JPH0627237B2 - Polypropylene resin composition for instrument panel - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polypropylene resin composition, and more specifically, it contains a crystalline ethylene-propylene copolymer as a main component and has a particularly good balance of rigidity and impact resistance. Good, good mechanical properties, can provide molded products with excellent appearance,
Moreover, the present invention relates to a polypropylene resin composition having excellent moldability, and can be used for large automobile parts, particularly instrument panels.

[Problems to be Solved by Conventional Techniques and Inventions] Conventionally, crystalline polypropylene has been used for various molded products that require physical properties such as rigidity and heat distortion resistance, but on the other hand, low temperature properties are not sufficient. Since it is a non-polar, highly crystalline polymer, it has poor impact resistance and paintability,
It has the drawback that it cannot be used in applications where rigidity, heat distortion resistance, impact resistance and paintability are required at the same time.

Impact resistance of the crystalline polypropylene, in order to improve the paintability, using a crystalline ethylene-propylene block copolymer as the crystalline polypropylene, further polypropylene composition blended with an amorphous ethylene-propylene copolymer, Alternatively, a polypropylene composition in which a crystalline ethylene-propylene block copolymer is blended with an amorphous ethylene-propylene copolymer and various polyethylenes has been proposed.

However, these conventionally proposed polypropylene compositions have a drawback that the properties inherent to the crystalline ethylene-propylene block copolymer, such as the rigidity and the heat distortion resistance, are deteriorated.

Then, as an invention intended to improve the drawbacks of the polypropylene composition proposed hitherto, JP-A-53-
The invention entitled "Impact Resistant Resin Composition" is described in Japanese Patent No. 64257. In this publication, crystalline ethylene-
A resin composition having improved low temperature impact resistance, which comprises a propylene block copolymer, an amorphous ethylene-α-olefin copolymer and talc is disclosed. In addition, the publication describes that the composition has significantly improved low-temperature impact strength, rigidity, and coatability as compared with the conventional crystalline ethylene-propylene block copolymer, and examples.
However, even with the above composition, the balance between rigidity and impact strength is not sufficient, and the appearance is also insufficient. Therefore, although the molded product obtained from the above composition can be used for some applications in which its appearance can be ignored, its appearance is also accompanied by mechanical properties such as various members for automobiles, particularly instrument panels. Not suitable for critical applications.

In addition, as a filler other than talc, various polypropylene compositions including a granular filler typified by calcium carbonate and a fibrous filler typified by glass fiber are disclosed. Is not improved enough,
In the fibrous filler, although the rigidity is significantly improved, the impact strength is lowered, and the surface appearance of the molded product is deteriorated, warped, and deformed. For example, Japanese Patent Application Laid-Open No. 62-91545 proposes a polyolefin resin composition comprising a polyolefin, a thermoplastic elastomer, a fibrous reinforcing material, talc and calcium carbonate. However, since the above composition contains calcium carbonate, a defective appearance such as silver is likely to occur during injection molding, and the effect of improving rigidity is also reduced. Further, in JP-A-61-69848, polypropylene resin, fibrous filler, talc,
A polypropylene resin composition composed of an elastomer has been proposed. However, the above-mentioned composition contains a large amount of fibrous filler, so that when a large automobile part is molded, the molded product is deformed.

Further, in Japanese Patent Application No. 62-324396, crystalline ethylene-propylene block copolymer, amorphous ethylene-
A polypropylene resin composition comprising a propylene copolymer, talc, and fibrous magnesium oxysulfate has been proposed, but the above composition lacks rigidity and is insufficient for molding large parts for automobiles.

Further, a technique of incorporating an olefin resin and a hydrogenated block copolymer used in the present invention into a composition is disclosed in JP-A-58-2.
No. 06644, JP-A-58-215446,
JP-A-59-223745, JP-A-60-166
Although already proposed in Japanese Patent Application Laid-Open No. 339, Japanese Patent Application Laid-Open No. 61-28547, Japanese Patent Application Laid-Open No. 61-28548, Japanese Patent Application Laid-Open No. 61-34047, Japanese Patent Application Laid-Open No. 61-34048, etc. All of the technologies have low rigidity because they contain a large amount of hydrogenated block copolymer and softening agent, and even when the amount of hydrogenated block copolymer is reduced to improve rigidity, The elongation becomes small, which is a problem. Therefore, as in the present invention, the crystalline ethylene-propylene block copolymer is mixed with a hydrogenated block copolymer, an amorphous ethylene-propylene copolymer, a surface-treated inorganic filler, and a specific fibrous filler. Therefore, it is completely different from the technical idea of improving the balance between rigidity and impact resistance, and providing a molded product with excellent paintability and appearance.

Further, JP-A-57-51735 discloses a crystalline ethylene-propylene block copolymer used in the present invention,
A composition containing a hydrogenated block copolymer and an amorphous ethylene-propylene copolymer has been proposed, but since it does not contain an inorganic filler, its heat distortion resistance and rigidity are low, and the object of the present invention is achieved. Can not do it.

Therefore, by molding the conventionally known polypropylene resin composition as described above, it is possible to obtain a molded product having a good balance of rigidity and impact strength, good mechanical properties, and good appearance and good moldability. It could not be used and could not be used for large parts for automobiles, especially for applications such as instrument panels.

[Means for Solving the Problems] Therefore, the present inventors have aimed to obtain a polypropylene resin composition that gives a molded product having a good balance of rigidity and impact strength, good mechanical properties, and excellent appearance. As a result of intensive research as a specific crystalline ethylene-propylene block copolymer, hydrogenated block copolymer, amorphous ethylene-propylene copolymer, granular form fibrous magnesium oxysulfate, surface-treated talc, and metal soap The present invention has been completed by finding that the above object can be achieved by obtaining a composition in which is blended in a specific ratio.

That is, the present invention provides (A) an ethylene content of 4 to 10% by weight, a boiling n-heptane insoluble content of polypropylene component of 95% by weight or more, and a room temperature p-
Crystalline ethylene-propylene block copolymer 57-79 with intrinsic viscosity (decalin, 135 ° C.) of 2 or more for xylene solubles, melt flow index of 3-30 g / 10 min.
%, (B) Both end blocks in the block copolymer consisting of both end blocks made of a polymer of an aromatic vinyl compound and an intermediate block made of a conjugated diene polymer are 1 in the copolymer.
A hydrogenated block copolymer having 0 to 40% by weight of which 10% or less is hydrogenated and 90% or more of the intermediate block is hydrogenated, and (C) an intrinsic viscosity (decalin, 135 ° C.)
1.5-3.5, Mooney viscosity ML _{1 + 4} (100 ° C) 4
The total amount of amorphous ethylene-propylene copolymer of 0 to 100 is 5 to 15% by weight, and the blending ratio (weight ratio) of (B) and (C) is in the range of 80/20 to 20/80. , (D) 15-25% by weight of surface-treated talc having an average particle size of 0.5 to 2.5 μm, (E) fiber diameter of 0.1 to 1.5 μm, aspect ratio of 70 to 1
50 to 50% by weight of fibrous magnesium oxysulfate in granular form, and (F) 0.2 with respect to 100 parts by weight of the total amount of (A) to (E).
Provided is a polypropylene resin composition for instrument panels, which comprises 0.5 to 0.5 parts by weight of metal soap.

Hereinafter, the present invention will be described in detail.

Component (A) The component (A) used in the present invention has an ethylene content of 4 to
10 wt%, preferably 5 to 8 wt%, boiling polypropylene n-heptane insoluble component of polypropylene component is 95 wt% or more, preferably 97 wt% or more, room temperature para-xylene soluble component (amorphous Intrinsic viscosity (decalin, 1 consisting of ethylene-propylene copolymer and low molecular weight polymer)
35 ° C.) is 2 or more, preferably 3.5 or more, and the melt flow index is 3 to 30 g / 10 minutes, preferably 3 to 10 g / 10 minutes.

In the present specification, the boiling of polypropylene component n
The term “heptane insoluble matter” refers to a boiling n-heptane insoluble matter of crystalline polypropylene (sometimes referred to as a matrix) used in a block copolymerization reaction.

When the boiling n-heptane insoluble content of the polypropylene component is less than 95% by weight, the flexural modulus of the molded article molded from the polypropylene composition becomes smaller, and the intrinsic viscosity of the room temperature para-xylene soluble component becomes smaller. (Decalin, 13
When (5 ° C) is less than 2, the Izod impact strength at -30 ° C of the molded product becomes small. When the melt flow index is less than 3 g / 10 minutes, the appearance of the molded product and the moldability of the polypropylene composition are deteriorated,
If it exceeds 30 g / 10 minutes, the impact resistance will decrease. In either case, the polypropylene resin composition cannot be used as a material for a molded product that is required to have excellent appearance at the same time as rigidity, heat distortion resistance, and impact resistance at low temperature.

The crystalline ethylene-propylene block copolymer is contained in the composition excluding the metal soap in an amount of 57 to 79% by weight, preferably 63 to 76% by weight. When the above content is less than 57% by weight, the flexural modulus of the molded product becomes small,
If it exceeds 79% by weight, the Izod impact strength at −30 ° C. becomes small. Two or more crystalline ethylene-propylene block copolymers may be used as long as the total amount thereof is within the above range. Further, unless deviating from the object of the present invention, a crystalline ethylene-propylene block copolymer modified by a grafting method with an unsaturated organic acid or its derivative added may be used.

Component (B) The base of the hydrogenated block copolymer used in the present invention is composed of an intermediate block (90 to 60% by weight) made of a conjugated diene polymer and both end blocks (10) made of an aromatic vinyl compound polymer at both ends thereof. Up to 40% by weight). Examples of the aromatic vinyl compound constituting the both end blocks include styrene, α-methylstyrene, styrene polymers such as chlorostyrene, and the molecular weight thereof is preferably 5,000 to 14,000 as a number average molecular weight. The styrene is particularly preferable as the aromatic vinyl compound. Examples of the conjugated diene constituting the intermediate block include butadiene, isoprene, and chloroprene, and the molecular weight thereof is 10,000 to 10,000 as a number average molecular weight.
Those of 300,000 are suitable, and butadiene is particularly preferable as the conjugated diene. Blocks at both ends are 1 in block copolymer
If it is less than 0% by weight, hardness and strength will be insufficient, and 40
If it exceeds 5% by weight, the impact resistance of the molded product becomes insufficient. Preferably both end blocks are 15 to 25% by weight.

By hydrogenating the block copolymer,
The hydrogenated block copolymer used in the present invention can be obtained. The hydrogenation rate of both end blocks during hydrogenation treatment is 10% or less,
The hydrogenation rate of the intermediate block is 90% or more. In particular, the hydrogenation rate of the intermediate block is preferably 95% or more, and when it is 90% or less, the weather resistance decreases. When the intermediate block is polybutadiene, its hydrogenated product has an ethylene-butylene copolymer structure, and when it is polyisoprene, it has an ethylene-propylene copolymer structure.

The hydrogenated block copolymer used in the present invention is easily available under the name of Kraton G (manufactured by Shell Kagaku).

Component (C) The amorphous ethylene-propylene copolymer used in the polypropylene resin composition of the present invention has a Mooney viscosity ML _{1 + 4} (100 ° C.) of 40 to 100, preferably 5
0 to 80. If the Mooney viscosity is less than 40, the rigidity of the molded product and the impact resistance at low temperature are deteriorated, and the appearance of the molded product is deteriorated. If it exceeds 100, uniform dispersion by kneading becomes difficult, Impact resistance decreases. Further, as this amorphous ethylene-propylene copolymer, a terpolymer containing a diene may be used unless it deviates from the object of the present invention.

The components (B) and (C) are 5 in the composition excluding metal soap.
˜15 wt%, preferably 7 to 12 wt%.
If the above content exceeds 15% by weight, the rigidity is insufficient,
Scratch resistance decreases. If it is less than 5% by weight, the impact resistance is lowered.

Furthermore, the weight ratio of component (B) to component (C) is 80/20 to 20/80, preferably 70/30 to 30/70.

If the above weight ratio exceeds 80/20, the impact resistance at low temperature is reduced and the appearance is also deteriorated. On the other hand, if the weight ratio is less than 20/80, the balance between rigidity and impact resistance becomes poor.

Regarding Component (D) The talc compounded in the present invention has an average particle size of 0.5 to 2.5.
It is important that it is μm, preferably 1.5-2.2 μm. If the average particle size of talc is less than 0.5 μm, the dispersibility of talc becomes poor. The average particle size is 2.5 μm
If it exceeds, the impact resistance of the molded product decreases. Further, the talc is contained in an amount of 15 to 25% by weight, preferably 16 to 22% by weight in the composition excluding metal soap. When the content is less than 15% by weight, the rigidity of the molded product is not sufficient, and when it exceeds 25% by weight, the appearance of the molded product is deteriorated.

The talc used in the present invention is surface-treated with various treatment agents.

As the surface treatment, for example, higher alcohol type, higher fatty acid type, diester type, fatty acid metal salt type, unsaturated organic acid or its derivative type (maleic anhydride type, acrylic acid type, etc.), silane coupling agent type, organic titanate system,
Chemical or physical surface treatment with various treating agents such as resin acid type and polyethylene glycol ether can be mentioned, and the treating agents are particularly preferably higher alcohol type and higher fatty acid type.

The amount of surface treatment is 0.2 to 3%, preferably 0.5 to 1.5% with respect to talc. If the surface treatment amount exceeds 3%, gas is generated during kneading, which makes the kneading difficult, or the rigidity of the composition decreases. On the other hand, if it is less than 0.2%, the appearance of the molded product is deteriorated.

Regarding component (E) The granular form fibrous magnesium oxysulfate of component (E) to be blended in the present invention has a fiber diameter of 0.1 to 1.5 μm.
m, preferably 0.1 to 0.7 μm, aspect ratio 7
It is important that it is between 0 and 150, preferably between 90 and 130. If the fiber diameter is less than 0.1 μm, the rigidity of the molded product will be insufficient, and if it exceeds 1.5 μm, the molded product will be deformed.
If the aspect ratio is less than 70, the rigidity of the molded product is insufficient, and if it exceeds 150, the molded product is deformed.

It is important that component (E) is in granular form. Conventional fibrous magnesium oxysulfate is cotton-like, the dispersion of fibers after kneading is poor, the aspect ratio becomes small,
Insufficient rigidity.

The granular form fibrous magnesium oxysulfate is produced as follows.

Magnesium hydroxide and sulfuric acid were dispersed in water as a slurry, and then hydrothermal reaction was carried out at 160 ° C. for 4 hours in a pressure vessel. After the reaction, the product is washed with water, filtered through a 100-mesh wire net, and dehydrated to a water content of 70 wt%. 3mm of this dehydrated cake
(Φ) is extruded with a granulator and dried to a water content of 1% or less to produce granular fibrous magnesium oxysulfate.

This granular form fibrous magnesium oxysulfate is contained in the composition excluding metal soap in an amount of 1 to 3% by weight, preferably 1.5 to 2.5% by weight.

If the content is less than 1% by weight, the rigidity of the molded product will be insufficient, while if the content exceeds 3% by weight, the molded product will be deformed, which is not preferable.

Regarding compounding and the like, what is further important in the present invention is that when the components (A), (B), (C), (D), and (E) are melt mixed, the total amount is 100 parts by weight. 0.2 to
It is to contain 0.5 parts by weight, preferably 0.2 to 0.4 parts by weight of metallic soap. If the content of the metallic soap deviates from the above range, the rigidity of the molded product will decrease.

Metal soap is M (OOCR) _n (M ... Ca, Ba, Mg,
Zn, etc., RCOOH ... higher fatty acid salts of various metals represented by stearic acid, lauric acid, octylic acid, etc., and specific examples thereof include magnesium stearate, calcium stearate, and zinc laurate.

Further, the polypropylene resin composition of the present invention has a high speed of 2
It is preferable to knead with an extruder such as a twin-screw extruder, a multi-vent twin-screw extruder, or a single-screw extruder. In the case of a high-speed twin-screw extruder, only the component (E) is added midway at the inlet of the single-screw extruder, In a multi-vent twin-screw extruder, it is necessary to adopt a kneading method that does not reduce the aspect ratio of the fiber, such as by side-feeding only component (E).

In order to further improve the performance of a molded article molded from the polypropylene composition of the present invention, an antioxidant, an ultraviolet absorber, a flame retardant, an electrostatic charge, at the time of mixing each component of the composition or after mixing each component. Inhibitors, pigments, etc. can also be added.

[Effects of the Invention] As described above, the polypropylene resin composition for an instrument panel of the present invention comprises a specific crystalline ethylene-propylene block copolymer, a hydrogenated block copolymer, and an amorphous ethylene-propylene copolymer. A coalescent product, a specific talc, and a specific granular form fibrous magnesium oxysulfate are blended, obtained by adding a specific metal soap during melt mixing, and a molded article made from the composition of the present invention is It has a good balance of rigidity and impact resistance and good scratch resistance, and can be suitably used for large automobile parts, especially for instrument panels of automobiles.

[Examples] Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

(Examples 1 to 4 and Comparative Examples 1 to 9) 0.2 parts by weight of a phenolic anti-aging agent was further added to each component shown in Table 1 below, and the mixture was added to a high-speed twin-screw extruder at 230 ° C. Kneaded and granulated. At this time, only the fibrous filler,
It was added with a metering feeder at the inlet of the single shaft of the high speed twin screw extruder. After kneading and granulation, test pieces for evaluation were molded by an injection molding machine and evaluated by the following test methods. The results are shown in Table 1.

(1) Izod impact strength Complies with ASTM D256.

(2) Flexural modulus According to ASTM D2853.

(3) Scratch resistance A resin composition is molded into a 100 mm x 100 mm x 3 mm (thickness) injection-molded sheet with a leather grain pattern, and this molded sheet is placed on a plate and the side of a 100-yen coin is vertically applied. Rubbing was performed at a speed of 50 mm / sec while applying a force of 3 kg, and the degree of whitening of the scratches was visually observed, and the following ranking was performed.

○ Friction area is not white and conspicuous △ 〃 Somewhat white × Conspicuous white (4) Appearance The surface of the test piece was visually observed.

○ Good appearance without silver and flow marks × Poor appearance with silver or flow marks (5) Deformation Injection molding the resin composition into a 100 mm () × 1.6 mm (thickness) mirror surface disk, After 48 hours from the molding, the disc was placed on a horizontal plate, one point on the circumference was pressed, and the height of the most floating part from the horizontal plate was measured.

The following were used as the compounding ingredients.

(A-1) Ethylene content 7.0% by weight, boiling n-heptane insoluble component of polypropylene component 97.7% by weight, room temperature p-
Crystalline ethylene-propylene block copolymer (A-2) ethylene content 6.8% by weight, polypropylene component insoluble in boiling n-heptane. 97.1% by weight, room temperature p-
Crystalline ethylene-propylene block copolymers (A-3) and (A-1) having a intrinsic viscosity of 4.4 for a xylene-soluble component and a melt flow index of 9 g / 10 min and having a boiling n-heptane-insoluble component of 94.0. % Crystalline ethylene-propylene block copolymer (A-4) (A-2) boiling n-heptane insoluble matter 92.2% crystalline ethylene-propylene block copolymer (B) shell Chemically made Kraton G1650 (C-1) Mooney viscosity ML _{1 + 4} (100 ° C) 69 amorphous ethylene-propylene copolymer (C-2) Mooney viscosity ML _{1 + 4} (100 ° C) 18 amorphous ethylene- Propylene copolymer (D-1) Talc having an average particle size of 1.9 μm surface-treated with a mixture of stearic acid and stearyl alcohol (D-2) Talc having an average particle size of 1.9 μm (E-) 1) Average fiber type 0.3 μm, aspect ratio 100 Granular form fibrous magnesium oxysulfate (E-2) (E-1) at and cotton form fibrous magnesium oxysulfate, as the metal soap was used magnesium stearate.

As is clear from the results shown in Table 1, the compositions of Examples 1 to 4 of the present invention all have good quality,
Good balance of rigidity and impact resistance, good scratch resistance,
Moreover, the appearance is good. On the other hand, the compositions of Comparative Examples 1 to 9 have problems in mechanical properties, scratch resistance, and appearance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location C08L 23:16 53:02) (72) Inventor Tomohiko Akagawa 3-chome, Tsukikoshinmachi, Sakai City, Osaka Prefecture Ube Industries, Ltd. Sakai Factory (72) Inventor Saburo Hineno, 3-1, Chikko Shinmachi, Sakai City, Osaka Prefecture Ube Industries Ltd. Sakai Factory, (72) Inventor, Shinji Katsui 3-chome, Chikko Shinmachi, Sakai City, Osaka Prefecture Address: Ube Industries, Ltd., Sakai Factory

Claims (1)

[Claims] 1. An (A) ethylene content of 4 to 10% by weight, a boiling n-heptane insoluble component of a polypropylene component of 95% by weight or more, and an intrinsic viscosity (decalin, 1) of a p-xylene soluble component at room temperature.
35 ° C) 2 or more, melt flow index 3 to 30 g
Block copolymer consisting of 57 to 79% by weight of a crystalline ethylene-propylene block copolymer for 10 minutes, (B) both end blocks made of a polymer of an aromatic vinyl compound and an intermediate block made of a conjugated diene polymer. Blocks at both ends in 1 in the copolymer
A hydrogenated block copolymer having 0 to 40% by weight of which 10% or less is hydrogenated and 90% or more of the intermediate block is hydrogenated, and (C) an intrinsic viscosity (decalin, 135 ° C.)
1.5-3.5, Mooney viscosity ML _{1 + 4} (100 ° C) 4
The total amount of amorphous ethylene-propylene copolymer of 0 to 100 is 5 to 15% by weight, and the blending ratio (weight ratio) of (B) and (C) is in the range of 80/20 to 20/80. , (D) 15-25% by weight of surface-treated talc having an average particle diameter of 0.5-2.5 μm, (E) fiber diameter of 0.1-1.5 μm, aspect ratio of 70-1
50 to 50% by weight of fibrous magnesium oxysulfate in the form of granules, and
A polypropylene resin composition for instrument panels, which comprises 0.5 to 0.5 parts by weight of metallic soap.