JP2000154281A - Polyolefin resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit agglomerates, i.e., the cause of white streaks or unevenness in color, from occurring in a molded polyolefin resin item without detriment to the mechanical properties of the molded item by compounding a polyolefin resin with specified amounts of a petroleum resin and at least one filler selected from among calcium carbonate, precipitated barium sulfate, glass beads, and silica. SOLUTION: A polyolefin resin of 100 pts.wt. having a density of 0.905 g/cm3 or higher is compounded with 0.5-2 pts.wt. petroleum resin which has a softening point (JIS K 2531) of 70 deg.C or higher and is obtained by polymerizing an unsaturated 6-9C component produced in naphtha cracking, 0.2-2 pts.wt. filler which has a particle size of 0.4-10 μm and is selected from among calcium carbonate, precipitated barium sulfate, glass beads, and silica, and optionally a carbon black, an organic pigment (such as a phthalocyanine, quinacridone, or anthraquinone pigment), an inorganic pigment (e.g. cobalt blue, red oxide, ultramarine blue, or titanium oxide), a dispersant, an ultraviolet absorber, a stabilizer, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin-based resin composition for eliminating white stripes, color unevenness and the like often occurring on the surface of a molded article produced using the polyolefin-based resin. .

[0002]

2. Description of the Related Art In general, when a molded article is produced by blending an additive having poor compatibility with a polyolefin resin, color unevenness or white stripes may occur on the surface of the molded article, which may cause a decrease in commercial value. ing. For example, blending titanium oxide or talc to color the polyolefin resin in white, or blending a large amount of inorganic filler to improve impact resistance, and manufacturing molded products by extrusion molding machines or injection molding machines Then, accidents such as white stripes and color unevenness often occur on the surface. Conventionally, when white streaks or color unevenness have occurred, a molded article containing a large amount of a dispersant has been manufactured in order to solve the problem, but additives are bleed on the surface of the molded article. It is not preferable because stickiness occurs and mechanical properties are deteriorated.

As an example of a method for eliminating streaks generated when a pigment is blended with a polyolefin resin, use of iron black instead of carbon black has been proposed (Japanese Patent Publication No. Sho 62).
-14576). However, iron black requires about 7 to 10 times as much as carbon black, which is not preferable because it causes a disadvantage that impact resistance and strength are reduced.
In recent years, in order to reduce the cost of molded products using polyethylene resin or polypropylene resin, the thickness of molded products has been reduced,
Low specific gravity is required. For polyolefin-based resins, in order to maintain the impact resistance and increase the rigidity of molded products such as automobile parts and home appliances, development of molded products using high quality resin with improved crystallinity is under study. With the advancement of performance catalysts and polymerization technology, resins with high-dimensional molecular control realized and dramatically improved quality performance have been developed. In particular, the highly crystalline polypropylene resin developed as a resin that fulfills the above two purposes has high stereoregularity of the molecular structure and high crystallinity, and therefore has the characteristics of high rigidity and high heat deformation temperature. In addition, as the specific gravity can be reduced by reducing the product wall thickness and the amount of filler added, it is widely used in automobile bumpers, instrument panels and the like.

[0004] However, the high-crystalline polypropylene resin contains a pigment in comparison with the conventional polyolefin resin,
When an inorganic filler is compounded, white stripes and color unevenness are more likely to occur. Therefore, in the production of various automobile parts using a high crystalline polypropylene resin, it is an important problem how to eliminate white stripes and white unevenness. In addition, a resin having excellent rigidity is required for automobile parts, for example, bumpers and instrument panel parts. For this reason, a highly crystalline polypropylene resin having significantly improved rigidity and impact resistance has been developed, and in recent years, a resin composition in which talc has been frequently blended as a filler to further improve rigidity has been developed. White streaks and color unevenness are likely to occur. As a cause of these white streaks and color unevenness, when a substance having poor compatibility with the thermoplastic resin is mixed, the mixture adheres to the cylinder or screw surface of the molding machine or the exit of the molding machine as an aggregate, which is formed. It is considered that white streaks are formed on the surface of the product, or that aggregates are peeled off from the surface of the molding machine and migrate to the molded product to generate white streaks.

[0005]

Accordingly, the present inventors have suppressed the generation of the above-mentioned white streaks and agglomerates causing color unevenness without impairing the mechanical properties of the obtained molded article, The present inventors have studied the development of a polyolefin-based resin composition capable of producing a colored molded article that is uniformly colored even when a large amount of a filler is blended.

[0006]

Means for Solving the Problems That is, the invention of claim 1 is:
(A) 0.5 to 2 parts by weight of petroleum resin and (B) 0.2 to 2 parts by weight of calcium carbonate, precipitated barium sulfate, glass beads and / or silica, based on 100 parts by weight of polyolefin resin. It is a polyolefin-based resin composition.
The invention according to claim 2 is a polyolefin resin composition in which the petroleum resin according to claim 1 is an aliphatic cyclic hydrocarbon resin. The invention of claim 3 is characterized in that (a) 0.5 to 2 parts by weight of an aliphatic cyclic hydrocarbon resin, (B) calcium carbonate, glass beads and / or silica are added in an amount of 0.2 to 100 parts by weight of a highly crystalline polypropylene resin. It is a polyolefin-based resin composition containing up to 2 parts by weight. The invention according to claim 4 is characterized in that (a) 0.2 to 2 parts by weight of an aliphatic cyclic hydrocarbon resin, and (b) 0.2% by weight of calcium carbonate with respect to 100 parts by weight of a polypropylene resin.
It is a polyolefin-based resin composition containing 2 to 2 parts by weight.

Therefore, in the present invention, the presence of agglomerates generated on the inner surfaces of screws and cylinders and the outlets of extruders and injection molding machines, which are the cause of white streaks, is eliminated from the surface of molded articles. By removing the streaks, the occurrence of color unevenness was significantly suppressed. That is, the product of the present invention comprises (B) calcium carbonate, precipitated barium sulfate, glass beads and / or
Alternatively, agglomerates generated during molding are removed by adding 0.2 to 2 parts by weight of silica, and the removed agglomerates are diffused into the polyolefin resin due to the presence of the petroleum resin.

[0008] The highly crystalline polypropylene resin used in the invention of claim 5 is prepared by previously blending talc and / or glass fiber to improve the rigidity. The use of the component (b) eliminates white streaks and color unevenness. In the present invention, the presence of the component (A) and the component (B) according to claim 1 makes it possible to produce a molded article in which a pigment is blended with a high-quality polyolefin-based resin developed in recent years, particularly a highly crystalline polypropylene resin, When a large amount of talc is blended, a molded article using a polyolefin-based resin that does not cause any white streaks or color unevenness can be obtained. As the olefin resin used in the present invention, in recent years, high-density polyethylene resins such as low-density, medium-density, high-density or linear low-density, which have improved quality performance that has emerged due to advances in high-performance catalysts and polymerization techniques, or Polyprolene resins such as homo, block and random are exemplified. In particular, for polypropylene-based resin, the elasticity and density can be significantly improved by increasing the crystallinity (eg, synthetic resin, 1992
No. 6: JETI, No. 8, 1995), and the synthesis method has progressed from the first generation to the fourth and fifth generations in accordance with the progress of the catalyst used. (Example: Technical Review, Issue 9 1997) is also said to be larger.

The highly crystalline polypropylene thus obtained has a small amount of non-crystalline portions in the molecular structure, has a high stereoregularity over a wide range from low molecular weight to high molecular weight, and has an optimally adjusted molecular weight distribution. The crystal is
The crystallization is fast, the structure is fine and uniform, and the crystallinity is high. Generally, when the resin density of the highly crystalline polypropylene resin is 0.905 or more, the impact resistance is large and the rigidity is greatly improved. Examples of the highly crystalline polypropylene resin used in the present invention include a homopolymer resin, a copolymer with a polypropylene resin, for example, a propylene / ethylene block copolymer, a propylene / butene block copolymer, and a propylene / methylpentene block copolymer. And a propylene / vinylcyclopentane block copolymer.

The highly crystalline polypropylene resin used in the present invention includes a highly crystalline polypropylene resin, which is preliminarily blended with talc or glass fiber and sold as a product that easily exhibits greater rigidity. These highly crystalline polypropylene-based resins have a disadvantage that white streaks are likely to frequently occur on the surface of the molded product when a pigment is blended or when talc is blended for further improving rigidity. Therefore, the product of the present invention has solved the above-mentioned drawbacks by combining the components (A) and (B) described in claim 1 and blending them in a fixed amount. Is used.

The petroleum resin used in the present invention will be described below. A petroleum resin is a rosin resin obtained by isolating an unsaturated component having 6 to 9 carbon atoms (monomer) produced during naphtha decomposition or polymerizing the mixture as a mixture. The type of the resin depends on the monomer source. It is classified into aliphatic, aromatic, alicyclic (aliphatic cyclic hydrocarbon resin) and copolymer. Specifically, in the case of aliphatic petroleum resins, the mainstream is an unsaturated petroleum resin containing a distillate having 6 carbon atoms containing pentene, isoprene, piperylene and the like. The mainstream aromatic petroleum resins are those obtained by polymerizing styrenes and indenes in an unsaturated C9 fraction. The mainstream of alicyclic petroleum resins is a resin obtained by hydrogenating an aromatic petroleum resin into an alicyclic structure.

The copolymerized petroleum resin is a resin obtained by polymerizing different monomer mixture fractions, and is generally obtained by copolymerizing an unsaturated C8 and C9 fraction. The physical properties of the petroleum resin used in the present invention are not particularly limited, but the softening point is preferably 70 ° C (measured in JIS-K-2531) or higher, and if the softening point is less than 70 ° C, the composition of the present invention is used. At the time of kneading and manufacturing, workability such as adhesion to a heated kneader is lowered, which is not preferable. As the petroleum resin used in the present invention, an aliphatic cyclic hydrocarbon resin is most effective for eliminating white scratches generated on the surface of a molded article, and is an unsaturated carbon containing pentene, isoprene, piperylene and the like. It is preferable to use a fraction of Formula 6 as a raw material. The average particle size of the calcium carbonate, precipitated barium sulfate, glass beads or silica used in the present invention may be any one having a particle size conventionally used for kneading with a thermoplastic resin, for example, 0.4 to 10 μm. is there. Also, any shape may be used as long as it has been conventionally used for a thermoplastic resin.

The compounding ratio of (A) petroleum resin and (B) calcium carbonate, precipitated barium sulfate, glass beads and / or silica to the polyolefin resin in claim 1 is 100 parts by weight of the polyolefin resin. , 0.5 to 2 parts by weight of petroleum resin, 0.2 to 2 parts by weight of calcium carbonate, precipitated barium sulfate, glass beads and / or silica. (A) If the amount of petroleum resin is less than 0.5 part by weight, particles of agglomerates will appear on the surface of the molded product and white streaks and color unevenness are likely to occur. If the amount is more than 2 parts by weight, the surface of the molded product will be sticky. It is not preferable because it may occur. (B) If the amount is less than 0.2 parts by weight of calcium carbonate, glass bead and / or silica, the aggregates adhered to the inner surface of the cylinder and the screw surface are not sufficiently removed, and therefore the white streaks are not eliminated from the surface of the molded product. If the amount is more than 2 parts by weight, the effect does not change and 2 parts by weight is sufficient. In the second aspect, by limiting the petroleum resin to the aliphatic cyclic hydrocarbon resin, the above-mentioned aggregate is easily compounded in the polyolefin resin, and the generation of white stripes and color unevenness is largely eliminated.

According to the third aspect of the invention, by limiting the polyolefin resin to a highly crystalline polypropylene resin, the present invention is applicable to molding of an automobile bumper or an instrument panel which requires rigidity and impact resistance. In particular, claim 4 provides an optimum composition for eliminating white stripes generated when using a highly crystalline polyprolene resin, which has been actively developed in recent years. Examples of the pigment to be blended with the polyolefin resin composition of the present invention include pigments conventionally used generally for coloring plastics, for example, organic pigments such as carbon black, phthalocyanine, quinacridone, and anthraquinone, and cobalt blue. , Bengara, ultramarine, titanium oxide and the like, and two or more of these may be used in combination. In the polyolefin-based resin composition of the present invention, various resins, additives such as a dispersant, an ultraviolet absorber, and a stabilizer may be appropriately compounded as needed as long as the characteristics of the present invention are not impaired. Further, the method for producing the polyolefin resin composition of the present invention is carried out by a conventional method conventionally employed,
For example, even if a master batch containing the components (A) and (B) described in claim 1 in a larger amount than the specified amount is manufactured and then diluted with a resin, the specified amounts of (A) and (B) are directly applied. ) The components may be blended in a moldable state. Examples and comparative examples are described below.

Example 1 100 parts by weight of a highly crystalline homopolypropylene resin for injection molding having a density of 0.910 and MFR6 (product of Chisso Corporation: HCPP-K5016), 1.0 part by weight of a phthalocyanine pigment, 0.2 part by weight of calcium stearate, an aliphatic cyclic 0.9 parts by weight of a hydrocarbon resin (commercially available from Arakawa Chemical Co., Ltd .: Alcon P-125) and 1.1 parts by weight of calcium carbonate having an average particle size of 2 μm are mixed using a V blender, and then melt-kneaded using an extruder. A color compound is manufactured to obtain the polyolefin resin composition of the present invention containing a pigment. The following evaluation tests (a) and (b) were carried out using test pieces obtained by preparing test pieces of 150 * 120 * 2 mm from the polyolefin resin composition using an injection molding machine, and the results were shown in Table 1. It describes in. Hereinafter, the same evaluation test was performed for Examples 1 to 9 and Comparative Examples 1 to 8, and the results are shown in Table 1.

(A) Observation of white streaks and color unevenness A 150 * 120 * 2 mm test piece was prepared, and the surface of the test piece was visually observed to determine the color streaks and color unevenness according to the following criteria.
The result

[Table 1] It was shown to. ◎: Not generated at all, ○: Slightly generated, ×: Generated frequently (b) Impact resistance Measured according to JIS-K-7110. In Examples 3 to 8 and Comparative Examples 1 to 8, the evaluation was based on the evaluation when used as an automobile bumper. In Examples 1, 2 and 9, the evaluation was based on the case where the product was used as a household product. Judgment is made based on ◎… Excellent, ○… Practical limit, ×… There is a problem in use

Example 2 100 parts by weight of a highly crystalline homopolypropylene resin for OPP having a density of 0.910 and MFR 1.5 (manufactured by Chisso Corporation: HCPP-XF2805), 20 parts by weight of talc, 0.05 parts by weight of calcium stearate, an aliphatic resin 0.9 parts by weight of cyclic hydrocarbon resin (Arakawa Chemical Co., Ltd. product: Archon P-125) and average particle size 2.1 μm
After mixing 1.1 parts by weight of the above calcium carbonate using a V-blender device, the mixture is melt-kneaded using an extruder to produce a color compound, and a polyolefin resin composition of the present invention containing talc is obtained. A 150 * 120 * 2 mm test piece was prepared from the polyolefin resin composition using an injection molding machine, and the same evaluation tests (A) and (B) as in Example 1 were performed.
And the results are shown in Table 1.

Example 3 Example 1 was repeated except that the highly crystalline homopolypropylene resin used in Example 1 was replaced by a highly crystalline block polypropylene having a density of 0.910 and MFR10 (Mitsubishi Petrochemical Co., Ltd. product: CJ640). Is the same as Example 4 The same as Example 1 except that the highly crystalline homopolypropylene resin used in Example 1 was replaced with a highly crystalline block polypropylene having a density of 0.91 and MFR60 (product of Chisso Corporation: HCPP-K5360). . Example 5 Except that the aliphatic cyclic hydrocarbon resin used in Example 4 was replaced with an aliphatic petroleum resin composed of pentene and isoprene (Arakawa Chemical Co., Ltd. product: P-140), all of Example 4 was used.
Is the same as

Example 6 The same procedure as in Example 4 was carried out except that calcium carbonate used in Example 4 was replaced by precipitated barium sulfate. Example 7 The same as Example 1 except that the highly crystalline homopolypropylene resin used in Example 1 was replaced with a highly crystalline block polypropylene having a density of 0.91 and MFR40 (manufactured by Chisso Corporation: HCPP-K9140). . Example 8 As a highly crystalline homopolypropylene resin, a high-grade polypropylene having a specific gravity of 1.04 and an MFR of 25, which is an impact-resistant brand previously blended with talc (Mitsui Petrochemical Co., Ltd. product: TA89
9) To 100 parts by weight, 1.0 part by weight of a phthalocyanine pigment, 0.2 parts by weight of calcium stearate, 1.1 parts by weight of an aliphatic cyclic hydrocarbon resin (Alcon P-125, manufactured by Arakawa Chemical Co., Ltd.) and calcium carbonate 1.1 having an average particle size of 2 μm. Parts by weight V
After mixing using a blender, the mixture is melt-kneaded using an extruder to produce a color compound, and a polyolefin-based resin composition of the present invention containing a pigment is obtained. Thereafter, test specimens were prepared in the same manner as in Example 1, and evaluation tests (a) and (b) were performed. The results are shown in Table 1.

Example 9 100 parts by weight of a high-density polyethylene resin having a density of 0.957, 0.8 parts by weight of a phthalocyanine pigment, 0.2 parts by weight of calcium stearate, 0.8 parts by weight of an aliphatic cyclic hydrocarbon resin (manufactured by Arakawa Chemical Co., Ltd .: Alcon P-125) Parts and average particle size 2.1μm
After mixing 1.1 parts by weight of the above calcium carbonate using a V-blender apparatus, the mixture is melt-kneaded using an extruder to produce a color compound, thereby obtaining a polyolefin resin composition of the present invention containing a pigment. A 150 * 120 * 2 mm test piece is prepared from the polyolefin resin composition using an injection molding machine.
Thereafter, evaluation tests (a) and (b) were performed, and the results are shown in Table 1.

Comparative Example 1 The same as Example 4 except that the amount of calcium carbonate used in Example 4 was 0.1 part by weight. Comparative Example 2 The amount of the aliphatic hydrocarbon resin used in Example 4 was 0.2
It is the same as Example 4 except that the weight is used. Comparative Example 3 The same as Example 4 except that the amount of calcium carbonate used in Example 4 was changed to 5 parts by weight. Comparative Example 4 The same as Example 4 except that the amount of the aliphatic hydrocarbon resin used in Example 4 was changed to 5 parts by weight.

Comparative Example 5 Example 8 was the same as Example 8 except that the amount of the precipitated barium sulfate used in Example 8 was changed to 0.1 part by weight. Comparative Example 6 The amount of the aliphatic hydrocarbon resin used in Example 8 was 0.2
It is the same as Example 8 except that the weight is used. Comparative Example 7 The same as Example 8 except that the amount of calcium carbonate used in Example 8 was changed to 5 parts by weight. Comparative Example 8 The same as Example 8 except that the amount of the aliphatic hydrocarbon resin used in Example 8 was changed to 5 parts by weight.

[0023]

[Table 1]

[0024]

According to the present invention, the effect of eliminating white streaks and color unevenness caused when a pigment is added for coloring a polyolefin-based resin or talc or glass fiber is added for improving rigidity is obtained. It is intended to provide a polyolefin-based resin composition as described above. Particularly, the present invention provides a resin composition for solving the drawback that white streaks and color unevenness are likely to occur when an additive is blended with a high-density high-crystalline polypropylene resin which has been actively developed in recent years.

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Claims (6)

[Claims] 1. To 100 parts by weight of a polyolefin resin, (A) 0.5 to 2 parts by weight of a petroleum resin, (B) 0.2 to 2 parts by weight of calcium carbonate, precipitated barium sulfate, glass beads and / or silica. A polyolefin-based resin composition that is blended. 2. A polyolefin resin composition wherein the petroleum resin according to claim 1 is (a) an aliphatic cyclic hydrocarbon resin. 3. A high-crystalline polypropylene resin (100 parts by weight), (a) 0.2 to 2 parts by weight of an aliphatic cyclic hydrocarbon resin, (B) calcium carbonate, precipitated barium sulfate, glass beads and / or A polyolefin-based resin composition containing 0.2 to 2 parts by weight of silica. 4. A polypropylene resin 1 having a density of 0.905 or more.
(A) aliphatic cyclic hydrocarbon resin 0.2
To 2 parts by weight, and (b) 0.2 to 2 parts by weight of calcium carbonate and / or precipitated barium sulfate. 5. A polyolefin resin composition wherein the highly crystalline polypropylene resin according to claim 3 is a blend of talc and / or glass fiber. 6. A molded article obtained by mixing a pigment and / or talc with the polyolefin-based resin composition according to claim 3.