JP2978197B2 - Resin composition for soft bumper - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resin composition for a soft bumper. More specifically, it has excellent impact resistance, moldability (melt fluidity), stickiness of molded products, and appearance of molded products, especially the flow mark of the tiger mark pattern (hereinafter referred to as flow mark).
And a resin composition for a soft bumper excellent in linear expansion.

(Conventional technology and its problems) Currently, polyolefin-based bumpers for automobiles having excellent impact resistance include those obtained by blending an amorphous ethylene-propylene copolymer with a propylene-ethylene block copolymer. Accordingly, a composite material containing talc has been put to practical use. However, there are few practical examples of bumpers that can withstand the standard that the vehicle body is not damaged at the time of collision with a concrete wall at 5 mph / h (8 km / h) specified by FMVSS (US Vehicle Safety Standard). .

Among them, those obtained by blending an amorphous ethylene-propylene copolymer and a specific styrene-based elastomer with a crystalline propylene-ethylene block copolymer disclosed in JP-A-61-14248, Soft polyolefin composition obtained by blending an amorphous α-olefin copolymer, a specific ethylene-α-olefin copolymer and an ethylene polymer with the crystalline propylene polymer disclosed in JP-A-62-112644. Is being developed.

However, a mixture of an amorphous ethylene-propylene copolymer and a specific styrene-based elastomer in a propylene-ethylene block copolymer,
The 1,1 trichloroethane vapor cleaning has a problem that it is inferior in chemical resistance, remarkably deteriorating the appearance and deteriorating physical properties.

In addition, when an amorphous α-olefin copolymer, a specific ethylene-α-olefin copolymer and an ethylene polymer are blended with a crystalline propylene polymer, the effect of improving the impact resistance and the mold separation are reduced. It is hard to say that the type is still sufficient. Furthermore, recent bumpers are often of the full fascia type, which is on the extension of the bonnet because of its design.At this time, the soft polyolefin composition has a large linear expansion coefficient, so the clearance between the bonnet and the bumper is large. There is a problem that it becomes too much.

As a result of intensive studies to solve the above-mentioned problems relating to such a resin composition for a soft bumper, the present inventors have found that a low-crystalline ethylene-butene copolymer and a specific talc are used for the polyolefin-based soft bumper. By applying this, a resin composition for soft bumpers that has excellent impact resistance and line cleaning without impairing its appearance in 1,1,1 trichloroethane vapor cleaning, which is excellent in the appearance of molded products, and in pretreatment for coating 1,1,1 trichloroethane. The inventors have found that the present invention has been completed and completed the present invention.

 More specifically, the present invention has the following configuration.

(1) (a) from 30 to 70% by weight of a crystalline propylene-ethylene block copolymer; (b) from 15 to 40% by weight of an amorphous ethylene-propylene copolymer; (c) low-crystalline ethylene-butene From copolymer 5
(D) from talc 3 having an average particle diameter of 3 microns or less
20% by weight of (e) (a) + (b) + (C) + (d) 100 parts by weight of a higher fatty acid amide per 100 parts by weight of a resin composition for a soft bumper.

(2) The density of the low crystalline ethylene-butene copolymer is 0.91
2. The resin composition for a soft bumper according to claim 1, wherein the resin composition has a maximum peak temperature of 0 g / cm ³ or less and a differential scanning calorimetry (DSC) of 40 ° C. to 125 ° C.

The crystalline propylene-ethylene block copolymer (a) serving as the base of the resin composition for a soft bumper functions as a hard segment in the resin composition for a soft bumper, and the crystalline propylene-ethylene block copolymer has 1,
Excellent deformation and impact resistance during heating of 1,1 trichloroethane steam cleaning.

The crystalline propylene-ethylene block copolymer has an ethylene content of 2% by weight or more, preferably 10% by weight or more, and a melt flow rate of 3 to 100 g / 10.
Min, preferably 5 to 60 g / 10 min. When the ethylene content in the polymer is less than 2% by weight, the ethylene content is 2%.
If the content is less than 10% by weight, the effect of improving impact resistance is small, and the flexibility is undesirably reduced. If the melt flow rate is less than 3 g / 10 minutes, the molding processability is reduced, and flow marks are liable to be generated. If the melt flow rate exceeds 100 g / 10 minutes, the impact resistance of the molded product is undesirably reduced. The amount of the propylene polymer is (a) + (b) + (c) +
(D) 30 to 70% by weight of the total weight, preferably 40 to 60% by weight. When the propylene-based polymer is blended in less than 30% by weight, the rigidity is reduced, and when the propylene-based polymer is blended in an amount exceeding 70% by weight, the effect of improving impact resistance is not sufficient, and the flexibility is unfavorably reduced. .

The amorphous ethylene-propylene copolymer (b) used in the present invention functions as a soft segment and improves impact resistance. The amorphous ethylene-propylene copolymer preferably has a Mooney viscosity ML _{1 + 4} (100 ° C.) of 50 or less.
If the compound has a Mooney viscosity of more than 50, it is not preferable to use the compound alone because it may impair the fluidity of the composition or cause a flow mark on the appearance of a molded article. The amount of the amorphous ethylene-propylene copolymer is from 15 to 40% by weight, preferably from 20 to 40% by weight, based on the total weight of (a) + (b) + (c) + (d). is there. When the amount of the amorphous ethylene-propylene copolymer is less than 15% by weight, the effect of improving the impact resistance is not sufficient, and when the amount exceeds 40% by weight, a flow mark is generated on the surface of the molded article. It is not preferable because it is easy to perform.

The (C) low-crystalline ethylene-butene copolymer used in the present invention functions as a soft segment, and when only the amorphous ethylene-propylene copolymer is blended, a flow mark is generated on the appearance of a molded product. By using the low crystalline ethylene-butene copolymer in combination, the flow mark can be reduced together with the effect of improving the impact resistance. In addition, chemical resistance is not deteriorated by 1,1,1 trichloroethane vapor cleaning as a pretreatment for coating. The low crystalline ethylene-butene copolymer preferably has a density of 0.910 g / cm ³ or less and a maximum peak temperature of 40 ° C. to 125 ° C. as shown by differential scanning calorimetry (DSC). If the density exceeds 0.910 g / cm ³ , it becomes hard and difficult to maintain flexibility.If the maximum peak of DSC is less than 40 ° C, the deformation during heating increases, and 125 ° C
It is not preferable to mix the above components because it becomes difficult to maintain impact resistance.

The amount of the low crystalline ethylene-butene copolymer is from 5 to 5 in the total weight of (a) + (b) + (c) + (d).
It is 30% by weight, preferably 10 to 25% by weight. 5
When the amount is less than 30% by weight, the flow mark is noticeable. When the amount exceeds 30% by weight, the effect of improving the impact resistance is small in spite of the decrease in rigidity (23 ° C. flexural modulus).

The (d) fine talc having an average particle diameter of 3 μm or less used in the present invention has a low linear expansion coefficient. Preferably, the average particle diameter is 2.5 microns or less, and when talc exceeding 3 microns is blended, it is not preferable because impact resistance, particularly surface impact, is reduced. The amount of talc is (a) + (b) + (c) + (d) from 3 of the total weight.
20% by weight, preferably 3 to 15% by weight. 3
When the amount is less than 20% by weight, the effect of reducing the coefficient of linear expansion is small, and when the amount exceeds 20% by weight, the impact resistance, particularly the surface impact, is undesirably reduced.

The (e) higher fatty acid amide used in the present invention has an effect of improving the mold releasability during molding and the stickiness of the molded article. As the higher fatty acid amide used in the present invention, for example, oleic acid amide, erucic acid amide, stearic acid amide and the like can be mentioned, among which oleic acid amide is particularly preferable. The blending ratio of the higher fatty acid amide is (a) +
(B) + (c) + (d):
It is 0.01 to 5 parts by weight, particularly preferably 0.1 to 2 parts by weight. When the compounding ratio is less than 0.01 part by weight, the mold releasability at the time of molding a molded article using the obtained composition is poor, and the obtained molded article has an insufficient sticky prevention effect. If the amount exceeds 5 parts by weight, bleeding of the higher fatty acid amide becomes remarkable on the surface of the obtained molded article, and the appearance of the molded article is deteriorated.

In the composition of the present invention, an antioxidant, an antistatic agent, a coloring agent, an ultraviolet absorber, a plasticizer, an extender oil for EPDM, as appropriate, as long as the effects of the present invention are not impaired. One or more kinds of various additives such as a softening agent for a mineral non-aromatic rubber such as a process oil can be blended.

As a method for producing the composition of the present invention, a crystalline propylene-ethylene block copolymer, an amorphous ethylene-propylene copolymer, a low-crystalline ethylene-butene copolymer, talc, a predetermined amount of higher fatty acid amide In addition, a predetermined amount of one or more of the various additives described above is stirred and mixed with a ribbon blender, a tumbler mixer, a Henschel mixer (trade name), a super mixer, or the like, and then the mixture is rolled.
Melting temperature from 150 ℃ to 3 with Banbury mixer, extruder, etc.
A method of melt-kneading pelletizing at 00 ° C., preferably 180 ° C. to 250 ° C. can be exemplified.

The resin composition for a soft bumper of the present invention thus obtained can be used for the production of various molded products by various molding methods such as injection molding, extrusion molding, vacuum molding, and pressure molding.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The components and evaluation methods used in the examples and comparative examples are as follows.

(Ingredients) (1) Crystalline propylene-ethylene block copolymer Propylene-ethylene block copolymer manufactured by Chisso Petrochemical Co., Ltd., ethylene content 12 wt% melt flow rate 25 g / 10 min (2) Propylene alone Polymer Made by Chisso Petrochemical Co., Ltd., melt flow rate 20g / 10
(3) Amorphous ethylene-propylene copolymer Mooney viscosity ML _{1 + 4} (100 ° C) 25 manufactured by Nippon Synthetic Rubber Co., Ltd.
EP02P (4) Amorphous ethylene-propylene copolymer Mooney viscosity ML _{1 + 4} (100 ° C) 70 Nippon Synthetic Rubber Co., Ltd.
EP07P (5) Low crystallinity ethylene-butene copolymer Nackflex DEFD1210 manufactured by Nippon Unicar Co., Ltd.
(Product name) (6) Talc (A) Average particle size 2.0 microns (7) Talc (B) Average particle size 8.5 microns (8) Oleic acid amide (Evaluation method) (1) Melt flow rate (g / 10 minutes) Conforms to JIS K6758 (2) Flexural modulus (3-point flexural modulus) (kgf / cm ² ); Conforms to JIS K7203 (3) Izod impact strength (kgf-cm / cm ² ); Conforms to JIS K7110 (4 ) DuPont impact strength (kgf-cm); Chisso method DuPont impact tester (manufactured by Toyo Seiki)
Hammer 1/4 inch R, hammer receiver 3/2 inch R, load 0.1Kg
From 3kg, load drop height 1m, test specimen 50 × 50 × 2mm
After adjusting the temperature to −60 ° C. using the flat plate, place the test piece on the barrel base and apply the barrel to drop the load from a height of 1 m.
If the test piece breaks, use a light load if it does not break, and use a heavy load if not, and find the load at which 50% of the test pieces break. If the fracture mode is a hole, it is regarded as a ductile fracture and is distinguished from a brittle fracture.

(5) Coefficient of linear expansion (cm / cm / ° C); Conforms to ASTM D696 (6) Appearance of molded product: Chisso method IS200B injection molding machine (manufactured by Toshiba Machine Co., Ltd.) Die: 400 × 80 × 3mm plate Mold Molding temperature: 230 ° C. The appearance of the flat plate obtained by injection molding under the molding condition of mold temperature: 30 ° C. was visually judged by the visibility of flow marks.

Evaluation criteria ◎: No tiger child mark is recognized ○: Little tiger child mark is recognized ×: Tiger child mark is noticeable (7) Evaluation of stickiness of molded product; Chisso method Five pieces using 400 × 80 × 3 mm test specimen Were superimposed, a load of 3 kg was applied, and after 24 hours, the blocking property between the molded products was determined.

Evaluation Criteria ○: No blocking between molded products ×: Blocking but peeling XX: Extremely blocking, causing material destruction when peeled (Examples of compounding method) Examples 1 to 7, Comparative Examples 1 to 6 As Example 1, the above-mentioned crystalline propylene-ethylene block copolymer, amorphous ethylene-propylene copolymer, low-crystalline ethylene-butene copolymer, talc, and higher fatty acid amide are described in Table 1 below. The mixture was stirred and mixed for 3 minutes with a Henschel mixer (trade name), melt-kneaded, extruded, and pelletized. Example 5 was repeated in the same manner as in Example 1 except that an amorphous ethylene-propylene copolymer having a high Mooney viscosity was used.

Similarly, in Comparative Examples 1 to 6, in Comparative Example 1, low-crystalline ethylene-butene copolymer and talc were not blended.
In Comparative Example 2, 40% by weight of a low crystalline ethylene-butene copolymer was blended. In Comparative Example 3, talc was blended at 30% by weight,
In Comparative Example 4, talc having a large average particle diameter was blended. In Comparative Example 5, higher fatty acid amides were added, and in Comparative Example 6, a propylene homopolymer was added, in accordance with Examples.

MF using the pellets obtained in each example and comparative examples
R measurement and specified test piece molding temperature 230 ° C, mold temperature 30
The composition was molded at ℃ by an injection molding method, and the flexural modulus, Izod impact strength, Dupont impact strength, and linear expansion were measured.
A molded article was formed from the obtained pellets, and the appearance of the obtained molded article and the stickiness were evaluated. The results are summarized in Table 1.

(Effects of the Invention) As is clear from Table 1, the molded product obtained by using the resin composition for a salt bumper has excellent impact resistance, moldability, mold releasability, and stickiness of the molded product. It can be seen that they are excellent in the properties and appearance of the molded product, especially in the flow mark and the linear expansion.

On the other hand, in Comparative Example 1 in which only the amorphous ethylene-propylene copolymer was blended as the soft segment, a flow mark was generated on the appearance of the molded article, and the stickiness of the molded article was poor, so that the commercial value was significantly reduced. Let it. Comparative Example 1
However, since talc is not further blended, the coefficient of linear expansion becomes large, which is not desirable because the coefficient of linear expansion desired for the bumper is not small. In Comparative Example 2 in which the low-crystalline ethylene-butene copolymer was blended beyond the range of use, the impact resistance was lowered, so that it was not practical. In Comparative Example 3 in which talc was added in an amount exceeding a predetermined amount and in Comparative Example 4 in which talc exceeding 3 μm was added, the impact resistance was reduced and flow marks were generated, thereby significantly reducing the commercial value. Comparative Example 5, in which the higher fatty acid amide was not blended, was inferior in stickiness and mold releasability of a molded product. Comparative Example 6 in which propylene homopolymer was blended as a hard segment
In this case, the impact resistance is lowered, so that it is not practical.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI C08K 5:20) (58) Investigated field (Int.Cl. ⁶ , DB name) C08L 53 / 00,23 / 08 C08K 3 / 34,5 / 20

Claims (2)

(57) [Claims] (1) 30 to 70% by weight of a crystalline propylene-ethylene block copolymer, (b) 15 to 40% by weight of an amorphous ethylene-propylene copolymer, and (c) low-crystalline ethylene. (E) (a) + (b) + (C) + (d), wherein 5 to 30% by weight of a butene copolymer and (d) 3 to 20% by weight of talc having an average particle diameter of 3 μm or less are blended. A resin composition for a soft bumper, comprising 0.01 to 5 parts by weight of higher fatty acid amide per 100 parts by weight. 2. The low-crystalline ethylene-butene copolymer has a density of 0.910 g / cm ³ or less, and has a differential scanning calorimetry (DSC).
The resin composition for a soft bumper according to claim 1, wherein the maximum peak temperature indicating the temperature is from 40 ° C to 125 ° C.