JP2019031314A - Hollow container and its manufacturing method, and polypropylene resin composition for blow fill seal - Google Patents

Abstract

To suppress occurrence of defects on hollow molded bodies regarding hollow containers having hollow molded bodies of a polypropylene resin composition.SOLUTION: A hollow container including a hollow molded body of a polypropylene resin composition is disclosed. The polypropylene resin composition includes crystalline propylene polymers A1 and A2, ethylene-α- olefin copolymer and a nucleus agent. The crystalline propylene polymer A1 is copolymer of which the content of the monomer unit derived from co-monomer is 2 to 8% by mass, and the crystalline propylene polymer A2 is homo-polymer of which the content of the monomer unit derived from co-monomer is 0 to 1% by mass and crystal melting peak temperature is at least 150°C. The density of the ethylene-α-olefin copolymer is 865-920 kg/m.SELECTED DRAWING: None

Description

  The present invention relates to a hollow container, a method for producing the same, and a polypropylene resin composition for blow fill sealing.

  As a food container or a medical container, a hollow container having a layer made of a polypropylene resin composition is known (Patent Document 1).

JP 2006-225536 A

  When forming a hollow molded body, the formed molded body may need to be solidified in an extremely short time. For example, a hollow molded body having a mouth part is formed in a mold by direct blow molding, and then liquid is sealed by a blow fill sealing method in which the hollow product is filled with a liquid product in the mold and then the mouth part is sealed. When manufacturing a container, since the liquid product is immediately filled in the hollow molded body formed in the mold, it is necessary to solidify the hollow molded body in a very short time. When a hollow molded body of a polypropylene resin composition is formed by a molding method that requires such a molded body to solidify in a short time, a hollow molded body having a target shape can be formed with high accuracy. It became clear that there was a difficult tendency.

  Therefore, an object of one aspect of the present invention is to suppress the occurrence of defects in a hollow molded body with respect to a hollow container having a hollow molded body of a polypropylene resin composition.

One aspect of the present invention relates to a hollow container including a hollow molded body of a polypropylene resin composition. The polypropylene resin composition is
(A1) a crystalline propylene polymer A1 containing a monomer unit derived from propylene;
(A2) a crystalline propylene polymer A2 containing a monomer unit derived from propylene;
(B) an ethylene-α-olefin copolymer;
(C) a nucleating agent;
Containing.
The crystalline propylene polymer A1 is a copolymer in which the content of monomer units derived from comonomers other than propylene is 2 to 8% by mass based on the mass of the crystalline propylene polymer A1.
In the crystalline propylene polymer A2, the content of monomer units derived from comonomers other than propylene is 0 to 1% by mass based on the mass of the crystalline propylene polymer A2, and 50 to 180 ° C. in differential scanning calorimetry. It is a homopolymer or copolymer having a maximum crystal melting peak temperature of 150 ° C. or higher observed in the range.
The comonomer in the crystalline propylene polymer A1 and the crystalline propylene polymer A2 is at least one olefin of ethylene and α-olefin.
The density of the ethylene-α-olefin copolymer is 865 to 920 kg / m ³ .
Based on the total amount of the crystalline propylene polymer A1, the crystalline propylene polymer A2 and the ethylene-α-olefin copolymer, the content of the crystalline propylene polymer A1 is 35 to 93% by mass, The content of the crystalline propylene polymer A2 is 1 to 35% by mass, and the content of the ethylene-α-olefin copolymer is 5 to 30% by mass.
The half crystallization time of the polypropylene resin composition measured at 115 ° C. is 70 seconds or less.

  The hollow container according to one aspect of the present invention is manufactured while suppressing defects in shape even by a molding method such as a blow fill seal method in which the formed body needs to be solidified in a short time. be able to.

  Another aspect of the present invention is a sealed container comprising the hollow container and a liquid product accommodated in the hollow container, the sealed container having a mouth portion in which the hollow molded body is sealed. The liquid product is sealed with the liquid product. Since this liquid enclosure has a hollow molded body of a polypropylene resin composition, it can be efficiently produced by the blow-fill seal method while suppressing shape defects.

  Still another aspect of the present invention is that a polypropylene resin composition is molded by direct blow molding to form a hollow molded body having a mouth portion in a mold, and the hollow molded body is filled with a liquid product in the mold. In addition, the present invention relates to a method for manufacturing a liquid-sealed container, which includes a step of forming the liquid-sealed container by a blow fill sealing method that seals a mouth portion. According to this method, the liquid enclosure can be efficiently manufactured while suppressing defects in the shape of the hollow molded body.

  Yet another aspect of the present invention relates to a polypropylene resin composition for blow fill sealing, which is used for forming the liquid-sealed container by a blow fill sealing method. The polypropylene resin composition here is the same as described above.

  According to the present invention, with respect to a hollow container having a hollow molded body of a polypropylene resin composition, which is formed by a molding method that requires the molded body to solidify in a short time, the occurrence of defects in the hollow molded body is suppressed. can do. The hollow container according to the present invention is excellent in terms of transparency, flexibility, and low-temperature impact strength, and can also have high surface smoothness.

It is a graph which shows the example of the method of determining half crystallization time.

  Hereinafter, some embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

The hollow container which concerns on one Embodiment contains the hollow molded object of a polypropylene resin composition. This polypropylene resin composition
(A1) a crystalline propylene polymer A1 containing a monomer unit derived from propylene;
(A2) a crystalline propylene polymer A2 containing a monomer unit derived from propylene;
(B) an ethylene-α-olefin copolymer;
(C) a nucleating agent;
Containing.
The crystalline propylene polymer A1 is a copolymer in which the content of monomer units derived from comonomers other than propylene is 2 to 8% by mass based on the mass of the crystalline propylene polymer A1. The crystalline propylene polymer A2 is a homopolymer or copolymer in which the content of monomer units derived from comonomers other than propylene is 0 to 1% by mass based on the mass of the crystalline propylene polymer A2. It is. Portions other than the monomer units derived from the comonomers of the crystalline propylene polymers A1 and A2 are composed of monomer units derived from propylene.

  Here, in the present specification, the “crystalline propylene polymer” means a propylene polymer in which a peak of crystal melting with a calorific value of 20 J / g or more is observed in differential scanning calorimetry. The amount of heat of fusion of the crystalline propylene polymer A1 is usually 20 to 75 J / g, and may be 30 to 75 J / g from the viewpoint of the transparency, flexibility and impact strength of the hollow molded body. The heat of fusion of the crystalline propylene-based polymer A2 is usually 82 J / g or more, and may be 85 J / g or more, or 130 J / g or less from the viewpoint of the transparency of the hollow molded article after the heat treatment. It may be.

Unless otherwise specified, the differential scanning calorimetry referred to herein is the following (i), (ii), (iii), (iv), (v), (vi) and under nitrogen atmosphere: (Vii) in the order of applying thermal history to the test piece.
(I) Temperature rise from 24 ° C. to 220 ° C. at a rate of 300 ° C./min (ii) Hold at 220 for 5 minutes (iii) Temperature drop to 150 ° C. at a rate of 300 ° C./min (iv) Hold at 150 ° C. for 1 minute ( v) Temperature drop to 50 ° C. at a rate of 5 ° C./minute (vi) Hold at 50 ° C. for 1 minute (vii) Temperature rise to 180 ° C. at a rate of 5 ° C./minute (vii) From the crystal melting peak obtained from the step The maximum crystal melting peak temperature observed in the range of 50 to 180 ° C. and the heat of fusion (J / g) at the crystal melting peak showing the maximum crystal melting peak temperature are calculated. The maximum crystal melting peak temperature is usually considered the melting point of the polymer. The heat of fusion of a crystal is a value calculated from the area of a region surrounded by a line obtained by extending the base line on both sides of the crystal melting peak and the crystal melting peak.

  The comonomer other than propylene constituting the crystalline propylene polymer A1 or A2 is ethylene, α-olefin, or a combination thereof. The α-olefin may be, for example, at least one selected from the group consisting of butene-1, hexene-1, 4-methylpentene-1, and octene-1. The crystalline propylene polymer A1 and the crystalline propylene polymer A2 may have the same or different types of comonomer.

  The content of the monomer unit derived from the comonomer in the crystalline propylene polymer A1 is usually 2 to 8% by mass, 2 to 7% by mass, or 3 to 3, based on the mass of the crystalline propylene polymer A1. It may be 6% by mass.

  The crystalline propylene polymer A1 may be a propylene-ethylene copolymer, a propylene-ethylene-butene-1 copolymer, or a propylene-butene-1 copolymer.

  In the differential scanning calorimetry of the crystalline propylene polymer A1, the temperature of the maximum crystal melting peak observed in the range of 50 to 180 ° C. is 100 to 145 ° C., 110 to 145 ° C., or 120 to 140 ° C. Also good.

  The melt flow rate of the crystalline propylene polymer A1 may be 0.5 to 10 g / 10 minutes, 1.0 to 8 g / 10 minutes, or 1.0 to 6 g / 10 minutes. Here, the melt flow rate is a value measured under conditions of a temperature of 230 ° C. and a load of 2.16 kgf. When measuring the melt flow rate, a small amount of an antioxidant (for example, about 0.5 parts by mass with respect to 100 parts by mass of the crystalline propylene polymer) may be blended with the crystalline propylene polymer. Hereinafter, the melt flow rate measured under these conditions is expressed as MFR (230 ° C., 2.16 kgf).

  The crystalline propylene polymer A2 is a propylene homopolymer or a copolymer containing a very small amount of monomer units derived from a comonomer. The crystalline propylene polymer A2 contributes to speeding up the crystallization of the polypropylene resin composition together with the nucleating agent.

  The crystalline propylene polymer A2 may be a propylene homopolymer, a propylene-ethylene copolymer, a propylene-ethylene-butene-1 copolymer, or a propylene-butene-1 copolymer.

  In the differential scanning calorimetry of the crystalline propylene polymer A2, the maximum crystal melting peak temperature (peak top temperature) observed in the range of 50 to 180 ° C. is 150 ° C. or higher. When the crystal melting peak temperature of the crystalline propylene polymer A2 is lower than 150 ° C., the transparency of the hollow molded article after the heat treatment tends to be lowered. From the same viewpoint, the temperature of the crystalline melting peak of the crystalline propylene polymer A2 may be 155 ° C. or higher and 170 ° C. or lower.

  From the viewpoint of surface smoothness and transparency of the hollow molded article, the MFR (230 ° C., 2.16 kgf) of the crystalline propylene polymer A2 is 1 to 200 g / 10 minutes, 2 to 100 g / 10 minutes, or 3 to 3%. It may be 20 g / 10 minutes.

  The ethylene-α-olefin copolymer is a copolymer containing ethylene as a main monomer unit. The monomer unit derived from ethylene may be 50% by mass or more based on the mass of the ethylene-α-olefin copolymer, and from the viewpoint of flexibility and impact strength of the hollow molded body, 55% by mass or more, It may be 60% by mass or more, or 65% by mass or more.

  4-12 may be sufficient as carbon number of the alpha-olefin which comprises an ethylene-alpha-olefin copolymer. The α-olefin may be, for example, at least one selected from the group consisting of butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, and decene-1. From the viewpoint of low-temperature impact strength of the hollow molded body, the α-olefin may be butene-1, hexene-1, or a combination thereof.

The density of the ethylene-α-olefin copolymer is usually 865 to 920 kg / m ³ , and may be 868 to 910 kg / m ³ , or 870 to 900 kg / m ³ .

  The MFR (190 ° C., 2.16 kgf) of the ethylene-α-olefin copolymer is 0.1 to 50 g / 10 minutes, 0.5 to 40 g / 10 minutes, 1 to 30 g / 10 minutes, or 2 to 20 g. / 10 minutes may be sufficient.

  Based on the total amount of the crystalline propylene polymer A1, the crystalline propylene polymer A2 and the ethylene-α-olefin copolymer, the content of the crystalline propylene polymer A1 is 35 to 93% by mass, The content of the crystalline propylene polymer A2 is 1 to 35% by mass, and the content of the ethylene-α-olefin copolymer is 5 to 30% by mass. From the viewpoint of flexibility, transparency, impact strength at low temperature and transparency after heat treatment of the hollow molded body, the content of the crystalline propylene polymer A1 is 60 to 90% by mass, and the crystalline propylene polymer. The content of A2 may be 3 to 20% by mass, and the content of the ethylene-α-olefin copolymer may be 5 to 20% by mass. In order to particularly increase the crystallization speed of the polypropylene resin composition and to enable a faster molding cycle, the content of the crystalline propylene polymer A1 is 70 to 92% by mass, and the crystalline propylene polymer A2 is contained. The amount may be 3 to 18% by mass, the ethylene-α-olefin copolymer content may be 5 to 12% by mass, the content of the crystalline propylene polymer A1 is 74 to 90% by mass, The content of the crystalline propylene polymer A2 may be 4 to 15% by mass, and the content of the ethylene-α-olefin copolymer may be 6 to 11% by mass. When two or more kinds of the polypropylene resin composition are contained in the polypropylene resin composition with respect to the crystalline propylene polymer A1, the crystalline propylene polymer A2 and the ethylene-α-olefin copolymer, the total amount thereof is It should just be in the range of the above-mentioned content.

  The nucleating agent is a component that promotes crystallization of the polypropylene resin composition. By combining this nucleating agent with the crystalline propylene polymer A1, the crystalline propylene polymer A2, and the ethylene-α-olefin copolymer, the half crystallization time of the polypropylene resin composition at 115 ° C. is 70 seconds. It can be as follows. By using a polypropylene resin composition having a semi-crystallization time of not more than 70 seconds at 115 ° C., a molding method in which the formed molded body is required to be solidified in a short time, particularly in the case of a blow fill sealing method. Even if it exists, generation | occurrence | production of the defect of a hollow molded object can be suppressed. From the viewpoint of suppressing defects in the hollow molded article, the half crystallization time at 115 ° C. of the polypropylene resin composition may be 50 seconds or less, 40 seconds or less, 5 seconds or more, or 10 seconds or more. Good. A polypropylene resin composition exhibiting such a short semi-crystallization time is useful, for example, as a polypropylene resin composition for blow fill sealing.

  The nucleating agent can be selected without particular limitation from those used as a nucleating agent in the technical field. Examples of the nucleating agent include aromatic phosphate metal salts, sorbitol nucleating agents, rosin nucleating agents, and polymer nucleating agents such as high density polyethylene and polyvinylcycloalkane. The polypropylene resin composition can contain two or more nucleating agents.

  The content of the nucleating agent is 10,000 ppm or less, 5000 ppm or less, or 2000 ppm or less based on the total amount of the crystalline propylene polymer A1, the crystalline propylene polymer A2 and the ethylene-α-olefin copolymer. It may be 50 ppm or more, 100 ppm or more, or 150 ppm or more. When the content of the nucleating agent is within these ranges, a polypropylene resin composition exhibiting a semicrystallization time of 70 seconds or less can be obtained particularly easily. Here, “ppm” in the present specification is a value based on mass (mass ppm).

  The polypropylene resin composition may further contain other components in addition to the components described above without departing from the spirit of the present invention. Examples of other components include neutralizers, antioxidants, heat stabilizers, weathering agents, ultraviolet absorbers, antistatic agents, dispersants, antibacterial agents, fluorescent whitening agents, dyes, pigments, and fillers. Can be mentioned.

  The polypropylene resin composition can be obtained as a melt-kneaded pellet by, for example, melt-kneading a mixture containing each component. 160-300 degreeC may be sufficient as the temperature of melt-kneading, for example. Or you may supply the mixture before melt kneading containing each component to the molding machine for shape | molding a hollow molded object. Examples of the apparatus used for mixing each component include a Henschel mixer, a V-blender, a ribbon blender, and a tumbler blender. Examples of the apparatus used for melt kneading include a single screw extruder, a twin screw extruder, a kneader kneader, a Banbury mixer, and a roll mill.

  Although the thickness in particular of a hollow molded object is not restrict | limited, For example, 0.1-2.0 mm may be sufficient.

  The hollow container may be a single-layer product composed only of the hollow molded body, or may be a multilayer product further having another layer provided on the inner surface or the outer surface of the hollow molded body. The other layer may be, for example, a resin layer containing a resin selected from an ethylene-vinyl alcohol copolymer, a polyamide resin, and a polyethylene terephthalate resin. Of the thickness of the hollow container, the proportion of the thickness of the hollow molded body of the polypropylene resin composition may be 30% or more, 40% or more, or 50% or more.

  A hollow container usually has a mouth for taking in and out the contents. The mouth portion may form an opening, and in that case, a removable lid may be attached to the mouth portion. Or the sealed container which has the opening | mouth part by which the hollow container was sealed may be sufficient. A hollow container or a hollow molded object can comprise a liquid enclosure container provided with a hollow container and the liquid product accommodated in the hollow container. In this case, the hollow molded body may be a sealed container formed by a blow fill seal method. A liquid product is enclosed in the sealed container. The liquid product only needs to have fluidity that can be taken in and out from the mouth, and may be a viscous material.

  When the surface of the hollow container or the hollow molded body of the polypropylene resin composition is smooth, the hollow container can have a high transparency and good appearance. From such a viewpoint, the average surface roughness SRa of the hollow molded body of the polypropylene resin composition may be 0.01 μm or more, 0.12 μm or less, or 0.10 μm or less.

  The hollow container can be manufactured, for example, by direct blow molding using an extrusion hollow molding machine. In direct blow molding, for example, a polypropylene resin composition is extruded from a die to form a tube-shaped parison, and the parison is sandwiched between molds having a shape corresponding to a hollow molded body, and then pressed inside the parison. Bubbling gas. The parison is shaped into a shape along the mold cavity by the pressure of the pressurized gas and cooled. Thereafter, the mold is opened and the hollow molded body (or hollow container) is discharged.

  When the liquid enclosure is manufactured by the blow fill seal method, the polypropylene resin composition is molded by the above direct blow molding to form a hollow molded body having a mouth portion in the mold, and then in the same mold, After filling the hollow molded body with the liquid product, the mouth is sealed. In this way, even when the hollow molded body is filled with a liquid component in a short time in the same mold after molding, the polypropylene resin composition quickly solidifies, so that defects in the shape of the hollow molded body are suppressed. be able to.

  The use of the hollow container is not particularly limited, but the hollow container is particularly useful as a food container or a medical container. The food container may be, for example, a container containing a liquid product selected from mayonnaise, ketchup, sauce, dressing, honey, jam, soft drink, and ice lolly. The medical container may be a container that contains any liquid medicine such as blood components, physiological saline, electrolyte, dextran preparation, mannitol preparation, saccharide preparation, amino acid preparation, fat emulsion, eye drops, or liquid food as a liquid product. it can.

1. Raw materials The polymers used in Examples and Comparative Examples are as follows.
(A1) Crystalline propylene polymer A1
Crystalline propylene polymer A1-1:
A solid polymerization catalyst for α-olefin polymerization was prepared by the method described in Example 1 of JP-A-7-216017. In the presence of this solid polymerization catalyst, propylene and ethylene were subjected to gas phase polymerization to obtain a propylene-ethylene random copolymer powdery propylene polymer A1-1. When the characteristics of the obtained crystalline propylene polymer A1-1 were measured by the method described later, the melt flow rate was 1.4 g / 10 minutes, the ethylene content was 5.6% by mass, and the melting point was 133 ° C. The heat of fusion was 62 J / g.

Crystalline propylene polymer A1-2
A powdery crystalline propylene polymer A1-2 (melt flow rate: 1), which is a propylene-ethylene random copolymer, is prepared in the same manner as the synthesis of the propylene polymer A1-1 except that the amount of ethylene is changed. 3 g / 10 min, ethylene content: 4.0 mass%, melting point: 142 ° C., heat of fusion: 69 J / g).

(A2) Crystalline propylene polymer A2
Crystalline propylene polymer A2-1 (melt flow rate: 8 g / 10 min, ethylene content: 0% by mass, in the same manner as in the synthesis of propylene polymer A1-1, except that ethylene was not used. Melting point: 166 ° C., heat of fusion: 120 J / g).

(B) Ethylene-α-olefin copolymer Ethylene-hexene-1 copolymer manufactured by Sumitomo Chemical Co., Ltd. (trade name: Excelen FX FX301, MFR (190 ° C., 2.18 N): 3.5 g / 10 min. , Density: 898 kg / m ³ ).

(C) Nucleator C1: Aromatic phosphate metal salt (ADEKASTAB NA-18, manufactured by ADEKA Corporation)
C2: Aromatic phosphate ester metal salt (ADEKASTAB NA-21, manufactured by ADEKA Corporation)

(D) Neutralizing agent, magnesium, aluminum, hydroxide, carbonate (DHT-4C, manufactured by Kyowa Chemical Industry Co., Ltd.)

(E) Antioxidant E1: Phenolic antioxidant (pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], Irganox 1010, manufactured by BASF Japan Ltd.)
E2: Phosphorus antioxidant (Tris (2,4-di-tert-butylphenyl) phosphite, Irgafos 168, manufactured by BASF Japan Ltd.)

2. Test method 2-1. Melt flow rate (MFR)
100 parts by mass of the crystalline propylene polymer A1 or A2 powder was blended with 0.5 parts by mass of an antioxidant dibutylhydroxytoluene (BHT). Using the obtained powder mixture, MFR of the crystalline propylene polymers A1 and A2 was measured at 230 ° C. according to the method of condition 14 of JIS K7210. The MFR of the ethylene-α-olefin copolymer was measured at 190 ° C. according to JIS K6760.

2-2. Density (d)
The density (kg / m ³ ) of the ethylene-α-olefin copolymer was measured according to JIS K6760-1981.

2-3. Content of monomer units derived from ethylene (ethylene content)
The IR spectrum of the crystalline propylene polymer was measured. From the obtained IR spectrum data, the content of monomer units derived from ethylene (unit: mass%) is described on page 616 of Polymer Analysis Handbook (1995, published by Kinokuniya). )) Method for random copolymer ".

2-4. Melting point Tm (unit: ° C), heat of fusion (unit: J / g)
The crystalline propylene polymer was hot press molded to prepare a sheet having a thickness of 0.5 mm. Hot press molding was performed under the conditions of preheating at 230 ° C. for 5 minutes, increasing the pressure to 5.0 MPa over 1 minute, holding the pressure for 2 minutes, and then cooling at 30 ° C. and 5.0 MPa for 5 minutes. About the sample extract | collected from the obtained sheet | seat, differential scanning calorimetry was performed on condition of the following using the differential scanning calorimeter (the Perkin-Elmer company make, Diamond DSC), and melting | fusing point and the heat of fusion were calculated | required.

<Measurement conditions>
The thermal history was added to the test piece in the order of the following (i), (ii), (iii), (iv), (v), (vi) and (vii).
(I) Temperature rise from 24 ° C. to 220 ° C. at a rate of 300 ° C./min (ii) Hold at 220 for 5 minutes (iii) Temperature drop to 150 ° C. at a rate of 300 ° C./min (iv) Hold at 150 ° C. for 1 minute ( v) Temperature drop to 50 ° C. at a rate of 5 ° C./minute (vi) Hold at 50 ° C. for 1 minute (vii) Temperature rise to 180 ° C. at a rate of 5 ° C./minute (vii) From the crystal melting peak obtained from the step The maximum crystal melting peak temperature observed in the range of 50 to 180 ° C. was recorded as the melting point. Further, the heat of fusion (J / g) of the crystal was calculated from the area of the crystal melting peak showing the maximum crystal melting peak. The heat of fusion of a crystal is a value calculated from the area of a region surrounded by a line obtained by extending the base line on both sides of the crystal melting peak and the crystal melting peak.

2-5. Half crystallization time t _1/2 (unit: seconds)
The half crystallization time (t _1/2 ) indicating the crystallization rate was measured by the depolarization intensity method. In the depolarization intensity method, a molten sample is placed between two polarizing plates installed so that their polarization axes are orthogonal to each other, crystallized at a constant temperature, and the crystallization process is followed by the transmitted light intensity of light. Is the method. A longer half crystallization time indicates slower crystallization.
The pellets of the polypropylene resin composition were molded by hot pressing at 190 ° C. to obtain a resin sheet having a thickness of 100 μm. The resin sheet was cut to obtain a 1.5 cm square resin sheet sample. This sample was sandwiched between cover glasses and heated in a melting furnace at 230 ° C. to melt the resin sheet. Thereafter, the cover glass sandwiching the molten resin sheet was placed in an oil bath at 115 ° C., and resin crystallization was started. Two polarizing plates are set in advance so that the polarization axes are perpendicular to each other with an oil bath in between, and a cover glass sandwiching a molten resin sheet has two main surfaces. It fixed to the position between two polarizing plates in an oil bath so that it might become parallel to a polarizing plate. The time during which the transmitted light intensity is halved with respect to the transmitted light intensity of the resin sheet in which crystallization has sufficiently progressed is detected as half-crystallization time t1 _{/ 2} . did. FIG. 1 is a graph showing an example of a method for determining a half-crystallization time from a change in transmitted light intensity with time. The vertical axis in FIG. 1 indicates the intensity of light transmitted through the resin sheet among the incident light, and a large value on the vertical axis means that the transmitted light intensity is high. As shown in FIG. 1, the transmitted light intensity rapidly changes from the initial value as the crystallization progresses, and becomes a constant value when the crystallization sufficiently proceeds. When the difference between the initial value of the transmitted light intensity and the transmitted light intensity after the crystallization has sufficiently progressed is L, the time t _half until the transmitted light intensity reaches the initial value + L / 2, and crystallization starts The difference (t _half -t ₀ ) from t ₀ (time when the change in transmitted light intensity starts) t ₀ is the half crystallization time t _1/2 .

3. 3. Molding of polypropylene resin composition 3-1. Preparation of pellets Raw materials having the composition (parts by mass or ppm) shown in Table 1 were dry blended in a nitrogen atmosphere using a Henschel mixer. The obtained mixture was melt kneaded at 230 ° C. and a rotation speed of 80 rpm under a nitrogen atmosphere by a single screw extruder (manufactured by Tanabe Plastics Machine Co., Ltd., screw diameter: 40 mmφ, VS40-28 type). Pellets were obtained.

3-2. Hollow molding 3-1. The pellets obtained in the above are extruded in a full flight type NB3B hollow molding machine with a diameter of 50 mm and manufactured by Nippon Steel Co., Ltd. at an extrusion rate of 5 kg / hour, die and core temperature of 195 ° C. The hot parison was formed. A hot molded body as a single-layer hollow container having a mouth portion (a hot parison is immediately sandwiched between molds whose temperature is adjusted to 35 ° C. and compressed air having a pressure of 0.1 to 0.15 MPa is blown into the hot parison for 11 seconds ( Weight: 35 g, volume: 600 ml, side wall thickness: about 0.5 mm).

4). Evaluation of hollow container 4-1. Surface roughness of hollow container The central part of the side wall of the hollow container was cut out as a test piece. The average surface roughness of the test piece is measured in the MD direction (longitudinal direction of the container) with a stylus using a three-dimensional surface roughness measuring device Surfcoder SE-30K (manufactured by Kosaka Laboratory Ltd.). The average surface roughness (SRa) μm was determined by the vertical movement of the stylus caused by surface irregularities. The surface of the range of 1 mm × 1 mm was traced at 10 μm intervals in the TD direction perpendicular to the MD direction at a stylus moving speed of 0.2 mm / second.

4-2. Formability Water was put into a hollow container and the mouth was covered. Thereafter, the hollow part was held with the mouth part facing down, and the presence or absence of liquid leakage was confirmed from the mouth part. If there is a defect in the shape of the mouth, liquid leakage occurs. When there is no liquid leakage, “good” and when there is a liquid leakage, “bad”. The moldability was evaluated.

  As shown in Table 1, the hollow container formed from the polypropylene resin composition of the example had a mouth part having a normal shape. Moreover, the surface of the side wall part of the hollow container was sufficiently smooth. On the other hand, since the hollow container formed from the polypropylene resin composition of the comparative example has a defect in the shape of the mouth, liquid leakage occurred. The hollow container of Comparative Example 1 had a low surface smoothness on the side wall.

Claims (7)

A hollow container containing a hollow molded body of a polypropylene resin composition,
The polypropylene resin composition is
(A1) a crystalline propylene polymer A1 containing a monomer unit derived from propylene;
(A2) a crystalline propylene polymer A2 containing a monomer unit derived from propylene;
(B) an ethylene-α-olefin copolymer;
(C) a nucleating agent;
Containing
The crystalline propylene polymer A1 is a copolymer in which the content of monomer units derived from comonomers other than propylene is 2 to 8% by mass based on the mass of the crystalline propylene polymer A1.
In the crystalline propylene polymer A2, the content of monomer units derived from comonomers other than propylene is 0 to 1% by mass based on the mass of the crystalline propylene polymer A2, and 50 to 50 in differential scanning calorimetry. A homopolymer or copolymer having a maximum crystal melting peak temperature of 150 ° C. or higher observed in the range of 180 ° C .;
The comonomer in the crystalline propylene polymer A1 and the crystalline propylene polymer A2 is at least one olefin of ethylene and α-olefin;
The ethylene-α-olefin copolymer has a density of 865-920 kg / m ³ ;
The content of the crystalline propylene polymer A1 is 35 to 93 based on the total amount of the crystalline propylene polymer A1, the crystalline propylene polymer A2, and the ethylene-α-olefin copolymer. The content of the crystalline propylene polymer A2 is 1 to 35% by mass and the content of the ethylene-α-olefin copolymer is 5 to 30% by mass,
A hollow container in which the crystallization time of the polypropylene resin composition measured at 115 ° C. is 70 seconds or less.   The hollow container according to claim 1, comprising only the hollow molded body.   The hollow container according to claim 1, which is a food container.   The hollow container according to claim 1, which is a medical container.   A sealed container comprising the hollow container according to any one of claims 1 to 4 and a liquid product accommodated in the hollow container, wherein the sealed hollow molded body has a sealed mouth, A liquid-filled container in which the liquid product is sealed in a container. A sealed container having a hollow container including a hollow molded body of a polypropylene resin composition and a liquid product accommodated in the hollow container, and having a mouth portion where the hollow molded body is sealed. A method for producing a liquid-sealed container, comprising the step of forming a liquid-filled container in which the liquid product is enclosed by a blow fill sealing method,
The polypropylene resin composition is
(A1) a crystalline propylene polymer A1 containing a monomer unit derived from propylene;
(A2) a crystalline propylene polymer A2 containing a monomer unit derived from propylene;
(B) an ethylene-α-olefin copolymer;
(C) a nucleating agent;
Containing
The crystalline propylene polymer A1 is a copolymer in which the content of monomer units derived from comonomers other than propylene is 2 to 8% by mass based on the mass of the crystalline propylene polymer A1.
In the crystalline propylene polymer A2, the content of monomer units derived from comonomers other than propylene is 0 to 1% by mass based on the mass of the crystalline propylene polymer A2, and 50 to 50 in differential scanning calorimetry. A homopolymer or copolymer having a maximum crystal melting peak temperature of 150 ° C. or higher observed in the range of 180 ° C .;
The comonomer in the crystalline propylene polymer A1 and the crystalline propylene polymer A2 is at least one olefin of ethylene and α-olefin;
The ethylene-α-olefin copolymer has a density of 865-920 kg / m ³ ;
The content of the crystalline propylene polymer A1 is 35 to 93 based on the total amount of the crystalline propylene polymer A1, the crystalline propylene polymer A2, and the ethylene-α-olefin copolymer. The content of the crystalline propylene polymer A2 is 1 to 35% by mass and the content of the ethylene-α-olefin copolymer is 5 to 30% by mass,
A method in which the half crystallization time of the polypropylene resin composition measured at 115 ° C. is 70 seconds or less. A sealed container having a hollow container including a hollow molded body of a polypropylene resin composition and a liquid product accommodated in the hollow container, and having a mouth portion where the hollow molded body is sealed. A polypropylene resin composition for blow fill sealing, which is used for forming a liquid sealed container in which the liquid product is sealed, by a blow fill sealing method,
The polypropylene resin composition is
(A1) a crystalline propylene polymer A1 containing a monomer unit derived from propylene;
(A2) a crystalline propylene polymer A2 containing a monomer unit derived from propylene;
(B) an ethylene-α-olefin copolymer;
(C) a nucleating agent;
Containing
The crystalline propylene polymer A1 is a copolymer in which the content of monomer units derived from comonomers other than propylene is 2 to 8% by mass based on the mass of the crystalline propylene polymer A1.
In the crystalline propylene polymer A2, the content of monomer units derived from comonomers other than propylene is 0 to 1% by mass based on the mass of the crystalline propylene polymer A2, and 50 to 50 in differential scanning calorimetry. A homopolymer or copolymer having a maximum crystal melting peak temperature of 150 ° C. or higher observed in the range of 180 ° C .;
The comonomer in the crystalline propylene polymer A1 and the crystalline propylene polymer A2 is at least one olefin of ethylene and α-olefin;
The ethylene-α-olefin copolymer has a density of 865-920 kg / m ³ ;
The content of the crystalline propylene polymer A1 is 35 to 93 based on the total amount of the crystalline propylene polymer A1, the crystalline propylene polymer A2, and the ethylene-α-olefin copolymer. The content of the crystalline propylene polymer A2 is 1 to 35% by mass and the content of the ethylene-α-olefin copolymer is 5 to 30% by mass,
A polypropylene resin composition for blow fill sealing, wherein the crystallization time of the polypropylene resin composition measured at 115 ° C is 70 seconds or less.

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