KR100708315B1 - Polypropylene resin composition having good transparency and heat resistance - Google Patents

Abstract

The present invention relates to a polypropylene resin composition having excellent transparency and heat resistance, and more specifically, 0.15 to 0.4 parts by weight of a sorbitol-based nucleating agent is added to 100 parts by weight of a high stereoregular polypropylene resin. It is related with this excellent polypropylene resin composition.

Description

Polypropylene resin composition excellent in transparency and heat resistance {POLYPROPYLENE RESIN COMPOSITION HAVING GOOD TRANSPARENCY AND HEAT RESISTANCE}

The present invention relates to a polypropylene resin composition excellent in transparency and heat resistance, and more particularly, by adding a sorbitol-based nucleating agent to a high-stereoregular polypropylene resin, a resin composition having improved transparency and heat resistance as compared to a conventional polypropylene resin composition It is about.

Polypropylene resin is excellent in rigidity, chemical resistance, and moldability compared to other polyolefin-based materials, and thus has a wide industrial application range for automobile interior parts and home appliance parts. The reason why polypropylene resin is widely used as a polyolefin resin for injection molding is that polypropylene resin has superior rigidity, hardness, tensile strength, and heat resistance compared to polyethylene resin.

There are many techniques for increasing the rigidity and heat resistance of polypropylene resins for use in high temperature environments. In particular, in automobiles and electrical and electronic parts applications requiring high heat resistance, a method of reinforcing rigidity and heat resistance by incorporating an inorganic filler into a polypropylene resin has been proposed. In this regard, Japanese Patent Laid-Open Publication Nos. And 57-55952, etc., have disclosed a composition which improves mechanical properties by blending polypropylene with inorganic fillers and rubber, but there are problems such as poor appearance due to inorganic fillers and cost incurred due to an increase in specific gravity of materials. The methods make polypropylene resins opaque and therefore not suitable for transparent product applications.

In addition, when the inorganic filler is generally added, the flowability becomes poor even in the same flow index, thereby increasing the possibility of problems such as poor dispersion of pigments and unmolding of complex products.

In order to solve this disadvantage, European Patent No. 562119 and Japanese Patent Publication No. 5222078 have developed a resin composition which improves rigidity and heat resistance by adding a phosphorus-based nucleating agent to a polypropylene resin without filling inorganic materials. Genie has a disadvantage in that heat resistance is inferior to inorganic filled polypropylene due to its low heat resistance.

In order to increase the transparency of polypropylene, a propylene-ethylene random copolymer has been developed in which a certain amount of ethylene is added and copolymerized when propylene is polymerized. Korean Patent Publication No. 87-009914 is a technique for improving transparency by adding a benzylidene sorbitol-based nucleating agent to such a propylene-ethylene random copolymer. However, propylene-ethylene random copolymer has a disadvantage in that it is not applicable to the application of continuous high temperature, such as iron, coffee maker, microwave oven due to the poor heat resistance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-stereoregular polypropylene resin composition having excellent transparency and heat resistance that can be applied to heat-resistant electric and electronic parts and home appliances by being transparent and usable at high temperatures by improving the above problems. .

The polypropylene resin composition of the present invention is a polypropylene resin composition in which a sorbitol-based nucleating agent is added to a high stereoregular polypropylene resin.

The polypropylene resin used in the present invention is a high-stereoregular polypropylene having a wide molecular weight distribution. The molecular weight distribution is 7-12 by gel permeation chromatography (GPC) method, and the stereoregularity index of nuclear magnetic resonance method is the pentaad method. It is preferably 96% or more and the melt index (MI) is 5 to 30 g / 10 minutes (ASTM D1238, 230 ° C).

If the molecular weight distribution of the polypropylene is less than 7, the flowability is deteriorated, which may cause unmolding, poor surface appearance, and deterioration of transparency during injection molding of a product having a complicated shape such as a grill. In addition, if the flowability worsens, a large amount of pressure is left on the product when it is injected, and a lot of residual stress is left. When the product is used at a high temperature, warpage and distortion occur in the product. If the molecular weight distribution exceeds 12, the time for injection molding is too long to reduce the overall production speed, and the product contains a large amount of low molecular weight polypropylene resin. Hurt.

If the stereoregularity index is less than 96%, the heat resistance of the polypropylene resin is lowered. The higher the stereoregularity index, the higher the heat resistance and the higher the mechanical strength. Three-dimensional rules also have no special disadvantages due to the increased index.

If the melt index of polypropylene is less than 5g / 10min, the productivity decreases due to poor moldability during injection molding.However, if the melt index exceeds 30g / 10min, the impact strength is drastically lowered, making the product valuable. Degrades.

Sorbitol-based nucleating agents used in the present invention are derivatives based on sorbitol, and include benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, and 3,4-dimethylbenzylidene sorbitol, among which methylbenzylidene is particularly preferred. Sorbitol and 3,4-dimethylbenzylidene sorbitol are preferred.

The amount of sorbitol-based nucleating agent added is preferably 0.15 to 0.4 parts by weight based on 100 parts by weight of polypropylene resin, and when the content is less than 0.15 parts by weight, it is difficult to obtain sufficient transparency, and when it exceeds 0.4 parts by weight, transparency is no longer improved.

To the polypropylene resin composition of the present invention, various additives such as antioxidants, heat stabilizers, weather stabilizers, antistatic agents, lubricants, pigments, dyes, and the like may be added within a range not departing from the features of the present invention.

There is no restriction | limiting in particular in the method of manufacturing the polypropylene resin composition of this invention, The method of manufacturing the polypropylene resin composition generally known can be used. Each of the above components can be freely selected and mixed according to a desired order. Usually, by adding necessary amounts of the above components and other additives, a kneader such as a kneader, a roll, a short-barrier mixer and a single or twin screw extruder are used. A kneading method can be used.

The present invention can be understood in more detail by the following examples, the following examples are only examples for illustrating the present invention and are not intended to limit the protection scope of the present invention.

Examples and Comparative Examples

Put all the ingredients in Table 1 in the following PCM30 twin-screw kneading extruder and kneaded to prepare a polypropylene resin composition, and then injected into Samsung Kleukner FCM-110 (clamping force = 110 tons) specimens determined by ASTM standards Was prepared and its physical properties were measured. The results are shown in Table 1.

Test conditions for each test property are as follows.

1) Flow index

According to ASTM D1238, it measured at 2.16Kg load at 230 degreeC.

2) spiral flow

It was measured by the Samsung comprehensive chemical test method, the measurement conditions are as follows.

Injection molding machine → 110 tons (9.2oz)

Shape of injection channel → semicircle (cross section)

Feeding part temperature → 215 ℃

Cylinder and nozzle temperature → 235 ℃

Mold temperature → 50 ℃

Cooling time → 10 seconds

Injection speed → 15 mm / s

Injection pressure → 1000kg / ㎠

Measurement item → Measurement of the flow length of the spiral specimen injected under the above conditions

3) heat deflection temperature

It was measured under low load (4.6Kg) according to ASTM D648.

4) Haze

The transparency of the specimens was measured according to ASTM D1003. The lower the blur, the more transparent.

5) High temperature warpage evaluation

The resin composition was injected into a round disc shape having a diameter of 100 mm and a thickness of 1.7 mm to prepare a specimen, and then placed in an oven at 100 ° C. and 150 ° C. for 2 hours. This was again cooled to room temperature to evaluate the degree of warpage of the specimen. The degree of roughness was evaluated by placing the specimen on a flat table and measuring the height of the largest section from the table surface.

Example Comparative example One 2 One 2 3 Polypropylene 1 100 100 100 - - Polypropylene 2 - - - 100 100 Sorbitol Nucleating Agent 0.2 0.3 - 0.3 - Aluminum Nucleus - - - - 0.2 Properties Melt Index (g / 10min) 10 10 10 10 10 Spiral Flow (cm) 120 120 105 105 105 Heat Deflection Temperature (℃) 140 140 120 135 140 ¹⁾ Haze 30 25 70 25 60 ²⁾ High temperature warpage evaluation (120 ℃) O O × O O High temperature warpage evaluation (150 ℃) O O × × ×

¹⁾ Blur: The lower the blur, the more transparent.

²⁾ High temperature warpage evaluation: O Good (no warpage), x defect (warpage occurrence, 1 ~ 2mm)

Description of each component used in Examples and Comparative Examples of Table 1 is as follows.

1) Polypropylene 1: Highly crystalline polypropylene homopolymer with a melt index (MI) of 10 g / 10 min (230 ° C.), nuclear magnetic resonance pentaad method stereoregularity index of 97%, and molecular weight distribution of 8.0

2) Polypropylene 2: Polypropylene homopolymer with melt index (MI) of 10g / 10min (230 ° C), nuclear magnetic resonance method pentaad method stereoregularity index of 91%, molecular weight distribution of 5.5

3) Sorbitol-based nucleating agent: 3,4-dimethylbenzylidene sorbitol

4) Aluminum-based nucleating agent: aluminum hydroxydibutyl benzoate

As can be seen from the results of Table 1, Example 1 is excellent in transparency and excellent in high temperature warpage evaluation compared to Comparative Example 1 without using the sorbitol-based nucleating agent.

And Example 2 is excellent in flowability and heat distortion temperature compared to Comparative Example 2. In Comparative Example 2, since the flowability is poor, injection workability is inferior, and a large amount of pressure is applied when molding. Although the transparency of Example 2 and Comparative Example 2 was the same, Comparative Example 2 was distorted in the high temperature warpage evaluation. Therefore, the comparative example 2 is unsuitable for the use of the product used at high temperature.

In the case of Example 1 and Comparative Example 3, although the heat distortion temperature is the same, Example 1 is more transparent than Comparative Example 3 using an aluminum-based nucleating agent. Even in the same heat deflection temperature, Example 1 did not bend at high temperature while Comparative Example 3 exhibited warpage.

As can be seen from the above examples and comparative examples, the polypropylene resin composition prepared according to the present invention has excellent flowability and good heat resistance by using a high-stereoregular polypropylene resin having a wide molecular weight distribution, and is used at high temperatures. Even if it does not warp, it is suitable for applications requiring transparency in microwave ovens, coffee makers, irons, etc., where such performance is required.

Claims (2)

High stereoregularity with a melt index of 5 to 30 g / 10 minutes, molecular weight distribution measured by gel permeation chromatography (GPC) of 7 to 12, and a stereoregularity index of nuclear magnetic resonance method of 96% or more based on pentaad method A polypropylene resin composition comprising 0.15 to 0.4 parts by weight of sorbitol-based nucleating agent added to 100 parts by weight of polypropylene resin. The polypropylene resin composition according to claim 1, wherein the sorbitol-based nucleating agent is benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, or 3,4-dimethylbenzylidene sorbitol.