JPH0753842A - Resin composition for automotive instrument panel - Google Patents

Abstract

PURPOSE:To obtain an automotive instrument panel having well-balanced mechanical strengths, good appearance of a molded material and moldability. CONSTITUTION:The resin composition for an automotive instrument panel comprises (A) 100 pts.wt. of a propylene-ethylene block copolymer having 2-5wt.% bonded ethylene content and 5-15g/10min. MFR, (B) 2-13 pts.wt. of styrene-ethylene-buthylene-styrene block copolymer having 15-20wt.% bonded styrene content and 8-15g/10min. MFR (230 deg.C, 2.16kg), (C) 5-16 pts.wt. of ethylene-propylene-ethylidene norbornene terpolymer rubber and (D) 20-32 pts.wt. of surface-treated talc by a compound of formula (RCOO)nM (R is a monofunctional hydrocarbon, etc., having 250-500 molecular weight; M is Li, Ca etc.; (n) is valency of M).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for a vehicle instrument panel, which is composed of a propylene resin composition reinforced with a filler. Furthermore,
Specifically, a propylene-based rubber obtained by kneading a specific styrene-based rubber, an ethylene-based rubber, or talc into a specific crystalline propylene / ethylene block copolymer (hereinafter sometimes simply referred to as “PP”). The present invention relates to a resin composition for a vehicle instrument panel, which is made of a resin composition and has excellent mechanical strength and moldability (including mold contamination).

[0002]

2. Description of the Related Art Conventionally, a propylene-based resin composition in which talc and various rubber components are compounded and reinforced has an excellent mechanical strength, moldability, and economical efficiency. It is offered to the panel. Under such circumstances, when further satisfactorily moldability, high mechanical strength balance, and quality for good appearance of molded products are required, in the past, talc was made into fine particles and ethylene / propylene copolymer rubber components were used. Attempts have been made to improve the composition by adding a dispersant such as a metal salt or wax. However, the above-mentioned talc microparticulation causes deterioration of strength and appearance due to secondary aggregation. In addition, compounding the above rubber components not only increases the cost but also lowers the heat resistance. Furthermore,
Addition of the above existing dispersants has problems such as contamination of the mold. That is, the mechanical strength balance between rigidity (heat resistance) and impact strength is low,
Designed by instrument panel design because flow marks (corrugated flow pattern) were generated in the injection molded instrument panel product, the mold was contaminated, and its moldability (fluidity) was low level. In many cases, it hindered the improvement of the degree of freedom and productivity.

[0003]

The object of the present invention is to have a high level of moldability (fluidity, appearance of a molded product) and mechanical strength balance (rigidity, impact strength) while being lightweight, and Another object of the present invention is to provide an automobile instrument panel using a talc-containing propylene-based resin composition in which mold contamination is suppressed.

[0004]

[Means for Solving the Problems]

[Summary of the Invention] The present inventors have conducted various studies in order to achieve the above object, and as a result,
Ethylene block copolymer, styrene elastomer,
By molding a propylene-based resin composition comprising an ethylene-based elastomer and treated talc by a conventional method, mold contamination is suppressed, the appearance of the molded product is good despite its light weight, and a high-level machine. The present invention has been completed by finding that an automobile instrument panel having a dynamic strength balance can be obtained.

That is, the resin composition for an automobile instrument panel of the present invention is characterized by comprising the following components (a) to (d). Component (a): Propylene / ethylene block copolymer having ethylene content of 2 to 5% by weight, room temperature xylene soluble content of 4 to 8% by weight, and MFR of 5 to 15 g / 10 min: 100 parts by weight (b ) Component: bound styrene amount 15 to 20%, number average molecular weight (Mn) 40,000 to 80,000, MFR (230 ° C, 2.16 kg) 8 to 15 g / 10 minutes styrene / ethylene / butylene / styrene block. Copolymer: 2 to 13 parts by weight (c) Component: Mooney viscosity ML _{1 + 4} 100 ° C. 85 to 90, iodine value 20 or less, and ethylene / propylene / ethylidene norbornene ternary with ethylene content of 71 to 74% by weight Copolymer rubber (EPDM): 5 to 16 parts by weight (d) Component: General formula (RCOO) nM (where R is a monovalent hydrocarbon group having a molecular weight of 250 to 500 or a hydroxy group-containing component) An amount of 250 to 500 monovalent hydrocarbon groups, M represents a lithium, calcium, strontium or barium atom, and n represents the same number as the valence of M). Talc having an average particle size of 2 to 5 μm, which is surface-treated by using 0.1 to 3 parts by weight per 100 parts by weight, measured by a laser light scattering type particle size distribution meter: 20 to 32 parts by weight

[Detailed Description of the Invention] [I] Propylene-based resin composition (1) Constituent component (a) Propylene / ethylene block copolymer (component (a)) Propylene / ethylene block copolymer of the above-mentioned component (a) The polymer is a stereoregular polymer obtained by block copolymerization using a highly stereoregular catalyst such as a Ziegler-Natta type catalyst, and has an ethylene content of 2 to 5% by weight and room temperature xylene. Soluble content is 4 to 8% by weight, and MFR
Is 5 to 15 g / 10 minutes. [Measurement method] Here, the measurement of the room temperature xylene-soluble component is 2 g.
The sample was immersed in 600 ml of boiling xylene for 20 minutes to dissolve it, then cooled to room temperature, filtered with a G4 type glass filter, dried, and back-calculated from the solid phase weight determined to determine the value. Further, the measured value of ethylene content can be obtained by a conventional method using infrared spectrum analysis or NMR.
The value of the above MFR is JIS-K7210 (230 ° C., 2.
16 kg). This (a)
If the total ethylene content or room temperature xylene solubles of the component propylene / ethylene block copolymer is less than the above range, the impact resistance is poor, and if the ethylene content or room temperature xylene solubles exceeds the above range, the heat resistance is low. Inferior. Also, MF
If the R (230 ° C., 2.16 kg) is less than the above range, the appearance of the molded product is poor, and if it exceeds the above range, the impact strength is poor. Further, the MFR of this block copolymer is adjusted to an MFR value within the above range only by changing the polymerization conditions. For example, the MFR value is adjusted by degrading with a peroxide such as dialkyl peroxide. If it is set, the appearance of the molded product is deteriorated, which is not preferable.

(B) Styrene / ethylene / butylene / styrene block copolymer (component (b)) As the styrene / ethylene / butylene / styrene block copolymer of the component (b), the amount of bound styrene is 15 to 2
0%, number average molecular weight 40,000-80,000, MF
R (230 ° C., 2.16 kg) 8 to 15 g / 10 min styrene elastomer. Here, when the bound styrene amount / number average molecular weight / MFR value is outside the above range,
The performance of the molded product is particularly inferior in impact strength. Furthermore,
The vinyl content of the elastomer (1,2-bond content of hydrogenated polybutadiene portion) is preferably 30 to 50%. The weight average molecular weight / number average molecular weight (Mw / Mn) of the elastomer is preferably within the range of 1.3 to 2.5. The bound styrene amount, number average molecular weight, weight average molecular weight / number average molecular weight, vinyl amount (1,2-bond amount of hydrogenated polybutadiene portion) can be determined by infrared spectrum analysis, gel permeation chromatography (GPC), It is a value measured by a conventional method such as NMR. The method for producing the styrene / ethylene / butylene / styrene block copolymer used in the present invention is not particularly limited and is generally produced by partially hydrogenating a styrene / butadiene / styrene copolymer. can do.

(C) Ethylene / propylene / ethylidene norbornene terpolymer rubber (component (c)) The ethylene / propylene / ethylidene norbornene terpolymer rubber of component (c) above has a Mooney viscosity (M
L _{1 + 4} , 100 ° C.) 85-90, iodine value 20 or less, and ethylene content 71-74 wt%. Here, the ethylene content is a value measured by an infrared spectrum analysis method, NMR and the like. If the Mooney viscosity of this copolymer rubber is less than the above range, the gloss is high and unsuitable.
If the content exceeds the above range, the appearance, particularly the flow mark, is poor and is not suitable.

(D) Talc (Component (d)) The talc of the above component (d) constituting the resin composition for automobile instrument panels of the present invention is talc 100.
Average particle size measured by a laser light scattering type particle size distribution meter, which was used in a ratio of 0.1 to 3 parts by weight per part by weight and which was surface-treated with the compound represented by the above general formula (RCOO) nM Of 2 to 5 μm. The talc to be subjected to the surface treatment is, for example, crushed talc ore with an impact type pulverizer or a micron mill type pulverizer, and further a micron mill,
After finely pulverized with a jet pulverizer, it is manufactured by classifying and adjusting with a cyclone or micron separator. Here, it is preferable to use the raw stone produced in China, which has less metal impurities.
The average particle diameter of talc is a value measured by a laser light scattering type particle size distribution meter, and as a measuring device, for example, LA-500 manufactured by Horiba Ltd. is preferable because it has excellent measurement accuracy. When talc having an average particle size exceeding the above range is used, the mechanical strength balance of the instrument panel for automobiles is poor. The balance is rather deteriorated, which is not preferable. Examples of the compound represented by the above general formula (RCOO) nM include arachidic acid, behenic acid, cerotic acid, montanic acid, melissic acid, abietic acid, dextropimaric acid,
Mention may be made of metal salts of organic acids such as hydroxystearic acid. Specific examples include lithium behenate, lithium montanate, lithium hydroxystearate, calcium behenate, calcium montanate, calcium hydroxystearate, strontium behenate, barium behenate, barium montanate, and barium hydroxystearate. You can Among these, calcium salts and barium salts are preferable, and calcium salts are particularly preferable. Other than the above metal salts, the effect of suppressing die contamination, the high level mechanical strength balance, and the good moldability cannot be achieved.

[Surface treatment] The surface treatment method of talc using these metal salts is not particularly limited. For example, a predetermined metal salt and talc to be treated are stirred in a high speed mixer, or with a dispersion medium, a solvent or the like. Examples thereof include a method of spraying or mixing the diluted or melted metal salt on the talc to be treated. The surface treatment is preferably a method of previously treating talc with the metal salt as described above.
In the step of kneading the components (a) to (d), the surface treatment agent can be added together with the untreated target talc and other components.

Component (e): Other optional compounding components The resin composition for an automobile instrument panel of the present invention is colored, if necessary, in addition to the above essential components (a) to (d). Therefore, a pigment may be blended, and additional components such as an antioxidant, a processing stabilizer, and a light stabilizer may be added to further improve the performance.

(2) Amount ratio In the resin composition for an automobile instrument panel of the present invention, the amount ratio of each of the above essential components (a) to (d) is important, and the above (a) to (d) ) Among the essential components of the above, (a)
100 parts by weight of the propylene / ethylene block copolymer as a component is used as a blending standard. Styrene of component (b)
The amount of the ethylene / butylene / styrene block copolymer to be blended is 2 to 13 parts by weight per 100 parts by weight of the propylene / ethylene block copolymer of the component (a). If the compounding amount of the styrene / ethylene / butylene / styrene block copolymer as the component (b) is less than the above range, the impact strength will be poor, and if it exceeds the above range, the heat resistance rigidity and the appearance of the molded product will be poor. Appropriate. The blending amount of the ethylene / propylene / ethylidene norbornene terpolymer rubber (EPDM) as the component (c) is 5 to 16 parts by weight per 100 parts by weight of the propylene / ethylene block copolymer as the component (a). is there. If the compounding amount of the ethylene / propylene / ethylidene norbornene terpolymer rubber (EPDM) as the component (c) is less than the above range, the rigidity (heat resistance) and dimensional stability of the molded product will be poor, and if it exceeds the above range, the resistance will be poor. It is not suitable because the impact resistance and the appearance of the molded product will be deteriorated. The blending amount of the talc as the component (d) is 20 to 32 parts by weight per 100 parts by weight of the propylene / ethylene block copolymer as the component (a). If the blending amount of the talc as the component (d) is less than the above range, the rigidity (heat resistance) of the molded product is poor, and if it exceeds the above range, the weight of the molded product itself becomes heavy, and the impact resistance and the molded product are also increased. It is unsuitable because the appearance becomes inferior. The total amount of the components (b) and (c) is preferably 13 to 21 parts by weight per 100 parts by weight of the component (a) from the viewpoint of impact resistance and heat resistance.

[II] Production of Propylene Resin Composition A propylene resin composition is prepared by blending and kneading the components (a) to (d) described above, and optionally the component (e) in the above amount ratio. It can be manufactured. The compounding / kneading of each of these components is generally obtained by kneading and granulating using a normal kneader such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender plastograph, and a kneader. is there. In this case, it is preferable to select a kneading and granulating method in order to improve the dispersion of each component, and usually, the kneading and granulating is performed using a twin-screw extruder. At this time, each of the components (a) to (d) may be kneaded at the same time, or each component is divided in order to improve the performance, for example, first, a part of the component (a) and the component (b) or It is also possible to knead all and then knead and granulate the remaining components. Also, as mentioned above,
At the time of kneading each of the components (a) to (d), a surface treating agent may be mixed to carry out the kneading of the components (a) to (d) and the surface treatment at the same time.

[III] Molding of Propylene-Based Resin Composition For automobile instrument panels, the above-mentioned propylene-based resin composition is molded into various resins by a conventional method, that is, injection molding, compression molding, extrusion molding (sheet molding, It is manufactured by molding by blow molding or the like, but among these various molding methods, it is most preferable to perform injection molding or injection compression molding (press injection) from the viewpoint of exhibiting effects. This automotive instrument panel not only has a high level of mechanical strength balance, good appearance and moldability (fluidity), but can also suppress mold contamination and has excellent paintability and Since dimensional stability can be exhibited, it has sufficient performance for practical use as a material suitable for high functionality and large size.

[0015]

EXAMPLES The present invention will be described in more detail with reference to experimental examples. The evaluation method performed here is as follows. [I] Evaluation method (1) Evaluation by test piece (test piece) [Moldability] Molding (fluidity) length of a spiral test piece (two-row type) having a cross-sectional shape with a fluidity width of 14 mm and a thickness of 2.5 mm ( Average value)
Was measured. The molding was carried out using an IS-170 type injection molding machine manufactured by Toshiba Machine, and the molding conditions were 230 ° C and 700 kg / c.
It was carried out at m ² . Observation of Appearance / Flow Mark The above spiral test piece was injection-molded, and its appearance (flow mark) was visually observed. Judgment 1st class: hardly recognized 2nd class: slightly recognized but practically acceptable. Grade 3: Clearly recognized, practically difficult. Grade 4: Remarkably recognized. Mold contamination 100 mm in length and 100 mm in width by the above injection molding machine, thickness 3
mm sheet was continuously molded under the condition of 220 ° C. and 600 kg / cm ^{2 at} a filling rate of about 50% of its basis weight, until mold contamination (white cloudy pattern) began to appear at the end of the filled resin. The number of shots was observed. The larger this value is, the better the effect of suppressing die contamination is. Mitsuzawa Measured according to JIS-Z8741.

[Mechanical Strength Evaluation] With the above injection molding machine,
Test pieces for measuring density, flexural modulus and IZOD impact strength were molded at a molding temperature of 230 ° C. and measured under the following conditions. The density was measured according to JIS-K7112. Flexural modulus was measured according to JIS-K7203. Measurement temperature is 2
It is 3 ° C. This measurement value is also a measure of heat resistance. IZOD impact strength Measured according to JIS-K7110 (cutting notch). The measurement temperature is 23 ° C.

[0017] (2) Evaluation by the instrument panel [moldability] moldability table the material formulation shown in the first embodiment and the comparative example, the current actual instrument panel mold are industrially used Using an injection molding machine (IS-2500D manufactured by Toshiba Machine Co., Ltd.
In N), the actual injection molding process was performed and the degree of filling of the molten resin into the mold was judged. ◯: Satisfactory Δ: Slightly satisfied ×: Unsatisfactory mold stain resistance 50 shot continuous molding was performed in the above mold, and it was observed whether mold contamination could be seen at the end of the resin filled by the mold. ○: Contamination No ×: determining the appearance of the observed flow marks the surface appearance of the instrument panel mold molded by using a contamination appearance the mold seen. ○: Satisfied △: Slightly satisfied ×: Not satisfied

[Mechanical Strength] Heat Deformation Resistance The instrument panel molded with the above-mentioned mold is attached to a cut model of a vehicle and put into a high temperature tank, atmosphere temperature is 85 to 92 ° C., product surface temperature (black panel). 11
The maximum change in the front end of the product after irradiation at 5 ° C. for 4 hours was measured. ◯: The maximum change amount is less than 3 mm from the standard (initial) X: The maximum change amount is 3 mm or more from the standard (initial) Impact resistance Impact based on the test conditions of MVSS-201 and ECE21 Was attached to the cut model, and the generated deceleration was measured and the hit part was observed. ◯: The generated deceleration does not exceed 80 g continuously for 3 ms or more,
Moreover, no sharp edge appears at the hit point. X: The generation deceleration exceeds 80 g continuously for 3 ms or more.
Or, a sharp edge appears at the hit point.

[II] Experimental Examples Examples 1 to 3 and Comparative Examples 1 to 4 The following (a) component (powder), (b) component, (c) component and (d)
The components were mixed in the proportions shown in Table 1, and tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane was added to (a) to (d).
0.08 parts by weight and 0.07 parts by weight of di-stearyl-thio-di-propionate were added to 100 parts by weight of the total amount of the components, and they were sufficiently mixed with a high speed mixer. Then, using a high-speed twin-screw extruder manufactured by Kobe Steel, Ltd., after kneading and granulating under a temperature condition of 220 ° C., the obtained pellets were supplied to an IS-170 type injection molding machine. A test piece was molded and supplied to an IS-2500DN type injection molding machine to mold an instrument panel test piece, and the evaluation shown in Table 2 was performed. The evaluation results are shown in Table 2.

Component (a) Component a-1: ethylene content of 4% by weight, room temperature xylene-soluble content 6% by weight, MFR of 10 g / 10 min ethylene-propylene block copolymer a-2: ethylene content of 4% by weight. %, Room temperature xylene-soluble content 3% by weight, MFR 4 g / 10 minutes ethylene / propylene block copolymer (b) component b-1: bound styrene content 20%, number average molecular weight 55.0
00, MFR 12 g / 10 min, styrene / ethylene / butylene / styrene block copolymer with vinyl content 35% b-2: bound styrene content 35%, number average molecular weight 65.0
00, MFR 2g / 10 minutes, vinyl content 37% styrene / ethylene / butylene / styrene block copolymer (c) Component c-1: Mooney viscosity (ML _{1 + 4} , 100 ° C) 88, iodine value 14 and ethylene Ethylene / propylene / ethylidene norbornene ternary copolymer rubber (EPDM) with a content of 73% by weight c-2: Mooney viscosity (ML _{1 + 4} , 100 ° C) 23, ethylene / propylene copolymer rubber with an ethylene content of 73% by weight ( EPM) (d) component d-1: Substantially the entire length measured by a laser light scattering type particle size distribution analyzer is 15 μm or less, and the length is 1
The area of less than 0 μm is 99.5%, the average particle size is 2.9 μm,
Talc having an average aspect ratio of 6 is surface-treated (blended with a high-speed mixer) with 1 part by weight of calcium behenate per 100 parts by weight of the talc. d-2: 9% of the entire length measured by a laser light scattering type particle size distribution analyzer exceeds 15 μm, and the length is 10
Talc having 70.5% less than μm and an average particle size of 8.6 μm is surface-treated (blended with a high-speed mixer) with 2 parts by weight of magnesium stearate per 100 parts by weight of the talc.

As shown in Table 2, the automobile instrument panels injection-molded from the resin compositions having the compositions shown in Examples 1 to 3 are all lightweight and have good appearance and mechanical strength of molded articles. It had a balance, and the mold contamination was suppressed. On the other hand, in all of Comparative Examples 1 to 4, some or all of them were insufficient.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

The automobile instrument panel comprising the resin composition of the present invention has a propylene
Since an ethylene block copolymer, a specific styrene elastomer, an ethylene rubber and a specific treated talc whisker were used, the conventional molding polypropylene resin composition was used as a material for an "automotive instrument panel". In contrast, it has a high level of mechanical strength balance as well as good moldability and appearance of a molded product in which mold contamination is suppressed and which is rich in fluidity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masamasa Hamaura 1 Toho-cho, Yokkaichi-shi, Mie Prefecture Yokkaichi Research Institute, Mitsubishi Petrochemical Co., Ltd. Chome 1910, within Kansei Co., Ltd. (72) Inventor Katsunori Arai, 2-1919, Nisshincho, Omiya City, Saitama Prefecture Within Kansei, Inc.

Claims (1)

[Claims] 1. A resin composition for an automobile instrument panel, comprising the following components (a) to (d). Component (a): Propylene / ethylene block copolymer having ethylene content of 2 to 5% by weight, room temperature xylene soluble content of 4 to 8% by weight, and MFR of 5 to 15 g / 10 min: 100 parts by weight (b ) Component: bound styrene amount 15 to 20%, number average molecular weight (Mn) 40,000 to 80,000, MFR (230 ° C, 2.16 kg) 8 to 15 g / 10 minutes styrene / ethylene / butylene / styrene block. Copolymer: 2 to 13 parts by weight (c) Component: Mooney viscosity ML _{1 + 4} 100 ° C. 85 to 90, iodine value 20 or less, and ethylene / propylene / ethylidene norbornene ternary having an ethylene content of 71 to 74% by weight. Copolymer rubber (EPDM): 5 to 16 parts by weight (d) Component: General formula (RCOO) nM (where R is a monovalent hydrocarbon group having a molecular weight of 250 to 500 or a hydroxy group-containing component) An amount of 250 to 500 monovalent hydrocarbon groups, M represents a lithium, calcium, strontium or barium atom, and n represents the same number as the valence of M). Talc having an average particle size of 2 to 5 μm, which is surface-treated by using 0.1 to 3 parts by weight per 100 parts by weight, measured by a laser light scattering type particle size distribution meter: 20 to 32 parts by weight