JP2009096525A - Food container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensively producible pillared food container provided with sufficient heat insulating property and drop impact resistance. <P>SOLUTION: A blank sheet 10 is tubularly rolled to form a side wall part 70. A pillar shaped part 20 is injection molded between both of the opposing side edges of the sheet 10. The second pillar shaped part 30 roughly in the same shape and size as the part 20 is formed on the opposing side of the part 20. A bottom part 40 is injection molded wholly on the bottom end opening part of the sheet 10. A bottom rim 41 is formed on the part 40. A frame part 50 is injection molded on the top end peripheral edge of the sheet 10. A flange part 51 is formed on the peripheral edge of the part 50. A stepped part 60 is formed from roughly one third the height from the bottom of the part 20 and the part 30 to the bottom part 40. The blank sheet is provided with a foamed resin layer. The injection mold resin is the same type resin used for the foamed resin layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pillared container for storing a blank sheet in an injection mold and injecting an injection molding resin to form a cup-shaped container, and more particularly to a food container suitable for storing food. is there.

  In recent years, three-dimensional containers are lighter, stronger and cheaper than glass bottles and metal cans, and plastic containers are increasing year by year. Plastic containers are bowl-shaped, lunch box-shaped, and containers such as trays that are shallowly squeezed are often made of molded products from sheets such as vacuum, vacuum / pressure forming, etc., because of their high productivity. However, in the case of a container having a large L / D (depth / caliber, the same applies hereinafter), since the sheet is stretched in a molded product from the sheet, uneven thickness tends to occur, so there are many injection molded containers that do not cause uneven thickness. It is used.

However, since the injection-molded container is made of a solid resin of 100% resin, the heat insulation is inferior, and when hot food or cold food is put, it is too hot or too cold for a long time. It was something that could not be held by hand. Moreover, in order to obtain the required rigidity and strength as a container, a certain amount of thickness was required as a whole.
Furthermore, in recent years, countermeasures against global warming have been screamed, and in particular, reduction of petroleum resource consumption that cannot be regenerated is desired.

  Therefore, in recent years, as a container having a large L / D, a pillar container capable of improving the above-described problems of the injection molded container has been frequently used. In this pillar container, generally, a blank sheet mainly composed of a paper layer is accommodated in a cylindrical shape in an injection molding machine mold, and an injection molding resin is applied to a butt portion at the side end portion and an opening portion at the upper and lower ends of the blank sheet. It is formed by injection filling (see Patent Document 1).

  By the way, in the pillared container, generally, the blank sheet used as the peripheral wall portion of the pillared container is coated on the inner side of the base material layer mainly made of paper in order to improve the adhesiveness with the skeleton member formed of the injection resin. A heat-adhesive resin layer such as PP is provided. However, in the blank sheet composed of the base material layer and the heat-adhesive resin layer, the blank sheet may be broken at the joint portion with the skeleton member due to an impact such as dropping.

  Therefore, in Patent Document 1, a blank plate (blank sheet) is formed by laminating a heat-adhesive resin layer on a base material layer through a biaxially stretched film having a high tensile strength, and can withstand an impact at the time of dropping. It is what I did.

Japanese Patent Laid-Open No. 9-207936

  However, in the pillared container proposed in Patent Document 1 described above, the cost of the biaxially stretched film, the cost of the AC agent for integration with the base material layer, the cost of the melt-extruded PP, and the processing cost for integration. There was a problem of increasing.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a food container that has sufficient heat insulation properties, is resistant to drop impact, and can be manufactured at low cost.

  The present inventors have intensively studied to solve the above-mentioned problems, and by providing a foamed resin layer on the blank sheet and making the resin used for the foamed resin layer and the injection-molded resin the same kind of resin, sufficient It has been found that heat insulation can be ensured, the blank sheet and the skeleton are completely integrated, extremely resistant to drop impacts, etc., and can be manufactured at low cost, and the present invention has been completed.

  In the food container according to claim 1, a blank sheet serving as a side wall portion of the container is wound and stored in a mold of an injection molding machine, and between the opposite side edges of the blank sheet, the entire lower end opening, and the upper end opening. A container for forming a frame part having a columnar part, a bottom part, and a flange by injection-filling a peripheral part with injection molding resin, wherein the blank sheet has a foamed resin layer, and the resin and the injection of the foamed resin layer The molding resin is the same kind of resin.

  In the food container according to claim 2, the blank sheet which becomes the side wall part and the bottom part of the container is wound and stored in the mold of the injection molding machine, and between the opposite side edges of the blank sheet, the entire bottom part or A container for forming a frame portion having a columnar portion, a bottom portion or a thread bottom portion, and a flange by injection-filling injection molding resin at least at a portion forming a thread bottom at the bottom surface portion and an upper end opening periphery, The blank sheet has a foamed resin layer, and the resin of the foamed resin layer and the injection molding resin are the same type of resin.

  The food container according to claim 3 is characterized in that, in the food container according to claim 1 or 2, the resin of the foamed resin layer is PE resin, PP resin or PET resin.

  A food container according to claim 4 is characterized in that, in the food container according to claim 1, 2, or 3, the blank sheet has a smooth unfoamed layer on at least one surface of the foamed resin layer. Has been.

  A food container according to claim 5 is the food container according to claim 1, 2, 3 or 4, wherein the blank sheet has an oxygen gas barrier layer.

Food container according to claim 6, in food containers according to claim 5, the oxygen gas barrier layer, EVOH film, PVDC film, MXD6-NY film, Al foil, SiOx-deposited PET film, _Al 2 _{O 3} deposited PET film Or a poly (meth) acrylic acid polymer / saccharide mixed polymer coated PET or O-NY film.

  A food container according to claim 7 is the food container according to claim 1, 2, 3, 4, 5 or 6, wherein the foamed resin layer is a foamed resin layer foamed by gas foaming. ing.

  In the food container according to claim 1, a blank sheet mainly composed of a foamed resin layer is wound and stored in a side wall portion occupying most of the container in a mold of an injection molding machine, and between the opposing side edges of the blank sheet The skeleton of the (columnar portion), the entire lower end opening (bottom portion), and the upper end opening periphery (frame portion having a flange) is formed by injecting the same type of resin as that of the blank sheet resin. Therefore, heat insulation as a container can be ensured with a small amount of resin, and the blank sheet and the skeleton are firmly integrated by fusion, so that they do not break even during a drop impact. Further, the columnar part can sufficiently resist the pressure from the upper part, and the lid member can be heat sealed by the flange of the frame part.

  In the food container according to claim 2, as in the case of claim 1 described above, the heat insulating property is not broken upon a drop impact. Furthermore, since the blank sheet is also present at the bottom portion, when providing the container with oxygen gas barrier properties, the oxygen gas barrier properties can be easily ensured by providing the blank sheet with an oxygen gas barrier layer.

  In the food container according to the third aspect, since the resin of the foamed resin layer is PE resin, PP resin, and A-PET resin, the container can be made low in cost and excellent in food safety and hygiene.

  In the food container according to claim 4, since printing can be performed on the surface of the smooth unfoamed layer, cosmetics can be obtained, which is preferable in appearance.

  In the food container according to the fifth aspect, since the blank sheet is composed of the foamed resin layer and the oxygen gas barrier layer, the container can be provided with oxygen gas barrier properties.

In the food container according to claim 6, oxygen gas barrier layer, EVOH film, PVDC film, MXD6-NY film, Al foil, SiOx-deposited PET film, _Al 2 _{O 3} deposited PET film, or poly (meth) acrylic acid Since it is a PET or O-NY film coated with a mixed polymer of a polymer and a saccharide, it can be manufactured at low cost.

  In the food container according to claim 7, since the foamed resin layer is a resin layer formed by gas foaming, the gas is replaced with air over time, which is preferable in terms of food safety and hygiene.

  In the food container of the present invention, the blank sheet has a foamed resin layer. This foamed resin layer is generally produced by chemical foaming or gas foaming. Chemical foaming includes sodium hydrogen carbonate which generates gas by heat, azo compounds such as azodicarbonamide, azide compounds such as P-toluenesulfonyl azide, nitroso such as N, N′-dinitrosopentamethylenetetramine. A chemical foaming agent such as a compound is kneaded with a resin, and is extruded from an extruder and foams when the pressure of the outside air (1 atm) is reached. Chemical foaming always leaves foaming residue in the sheet, especially azo compounds, azide compounds, nitroso compounds, etc., because there is a risk of forming carcinogenic amine compounds. It is not preferable. In the gas foaming, carbon dioxide gas, butane gas, nitrogen gas or the like is fed into the resin of the extruder, and the gas is foamed when the pressure of the outside air is reached from the extruder. In addition, recently, it is also possible to use a technique in which carbon dioxide gas is fed into an extruder to be supercritical (intermediate between liquid and gas) and extruded.

  Examples of the resin used for the foamed resin layer include PE resin, PP resin, and PET resin. The expansion ratio of the foamed resin layer is preferably 1.3 to 5.0 times, and more preferably 1.5 to 3.0 times. When the expansion ratio is less than 1.3 times, the heat insulating property is inferior. When the expansion ratio exceeds 5.0 times, the foam cells become large and the waist as a sheet is lost. The thickness of the foamed resin layer is preferably 0.3 to 1.5 mm, and more preferably 0.5 to 1.0 mm. When the thickness is less than 0.3 mm, there is no waist as a sheet, and when it exceeds 1.5 mm, only the cost is increased.

  A smooth unfoamed layer can be provided on one surface of the foamed resin layer. By providing a smooth unfoamed layer, printing can be performed, which is preferable in terms of cosmetics. In order to provide a smooth unfoamed layer, a film of the same resin as the resin of the foamed resin layer may be laminated by dry lamination, or the foamed resin layer and the unfoamed layer may be coextruded by a coextrusion method.

  The thickness of the unfoamed layer is preferably 15 to 80 μm, and more preferably 20 to 50 μm. When the thickness is less than 15 μm, there is no inexpensive commercially available film when laminating by dry lamination, and uniform coextrusion is difficult by the coextrusion method. When the thickness exceeds 80 μm, the heat insulating property is deteriorated, and the effect of reducing the resin is lost.

  An oxygen gas barrier layer can be provided on the blank sheet. By providing the oxygen gas barrier layer, it is possible to prevent oxygen from entering the container, so that foods and the like can be stored for a longer period of time. In order to provide an oxygen gas barrier layer, when the oxygen gas barrier layer is an EVOH resin layer, a PVDC resin layer, or an MXD6-NY resin layer, a two-kind / three-layer co-extrusion machine is used, The both sides can be laminated by coextrusion with a foamed resin layer as a foamed resin layer / oxygen gas barrier layer / foamed resin layer. Further, using an EVOH film, a PVDC film, and an MXD6-NY film, they can be laminated on one surface of the foamed resin layer by dry lamination.

As oxygen gas barrier layer, in the case of using an Al foil, SiOx-deposited PET film, _Al 2 _{O 3} deposited PET film, poly (meth) PET were mixed polymer coating of an acrylic acid polymer, a saccharide or O-NY film, co Since extrusion is not possible, lamination is performed by dry lamination. When laminating by dry lamination, first apply a two-component curable polyurethane adhesive to one side of the oxygen gas barrier film, dry it in the drying zone, and then nip roll a film of the same resin as the resin in the foamed resin layer. Laminate while applying pressure. Next, a two-component curable polyurethane adhesive is applied to the oxygen gas barrier film surface on which the opposite film is not laminated in the same manner as described above, and after drying in the same manner as described above, applying pressure with the foamed resin layer and the nip roll Lamination is performed to produce a blank sheet having a layer configuration of film layer / oxygen gas barrier layer / foamed resin layer.

  The blank sheet as described above is punched into a predetermined shape so that a container can be formed, and examples of the shape are shown in FIGS. 1 and 2 are plan views of the blank sheet, respectively. The blank sheet 10 shown in FIG. 1 is used only on the side wall, and a fan-shaped side wall member 11 serving as a side wall portion of the container is formed. The blank sheet 10 shown in FIG. 2 is used for the side wall and the bottom surface. The fan-shaped side wall member 11 serving as the side wall portion of the container and the substantially circular shape serving as the bottom surface portion of the container connecting the side wall member 11 are used. The bottom surface member 12 is formed.

  Next, the blank sheet punched into a predetermined shape is wound and stored in a mold of an injection molding machine, between the opposite side edges (columnar portion) of the blank sheet, the entire lower end opening (bottom portion), and the upper end opening periphery. The skeleton member of the portion (the frame portion having the flange) is formed by injection molding the same type of resin as the resin of the foamed resin layer.

  The columnar part formed by injection between both side edges of the blank sheet may be one columnar part between the side edges, but it is preferable to form a similar columnar part on the opposite side. By forming the columnar part on the opposite side, the pressure from the upper part of the container can be evenly received.

  When using a blank sheet having only a side wall, the bottom formed by injecting the entire lower end opening may be a flat surface.However, while providing a thread tail, a step for receiving the thread tail is provided on the inner surface of the blank sheet, and stacking and It is preferred to facilitate destacking. Moreover, when using the blank sheet used as a side wall part and a bottom face part, you may carry out injection molding to the whole bottom face part so that the bottom face part of a blank sheet may be covered, but in the case of the blank sheet only of a side wall part, While providing a thread tail as if it was pulled out in the section, a step portion for receiving the thread tail may be provided on the inner surface of the blank sheet. The step part for receiving the thread tail can be formed integrally with the columnar part. In this case, the width of the step part may be the entire width of the columnar part, but the thread tail is formed all around the lower end opening. Therefore, it can be provided in the center of the columnar part with a width of 1 to 2 mm. By providing with a width of 1 to 2 mm, the amount of resin used can be reduced.

  The frame flange formed on the periphery of the upper opening must have a width of 3.0 to 8.0 mm in order to heat-seal the easy-peel lid. A width of 0 to 6.0 mm is preferred.

  One embodiment of the food container manufactured as described above will be described with reference to the drawings. 3 is a plan view of the food container, FIG. 4 is a cross-sectional view taken along line AA in FIG. 3, FIG. 5 is a cross-sectional view taken along line BB in FIG. FIG. 3 is an enlarged perspective view of a second columnar portion of the food container.

  In FIG. 3 to FIG. 5, the blank sheet 10 is wound into a cylindrical shape, and the side wall portion 70 is formed by the side wall portion member 11. Between the opposite side edges of the blank sheet 10, as shown in FIG. 6, a columnar portion 20 is formed by injection molding, and also on the opposite side of the columnar portion 20 as shown in FIG. 7, A second columnar portion 30 having substantially the same shape and dimensions as the columnar portion 20 is formed. A bottom portion 40 is formed on the entire lower end opening of the blank sheet 10 by injection molding, and a yarn bottom portion 41 is formed on the bottom portion 40. A strip-shaped frame part 50 is formed by injection molding on the upper edge of the blank sheet 10, and a flange 51 is formed on the periphery of the frame part 50. Moreover, the step part 60 is formed over the bottom part 40 from the height of about 1/3 from the downward direction of the columnar part 20 and the 2nd columnar part 30, and this step part 60 is the shape which protruded in the container inside. Since there is, it is possible to receive the thread tail 41.

[Example 1]
Dry 75 parts of polypropylene resin PL500A (MFR = 3.3) and 25 parts of PF814 (MFR = 2.8) manufactured by Sun Allomer Co., Ltd. on an extruder (90 mmφ, L / D = 32) manufactured by Modern Machinery Co., Ltd. The blended resin is added, and after extruding from a T-die at a temperature of 250 ° C. while adjusting the amount of carbon dioxide sealed so that the foam thickness after foaming is 0.7 mm and the expansion ratio is 2.0 times, A foamed polypropylene sheet was obtained.

On the other hand, polypropylene film “E _z C, 30 μm” manufactured by Tosero Co., Ltd. is corona-treated, and the ink “Lamiol Mark IIIR Grade” manufactured by Sakata Inx Co., Ltd. is used on the corona-treated surface with a wetting index of 42 dyne / cm or more. In addition, multicolored back-printing of steamed coffee cup and saucer designs and explanatory text was performed.

  This printed polypropylene film is set on a dry laminate LX-3 manufactured by Nakajima Seiki Engineering Co., Ltd., and a gravure roll with 95 screen lines by Helio engraving, urethane adhesive (manufactured by Toyo Morton Co., Ltd., main agent: TM- 569, curing agent: CAT-RT37, solvent: ethyl acetate), dried in 3 zones of hot air temperature 40 ° C., 65 ° C., 55 ° C., and then bonded to the foamed resin sheet to obtain a polypropylene film layer / A laminated foam sheet composed of an ink layer / polyurethane adhesive layer / foamed polypropylene sheet layer was produced.

  After punching this laminated foam sheet into a blank sheet having a shape as shown in FIG. 1, it is wound and stored in a mold of an injection molding machine “FE210-S50-ASE” manufactured by Nikko Resin Industry Co., Ltd. A polypropylene resin “Novatec BC03B” manufactured by Nippon Polypropylene Co., Ltd. with a clamping pressure of 210 t and a resin temperature of 230 ° C. is formed between the opposite side edges of the blank sheet and the opposite part of the columnar part and the second columnar part, and the bottom part of the entire lower end opening. Then, a food container as shown in FIGS. 3 to 7 was prepared by injection molding a frame portion having a flange at the periphery of the upper end opening.

  The flange 51 has a width of 5.0 mm and a thickness of 1.0 mm, the band-shaped frame portion 50 has a width (length in the vertical direction in FIG. 4) of 8.0 mm and a thickness of 1.2 mm, and the columnar portion 20 has a width. The height of the stepped portion 60 (the length from the bottom end of the container at the upper end surface of the stepped portion 60) is 35 mm, the width is 1.0 mm, and the taper angle is increased in thickness. Angle) 1 degree, projecting length (length projecting inward from the columnar part 20) 1.8 mm, height of the bottom part 40 (part joined to the blank sheet 10. The thread bottom part 41 is included. ) 14 mm, the height of the thread tail 41 is 3 mm, and the thickness is 1.0 mm.

The obtained food container was a food container with a high-class feeling due to the flange and the thread end shape accurately formed by injection molding with cosmetic printing on the side wall 11.
Further, the skeleton part (columnar part, bottom face part, frame part) and the blank sheet were firmly integrated, and the drop impact was not broken.

[Evaluation of thermal insulation]
Hot water at a temperature of 70 ° C. is poured into the food container, the hot water in the container is measured with an alcohol thermometer, and the temperature of the food container side wall is a heat label (“6R-40” temperature range 40, 43, 46, manufactured by Micron Corporation). 49, 54, 60 ° C. display), and the discoloration temperature was measured. The results were as follows.
Hot water temperature of the container: 65 ° C
Side wall display temperature: 46 ° C
As a result of the above, it was confirmed that the hot water in the food container was a temperature at the time of drinking, but the food container side wall was not heated by hand and was well insulated.

[Reduction amount of resin]
The weight of the food container of the present invention was measured, the amount of resin when a container having the same capacity and the same shape as this container was formed by injection molding with a thickness of 1.0 mm was calculated, and the amounts of both resins were compared. The results were as follows.
Food container of the present invention: 13.8 g
Container by injection molding: 19.6g
Container area: 210.6 cm ²
Volume for injecting resin: 210.6 cm ² × 0.1 cm = 21.06 cm ³
Container weight: 21.06 cm ³ × 0.93 (specific gravity of PP) = 19.6 g
As described above, the food container according to the present invention is 13.8 / 19.6 × 100 = 70.4%, which is a reduction in resin of about 30%, compared with the conventional injection molded container. It can contribute to the reduction of consumption of oil resources that cannot be achieved. This is because, in the food container of the present invention, a 0.7 mm double foamed blank sheet is used for the side wall that occupies most of the container.

[Example 2]
In the same manner as in Example 1, an ink manufactured by Sakata Inx Co., Ltd. was applied to a coated surface of a PET film (manufactured by Kureha Chemical Industry Co., Ltd., ET-130R) coated with a mixed polymer of a poly (meth) acrylic acid polymer and a saccharide. The back printing was performed in the same manner as in Example 1. Next, the carbon dioxide foam sheet of Example 1 was bonded by dry lamination in the same manner as in Example 1 using a urethane adhesive (manufactured by Toyo Morton Co., Ltd.). This laminated foam sheet was punched into the shape shown in FIG. 2 to produce a blank sheet.

  The blank sheet thus punched is wound and stored in a mold of the same injection molding machine as that of Example 1, and the same resin as that of Example 1 is injection molded under the same conditions to obtain a food container having oxygen gas barrier properties. Obtained.

[Evaluation of oxygen gas barrier properties]
An easy peel film having an easy peel layer (35 μ) / dry / Al foil (7 μ) / dry / PET (12 μ) layer structure was heat-sealed and sealed on the flange of the obtained food container. The oxygen gas barrier property of the sealed container was measured using an oxygen permeability measuring device (manufactured by MOCON, OX-TRAN (registered trademark), MODEL 2/21) at a temperature of 30 ° C. and a humidity of 80% RH or less.
As a result of the measurement, the oxygen gas barrier property was 1.3 ml / m ² . D. It was confirmed that the food could be stored for a long time.

The top view of one Embodiment of the blank sheet used for the food container by this invention The top view of other embodiment of the blank sheet used for the food container by this invention Top view of one embodiment of a food container according to the present invention AA line cross section in FIG. BB sectional view in FIG. The enlarged perspective view of the columnar part of the food container by the present invention The expansion perspective view of the 2nd columnar part of the food container by this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Blank sheet 11 Side wall part 12 Bottom part member 20 Columnar part 30 Second columnar part 40 Bottom part 41 Yarn bottom part 50 Frame part 51 Flange 60 Step part 70 Side wall part

Claims (7)

A blank sheet serving as a side wall of a container is wound and stored in a mold of an injection molding machine, and injection molding resin is injected and filled between opposite side edges of the blank sheet, the entire lower end opening, and the upper end opening periphery. By this, it is a container which forms the frame part which has a columnar part, a bottom part, and a flange, Comprising: While the said blank sheet has a foamed resin layer, resin of this foamed resin layer and injection molding resin are the same kind of resin A food container characterized by that. A blank sheet to be used as a side wall portion and a bottom surface portion of a container is wound and stored in a mold of an injection molding machine, and the entire bottom surface portion or at least the bottom of the bottom surface portion is formed between opposite side edges of the blank sheet. A container for forming a frame part having a columnar part, a bottom part or a thread bottom part, and a flange by injection-filling an injection molding resin into a part and a peripheral edge of an upper end opening, wherein the blank sheet has a foamed resin layer The food container, wherein the resin of the foamed resin layer and the injection molding resin are the same kind of resin. The food container according to claim 1 or 2, wherein the resin of the foamed resin layer is PE resin, PP resin or PET resin. The food container according to claim 1, 2 or 3, wherein the blank sheet has a smooth unfoamed layer on at least one surface of the foamed resin layer. The food container according to claim 1, 2, 3, or 4, wherein the blank sheet has an oxygen gas barrier layer. The oxygen gas barrier layer is coated with EVOH film, PVDC film, MXD6-NY film, Al foil, SiOx vapor-deposited PET film, Al ₂ O ₃ vapor-deposited PET film, or a mixed polymer of poly (meth) acrylic acid polymer and saccharide. The food container according to claim 5, which is a PET or O-NY film. The food container according to claim 1, wherein the foamed resin layer is a foamed resin layer foamed by gas foaming.

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