JPS5998157A - Resin composition for bumper - Google Patents

Abstract

PURPOSE:To prepare the titled composition having excellent rigidity, low-temperature impact strength and paintability, and high processability, and giving a molded article having good appearance, by compounding a specific propylene- ethylene block copolymer, a specific ethylene-propylene copolymer rubber and a specific talc. CONSTITUTION:The objective composition is prepared by compounding (A) 50- 70pts.wt. of a propylene-ethylene block copolymer having a melt index of 15- 30g/10min, preferably 15-25g/10min, an ethylene-content of 5-15wt%, an ethylene-content in the propylene-ethylene copolymerized part of 30-60wt% and an intrinsic viscosity of the copolymerized part of 4-10dl/g in tetralin solution at 135 deg.C, (B) 25-35pts.wt. of an ethylene-propylene copolymer rubber having an ethylene-content of 40-80wt% and a Mooney viscosity (ML1+4, 100 deg.C) of 15- 45, and an intrinsic viscosity of 1.2-2.0dl/g in xylene solution at 70 deg.C, and (C) 5-20pts.wt. of talc having an average particle diameter of 0.5-10mu.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition for bumpers, and more specifically, the present invention relates to a resin composition for bumpers, and more particularly, it has excellent processability during injection molding and the appearance of molded products (and has an excellent balance between rigidity and impact strength at low temperatures). In addition,
This invention relates to a resin composition for bumpers with excellent paintability.

Recently, for automobile bumpers, polyurethane bumpers and propylene-ethylene block copolymer bumpers have begun to be used instead of conventional iron bumpers in terms of weight reduction and safety.

However, polyurethane bumpers are expensive and have a relatively high specific gravity, and propylene-ethylene block copolymer bumpers have excellent thermal properties such as stiffness and heat distortion temperature, but have low impact strength at low temperatures. , and the paintability is poor. Therefore, there has been a need for a bumper material that is inexpensive, has excellent rigidity and impact strength at low temperatures, and has excellent paintability. As a material that satisfies these required performances, it was proposed to combine polypropylene resin, ethylene-propylene copolymer rubber, and inorganic fillers such as talc and calcium carbonate.
57, 57-55952, etc. However, in these cases, the melt index of the polypropylene resin used is low and the intrinsic viscosity of the ethylene-propylene copolymer rubber is high, so the fluidity of the resulting composition becomes poor and the molding cycle during injection molding processing becomes difficult. There was a problem that the molded product could not be shortened or thinned, and the appearance of the obtained molded product would be poor, such as poor gloss and flow marks, resulting in a decrease in commercial value.

From the viewpoint of improving processability in injection molding, polypropylene resins with high melt indexes have been put into practical use. However, on the other hand, improving fluidity has the drawback of significantly lowering impact strength, and there was a problem of whether to select processability based on physical properties, or conversely, to select physical properties based on processability. . With regard to bumper materials as well, as bumpers become larger, there has been a demand for improved workability without deteriorating the physical properties of the materials.

The present inventors have developed a resin composition for a bumper that satisfies the rigidity, impact strength at low temperatures, and paintability required for a bumper material, and has excellent processability during injection molding and excellent appearance of the molded product. As a result of various studies on how to obtain this, we found that a propylene-ethylene block copolymer with a specific structure with a relatively high melt index, and an ethylene-propylene block copolymer with a specific structure with a relatively low Mooney viscosity. Copolymer rubber and average particle size of 0.5 to 1O
It has been found that the desired objective can be achieved by blending μ talc in a specific proportion.

Therefore, the present invention provides (1) a melt index of 15 to
80 (y/10 min), ethylene content is 5 to 15 weight Ji1
%, the ethylene content of the propylene and ethylene copolymer part is 3
Propylene-ethylene block copolymer having an intrinsic viscosity of 4 to 10 Cd1lf) in a tetralin solution at 186° C., 50 to 70 polymer parts, (11) an ethylene content of 40 ~80 weight, 100℃ Mooney viscosity ML 15~45, 7゜1+
The intrinsic viscosity in xylene solution at 4℃ is 1.2 to 20 (dt/y
) and 75 to 20 parts by weight of talc having an average particle diameter of 0.5 to 10μ.

The characteristics of the present invention are that a resin composition can be obtained that has excellent material properties, especially a good balance between rigidity and impact strength at low temperatures, and also has excellent fluidity during injection molding and excellent appearance (gloss, flow marks) of molded products. It is something that can be done. This makes it possible to shorten the injection molding cycle, make the molded product thinner, and prevent deformation of the molded product such as warping, twisting, and sink marks.

Another feature is that conventionally, when painting polypropylene resin, special pretreatment was required, and even with pretreatment, the adhesion of the coating film was not sufficient, but using the composition of the present invention. In this system, a resin composition with excellent coating film adhesion can be obtained without special pretreatment.

The propylene-ethylene block copolymer used in the present invention is obtained by first polymerizing propylene to form a polypropylene portion using a Ziegler-Natsuta catalyst, and then copolymerizing a mixture of propylene and ethylene. The block copolymer has a melt index of 15 to 80 (P/10 min), preferably 15 to 25.
(ri/10 power), the ethylene content is 5-15%, the ethylene content of the ignited propylene and ethylene copolymer part is 80-6
0%, and the intrinsic viscosity of the copolymerized portion in a tetralin solution at 186°C is 4 to 10 (dz/y), preferably 4
．． 5 to 8 ((It/f). Melt index of small-depicted molded products cannot be obtained with excellent appearance (flow marks, gloss), and if it is larger than B O (y/10 min), the physical properties, especially The impact strength decreases significantly.If the ethylene content of the propylene and ethylene copolymer part is outside the above range, the impact strength decreases, if the intrinsic viscosity is less than 4, the impact strength decreases, and if the intrinsic viscosity is less than 4, the fluidity deteriorates. Appearance becomes poor.

The ethylene content mentioned here is determined from the infrared absorption spectrum, and is based on the 18% of the propylene-ethylene copolymer portion.
The intrinsic viscosity in a tetralin solution at 5° C. [77] means the viscosity calculated by the following formula.

=1−[η] −(−−1)[η]P”EP X
T X [η]P=intrinsic viscosity of polypropylene polymerization part [η]1
: Intrinsic viscosity of the final propylene-ethylene block copolymer ) The ethylene-propylene copolymer rubber used in the present invention has an ethylene content of 40 to 80 weights at 100°C, and a Mooney viscosity ML of 15 to 451+4, preferably 15 to 35, and 70°C. Intrinsic viscosity in xylene solution is 1.2 to 2.0, preferably 1.2 to 1.7 cd
ll'? ). If the ethylene content is outside the above range, or if the Mooney viscosity is less than 15 or the intrinsic viscosity is less than 1.2, the impact strength will decrease significantly, and if the Mooney viscosity is greater than 45 or the intrinsic viscosity is greater than 2.0, injection molding The appearance of the product (flow marks, gloss) deteriorates.

The average particle diameter of the talc used in the present invention is 05 μ to 1
0μ, preferably 0.6 to 5μ. If it is smaller than 0.5 μm, it will tend to agglomerate during cross-talk, making uniform dispersion difficult, and if it is larger than 10 μm, the impact strength will be greatly reduced and the appearance such as gloss will deteriorate. Talc can be used untreated, but various commonly known silane coupling agents, titanium coupling agents, and higher fatty acids can be used to improve interfacial adhesion with polypropylene resins and improve dispersibility. , higher fatty acid esters, higher fatty acid amides, higher fatty acid salts, or other surfactants can be used.

In order to use the bumper resin composition obtained in the present invention as an automobile bumper, the resin composition has a flexural modulus of 8000 Kf/m or more in terms of rigidity, and an Izot impact strength at -80°C in terms of impact strength at low temperatures. It is necessary that the strength (with notches) is 1O instant/(7)/cIR or higher, and the number of peelings in the paintability test and the cross-cut peeling test is zero, and in addition, the processability during injection molding is improved. Therefore, the composition must have a melt index of 7 or more and must have an excellent appearance, such as high gloss and no flow marks.

Therefore, the blending ratio of the bumper resin composition is 50 to 70 parts by weight of the propylene-ethylene block copolymer,
25 to 85 parts by weight of ethylene-propylene copolymer rubber,
Talc is set on fire for 5 to 20 years. Propylene-
When the amount of ethylene block copolymer is less than 50 parts by weight, the rigidity is low and heat resistance is poor, and when it is more than 70 parts by weight, low-temperature impact strength is low and paintability is poor. If the amount of ethylene-propylene copolymer rubber is less than 25 parts by weight, the low-temperature impact strength will be low and the paintability will be poor, and if it is more than 85 parts by weight, the rigidity will be low.

If the amount of talc is less than 1% by weight, the rigidity will not be improved sufficiently, and if it is more than 20 parts by weight, the impact strength will decrease.

In this way, the resin composition for bumpers that is the object of the present invention can only be obtained by limiting the structure of each component used to a specific range as described above, and by specifying the blending ratio of each component. .

The composition of the present invention can be produced using a mixer such as a -screw extruder, a twin-screw extruder, or a Banbury mixer with 5 heated rolls. The components may be mixed simultaneously or separately. As for the divisional addition method, there is a method of kneading the propylene-ethylene block copolymer and talc and then adding rubber, or a method of kneading talc in advance to a high concentration to make a masterbatch, and then adding the block copolymer, rubber, etc. separately. There is a method of kneading it while diluting it, and it can also be molded using a similar method. The E1 degree required for crosstalk is 160-260°C, and the time is 1-20 minutes.

Furthermore, in addition to these basic ingredients, antioxidants, ultraviolet absorbers, lubricants, face \"1, belt γ
(Additives such as L inhibitor, copper damage inhibitor, flame retardant, neutralizer, photofoaming agent, plasticizer, nucleating agent, antifoaming agent, crosslinking agent, etc. can be blended. Among these, in order to improve outdoor weather resistance, heat resistance, and oxidation resistance stability as a resin composition for bumpers, 2.
．． 6-di-tert-butylphenol, 2,6-di-tert-phthyl-4-ethylphenol, 2, (i-'; tert-butyl-α-dimethylamino-para-cresol, 6
-(4-hydroxy-3,5-di-tert-butylanilino)
-2,4-bisoctyl-thio-1,8,5-)riazine, 2,6-di-tert-butyl-4-methylthuunol, tris-(2-methyl-4-hydroxy-5-tert-methylphenyl) ) phthane, tetrakis-[methylene-3-(3
', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate comethane, dilauryl thiodipropionate, etc., as ultraviolet absorbers, 2-hydroxy-4
-〇-Octoxybenzophenone, 2-hydroxy-4
-octadecyloxybenzophenone, 4-dobucyloxy-2-hydroxybenzophenone, 2 = (2'-hydroxy-3'-tert-bunal-5'-)'-f-ruphenyl)-5-chlorobenzotriazole, 2-( 2'-
Hydroxy-a/, 5L-di-tert-butyl-phenyl)-5-chlorohencytriazole, bis-(2,6-
It is preferable to blend dimethyl-4-piperidyl) sebacate or the like.

The composition obtained according to the present invention can be injection molded, extruded or blow molded. Particularly suitable for injection molding. This composition has an excellent balance between rigidity and low-temperature impact strength, has excellent paintability, and has excellent processability during injection molding and excellent adhesion of molded products, making it possible to shorten molding cycles and reduce wall thickness. This makes it possible to apply it to automobile bumper materials, especially large bumpers that require fluidity.

Hereinafter, the content of the present invention will be specifically explained with reference to Examples, but the scope is not limited thereby.

Measurement of physical properties according to the present invention is carried out by the following method.

Melt index: Based on JIS K-6758.

Flexural modulus: Measured at 23°C in accordance with ASTM D790. The test scissors for measurement were molded using a screw in-line injection molding machine manufactured by Sumitomo Heavy Industries Co., Ltd.

Izot impact strength (notched): Based on JIS K 7110, at 23°C and -30°C
Measured at °C.

The test piece for measurement is flexural modulus measurement. It was molded in the same way as the running test piece.

Gloss: ASTM D5B2-5BT Compliant. The test piece for measurement is a resident Screwey manufactured by Juukikari Kogyo Co., Ltd. With an on-line injection molding machine, A sheet weighing 211 g was molded.

Flowmark: Using a screw in-line injection molding machine manufactured by Sumitomo Heavy Industries Co., Ltd., a sheet with a width of 10 mm, a length of 400 mm, and a thickness of 3 tI11 was molded. Visually observe the flow mark occurrence and make the following judgments.

Visual inspection result Judgment 70 - Marks are not observed at all A few marks are observed at the end of the 5th sheet A few marks are observed throughout the 4th sheet
3 Quite noticeable throughout the sheet 2 Extremely noticeable throughout the sheet 1 Flow length 2 Using a screw in-line injection molding machine manufactured by Japan Steel Works, a mold with a width of 25 m x length of 10106O and a thickness of 2.0 fins was made. in,
Molding was carried out under the conditions of injection pressure cuff 00/d, injection time 8 seconds, mold temperature 50°C, and molding temperature 250°C, and the length of the flow was measured and used as a measure of workability.

Example 1 Melt index is 20, ethylene content is 9.5 weight tons
%, a propylene-ethylene block copolymer (referred to as PP-1) in which the ethylene content in the propylene-ethylene copolymer part is 58% by weight and the intrinsic viscosity of the copolymer part is 5.5; 50% by weight, Mooney viscous 006
The C degree ML is 29 and the intrinsic viscosity is 1.47.
65 ethylene propylene copolymer rubber (referred to as EPR-1) and talc with an average particle size of 3μ, respectively.
:25:10 (parts by weight), and further added 0.5 of the antioxidant Irganox 01010 (Ciba Geigy!1) to 100 parts by weight of the above ingredients in total.
After adding 0.2 parts by weight of the ultraviolet absorber Sanol 0LS770 (manufactured by Ciba Geigy) to the heavy phase, the mixture was kneaded at 190°C for 10 hours in a Banbury mixer. After kneading, the mixture was formed into pellets using an extruder. Physical property measurement results are shown in Table 1 In Example 1, instead of PP-1, melt index was 7.0, ethylene content was 8,0% by weight, and ethylene content in the propylene-ethylene copolymer part was 4.
5% by weight, a propylene-ethylene block copolymer (referred to as PP-2) whose intrinsic viscosity of the copolymerized portion is 6.5.

), and instead of EPR-1, the ethylene content is 49
Mooney viscosity MLlθ°'C1+4 is 80. It was carried out in the same manner as in Example 1 except that an ethylene-propylene copolymer rubber (referred to as EPR-2) having an intrinsic viscosity of 2.50 was used. The physical property measurement results are shown in Table 1.

0 Comparative Example 2 A test was conducted in the same manner as in Example 1 except that PP-2 was used instead of PP-1. The physical property measurement results are shown in Table 1.

Comparative Example 8 In Example 1, Lini EPR-1 (7) was used instead of EPR-1 (7).
Example 1 was carried out in the same manner as in Example 1, except that Example 2 was used. The physical property measurement results are shown in Table 1.

Comparative Example 4 In Example 1, PP-1(7) substitute Lini, melt index was 46, ethylene content was 9.0% by weight,
A propylene-ethylene block copolymer (referred to as PP-8) having an ethylene content of 41 weight jiL% in the propylene-ethylene co-electrolyte portion and an intrinsic viscosity of the copolymer portion of 6.0. , The same method as in Example 1 was carried out except that EPR-2 was used instead of EPR-1. The physical property measurement results are shown in Table 1.

Table 1 Note 1. PP: Propylene-ethylene block copolymer 2, EI'R: Ethylene-propylene copolymer rubber Example 2 In Example 1, the blending ratio of PP-1, EPR-1, and talc was 60:80:1O ( The procedure was carried out in the same manner as in Example 1, except that the amount was changed to (parts by weight). The physical property measurement results are shown in Table 2.

Example 8 A test was conducted in the same manner as in Example 1, except that the mixing ratios of PP-1, EPR-1, and talc were changed to 50:80:20, respectively. The physical property measurement results are shown in Table 2.

Example 4 In Example 1, instead of EPR-1, 1+4 ethylene-propylene copolymer rubber (EPR-3) having an ethylene content of 70% by weight, a Mooney viscosity of 100° C. ML of 22, and an intrinsic viscosity of 1.82 was used. shall be.

) was used in the same manner as in Example 1. The physical property measurement results are shown in Table 2.

Comparative Example 6 A test was performed in the same manner as in Example 1 except that the mixing ratios of PP-1, EPR-1, and talc were changed to 70:20:IO. The physical property measurement results are shown in Table 2.

Comparative Example 7 A test was carried out in the same manner as in Example 1 except that the mixing ratios of PP-1, EPR-1 and talc were changed to 50:40:10, respectively. The physical property measurement results are shown in Table 2.

Table 2 Note 1. PP: Propylene-ethylene block copolymer 2, EPR: Ethylene-propylene copolymer rubber Example 5 In order to examine the paintability of the resin composition obtained in the present invention, Examples 1 to 4 and Comparative Example 6 were used. The resulting composition was subjected to a coating performance test using the method described below.

Paintability: Length 90fi, width 90m, thickness 2 trials a
First, an ethylene vinyl acetate copolymer primer (rRB 196J, manufactured by Nippon B Chemical Co., Ltd.) was spray-painted on the test plate, and then a urethane-based top coat (FRB-2 63'', manufactured by Nippon B Chemical Co., Ltd.) was applied to the film thickness. The coating was sprayed to a thickness of 40μ. After being left for 10 minutes, it was baked at 80° C. for 40 minutes. The adhesion of the paint was determined by the number of peeled pieces after leaving it for 3 days, making ioo dots on the paint film with a knife, and peeling off with cellophane tape.

Table 8 Procedural Amendment (Spontaneous) November 27, 1982 2 Name of the invention Resin sheath composition for bumpers 3 Relationship to the person making the amendment Patent applicant 5-15 Kitahama, Higashi-ku, Osaka (209 ) Sumitomo Chemical Co., Ltd. Representative Takeshi Hijikata 4, Agent 5-16-5 Kitahama, Higashi-ku, Osaka, Subject of amendment 6, Contents of amendment (1) The scope of claims in the description will be amended as shown in the attached sheet.

(2) The detailed description of the invention in the specification is amended as follows.

(-i) Change “15-35” to “15-4” on page 5 of the specification, line 3.
5”.

(b) On page 5, line 4, “1.2-1.7” was changed to “1.2-2.”
・Correct it to 0.

(C) Correct "15-35" on page 8, line 3, to "15-45, preferably 15-35."

(d) On page 8, lines 4-5, “1.2-1.7” was changed to “1.2”.
~2.0, preferably 1.2~1.7''.

(e) Correct "35" on page 8, line 8 of the same page to "45".

(・\) Same page 8, line 9 r1.7J as r2. Correct with DJ.

(g) "Impact strength" in page 9, line 8, page 13, line 15, page 18, table 1, and page 21, table 2, is corrected to "impact strength (notched)."

The appended claims ``(■) have a melt index of 15 to 3 degrees (g/10 minutes), an ethylene content of 5 to 15% by weight, an ethylene content of the propylene and ethylene copolymer portion of 30 to 60% by weight, and The intrinsic viscosity of the copolymerized portion in a tetralin solution at 135°C is 4.
Ethylene-propylene whose propylene-ethylene block copolymer 5 is 15-45 and has an intrinsic viscosity of 1.2-2.0 (dl/g) in xylene N solution at 70° C. A resin sugar composition for a bumper comprising 25 to 35 parts by weight of copolymer rubber and 5 to 2 parts by weight of talc having an average particle diameter (DI) of 0.5 to 10 μm.

” Procedural amendment (method) 1. Indication of the case 1988 Patent Application No. 2 (17881 2, Name of the invention Hanno? - Resin M1 composition 3, Person making the amendment Relationship to the case Patent applicant Osaka City Higashi 5-15 Kitahama-ku (209) Sumitomo Chemical Co., Ltd. Representative: Takeshi Hijikata 4, Agent contact information: (06) 220-34045, Full text of the date statement of the amendment order 7, Inscription of the content statement of the amendment No changes to the content〉 That's all

Claims (1)

[Claims] (I) Melt index is 15 to 80 (y/IO minutes)
, the ethylene content is 5 to 15% by weight, the ethylene content of the copolymerized portion of pylene and ethylene is 30 to 60%, and the intrinsic viscosity of the copolymerized portion in L86°C tetralin solution is 4.
50 to 70 parts by weight of a propylene-ethylene block copolymer with ~10 (dz/r), (II) ethylene content of 40 to 80% by weight, Mooney viscosity of 100°0 of 15 to 4
5, and 26 to 35 parts by weight of an ethylene-propylene copolymer rubber having an intrinsic viscosity of 1.2 to 2.0 (dz/y) in a 70° C. xylene solution;
A resin composition for a bumper comprising 6 to 20 parts by weight of talc having an average particle diameter of 0.5 to 10 μm.