JP2869606B2 - High melt tension polypropylene, its production method and molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to high melt tension polypropylene. More specifically, high melt tension polypropylene, which has a high melt tension and a high crystallization temperature, is excellent in rigidity and moldability, and which can be used again as a molded product, then remelted and recycled, and a method for producing the same. Related to molded products.

[0002]

2. Description of the Related Art Crystalline polypropylene has mechanical properties,
It is widely used in various molding fields because it has excellent chemical resistance and is very useful in balance with economic efficiency. However, since the melt tension is low and the crystallization temperature is low, moldability such as hollow molding, foam molding, and extrusion molding is poor.

As a method for increasing the melt tension and crystallization temperature of crystalline polypropylene, a method of reacting an organic peroxide and a crosslinking assistant with crystalline polypropylene in a molten state (JP-A-59-93711, JP-A-61-
No. 152754), however, there is a problem that the modified polypropylene obtained by using the crosslinking aid has an odor remaining. In addition, the melt tension is not sufficiently improved, and if the amount of the organic peroxide and the crosslinking aid is increased to increase the melt tension, a gel will be generated. It was impossible to do that.

On the other hand, Japanese Patent Application Laid-Open No. 2-298536 discloses that a polypropylene having a free-end long-chain branch and containing no gel is prepared by reacting a semi-crystalline polypropylene with a peroxide having a low decomposition temperature in the absence of oxygen. Although a method for obtaining the polypropylene has been disclosed, improvement in the melt tension of the obtained polypropylene has been insufficient.

[0005]

As described above, the polypropylene obtained by the method of the known invention has insufficient melting tension and crystallization temperature, has an odor, and contains a gel. After use as a molded product
There was a problem that it was impossible to re-melt and use it for recycling.

[0006] The present inventors have solved the problems of the above-mentioned known inventions and have intensively studied a polypropylene suitable for hollow molding, foam molding, extrusion molding and the like, and a method for producing the same. As a result, a specific organic peroxide is reacted with polypropylene under specific conditions, and further melt-kneaded to obtain a high melt tension polypropylene having a specific structure and properties, and the high melt tension polypropylene is used as a molded article. Then, they found that the problem of the prior invention was solved, and reached the present invention.

As apparent from the above description, an object of the present invention is to provide a material having a high melt tension and a high crystallization temperature, excellent rigidity and moldability, and, after being used as a molded article, can be re-melted and recycled. An object of the present invention is to provide a high melt tension polypropylene that can be used, a method for producing the same, and a molded product using the high melt tension polypropylene.

[0008]

The present invention has the following constitutions (1) to (10). (1) Linear crystalline polypropylene having a branching index of substantially 1 and (A) a melt tension (MS) at 230 ° C. and an intrinsic viscosity [η] measured at 135 ° C. in tetralin. And 1 og (MS)> 4.24 × 1 og
[Η] −0.843, and (B) the crystallization temperature (T) measured by a differential scanning calorimeter (DSC).
c) and the melting point (Tm) are (Tc)> 0.784 × (T
m) A high melt tension polypropylene that satisfies the relationship expressed by -4.00 and (C) the boiling xylene extraction residual ratio is 1% by weight or less.

(2) The high melt tension polypropylene according to (1), wherein the crystalline polypropylene is a propylene homopolymer.

(3) The high melt tension polypropylene according to the above (1), wherein the crystalline polypropylene is a propylene-olefin random copolymer containing 10% by weight or less of olefin polymerized units other than propylene.

(4) Under an inert gas atmosphere, 100 g of linear crystalline polypropylene is
Ethylhexyl peroxydicarbonate (1-10 mmol) is added and mixed.
A linear crystalline polypropylene having a branching index of substantially 1, characterized by melt kneading after reacting for from 1 minute to 3 hours, and (A) a melt tension at 230 ° C. (MS ) And the intrinsic viscosity [η] measured at 135 ° C. in tetralin are log (MS)> 4.24 × log.
[Η] −0.843, and (B) the crystallization temperature (T) measured by a differential scanning calorimeter (DSC).
c) and the melting point (Tm) are (Tc)> 0.784 × (T
m) A method for producing a high melt tension polypropylene that satisfies the relationship indicated by -4.00 and (C) has a residual boiling xylene extraction of 1% by weight or less.

(5) The method according to the above (4), wherein the crystalline polypropylene is a propylene homopolymer.

(6) The method according to (4), wherein the crystalline polypropylene is a propylene-olefin random copolymer containing not more than 10% by weight of olefin polymerized units other than propylene.

(7) After the reaction between the crystalline polypropylene and di-2-ethylhexyl peroxydicarbonate, the reaction is continued at 100 to 150 ° C. in an inert gas atmosphere.
The method according to the above (4), which comprises performing a post-heating treatment for 10 minutes to 3 hours.

(8) A linear crystalline polypropylene having a branching index of substantially 1, and (A) a melt tension (MS) at 230 ° C. and an intrinsic viscosity measured at 135 ° C. in tetralin. [Η] and log
(MS)> 4.24 × log [η] −0.843, and (B) the crystallization temperature (Tc) and the melting point (Tm) measured by a differential scanning calorimeter (DSC) are as follows: (Tc)> 0.7
84 × (Tm) -A molded article using high melt tension polypropylene which satisfies the relationship of 4.00 , and (C) the residual amount of boiling xylene extracted is 1% by weight or less.

(9) The method according to the above (8), wherein the crystalline polypropylene is a propylene homopolymer.

(10) The molded article according to (8), wherein the crystalline polypropylene is a propylene-olefin random copolymer containing 10% by weight or less of olefin polymerized units other than propylene.

The configuration of the present invention will be described in detail below. The polypropylene of the present invention contains not only propylene homopolymer but also 10 units of olefin polymer units other than propylene.
It also includes a propylene-olefin random copolymer containing less than about 10% by weight, and the description of polypropylene is used in this sense hereinafter.

The polypropylene of the present invention is a linear crystalline polypropylene having a branching index of substantially 1.
The branching index indicates the degree of long-chain branching, and is generally defined by the following formula. Branching degree index (g) = [η] _Br / [η] _Lin where [η] _Br is the intrinsic viscosity of the branched polypropylene, and in this specification, is the measured value [η] _Obs of the actual sample.
[Η] _Lin is the intrinsic viscosity of a linear crystalline polypropylene obtained by a conventionally known ordinary method having the same weight average molecular weight. The above ratio of the intrinsic viscosity indicates the degree of branching of the non-linear polymer, and is less than 1 when a long-chain branch is present.

The intrinsic viscosity was measured at 135 ° C. on a sample dissolved in tetralin. Also,
The weight average molecular weight is determined by M.P. L. American Laboratory, May, by McConnell
63-75 (1978), namely:
Measured by low angle laser light scattering photometry.

According to the above-mentioned method, the present inventor measured a linear polypropylene obtained by a known polymerization method, and found that the intrinsic viscosity [η] _Lin and the weight average molecular weight (Mw) were as follows. Formula log [η] _Lin = 0.890 × log (Mw) -4.
67, the calculation of the branching index was performed in order to calculate the weight average molecular weight (Mw) _Obs
Was substituted for (Mw) in the above equation to determine the intrinsic viscosity [η] _Lin of the linear polypropylene having the same weight average molecular weight, and the branching index was calculated from this value.

The polypropylene of the present invention has a branching index according to the above definition and measuring method of substantially 1, and does not have a long-chain branched structure. In addition, being substantially 1 means that even if there is a long-chain branch, it is below the detection limit by the above method, and the range of statistical error when the same sample is repeatedly measured by the above method. It includes the meaning of 1 including. Therefore, the actual value is 0.
It shows a value of about 95 to 1.05. Since the degree of branching index is substantially 1, except for the characteristic properties of the polypropylene of the present invention described below, it has the same properties as the conventionally known linear polypropylene, so that the conventionally known linear It has a feature that the molding method and apparatus used for polypropylene can be used as they are.

Further, the polypropylene of the present invention has the following three essential requirements. That is, (A) the melt tension (MS) at 230 ° C. and the intrinsic viscosity [η] measured at 135 ° C. in tetralin are such that log (MS)> 4.24 ×
(B) The crystallization temperature (Tc) and the melting point (Tm) measured by a differential scanning calorimeter (DSC) are (Tc)> 0.7.
84 × (Tm) −4.00
(C) It is characterized in that the residual amount of boiling xylene extracted satisfies 1% by weight or less.

The melt tension of polypropylene required to achieve the object of the present invention is, as described above, the melt tension (MS) at 230 ° C. and the intrinsic viscosity [η] measured in tetralin at 135 ° C. log (MS)> 4.24
× log [η] −0.843, more preferably log (MS)> 4.24 × log [η] −0.043.
It is necessary that the relationship indicated by 570 be established.

Here, the melt tension at 230 ° C. (M
S) uses a melt tension tester type 2 manufactured by Toyo Seiki Seisaku-Sho, Ltd. to convert polypropylene into 230
℃, melted polypropylene 2.095mm in diameter
From the nozzle at a speed of 20 mm / min into the air at 23 ° C. to form a strand.
The tension of the filamentous polypropylene at the time of drawing at a rate of / minute was measured and defined as a melt tension (MS).

The crystallization temperature of polypropylene required to achieve the object of the present invention is, as described above, a crystallization temperature (Tc) and a melting point (Tm) measured by a differential scanning calorimeter (DSC). Is (Tc)> 0.784 ×
The relationship represented by (Tm) −4.00, more preferably the relationship represented by (Tc)> 0.784 × (Tm) −3.00, must be satisfied. If this relationship is not satisfied, the good moldability characteristics of the polypropylene of the present invention are lost due to slow crystallization.

The crystallization temperature (Tc) and the melting point (Tm) of the polypropylene were raised from room temperature to 230 ° C. under a heating condition of 30 ° C./min using a DSC7 differential scanning calorimeter manufactured by Perkin Elmer. After holding at the same temperature for 10 minutes,
The temperature was lowered to -20 ° C at -20 ° C / min, and
After holding for 20 minutes, the temperature showing the maximum peak at the time of melting under a heating condition of 20 ° C./min was defined as a melting point (Tm). Further, after the melting point peak appeared, the temperature was continuously raised to 230 ° C. under the same conditions, and the temperature was maintained at the same temperature for 10 minutes.
The temperature was lowered to 50 ° C., and from 150 ° C., the temperature at which the maximum peak was reached during crystallization while the temperature was lowered at −5 ° C./min was defined as the crystallization temperature (Tc).

Further, as described above, the polypropylene of the present invention must have a boiling xylene extraction residual ratio of 1% by weight or less, more preferably 0.6% by weight or less. If the extraction residual ratio is large, the moldability deteriorates, and it becomes extremely difficult to re-melt and recycle after use as a molded article.

The boiling xylene extraction residue ratio was determined by placing 1 g of polypropylene in a 200-mesh wire net using a Soxhlet extractor, extracting with 200 ml of p-xylene with boiling xylene for 6 hours, and drying and weighing the extraction residue. It was calculated as (weight of extraction residue / weight before extraction) × 100%.

The polypropylene of the present invention has, besides the above-mentioned characteristics, a crystallinity of 10 measured by an X-ray diffraction method.
%, The intrinsic viscosity [η] measured in tetralin at 135 ° C. is 0.5 to 5 dl / g, particularly preferably 0.7 to 4 dl / g, and the weight average molecular weight (Mw) is 80,000 to
It is a measure of 1.1 million, particularly preferably 120,000 to 850,000, furthermore the molecular weight distribution. It has the additional characteristic that the value of weight average molecular weight / number average molecular weight is 3 to 7, particularly preferably 3.5 to 7.

Next, a method for producing the above-mentioned polypropylene of the present invention will be described. The crystalline polypropylene used in the production of the polypropylene of the present invention is a crystalline polypropylene having a degree of crystallinity of 10% or more as measured by X-ray diffraction, preferably 135 in tetralin.
The one having an intrinsic viscosity [η] of 0.5 to 5 dl / g, particularly preferably 0.7 to 4 dl / g, measured at ° C. is desirable from the viewpoint of moldability. Further, not only propylene homopolymer but also olefins other than propylene, for example, linear monoolefins such as ethylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, and the like, 4-methylpentene- Branched chain monoolefins such as 1,2-methylpentene-1, and random copolymers of styrene and propylene with propylene can also be used. When a copolymer is used, the olefin other than propylene is not limited to one type, and two or more olefins may be included. Specifically, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-hexene-1 copolymer, propylene-
Octene-1 copolymer, propylene-4-methylpentene-1 copolymer, propylene-ethylene-butene-1 copolymer, propylene-ethylene-4-methylpentene-
1 copolymer and the like. At this time, it is necessary that the olefin polymerization unit other than propylene is 10% by weight or less. If it exceeds 10% by weight, a gel is formed in the obtained polypropylene, which is outside the scope of the present invention.

Such a crystalline polypropylene can be used as a titanium catalyst component (solid composition containing titanium trichloride as a main component,
Or a solid composition comprising titanium tetrachloride supported on a carrier such as a magnesium chloride compound) and an organoaluminum compound, and in some cases, molecules such as ethers, esters, and organosilicon compounds having a Si-OC bond. In a so-called Ziegler-Natta catalyst in which an electron donor component having any of oxygen, nitrogen, phosphorus and sulfur atoms is further combined as a third component of the catalyst, the polymerization of propylene is conducted in an inert solvent. It can be obtained by a known method such as slurry polymerization, bulk polymerization using propylene itself as a solvent, or gas phase polymerization performed in a gas phase mainly containing propylene gas.

The crystalline polypropylene used in the present invention may be in the form of powder, pellets, film, sheet, or the like. The powder in a state immediately after completion of the polymerization step obtained before and before pelletization is a preferred embodiment. The average particle size of the powder is about 50 μm to 1 mm.
It is preferable that the particle size is small in terms of reaction efficiency, but it is preferable that the particle size is large from the viewpoint of powder fluidity. Therefore, it is preferable to use one having a particle size suitable for the purpose.

In the present invention, di-2-ethylhexyl peroxydicarbonate reacted with crystalline polypropylene has a decomposition temperature of 92 ° C. when the half-life is 1 minute and a decomposition temperature when the half-life is 1 hour. It is an organic peroxide exhibiting 60 ° C. The use of similar percarbonates having similar decomposition temperatures, as evident in the examples below, does not achieve the objectives of the present invention.

When adding and mixing with polypropylene, in order to handle the reaction uniformly and to make the reaction uniform, the one diluted in an inert solvent represented by a hydrocarbon solvent such as toluene, xylene, isoparaffin, octane, decane, etc. is used. Convenient to use. The concentration of di-2-ethylhexyl peroxydicarbonate in the solvent is about 10 to 90% by weight.

The reaction between the crystalline polypropylene and di-2-ethylhexyl peroxydicarbonate in the method of the present invention is carried out by first reacting the crystalline polypropylene with di-2 in an inert gas atmosphere such as nitrogen or argon in a reaction vessel.
-Add and mix ethylhexyl peroxydicarbonate. The temperature at this time is desirably 40 ° C. or less and 0 ° C. or more.
In addition, it is desirable to stir so as to sufficiently mix.
The addition amount is preferably 1 to 10 mmol, particularly preferably 2 to 10 mmol, per 100 g of the crystalline polypropylene. If the amount used is small, the effect of the modification is insufficient, and if it is too large, not only the effect cannot be expected to be improved, but also an odor remains or the polypropylene becomes unstable with a long term deterioration.

The mixed crystalline polypropylene and di-
2-Ethylhexyl peroxydicarbonate is subsequently reacted in an inert gas atmosphere in a reaction vessel, optionally with stirring, at 70-150 ° C., preferably 75-150 ° C.
5 minutes to 5 hours at a temperature of 140 ° C., preferably 10 minutes
Incubate for minutes to 3 hours.

After the reaction, the polypropylene is taken out of the reaction vessel and further melt-kneaded to obtain the polypropylene of the present invention. For the melt kneading, a known melt kneading method is used. For example, using a single-screw extruder, a twin-screw extruder, an extruder combining these and a gear pump, a Brabender, a Banbury mixer, etc.
Melt kneading is performed at a temperature not lower than the melting point of polypropylene for about 10 seconds to 1 hour, preferably for about 20 seconds to 10 minutes. By melt kneading, the crystallization temperature rises significantly, and the characteristics of the polypropylene of the present invention appear. The crystallization temperature in the powder before the melt-kneading is the same as that before the reaction or only slightly increased.

After the melt-kneading, it is usually cut into granules to form pellets, which are used for various molded articles. However, the molded articles can be processed immediately after the melt-kneading. In addition,
After washing with an inert solvent if necessary in a powder state before melt-kneading, it is also possible to dry and then melt-knead.

When melt-kneading, an antioxidant, an ultraviolet absorber, an antistatic agent, a nucleating agent, a lubricant, a flame retardant, an anti-blocking agent, a coloring agent,
Various additives such as inorganic or organic fillers can be blended.

The polypropylene of the present invention can be obtained by the above-mentioned method. However, after the completion of the reaction and before the melt-kneading, the reaction product is continuously treated under an inert gas atmosphere and, if necessary, under a stirring condition under an inert gas atmosphere. Post-heating at 150 ° C. is a desirable embodiment of the present invention. Processing time is 1
0 minutes to 2 hours, preferably 15 minutes to 1 hour is appropriate. The post-heating treatment increases the reaction efficiency,
In addition to further reducing the odor of the obtained polypropylene, a stabilized polypropylene with little change over time can be obtained.

The desired polypropylene of the present invention is obtained by the above-mentioned method, and the polypropylene must have the above-mentioned characteristics. Unless these characteristics are satisfied, the object of the present invention cannot be achieved.

The high melt tension polypropylene of the present invention thus obtained has a high melt tension and a high crystallization temperature, is excellent in rigidity and moldability, and can be used again as a molded article and then re-melted for recycling. Therefore, particularly suitable for hollow molding, foam molding, extrusion molding, but not limited to the molding field, by injection molding, T-die molding, thermoforming, etc., various containers such as hollow containers, films, sheets, It can be used for various molded products such as pipes and fibers.

[0044]

The reaction mechanism for obtaining the polypropylene of the present invention is not known at present, but the radical generated from di-2-ethylhexyl peroxydicarbonate causes some interaction with the polypropylene. It is presumed that the melt-kneading exhibits the melting behavior and crystallization behavior characteristic of the polypropylene of the present invention, which are not found in known polypropylenes.

[0045]

Next, the present invention will be described specifically with reference to examples. Definitions of terms used in Examples and Comparative Examples and measurement methods are as follows. (1) Intrinsic viscosity: [η], measured by the method described above.
(Unit: dl / g) (2) Weight average molecular weight: (Mw), measured by the method described above. (3) Branching degree index: (g), measured by the method described above. (4) Melt tension: (MS) was measured by the method described above. (Unit: gf) (5) Melting point: (Tm) was measured by the method described above.
(Unit: ° C.) (6) Crystallization temperature: (Tc), measured by the method described above. (Unit: ° C) (7) Rigidity: A JIS-type test piece is prepared from a polypropylene pellet at a molten resin temperature of 230 ° C and a mold temperature of 50 ° C using an injection molding machine, and the humidity of the test piece is set to 50%.
%, At room temperature of 23 ° C. for 72 hours.
The flexural modulus was measured according to 7230. (Unit: k
gf / cm ² )

Example 1 After replacing the reactor equipped with a stirrer with a stirrer with a nitrogen gas, Example 1 in JP-B-59-28573 was used.
An intrinsic viscosity obtained by slurry polymerizing propylene in n-hexane using a catalyst obtained by combining the titanium trichloride composition obtained by the method described above, diethylaluminum chloride, and diethylene glycol dimethyl ether as a third component [ η] is 1.67 dl / g and the average particle size is 150 μm.
g. Then, the operation of evacuating the reactor and supplying nitrogen gas to atmospheric pressure was repeated 10 times, and then di-2-ethylhexyl having a concentration of 70% by weight in a toluene solution at 25 ° C. under a nitrogen gas atmosphere with stirring. 0.35 mol of peroxydicarbonate was added and mixed. Subsequently, the temperature in the reactor was increased to 120 ° C., and the reaction was performed at the same temperature for 30 minutes. After the elapse of the reaction time, the temperature in the reactor was further increased to 135 ° C., and post-treatment was performed at the same temperature for 30 minutes. After the post-treatment, the reactor was cooled to room temperature, and then opened to obtain polypropylene. When the melting point (Tm) and crystallization temperature (Tc) of the polypropylene were measured, they were 161.4 ° C and 117.2 ° C, respectively. Subsequently, 0.1 part by weight of tetrakis [methylene-3- (3′-5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane and 100 parts by weight of the obtained polypropylene were used. Calcium phosphate 0.1
Parts by weight were mixed, and the mixture was granulated at 230 ° C. using an extrusion granulator having a screw diameter of 40 mm to obtain pellets. Various physical properties of the pellets were evaluated and measured. As a result, the crystallinity by X-ray diffraction was 64%, and the weight average molecular weight (Mw) / number average molecular weight (Mn) was 5.6.
Other results are shown in Table 1.

Examples 2 and 3 Polypropylene pellets were prepared in the same manner as in Example 1 except that the intrinsic viscosity of the polypropylene used in the reaction, and the reaction conditions and post-treatment conditions were changed as shown in the table. I got

Comparative Examples 1 to 3 In Examples 1 to 3, granulation was carried out in the same manner as in Example 1 without reacting di-2-ethylhexyl peroxydiccarbonate with the propylene homopolymer used as a raw material. To obtain pellets.

Examples 1 to 3 and Comparative Examples 1 to 3
Table 1 shows the conditions and results.

[0050]

[Table 1]

Comparative Example 4 In Example 1, the decomposition temperature when the half-life was 1 minute was 85 ° C. and the decomposition temperature when the half-life was 1 hour in place of di-2-ethylhexylperoxydicarbonate. Is 57
The reaction was performed in the same manner as in Example 1 except that di-3-methoxybutyl peroxydicarbonate was used.
Post-processing was performed.

Comparative Example 5 In Example 1, instead of di-2-ethylhexyl peroxydicarbonate, the decomposition temperature when the half-life was 1 minute was 93 ° C., and the decomposition temperature when the half-life was 1 hour. Is 61
The reaction and post-treatment were carried out in the same manner as in Example 1 except that diisopropyl peroxydicarbonate at a temperature of ° C was used.

Comparative Example 6 In Example 1, the decomposition temperature when the half-life was 1 minute was 112 ° C. and the decomposition temperature when the half-life was 1 hour in place of di-2-ethylhexylperoxydicarbonate. Is 7
The reaction and post-treatment were carried out in the same manner as in Example 1 except that t-butyl peroxypivalate at 3 ° C. was used.

Table 2 shows the conditions and results of Comparative Examples 4 to 6 described above.

[0055]

[Table 2]

Example 4 In Example 1, the polypropylene used in the reaction was the same as Example 1 in JP-A-62-104812.
Using a catalyst in which magnesium chloride-supported titanium catalyst component obtained by the method described and triethylaluminum, and diisopropyldimethoxysilane as a third component are combined, propylene and ethylene are obtained by gas phase polymerization, and ethylene units are contained. 10 kg of propylene-ethylene random copolymer powder having an amount of 0.2% by weight, an intrinsic viscosity [η] of 1.70 dl / g, and an average particle size of 800 μm.
Except for using, a polypropylene pellet was obtained in the same manner as in Example 1.

Comparative Example 7 In Example 4, the propylene-ethylene random copolymer used as a raw material was granulated in the same manner as in Example 4 without reacting di-2-ethylhexylperoxydicarbonate with pellets. I got

Example 5 In Example 1, instead of the propylene homopolymer used as a raw material, the ethylene unit content was 3.2% by weight, the butene-1 unit content was 2.5% by weight, and the intrinsic viscosity [ η] is 1.60 dl / g and the average particle size is 190 μm. Propylene-ethylene-butene-1 random copolymer powder 10
kg and the reaction conditions and post-treatment conditions are shown in Table 3.
The polypropylene pellets were obtained in the same manner as in Example 1 except that the pellets were changed as shown in (1).

Comparative Example 8 The procedure of Example 5 was repeated, except that the propylene-ethylene-butene-1 random copolymer used as the starting material was not reacted with di-2-ethylhexylperoxydicarbonate. Granulated to obtain pellets.

Table 3 shows the conditions and results of Examples 4 and 5 and Comparative Examples 7 and 8.

[0061]

[Table 3]

Example 6 Polypropylene 10 of the present invention obtained in the same manner as in Example 1
0 parts by weight of tetrakis [methylene-3- (3′-5 ′).
- 0.1 part by weight of di -t- butyl-4'-hydroxyphenyl) propionate] methane, 0.1 part by weight of calcium stearate, and mixing the talc 0.1 parts by weight as the foaming nucleating agent, screw diameter and the mixture It was fed to a single screw extruder set at 65 mm and an extruder temperature of 230 ° C. Then, from the middle of the extruder, 1, 1, 2,
22 parts by weight of 2-tetrafluorodichloroethane were injected. Extrusion foam molding was performed at a mold temperature of 155 ° C. using a nozzle-shaped mold having a diameter of 5 mm attached to the extruder.
The surface of the obtained foam was smooth, and there were no abnormal air bubbles and uniform air bubbles.

Comparative Example 9 In Example 6, instead of the polypropylene of the present invention,
Extrusion foaming was carried out in the same manner except that the propylene homopolymer used as a raw material was used as it was, and the resulting foam was out of gas due to outgassing and had a large void, and had large voids. It was unsatisfactory and could not be offered.

Example 7 The propylene-ethylene random copolymer pellets obtained in the same manner as in Example 4 were subjected to extrusion sheeting at 260 ° C. using an extruder having a T-die and a screw diameter of 65 mm. And a sheet having a thickness of 0.5 mm. Next, in order to modelly evaluate the heat vacuum formability of the sheet, the sheet was fixed to a 40 cm square frame at 210 ° C.
And the behavior was observed. By heating, the center of the sheet begins to hang down, and when it hangs down 40 mm,
The droop stopped, and the droop rose. After a further elapse of time, the sheet began to sag again, and thereafter only hung. When the sheet, which had once hung, showed the behavior of returning, it was found that the sheet had excellent heating vacuum formability.

Comparative Example 10 In Example 7, instead of the polypropylene of the present invention,
A sheet was obtained in the same manner except that pellets of the propylene-ethylene random copolymer obtained in the same manner as in Comparative Example 7 were used. Observation of the heating behavior of the sheet in the same manner as in Example 7 revealed that the sheet remained hanging, did not return, and was inferior in heat vacuum moldability.

Example 8 In order to recycle the molded article of the present invention, many test pieces for measuring the flexural modulus were prepared in the same manner as in Example 1.
A polypropylene composition comprising 10% by weight of a pulverized test piece obtained by subjecting the injection molded test piece to a pulverizer and 90% by weight of a polypropylene pellet obtained in the same manner as in Example 1 was directly blown with a screw diameter of 65 mm. Using a molding machine, a kerosene can with an internal volume of 20 l was hollow-molded at a molding temperature of 220 ° C and a mold temperature of 20 ° C. As a result, a uniform hollow molded product without unevenness in thickness was obtained without drawdown. Was done.

Comparative Example 11 In Example 8, except that the polypropylene pellets obtained in the same manner as in Comparative Example 1 were used as the polypropylene, hollow molding was performed in the same manner as in Example 8, and the parison was greatly drawn down. And the hollow molding was impossible.

[0068]

As is clear from the above-described embodiment,
The polypropylene of the present invention has a high melt tension and a high crystallization temperature, and is excellent in rigidity and moldability, and can be used in a wide range of applications which were limited with conventional polypropylene.

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Claims (10)

(57) [Claims] 1. A linear crystalline polypropylene having a degree of branching index of substantially 1 and (A) a melt tension (MS) at 230 ° C. and an intrinsic viscosity measured at 135 ° C. in tetralin [ η] and 1 log (MS)> 4.24
× 1 og [η] −0.843, and (B) the crystallization temperature (Tc) and the melting point (Tm) measured by a differential scanning calorimeter (DSC) are (Tc)> 0.7.
84 × (Tm) −4.00
(C) A high melt tension polypropylene having a boiling xylene extraction residual ratio of 1% by weight or less. 2. The high melt tension polypropylene according to claim 1, wherein the crystalline polypropylene is a propylene homopolymer. 3. The high melt tension polypropylene according to claim 1, wherein the crystalline polypropylene is a propylene-olefin random copolymer containing 10% by weight or less of olefin polymerization units other than propylene. 4. An inert gas atmosphere, 1 to 10 mmol of di-2-ethylhexylperoxy-dicarbonate is added to 100 g of linear crystalline polypropylene, and the mixture is mixed at a temperature of 70 to 150 ° C. A linear crystalline polypropylene having a branching index of substantially 1, characterized in that the mixture is melted and kneaded after reacting for 10 minutes to 3 hours under the following conditions, and (A) melting at 230 ° C. The tension (MS) and the intrinsic viscosity [η] measured at 135 ° C. in tetralin are such that 1 og (MS)> 4.24 × 1 og.
[Η] −0.843, and (B) the crystallization temperature (T) measured by a differential scanning calorimeter (DSC).
c) and the melting point (Tm) are (Tc)> 0.784 × (T
m) A method for producing a high melt tension polypropylene satisfying the relationship of -4.00 and (C) having a residual boiling xylene extraction ratio of 1% by weight or less. 5. The method according to claim 4, wherein the crystalline polypropylene is a propylene homopolymer. 6. The method according to claim 4, wherein the crystalline polypropylene is a propylene-olefin random copolymer containing 10% by weight or less of olefin polymerized units other than propylene. 7. After the reaction between the crystalline polypropylene and di-2-ethylhexyl peroxydicarbonate, the mixture is subjected to a post-heating treatment at 100 to 150 ° C. for 10 minutes to 3 hours in an inert gas atmosphere. The method according to claim 4. 8. A linear crystalline polypropylene having a degree of branching index of substantially 1 and (A) a melt tension (MS) at 230 ° C. and an intrinsic viscosity measured at 135 ° C. in tetralin [ η] and 1 log (MS)> 4.24
× 1 og [η] −0.843, and (B) the crystallization temperature (Tc) and the melting point (Tm) measured by a differential scanning calorimeter (DSC) are (Tc)> 0.7.
84 × (Tm) −4.00
(C) A molded article using a high melt tension polypropylene having a boiling xylene extraction residual ratio of 1% by weight or less. 9. The molded article according to claim 8, wherein the crystalline polypropylene is a propylene homopolymer. 10. The crystalline polypropylene is a propylene-olefin random copolymer containing not more than 10% by weight of olefin polymerized units other than propylene.
The molded article according to the above.