Packaging container and method of manufacturing the same

Abstract

To provide a packaging container that has anti-fog properties and is suppressed from having worse appearance and thermally deforming even when a resin sheet including an anti-fog agent is heat-sealed at high temperature, and a method of manufacturing the same that can suppress the thermal deformation and melting of resin in the heat sealing.SOLUTION: A packaging container (1) has a container body (2) and a lid body (3), and is characterized in that: a main body flange part (23) of the container body (2) and a lid body flange part (33) of the lid body (3) are hermetically heat-sealed, and the lid body (3) has an inner surface coated with an anti-fog agent for anti-fog treatment, and also has an outer surface coated with silicone oil for silicone treatment, the silicone oil being applied by 20 mg / m2 or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention provides a packaging container that is sealed by heat sealing, has anti-fogging properties, and is suppressed from deteriorating in appearance and thermal deformation, as well as a method for producing a packaging container that can suppress thermal deformation and melting of the resin during heat sealing. [Background technology]

[0002] Conventionally, transparent packaging containers obtained by thermoforming highly transparent resins such as polyethylene terephthalate (PET) have been known. Such packaging containers are widely used, for example, as food packaging containers for containing various foods and distributing them on the market. Such packaging containers are usually composed of a container body and a lid that covers the container body. In general, packaging containers are hermetically sealed between the container body and the lid by heat sealing to prevent external foreign matter from entering the container body (Patent Documents 1 and 2).

[0003] Conventionally, most packaging containers have drop lids, and the contents are often kelp, old pickles, and lightly pickled vegetables. In such drop lid containers, the space between the contents and the lid is narrow, so the packaging container does not need to have anti-fogging properties.

[0004] In recent years, due to the variety of contents stored, top seals have also been adopted to improve workability and sealing, as well as for gas-replacement packaging. However, in recent years, there has been a demand for creating a sense of volume and freshness in the contents, and top seals have difficulty maintaining this sense of volume and freshness. Therefore, to solve this problem, packaging containers with raised lids have been adopted. However, raised lids have a larger space between the contents and the lid body than drop lids, and water vapor inside the container is likely to condense on the inside of the lid body, causing "fogging." Therefore, anti-fogging properties are required for packaging containers. For example, Patent Document 1 describes imparting anti-fogging properties by applying an anti-fogging agent to at least the inside of the covering portion of the lid body (

[0025] and

[0026] ).

[0005] Furthermore, silicone treatment of film surfaces has been practiced to improve the releasability and blocking properties of films. For example, Cited Document 3 discloses the formation of a silicone coating on the back surface of an anti-fog resin sheet material to improve blocking properties (claims). Patent Document 4 describes the application of silicone oil to the surface of a resin sheet to improve the releasability of a resin sheet coated with an anti-fog agent and a molded product obtained by thermoforming the sheet (

[0024] ). Patent Document 5 discloses that by blending a specific amount of silicone oil into a polymer mixture, the coefficient of friction of the film in an overheated state is improved and the occurrence of wrinkles is prevented, thereby obtaining a film with excellent appearance, adhesion, and sealing properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6882089 [Patent Document 2] Patent No. 4031515 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-280410 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-60633 [Patent Document 5] Special Publication No. 58-50591 Summary of the Invention [Problem to be solved by the invention]

[0007] Packaging containers are usually formed by thermoforming a transparent resin sheet, and if a resin sheet containing an anti-fogging agent is heat-sealed at a high temperature, the heat may impair the transparency and anti-fogging properties.

[0008] Heat sealing of a container body and a lid is usually performed by placing the lid on the container body and then pressing a seal head against the contact area between the container body and the lid. However, when the seal head is pressed against the container body and the lid, the resin that constitutes the container body and the lid melts and adheres to the seal head. Adhesion of the resin to the seal head can lead to poor appearance and thermal deformation of the manufactured packaging container, as well as reduced manufacturing efficiency of the packaging container. PET resin, which is used as a resin for transparent packaging containers, is prone to such problems due to its low softening temperature (70 to 80°C).

[0009] Furthermore, packaging containers sealed by heat sealing are usually provided with a tab extending horizontally from the side of the lid to open the lid. To facilitate opening and closing of the lid, it is desirable for the length and area of the tab to be large. However, it is known that the tab is susceptible to thermal deformation during heat sealing. In particular, the longer the length and area of the tab, the more susceptible it is to thermal deformation.

[0010] Therefore, an object of the present invention is to provide a packaging container that has anti-fogging properties and is suppressed from deteriorating in appearance and thermal deformation even when a resin sheet containing an anti-fogging agent is heel-sealed at high temperatures, and a method for manufacturing a packaging container that can suppress thermal deformation and melting of the resin during heat sealing. [Means for solving the problem]

[0011] The packaging container of the present invention (hereinafter referred to as "the present container") has a container body and a lid body, and the container body and the lid body are tightly attached by heat sealing. The inner surface of the lid body is anti-fogging treated by applying an anti-fogging agent, and the outer surface of the lid body is siliconized by applying silicone oil, and the amount of silicone oil applied is 20 mg / m 2 The present invention is characterized in that:

[0012] The method for producing a packaging container of the present invention (hereinafter referred to as "the method") includes a step of heat-sealing a container body and a lid, the inner surface of the lid being anti-fogging treated by applying an anti-fogging agent thereto, and the outer surface of the lid being siliconized by applying silicone oil thereto, and the amount of silicone oil applied is 20 mg / m. 2 The present invention is characterized in that: [Effects of the Invention]

[0013] The container has excellent anti-fogging properties even when heat-sealed at high temperatures, and is also prevented from deteriorating in appearance and thermal deformation due to resin welding during heat-sealing. According to the present method, resin welding during heat-sealing can be suppressed, and therefore, a decrease in production efficiency due to such welding can be suppressed, thereby enabling efficient production of packaging containers with excellent appearance. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an overall perspective view of a packaging container (1). [Figure 2] FIG. 1 is a cross-sectional view of a packaging container (1). [Figure 3] FIG. 1 is a plan view of a packaging container (1). [Figure 4] FIG. 2 is an enlarged view of the vicinity of the lid flange portion (33) of the packaging container (1). DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below. The embodiment is an example of implementing the present invention, and the present invention is not limited to the embodiment.

[0016] One embodiment of the present container is shown in Figures 1 to 4. The packaging container (1) has a container body (2) and a lid (3) that covers the container body (2).

[0017] The container body (2) has a body bottom wall (21), a body side wall (22) formed to surround the body bottom wall (21), and a body flange portion (23) extending horizontally from the upper end of the body side wall (22). The lid body (3) has a lid body upper wall (31), a lid side wall (32) formed to surround the lid body upper wall (31), and a lid body flange portion (33) extending horizontally from the lower end of the lid body side wall (32). The body flange portion (23) and the lid body flange portion (33) are tightly attached by heat sealing.

[0018] The container body is not particularly limited in terms of its shape, as long as it can accommodate the contents. Similarly, the lid is not particularly limited in terms of its shape, as long as it can cover the container body. Therefore, the container body may have a body bottom wall (21), a body side wall (22), and a body flange (23), or it may not have any of the above. Similarly, the lid may have a lid top wall (31), a lid side wall (32), and a lid flange (33), or it may not have any of the above.

[0019] The specific shapes of the container body and the lid can be appropriately selected taking into consideration the contents to be contained, etc. For example, the lid may be a conventional drop lid or a raised lid (see FIG. 1). Using a raised lid as the lid is preferable because it improves the appearance by suppressing clouding of the lid and maintains a sense of volume and freshness. Furthermore, the container body may be low in depth (height) (usually 30 mm or less, preferably 20 mm or less) or high in depth (height; typically more than 30 mm, preferably 70 mm or more). A low depth (height) of the container body is preferable because it provides excellent moldability and suppresses the occurrence of thickness deviations.

[0020] In this container, the container body and the lid are tightly attached by heat sealing. There are no particular limitations on the specific manner in which the container body and the lid are tightly attached by heat sealing. Typically, as in the packaging container (1), a body flange extending horizontally from the upper end of the container body and a lid flange extending horizontally from the lower end of the lid are provided, and the container body and the lid are tightly attached by heat sealing them together.

[0021] When the lid has a lid flange, a tab can be formed extending horizontally from the end of the flange. The tab is not in contact with the container body. Having the tab is desirable because it allows the lid to be opened easily. The tab has an uneven shape on at least one of its upper and lower surfaces. There are no particular limitations on the method for forming the uneven shape. The uneven shape can usually be formed by knurling. Having the uneven shape, particularly an uneven shape formed by knurling, on the tab is preferred because it can suppress thermal deformation of the tab when the container body and the lid are heat-sealed.

[0022] There is no particular limitation on the location where the tab is formed. Usually, the tab is formed at at least one of the four corners of the lid. In the packaging container 1, tabs 34 are formed at the four corners of the lid 3 (see Figures 1 and 3).

[0023] There are no particular limitations on the size and shape of the tab. Specifically, in the case of the packaging container (1) having an elongated or semicircular shape, the tab (34) is elongated and circularly provided in the diagonal direction from the four corners of the lid flange.

[0024] In this container, the tab can be elongated. Specifically, the length (h) from the end of the lid or the lid flange can be 3 mm or more (see Figure 4). The upper limit of this length can be appropriately set as needed. For example, the upper limit of the length can be 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm. A longer tab makes it easier to open the lid, but there is a risk of thermal deformation (warping, etc.) during heat sealing. As described above, the tab has an uneven shape, particularly an uneven shape formed by knurling, which is preferable because it can suppress thermal deformation during heat sealing between the container body and the lid, even if the tab is long, and also makes it easier to open the lid.

[0025] The container body and the lid can usually be obtained by thermoforming the resin sheets that constitute them. The specific method of thermoforming is not particularly limited, and known thermoforming methods, such as hot platen forming, vacuum forming, pressure forming, or vacuum pressure forming, can be used. The thermoforming conditions are also not particularly limited. The forming conditions can be appropriately determined as needed.

[0026] The layer structures of the container body and the lid are not particularly limited. Both the container body (2) and the lid (3) have a single-layer structure (see Figure 2), but the container body and the lid may have a single-layer structure or a multi-layer structure in which two, three, or four or more layers are laminated. Furthermore, the layer structures of the container body and the lid may be the same or different.

[0027] The materials of the container body and the lid are not particularly limited. The materials of the container body and the lid may be the same or different. Examples of resins constituting the container body and the lid include polyolefins (polyethylenes, polypropylenes, etc.) and polyesters. Polyester-based resins are preferred as the resin. It is more preferred that both the resins constituting the container body and the lid are polyester-based resins. When the container body and the lid have a multi-layer structure, the layers may be composed of the same resin or different resins.

[0028] Specific examples of the polyester resin include polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene-1,2-bis(phenoxy)ethane-4,4'-dicarboxylate, and polycyclohexylene dimethylene terephthalate. PET is preferred as the polyester resin. The PET may be a copolymer of terephthalic acid as an acid component and a single diol component, or may be a copolymer of two or more diol components.

[0029] The polyester resin may be in either a crystalline state or an amorphous state. From the viewpoint of moldability, the polyester resin is preferably an amorphous polyester resin, and more preferably an amorphous PET. The term "amorphous state" includes an uncrystallized state and a state in which the polyester is not completely crystallized. For example, "amorphous PET" includes PET in an uncrystallized state such as A-PET and PET in a completely uncrystallized state such as PET-G. The polyester resin is preferably an amorphous polyester resin, more preferably an amorphous PET, and even more preferably A-PET.

[0030] The conditions for heat sealing the container body and the lid are not particularly limited and can be adjusted appropriately as needed. For example, the temperature of the sealing head can be 150°C to 200°C, preferably 160°C to 180°C. The pressure of the sealing head can be 0.1 to 0.5 MPa. The time for pressing the sealing head can be 1 to 5 seconds.

[0031] In this container, the inner surface of the lid is anti-fogging treated by applying an anti-fogging agent. In this specification, the "inner surface" of the lid means the surface on the container body side (i.e., the side that holds the contents). Furthermore, if the lid has a lid flange, the surface of the lid flange that contacts the container body is the "inner surface." In Figure 2, to clarify that the inner surface of the lid (3) is anti-fogging treated, the anti-fogging treated portion is expressed as a layer (anti-fogging treated portion (35)). However, this expression is only for the convenience of explanation. In this container, the anti-fogging treatment does not necessarily form a layer.

[0032] The antifogging agent is not particularly limited in type as long as it can impart antifogging properties to the lid, and can be appropriately selected as needed. The antifogging agent may be a single type or a combination of two or more types. Sucrose fatty acid esters and water-soluble acrylic polymers can be used as the antifogging agent. Here, sucrose fatty acid esters are modified organic compounds formed by esterifying a fatty acid to at least one of the hydroxyl groups in a single sucrose molecule. Sucrose fatty acid esters include various ester forms, such as monoesters, diesters, and triesters. The HLB value of sucrose fatty acid esters is not particularly limited, but is preferably 10 to 20. On the other hand, water-soluble acrylic polymers are polymers obtained by polymerizing a monomer raw material containing at least an acrylic monomer, such as acrylic acid, alkyl acrylate, methacrylic acid, or alkyl methacrylate, and are prepared in a water-soluble state by, for example, neutralizing the acid component in the polymer with an alkali. The water-soluble acrylic polymers cooperate with sucrose fatty acid esters to enhance antifogging properties.

[0033] The anti-fogging treatment is not particularly limited in terms of the specific method and conditions, as long as it can coat the inner surface of the lid with the anti-fogging agent. The anti-fogging treatment is typically carried out by applying a liquid in which the anti-fogging agent is dissolved or dispersed in a solvent to the surface of the lid substrate layer using a conventional coating method, such as a spray, roll coater, gravure roll coater, bar coater, knife coater, or dip coater, followed by drying. The solvent may be water, an organic solvent, or an aqueous-organic mixed solvent. Examples of the organic solvent include hydrophilic organic solvents such as alcohols (e.g., methanol, ethanol, isopropanol, etc.). The anti-fogging treatment may be carried out once or multiple times. The liquid may contain only the anti-fogging agent, but may also contain other components in addition to the anti-fogging agent as long as they do not significantly adversely affect the effectiveness of the liquid.

[0034] In the packaging container 1, the inner surfaces of the lid upper wall 31, lid side wall 32, and lid flange 33 are anti-fogging treated (see Figure 2). However, the anti-fogging treatment may be applied to the entire inner surface of the lid, or only a part of it. Furthermore, the anti-fogging treatment may be applied after the lid is obtained by molding, but is usually applied to the resin sheet before molding.

[0035] In this container, the outer surface of the lid is siliconized by applying silicone oil. The "outer surface" of the lid means the surface on the outside of the lid (opposite the "inner surface"). When the lid has a lid flange, the surface of the lid flange opposite the "inner surface" is the "outer surface" of the lid. In FIG. 2, to clarify that the outer surface of the lid (3) is siliconized, the siliconized portion is depicted as a layer (silicone-treated portion (36)). However, this depiction is for convenience of explanation only. In this container, the siliconization does not necessarily form a layer.

[0036] Examples of the silicone oil include (halo)alkylpolysiloxanes such as dimethylpolysiloxane, diethylpolysiloxane, and trifluoropropylpolysiloxane; arylpolysiloxanes such as diphenylpolysiloxane; and alkylarylpolysiloxanes such as methylphenylpolysiloxane. The silicone oil may be a linear polysiloxane or a cyclic polysiloxane. Furthermore, the silicone oil may be a modified silicone oil, such as a silicone oil having a hydroxyalkyl group (e.g., a hydroxy C2-4 alkyl group such as a hydroxyethyl group), a polyoxyalkylene group, an amino group, an N-alkylamino group, a glycidyl group, an epoxy group, or a polymerizable group (e.g., a vinyl group, a (meth)acryloyl group). The silicone oils may be used alone or in combination of two or more types.

[0037] In this container, the amount of silicone oil applied is 20 mg / m 2 or more, preferably 25 mg / m 2 That is all. If the amount of silicone oil applied is less than the above range, it is not preferable because the melting of the resin constituting the container body or the lid and the adhesion to the seal head during heat sealing are insufficient. The upper limit of the amount of application can be appropriately set as needed. For example, the upper limit of the amount of application is 40 mg / m 2 , 45 mg / m 2 , 50 mg / m 2 , 55 mg / m 2 , or 60 mg / m 2 The amount of silicone oil to be applied is a value calculated based on the amount of solid content.

[0038] The form of the silicone oil is not particularly limited.The silicone oil can be used in various forms, but is usually used in the form of aqueous emulsion (aqueous emulsion in which silicone oil is emulsified and dispersed).As long as it does not significantly affect the effect, the aqueous emulsion may contain other components other than the silicone oil.

[0039] The silicone treatment is not particularly limited in terms of the specific method and conditions, as long as the silicone oil can be applied to the outer surface of the lid.The silicone treatment is usually carried out by applying the aqueous emulsion to the outer surface of the lid using a conventional application means, such as a spray, a roll coater, a gravure roll coater, a bar coater, a knife coater, a dip coater, etc., and then drying it.

[0040] In the packaging container (1), the outer surfaces of the lid top wall (31), lid side wall (32), and lid flange portion (33) are silicone-treated (see Figure 2). However, the silicone treatment may be applied to the entire outer surface of the lid, or only a portion thereof. However, at least the outer surface of the portion to be heat-sealed is silicone-treated. The silicone treatment may be applied after the lid is obtained by molding, but is usually applied to a resin sheet before molding.

[0041] The container body and the lid may contain other components as needed to the extent that the adhesiveness and transparency are not significantly impaired. Specific examples of the other components include additives used in known resin sheets, such as flame retardants, ultraviolet absorbers, fluorescent brighteners, antistatic agents, lubricants, antiblocking agents, flow improvers, plasticizers, dispersants, and antibacterial agents.

[0042] There are no particular limitations on the use of the present container. The present container can be used to store a variety of items. The present container can be suitably used as a food and beverage packaging container for storing food and beverages.

[0043] <Impossible or impractical circumstances> This container is a product invention, and the claims use the process expressions "anti-fogging by applying an anti-fogging agent" and "silicone-treated by applying silicone oil."

[0044] As already mentioned, the anti-fogging treatment and the silicone treatment do not necessarily result in the formation of a layer (anti-fogging layer, silicone layer), and even if they do form, it is not necessarily possible to clarify this using known analytical methods. In other words, it is not possible to clearly show how the anti-fogging treatment and the silicone treatment change the shape of the inner and outer surfaces of the lid. Therefore, describing the lid after each treatment as having an "anti-fogging layer" structure does not reflect the true nature of the invention, and it is impossible or even impractical to describe the true nature of the invention in terms of the structure or characteristics of a product (however, this explanation does not deny that a layer is formed by the anti-fogging treatment and the silicone treatment).

[0045] Therefore, even if the claims contain descriptions of methods such as "anti-fogging treatment by applying an anti-fogging agent" and "silicone treatment by applying silicone oil," the claims of this application satisfy the clarity requirement because, at the time of filing, it was impossible or almost impractical to directly identify the product by its structure or characteristics. [Example]

[0046] The present invention will be specifically described below with reference to examples. Note that the present invention is not limited to the embodiments shown in the examples. The embodiments of the present invention can be modified in various ways within the scope of the present invention depending on the purpose, application, etc.

[0047] (1) Manufacturing of packaging containers A-PET (PET resin "CB-602" manufactured by Far Eastern New Century Co., Ltd., thickness 0.35 mm x width 500 mm) was used as the polyester-based base sheet. Furthermore, a co-extruded multilayer film "DIFAREN E7800PET" (manufactured by DIC Corporation; layer structure: PET / LLDPE / LLDPE; thickness 30 μm) was used as the easy-open film. The surface of the polyester-based base sheet was subjected to a corona discharge treatment, and then the easy-open film was dry-laminated onto the treated surface so that the PET of the easy-open film was in contact with the polyester-based base sheet, thereby obtaining a resin sheet consisting of a base sheet layer and an easy-open film layer.

[0048] The resin sheet obtained by the above method was thermoformed by vacuum pressure forming at a surface temperature of 165°C to produce a container body (container size: length 152 mm, width 215 mm, height 30 mm). The outer surface of the container body was the base sheet layer, and the inner surface was the easy-open film layer.

[0049] The surface of the polyester base sheet was subjected to a corona discharge treatment, and then an anti-fogging treatment was performed by mixing an anti-fogging agent (sucrose fatty acid ester "LWA-1570" manufactured by Mitsubishi Chemical Foods Corporation (HLB value = 15, liquid, fixed content 40%) and a water-soluble acrylic polymer, polyacrylic acid alkyl ester copolymer "Jurymer FC-80" (liquid) manufactured by Nihon Junyaku Co., Ltd., in a solid content ratio of 1:3.8, applying the mixture to the treated surface, and drying. Next, an aqueous emulsion of silicone oil "SM 7025 EX Emulsion" manufactured by Toray Dow Corning Co., Ltd. (liquid, water-dispersible, solid content 34 wt%) was applied to the opposite surface of the polyester base sheet (application amount: 30 mg / m 2 ) and dried to perform the silicone treatment.

[0050] The polyester substrate sheet was then thermoformed by vacuum and pressure forming to produce a lid (3) (container size: length 152 mm, width 215 mm, height 30 mm). The inner surface of the lid (3) was treated with an anti-fogging agent (35), and the outer surface was treated with a silicone agent (36). The length (h) of the grip of the lid (3) was 4 mm.

[0051] The lid (3) was placed on the obtained container body (2) to cover it, and then the joint between the body flange portion (23) and the lid flange portion (33) was heat-sealed at a temperature of 170°C and a pressure of 0.2 MPa for 1.0 second to bond the container body (2) and the lid (3), thereby producing a packaging container.

[0052] As a comparative example, the amount of silicone oil applied was 15 mg / m 2 A packaging container was produced in the same manner as above, except that:

[0053] The packaging containers of the Examples could be manufactured without the resin melting during the heat sealing process, and the resulting packaging containers did not show any deterioration in appearance due to melting of the resin. Furthermore, no thermal deformation of the grip was observed. On the other hand, in the packaging containers of the Comparative Examples, the resin in the lid flange melted and adhered to the heat head during the heat sealing process. As a result, the resulting packaging containers had a deteriorated appearance at the lid flange. [Explanation of symbols]

[0054] 1; packaging container, 2; container body, 21; body bottom wall, 22; body side wall, 23; body flange portion, 3; lid body, 31; lid body top wall, 32; lid body side wall, 33; lid body flange portion, 34; grip portion, 35; anti-fogging treatment portion, 36; silicone treatment portion.

Claims

1. A packaging container having a container body and a lid body, the container body and the lid body being tightly sealed by heat sealing, The inner surface of the lid is anti-fogging treated by applying an anti-fogging agent thereto, The outer surface of the lid is siliconized by applying silicone oil, and the amount of the silicone oil applied is 20 mg / m ２ A packaging container characterized by the above.

2. 2. The packaging container according to claim 1, wherein at least one of the container body and the lid is made of a polyester resin.

3. 3. The packaging container according to claim 1, wherein the lid has a flange portion, and an end of the flange portion has a knob portion having an uneven shape formed on at least one of an upper surface and a lower surface.

4. a step of heat-sealing the container body and the lid body, The inner surface of the lid is anti-fogging treated by applying an anti-fogging agent thereto, The outer surface of the lid is siliconized by applying silicone oil, and the amount of the silicone oil applied is 20 mg / m ２ A method for producing a packaging container, characterized by the above.

5. The method for manufacturing a packaging container according to claim 3 , wherein at least one of the container body and the lid body is made of a polyester-based resin.

6. The method for manufacturing a packaging container according to claim 4 or 5, characterized in that the lid body has a flange portion, and the end of the flange portion has a knob portion having an uneven shape formed on at least one of the upper surface and the lower surface.

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