JPH0269549A - Production of polypropylene-based resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition capable of providing molded products excellent in surface appearance properties without impairing mechanical properties by blending specific amounts of a polypropylene-based block copolymer with polyethylene, crosslinking assistant and radical former. CONSTITUTION:(C) A crosslinking assistant in an amount of 0.1-5 pts.wt. and (D) a radical former in an amount of 0.001-0.2 pt.wt. are blended with 100 pts.wt. total amount of (A) 50-90wt.% block copolymer, consisting of 65-95wt.% propylene homopolymer part and 5-35wt.% ethylene-propylene random copolymer part with 30-80wt.% ethylene content and having 2-25wt.% ethylene content and 0.1-100g/10min melt flow rate and (B) 50-10wt.% block copolymer having >=0.93g/cm<3> density and <=5g/10min melt flow rate.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention consists of a method for producing a polypropylene resin composition, and more specifically, a specific amount of polyethylene resin is blended with polypropylene resin, and a crosslinking aid and a radical generator are added to the polypropylene resin. In addition, this is a method for producing a resin composition obtained by gelling in polypropylene, which is a polyethylene resin, and provides a molded product with excellent surface appearance while maintaining the mechanical properties of polypropylene. Regarding.

[Sakurai's technology]

Polypropylene has various excellent properties such as mechanical properties, chemical resistance, and temperature characteristics, so it is used in a wide range of industrial fields. In addition, due to its good workability, the surface of the molded product has a smooth and glossy appearance, so it is suitable for automobile parts,
It is widely used in the fields of various injection molded products, sheets, films, and blow molded products such as home appliance parts and household goods. It may be a characteristic of polypropylene that it has a good gloss appearance, but in recent years consumers are looking for products with a different texture and lower surface gloss in order to give products a sense of luxury.

In order to reduce gloss, a method has been adopted that roughens the surface of the molded product by adding texture to the surface of the mold in injection molding, or texture to the roll in sheet molding. . On the other hand, in resin cloth, calcium carbonate,
One method is to roughen the surface of the product by adding multiple layers of inorganic fillers such as talc. It is expensive to produce grain marks on molds or rolls, etc., and when performing general molding, it is a hassle to change to molds and rolls with grains, and it is difficult to reduce the gloss sufficiently. Can not.

On the other hand, there are methods such as applying a matte paint to the surface of the molded product, but these methods have problems with process costs and adhesion.

A large amount of inorganic filler is required to mix the inorganic filler and reduce the gloss, which causes a decrease in fluidity during injection molding, and causes flow marks and speckled patterns on the surface due to the inorganic filler. occurs, resulting in a defect that deteriorates the appearance of the molded product.

Furthermore, JP-A-62-277450 proposes a method of melt-mixing polyethylene with a wide molecular weight to a propylene monomer or an ethylene-propylene block copolymer, in which the low molecular weight part is used as a lubricant and the high molecular weight part is used as a lubricant. Although it is said that micro-blending is possible by dispersing it in polypropylene resin, the dispersibility with polypropylene is insufficient, and although the gloss decreases, flow marks and sparkling spots appear on the surface of the molded product, resulting in poor molding. The appearance of the product is unsatisfactory because it has defects that are worse than the base polypropylene.

(Problems to be Solved by the Invention) As a result of intensive study on maintaining the excellent physical properties of polypropylene and reducing gloss, the present inventor has found that the present inventor has a good surface appearance without spots, etc., and maintains the physical properties of polypropylene resin. The present invention was completed by obtaining a polypropylene resin composition.

[Means to solve the problem]

As a result of extensive research in order to reduce the gloss while maintaining the physical properties of polypropylene resin, the present inventors have discovered that a composition manufactured with the following configuration satisfactorily achieves the objective. That is, (A) contains a propylene homopolymer portion obtained by polymerization on the same catalyst and an ethylene-propylene random copolymer portion, the ethylene content is 2 to 25% by weight, and the propylene homopolymer portion is 65 to 25% by weight. 95% by weight, ethylene-
The propylene random copolymer part has a content of 5 to 35% by weight, the ethylene content of the ethylene-propylene random copolymer part has a content of 30 to 80g1fi%, and the melt flow rate has been 0.1 to 10 (l g/lf1min). (B) Polyethylene having a density of 0.Q: 10 g/crn' or more and a melt flow rate of 5.0 g/crn' or less and a melt flow rate of 50 to 90% by weight. and (C) crosslinking aid in an amount of 0.1 to 5.0 parts by weight based on 100 parts of the total amount of (A) and (R).

(0) Total of radical generator (^) and (B) i 10
This is a method for producing a polypropylene resin composition, characterized by heating a mixture of 0.001 to 0.2 parts by weight relative to 0 parts.

By heating the mixture of (A) to (tl) above, the resulting polypropylene resin composition can reduce gloss and obtain matte uniformity without impairing the mechanical properties, which are the advantages of polypropylene resin. This discovery led to the present invention.

The present invention will be explained in detail below.

The ethylene-propylene block copolymer used in the present invention is obtained using a so-called Ziklana-Nta catalyst, and contains a transition metal compound (for example, a titanium-containing compound) as the main catalyst.
, or a carrier-supported catalyst obtained by supporting a transition metal compound on a carrier (e.g., a magnesium compound, a processed product thereof), and a zero polymerization obtained by using an organometallic compound (e.g., an organoaluminum compound) as a cocatalyst. It is manufactured by processes such as slurry polymerization, solution polymerization, and gas phase polymerization.

Here, if the ethylene content of the floc copolymer is less than 2% by weight, the impact resistance will be insufficient, and if it exceeds 25% by weight, the stiffness will be insufficient. Preferably it is 5% by weight to 20ff<ffi%. Also, if the ethylene content of the ethylene-propylene random copolymer part contained in the flock copolymer is less than 30%, the gloss will be high; If it exceeds 80% by weight, the compatibility with the propylene homocopolymer portion is poor.

The problem is that the floc copolymer itself is affected by the low-temperature falling ball. Preferably, the ethylene content of the ethylene-propylene random copolymer portion is 30 to 70% by weight. Furthermore, if the MFR of the block copolymer is less than 0.01, it is difficult to mold the block copolymer.
If the time exceeds 710 minutes, the original impact resistance cannot be satisfied.

Polyethylene is a high-density polyethylene obtained by the so-called Ziegler process, which is obtained by polymerizing ethylene in the presence of a catalyst containing an organic aluminum compound such as triethylaluminum and a titanium halide such as titanium tetrachloride as polymerization catalysts. Polyethylene is obtained by polymerizing ethylene in the presence of a catalyst such as a so-called Phillips catalyst, in which chromium oxide or the like is supported on silica, alumina, zirconia, or the like. This polyethylene is not limited to a homopolymer consisting only of ethylene, but also includes copolymers copolymerized with other α-olefin comonomers. These monomers include propylene, butene-1, pentene-1, hexene-1, octene-1,
4-methylpentene-1,5-methylhexene-1 or the like is used.

If the density of polyethylene is less than 0.9]Og/crn', the stiffness of the composition will decrease significantly, and the MFR will be 5.0g.
If it exceeds 710 minutes, the gloss improves, and even if it is cross-linked, the decrease in gloss is small. Furthermore, if it is less than 10% by weight in the total composition, the decrease in gloss is small, and if it exceeds 50% by weight, the rigidity decreases and This is not preferable because it deteriorates the uniformity of appearance. Preferably the density is 0.940 g/cm″ or more,
In terms of mechanical properties and gloss, it is best to mix 15 to 40% by weight of polyethylene with an MFR of 3 g/10 minutes or less to the polypropylene brow copolymer.

Specifically, as a crosslinking aid, triallyl cyanurate,
triallyl isocyanurate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, diallyl phthalate, pentaerythol triacrylate, neopentyl glycol diacrylate,
Examples include oxime compounds such as 1,6-hexanesiol dimethacrylate, quinone dioxime, benzoquinone dioxime, para-nitrosophenol, N'N-meta-phenylene bismaleimide, or a mixture of two or more of these.

If the cross-linking aid is less than 0.1 part by weight, the cross-linking agent etc. will be reduced, and if it exceeds 5.0 parts by weight, the decrease in gloss will be small, and the cross-linking aid will be surplus in reducing the gloss of wood. Moreover, since the crosslinking aid is expensive, it is not economically preferable.

Organic peroxides are mainly used as the radical generator, and the decomposition temperature (temperature with a half-life of minutes) of this radical generator is preferably higher than the melting point of polyethylene.

Specifically, dibenzoyl peroxide, t-butylperoxy-2-ethylhexoate, -butylperoxydiethyl acetate, -phthylperoxyisopropyl carbonate butylperoxy-:I,
5.5-)-limethylhexoate, t-butyl peracetate, t-butyl perbenzoate, 4.4
-di-t-butylperoxyvaleric acid-lobyl ester 2,2-di-t-butylperoxybutane, dicumyl peroxide, t-butylcumyl peroxide, 1,3-bis(t-butylperoxyiso) Furobyl) benzene, t-butyl peroxide, di-isopropylbenzene-monohytroperoxide, cumene hydroperoxide, t
- Examples include butyl hydroveroxide. 2 again! ! A mixture of the above may also be used.

As a radical generator, if it is less than 0.0 parts by weight, the crosslinking efficiency is poor and low gloss cannot be expected, and if it exceeds 0.2 parts by weight or 14 parts by weight, polypropylene parts may be cut and the mechanical properties may be deteriorated, which is not preferable.

The method for producing the composition of the present invention involves blending the propylene-ethylene block copolymer with polyethylene, a crosslinking aid, and a radical generator in a predetermined amount, adding a predetermined amount of additives such as an antioxidant, and using a conventional mixing device. 1 For example, mix using a Henschel mixer, super mixer, ribbon blender, tumbler mixer, etc., and mix these using a screw extruder (single-screw, twin-screw), heating roll, Banbury mixer, etc. at a normal melt mixing temperature of 150 ~ 300°C1 preferably 1
It can be obtained by a process of melting and cross-fermenting pelletizing at 80 to 250°C.

At that time, various fillers such as antioxidants, ultraviolet absorbers, lubricants, nucleating agents, antistatic agents, flame retardants, pigments, dyes or inorganic or organic fillers such as talc, calcium carbonate, and reinforcing agents are added according to the present invention. They can be blended within the range that does not impair the purpose.

[Effect]

Polyethylene with good dispersibility is melt-kneaded into the base ethylene-propylene block copolymer, and at the same time crosslinking of the polyethylene catalyst is started using a crosslinking aid and a radical generator. It is presumed that it behaves like an inorganic filler in molded products and reduces gloss by slightly roughening the surface of the molded product.

By microdispersing polyethylene, the gloss can be lowered without impairing the physical properties of polypropylene, and the density can be lower than when a filler is mixed.

〔Example〕

The present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Each measurement value shown in the Examples was measured according to the following measurement method.

Ethylene content and propylene content were measured using infrared spectroscopy. The MFR density of polyethylene is JIS-
6760, the MFR of polypropylene is J
Measured using IS-6758. For gloss, gloss uniformity, and falling ball impact, injection molding (Sumitomo Nestal 3480
/+50) by 120@IX 150ssx
A 2as flat plate was prepared and measured one day later.

Gloss was measured in accordance with JIS-Z8741.

The uniformity of gloss was visually observed and ranked.

O: Good smoothness and no spots etc.; X: Spots are visually observed or streaks caused by spots are generated.

Regarding the impact of a falling ball, place it on a 2inΦ "receiver",
Calculated from the probability of a ball falling from a height of 1 meter and breaking a 2 inch diameter hemisphere with varying loads.

(Examples 1 to 6, Comparative Examples 1 to 4) PP-1 is an ethylene-propylene block copolymer (hereinafter referred to as floc PP) with a concentration of Og/lo, and the ethylene content in the block Pp is 10, 4% by weight, the ethylene-propylene random copolymer portion is 21.0% by weight, and the ethylene-propylene random copolymer portion is 50.0% by weight.

HD-1 is VFRo, 80g/10min, density 0.9
This is an ethylene-phthene-l copolymer obtained with a Ziegler catalyst of 53 g/crn'. Radical generator PO-1
1.3-bis(t-butylperoxyisopropyl)benzene was used as the crosslinking aid CA-1, and 1~lylylisocyanurate was used as the crosslinking aid CA-1.The mixture was placed in a Henschel mixer and mixed for 3 minutes with the formulation shown in Table 1. Later 2 caliber 4
The mixture was melt-kneaded and pelletized using a 0 mm extruder at a melt-kneading temperature of 220°C. The obtained pellet was injection molded to form a double thick flat plate, and the gloss level, surface appearance uniformity, and falling ball test were evaluated. The results are shown in Table-1.

Comparative Example-1 has only block PP used for the base;
In Comparative Example 2, block PP and polyethylene were simply melt-kneaded. Compared to these, crosslinking modification was performed. Examples 1 to 3 had significantly lower gloss, showed good values in the falling ball test, had no visible gloss spots, and had good surface appearance uniformity. Further, Examples 4 to 6 in which the concentrations of PO-1 and CA-1 were changed also had low gloss levels showing good physical properties as in Example 1. It should be noted that low gloss was judged to be good if the gloss was 20% or more lower than the base block PP (gloss ≦40%). Polyethylene or 5 from Comparative Example 3.4
If the weight ratio is 60% by weight, the reduction rate of gloss is too small to achieve this purpose.

(Example 7) The same treatment as in Example 1 was performed except that the crosslinking aid (CA-2) was changed to N,N-metaphenylene bismaleimide.

Low gloss crystals similar to those in Example 1 were obtained.

(Example 8) MFR of polyethylene (HD-2) = 1.1g/1
The same treatment as in Example 1 was carried out except that polyethylene (Shorex 5S6008FD) obtained with a Phillips-based catalyst having a density of 0.956 and a density of 0.956 was used. Low gloss crystals similar to those in Example 1 were obtained.

(Comparative Example 5) The base polypropylene was changed from block PP to homopolypropylene (PP-2VFR = 8g/10 minutes),
The same treatment as in Example 1 was performed. Although the gloss is similarly reduced, the falling ball test is significantly worse, and it cannot be used as an industrial part in the impact-resistant field.

(Example 9, Comparative Example 6) PP-3 is lock FR2: Ig / 10 minute block pp
The ethylene content in the floc PP is 10.3% by weight, and the ethylene-propylene random copolymer portion is 22% by weight.
The ethylene content of the ethylene-propylene random copolymer was 53.0% by weight, and this floc P
The same treatment as in Example 1 was carried out using P. Compared to the base flock PP shown in Comparative Example 6, a similar low gloss product was obtained, and it was found that even a high MFH product could be obtained with sufficiently good low-temperature falling ball impact.

(The following is a blank space) [Effect of the invention] The polypropylene composition according to the present invention can be used as a matte material required for household goods, home appliance parts, automobile parts, etc.
A lightweight product equivalent to original polypropylene can be obtained without adding a large layer of fillers, etc. In addition, it is possible to obtain a matte molded product without using a grain mold in injection molding or blow molding or a grain roll in sheet molding, and it can be applied to various fields, and it is possible to obtain a product with a luxurious feel due to the matte finish. I can do it.

Claims (1)

[Claims] (1) (A) Contains a propylene homopolymer portion and an ethylene-propylene random copolymer portion obtained by polymerization on the same catalyst, the ethylene content is 2 to 25% by weight, and the propylene homopolymer portion is 65 to 95% by weight, the ethylene-propylene random copolymer portion is 5 to 35% by weight, the ethylene content of the ethylene-propylene random copolymer portion is 30 to 80% by weight, and the melt flow rate is 0. (B) polyethylene having a density of 0.930 g/cm^2 or more and a melt flow rate of 5.0 g/10 minutes or less; (C) a crosslinking aid of 0.1 to 5.0 parts by weight based on 100 parts of the total amount of (A) and (B); (D) a radical generator (A); and (B) total amount 100
0.001 to 0.2 parts by weight per part of the polypropylene resin composition.