JPH07149968A - Polypropylene resin molding - Google Patents

Abstract

PURPOSE:To obtain the molding having very excellent physical properties and excellent moldability as well as transparency and flexibility inherent in syndiotactic polypropylene. CONSTITUTION:The molding is produced by melt-molding a mixture of a substantially syndiotactic polypropylene with an isotactic polypropylene, and has a crystalization temperature appearing as a single peak when measured at a temperature fall rate of 30 deg.C/min by differential scanning calorimetry(DSC).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polypropylene resin molded product. More specifically, it relates to a polypropylene resin molded product having good transparency and excellent flexibility.

[0002]

2. Description of the Related Art Syndiotactic polypropylene having a relatively high stereoregularity is synthesized by using a kind of metallocene catalyst called Kaminsky catalyst (JP-A-2-41303).
It is known that the molded product has good transparency, and is expected to be used as polypropylene having excellent flexibility. However, the syndiotactic polypropylene synthesized by this method has a slower crystallization rate than the conventional isotactic polypropylene and is hard to be solidified, so that there is a problem that a good molded product cannot be obtained at the time of molding. It has been studied to add various crystal nucleating agents in order to accelerate the crystallization rate or mix isotactic polypropylene having a high crystallization rate to improve the moldability (Japanese Patent Laid-Open No. 3-5423).
8).

[0003]

By adding a crystal nucleating agent to syndiotactic polypropylene or mixing isotactic polypropylene, molding processability is improved, and physical properties such as flexural modulus and impact strength are improved. Things have been obtained. However, although the moldability is improved by the method of adding a crystal nucleating agent, the rigidity is increased because the crystallinity of the molded product is also increased, and the excellent flexibility characteristic of syndiotactic polypropylene is impaired, There was a defect that there was no effect of improving transparency. Further, in the method of mixing isotactic polypropylene, because isotactic polypropylene and syndiotactic polypropylene are substantially incompatible, for example, when the melting point is measured by performing thermal analysis by differential scanning calorimetry, isotactic polypropylene and A melting peak due to syndiotactic polypropylene was observed, and once melting at 250 ° C, the temperature was lowered to 30 ° C at 10 ° C / min, and the crystallization temperature when the temperature was raised again at 10 ° C / min was two. Is observed. Such a composition has the drawbacks that the rigidity becomes high, the excellent flexibility characteristic of syndiotactic polypropylene is impaired, and the transparency is not improved.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have intensively searched for a molded article of highly transparent polypropylene having excellent flexibility by solving the above problems, and a composition having a specific structure has excellent flexibility. The present invention has been completed by finding that the composition is a highly transparent composition.

That is, the present invention is obtained by subjecting a mixture of polypropylene having a substantially syndiotactic structure and propylene having a substantially isotactic structure to hot melt molding, and using a differential scanning calorimetry (DSC) method. 30 ° C
The polypropylene resin molded product is characterized in that the crystallization temperature measured by lowering the temperature at 1 / min has a single peak.

Substantially synd used in the present invention
As polypropylene, which has an tactic structure,
Measurement of 1,2,4-trichlorobenzene solution of pyrene chain part
did ¹³C-NMR based on tetramethoxysilane
The peak intensity observed at about 20.2 ppm
Ratio of all peak intensities attributed to chill groups (hereinafter syndio
A tactic pentad fraction) is 0.5 or more.
All of propylene homopolymers
Without propylene and ethylene, butene-1, hexene-1, etc.
Random copolymers and block copolymers with other olefins
It may be the body. This syndiotactic polypropy
The molecular weight of ren is measured with a tetralin solution at 135 ° C.
The intrinsic viscosity [η] is about 0.1 to 20 dl / g,
The olefin content is 0 to 50% by weight.

As a method for producing these syndiotactic polypropylenes, a method of polymerizing propylene using a catalyst composed of a transition metal compound having an asymmetric ligand and an aluminoxane is known (J. Am. Chem. Soc. , 1988,1
10,6255-6256) is a method for producing syndiotactic polypropylene having a syndiotactic pentad fraction of more than 0.5 even if the catalyst is different, and any one synthesized can be used.

As a general method for producing syndiotactic polypropylene, a catalyst comprising a metallocene compound represented by the following formula (Formula 1) and an activator described below is used.
The method of polymerizing propylene is mentioned.

[0009]

[Chemical 1] (In the formula, A and B are monovalent or divalent unsaturated hydrocarbon residues different from each other, and R is a divalent linear saturated hydrocarbon residue which may have a side chain or its linear chain). A residue in which some or all of the carbon atoms are replaced by silicon, germanium, or tin atoms, M is a titanium atom, zirconium atom, or hafnium atom, and X is a halogen atom or a carbon atom number of 1 to 20. Represents a hydrocarbon residue).

Examples of the unsaturated hydrocarbon residue represented by A and B include monocyclic or polycyclic groups having a conjugated π electron having 5 to 50 carbon atoms, and specific examples thereof include cyclopetadienyl. Alternatively, a part or all of hydrogen thereof is replaced with a hydrocarbon residue having 1 to 10 carbon atoms (wherein the hydrocarbon residue may have a structure in which the terminal is again bound to the cyclopentadiene ring). ), Or a polycyclic aromatic hydrocarbon residue such as indenyl or fluorenyl, or one in which a part or all of the hydrogen thereof is replaced with a hydrocarbon residue having 1 to 10 carbon atoms.

As the divalent group represented by R, a methylene group represented by the following formula (Formula 2) or a part or all of the carbon atoms of the methylene group is a silicon atom, a germanium atom,
Alternatively, those having a silylene group substituted with a tin atom, a germylene group or a stannylene group are exemplified.

[0012]

## STR2 ## _{- (R '2 C) n} - (R' 2 Si) m- (R '2 Ge) p- (R' 2 Sn) q- ( wherein R 'is hydrogen or C 1 -C Or R's may be the same or different, and n, m, p and q are integers from 0 to 4 and
It represents an integer satisfying 1 ≦ n + m + p + q ≦ 4. )

Examples of X include fluorine, chlorine, bromine, iodine, and alkyl groups such as methyl, ethyl, propyl and butyl, aromatic compounds such as cyclopentadienyl group, phenyl group and benzyl group, but especially chlorine. A methyl group is preferred.

As the activator, a compound which reacts with a metallocene compound such as aluminoxane, triphenylmethyltetra (pentafluoro) borate or a Lewis acid compound to form a metal cation (see, for example, JP-A-1-
No. 5,020,36 and JP-A No. 1-501950) are known. Examples of aluminoxanes include compounds obtained by hydrolyzing trialkylaluminum with water. The use ratio of aluminoxane to the metallocene compound is 1 to 10000 mol times, usually 10 to 5000 mol times.

As the polymerization method, a conventional method such as a solvent polymerization method, a bulk polymerization method in which substantially no solvent is present, or a gas phase polymerization method can be used, and the polymerization conditions are not particularly limited, and the reaction temperature is usually room temperature. ~ 200 ℃, normal pressure ~ 50kg
/ Is carried out in cm ^2.

Polypropylene having a relatively high stereoregularity can be used as the substantially isotactic polypropylene used as a mixture, and the isotactic pentad fraction measured by ¹³ C-NMR is 0.90 or more. . However, this number is a value in the homopolymerization part of propylene when a block copolymer of propylene is used. As the polypropylene, not only a homopolymer of propylene but also α-of propylene and ethylene, butene, hexene, etc.
Examples thereof include random copolymers with olefins or block copolymers. When the isotactic pentad fraction is less than 0.90, the formability is not improved so much. The molecular weight of this isotactic polypropylene is not particularly limited, but the one having an intrinsic viscosity [η] measured with a tetralin solution at 135 ° C. of about 0.5 to 2.5 dl / g is usually used.

Methods for producing isotactic polypropylene satisfying these requirements are already known and various brands are available on the market. For example, a catalyst comprising a solid catalyst in which an electron donating compound and a titanium halide are supported on magnesium halide, an organic aluminum compound, and an electron donating compound is particularly preferably used. Many examples of such a catalyst system are already known (for example, various examples are described in the following documents. Ziegler-
Natta Catalysts and Polymerization by JohnBoor Jr
(Academic Press), Journal of Macromorecular Science
Reviews in Macromolecular Chemistry and Physics, C2
4 (3) 355-385 (1984) and C25 (1) 578-597 (1985)). The polymerization method is not particularly limited, and it can be produced by a bulk polymerization method or a gas phase polymerization method in addition to the solvent method using an inert solvent.

As the electron-donating compound, oxygen-containing compounds such as ethers, esters, orthoesters and alkoxysilicon compounds can be preferably exemplified, and alcohols, aldehydes, water and the like can also be used.

As the organoaluminum compound, trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide and alkylaluminum dihalide can be used, and examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group and hexyl group. Examples of the halide include chlorine, bromine and iodine.

The molded product of the present invention can be obtained, for example, by adding and mixing polypropylene having a substantially isotactic structure to polypropylene having a substantially syndiotactic structure, and further heating and melting the mixture.

Alternatively, a catalyst capable of synthesizing substantially syndiotactic structure polypropylene and substantially isotactic structure polypropylene is added to the polymerization system to directly synthesize syndiotactic structure polypropylene and isotactic structure polypropylene. You may synthesize a mixture.

Usually, when syndiotactic polypropylene and isotactic polypropylene are mixed, they are not completely compatibilized with each other.
After melting at 250 ℃, cool down to 30 ℃ at 30 ℃ / min, and
Crystallization temperature and melting point are 2 ~ when heated at 10 ℃ / min
Three are observed.

On the other hand, the molded article of the present invention is characterized in that it has a single crystallization temperature measured by differential scanning calorimetry once melted at 250 ° C. and then cooled to 30 ° C. at 30 ° C./min. Is.

In the molded product of the present invention, the ratio of the syndiotactic structure polypropylene and the isotactic structure polypropylene and the molding conditions have a great influence on the molding conditions. By increasing the amount of polypropylene having an tactic structure, a polypropylene resin molded product having a single peak crystallization temperature and excellent physical properties can be obtained.
If the amount is too large (the ratio of the isotactic structure polypropylene is too small), the effect of adding and mixing the isotactic structure polypropylene is not sufficient. Therefore, the addition amount of the isotactic polypropylene to the preferred syndiotactic polypropylene is 45 to 5% by weight, and more preferably 30 to 10% by weight. In addition, the temperature at the time of molding from the melt and the cooling conditions after molding also have a great influence, so the temperature of the mold and the conditions for taking out the molded product from the mold are also important. Need to be set.

[0025]

EXAMPLES The present invention will be further described with reference to the following examples.

Example 1 [Production of syndiotactic polypropylene] Internal volume 2
Toluene in a 00 liter stainless steel autoclave 1
00 liters were put, and 64 g of methylaluminoxane (manufactured by Tosoh Akzo Co., degree of polymerization 16.2) was charged. further
Propylene gas was introduced at 20 ° C to obtain 3 kg / cm ² -G isopropyl (cyclopentadienyl) (fluorenyl)
A solution prepared by dissolving 0.2 g of zirconium dichloride in 1 liter of toluene was added, and the mixture was polymerized at 20 ° C. for 2 hours.

After the completion of the polymerization, unreacted propylene was purged and the polymer was taken out by filtration, vacuum dried at 80 ° C. for 8 hours and weighed to obtain 15.6 kg of syndiotactic polypropylene. Further, the syndiotactic pentad fraction measured from ¹³ C-NMR measured with a 1,2,4-trichlorobenzene solution was 0.91, and the intrinsic viscosity number measured with a 135 ° C. tetralin solution (hereinafter referred to as [η]). ) Is 1.05, 1,2,4-
The ratio of the weight average molecular weight to the number average molecular weight measured with trichlorobenzene (hereinafter referred to as MW / MN) was 2.2.

[Production of Resin Molded Product] Based on 100 parts by weight of the above syndiotactic polypropylene, commercially available polypropylene (JHH-G, ¹³ C-NM manufactured by Mitsui Toatsu Chemicals, Inc.) is used.
The isotactic pentad fraction measured by R is 0.935
) Add 25 parts by weight, and then add 0.1 parts by weight of antioxidant and mix with a Henschel mixer, then add 230 parts with an extruder.
The mixture was heated and mixed at ℃ to obtain pellets. Using these pellets, a downward T-die extruder (FSK-5 manufactured by Komatsu Ltd.)
By extrusion molding in 5), a sheet-like molded product having a thickness of 500 μm was obtained. At this time, the cylinder temperature and die temperature of the extruder were 210 ° C, the screw rotation speed was 110 rpm,
The roll temperature was 30 ° C.

The following physical properties of this molded product were measured. Tensile modulus is ASTM-D638, haze is AST
Tensile elastic modulus measured in accordance with MD1003 5800kg / c
m ² and haze (total 3.0%, internal 2.8%). In addition, once by the differential scanning calorimetry (hereinafter referred to as DSC) 2
After melting at 50 ℃, cool down to 30 ℃ at 30 ℃ / min, and
The crystallization temperature and melting point when the temperature was raised at ℃ / min showed a single peak at 54.0 ℃ at the crystallization temperature, and the melting points were 112.1 ℃ and 129.5 ℃.
Three peaks were observed at ℃ and 161.5 ℃. This DSC
The chart (crystallization temperature) is shown in (FIG. 1).

Comparative Example 1 The same procedure as in Example 1 was carried out except that only syndiotactic polypropylene was used without using isotactic polypropylene. The polymer was apt to stick to the roll, and the sheet had to be taken out while peeling it off by hand. There wasn't. When the physical properties of this molded product were measured, the tensile elastic modulus was 5900 kg / cm ² , and the haze (total 7.4%, internal 6.5%). Also, after melting at 250 ° C once by DSC,
The crystallization temperature and melting point when the temperature was lowered to 30 ° C at 30 ° C / min, and then again raised to 10 ° C / min, the single peak at 63.4 ° C was found at the crystallization temperature, and the melting points were 114.3 ° C and 127.9 ° C. A book peak was observed.

Example 2 Commercially available polypropylene (JHH manufactured by Mitsui Toatsu Chemicals, Inc.)
-G, the isotactic pentad fraction measured by ¹³ C-NMR was 0.935), and a polypropylene random copolymer (MFL-4.9 manufactured by Mitsui Toatsu Chemicals, Inc., the isotactic pentad fraction was 0.905) 25 parts by weight was added and a molded product was prepared in the same manner as in Example 1 except that the tensile modulus of elasticity was changed.
It was 4500 kg / cm ² and the haze (total 1.0%, internal 0.9%).
Also, once melted at 250 ℃ by DSC, 30 ℃ / min
The crystallization temperature and melting point when the temperature was lowered to 30 ° C at 10 ° C / min and the melting point had a single peak at 48.5 ° C, but the melting points were three peaks at 111.3 ° C, 128.9 ° C and 147.3 ° C. Was observed.

Example 3 Polypropylene random copolymer (Mitsui Toatsu Chemicals, Inc.)
MFL-4.9, isotactic pentad fraction is 0.
905) 43 parts by weight was added and a molded product was prepared in the same manner as in Example 2 except that the tensile elastic modulus was 5100 kg / cm ² , and the haze (total 1.9).
%, Internal 1.3%). Once again by DSC 2
After melting at 50 ℃, cool down to 30 ℃ at 30 ℃ / min, and
As for the crystallization temperature and melting point when the temperature was raised at ℃ / min, the crystallization temperature showed a single peak at 54.5 ° C, and the melting point was 112.1 ° C.
Three peaks were observed at 9.2 ° C and 147.9 ° C.

Comparative Example 2 Polypropylene (JHH-G manufactured by Mitsui Toatsu Chemicals, Inc.)
^A molded product was made in the same manner as in Example 1 except that the added amount of the isotactic pentad fraction measured by ¹³ C-NMR was 0.935), and the tensile modulus of elasticity was 7100 kg / cm ^2.
And, it was higher than the syndiotactic polypropylene used, and the haze (total 12.0%, internal 5.4%) was not improved so much. In addition, the crystallization temperature and melting point when melting once at 250 ° C by DSC, then decreasing to 30 ° C at 30 ° C / min, and raising again at 10 ° C / min are 76.5 ° C at the crystallization temperature.
And two peaks at 104.0 ° C and melting points of 119.9 ° C and 129.7 ° C.
Four peaks were observed at ℃, 159.3 ℃ and 163.1 ℃.
A chart (crystallization temperature) of this DSC is shown in (FIG. 2).

[0034]

INDUSTRIAL APPLICABILITY The molded product of the present invention can obtain a resin molded product having excellent physical properties and molding processability without impairing the original transparency and flexibility of syndiotactic polypropylene. , Industrially extremely valuable.

[Brief description of drawings]

FIG. 1 is a chart diagram of a crystallization temperature in a differential scanning calorimetry (DSC) of Example 1.

FIG. 2 is a chart diagram of a crystallization temperature in a differential scanning calorimetry (DSC) of Comparative Example 2.

Claims (1)

[Claims] 1. A mixture of polypropylene having a substantially syndiotactic structure and propylene having a substantially isotactic structure is heat-melt-molded, and at 30 ° C./min by differential scanning calorimetry (DSC). A polypropylene resin molded product having a single peak in crystallization temperature measured by lowering the temperature.