JPH0577309A - Transparent impact-resistant molded item - Google Patents

Abstract

PURPOSE:To improve transparency and improve impact resistance by performing blow molding of a resin compsn. contg. a polypropylene having a specified structure or a polyolefin copolymer having a specified structure. CONSTITUTION:Blow molding of a resin compsn. contg. a polypropylene having substantially syndiotactic structure or contg. a polypropylene having syndiotactic structure and an ethylene-propylene copolymer is performed. In this case, the polypropylene having substantially syndiotactic structure is obtd. by e.g. E. Wen's method and is pref. obtd. by using an isopropyl hafnium dichloride catalyst, namely, a catalyst consisting of a transition metal compd. having an asymmetric ligand and aluminoxane. As the method for blow molding, basically a parison is molded and it is fed into a mold and then, blow molding is performed by pressing compressed air thereinto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene molded article which is transparent and has excellent impact resistance. Specifically, a transparent impact-resistant molded product obtained by blow molding a polypropylene having a substantially syndiotactic structure, or a composition comprising a polypropylene having a substantially syndiotactic structure and a copolymer of ethylene and propylene. And a transparent, good impact-resistant multi-layer molded product having a layer of polypropylene of substantially syndiotactic structure on at least one surface of the molded product obtained from this composition.

[0002]

BACKGROUND OF THE INVENTION Syndiotactic polypropylene has long been known to exist, but the conventional method of low-temperature polymerization using a vanadium compound, an ether and an organoaluminum, gives polypropylene having poor syndiotacticity. However, it cannot be said that the characteristic of syndiotactic polypropylene is exhibited, let alone the copolymer of ethylene and propylene obtained by using the above-mentioned catalyst is hardly referred to as crystalline polypropylene.

On the other hand, J. A. It was discovered by Ewen et al. For the first time that a polypropylene having a good tacticity with a syndiotactic pentad fraction of more than 0.7 can be obtained by a transition metal catalyst having an asymmetric ligand and a catalyst comprising aluminoxane ( J.
Am. Chem. Soc. , 110 , 6255-625
6 (1988)).

The above J. A. Molded articles from syndiotactic polypropylene obtained by the method of Ewen et al. Have good transparency and relatively good rigidity, but have a problem of poor impact resistance at low temperatures.

On the other hand, isotactic polypropylene is inexpensive and has good heat resistance, so that it is blow-molded and used for manufacturing bottles and the like.

However, a molded article made of isotactic polypropylene has good heat resistance but is not sufficiently transparent, and further has poor low-temperature impact resistance, so that the low-temperature impact resistance is improved. When a block copolymer with ethylene is used, the transparency is further impaired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polypropylene molded product having good transparency and excellent impact resistance.

Another object of the present invention is to provide a polypropylene blow-molded article having good transparency and excellent impact resistance.

A further object of the present invention is to provide a polypropylene multi-layer molded article having good transparency, excellent impact resistance and hardness.

Other objects of the present invention will be apparent from the following description.

[0011]

The above objects of the present invention can be achieved by the following polypropylene moldings.

Transparent impact-resistant molding obtained by blow molding a substantially syndiotactic structure polypropylene or a resin composition containing substantially syndiotactic structure polypropylene and a copolymer of ethylene and propylene. object.

A molded article obtained from a resin composition containing substantially syndiotactic polypropylene and a copolymer of ethylene and propylene, at least one surface of which has substantially syndiotactic structure. A transparent impact-resistant molded product having good rigidity, which is a layer.

Polypropylene having a substantially syndiotactic structure is obtained, for example, by the method of Ewen et al. Suitable catalysts include asymmetric ligands such as isopropyl (cyclopentadienyl-1-fluorenyl) hafnium dichloride disclosed by Ewen et al., Or isopropyl (cyclopentadienyl-1-fluorenyl) zirconium dichloride. A catalyst system comprising a transition metal compound having a and an aluminoxane.
Examples of aluminoxanes include those obtained by condensing alkylaluminum with water, particularly methylaluminoxane,
Particularly, those having a degree of polymerization of 5 or more, and more preferably 10 or more are preferably used.

When a propylene homopolymer is produced even with a catalyst system different from the above, the syndiotactic pentad fraction (A. Zambelli) of the obtained polymer is obtained.
Et al., Macromolecules 6 , 687 (19).
73), ibid. 8 , 925 (1975)) and a catalyst system that gives a polymer having a relatively high tacticity of about 0.7 or more, and can be used, for example, a transition metal compound having an asymmetric ligand and A catalyst system consisting of organoaluminum is effective.

The ratio of the transition metallization having the above asymmetric ligand and the aluminoxane is preferably 10 to 1,000.
The molar amount is 10,000 times, especially 50 to 5,000 times. When organoaluminum is used, it is preferably 0.1 to 100,000 mole times, and particularly 1 to 10,000 mole times the transition metal compound.

The polymerization method is not particularly limited, and a solvent polymerization method using an inert medium, a bulk polymerization method in which substantially no inert medium is present, or a gas phase polymerization method can be used.

The polymerization temperature is generally -100 ° to 200 ° C., and the polymerization pressure is generally atmospheric pressure to 100 kg / cm ² (gauge pressure). Especially -100 ° to 100 ° C and normal pressure to 50 kg
A polymerization temperature and pressure of / cm ² (gauge pressure) are preferably used.

Although the polymerization can be carried out with propylene alone,
Ethylene or carbon number 4 or more in an amount of 10% by weight or less,
Preferably 4 to 20 α-olefins such as butene-
1, pentene-1, hexene-1, heptene-1, 4-
It is also possible to copolymerize methylpentene-1. 1
If it is more than 0% by weight, the characteristics of the molded product from the resin composition containing the ethylene-propylene copolymer will be poor.

When the polypropylene having a substantially syndiotactic structure is a homopolymer of propylene,
The syndiotactic pentad fraction is 0.6 or more,
Particularly, 0.7 or more is preferable. Those smaller than 0.6
It is not preferable because the properties as crystalline polypropylene are not sufficient and the physical properties are poor.

In the case of a copolymer with another α-olefin, it was measured with a 1,2,4-trichlorobenzene solution.
^In the absorption spectrum of ¹³ C-NMR, about 20.2 p
The peak intensity observed in pm is 0.3 or more, preferably 0.5 or more of the peak intensity assigned to all methyl groups of the propylene unit. If it is less than 0.3, the physical properties are poor, which is not preferable.

The polypropylene having a substantially syndiotactic structure has a molecular weight of 0.1 to 20, preferably 0.1, as an intrinsic viscosity measured with a tetralin solution at 135 ° C.
It is about 5 to 10.

The ethylene-propylene copolymer preferably has an ethylene content of 10 to 95% by weight. Copolymers with an ethylene content outside this range do not show the effect of improving impact resistance even when blended with polypropylene having a substantially syndiotactic structure. Above all, the ethylene content is 15 to 90
Weight% is preferable. In this copolymer, it is possible to substitute 50% or less of ethylene with an α-olefin having 4 or more carbon atoms.

The above copolymer has a glass transition temperature of -10.
It is preferably below ℃, especially below -20 ℃. Especially preferred
What is important is that it is a polypro with substantially syndiotactic structure.
Well compatible with pyrene or slightly in the above propylene
It is a copolymer that is dispersed as particles. Compatibility of the above
As the copolymer, the propylene chain is racemic.
It is something. The degree of this racemate is 6 in the polymer chain.
Looking at one monomer unit, two or three propene
Expressed as a continuous racemic fraction of len, this structure is ¹³C-N
It can be known by MR. For example, Asakura et al., Po
lymer129, 2208 (1988) for details
It has been tell. Further, with a copolymer dispersed as fine particles
It has a relatively low melt viscosity and visible light when mixed and dispersed.
Those that are dispersed in fine particles smaller than the wavelength of
Can be

Such a copolymer is a titanium-based catalyst,
It can be produced using various catalysts such as vanadium-based catalysts or metallocene-based catalysts. Various kinds of such copolymers are available on the market.

The molecular weight of this copolymer is preferably 0.1 to 20 and more preferably 0.5 to 10 in terms of the intrinsic viscosity measured with a tetralin solution at 135 ° C.

The weight ratio of the polypropylene to the copolymer in the resin composition comprising the polypropylene of substantially syndiotactic structure and the copolymer of ethylene and propylene is preferably 30/70 or more, particularly 45/55 or more. The upper limit of the weight ratio is preferably 99/1.

When the above weight ratio is less than 30/70, the molded product made from the resin composition has poor rigidity and impact resistance at low temperature is poor.

When the upper limit value exceeds 99/1, there is almost no effect of improving the impact resistance of the molded product made of the resin composition, and there is no difference in impact resistance as compared with polypropylene having a syndiotactic structure.

A particularly preferred range of the above weight ratio is 55 /
It is in the range of 45 to 98/2.

The above resin composition is produced by mixing substantially syndiotactic polypropylene and a copolymer of ethylene and propylene in the above weight ratio using a kneader capable of performing good mixing. To be done. Alternatively, the resin composition can also be obtained by a so-called block copolymerization method in which propylene is first polymerized to form polypropylene having a substantially syndiotactic structure, and then ethylene and propylene are copolymerized in the polymerization system. .. Better results can be obtained by a method in which the copolymer in which the propylene chain is racemic is strongly kneaded with polypropylene having a substantially syndiotactic structure.

As the above-mentioned kneader, for example, an extruder provided with a twin screw, a Banbury type kneader, or the like capable of relatively strong kneading is used. The kneading temperature is preferably 150 ° to 350 ° C., particularly preferably 1
It is 80 ° to 300 ° C. When the above-mentioned copolymer having a racemic propylene chain is kneaded with polypropylene having a substantially syndiotactic structure to obtain good results, the degree of kneading is determined by measuring the glass transition temperature by analysis of dynamic viscoelasticity. Then, kneading is carried out until the transition attributed to the ethylene-propylene copolymer is no longer observed.
Here, the transition is not observed means that the peak of tan δ attributed to the copolymer of ethylene and propylene is about 1/3 of that before mixing, as measured by dynamic mechanical thermal analysis.

The resin composition thus obtained or polypropylene having a substantially syndiotactic structure is blow molded. As a blow molding method, any method can be basically used as long as it includes steps of molding a parison, supplying the parison to a mold, and then pressurizing and compressing compressed air or the like. In particular, various methods are known in the parison molding stage, and these methods can also be adopted. For example,
Molded into a cylinder by extrusion molding, followed by blowing, cooling and cutting a cylindrical molded product, then further heating and blowing, or injection molding to form a cylinder,
Then, there is a method of blowing. A molded product obtained by molding a resin composition consisting of polypropylene having a substantially syndiotactic structure and a copolymer of ethylene and propylene has good impact resistance at low temperatures, but has a problem of slightly poor hardness. There is. This problem,
This can be solved by making at least one surface of the molded product from the above resin composition a polypropylene having a substantially syndiotactic structure.

The method for producing such a multilayer molded article is not particularly limited, and various methods such as multilayer blow molding, multilayer injection molding, and multilayer extrusion can be adopted. What is important here is that the surface requiring hardness is made of polypropylene having a substantially syndiotactic structure. As the polypropylene having a substantially syndiotactic structure, a propylene homopolymer having such a structure is particularly preferable.

The thickness ratio of the resin composition layer to the polypropylene layer is 1/1 to 1 / 0.001, particularly 1/0.
The range of 5 to 1 / 0.05 is preferable.

In a molded product such as a bottle formed by blow molding, it is possible that only the outer layer is made of polypropylene having a substantially syndiotactic structure and the inside is not provided with a polypropylene layer having a substantially syndiotactic structure. ..

[0037]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. In the examples, G after the pressure indicates gauge pressure, and wt% indicates weight%. Example 1 a) Isopropylcyclopentadienyl-1- synthesized according to a conventional method in an autoclave having an internal volume of 7 liters.
15 mg of isopropyl (cyclopentadienyl-1-fluorenyl) zirconium dichloride obtained by purifying fluorene by lithiation and reaction recrystallization with zirconium tetrachloride and methylaluminoxane (polymerization degree: 16.1) manufactured by Tosoh Akzo Co., Ltd. ) 2 g was dissolved in 3 l of toluene. Propylene at 20 ° C. was charged into the autoclave to ^{4kg / cm 2 -G, 4kg /} cm 2 -G
Polymerization was carried out for 1 hour while adding propylene so that Then, propylene was purged from the autoclave to 0.5 kg / cm ² -G, a part of the slurry was sampled, filtered and dried to obtain a polymer. This polymer was dissolved in 1,2,4-trichlorobenzene to obtain ¹³ C-NM
When analyzed by R, the ratio of syndiotactic pentads was 0.93.

B) Then, insert into the autoclave described above.
3 kg / cm² -Add G for 20 minutes
It matched. After the polymerization was completed, unreacted mono
The resulting powder was obtained by purging the polymer and filtering the polymerization mixture.
After washing 5 times with 1 liter of hexane each time,
It was dried under reduced pressure at 0 ° C. to obtain 220 g of a polymer. ¹³
Analysis of the polymer by C-NMR revealed that the polymer
Ethylene content of 12.4wt%, syndiotactic
The proportion of pentads was 0.78. Also, 135 ℃
Intrinsic viscosity (hereinafter referred to as η
Is 1.24, which is 1,2,4-trick at 135 ° C.
Weight average molecular weight and number average fraction measured with lorobenzene solution
The ratio of the offspring (hereinafter referred to as MW / MN) was 6.7.
It was Before and after starting the copolymerization of ethylene and propylene
Ethylene-propylene copolymer calculated from slurry concentration
The proportion of body to total polymer is 32 wt%, therefore
It can be estimated that the ethylene content of the copolymer is 41 wt%.
It

C) The polymer thus obtained was further heated at 210 ° C. by an extruder having a diameter of 30 mm manufactured by Ikegai Co., Ltd.
After kneading, the mixture was kneaded with a blow molding machine manufactured by Placo Co., Ltd. at a parison molding temperature of 195 ° C. and a blow mold temperature of 20 ° C. to manufacture a blow bottle having an internal volume of 750 ml.

For this molded product, the haze (%) was calculated as AS.
A sample for measurement of Izod impact strength (kg · cm / cm) is cut out from a blow bottle in accordance with TM D1003, and ASTM D256 (23 ° C, -10 ° C)
It was measured according to. The result is a unit weight of 41 g and a haze of 1.
2.4%, Izod impact strength is 58, 49k respectively
It was g · cm / cm. Example 2 a) Propylene was polymerized in the same manner as in Example 1a) to obtain a polymer having η1.38, a syndiotactic pentad ratio of 0.93 and a MW / MN of 2.1. A blow bottle was molded from this polymer by the same molding method as in Example 1c). The physical properties of this blow bottle are as follows. The areal weight was 37 g, the haze was 10.8%, and the Izod impact strengths were 58 and 3.5 kg · cm / cm, respectively.

B) Using the catalyst obtained in Example 1a), an autoclave was charged with propylene up to 0.5 kg / cm ² -G and ethylene up to 3 kg / cm ² -G, and 2
Polymerization was carried out at 0 ° C. to produce a copolymer of ethylene and propylene. The η of the copolymer was 0.88 and the ethylene content was 45 wt%.

C) 30 parts by weight of this copolymer and the above a)
70 parts by weight of the syndiotactic polypropylene obtained in 1. were mixed in the same manner as in the extruder used in Example 1c) to obtain a composition. Blow bottles were similarly molded using this composition.
The physical properties of this blow bottle are 42 g of basis weight and 12.1 of haze.
%, Izod impact strength is 58, 59 kg / c, respectively
It was m / cm. Example 3 70 parts by weight of the polymer obtained in Example 2a) and a random copolymer of ethylene and propylene manufactured by Mitsui Petrochemical Co., Ltd., Tufmer (trademark) SPO370 (η1.4).
30 parts by weight of 1, ethylene content 70.6 wt%) were similarly mixed to obtain a composition. This composition was molded in the same manner as in Example 1 to obtain a blow bottle. The blow bottle had physical properties of 49 g, a haze of 13.1%, and Izod impact strengths of 61 and 63 kg · cm / cm, respectively. Comparative Example 1 Commercially available isotactic polypropylene (MJS5.1 manufactured by Mitsui Toatsu Co., Ltd., melt index 1.5 g /
Blow molding was carried out in the same manner as in Example 1c) using a random copolymer of propylene and ethylene having a min of 4.9 wt% ethylene. The physical properties are as follows. Basis weight 69
g, haze 51.5%, and Izod impact strength were 48 and 2.8 kg · cm / cm, respectively. Examples 4 to 7 and Comparative Example 2 The syndiotactic polypropylene obtained in Example 2a) and the ethylene-propylene copolymer obtained in Example 2b) were mixed with Example 1c) in the proportions shown in Table 1. Kneading was performed in the same manner, and then blow molding was performed, and the physical properties of the obtained blow bottle were measured. The results are shown in Table 1. The composition of Comparative Example 2 could not be blow molded.

[0043]

[Table 1] Examples 8 to 11 and Comparative Example 3 An ethylene-propylene copolymer having the ethylene content shown in Table 2 was produced according to Example 2b). This copolymer was kneaded with the syndiotactic polypropylene obtained according to Example 2a) in a weight ratio of 50/50 according to Example 1c) and blow molded. Table 2 shows the physical properties of the obtained blow bottle.

[0044]

[Table 2] Example 12 The polymer obtained in Example 1b) was kneaded in the same manner as in Example 1c), and then, using a multilayer blow molding machine manufactured by Placo Co., Ltd., a parison molding temperature of 195 ° C. and a blow mold temperature of 2
Blow molding was carried out at 0 ° C. using the syndiotactic polypropylene obtained in Example 2a) as the outer layer and the above polymer as the inner layer. The physical properties of the obtained blow bottle were 41 g of basis weight, 12.4% haze, 58.49 kg · cm / cm of Izod impact strength, and 51 gf of surface hardness.
Met. Further, the thickness of the outer layer calculated by observing the cross section of the cut out section was 0.15 mm, and the thickness of the inner layer was 0.6.
It was mm.

When the surface strength of the blow bottle obtained in Example 1 was measured, the surface hardness was 23 gf. Example 13 A blow bottle was obtained in the same manner as in Example 12 except that syndiotactic polypropylene was used as the outer layer in Example 12 and the syndiotactic polypropylene was used as the inner layer and the outer layer. The physical properties of this blow bottle are as follows: unit weight is 37 g, haze is 10.8%, Izod impact strength is 58, 3.5 kg · cm / cm, and surface hardness is 5.
It was 1 gf, and the physical properties other than the surface hardness were almost the same as the bottle of Example 12, but the impact resistance at low temperature was poor. Example 14 30 parts by weight of the ethylene-propylene copolymer obtained in Example 2b) were kneaded with 70 parts by weight of the syndiotactic polypropylene obtained in Example 2a) in the same manner as in Example 1c) to prepare a resin composition. I got a thing. A blow bottle was molded using this resin composition as an inner layer in the same manner as in Example 12. The physical properties of this blow bottle are as follows:
Haze 12.1%, Izod impact strength is 58, 59k
The surface hardness was g · cm / cm and the surface hardness was 51 gf. The outer layer of this bottle had a thickness of 0.2 mm, and the inner layer had a thickness of 0.6 mm. Example 15 A multilayer blow bottle was molded in the same manner as in Example 12 except that the resin composition in Example 3 was used as the inner layer. The blow bottle had physical properties of 49 g, a haze of 13.1% and an Izod impact strength of 61, 63 kg · cm / cm.
The outer layer of this bottle has a thickness of 0.2 mm, and the inner layer has a thickness of 0.6.
It was 5 mm and the surface hardness was 53 gf. Comparative Example 4 The surface hardness of the isotactic polypropylene blow bottle obtained in Comparative Example 1 was measured to be 60 gf.
Met.

The resin composition used in the present invention is
Various additives usually used, for example, antioxidants, ultraviolet absorbers, antiblocking agents, slip agents, nucleating agents and the like can be contained.

As the molded product having at least one surface made of polypropylene having a substantially syndiotactic structure, various molded products other than the blow bottle shown in the examples, for example, a plate,
Extruded materials, sheets, films, pipes and the like can be mentioned.

[0048]

The molded article of the present invention has excellent appearance such as transparency and gloss and is excellent in impact resistance, and the multilayer molded article has good surface hardness.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location B29K 105: 32 (72) Inventor Shosuke Nakanishi 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Chemical Co., Ltd. formula In the company

Claims (2)

[Claims] 1. A transparent impact resistance obtained by blow molding a polypropylene having a substantially syndiotactic structure or a resin composition containing a polypropylene having a substantially syndiotactic structure and a copolymer of ethylene and propylene. Molded article. 2. A molded product obtained from a resin composition comprising a polypropylene having a substantially syndiotactic structure and a copolymer of ethylene and propylene, at least one surface of which has a substantially syndiotactic structure. A transparent impact resistant molded product that is a layer of polypropylene.