JP3397095B2 - Highly transparent film and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a highly transparent film made of a resin composition containing a specific propylene block copolymer and a component having a nucleating effect, and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Polypropylene is widely used in the fields of films, sheets, containers and the like because it has excellent heat resistance and rigidity. In recent years, materials having flexibility, transparency, impact resistance, and heat resistance have been demanded in the medical field such as infusion bags and the food packaging field. However, although propylene homopolymer has excellent heat resistance, flexibility,
Although the transparency and impact resistance are poor, and the propylene-α-olefin random copolymer is excellent in transparency, its impact resistance is insufficient and its use is limited.

As a method for imparting impact resistance,
Some attempts have been made to improve it by mainly using a propylene block copolymer. JP-A-56-84712 discloses a melt flow index of 0.01 to 0.3 g / 10 minutes, which is suitable for an air-cooled inflation molding method, a content of a repeating unit in which part A is derived from ethylene is less than 20% by weight, A propylene-based block copolymer having characteristics such that the content of the repeating unit derived from ethylene in the part B is 20% by weight or more is disclosed, and specifically, a polymer polymerized by a solvent method is disclosed. It was unsatisfactory in terms of transparency, and in the comparative example, the content of repeating units derived from ethylene in part A was 4.6% by weight and B
The content of repeating units derived from 1 part of ethylene is 1
A copolymer containing 3.9% by weight and 17.7% by weight of part B is disclosed, but transparency is improved by reducing the content of repeating units derived from ethylene, but at low temperature. The impact strength was low and was inadequate.

In JP-A-6-93061, a Ziegler-Natta type catalyst is used to produce a polymer portion (A) mainly containing propylene in the first step in the substantial absence of an inert solvent. Then, the ethylene-propylene block copolymer obtained by producing the ethylene-propylene copolymer part (B) in the gas phase in the second step is proposed. The content of repeating units derived from is from 20 to 50% by weight,
Although the impact resistance at low temperature was good, the transparency was low and it was insufficient.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly transparent film having excellent flexibility and impact resistance, and a method for producing the same.

[0006]

Means for Solving the Problems As a result of diligent studies on a highly transparent film having flexibility and impact resistance, the present inventors have found that a specific propylene block copolymer and a component having a nucleating effect are contained. It was found that a film comprising the resin composition described above achieves the object of the present invention, and the present invention has been completed.

That is, according to the present invention, the maximum melting peak temperature (T) of the portion (CXIS portion) excluding the CXS portion containing 5% by weight or more of the 20 ° C. xylene-soluble portion (CXS portion) is contained.
m) is a resin composition containing 95 to 99.99% by weight of a propylene block copolymer having a temperature of 130 to 155 ° C. and 0.01 to 5% by weight of a component having a nucleating effect. It is a highly transparent film. Further, the present invention is the method for producing a highly transparent film, characterized in that the highly transparent film is formed by a melt extrusion method. Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The propylene-based block copolymer used in the present invention contains 5% by weight or more, preferably 7 to 30% by weight, of a xylene-soluble portion (CXS portion) at 20 ° C., excluding the CXS portion. It is a propylene-based block copolymer in which the maximum melting peak temperature (Tm) of the open portion (CXIS portion) is 130 to 155 ° C. Maximum melting peak temperature (Tm)
Is measured with a differential scanning calorimeter (DSC). If the CXS part of the propylene-based block copolymer is less than 5.0% by weight, the impact resistance is inferior, which is not preferable. If the maximum melting peak temperature (Tm) of the CXIS part of the propylene-based block copolymer is less than 130 ° C, heat resistance is insufficient, while if it exceeds 155 ° C, transparency is poor, which is not preferable.

The propylene-based block copolymer used in the present invention comprises at least a repeating unit derived from propylene (hereinafter referred to as "propylene unit") and a repeating unit derived from ethylene (hereinafter referred to as "ethylene unit").
And / or a repeating unit derived from butene-1 (hereinafter referred to as “butene-1 unit”), and at least a propylene unit and an ethylene unit and / or butene. -1 unit, which is a propylene-based block copolymer obtained by continuously producing a copolymer component (component B) different from the component A, and having a 20 ° C xylene-soluble portion (CXS).
Part) 5 wt% or more, preferably 7 to 30 wt%, and the maximum melting peak temperature (Tm) of the part excluding the CXS part (CXIS part) is 130 to 155 ° C. Is preferred. The propylene block copolymer means the propylene-ethylene and / or butene-1 copolymer component (A
Component) and a propylene-ethylene and / or butene-1 copolymer component (component B) different from the component A in the second step, which is a copolymer obtained by sequential polymerization. It means a kind of blend type copolymer, not a typical block copolymer in which a polymer end and another copolymer end are connected by a bond.

When the CXS portion of the propylene block copolymer is less than 5.0% by weight, impact resistance is poor, which is not preferable.

CXIS of propylene block copolymer
If the maximum melting peak temperature (Tm) of the part is less than 130 ° C, the heat resistance is insufficient, while if it exceeds 155 ° C, the transparency is poor, which is not preferable.

Examples of the propylene-based block copolymer capable of exhibiting even higher transparency include, for example, a propylene-ethylene copolymer portion (A component) having an ethylene unit content of 1.5 to 6.0% by weight in the first step. ) Is produced in an amount of 40 to 85% by weight of the total polymerization amount (the total of the component A and the following component B), and then in the second step, the propylene-ethylene copolymer part (B containing 7 to 17% by weight of ethylene units is contained). Component) is a block copolymer obtained by producing 15 to 60% by weight of the total polymerization amount (total of A component and B component), and the intrinsic viscosity ([η] B) of B component is 2 to 5 dl. / G, intrinsic viscosity of B component
The ratio of [[η] B) to the intrinsic viscosity of component A ([η] A) ([η] B /
A propylene block copolymer having a [η] A) of 0.5 to 1.8 is preferable.

Further, from the viewpoint of suppressing bleeding and whitening at high temperature, the propylene-based block copolymer, for example, has a content of ethylene units of 3% by weight or less and a content of butene-1 units of 3 to 3 in the first step. 25% by weight of propylene-ethylene-butene-1 copolymer part (component A) was produced in an amount of 40 to 85% by weight of the total polymerization amount (the total of the component A and the following component B), and then ethylene units were added in the second step. Propylene-ethylene-butene-1 copolymer portion (B component) having a content of 17 wt% or less and a butene-1 unit content of 3 to 35 wt%
Is a block copolymer obtained by producing 15 to 60% by weight of the total polymerization amount (the total of the components A and B), and B
The intrinsic viscosity ([η] B) of the component is 1.5 to 5.0 dl / g, B
Propylene block copolymer whose ratio ([η] B / [η] A) of component intrinsic viscosity ([η] B) and component A's intrinsic viscosity ([η] A) is 0.5 to 1.8 Coalescence is more preferred.

The content of ethylene units is measured by the ¹³ C-NMR method according to the method described on page 616 of Handbook of Polymer Analysis (1995, Kinokuniya Bookstore). The ethylene unit content (EA) of the component A is analyzed by sampling the copolymer after the completion of the polymerization in the first step. The content (EB) of the ethylene unit of the component B is determined by sampling the block copolymer after the completion of the polymerization in the second step and determining the content (EA) of the ethylene unit of the block copolymer.
B) is analyzed, and is further calculated from the ratio of the A component (PA) and the ratio of the B component (PB) by the following formula. EA × PA / 100 + EB × PB / 100 = EAB EB = (EAB−EA × PA / 100) × 100 / PB

In the case of a propylene-ethylene-butene-1 block copolymer, the proportion of component A (PA) and the proportion of component B (PB) were measured with a differential scanning calorimeter for component A and all polymers, respectively. It can be obtained from the melting peak calorific value of. The ethylene unit content (EA) of the component A and the butene-1 unit content (BA) of the component A are analyzed by sampling the copolymer after the completion of the polymerization in the first step. Further, the content of ethylene units of the B component (EB) and the content of butene-1 units of the B component (BB) are
After completion of the production of the second step, the block copolymer was sampled, and the ethylene unit content (EAB) and butene-
The content of 1 unit (BAB) is analyzed to obtain the ratio of the A component (PA) and the ratio of the B component (PB), the content of the ethylene unit of the A component (EA) and the butene-1 unit of the A component. The content (BA) should be calculated from the following formula. EB = (EAB-EA * PA / 100) * 100 / PB BB = (EAB-BA * PA / 100) * 100 / PB

The intrinsic viscosity is measured in tetralin at 135 ° C. using an Ubbelohde viscometer. The intrinsic viscosity ([η] A) of the component A is analyzed by sampling the copolymer after the completion of the polymerization in the first step. Intrinsic viscosity of B component ([η] B)
Is a sample of the block copolymer after the completion of the polymerization in the second step, the intrinsic viscosity ([η] AB) of the block copolymer is analyzed, and the ratio of A component (PA) and the ratio of B component (PB) are further analyzed. From the following formula. [η] A × PA / 100 + [η] B × PB / 100 = [η] A
B [η] B = ([η] AB− [η] A × PA / 100) × 100
/ PB

The propylene block copolymer used in the present invention is, for example, a batch polymerization method in which the A component is polymerized in the same polymerization tank in the presence of a Ziegler-Natta type catalyst, and then the B component is subsequently polymerized. Or a continuous polymerization method in which a component A and a component B are continuously polymerized using a polymerization tank comprising at least two tanks.

Specifically, for example, in the coexistence of (a) an organosilicon compound having a Si--O bond, the general formula Ti (OR
¹ ) _n X _4-n (R ¹ is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, and n is a number of 0 <n ≦ 4) and / or an ether compound (B) organoaluminum compound containing a trivalent titanium compound-containing solid catalyst component obtained by treating a solid product obtained by reducing the compound with an organomagnesium compound with a mixture of an ester compound and an ether compound and titanium tetrachloride. (C) A catalyst system comprising a silicon compound having a Si—OR ² bond (R ² is a hydrocarbon group having 1 to 20 carbon atoms), or (a) a general formula Ti (OR ¹ ) _n X _4−. A titanium compound represented by _n (R ¹ is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, and n is a number of 0 <n ≦ 4) is represented by the general formula AlR ² _m Y _3-m (R ² is a hydrocarbon group having 1 to 20 carbon atoms, Y is A solid product containing a hydrocarbyloxy group insoluble in a hydrocarbon solvent, which is obtained by reduction with an organoaluminum compound represented by the formula (1≤m≤3), is prepared with ethylene. After the polymerization treatment, a hydrocarbyloxy group-containing solid catalyst component obtained by treating in a hydrocarbon solvent in the presence of an ether compound and titanium tetrachloride at a temperature of 80 to 100 ° C., (b) an organoaluminum compound In the presence of a Ziegler-Natta type catalyst containing at least titanium, magnesium and halogen as essential components, such as a catalyst system consisting of the following, the molar ratio of Al atoms in component (b) / Ti atoms in component (a) is 1 to 2000, preferably 5 to 1500,
The molar ratio of Al atoms in the component (c) / component (b) is 0.0
2 to 500, preferably 0.05 to 50, and a polymerization temperature of 20 to 150 ° C., preferably 50 to 95
C., the polymerization pressure is atmospheric pressure to 40 kg / cm ² G, preferably ^{2 to} 40 kg / cm ² G under the conditions of propylene and ethylene and hydrogen for controlling the molecular weight in the first step to supply propylene-ethylene. After producing the polymer portion (component A), propylene, ethylene and hydrogen are subsequently supplied in the second step to produce the propylene-ethylene copolymer portion (component B).

The propylene block copolymer used in the present invention can be changed in the presence or absence of an organic peroxide by a known method, for example, by changing the fluidity represented by a melt flow rate. . Further, the propylene block copolymer may contain an antioxidant, an ultraviolet absorber, an antistatic agent, an antifogging agent, etc., if necessary.

Examples of the component having a nucleating effect used in the present invention include ethylene-α-olefin copolymers, ethylene resins such as high-density polyethylene, inorganic fillers such as talc, and organic metal salts such as aluminum phosphate. , Sorbitol nucleating agents, rosin nucleating agents and the like. Among these, ethylene-α-olefin copolymer, high-density polyethylene or aluminum phosphate is preferable.
Examples of the α-olefin of the ethylene-α-olefin copolymer include propylene, butene-1, hexene-
Examples include α-olefins having 3 to 20 carbon atoms such as 1, octene-1, and 4-methylpentene-1. The content of α-olefin is usually 0.5 to 50% by weight. The density of the ethylene-α-olefin copolymer is usually 0.910.
˜0.940 g / cm ³ . The density of high-density polyethylene is usually 0.940 to 0.970 g / cm ³ .

The resin composition used in the present invention contains 95 to 99.99% by weight, preferably 99 to 99.99% by weight of the propylene block copolymer and 0.01 to 5% by weight of the component having the nucleating effect. %, Preferably 0.01-1
It contains the weight%.

When the proportion of the component having a nucleating effect is less than 0.01% by weight, flexibility and impact resistance are excellent, but sufficient transparency cannot be exhibited, and when it exceeds 5% by weight, flexibility is high. Is inferior in properties and impact resistance, which is not preferable.

The film of the present invention can be formed by a single layer or a coextrusion type melt extrusion method. Examples of the melt extrusion method include an inflation method, a T die casting method, and a calendar method.

[0024]

EXAMPLES The present invention will be described below based on examples.
The present invention is not limited to these examples.

Next, methods for measuring physical property values in Examples and Comparative Examples will be described. (1) Ratio of Component A and Component B (% by Weight) The ratio of component A (PA) and the ratio of component B (PB) were determined from the mass balance of the components A and B during polymerization. (2) Intrinsic viscosity ([η]) Measurement was carried out in tetralin at 135 ° C. using an Ubbelohde viscometer. Intrinsic Viscosity of Components A and B ([η] A, [η] B) Intrinsic Viscosity [η] Measured After Completion of Polymerization of Component A in the First Step
A and the intrinsic viscosity [η] A measured after the polymerization in the second step
B and A component ratio (PA), B component ratio (P
From B), the intrinsic viscosity [η] B of the B component is determined by the following equation. [η] B = ([η] AB− [η] A × PA / 100) × 100
/ PB (3) Handbook of polymer analysis for ethylene unit content (published by Kinokuniya Shoten in 1995)
¹³ C-N by the method described on page 616 of
The measurement was performed by the MR method. Component A, content of ethylene unit of component B (EA, EB) Content of ethylene unit (EA) measured after completion of polymerization of component A of the first step and ethylene unit measured after completion of polymerization of the second step From the content (EAB), the ratio of the A component (PA), and the ratio of the B component (PB), the content (EB) of the ethylene unit of the B component was determined by the following formula. EB = (EAB-EA × PA / 100) × 100 / PB

(4) Transparency (haze) Measured according to JIS K7105. (5) 1% secant elastic modulus (1% SM: Secant Mo
A sample with a width of 2 cm is cut out in the film processing direction (MD) and the film width direction (TD), mounted on a tensile tester with a chuck distance of 6 cm, pulled at a speed of 5 mm / min, and stretched at 1%. From stress, 100 x (stress) /
It was obtained from the calculation formula of (cross-sectional area). The smaller this value is, the more flexible it is. (6) Impact resistance According to ASTM D1709 A method. (7) 20 ° C. Xylene Soluble Part (CXS) After completely dissolving 5 g of polypropylene in 500 ml of boiling xylene, the temperature was lowered to 20 ° C. and the mixture was allowed to stand for 4 hours or more.
Then, this was separated by filtration into a precipitate (CXIS part) and a solution, the filtrate was dried and dried at 70 ° C. under reduced pressure, and then the weight of the obtained solid was measured. (8) Maximum melting peak temperature (Tm) of CXIS part Using a differential scanning calorimeter (DSC manufactured by Perkin Elmer Co., Ltd.), 10 mg of CXIS part obtained in (7) above was melted at 220 ° C. for 5 minutes under a nitrogen atmosphere. After that, the temperature was decreased to 40 ° C. at a temperature decrease rate of 5 ° C./min. Thereafter, the temperature was raised at 5 ° C./min, and the peak temperature of the maximum peak of the obtained melting endothermic curve was defined as the maximum melting peak temperature (Tm) of the CXIS part.
The melting point of indium (In) measured with this measuring device at a temperature rising rate of 5 ° C./min was 156.6 ° C.

Example 1 [Synthesis of solid catalyst] After replacing a 200 LSUS reaction vessel equipped with a stirrer with nitrogen, 80 L of hexane, 6.55 mol of tetrabutoxytitanium, and 2.8 diisobutyl phthalate were prepared.
Mol and 98.9 mol of tetraethoxysilane were added to make a uniform solution. Then, a solution of butylmagnesium chloride in diisobutyl ether having a concentration of 2.1 mol / L 51
L was gradually added dropwise over 5 hours while maintaining the temperature in the reaction vessel at 5 ° C. After completion of dropping, the mixture was further stirred at 20 ° C. for 1 hour, solid-liquid separated at 20 ° C., and washed with 70 L of toluene three times. Next, the slurry concentration is 0.2 kg /
Toluene was added so that the amount became L, 47.6 mol of diisobutyl phthalate was added, and the reaction was carried out at 95 ° C. for 30 minutes. After the reaction, solid-liquid separation was performed, and washing with toluene was performed twice. Then, 3.13 mol of diisobutyl phthalate, 8.9 mol of butyl ether and 274 mol of titanium tetrachloride were added, and the reaction was carried out at 105 ° C. for 3 hours. After completion of the reaction, solid-liquid separation was performed at the same temperature, and then 90 L of toluene was washed twice at the same temperature. Then, the slurry concentration is 0.4 kg /
After adjusting to L, 8.9 mol of butyl ether and 137 mol of titanium tetrachloride were added, and the reaction was carried out at 105 ° C for 1 hour. After completion of the reaction, solid-liquid separation was performed at the same temperature, and 90 L of toluene was washed at the same temperature three times, and then hexane 7 was added.
The solid catalyst component was washed with 0 L three times and then dried under reduced pressure.
4 kg was obtained. The solid catalyst component contains 1.8% by weight of titanium atom, 20.1% by weight of magnesium atom, 8.4% by weight of phthalate, 0.3% by weight of ethoxy group and 0.2% by weight of butoxy group, and is a fine powder. It had a good particle property with no.

[Production of Polymer] <Preactivation of Solid Catalyst Component> Made of SUS with an internal volume of 3 L,
Sufficiently dehydrated and degassed n-hexane 1.5 L, triethylaluminum 37.
5 mmol, t-butyl-n-propyldimethoxysilane 37.5 mmol and 15 g of the above solid catalyst component were added, and propylene 15 was added while keeping the temperature in the tank at 30 ° C or lower.
g was continuously supplied for about 30 minutes to carry out preliminary activation, and then the obtained solid catalyst slurry was transferred to an SUS autoclave with an agitator having an internal volume of 150 L, and 100 L of liquid butane was added and stored. .

<Polymerization> Two fluidized bed reactors made of SUS and having an internal volume of 1 m ^{3 with} a stirrer were connected to each other, and the first stage (A
The copolymerization of propylene and ethylene as the component) and the copolymerization of propylene and ethylene as the latter part (component B) were continuously carried out in the second tank. The propylene-based block copolymer thus obtained was adjusted so that the melt flow rate (MFR) was 3.4 g / 10 minutes by a peroxide decomposition treatment, and the propylene-based block copolymer shown in Table 1 was obtained.

[0030]

[Table 1] ----------------- Content of ethylene unit of component A (wt%) 3.5 Content of ethylene unit of B component (wt%) 12.5 Ratio of component A (wt%) 65 Ratio of B component (wt%) 35 [η] A (dl / g) 3.0 [η] B (dl / g) 3.2 CXS (wt%) 13 Cm of Tm (℃) 137 −−−−−−−−−−−−−−−−−−−−−−−−−

[Production of Film] 99.5% by weight of the propylene block copolymer and 0.5% of high-density polyethylene (manufactured by Nissan Maruzen Co., Ltd., 1150D, density 0.956 g / cm ³ ).
An air-cooled inflation film processing machine (die diameter-lip = 120) manufactured by Tomy Machine Industry Co., Ltd.
φ-2.0t), the die temperature is 190 ° C, the blow-up ratio (BUR) is 2.3, and the thickness is 50 μm.
A film was produced. Table 2 shows the evaluation results of the obtained film.

Example 2 The same propylene copolymer 99 as used in Example 1
% By weight and ethylene-hexene-1 copolymer (Sumitomo Chemical Co., Ltd. Sumikasen α FZ203-0, MFR =
2.0 g / 10 min, density 0.931 g / cm ³ ) 1.
The mixture was blended with 0% by weight, and air-cooled inflation processing was performed in the same manner as in Example 1. The evaluation results are shown in Table 2.

Example 3 Melting 99.9% by weight of the same propylene-based block copolymer as used in Example 1 and 0.1% by weight of aluminum phosphate (Adeka Stab NA-21 manufactured by Asahi Denka Co., Ltd.) After kneading, using the same apparatus as in Example 1, the die temperature was 20
A film having a thickness of 50 μm was produced under the conditions of 0 ° C. and blow-up ratio (BUR) = 2.3. Table 2 shows the evaluation results of the obtained film.

Comparative Example 1 Air-cooled inflation processing was carried out in the same manner as in Example 1 except that only the same propylene block copolymer as that used in Example 1 was used. The evaluation results are shown in Table 2.

Comparative Example 2 Propylene-ethylene random copolymer (Sumitomo Chemical Co., Ltd. Sumitomonobrene FSX16E1, MFR
= 1.8 g / 10 min), and the die temperature is 230
Air-cooled inflation processing was performed in the same manner as in Example 1 except that the temperature was changed to ° C. The evaluation results are shown in Table 2.

Comparative Example 3 Propylene-ethylene block copolymer (Sumitomo Chemical Co., Ltd. Sumitomonobrene KS24E1, MFR =
2.0 g / 10 minutes, CXS part = 14% by weight, Cm of CXIS part = 164 ° C.), and die temperature of 230 ° C.
Air-cooled inflation processing was performed in the same manner as in Example 1 except that The evaluation results are shown in Table 2.

[0037]

[Table 2] ----------------------------------------- Examples Comparative Examples 1 2 3 1 2 3 --- −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Haze (%) 4.4 4.2 2.5 20.4 9.0 44.1 1% SM (kg / cm ² ) MD 3650 3510 4700 4040 5790 7230 1% SM (kg / cm ² ) TD 3650 3470 4500 4030 5860 6520 Impact strength (kg ・ cm / mm) 179 122 340 165 85 272 −−−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−−−

[0038]

As described in detail above, according to the present invention,
A highly transparent film having excellent flexibility and impact resistance can be provided. Further, the production method of the present invention can produce a highly transparent film having the above-mentioned excellent properties. Furthermore, the film of the present invention is suitable for medical fields, food packaging fields and the like.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI (C08L 53/00 C08L 23:04 23:04) B29L 7:00 B29L 7:00 (56) Reference JP-A-9-52924 (JP, A) JP 56-84712 (JP, A) JP 6-93061 (JP, A) JP 6-93062 (JP, A) JP 9-71709 (JP, A) (JP 58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 53/00 C08J 5/18 CES B29C 47/00 C08F 297/08

Claims (3)

(57) [Claims] 1. A propylene-based block copolymer containing 95 to 9
0.99% by weight and a component having a nucleating effect of 0.01 to
A resin composition containing 5% by weight was added with air-cooled inflation.
It is a highly transparent film manufactured by
-Based block copolymer uses a fluidized bed reactor in the first step
And the content of repeating units derived from ethylene
1.5-6.0% by weight of propylene-ethylene copolymer
Part (A component) total polymerization amount (total of A component and the following B component)
40-85 wt% of the
Of the repeating unit derived from ethylene using a reactor
Propylene-ethylene copolymer having a content of 7 to 17% by weight
Part (B component) of the total polymerization amount (total of A component and B component) 1
It is a block copolymer obtained by forming 5 to 60% by weight.
And the intrinsic viscosity ([η] B) of component B is 2-5 dl /
g, B component intrinsic viscosity ([η] B) and A component intrinsic viscosity
The ratio ([η] B / [η] A) with ([η] A) is 0.5 to 1.8.
A high-molecular-weight block copolymer
Transparent film. 2. The propylene-based block copolymer has a content of repeating units derived from ethylene of 3 in the first step.
The propylene-ethylene-butene-1 copolymer portion (A component) having a content of repeating units derived from butene-1 of 3 to 25% by weight is contained in the total polymerization amount (A component and B component below). The total content of repeating units derived from ethylene is 17% by weight or less, and the content of repeating units derived from butene-1 is 3 to 35% by weight. Of propylene-ethylene-
A block copolymer obtained by producing a butene-1 copolymer part (component B) in an amount of 15 to 60% by weight of the total polymerization amount (total of component A and component B), and having an intrinsic viscosity of component B ( [η]
B) is 1.5 to 5.0 dl / g, and the intrinsic viscosity of the B component ([η]
The ratio ([η] B / [η]) of B) to the intrinsic viscosity of component A ([η] A)
The highly transparent film according to claim 1, wherein A) is a propylene-based block copolymer having 0.5 to 1.8. 3. A component having a nucleating effect is ethylene-α-
The highly transparent film according to claim 1 or 2, which is an olefin copolymer, a high-density polyethylene or an aluminum phosphate salt.