JPH07118487A - Polypropylene resin composition and automobile part produced by using the composition - Google Patents

Abstract

PURPOSE:To provide a polypropylene resin composition having a specific composition, exhibiting excellent coating adhesivity without using trichloroethane treatment and primer treatment and giving a molded article having high rigidity, impact resistance at low temperature, heat-resistance, appearance, etc. CONSTITUTION:This composition is composed of (A) 29-75wt.% of a crystalline ethylene-propylene block copolymer, (B) 3-8wt.% of a crystalline ethylene-alpha-olefin copolymer, (C) 20-28wt.% of an ethylene-propylene copolymer rubber, (D) 2-10wt.% of a propylene-based oligomer containing hydroxyl group and (E) 10-25wt.% of an inorganic filler (preferably tale having an average particle diameter of <=3mum). The component A is produced usually by polymerizing propylene and then a mixture of propylene and ethylene in two stages in the presence of a Ziegler-Natta catalyst. The catalyst is preferably composed of a composite material of titanium trichloride and Mg, a trialkylaluminum compound and an electron-donative organic compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention omits the trichloroethane treatment, which is a pretreatment process for coating, and is excellent in coating adhesion with a non-primer, and has rigidity, impact resistance at low temperature, heat resistance,
The present invention relates to a polypropylene resin composition excellent in moldability, appearance of a molded product and the like, and an automobile part using the composition.

[0002]

2. Description of the Related Art In recent years, automobile parts have become thinner and thinner due to larger size and lighter weight, and rigidity, heat resistance, impact resistance at low temperature, and excellent appearance of molded products are maintained. Materials that are expected to be cycled up are being demanded.

Conventionally, as these materials, many compositions in which crystalline polypropylene is used in combination with rubber and an inorganic filler have been proposed. However, most of the automobile exterior parts are often painted and attached in order to give them freshness and high quality. Currently, in this coating process, for the purpose of degreasing and etching the molded product, first the molded product is usually treated in steam of 1,1,1 trichloroethane for about 30 seconds, then the primer is primed and the polyurethane coating is applied as the top coat. is the current situation.

Japanese Patent Laid-Open No. 63-128045 describes a propylene-based polymer composition having an improved coating property, which has excellent adhesion to a polyurethane as an overcoat without using a primer. However, it requires steam treatment of 1,1,1 trichloroethane.

However, at the London Conference in June 1990, the use of 1,1,1 trichloroethane was restricted together with the regulation of CFCs, and it was decided to abolish it by the end of 1995. Therefore, it is not enough for automobile parts to have rigidity, strength, heat resistance, and impact resistance at low temperature, so steam treatment of 1,1,1 trichloroethane is omitted, and primer for undercoating is also omitted. There is a strong demand for the development of a material that allows the top coating to directly adhere to the material without using it.

[0006]

In view of the state of the art as described above, the present invention omits the 1,1,1 trichloroethane treatment, which is a pretreatment process for coating, and applies the primer even if the primer as the undercoat is omitted. An object of the present invention is to provide a polypropylene resin composition having excellent adhesion, rigidity, impact resistance at low temperature, heat resistance, appearance of a molded product, and the like, which can be expected to improve cycle time at the time of molding, and an automobile part using the same. And

[0007]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be solved by using a polypropylene resin composition having a specific composition, and complete the present invention. I arrived.

That is, the present invention relates to a crystalline ethylene propylene block copolymer (A) 29 to 75% by weight, a crystalline ethylene-α olefin copolymer (B) 3 to 8% by weight, an ethylene propylene copolymer rubber. (C) 20-28
% By weight, hydroxyl group-containing polypropylene oligomer (D)
A polypropylene resin composition comprising 2 to 10% by weight and an inorganic filler (E) of 10 to 25% by weight, and an automobile part using the same.

The present invention will be specifically described below. The production of the crystalline ethylene propylene block copolymer (A) of the present invention is usually carried out in a two-step process using propylene and then a mixture of propylene and ethylene in the presence of a Ziegler-Natta catalyst in combination with titanium trichloride and an alkylaluminum compound. Although obtained by polymerization, in carrying out the present invention, it is preferable to use a catalyst composed of a complex of titanium trichloride and magnesium, a trialkylaluminum compound and an electron-donating organic compound. The method for producing this catalyst is described in detail, for example, in JP-A-61-218606.

Crystalline ethylene propylene block copolymer (A) in the polypropylene resin composition of the present invention
The compounding ratio is 29 to 75% by weight, preferably 3
5 to 70% by weight. When the blending ratio is less than 29% by weight, the appearance of the obtained molded product, particularly the flow mark, the rigidity and the heat resistance are deteriorated. On the other hand, when it exceeds 75% by weight, low temperature impact resistance and coating adhesion are deteriorated.

The crystalline ethylene-propylene block copolymer (A) has a crystalline polypropylene portion and ethylene / propylene = 20/80 to 60/40 (weight ratio).
Which has an ethylene-propylene random copolymer portion, the intrinsic viscosity [η] p of the crystalline polypropylene portion is 0.8 to 2.0 dl / g, and the ratio Q of the molecular weight measured by GPC.
Value (weight average molecular weight M _W / number average molecular weight M _N ) is 3.0
5% of the crystalline ethylene propylene block copolymer (A) having an ethylene-propylene random copolymer moiety of up to 5.0, 20 ° C xylene solubles of 1.5 wt% or less.
Those having a content of up to 20% by weight are preferably used.

The ethylene / propylene random copolymer portion has an ethylene / propylene (weight ratio) of 20/80 to.
It is 60/40, preferably 20/80 to 50/50. If the amount of ethylene is less than 20% by weight, the composition has low rigidity and low-temperature impact strength, and if it exceeds 60% by weight, impact properties at low temperature, adhesion to coating, and appearance of molded articles, particularly flow marks, are deteriorated.

The proportion of the ethylene-propylene random copolymer part is 5 to 20% by weight, preferably 7 to 15% by weight in the crystalline ethylene propylene block copolymer (A). When the amount is less than 5% by weight, the low temperature impact strength and coating adhesion of the composition are deteriorated, and when the amount exceeds 20% by weight, the rigidity and heat resistance are deteriorated.

The intrinsic viscosity [η] p of the crystalline polypropylene portion in 135 ° C. tetralin is 0.8 to 2.0 dl /
In g, if [η] p is smaller than 0.8 dl / g, mechanical strength is lowered, and if it exceeds 2.0 dl / g, the fluidity of the composition is remarkably lowered, and the moldability and the appearance of the molded product are Especially, the flow mark is lowered.

The ratio Q of the molecular weight of the crystalline polypropylene portion measured by GPC (weight average molecular weight M _W / number average molecular weight _MN ) is in the range of 3.0 to 5.0, which is smaller than 3.0. And the appearance of the molded product, especially the flow mark, deteriorates,
If it exceeds 5.0, the weld line of the injection-molded product of the composition becomes conspicuous.

The xylene solubles at 20 ° C. in the crystalline polypropylene portion is 1.5% by weight or less, preferably 1.2% by weight or less. If it exceeds 1.5% by weight, the flexural modulus and heat resistance decrease.

The crystalline ethylene-α-olefin copolymer (B) used in the present invention is obtained by polymerizing ethylene alone or ethylene and an α-olefin having 3 to 18 carbon atoms using a transition metal catalyst. Is. The polymerization reaction is usually carried out at a polymerization temperature of 30 to 300 ° C., a normal pressure to a polymerization pressure of 300 kg / cm ² , in the presence or absence of a solvent, or in a gas-solid, liquid-solid, or homogeneous liquid phase. It is carried out in. In this case, the α-olefin includes propylene, butene-1,4-methylpentene-
1, hexene-1, octene-1, decene-1 and the like are used. These α-olefins are not only 1 type, but 2
A combination of two or more species can be used. The crystalline ethylene-α olefin copolymer (B) used in the present invention
Density (JIS K6760) is 0.942 g / cm ³
The above is preferable. Density 0.942 g / cm ³
If it is less than the above range, the mold release at the time of molding becomes poor and the molding cycle cannot be accelerated.

The blending ratio of the crystalline ethylene-α-olefin copolymer (B) in the polypropylene resin composition of the present invention is 3 to 8% by weight. If the compounding ratio is less than this range, the mold release during molding becomes poor. On the other hand, if the blending ratio exceeds the above range, the impact resistance at low temperature and the coating adhesion will be deteriorated.

The ethylene-propylene copolymer rubber (C) of the present invention is usually polymerized in a hydrocarbon solvent in the presence of a catalyst composed of a vanadium compound and an organoaluminum compound. As the vanadium compound, vanadium oxytrichloride, vanadium tetrachloride, a vanadate compound, and as the organoaluminum compound, ethylaluminum sesquichloride, diethylaluminum chloride or the like is used, and by polymerizing in a solvent such as hexane or heptane. Manufactured.

Here, "ethylene / propylene copolymer rubber" means not only a copolymer consisting of ethylene and propylene, but also a copolymer of these and other comonomers, especially a non-conjugated diene, if necessary. means. As a non-conjugated diene,
Dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylnorbornene, 5-ethylidene-
2-norbornene or the like is used.

The ethylene-propylene copolymer rubber of the present invention includes those produced by using a titanium-based catalyst composed of a titanium-based compound and an organoaluminum compound, including copolymers and non-polymers composed of ethylene and propylene only. It means a copolymer with another comonomer such as a conjugated diene.

These ethylene-propylene copolymer rubbers are classified into two types according to their respective purposes such as fluidity of the composition, rigidity, heat resistance, low-temperature impact resistance, appearance of molded products, coating adhesion, and releasability during molding. Alternatively, several kinds can be mixed and used.

The Mooney viscosity ML _{1 + 4} measured at 100 ° C. of the ethylene-propylene copolymer rubber (C) of the present invention is
20-100, preferably 20-85. When the Mooney viscosity is less than 20, the low temperature impact strength of the composition, the appearance of the molded product, the releasability at the time of molding, especially the weld, is lowered, and 100
If it exceeds, the coating adhesion and flow mark of the molded product will deteriorate. Further, the propylene content of the ethylene-propylene copolymer rubber is 20 to 75% by weight, and the adhesiveness to coating is less than 20% by weight,
The mold releasability at the time of molding deteriorates, and when it exceeds 75% by weight, rigidity,
Heat resistance decreases.

When a small amount of a non-conjugated diene monomer is copolymerized with the ethylene-propylene copolymer rubber, the appearance of the molded article, especially the flow mark is deteriorated when the iodine value exceeds 20.

The mixing ratio of the ethylene-propylene copolymer rubber (C) in the polypropylene resin composition of the present invention is 20.
28% by weight. If the blending ratio is less than this range, the low temperature impact strength and the coating adhesion are deteriorated. On the other hand, if the mixing ratio exceeds the above range, the rigidity, heat resistance, releasability at the time of molding, and appearance, particularly flow mark, are deteriorated.

The hydroxyl group-containing polypropylene oligomer (D) used in the present invention has a molecular weight (Mn) of 2000 to
At 20,000, the hydroxyl value is 10 to 50. Examples of materials corresponding to this include Umex (registered trademark) 1201H and Umex (registered trademark) 1210 manufactured by Sanyo Kasei Co., Ltd.

The compounding ratio of the hydroxyl group-containing polypropylene oligomer (D) in the polypropylene resin composition of the present invention is 2 to 10% by weight, preferably 3 to 7% by weight.
When the compounding ratio is less than 2% by weight, the coating adhesion is extremely lowered, and when it exceeds 10% by weight, the impact property at low temperature is extremely lowered and the flow mark and the weld are also lowered.

The inorganic filler (E) used in the present invention includes talc, mica, wollastonite, calcium carbonate, barium sulfate, magnesium carbonate, clay, alumina, silica, calcium sulfate, carbon fiber, glass fiber,
Metal fiber, silica sand, porphyry, carbon black, titanium oxide, magnesium hydroxide, asbestos, zeolite,
Examples include molybdenum, diatomaceous earth, sericite, shirasu, calcium hydroxide, calcium sulfite, sodium sulfate, bentonite, and graphite.

The blending ratio of the inorganic filler (E) in the polypropylene resin composition of the present invention is 10 to 25% by weight, preferably 10 to 20% by weight. 10% by weight
If it is less than 25% by weight, the rigidity and heat resistance are deteriorated, and if it exceeds 25% by weight, the impact strength, the appearance of the molded product and the releasability at the time of molding are deteriorated.

The inorganic filler (E) has an average particle size of 3 μm from the viewpoint of improving rigidity, low temperature impact resistance and appearance of the molded product.
The following talc is preferred.

The resin composition of the present invention can be produced using a kneading machine such as a single-screw or twin-screw extruder, a Banbury mixer, a hot roll. The temperature required for kneading is 160-
The temperature is 260 ° C. and the time is 1 to 20 minutes. Further, in these kneadings, in addition to these basic components, antioxidants, ultraviolet absorbers, lubricants, pigments, antistatic agents, copper damage inhibitors, flame retardants, neutralizing agents, foaming agents, plasticizers, nucleating agents, etc. Additives can be added within a range that does not impair the object of the present invention.
Further, in the coating of the resin composition of the present invention, an undercoat primer can be applied.

[0032]

EXAMPLES The present invention will be specifically described with reference to the following examples and comparative examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. Next, the method for measuring the physical property values in the examples is shown below.

(1) Melt flow rate According to the method specified in JIS K6758. The measurement temperature is 230
° C, and the load is measured at 2.16 kg unless otherwise specified.

(2) Tensile test According to the method specified in ASTM D638. A test piece molded by injection molding is used. The thickness of the test piece is 3.2 mm, and the tensile yield strength and breaking elongation are evaluated. Unless otherwise specified, the measuring temperature is 23 ° C. and the pulling speed is 50 mm / min.

(3) Bending test According to the method specified in JIS K7203. A test piece molded by injection molding is used. The thickness of the test piece is 3.2 mm, the flexural modulus is evaluated under the conditions of a span length of 64 mm and a load speed of 2.0 mm / min. Measured temperature is 23 unless otherwise noted.
℃.

(4) Izod impact strength According to the method specified in JIS K7110. A test piece molded by injection molding is used. The thickness of the test piece is 3.2 mm, and the impact strength with notch that is notched after molding is evaluated. The measurement temperature is −30 ° C., and in this case, the measurement is performed after adjusting the condition for 2 hours in a constant temperature bath.

(5) Deflection test under load According to JIS K7207. Fiber stress is 4.6kg /
Measured in cm ² .

(6) Appearance Shape of molded product Using a flat plate having a width of 100 mm, a length of 400 mm and a thickness of 3 mm, a flow mark of the molded product was visually judged by a one-point side gate from one side having a width of 100 mm. The weld was molded by a two-point side gate from one side having a width of 100 mm, and the appearance of the weld was visually judged. For the visual judgment of flow marks and welds, those that were inconspicuous were marked with ◯, and those that were conspicuous were marked with x.

(7) Paintability A flat plate for judging flow marks was used in the above-mentioned appearance evaluation.
A sample was used after 1 day of molding, which was aged and air-blown without any pretreatment. The flat plate used for coating evaluation was designed so that fingerprints and mold release agent were not attached. The coating adhesion was confirmed by two types of coating methods. Coating method-1: As a base coat, a one-pack acrylic melamine-based paint (Kansai Paint Co., Ltd., trade name Luga Bake, silver metallic paint) is applied in an amount of about 15 μ and applied.
After one minute, a one-liquid acrylic melamine clear (Kansai Paint Co., Ltd., trade name Lugerbake) was applied to a thickness of about 35 μm. Then, it was baked in a dryer so that it was kept at 140 ° C. for 30 minutes. Coating method-2: Only one-component acrylic melamine-based clear of coating method-1 was applied and baked. Other conditions are the same as in coating method-1.

After the baked product was left at room temperature for one day and night, the adhesion test of each sample was carried out. The adhesion test was carried out by a residual rate (%) evaluation (90 ° peeling) in a 1 mm square goggles test using a 24 mm wide cellophane tape (registered trademark) manufactured by Nichiban.

(8) Releasability Molded product shape, width 100 × length 600 × height 80 × thickness 3
A box molded product of mm was used. Injection with only the primary injection pressure, 15
Hold at that pressure for a second. The cooling time after depressurization was changed, and the minimum cooling time (second) at which the sprue did not break when the mold was opened was shown.

[0042]

EXAMPLES Components A, B, C used in Examples and Comparative Examples
The contents of D and E are as shown in Tables 1 to 5 below.

[0043]

[Table 1]

[0044]

[Table 2] Content of crystalline ethylene-α olefin copolymer (B) ───────────────────────────────── ─── No. Product name Melt flow rate Density ─────────────────────────────────── B-1 Idemitsu Polyethylene 210J 5.3 g / 10 minutes 0.968 g / cm ³ (Idemitsu Petrochemical Co., Ltd.) B-2 Sumikasen G401 4 0.925 (Sumitomo Chemical Co., Ltd.) B-3 Sumikasen-L GA401 3 0.935 (Sumitomo Chemical Co., Ltd.) ───────── ────────────────────────────

[0045]

[Table 3] Content of ethylene-propylene copolymer rubber (C) ──────────────────────────────────── No. ML _{1 + 4} 100 ℃ Propylene amount Iodine number Catalyst system ─────────────────────────────────── EPR-1 45 28-Vanadium EPR-2 30 45-Vanadium EPR-3 30 30 18 (ENB) Vanadium EPR-4 77 45 10 (ENB) Vanadium EPR-5 30 68-Titanium EPR-6 120 30 1 (ENB) Vanadium EPR- 7 55 15-Vanadium ────────────────────────────────────

[0046]

[Table 4] Contents of hydroxyl group-containing polypropylene oligomer (D) ─────────────────────────────────── Name Molecular weight (Mn) Hydroxyl value Specific gravity ─────────────────────────────────── Umex 1201H 12000 21.5 0.95 (Sanyo Kasei Co., Ltd.) ─────────────────────────────────── Yumex 1210 4000 50 0.95 (Sanyo Chemical ( Co., Ltd.) ────────────────────────────────────

[0047]

[Table 5]

Examples 1 to 10 and Comparative Examples 1 to 19 Components A to E were blended as shown in Tables 7 and 9 and blended in a Henschel type mixer, and then 220 mm in a 44 mm twin screw extruder. Melt kneading at 0 ° C. to obtain pellets. Using these pellets, under test conditions A, B and C shown in Table 6, test piece pieces, flat plates,
The box was injection molded to prepare a sample for evaluation. The evaluation results are shown in Tables 8 and 10.

[0049]

[Table 6]

[0050]

[Table 7]

[0051]

[Table 8]

[0052]

[Table 9]

[0053]

[Table 10]

[0054]

EFFECTS OF THE INVENTION According to the present invention, even if the trichloroethane treatment which is the pretreatment process for coating is omitted and the primer which is the undercoat is also omitted, the coating adhesion is excellent, the rigidity and the impact resistance at low temperature are excellent. A polypropylene resin composition which is excellent in heat resistance and appearance of a molded article, and can be expected to improve cycle time at the time of molding, and an automobile part using the same can be obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location C08L 23:16 23:08 23:10) (72) Inventor Susumu Kanzaki 5 Anesaki Kaigan, Ichihara City, Chiba Prefecture No. 1 In Sumitomo Chemical Co., Ltd. (72) Inventor Kosuke 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Masahiro Terada 2 Takara-cho, Kanagawa, Yokohama, Nissan Nissan Motor Co., Ltd. Within

Claims (7)

[Claims] 1. A crystalline ethylene propylene block copolymer (A) 29 to 75% by weight, a crystalline ethylene-α olefin copolymer (B) 3 to 8% by weight, an ethylene propylene copolymer rubber (C) 20. A polypropylene resin composition comprising ˜28% by weight, a hydroxyl group-containing polypropylene oligomer (D) 2 to 10% by weight, and an inorganic filler (E) 10 to 25% by weight. 2. An automobile part using the polypropylene resin composition according to claim 1. 3. A crystalline ethylene-propylene block copolymer (A) comprises a crystalline polypropylene portion and ethylene /
Propylene = 20/80 to 60/40 (weight ratio) having an ethylene-propylene random copolymer part,
Intrinsic viscosity [η] p of crystalline polypropylene is 0.8
To 2.0 dl / g, the ratio Q value of molecular weight measured by GPC (weight average molecular weight M _W / number-average molecular weight M _N) is 3.0 to 5.
2. The xylene-soluble content at 0 and 20 ° C. is 1.5% by weight or less, and the ethylene-propylene random copolymer portion is 5 to 20% by weight of the crystalline ethylene propylene block copolymer (A). Polypropylene resin composition. 4. The polypropylene resin composition according to claim 1, wherein the crystalline ethylene-α-olefin copolymer (B) has a density of 0.942 g / cm ³ or more. 5. The ethylene-propylene random copolymer rubber (C) has a Mooney viscosity ML _{1 + 4 of} 100 ° C. 10 to 10.
The polypropylene resin composition according to claim 1, wherein the polypropylene resin content is 0 and the propylene content is 20 to 75% by weight. 6. The polypropylene resin composition according to claim 1, wherein the hydroxyl group-containing polypropylene oligomer (D) has a molecular weight (Mn) of 2000 to 20000 and a hydroxyl value of 10 to 50. 7. The polypropylene resin composition according to claim 1, wherein the inorganic filler (E) is talc having an average particle size of 3 μm or less.