JP2764057B2 - Polypropylene resin composition - Google Patents

Description

The present invention relates to a polypropylene resin composition. Specifically, the present invention relates to a crystalline polypropylene resin composition containing a specific crosslinked polypropylene.

(Prior art)

Crystalline polypropylene is relatively excellent in rigidity and copolymerized with other olefins such as ethylene is used in many applications as an inexpensive polymer excellent in balance between rigidity and impact resistance. However, polypropylene has various problems, such as relatively low crystallinity, not exhibiting excellent physical properties such as original rigidity and transparency, and in some cases, a long molding time. To this end, various nucleating agents have been added. Among them, the method of using a high molecular substance as a nucleating agent is extremely effective and excellent even in a small amount (Japanese Patent Application Laid-Open No. 60-139731, JP-A-60-139731). 61-16944). However, in the former, there is a problem that a polymer substance having a nucleating agent action is expensive, and in the latter, there is a problem that an operation for obtaining a crosslinked polypropylene is complicated, and naturally, there is an odor peculiar to the crosslinked polypropylene.

[Problems to be solved by the invention]

The above-mentioned method using a crosslinked polypropylene is relatively inexpensive and effective, so that if a crosslinked polypropylene free of the odor peculiar to a crosslinked polymer can be obtained, the properties of crystalline polypropylene can be widely improved. It is expected to be possible.

[Means for solving the problem]

Means for Solving the Problems The present inventors diligently searched for a crystalline polypropylene resin composition that solved the above problems, and as a result, found that the above problems could be solved by using a specific polypropylene, and completed the present invention. That is, the present invention is a polypropylene resin composition obtained by melting and mixing 0.01 parts by weight or more of a copolymer of propylene and alkenylsilane cross-linked by irradiation with 100 parts by weight of crystalline polypropylene.

A copolymer of alkenylsilane and propylene obtained by polymerizing alkenylsilane and propylene used in the present invention in the presence of a transition metal compound and an organometallic compound is disclosed in U.S. Pat.No.3,223,686. No. 3,644,306 discloses that an alkenylsilane copolymer is crosslinked to form an elastic copolymer, but it is not known that a crystalline propylene-alkenylsilane copolymer can be crosslinked by radiation. In the present invention, the alkenyl silane used for copolymerization is at least one Si-H
Those having a bond is preferably used, for example, the general formula _{H 2 C = CH- (CH 2} ) n -SiH P R 3-P ( wherein n is 0 to 12, p is 1 to 3, R is the number of carbon atoms A hydrocarbon residue of 1 to 12), specifically, vinyl silane, allyl silane, butenyl silane, pentenyl silane, or 1 to 3 of these monomers.
A compound in which H in the Si-H bond is substituted with chloro can be exemplified.

In the present invention, the crystalline propylene-alkenylsilane copolymer is obtained by polymerization using a catalyst comprising a transition metal compound and an organometallic compound, and as the catalyst, not only those described in the above U.S. Patent, but also Many of the disclosed improved performance catalysts for the polymerization of propylene can be used without difficulty.

As the polymerization method, a bulk polymerization method and a gas phase polymerization method can be adopted in addition to the solvent method using an inert solvent. Here, as the catalyst comprising the transition metal compound and the organometallic compound, a titanium halide is preferably used as the transition metal compound, and an organoaluminum compound is preferably used as the organometallic compound. For example, electron donation of titanium trichloride obtained by reducing titanium tetrachloride with metal aluminum, hydrogen, or organic aluminum, or those obtained by modifying them with an electron donating compound, an organic aluminum compound, and, if necessary, an oxygen-containing organic compound. Transition metal compound catalyst obtained by supporting a titanium halide on a catalyst system composed of a neutral compound, or a carrier such as a magnesium halide or those obtained by treating them with an electron-donating compound, an organic aluminum compound, and optionally an oxygen-containing organic compound. A catalyst system comprising an electron donating compound such as a compound,
Alternatively, a reaction product of magnesium chloride and an alcohol is dissolved in a hydrocarbon solvent, and then treated with a precipitant such as titanium tetrachloride to insolubilize the hydrocarbon solvent and, if necessary, an electron-donating compound such as an ester or ether. , And then a catalyst system comprising a transition metal compound catalyst and an organoaluminum compound obtained by a method of treating with a titanium halide, and an electron-donating compound such as an oxygen-containing organic compound if necessary (for example, Various examples are described in the following references: Ziegler-Natta Catalys
ts and polymerization by John Boor jr (Academic Pr
ess), Journal of Macromorecular Sience Reviews in
Macromolecular Chemistry and Physics, C24 (3) 35
5-385 (1984) and C25 (1) 578-597 (1985)).

Here, as the electron donating compound, oxygen-containing compounds such as ether, ester, orthoester and alkoxysilicon compound can be preferably exemplified, and alcohol, aldehyde, water and the like can also be used.

Examples of the organoaluminum compound include trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, and alkylaluminum dihalide.Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Examples of the halide include chlorine, bromine and iodine.

Here, the polymerization ratio of alkenylsilane and propylene is not particularly limited, but from the viewpoint of easily setting the degree of crosslinking to an appropriate range, alkenylsilane is usually used in an amount of about 0.001 to 30 mol%, preferably 0.01 to 5 mol%. is there.

The molecular weight of the polymer is not particularly limited, but is preferably about the same as the molecular weight of the crystalline polypropylene to be mixed to improve the physical properties. In some cases, the same polymerization (composition, molecular weight, etc.) as that of crystalline polypropylene may be performed except that alkenylsilane is not contained.

In the present invention, the crystalline propylene-alkenylsilane copolymer is irradiated with radiation prior to use.
Examples of the radiation include α-rays, β-rays, γ-rays, X-rays, neutron rays, synchrotron radiation, and the like. Usually, γ-rays and electron beams are preferably used. Irradiation dose is usually a number
Although it is about rad to several tens of Mrad, and varies depending on the content of alkenylsilane, as a general guide, for example, a gel fraction calculated as boiling xylene-insoluble matter is about 0.01 to 90 wt%,
Preferably, it is about 0.1 to 40 wt%. If the gel fraction is too small, there is no effect, and if the gel fraction is too large, when the composition is molded, bumps and the like are generated and not only the appearance is impaired, but also the physical properties are poor.

The mixing ratio of the propylene copolymer irradiated with radiation to the crystalline polypropylene is 0.01 part by weight or more based on 100 parts by weight of the crystalline polypropylene. It is more preferably at least 0.1 part by weight. When the amount is less than 0.01 part by weight, the effect of improving the physical properties is small, and the crosslinked polypropylene is
Except for not containing alkenylsilane, there is no upper limit because it has better physical properties than crystalline polypropylene obtained by similar polymerization, but it is about 50 parts by weight in terms of improvement in physical properties and moldability.

In the present invention, the crystalline polypropylene means not only a homopolymer of propylene, but also a degree that does not lose crystallinity (usually 10 wt% or less in random, 50 wt% or less in blocks).
With propylene and ethylene, butene-1, pentene-1,
Copolymers obtained by random or block copolymerization with other olefins such as hexene-1 and 2-methylpentene-1 can be exemplified. Many of these polymers are already known only in patents and other documents. Instead, various things are available on the market. It can be produced in the same manner as in the above-mentioned method for producing a polymer of propylene and alkenylsilane except that alkenylsilane is not used.

There is no particular limitation on the method of mixing both components, or a method of mixing with known additives such as an antioxidant, an ultraviolet absorber, a lubricant, an antistatic agent, or another nucleating agent, if necessary, and a Henschel mixer. After mixing with a V-type blender or the like, a composition can be obtained by melt-mixing with an extruder, a roll, a Banbury mixer, a kneader or the like.

〔Example〕

Example 1 A vibration mill equipped with four crushing pots having an internal volume of 4 and containing 9 kg of steel balls having a diameter of 12 mm was prepared. Under a nitrogen atmosphere, 300 g of magnesium chloride, 60 ml of tetraethoxysilane, and 45 ml of α, α, α-trichlorotoluene were added to each pot, followed by addition of 40 ml.
Crushed for hours. 300 g of the co-ground product thus obtained was placed in a flask of 5, and after 1.5 parts of titanium tetrachloride and 1.5 parts of toluene were added, the mixture was stirred at 100 ° C. for 30 minutes, and then the supernatant was removed. Add 1.5,
The mixture was stirred at 100 ° C. for 30 minutes, the supernatant was again removed, and the obtained solid was repeatedly washed with n-hexane to obtain a transition metal catalyst slurry. When a part was sampled and the titanium content was analyzed, it was 1.9 wt%.

30 m of the above transition metal catalyst was placed in an autoclave having an internal volume of 5.
g, 0.124 ml of diethylaluminum chloride, 0.06 ml of methyl toluate, 0.08 ml of triethylaluminum, and 1.5 kg of propylene, 10 g of vinylsilane, and 1.4 Nl of hydrogen were added.
Polymerization was performed at 2 ° C. for 2 hours. After 2 hours, unreacted monomers were purged, the powder was taken out, dried and weighed to 540 g
A copolymer containing 0.08% by weight of vinyl silane was obtained. This polymer was placed in a Soxhlet extractor and extracted with n-heptane for 6 hours. The ratio of the extraction residue to the weight before extraction (hereinafter abbreviated as II) was 96.4%. An electron beam (75
0KV) at 2 Mrad. The xylene-soluble matter of this treated product (proportion of extraction residue when extracted in boiling m-xylene with powder in a 100 mesh wire mesh for 6 hours) is 4 wt%.
After heating at 240 ° C. for 10 minutes with a differential thermal analyzer,
The crystallization temperature measured by lowering the temperature at ° C / min was 126 ° C. The melt flow index (measured at 230 ° C. in accordance with ASTM D-1238, shown in g / 10 min) was 14.0.

The following physical properties were measured for a composition obtained by adding 5 parts by weight of the above crosslinked polypropylene to 95 parts by weight of polypropylene JHH-G manufactured by Mitsui Toatsu Chemicals Co., Ltd., and granulating with an extruder.

Flexural ^{modulus: kg / cm 2 ASTM D638 (} 23 ℃) Tensile yield ^{strength: kg / cm 2 ASTM D638 (} 23 ℃) The propylene - more for ethylene copolymers, Izod (notched) impact strength: kg · cm / cm ASTM D256
-56 (20 ° C, -10 ° C) was also measured. The results are shown in Table 1. Further, a sensory test of this composition was carried out, and no abnormal odor was found.

Comparative Example 1 The physical properties were measured in the same manner as in Example 1 without using the crosslinked polypropylene, and the results shown in Table 1 were obtained.

Example 2 As a crystalline polypropylene, a polypropylene block copolymer BJHH-G manufactured by Mitsui Toatsu Chemicals, Inc. was used, and the crosslinked polypropylene obtained in Example 1 was melt-mixed in the same manner to obtain a polypropylene resin composition. When physical properties of this composition were measured in the same manner, the results shown in Table 1 were obtained.

Comparative Example 2 The physical properties were measured in the same manner as in Example 2 without using the crosslinked polypropylene, and the results shown in Table 1 were obtained.

Example 3 A crosslinked polypropylene was obtained in the same manner as in Example 1 except that allylsilane was used instead of vinylsilane. This polymer contained 0.1 wt% of allylsilane, and the xylene extraction residue was 7 wt%. Similarly, the results of measuring the physical properties
It is shown in the table.

Example 4 Polymerization was carried out in the same manner as in Example 1. After polymerization for 2 hours, the temperature was lowered to 50 ° C., ethylene was introduced so that the ethylene partial pressure became 8 kg / cm ² , and 0.15 ml of triethylaluminum was further added.
Polymerization while maintaining ethylene partial pressure for 30 minutes, ethylene content 8.5w
A polymer having a t% of vinylsilane content of 0.07% by weight was obtained.

The copolymer was irradiated with γ-rays at 2 Mrad in the presence of oxygen. The proportion of xylene insolubles was 9 wt%.

Except that this crosslinked polypropylene was used, the same as in Example 2, except that the proportion of the crosslinked polypropylene was 10 parts by weight based on 90 parts by weight of the block copolymer of polypropylene.
Table 1 shows the measurement results of the physical properties.

Example 5 The procedure of Example 4 was repeated except that the proportion of the crosslinked polypropylene was changed to 1 part by weight with respect to 99 parts by weight of the block copolymer of polypropylene. The results are shown in Table 1.

[Effect of the Invention] The composition of the present invention is simple in its production method and excellent in physical properties, and is extremely valuable industrially.

Claims (1)

(57) [Claims] (1) 100 parts by weight of crystalline polypropylene,
A polypropylene resin composition obtained by melt-mixing at least 0.01 part by weight of a copolymer of propylene and alkenylsilane crosslinked by irradiation with radiation.