JP2596904B2 - Polyolefin resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin composition which is extremely suitable as a material for automobiles, home appliances, light electric appliances and the like, and more particularly to an excellent appearance (weld appearance, flow mark) and balance of physical properties. The present invention relates to a polyolefin-based resin composition which has good (balance between rigidity and impact resistance), excellent moldability, warps a molded article after molding, and has little material anisotropy.

[0002]

2. Description of the Related Art Talc has been widely used as an inorganic filler in a polyolefin resin composition. In other words, the polyolefin resin composite material using talc has good balance between rigidity and impact resistance, including good moldability,
Moreover, since the material has little anisotropy and is inexpensive, it is used in various fields mainly in the automobile field.

[0003] However, the polyolefin resin composite material using talc has a drawback that it is inferior in weld appearance, appearance performance such as flow mark, tapping characteristics and the like. Therefore, instead of talc, attempts have been made to solve these problems by using fine fibrous powders such as cubic calcium carbonate, milled fiber, and wollastonite. The anisotropy is large, and problems such as abrasion of a mold and a screw have arisen.

That is, among these inorganic fillers,
Calcium carbonate is generally used because it is inexpensive, has high whiteness and good appearance. However, the resin composition containing calcium carbonate has a rigidity,
It had disadvantages such as low mechanical properties such as strength and low heat resistance.

Therefore, the applicant of the present application has already proposed a resin composition which suppresses fiber breakage, makes use of the aspect ratio peculiar to the fibrous filler, and has an excellent balance between rigidity and impact resistance (Japanese Unexamined Patent Publication No. Hei. 319552). However, this method requires a special kneading method such as side-feeding the raw material, and furthermore, the resulting composition has a problem that warpage and material anisotropy are large.

In order to solve this problem, a method of blending a soft resin component such as ethylene propylene rubber or low-density polyethylene can be considered. However, there is a problem that the rigidity is reduced and the high aspect effect of the fiber is reduced by half. there were.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve such a problem, and as a result, as a raw material, high-crystalline polypropylene has been used as a basic resin, and if necessary, high-density polypropylene has been used. By combining calcium carbonate fiber with a specific fiber diameter and a low aspect ratio with a combination of polyethylene, the warpage and the anisotropy of the material are small, and the appearance (weld appearance, flow mark) is excellent, and the physical properties are balanced. It has been found that a composition having good balance between rigidity and impact resistance and excellent in moldability can be easily produced by a usual kneading method, and based on this finding, the present invention has been completed. Was.

That is, according to the present invention, (A) the melt index is 1 to 100 g / 10 min, and the ethylene content is 0.
50 to 99% by weight of a propylene polymer having an isotactic pentad fraction [I] of at least 92% by weight in a homopolymer part, and (B) a melt index of 1 g / 10. Polyolefin-based resin set comprising 1 to 50% by weight of calcium carbonate fiber having 0 to 25% by weight of high-density polyethylene (C) or more and (C) an average fiber diameter of 5 μm or less and an average aspect ratio of 3 to 25.
It provides a product.

The propylene polymer (A) used in the present invention has a melt index (MI) of 1 to 100 g / 10
Min, preferably 5 to 50 g / 10 min, particularly preferably 5 to 30 g / 10 min. Where M
If I is less than 1 g / 10 minutes, fiber breakage will proceed too much during kneading, and the calcium carbonate fiber will have an aspect ratio of 3 or less, and the required rigidity cannot be obtained. On the other hand, MI
If it exceeds 100 g / 10 minutes, the impact resistance becomes insufficient, which is not preferable.

The propylene polymer (A) used in the present invention has an ethylene content of 0 to 15% by weight, preferably 0 to 10% by weight. Here, if the ethylene content exceeds 15% by weight, the rigidity becomes insufficient, which is not preferable.

Further, the propylene polymer (A) used in the present invention has a homopolymer part having an isotactic pentad fraction [I] of at least 92% by weight, preferably 9% by weight.
It is at least 4% by weight, particularly preferably at least 95% by weight. Here, if the isotactic pentad fraction [I] of the homopolymer portion is less than 92% by weight, the resulting composition has low rigidity, which is not preferable.

Further, the blending amount of the propylene polymer is as follows:
50-99% by weight of the total composition , preferably 50-95
%, More preferably 60 to 90% by weight. Here, if the blending amount of the propylene-based polymer is less than 40% by weight, the moldability decreases and the specific gravity becomes high, which is not preferable. On the other hand, the blending amount of the propylene polymer is 99% by weight.
If it exceeds, the rigidity becomes insufficient, which is not preferable.

Next, the high density polyethylene (B) used in the present invention has an MI of 1 g / 10 min or more. Here, if the MI of the high-density polyethylene is less than 1 g / 10 minutes, the fiber breakage proceeds too much, the aspect ratio becomes 3 or less, and the moldability and the flow mark deteriorate. Further, the compounding amount of the high-density polyethylene is 0 to 25% by weight, preferably 0 to 20% by weight, more preferably 0 to 15% by weight of the whole composition. Here, when the compounding amount of the high-density polyethylene exceeds 25% by weight, rigidity,
Particularly, the high-temperature rigidity is deteriorated, and the moldability and the flow mark are deteriorated. In addition, by blending high-density polyethylene, the whitening resistance against scratching is improved and the impact resistance is also improved.

Further, the calcium carbonate fiber (C) used in the present invention is dispersed in the molded article when the molded article is formed, and has an average fiber diameter of 5 μm or less, preferably 3 μm or less, particularly preferably. Is 2 μm or less.
Here, if the average fiber diameter of the calcium carbonate fiber exceeds 5 μm, rigidity and impact resistance cannot be obtained.

Further, the calcium carbonate fiber has an average aspect ratio of 3 to 25, preferably 5 to 20, and more preferably 7 to 15. Here, if the average aspect ratio of the calcium carbonate fiber is less than 3, rigidity cannot be obtained. On the other hand, if the calcium carbonate fiber has a high aspect ratio such that the average aspect ratio exceeds 25, the molded product is warped, the impact resistance and the anisotropy of the material are deteriorated, and the side feed is deteriorated. And the like, which is not preferable because it requires high kneading.

The amount of such calcium carbonate fiber is 1 to 50% by weight, preferably 5 to 40% by weight of the whole composition.
%, More preferably 7 to 30% by weight. Here, if the amount of the calcium carbonate fiber is less than 1% by weight, rigidity cannot be obtained.
Both are not preferred because the flow mark deteriorates.

The composition of the present invention basically comprises the above (A),
It is composed of three components (B) and (C). If necessary, a rubber-like elastic body, cubic calcium carbonate or talc, glass fiber, or the like may be used as long as the object of the present invention is not impaired. Other inorganic fillers such as mica can be used in combination. Furthermore, pigments and other additives can be added as appropriate.

In producing the polyolefin resin composition of the present invention, a usual kneading method can be adopted. Specifically, for example, a predetermined amount of each of the above components is blended and preliminarily blended with a ribbon blender, a V-type blender or the like, and then a twin-screw kneader (FCM, TEM) or a single-screw extruder (N
Using a kneading machine such as VC), the composition can be uniformly kneaded to obtain a powdery or granular composition. The kneading temperature is not particularly limited, but is usually 190 to 270 ° C.

The polyolefin-based resin composition obtained by the method of the present invention can be prepared by injection molding, extrusion molding, hollow molding, compression molding, lamination molding, roll molding, centrifugal molding, stamping, etc. Can be formed into a molded article having a desired shape.

[0020]

Next, the present invention will be described in detail with reference to examples.

Examples 1 to 12 The components shown in Table 1 were mixed in a strong kneading type twin-screw kneader (FCM), and the kneading temperature was 220 ° C. and the screw rotation speed was 90.
0r. p. The mixture was kneaded under the conditions of m to obtain a granular material. Using the granules thus obtained, an injection molded product (test piece) was molded by an injection molding machine, and the physical properties were evaluated.

The general physical properties (low-temperature DuPont impact strength, bending characteristics and heat distortion temperature (HDT)) of the injection-molded article were measured and evaluated by the following methods. First, the low-temperature Dupont impact strength was measured under the following test conditions. 1) Load: 2 kg 2) Hammer tip size: 1/4 inch R 3) Dish inner diameter: 2 inches in diameter 4) Evaluation sample: 75 x 75 x 3 (flat plate) 5) Data: Destruction start height x load The bending properties were determined in accordance with ASTM D-790, and the heat distortion temperature (HDT) was determined in accordance with ASTM D-648. The flow mark in the appearance performance was measured by molding a flat plate of 420 × 100 × 3 mm from the side gate of the injection molding machine, and measuring the distance (cm) from the gate to the place where the flow mark was generated. Was evaluated at that distance.

Further, the weld appearance of the appearance performance is determined by the degree of discrimination of the black line of the weld portion generated on the embossed surface of the injection-molded article having the shape shown in FIG. Left and right color unevenness
All were evaluated in the following four stages. Note that, in FIG. 1, reference symbol A is a gate, reference symbol B is a weld line, and reference symbol C is a textured surface. The numbers in FIG. 1 indicate lengths (unit: mm).

◎: Unrecognizable (excellent) 〇: Almost indistinguishable (excellent) Δ: Somewhat noticeable (poor) ×: Considerable (unacceptable)

Further, as shown in FIG.
For a disk (thickness: 2.5 mm, diameter: 150 mm) molded from the center gate of an injection molding machine, the maximum warpage width (amm, bmm) in the front-to-back direction from the standard surface was obtained, and was obtained by the following equation.

Warpage rate (%) = [(a + b) / 2] × [1/150]

Further, the tapping characteristic is that the inner diameter is 3.5φ.
Boss specified in JIS-B1115
Two kinds of pan-type screws were screwed in at 80 rpm, and when the boss screw was broken, the case where the boss side surface was broken (when broken) was evaluated as x, and the case where it was not broken was evaluated as ○.

Further, the metal abrasion can be measured by setting a 150 g brass nozzle at the tip of a molding machine (IS-40B manufactured by Toshiba Machine Co., measuring stroke 90 mm, injection speed 100%) at a molding temperature of 220 ° C. When 100 shots were purged, the weight of the brass nozzle was measured, and the change in weight (mg) was evaluated. Table 1 shows the results.

Comparative Examples 1 and 10 Except for using an extruder type twin screw kneader (TEM), calcium carbonate fiber was supplied by a side feed method, and the components shown in Table 1 were blended. In the same manner as in Example 1, physical properties were evaluated. The results are shown in Table 1. As shown in Comparative Example 1, when the calcium carbonate fiber having an average aspect ratio of more than 25 is used, it is found that the low-temperature surface impact resistance sharply decreases and the warpage ratio also increases. In addition, when EPR was used instead of HDPE as in Comparative Example 10, it was found that the bending characteristics were significantly reduced and there was a problem in weld appearance, particularly in color unevenness.

Comparative Examples 2 to 5 and Comparative Examples 11 to 12 In the same manner as in Example 1, except that the components shown in Table 1 were blended, physical properties were evaluated. The results are shown in Table 1. As shown in Comparative Example 2, the average fiber diameter was 5
When a calcium carbonate fiber exceeding μm is used, Example 2
As is clear from comparison with the above, it can be seen that particularly the bending characteristics and HDT are reduced. Further, as shown in Comparative Example 3, the isotactic pentad fraction [I] of the propylene-based polymer was less than 92% by weight, or as shown in Comparative Example 4, the ethylene content of the propylene-based polymer was 15% or less. It is found that when the content exceeds% by weight, the heat distortion temperature is lowered and the bending properties are lowered. Comparative Example 5
As shown in the graph, when the MI of the propylene-based polymer is less than 1 g / 10 minutes, the heat distortion temperature is lowered, the bending properties are lowered, and more flow marks are generated.

Comparative Example 6 The procedure of Example 1 was repeated, except that cubic heavy calcium carbonate having an average particle size of 2 μm and an aspect ratio of 1 was used instead of the calcium carbonate fiber. Was evaluated. The results are shown in Table 1. When heavy calcium carbonate is used, impact resistance is obtained, but the heat distortion temperature decreases and the bending properties (rigidity)
It turns out that it decreases.

Comparative Example 7 The same as Example 9 except that a high impact-resistant instrument panel material containing talc was used instead of the calcium carbonate fiber in Example 9 as a material used as an automobile interior part. And the physical properties were evaluated. The results are shown in Table 1. In this case, it can be seen that the weld appearance is significantly reduced and the tapping characteristics are also poor.

Comparative Example 8 The same procedure as in Example 8 was carried out except that, instead of the calcium carbonate fiber in Example 8, a material for high-flow trim containing talc was used as a material used as an automobile interior part.
And the physical properties were evaluated. The results are shown in Table 1. In this case, it can be seen that the weld appearance is significantly reduced and the tapping characteristics are also poor.

Comparative Example 9 A mixture of milled fiber (crushed glass fiber) and wollastonite (former / latter = 1 / l) instead of the calcium carbonate fiber in Example 4 was used as a material used as an automobile interior part. 2 (weight ratio)), and the physical properties were evaluated in the same manner as in Example 4, except that a material for a high-rigid instrument panel in which 30% by weight was blended was used. First result
It is shown in the table. In this case, it can be seen that the metal wear resistance is significantly reduced.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[In the legs in Table 1] * 1: MI is 10 g / 1
A propylene resin having 0 minutes, an ethylene content of 8% by weight, and an isotactic pentad fraction [I] of 95%. * 2: A propylene-based resin having an MI of 20 g / 10 minutes, an ethylene content of 0% by weight, and an isotactic pentad fraction [I] of 95%. * 3: A propylene-based resin having an MI of 10 g / 10 minutes, an ethylene content of 8% by weight, and an isotactic pentad fraction [I] of 98%. * 4: A propylene-based resin having an MI of 10 g / 10 minutes, an ethylene content of 4% by weight, and an isotactic pentad fraction [I] of 95%. * 5: A propylene-based resin having an MI of 20 g / 10 minutes, an ethylene content of 8% by weight, and an isotactic pentad fraction [I] of 95%. * 6: A propylene-based resin having an MI of 10 g / 10 minutes, an ethylene content of 8% by weight, and an isotactic pentad fraction [I] of 91%. * 7: A propylene-based resin having an MI of 10 g / 10 minutes, an ethylene content of 17% by weight, and an isotactic pentad fraction [I] of 95%. * 8: MI of 0.08 g / 10 min, ethylene content of 4% by weight, isotactic pentad fraction [I] of 94%
Propylene resin. * 9: High density polyethylene (MI 5.8 g / 10 min, density 0.967 g / cm ³ , manufactured by Idemitsu Petrochemical Co., Ltd., trade name: 210J) * 10 Ethylene propylene rubber (Mooney viscosity 24 [M
L _{1 + 4} (100 ° C)], manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: E
P-02P) * 11 Milled fiber (crushed glass fiber) / wollastonite = 1/2 (weight ratio) * 12 High density polyethylene (MI 0.04 g / 10)
Minute, manufactured by Idemitsu Petrochemical Co., Ltd., trade name: Idemitsu 750L
B) * 13 The frozen fracture surface of the Izod specimen was measured by confirming it with an SEM photograph.

[0039]

The polyolefin resin composition of the present invention is characterized in that the molded article after molding is warped and the material has little anisotropy. Moreover, the polyolefin-based resin composition of the present invention is excellent in appearance (weld appearance, flow mark) of a molded article after molding. Furthermore, the polyolefin-based resin composition of the present invention has a good balance of physical properties (balance between rigidity and impact resistance) of a molded article after molding, and excellent moldability. Further, the polyolefin-based resin composition of the present invention does not require addition of a soft resin component, does not require a special kneading method, and is economically excellent. Therefore, the polyolefin-based resin composition of the present invention can be used very effectively as a material for automobiles, home appliances, light electrical appliances and the like.

[0040]

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a shape of a molded product used for evaluating a weld appearance in Examples and Comparative Examples of the present invention.

FIG. 2 is an explanatory view showing a cross section of a molded disk used for evaluating a warpage ratio in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

A Gate B Weld line C Surface of grained surface a Maximum warp width in the surface direction of the molded disk (unit: mm) b Maximum warp width in the back (opposite) direction of the molded disk (unit: m)
m)

Claims (1)

(57) [Claims] (A) a melt index of 1 to 100
a g / 10 min, an ethylene content of 0-15 wt%, and propylene isotactic pentad fraction of the homopolymer portion [I] is 92 wt% or more heavy
50-99% by weight , (B) melt index is 1
g / 10 min or more high-density polyethylene 0-25 wt% and (C) an average fiber diameter of at 5μm or less, and a polyolefin-based resin having an average aspect ratio is from 1 to 50% by weight fibers of calcium carbonate 3-25 Composition .