JPH0570661A - Thermoplastic flexible resin composition - Google Patents

Abstract

PURPOSE:To provide the subject composition having moderate flexibility for shock absorption and low-temperature impact strength, good in the appearance of the form thereof, comprising a propylene block copolymer resin, ethylene- propylene copolymer rubber and PE resin, etc., at specified proportion. CONSTITUTION:The objective composition comprising (A) 50-70wt.% of a propylene block copolymer resin of 20-100g/10min in melt flow rate(MFR) (230 deg.C, 2.16kg load), >=2.3 in swell and 1-10wt.% in ethylene content, (B) 10-20wt.% of an ethylene-propylene copolymer rubber of 15-40 in ML1-4 at 100 deg.C and 30-60wt.% in propylene content produced by polymerization using a V-based catalyst, (C) 10-20wt.% of another ethylene-propylene copolymer rubber of 20-60 in ML1-4 at 100 deg.C and 30-80wt.% on propylene content produced by polymerization using a Ti-based catalyst, and (D) 3-15wt.% of a linear low-density polyethylene of 10-50g/10min in MFR (190 deg.C, 2.16kg load). This composition has the following characteristics: (1) MFR: 5-30; (2) swell: >=2.0; and (3) flexural modulus determined by JIS K-7203: 3000-7000kg/cm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has appropriate flexibility for shock absorption and low temperature impact strength, and provides the appearance (flow mark, weld) of a molded product after trichloroethane (TCE) steam cleaning for painting. The present invention relates to a thermoplastic soft resin composition having a performance balance that can be improved.

[0002]

2. Description of the Related Art In recent years, automobile parts have been rapidly made plastic for the purpose of improving fuel efficiency by reducing weight, and interior parts such as instrument panels, console boxes, glove boxes, handles, trims and mall protectors, Lamp housing, front grill,
Not only exterior parts such as mudguards and corner bumpers, but also bumpers, fascias, which have traditionally been made of metal,
Various plastic materials have come to be used even for door garnishes and bodies (partly).

Examples of plastics used for such automobile parts include polymer alloy materials such as RIM / urethane, composite polypropylene, polycarbonate / ABS and polyphenylene ether / polyamide. In particular, the materials used for bumpers and fascias are currently inferior to the type that uses a low-rigidity material that has the property of absorbing the impact at the time of collision mainly by deforming and then recovering the shape, and the deformation recovery performance. However, it is divided into two types, which are lightweight and use low-priced high-rigidity materials.

Of these, the materials used for the former type are mainly RIM / urethane, partially cross-linked ethylene / propylene copolymer rubber-containing polypropylene, ethylene / propylene copolymer rubber, and oil-containing polypropylene. Etc., and the flexural modulus is generally 3,000-
It shows about 7,000 kg / cm ² . As the material used in the latter type, ethylene / propylene copolymer rubber, polypropylene containing an inorganic filler and the like are used, and the elastic modulus thereof is about 8,000 to 20,000 kg / cm ² . These materials other than RIM / urethane have been widely used in recent years because they have high productivity and low cost because they are produced by general-purpose injection molding.

Among the above-mentioned materials, the material used for the low-rigidity bumper is, for example, a polypropylene composition obtained by mixing ethylene / propylene copolymer rubber partially cross-linked with polypropylene, and oil and the like. Methods described in JP-A-53-145857, JP-A-54-16554, JP-A-57-135847, etc., or polypropylene prepared by blending non-crosslinked ethylene / propylene copolymer rubber and high density polyethylene A method relating to a system composition described in JP-A-56-106948, a polypropylene composition in which a non-crosslinked ethylene / propylene copolymer rubber and oil are blended, and JP-A-63-146951. It is manufactured by the method described in Japanese Patent Publication. Further, the material used for the high-rigidity bumper is, for example, a polypropylene composition in which a non-crosslinked ethylene / propylene copolymer rubber and oil are blended, and JP-A-52-23148 and 52-52.
It is manufactured by the method described in Japanese Patent Publication No. 126450 and the like.

Further, in the case of injection-molded products such as bumpers, fascias and door trims, which are required to have a shape (flushness, that is, flatness uniformity) integrated with the vehicle body, environmental temperature changes (- A combination of a specific polypropylene and a specific ethylene propylene rubber with almost no use of an inorganic filler is proposed in Japanese Patent Laid-Open No. 311533 as a means for improving the problems caused by 40 ° C. to 80 ° C.).

Further, the present applicants have already proposed for the same field an injection-molded article having a good appearance (weld) of a molded article, a coated article and a low-temperature impact resistance (Japanese Patent Application No. 2-166870). )It is carried out.

On the other hand, until now, the mainstream of the entire bumper has been painted, but recently, from the viewpoint of design, a striped unpainted part is provided in the upper or lower part of the bumper, or in the central part depending on the design, as an accent. Things are getting more and more. In this case, the coating is partial coating, but the entire molded product is treated by trichloroethane (TCE) steam cleaning which is a pretreatment for coating. It is known that in the TCE treatment, the amorphous portion of the olefin polymer, especially ethylene propylene rubber, is partially dissolved. From this, it was found that the flow marks and weld lines, which were not noticeable immediately after molding, became noticeable by the TCE treatment.

[0009]

However, in the case of molded articles obtained by using the known techniques described in the patent documents proposed so far, the appearance of the molded articles after TCE cleaning (flow marks,
Welds of good quality were not obtained.

The object of the present invention is therefore the TCE for painting.
It is an object of the present invention to provide a thermoplastic soft resin composition capable of absorbing impact by significantly improving the appearance (flow mark, weld) of a molded article after washing and having appropriate flexibility and low temperature impact strength.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a propylene polymer resin having a specific viscoelastic behavior has two types of specific ethylene / propylene. It was found that the appearance (flow mark, weld) of the molded product after TCE steam cleaning is significantly improved and the above-mentioned object can be achieved by blending a specific amount of a copolymer type rubber and a specific linear low density polyethylene. The present invention has been completed.

That is, the thermoplastic soft resin composition of the present invention comprises a component A: melt flow rate (MFR) (230 ° C., 2.16).
kg load) 20 to 100 g / 10 min, swell 2.3 or more, and 50 to 70 wt% ethylene content from 1 to 10% by weight of polypropylene block copolymer resin, Component B: ML ₁ polymerized by using a vanadium-based catalyst ₊₄
100 ° C 15-40, 10-20% by weight of ethylene / propylene copolymer rubber having a propylene content of 30-60% by weight, Component C: ML _{1 + 4} 100 polymerized using a titanium-based catalyst
10 to 20% by weight of ethylene / propylene copolymer rubber having a temperature of 20 to 60 and a propylene content of 30 to 80% by weight, and a component D: melt flow rate (190 ° C, 2.16 kg load) 10
-50g / 10min linear lodity polyethylene resin 3-15wt%, melt flow rate of compound (230 ℃, 2.16kg load) 5-30, swell 2.0 or more and flexural modulus according to JIS-K7203 3,000-7,000 kg
It is characterized by being / cm ² . In the present invention, the swell in component A and component D means a molten resin extruded with a flow tester having a nozzle diameter of 0.5 mm and a length of 5 mm at a furnace temperature of 200 ° C. and a share rate of 2,000 sec ⁻¹ , 10 mm below the nozzle. It is the value obtained by measuring the diameter at the position and dividing this by the nozzle diameter.

The present invention will be specifically described below. [1] Constituents / Composition <Component A> The propylene block copolymer resin used in the resin composition of the present invention comprises a crystalline polypropylene part (a
Component) and ethylene / propylene random copolymer part (b
Component), the component a accounts for 70 to 95% by weight of the block copolymer, and the melt flow rate (230 ° C., 2.16 kg load) is 40 to 200 g / 10 minutes, preferably 80 to 160 g / 10. Minutes, M _W / M _N is usually 7 to 15, preferably 8 to 13, and the density is 0.9060 or more, preferably 0.9070 or more.

The component b accounts for 5 to 30% by weight of the block copolymer, the ethylene content is 20 to 80% by weight, and the melt flow rate is usually 0.001 to 1.0 g / 10 minutes, preferably 0.01 to
0.5g / 10min, and the total melt flow rate is 2
It is from 0 to 100 g / 10 minutes, preferably from 50 to 80 g / 10 minutes.
These (a component) and (b component) can be separately produced, or can be obtained as a component in the polymer obtained by the two-step polymerization method described below. As for the ratio of the (a component) and the (b component), the separately manufactured (a component) and the (b component) are mixed at a predetermined ratio, or the (a component) is the main component. A propylene polymer composition and an ethylene / propylene copolymer composition containing (b) as a main component are blended in controlled proportions, or a raw material monomer in a polymerization such as a two-stage polymerization method. It can be adjusted by methods such as controlling the composition and polymerization conditions.

Particularly, a two-step polymerization method using a stereoregular catalyst is preferably used. The stereoregular catalyst used for the polymerization is a catalyst generally used for stereoregular polymerization reactions of ethylene, propylene and the like, and is usually a catalyst prepared from at least a transition metal halide and an organoaluminum compound. Here, the transition metal halide is preferably a titanium halide, and examples thereof include titanium tetrachloride and titanium trichloride.

As the organic aluminum compound, AlR _n
X _3-n (wherein R represents an alkyl group, an alkoxy group or an aryl group having 1 to 10 carbon atoms, X represents a halogen atom, and n represents a real number of 0 <n ≦ 3). Compounds are preferred.

Specific examples thereof include triethylaluminum, triisobutylaluminum, tri-n-propylaluminum and diethylaluminum monochloride, and one or more of these can be used.

The polymerization conditions may be such that the temperature is usually 0 to 100 ° C., preferably 30 to 90 ° C., and the pressure is usually 0.01 to 45 kg / cm ² , preferably 0.05 to 40 kg / cm ² . As the polymerization method, a known method can be applied, and examples thereof include slurry polymerization, solution polymerization, gas phase polymerization, and liquid phase polymerization using an olefin monomer as a medium. As the solvent used for the polymerization, usually, an aliphatic, alicyclic, or aromatic inert hydrocarbon can be preferably used, and specific examples thereof include pentane, hexane, heptane, cyclohexane, benzene, and toluene. it can.

In the present invention, (a component) and (b component) are mainly produced by using a two-stage polymerization method, in which the first stage (a component) and the second stage (b component) are polymerized. .. In particular, in order to obtain a propylene block copolymer resin having a high melt flow rate and a high swell in the present invention, an organic acid ester as a molecular weight distribution broadening agent is added in an amount of 0.01 to 0.5 with respect to the organoaluminum compound during the first stage polymerization. It is important to add them in a molar ratio.

The propylene block copolymer resin used in the present invention thus obtained has a melt flow rate (230 ° C., 2.16 kg load) of 20 to 100 g / 10 min, preferably 50 to 80 g / 10 min. 2.3 or more, preferably 2.5 or more and an ethylene content of 1 to 10% by weight, preferably 2 to 8% by weight, and a blending ratio of 50 to 70% by weight, preferably 55 to
60% by weight.

When a melt flow rate of less than 20 g / 10 minutes is used, the generation of flow marks after TCE steam cleaning of the molded product is significantly deteriorated. When a melt flow rate of more than 100 g / 10 minutes is used, the low temperature impact strength is lowered.

Similarly, when a swell of less than 2.3 is used, the generation of flow marks after TCE vapor cleaning is significantly deteriorated. Further, when the ethylene content exceeds 10% by weight, not only the injection moldability (mold release property) becomes problematic, but also the blending amount of the component B and the component C needs to be relatively lowered depending on the case. As a result, the low temperature impact strength may decrease.

If the blending ratio is less than 50% by weight, flow mark generation and weld appearance after TCE vapor cleaning of the obtained molded product are remarkably deteriorated, and releasability at the time of molding is deteriorated. On the other hand, when it exceeds 70% by weight, not only the low temperature impact strength is deteriorated, but also the proper flexibility as one of the objects of the present invention, that is, the bending elastic modulus according to JIS-K7203 is 3,
It will exceed 000 to 7,000 kg / cm ² .

<Component B> Component B used in the resin composition of the present invention is produced by using a vanadium-based catalyst composed of a vanadium compound and an organic aluminum compound,
ML _{1 + 4} 100 ° C. 15 to 40, preferably 20 to 35 and propylene content of 30 to 60% by weight, preferably 40 to 55% by weight of ethylene / propylene copolymer rubber. Here, "ethylene / propylene copolymer rubber" means not only a copolymer consisting of ethylene and propylene, but also a copolymer of these and other comonomer, especially a non-conjugated diene, if necessary.

As the non-conjugated diene, dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylnorbornene, 5-ethylidene-2-norbornene and the like are used.

The rubber obtained by using the above catalyst is essential from the viewpoint of ensuring low temperature impact resistance, flexibility and low linear expansion.

ML _{1 + 4} 100 ° C. If a viscosity of less than 15 is used, moldability (mold release property), weld appearance after TCE steam cleaning and low temperature impact strength are deteriorated. On the other hand, 40
When the amount exceeding the above is used, the generation of flow marks after TCE steam cleaning is significantly deteriorated.

When the propylene content is less than the above range, there is a problem in flexibility, while when the propylene content exceeds the above range, there is a problem in molding processability (release property).

The blending ratio of the component B is 10 to 20% by weight, preferably 12 to 18% by weight. When the blending ratio is less than 10% by weight, the low temperature impact strength is lowered. On the other hand, if the mixing ratio exceeds the above range, the flow mark and weld appearance after TCE steam cleaning are significantly deteriorated.

<Component C> Component C used in the resin composition of the present invention is produced by using a titanium-based catalyst comprising a titanium-based compound and an organoaluminum compound, and ML _{1 + 4} 100
℃ 20 ~ 60, preferably 30 ~ 50 and propylene content
The ethylene / propylene copolymer rubber is 30 to 80% by weight, preferably 40 to 75% by weight. "Ethylene
"Propylene copolymer rubber" means a copolymer consisting of ethylene and propylene only and a copolymer with another comonomer such as a non-conjugated diene as in the case of the component B.

The rubber obtained by using the above catalyst is essential from the viewpoint of improving the appearance of the molded product after TCE steam cleaning, especially the weld appearance, and ensuring the flexibility.

ML _{1 + 4} 100 ° C. If a viscosity of less than 20 is used, moldability (release property), weld appearance after TCE steam cleaning and low temperature impact strength deteriorate. On the other hand, when more than 60 is used, the generation of flow marks after TCE steam cleaning becomes worse.

When a propylene content of less than 30% by weight is used, there is a problem in the weld appearance after TCE steam cleaning, while when a propylene content of more than 80% by weight is used, low temperature impact resistance and molding processing are performed. Problem (releasability) occurs.

<Component D> The component D used in the resin composition of the present invention is a melt flow rate (190 ° C., 2.16 kg load) produced by a conventional method in the range of 10 to 50 g / 10 minutes, preferably 20.
-40g / 10min linear low density polyethylene resin, obtained by medium and low pressure ethylene and straight chain α
-Low density and medium density polyethylene resins which are olefin copolymers.

Examples of the linear α-olefin which is a co-monomer include butene-1, pentene-1, hexene-1, octene-1 and the like.

When a melt flow rate of less than 10 g / 10 min is used, the generation of flow marks after TCE steam cleaning of the obtained molded product is markedly deteriorated, while 50 g / min.
If a material exceeding 10 minutes is used, the low temperature impact strength will decrease.

The mixing ratio of the component D is 3 to 15% by weight, preferably 5 to 10% by weight. When the compounding ratio exceeds 15% by weight, the weld appearance of the molded product after TCE steam cleaning remarkably deteriorates, while when it is less than 3% by weight, the flow mark appearance of the molded product after TCE steam cleaning remarkably deteriorates.

The resin composition of the present invention is characterized by comprising the above components A to D. The term "consisting of" as used herein means that an auxiliary component (details described later) may be contained in addition to the components (A, B, C and D) listed above, as long as the gist of the present invention is not impaired. Is.

That is, the resin composition of the present invention comprises
In addition to D, pigments that are generally blended with ordinary resin materials,
Various additives such as a stabilizer, an antioxidant, an ultraviolet absorber and a foaming agent can be added according to the purpose. Further, mineral oil-based softening agents generally called as process softeners or extender oils, which are generally used as rubber softening agents, and inorganic fillers can also be added within a range that does not significantly impair the effects of the present invention.

The resin composition of the present invention comprises the above-mentioned components and has appropriate flexibility for impact absorption and low-temperature impact resistance, and the composition has a melt flow rate of 5 to 30, It has a swell of 2.0 or more and a flexural modulus of 3,000 to 7,000 kg / cm ² according to JIS-K7203. Therefore, it is suitable for the molding of various molded products, especially for the molding of automobile parts. Used for molding.

[2] Mixing Method of Components A to D and Molding The resin composition of the present invention contains the above components A to D (and other components, if necessary) in a Banbury mixer within the range of the above mixing ratio. , Kneader, single-screw extruder, twin-screw extruder and the like are used for blending, and then the mixture is preferably injection-molded by a conventional method.

The injection-molded article thus obtained is, for example, a bumper, fascia, fender air dam,
Used as automotive exterior parts such as air spoilers, moldings, front grills, door garnishes, etc. Therefore, a certain flexural modulus (measured by JIS-K7203)
It is important to have That is, each of the components A to
Within the above range, the mixing ratios of D are such that the bending elastic modulus, which is one of the requirements of the present invention, is 3,000 to 7,000 kg / c.
m ^2, preferably it is desirable to select such that 4,000 ~6,500 kg / cm ^2. When it is used as an exterior member for automobiles, if the bending elastic modulus is less than 3,000 kg / cm ^2, it is too soft, and problems occur in taking out at the time of molding, painting, and attachment of the member. On the other hand, if it exceeds 7,000 kg / cm ² , performance in impact absorption, deformation recovery, damage to the vehicle body, etc. will deteriorate.

[0043]

EXAMPLES The present invention will be specifically described with reference to the following examples and comparative examples. The test methods used for various evaluations in the following Examples and Comparative Examples are as follows.

(Evaluation) (1) Bending elastic modulus: width 10 mm, thickness 4 mm, length adjusted under the molding conditions described below.
It was measured according to JIS-K7203 using a 90 mm injection molded product. (2) Melt flow rate (MFR) According to JIS-K7210, 230 ° C, 2.16kg. (3) Swell Using a flow tester with a diameter of 0.5 mm and a length of 5 mm, measure the diameter of the molten resin extruded at a furnace temperature of 200 ° C and a share rate of 2,000 sec ^-1 at a position 10 mm below the nozzle, and measure this with the nozzle. Divide by the diameter. (4) IZOD impact strength V-shaped notch with width 4mm, thickness 12.5mm, length 64mm, angle 45 °, depth 2.54mm, tip 0.25mmR adjusted in the molding conditions described below. Using injection molded products with JI
It was measured in an atmosphere of -40 ° C according to SK7110. (5) Appearance of molded product after TCE cleaning
Using a steam cleaning tank of 1,1-trichloroethane, the mixture was allowed to stand in steam for 30 seconds, then taken out, and flow marks and welds were evaluated and judged by the following methods. (A) Evaluation method Flow mark: Visual Weld (length): JIS Class 1 30 cm ruler (depth): Surface roughness meter (b) Evaluation point Flow mark: Top part 3 of unbumped part 1 shown in Fig. 1, Side part 4. Weld length; depth: 10 mm from the weld occurrence point of the side ramp part 5 shown in FIG.

(Judgment Criteria) (1) Flexural Modulus 3,000-7,000
kg / cm ² (2) IZOD impact strength (-40 ℃) 5.0 kg ・ cm / cm
Above (3) Appearance after TCE cleaning (Practical Applicability ○ mark: Yes × mark: No) (a) Flow mark (5-grade evaluation)

[Outer 1] (B) Weld length 140 mm ≦: × 130 mm ≧: ○ (c) Weld depth 4 μ ≦: × 3 μ ≧: ○

Examples 1 to 3 and Comparative Examples 1 to 6 Constituent Components Components A, B, C and D used in Examples and Comparative Examples are as shown in Tables 1 to 4 below.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

Blending and molding Blending components A, B, C and D were blended in a Henschel type mixer according to the blending in Table 6, and then melt-kneaded at 200 ° C. in a 45 mm diameter twin-screw extruder to obtain pellets. .. The pellets were injection-molded under the molding conditions shown in Table 5 and used for measurement of flexural modulus and IZOD impact strength (Examples 1 to 1).
3, the molded products of Comparative Examples 1 to 6) and the evaluation sample of the bumper shaped molded body shown in FIG. 1 were prepared. The evaluation results are shown in Table 6.

[0052]

[Table 5]

[0053]

[Table 6]

[0054]

As described above, a bumper obtained from the low-rigidity type thermoplastic soft resin composition of the present invention by injection molding, for example, has a significantly improved appearance (flow mark, weld) after TCE cleaning. In addition, it has a proper performance balance in low temperature impact strength and appropriate flexibility for having impact absorption. In particular, it features a good appearance of the molded body in which the flow marks on the unpainted part of the bumper are not noticeable. It is understood that it was unexpected that this feature can be achieved by combining the components A and B of the present invention and the components C and D of the present invention as essential components, as is apparent from Table 6.

[Brief description of drawings]

FIG. 1 is a perspective view of a bumper-shaped molded body created in Examples and Comparative Examples.

[Explanation of symbols]

 1 Unpainted part 2 Painted part 3 Flow mark evaluation part on the bumper top surface 4 Flow mark evaluation part on the bumper side part 5 Bumper weld appearance evaluation part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayoshi Tsujii 1 Toho-cho, Yokkaichi-shi, Mie Prefecture Yokkaichi Research Institute Ltd. (72) Inventor Yoshiharu Yamamoto 1-place, Toho-cho, Yokkaichi-shi, Mie Mitsubishi Oil Chemical Company Yokkaichi Research Institute

Claims (1)

[Claims] 1. Component A: Melt flow rate (230 ° C.,
2.16kg load) 20-100g / 10 minutes, swell (nozzle diameter 0.1.
Use a flow tester with a length of 5 mm and a length of 5 mm to set the furnace temperature to 20.
The diameter of the molten resin extruded at 0 ° C and a share rate of 2,000 sec ^-1 at the position 10 mm below the nozzle was measured, and the diameter was divided by the nozzle diameter.) 2.3 or more Polymer resin 50 to 70% by weight, component B: ML _{1 + 4} polymerized using a vanadium catalyst
100 ° C 15-40, 10-20% by weight of ethylene / propylene copolymer rubber having a propylene content of 30-60% by weight, Component C: ML _{1 + 4} 100 polymerized using a titanium-based catalyst
10 to 20% by weight of ethylene / propylene copolymer rubber having a temperature of 20 to 60 and a propylene content of 30 to 80% by weight, and a component D: melt flow rate (190 ° C, 2.16 kg load) 10
-50g / 10min linear lodity polyethylene resin 3-15wt%, melt flow rate of compound 5-30, swell 2.0 or more and flexural modulus according to JIS-K7203 3,000-7,000kg / cm ² And a thermoplastic soft resin composition.