JPH03269036A - Polyolefin resin composition for injection molding - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a polyolefin resin composition that is suitable for injection molding, has dramatically improved flow characteristics, and has excellent impact resistance and rigidity.

In this specification, "injection molding 1" refers to a molding method that includes a step of injecting a resin into a mold, in which the mold is closed in advance to form a cavity, and then the resin is injected. In addition to general injection molding, resin is injected into an open mold and then molded products are obtained by compression molding, etc.
It also refers to methods that include injection compression molding (stamping mold, etc.) and injection processes using accumulators.

[Prior art and its problems] Conventionally, in order to increase the rigidity and impact resistance of polyolefin resins, propylene-ethylene block copolymers, ethylene-α olefin random copolymers, and inorganic fillers such as talc have been added to propylene-ethylene block copolymers. It was known to combine (
JP-A-6O-13838). However, when an ethylene-α olefin random copolymer having a higher viscosity, an inorganic filler, etc. are added to the propylene-ethylene broth copolymer, the molding fluidity of the composition is significantly reduced.

In melt molding such as injection molding and compression injection molding, materials with good fluidity have been desired to improve processability.

In order to improve this moldability, there are methods such as using a polyolefin resin that is a base material with a low molecular weight, or blending low molecular weight polyethylene wax or the like.

It is also known that in order to improve the fluidity of a polypropylene resin composition, an organic peroxide or the like is added and heat treated. However, this method has a problem in that the impact strength decreases significantly as the molecular weight decreases.

[Means for Solving the Problems] The gist of the present invention is that A) 100 parts by weight of polyolefin resin and B) filler.
1 to 70 parts by weight and C) a polyester plasticizer 1 to 20 parts by weight of an injection molding resin composition with improved fluidity.

The resin composition obtained by blending the above (A), (B), and (C) has greatly improved fluidity properties expressed by melt index, etc., and has excellent material properties, especially the balance between rigidity and impact strength. An excellent resin composition is obtained, and by using this composition, melt moldability in injection molding, injection compression molding, etc. is significantly improved, and resin molding with excellent molded product appearance (gloss, flow marks) is achieved. product is obtained.

The invention will now be described in further detail.

The polyolefin resin used in the present invention includes propylene-ethylene block copolymer, propylene-ethylene random copolymer, polypropylene, ethylene homopolymer, and other propylene. It is an olefin copolymer.

These may be used alone or in combination of two or more. Preferably, a propylene-ethylene block copolymer and a blend of a propylene-ethylene block copolymer and an ethylene-propylene copolymer rubber are used.

Inorganic fillers that can be applied to the present invention include talc, calcium carbonate, glass fiber, silica, mica, barium sulfate, aluminum hydroxide, magnesium hydroxide, clay, diatomaceous earth, titanium oxide, carbon fiber, volasnite, dawsonite, Potassium titanate, ferrite, carbon black, antimony trioxide, molybdenum disulfide, kaolin, magnesium carbonate, calcium sulfate, zinc oxide, calcium oxide, magnesium oxide, alumina, asbestos powder, glass powder, shirasu balloon, heptaolide, silicic acid Clay, metal powder, etc. are used, and preferably talc, calcium carbonate, mica, barium sulfate, glass fiber, etc. are used. As the organic filler, cellulose-based powders such as wood flour and pulp are used.

These may be used alone or in combination. In addition, fillers can be left untreated or treated with various silane coupling agents, titanium coupling agents, higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid salts, or other surfactants. can be used.

The average particle size of the filler is generally 500 pm or less, preferably in the range of 0.05 to 300 μm, and particularly preferably in the range of about 0.1 to 50 □m. The blending ratio of filler can be selected depending on the application, and polyolefin resin 1
00 parts by weight, 1 to 70 parts by weight, preferably 10 parts by weight
-48 parts by weight, more preferably 15-40 parts by weight. If the amount of filler is too small, the composition will not have sufficient rigidity, and if it is too large, the fluidity during molding will decrease and the impact strength will be low.

Polyester plasticizers that can be used in the present invention include dibasic acids or tribasic acids such as adipic acid, azelaic acid, sebacic acid, phthalic acid, and trimellitic acid;
Examples include polyester compounds consisting of short-chain alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, and neopentyl glycol, long-chain alkylene glycols, and terminal-modified polyesters of these polyester compounds. As the above-mentioned terminal-modified polyester, those in which the ends of the above-mentioned polyester compound are modified with a C6-C13 alkanol and those modified with a 02-C18 alkane (or alkene) acid are used. Preferably, the terminal-modified polyester mentioned above is used, which is an ester of adipic acid and alkylene glycol modified with an alkanol. These plasticizers may be used alone or in combination, and are blended in an amount of 1 to 20 parts by weight, preferably 3 to 12 parts by weight, per 100 parts by weight of the polyolefin resin. When the amount of plasticizer blended is small, the effect of improving flow characteristics is small and the impact strength is also small.

On the other hand, if the amount is too large, the rigidity decreases significantly and the molded product often bleeds.

The resin composition of the present invention can be produced using a mixing machine such as a -screw extruder, a twin-screw extruder, or a Banbury mixer-1 heat roll. The components may be mixed simultaneously using a Blenku-Henschel mixer or the like, or may be mixed separately. Alternatively, the components may be simply fed to the extruder without being mixed in advance. Furthermore, in addition to these basic ingredients, antioxidants, lubricants, ultraviolet absorbers, pigments, antistatic agents,
Additives such as flame retardants, nucleating agents, crosslinking agents, foaming agents, and metal soaps can be added.

[Effects of the Invention] A feature of the polyolefin resin composition obtained by the present invention is that although the fluidity characteristics are significantly improved by the polyester plasticizer, the impact strength is improved without decreasing the rigidity. Furthermore, since it has very excellent flow characteristics, it is possible to reduce the molding pressure during melt molding such as injection molding and injection compression molding, and it also facilitates the molding of thin-walled products.

In addition, in the above-mentioned injection compression molding, a stretchable sheet is placed in the mold in advance, and the injected resin stretches the sheet and presses it against the inner surface of the mold, becoming integrated with the sheet and solidifying. However, due to the pressure reduction effect, the compression ratio of the sheet material can be reduced even when laminated with foamed sheets, etc., making it possible to produce high-quality products without deformation of the sheet. can get. Furthermore, due to its good fluidity, it is possible to obtain a product with good gloss, no flow marks, and an excellent molded appearance.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the Examples unless the scope thereof is exceeded.

Characteristic measurements were performed by the method shown below.

Melt index: Based on JIS K-6758.

Flexural modulus: 23 according to JIS K-7203
Measured at °C.

The test piece for measurement was molded using a screw in-line injection molding machine N70BII manufactured by Japan Steel Works, Ltd.

Izotsu impact strength (notched): Measured at 23°C in accordance with JIS K7110.

The test piece for measurement is for measuring flexural modulus. It was molded in the same way as the test piece.

Dirt drop impact (DuPont type): Measured at 23°C using a DuPont type dirt drop impact tester.

The receiver has a base diameter of 38φ Tip punch 1/41nch R Test piece size: 50φ diameter x 2mm thick disc The test piece for measurement is for measuring flexural modulus. It was molded in the same way as the test piece.

Bleed: The surface appearance of a test piece similar to that used in the DuPont dirt drop impact test was visually observed.

Evaluation was performed in the following three stages.

○ No bleed of plasticizer △ Slightly increased bleed of plasticizer × Severe bleed of plasticizer Examples 1 to 4 Resin, filler, and plasticizer were mixed and used in the proportions shown in Table-1. Specifically, the melt index is 47 (g
/10 minutes Propylene-ethylene copolymer (trade name Mitsubishi Polypro 8936J (diapolymer a not yet manufactured))
(referred to as A-1) and talc with an average particle size of 1.8 μm (trade name Micro Ace P-3 (manufactured by Nippon Talc)) (B-
1) and as a polyester plasticizer, adipic acid polyester with a viscosity of 3000 cps (25°C) and a molecular weight of approximately 1800 (product name Diasizer ■
D-623 (manufactured by Mitsubishi Kasei Vinyl ■)) (referred to as C-1) were mixed at the same time, and then heated at 180°C in a twin-screw extruder.
The mixture was melt-kneaded and granulated. After kneading, the granulated pellets were injection molded and their physical properties were measured. The physical property measurement results are shown in Table-2.

Example 5 A filler and a plasticizer were mixed and used in the proportions shown in Table-1. In Examples 1 to 4, instead of A-1, A-1
and Mooney viscosity ML 1+4 (100°C) is 24 ethylene-propylene copolymer rubber (trade name EP02P
(manufactured by Japan Synthetic Rubber ■)) (referred to as D-1) in a proportion of 93 parts by weight was used, but the same method as in Examples 1 to 4 was used. The physical property measurement results are shown in Table-2.

Examples 6 to 9 Resin, filler, and plasticizer were mixed and used in the proportions shown in Table-1. In Examples 1 to 4, instead of C-1, an adipic acid polyester (trade name Diasizer ■) with a viscosity of 200 cps (25°C) and a molecular weight of about 800 was used.
D-620 (manufactured by Mitsubishi Kasei Vinyl ■)) (referred to as C-2) was used, but the same method as in Examples 1 to 4 was used. The physical property measurement results are shown in Table-2.

Example i.

The resin, filler, and plasticizer were mixed and used in the proportions shown in Table 1. In Examples 1 to 4, instead of A-1, an ethylene-propylene block copolymer (trade name: Mitsubishi Polypro 8500J) having a melt index of 9.0 g/10 minutes was used.
(manufactured by Diapolymer ■)) (referred to as A-2) was used in the same manner as in Examples 1 to 4.

The physical property measurement results are shown in Table-2.

Comparative Examples 1 and 2 Resin and filler were mixed and used in the proportions shown in Table 3. Example 1 except that only resin A-1 and filler B-1 were mixed.
It was carried out in the same manner as in 4. The physical property measurement results are shown in Table 4.

Comparative Example 3 A resin, filler, and wax were mixed and used in the proportions shown in Table 3. In Examples 1 to 4, C-1 was replaced with C-1 having a viscosity of 180 cps (140°C) and an average molecular weight of 1
500 polyethylene wax (product name Sunwax 1)
71-P (manufactured by Sanyo Chemical Industries, Ltd.)) (referred to as E-1) was carried out in the same manner as in Examples 1 to 4. The physical property measurement results are shown in Table 4.

Comparative Example 4 A resin, filler, and wax were mixed and used in the proportions shown in Table 3. In Examples 1 to 4, C-1 was replaced with C-1 having a viscosity of 200 cps (160°C) and an average molecular weight of 4.
The test was carried out in the same manner as in Examples 1 to 4, except that 000 polypropylene wax (trade name: Viscol 550-P (manufactured by Sanyo Chemical Industries, Ltd.)) (referred to as E-2) was used. The physical property measurement results are shown in Table 4.

Comparative example 5 Fillers were mixed and used in the proportions shown in Table 3.

In Example IO, instead of A-2, A-2 and Mooney viscosity ML, +4 (100'C) are ethylene-propylene copolymer rubber (trade name EPO7P (Japan Synthetic Rubber (m))) (D-2 ) is 93 near (weight B)
It was carried out in the same manner as in Example 10, except that the plasticizer was blended at the ratio of . The physical property measurement results are shown in Table 4.

Comparative Example 6 A resin, a filler, and a plasticizer were mixed and used in the proportions shown in Table-3. Example 10 was carried out in the same manner as in Example 10 except that the parts by weight of the filler and plasticizer were changed.

The physical property measurement results are shown in Table 4.

Comparative Example 7 A resin, a filler, and a plasticizer were mixed and used in the proportions shown in Table-3. Examples 1 to 4 were carried out in the same manner except that the parts by weight of the plasticizer were changed.

The physical property measurement results are shown in Table 4.

Table-1 Table-3

Claims (1)

[Scope of Claims] 1) A polyolefin resin composition for injection molding, comprising A) 100 parts by weight of a polyolefin resin, B) 1 to 70 parts by weight of a filler, and C) 1 to 20 parts by weight of a polyester plasticizer. 2) The resin composition according to claim 1, wherein the polyester plasticizer is a polyester selected from the group consisting of oligoesters of adipic acid and alkylene glycol and modified polyesters obtained by modifying the ends of the oligoesters with alkanol.