JPS60190409A - Polypropylene block copolymer for injection molding - Google Patents

Abstract

PURPOSE:The titled copolymer that is obtained by polymerization of more than half amount of propylene with a stereo-regular polymerization catalyst followed by copolymerization of propylene and ethylene, thus showing good valance between toughness and impact strength and large elongation on breakage. CONSTITUTION:A stereo-regular polymerization catalyst such as TiCl3-(C2H5)2 AlCl is used to polymerize propylene of less than 3wt% ethylene up to 60- 95wt% polymer yield, then the copolymerization of propylene and ethylene at a weight ratio of 90/10-10/90 at room temperature - 90 deg.C and normal pressure - 50kg/m<2> is conducted in the bulk or gas phase process by 40-5wt% of the total polymer to give the objective copolymer satisfying the equation where Tc is the maximum crystallization temperature which is measured by means of differential scan thermoanalysis, Mw weight average molecular weight and Mn number average molecular weight which have been measured on the insoluble fraction in light oil at 30 deg.C by means of GPC.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyzolopyrene block copolymer for injection molding, which has an excellent balance between rigidity and impact resistance, and has a large elongation at break.

There is a block copolymer of propylene and ethylene that maintains the original high rigidity of polypropylene and has improved impact resistance, especially impact resistance at low temperatures. Copolymerize with 60 to 95% by weight of the total polymer, then propylene and ethylene at a weight ratio of 9fl/10 to 10/'
A polypropylene block copolymer obtained by polymerizing at 90°C to obtain 40 to 5% by weight of the total polymer is desirable because it has a relatively excellent balance of rigidity and impact resistance and meets market demands. . In order to further improve this desirable polypropylene block copolymer, many methods have been proposed in which the polymerization ratio of propylene and ethylene is further varied within the above range, or in which the molecular weight is varied.

On the other hand, recent demands for resource and energy conservation have led to demands for further improvements in rigidity and impact resistance, as well as improvements in flowability during molding. In order to improve flowability during molding, the molecular weight of the polymer is lowered and the melt flow index (hereinafter abbreviated as MFI) is increased.

By the way, if such measures are taken, the flowability during molding will be
However, for reasons unknown, the elongation at break, which is said to be correlated with the impact resistance of actual molded products, is
As I increases, the value decreases rapidly, which causes a problem when molded.

Therefore, the reality is that a polypropylene block copolymer that has high rigidity and impact resistance as well as high elongation at break is desired.

As a result of intensive searches for polypropylene block copolymers that solved the above-mentioned problems, the inventors of the present invention discovered that those having specific physical properties had a large elongation at break, and completed the present invention.

An object of the present invention is to provide a polypropylene block copolymer that has an excellent balance of rigidity and impact resistance, and has high elongation at break.

That is, the present invention uses a stereoregular catalyst to convert ethylene into 3
#6 of the total polymer by polymerizing propylene that is less than % by weight
0 to 95% by weight and then propylene and ethylene in a weight ratio of 9 Q/'10 to In/9 ('l) to obtain 5 to 40% by weight of the total polymer. It is a polypropylene block copolymer, and the peak temperature (
i″C) and 3(1′ of polypropylene block copolymer)
The ratio of the weight average molecular weight (Mw) to the number average molecular weight (H4n) measured by gel permeation chromatography of the part of C that is insoluble in white kerosene and insoluble in boiling n-hebutane (
84w/'M+1) is expressed as 1 expression % expression %)) In θ), E, rays characterized by 11
A polypropylene block copolymer for molding.

In the present invention, differential thermal scanning calorimetry (hereinafter referred to as DSC)
It is abbreviated as ) measurements are usually carried out using commercially available equipment. This specific measurement method is well known, for example, New Experimental Chemistry Course 19 [edited by the Japanese Society of Physical Chemistry]
Polymer Chemistry nJ (September 30, 1978, Maruzen Co., Ltd.)
(Issuance) pages 890-893.

In addition, it is the temperature of the maximum crystallization temperature measured by I) SC, and when a plurality of peaks are measured, it is the temperature of the maximum peak.

In the present invention, insoluble in white kerosene at 30°C and boiling n
- The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw/Mn) measured by gel permeation chromatography (hereinafter abbreviated as GPC) of the part insoluble in heptane is It is measured as follows.

The white soluble portion of the polypropylene block copolymer at 130°C is separated. After washing the insoluble portion with white kerosene 4 times, boiling water was removed using a Soxhlet extractor.
Extract with hebutane for 6 hours to obtain the portion insoluble in boiling n-hebutane. Next, the Mw/M n of the core is measured by GPC. This GPC measurement was performed at 135°C with 1.
Measured using 2,4-trichlorobenzene as a medium. The molecular weight can be calculated using the standard molecular weight of polystyrene, and the Q factor ratio of 0.639 (Q factor of polypropylene/'Q factor of polystyrene) can be used.

In the present invention, Mw/Mn and Tc determined in F are required to satisfy the following relational expression.

115 (12(1, (1-Tc) -1-(Mw/M
n-3,5) ) O has a small elongation at break, resulting in poor actual impact resistance of the injection molded product.

In the polymerization to obtain a block copolymer in the present invention, a stereoregular catalyst is used to first copolymerize propylene alone or with 3% by weight or less of ethylene to achieve a total polymerization of 60 to 95% by weight of the total polymer. '%, then propylene and ethylene at a weight ratio of 90%.
/1 (1 to 10./'90 and the total polymer is 40 to
There are no particular restrictions on conditions other than the weight of 5 weight scale.

If the initial polymerization is carried out under conditions where the ethylene content is more than 3% by weight, the original rigidity of polypropylene will be lost, which is not desirable.
If it is less than 0% by weight, the rigidity will be poor, and if it is more than 95% by weight, the impact resistance (especially at low temperatures) will be poor. The reaction ratio of propylene and ethylene in the subsequent polymerization is
If the ratio is larger than 90/lO, the improvement in impact resistance is insufficient, and if the ratio is smaller than 90/1O, the improvement in impact resistance is similarly insufficient.

As a polymerization method for obtaining a block copolymer, a solvent polymerization method using an inert hydrocarbon medium, a bulk polymerization method using propylene itself as a medium, or a gas phase polymerization method can be adopted, and is usually carried out at room temperature to 90°C. The polymerization reaction is carried out at a pressure of ~50 kg 7 m''.The catalyst used is a catalyst system that provides highly stereoregular polypropylene, such as titanium trichloride, a eutectic of titanium trichloride and aluminum trichloride, or a complex thereof. Catalyst systems consisting of treated or complexed materials and organoaluminum compounds, catalysts obtained by supporting trivalent or tetravalent titanium compounds, especially halides, on carriers such as magnesium halides, and organoaluminum compounds. Examples include a catalyst system consisting of -[two-catalyst tMJF] to which complexes such as esters, ethers, amines, and alkoxysilicone are added.

There are many known methods for obtaining block copolymers with a good balance between rigidity and impact resistance by controlling the reactions in the first and second stages. As for ratios, the special public interest rate is 1974-2.
No. 0621, JP-A No. 53-35789, JP-A No. 49-
No. 40156, Special Publication No. 49-24593, Special Publication No. 47
-26190, etc., as for those related to molecular weight, Japanese Patent Publication No. 14-19542, Japanese Patent Publication No. 47-7141,
JP-A-49-61278, JP-A-50-142652
No. 1989-139693, etc., and those using specific equipment such as a reactor are described in Japanese Patent Publication No. 49-12589 and JP-A No. 57-1.
No. 45115, JP-A No. 57-170915, and the like. In the present invention, it may be obtained by any of the above methods.

The block copolymer thus obtained has a `rc of 110
~130°C, but Tc depends not only on the composition of the polypropylene block copolymer itself obtained by polymerization, but also on preservatives, antioxidants, ultraviolet absorbers, and antistatic agents added during granulation. , nucleating agents, pigments, residual catalyst residues in some cases, polyethylene wax or liquid paraffin added to improve fluidity, or talc, calcium carbonate, mica, etc. added to improve rigidity. may also change. Therefore, the polypropylene block copolymer (which corresponds to the polypropylene block copolymer for injection molding as referred to in the present invention, which is usually It is necessary to control the Tc of the granulated material to be appropriate.

8 In the present invention, as is clear from the above formula, Mw/M
If n is relatively large, the appropriate range of I"c will be widened, which is advantageous. However, Mw/Mn of polypropylene
tends to decrease as the molecular weight of polypropylene decreases, and especially in highly fluid polypropylene block copolymers (mel l flow index of 10 or less measured at 230°C), by appropriately controlling Te, the above formula If the conditions are not satisfied, the elongation at break will decrease.

As a method for increasing Mw/Mn, it is possible to use a catalyst that is inferior to polypropylene, which has a relatively wide molecular distribution, such as a catalyst consisting of magnesium halide and titanium halide, a catalyst consisting of an organic acid ester, and an organic aluminum, or It is preferable to adopt a method in which the first stage polymerization is further divided into several stages to obtain polypropylene having different molecular weights, since the allowable range of Tc is relatively wide.

The polypropylene block copolymer of the present invention has an excellent balance of rigidity and impact resistance, and has a large elongation at break.
It is excellent for injection molding and 17.

The present invention will be explained below with reference to Examples.

Reference Example (Manufacture of Block Copolymer) ■) A block copolymer with an ethylene content of 10.0% by weight was prepared by first copolymerizing propylene alone and then ethylene and propylene by the method of Example 1 of JP-A-57-149320. A polymer was obtained. However, at this time, the polymer obtained by polymerizing alone with propylene has an intrinsic viscosity number (c or less, abbreviated as η) measured in a tetralin solution at 135°C of 1.15, which is 83% by weight based on the total polymer. The copolymerization section of ethylene and propylene in the latter stage is carried out in two further stages, and initially the reaction ratio of propylene/ethylene is 5 (1/'50 by weight) so that a polymer of 8% by weight of the total polymer is produced. and then propylene/' to give a polymer strength of 9% by weight of the total polymer.
Polymerization was carried out at an ethylene reaction ratio of 32/68 by weight, and the copolymer obtained in the subsequent copolymerization had a η of 2.85. The block copolymer powder thus obtained is η=1
．． 44, and the ethylene content was 10.1% by weight. This powder is designated as sample A.

ii) 11 to 3 heptane in a l m3 autoclave
(H) 7. Add 41 highly active titanium trichloride catalyst (round pillar vine, TGY-24 manufactured by Niichi Co., Ltd.) and 320 ml of diethylaluminium chloride, then charge propylene, and set the total pressure (gauge) to 70 kg/iM. Polypropylene 102 was obtained by first polymerizing propylene alone at 10°C. After the temperature was lowered to 50° C., ethylene and propylene were charged to carry out copolymerization of ethylene and propylene to obtain a propylene block copolymer having a total amount of 1231c9.

At this time, the initial polymerization of propylene alone was controlled by charging hydrogen so that η was 1.28, and the copolymerization part was controlled so that η was 3.
Hydrogen was charged and controlled so that the temperature was 0.02. The reaction ratio of propylene and ethylene in the copolymerization part is 60/411 by weight.
Met.

The obtained copolymer slurry was washed with water after deactivating the catalyst with methanol, and then filtered to obtain a polypropylene block copolymer. The obtained block copolymer has η of 1.
50, and the ethylene content was 11-6.9% by weight. This powder will be referred to as sample B.

Examples 1 to 5 and Comparative Examples 1 to 4 Using samples A and B, 2,6-ditertiary-butyl p-cresol 10/10000 weight ratio (to powder)
and calcium stearate in a weight ratio of 10/10,000, and then granulated with or without the addition of a nucleating agent, peroxide, and calcium carbonate, respectively, to obtain pellets. 8 (IX) in the injection molding machine for each pellet.
A sheet of 16 m x 2 mm was manufactured and its physical properties were measured. Also, Mw/Mn of Tc and boiling n-hebutane insoluble matter
was measured.

1 The results are shown in the table.

In addition, the physical properties were measured according to the following.

Melt 7o-index (9740min) ASTM
D1238 Yield stress (kμ) A, STM D6
38-%4. Elongation at break (%) ASTM D63
8-64T bending rigidity (kgfil) ASTM D
747-63 Dupont (kg・crfL/'1/'2
961su JIS K6718 Izotsu l- (with notch)
(kg・crrL/'Crn) ASTM D256-5
612-

Claims (1)

[Claims] 1) Polymerize propylene containing 3% by weight or less of ethylene using a stereoregular catalyst to produce 60 to 95% by weight of the total polymer.
and then propylene and ethylene at a weight ratio of 90/'1
(Polymerized at '1~10/'9 (') and total weight of 40~
5% by weight of the obtained polypropylene block copolymer, and the peak temperature (T c ) of the maximum crystallization temperature measured by differential thermal scanning calorimetry.
Weight average molecular weight (Mw) and number average molecular weight (M
A polypropylene block copolymer for injection molding, characterized in that the ratio (Mw/Mn) of n) is expressed by the following formula: