JPH0873547A - Propylene block copolymer, its production and its composition - Google Patents

Abstract

PURPOSE: To obtain a propylene block copolymer excellent in rigidity, impact resistance, heat resistance and surface hardness. CONSTITUTION: This copolymer is one comprising 50-97wt.% propylene homopolymer (A) having the following properties (i) to (iv): (i) the content of a xylenol inextractibles at 25 deg.C is 99.0wt.% or above, (ii) the isotactic pentad fraction is 98.0% or above, (iii) the average isotactic chain length is 500 or above, and (iv) the total content of fractions with an average isotactic chain length of 800 or above obtained by the column fractionation method is 10wt.% or above and 50-3wt.% (the total of the components is 100wt.%) copolymer (B) comprising propylene, ethylene and/or a 4-12C α-olefin and having a propylene content of 20-80mol, provided that the sum of (A) and (B) is 100wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is particularly applicable to mechanical parts, electric
The present invention relates to a propylene block copolymer excellent in rigidity, impact resistance, heat resistance and surface hardness, which is preferably used in the field of electronic parts, packaging materials, engineering plastic substitutes, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Propylene block copolymers are widely used as industrial materials such as automobile parts and electric / electronic parts as resins improving impact resistance which is a drawback of conventional polypropylene. The propylene block copolymer is usually produced by a multi-stage polymerization method, in which propylene is polymerized in the first stage reaction and then propylene and α-olefin are copolymerized in the second stage reaction. There is. These polymerization methods include, for example, JP-B-36-15284, JP-B-38-14834, JP-B-37-11436 and JP-A-53-
-35788, JP-A-53-35789, JP-A-48-25781
JP-A-56-55416 and the like.

[0003]

However, the propylene block copolymer obtained by the above method is excellent in impact resistance, but on the contrary, rigidity and heat resistance tend to be decreased, and improvements thereof have been desired. . Further, in recent years, weight reduction of products has been aimed and improvement of various physical properties is required. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a propylene block copolymer having excellent rigidity, impact resistance, heat resistance, and surface hardness.

[0004]

As a result of intensive studies, the inventors of the present invention have found that the above object can be achieved by a propylene block copolymer comprising a propylene homopolymer part having specific physical properties, The present invention has been completed based on this finding. That is, (A) a propylene homopolymer part 50 to 9 having the following physical properties (i) to (iv)
7% by weight, and (i) xylene extraction insoluble part at 25 ° C. 99.0% by weight or more (ii) isotactic pentad fraction 98.0%
Above (iii) Isotactic average chain length of 500 or more (iv) Total amount of fractions by column fractionation having an isotactic average chain length of 800 or more 10
Weight% or more (B) Propylene content of 20 to 80 mol%, propylene and ethylene and / or α having 4 to 12 carbon atoms
-Copolymer part with olefin 50 to 3% by weight (however, (A) + (B) = 100% by weight), and a propylene block copolymer and a method for producing the same. Hereinafter, the present invention will be specifically described.

The propylene block copolymer (hereinafter referred to as "BPP") in the present invention comprises a propylene homopolymer part and a copolymer part of propylene and ethylene or an α-olefin having 4 to 12 carbon atoms. It is a polymer. Examples of the α-olefin include 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-dimethyl-1-pentene, vinylcyclopentane, vinylcyclohexane and the like. Is mentioned. These α-olefins may be used alone or in combination of two or more.

The (A) propylene homopolymer part of BPP in the present invention is substantially a propylene homopolymer, but it is required to have the following physical properties. The (A) propylene homopolymer part has a (i) xylene extraction insoluble part (hereinafter referred to as “XI”) at 25 ° C. of 99.0.
It is preferably at least 9% by weight, more preferably at least 99.5% by weight, and further preferably at least 99.7% by weight. XI is 9
If it is less than 9.0% by weight, the rigidity and heat resistance are poor. In addition,
The XI was measured by a method in which polypropylene was once dissolved in ortho-xylene at 135 ° C. and then cooled to 25 ° C. to precipitate a polymer.

Further, (ii) the isotactic pentad fraction (hereinafter referred to as "IP") needs to be 98.0% or more, preferably 98.5% or more, particularly 99.0%.
% Or more is preferable. If the IP is less than 98.0%, the rigidity and heat resistance are poor, which is not preferable. The IP is
Isotactic fraction in pentad units in a polypropylene molecular chain measured using nuclear magnetic resonance with isotope carbon ( ¹³ C-NMR). The measuring method is as described in A.
Zambelli; Macromolecules,
6 , 925 (1973), ibid, 8 , 687 (1975)
And ibid, 13 , 267 (1980).

Further, (iii) the isotactic average chain length (hereinafter referred to as "N") is 500 or more, preferably 700.
It is necessary to be 800 or more, particularly preferably 800 or more. N
Is less than 500, the rigidity and heat resistance are poor. Where N
Means the average length of the isotactic portion of the methyl group in the polypropylene molecule, and its measuring method is described in J. C. Randall; Polymer Se
queue Distribution, Academ
icPress, New York 1977, Cha
pter2).

Specifically, polypropylene 1, 2, 4
-Dissolve in a mixed solvent of trichlorobenzene / deuterated benzene by heating to a temperature of 130 ° C so that the polymer concentration becomes 10% by weight. This solution is put into a glass sample tube of 10 mmΦ, and ¹³ C-NMR spectrum is measured by the same method as for IP. An example of this spectrum diagram is shown in FIG. 1A is a spectrum of a methyl group region in polypropylene, and b is an enlarged view of the spectrum. The spectrum is measured with a pentad unit, that is, five adjacent methyl groups as one unit, and the absorption peak differs depending on the isotacticity of the methyl group (there are 10 types such as mmmm, mmmr structurally). Correspondence between the absorption peak and isotacticity is shown in b of FIG.

On the other hand, as a polymerization theory, Shan-Nong
ZHU, etc .; Polymer Journal, vo
l. 15, No. 12, p859-868 (1983).
There is a two-site model described in. That is, there are two types of active species at the time of polymerization, that is, the catalyst side and the polymer terminal, the catalyst side is called catalyst-controlled polymerization, and the other is called terminal-controlled polymerization (for details, see Furukawa Junji; Taka Molecular Essence and Topics 2, "Polymer Synthesis", P73, Kagaku Dojin (1986)).

According to the above-mentioned literature, the two-site model is, after all, α: the probability that the D-form and the L-form are added to the polymerization end by the catalyst-controlled polymerization (enantiomorphic process), that is, the degree of disorder in the isotactic chain. Index σ: Probability of the formation of meso isomers that are the same as the polymerized end due to end-dominated polymerization (Bernoulli process) ω: As the ratio of α sites, 10 types of isotactic strengths with different isotacticity in pentad units are theoretically estimated. Can be calculated Then, α, σ, and ω are obtained by the method of least squares so that the intensity measured by NMR and the theoretical intensity match, and each pentad unit is obtained by the following equation.

[0012]

[Table 1] However, β = α (1-α)

Next, the above-mentioned J. C. The definition formula of the average chain length (N) described in Randall's reference; N = the number of chains of meso form / the number of units of meso form, which is actually obtained by the following formula. N = 1 + (A ₁ + A ₂ + A ₃ ) /0.5 (A ₄ + A ₅ +
A ₆ + A ₇ ) Furthermore, (iv) the isotactic average chain length (hereinafter referred to as “N _f ”) of each fraction by the column fractionation method is 80.
The total amount of 0 or more must be 10% by weight or more, preferably 30% by weight or more, and particularly preferably 50% by weight. When _Nf is 800 or more but the total amount is less than 10% by weight, the effect of improving rigidity, surface hardness and heat resistance is poor.

Here, the column fractionation method means that after the xylene-extracted insoluble portion is dissolved in para-xylene at a temperature of 130 ° C., Celite is added and the temperature is lowered to 30 ° C. at a temperature lowering rate of 10 ° C./hour to adhere to Celite. Then, the method is to fill the column with slurry celite, raise the temperature stepwise every 30 ° C. to 2.5 ° C. with paraxylene as a developing solution, and fractionate polypropylene by fractions. For more information, see Masahiro Kakugo et
al; Macromolecules, vol. 21,
p314-319 (1988). The N _f of the separated polypropylene is measured by the above N measuring method.

The copolymer portion of (B) propylene and ethylene and / or α-olefin of BPP in the present invention has a propylene content of 20 to 80 mol%, preferably 25 to 75 mol%, In particular, 30 to 70 mol% is preferable. If the propylene content is less than 20 mol%, the appearance of the molded product is significantly deteriorated, which is not preferable. On the other hand, when it exceeds 80 mol%, the impact resistance is lowered.

The proportion of the polymer portion (A) in the BPP of the present invention is 50 to 97% by weight, preferably 55 to 95% by weight, and more preferably 60 to 90% by weight. If the proportion of the polymer portion (A) is less than 50% by weight, the heat resistance will decrease. On the other hand, if it exceeds 97% by weight, impact resistance and flexibility are deteriorated, which is not preferable.

The polymerization of BPP of the present invention is carried out in the presence of an inert hydrocarbon such as hexane, heptane, kerosene or a liquefied α-olefin solvent such as propylene in a slurry method,
The temperature condition is room temperature to 130 ° C., preferably 50 to 90 ° C., pressure 2 to 50, by a gas phase polymerization method in the absence of a solvent.
It is carried out under the condition of kg / cm ² . As the reactor in the polymerization step, those usually used in the technical field can be appropriately used, and examples thereof include a stirred tank reactor, a fluidized bed reactor, a circulation reactor, and a continuous type, a semi-batch type, or a batch type. Either method may be used.

The BPP of the present invention cannot be obtained with a known Ziegler-Natta type catalyst, for example, a titanium trichloride-based catalyst or a magnesium chloride-supported titanium catalyst. Examples of the catalyst for obtaining the BPP of the present invention include magnesium compounds,
A solid catalyst containing a titanium compound, a halogen-containing compound, and an electron-donating compound as essential components is further prepared by a general formula: TiXa
Yb (In the formula, X is a halogen atom of Cl, Br, I,
Is an electron-donating compound, a is 3 or 4, and b is an integer of 3 or less), and is then washed with a halogen-containing compound and further washed with a hydrocarbon. A polymerization catalyst may be used.

Ti Xa in the expression is, for example, RPSCout.
ts, et al, Advan.Organometal.Chem., 9 , 135 (1970), 4th
New experimental chemistry course 17 Inorganic and chelate complexes Maruzen (1991) p.35, HKKakkoen, et al, J. Organom
As described in et.Chem., 453 , 175 (1993), etc.,
It is generally known that an electron-donating compound easily forms a complex.

X is a halogen atom of Cl, Br, I, of which Cl is preferred. a is 3 or 4, but is preferably 4. Examples of Y generally include oxygen-containing compounds, nitrogen-containing compounds, phosphorus-containing compounds and sulfur-containing compounds. Examples of the oxygen-containing compound include alcohols, ethers, esters, acid halides, acid anhydrides and the like. More specifically, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, 2-ethyl alcohol, oleyl alcohol, benzyl alcohol, phenylethyl alcohol. , Phenol, cresol, ethylphenol, naphthol and other alcohols; methyl ether, ethyl ether, propyl ether, butyl ether, amino ether, hexyl ether, tetrahydrofuran, anisole, diphenyl ether and other ethers and diethers; ethyl acetate, ethyl chloroacetate , Ethyl propionate, ethyl butyrate, ethyl acrylate, ethyl crotonate, ethyl oleate , Ethyl stearate, ethyl phenylacetate, methyl benzoate,
Ethyl benzoate, propyl benzoate, butyl benzoate,
Methyl toluate, ethyl toluate, propyl toluate, butyl toluate, methyl ethyl benzoate, methyl anisate, ethyl anisate, methyl ethoxybenzoate, ethyl ethoxybenzoate, ethyl cinnamate, dimethyl phthalate, phthalic acid Diethyl, dipropyl phthalate,
Esters such as di-n-butyl phthalate, diisobutyl phthalate, dihexyl phthalate, dioctyl phthalate, γ-butyrolactone, δ-valerolactone, ethylene carbonate; acetyl chloride, benzoyl chloride, toluic acid chloride, phthalic acid chloride, etc. Acid chlorides of
Examples thereof include acid anhydrides such as maleic anhydride and phthalic anhydride. Further, these electron donating compounds may be used alone or in combination of two or more. Among these, esters are preferable, and phthalates are particularly preferable. B of Y is preferably 1 to 3 when a is 3, and 1 or 2 when a is 4;
Particularly preferred is when a is 4 and b is 1.

The BPP of the present invention is further blended with a nucleating agent to improve rigidity, heat resistance and impact strength. In the field of synthetic resins, the nucleating agent refers to a substance that has an effect of growing a crystal by becoming a nucleus when added to a crystalline resin, and there are various substances. Specific examples include metal salts of carboxylic acids, dibenzylidene sorbitol derivatives, metal phosphate salts, talc and inorganic fillers such as calcium carbonate. These nucleating agents are 1
One kind may be used, or two or more kinds may be used in combination.

The amount of the nucleating agent added is generally 0.05 to 0.5% by weight, excluding the inorganic filler, and preferably 0.
08-0.4% by weight, especially 0.1-0.35% by weight
Is preferred. On the other hand, inorganic fillers such as talc are 5
30% by weight, preferably 7 to 28% by weight, particularly 9
-25% by weight is preferred. The combination of these nucleating agents is
A known mixing method, for example, a ribbon blender, a tumbler, or a Henschel mixer is used to mix the components,
Further, it is obtained by melt mixing using a kneader, mixing roll, Banbury mixer, extruder or the like. The temperature at the time of melt mixing is usually 170 to 280 ° C, preferably 190 to 260 ° C. The composition obtained is
By a known melt molding method and compression molding method, a film,
It can be formed into a sheet, a tube, a bottle or the like and used alone, or can be used as a laminated body by laminating other materials.

As the laminating method, a so-called dry laminate molding method, a coextrusion lamination method, a coextrusion method, a coextrusion method, or a coextrusion method, in which other thermoplastic resins are laminated by using an adhesive such as polyurethane, polyester, or polyacrylic An injection molding method, a co-extrusion pipe molding method, etc. are mentioned. The multilayer laminate thus obtained can be formed into a molded body by a method of reheating and stretching using a molding method such as vacuum molding, pressure molding, stretch blow molding or the like.

Further, the BPP of the present invention contains additives commonly used by those skilled in the art, such as an antioxidant, a weather resistance stabilizer, an antistatic agent, a lubricant, an antiblocking agent and an antifogging agent.
A pigment, a plasticizer, a softening agent and the like may be appropriately added within a range that does not impair the object of the present invention.

[0025]

EXAMPLES The present invention will now be described in more detail with reference to examples. In addition, the measuring method of each physical property is shown below. [MFR] In accordance with JIS K7210, a melt indexer manufactured by Takara Co. was used. [Ethylene content] C.I. J. Carman et a
1; based on ¹³ C-NMR method described in Macromolecules, 10 , 537 (1977). [Flexural Modulus] Based on JIS K7203. [Izod impact strength] In accordance with JIS K7110,
It was measured with a notch using a U-F impact tester manufactured by Ueshima Seisakusho. [Drop weight impact strength] According to ASTM D3029-78, the weight is dropped from a height of 1 m, and the weight load is 100%.
The load when 50% of the 20 test pieces was broken was calculated while changing every g. The temperature was measured under the condition of -20 ° C. [Deflection temperature under load] In accordance with JIS K7207B method,
The load was measured at 4.6 kg. [Rockwell hardness] Measured with a scale R according to JIS K7202. [Surface Glossiness] A VG-1D type gloss meter manufactured by Nippon Denshoku Industries Co., Ltd. was used in accordance with JIS K7205.

A production example of BPP used is shown below. (A) Preparation of solid catalyst 56.8 g of anhydrous magnesium chloride was added to anhydrous ethanol 1
00g, Idemitsu Kosan Vaseline oil (CP15N) 5
00 ml and Shin-Etsu Silicone Silicone Oil (KF
96) In a 500 ml mixed solution, under a nitrogen atmosphere,
Completely dissolved at 0 ° C. This mixture is made by T.
The mixture was stirred for 3 minutes at 120 ° C. and 3000 revolutions / minute using a K homomixer. Then, the mixture was transferred into 2 liters of anhydrous heptane while maintaining stirring and cooling so as to maintain 0 ° C or lower. The obtained white solid was thoroughly washed with anhydrous heptane and vacuum dried at room temperature. White solid 3 obtained
0 g was suspended in 200 ml of anhydrous heptane, and 500 ml of titanium tetrachloride was added dropwise over 1 hour while stirring at 0 ° C. Next, when heating started to 40 ° C, 4.96 g of diisobutyl phthalate was added, and the temperature was raised to about 100 ° C by about 1
Raised in time. After reacting at 100 ° C. for 2 hours, a solid portion was collected by hot filtration. Titanium tetrachloride (500 ml) was added to the obtained solid portion, and the mixture was reacted at 120 ° C. for 1 hour under stirring, and then the solid portion was collected by hot filtration again, and 60 ° C.
1 liter of hexane 7 times, then hexane 1 at room temperature
Wash 3 times with liters.

(B) TiCl ₄ [C ₆ H ₄ (COO ⁱ C
Preparation of ₄ H ₉ ) ₂ ] To a solution of 1 liter of hexane containing 19 g of titanium tetrachloride, 27.8 g of diisobutyl phthalate was added dropwise over about 30 minutes while maintaining 0 ° C. After the dropping was completed, the temperature was raised to 40 ° C. and the reaction was performed for 30 minutes. After the reaction was completed, the solid portion was collected and washed with 500 ml of hexane 5 times to obtain the desired product.

(C) Preparation of polymerization catalyst component 20 g of the solid catalyst obtained in the above (a) was added to 300 parts of toluene.
TiC obtained in (b) above at 25 ° C.
I ₄ [C ₆ H ₄ (COO ⁱ C ₄ H ₉ ) ₂ ] 5.2 g was treated for 1 hour to be supported. After the completion of loading, the solid portion was collected by hot filtration and 300 ml of toluene and 10 m of titanium tetrachloride.
resuspend in 1 l, wash with stirring at 90 ° C for 1 hour, collect the solid part by hot filtration, and then remove the reaction mixture at 90 ° C.
5 times with 500 ml of toluene, 500 m of hexane at room temperature
Wash 3 times with 1.

[0029] Under prepolymerization nitrogen atmosphere, in a content volume of 3-liter autoclave, n- heptane 500 ml, triethyl aluminum 6.0 g, dicyclopentyldimethoxysilane 3.9
g, and 10 g of the polymerization catalyst component obtained in (c) above were added, and the mixture was stirred at a temperature range of 0 to 5 ° C for 5 minutes. next,
Propylene was fed into the autoclave so that 10 g of propylene was polymerized per 1 g of the polymerization catalyst component, and 0 to 5 was added.
Prepolymerization was carried out in the temperature range of ° C for 1 hour. The resulting prepolymerized solid catalyst component was washed with 500 ml of n-heptane three times and used for the following main polymerization.

Main polymerization (1) First-stage polymerization; 2.0 g of prepolymerized solid catalyst prepared by the above method in an autoclave with a stirrer and an internal volume of 60 liters under a nitrogen atmosphere, and triethylaluminum 1
1.4 g, dicyclopentyldimethoxysilane 6.84
g, then 18 kg of propylene, and hydrogen were charged so that the concentration would be 13000 mol ppm with respect to propylene.
The temperature was raised to 70 ° C. and polymerization was carried out for 1 hour. Then, unreacted propylene was removed to terminate the polymerization. After the reaction,
The reaction product was sampled. (2) Second-stage polymerization; after completion of the first-stage polymerization, liquid propylene was removed and ethylene / propylene = 40/6 at a temperature of 75 ° C.
0 (molar ratio) mixed gas 2.2 Nm ³ / hour, hydrogen 20
Copolymerization was carried out for 40 minutes at a feed rate of N liter / hour. After the polymerization was completed, the unreacted gas was removed to terminate the polymerization. As a result, ethylene content was 9.7% by weight and MFR was 1
8.0 kg of a propylene-ethylene block copolymer (hereinafter referred to as "BPP1") having a weight of 7.8 g / 10 minutes was obtained.

Similarly, the amount of hydrogen charged at the first stage polymerization,
By adjusting the polymerization time and the amount of ethylene during the second stage polymerization, the ethylene content is 10.5% by weight and the MFR is 8.1 g / 1.
A propylene-ethylene block copolymer having 0 minutes (hereinafter referred to as "BPP2") and an ethylene content of 8.
Propylene-ethylene block copolymer having 4% by weight and MFR of 16.7 g / 10 minutes (hereinafter referred to as "BPP3").
I got). In addition, during the second-stage polymerization, the ethylene content was 8.4% by weight, the butene-1 content was 0.7% by weight, and the MFR was 16. A propylene-ethylene block copolymer (hereinafter referred to as "BPP4") having a weight of 7 g / 10 minutes was obtained.

Further, the following two types of BP are used for comparison.
P was used. Tosoh Akzo AA type titanium trichloride 6.0g, diethyl aluminum chloride 23.5g
Was used as a catalyst component, 18 kg of propylene and hydrogen were charged so that the concentration would be 8000 mol ppm based on propylene, the temperature was raised to 70 ° C., and the polymerization was carried out in the same manner as in BPP1. As a result, ethylene content was 9.8. Wt% and MFR
Of 18.2 g / 10 minutes (hereinafter referred to as "BPP5"), BPP1 except that the catalyst prepared in (a) above was used and the amount of hydrogen at the first stage polymerization was 9300 mol ppm. Polymerization was carried out in the same manner as above, with an ethylene content of 10.1% by weight and an MFR of 18.4 g / 1.
What was 0 minutes (hereinafter referred to as "BPP6") was obtained.

Regarding the propylene homopolymer portion sampled at the end of the first stage polymerization of the above copolymer, X
I, IP, N and N _f were measured. The results are shown in Table 2. The IP measurement conditions are as follows. Measuring device JNM-GSX400 manufactured by JEOL Ltd. Measurement mode: Proton decoupling method Pulse width: 8.0 μs Pulse repetition time: 3.0 s Cumulative number of times: 20000 Solvent: 1,2,4-Trichlorobenzene /
Mixed solvent of heavy benzene (75/25 wt%) Internal circulation: Hexamethyldisiloxane Sample concentration: 300 mg / 3.0 ml Solvent measurement temperature: 120 ° C

[0034]

[Table 2]

Further, aluminum pt-butyl benzoate was used as a nucleating agent.

Examples 1 to 7, Comparative Examples 1 to 4 BPP and nucleating agent whose types and amounts are shown in Table 3 and di-t-butyl-p-cresol 0.05% by weight as a stabilizer, Pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenylpropionate 0.10% by weight and calcium stearate 0.10% by weight were mixed, and a supermixer manufactured by Kawata Manufacturing Co., Ltd. ( SMV20 type) was used for mixing and pelletized using a twin-screw extruder (AS30 type) manufactured by Nakatani Machinery Co., Ltd. Each of the obtained pellets was injection molded by Toshiba Machine Co., Ltd. (IS-170FII). Temperature 220
Each test piece was prepared at a temperature of 50 ° C. and a mold cooling temperature of 50 ° C. After leaving the obtained test piece in a thermostatic chamber at a relative humidity of 50% and a temperature of 23 ° C. for 2 days, the flexural modulus, Izod impact strength (notch), falling weight impact strength, deflection temperature under load, Rockwell hardness and surface gloss The degree was measured. Table 3 shows the obtained results.

[0037]

[Table 3]

[0038]

Since the resin composition of the present invention is excellent in rigidity, impact resistance, heat resistance and surface hardness, it is particularly useful for automobile parts, electric / electronic parts, packaging materials and the like.

[Brief description of drawings]

FIG. 1 is an example of a nuclear magnetic resonance spectrum in the methyl region of polypropylene.

[Explanation of symbols]

 a ・ ・ ・ Spectral diagram b ・ ・ ・ Enlarged view of a

Claims (3)

[Claims] 1. A propylene homopolymer part having the following physical properties (i) to (iv): 50 to 97% by weight, and (i) a xylene extraction insoluble part at 25 ° C .: 99.0% by weight or more (ii) ) Isotactic pentad fraction 98.0%
Above (iii) Isotactic average chain length of 500 or more (iv) Total amount of fractions by column fractionation having an isotactic average chain length of 800 or more 10
Weight% or more (B) Propylene content of 20 to 80 mol%, propylene and ethylene and / or α having 4 to 12 carbon atoms
-Copolymer part with olefin 50 to 3% by weight (however, (A) + (B) = 100% by weight), a propylene block copolymer. 2. A solid catalyst containing a magnesium compound, a titanium compound, a halogen-containing compound, and an electron-donating compound as essential components, further comprising a compound represented by the general formula: TiXa.Yb (wherein:
X is a halogen atom of Cl, Br, I, Y is an electron-donating compound, a is 3 or 4, and b is an integer of 3 or less. The method for producing a propylene block copolymer according to claim 1, which comprises using an improved solid catalyst component obtained by washing and further washing with a hydrocarbon. 3. A propylene block copolymer composition comprising the propylene block copolymer according to claim 1 and at least 0.05 to 30% by weight of a nucleating agent.