KR20190064323A - Polyolefin compositions having excellent dimensional stability - Google Patents

Abstract

A polyolefin-based resin composition of the present invention comprises: 85 to 95 wt% of a first polyolefin having a density of 0.945 g/mL or more; 1 to 10 wt% of a second polyolefin having a density of 0.920 g/mL or less; 0.1 to 5 wt% of a master batch comprising a pigment comprising copper and a polyolefin resin; 0.1 to 1 wt% of an inorganic filler; and 0.1 to 1 wt% of a nucleating agent.

Description

[0001] POLYOLEFIN COMPOSITIONS HAVING EXCELLENT DIMENSIONAL STABILITY [0002]

The present invention relates to a polyolefin-based resin composition excellent in dimensional stability. More specifically, the present invention relates to a polyolefin-based resin composition excellent in dimensional stability such that distortion and distortion of a high-density polyethylene molded article using a pigment containing copper can be improved.

High density polyethylene is excellent in high fluidity, rigidity and chemical resistance, and is used to make various products through injection molding process. However, if the molding shrinkage rate is so high that it is difficult to control the dimensions, if the desired size of the product can not be made, there is a high possibility of failure in the final assembly stage. This phenomenon is attributed to the rapid crystallization rate and high crystallization of high-density polyethylene, which can not be said to be fundamentally a complete solution.

In the prior art, a method of adding an inorganic filler, a rubber elastomer, a nucleating agent and the like is used to correct a shrinkage ratio of a polymer, and a method of improving through the production of a mold considering shrinkage and a modification of a molding condition is used. However, in many cases, unpredictable problems arise due to the shape of a complicated structure, deviation in temperature, pressure, etc. in the mold, and there is a limit that the improvement effect by the molding condition change is limited. Particularly, in the case of polyethylene having a very high crystallization rate, it is more difficult to control it. Therefore, many inventions and articles for improving this characteristic have not been studied much.

Korean Patent No. 0952012 is a prior art.

It is an object of the present invention to provide a polyolefin-based resin composition improved in dimensional stability and deformation.

Another object of the present invention is to provide a polyolefin-based resin composition having not only dimensional stability but also excellent physical properties such as flexural modulus and impact strength.

It is still another object of the present invention to provide a polyolefin-based resin composition capable of improving the deformation and warpage of a large-sized (plate-like, rib-free structure) molded article which can be produced by using a copper-containing pigment.

One aspect of the present invention is a polyolefin composition comprising 85 to 95% by weight of a first polyolefin having a density of 0.945 g / mL or greater; 1 to 10% by weight of a second polyolefin having a density of 0.920 g / mL or less; 0.1 to 5% by weight of a master batch in which a pigment containing copper is dispersed; 0.1 to 1% by weight of an inorganic filler; And 0.1 to 1% by weight of a nucleating agent; To a polyolefin-based resin composition.

The first polyolefin may have a melt flow index of 1 to 50 dg / min.

The second polyolefin may have a melt flow index of 15 to 60 dg / min.

The second polyolefin may have a melt flow index that is three to five times greater than the melt flow index of the first polyolefin.

The second polyolefin may comprise at least one of linear low density polyethylene, ethylene- and alpha-olefin copolymers.

The inorganic filler may be of an anisotropic plate type.

The inorganic filler may include at least one of talc, calcium carbonate, barium sulfate, magnesium oxide, wollastonite, mica, silica, and whiskers.

The nucleating agent is selected from the group consisting of bis (3,4-dimethylbenzylidene) sorbitol, sodium benzoate, lithium benzoate, bis (4-tertiary-butyl-benzoate) aluminum hydroxide, dicarboxylate salts, A phosphoric acid salt, a phosphoric acid salt, a phosphoric acid salt, a phosphoric acid salt, a phosphoric acid salt, The weight ratio of the inorganic filler to the nucleating agent may be 1: 0.8 to 1.2.

Wherein the polyolefin resin composition has a shrinkage anisotropy according to the following formula 1 of not less than 1 and not more than 2.0, a flexural modulus measured according to ASTM D790 of not less than 8.000 kgf / cm2, an impact strength measured according to ASTM D256 of not less than 10 kgf / Or more.

[Formula 1]

Shrinkage Anisotropy = Shrinkage in MD / Shrinkage in TD

In the formula (1), the shrinkage ratio in the MD direction and the shrinkage ratio in the TD direction are values obtained by measuring the lengths of the injection specimen (70x140x2 mm) before and after leaving at 23 deg. C for 72 hours in MD and TD directions .

Disclosed is a polyolefin-based resin composition which is improved in dimensional stability and deformation, has not only dimensional stability but also excellent physical properties such as flexural modulus and impact strength, and can improve high-density polyethylene deformation that may occur using a copper- And has the effect of the invention provided.

1 is a photograph of a specimen prepared in Examples and Comparative Examples of the present invention.

Hereinafter, the present invention will be described in detail.

One aspect of the present invention is a polyolefin composition comprising 85 to 95% by weight of a first polyolefin having a density of 0.945 g / mL or greater; 1 to 10% by weight of a second polyolefin having a density of 0.920 g / mL or less; 0.1 to 5% by weight of a masterbatch comprising a pigment comprising copper and a polyolefin resin; 0.1 to 1% by weight of an inorganic filler; And 0.1 to 1% by weight of a nucleating agent; To a polyolefin-based resin composition.

(A) a first polyolefin having a density of 0.945 g / mL or more

The injection-molded high-density first polyolefin (A) having a density of 0.945 g / mL or more has a melt flow index (190 DEG C, 2.16 kg) of 1 to 50 dg / min, for example, 1 to 25 dg / min, Lt; RTI ID = 0.0 > dg / min. ≪ / RTI >

When the high density first polyolefin (A) having a density of 0.945 g / mL or more is used alone without the pigment, shrinkage anisotropy is not increased, but when the pigment is mixed with a pigment containing copper as a pigment, the shrinkage anisotropy is 2.0 or more So that the molded article is deformed or distorted. That is, when a high-density first polyolefin (A) is mixed with a pigment containing a copper component, the thermal conductivity of the polyolefin is changed, so that the shrinkage anisotropy becomes very large and a defective molding product may occur due to the addition of the pigment.

The present invention relates to a polyolefin composition comprising 85 to 95% by weight of a first polyolefin having a density of 0.945 g / mL or more; 1 to 10% by weight of a second polyolefin having a density of 0.920 g / mL or less; A masterbatch comprising a pigment comprising copper and a polyolefin resin; Inorganic filler; And a nucleating agent may be added to improve the dimensional stability of the composition.

The upper limit of the shrinkage anisotropy of the first polyolefin resin is not particularly limited, but may be 10 or less and 5 or less, for example.

The high-density extrusion first polyolefin (A) having a density of 0.945 g / mL or more may be contained in an amount of 85 to 95% by weight of the total composition.

(B) a second polyolefin having a density of 0.920 g / mL or less

The second polyolefin (B) may have a density of 0.920 g / mL or less, for example, 0.85 to 0.918 g / mL. Excellent dimensional stability can be secured in the above range.

The second polyolefin (B) may comprise at least one of linear low density polyethylene, ethylene-alpha-olefin copolymer.

The melt flow index (190 DEG C, 2.16 kg) of the second polyolefin (B) is 15 to 60 dg / min, for example, 20 to 35 dg / min Linear And may include low density polyethylene. Within this range, dimensional stability and deformation improvement effect are excellent.

In an embodiment, the melt index (L-MI) of the second polyolefin (B) is larger than the melt flow index (H-MI) of the polyolefin (A). For example, the melt flow index (L-MI) of the polyolefin (B) may be 3 to 5 times the melt flow index (H-MI) of the polyolefin (A). And can have better dimensional stability in the above range.

The second polyolefin (B) is 1 to 10% by weight, for example, 3 to 7% by weight based on 100% by weight of the total polyolefin-based resin composition. And has better dimensional stability in the above range.

(C) a master batch in which a pigment containing copper is dispersed

The pigments containing copper usually have a blue color and include copper oxide (CuO).

The pigment containing copper may cause deformation or warpage of the first polyolefin (A), but in the present invention, the use of the pigment (C) containing copper in the form of a master batch in which copper is dispersed can solve this problem It is.

The master batch in which the pigment containing (C) copper is dispersed may be one comprising the third polyolefin as the base resin. The third polyolefin resin may be a low density polyolefin having a density of 0.920 g / mL or less. In this case, the effect of solving the problem can be further improved.

The masterbatch may include a third polyolefin as a base resin in an amount of 70% by weight to 90% by weight, and the copper-containing pigment in an amount of 10% by weight to 30% by weight.

The third olefin resin may have a melt flow index of 1 to 10 g / min.

The master batch in which the pigment containing (C) copper is dispersed may be contained in an amount of 0.1 to 5% by weight based on 100% by weight of the total polyolefin resin composition. In an embodiment, the pigment (C) may be contained in an amount of 0.01 to 3% by weight based on the total polyolefin resin composition.

(D) Inorganic filler

The inorganic filler may be selected from the group consisting of talc, calcium carbonate, barium sulfate, magnesium oxide, wollastonite, mica, silica, whiskers, etc. These may be used alone or in combination of two or more.

In an embodiment, the inorganic filler may be anisotropic or isotropic, and having double anisotropy is advantageous in suppressing shrinkage in the longitudinal direction. In a preferred embodiment, the inorganic filler may include magnesium oxysulfate, glass fiber, talc, and the like.

The inorganic filler may be fibrous or sheet-like. The double fiber type filler not only suppresses shrinkage in the longitudinal direction due to the directional property but also has an advantage of increasing the stiffness.

In one embodiment, more excellent dimensional stability can be realized when the inorganic filler is anisotropic and plate-like.

The inorganic filler may be applied in an amount of 0.1 to 1% by weight, for example, 0.3 to 0.7% by weight, based on 100% by weight of the total polyolefin resin composition. And has excellent dimensional stability and modulus in the above range.

(E) Nucleating agent

When a pigment containing copper is applied to a high-density polyolefin, the thermal conductivity of the polyolefin is changed, resulting in a large shrinkage anisotropy and a problem of a molded product failure phenomenon. In the present invention, shrinkage anisotropy can be significantly improved by reducing the crystal size of the high-density first polyolefin by adding a nucleating agent.

Nucleating agents capable of decreasing the crystal size are bis (3,4-dimethylbenzylidene) sorbitol, sodium benzoate, lithium benzoate, bis (4-tertiary-butyl-benzoate) aluminum hydroxide, Substituted dibenzylidene sorbitols, phosphate ester salts, aluminum salts of carboxylic acids, and the like can be used. These may be used alone or in combination of two or more.

The nucleating agent may be applied in an amount of 0.1 to 1% by weight, for example, 0.3 to 0.7% by weight, based on 100% by weight of the total polyolefin-based resin composition. And has excellent dimensional stability and modulus in the above range.

The weight ratio of the inorganic filler to the nucleating agent may be 1: 0.8 to 1.2. And has a balance of excellent shrinkage anisotropy and mechanical properties in the above range.

Wherein the polyolefin resin composition has a shrinkage anisotropy represented by the following formula 1 of not less than 1 and not more than 2.0, a flexural modulus measured according to ASTM D790 of not less than 8.000 kgf / cm ² , an impact strength measured according to ASTM D256 of not less than 10 kgf / cm cm or more.

The shrinkage anisotropy is a value represented by a shrinkage ratio in the MD direction and the TD direction of the injection molded product, and is defined by the following equation (1).

[Formula 1]

Shrinkage Anisotropy = Shrinkage in MD / Shrinkage in TD

In the formula (1), the shrinkage ratio in the MD direction and the shrinkage ratio in the TD direction are values obtained by measuring the lengths of the injection specimen (70x140x2 mm) before and after leaving at 23 deg. C for 72 hours in MD and TD directions .

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example

Hereinafter, specifications of each component used in Examples and Comparative Examples are as follows.

(A) a polyolefin having a density of 0.945 g / mL or more: high density polyethylene: a melt index of 7 dg / min (190 DEG C, 2.16 kg), a density of 0.949 g / mL

(B) a polyolefin having a density of 0.920 g / mL or less:

(B1) Linear low density polyethylene: melt index 22 dg / min (190 占 폚, 2.16 kg), density 0.914 g / ml

(B2) Ethylene-alpha-olefin copolymer: melt index 30 dg / min (190 DEG C, 2.16 kg), density 0.870 g / mL

(C) Pigment master batch containing copper: Blue powdery phase Low density polyethylene containing 10% Cupric Oxide (melt index: 2.8 g / 10 min, density: 0.926 g / mL)

(C ') Pigment master batch without copper pigment: Green powder Low density polyethylene containing 10% Chromic Oxide (melt index: 2.8g / 10min, density: 0.926g / mL)

(D) Inorganic filler: MOS-HIGE (Fibrous magnesium oxysulfate) as an anisotropic filler, Ube Material Industries

(E) Nucleating agent: Hyperform HPN-20E, Milliken Chemical

Examples 1 to 2 and Comparative Examples 1 to 8

The respective components were physically mixed in the amounts as shown in Tables 1 and 2, and then physical properties and flatness specimens were obtained by using an injection molding machine. The warpage of the specimens prepared in Example 1, CONTROL 2 and Comparative Example 2 was compared, and a photograph of the specimen was shown in Fig. The properties of the prepared specimens were evaluated by the following physical property measuring methods, and the results are shown in Tables 1 to 2.

How to measure property

(1) Shrinkage anisotropy: Injection specimens of 70x140x2 mm were molded to measure the shrinkage in the MD and TD directions, and the specimens were stored in a thermostatic chamber for 72 hours or more. The measured values of MD and TD shrinkage were obtained by the following formula 1:

[Formula 1]

Shrinkage Anisotropy = MD / TD

In the formula (1), the shrinkage ratio in the MD direction and the shrinkage ratio in the TD direction are values obtained by measuring the lengths of the injection specimen (70x140x2 mm) before and after leaving at 23 deg. C for 72 hours in MD and TD directions .

(2) Flexural modulus (kgf / cm 2): Measured according to ASTM D 790. The specimen used was 127x12.7x6.4 mm in size and 28 mm / min in speed.

 (3) IZOD Impact Strength (kgf / cm.cm): Measured according to ASTM D 256, the measurement temperature was 23 ° C, and the specimen was 3 mm thick with a notch formed during injection molding.

Example 1 Example 2 Control 1 Control 2 (A) 92 94 100 98 (B1) 5 - - - (B2) - 3 - - (C) 2 2 - - (C ') - - - 2 (D) 0.5 0.5 - - (E) 0.5 0.5 - - Shrinkage anisotropy 1.7 1.6 1.2 1.2 Flexural modulus (kgf / cm2) 8,280 8,200 8,030 8,140 IZOD (kgf / cm · cm) 11 12 12 10

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 (A) 99 98 97 97 93 95 97 96 (B1) - - - - 5 - - - (B2) - - - - - 3 - - (C) One 2 2 2 2 2 2 2 (D) - - One - - - 0.5 One (E) - - - One - - 0.5 One Shrinkage anisotropy 2.4 2.8 2.4 2.3 2.5 2.6 1.9 1.9 Flexural modulus
(Kgf / cm2) 8,060 8,120 8,440 8,350 7,210 6,800 8,460 8,600 IZOD
(Kgf / cm · cm) 11 10 6 7 16 21 5 4

From the results shown in Table 1, it can be seen that the polyolefin-based resin composition of the present invention has low shrinkage anisotropy and excellent mechanical strength. In Comparative Example 1-8, when any one of the polyolefin, inorganic filler and nucleating agent having a density of 0.920 g / mL or less was omitted, it was confirmed that the shrinkage anisotropy greatly increased, or the flexural modulus or impact strength decreased.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be embodied in other specific forms without departing from the essential characteristics thereof. It is therefore to be understood that the embodiments described above are in all respects illustrative and not restrictive.

Claims (10)

85 to 95 wt% of a first polyolefin having a density of 0.945 g / mL or more;
1 to 10% by weight of a second polyolefin having a density of 0.920 g / mL or less;
0.1 to 5% by weight of a master batch in which a pigment containing copper is dispersed;
0.1 to 1% by weight of an inorganic filler; And
0.1 to 1% by weight of a nucleating agent;
And a polyolefin-based resin.
The polyolefin-based resin composition according to claim 1, wherein the first polyolefin is a high-density polyethylene having a melt flow index of 1 to 50 dg / min.
The polyolefin-based resin composition according to claim 1, wherein the second polyolefin is linear low-density polyethylene having a melt flow index of 15 to 60 dg / min.
The polyolefin-based resin composition according to claim 1, wherein the second polyolefin is linear low-density polyethylene whose melt flow index is a value which is three to five times larger than the melt flow index of the first polyolefin.
The polyolefin-based resin composition according to claim 1, wherein the second polyolefin comprises at least one of a linear low-density polyethylene, an ethylene- and an alpha-olefin copolymer.
The polyolefin-based resin composition according to claim 1, wherein the inorganic filler is an anisotropic sheet-like type.
The polyolefin-based resin composition according to claim 1, wherein the inorganic filler comprises at least one of talc, calcium carbonate, barium sulfate, magnesium oxide, wollastonite, mica, silica, and whiskers.
The method of claim 1, wherein the nucleating agent is selected from the group consisting of bis (3,4-dimethylbenzylidene) sorbitol, sodium benzoate, lithium benzoate, bis (4-tertiary- butyl-benzoate) aluminum hydroxide, Wherein the polyolefin resin composition is at least one of salts, substituted dibenzylidene sorbitols, phosphate ester salts and aluminum salts of carboxylic acids.
The polyolefin-based resin composition according to claim 1, wherein the weight ratio of the inorganic filler to the nucleating agent is 1: 0.8 to 1.2.
The polyolefin-based resin composition according to claim 1, wherein the polyolefin-based resin composition has a shrinkage anisotropy represented by the following formula (1)
The flexural modulus measured by ASTM D790 is not less than 8.000 kgf / cm ² ,
Wherein the impact strength measured by ASTM D256 is not less than 10 kgf / cm <
[Formula 1]
Shrinkage Anisotropy = Shrinkage in MD / Shrinkage in TD
In the formula (1), the shrinkage ratio in the MD direction and the shrinkage ratio in the TD direction are values obtained by measuring the lengths of the injection specimen (70x140x2 mm) before and after leaving at 23 deg. C for 72 hours in MD and TD directions .

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