KR20000061149A - A thermoplastic resin composition - Google Patents

Abstract

PURPOSE: A thermoplastic resin composition is provided that has an excellent non-luster, molding processability and rigidity, to produce a high-grade bottle or case when applied to a bottle or case of goods such as cosmetics. CONSTITUTION: The resin composition comprises a blend of polypropylene resin and high density of polyethylene resin, wherein the melting index ratio of the high density polyethylene resin to the polypropylene resin is at least 3. The composition contains also a nucleating agent or calcium carbonate. Specially, the resin composition comprises (A) 30 to 70 pts.wt. of polypropylene being a propylene homopolymer or a propylene-ethylene block copolymer having not more than 15% of ethylene; and (B) 70 to 30 pts.wt. of the high density polyethylene resin having a density of 0.94 to 0.97 g/cm¬2, wherein the melting index ratio of components (A) and (B) is at least 3.

Description

Thermoplastic resin composition

The present invention relates to a thermoplastic resin composition having excellent matte properties, and more particularly, in blending a polypropylene resin and a high density polyethylene resin, the ratio of the melt index of the high density polyethylene resin to the melt index of the polypropylene resin is determined. The present invention relates to a thermoplastic resin composition which is not only excellent in mattness but also excellent in moldability and rigidity by adjusting to 3 or more or by adding a nucleating agent or calcium carbonate to the composition.

Plastic containers are light and have excellent mechanical properties such as impact resistance, and are widely used in household goods containers such as cosmetics and shampoos, replacing glass containers. However, if the surface is glossy, there are problems such as eye fatigue, and in recent years, consumers prefer matte products as the containers with matte are regarded as luxury goods.

Therefore, in order to reduce glossiness of the container, a method of diffusely reflecting light incident on the surface by providing irregularities on the surface has been devised as a method of processing the cavity surface of the molding die. However, the expression of matte through this method did not express sufficient matteness due to problems such as insufficient transfer at the surface of the container during molding of plastics, limitation of mold fine irregularities, or surface irregularities disappeared by heat. Attempts have been made to blend polyethylene resins into propylene resins.

However, since these resins are incompatible with each other, a method of improving the compatibility while developing matteness has been developed.

That is, Japanese Laid-Open Patent Publication No. 4-82260 discloses a method of bleeding a high density polyethylene resin having a density of 0.94-0.97 g / cc in a propylene-ethylene block copolymer containing ethylene in an amount of 3 to 10% by weight. have. However, this method can effectively express the matte, but there is still a problem of compatibility, the polymer gel is formed when blending, and thus there is a problem that the appearance is poor and the mechanical properties are not satisfactory when forming the container.

In addition, in Korean Patent Publication No. 97-74852, 55 to 85% by weight of polypropylene resin and 5 to 15% by weight of polyethylene resin are used as compatibilizers in an amount of 10 to 30% by weight of ethylene propylene diene copolymer rubber (EPDM rubber). Although a blended method is disclosed, this method improves mechanical strength but does not significantly reduce gloss. Moreover, in order to provide matteness, the compatibilizer must be used in an excessive amount. In this case, there is a problem in that it is economically unreasonable to manufacture practical products such as household goods.

Further, after blending 40-90 wt% of polypropylene resin and 60-10 wt% of high density polyethylene resin having a density of 0.94-0.97 g / cm 3 in Korean Laid-Open Patent Publication No. 98-1728, 100 parts by weight of this resin composition A method of lowering glossiness using a composition in which a metallocene catalyst-based propylene copolymer is added in an amount of 0.1 to 20 parts by weight with respect to the outer layer and a polypropylene resin as an inner layer has been disclosed. There is a problem that a separate device such as an extruder is required.

Accordingly, the present inventors have conducted studies to solve the above problems, and when blending polypropylene resin and high density polyethylene resin, when the ratio of the melt index of these resin is 3 or more, sufficient matt effect is achieved. The present invention has been found to be capable of being expressed, and mechanical properties such as moldability and rigidity can be obtained at a satisfactory level.

Accordingly, it is an object of the present invention to provide a thermoplastic resin composition which is excellent in mattness and also excellent in moldability and rigidity.

The above and other objects of the present invention will become apparent from the following detailed description of the invention.

In order to achieve the above object, the thermoplastic resin composition according to the present invention includes (A) 30 to 70 parts by weight of polypropylene resin and (B) 70 to 30 weight of high density polyethylene resin having a density of 0.94 to 0.97 g / cm 3. And a ratio of the melt index of the component (A) to the melt index of the component (B).

The thermoplastic resin composition of the present invention is further characterized by containing (C) a nucleating agent in an amount of 1.0 parts by weight or less based on 100 parts by weight of the (A + B) resin composition in the composition (A + B).

The thermoplastic resin composition of the present invention further contains (D) calcium carbonate in the (A + B + C) composition in an amount of 10 parts by weight or less based on 100 parts by weight of the (A + B) resin composition. It is done.

The thermoplastic resin composition of the present invention is characterized by controlling the ratio of the melt index between polypropylene resin and high density polyethylene resin without the use of a compatibilizer such as EPDM rubber and ethylene-propylene rubber (EPR). Improves physical properties and matteness That is, when the ratio of the melt index between the polypropylene resin and the high-density polyethylene resin is 3 or less, the compatibility becomes poor and the matteness and mechanical properties are lowered.

In the thermoplastic resin composition of the present invention, the polypropylene-based resin (A) component may be a propylene homopolymer or an propylene-ethylene block copolymer having an ethylene content of 15% or less.

In the thermoplastic resin composition of the present invention, as the high density polyethylene resin as the component (B), a resin having a density of 0.94 to 0.97 g / cm 3 can be used.

The thermoplastic resin composition of the present invention further adds the (C) nucleating agent component to the (A + B) composition in an amount of 1.0 parts by weight or less based on 100 parts by weight of the (A + B) composition, thereby providing a matte finish and molding processability. Can be improved. That is, the addition of the nucleating agent causes irregularities on the surface of the resin and diffusely reflects light, thereby improving matteness and molding processability. The nucleating agent used in the present invention is not particularly limited and commercially available ones can be used.

The composition of the present invention may further add (D) calcium carbonate to the (A + B + C) composition in an amount of 10 parts by weight or less based on 100 parts by weight of the (A + B) composition. Calcium carbonate can also improve the low gloss by making irregularities on the surface.

The thermoplastic resin composition provided by the present invention has a density of 0.9-0.97 g / cm 3 and a melt index of 0.1-5.0 g / 10 min (230 ° C., 2.16 kgf), and is excellent in matteness, moldability, and rigidity. It can meet the needs of consumers seeking high-quality containers of cosmetics, hygiene products, and other household goods.

Hereinafter, the present invention will be described in more detail with reference to various examples.

The physical property evaluation method of the various compositions employ | adopted in the following Example and the comparative example was performed by the following test method.

(1) Melt index was measured by ASTM D-1238:

Test condition: 230 ℃, 2.16㎏f

(2) Density was measured by ASTM D-792 method.

(3) Yield stress was measured by ASTM D-638 method:

Specimen: I type specimen

Crosshead speed under test conditions: 50mm / min

(4) Flexural modulus was measured by ASTM D-790 method:

Specimen size: 12.7 × 127 × 6.4㎜

Crosshead speed under test conditions: 28 mm / min

(5) Glossiness was measured by ASTM D-523 method:

Test angle condition: 60 °

<Example 1>

First, the components (A) and (B) specified in Table 1 were mixed, and then mixed with a Henschel mixer for 3 minutes. The mixture was extruded at a temperature range of 190 to 250 ° C. by a twin screw extruder having a L / D of 30 and a diameter of 30 mm, and then cooled and solidified to obtain a pellet-like composition. After the obtained composition was prepared as a composite specimen through an injection machine, the density, melt index, yield stress and flexural modulus were measured according to the above-described methods, and the pellet-like composition was not surface-treated with a hollow molding machine having a diameter of 65 mm. The glossiness of the surface of the container was measured by molding into a container at 190 to 220 ° C. using a mold. The results are shown in Table 1.

<Examples 2-3>

Except for further adding (C) component in Example 1 to the content shown in Table 1 was carried out in the same manner as in Example 1, and measured various physical properties in accordance with the above-described methods. The results are shown in Table 1.

<Examples 4-5>

Except that the contents of Example 2 (A) and (B) was changed as described in Table 1 below, the same method as in Example 1 was carried out, and various physical properties were measured according to the above-described methods. The results are shown in Table 1.

<Example 6>

Except for using the high-density polyethylene having a melt index of 0.2g / 10 minutes (230 ℃, 2.16kgf) and a density of 0.95g / cm 3 as the component (B) in Example 2 in the same manner as in Example 1 Various physical properties were measured according to the methods described above. The results are shown in Table 1.

<Example 7>

In Example 2, a propylene-ethylene block copolymer having a melt index of 2.0 g / 10 min (230 ° C., 2.16 kgf) as the component (A) and an ethylene content of 4% was used, and the melt index as the component (B). Was performed in the same manner as in Example 1 except that a high density polyethylene having 0.2g / 10 min (230 ° C., 2.16 kgf) and a density of 0.95 g / cm 3 was used. Were measured. The results are shown in Table 1.

<Example 8>

Except for further adding (D) component in Example 2 was carried out in the same manner as in Example 1, it was measured in accordance with the various methods described above. The results are shown in Table 1.

<Comparative Example 1>

Example 2 was carried out in the same manner as in Example 1, except that component (B) was used as a high density polyethylene resin having the same melt index as component (A), and various physical properties were measured according to the methods described above. . The results are shown in Table 1.

<Comparative Examples 2-3>

Except that the content of (A) component and (B) component in Example 2 was changed as shown in Table 1, was carried out in the same manner as in Example 1, and various physical properties were measured according to the above-described methods. The results are shown in Table 1.

<Comparative Example 4>

Component (A) and component (B) were used in the kind and content shown in Table 1 below, and EPDM was further added thereto, followed by the same method as Example 1, and various physical properties were measured according to the above-described methods. . The results are shown in Table 1.

The thermoplastic resin composition according to the present invention improves the properties of matteness, formability, and stiffness by controlling the ratio of the melt index of these resins when blending polypropylene resin and polyethylene resin without using a compatibilizer. When the resin is used as a plastic container, the surface of the container can be improved at low cost.

Claims (7)

In the thermoplastic resin composition, (A) A homopolymer of propylene or a propylene-ethylene block copolymer having an ethylene content of 15% or less, 30 to 70 parts by weight of polypropylene; And (B) contains 70-30 parts by weight of high density polyethylene having a density of 0.94-0.97 g / cm 3, The ratio of the melt index of the component (A) and the melt index of the component (B) is 3 or more. The composition of claim 1, wherein the melt index of the resin composition is 0.1 to 5.0 g / 10 minutes (230 ° C.). The composition according to claim 1 or 2, further comprising (C) a nucleating agent in an amount of 1.0 parts by weight or less based on 100 parts by weight of the component (A + B). 4. The composition according to claim 3, further comprising (D) calcium carbonate in an amount of 10 parts by weight or less based on 100 parts by weight of the component (A + B). A plastic container made of the resin composition of claim 1. A plastic container made of the resin composition of claim 3. A plastic container made of the resin composition of claim 4.