JP3362791B2 - 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 filler-filled polyolefin resin composition. More specifically, it realizes weight reduction while maintaining properties such as rigidity, heat resistance and linear expansion coefficient of the filler-filled polyolefin. The present invention relates to a polyolefin resin composition that is preferably used as a molding material for automobile interior parts.

[0002]

2. Description of the Related Art In recent years,
In the automobile industry, weight saving of a vehicle body for improving fuel efficiency is being studied for the purpose of reducing carbon dioxide in order to protect the global environment. One of the concrete measures is to reduce the weight of the filler-filled polyolefin, which is often used as a material for interior parts. However, the purpose of filling the filler (talc, mica, various fibers, etc.) is to maintain the rigidity and heat resistance required for the product. Therefore, if the filler content is simply reduced to reduce the weight, the rigidity, The heat resistance is lowered and the linear expansion coefficient is increased, which causes a problem in use. Therefore, it has been difficult to reduce the weight by reducing the amount of filler.

Therefore, in order to reduce the weight of the filler-filled polyolefin for automobile interior parts, several methods have been conventionally considered. For example, in order to reduce the weight of talc-filled polypropylene (the talc filling amount is 15 to 25% by weight), a method of filling mica having a higher rigidity improving effect than talc has been considered. However, this method still has the drawbacks that the effect of improving the rigidity is not sufficient, the effect of reducing the weight is small, and conversely, the impact strength and the appearance are significantly deteriorated. Further, it has been considered to mix glass fiber as a fibrous filler, but there is a problem that the interior parts for automobiles by this method have large deterioration of appearance and large warp deformation.
As a fibrous filler, it may be possible to mix milled fiber or wollastonite having a short fiber length, but these have a smaller effect of improving rigidity than talc. Further, it is possible to mix potassium titanate whiskers as a whisker-like filler, but the resin composition by this method is difficult to be colored and toned, and it is difficult to use for interior parts for automobiles where various hues are desired.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polyolefin resin composition which realizes weight reduction while maintaining physical properties such as rigidity, heat resistance and linear expansion coefficient.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a crystalline propylene-ethylene copolymer having high fluidity, high crystallinity and high impact resistance. Containing a specific polypropylene resin, a fibrous inorganic filler having a specific fiber diameter and a fiber length, and talc having a specific particle diameter in a specific ratio, a melt index of the composition, IZOD impact strength, When the specific rigidity is set to a specific value, it is possible to realize a significantly low specific gravity and an improved appearance while maintaining the rigidity, heat resistance, and linear expansion coefficient, which are the characteristics of the filler-filled polyolefin. Find that you can get things,
The present invention has been completed.

That is, the present invention provides the following component (A),
(B) and (C), and the blending amount of the (B) component and the blending amount of the (C) component are the following relational expression: 3% by weight-C ≦ B ≦ 12% by weight-CB: Compounding amount (wt%) C: While satisfying the compounding amount (wt%) of the component (C), the melt index is 10 to 50 g.
/ 10 minutes, IZOD (notched) impact strength 5.0 kg
Provided is a polyolefin resin composition having a specific rigidity F (F = flexural modulus / specific gravity) of 24000 kg / cm ² or more. (A) 88-97% by weight of a polypropylene resin having a crystalline propylene-ethylene copolymer or a blend thereof with a propylene homopolymer and having an ethylene content of 2-15% by weight, and (B) an average fiber diameter of 0.1 to 2 μm, average fiber length of 5
1 to 10% by weight of fibrous inorganic filler having an oil absorption of 350 ml / 100 g or more at 60 μm, and (C) talc having an average particle size of 0.5 to 10.0 μm by optical particle size distribution measurement using a centrifugal sedimentation method. 1-10 % by weight,

The present invention will be described in more detail below.
First, the characteristics, types and blending amounts of each component will be described. Component (A) In the resin composition of the present invention, the polypropylene resin used as the component (A) comprises a crystalline propylene-ethylene copolymer homopolymer or a blend of a propylene homopolymer and a crystalline propylene-ethylene copolymer. It is a thing. The polypropylene resin as the component (A) has an ethylene content of 2 to 15% by weight, preferably 3 to 10% by weight. If the ethylene content is less than 2% by weight, the impact strength will decrease, and if it exceeds 15% by weight, the rigidity and heat resistance will decrease.

Component (B) The fibrous inorganic filler used as component (B) has an average fiber diameter of 0.1 to 2 μm, preferably 0.2 to 1 μm, and an average fiber length of 5 to 60 μm, preferably 10 to 50 μm. And an oil absorption of 350 ml / 100 g or more, preferably 400 ml / 100 g or more. If the average fiber diameter is less than 0.1 μm, the dispersibility of the fibrous inorganic filler may be poor and the impact strength may be reduced. If it is 2 μm or more, the impact strength, rigidity and heat resistance may be reduced, and the appearance may be poor. become worse. If the average fiber length is less than 5 μm, the effect of improving rigidity and heat resistance is small, and if it is 60 μm or more, the impact strength is lowered. If the oil absorption is less than 350, fiber spreading will be poor and dispersion will be poor, impact strength will be reduced, and aggregates will occur on the surface of the molded product. The type of the fibrous inorganic filler used as the component (B) is not particularly limited, but the fibrous basic magnesium oxysulfate, in that the fibers are less likely to break and the toning is easy,
One or more selected from magnesium hydroxide and magnesium borate can be particularly preferably used. Also,
The fiber surface of the fibrous inorganic filler as the component (B) is preferably surface-treated with a fatty acid metal salt, especially magnesium stearate or sodium stearate, from the viewpoint of improving dispersibility.

Component (C) The talc used as the component (C) has an average particle size of 0.5 to 10 in the optical particle size distribution measurement by the centrifugal sedimentation method.
The thickness is 0 μm, preferably 0.8 to 2.0 μm.
If the average particle diameter is less than 0.5 μm, the dispersibility of talc may be deteriorated and the impact strength may be lowered.
If it exceeds 0 μm, not only the effect of improving the rigidity is small, but also the impact strength is lowered.

Blending amount The blending amount of the component (A) is 88 to 97% by weight, preferably 90 to 96% by weight based on the total amount of the components (A), (B) and (C). When the content of the component (A) is less than 88% by weight, the specific gravity of the composition may be increased, and the impact strength may be reduced, or the appearance may be poor or the warp may be deformed. If the amount of the component (A) compounded exceeds 97% by weight, the rigidity and heat resistance will decrease and the linear expansion coefficient will become too large.

Further, the blending amount of the component (B) and the blending amount of the component (C) need to satisfy all of the following relational expressions (1) to (3). 1% by weight ≤B≤10% by weight (1) 1% by weight ≤C≤10 % by weight (2) 3% by weight-C≤B≤12% by weight-C (3) [where B is (B ) Component is blended (wt%), C is the blending amount of component (C) (wt%). When the blending amount of the component (B) is less than 1% by weight, the effect of improving rigidity and heat resistance becomes small and the coefficient of linear expansion becomes large. If the blending amount of the component (B) exceeds 10% by weight, the impact strength may decrease and warp deformation may occur. When the blending amount of the component (C) exceeds 10% by weight, the impact strength is lowered, and flow marks or the like are generated, which may deteriorate the appearance. Further, the blending amount of the component (B) is [3
If it is less than wt% -C], the effect of improving rigidity and heat resistance is small and the linear expansion coefficient is large. When the blending amount of the component (B) exceeds [12% by weight-C], the specific gravity may increase and the impact strength may decrease, the appearance may decrease, and warp deformation may occur. The more preferable blending amount of the component (B) is 2 to 5% by weight, and the more preferable blending amount of the component (C) is 2 to 5% by weight.

Physical Properties of the Composition itself The polyolefin resin composition of the present invention has a melt index (MI) of 10 to 60 g / 10 minutes, preferably 15
~ 40 g / 10 minutes. If the MI is less than 10 g / 10 minutes, the composition may have poor fluidity, so that a thin and large product cannot be molded and the appearance of the product may deteriorate. Further, when the MI exceeds 60 g / 10 minutes, the impact strength decreases. The polyolefin resin composition of the present invention has an IZOD impact strength (notched) of 5.0 kgcm.
/ Cm or more, preferably 5.5 kgcm / cm or more. If the IZOD impact strength is less than 5.0 kgcm / cm, the product has insufficient impact strength as an automobile interior component, and its use is significantly limited. Further, the polyolefin resin composition of the present invention has a specific rigidity F represented by the following formula F = flexural modulus / specific gravity of 24000 kg / cm ² or more, preferably 25000 kg / cm ² or more. If the specific rigidity F is less than 24000 kg / cm ² , the product lacks rigidity, cannot be made thin, and the weight reduction is significantly limited.

In the resin composition of the present invention, 1 to 10 parts by weight, preferably 1 to 10 parts by weight, of an olefinic elastomer or a styrene-based elastomer is added to 100 parts by weight of the total amount of the components (A), (B) and (C). It is possible to add 2 to 8% by weight, whereby the impact strength can be further improved. In this case, if the added amount of the elastomer is less than 1 part by weight, the effect of improving the impact strength is small, and if it exceeds 10 parts by weight, the rigidity and heat resistance decrease.

Here, the olefin elastomer is not particularly limited, but for example, ethylene / propylene copolymer rubber (EPR), ethylene / propylene / diene copolymer rubber, ethylene-butene-1 copolymer, ethylene- Examples include propylene-butene-1 copolymer. Among these, ethylene / propylene copolymer rubber (EPR) is particularly preferably used. The styrene-based elastomer is not particularly limited, but for example, a styrene-ethylene / butadiene-styrene copolymer (SE
BS), styrene-butadiene-styrene copolymer (S
BS), styrene-isoprene-styrene copolymer (S
IS), styrene-butadiene copolymer (SBR) and the like. Among these, styrene-ethylene / butadiene-styrene copolymer (SEBS) is particularly preferably used.

Further, in the resin composition of the present invention, various kinds such as a pigment, a heat stabilizer, an antioxidant, an ultraviolet absorber, a dispersant, an antistatic agent, a release agent and a copper damage inhibitor may be added, if necessary. Additives can be added.

The method for producing the resin composition of the present invention is not particularly limited, and known methods can be adopted, but it is important to prevent the fiber from breaking. In particular, using a twin-screw extruder, the components (A) and (C) are quantitatively supplied to the hopper,
It is preferable that the components (A) and (C) are melt-kneaded, and then the component (B) is quantitatively supplied to the downstream portion of the twin-screw extruder and the components are kneaded again. The kneading is preferably performed at a temperature of about 180 to 240 ° C. Moreover, there is no limitation on the molding method of the resin composition of the present invention, and any molding method such as injection molding, extrusion molding, hollow molding, sheet molding, thermoforming, rotational molding, or laminated molding can be adopted. Injection molding is particularly suitable.

[0017]

EXAMPLES AND COMPARATIVE EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Examples 1 to 7 using the components shown in Table 1,
The resin compositions of Comparative Examples 1 to 8 were manufactured. Then, a test piece was prepared using the obtained resin composition, and a physical property test was conducted. The results are shown in Table 2.

In this case, the following components were used as the components shown in Table 1. A-1: MI = 30 g / 10 minutes, ethylene content = 6.
5% by weight of crystalline propylene-ethylene copolymer. A-2: MI = 20 g / 10 minutes, ethylene content = 8.
Blend A-3: 80% by weight of 7% by weight of crystalline propylene-ethylene copolymer and 20% by weight of propylene homopolymer with MI = 30 g / 10 min A-3: MI = 30 g / 10 min, ethylene content = 1 ．
6% by weight of crystalline propylene-ethylene copolymer. A-4: MI = 80 g / 10 minutes, ethylene content = 5.
2% by weight of crystalline propylene-ethylene copolymer. A-5: MI = 4 g / 10 minutes, ethylene content = 25.
5% by weight of crystalline propylene-ethylene copolymer.

Here, the MI and ethylene contents of the crystalline propylene-ethylene copolymer as the component (A) were measured as follows. It was measured according to MI ASTM D-1238. The ethylene content was determined from ¹³ C-NMR spectrum.

B-1: Fibrous basic magnesium oxysulfate having an average fiber diameter of 0.4 μm, an average fiber length of 21 μm and an oil absorption of 460 ml / 100 g B-2: an average fiber diameter of 0.6 μm, an average fiber length of 40 μm,
Fibrous magnesium borate B-3 having an oil absorption of 430 ml / 100 g: average fiber diameter 5.2 μm, average fiber length 80 μm,
Fibrous calcium silicate B-4 with an oil absorption of 230 ml / 100 g: average fiber diameter 0.4 μm, average fiber length 18 μm,
Fibrous basic magnesium oxysulfate with an oil absorption of 310 ml / 100 g

C-1: talc having an average particle size of 0.9 μm as determined by optical particle size distribution measurement using a centrifugal sedimentation method C-2: talc having the same average particle size of 1.4 μm C-3: the same average Talc having a particle diameter of 20.5 μm Here, the average particle diameter of the talc as the component (C) was specifically measured as follows. Measurement of average particle size The particle size distribution was determined by a light transmission type particle size distribution analyzer using the centrifugal sedimentation method, and the value of D ₅₀ was taken as the average particle size.

The production of each resin composition and the production of test pieces were carried out as follows. Production of Resin Composition After dry-blending a predetermined amount of propylene resin (A) and talc (C), a twin-screw kneader (manufactured by Toshiba Machine Co., Ltd. TEM-
35) was quantitatively supplied to the hopper and kneaded at 200 ° C.
On the other hand, the fibrous inorganic filler (B) was supplied in a predetermined amount to the midway portion (downstream from the resin melting portion) of the biaxial kneader. Thereby, pellets were obtained. Preparation of test piece The obtained pellet was injection-molded to form a test piece.

The physical property test was conducted as follows. Specific gravity Measured according to ASTM D-792. Flexural modulus was measured according to ASTM D-790. IZOD impact strength (with notch) It was measured according to ASTM D-256. HDT (High load) Measured in accordance with ASTM D-648. A flat plate having a surface appearance of 420 mm × 100 mm × 3 mm was formed, and the surface appearance was visually evaluated.

[0024]

[Table 1]

[0025]

[Table 2]

[Product Evaluation] Using the pellets obtained in Examples 1 to 3 and Comparative Examples 1 to 3, the shape shown in FIG.
An automobile interior part having a size (a front pillar having a thickness of 2.5 mm) was molded, and product evaluation was performed. The results are shown in Table 3.

The product evaluation test was conducted as follows. Drop ball impact test A 535 g steel ball was dropped on a product and evaluated by the height at which the product broke. The test temperature was 0 ° C and -30 ° C. It is to be noted that the product is basically required to have an ability to withstand an impact of 535 g × 500 mm or more at each temperature. Heat-resistant deformation test After leaving the product in an atmosphere of 80 ° C for 24 hours, taking it out, adjusting the condition at room temperature for 24 hours, fixing one side, and measuring the amount of lifting from the flat surface of the opposite end surface. The amount of deformation was calculated. The product is basically required to have a deformation amount of 1.00 mm or less. Measurement of coefficient of thermal expansion A test piece was cut out from the product and measured according to ASTM D-696.

[0028]

[Table 3]

[0029]

As described above, the polyolefin resin composition of the present invention achieves weight reduction and appearance improvement while maintaining the physical properties of the filler-filled polyolefin such as rigidity, heat resistance and linear expansion coefficient. Is.

[Brief description of drawings]

FIG. 1 is a plan view showing the dimensions and shape of a front pillar used in a product evaluation test.

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Claims (2)

(57) [Claims] 1. The following components (A), (B) and (C) (A) A crystalline propylene-ethylene copolymer or a blend thereof with a propylene homopolymer, wherein the ethylene content is 2 to 15% by weight. % Polypropylene resin 88-
97% by weight, (B) average fiber diameter of 0.1 to 2 μm, average fiber length of 5
1 to 10% by weight of fibrous inorganic filler having an oil absorption of 350 ml / 100 g or more at 60 μm, and (C) talc having an average particle size of 0.5 to 10.0 μm by optical particle size distribution measurement using a centrifugal sedimentation method. 1 to 10 % by weight, and the blending amount of the component (B) and the blending amount of the component (C) are the following relational expression: 3% by weight-C ≦ B ≦ 12% by weight-CB: The blending of the component (B) Amount (wt%) C: The blending amount (wt%) of the component (C) is satisfied, and the melt index is 10 to 60 g.
/ 10 minutes, IZOD (notched) impact strength 5.0 kg
A polyolefin resin composition having a cm / cm or more and a specific rigidity F (F = flexural modulus / specific gravity) of 24000 kg / cm ² or more. 2. The total amount 1 of the components (A), (B) and (C).
The polyolefin resin composition according to claim 1, wherein 1 to 10 parts by weight of an olefin elastomer or a styrene elastomer is added to 00 parts by weight.