JPH07309910A - Production of modified polypropylene and molded article - Google Patents

Abstract

PURPOSE:To obtain a modified polypropylene having high melt tension and excellent in moldability. CONSTITUTION:100 pts.wt. crystalline polypropylene having a value (Q) of weight-average molecular weight (Mw)/number-average molecular weight (Mn), determined by the gel permeation chromatography, of 6 to 30 is mixed with 0.0005-0.5 pt.wt. organic peroxide and 0.01-5.0 pts.wt. cross-linking aid, and the mixture is heat treated at 180-300 deg.C to give a modified polypropylene having a boiling xylene extraction residue of at most 1wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing modified polypropylene and molded articles. More specifically, the present invention relates to a method for producing a modified polypropylene excellent in melt tension and melt elasticity, and a molded article using the modified polypropylene obtained by the method.

[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 extremely useful in balance with economic efficiency.
However, since the melt tension is small, the moldability is poor in the fields of hollow molding, foam molding, extrusion molding and the like.

As a method for increasing the melt tension of crystalline polypropylene, a method of reacting crystalline polypropylene with an organic peroxide and a cross-linking aid in a molten state (JP-A-59-93711 and JP-A-61). -152754
However, the improvement of the melt tension is insufficient, and when the addition amount of the organic peroxide and the crosslinking aid is increased to increase the melt tension, gel is generated and the moldability is deteriorated.

[0004]

As described above, the polypropylene obtained by the method of the known invention is insufficient in improving the melt tension, and in addition, the amount of the organic peroxide and the cross-linking aid is increased in order to increase the melt tension. However, there is a problem in that gel is generated when the ratio is increased and the moldability is deteriorated.

The inventors of the present invention have solved the problems of the above-mentioned known invention, and have earnestly studied a polypropylene suitable for blow molding, foam molding, extrusion molding, and a method for producing the same. As a result, after blending an extremely small amount of an organic peroxide and a cross-linking aid into polypropylene having a wide molecular weight distribution, it was found that the problems of the known invention can be solved by heat treatment, preferably by melt-kneading, leading to the present invention. It was

As is clear from the above description, an object of the present invention is to provide a modified polypropylene having a very high melt tension and excellent in moldability such as hollow molding, foam molding and extrusion molding, and a molded product using the polypropylene. To provide.

[0007]

The present invention has the following respective configurations (1) and (2). (1) Weight average molecular weight (Mw) / number average molecular weight (M) measured by gel permeation chromatography
The organic peroxide is added in an amount of 0.0005 to 100 parts by weight of the crystalline polypropylene having a value (n) of 6 to 30.
Modified polypropylene having a boiling xylene extraction residual rate of 1% by weight or less, characterized in that 0.5 parts by weight and 0.01 to 5.0 parts by weight of a crosslinking aid are blended and heat-treated at 180 to 300 ° C. Manufacturing method.

(2) 100 parts by weight of crystalline polypropylene having a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 6 to 30 measured by gel permeation chromatography 0.0% peroxide
005 to 0.5 parts by weight and 0.01 to 5 parts of a crosslinking aid.
A molded product comprising a modified polypropylene having a boiling xylene extraction residual rate of 1% by weight or less, characterized by being blended in an amount of 0 part by weight and heat-treated at 180 to 300 ° C.

The structure of the present invention will be described in detail below. The polypropylene used in the present invention includes not only a propylene homopolymer but also a propylene-olefin copolymer containing 40% by weight or less of an olefin polymerized unit other than propylene. In the following, polypropylene means such a meaning. To use.

The polypropylene used in the present invention must have a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 6 to 30, which is a measure of the molecular weight distribution. When the molecular weight distribution (Q) is less than 6, improvement of melt tension is insufficient, and when it exceeds 30, moldability becomes rather poor and gel is apt to occur.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography using orthodichlorobenzene as a solvent at a temperature of 135 ° C.

The modified polypropylene obtained in the present invention is
It is an essential condition that the boiling xylene extraction residual rate is 1% by weight or less. The polypropylene of the present invention needs to have a boiling xylene extraction residual rate of 1% by weight or less, which is a measure of gel content, more preferably 0.7% by weight or less, and most preferably 0.5% by weight or less. . If the extraction residual ratio is high, the moldability is deteriorated, and it is extremely difficult to remelt and recycle after use as a molded product.

The boiling xylene extraction residual ratio was obtained by placing 1 g of polypropylene in a 200 mesh wire mesh using a Soxhlet extractor, extracting with p-xylene 200 ml with boiling xylene for 6 hours, and then drying and weighing the extraction residue. , (Extraction residue weight / pre-extraction weight) × 100%.

The desirable melt tension of polypropylene for achieving the object of the present invention is that melt tension (MS) at 230 ° C. and intrinsic viscosity [η] measured in tetralin at 135 ° C. are log (MS)> 4. .24 × log [η]
The relationship represented by −0.402, more preferably log
(MS)> 4.24 × log [η] −0.347 is preferable.

Here, the melt tension (M
S) uses a melt tension tester-2 type manufactured by Toyo Seiki Co., Ltd.
Heated to ℃, melted polypropylene diameter 2.095mm
From the nozzle of No. 2 at a speed of 20 mm / min into the atmosphere of 23 ° C. to form a strand, and this strand is 3.14 m
The tension of the filamentous polypropylene at the time of taking it up at the speed of / min was measured and it was set as the melt tension (MS).

Next, a method for producing the above-mentioned modified polypropylene of the present invention will be described. The crystalline polypropylene used in the production of the modified polypropylene of the present invention has a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 6 which is a measure of the molecular weight distribution from the effect of improving the melt tension.
It is necessary to have a broad molecular weight distribution of ~ 30. The crystallinity measured by X-ray diffraction is 10
% Or more, the intrinsic viscosity [η] measured at 135 ° C. in tetralin is preferably 0.5 to 7 dl / g, particularly preferably 0.7 to 5 dl / g.
g is preferable from the viewpoint of moldability. These crystalline polypropylenes contain a catalyst obtained by combining a transition metal compound catalyst component, an organometallic compound catalyst component containing a metal selected from Groups 1 to 3 of the periodic table, and an electron donor as necessary. It is a known crystalline polypropylene obtained by polymerizing propylene.

Specifically, not only propylene homopolymers but also olefins other than propylene, such as ethylene,
Butene-1, pentene-1, hexene-1, heptene-
1, straight chain monoolefins such as octene-1, branched chain monoolefins such as 4-methylpentene-1 and 2-methylpentene-1, and further random copolymers of styrene and propylene, and propylene Obtained by homopolymerization or copolymerization of propylene with a small amount of olefins other than propylene so that the content of olefins other than propylene is 3% by weight or less, and then random copolymerization of propylene with olefins other than propylene. A so-called block copolymer can also be used. When using a copolymer, the number of olefins other than propylene is not limited to one, and 2
It does not matter if more than one type is included. In particular,
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- Examples thereof include 4-methylpentene-1 copolymer. At this time, the olefin content other than propylene in the copolymer is not particularly limited, but is preferably 40% by weight or less. If it exceeds 40% by weight, gel tends to be generated in the obtained polypropylene, which is outside the scope of the present invention.

Examples of the transition metal compound catalyst component used in the production of the above crystalline polypropylene include compounds containing a transition metal selected from Groups 3 to 8 of the Periodic Table. Ti, Zr, Hf, N
Examples include compounds containing one or more transition metals selected from b, Ta, Cr and V.

Examples of such transition metal compound catalyst components include known olefin polymerization catalyst components. Specifically, titanium compounds, magnesium compounds, and, if necessary, oxygen and nitrogen in the molecule. , A supported catalyst component comprising titanium, magnesium, halogen and, if necessary, an electron donor, which is obtained by contacting an electron donor containing at least one of phosphorus, sulfur and titanium tetrachloride. Examples of the titanium trichloride-based catalyst component obtained by contacting the obtained titanium trichloride composition with a tetravalent titanium compound and / or an electron donor. Further, a metallocene compound obtained by contacting a cyclopentadienyl compound and a transition metal compound can also be used. As the metallocene compound, those supported on an inorganic compound such as SiO ₂ , Al ₂ O ₃ or a polymer compound such as polyethylene or polypropylene can also be used.

The organometallic compound catalyst component containing a metal selected from Groups 1 to 3 of the Periodic Table is specifically a trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, aluminoxane, etc. The organoaluminum compound of is preferably used.

Further, as the electron donor used as required, any one of oxygen, nitrogen, phosphorus and sulfur in the molecule can be used.
Examples thereof include compounds containing at least one species, and specifically, organic silicon compounds having a Si—O bond, esters, ethers and the like are preferably used.

Using a catalyst prepared by combining the above transition metal compound catalyst component, an organometallic compound catalyst component containing a metal selected from Groups 1 to 3 of the periodic table, and an electron donor, if necessary. Obtained by polymerizing propylene by a known polymerization method in which slurry polymerization in which propylene is polymerized in an inert solvent, propylene itself as a solvent, bulk polymerization in which propylene itself is a solvent, gas phase polymerization mainly in propylene gas or a combination thereof is performed. Crystalline polypropylene is used in the present invention.

The method for producing crystalline polypropylene having a wide molecular weight distribution is not particularly limited, and various known methods can be used. For example, a method of mixing two or more types of crystalline polypropylene having different molecular weights, a method of polymerizing crystalline polypropylenes having different molecular weights in multiple stages, a plurality of methods,
Alternatively, it can be produced by a method in which propylene is polymerized using a specific catalyst component.

The method of the present invention is based on the polypropylene 100 described above.
0.0005 to 0.5 part by weight of an organic peroxide and 0.01 to 5.0 parts by weight of a cross-linking aid, preferably 0.001 to 0.1 and 0.1 to 0.1 part of an organic peroxide, based on parts by weight. 180-300 ° C with 0.1 to 2.0 parts by weight of auxiliary agent
It is a method of heat treatment in. The amount of organic peroxide added is 0.
If the amount is less than 0005 parts by weight, the reactivity is poor and the melt tension is not improved, and if it exceeds 0.5 parts by weight, a decomposition reaction of polypropylene occurs and further improvement of the melt tension is not desired.
If the amount of the crosslinking aid added is less than 0.01 parts by weight, the decomposition reaction of polypropylene occurs preferentially, and if it exceeds 5.0 parts by weight, the boiling xylene extraction residual rate becomes 1% by weight or more and the moldability deteriorates.

The organic peroxide to be added and mixed in the present invention is preferably one having a decomposition temperature in the range of 150 to 270 ° C., which has a half-life of 1 minute, and specifically, 2, 4, 4
-Trimethylpentyl-2-hydroperoxide,
Hydroperoxides such as diisopropylbenzene hydroperoxide, cumene hydroperoxide and t-butyl hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexane, 1 , 3-bis (t-butylperoxyisopropyl) -benzene, t-butylcumyl peroxide, di-t-butylperoxide, 2,
5-Dimethyl-2,5-di (t-butylperoxy)-
Hexyne-3, dialkyl peroxides such as tris (t-butylperoxy) triazine, 1,1-di-t-
Butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, 2,2-di (t-butylperoxy) -butane,
4,4-di-t-butylperoxyvaleric acid-n-butyl ester, 2,2-bis (4,4-di-t
-Butylperoxycyclohexyl) propane and other peroxyketals, t-butylperoxy-3,5,5-
Examples thereof include alkyl peresters such as trimethylhexanoate, t-butylperoxyacetate and t-butylperoxybenzoate, and t-butylperoxyisopropyl carbonate as percarbonate. Of these, dicumyl peroxide and di-
t-Butyl peroxide, 2,5-dimethyl-2,5
-Di (t-butylperoxy) -hexyne-3,2,5
-Dimethyl-2,5-di (t-butylperoxy) -hexane, 1,3-bis (t-butylperoxyisopropyl) -benzene and the like are preferable.

The cross-linking aid used in the present invention is used in cross-linking the polyolefin as long as it has the effect of satisfying the performance requirements necessary for the modified polypropylene obtained by the method of the present invention described later. Known publicly known crosslinking aids can be used. Such a crosslinking aid is a compound having two or more double bonds in the molecule, and specifically, 1,4-butanediol diacrylate, 1,6
-Hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, etc. 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene Dimethacrylate such as glycol dimethacrylate, trimethyl Lumpur propane triacrylate, tetra methylol methane triacrylate, triacrylate such as pentaerythritol triacrylate, trimethylolpropane trimethacrylate, trimethacrylate such as trimethylol ethane trimethacrylate,
Tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; triallyl compounds and diallyl compounds such as diallyl phthalate; oximes such as p-quinonedioxime and p-p′-dibenzoylquinonedioxime; and maleimides such as phenylmaleimide. And so on. Among these crosslinking aids, more preferred are diacrylate, dimethacrylate and triacrylate, and most preferred are diacrylate and triacrylate. These crosslinking aids can be used alone or in combination of two or more.

As a method of mixing the crystalline polypropylene and the organic peroxide, various known methods, for example, a method of mixing the polypropylene and the powdery or liquid organic peroxide and the crosslinking aid with a Henschel mixer, a tumbler or the like. Can be given.

The polypropylene of the present invention is modified by using the above mixture with a single-screw extruder, a twin-screw extruder, an extruder in which these are combined with a gear pump, a Brabender, a Banbury mixer, etc. Is melt-kneaded for about 10 seconds to 1 hour, preferably about 20 seconds to 30 minutes. If the temperature of the heat treatment is less than 180 ° C., the crosslinking reaction of polypropylene does not sufficiently occur, and if it exceeds 300 ° C., the polypropylene decomposition reaction takes precedence and polypropylene with poor mechanical strength is obtained.

In the melt-kneading, if necessary, an antioxidant, an ultraviolet absorber, an antistatic agent, a nucleating agent, a lubricant, a flame retardant, an anti-blocking agent, a coloring agent, before heating and melting.
Various additives such as an inorganic or organic filler can be blended.

The desired polypropylene of the present invention can be obtained by the above-mentioned method, but the polypropylene must have the characteristics described above. The object of the present invention cannot be achieved unless these characteristics are satisfied.

The thus-obtained modified polypropylene of the present invention has an extremely high melt tension and is excellent in moldability. Further, after being used as a molded product, it can be remelted and recycled for use. It is suitable for molding, foam molding, extrusion molding, but is not limited to the molding field, and various kinds of containers such as hollow containers, films, sheets, pipes, fibers, etc. can be formed by injection molding, T-die molding, thermoforming and the like. It can be used for molded articles.

[0032]

EXAMPLES Next, the present invention will be specifically described with reference to examples. Definitions of terms and measurement methods used in Examples and Comparative Examples are as follows. (1) Weight average molecular weight: (Mw), measured by the method described above. (2) Number average molecular weight: (Mn), measured by the method described above. (3) Boiling xylene extraction residual rate: measured by the method described above. (Unit:% by weight) (4) Intrinsic viscosity: [η], measured by the method described above.
(Unit: dl / g) (5) Melt tension: (MS), measured by the method described above. (Unit: g)

Example 1 A titanium trichloride composition obtained by the method described in Example 1 of Japanese Examined Patent Publication No. 59-28573, and further, diethylaluminum chloride was used in an amount of 3 with respect to 1 mol of titanium in the titanium trichloride composition. And a catalyst in which 0.8 mol of methyl p-toluate as a third component is combined with 1 mol of titanium in the titanium trichloride composition, and n-
Slurry polymerization of propylene in the presence of hydrogen, which is a molecular weight control agent, in hexane gives an intrinsic viscosity [η] of 2.12 dl.
/ G, weight average molecular weight (Mw) / number average molecular weight (Mn)
A propylene homopolymer having a value (Q) of 8.2 was obtained. 2,6-di-t- was added to 100 parts by weight of the obtained polypropylene.
Butyl-p-cresol 0.1 part by weight, tetrakis [methylene (3-5-di-t-butyl-4-hydroxy) hydrocinnamate] methane 0.05 part by weight, calcium stearate 0.1 part by weight, 2, 5-dimethyl-2,5
0.01 part by weight of di- (t-butylperoxy) -hexane and 0,6-hexanediol diacrylate.
7 parts by weight were added and mixed in a Henschel mixer, and the mixture was kneaded and granulated under the condition of a resin temperature of 220 ° C. using a uniaxial extruder having a screw diameter of 40 mm. Table 1 shows the physical properties of the modified polypropylene obtained here.

Example 2 In Example 1, the intrinsic viscosity [η] was 1.54 dl / g and the weight average molecular weight (Mw) / was changed by changing the amount of hydrogen and the amount of methyl p-toluate in the polypropylene production process.
A propylene homopolymer having a number average molecular weight (Mn) value (Q) of 8.7 was obtained. 100 parts by weight of the obtained polypropylene, 0.1 part by weight of 2,6-di-t-butyl-p-cresol and tetrakis [methylene (3-5-di-t-butyl-4-hydroxy) hydrocinnamate] methane. 0.0
5 parts by weight, calcium stearate 0.1 parts by weight, 2,
5-Dimethyl-2,5-di (t-butylperoxy)-
Hexane (0.005 parts by weight) and diethylene glycol diacrylate (0.5 parts by weight) were added and mixed in a Henschel mixer, and the mixture was kneaded and granulated using a uniaxial extruder having a screw diameter of 40 mm at a resin temperature of 220 ° C.
Table 1 shows the physical properties of the modified polypropylene obtained here.

Comparative Example 1 In Example 1, 0.01 mol of diethylene glycol dimethyl ether was used per mol of titanium in place of methyl p-toluate as the third component of the catalyst when obtaining polypropylene used as a raw material. Was used, and propylene was slurry-polymerized in the same manner as in Example 1 except that the amount of hydrogen was changed, and the intrinsic viscosity [η] was 2.20 dl / g and the weight average molecular weight (Mw) /
A propylene homopolymer having a number average molecular weight (Mn) value (Q) of 5.0 was obtained. Modified polypropylene pellets were obtained in the same manner as in Example 1 except that the polypropylene was used as the raw material polypropylene. Table 1 shows the physical properties of the modified polypropylene obtained here.

Comparative Example 2 100 parts by weight of the raw material polypropylene used in Example 1 was added with 0.1 part by weight of 2,6-di-t-butyl-p-cresol and tetrakis [methylene (3-5-di-t-butyl). −
4-hydroxy) hydrocinnamate] methane 0.05
Parts by weight and 0.1 part by weight of calcium stearate were added and mixed in a Henschel mixer, and the mixture was kneaded and granulated at a resin temperature of 220 ° C. using a uniaxial extruder having a screw diameter of 40 mm. The physical properties of the polypropylene obtained here are shown in Table 1.

Comparative Example 3 In Comparative Example 1, the intrinsic viscosity [η] was changed to 1.61 dl / g and the weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q ) Was obtained as 5.4 to obtain a propylene homopolymer. Modified polypropylene pellets were obtained in the same manner as in Example 2 except that the polypropylene was used as the raw material polypropylene. Table 1 shows the physical properties of the modified polypropylene obtained here.

Comparative Example 4 100 parts by weight of the raw material polypropylene used in Example 2 was added with 0.1 part by weight of 2,6-di-t-butyl-p-cresol and tetrakis [methylene (3-5-di-t-butyl). −
4-hydroxy) hydrocinnamate] methane 0.05
Parts by weight and 0.1 part by weight of calcium stearate were added and mixed in a Henschel mixer, and the mixture was kneaded and granulated at a resin temperature of 220 ° C. using a uniaxial extruder having a screw diameter of 40 mm. The physical properties of the polypropylene obtained here are shown in Table 1.

[0039]

[Table 1]

Example 3 In Example 1, as polypropylene used in the reaction, Example 1 in JP-A-62-104812 was used.
Magnesium chloride-supporting titanium catalyst component obtained by the method described above and triethylaluminum are 200 mols per 1 mol of titanium in the titanium catalyst component, and diisopropyldimethoxysilane as the third component is 1 mol of titanium in the titanium catalyst component. In the n-hexane, three continuous polymerization reactors connected in series were used with a catalyst in which 20 moles were combined with each other, while maintaining different hydrogen concentrations in the gas phase in each polymerization reactor. Intrinsic viscosity [η] obtained by continuously multi-stage polymerization of propylene at 1.52d
1 / g, weight average molecular weight (Mw) / number average molecular weight (M
The same procedure as in Example 1 was carried out except that a propylene homopolymer having a value (Q) of n) of 12.4 was used as the raw material polypropylene. Table 2 shows the physical properties of the modified polypropylene obtained here.

Comparative Example 5 In Example 3, propylene was slurry-polymerized in the same manner as in Example 3 except that one polymerization vessel was used to obtain polypropylene used as a raw material and the amount of hydrogen was adjusted. And the intrinsic viscosity [η] is 1.50 dl / g,
A propylene homopolymer having a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 4.9 was obtained. Modified polypropylene pellets were obtained in the same manner as in Example 3 except that the polypropylene was used as the raw material polypropylene. Table 2 shows the physical properties of the modified polypropylene obtained here.

Example 4 Polymerization using the same catalyst as in Example 3 to produce a high molecular weight polymer by bulk polymerization in the first stage and subsequently a low molecular weight polymer by gas phase polymerization in the same polymerization vessel. By carrying out the copolymerization of propylene and ethylene under the conditions, the ethylene unit content is 0.2% by weight and the intrinsic viscosity [η] is 2.1.
A propylene-ethylene random copolymer having a value (Q) of 6 dl / g and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 8.0 was obtained. The obtained polypropylene 100
2,6-di-t-butyl-p-cresol of 0.
1 part by weight, tetrakis [methylene (3-5-di-t-butyl-4-hydroxy) hydrocinnamate] methane 0.05 part by weight, calcium stearate 0.1 part by weight, 2,5-dimethyl-2,5 0.005 parts by weight of di- (t-butylperoxy) -hexane and 0.7 parts by weight of 1,6-hexanediol diacrylate were added and mixed in a Henschel mixer, and the mixture was mixed with a screw diameter of 40.
mm uniaxial extruder, and kneaded and granulated under the condition of a resin temperature of 220 ° C. Table 2 shows the physical properties of the modified polypropylene obtained here.

Comparative Example 6 In Example 4, except that polypropylene was used as a raw material, bulk polymerization was carried out in one step without carrying out polymerization in multiple steps, and ethylene amount and hydrogen amount were adjusted. Was copolymerized with propylene and ethylene in the same manner as in Example 4, and the ethylene unit polymerization amount was 0.2.
A propylene-ethylene random copolymer having a weight%, an intrinsic viscosity [η] of 2.12 dl / g and a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 4.8 was obtained. Modified polypropylene pellets were obtained in the same manner as in Example 4 except that the raw material polypropylene was used as the propylene-ethylundum copolymer. Table 2 shows the physical properties of the modified polypropylene obtained here.

Example 5 Using the same catalyst as in Example 3, two continuous gas phase polymerizers connected in series were used, and different hydrogen concentration in the gas phase was maintained in each polymerizer. While the copolymerization of propylene, ethylene and butene-1 is continuously carried out by gas phase polymerization in two stages, the ethylene unit content is 3.2% by weight and the butene-1 unit content is 2.5% by weight. %,
A propylene-ethylene-butene-1 random copolymer having an intrinsic viscosity [η] of 1.62 dl / g and a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 7.8 was obtained. 2,6-in 100 parts by weight of the obtained polypropylene
Di-t-butyl-p-cresol 0.1 part by weight, tetrakis [methylene (3-5-di-t-butyl-4-hydroxy) hydrocinnamate] methane 0.05 part by weight, calcium stearate 0.1 part by weight Part, 1,3-bis (t
-Butylperoxy-isopropyl) -benzene 0.0
Add 05 parts by weight and 0.4 parts by weight of trimethylolpropane triacrylate and mix with a Henschel mixer.
The mixture was kneaded and granulated at a resin temperature of 210 ° C. using a uniaxial extruder having a screw diameter of 40 mm. Table 2 shows the physical properties of the modified polypropylene obtained here.

Comparative Example 7 In Example 5, when the polypropylene used as the raw material was obtained, the gas phase polymerization was carried out in one step without carrying out the polymerization in multiple steps, and the ethylene content, butene-1 and hydrogen concentration were adjusted. Copolymerization of propylene-ethylene-butene-1 was carried out in the same manner as in Example 5 except that the adjustment was made so that the ethylene unit polymerization amount was 3.2% by weight and the butene-1 unit content was 2.5% by weight. , The intrinsic viscosity [η] is 1.60 dl / g,
A propylene-ethylene-butene-1 random copolymer having a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 4.1 was obtained. Modified polypropylene pellets were obtained in the same manner as in Example 5, except that the propylene-ethylene-butene-1 random copolymer was used as the raw material polypropylene. Table 2 shows the physical properties of the modified polypropylene obtained here.

[0046]

[Table 2]

Example 6 A modified polypropylene was obtained in the same manner as in Example 1 except that 0.1 part by weight of talc was added as a foam nucleating agent. The obtained pellets were screwed with a screw diameter of 65 mm and an extruder temperature of 2
It was fed into a single-screw extruder set at 30 ° C. Then, 22 parts by weight of 1,1,2,2-tetrafluorodichloroethane was injected as a foaming agent from the middle of the extruder. Extrusion foam molding was carried out at a mold temperature of 155 ° C. using a nozzle-shaped mold having a diameter of 5 mm mounted on an extruder. The surface of the obtained foam was smooth, and abnormal cells were not observed, and the cells had uniform cells.

Comparative Example 8 A modified polypropylene was obtained in the same manner as in Comparative Example 1, except that 0.1 part by weight of talc was added as a foam nucleating agent. When extrusion foam molding was carried out in the same manner as in Example 6 except that this modified polypropylene was used, the resulting foam had a poor appearance due to outgassing.

Example 7 The modified propylene-ethylene random copolymer pellets obtained in the same manner as in Example 4 were extrusion-sheeted at 260 ° C. using an extruder with a T-die and a screw diameter of 65 mm. Then, a sheet having a thickness of 0.5 mm was obtained. Next, in order to evaluate the heat-vacuum formability of the sheet as a model, the sheet was fixed to a 40 cm square frame and
The behavior was observed by placing in a thermostatic chamber at 0 ° C. By heating, the center portion of the sheet started to hang down, and when it drooped 38 mm, the hanging stopped, and conversely, the lower part rose. The sheet started to hang down again 15 seconds after the hang-down stopped, and only drooped thereafter. It was found that the amount of drooping was small and the time until the start of re-drooping was as long as 15 seconds, and the sheet was extremely excellent in heating vacuum forming property.

Comparative Example 9 In Example 7, instead of the polypropylene of the present invention,
A sheet was obtained in the same manner except that the pellets of the modified propylene-ethylene random copolymer obtained in the same manner as in Comparative Example 6 were used. When the heating behavior of the sheet was observed in the same manner as in Example 7, it was found that the hanging was 46 mm.
However, the time until the start of re-hanging was as short as 6 seconds, and the heating vacuum forming property was inferior to that of Example 7.

[0051]

As is apparent from the above description, according to the method of the present invention, the melt tension of polypropylene is remarkably improved and the gel content is eliminated so that the hollow molding, foam molding,
It has excellent moldability such as extrusion molding, and it is possible to expand the fields of application that were limited by conventional polypropylene.

Claims (2)

[Claims] 1. An organic solvent is added to 100 parts by weight of crystalline polypropylene having a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 6 to 30 measured by gel permeation chromatography. Oxide 0.000
5 to 0.5 parts by weight and 0.01 to 5.0 parts by weight of a cross-linking aid are mixed and heat-treated at 180 to 300 ° C., and the boiling xylene extraction residual rate is 1% by weight or less. For producing high quality polypropylene. 2. An organic solvent is added to 100 parts by weight of crystalline polypropylene having a weight average molecular weight (Mw) / number average molecular weight (Mn) value (Q) of 6 to 30 measured by gel permeation chromatography. Oxide 0.000
5 to 0.5 parts by weight and 0.01 to 5.0 parts by weight of a cross-linking aid are mixed, and the boiling xylene extraction residual rate obtained by a method of heat treatment at 180 to 300 ° C. is 1% by weight or less. A molded product made of high quality polypropylene.