container

Abstract

To provide a container capable of sufficiently suppressing an occurrence of a sealing defect between an opening and a lid.SOLUTION: The present invention provides a container molded using a rubber-modified styrenic resin composition. The container has a flange surface at an opening, has a height of 75 mm or more, an opening diameter of 25 mm or more, and a flange width of the flange surface of 3.0 mm or less, and a shrinkage rate in a height direction of the container when immersed in hot water at 90°C for 10 seconds is 0.25% or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a container. [Background technology]

[0002] 2. Description of the Related Art Rubber-modified styrene-based resin compositions have been conventionally used for various containers for storing beverages, foods, etc., particularly for packaging containers for beverages such as lactic acid bacteria beverages and foods such as fermented milk. When contents such as beverages are to be contained in such a container, a shrink label is first attached to the outer surface of the container to display the product name, shelf life, manufacturer, distributor, handling precautions, etc., and to provide decorativeness and functionality, and then the container is filled with the contents and the opening of the container is sealed with a lid. As an example of a method for attaching a shrink label to a container, a method is known in which the outer circumference of the container is covered with a cylindrical label, and the shrink label is heated together with the container in this state in a heating tunnel to cause thermal shrinkage. In addition, as a lid material for sealing the opening of the container, for example, an aluminum laminate with an aluminum foil as a base material or a resin sheet with a sealant layer provided on the lower surface of a laminated base material of a synthetic resin is used. These lid materials are attached to the flange surface of the opening of the container by a method such as ultrasonic sealing, high-frequency induction sealing, high-frequency dielectric sealing, heat sealing with a hot plate, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-76565 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, a wide variety of shapes of such containers have been proposed for the purpose of imparting functionality such as an attractive appearance, light weight, and impact resistance. However, for containers having specific dimensions, poor sealing can occur between the opening of the container and the lid, and improvements were required.

[0005] Therefore, an object of the present disclosure is to provide a container that can sufficiently prevent the occurrence of poor sealing between the opening and the lid. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems, and as a result have found that (i) in the process of sealing the lid to the opening of a container, it is necessary that the entire lid be in close contact with the flange surface of the opening of the container, but in the heating atmosphere in the shrink label attachment process (thermal shrinkage process), uneven thermal shrinkage of the container may occur due to, for example, temperature unevenness, and the flange surface of the opening of the container may shift slightly in the attachment direction of the lid, making it difficult to adhere, and (ii) in a container whose opening diameter is equal to or larger than a certain size and whose flange width is small, when the lid is placed over the opening to seal the opening, if the lid shifts with respect to the opening of the container, a seal failure between the opening of the container and the lid is likely to occur.The present inventors have found that suppressing the shift of the flange surface of the container in the shrink film attachment process leads to an improvement in the seal failure, and have completed the present invention.

[0007] That is, the present invention is as follows. [1] The present disclosure relates to a container molded from a rubber-modified styrene-based resin composition, the container having a flange surface for tightly fitting a lid material, a height of 75 mm or more, a mouth diameter of 25 mm or more, and a flange width of 3 mm or less, and a shrinkage rate in the height direction of the container of 0.25% or less when immersed in 90°C warm water for 10 seconds. [2] In this embodiment, the container according to [1] is characterized in that a shrink label is attached. [3] In this embodiment, the container is according to [1] or [2], which is formed by molding a rubber-modified styrene-based resin composition, the rubber-modified styrene-based resin composition having a liquid paraffin content of 0.3 to 2.5 wt %. [4] In this embodiment, the container is the container according to any one of [1] to [3], characterized in that the container is injection blow molded. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a container that can sufficiently prevent the occurrence of poor sealing between the opening and the lid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The following describes in detail an embodiment of the present invention (hereinafter referred to as the "present embodiment"); however, the present invention is not limited to the following description and can be implemented in various modified forms within the scope of its gist.

[0010] <Container> The container of this embodiment is a container molded using a rubber-modified styrene-based resin composition. The container has a flange surface at the opening, a height of 75 mm or more, an opening diameter of 25 mm or more, a flange width of the flange surface of 3.0 mm or less, and a shrinkage rate in the height direction of the container when immersed in 90°C warm water for 10 seconds of 0.25% or less. According to this embodiment, it is possible to sufficiently suppress the occurrence of poor sealing between the opening of the container and the lid material.

[0011] The container of the present embodiment is not particularly limited as long as it has a recessed structure with an opening having a flange surface, but may be, for example, a cylindrical upright container with an opening at the top. The opening can be sealed by adhering a lid material to the flange surface. The container of this embodiment has a height of 75 mm or more, an opening diameter of 25 mm or more, and a flange width of the flange surface of 3.0 mm or less. Conventionally, containers of this shape have been prone to sealing defects, but the container of this embodiment can sufficiently prevent the occurrence of such sealing defects. In addition, the height of the container in this embodiment is 75 mm or more as described above, but may be 77.5 mm or more, and is preferably 80 mm or more. On the other hand, from the viewpoint of container strength, the upper limit of the container height is preferably 120 mm, and more preferably 115 mm. The height of a container is the length measured vertically upward from the horizontal plane to the opening of the container when the container is placed on a horizontal plane with the opening facing vertically upward.

[0012] The diameter of the body of the container can be 30 to 60 mm, preferably 33 to 55 mm, and more preferably 35 to 50 mm. The body diameter of a container is the longest length measured from one horizontal end to the other horizontal end of the container when the container is placed on a horizontal surface with its opening facing vertically upward and viewed horizontally.

[0013] The opening of the container is, for example, circular, and has a diameter of 25 to 60 mm. The opening diameter can be 26 to 55 mm, and is preferably 27 to 50 mm. The flange surface has a flange width of 3.0 mm or less, but may have a flange width of 2.7 mm or less, and is preferably 2.5 mm or less. On the other hand, from the viewpoint of adequately maintaining the sealing by the lid material, the flange width is preferably 1.0 mm or more, more preferably 1.2 mm or more, and even more preferably 1.5 mm or more. The opening diameter is the outer diameter of the opening (the diameter at the outer end of the opening), and the flange width is the length measured radially from the outer end to the inner end of the opening when the container is viewed from above. In the container of this embodiment, it is preferable that a bottom surface portion is provided so as to face the opening portion. The bottom surface portion of the container is, for example, circular, and the diameter of the circular bottom surface portion can be 30 to 60 mm, preferably 33 to 55 mm, and more preferably 35 to 50 mm, similar to the body diameter of the container.

[0014] Furthermore, the container of this embodiment has a shrinkage rate in the height direction of 0.25% or less, and preferably 0.2% or less. If the shrinkage rate in the height direction of the container exceeds 0.25%, poor sealing occurs between the container and the lid. Specifically, the larger the opening diameter and the smaller the flange width of the container, the more likely it is that a sealing defect will occur if there is a misalignment, such as the attachment direction of the lid material not being perpendicular to the flange surface of the container opening (specifically, the flange surface being slightly tilted), and the taller the container, the more likely such a misalignment will occur. Since the container of this embodiment has a shrinkage rate in the height direction of 0.25% or less, misalignment of the attachment direction of the lid material relative to the flange surface of the container opening is suppressed in the shrink label attachment process (thermal shrinkage process), and poor sealing between the container opening and the lid material in the sealing process can be suppressed. On the other hand, from the viewpoint of preventing the occurrence of poor sealing, the lower limit of the shrinkage rate in the height direction is not particularly limited, and it is preferably more than 0%. The shrinkage rate is measured by measuring the height of the container before and after immersion in 90° C. warm water for 10 seconds, and the ratio of the difference before and after immersion to the height before immersion. A specific measurement method can be performed by the method described in the Examples.

[0015] In the container of this embodiment, the shrinkage rate in the height direction of the container can be adjusted, for example, by the heat resistance temperature and orientation stress of the container. The higher the heat resistance temperature of the container, the smaller the shrinkage rate of the container, and the smaller the orientation stress of the container, the smaller the shrinkage rate of the container.

[0016] The heat-resistant temperature of the container is the glass transition temperature measured according to JIS K7121, and is preferably 96 to 106°C, and more preferably 97 to 105°C. If the heat-resistant temperature is less than 96°C, the shrinkage rate of the container tends to increase. If the heat-resistant temperature exceeds 106°C, the orientation during container molding tends to increase, and the shrinkage rate of the container tends to increase. The heat-resistant temperature of the container can be adjusted by the content of the styrene-based resin and the rubber-like polymer dispersion particles contained in the rubber-modified styrene-based resin composition, and the content of the liquid paraffin, which is an optional component.

[0017] The orientation stress of the container is the peak value of the heat shrinkage stress measured in silicone oil at a temperature equal to the glass transition temperature of the container plus 30°C. The preferred range varies depending on the heat resistance temperature of the container, but is 10 to 35 N / mm at a heat resistance temperature of 96°C or higher. 2 and more preferably 12 to 30 N / mm 2 In addition, at heat resistance temperatures below 96°C, the strength is 10 to 25 N / mm 2 and more preferably 12 to 23 N / mm 2 It is. If the orientation stress exceeds the upper limit, the shrinkage rate of the container in the height direction tends to increase, whereas if the orientation stress is below the lower limit, the strength of the container tends to decrease. The orientation stress applied to the container can be adjusted by adjusting the molding conditions such as temperature, pressure, and cooling time when molding the container.

[0018] <Rubber-modified styrene-based resin composition> The rubber-modified styrene resin composition is a composition in which rubber polymer particles are dispersed in a styrene resin matrix, and can be produced by polymerizing a styrene monomer in the presence of the rubber polymer. Hereinafter, the rubber polymer particles dispersed in the matrix are referred to as rubber polymer dispersed particles.

[0019] In this embodiment, examples of the styrene monomer constituting the styrene resin in the rubber-modified styrene resin composition include, in addition to styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and t-butylstyrene, or styrene derivatives such as bromostyrene, chlorostyrene, and indene, with styrene being particularly preferred. These styrene monomers may be used alone or in combination.

[0020] As the rubber-like polymer, polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. can be used, but from an industrial point of view, polybutadiene and styrene-butadiene copolymer are preferred. As the polybutadiene, both high-cis polybutadiene having a high cis content and low-cis polybutadiene having a low cis content can be used. In addition, as the structure of the styrene-butadiene copolymer, both a random structure and a block structure can be used. These rubber-like polymers can be used alone or in combination. In addition, saturated rubber obtained by hydrogenating butadiene rubber can also be used.

[0021] The rubber-like polymer contained in the rubber-modified styrene-based resin composition may be one which encapsulates a styrene-based resin on the inside and has a styrene-based resin grafted on the outside. Examples of such rubber-modified styrene-based resin compositions include HIPS (high impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), and AES resin (acrylonitrile-ethylene propylene rubber-styrene copolymer).

[0022] The content of the rubber-like polymer dispersion particles contained in the rubber-modified styrene-based resin composition is preferably 15 to 25% by mass, more preferably 17 to 24% by mass. If the content of the rubber-like polymer dispersion particles is less than 15% by mass, the impact resistance of the molded container decreases and it becomes easy to break. On the other hand, if the content of the rubber-like polymer dispersion particles exceeds 25% by mass, the flowability decreases and the rigidity of the molded container decreases. In the present disclosure, the content of the rubber-like polymer dispersed particles contained in the rubber-modified styrene-based resin composition is a value measured by the procedure described in the Examples section below.

[0023] The average particle size of the dispersed rubber polymer particles contained in the rubber-modified styrene-based resin composition is preferably from 0.5 to 5.0 μm, and more preferably from 1.0 to 4.0 μm, from the viewpoint of impact resistance. In the present disclosure, the average particle size of the dispersed rubber polymer particles contained in the rubber-modified styrene-based resin composition is a value measured by the procedure described in the Examples section below.

[0024] The reduced viscosity of the rubber-modified styrene-based resin composition (which is an index of the molecular weight of the styrene-based resin in the rubber-modified styrene-based resin composition) is preferably in the range of 0.50 to 0.85 dL / g, more preferably in the range of 0.55 to 0.80 dL / g. If it is less than 0.50 dL / g, the impact strength decreases, and if it exceeds 0.85 dL / g, the moldability decreases due to the decrease in fluidity. In the present disclosure, the reduced viscosity of the rubber-modified styrene-based resin composition is a value measured in a toluene solution at 30°C and a concentration of 0.5 g / dL, and more specifically, is a value measured by the procedure described in the Examples section below.

[0025] In this embodiment, the melt flow rate of the rubber-modified styrene-based resin composition is preferably 1 to 50 g / 10 min, more preferably 2 to 40 g / 10 min, and even more preferably 3 to 30 g / 10 min. If the melt flow rate is lower than 1 g / 10 min, the fluidity during container molding is insufficient, and moldability is reduced. If the melt flow rate is 50 g / 10 min or more, appearance defects such as stringiness and burrs are likely to occur during container molding, which is not preferable. In this embodiment, the melt flow rate can be measured in accordance with ISO 1133.

[0026] In this embodiment, it is preferable to compound a release agent in the rubber-modified styrene-based resin composition for release during molding of the container. The release agent may be a mixture of higher fatty acid and higher fatty acid metal salt, and the mass ratio is 1 / 3 to 3.5, and the compounding amount is preferably 0.1 to 0.4 parts by mass with respect to 100 parts by mass of the rubber-modified styrene-based resin composition. If the compounding amount is less than 0.1 parts by mass, the release property tends to be poor. On the other hand, if the compounding amount is more than 0.4 parts by mass, the resin composition is likely to undergo thermal discoloration and thermal deterioration. Here, the higher fatty acid is a saturated linear carboxylic acid having 12 to 22 carbon atoms. In addition, the higher fatty acid metal salt is a metal salt of the above higher fatty acid, and the type of metal is not particularly limited, but examples include aluminum, calcium, magnesium, zinc, etc.

[0027] In this embodiment, from the viewpoint of moldability, the rubber-modified styrene-based resin composition preferably contains 0.3 to 2.5% by mass of liquid paraffin relative to the entire rubber-modified styrene-based resin composition (100% by mass). Preferably, it is 0.5 to 2.0% by mass. From another viewpoint, it is preferable to contain 0.3 to 0.95% by mass of liquid paraffin. If the content of liquid paraffin exceeds 2.5% by mass, the heat-resistant temperature decreases, the container becomes easily deformed, and stringiness occurs easily during injection blow molding, which is not preferable. If the content of liquid paraffin is less than 0.3% by mass, the mouth strength of the container (strength at the opening) decreases, which is not preferable. Various liquid paraffins can be mentioned, but the number average molecular weight is preferably in the range of 375 to 425. Such liquid paraffins have an initial boiling point of 2.5% by mass measured by ASTM D1160 (10 mmHg) of 230 to 290°C. The content of liquid paraffin can be determined by analyzing the methanol-soluble content by liquid chromatography.

[0028] In the present embodiment, various additives that are commonly used may be added to the rubber-modified styrene-based resin composition as desired to achieve known effects, such as lubricants, antioxidants, UV absorbers, plasticizers, dyes, pigments, antistatic agents, antifogging agents, and various fillers, to achieve effects suited to the respective purposes. The amount of each of the above-mentioned various additives in the rubber-modified styrene-based resin composition is preferably 1.0 mass% or less, more preferably 0.8 mass% or less, and even more preferably 0.5 mass% or less, relative to 100 mass% of the rubber-modified styrene-based resin composition.

[0029] <Method of producing rubber-modified styrene-based resin composition> The method for producing the rubber-modified styrene-based resin composition is not particularly limited, but it can be obtained by graft polymerization of a styrene-based monomer in the presence of a rubber-like polymer, and the polymerization method can be a known method such as bulk polymerization, two-stage bulk / suspension polymerization, solution polymerization, etc. In addition, when the rubber-modified styrene-based resin composition contains the above-mentioned release agent, liquid paraffin, various additives, and the like, any method may be adopted. For example, each component may be added during polymerization of the rubber-modified styrene-based resin composition, or each component may be mixed after the polymerization using a mixing means such as a blender to prepare a lump-sum blend, which is then melt-kneaded in a vented extruder and pelletized.

[0030] <Properties of the rubber-modified styrene-based resin composition> In the present embodiment, the amount of low molecular weight components in the rubber-modified styrene-based resin composition is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, based on 100% by mass of the rubber-modified styrene-based resin composition. By making the amount of low molecular weight components 0.5% by mass or less, it is possible to reduce mold contamination during molding or to make it easier to ensure the strength of the container. In this embodiment, the low molecular weight components broadly include styrene monomer, styrene dimer, styrene trimer, unreacted copolymerizable monomer, monomer impurities, polymerization inhibitors for monomers, polymerization solvents, decomposition products of polymerization initiators, and the like. In order to adjust the low molecular weight component to a predetermined range, there can be mentioned a method of increasing the temperature when removing unreacted monomers during the production of the rubber-modified styrene-based resin composition, or a method of reducing it by using an additive.

[0031] In addition, the rubber-modified styrene-based resin composition in this embodiment has a notched Charpy impact strength of 4 kJ / m as measured in accordance with ISO179. 2 It is preferable that the concentration is equal to or higher than 5 kJ / m 2 The strength is 4kJ / m or more. 2 The above conditions mean that the material can be used adequately as a container.The test pieces used to measure the strength are ISO mold type A test pieces molded with an injection molding machine EC60N manufactured by Toshiba Machine Co., Ltd. at a cylinder temperature of 220°C, a mold temperature of 45°C, an injection pressure of 80 MPa, and an injection speed of 26 mm / s. The notched Charpy impact strength can be adjusted within a predetermined range by the amount of rubber in the rubber-modified resin composition or the swelling degree of the dispersed rubber polymer particles, and the reduced viscosity of the styrene-based resin.

[0032] In this embodiment, the swelling degree of the rubber-like polymer dispersion particles is preferably 8 to 15. The swelling index is more preferably 9 to 14, and even more preferably 10 to 13. The smaller the swelling degree value, the higher the crosslink density, and the less flexible the rubber component is, the harder it becomes and the less likely it is to deform. On the other hand, the larger the swelling degree value, the lower the crosslink density, and the more flexible the rubber component is, and the more likely it is to be modified. By appropriately adjusting the degree of crosslinking of the rubber component, excellent mechanical strength is achieved.

[0033] <Container molding method> The method for molding the container in this embodiment is not particularly limited, and the container can be molded by a known molding method. For example, the injection blow molding method, the injection stretch blow molding method, and the direct blow molding method can be preferably used. Here, the injection blow molding method is a method in which a bottomed parison is first formed by injection molding, and then this parison is transferred in a softened state to a blow molding die while still attached to a core (male injection molding die), and compressed air is then pumped in from the core to inflate the parison up to the inner wall of the blow molding die, thereby forming a hollow molded product (container). Injection stretch blow molding is a method in which a bottomed parison previously obtained by extrusion molding or the like is heated and softened, set in a mold, and while maintaining the parison at the molding temperature, it is stretched vertically with a rod, and then compressed air is blown in to inflate it up to the inner wall of the mold, forming a hollow molded product (container). Direct blow molding is a method of forming a hollow molded product (container) by placing a tubular molten parison extruded from an extruder into a mold, maintaining the parison at the molding temperature, and blowing compressed air into it to inflate it up to the inner wall of the mold.

[0034] The parison is an intermediate from which the container of the present embodiment can be produced, and can be produced from the rubber-modified styrene-based resin composition. The shape of the parison is not particularly limited, but may be, for example, a vertical cylinder having an opening. The parison may have a height of 72 to 116 mm and a body diameter of 23 to 58 mm. The opening of the parison is flange-shaped, with an opening diameter of 21 to 54 mm and a flange width of 1.0 to 3.0 mm. The height of the parison is the length measured from the opening to the bottom along the longitudinal direction of the parison, the body diameter is the longest length measured along the direction perpendicular to the longitudinal direction of the parison, the opening diameter is the outer diameter of the opening (the diameter at the outer end of the opening), and the flange width is the length measured radially from the outer end to the inner end of the opening when the parison is viewed from above.

[0035] In the above molding method, the temperature of the cylinder in the melting step of the resin or rubber-modified styrene-based resin composition is preferably 180 to 280° C., and more preferably 200 to 260° C. In the stage of molding the parison, the temperature of the core (male mold for injection molding) is preferably 100 to 180° C., and more preferably 110 to 170° C. In the stage of blow molding the parison, the mold temperature is preferably 20 to 70° C., more preferably 25 to 65° C., and even more preferably 30 to 60° C. The ratio of the volume of the container to the volume of the parison (volume stretching ratio) is preferably 1.5 to 7 times, and more preferably 2 to 5 times.

[0036] In this embodiment, from the viewpoint of container productivity, the container is preferably manufactured by injection blow molding.

[0037] <Container Use> The container of the present embodiment can be used, for example, as a container for storing beverages such as lactic acid bacteria beverages and foods such as fermented milk, without being particularly limited thereto. A shrink film can be attached to the molded container, and after the shrink film is attached, the container can be filled with contents and a lid material can be heat-sealed to the opening of the container to form a sealed container. The sealed container is then inspected and packaged before being shipped as a product.

[0038] The container of this embodiment may have a shrink film (it may be used in a tightly attached state). The shrink film is a layer that serves as the base material of the label and is responsible for strength properties, shrinkage properties, etc. The resin used in the shrink film can be appropriately selected according to the required physical properties, cost, etc., and is not particularly limited. For example, polyester resins, polyolefin resins, polystyrene resins, polyvinyl chloride, polyamide resins, aramid, polyimide, polyphenylene sulfide, acrylic resins, and other resins can be used. Among them, polyester films, polystyrene films, or laminated films thereof are preferred. As polyester resins, polyethylene terephthalate (PET) resins, poly(ethylene-2,6-naphthalenedicarboxylate) (PEN), polylactic acid (PLA), and the like can be used, and among them, polyethylene terephthalate (PET) resins are preferred. As polystyrene resins, general polystyrene, styrene-butadiene copolymers (SBS), styrene-butadiene-isoprene copolymers (SBIS), and the like are particularly preferred.

[0039] The method of attachment to a container is not particularly limited, but for example, in the case of a cylindrical shrink label, a long cylindrical shrink label is cut and attached to a specified container, and the label is shrunk by heat treatment and adhered to the container to produce a labeled container. Specifically, the long cylindrical shrink label is fed to an automatic label attachment device (shrink labeler), cut to the required length, and then the container is surrounded and passed through a hot air tunnel or steam tunnel heated to 75 to 200°C. The label is heated in the tunnel and thermally shrunk, adhering to the container to obtain a labeled container. The shrink film can be attached to the container after sterilization. The container with the shrink film attached can be used by filling it with a beverage or food and providing a lid on the opening of the container. The lid material for sealing the container can be an aluminum laminate using aluminum foil as a base material or a resin sheet with a sealant layer provided on the lower surface of a laminated base material of synthetic resin. The method for sealing these lid materials to the flange surface of the opening of the container is not particularly limited, but for example, ultrasonic sealing, high-frequency induction sealing, high-frequency dielectric sealing, heat sealing using a hot plate, etc. are known.

[0040] Although the embodiment of the present invention has been described above, the container of the present invention is not limited to the above example and can be modified as appropriate. EXAMPLES

[0041] The present invention will be specifically described below with reference to examples and comparative examples, but it should not be construed that the present invention is limited to these examples. First, the evaluation methods used to evaluate the Examples and Comparative Examples will be described below.

[0042] 1. Evaluation method (1) Content of rubber-like polymer dispersed particles 1 g of the rubber-modified styrene-based resin composition is weighed out (W1), 20 ml of toluene is added, and the mixture is shaken at 23°C for 2 hours, and then centrifuged at 10°C or lower and 20,000 rpm for 60 minutes in a centrifuge (e.g., Hitachi, Ltd.'s himac (product name) CR-20 (rotor: R20A2)). The supernatant is removed by decantation to obtain the insoluble matter. Subsequently, the mixture is vacuum-dried for 60 minutes under conditions of 160°C and 20 mmHg or lower, and then cooled to room temperature in a desiccator, and the mass of the insoluble matter is weighed out (W2). The toluene insoluble matter is calculated using the following formula: Toluene insolubles (mass%) = (W2 / W1) x 100

[0043] (2) Particle size of dispersed rubber polymer particles Using a COULTER MULTISIZER III (trade name) manufactured by Beckman Coulter, Inc. equipped with an aperture tube with a diameter of 30 μm, 2 to 5 pellets of the rubber-modified styrene-based resin composition were placed in about 5 ml of dimethylformamide and left for about 2 to 5 minutes. Next, the dimethylformamide soluble content was measured as an appropriate particle concentration, and the volume-based median diameter was calculated.

[0044] (3) Measurement of low molecular weight components The remaining amounts (mass %) of styrene monomer, styrene dimer and styrene trimer in the pellets of the rubber-modified styrene resin composition were measured under the following conditions and procedures. Sample preparation: 2.0 g of the rubber-modified styrene-based resin composition was dissolved in 20 mL of chloroform, and then 5 mL of methanol containing a standard substance (triphenylmethane) was added to reprecipitate the polymer component. The supernatant was collected and used as the measurement solution. Measurement conditions Equipment: Agilent 6850 Series GC system Detector: FID Column: HP-1 (100% dimethylpolysiloxane) 30 m, film thickness 0.25 μm, 0.32mmφ Injection volume: 1 μL (splitless) Column temperature: 40°C for 2 minutes, increase temperature to 320°C at 20°C / min, and hold at 320°C for 15 minutes. Inlet temperature: 250℃ Detector temperature: 280℃ Carrier gas: Helium

[0045] (4) Measurement of liquid paraffin content 2 g of the rubber-modified styrene-based resin composition was precisely weighed, 40 ml of methyl ethyl ketone was added, and the mixture was shaken at 23°C for 40 minutes. The solution was then dropped into 200 ml of methanol, heated at 60°C for 10 minutes, cooled to 23°C, and filtered through a membrane filter with a pore size of 0.45 μm. The separated filtrate was concentrated by distillation under reduced pressure, dried at 80°C for 30 minutes, cooled to 23°C, and dissolved in normal hexane to obtain a 10 ml sample. The liquid paraffin content of the obtained sample was quantified by liquid chromatography under the following conditions.

[0046] (5) Melt flow rate measurement The melt mass flow rate (g / 10 min) was measured in accordance with ISO 1133 (200° C., load 49 N).

[0047] (6) Charpy impact strength measurement The notched Charpy impact strength was measured in accordance with ISO 179. The test pieces used to measure the strength were ISO mold type A test pieces molded with an injection molding machine EC60N manufactured by Toshiba Machine Co., Ltd. at a cylinder temperature of 220°C, a mold temperature of 45°C, an injection pressure of 80 MPa, and an injection speed of 26 mm / s.

[0048] (7) Measurement of reduced viscosity Approximately 1 g of the rubber-modified styrene-based resin composition is added to 20 ml of a methyl ethyl ketone / methanol mixed solvent (mixture weight ratio 90 / 10), and dissolved using a shaker for 60 minutes. Next, using a Hitachi himacCR20 centrifuge equipped with an R20A2 rotor, the mixture is centrifuged at 0°C and 20,000 rpm for 60 minutes, and methanol is added to the supernatant to precipitate the styrene-based resin matrix. The precipitate is filtered and then dried to prepare a sample, which is then dissolved in toluene at a concentration of 0.5 g / dL to prepare a sample solution. The sample solution and pure toluene are measured for the number of seconds the solution flows down using a Cannon-Fenske viscometer at a constant temperature of 30°C, and the reduced viscosity (η) is calculated using the following formula (1). sp ) was calculated. η sp / C=(t1 / t0-1) / C Equation (1) (In the above formula (1), t0 is the number of seconds that pure toluene flows down, t1 is the number of seconds that the sample solution flows down, and C is the concentration of the polymer (styrene-based resin).)

[0049] (8) Height shrinkage rate of container The container was left to stand (conditioning) for 24 hours in an environment with a temperature of 23°C and a humidity of 50%. The container was placed on a horizontal surface so that the opening of the container was vertically upward, and the height L1 of the container was obtained by measuring from the horizontal surface to the opening in the vertical direction upward, and then the container was immersed in hot water at 90°C for 10 seconds, and the container was quickly cooled using cold water at 25°C after being taken out. The container was then left to stand (conditioning) for 24 hours again in an environment with a temperature of 23°C and a humidity of 50%, and the height L2 of the container was measured in the same manner as the height L1. The shrinkage rate was calculated from the obtained heights L1 and L2 using the following formula (2). ((L1-L2) / L1)×100(%) Formula (2)

[0050] (9) Heat resistance of container A sample was cut out from the body of the container and measured using a differential scanning calorimeter (DSC-60) manufactured by Shimadzu Corporation in accordance with JIS K7121. Specifically, the temperature was raised from room temperature to 200°C at 10°C / min under a nitrogen stream, then returned to room temperature at 10°C / min, and again raised to 200°C at 10°C / min. The glass transition temperature measured during the second heating process was taken as the heat resistance temperature of the container.

[0051] (10) Orientation stress on the container A test piece 10 mm wide and 60 mm long was cut out from the container so that the longitudinal direction of the test piece was the height direction of the container, and it was immersed in an oil bath filled with silicone oil heated to the heat resistance temperature of the container + 30°C, and the stress when the test piece thermally contracted was measured.

[0052] (11) Evaluation of the attachment of the lid to the opening of the container (evaluation of sealing ability) The container was placed in a hot air dryer (Kato Riki Seisakusho Co., Ltd., Speed ​​Dry Oven KRS-III-12) set at a temperature of 85°C, and removed after 10 seconds. The heated container was placed on a horizontal plane, 100 ml of water (5°C) was poured in, and then a lid material having an aluminum foil base and an LDPE sealant layer on the lower surface of the base was placed on the opening of the container. Then, a 2 kg iron plate heated to 160°C was brought into contact with the opening of the container from the vertical direction for 1 second while maintaining the iron plate horizontal. The obtained container was evaluated according to the following criteria. ○: Water did not leak out when the container was turned upside down, and the lid did not come off when it was lifted by grabbing the edge of the lid. △: Water did not leak out when the container was turned upside down, but when the edge of the lid was grasped and lifted, a portion of the lid came off. ×: Water leaked out when the container was turned upside down.

[0053] (12) Impact strength of container opening The impact strength of the container opening was measured using a DuPont impact tester (No. 451) manufactured by Toyo Seiki Seisakusho Co., Ltd. The falling weight had a mass of 0.2 kg and a radius of 1 / 2 inch at the tip of the impact center. Tests were conducted on 280 containers, and the impact strength of the falling weight calculated from the 50% breaking height was taken as the impact strength of the opening. Mass of the falling weight 0.2 kg × 50% breaking height cm = opening impact strength (kg cm) The opening impact strength is preferably 3.5 kg·cm or more, and more preferably 4.0 kg·cm or more. If it is less than 3.5 kg·cm, the opening may break when the container is dropped.

[0054] (13) Mold contamination After 1000 shots of continuous molding with one cycle of 7.2 seconds, the mold surface was wiped vigorously with gauze and the degree of adhesion of oily substances to the gauze was evaluated. The evaluation criteria are as follows: ◯: No adhesion of oily substances was observed. △: A small amount of oily substance was observed. ×: Significant adhesion of oily substances was observed.

[0055] (14) Formability of containers Continuous molding was performed at 7.2 seconds per cycle, and 1000 shots were molded to evaluate whether continuous molding was possible. The evaluation criteria are as follows: ◯: Continuous molding of 1000 shots was possible, or the number of containers with insufficient blowing or stringy marks was 4 or less. △: Continuous molding of 1000 shots was possible, but five or more containers had insufficient blowing or stringy marks. ×: Continuous molding of 1000 shots was not possible (problems such as poor blowing occurred and the molding was stopped midway).

[0056] 2. Container manufacturing Subsequently, rubber-modified styrene-based resin compositions (HIPS-1 to HIPS-9) were obtained according to the following Synthesis Examples 1 to 9. Synthesis Example 1: Preparation of rubber-modified styrene-based resin composition HIPS-1 A polymerization liquid obtained by mixing and dissolving 87.0 parts by mass of styrene as a styrene monomer, 3.8 parts by mass of polybutadiene rubber (Diene 55AE manufactured by Asahi Kasei Corporation) as a rubber-like polymer, 8.5 parts by mass of ethylbenzene as a solvent, 0.6 parts by mass of liquid paraffin (CP-68N manufactured by Idemitsu Kosan Co., Ltd.) as a plasticizer, 0.002 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane as a polymerization initiator 1, and 0.06 parts by mass of α-methylstyrene dimer as a chain transfer agent 1 was continuously charged at 3.2 L / Hr into a 6.2 L laminar flow reactor-1 equipped with a stirrer and capable of temperature control in three zones, and the temperature was adjusted to 125 ° C. / 130 ° C. / 135 ° C. The rotation speed of the stirrer was 80 revolutions per minute. The reaction rate at the reactor outlet was 28%.

[0057] The reaction liquid was then sent to a 6.2-liter laminar flow reactor-2 equipped with an agitator and capable of temperature control in three zones, which was connected in series to the laminar flow reactor-1. The agitator rotation speed was set to 20 rpm, and the temperature was set to 137°C / 138°C / 139°C. The reaction solution was then sent to a 6.2-liter laminar flow reactor-3 equipped with an agitator and capable of temperature control in three zones. The agitator speed was set at 10 revolutions per minute, and the temperature was set at 142°C / 143°C / 148°C.

[0058] The reaction liquid from the laminar flow reactor-3 was then fed to a two-stage vacuum vent-equipped extruder adjusted to 220°C and 1.2kPa to remove volatile components such as unreacted monomers and solvents, and the resin extruded in a strand shape was cut to obtain pellets. 0.23 parts by mass of a 3:1 mixture of stearic acid / calcium stearate was mixed with 100 parts by mass of the pellets as a release agent, and the mixture was kneaded using an extruder to prepare a rubber-modified styrene-based resin composition. The manufacturing conditions and analysis results of the obtained rubber-modified styrene-based resin composition are shown in Table 1.

[0059] <Synthesis Examples 2 to 9> Preparation of rubber-modified styrene-based resin compositions HIPS-2 to 9 The rubber-modified styrene-based resin compositions HIPS-2 to 9 were synthesized in the same manner as HIPS-1, except that the conditions were changed as shown in Table 1. The rubber-like polymer dispersed particle content of the rubber-like polymer particles, the particle size of the rubber-like polymer particles, and the reduced viscosity of the styrene-based resin were controlled as shown in Table 1.

[0060] [Table 1]

[0061] Next, examples and comparative examples will be described. <Example 1> The obtained rubber-modified styrene-based resin composition HIPS-1 was molded into a container using an injection blow molding machine SG-125NP manufactured by Sumitomo Heavy Industries, Ltd. Specifically, a parison with a bottom (height 80 mm, opening diameter 28 mm, flange width 2.0 mm, body diameter 25 mm) was first formed by injection molding, and this parison was transferred into a blow molding die while still attached to a core (male injection mold) in a softened state (260°C), and compressed air was pumped in from the core to inflate it to the inner wall of the blow molding die, forming a hollow molded product (container). The male mold temperature at this time was 150°C, and the resin temperature was 200°C. The size of the resulting container was height 83 mm, opening diameter 28 mm, flange width 2.0 mm, body 45 mm, and it was stretched 2.7 times the parison. The molding conditions and evaluation results of the obtained containers are shown in Table 2.

[0062] <Examples 2 to 7> Containers of Examples 2 to 7 were produced in the same manner as in Example 1, except that the rubber-modified styrene-based resin compositions HIPS-2 to HIPS-6 were molded under the molding conditions shown in Table 2. The size of the resulting containers was 83 mm in height, 28 mm in opening diameter, 2.0 mm in flange width, and 45 mm in body, and the stretch ratio relative to the parison was 2.7 times. The molding conditions and evaluation results of the obtained containers are shown in Table 2.

[0063] <Comparative Examples 1 to 4> Containers of Comparative Examples 1 to 4 were produced in the same manner as in Example 1, except that the rubber-modified styrene-based resin compositions HIPS-7 to HIPS-9 and HIPS-4 were molded under the molding conditions shown in Table 2. The size of each of the resulting containers was 83 mm in height, 28 mm in opening diameter, 2.0 mm in flange width, and 45 mm in body, and the stretch ratio relative to the parison was 2.7 times. The molding conditions and evaluation results of the obtained containers are shown in Table 2.

[0064] [Table 2]

[0065] From the examples in Table 2, it can be seen that the containers of the present invention have excellent sealing properties for the lid attached to the container opening. On the other hand, from the comparative examples in Table 2, it can be seen that the containers with a large shrinkage rate in container height after immersion in 90°C hot water for 10 seconds have poor sealing properties at the opening. [Industrial Applicability]

[0066] According to the present invention, it is possible to provide a container that can sufficiently prevent the occurrence of poor sealing between the opening of the container and the lid.

Claims

1. A container molded using a rubber-modified styrene-based resin composition and having a shrink label attached thereto, The container has a flange surface at an opening sealed by a lid, the height being 75 mm or more, the opening diameter being 25 mm or more, and the flange width of the flange surface being 3.0 mm or less, the rubber-modified styrene-based resin composition comprises a styrene-based resin and rubber-like polymer dispersion particles, and the content of the rubber-like polymer dispersion particles contained in the rubber-modified styrene-based resin composition is 15 to 25 mass %, The glass transition temperature measured in accordance with JIS K7121 is 96 to 106°C. A container, characterized in that the shrinkage rate in the height direction of the container when immersed in warm water at 90°C for 10 seconds is 0.25% or less.

2. The container described in claim 1, wherein the melt flow rate of the rubber-modified styrene-based resin composition is 1 to 50 g / 10 min.

3. 10. The container of claim 1 having a shrink label.

4. 4. The container according to claim 1, wherein the rubber-modified styrene-based resin composition contains liquid paraffin in an amount of 0.3 to 2.5% by mass based on 100% by mass of the rubber-modified styrene-based resin composition.

5. A method for manufacturing a container described in any one of claims 1 to 4, wherein the rubber-modified styrene-based resin composition is melted and then molded by an injection blow molding method.

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