KR20240070178A - Highly transparent polypropylene resin composition for automobiles with excellent pressure resistance and impact resistance - Google Patents

Abstract

The present invention relates to a highly crystalline polypropylene resin composition with excellent pressure resistance properties, impact resistance, and transparency, and more specifically, (A) homopolypropylene with an isotactic pentad fraction of 95% or more and a molecular weight distribution of 7 to 12. 30 to 74% by weight of resin, (B) 20 to 64% by weight of ethylene-propylene random block copolymer having an absolute viscosity ratio of 0.8 to 1.2 with respect to the homo polypropylene resin, (C) alpha olefin copolymer 5 having 2 to 8 carbon atoms to 30% by weight, and (D) 0.05 to 1.0% by weight of a nucleating agent.

Description

Highly transparent polypropylene resin composition for automobiles with excellent pressure resistance and impact resistance {Omitted}

The present invention relates to a highly crystalline polypropylene resin composition with excellent pressure resistance properties, impact resistance, and transparency, and more specifically, to a highly crystalline polypropylene resin composition comprising homo polypropylene resin, ethylene-propylene random block copolymer, alpha olefin copolymer, and nucleating agent, for automotive use. It relates to a polypropylene resin composition suitable as a material for transparent storage containers.

In general, polypropylene resin has excellent mechanical properties, chemical resistance, and moldability, and is a material with a wide range of industrial uses, such as automobile interior parts, home appliance parts, and industrial materials. In general, homopolypropylene, which is a homopolymerization of propylene, has excellent rigidity, hardness, tensile strength, and heat resistance, but when used as a material for injection molded products for automobiles and general liquid storage, it has low impact strength, especially at low temperatures. There were many restrictions. In addition, when the thickness becomes thicker than 2 mm, transparency decreases, making it unsuitable for application as a see-through transparent container.

There are several methods to improve the impact properties of polypropylene, and the method of melting and mixing rubber materials such as EPM (ethylene propylene copolymer) or EPDM (ethylene propylene diene polymer) into polypropylene has been widely used. . However, in this case, the transparency is reduced due to the limited dispersibility between polypropylene and the rubber material, making application as a transparent storage container impossible.

To improve transparency, in Korean Patent Publication Nos. 2002-033562 and 2001-96295, a block copolymer of a vinyl aromatic hydrocarbon compound hydrogenated to polypropylene resin, styrene-ethylene-butylene-styrene (SEBS) block copolymer, styrene -Polypropylene resin compositions using ethylene-propylene-styrene (SEPS) block copolymers have been proposed, but these significantly reduce the crystallinity of polypropylene and do not exhibit sufficient rigidity to be molded into storage containers.

Meanwhile, there is a method of applying a hydrogenated nucleating agent to the block copolymer as a way to improve impact properties while maintaining a significant level of rigidity. These nucleating agent prescription techniques include adding an organic nucleating agent or using an inorganic filler, but there is a possibility that it may cause a relative decrease in other physical properties.

Republic of Korea Patent Publication No. 2002-033562

The present invention provides a polypropylene resin composition that has excellent pressure properties and impact resistance and is highly transparent, so that it can be applied as a material for transparent storage containers for automobiles.

The present invention is suitable as a material for transparent storage containers for automobiles, including homopolypropylene resin, ethylene-propylene random block copolymer, alpha olefin copolymer, and nucleating agent.

The present invention to achieve this objective is (A) 30 to 74% by weight of a homopolypropylene resin with an isotactic pentad fraction of 95% or more and a molecular weight distribution of 72, (B) an absolute polypropylene resin with respect to the homopolypropylene resin. A highly crystalline poly containing 20 to 64% by weight of an ethylene-propylene random block copolymer with a viscosity ratio of 0.8, (C) 5 to 30% by weight of an alpha olefin copolymer with 2* carbon atoms, and (D) 0.05 to 1.0% by weight of a nucleating agent. A propylene resin composition is provided.

According to the present invention, a highly crystalline polypropylene resin composition with excellent pressure resistance, impact resistance, and transparency is suitable for use as a material for transparent storage containers for automobiles.

Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention and drawings. These examples are merely presented as examples to explain the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples. .

Additionally, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains, and in case of conflict, this specification including definitions The description will take precedence.

In order to clearly explain the proposed invention in the drawings, parts unrelated to the description have been omitted, and similar reference numerals have been assigned to similar parts throughout the specification. And, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary. Additionally, “unit” as used in the specification refers to a unit or block that performs a specific function.

Identification codes (first, second, etc.) for each step are used for convenience of explanation. The identification codes do not describe the order of each step, and each step does not clearly state a specific order in context. It may be carried out differently from the order specified above. That is, each step may be performed in the same order as specified, may be performed substantially simultaneously, or may be performed in the opposite order.

Hereinafter, a detailed look at the high transparency polypropylene resin composition for automobiles with excellent pressure resistance characteristics and impact resistance is as follows.

(A) Homopolypropylene resin is highly stereoregular lipropylene, and has an isotactic pentad fraction of 95% or more, which is the stereoregularity index in Nuclear Magnetic Resonance, and gel permeation chromatography (GPC) method. It is a resin with a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw/Mn, hereinafter referred to as molecular weight distribution) of 7 to 12. If the pentad fraction is less than 95%, problems such as decreased rigidity and heat resistance occur. If the molecular weight distribution is less than 7, melt flowability deteriorates when a resin composition with the same melt index is manufactured, and if it exceeds 12, productivity decreases due to increased weighing time during injection molding. Meanwhile, the content of homopolypropylene resin is preferably 30 to 74% by weight. If the content is less than 30%, the rigidity and heat resistance required for use as a storage container cannot be developed, and if the content is more than 74%, the impact properties are relatively sharply reduced.

The ethylene-propylene random block copolymer, which is component (B) of the present invention, is a polymer made by copolymerizing ethylene and propylene after component (A) is made in a series of reactors, and has an intrinsic viscosity measured at 35°C. (A) Compared to the viscosity of component, it is at the level of 0.8 to 1.2. If the viscosity ratio is less than 0.8, the impact properties decrease rapidly, and if the viscosity ratio exceeds 1.2, transparency decreases. Meanwhile, the content of ethylene-propylene random block copolymer is preferably 20 to 64% by weight. If the content exceeds this range, the balance between rigidity/heat resistance and impact resistance according to the relative ratio with component (A) will be broken, and transparency will also be reduced.

The alpha olefin copolymer, which is component (C) of the present invention, is intended to develop transparency and impact resistance, and has an appropriate level of optical/thermodynamic compatibility with component (B), enabling dispersion at a fine level. Provides transparency. In the alpha-olefin copolymer that can be used as component (C), the carbon number of the alpha-olefin is in the range of 2 to 8, which is for developing impact resistance at low temperatures. The content of component (C) ranges from 5 to 30% by weight. If the content is less than 5% by weight, the effect of reinforcing impact properties and transparency is insufficient, and if it is more than 30% by weight, the relative balance of physical properties deteriorates, making it impossible to develop rigidity and heat resistance for storage containers.

The nucleating agent, which is component (D) used in the present invention, does not have any particular restrictions on its use, and both organic and inorganic nucleating agents can be used, and the amount used is preferably 0.05 to 1.0% by weight. Organometallic nucleating agents such as aluminum para-tertiary butyl benzoic acid, sodium benzoic acid, and calcium orthocid are more preferably 0.05 to 0.3% by weight, and inorganic nucleating agents such as talc are more preferably 0.1 to 1.0% by weight. At this time, in the case of talc, an average particle diameter of 1.0 ㎛ and a maximum particle diameter of 6.0 ㎛ or less are desirable. The content of this nucleating agent is effective in developing rigidity and heat resistance when applied within the above-mentioned range.

When applied below the minimum content, the effect is insufficient, and when applied above the maximum content, no further expression occurs.

In the polypropylene resin composition according to the present invention, various additives such as antioxidants, neutralizers, heat stabilizers, antistatic agents, weathering stabilizers, lubricants, slip agents, dispersants, and UV-stabilizers are added within the range that does not conflict with the characteristics of the present invention. It can be.

The method for producing the polypropylene resin composition of the present invention is preferably kneading using a twin-screw extruder, and mixing at a temperature higher than the melting point of polypropylene is also possible using processing conditions for producing a universally known polypropylene resin composition.

The present invention can be understood more specifically by the following examples, which are merely examples to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[Example]

The test conditions for each test material are as follows.

1) Stereoregularity (isotactic pentad fraction) C13-NMR was used to measure the isotactic fraction as a pentad unit in the polypropylene molecular chain.

2) Molecular weight distribution The ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) was measured by transmission chromatography (GPC).

3) Absolute viscosity of ethylene-propylene random block copolymer The non-copolymer was extracted with n-decane solution and then dissolved in Decaline at 135°C to measure the viscosity.

4) Pressure resistance characteristics

After applying external pressure directly to the injection molded storage container for automobiles for a certain period of time, the external condition and degree of deformation of the injection molded products were relatively compared and evaluated based on the following criteria:

(◎: Appearance condition and no deformation at all, ○: Appearance condition and almost no deformation, ×: Appearance condition and severe deformation due to lack of rigidity against external pressure).

Examples 1 to 3

With the ingredients and mixing ratios shown in Table 1 below, homopolypropylene, ethylene-propylene random block copolymer, alpha-olefin copolymer, and nucleating agent were dry blended with other additives using a Henschel mixer and then added to the hopper of the twin-screw kneading extruder. and melt-kneading to produce the same resin composition, then injected with Samsung Klöckner FCM-110 (mold force = 110 tons) to produce specimens specified in ASTM standards, and tested for pressure resistance, tensile strength, and elongation according to the above-described method. ,Impact strength, transparency, and flexural modulus were measured. However, the injection mold for evaluating the pressure resistance characteristics was injected using the automobile storage container mold as is. The results are shown together in Table 1.

Comparative Examples 1 to 3 Resins were prepared in the same manner as in Example 1, except that homopolypropylene, ethylene-propylene random block copolymer, alpha-olefin copolymer, nucleating agent, and other additives were used in the components and mixing ratios shown in Table 1 below. The composition was prepared, a specimen was made using it, and the pressure characteristics, tensile strength, elongation, impact strength, transparency, and flexural modulus were measured according to the method described above. However, the injection product for evaluating pressure resistance characteristics was injected using the automobile storage container mold as is. The results are shown in Table 1.

[Table 1]

From the above table, the following facts can be seen: Comparative Example 1 had similar impact properties and transparency compared to Example 1 using homopolypropylene with appropriate stereoregularity and molecular weight distribution, but had lower pressure characteristics due to lower rigidity. This was greatly inferior. Comparative Example 2, in which the alpha olefin copolymer was not applied, had significantly reduced impact properties compared to Examples 1 to 3. Comparative Example 3 was inferior in transparency and impact properties because the absolute viscosity ratio of the ethylene-propylene random block copolymer and homopolypropylene was too high compared to Example 2, and the pressure resistance was also inferior due to decreased rigidity due to non-prescription of the nucleating agent.

Claims (3)

(A) 30 to 74% by weight of homopolypropylene resin with an isotactic pentad fraction of 95% or more and a molecular weight distribution of 72, (B) ethylene-propylene random block aerial with an absolute viscosity ratio of 0.8 to the homopolypropylene resin. A highly crystalline polypropylene resin composition comprising 20 to 64% by weight of polymer, (C) 5 to 30% by weight of alpha olefin copolymer of 2 carbon atoms, and (D) 0.05 to 1.0% by weight of nucleating agent.
The highly crystalline polypropylene resin composition according to claim 1, wherein the nucleating agent (D) is talc with an average particle diameter of 1.0 ㎛ and a maximum particle diameter of 6.0 ㎛.
The highly crystalline polypropylene resin composition according to claim 1, wherein the nucleating agent (D) is a sorbitol-based organic nucleating agent.