JPS60112844A - Polypropylene composition for injection molding - Google Patents

Abstract

PURPOSE:To provide titled composition having specific melt fluidity index, of outstanding impact strength, ridigity, melt fluidity, colored appearance, comprising specific polypropylene, ethylene-alpha-olefin random copolymer and polyethylene. CONSTITUTION:The objective composition with a melt flow rate 3-50g/10min and melt fluidity index (N) <=3 comprising (A) 50-90 (pref. 60-80)wt% of polypropylene with an isotactic index >=89, melt flow rate 20-150g/10min (may be copolymer with >=95mol% of propylene), (B) 5-40 (pref. 10-30)wt% of ethylene- alpha-olefin random copolymer with an ethylene content 35-85mol% (pref. with an intrinsic viscosity [eta] 2-9dl/g and degree of crystallinity determined by X-ray analysis <=10%) and (C) 0-30 (pref. 3-20)wt% of polyethylene with an intrinsic viscosity [eta] 2-6.8dl/g (may be copolymer with >=93mol% of ethylene).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polypropylene compositions for injection molding. More specifically, the present invention relates to a polypropylene composition for injection molding that has excellent rain impact resistance, rigidity, and melt flowability, and has an excellent appearance even when colored with a pigment.

Although crystalline polypropylene has excellent properties in terms of strength, heat resistance, and gloss, it has the drawback of poor impact strength and paintability when used alone. Therefore, at present, its use in fields where impact strength is required or where painting is required is extremely limited.

In order to improve these drawbacks, many methods have been proposed in the past for mixing crystalline polypropylene with rubber-like substances such as polyethylene, polyisobutylene, polybutadiene, and ethylene-propylene rubber. However, when high-molecular-weight rubbery substances are added to improve impact resistance, the melt viscosity of the composition increases, moldability, especially injection moldability, decreases, and conversely, the melt viscosity increases. If low-molecular-weight rubbery substances are added without increasing C, the impact resistance of the composition will not be sufficiently improved. At present, polypropylene compositions with a good balance of impact resistance and moldability are available.

Recently, attempts have been made to use crystalline polypropylene compositions to make large parts such as automobile bumpers, grills, and trims into resins, and there is an increasing trend toward colorization in these applications.

For such large parts, moldability is particularly important, so it is necessary to reduce the viscosity of the composition, i.e., high melt flow rate (MFR).
However, when such high MFR products are mixed with pigments or dyes for coloring and injection molded, especially when colored using the masterbatch method, unexpectedly, color separation occurs on the surface of the molded product. There are many cases where similar problems occur.
There was a risk that the product value would be lost.

In view of this situation, the present inventors aimed to provide a polypropylene composition for injection molding that has excellent impact resistance, rigidity, and melt flowability, and also has an excellent appearance even when colored with pigments etc.
As a result of preliminary printing, it was discovered that the above objects could be achieved by using a polypropylene composition having a specific melt flowability index, and the present invention was completed.

That is, the present invention provides (A) an isotactic index of 89 or more and a melt of 7.
Polypropylene with a 0-rate of 20 to 150 g/10 m1n: 50 to 90% by weight, (E) Ethylene/α-olefin random copolymer with an ethylene content of 65 to 85 mol%: 5 to 40% by weight, and ( 0) Polyethylene with an intrinsic viscosity [η] of 2.0 to 6.8 dl#: consisting of 0 to 30 Fnk%, and the melt 70-rate of the composition is 6 to 509 ΔOmi, m, and melt fluidity index (N) 3.
The purpose of the present invention is to provide a polypropylene composition for injection molding that has a well-balanced resistance to Ii79E, stiffness, melt flowability, appearance, etc.

In the polypropylene composition for injection molding of the present invention, component (A) has an isotactic index of 89 or more and a melt rate of 70 (MFR: ASTM D 1238 L).
) is in the range of 20 to 150 g/lomin, n% preferably 40 to 100 g/lomin of polypropylene. The isotactic index (TP) in the present invention is A, Zam'b for homopolypropylene.
Macromolecules by elli et al.
13o- announced in 6.925 (1975)
This is the isotactic fraction of methyl groups in triat units according to the m method. Regarding the polypropylene random copolymer, the influence of the comonomer was also taken into consideration.
It can be determined according to the method of Za+nbelli et al. The polypropylene is a homopolymer of propylene or a copolymer of propylene containing 95 mol % or more of propylene and ethylene and/or other α-olefins. If the TP is 89 or less, only a composition with low rigidity can be obtained, and if the MFR is less than 20 l/lomin, the MFR of the product (A) described below will be low and the moldability will be poor. On the other hand, MFR is 150 G'/10m1n
If it exceeds 6.0, the N value will exceed 6.0 and the appearance of the molded product will be poor.

And component (A) is 50 to 90% in the composition of the present invention.
It accounts for 60 to 80% by weight, preferably 60 to 80% by weight, more preferably 65 to 77% by weight.

component CB) has an ethylene content of 65 to 85 mol%;
Preferably, it is an ethylene/α-olefin random copolymer containing 45 to 85 mol%, and preferably has an intrinsic viscosity [η] of 2.0 to 9. Qd//ri, nakandzu<2.5 to s, odl
/9, usually a low crystallinity or amorphous copolymer with a degree of crystallinity by X DB of 10% or less, especially 5% or less. The α-olefin that is combined with ethylene is usually an α-olefin having 6 to 10 carbon atoms,
Specifically, for example, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-
Examples include decene. If the ethylene content is outside the above range, there is no improvement in impact resistance. Also, [η] is 9
．． If more than 0 dl/g is used, the MFR of the composition may decrease or the N value may exceed 6.0 depending on the case, resulting in decreased moldability and poor appearance. The improvement effect on VPJQ properties tends to be somewhat low.

Note that those with crystallinity exceeding 10% have some resistance to f! tf
j It tends to be less effective in improving impact resistance. and component (B
) in the nI composition of the present invention, preferably 10 to 30% by weight, more preferably 15 to 2% by weight.
It accounts for 5% of quintuple groups. When the amount of component (B) is less than 5% by weight, the effect of improving impact strength is small, and when it exceeds 40% by weight, the stiffness, especially in a high temperature atmosphere, is insufficient and the surface hardness is poor.

The component (C) has an intrinsic viscosity [η] of 2.0 to 6.8e.
Ll/9, preferably 6.0 to 6, o dz/
9 range of polyethylene. [η] is decalin solution I
This is a value measured in M16s°0. In addition, polyethylene as used in the present invention is not only an ethylene homopolymer but also has an ethylene content of 96 mol% or more, preferably 97 mol%.
It is a highly crystalline copolymer of the above ethylene and other α-olefins. [η] is 2.0 dl/g
If it is less than [η], there is no effect of improving impact resistance.
If the amount exceeds 6.8617g, the MF of the composition described below
If R is decreased or N value exceeds 6.0, moldability is decreased and appearance is poor. and component (0)
The amount of these in the composition of the present invention is from 0 to 60% by weight, preferably from 6 to 20% by weight, and more preferably from 5 to 15% by weight. Although a composition with sufficient impact resistance can be obtained without adding component (0), adding 61% or more of R gives a good balance between impact resistance and rigidity.
On the other hand, if it exceeds 30% by weight, the heat-resistant rigidity will be insufficient, although this is not the case with component (B).

In addition, the 11 components of each component in the present invention are (A) and (B)
and hl with the total Jd of (0) being 100[1%.

The polypropylene composition for injection molding of the present invention is as described in (4) above.
, (B) and (0), and the MFR of the composition is 6 to 50 g710min, preferably 7 to 209/lomin, and the melt flow curve M(N) is 6.
0 or less, preferably in the range of 2.6 to 2.0.

A composition having an MFR of less than 69,710 m1n has poor moldability, and particularly when molding a large molded product, the molding cycle is increased by 7 cores. On the other hand, those exceeding 50 n/lomiH have poor mechanical strength. Compositions with an N value of more than 3.0 have poor appearance of molded articles. There is no particular limitation as long as the N value is 6.0 or less, but if it is less than 2.0, the melt fluidity will be greatly reduced, and 70- marks will appear on the surface of the molded product, resulting in poor appearance. There is.

The melt fluidity index (N) in the present invention refers to the shear rate (
This is the slope between shear rate: 10'sec' and shear rate: 103sec4 of the flow curve expressed by 10g10D) and shear stress (tag□.τ), and is expressed by equation (I).

The N value is (1) Using a capillary rheometer manufactured by Shimadzu Corporation, nozzle: LOmmφ, L/D: 30
, is a value determined by measuring the melt flow curve under the condition of measurement temperature = 260°O.

The polypyrene composition for injection molded cedar of the present invention can be produced by mechanically mixing each component that has been polymerized separately in advance, or by polymerizing olefins in the presence of a stereoregular catalyst in one polymerization reaction system. It can be obtained by a method in which each component is produced in sequence and mixed uniformly, or by a method in which these methods are kneaded.

When preparing the MI composition of the present invention by mechanically mixing each component, sufficient care must be taken to avoid poor dispersion of each component. As a melt mixer used for mixing,
For example, Banbury mixer, Nigu, twin screw extrusion 4;
Examples include ip and extrusion.

Polymerizing olefins in one polymerization reaction system means
Components (A), (B) in the singular or in the number anti-II are also included in the type.
It means to produce a polymer mixture by sequentially producing (0) and (0), and the catalyst is not deactivated during the production of Jm common components (Shu, (B) and (0)).

As the stereoregular catalyst used in the production of each component of the polypropylene composition for injection molding of the present invention, a catalyst normally used in the production of crystalline polypropylene is used. Typical examples include a transition metal catalyst component such as titanium trichloride or a transition metal component in which four compounds are supported on a carrier as a C transition metal catalyst component, and an alkyl aluminum compound or its halogen compound; hydride,
This is a second-order catalyst system consisting of alkoxides, or a sixth-order catalyst system in which an organic compound containing nitrogen, phosphorus, sulfur, oxygen, silicon, boron, etc. is added to this catalyst system.

Furthermore, as the ethylene-fist α-olefin random copolymer and polyethylene, which are components (B) and (0) in the present invention, those polymerized using a known Ziegler catalyst can also be used.

When producing the polypropylene composition for injection molding of the present invention, antioxidants, ultraviolet absorbers, lubricants, nucleating agents, antistatic agents, flame retardants, pigments, dyes, inorganic or organic fillers are added at any stage of its preparation. Various additives such as additives can be blended within a range that does not impair the purpose of the present invention. Specific examples of the pigment include a11 pigments such as cyanine blue, cyanine clean, perylene, and quinacridone, and inorganic pigments such as titanium oxide and carbon lac. Specific examples of the filler include calcium carbonate, talc, mica, clay, magnesium hydroxide, glass fiber, potassium titanate fiber, and carbon fiber.

Further, when the polypropylene composition for injection molding of the present invention is colored by the masterbatch method, the masterbatch is used in a color density range of usually 10 to 50 times, preferably 25 to 35 times. The number of pigments used in the masterbatch is not limited to one type, and two or more types of pigments may be used as necessary to adjust the color to a desired color. 4, which is the base of the masterbatch. iJ fat is not particularly limited as long as it is an olefin resin, but
Polypropylene-based resins are preferred because they can be easily dispersed in the polypropylene composition for injection molding of the present invention.

The polypropylene composition for injection molding of the present invention has excellent moldability, and the molded products obtained also have low-temperature impact resistance, rigidity,
It has excellent surface hardness, and has an excellent appearance, especially when colored with pigments, and especially when colored using the masterbatch method, without causing any color separation, making it suitable for household goods and appliance parts. Of course, it can be particularly suitably used for large automobile parts such as bumpers, spoilers, instrument panels, grills, and trims.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded.

Example 1 Polyethylene component (hereinafter abbreviated as j component (A)-I-■) with engineering TP: 97 and MFR: 6[]ri/lomin, 76% by weight, ethylene content "i<: 50% by mole,
[η): 3.5 dt/9 and X-ray crystallinity 3
% of ethylene-propylene random copolymer component (hereinafter abbreviated as component (B)-1) 20m [%, and [η):
5.2 dt/q polyethylene component (hereinafter referred to as (a)-
7% by weight (abbreviated as i) in multiple reactors (A), (B
) and (0) components were sequentially produced to obtain a polymer. Next, a heat-resistant stabilizer, a weather-resistant stabilizer, and a rust preventive agent were mixed with the polymer, and the mixture was granulated using a twin-screw extruder to obtain Composition I. The melt flow index 1 & (N) of Composition I was 2.6.

In addition, by changing only the polymerization conditions of component (A)-1-○, composition ■, composition layer, composition ■, composition ■, and composition ■
I got it. Each melt fluidity index (N) is 2.2.2
．． 4.2.7.2.9 and 6.2.

Carbon black 10.5 weight 1J,%, I'rfj titanium chloride 12.0 weight %, iron (III) oxide 4.5 weight j7
i%, polypropylene (MFR: 25 g/lomi
n) 62 jJXBt%, stearic acid gold salt 9.0
The above-mentioned compositions I to ① were mixed in a ratio of 3071'i to 3071'i to the nail foot part of the master patch consisting of 1% by weight, and a bumper was made by injection molding.
C) Molded in J). The conditions at that time were as follows.

Resin temperature: 225°0 Injection pressure (primary): 100kg/aJ (secondary):
70Q/c+n2 Screw back pressure 20kg/aJ Molding time 28580C/cycle Screw shape: Slow compression full flight, L/D-20 product weight 1 stage:
26009 The resulting molded product was examined for color fading.

The results are shown in Table 1. The degree of color separation was determined by visually observing the appearance of the bumper surface and using the following criteria.

◎: Abnormalities such as streaks are not observed at all ○: Slight abnormalities such as streaks are observed, but they are hardly noticeable △: Slight abnormalities such as streaks are observed ×: Injection molding machine (Steel 0 tM Seisakusho i1!-1! S, +45-0, mold clamping force 150 tons)
A test piece was prepared using a resin at a resin temperature of 200°O, and the following physical properties were measured. The results are shown in Table 1.

MFR (G'/10rnin): ASTM D
1238 L bending modulus (k, 7゜m2): AST
M D790 is 'jFl value, -60°0
(kg・cm/am): ASTM D256 Example 2 Component (A) used in Example 1:
97 and MFR: +50%
, ethylene content: 55 mol% instead of component (E)-I, [η): 2.4 dt/9 ethylene-propylene random copolymer (component (B)-11) 12% by weight
, instead of component (0)-1 [η): 12477g
Polyethylene component (component (0)-n) 9 jJt
j? A composition (2) consisting of t% was obtained. Also, component (A)-1
-Change the polymerization conditions of ■Saze 511 composition ■ and composition ■
I got it. Each melt fluidity index (N) is 2.6.2
．． 9 and 6.6.

6.0% by weight of carbon black, 15.01t% of phthalocyanine blue, 1t% of aluminum (6.0% by weight, 11t% of metal stearate, 15% of metal stearate, and 11t% of polypropylene (MFR: 459/10 min) 64.!IS I) 1 part by weight of the master patch consisting of 1 part of the composition (■);
After mixing 60 parts by weight of ■ and ■, injection molding machine (Ube MAX 1)
800) to form a large trim. The conditions at that time were as follows.

Resin temperature: 218°O Injection pressure <1'eK): 110 kg/cm''〃
(2m 75 kg/cm2 Screw back pressure' 22]c (2/am2 when molding
Duration: 93 qec/Sital screw shape: Slow compression Dalmage L/D-20 Product Weight: 1
Average wall thickness of 560 mm: 1.8 mm The color separation of the obtained molded product was measured by θ·1.

The criteria for determining color separation are the same as in Example 1.

Further, test pieces were prepared using the same procedure as in Example 1 for compositions (1) to (2), and physical properties (Wf filli) were measured.

The above results are shown in Table 2.

Claims (1)

[Claims] 1 (A) Polypropylene with an isotactic index of 89 or more and a melt tetra-rate of 20 to 150/10 m1n: 50 to 90 weight Mk, %, (B) ethylene content 65 to 85 mol% of ethylene/α-olefin random co-Jli combination” to 40% by weight,
and (0) polyethylene with an intrinsic viscosity [η] of 2.0 to 6.8 dJ/9: 0 to 60%, and the melt flow rate of the composition is 6 to 50 g80 min and melt flow. A polypropylene composition for injection molding, characterized in that its gender index (N) is 6 or less.