JP2020090597A - Injection stretch blow molded body of polypropylene composition and manufacturing method therefor - Google Patents

Abstract

To provide an injection stretch blow molded body of a propylene composition excellent in balance of transparency, rigidity and low temperature impact resistance.SOLUTION: There is provided a manufacturing method of an injection stretch blow molded body, having (I) a process for preparing a polypropylene composition A containing a propylene-ethylene copolymer containing 1.5 to 2.5 wt.% of an ethylene-derived unit as a component (1), an ethylene-1-butene copolymer containing 14 to 18 wt.% of a 1-butene derived unit as a component (2), and a nucleus agent, and satisfying following requirements: 1) a weight ratio of the component (1) and the component (2) is 75 to 83:25 to 17, 2) intrinsic viscosity of a xylene soluble component of the composition is 0.8 to 1.2 dl/g, and 3) MFR (230°C, load 2.16 kg) of the composition is 15 to 40 g/10 min., and (II) a process for injection stretch blow molding the polypropylene composition A.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to an injection stretch blow-molded product 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 hygiene. However, the polypropylene container has a problem that its impact resistance decreases when it is used at a low temperature. Further, the polypropylene container is required to have high rigidity and transparency so that the contents can be confirmed, that is, a balance between transparency, rigidity, and impact resistance at low temperature (cold impact resistance) is required. For the purpose of improving transparency and cold shock resistance, Patent Document 1 discloses that ethylene units having an ethylene unit of 74 to 86% by weight are present in the presence of an ethylene-propylene copolymer having an ethylene unit of 2.0 to 4.0% by weight. A composition obtained by polymerizing a -1-butene copolymer, in which the content of the ethylene-1-butene copolymer is 10 to 20% by weight, has been proposed. Further, in Patent Document 2, an ethylene-1-butene copolymer having an ethylene unit of 74 to 86% by weight is polymerized in the presence of an ethylene-propylene copolymer having an ethylene unit of 1.2% by weight or less or a homopolypropylene. A composition having an ethylene-1-butene copolymer content of 22 to 32% by weight has been proposed. Further, in Patent Document 3, for the purpose of improving cold shock resistance, in the presence of an ethylene-propylene copolymer having an ethylene unit of 2.0 to 4.0% by weight, the ethylene unit is 74 to 86% by weight. A composition in which the ethylene-1-butene copolymer is polymerized, wherein the content of the ethylene-1-butene copolymer is 25 to 35% by weight has been proposed.

JP2012-126829A JP 2012-107136A JP2012-126828A JP, 10-168254, A

However, the compositions described in the above patent documents still have insufficient balance between transparency, rigidity and cold impact resistance. Although an injection stretch blow-molded body is used in a container or the like, the above-mentioned patent document does not refer to the injection stretch blow-molded body. Regarding the injection stretch blow-molded article, Patent Document 4 proposes a polypropylene composition containing a linear low-density polyethylene or an ethylene/1-butene copolymer, but at a sufficient level of balance between rigidity and cold shock resistance. Absent. Further, the production of the composition requires the provision of an intermediate step of blending a plurality of polymer components and melt-kneading, which is not necessarily suitable for implementation on an industrial scale. In view of such circumstances, it is an object of the present invention to provide an injection stretch blow-molded product of a polypropylene composition, which has an excellent balance of transparency, rigidity and cold shock resistance.

The inventors have found that the above problems can be solved by using a specific polypropylene composition. That is, the said subject is solved by the following this invention.
[1] A propylene-ethylene copolymer containing 1.5 to 2.5 wt% of an ethylene-derived unit as the component (1) (1),
A polypropylene composition A comprising an ethylene-1-butene copolymer containing 14 to 18% by weight of a 1-butene-derived unit as a component (2), and a nucleating agent,
The following requirements:
1) The weight ratio of the component (1) to the component (2) is 75 to 83:25 to 17 2) The xylene-soluble component of the composition has an intrinsic viscosity of 0.8 to 1.2 dl/g 3 ) A step of preparing a polypropylene composition A satisfying the condition that the MFR (230° C., load 2.16 kg) of the composition is 15 to 40 g/10 minutes,
(II) comprises a step of injection stretch blow molding the polypropylene composition A,
A method for producing an injection stretch blow molded product.
[2] Prior to the step (II), a polypropylene composition B containing a polymer selected from the group consisting of a propylene homopolymer, a propylene random copolymer, and a combination thereof is prepared and mixed with the polypropylene composition A. Further comprising the step (I′) of preparing a mixture by
The production method according to [1], wherein in the step (II), the mixture is injection stretch blow molded.
[3] The production method according to [2], wherein the weight ratio of the polypropylene composition A and the 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 the component (1) and the component (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 100 parts by weight of the polymer described in [2] above. The production method described in Crab.
[6] An injection stretch blow-molded article obtained by the production method according to any one of [1] to [5] above.
[7] A container containing the molded product according to [6].

According to the present invention, it is possible to provide an injection stretch blow-molded product of a polypropylene composition having an excellent balance of transparency, rigidity and cold shock resistance.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail. “X to Y” includes the extreme values X and Y.
1. Process I
(1) Polypropylene composition A
In this step, the polypropylene composition A is prepared. The 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)
The component (1) is a propylene-ethylene copolymer and contains 1.5 to 2.5% by weight of an ethylene-derived unit. 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 and propylene-derived units is 1.5:98.5. The same applies to other copolymers. The upper limit of the content of the ethylene-derived unit is 2.5% by weight or less, preferably 2.3% by weight or less. If the amount exceeds the upper limit value, the rigidity and the transparency decrease. The lower limit of the ethylene-derived unit is 1.5% by weight or more, but 1.7% by weight or more is preferable. When the amount is less than the lower limit value, the transparency is lowered. The component (1) may contain less than 1% by weight of 1-butene units due to a recycled gas generated during the production of the polymer containing the component (2). Component (1) is preferably a random copolymer.

2) Component (2)
Component (2) is an ethylene-1-butene copolymer and contains 14 to 18% by weight of 1-butene-derived units. The upper limit of the content of the unit derived from 1-butene 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 unit derived from 1-butene is 14% by weight or more, preferably 15% by weight or more. If the amount is less than the lower limit value, the cold shock resistance decreases. The component (2) may contain less than 1% by weight of a propylene-derived unit due to a recycled gas generated during the production of the polymer containing the component (1).

3) Composition ratio The composition ratio (weight ratio) of the component (1) and the component (2) is 75 to 83:25 to 17, but 76 to 80:24 to 20 is preferable. If the amount of the component (1) exceeds the upper limit value, the cold shock resistance decreases. When the amount of the component (1) is less than the lower limit value, the rigidity is lowered, and the polymerized powders are easily adhered to each other to increase the risk of blockage in the storage or transportation route, which makes the production of the polypropylene composition A difficult. Tend to be.

4) Nucleating agent Polypropylene composition A contains a nucleating agent. The nucleating agent is an additive (transparent nucleating agent) used for controlling the size of the crystal component in the resin to be small and particularly improving the transparency. The amount of the nucleating agent is preferably 0.01 to 0.5 parts by weight, more preferably 0.01 to 0.5 parts by weight based on 100 parts by weight of the total amount of the components (1) and (2) (hereinafter also referred to as “resin component”). To 0.4 parts by weight, and more preferably 0.015 to 0.4 parts by weight. If no nucleating agent is used, satisfactory transparency and cold impact resistance cannot be obtained. Even if the nucleating agent is contained in excess of the above upper limit, the effect of promoting the formation of crystal nuclei reaches a ceiling and the manufacturing cost simply increases, which is not realistic in the case of industrial mass production at low cost.

The nucleating agent is not particularly limited, and those commonly used in the art may be used, but nonitol nucleating agents, sorbitol nucleating agents, phosphoric acid ester nucleating agents, triaminobenzene derivative nucleating agents, carboxylic acids. It is preferably selected from metal salt nucleating agents and organic nucleating agents such as xylitol nucleating agents. Examples of the nonitol-based nucleating agent include 1,2,3-trideoxy-4,6:5,7-bis-[(4-propylphenyl)methylene]-nonitol. Examples of the sorbitol-based nucleating agent include 1,3:2,4-bis-o-(3,4-dimethylbenzylidene)-D-sorbitol. Examples of the phosphoric acid ester-based nucleating agent include phosphoric acid 2,2′-methylenebis(4,6-di-t-butylphenyl) sodium salt and phosphoric acid-2,2′-methylenebis(4,6-di-tert). Aromatic phosphate ester nucleating agents such as -butylphenyl)aluminum salt and phosphoric acid-2,2'-methylenebis(4,6-di-tert-butylphenyl)lithium salt. Examples of the triaminobenzene derivative-based nucleating agent include 1,3,5-tris(2,2-dimethylpropanamide)benzene and the like. Examples of the carboxylic acid metal salt nucleating agent include sodium adipate, potassium adipate, aluminum adipate, sodium sebacate, potassium sebacate, aluminum sebacate, sodium benzoate, aluminum benzoate, di-para-t-butyl. Aluminum benzoate, titanium di-para-t-butyl benzoate, chromium di-para-t-butyl benzoate, aluminum hydroxy-di-t-butyl benzoate and the like can be mentioned. Examples of the xylitol-based nucleating agent include bis-1,3:2,4-(5′,6′,7′,8′-tetrahydro-2-naphthaldehydebenzylidene)1-allylxylitol and bis-1,3: 2,4-(3′,4′-dimethylbenzylidene) 1-propylxylitol can be mentioned. The nucleating agents may be used alone 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. At this time, if necessary, a resin other than the above resin components (excluding the polypropylene composition B) or rubber, or an additive described below may be further mixed. The order of adding the components is not limited. The mixing method is not limited, and examples thereof include a method using a mixer such as a Henschel mixer and a tumbler mixer. After mixing, the obtained mixture may be melt-kneaded and further pelletized. As the melt-kneading device, a single screw extruder, a twin screw extruder, a Banbury mixer, a kneader, a roll mill or the like can be used.

5) Characteristics XSIV
The intrinsic viscosity (XSIV) of the xylene-soluble component of the polypropylene composition A is an index of the molecular weight of the component having no crystallinity 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 standard method. In the present invention, XSIV is 0.8 to 1.2 dl/g. When XSIV exceeds the upper limit, the transparency decreases, and when it is less than the lower limit, it becomes difficult to produce a polypropylene composition. From this viewpoint, the intrinsic viscosity is preferably 0.9 to 1.1 dl/g.

MFR
The MFR of the polypropylene composition A at 230° C. and a load of 2.16 kg is 15 to 40 g/10 minutes. If the MFR exceeds the upper limit, the cold shock resistance and the transparency will decrease, and if it is less than the lower limit, molding will be difficult. From this viewpoint, the MFR is preferably 20 to 40 g/10 minutes, more preferably 20 to 35 g/10 minutes.

6) Other components The polypropylene composition A includes an antioxidant, a chlorine absorber, a heat resistance stabilizer, a light stabilizer, an ultraviolet absorber, an internal lubricant, an external lubricant, an antiblocking agent, an antistatic agent, an antifogging agent, Conventional additives commonly used in the art, such as flame retardants, dispersants, copper damage inhibitors, neutralizers, plasticizers, defoamers, crosslinkers, peroxides, oil extensions and other organic and inorganic pigments. May be added. The addition amount of each additive may be a known amount. The polypropylene composition A may contain one or more resins (excluding the polypropylene composition B) or rubbers other than the above resin components as long as the effects of the present invention are not impaired.

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

A polymerization vessel having a gradient of monomer concentration or polymerization conditions may be used. In such a polymerization vessel, for example, one in which at least two polymerization regions are connected is used, and the monomer can be polymerized 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, and a downcomer connected to the ascending pipe is supplied with a monomer to polymerize the ascending pipe and the descending pipe. The polymer product is recovered while circulating. The method comprises means for totally or partially preventing the gas mixture present in the riser from entering the downcomer. Also, a gas or liquid mixture having a different composition than the gas mixture present in the riser is introduced into the downcomer. As the above-mentioned polymerization method, for example, the method described in Japanese Patent Publication No. 2002-520426 can be applied.

For the polymerization, a solid catalyst containing (A) magnesium, titanium, halogen, and an electron donor compound, a (B) organoaluminum compound, and (C) a Ziegler-Natta catalyst containing an external electron donor compound, and a metallocene catalyst are used. Can be used. Examples of the electron donor compound (also referred to as “internal electron donor compound”) in the component (A) include a phthalate compound, a succinate compound, and a diether compound. In the present invention, any internal electron donor compound is used. They can be used, and if necessary, those compounds may be used in combination.

2. Process (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 a propylene homopolymer, a propylene random copolymer, and a combination thereof, and mixing with the polypropylene composition A. May be.
(1) Polypropylene composition B
Known polymers can be used as the polypropylene composition B, but it is preferable that the MFR of the polypropylene composition B is selected to be in the same range as the polypropylene composition A.

The comonomer unit amount in the propylene random copolymer is preferably 5.0% by weight or less, more preferably 4.0% by weight or less. When the amount of the comonomer exceeds the upper limit value, the stability in producing the polypropylene composition B may decrease. Ethylene is preferable as the comonomer from the viewpoints of being industrially inexpensive, stably distributed, and relatively easily available.

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

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

3. Process (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 stretching ratio (axial stretching ratio) during stretch blow molding (biaxial stretching) is usually 1.5 times or more, preferably 1.6 to 5 times, and the transverse stretching ratio (circumferential stretching 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, problems may occur in transparency and buckling strength. The longitudinal/transverse stretching ratio is preferably 0.2 to 5 times, more preferably 0.3 to 3 times. The cylinder temperature, the mold temperature, and the temperature during biaxial stretching can be appropriately adjusted according to the characteristics 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 An injection stretch blow-molded article can be produced according to the present invention. The molded product is a food bottle container such as a beverage bottle container, a confectionery bottle container, a fruit juice container, and a mineral water container; a bottle container for toiletry solutions such as shampoo, rinse, and liquid soap; acidic, neutral, and alkaline household detergents. Detergent bottle containers such as; Liquid cosmetic bottle containers; Chemical containers such as alcohol and industrial chemicals; Medical containers such as infusion bottles and blood bottles; Leisure bottle containers; Stationery bottle containers; Toy bottle containers; Other general miscellaneous goods It is useful for applications. In particular, the injection stretch blow-molded product of the present invention is useful as a food container, particularly as a container used in a low temperature state such as -20°C. The container may have members other than the polypropylene composition. The shape of the container may be known, but it is preferable that the container 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/m ² or more

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

The polymerization temperature and the ratio of the reactants are such that the polymerization temperature, hydrogen concentration and ethylene concentration in the first stage reactor are 70° C., 0.80 mol% and 0.53 mol %, respectively, and in the second stage reactor, Polymerization temperature, H2/C2, C4/(C2+C4) were 80° C., 0.30 molar ratio and 0.35 molar ratio, respectively. Further, the residence time distributions in the first and second stages were adjusted so that the amount of the component (2) was 22% by weight. Based on 100 parts by weight of the obtained resin component, 0.02 part by weight of IRGACLEAR XT386 (triaminobenzene derivative-based nucleating agent) manufactured by BASF as a nucleating agent and 0.2 part by weight of B225 manufactured by BASF as an antioxidant. Parts, 0.05 part by weight of calcium stearate manufactured by Tanan Chemical Industry 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 Machinery Co., Ltd., and the strand was cooled in water and then cut with a pelletizer to obtain a polypropylene composition A-1 in pellet form. The composition was evaluated by the method described below. The results are shown in Table 1.

[Production Example 2: Polypropylene composition A-2]
Manufactured except that 0.02 parts by weight of IRGACLEAR XT386 (triaminobenzene derivative-based nucleating agent) manufactured by BASF and 0.2 part by weight of Millad NX8000J (nonitol-based nucleating agent) manufactured by Milliken were used as the nucleating agent. A 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 was not fed and the hydrogen concentration was changed to 0.95 mol% to polymerize the propylene homopolymer. In the second-stage reactor, H2/C2 and C4/(C2+C4 ) Are changed to 0.27 mol ratio and 0.41 mol ratio, respectively, and the residence time distributions in the first and second stages are adjusted so that the amount of the ethylene-1-butene copolymer is 23% by weight. Comparative polypropylene composition A-3 was produced in the same manner as in Production Example 1 except that the above was performed.

[Production Example 4: Comparative polypropylene composition A-4]
Change the hydrogen concentration and ethylene concentration of the first stage reactor to 0.84 mol% and 0.84 mol% respectively, and change the C4/(C2+C4) of the second stage reactor to 0.41 mol ratio. Along with the resin component obtained by adjusting the residence time distribution in the first and second stages so that the amount of the ethylene-1-butene copolymer was 31% by weight, BASF Corporation IRGACLEAR XT386 (triamino 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 in which Ti and diisobutyl phthalate as an internal donor were supported on MgCl ₂ was prepared by the method described in paragraphs 213 to 21 to 36 of JP2004-27218A. 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 the solid catalyst is 20, and the weight ratio of TEAL to DCPMS is In an amount of 10 to bring them into contact with each other at 12° C. for 24 minutes to obtain a catalyst. Preliminary polymerization was carried out by keeping the obtained catalyst in suspension in liquid propylene at 20° C. for 5 minutes to obtain a prepolymerized product. The obtained prepolymerized product was introduced into the first-stage polymerization reactor of a polymerization apparatus equipped with a two-stage polymerization reactor in series, and propylene in a liquid phase was fed to obtain a propylene homopolymer as component (1). Was produced, and an ethylene-propylene copolymer as the component (2) was produced in the second stage gas phase polymerization reactor. During the polymerization, temperature and pressure were adjusted and hydrogen was used as a molecular weight modifier. The polymerization temperature and the ratio of the reactants are as follows: the polymerization temperature and the hydrogen concentration in the first-stage polymerization reactor are 70° C. and 1.11 mol %, respectively, and the polymerization temperature, the hydrogen concentration and C2/ (C2+C3) was 80° C., 2.45 mol% and 0.49 mol ratio, respectively. Further, the residence time distributions of the first and second stages were adjusted so that the amount of the component (2) was 19% by weight. Comparative polypropylene composition A-5 was produced in the same manner as in Production Example 4 using the obtained resin component.

[Production Example 6: Polypropylene composition B-1]
The solid catalyst used for the 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, triethylaluminum (TEAL), and dicyclopentyldimethoxysilane (DCPMS) were added in an amount such that the weight ratio of TEAL to the solid catalyst was 11, and the weight ratio of TEAL/DCPMS was 10, at 5° C. Contacted for minutes. Prepolymerization was carried out by keeping the resulting catalyst system in suspension in liquid propylene for 5 minutes at 20°C. After introducing the obtained prepolymerized product into a polymerization reactor, hydrogen, propylene, and ethylene were fed to set the polymerization temperature, hydrogen concentration, and ethylene concentration to 75° C., 0.97 mol%, and 0.80 mol%, respectively. By adjusting the pressure, a propylene-ethylene random copolymer containing 3.0 wt% of ethylene-derived units and having an MFR of 25 g/10 min was produced. Polypropylene composition B-1 in the same manner as in Production Example 1 except that 0.2 part by weight of Millad 3988 (sorbitol-based nucleating agent) manufactured by Milliken was used as a nucleating agent based on 100 parts by weight of the obtained resin component. Was 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. As a nucleating agent, a polypropylene composition was prepared in the same manner as in Production Example 6 except that 0.2 part by weight of Millad NX8000J (nonitol-based nucleating agent) was used as the nucleating agent instead of Millad 3988 (sorbitol-based nucleating agent) manufactured by Milliken. The product B-2 was manufactured.

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

The preform was stretch blow molded under the following conditions to form a 500 mL cylindrical bottle (container) having an average wall thickness of 0.5 mm.
Stretch Blow Molding Machine: Kamei Machinery Co., Ltd. Cold parison method Preform temperature (℃): 94
Blow pressure (kg/cm ² ): 7
Blow time (sec): 3.5
Longitudinal draw ratio: 1.9
Lateral stretch ratio: 2.0

The polypropylene composition and these molded products were evaluated by the methods described below. The results are shown in Table 2. The polypropylene composition of Example 1 was excellent in moldability in injection stretch blow molding, and the resulting molded product had a good balance of transparency, rigidity and cold shock resistance.

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

[Example 3]
The polypropylene composition A-1 and the 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. The composition was injection molded under the above conditions to produce a preform. Stretch blow molding was performed from the obtained preform in the same manner as in Example 1 to produce a bottle, which was evaluated. In addition to being excellent in moldability in injection stretch blow molding, the resulting molded article had a good balance of transparency, rigidity and cold shock resistance.

[Example 4]
A molded product 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. In addition to being excellent in moldability in injection stretch blow molding, the resulting molded article had a good balance of transparency, rigidity and cold shock resistance.

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

[Comparative example 2]
A molded body was produced and evaluated in the same manner as in Example 4 except that the polypropylene composition for comparison A-4 was used instead of the polypropylene composition A-1 as shown in Table 2. Although injection stretch blow molding is possible, slight voids were generated in the preform obtained by injection molding, and it was translucent in the transparency (visual) evaluation of the molded product after stretch blow molding.

[Comparative Example 3]
A molded product was produced and evaluated in the same manner as in Example 1 except that the comparative polypropylene composition A-5 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 product was produced and evaluated in the same manner as in Example 3 except that the ratios of the polypropylene composition A-1 and the polypropylene composition B-1 were changed as shown in Table 2. Injection stretch blow molding was possible, but bottle drop resistance was particularly poor as cold impact resistance.

[Comparative Example 5]
A molded product 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. The results are shown in Table 2. Many voids were generated in the preform obtained by injection molding, and rupture occurred by stretch blow molding, and the physical properties of the bottle could not be evaluated.

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

2) Amount of ethylene-derived units in component (1) and 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-soluble component of polypropylene composition
The xylene-soluble matter of the polypropylene composition was obtained by the following method, and the intrinsic viscosity (XSIV) of the xylene-soluble matter was measured.
A polypropylene sample (2.5 g) was placed in a flask containing 250 mL of o-xylene (solvent), and the mixture was stirred for 30 minutes at 135° C. using a hot plate and a reflux device while performing a nitrogen purge to complete the composition. After dissolution, it was cooled at 25° C. for 1 hour. The solution thus obtained 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 a xylene-soluble component.
The intrinsic viscosity was measured in tetrahydronaphthalene at 135° C. by using a capillary automatic viscosity measuring device (SS-780-H1, manufactured by Shibayama Scientific Instruments Co., Ltd.).

4) Bending elastic 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 holding time is 40. Seconds, total cycle time of 60 seconds, injection molding a multipurpose test piece (type A1) specified in JIS K7139 from polypropylene composition, processing to width 10 mm, thickness 4 mm, length 80 mm, and measurement test A piece (type B2) was obtained. Using a precision universal tester (Autograph AG-X 10kN) manufactured by Shimadzu Corporation, under the conditions of temperature 23° C., relative humidity 50%, distance between fulcrums 64 mm, and test speed 2 mm/min. The flexural modulus was measured and used as an index of the rigidity of the molded product obtained from the polypropylene composition.

5) Charpy impact strength According to JIS K6921-2, it was measured using a type A1 test piece obtained by the same operation as the test piece used in the flexural modulus measurement. That is, according to JIS K7111-1, using a notching tool A-4 manufactured by Toyo Seiki Seisaku-sho, Ltd., a width of 10 mm, a thickness of 4 mm, and a length of 80 mm are processed, and then a notch of 2 mm is inserted in the width direction to measure the shape A A test piece was obtained. About the test piece for measurement, using a fully automatic impact tester with a low temperature tank (No. 258-ZA) manufactured by Yasuda Seiki Co., Ltd., Charpy impact strength (edgewise impact) under the conditions of temperature 0° C. and relative humidity 50%. 1eA method) was used as an index of cold impact resistance of a molded article obtained from the polypropylene composition.

6) Moldability Visual evaluation was performed according to the following criteria.
Injection (preform)
a: Can be molded without problems b: Slight voids are generated c: Voids are generated NG
Blow (bottle)
a: Can be molded without problems c: Not stretchable (explodes)

7) Transparency (visual inspection)
The transparency of the bottle 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 locations on the side surface of the bottle in the circumferential direction, 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℃/1.5m)
A 500 ml cylindrical bottle was fully filled with water adjusted to 5°C. From a height of 1.5 m, it was dropped onto the concrete floor from the bottom of the bottle. One bottle was repeatedly dropped, and the number of drops required until cracking occurred (the number of cracked drops) was determined. In each example, the same test was carried out on 5 bottles, and the average value of the number of crack-generated drops obtained was determined as an index of cold impact resistance as an injection stretch blow-molded article. In the present invention, 10 times or more is preferable.

Claims (7)

(I) A propylene-ethylene copolymer containing 1.5 to 2.5% by weight of an ethylene-derived unit as the component (1),
A polypropylene composition A comprising an ethylene-1-butene copolymer containing 14 to 18% by weight of a 1-butene-derived unit as a component (2), and a nucleating agent,
The following requirements:
1) The weight ratio of the component (1) to the component (2) is 75 to 83:25 to 17 2) The xylene-soluble component of the composition has an intrinsic viscosity of 0.8 to 1.2 dl/g 3 ) A step of preparing a polypropylene composition A satisfying the condition that the MFR (230° C., load 2.16 kg) of the composition is 15 to 40 g/10 minutes,
(II) comprises a step of injection stretch blow molding the polypropylene composition A,
A method for producing an injection stretch blow molded product. Prior to step (II), a polypropylene composition B comprising 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
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 the polypropylene composition A and the polypropylene composition B is “40 or more and less than 100”: “more than 0 to 60 or less”. The manufacturing method in any one of Claims 1-3 containing 0.01-0.5 weight part nucleating agent with respect to 100 weight part in total of a component (1) and a component (2). The production method according to any one of claims 2 to 4, wherein the polypropylene composition B contains 0.01 to 0.5 part by weight of a nucleating agent based on 100 parts by weight of the polymer according to claim 2. An injection stretch blow-molded article obtained by the production method according to claim 1. A container comprising the molded body according to claim 6.