 2.16 kg at 230 캜 according to ASTM D1238.

(5) Notch Izod impact strength: Measured according to ASTM D256.

(6) Surface Impact Strength: A falling weight impact (J) was measured at 23 ° C and 0 ° C using Gardner type impactor of 2 mm thick injection sheet specimen according to ASTM D5420.

(7) The degree of occurrence of whitening (impact whitening): 100 kg × 100 mm × 2 mm A weight of 5 kg (25 mm in diameter) was dropped on a sheet at a height of 20 cm and impacted. mm) were measured and recorded.

Evaluation items Example Comparative Example One 2 3 4 5 6 7 One 2 3 4 Degree of whitening 3 4 3 8 5 6 14 19 17 16 6 Izod impact strength (23 ° C) 13 12 14 9 6 12 16 11 10 11 8 Izod impact strength (0 ° C) 8 7 8 5 4 7 8 6 5 6 5 Surface impact strength (23 ℃) 22 23 22 21 14 21 22 20 16 18 14 Surface Impact Strength (0 ℃) 21 22 22 20 3 20 21 15 11 14 10

As shown in Table 3, the whitening resistance or the impact strength was lowered in Comparative Examples 2 and 4 in which the intrinsic viscosity ratio was more than 1 or less than 0.3, and in Comparative Example 3 in which the ethylene content was exceeded, the whitening resistance was remarkably decreased .

In the case of Example 7 which did not contain a nucleating agent and a coloring agent, the impact strength was improved but the whitening resistance deteriorated.

On the other hand, in Examples 1 to 6, whitening resistance and impact strength were improved as compared with Comparative Examples 1 to 4.

Therefore, the polypropylene resin composition excellent in whitening resistance and impact resistance according to the present invention is excellent in whitening resistance and impact resistance, and can be applied to various molded articles such as automobile interior / exterior materials and food packaging containers. And exhibits an excellent effect.

Claims (16)

A polypropylene random block copolymer comprising 75 to 95% by weight of an ethylene-propylene-alphaolefin random copolymer and 5 to 25% by weight of an ethylene-propylene block copolymer having an ethylene content of 20 to 40% by weight,
Wherein the ethylene-propylene-alphaolefin random copolymer for the ethylene-propylene block copolymer has an intrinsic viscosity ratio of 0.3 to 1,
Wherein the polypropylene resin composition comprises 0.07 to 0.5% by weight of a nucleating agent, 0.1 to 1% by weight of a coloring agent and 0.03 to 0.08% by weight of an MI enhancer based on the total weight of the polypropylene resin composition.
The method according to claim 1,
Wherein the ethylene-propylene-alpha olefin random copolymer comprises 0.5 to 7% by weight of ethylene and 1 to 15% by weight of an alpha-olefin having 4 to 5 carbon atoms.
3. The method of claim 2,
Wherein the alpha olefin is butene.
The method according to claim 1,
Wherein the polypropylene resin composition further comprises at least one additive selected from an antioxidant and a catalyst neutralizer.
The method according to claim 1,
Wherein the nucleating agent is at least one selected from an organometallic nucleating agent, a sorbitol nucleating agent, and a non-nitric nucleating agent.
The method according to claim 1,
Wherein the coloring agent is at least one selected from the group consisting of titanium-based oxides.
delete delete delete The method according to claim 1,
Wherein the polypropylene resin composition has a molten resin of 1 to 50 g / 10 min (230 DEG C / 2.16 kg).
A first polymerization step of polymerizing the ethylene-propylene-alphaolefin random copolymer; And
And a second polymerization step of polymerizing the ethylene-propylene block copolymer by additionally introducing ethylene and propylene in the presence of the ethylene-propylene-alpha olefin random copolymer prepared through the first polymerization step,
And adding a nucleating agent and a coloring agent to the polypropylene resin composition after the second polymerization step, and mixing the polypropylene resin composition and the polypropylene resin composition,
Wherein the polypropylene resin composition is the polypropylene resin composition according to any one of claims 1 to 6 and 10.
delete 12. The method of claim 11,
Further comprising a mixing step of adding and mixing at least one additive selected from an MI enhancer, an antioxidant and a catalyst neutralizer after the second polymerization step.
12. The method of claim 11,
Wherein the first polymerization step and the second polymerization step are gas phase polymerization or bulk polymerization.
delete delete