JP2018016683A - Polypropylene resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene resin composition which can produce a molded article excellent in scratch resistance (initially and after heating) and impact resistance.SOLUTION: A polypropylene resin composition contains component (A), component (B) and component (C), has a content of the component (A) of 70-90 pts.mass, a content of the component (B) of 10-30 pts.mass and a content of the component (C) of 1-5 pts.mass when the total of the content of the component (A) and the content of the component (B) is 100 pts.mass. The component (A) is polypropylene; the component (B) is talc having an average particle size of 1 μm to 8 μm; and the component (C) is polyethylene glycol, in which a molecular weight at the maximum point of the refractive index strength in a chromatogram obtained using a differential refractive index meter in gel permeation chromatography is 15,000-25,000, and when a peak area from an elution start point to an elution time corresponding to the refractive index strength maximum point is represented by Sand a peak area from an elution time corresponding to the refractive index strength maximum point to an elution end point is represented by S, S/Sis 2.0-3.0.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polypropylene resin composition capable of producing a molded article having excellent scratch resistance and impact resistance.

  Conventionally, polyvinyl chloride has been the mainstream material for interior parts such as automobile instrument panels and door trims. However, from the viewpoint of excellent formability, light weight, recyclability, and economic efficiency, an alternative to a polypropylene composite material containing talc is progressing. However, this polypropylene composite material is susceptible to material destruction starting from talc and has the disadvantages of being inferior in scratch resistance and impact resistance compared to polyvinyl chloride.

  Scratches attached to polypropylene composites containing talc have the problem that the surface of the wound has fine irregularities due to material destruction starting from talc, causing light scattering and making the scratches white. In order to solve such problems, various methods have been proposed. For example, Patent Document 1 proposes a composition having improved scratch resistance by adding a fatty acid amide to a polypropylene composite containing talc. However, since fatty acid amide is relatively compatible with polypropylene, it is difficult to migrate to the surface of the molded product, and the effect of improving scratch resistance is insufficient. In addition, since fatty acid amides are highly volatile, there is a problem that scratch resistance is impaired when heated.

JP 2010-43252 A

  An object of the present invention is to provide a polypropylene resin composition capable of producing a molded article having excellent scratch resistance (initial and after heat resistance) and impact resistance.

The polypropylene resin composition according to the present invention contains the following component (A), component (B) and component (C), and the total of the content of component (A) and the content of component (B) is 100 mass. Part (A) content is 70 to 90 parts by mass, component (B) content is 10 to 30 parts by mass, and component (C) content is 1 to 5 parts by mass. It is characterized by being.

(A) Polypropylene (B) Talc with an average particle diameter of 1 μm to 8 μm (C) Polyethylene glycol, which is the maximum refractive index intensity in a chromatogram obtained by gel permeation chromatography using a differential refractometer. the molecular weight of 15,000 to 25,000, the peak area up to the elution time corresponding to the refractive index intensity maxima from the elution starting point and S _1, elution end point from the elution time corresponding to the refractive index intensity maxima when the peak area up to the _{S 2, S 2} / _{S 1} is 2.0 to 3.0.

  According to the present invention, by blending a specific polyethylene glycol with a polypropylene blended with talc, the initial and post-heat-resistant lubricity of the surface of the molded article and the interfacial strength between the polypropylene and talc are improved, and scratch resistance is obtained. A polypropylene resin composition capable of producing a molded article excellent in impact resistance (initially and after heat resistance) can be provided.

FIG. 1 is a model chromatogram diagram for explaining peak areas S ₁ and S ₂ defined in the present invention.

Hereinafter, the present invention will be described in detail.
<(A) Polypropylene>
As the polypropylene (A) used in the present invention, homopolypropylene obtained by polymerizing propylene alone, random polypropylene obtained by copolymerizing propylene and ethylene, polymerized homopolypropylene, and then copolymerized propylene and ethylene in the presence of homopolypropylene. Block polypropylene. Among these, block polypropylene is particularly preferable from the viewpoint of impact resistance.

  Examples of the block polypropylene include Prime Polymer J708UG, J830HV, J715M, Sun Allomer PMA60Z, PMB60A, Nippon Polypro BC02N, BC03GS, and the like.

<(B) Talc>
The talc used in the present invention has an average particle diameter measured by a laser diffraction method in the range of 1 μm to 8 μm. When the average particle diameter is larger than 8 μm, the scratch resistance is deteriorated. When the average particle diameter is smaller than 1 μm, the cohesive force between talcs is large, causing poor dispersion in polypropylene, so that the scratch resistance is deteriorated.

<(C) Polyethylene glycol>
The polyethylene glycol used in the present invention has a molecular weight of 15,000 to 25,000 at the maximum refractive index intensity in a chromatogram obtained by gel permeation chromatography using a differential refractometer. .

Even if the peak area ratio S ₂ / S ₁ is 2.0 to 3.0, if the molecular weight of the polyethylene glycol is smaller than 15,000, the scratch resistance (after heat resistance) is lowered. In addition, it is difficult to produce polyethylene glycol having a molecular weight larger than 25,000, and even if the peak area ratio S ₂ / S ₁ is 2.0 to 3.0, the molecular weight is larger than 25,000. And scratch resistance (initial) is reduced. From this viewpoint, the molecular weight of polyethylene glycol is more preferably 20,000 or more.

Further, in the present invention, in the chromatogram eluted ends peak area up to the elution time corresponding to the refractive index intensity maxima from the elution starting point of the polyethylene glycol and S _1, from the elution time corresponding to the refractive index intensity maxima when the peak area of the point and the _{S 2, S 2} / _{S 1} is 2.0 to 3.0. Even if the molecular weight of polyethylene glycol is 15,000 to 25,000, if the peak area ratio S ₂ / S ₁ is larger than 3.0, the scratch resistance (after heat resistance) decreases, so S ₂ / S ₁ is 3.0 or less, preferably 2.7 or less, and more preferably 2.5 or less. Further, since polyethylene glycol having a molecular weight of 15,000 to 25,000 and a peak area ratio S ₂ / S ₁ smaller than 2.0 has reduced impact resistance, the peak area ratio S ₂ / S ₁ Is 2.0 or more, more preferably 2.1 or more.

Hereinafter, this requirement will be further described.
The peak area ratio (S ₂ / S ₁ ) is defined by a chromatogram obtained using a differential refractometer in gel permeation chromatography (GPC). This chromatogram is a graph showing the relationship between refractive index intensity and elution time.

  Here, FIG. 1 is a model diagram of a chromatogram obtained by gel permeation chromatography of polyethylene glycol, in which the horizontal axis indicates the elution time, and the vertical axis indicates the refractive index intensity obtained using a differential refractometer. .

  When a sample solution is injected into a gel permeation chromatograph and developed, elution starts from the molecule with the highest molecular weight, and the elution curve increases as the refractive index intensity increases. Thereafter, when the refractive index intensity maximum point K at which the refractive index intensity becomes maximum is passed, the elution curve descends.

  In the gel permeation chromatography, polyethylene glycol usually has one refractive index intensity maximum point in the chromatogram, and often has a unimodal peak. At this time, the peak due to the developing solvent used in the gel permeation chromatography and the pseudo peak due to the fluctuation of the baseline due to the column or apparatus used are excluded. In addition, when there are a plurality of refractive index intensity maximum points, the point having the maximum intensity is set as the maximum refractive index intensity point.

Here, the peak area from the elution starting point O to the elution time C corresponding to the refractive index intensity maxima K and S _1. The elution time C is at the intersection of the base line B and the perpendicular line P drawn from the refractive index intensity maximum point K to the base line B. Then, the peak area from the elution time C until dissolution end point E and S _2. Peak area S ₁ corresponds to the amount of components of relatively high molecular weight side, the peak area S ₂ corresponds to the amount of components of relatively low molecular weights. The fact that S 2 _/ S ₁ is 2.0 to 3.0, the components of the low molecular weight side than the component of the high molecular weight side, which means that considerably large, the molecular weight balance, polypropylene resin It contributes to the scratch resistance and impact resistance of the composition.

In the present invention, gel permeation chromatography (GPC) for determining the peak area ratio (S ₂ / S ₁ ) uses TOSOH HLC-8320GPC as a GPC system and two TOSOH TSKgel Super Multipores HZ-M as columns. And one TOSOH TSKgel Super H-RC. The column temperature is 40 ° C., the reference material is polystyrene, and tetrahydrofuran is used as the developing solvent. The developing solvent is flowed at a flow rate of 1 ml / min, 0.1 ml of a sample solution having a sample concentration of 0.1% by weight is injected, and is expressed in terms of refractive index intensity and elution time using the EcoSEC-Work Station GPC calculation program. Obtain a chromatogram.

(Ratio of each component)
In this invention, when the sum total of content of a component (A) and content of a component (B) is 100 mass parts, content of a component (A) is 70-90 mass parts, and a component (B) Is 10-30 parts by mass. When content of a component (B) (talc) exceeds 30 mass parts, the damage resistance and impact resistance of a resin composition will fall. Moreover, the impact resistance of a resin composition falls that content of a component (B) is less than 10 mass parts.

  (A) When the total of the content of polypropylene and the content of (B) talc is 100 parts by mass, the content of (C) polyethylene glycol is 1 to 5 parts by mass. This improves the scratch resistance (initial and after heat resistance) or impact resistance of the polypropylene resin composition. From this viewpoint, the content of (C) polyethylene glycol is more preferably 2 parts by mass or more, and further preferably 4 parts by mass or less.

<Other additives>
In the polypropylene resin composition of the present invention, other additives such as rubber, plasticizer, softener, antioxidant, processing aid, flame retardant, ultraviolet absorber, and colorant are added as long as the effect is not impaired. can do.

  The polypropylene resin composition of the present invention can be produced by melt-kneading (A) polypropylene, (B) talc, and (C) polyethylene glycol, and the kneading temperature is 180 to 260 ° C, preferably What is necessary is just to perform at 200-240 degreeC.

  For kneading (A) polypropylene, (B) talc, and (C) polyethylene glycol, a continuous extruder such as a single screw extruder, a twin screw extruder, or a twin screw rotor type extruder can be used. . The obtained polypropylene resin composition can be molded into a predetermined shape by known molding methods such as extrusion molding, injection molding, blow molding, and compression molding.

  The polypropylene resin composition of the present invention is excellent in scratch resistance (initial and after heat resistance) and impact resistance. Therefore, it can be used as a material for interior parts such as an automobile instrument panel and door trim.

Hereinafter, specific examples of the present invention will be described.
<Polypropylene resin composition>
Each component was dry blended with the composition shown in Tables 1 and 2, and kneaded and granulated at a set temperature of 230 ° C. with a twin screw extruder to obtain a polypropylene resin composition. The obtained polypropylene resin composition was injection molded with an injection molding machine at a cylinder temperature of 230 ° C. and a mold temperature of 30 ° C., and scratch resistance (initial and after heat resistance) and impact resistance were evaluated. Polypropylene J708UG made from prime polymer was used.

The evaluation method of each performance is as follows.
<Scratch resistance (initial)>
A test piece (80 mm × 55 mm × t2 mm) was scratched in a grid pattern by 20 pieces vertically and horizontally at intervals of 2 mm using a scratch tester 430P made by ERICHSEN under the conditions of a load of 5 N, a pin shape of 1 mmφ, and a scratching speed of 1,000 mm / min. Was attached. The lightness index L before and after the scratch of the test piece was measured under the conditions of light source C, visual field 10 °, and measurement surface φ30 mm with Nippon Denshoku SQ-2000, and the difference (ΔL) was calculated. This L is a value in the L ^* a ^* b ^* color space defined in JIS Z 8781-4.

<Scratch resistance (after heat resistance)>
After leaving the test piece (80 mm × 55 mm × t2 mm) in a gear oven set at 80 ° C. for 168 hours, the condition of load 5N, pin shape 1 mmφ, and scratching speed 1,000 mm / min was used with the scratch tester 430P manufactured by ERICHSEN. Then, scratches were made in a grid pattern at 20 mm length and width at intervals of 2 mm. The lightness index L before and after the scratch of the test piece was measured under the conditions of light source C, visual field 10 °, and measurement surface φ30 mm with Nippon Denshoku SQ-2000, and the difference (ΔL) was calculated. This L is a value in the L ^* a ^* b ^* color space defined in JIS Z 8781-4.

<Impact resistance>
In accordance with JIS K 7110, the Izod impact strength of the notched specimen was measured at 23 ° C.

  As is clear from the results in Table 1, Examples 1 to 9 were all excellent in scratch resistance (initial and after heat resistance) and impact resistance.

On the other hand, Comparative Examples 1 to 8 had an insufficient performance balance.
Specifically, Comparative Example 1 was inferior in scratch resistance (initial) and impact resistance due to excessive talc. Comparative Example 2 was inferior in impact resistance due to a small amount of talc. Comparative Example 3 was inferior in scratch resistance (initial) and impact resistance because the average particle diameter of talc was too small. Comparative Example 4 was inferior in scratch resistance (initial) because the average particle diameter of talc was excessive.

  Comparative Example 5 was inferior in scratch resistance (after heat resistance) because the molecular weight of polyethylene glycol was too small. Comparative Example 6 was inferior in scratch resistance (after heat resistance) because the peak area ratio in gel permeation chromatography of polyethylene glycol was excessive. Comparative Example 7 was inferior in scratch resistance (initial) and impact resistance because the blending amount of polyethylene glycol was too small. In Comparative Example 8, since the blending amount of polyethylene glycol was excessive, the impact resistance was inferior.

Claims (1)

When the following component (A), component (B) and component (C) are contained, and the total of the content of the component (A) and the content of the component (B) is 100 parts by mass, the component ( The content of A) is 70 to 90 parts by mass, the content of the component (B) is 10 to 30 parts by mass, and the content of the component (C) is 1 to 5 parts by mass. A polypropylene resin composition.

(A) Polypropylene (B) Talc with an average particle diameter of 1 μm to 8 μm (C) Polyethylene glycol, which is the maximum refractive index intensity in a chromatogram obtained by gel permeation chromatography using a differential refractometer. the molecular weight of 15,000 to 25,000, the peak area from the elution starting point to the elution time corresponding to the refractive index intensity maxima and S _1, from the elution time corresponding to the refractive index intensity maxima when the peak area to the elution end point was _{S 2, S 2} / _{S 1} is 2.0 to 3.0.

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