JP2595312C - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyolefin resin composition, and more particularly, to a polyolefin resin composition having good surface appearance and physical properties excellent in rigidity, strength, impact resistance and heat resistance. The present invention relates to a polyolefin resin composition. [Problems to be Solved by Conventional Techniques and Inventions] Conventionally, a polyolefin resin composition has a mixture of a polyolefin as a matrix resin and an inorganic filler, and a molded article produced from the polyolefin resin composition is generally used. Have been. Among these inorganic fillers, particularly, calcium carbonate is generally used as an inexpensive filler, and as the polyolefin, polypropylene, polyethylene and the like are particularly often used. The polyolefin resin composition containing calcium carbonate has the advantages of high whiteness and good appearance, but has the disadvantage of low mechanical properties such as rigidity and strength or low heat resistance. . Accordingly, molded articles of these polyolefin resin compositions cannot be suitably used for industrial materials and daily necessities materials requiring mechanical strength, particularly for automobile parts. An object of the present invention is to provide a polyolefin resin composition having a good appearance, excellent mechanical properties, excellent heat resistance, and usable as a material in the field of industrial products and daily necessities by blending fibrous calcium carbonate having a fiber diameter of 3 μm or less. To provide. [Means for Solving the Problems] The present inventors have intensively studied to solve the above-mentioned conventional problems, and filled particulate calcium carbonate by blending fibrous calcium carbonate having a fiber diameter of 3 μm or less. By finding a polyolefin composition that can maintain the properties of the composition and greatly improve rigidity, strength, and heat resistance, and by adding an inorganic filler having a plate-like morphology as a third component to the composition, The inventors have found a polyolefin resin composition capable of preventing warpage and have reached the present invention. In other words, the present invention for solving the above-mentioned problems comprises a polyolefin of 30 to 95% by weight and a fibrous calcium carbonate having a fiber diameter of 3 μm or less of 5 to 70% by weight. And the polyolefin in a molten state contained in such a manner that the sum of the
A polyolefin resin composition characterized by adding and mixing kium (claim 1), and 30 to 90% by weight of polyolefin and 5 to 50% by weight of fibrous calcium carbonate having a fiber diameter of 3 μm or less. And an inorganic filler 5 having a plate shape
30% by weight so that the sum of the weight% of the polyolefin, the weight% of the fibrous calcium carbonate and the weight% of the inorganic filler is 100 , and
The above-mentioned fibrous calcium carbonate is added to the above-mentioned polyolefin in a state, and the mixture is kneaded.
A polyolefin resin composition characterized by that (claim 2). Hereinafter, the polyolefin resin composition will be described in detail. Examples of the polyolefin that can be used in the present invention include polypropylene such as polypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer, and the like, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-polyethylene, and the like. Polyethylene such as high density polyethylene; ethylene-α-olefin copolymer such as ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer Polymers; propylene-olefin copolymers such as propylene-butene-1 copolymer, ethylene-propylene-diene copolymer including cyclopentadiene, etc .; polybutene-1; poly-4-methyl-pentene-3 and the like. Can be mentioned. Each of these may be used alone, or two or more of them may be used in appropriate combination. Further, from the viewpoint of the production method, a polyolefin obtained by using a Ziegler-Natta catalyst and producing it in a two-stage or three-stage or more multistage polymerization method can also be used. A method for producing, for example, a so-called propylene-ethylene block copolymer by this multi-stage polymerization method will be described below. That is, for example, polymerization of propylene monomer in the first stage is carried out in the presence of a Ziegler-Natta catalyst to obtain a polypropylene homopolymer, and then the propylene monomer is removed or not removed in the second stage in the presence of ethylene. Alternatively, polypropylene can be produced by performing a polymerization reaction in the coexistence of ethylene and propylene. The pressure in the reaction of each stage may be several atmospheres to 40 atmospheres, and the temperature may be room temperature to 80 ° C. Further, as a polymerization reaction system, solution polymerization, slurry polymerization, gas phase polymerization, a combination method thereof, or the like can be employed. The so-called propylene ethylene block copolymer obtained by such a multi-stage polymerization method contains ethylene as a monomer unit in the resin, so it is not yet clear, but polyethylene is contained in the resin, or Copolymerization of ethylene and propylene may be included. In the present invention, among the various polyolefins, a so-called propylene-ethylene block copolymer produced by a multi-stage polymerization method, polypropylene, and the like are preferable. What is important in the present invention is that fibrous calcium carbonate is blended, and mechanical properties and heat resistance are insufficient when using conventional amorphous, cubic, or spindle-shaped calcium carbonate. However, these physical properties could be remarkably improved by using fibrous calcium carbonate. The form of the fibrous calcium carbonate has a fiber diameter of 3 μm or less, particularly preferably 1 μm or less, and an aspect ratio of 20 or more, preferably 30 or more. When the fiber diameter exceeds 3 μm and the aspect ratio is less than 20, the improvement in rigidity and strength of the polyrefin resin composition may be small, and the appearance of the molded product may be impaired. The amount of the polyolefin in the polyolefin resin composition is 30 to 95% by weight, preferably 50 to 90% by weight, based on the total amount of the polyolefin and the fibrous calcium carbonate. When the polyolefin content exceeds 95% by weight and the fibrous calcium carbonate content is less than 5% by weight, the improvement in rigidity, strength, heat resistance and the like is small. Conversely, the polyolefin content is less than 30% by weight and the fibrous calcium carbonate content is 70% by weight. %, The impact strength is remarkably reduced, and the specific gravity is increased. The polyolefin resin composition according to claim 2 is a composition containing a polyolefin, fibrous calcium carbonate, and an inorganic filler having a plate-like shape. The kind of the polyolefin in claim 2 is the same as the kind of the polyolefin in claim 1, and the form of the fibrous calcium carbonate in claim 2 is the same as that in claim 1. Examples of the inorganic filler having a plate shape include alumina, aluminum hydroxide, kaolin clay, iron oxide, sericite, molybdenum disulfide, baryte (barium sulfate), vermiculite, talc, mica, and glass flake. Can be. One of the various inorganic fillers may be used alone, or two or more thereof may be used in combination. Among the various inorganic fillers, talc, mica, glass flake and the like are preferable. The plate-like form preferably has a ratio of the maximum diameter to the thickness of 5 or more. The mixing ratio of each component in the polyolefin resin composition according to claim 2 is preferably 30 to 90% by weight of the polyolefin, based on the total of the polyolefin, the fibrous calcium carbonate, and the inorganic filler having a plate shape. Is from 40 to 80% by weight, from 5 to 50% by weight, preferably from 10 to 40% by weight, for fibrous calcium carbonate, and from 5 to 40% by weight for the inorganic filler having a plate form.
-30% by weight, preferably 10-20% by weight. When the amount of the inorganic filler having a plate form exceeds 30% by weight, the appearance of the weld is deteriorated, the flow mark is liable to be generated, and the weld strength and the impact strength are greatly reduced, and conversely, less than 5% by weight. And the effect of suppressing the warpage may be small.
When the amount of fibrous calcium carbonate exceeds 50% by weight, the anisotropy increases and the impact strength decreases. Conversely, when the amount is less than 5% by weight, the effect of improving strength, rigidity and heat resistance may decrease. Further, the polyolefin resin composition according to any one of claims 1 and 2 contains one or more of various elastomers, various inorganic fillers, and various additives as long as the object of the present invention is not impaired. Is also good. Desirably, the elastomer is, for example, EP rubber or SB rubber, and the inorganic filler is, for example, calcium silicate, magnesium oxide, amorphous, cubic or spindle-shaped calcium carbonate, gypsum, carbon black, titanium oxide, quartz powder, or the like. May be blended according to. As additives, heat stabilizers, lubricants, surface treatment agents, dispersants, antioxidants, ultraviolet absorbers, antistatic agents, weathering agents, flame retardants, coloring agents, etc. may be added as desired. Good. In producing the polyolefin resin composition of the present invention, the above components are blended in a predetermined amount, blended in advance with a ribbon blender, a V-type blender, etc., kneaded with a kneader and uniformly mixed to obtain a powdery or granular form. It can be a composition. Alternatively, the predetermined amount of the polyolefin and the predetermined amount of the fibrous calcium carbonate are separately separated, and the polyolefin is supplied to a material supply port (first material supply port) far from the extrusion port of the kneader, and a position close to the extrusion port is provided. The fibrous calcium carbonate is supplied to the material supply port (second material supply port) in the above, and when the polyolefin is pushed forward by a screw to be in a molten state, the fibrous calcium carbonate is uniformly mixed from the second material supply port. However, it can also be a powdery or granular composition. In order to maintain the shape of the fibrous calcium carbonate and exert the effect of the polyolefin resin composition, the latter kneading method is preferred. Although the inorganic filler having a plate-like form is supplied to the first material supply port together with the polyolefin, it may be supplied together with the fibrous calcium carbonate from the second material supply port depending on the use conditions. The polyolefin resin composition obtained by the method of the present invention can be subjected to various molding methods such as an injection molding method, an extrusion molding method, a hollow molding method, a compression molding method, a lamination molding method, a roll molding method, a stretching method, and a stamping method. It can be formed into a molded article by the method. The molded article of the polyolefin resin composition obtained by the method of the present invention does not generate gel in the molded article, has good surface appearance and weld appearance, and has excellent mechanical properties and heat resistance. . EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples. Examples 1 to 8 and Comparative Example 1 Polypropylene having the kind and amount shown in Table 1 and fibrous calcium carbonate having the amount shown in Table 1 and other components shown in Table 1 were used as follows. Kneaded. In addition, the fibrous calcium carbonate A used in the examples is shown in FIG.
), And the fibrous calcium carbonate B clearly had a fibrous morphology as shown in the electron micrograph of FIG. 3B (magnification: 3,000). This was performed using a twin-screw kneader (TEM-35: manufactured by Toshiba Machine Co., Ltd.) 1 shown in FIG.
Separate constant supply of polypropylene and other components to the first material supply port 2 located far from the extrusion port of the twin-screw kneader 1 and fibrous calcium carbonate to the second material supply port located near the extrusion port. Each machine supplied. The kneading temperature was 200 ° C. and the screw rotation speed was 500 r. p. m. Set to the first
When the polypropylene supplied to the material supply port 2 reaches the position of the second material supply port 3, it is in a molten state, and fibrous calcium carbonate is added to the molten polypropylene and kneaded with the rotation of the screw. Then, the strand 4 was extruded from the extrusion port, and pellets were produced by a strand cutting method. 140 × 140 × by the injection molding machine using the pellets thus obtained
A 3 mm flat plate was prepared, the surface state of the flat plate was observed, and the state of dispersion of fibrous calcium carbonate and the presence or absence of silver were examined. The results are shown in Table 1. In addition, a test piece was prepared from a flat plate, and the bending strength (according to JIS K7203), flexural modulus (according to JIS K7203), and heat distortion temperature (according to JIS K6871) were measured. As shown in FIGS. 2A and 2B, the amount of warpage was measured by preparing a disk 5 having a thickness of 1.2 mm and a diameter of 100 mm by an injection molding method, and heating the disk 5 at room temperature 23 ° C. After standing for 48 hours, the maximum value of the warpage height h at both ends of the disk 5 was measured as the warpage amount. Table 1 shows the results of these measurements. In Comparative Example 1, calcium carbonate by weight was not separated, and it was difficult to measure physical properties. Examples 9 to 13 After the polypropylene and the plate-like inorganic filler were dry-blended in parts by weight shown in Table 2, the same twin-screw kneader as in Example 1 (TEM-35, manufactured by Toshiba Machine Co., Ltd.) Of the first material supply port, and one of the fibrous calcium carbonates is supplied to the second material supply port, and kneaded in the same manner as in Example 1 to obtain a polypropylene resin composition. Was measured. Table 2 shows the results. Comparative Examples 2 to 8 As shown in Comparative Example 1, calcium carbonate having a form other than fibrous calcium carbonate has poor dispersibility. Therefore, calcium carbonate of the type shown in Table 1 was used (Comparative Examples 2 to 4). ) Or calcium carbonate of the type shown in Table 1 and other components, and after the calcium carbonate was dry-run with polypropylene, it was supplied to the first material supply port. The results are shown in Table 1. Comparative Examples 9 and 10 Polypropylene and a flat inorganic filler were dry-blended to a predetermined amount shown in Table 2 and then supplied to a first material supply port of a twin-screw kneader (TEM-35, manufactured by Toshiba Machine Co., Ltd.). The mixture was kneaded to obtain a polypropylene resin composition, and a flat plate was prepared therefrom, and the physical properties were measured. Table 2 shows the results. As is clear from Table 1, the polypropylene resin compositions containing polypropylene and fibrous calcium carbonate in Examples 1 to 8 were mixed with the amorphous, cubic, or spindle-shaped calcium carbonates in Comparative Examples 1 to 8. The flexural strength, flexural modulus and impact strength are significantly higher, the heat distortion temperature is higher, the appearance is better, and the physical properties are better balanced than the polypropylene resin composition. Further, the polypropylene resin compositions of Examples 9 to 13 in Table 2 in which the polypropylene, the fibrous calcium carbonate and the plate-like inorganic filler are blended are excellent in the above-mentioned physical properties and small in the amount of warpage. it is obvious. [Effect of the Invention] The present invention is a polyolefin resin composition in which fibrous calcium carbonate is blended with polyolefin, and a polyolefin resin composition in which fibrous calcium carbonate and an inorganic filler having a plate-like form are blended with polyolefin. The molded product obtained therefrom has the well-balanced physical properties of high rigidity, high strength and high heat that could not be expected from the molded product made of polyolefin resin containing conventional specific fibrous calcium carbonate. It has a high degree of appearance, good appearance and good weldability, small warpage, can be manufactured at low cost, and can be an excellent material. Therefore, it can be used as a member for automobiles and can be usefully used in the fields of electric and electronic devices, general industrial products and daily necessities.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a twin-screw kneader for obtaining a polyolefin resin composition, FIG. 2A and FIG. 2B show explanatory views of a method for measuring the amount of warpage, and FIG. FIGS. 3A and 3B are micrographs showing fibrous calcium carbonate, which are substitutes for drawings.

Claims (1)

Claims: (1) 30 to 95% by weight of a polyolefin and 5 to 70% by weight of fibrous calcium carbonate having a fiber diameter of 3 μm or less are obtained by mixing the weight% of the polyolefin with the weight% of the fibrous calcium carbonate. The poly is contained so that the total is 100 and is in a molten state.
A polyolefin resin composition obtained by adding the fibrous calcium carbonate to an olefin and kneading the mixture . (2) 30 to 90% by weight of polyolefin, 5 to 50% by weight of fibrous calcium carbonate having a fiber diameter of 3 μm or less, and 5 to 30% by weight of an inorganic filler having a plate-like form,
The poly total contained so that the 100, and the molten state of the weight percent weight percent and the inorganic filler of the fibrous calcium carbonate to the weight% of the polyolefin
A polyolefin resin composition obtained by adding the fibrous calcium carbonate to an olefin and kneading the mixture .