JPH08302106A - Automotive instrumental panel - Google Patents

Abstract

PURPOSE: To obtain an automotive instrumental panel improved in low- temperature impact resistance and heat-resistant rigidity. CONSTITUTION: This automotive instrumental panel made of a material comprises 16-22wt.% product prepared by dynamically heat-treating a mixture comprising 10-50wt.% propylene homopolymer and/or ethylene/propylene block copolymer (the isotactic pentad fraction of the propylene homopolymer part is 0.98 or above) and 50-90wt.% olefin copolymer rubber in the presence of an organic peroxide and a crosslinking agent, 52-66wt.% propylene homopolymer and/or ethylene/propylene block copolymer (the isotactic pentad fraction of the propylene homopolymer is 0.98 or above, and its melt index is 30-150g/10min) and 18-26wt.% inorganic filler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automotive instrumental panel using a specific thermoplastic resin composition. More specifically, the present invention relates to an instrumental panel for automobiles, which uses a thermoplastic resin composition having excellent mechanical properties, particularly flexural modulus, heat resistance and impact resistance, and particularly excellent heat resistance.

[0002]

2. Description of the Related Art In recent years, ethylene-propylene block copolymers have been used as molding materials for automobile parts.
This ethylene-propylene block copolymer has a good balance of flexural modulus, heat distortion temperature, and impact strength, but has drawbacks such as low low-temperature impact strength for automobile bumpers. To improve the low temperature impact resistance, it is known to blend an ethylene-propylene copolymer rubber or the like with a propylene-ethylene block copolymer.
No. 2552, No. 53-40045, etc. However, since the ethylene-propylene copolymer rubber is compounded, the thermal properties such as flexural modulus and heat distortion temperature are inferior, and in order to solve this, calcium carbonate, barium sulfate, mica, crystalline calcium silicate and talc are further added. The addition of an inorganic filler such as
1-136735, 53-64256, 53-
64257, 57-55952, 57-207.
No. 630, No. 58-17139, No. 58-11184.
6, No. 59-98157, Japanese Patent Publication No. 55-3374, and the like. In recent years, a resin composition having improved flexural modulus, surface hardness and the like by increasing the isotactic pentad fraction of the propylene homopolymer portion of polypropylene or ethylene-propylene block copolymer is disclosed in JP-A-5-59251. , The same 5-23
It is proposed in Japanese Patent No. 0321. Further, it is proposed in JP-B Nos. 36-11240, 38-2126, and 41-21785 that the impact resistance is improved by blending a vulcanized rubber with an olefin-based plastic. However, when a vulcanized rubber is blended, the fluidity is lowered and the appearance is apt to be deteriorated. Therefore, a mineral oil-based softening agent or a peroxide non-crosslinking rubber-like substance is blended to improve the fluidity. 15740 and 5
It is proposed in Japanese Patent Publication No. 6-15743. Further, as a material having a good balance of impact strength and rigidity, JP-A-6-
145437 has been proposed. However, recently, there has been a demand for further improvement in heat resistance and rigidity of instrumental panels for automobiles. However, low temperature impact resistance and thermal rigidity are contradictory performances, and there is a limit in the conventional technology to improve thermal rigidity without impairing low temperature impact resistance.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, an object of the present invention is to provide an automotive instrumental panel using a specific polypropylene and a thermoplastic resin composition having improved low temperature impact resistance and heat resistance rigidity. Especially.

[0004]

Means for Solving the Problems The inventors of the present invention have continued research on improving impact resistance and heat resistance by dispersing an olefin copolymer rubber in polypropylene. As a result, a mixture of polypropylene and an olefinic copolymer rubber was dynamically heat treated in the presence of an organic peroxide and a cross-linking auxiliary agent, and melt-mixed with a specific polypropylene and an inorganic filler to obtain a low temperature resistance. We found that impact resistance and heat resistance can be improved at the same time,
The present invention has been completed. That is, in the present invention, the homopolymer of (I) (a) propylene and / or the ethylene-propylene block copolymer (provided that the homopolymerization portion of propylene has an isotactic pentad fraction of 0.98 or more). ) 10 to 50% by weight and (b) 50 to 90% by weight of an olefinic copolymer rubber, a heat-treated product 16 to 22% by weight which is dynamically heat-treated in the presence of an organic peroxide and a crosslinking auxiliary. And (II) propylene homopolymer and / or ethylene-propylene block copolymer (provided that the isotactic pentad fraction of the homopolymerized portion of propylene is 0.
98 or more and the propylene homopolymerization portion has a melt index (JIS-K-6758, 230 ° C.) of 30 to 1
It is 50 g / 10 min. ) 52 to 66% by weight, and (III) 18 to 26% by weight of inorganic filler, the instrumental panel for automobiles.

The present invention will be described in detail below. The (a) propylene homopolymer and / or ethylene-propylene block copolymer used in the present invention means a propylene homopolymer, that is, a propylene homopolymer, or an ethylene-propylene block copolymer, that is, a propylene homopolymer. The latter is a copolymer of ethylene and propylene. These may be used alone or in combination. The isotactic pentad fraction of the homopolymerized portion of propylene needs to be 0.98 or more.
If it is less than 0.98, it is difficult to obtain the rigidity and heat resistance required for the purpose of the present invention. The homopolymerized portion of propylene means a homopolymer of propylene, and ethylene-
Refers to both the propylene homopolymerization portion of the propylene block copolymer. The ethylene content of the ethylene-propylene copolymer portion in the ethylene-propylene block copolymer is 20 to 70% by weight, preferably 25 to 60.
% By weight. The melt index of such polymers is 1
The one having 1 to 30 g / 10 min is preferably used, and more preferably 12 to 20 g / 10 min. If the melt index is less than 11 g / 10 min, the fluidity of the composition will decrease. If it exceeds 30g / 10min,
This causes deterioration of mechanical properties.

The term "isotactic pentad fraction" as used herein means A. Zambelli et al., Macrom
olecules, 6 , 925 (1973), an isotactic chain at the pentad unit in the crystalline polypropylene molecular chain measured using ¹³ C-NMR, in other words a propylene monomer unit. It is the fraction of propylene monomer units at the center of a chain of five consecutive meso-bonds. However, regarding the attribution of the NMR absorption peak, Macro
molecules, 8 , 687 (1975). Specifically, the isotactic pentad fraction is measured as the area fraction of the mmmm peak in all the absorption peaks in the methyl carbon region of the ¹³ C-NMR spectrum. By this method, British PHY
SICAL LABORATORY NPL Reference Material C
RM No. M19-14 Polypropylen
The isotactic pentad fraction of ePP / MWD / 2 was measured and found to be 0.944.

In the ethylene-propylene block copolymer, the weight ratio X of the ethylene-propylene copolymer part to the whole block copolymer is such that the propylene homopolymerized part and the whole block copolymer have respective crystals. By measuring the heat of fusion, it can be calculated by the following equation. X = 1- (ΔHf) _T / (ΔHf) _P (ΔHf) _T : heat of fusion of the entire block copolymer (c
al / g) (ΔHf) _P : heat of fusion of homopolymerized portion of propylene (cal / g) The ethylene content is determined by the characteristics of the methyl group and the methylene group appearing in the infrared absorption spectrum measured by making a press sheet. By a calibration curve method using the absorbance of absorption. The ethylene content of the ethylene-propylene copolymer portion can be calculated by measuring the ethylene content of the entire block copolymer and calculating from the following equation. (C ₂ ') _EP = (C ₂ ') _T / X (C ₂ ') _T : ethylene content (% by weight) of the entire block copolymer (C ₂ ') _EP : ethylene of ethylene-propylene copolymer part Content (% by weight)

On the other hand, the olefin copolymer rubber (b) used in the present invention is a copolymer of ethylene and α-olefin or a terpolymer of ethylene, α-olefin and non-conjugated diene. . As the α-olefin, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1 and the like are used, and among them, propylene and butene-1 are preferable. Examples of the non-conjugated diene include chain non-conjugated dienes such as 1,4-hexadiene and 1,6-octadiene; 1,4-cyclohexadiene, dicyclopentadiene, 5-vinylnorbornene, 5-ethylidene-2-norbornene. Cyclic non-conjugated dienes such as; 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-
Trienes such as norbornene are mentioned, among which 1,
4-hexadiene, dicyclopentadiene and 5-ethylidene-2-norbornene are preferred. As the (b) olefin-based copolymer rubber, these are 2
It does not prevent you from using more than one kind.

(B) The ethylene content of the olefin copolymer rubber is 90 to 40% by weight, and the α-olefin is 10 to 6%.
0% by weight and the content of non-conjugated diene is 0 to 12% by weight. When the ethylene content is 90% by weight or more, the ethylene component is increased, so that the copolymer rubber exhibits crystallinity, and as a result, the low temperature impact resistance is lowered. If it is less than 40% by weight, the decomposition reaction by the organic peroxide proceeds too much,
This causes deterioration of mechanical properties and poor appearance of the molded product. The ethylene content is preferably 80-45% by weight. When the content of non-conjugated diene is 12% by weight or more, it becomes difficult to control the crosslinking reaction. The (b) olefin copolymer rubber has a Mooney viscosity (M
L _{1 + 4} 100 ° C.) is 10 to 100, preferably 20 to 8
Must be 0. When the Mooney viscosity at 100 ° C. is less than 10, mechanical properties are inferior, and when it exceeds 100, fluidity is inferior, resulting in poor appearance of the injection-molded product.

(B) Olefin-based copolymer in 100% by weight of a mixture of (a) propylene homopolymer and / or ethylene-propylene block copolymer in the present invention and (b) olefin-based copolymer rubber. The proportion of the united rubber is 50 to 90% by weight, preferably 60 to 80
% By weight. If it is less than 50% by weight, the crosslinking reaction by the organic peroxide does not proceed sufficiently and the mechanical properties are not improved. If it exceeds 90% by weight, thermoplastic properties are difficult to develop.

Examples of the organic peroxide used in the present invention include 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2,5-dimethyl-2,5-di (t).
-Butylperoxy) hexyne-3,1,3-bis (t
-Butylperoxyisopropyl) benzene, 1,1-
Specific examples thereof include di (t-butylperoxy) -3,5,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (peroxybenzoyl) hexyne-3, and dicumyl peroxide. However, it can be appropriately selected depending on the melt-kneading conditions. The addition ratio of organic peroxide is
0.02 to 1.0 with respect to 100% by weight of (a) + (b)
It can be selected in the range of parts by weight. If it is less than 0.02% by weight, the effect of the crosslinking reaction is small, and if it exceeds 1.0% by weight, it is difficult to control the crosslinking reaction.

Examples of the crosslinking aid used in the present invention include bismaleimide compounds such as N, N'-m-phenylene bismaleimide, toluylene bismaleimide, and p-
Polyfunctional compounds such as quinone dioxynium, nitrobenzene, diphenyl guanidine, trimethylol propane, ethylene glycol dimethacrylate can be used. N, N'-m-phenylene bismaleimide is
For example, commercially available Sumi Fine BM (Sumitomo Chemical Co., Ltd.), HV
A-2 (manufactured by DuPont) or the like can be used. The addition ratio can be selected in the range of 0.01 to 5.0% by weight with respect to 100% by weight of (a) + (b).
If it is less than 0.01% by weight, the effect on cross-linking is difficult to be exhibited, and if it exceeds 5.0% by weight, moldability is poor. It is preferably 0.05 to 4.0% by weight.

The heat-treated product of the present invention (sometimes called a dynamic heat-treated product) is (a) a homopolymer of propylene and / or
Or ethylene-propylene block copolymer (b)
It is obtained by dynamically heat-treating an olefin-based copolymer rubber in the presence of the above organic peroxide and a crosslinking aid. In the present invention, the method for dynamically performing heat treatment is 1
Melt kneading can be carried out in a temperature range of 60 to 280 ° C. by using known kneading equipment such as a mixing roll, a Banbury mixer, a twin-screw kneading extruder, a kneader and a continuous mixer. In this case, it is more desirable to carry out in an inert gas such as nitrogen or carbon dioxide.

In the present invention, it is preferable not to use a mineral oil-based softener used for improving the fluidity and appearance of a usual thermoplastic elastomer composition in the dynamically heat-treated product. This is because the mineral oil-based softening agent reduces rigidity and heat resistance and thus does not meet the purpose of the present invention.

Next, the (II) propylene homopolymer and / or ethylene-propylene block copolymer used in the present invention which is mixed with (I) a heat-treated product means a propylene homopolymer, that is, a propylene homopolymer. Or an ethylene-propylene block copolymer, that is, a copolymer of ethylene and propylene after homopolymerization of propylene. These may be used alone or in combination.
The ethylene content of the ethylene-propylene copolymer portion in the ethylene-propylene block copolymer is 20 to 70.
% By weight, preferably 25-60% by weight. The isotactic pentad fraction of the homopolymerized portion of propylene needs to be 0.98 or more. 0.98
If it is less than the above range, it is difficult to obtain the rigidity and heat resistance required for the purpose of the present invention. The melt index of the homopolymerized portion of propylene needs to be 30 to 150 g / 10 min. If it is less than 30 g / 10 min, fluidity is low, and if it exceeds 150 g / 10 min, mechanical properties are deteriorated. The homopolymerized portion of propylene of the ethylene-propylene block copolymer can be obtained by taking out from the polymerization tank after the homopolymerization of propylene during the production.

In the present invention, (I) a heat-treated product and (II)
Regarding the method of mixing with a propylene homopolymer and / or an ethylene-propylene block copolymer,
Melt-kneading can be performed by a known kneading machine as in the case of the dynamically heat-treated product. Incidentally, in carrying out the present invention, kneading may be carried out in two stages,
It is also possible to use a multi-stage feed type twin-screw kneader to perform one step.

The inorganic filler (III) used in the present invention may be any one that improves rigidity and heat resistance, and examples thereof include calcium carbonate, barium sulfate, mica, crystalline calcium silicate, talc and glass fiber. Etc., but talc and glass fiber are particularly preferable. The talc preferably has an average particle size of 1 to 5 μm. If the average particle size is less than 1 μm, problems such as re-aggregation and poor dispersion occur. Further, when the average particle size is 5 μm or more, there is little effect on improving impact resistance and rigidity. As the glass fiber, chopped glass having a fiber diameter of 4 to 13 μm, which is surface-treated with a silane coupling agent, is preferably used.

The contents of (I), (II) and (III) in the final composition are 16 to 22% by weight and 52 to 66% by weight, respectively.
18-26% by weight, preferably 17-2, respectively
It is 1% by weight, 55 to 64% by weight, and 19 to 22% by weight. If the heat-treated product (I) is less than 16% by weight, the desired low-temperature impact resistance cannot be obtained. If the content of the inorganic filler (III) is less than 18% by weight, the effect of improving rigidity and heat resistance is small, and if it exceeds 26% by weight, the fluidity is lowered.

In the present invention, the mixing of the inorganic filler (III) can be carried out in the same manner as in the above kneading machine, and a mixture comprising (I) and (II) is obtained in advance and then (III) is mixed. Alternatively, the heat-treated product (I) of (a) or (b) is added to (II)
A method in which (III) is mixed at the same time when the above are mixed can be adopted. Usually, a method is used in which (II) and (III) are simultaneously added to and mixed with the heat-treated product (I) of (a) and (b).

The thermoplastic resin composition comprising the above (I) to (III) according to the present invention further comprises a heat stabilizer, a nucleating agent, an ultraviolet absorber, a lubricant, as long as the object of the present invention is not impaired.
Antistatic agents, flame retardants, pigments, dyes, other polymers and the like may be contained.

The thermoplastic resin composition thus obtained is
It has excellent low-temperature impact resistance and heat resistance rigidity and is suitable for use as an instrumental panel material for automobiles. The material of the present invention can be formed into an instrumental panel by molding it by a generally known method.

[0022]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. The methods of measuring physical properties and the specifications of the kneading equipment used in the examples are as follows. (1) Melt index (MI) The melt index was measured by the method specified in JIS-K-6758.
The measurement temperature was 230 ° C. and the load was 2.16 kg. (2) Bending test According to the method specified in JIS-K-7203. Using a test piece (thickness 6.4 mm) molded by injection molding, the flexural modulus was evaluated under the conditions of a span length of 100 mm and a load speed of 2.0 mm / min. The measurement temperature was 23 ° C. (3) Izod Impact Strength (Izod Impact) The method was defined in JIS-K-7110. Using a test piece (thickness: 6.4 mm) molded by injection molding, notch processing was performed after molding, and the notched impact strength was evaluated. The measurement temperature was 23 ° C. unless otherwise specified. For other temperatures, the measurement was carried out after the condition was adjusted for 2 hours in a constant temperature bath. (4) Rockwell hardness It was determined by the method specified in JIS-K-7202. Using a test piece (two sheets having a thickness of 3.2 mm stacked) formed by injection molding, the steel ball was evaluated using R, and the value was displayed on the R scale. (5) Heat distortion temperature (HDT) According to the method specified in JIS-K-7207. Using a test piece (thickness: 6.4 mm) molded by injection molding, with a fiber stress of 4.6 kgf / cm ² , 2 ° C.
The temperature at which the test piece had a deflection of 0.254 mm when heated at a heating rate of / min was measured. (6) Banbury Mixer Kobe Steel MIXTRON BB-16 MIXE
An R, 2 wing type rotor having a chamber volume of 17.7 liters was used. (7) Biaxial Kneading Extruder A TEX-44SS-30W-2V (different rotation type) manufactured by Nippon Steel Co., Ltd. and a screw of 44 mm × 30 L / D were used.

In the following examples and comparative examples, various materials use the abbreviations shown in Tables 1 and 2, that is, the following. PP: Propylene homopolymer BC: Ethylene-propylene block copolymer EPDM: Ethylene-propylene-nonconjugated diene terpolymer rubber TALC: Talc PO: Organic peroxide 2,5-dimethyl-2,5-di (T-Butylperoxy) hexane BM: Crosslinking aid N, N'-m-phenylene bismaleimide

Example 1 As polypropylene, propylene homopolymer (PP-
1) 30% by weight and ethylene-propylene-as rubber
Non-conjugated diene terpolymer rubber (EPDM-1) 70
In the presence of 0.1% by weight of an organic peroxide (PO) and 0.5% by weight of a cross-linking aid (BM), the mixture was kneaded in a Banbury mixer in an adiabatic state for 10 minutes and then passed through a roll. And formed into pellets (hereinafter referred to as MB or MB pellets) with a sheet cutter (first step). Next, 24% by weight of PP-3, 36% by weight of ethylene-propylene block copolymer (BC-2), 20% by weight of MB produced in the first step and 20% by weight of talc (TALC) were variously stabilized. After uniform mixing with the agent, granulation was carried out at 200 ° C. with a twin-screw kneading extruder (second step), and test pieces were prepared with an injection molding machine and evaluated. Table 2 shows the compositions of MB and the homogeneous mixture (compound) for reference. The evaluation results are shown in Table 3.

Examples 2 to 4 In the composition of Example 1, BM was changed to 1.0 and 2.0% by weight in Examples 2 and 3, respectively, and kneaded in a heat insulating state with a Banbury mixer for 10 minutes, After that, it was passed through a roll and made into pellets with a sheet cutter to obtain MB. For Example 4, the same MB as in Example 2 was used (first step). Compounds containing the MBs and having the compositions shown in Table 2 were granulated in the same manner as in Example 1 (second step) to prepare and evaluate test pieces. Table 3 shows the results.

Examples 5 and 6 Of the compositions of Example 1, BM was used in Example 6 at 4.0.
Change to wt% and heat insulation in a Banbury mixer 1
The mixture was kneaded for 0 minutes, and then pelletized with a sheet cutter through rolls to obtain MB. For Example 5, the same MB as in Example 3 was used (first step). Then, the compounds containing the MBs and having the compositions shown in Table 2 were granulated in the same manner as in Example 1 (second step) to prepare and evaluate test pieces. Table 3 shows the results.

Comparative Example 1 PP-2 42% by weight, BC-3 22% by weight, EPD
After uniformly mixing 16% by weight of M-2 and 20% by weight of TALC with various stabilizers, 200 ° C. in a twin-screw kneading extruder.
Was granulated, and a test piece was prepared using an injection molding machine for evaluation. Table 3 shows the results.

Comparative Example 2 58% by weight of BC-3 and 42% by weight of EPDM-3
Was kneaded in a Banbury mixer in an adiabatic state for 10 minutes, and then passed through a roll to be pelletized with a sheet cutter to obtain MB (first step). Then PP-2 is 4
2 wt%, 38 wt% of MB prepared in the first step and 20 wt% of TALC were granulated in the same manner as in Comparative Example 1 (second
Process), and a sample was prepared and evaluated. Table 3 shows the results.

Comparative Examples 3 and 4 30% by weight of PP-1 and 70% by weight of EPDM-3 and EPDM-2 were kneaded in a Banbury mixer in an adiabatic state for 10 minutes, and then passed through a roll into a sheet cutter. Into pellets to obtain MB (first step). Next, 32% by weight of PP-2, 28% by weight of BC-3, 20% by weight of MB prepared in the first step and 2% of TALC.
0% by weight was granulated in the same manner as in Comparative Example 1 (second step), and a sample was prepared and evaluated. Table 3 shows the results.

Comparative Examples 5 and 6 PP-3 was 20 to 30% by weight and BC-1 was 36% by weight.
EPR of 12,7% by weight, EBR of 12,7% by weight and TALC of 20% by weight were granulated in the same manner as in Comparative Example 1 to prepare and evaluate test pieces. Table 3 shows the results.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

According to the present invention, a heat-treated product obtained by dynamically heat-treating a specific polypropylene and an olefin copolymer rubber in the presence of an organic peroxide and a crosslinking aid, a specific polypropylene and an inorganic filler. An instrumental panel for an automobile is provided using a thermoplastic resin composition containing. Such an instrumental panel is excellent in mechanical properties, in particular, flexural modulus, heat resistance and impact resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location // (C08L 23/12 23:16 23:00) (72) Inventor Yuichi Miyake Toyota City, Aichi Prefecture Toyota Town No. 1 Toyota Motor Co., Ltd. (72) Inventor Takao Nomura No. 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Takesumi Nishio No. 1 Toyota Town, Aichi Prefecture Toyota City Toyota Motor Vehicle Within the corporation

Claims (4)

[Claims] 1. A homopolymer of (I) (a) propylene and / or an ethylene-propylene block copolymer (provided that the homopolymerization portion of propylene has an isotactic pentad fraction of 0.98 or more). ) 10 to 50% by weight and (b) olefinic copolymer rubber 50 to 90% by weight
16 to 22% by weight of a heat-treated product obtained by dynamically heat-treating a mixture consisting of and in the presence of an organic peroxide and a crosslinking aid, and (II) a homopolymer of propylene and / or an ethylene-propylene block copolymer ( However, the isotactic pentad fraction of the homopolymerized portion of propylene is 0.
98 or more and the propylene homopolymerization portion has a melt index (JIS-K-6758, 230 ° C.) of 30 to 1
It is 50 g / 10 min. ) 52 to 66% by weight, and (III) inorganic filler 18 to 26% by weight, and an instrumental panel for automobiles. 2. A melt index (JIS-K-6758, 230 ° C.) of (a) propylene homopolymer and / or ethylene-propylene block copolymer is 11.
It is ~ 30g / 10min, It is characterized by the above-mentioned.
The instrumental panel for automobiles described. 3. The olefin copolymer rubber (b) has an ethylene content of 90 to 40% by weight and an α-olefin content of 1.
An ethylene-α-olefin copolymer rubber or an ethylene-α-olefin-nonconjugated diene terpolymer rubber having 0 to 60% by weight and a non-conjugated diene content of 0 to 12% by weight, having a Mooney viscosity. (ML1 _{+ 4} 100 degreeC) is 10-100, The instrumental panel for motor vehicles of Claim 1 characterized by the above-mentioned. 4. The instrumental panel for automobiles according to claim 3, wherein the α-olefin is propylene or butene-1.