TW201425157A - Packing for food and drink container, and lid for liquid container and liquid container with lid using said packing - Google Patents

Abstract

To provide a packing for food and drink having a low risk of bad odor and infiltration of foreign substances. A packing used in a container for storing food and drink, characterized in comprising a foam body having closed cells obtained by impregnating a melted thermoplastic resin composition with a foaming agent and then reducing pressure, the foaming agent being supercritical carbon dioxide, and the foam body density being 40 to 300 kg/m<SP>3</SP>.

Description

Pad for food and beverage containers, lid for liquid container using the liner, and liquid container with lid

The present invention relates to a liner for a food container, and more particularly to a liner for use in a lid for a liquid container for a water server.

In the home or workplace, a water dispenser is provided so that the delicious water can be easily used as a beverage or the like. The water dispenser is provided in the following manner: a body including a faucet having a water outlet, and a water bottle is disposed on the body, so that there is always a delicious water flowing out from the faucet.

The water bottle is mounted on the main body such that the opening is located on the lower side. At this time, in order to prevent water from leaking to the outside, a gasket is provided on the lid of the water bottle. This liner is usually a foam using closed cells. However, if an odor is generated in the gasket, there is a problem that the odor is transferred to water to lower the quality of water. Therefore, in order to solve this problem, various studies have been conducted (for example, Patent Document 1).

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2010-30679

In addition to the problem of odor, the prior gasket sometimes has a problem of mixing black foreign matter inside the liner. Regarding the foreign matter, since the liner is used for foods and drinks, it is also considered a problem. Therefore, the object of the present invention is to provide A pad for food and drink that is used for the production of odors and the incorporation of foreign matter.

The present inventors have found that the reason for the incorporation of the odor and the foreign matter is the chemical foaming agent used in the foaming of the liner, and the present invention has been completed.

The present invention (1) is a pad for food and beverage containers, which is used for a container for accommodating foods and drinks; and is characterized in that it is obtained by impregnating a thermoplastic resin composition in a molten state with a foaming agent and then reducing the pressure. The foam having independent bubbles; the foaming agent is supercritical carbon dioxide; and the foam has a density of 40 to 300 kg/m ³ .

The present invention (2) is the pad for food and beverage containers according to the above aspect (1), wherein the number of the bubbles in the cross section of the foam is 100 to 500 / mm ² .

The present invention (3) is the pad for food and beverage containers according to the above aspect (1) or (2), wherein the ratio of the number of bubbles having a bubble diameter of 50 μm or less in the cross section of the foam is 50% of the whole. the above.

The liner for food and beverage containers according to any one of the above aspects of the invention, wherein the impregnation is carried out in a system having a temperature of 31 ° C or higher and a pressure of 7.3 MPa or more.

The pad for foods and drinks containers according to any one of the above aspects of the invention, wherein the foaming system is formed into a long sheet shape by extrusion molding under reduced pressure.

The pad for foods and drinks containers according to any one of the above aspects of the invention, wherein the thermoplastic resin composition comprises a polyolefin resin.

The invention (7) is a lid for a liquid container, which is a lid for a liquid container in which the opening portion is used vertically downward; and includes: a bottom portion; a cylindrical outer wall covering the outer circumference of the bottom portion, and a liquid-tight joint with the bottom portion; and a gasket disposed at least a peripheral portion of the bottom portion of the bottom portion of the cylindrical outer wall; and the gasket is as in any of the above inventions (1) to (6) A padding.

According to a seventh aspect of the invention, the liquid container cover of the invention of the present invention, comprising: a cylindrical inner wall provided on the inner side of the bottom outer portion of the cylindrical outer wall and having a liquid tightness with the bottom portion And a liquid outlet hole disposed inside the cylindrical inner wall of the bottom portion; the gasket is disposed between the outer wall and the inner wall of the bottom portion; and the liquid container cover is used for a water dispenser Bottle tank.

The present invention (9) is a covered liquid container comprising: the lid for a liquid container according to the above (7) or (8); and a liquid container comprising: a liquid container accommodating the liquid; and an opening portion The liquid is tightly connected to the liner provided on the bottom and the cylindrical outer wall of the lid.

The present invention (10) is a method for producing a liner, which is a method for producing a foam-containing liner for accommodating a food or beverage container; and includes the following steps: Melting the thermoplastic resin composition; impregnating the molten thermoplastic resin composition with a foaming agent; and decompressing the thermoplastic resin composition impregnated with the foaming agent to obtain the foam; and the foaming agent is supercritical carbon dioxide .

The invention of claim 11 is the method for producing a liner according to claim 10, wherein the step of impregnating is carried out in a system having a temperature of 31 ° C or more and a pressure of 7.3 MPa or more.

The present invention (12) is the method for producing a liner according to the above aspect (10) or (11), wherein the step of obtaining the above-mentioned foam is obtained by extrusion molding under reduced pressure to obtain a long sheet-like foam. Step; and The method for producing the above-mentioned liner further includes the step of obtaining a liner by punching from the long sheet-like foam.

According to the present invention, by using supercritical carbon dioxide as a foaming agent, the foaming agent becomes carbon dioxide of the gas after the production, and the effect of not causing odor or black foreign matter is exhibited. In addition, by selecting supercritical carbon dioxide as a foaming agent, a foam having a small bubble diameter and a fine foam can be obtained, so that bubbles generated in the foaming tend to be independent bubbles, and liquid tightness or airtightness is easily ensured. . Further, by selecting supercritical carbon dioxide in the supercritical gas, the diameter of the bubble does not become too small and becomes an appropriate size, so that the foam has moderate deformability and is held by the opening and the lid of the container. It becomes easy to form a liquid-tight structure between them.

The present invention is a liner which is used for ensuring liquid tightness or airtightness in a container for accommodating foods and drinks. The gasket of the present invention is characterized by comprising a foam having closed cells obtained by impregnating a thermoplastic resin composition in a molten state with a pressure-reducing agent, and the foaming agent is supercritical carbon dioxide. Unlike the case of using a chemical foaming agent, by using supercritical carbon dioxide, the foaming agent used in the production step becomes carbon dioxide of the gas, so that it does not become a cause of odor or black foreign matter, and even if it is mixed into foods and drinks. It will not cause harm to the human body. Further, by selecting the supercritical carbon dioxide, a foam having a small bubble diameter and fineness can be obtained, so that the bubbles generated in the foaming tend to be independent bubbles, and liquid tightness or airtightness is easily secured. Further, by selecting supercritical carbon dioxide in the supercritical gas, the bubble diameter does not become too small and becomes an appropriate size, so that the foam has moderate deformability and is held by the mouth and the lid of the container. It becomes easy to form a liquid-tight structure.

The foam used in the gasket of the present invention has a density of 40 to 300 kg/m ³ , preferably 40 to 250 kg/m ³ , more preferably 40 to 100 kg/m ³ , and most preferably 40 to 80. Kg/m ³ . The density of the foam was measured in accordance with JIS-K7222.

The number of bubbles in the cross section of the foam is preferably from 100 to 500 / mm ² , more preferably from 200 to 450 / mm ² , and still more preferably from 300 to 450 / mm ² . The number of the bubbles in the cross section of the foam is calculated from the average value of the number of bubbles included in the field of view of 1 mm × 1 mm which is arbitrarily determined at 8 or more points in the cross section obtained by cutting the foam. The number of bubbles having such a range means that bubbles are formed finely in the foam. Therefore, by setting such a range, it is effective to form a plurality of wall surfaces when a liquid is to be allowed to pass from one surface of the foam to the other surface, even if it is assumed that a defect containing a part of the connected bubbles is generated. The defect can also be compensated for by ensuring the independence of other bubbles, and as a result, the liquid becomes difficult to pass, and a high liquid tightness can be obtained.

In the case where a bubble is formed into an elliptical spherical foam by the formation of a continuous long strip by extrusion molding, the bubble becomes an ellipse in the cross section of the foam ( The direction parallel to the longitudinal direction, etc.), the direction in which the bubble becomes a circle (or an ellipse that becomes the smallest long diameter) (the direction perpendicular to the longitudinal direction). In this case, the number of the bubbles in the cross section of the foam is set to a value observed in a cross section perpendicular to the longitudinal direction.

It is preferable that the number ratio of the bubbles having a bubble diameter of 50 μm or less in the cross section of the foam is 50% or more with respect to the total number of the bubbles in the cross section. Further, it is preferable that the number ratio of the bubbles having a bubble diameter of 100 μm or less in the cross section is 80% or less with respect to the total number of the bubbles in the cross section. The ratio of the bubbles is calculated based on the distribution of the diameter and the number of the bubbles included in the field of view of 1 mm × 1 mm which is arbitrarily determined from the cross section obtained by cutting the foam. By including the bubbles in the range, the size of the bubbles is made small, so that it is easy to ensure the independence of the bubbles, thereby improving the liquid tightness.

In the case where a continuous elongated strip is formed by extrusion molding and the bubbles are formed into an ellipsoidal foam, the number of bubbles is set to be circular (or The value obtained by observing the cross section of the ellipse whose long diameter is the minimum value (the direction perpendicular to the longitudinal direction). Furthermore, when the bubble is not a spherical shape, it is perpendicular to the length direction. The diameter of the bubble was evaluated on the basis of the long diameter of the bubble shape in the cross section.

(foam)

The foam used in the present invention contains a foam material having closed cells obtained by mixing and extruding a thermoplastic resin composition in a molten state with a foaming agent.

Thermoplastic resin composition

The thermoplastic resin composition used in the foam preferably contains a polyolefin resin. The polymer used as the polyolefin resin is not particularly limited, and examples thereof include polypropylene (for example, random polypropylene, block polypropylene, homopolypropylene, high melt tension polypropylene), polyethylene, propylene-ethylene copolymer, and the like. .

The thermoplastic resin composition is not particularly limited, and a resin containing polypropylene is preferably used. The polypropylene to be used is not particularly limited as long as it is a polymer material containing a propylene monomer component, and examples thereof include polypropylene and a propylene-ethylene copolymer.

Further, the main component of the thermoplastic resin composition used herein has a MFR (Melt Flow Rate) of preferably 5 g/ at a melting temperature of 150 ° C or more and 230 ° C and 2.16 kgf as defined by JIS-K7210. It is 10 minutes or less, more preferably 3 g/10 minutes or less, further preferably 1 g/10 minutes or less. The main component of the thermoplastic resin composition is preferably a polypropylene material. Further, the main component means a component which accounts for the largest proportion (by weight) of the thermoplastic resin composition.

Further, the crystallization ratio of the polypropylene which is a preferred main component is preferably from 30 to 100%, more preferably from 30 to 80%, still more preferably from 30 to 70%. By setting it as the range, it is easier to cool and solidify at the time of foam molding, and it is possible to obtain fineness. Foam of microcells. Further, the crystallization ratio was calculated based on the measurement method of the transfer temperature of JIS-K7121 plastic. The sample which was previously melted at 200 ° C and cooled at a cooling rate of 10 ° C /min was melted at a temperature increase rate of 10 ° C / min to obtain a melting energy. As a comparative material, the degree of crystallization when the melting energy obtained by measuring the polypropylene resin having an MFR of 40 g/10 minutes or more at 230 ° C and 2.16 kgf as defined in JIS-K7210 was measured in the same manner. 100%, and the degree of crystallization of the sample to be evaluated was calculated. The homopolypropylene having an MFR of 40 g/10 minutes or more has a melting energy which is substantially fixed, so that it is judged to be saturated and a material having an MFR of 40 or more is used as a comparative material.

Further, the crystallization temperature (Tc) of the polypropylene which is a preferred main component is preferably from 90 to 130 ° C, more preferably from 95 to 130 ° C, still more preferably from 100 to 130 ° C. By setting it as this range, it is easy to cool-harden at the time of foam molding, and the foam of the micro-cells can be obtained. Further, the crystallization temperature was evaluated in accordance with JIS-K7121.

It is preferred to add a high melt tension polypropylene to the polypropylene of the above main component. The melt tension of the high melt tension polypropylene at 200 ° C is preferably from 5 to 50 cN, more preferably from 20 to 40 cN, and still more preferably from 25 to 35 cN. In the case of the addition, the melting temperature of the high melt tension polypropylene is preferably in the range of ±10 ° C with respect to the melting temperature of the main component, and the crystallization temperature of the high melt tension polypropylene is preferably relative to the crystallization temperature of the main component. It is ±25 ° C, more preferably ± 20 ° C. When the melting temperature is outside the above range, there is a possibility that dispersion is poor when kneading a plurality of materials. If the crystallization temperature is outside the above range, the molten resin which is bubbled by foaming may be cooled and solidified. The temperature becomes uneven and a fine bubble diameter cannot be obtained. The melting temperature and the crystallization temperature were calculated in accordance with JIS-K7121. The high-melt-tensile polypropylene can be used commercially, and specifically, "HMS-PP" of SunAllomer Co., Ltd., "NEWFOAMER" of Japan Polypropylene Co., Ltd., etc. are mentioned. The high melt tension polypropylene is preferably from 1 to 50 parts by weight, more preferably from 10 to 40 parts by weight, even more preferably from 20 to 30 parts by weight based on 100 parts by weight of the component of the thermoplastic resin composition. Parts by weight. By using polypropylene which exhibits high melt tension, the strain hardenability of the thermoplastic resin composition is increased, and the combination of the bubbles at the time of molding is suppressed, whereby a closed cell body having a small cell size can be obtained. In particular, by selecting atactic polypropylene as a main component of the thermoplastic resin composition and using a combination of high melt tension polypropylene, it is possible to obtain finer microcapsules.

Polyethylene may also be added to the above polypropylene. In the case of use, it is preferred to use a low density polyethylene in polyethylene. The density of the low density polyethylene is preferably 910 to 940 kg/m ³ , more preferably 915 to 938 kg/m ³ , and further preferably 920 to 935 kg/m ³ . The content of the low-density polyethylene is preferably from 20 to 80 parts by weight, more preferably from 25 to 60 parts by weight, even more preferably from 30 to 60 parts by weight, based on 100 parts by weight of the component of the thermoplastic resin composition. 50 parts by weight. By containing low density polyethylene, flexibility can be obtained and strain can be easily improved.

The content of the polyolefin resin is preferably from 30 to 80 parts by weight, more preferably from 40 to 80 parts by weight, still more preferably from 45 to 80 parts by weight, still more preferably from 60 to 80 parts by weight, based on 100 parts by weight of the total amount of the thermoplastic resin composition. 80 parts by weight. Less than 30 parts by weight, that is, an elastomer (such as ethylene propylene rubber) or a foaming nucleating agent (for example) In the case where the content of cerium oxide or the like is large, there is a case where deflation occurs and the expansion ratio becomes low (that is, the density becomes high), which is unsatisfactory (in the case where the elastomer is large), and the obtained foam Hardening (in the case of more foaming nucleating agents). On the other hand, in the case of more than 80 parts by weight, the obtained foam cannot obtain flexibility and is not preferable as a liner. The content of the polypropylene is preferably 30 to 90 parts by weight, more preferably 40 to 90 parts by weight, still more preferably 70 to 90 parts by weight, particularly preferably 75 to 85 parts by weight, based on 100 parts by weight of the total of the polyolefin resin. . When it is this range (30-90 weight part), it can obtain the cushioning which has a higher expansion ratio and is more excellent in flexibility. Further, the content of the polypropylene which is a preferred main component is preferably 20 to 80 parts by weight, more preferably 30 to 70 parts by weight, still more preferably 30 to 60 parts by weight, based on 100 parts by weight of the total amount of the thermoplastic resin composition. . When it is this range (20-80 weight part), it can obtain the cushioning which has a higher expansion ratio and is more excellent in flexibility.

Further, the thermoplastic resin material may contain an elastomer, a pigment, an antioxidant, a foaming nucleating agent, a crystal nucleating agent, and the like.

The elastomer is not particularly limited, and examples thereof include thermoplastic elastomers such as a styrene elastomer or an ethylene propylene diene rubber or an ethylene propylene rubber. By containing these elastomers, the effect of imparting flexibility to the foam is exhibited. The MFR of the elastomer is not particularly limited, and the MFR at 230 ° C and 2.16 kgf as specified in JIS-K7210 is preferably 0 to 5 g/10 min, more preferably 0 to 4 g/10 min, and further preferably 0. ~3 g/10 minutes. The content of the elastomer is preferably from 0.1 to 80 parts by weight, more preferably from 20 to 75 parts by weight, even more preferably from 40 to 75 parts by weight, based on 100 parts by weight of the component of the thermoplastic resin composition. 60 parts by weight.

The pigment is not particularly limited, and examples thereof include titanium oxide and the like. The content of the pigment is preferably 0.1 to 25 parts by weight, more preferably 0.1 to 20 parts by weight, still more preferably 0.1 to 15 parts by weight, per 100 parts by weight of the component of the thermoplastic resin composition. .

The antioxidant is not particularly limited, and examples thereof include Adekastab AO-60 manufactured by ADEKA Co., Ltd. or Irganox 1010 manufactured by BASF Japan Co., Ltd. as a phenolic antioxidant. The content of the antioxidant is preferably 0.1 to 3.0 parts by weight, more preferably 0.1 to 1.0 part by weight, still more preferably 0.15 to 0.5 part by weight based on 100 parts by weight of the component of the thermoplastic resin composition. Share.

The foaming nucleating agent is not particularly limited, and examples thereof include cerium oxide and talc. The bubble size obtained can be adjusted by using a foaming nucleating agent. The content of the foaming nucleating agent is not particularly limited. For example, it is preferably 0.1 to 20 parts by weight, more preferably 1 to 15 parts by weight based on 100 parts by weight of the component of the thermoplastic resin composition. The portion is further preferably 2 to 10 parts by weight. If it is less than 0.1 part by weight, foaming becomes easy to occur at the same time at any position. In this case, if there is a position where foaming occurs intensively, it is possible that the bubbles are combined with each other at this position to form coarser cells (bubbles having a larger diameter). On the other hand, when it exceeds 10 parts by weight, the softness of the obtained foam may be impaired.

The crystal nucleating agent is not particularly limited, and examples thereof include Gel All of New Japan Physical and Chemical Co., Ltd., Adekastab NA11 of ADEKA Co., Ltd., and the like.

The foaming agent used in the liner of the present invention is produced by the following steps: The thermoplastic resin composition is melted; the molten thermoplastic resin composition is impregnated with a foaming agent; and the thermoplastic resin composition impregnated with the foaming agent is decompressed to obtain the foam. Here, the above blowing agent is supercritical carbon dioxide. Hereinafter, each step will be described in detail.

First, the thermoplastic resin composition is melted. More specifically, each component of the thermoplastic resin composition is placed in an extruder of a single type or a tandem type (a type in which two extruders are connected), and is melted in a molten region. Further, it is preferred that the thermoplastic resin material used in this step is melt-mixed by using a resin mixing machine such as a 2-axis extruder, a kneader or a Banbury mixer. Granulated.

In the subsequent step, the molten thermoplastic resin composition is impregnated with a foaming agent. The blowing agent used herein is supercritical carbon dioxide. The injection nozzle provided in the vicinity of the melting zone ejects carbon dioxide which has been supercharged by the gas supply to the supercritical state, and is melted into the melted thermoplastic resin composition. The supercritical carbon dioxide is introduced into an extruder and melted in the molten thermoplastic resin composition to be in a state in which the foaming agent is melted in the thermoplastic resin composition.

By using the supercritical carbon dioxide used herein, the micropore diameter of the foam can be made fine. Further, the pressure of the supercritical carbon dioxide must be 7.3 MPa or more, more preferably 8 MPa or more, and still more preferably 9 MPa or more. Further, although the upper limit is not particularly limited, it is, for example, 20 MPa or less.

In the next step, the thermoplastic resin composition impregnated with the above foaming agent is decompressed to obtain the above-mentioned foam. Introducing supercritical carbon dioxide into the molten thermoplastic resin composition in an extruder and setting the temperature to 31 ° C or higher. The state of the pressure of 7.3 MPa or more is maintained until the state is ejected from the die port and depressurized under atmospheric pressure to maintain the state, whereby a foam having small and fine foamed micelles can be obtained. Further, by setting the temperature to 31 ° C or higher and the pressure to 7.3 MPa or more, the carbon dioxide can be kept in a supercritical state, so that the thermoplastic resin composition and the supercritical carbon dioxide can be uniformly mixed with each other. The upper limit of the temperature is not particularly limited. For example, the temperature at which the thermoplastic resin composition is not thermally decomposed can be set, for example, 300 °C.

Further, in the mixing of the thermoplastic resin composition and the supercritical carbon dioxide, it is preferred to use two or more extruders (tandem type extruders), and the step of performing the mixed extrusion treatment is longer, and The temperature of the mixture is lowered or the like to adjust the temperature so as not to be released into the atmosphere to be equal to or lower than the above pressure. The thermoplastic resin composition before being foamed preferably has a temperature near the pour point of the composition. By keeping the temperature low, the pressure difference before and after the foaming becomes large, and a large number of bubble growth nuclei are generated, whereby a fine foam can be obtained. Further, after foaming, the thermoplastic resin composition can be cooled and solidified more rapidly. Therefore, the growth of the bubbles can be stopped at an early stage, and the foam of the closed cells having a small micropore diameter can be easily obtained.

The mold structure in the extruder is not particularly limited, and examples thereof include a T-die and a circular die. Among these, in order to obtain a foamed sheet having a uniform thickness, a circular mold is preferred. In the case of using a circular mold, a cylindrical foam can be obtained, but it can be formed into a sheet shape by cutting one side. Thus, at the time of extrusion molding, the long sheet-like foam can be directly formed by directly selecting a T-shaped mold, or the continuous sheet-shaped foam can be continuously formed by selecting a circular mold through a cylindrical foam. body. Further, by punching, etc. The strip-shaped foam was cut out to form a shape of a liner.

The above foaming system is used as a liner for food and beverage containers. Fig. 1 is a schematic configuration diagram of a liner for a food and beverage container of the present invention. The food product container liner 1 of the present invention comprises a disk-shaped body 11 and a circular hole 13 formed in the center of the body. Since the liner is composed of a foam obtained by foaming using the above-described supercritical carbon dioxide, the odorless or black residue remains and becomes a clean liner. By selecting supercritical carbon dioxide as a foaming agent, the obtained microcapsules of the foam are finer, and the microcells are independent bubbles, so that they have moderate flexibility and high liquid tightness.

Moreover, the liner 1 for food and beverage containers of the present invention is preferably a lid for a liquid container. Fig. 2 is a schematic configuration diagram of a lid for a liquid container of the present invention. 2(a) is a plan view, FIG. 2(b) is a perspective view, and FIG. 2(c) is a cross-sectional view taken along line AA'.

The liquid container cover 2 includes a disc-shaped bottom portion 21, a cylindrical outer wall 23 covering the outer periphery of the bottom portion, and being fluid-tightly engaged with the bottom portion; a cylindrical inner wall 25 disposed at the bottom portion The inner side of the cylindrical outer wall is fluid-tightly joined to the bottom portion; the liquid lead-out hole 27 is disposed inside the cylindrical inner wall of the bottom portion; and the gasket 1 is disposed on the bottom portion Part between the outer wall and the inner wall. Here, the liner 1 is the liner of the present invention as described above.

The lid 2 for a liquid container is attached to an opening of a liquid container 3 or the like for a bottle of a water dispenser. 3 is a cross-sectional view showing a state in which the lid 2 for a liquid container of the present invention is attached to an opening of the liquid container 3. The liquid container 3 includes a liquid container body 31 that houses a liquid, and an opening portion 33 that is fluid-tightly connected to a gasket provided on the bottom portion and a cylindrical outer wall of the lid. Here, the opening end 33a of the opening of the liquid container is attached so as to be in close contact with the gasket 1, so that the liquid in the liquid container body does not leak from between the opening 33 and the outer wall 23 of the cylindrical inner wall. structure.

As shown in FIG. 4, the liquid container 3 to which the liquid container lid 2 is attached is attached to the water dispenser main body 4, and it is used. The water dispenser main body 4 includes a mounting opening 41 through which the liquid container 3 is attached via the liquid container cover 2, and a faucet 42 for discharging the liquid conveyed from the mounting opening. More specifically, the liquid in the liquid container is supplied to the mounting port 41 of the water dispenser via the liquid outlet hole 27 of the lid 2 for the liquid container. Thus, the structure is such that even if the opening of the liquid container is attached downward to the water dispenser body, the liquid does not leak out by the gasket.

Example (Example 1)

A two-axis extruder manufactured by Nippon Steel Co., Ltd. is further mixed with JIS- in a 100 parts by weight of atactic polypropylene having an MFR of 0.5 g/10 minutes at 230 ° C and 2.16 kgf as the main component of JIS-K7120. The melting temperature specified by K7121 is 25 parts by weight of a high melt tension polypropylene (melt tension 26 cN) within a negative 10 ° C relative to the main component (the above-mentioned random polypropylene), and a weight of 931 kg/m ³ of polyethylene 30 5 parts by weight of ethylene propylene rubber of 230 ° C and 2.16 kgf as defined in JIS-K7210, which is 0 (that is, no flow), 9 parts by weight of cerium oxide as a foaming nucleating agent, and further 3 parts by weight of pigment The obtained thermoplastic resin composition is melted and prepared, and after impregnating supercritical carbon dioxide under the conditions of a temperature of 31 ° C or higher and a pressure of 7.3 MPa or more, the molten material is extruded to produce a foamed sheet. The bubble shape of the obtained foam sheet was an independent bubble. The foam density was 60 kg/m ³ . Further, a cross section perpendicular to the extrusion direction of the foamed sheet (Fig. 5) was measured by SEM (Scanning Electron Microscope), and a range of 1 mm × 1 mm was measured at any eight points. After the number of micelles contained therein was calculated and the average value was calculated, the number of micelles was 250/mm ² . Further, when the distribution of the size (diameter) of the micelles was calculated from the cross section, the ratio of the number of bubbles of 50 μm or less was 60%, and the ratio of the number of bubbles of 100 μm or less was 84% (Fig. 6). The liner of Example 1 was produced by cutting the foam sheet.

(Examples 2 to 5)

The liners of Examples 2 to 5 were produced in the same manner as in Example 1 except that the compositions in Table 1 were used. The results are shown in Table 1.

Homopolymer: MFR = 0.5 g/10 min, crystallization rate = 58%, crystallization temperature = 113 ° C, melting temperature = 172 ° C

Atactic polypropylene: MFR = 0.5 g/10 min, crystallization rate = 48%, crystallization temperature = 104 ° C, melting temperature = 152 ° C

High melt tension polypropylene (R-PP system): melt tension = 26 cN, melting temperature = 146 ° C, crystallization temperature = 116 ° C

High melt tension polypropylene (H-PP system): melt tension = 32 cN, melting temperature = 164 ° C, crystallization temperature = 131 ° C

Polyethylene: density 931 kg/m ³

(Comparative example)

Further, as a comparative example, the foam was observed by foaming a low-density polyethylene by a chemical foaming agent (VINYFOR AC #3 manufactured by Yonghe Chemical Industry Co., Ltd., decomposition temperature: 210 ° C), and the result was observed. The number of micelles in the section was 101/mm ² . Further, when the distribution of the size (diameter) of the micelles was calculated, the bubbles of 50 μm or less were 19%, and the bubbles of 100 μm or less were 34%.

With respect to the above chemical foaming agent, after measuring the thermogravimetric change under the conditions of argon gas of 250 ml/min and a temperature increase of 20 ° C/min from room temperature to 550 ° C, about 1% of the residue (carbide) was produced. (Figure 7).

Further, the monomer for chemical foaming agent (VINYFOR AC #3 manufactured by Yonghe Chemical Industry Co., Ltd., decomposition temperature: 210 ° C) was heated from room temperature to 250 ° C / min at an increase rate of 20 ° C / min. After 210 ° C (about 9 minutes), the thermogravimetric change was measured by isothermal holding for 30 minutes, and as a result, 20% of the residue was produced (Fig. 8).

Further, in Fig. 7, the horizontal axis represents temperature (°C), and the right vertical axis represents weight loss (%). In Fig. 8, the horizontal axis represents the time elapsed since the temperature rise (min), and the right vertical axis represents the weight loss (%). ). From the above results, it is understood that the chemical foaming agent is generated by thermal decomposition even if it is heated to a temperature higher than the decomposition temperature.

In addition, the foam which is foamed by the mechanical frothing process is not a closed cell, but is a semi-connected bubble containing a large number of connected bubbles, and thus is not excellent in liquid tightness.

Industrial availability

According to the present invention, since the chemical foaming agent is not used, it is possible to provide a liner for food and beverage containers having high safety.

1‧‧‧Patient for food and beverage containers

2‧‧‧Liquid for liquid containers

3‧‧‧Liquid container

4‧‧‧Water dispenser body

11‧‧‧Ontology

13‧‧‧round hole

21‧‧‧ bottom

23‧‧‧Cylindrical outer wall

25‧‧‧Cylindrical inner wall

27‧‧‧Liquid outlet hole

31‧‧‧Liquid container body

33‧‧‧ openings

33a‧‧‧ front end

41‧‧‧Installation port

42‧‧‧Water tap

Fig. 1 is a schematic configuration diagram of a liner for a food and beverage container of the present invention.

2 is a schematic configuration view of a lid for a liquid container according to the present invention. In detail, FIG. 2(a) is a plan view, FIG. 2(b) is a perspective view, and FIG. 2(c) is a cross-sectional view taken along line AA'.

3 is a cross-sectional view showing a state in which the lid 2 for a liquid container of the present invention is attached to an opening of the liquid container 3.

Fig. 4 is a view showing a state in which the liquid container 3 to which the liquid container lid 2 is attached is attached to the water dispenser body 4.

Fig. 5 is a SEM photograph (A to D) of a cross section of the foam of Example 1.

Fig. 6 is a distribution of the number of bubble diameters of the foam of Example 1.

Fig. 7 is a view showing the thermal decomposition test of the foam used in the comparative example.

Fig. 8 is a view showing the thermal decomposition test of the foaming agent used in the comparative example.

1‧‧‧Patient for food and beverage containers

11‧‧‧Ontology

13‧‧‧round hole

Claims (12)

A food or beverage container liner for use in a container for accommodating foods and drinks, comprising: a foam having independent bubbles obtained by impregnating a thermoplastic resin composition in a molten state with a foaming agent The foaming agent; the foaming agent is supercritical carbon dioxide; and the foam has a density of 40 to 300 kg/m ³ . A pad for a food and beverage container according to claim 1, wherein the number of the bubbles in the cross section of the foam is 100 to 500 / mm ² . The food or beverage container liner according to claim 1 or 2, wherein a ratio of the number of bubbles having a bubble diameter of 50 μm or less in the cross section of the foam is 50% or more of the whole. The pad for food and beverage containers according to any one of claims 1 to 3, wherein the impregnation is carried out in a system having a temperature of 31 ° C or higher and a pressure of 7.3 MPa or more. The pad for food and beverage containers according to any one of claims 1 to 4, wherein the foaming system is continuously formed into a long sheet shape by extrusion molding under reduced pressure. The liner for food and beverage containers according to any one of claims 1 to 5, wherein the thermoplastic resin composition comprises a polyolefin resin. A liquid container cover for use in a liquid container for opening an opening portion, and comprising: a bottom; a cylindrical outer wall covering the outer periphery of the bottom portion, and the bottom liquid And a gasket disposed at least in a peripheral portion of the bottom outer wall of the cylindrical outer wall; and the gasket is a gasket according to any one of claims 1 to 6. The lid for a liquid container according to claim 7, comprising: a cylindrical inner wall provided on the inner side of the bottom outer portion of the cylindrical outer wall and being fluid-tightly joined to the bottom portion; and a liquid outlet hole, The gasket is disposed on the inner side of the cylindrical inner wall of the bottom portion; the gasket is disposed between the outer wall and the inner wall of the bottom portion; and the lid for the liquid container is used for the bottle of the water dispenser. A capped liquid container comprising: a lid for a liquid container according to claim 7 or 8; and a liquid container comprising: a liquid container accommodating the liquid; and an opening portion opposite to the pad provided at the bottom portion The cylindrical outer wall of the cover is fluidly connected. A method for producing a liner for producing a foam-containing liner for accommodating a food or beverage container, and comprising the steps of: melting a thermoplastic resin composition; impregnating the molten thermoplastic resin composition with foam And removing the thermoplastic resin composition impregnated with the foaming agent to obtain the foam; and the foaming agent is supercritical carbon dioxide. The method for producing a liner according to claim 10, wherein the step of impregnating is carried out in a system having a temperature of 31 ° C or more and a pressure of 7.3 MPa or more. The method for producing a liner according to claim 10, wherein the step of obtaining the foam is a step of extruding at a reduced pressure to obtain a long sheet-like foam; and the method for producing the liner is further The step of obtaining a liner by punching from the above-mentioned long sheet-like foam is included.