JP7138030B2 - Injection stretch blow molding of polypropylene composition and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an injection stretch blow molded article of a polypropylene composition and a method for producing the same.

Polypropylene is useful as a food container because it has excellent physical properties and is also excellent in terms of hygiene. However, the polypropylene container has a problem that its impact resistance is lowered when it is used at a low temperature. Furthermore, polypropylene containers are required to have high rigidity and transparency so that the contents can be checked. For the purpose of improving transparency and cold impact resistance, Patent Document 1 discloses that in the presence of an ethylene-propylene copolymer containing 2.0 to 4.0% by weight of ethylene units, ethylene containing 74 to 86% by weight of ethylene units is prepared. A composition obtained by polymerizing a -1-butene copolymer and having an ethylene-1-butene copolymer content of 10 to 20% by weight has been proposed. Further, in Patent Document 2, an ethylene-1-butene copolymer containing 74 to 86% by weight of ethylene units is polymerized in the presence of an ethylene-propylene copolymer or homopolypropylene containing 1.2% by weight or less of ethylene units. A composition having an ethylene-1-butene copolymer content of 22 to 32% by weight has been proposed. Furthermore, in Patent Document 3, in the presence of an ethylene-propylene copolymer containing 2.0 to 4.0% by weight of ethylene units for the purpose of improving cold impact resistance, 74 to 86% by weight of ethylene units is a composition obtained by polymerizing the ethylene-1-butene copolymer of No. 1, wherein the content of the ethylene-1-butene copolymer is 25 to 35% by weight.

JP 2012-126829 A JP 2012-107136 A JP 2012-126828 A JP-A-10-168254

However, the compositions described in the above-mentioned patent documents still do not have a sufficient balance of transparency, rigidity, and cold impact resistance. Injection stretch blow molded articles are used for containers and the like, but the aforementioned patent documents do not refer to injection stretch blow molded articles. Regarding injection stretch blow molded articles, Patent Document 4 proposes polypropylene compositions containing linear low-density polyethylene and ethylene/1-butene copolymers. do not have. Furthermore, the production of the composition requires an intermediate step of blending and melt-kneading a plurality of polymer components, which is not necessarily suitable for industrial scale implementation. In view of such circumstances, an object of the present invention is to provide an injection stretch blow-molded article of a polypropylene composition having an excellent balance of transparency, rigidity and cold impact resistance.

The inventors have found that the above problems can be solved by using a specific polypropylene composition. That is, the above problems are solved by the present invention described below.
[1] (I) A propylene-ethylene copolymer containing 1.5 to 2.5% by weight of ethylene-derived units as component (1),
A polypropylene composition A comprising, as component (2), an ethylene-1-butene copolymer containing 14 to 18% by weight of 1-butene-derived units, and a nucleating agent,
Requirements for:
1) The weight ratio of component (1) and component (2) is 75-83:25-17 2) The intrinsic viscosity of the xylene-soluble portion of the composition is 0.8-1.2 dl/g 3 ) A step of preparing a polypropylene composition A that satisfies the MFR (230 ° C., load 2.16 kg) of 15 to 40 g / 10 minutes,
(II) comprising a step of injection stretch blow molding the polypropylene composition A;
A method for producing an injection stretch blow molded article.
[2] Before step (II), a polypropylene composition B containing a polymer selected from the group consisting of propylene homopolymers, propylene random copolymers, and combinations thereof is prepared and mixed with polypropylene composition A. further comprising a step (I') of preparing a mixture by
The production method according to [1], wherein in step (II), the mixture is subjected to injection stretch blow molding.
[3] The production method according to [2], wherein the weight ratio of polypropylene composition A and polypropylene composition B is "40 or more and less than 100": "greater than 0 to 60 or less".
[4] The production according to any one of [1] to [3], which contains 0.01 to 0.5 parts by weight of a nucleating agent with respect to a total of 100 parts by weight of components (1) and (2). Method.
[5] Any of [2] to [4], wherein the polypropylene composition B contains 0.01 to 0.5 parts by weight of a nucleating agent with respect to a total of 100 parts by weight of the polymer according to [2]. The manufacturing method according to
[6] An injection stretch blow-molded article obtained by the production method according to any one of [1] to [5].
[7] A container comprising the molded article according to [6] above.

INDUSTRIAL APPLICABILITY According to the present invention, an injection stretch blow molded article of a polypropylene composition having an excellent balance of transparency, rigidity and cold impact resistance can be provided.

MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below. "X to Y" includes X and Y which are the extreme values.
1. Process I
(1) polypropylene composition A
A polypropylene composition A is prepared in this step. Polypropylene composition A contains the following components (1) and (2).
Component (1): Propylene-ethylene copolymer containing 1.5 to 2.5% by weight of ethylene-derived units Component (2): Ethylene-1-butene copolymer containing 14 to 18% by weight of 1-butene-derived units polymer

1) Component (1)
Component (1) is a propylene-ethylene copolymer containing 1.5 to 2.5% by weight of ethylene-derived units. A propylene-ethylene copolymer containing 1.5% by weight of ethylene-derived units is a copolymer in which the weight ratio of ethylene-derived units to propylene-derived units is 1.5:98.5. The same applies to other copolymers. The upper limit of the content of ethylene-derived units is 2.5% by weight or less, preferably 2.3% by weight or less. If the amount exceeds the upper limit, the rigidity and transparency will decrease. The lower limit of the ethylene-derived units is 1.5% by weight or more, preferably 1.7% by weight or more. Transparency will fall that the said amount is less than a lower limit. Component (1) may contain less than 1% by weight of 1-butene units due to, for example, recycled gas generated during production of the polymer containing component (2). Component (1) is preferably a random copolymer.

2) Component (2)
Component (2) is an ethylene-1-butene copolymer containing 14-18% by weight of 1-butene-derived units. The upper limit of the content of 1-butene-derived units is 18% by weight or less, preferably 17% by weight or less. If the amount exceeds the upper limit, the transparency will decrease. The lower limit of the 1-butene-derived unit is 14% by weight or more, preferably 15% by weight or more. If the amount is less than the lower limit, the cold impact resistance is lowered. Component (2) may contain less than 1% by weight of propylene-derived units due to, for example, recycled gas generated during production of the polymer containing component (1).

3) Composition ratio The composition ratio (weight ratio) of component (1) and component (2) is 75-83:25-17, preferably 76-80:24-20. When the amount of component (1) exceeds the upper limit, the cold impact resistance is lowered. If the amount of component (1) is less than the lower limit, the rigidity is lowered, and the polymer powder tends to adhere to each other, increasing the risk of clogging in storage or transportation routes, making it difficult to produce polypropylene composition A. tend to become

4) Nucleating agent Polypropylene composition A contains a nucleating agent. A nucleating agent is an additive (transparent nucleating agent) that is used to control the size of crystal components in a resin to be small to particularly improve transparency. The amount of the nucleating agent is preferably 0.01 to 0.5 parts by weight, more preferably 0.01 part per 100 parts by weight of the total amount of components (1) and (2) (hereinafter also referred to as "resin component"). ~0.4 parts by weight, more preferably 0.015 to 0.4 parts by weight. Satisfactory transparency and cold impact resistance cannot be obtained unless a nucleating agent is contained. Even if the content of the nucleating agent exceeds the above upper limit, the effect of promoting the formation of crystal nuclei reaches a plateau and simply increases the production cost, which is not realistic for industrial mass production at low cost.

The nucleating agent is not particularly limited, and those commonly used in the field may be used. It is preferably selected from metal salt nucleating agents and organic nucleating agents such as xylitol nucleating agents. Nonitol nucleating agents include, for example, 1,2,3-trideoxy-4,6:5,7-bis-[(4-propylphenyl)methylene]-nonitol. Examples of sorbitol-based nucleating agents include 1,3:2,4-bis-o-(3,4-dimethylbenzylidene)-D-sorbitol. Phosphate nucleating agents such as 2,2′-methylenebis(4,6-di-t-butylphenyl) sodium phosphate, 2,2′-methylenebis(4,6-di-tert phosphate), -Butylphenyl)aluminum salts, 2,2′-methylenebis(4,6-di-tert-butylphenyl)lithium phosphates, and other aromatic phosphate nucleating agents. Examples of triaminobenzene derivative-based nucleating agents include 1,3,5-tris(2,2-dimethylpropanamido)benzene and the like. Carboxylic acid metal salt nucleating agents include, for example, sodium adipate, potassium adipate, aluminum adipate, sodium sebacate, potassium sebacate, aluminum sebacate, sodium benzoate, aluminum benzoate, di-para-t-butyl Examples include aluminum benzoate, titanium di-para-t-butylbenzoate, chromium di-para-t-butylbenzoate, and aluminum hydroxy-di-t-butylbenzoate. Examples of xylitol-based nucleating agents include bis-1,3:2,4-(5′,6′,7′,8′-tetrahydro-2-naphthaldehydebenzylidene)1-allylxylitol, bis-1,3: 2,4-(3',4'-dimethylbenzylidene) 1-propylxylitol. The above nucleating agents may be used singly or in combination of two or more.

A polypropylene composition A containing a nucleating agent can be prepared by mixing the resin component and the nucleating agent and melt-kneading the mixture. At this time, if necessary, a resin other than the resin component (except polypropylene composition B) or rubber, or an additive described later may be further mixed. The order of adding each component is not limited. The mixing method is also not limited, and examples thereof include a method using a mixer such as a Henschel mixer or a tumbler mixer. After mixing, the resulting mixture may be melt-kneaded and pelletized. A single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader, a roll mill, or the like can be used as a melt-kneading device.

5) Characteristic XSIV
The xylene soluble intrinsic viscosity (XSIV) of polypropylene composition A is an indicator of the molecular weight of the non-crystalline component in the composition. XSIV is obtained by obtaining a component soluble in xylene at 25° C. and measuring the intrinsic viscosity of the component by a conventional method. In the present invention, XSIV is 0.8-1.2 dl/g. If the XSIV exceeds the upper limit, the transparency will decrease, and if it is below the lower limit, it will be difficult to produce the polypropylene composition. From this point of view, the intrinsic viscosity is preferably 0.9 to 1.1 dl/g.

MFR
The MFR of polypropylene composition A at 230° C. and a load of 2.16 kg is 15 to 40 g/10 minutes. When the MFR exceeds the upper limit, the cold impact resistance and transparency are lowered, and when the MFR is less than the lower limit, molding becomes difficult. From this point of view, the MFR is preferably 20-40 g/10 min, more preferably 20-35 g/10 min.

6) Other components Polypropylene composition A contains antioxidants, chlorine absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, internal lubricants, external lubricants, antiblocking agents, antistatic agents, antifogging agents, Conventional additives commonly used in the field such as flame retardants, dispersants, anti-copper agents, neutralizers, plasticizers, antifoam agents, cross-linking agents, peroxides, oil extenders and other organic and inorganic pigments may be added. The amount of each additive to be added may be a known amount. The polypropylene composition A may contain one or more resins other than the resin component (excluding the polypropylene composition B) or rubber within the range that does not impair the effects of the present invention.

(2) Method for producing polypropylene composition A Polypropylene composition A can be produced according to a known method. preferably. Particularly preferred is a method of polymerizing the raw material monomer of component (1) to produce a copolymer of component (1) and then polymerizing the raw material monomer of component (2) in the presence of the copolymer. The polymerization can be carried out in liquid phase, gas phase or liquid-gas phase. The polymerization temperature is preferably normal temperature to 150°C, more preferably 40°C to 100°C. The polymerization pressure is preferably in the range of 3.3-6.0 MPa when carried out in the liquid phase, and in the range of 0.5-3.0 MPa when carried out in the gas phase. Conventional molecular weight modifiers known in the art such as chain transfer agents (eg hydrogen or ZnEt ₂ ) may be used.

Also, a polymerization vessel having a gradient of monomer concentration and polymerization conditions may be used. Such a polymerization vessel can be used, for example, with at least two connected polymerization zones and can polymerize the monomers by gas phase polymerization. Specifically, in the presence of a catalyst, a monomer is supplied and polymerized in a polymerization region composed of an ascending pipe, a monomer is supplied and polymerized in a descending pipe connected to the ascending pipe, and the ascending pipe and the descending pipe are used. is circulated to recover the polymer product. The method comprises means for wholly or partially preventing the gas mixture present in the riser from entering the downcomer. Also, a gas or liquid mixture is introduced into the downcomer having a different composition than the gas mixture present in the riser. As the above polymerization method, for example, the method described in JP-T-2002-520426 can be applied.

Polymerization includes (A) solid catalysts containing magnesium, titanium, halogen, and electron donor compounds, (B) organoaluminum compounds, and (C) Ziegler-Natta catalysts, including external electron donor compounds, and metallocene catalysts. Available. Examples of the electron donor compound (also referred to as "internal electron donor compound") in component (A) include phthalate compounds, succinate compounds, and diether compounds. can be used and, if desired, those compounds may be used in combination.

2. Step (I')
The production method of the present invention comprises a step of preparing a polypropylene composition B containing a polymer selected from the group consisting of propylene homopolymers, propylene random copolymers, and combinations thereof, and mixing with polypropylene composition A. may
(1) polypropylene composition B
Polymers used in the polypropylene composition B include known polymers, but are preferably selected so that the MFR of the polypropylene composition B is in the same range as that of the polypropylene composition A.

The amount of comonomer units in the propylene random copolymer is preferably 5.0% by weight or less, more preferably 4.0% by weight or less. If the amount of comonomer exceeds the upper limit, the stability during production of polypropylene composition B may decrease. Ethylene is preferable as the comonomer because it is industrially inexpensive, stably distributed, and relatively easy to obtain.

Polypropylene composition B may contain a nucleating agent, and the type and amount of nucleating agent used in that case are as described for polypropylene composition A.

(2) Mixture The weight ratio of polypropylene composition A and polypropylene composition B is preferably "40 or more and less than 100": "greater than 0 to 60 or less". The lower limit of polypropylene composition B is preferably 0.2 or more, more preferably 1 or more, and still more preferably 10 or more. Thus, in one aspect the weight ratio is 45-90:55-10. The mixing method is not limited, and for example, a method such as melt-kneading or dry-blending the two can be used.

3. Step (II)
In this step, polypropylene composition A or a mixture of polypropylene composition A and polypropylene composition B (hereinafter collectively referred to as “polypropylene composition used in the present invention” or simply “polypropylene composition”) is injection-stretched. Blow molding. Injection stretch blow molding is a molding method in which a resin composition is injection molded to form a preform, and the preform is stretch blow molded. The longitudinal draw ratio (axial draw ratio) during stretch blow molding (biaxial drawing) is usually 1.5 times or more, preferably 1.6 to 5 times, and the transverse draw ratio (circumferential stretch ratio) is It is usually 1.5 times or more, preferably 1.6 to 10 times. If the draw ratio of the molded product is less than 1.5 times, there is a possibility that problems may arise in terms of transparency and buckling strength. The longitudinal/lateral stretching ratio is preferably 0.2 to 5 times, more preferably 0.3 to 3 times. The cylinder temperature, mold temperature, and temperature during biaxial stretching can be appropriately adjusted according to the properties of the polypropylene composition, but are usually about 190 to 250°C, 10 to 40°C, and 80 to 160°C, respectively.

3. Injection Stretch Blow Molded Article According to the present invention, an injection stretch blow molded article can be produced. The molded product is a beverage bottle container, a food container such as a confectionery bottle container, a fruit juice container, a mineral water container; a bottle container for a toiletry solution such as a shampoo, a rinse, and a liquid soap; Bottles for liquid cosmetics; Bottles for alcohol, industrial chemicals, etc.; Medical containers, such as infusion bottles and blood bottles; Bottles for leisure use; It is useful for various purposes. In particular, the injection stretch blow-molded article of the present invention is useful as a food container, and particularly useful as a container used at a low temperature such as -20°C. The container may have members other than the polypropylene composition. The container may have any known shape, but preferably has a thickness of 0.1 to 0.7 mm.

The polypropylene composition used in the present invention preferably has the following properties.
1) Rigidity Flexural modulus (JIS K6921-2): 900 to 1400 MPa
2) Cold impact resistance Charpy impact strength at 0°C: ² kJ/m2 or more

[Production Example 1: Polypropylene composition A-1]
A solid catalyst of Ti and diisobutyl phthalate as an internal donor on MgCl2 was prepared by the method described in Example ₅ of EP 728769. Next, using the solid catalyst, triethylaluminum (TEAL) as an organoaluminum compound, and dicyclopentyldimethoxysilane (DCPMS) as an external electron donor compound, the weight ratio of TEAL to the solid catalyst is 20, and the weight ratio of TEAL/DCPMS of 10 at 12° C. for 24 minutes. Prepolymerization was carried out by keeping the resulting catalyst system in suspension in liquid propylene at 20° C. for 5 minutes. The obtained prepolymer is introduced into the first-stage polymerization reactor of a polymerization apparatus equipped with two-stage polymerization reactors in series, and ethylene is fed to propylene in a liquid phase state to obtain component (1) propylene- An ethylene random copolymer was produced, and an ethylene-1-butene copolymer as component (2) was produced in a second-stage gas-phase polymerization reactor. During the polymerization, temperature and pressure were controlled and hydrogen was used as a molecular weight regulator.

The polymerization temperature and the ratio of the reactants are as follows: in the first stage reactor, the polymerization temperature, hydrogen concentration, and ethylene concentration are 70° C., 0.80 mol %, and 0.53 mol %, respectively; in the second stage reactor, The polymerization temperature, H2/C2 and C4/(C2+C4) were 80° C., 0.30 molar ratio and 0.35 molar ratio, respectively. Also, the residence time distribution in the first stage and the second stage was adjusted so that the amount of component (2) was 22% by weight. With respect to 100 parts by weight of the obtained resin component, 0.02 parts by weight of IRGACLEAR XT386 (triaminobenzene derivative-based nucleating agent) manufactured by BASF as a nucleating agent, and 0.2 parts by weight of B225 manufactured by BASF as an antioxidant. 0.05 parts by weight of calcium stearate manufactured by Tannan Kagaku Kogyo Co., Ltd. was blended as a neutralizing agent, and stirred and mixed for 1 minute with a Henschel mixer. The mixture was extruded at a cylinder temperature of 230° C. using an NVCφ50 mm single-screw extruder manufactured by Nakatani Kikai Co., Ltd. The strand was cooled in water and then cut with a pelletizer to obtain a polypropylene composition A-1 in the form of pellets. The composition was evaluated by the method described later. Table 1 shows the results.

[Production Example 2: Polypropylene composition A-2]
As the nucleating agent, 0.02 parts by weight of IRGACLEAR XT386 (triaminobenzene derivative-based nucleating agent) manufactured by BASF and 0.2 parts by weight of Millad NX8000J (nonitol-based nucleating agent) manufactured by Milliken were used. Polypropylene composition A-2 was produced in the same manner as in Example 1.

[Production Example 3: Comparative polypropylene composition A-3]
In the first-stage reactor, ethylene is not fed and the hydrogen concentration is changed to 0.95 mol% to polymerize propylene homopolymer. ) were changed to 0.27 molar ratio and 0.41 molar ratio, respectively, and the residence time distribution in the first and second stages was adjusted so that the amount of ethylene-1-butene copolymer was 23% by weight. Comparative polypropylene composition A-3 was produced in the same manner as in Production Example 1, except that

[Production Example 4: Comparative polypropylene composition A-4]
The hydrogen concentration and ethylene concentration in the first reactor are changed to 0.84 mol% and 0.84 mol%, respectively, and the C4/(C2+C4) in the second reactor is changed to 0.41 molar ratio. In addition, IRGACLEAR XT386 (triamino A comparative polypropylene composition A-4 was produced in the same manner as in Production Example 2, except that the benzene derivative-based nucleating agent) was not added.

[Production Example 5: Comparative polypropylene composition A-5]
A solid catalyst supporting Ti and diisobutyl phthalate as an internal donor on MgCl ₂ was prepared by the method described in paragraph 0032, lines 21-36 of JP-A-2004-27218. Then, using the above solid catalyst, triethylaluminum (TEAL) as an organoaluminum compound, and dicyclopentyldimethoxysilane (DCPMS) as an external electron donor compound, the weight ratio of TEAL to solid catalyst is 20, and the weight ratio of TEAL to DCPMS is A catalyst was obtained by contacting them at 12° C. for 24 minutes in an amount to give a .di.sup.10. The obtained catalyst was prepolymerized by keeping it in suspension in liquid propylene at 20° C. for 5 minutes to obtain a prepolymer. The obtained prepolymer is introduced into the first-stage polymerization reactor of a polymerization apparatus equipped with two-stage polymerization reactors in series, and propylene in a liquid phase state is fed to obtain a propylene homopolymer as component (1). was produced, and an ethylene-propylene copolymer as component (2) was produced in the second-stage gas-phase polymerization reactor. During the polymerization, temperature and pressure were controlled and hydrogen was used as a molecular weight regulator. As for the ratio of polymerization temperature and reactants, in the first-stage polymerization reactor, the polymerization temperature and hydrogen concentration were 70° C. and 1.11 mol %, respectively, and in the second-stage polymerization reactor, the polymerization temperature, hydrogen concentration, and C2/ (C2+C3) were respectively at 80° C., 2.45 mol % and 0.49 mol ratio. Also, the residence time distribution in the first stage and the second stage was adjusted so that the amount of component (2) was 19% by weight. Using the obtained resin component, a comparative polypropylene composition A-5 was produced in the same manner as in Production Example 4.

[Production Example 6: Polypropylene composition B-1]
The solid catalyst used for polymerization was prepared by the method described in Example 1 of EP 674991. The solid catalyst is obtained by supporting Ti and diisobutyl phthalate as an internal donor on MgCl ₂ by the method described in the above patent publication. The solid catalyst was mixed with triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) in amounts such that the weight ratio of TEAL to solid catalyst was 11 and the weight ratio of TEAL/DCPMS was 10 at -5°C. contact for 1 minute. Prepolymerization was carried out by keeping the resulting catalyst system in suspension in liquid propylene at 20° C. for 5 minutes. After introducing the obtained prepolymer into a polymerization reactor, hydrogen, propylene and ethylene were fed, and the polymerization temperature, hydrogen concentration and ethylene concentration were set to 75° C., 0.97 mol % and 0.80 mol %, respectively. A propylene-ethylene random copolymer containing 3.0% by weight of ethylene-derived units and having an MFR of 25 g/10 min was produced by adjusting the pressure. Polypropylene composition B-1 was prepared in the same manner as in Production Example 1, except that 0.2 parts by weight of Millad 3988 (sorbitol-based nucleating agent) manufactured by Milliken Co., Ltd. was used as a nucleating agent for 100 parts by weight of the resulting resin component. manufactured.

[Production Example 7: Polypropylene composition B-2]
In the polymerization reactor of Production Example 6, ethylene was not fed and the hydrogen concentration was changed to 0.71 mol% to polymerize a propylene homopolymer having an MFR of 30 g/10 min. Polypropylene composition in the same manner as in Production Example 6, except that 0.2 parts by weight of Millad NX8000J (nonitol nucleating agent) manufactured by Milliken Co., Ltd. was used instead of Millad 3988 (sorbitol nucleating agent) as a nucleating agent. Product B-2 was produced.

[Example 1]
Using the polypropylene composition A-1, a preform was produced by injection molding under the following conditions. The preform had a weight of 30 g and a wall thickness of 3.0 mm.
Injection molding machine: ECOJET 180B52 manufactured by LTD
Molding temperature (°C): 250
Mold temperature (°C): 25
Injection time (seconds): 8.5
Injection pressure (kg/cm ² ): 60
Holding pressure (kg/cm ² ): 50
Holding pressure time (seconds): 5
Total cycle time (seconds): 56

The preform was stretch-blow molded under the following conditions to form a 500 mL cylindrical bottle (container) with an average wall thickness of 0.5 mm.
Stretch blow molding machine: Cold parison method manufactured by Jiaming Machinery Co., Ltd. Preform temperature (°C): 94
Blow pressure (kg/cm ² ): 7
Blow time (seconds): 3.5
Longitudinal draw ratio: 1.9
Lateral draw ratio: 2.0

The polypropylene compositions and molded articles thereof were evaluated by the method described below. Table 2 shows the results. The polypropylene composition of Example 1 was excellent in moldability in injection stretch blow molding, and the resulting molded article had a good balance of transparency, rigidity and cold impact resistance.

[Example 2]
A molded article was produced and evaluated in the same manner as in Example 1, except that the polypropylene composition A-2 was used. The moldability in injection stretch blow molding was excellent, and the resulting molded article had a good balance of transparency, rigidity and cold impact resistance.

[Example 3]
Polypropylene composition A-1 and polypropylene composition B-1 were dry-blended at a ratio of 1:1 (weight ratio) to prepare a polypropylene composition used in the present invention. A preform was manufactured by injection molding the composition under the above conditions. A bottle was produced from the obtained preform by stretch blow molding in the same manner as in Example 1 and evaluated. The moldability in injection stretch blow molding was excellent, and the resulting molded article had a good balance of transparency, rigidity and cold impact resistance.

[Example 4]
A molded article was produced and evaluated in the same manner as in Example 3, except that the polypropylene composition B-2 was used instead of the polypropylene composition B-1. The moldability in injection stretch blow molding was excellent, and the resulting molded article had a good balance of transparency, rigidity and cold impact resistance.

[Comparative Example 1]
A molded article was produced and evaluated in the same manner as in Example 1, except that the polypropylene composition A-3 for comparison was used instead of the polypropylene composition A-1. Injection stretch blow molding was possible, but the molded product after stretch blow molding became translucent in the evaluation of transparency (visual observation).

[Comparative Example 2]
A molded article was produced and evaluated in the same manner as in Example 4, except that the polypropylene composition A-4 for comparison was used as shown in Table 2 instead of the polypropylene composition A-1. Injection stretch blow molding is possible, but the preform obtained by injection molding has a few voids, and the transparency (visual observation) of the molded product after stretch blow molding is translucent.

[Comparative Example 3]
A molded article was produced and evaluated in the same manner as in Example 1, except that the polypropylene composition A-5 for comparison was used instead of the polypropylene composition A-1. Injection stretch blow molding was possible, but the molding was opaque.

[Comparative Example 4]
A molded article was produced and evaluated in the same manner as in Example 3, except that the ratio of polypropylene composition A-1 and polypropylene composition B-1 was changed as shown in Table 2. Injection stretch blow molding is possible, but the cold impact resistance, especially bottle drop resistance, is poor.

[Comparative Example 5]
A molded article was produced and evaluated in the same manner as in Example 1, except that the polypropylene composition B-2 was used instead of the polypropylene composition A-1. These results are shown in Table 2. Many voids occurred in the preform obtained by injection molding, and bursting occurred in the stretch blow molding, so the physical properties of the bottle could not be evaluated.

[Measurement condition]
1) MFR
MFR was measured in accordance with JIS K7210-1 under conditions of a temperature of 230° C. and a load of 2.16 kg.

2) The amount of ethylene-derived units in component (1) and the amount of ethylene-derived units in component (2) (1-butene-derived unit amount)
A sample dissolved in a mixed solvent of 1,2,4-trichlorobenzene/deuterated benzene was measured by ¹³ C-NMR method using JNM LA-400 ( ¹³ C resonance frequency 100 MHz) manufactured by JEOL Ltd.

3) Intrinsic viscosity (XSIV) of xylene solubles in polypropylene composition
A xylene-soluble component of the polypropylene composition was obtained by the following method, and the intrinsic viscosity (XSIV) of the xylene-soluble component was measured.
A 2.5 g sample of polypropylene was placed in a flask containing 250 mL of o-xylene (solvent) and stirred using a hot plate and reflux apparatus at 135° C. for 30 minutes with a nitrogen purge to completely dissolve the composition. After dissolving, it was cooled at 25° C. for 1 hour. The resulting solution was filtered using filter paper. 100 mL of the filtrate after filtration was collected, transferred to an aluminum cup or the like, evaporated to dryness at 140° C. while purging with nitrogen, and allowed to stand at room temperature for 30 minutes to obtain xylene solubles.
The intrinsic viscosity was measured in tetrahydronaphthalene at 135° C. using an automatic capillary viscometer (SS-780-H1, manufactured by Shibayama Scientific Instruments Co., Ltd.).

4) Flexural modulus According to JIS K6921-2, using an injection molding machine (FANUC ROBOSHOT S2000i manufactured by FANUC CORPORATION), the molten resin temperature is 200 ° C., the mold temperature is 40 ° C., the average injection speed is 200 mm / sec, and the pressure holding time is 40. Seconds, a total cycle time of 60 seconds, a multi-purpose test piece (type A1) specified in JIS K7139 is injection molded from the polypropylene composition, processed into a width of 10 mm, a thickness of 4 mm, and a length of 80 mm for the measurement test. A piece (type B2) was obtained. Using a precision universal testing machine manufactured by Shimadzu Corporation (Autograph AG-X 10 kN), a temperature of 23 ° C., a relative humidity of 50%, a distance between fulcrums of 64 mm, and a test speed of 2 mm / min. The flexural modulus was measured as an index of the rigidity of the molded article obtained from the polypropylene composition.

5) Charpy impact strength Measured according to JIS K6921-2, using a type A1 test piece obtained in the same manner as the test piece used in the flexural modulus measurement. That is, according to JIS K7111-1, a notching tool A-4 manufactured by Toyo Seiki Seisakusho Co., Ltd. is used to process a width of 10 mm, a thickness of 4 mm, and a length of 80 mm, and then a notch of 2 mm is inserted in the width direction. A specimen was obtained. For the measurement test piece, using a fully automatic impact tester with a low temperature chamber (No. 258-ZA) manufactured by Yasuda Seiki Seisakusho Co., Ltd., the Charpy impact strength (edgewise impact , 1eA method) was used as an index of the cold impact resistance of the molded article obtained from the polypropylene composition.

6) Formability Evaluation was made visually according to the following criteria.
Injection (preform)
a: Can be molded without problems b: Slight voids generated c: NG due to voids generated
blow (bottle)
a: Can be molded without problems c: Cannot be stretched (ruptures)

7) Transparency (Visual)
The transparency of the bottles was visually evaluated according to the following criteria.
a: transparent b: translucent c: opaque

8) Transparency (bottle haze)
The haze (%) was measured according to JIS K7136 at four points in the circumferential direction of the bottle side, and the average value was obtained. In the present invention, it is preferably 30% or less, more preferably 24% or less.

9) Bottle drop resistance (5°C/1.5m)
A 500 ml cylindrical bottle was filled with water adjusted to 5°C. The bottom of the bottle was dropped onto a concrete floor from a height of 1.5 m. One bottle was repeatedly dropped, and the number of drops required until cracking occurred (number of drops with cracking) was determined. In each example, five bottles were subjected to the same test, and the average value of the number of times cracks occurred and dropped was obtained as an index of the cold impact resistance of the injection stretch blow molded article. Ten times or more is preferable in the present invention.

Claims (8)

(I) a propylene-ethylene copolymer containing 1.5 to 2.5% by weight of ethylene-derived units as component (1);
A polypropylene composition A comprising, as component (2), an ethylene-1-butene copolymer containing 14 to 18% by weight of 1-butene-derived units, and a nucleating agent,
Requirements for:
1) The weight ratio of component (1) and component (2) is 75-83:25-17 2) The intrinsic viscosity of the xylene-soluble portion of the composition is 0.8-1.2 dl/g 3 ) A step of preparing a polypropylene composition A that satisfies the MFR (230 ° C., load 2.16 kg) of 15 to 40 g / 10 minutes,
(II) comprising a step of injection stretch blow molding the polypropylene composition A;
A method for producing an injection stretch blow molded article. Prior to step (II), a polypropylene composition B containing a polymer selected from the group consisting of propylene homopolymers, propylene random copolymers, and combinations thereof is prepared and mixed with polypropylene composition A to form a mixture further comprising a step (I') of preparing
In step (II), injection stretch blow molding the mixture;
The manufacturing method according to claim 1. The production method according to claim 2, wherein the weight ratio of polypropylene composition A and polypropylene composition B is "40 or more and less than 100": "greater than 0 to 60 or less". The production method according to any one of claims 1 to 3, wherein the nucleating agent is contained in an amount of 0.01 to 0.5 parts by weight with respect to a total of 100 parts by weight of components (1) and (2). The manufacturing method according to any one of claims 2 to 4, wherein the polypropylene composition B contains 0.01 to 0.5 parts by weight of a nucleating agent with respect to a total of 100 parts by weight of the polymer according to claim 2. The production method according to any one of claims 1 to 5, wherein the MFR is 20 to 40 g/10 minutes. An injection stretch blow molded article obtained by the manufacturing method according to any one of claims 1 to 6 . A container comprising the molded article according to claim 7 .