JPH0551074A - Container cover - Google Patents

Abstract

PURPOSE:To obtain a container in which the cover of half-opened container is heated by the steam of hot water conducted in the container and then automatically closed. CONSTITUTION:The cover of a container is made of a laminate of a layer 2, an adhesion layer 3, metallic layer 4, and a heat-sealed resin layer. The cover 1 is used for closing the container and provided with a pulling part at the end. The lamination 6 includes a single extended resin film having a number of micro-voids 8 in the inside of the base layer 2 or an extended resin film having a number of micro-voids 8 in the inside layer. The pulling part is attached to the side correspond to the direction of the larger thermal expansion ratio when the base material layer 2 is heated from 30 deg.C up to 80 deg.C during five minutes at the ratio of rising speed of temperature, 10 deg.C/min.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sealing of a container for instant food such as instant cup noodles, cup sushi, cup soup, and cup miso soup, which is eaten after pouring hot water into the container and holding it for a certain period of time. Regarding the lid used.

[0002]

2. Description of the Related Art Conventionally, instant foods represented by instant cup noodles can be eaten simply by pouring hot water into a container and waiting for a few minutes (1 to 5 minutes). It is eaten in large quantities by single people, factory night workers, single employees, students, and others. In order to eat such an instant food, for example, the case of instant cup noodles will be specifically described. First, the transparent shrink packaging film packaged at the time of purchase is removed, and then the container is heat-sealed ( The pulling part of the heat-sealed lid is picked up by fingers and pulled up, and about 1/3 to 1/2 of the lid is peeled off from the container.
Then, a bag containing ingredients and soup other than noodles in the container is cut with fingers, placed on the noodles, and boiling water is poured into this. After pouring hot water, the peeled lid portion is overlapped with the flange portion at the upper end of the container to close the lid, and a weight is placed on the lid so that the lid does not roll up and open, or The heat in the container is prevented from escaping by using tape or the like to improve the heat efficiency, and the contents are steamed. And
After a lapse of a predetermined time (1 to 5 minutes), the weight on the lid is removed, the rolled-up lid is pulled, the lid is completely peeled off from the container, and the contents are steamed. Can eat.

As a container used for such instant foods, a polystyrene paper, a high-impact polystyrene sheet, or a laminated sheet of nylon and polyethylene, which have good heat retaining properties, is usually cup-assisted by vacuum molding or pressure-assisting. A molded product, a foam polystyrene cup obtained by in-mold bead foam molding, a container obtained by injection molding polypropylene, and the like are used. Further, as the lid used for the above-mentioned container, as shown in FIG. 5, a high-quality paper having a print 14 on its surface is used as the base material layer 2, and a low-density polyethylene, an ethylene / acrylic acid copolymer An adhesive layer 3 extrusion-coated with a molten resin film, or an adhesive layer 3 coated with a urethane-based or polyester-based liquid adhesive (so-called anchor coating agent), to which an aluminum foil having a thickness of 6 to 15 μm was laminated From the aluminum foil layer 4, and further from this heat-sealing layer 5 which is formed by extrusion laminating a low-density polyethylene or a low melting point (80 to 135 ° C.) resin of ethylene / vinyl acetate copolymer in a solvent or applying it on a solvent and coating it on the aluminum foil layer. Which is a laminated sheet 6 having a four-layer structure with heat sealability
Was being used.

[0004]

However, in such a lid of an instant food container, when the lid of the container is partially opened and boiling water is poured, the steam of the boiling water passes through the aluminum layer on the inside of the lid to form a base material. As a result of heating the high-quality paper and releasing the water content in the high-quality paper, the high-quality paper contracts, the lid curls upward and warps (see FIG. 6). Therefore, the lid of an instant food container cooked with this kind of boiling water conventionally requires the trouble of pouring boiling water and then closing the lid of the opened lid by weighting the lid. It was

[0005]

[Summary of the Invention] As a result of intensive studies conducted by the present inventors in view of the above problems, the present invention results in a larger thermal expansion than the metal foil due to the temperature of steam on the outside of the metal foil. As a result, the thermal expansion of the lid is not so large as to cause the lid to curl inward, and a stretched resin film having a specific structure and specific physical properties is used to bond the containers together. The inventors of the present invention have completed the present invention by finding that the lid can be automatically closed. That is, the lid of the container of the present invention comprises a laminated sheet of a base material layer / adhesive layer / metal layer / heat-sealable resin layer, and is a lid used for sealing the container, and the lid is the heat-sealable one. In a lid that has a pulling portion at its end for facilitating peeling of the lid from the container when heat-sealed to the container via the flexible resin layer, the base material layer is finely divided inside. Formed by a single layer of a stretched resin film having a large number of voids or a layer made of a laminated sheet containing a stretched resin film having a large number of fine voids inside, and the position where the tensile portion is formed raises the base material layer. Temperature rate 10 ℃ /
It is characterized in that it is provided so as to match the direction in which the coefficient of thermal expansion is large when the temperature is raised to a temperature of 30 to 80 ° C. in 5 minutes.

[Detailed Description of the Invention] [I] Container Lid (1) Structure As shown in FIG. 1, the container lid 1 of the present invention basically has the following base material layer 2 / adhesive layer. 3 / Metal layer 4 / Heat-sealing resin layer 5 is included in the laminated sheet 6. (a) Base Material Layer As the base material layer 2 used in the lid 1 of the container of the present invention, as shown in FIG. 1, a thermoplastic resin film 2a containing an inorganic fine powder 7 is used at a temperature lower than the melting point of the resin. The stretched resin film 2a has a large number of fine voids 8 inside the film obtained by stretching, or the laminated film 2 in which the stretched resin film 2a and other resin films 2b and 2c are laminated. Such a base material layer 2 is specifically a biaxially stretched resin microporous film 2 containing an inorganic fine powder 7.
a, a uniaxially stretched resin microporous film 2b, 2c containing the biaxially stretched resin film as a core layer and inorganic fine powder 7 on one or both sides (Japanese Patent Publication No. 46-40794, Japanese Patent Publication No. 63-1183). An example is a stretched resin film 2 (see FIG. 1) having a multilayer structure in which is laminated. Of course, a resin film containing no inorganic fine powder 7 may be laminated as long as the self-closing property of the lid 1 of the container of the present invention is not impaired. For example, in order to impart high gloss to the print, the surface side of the base material layer 2 to be printed does not contain substantially inorganic fine powder 7 having a thickness of 0.2 to 8 μm (0 to 0). 3 wt%) resin film layer can be formed.

Inorganic Fine Powder As the above inorganic fine powder, calcined clay, calcium carbonate, diatomaceous earth, titanium oxide, palm curite, talc, etc. can be mentioned, and the inorganic fine powder generally has a particle size of 0.03 to. Those having a thickness of 15 μm, preferably 0.1 to 5 μm are used.

Thermoplastic Resin Examples of the thermoplastic resin include polypropylene, polyethylene, ethylene / propylene copolymer, ethylene / buden-1 copolymer, ethylene / 4-methylpentene-1 copolymer, propylene / ethylene / buden. -1 copolymer,
Examples thereof include polystyrene, polyethylene terephthalate, nylon-6, nylon-6,6, nylon-6,10 and nylon-6,12.

[0009] Thermoplastic resin films containing an extended elongation above inorganic fine powder is stretched at a temperature lower than the melting point of the resin. The stretching ratio at this time is 1.3 to 15 times, preferably 3.5 to 10 times in each of the one direction and the two directions. The number of stretching axes is uniaxial or biaxial.

Physical Properties <Void> In the container lid of the present invention, the stretched resin film used for the base material layer 2 has a large number of fine voids (porosity) 8 with the inorganic fine powder 7 as a core. Such a stretched resin film has a porosity of 4 to 60 calculated by the following formula.
%, Preferably 8 to 50%. Porosity = [(ρ ₀ −ρ) / ρ ₀ ] × 100 ρ ₀ : Density of film before stretching ρ: Density of film after stretching <Coefficient of thermal expansion> In the lid of the container of the present invention, The coefficient of thermal expansion (L _e ) is important. The coefficient of thermal expansion of such a base material layer is measured by a thermomechanical analyzer “TM-70” manufactured by Vacuum Riko Co., Ltd.
00 "(trade name), width: 5 mm, span length: 3
A ₀ mm (L ₀ ) test piece was heated from a temperature of 30 ° C. to a temperature of 80 ° C. over 5 minutes at a heating rate of 10 ° C./minute,
The span length (L) of the test piece at the temperature of 80 ° C. was measured, and the value (TMA method) obtained by the following equation is shown. Thermal expansion coefficient = [(L−L ₀ ) / L ₀ ] × 100 The value of this thermal expansion coefficient is 0.40 to 1.0%, preferably 0.55 to 0.85%. The value of this coefficient of thermal expansion is 1.
When it exceeds 0%, as shown in FIG. 7, the self-closing speed of the lid after pouring hot water into the container is too fast, and the contents have been steamed (before the cup noodles are ready to eat). In this case, the pulling part of the lid, which is closed too much, is excessively caught inside, and a gap 10 is formed between the container 9 and the lid 1. Further, when the value of the coefficient of thermal expansion is less than 0.40%, the time required for self-closing is too late (takes 90 seconds to 3 minutes), which causes irritation to the eater. The value of the coefficient of thermal expansion of the base material layer determined by the TMA method is a value obtained by subtracting the coefficient of thermal contraction of the stretched resin film from the coefficient of thermal expansion of the material resin of the stretched resin film.

<Tensile Elastic Modulus> Tensile elastic modulus of the base material layer in the direction in which the tensile portion of the base material layer is provided (JIS-K7113)
Is 10,000 to 45,000 kg / cm ² , preferably 15,000 to 30,000 kg / cm ² .
Since the orientation of the base layer is exerted on the film by stretching, the elastic modulus shows a value higher than that of the unstretched resin film. Therefore, the thickness of the base material layer can be reduced.

[0012] thickness of the thick cover substrate layer for use in the container of the present invention generally 15～180Myuemu, preferably 40 to 100 [mu] m.

(B) Adhesive Layer The adhesive layer laminated in the lid of the container of the present invention for laminating the base material layer and a metal layer such as an aluminum foil described later includes urethane prepolymer, liquid polyester, Isocyanate-based, polyester isocyanate-based, polyether isocyanate-based, polyethyleneimine-based, organic titanate-based anchor coating agents, low-density polyethylene, ethylene / vinyl acetate copolymers, ethylene / acrylic acid copolymers and other hot melt adhesives Can be mentioned. 1-20g / m for coating type adhesive
² , preferably used in an amount of 2-6 g / m ² . Hot melt adhesive is melt extrusion laminated, 8-30μ
Used with a thickness of m. Such an adhesive layer is typically 1
It is used in a thickness of -30 μm, preferably 2-15 μm.

(C) Metal Layer As the metal layer used in the container lid of the present invention,
A metal foil such as an aluminum foil or an iron foil having a wall thickness of usually 3 to 25 μm can be mentioned. Especially the wall thickness is 6 ~ 15μ
It is preferable to use an aluminum foil of m for the reasons of handling and economical reasons. Further, from the economical viewpoint, the metal foil is usually used with a thickness smaller than that of the base material layer.

(D) Heat-sealable resin layer As the heat-sealable resin used for heat-sealing the container and the lid in the present invention, a resin having a melting point lower than that of the resin constituting the base material layer is used. .. Specific examples of such heat-sealable resin include low-density polyethylene,
Linear low density polyethylene, ethylene / vinyl acetate copolymer (preferably ethylene / vinyl acetate copolymer having a vinyl acetate content of 12% by weight or less), ethylene / acrylic acid copolymer (preferably ethylene content of 65 to 94) Wt% ethylene / acrylic acid copolymer), ethylene / methacrylic acid alkyl ester copolymer, ionomer (metal salt of ethylene / acrylic acid copolymer, metal salt of ethylene / methacrylic acid copolymer), ethylene / propylene Examples thereof include copolymers, ethylene / propylene / butene-1 copolymers, vinyl chloride / vinyl acetate copolymers, and the like. The heat-sealable resin may be extrusion-laminated on a metal sheet such as an aluminum foil, or the resin may be dissolved in a solvent, coated on the aluminum foil using a coater, and dried to obtain a heat-sealable resin. Layers may be provided. The thickness of the heat-sealable resin layer is 2 to
The thickness is 50 μm, preferably 3 to 40 μm. The heat-sealing of the container and the lid using such a heat-sealable resin can prolong the storage period of the food in the container.

(2) Pulling part In the lid 1 of the container of the present invention, as shown in FIG.
A pulling portion 11 for peeling off the lid 1 is provided, but its forming position is important in the present invention. Since the pulling portion 11 of the lid 1 coincides with the peeling direction α of the lid 1, it promotes the self-closing property of the lid 1 so that it coincides with the direction β in which the value of the coefficient of thermal expansion of the base material layer 2 is large. It is desirable to provide it. If the pulling portion 11 of the lid 1 is provided so as to match the direction γ in which the value of the coefficient of thermal expansion is small, the self-closing property is deteriorated. However, since the lid 1 is trimmed from the laminated sheet 6 made of the base material layer 2, an angle of 45 degrees is formed with respect to the direction β exhibiting a large heat shrinkage as shown in FIG. 4 in order to reduce material loss. If the angle is within θ,
The self-closing property of the lid 1 can be maintained to such an extent that the self-closing property is slightly reduced.

(3) Thickness The thickness of the lid 1 made of the laminated sheet 6 is generally 40 to 2
00 μm, economically 60 to 150 μm.

[II] Manufacture of container with lid (1) Heat sealing Basically, base material layer 2 / adhesive layer 3 / metal layer 4 / heat sealability, which becomes the lid 1 of the container of the present invention formed as described above. A laminated sheet 6 composed of the resin layer 5 is provided inside the dried noodles 12 and the ingredients 13
It is placed on a container 9 in which is placed and heat-sealed at a temperature of usually 100 to 160 ° C., preferably 120 to 140 ° C. for 0.1 to 3 seconds. (2) Formation of pulling part The container 9 heat-sealed to the laminated sheet 6 is a separate container 9
A substantially circular shape (for example, a diameter of 150m
The lid 1 having a protruding portion 11 (pulling portion) of about 10 mm with respect to m is trimmed. (3) Shrink packaging Next, the sealed container thus obtained is shrink-wrapped to form a product.

[III] Hot Water Supply The lid 1 that has been opened halfway is heated by the steam that has been supplied, and the base material layer 2 is subjected to the thermal expansion of the metal layer 4 of the material forming the lid 1.
The thermal expansion is superior, and the lid 1 is automatically returned to the original position (see FIG. 2) by the bimetal effect and the container 9 can be sealed.

[0020]

【Example】

Example 1 Production of base material layer (1) 81% by weight of polypropylene having a melt index (MI) of 0.8 (melting point of about 164 to 167 ° C.), 3% by weight of high-density polyethylene and calcium carbonate having an average particle size of 1.5 μm The composition (A) containing 16% by weight is mixed at 270 ° C.
After kneading with the extruder set to, the sheet was extruded and cooled by a cooling device to obtain an unstretched sheet. Then, this sheet was heated again to a temperature of 150 ° C. and then stretched 5 times in the machine direction. (2) Polypropylene with MI of 0.4 (melting point about 164-1)
(67 ° C.) 54% by weight and 46% by weight of calcium carbonate having an average particle size of 1.5 μm were mixed and kneaded in another extruder, and then extruded into a sheet from a die. Was laminated on both sides of the 5-fold stretched film of (1) to obtain a laminated film having a three-layer structure. Then, after cooling the laminated film having the three-layer structure to 60 ° C., it is again heated to about 175 ° C.
7. Heat up to the temperature of 7. and use a tenter to move laterally 7.
Stretched 5 times, annealed at 165 ° C,
Cooled to a temperature of 60 ° C, slit the ears, and have a three-layer structure (uniaxial stretching / biaxial stretching / uniaxial stretching), thickness 80 μm
A base material layer (B / A / B = 20 μm / 40 μm / 20 μm) was obtained. The void ratio of each layer is (B / A / B =
It was 4.6% / 13.9% / 4.6%).

Manufacture of Lid The surface of the above-mentioned base material layer is printed, and further, an anchor coating agent of urethane prepolymer is applied to the back surface side so as to be 3 g / m ^2, and an aluminum foil having a thickness of 6 μm is applied to this. Was laminated. On the aluminum foil side of this laminate, an ethylene / vinyl acetate copolymer (vinyl acetate content: 5.4% by weight) was extruded at 200 ° C. and laminated (thickness: 22%).
μm) and then cooled. This is the sheet feeding direction (M
Trimming was performed so that a tensile portion was formed in the D direction), and a substantially circular lid was obtained (diameter 150 mm, tensile portion 10 mm).

Heat seal 250 g of dried noodles and 25 g of ingredients were put in a container made of expanded polystyrene having a capacity of 1,000 cc and a diameter of about 150 mm, and the lid was heat-sealed by applying pressure at 140 ° C. for 0.5 seconds. ..

Evaluation After standing for one day, the pulling portion of the lid of the expanded polystyrene container is pulled with a finger to open 2/3 of the lid, and boiling water is heated from this opening (temperature: about 91 ° C.). 600 cc was poured into the container for 5 seconds to measure the self-closing property of the lid. The results obtained are shown in Table 1.

Example 2 The procedure of Example 1 was repeated, except that the base layer was manufactured as follows. The results obtained are shown in Table 1. Production of base material layer (1) Composition (A) in which 81% by weight of polypropylene having a melt index (MI) of 8% by weight is mixed with 3% by weight of high-density polyethylene and 16% by weight of calcium carbonate having an average particle diameter of 1.5 μm. Was kneaded with an extruder set to 270 ° C., extruded into a sheet and cooled by a cooling device,
An unstretched sheet was obtained. Then, this sheet was heated again to a temperature of 140 ° C. and then stretched 5 times in the machine direction. (2) Composition (B) in which 54% by weight of polypropylene having an MI of 0.4 and 46% by weight of calcium carbonate having an average particle size of 1.5 μm are mixed, and 81% by weight of polypropylene having an MI of 4.0 is high density. Polyethylene 3% by weight and average particle size 1.5
The composition (C) mixed with 16% by weight of calcium carbonate (μm) is melt-kneaded by another extruder, and then melt-extruded into a sheet form from a die, which is stretched 5 times as long as (1). By laminating on both sides of the film, a laminated film having a three-layer structure was obtained. Then, after cooling the laminated film having the three-layer structure to 60 ° C., it is heated again to a temperature of about 160 ° C., stretched 7.5 times in the transverse direction using a tenter, and annealed at a temperature of 165 ° C. Then, it is cooled to a temperature of 60 ° C. and the ears are slit to form a three-layer structure (uniaxially stretched / biaxially stretched / uniaxially stretched) having a wall thickness of 80 μm (B / A / C = 16 μm).
A base material layer of / 48 μm / 16 μm) was obtained. The void ratio of each layer is (B / A / C = 30% / 29.7% / 3.
It was 0%). The printing surface was applied to the surface of layer B.

Example 3 A substrate layer was produced in the same manner as in Example 1 except that it was produced as follows. The results obtained are shown in Table 1. Manufacture of base material layer (1) Polypropylene having MI of 2 g / 10 min (melting point of about 1
64 ° C) 77% by weight, high-density polyethylene 10% by weight,
A resin composition containing 10% by weight of calcium carbonate having an average particle size of 1.5 μm and 3% by weight of titanium oxide was melt-kneaded by an extruder and extruded into a sheet at a temperature of 200 ° C., which was cooled by a cooling device. After that, the sheet is reused for 15
After heating to a temperature of 0 ° C., it was stretched 5 times in the machine direction to obtain a stretched film. Then, after heating again to a temperature of 158 ° C, it is stretched 7 times in the transverse direction, annealed at a temperature of 164 ° C, cooled to a temperature of 60 ° C, and the ears are slit to reduce the wall thickness. A 50 μm monolayer biaxially oriented film was obtained. The void ratio of this monolayer biaxially stretched film was 44.7%.

Comparative Example 1 A substrate layer was produced in the same manner as in Example 1 except that it was produced as follows. The results obtained are shown in Table 1. Production of base material layer (1) Composition (A) in which 81% by weight of polypropylene having a melt index (MI) of 8% by weight is mixed with 3% by weight of high-density polyethylene and 16% by weight of calcium carbonate having an average particle diameter of 1.5 μm. Was kneaded with an extruder set to 270 ° C., extruded into a sheet and cooled by a cooling device,
An unstretched sheet was obtained. Then, this sheet was heated again to a temperature of 140 ° C. and then stretched 5 times in the machine direction. (2) A composition (B) prepared by mixing 54% by weight of polypropylene having MI of 4.0 and 46% by weight of calcium carbonate having an average particle size of 1.5 μm was kneaded in another extruder, and then this was die-cast. It was extruded into a sheet and laminated on both sides of the 5 times stretched film of (1) to obtain a laminated film having a three-layer structure.
Then, after cooling the laminated film having the three-layer structure to 60 ° C., it is heated again to a temperature of about 160 ° C., stretched 7.5 times in the transverse direction using a tenter, and annealed at a temperature of 165 ° C. Then, it is cooled to a temperature of 60 ° C., and the ears are slit to form a three-layer structure (uniaxially stretched / biaxially stretched / uniaxially stretched) having a wall thickness of 80 μm (B / A / B = 16 μm / 48).
A base material layer having a thickness of μm / 16 μm) was obtained. The void ratio of each layer was (B / A / B = 30% / 33.7% / 30%).

Comparative Example 2 The procedure of Example 1 was repeated except that the base material layer was manufactured as follows. The results obtained are shown in Table 1. Manufacture of base layer Synthetic paper "Yupo FPG #" made by Oji Yuka Synthetic Paper Co., Ltd., which is made of multi-layer stretched polypropylene film containing inorganic fine powder
80 "(trade name, wall thickness 80 μm) was used. (Porosity of base material layer: 33%) Comparative Example 3 The same procedure as in Example 1 was carried out except that the base material layer was produced as follows. The results obtained are shown in Table 1. Production of Base Layer A transparent unstretched polypropylene film “Taiko FHK2” (trade name, wall thickness 60 μm) manufactured by Nimura Sansho Co., Ltd. was used. (Void ratio of base material: 0%) Comparative Example 4 The same procedure as in Example 1 was carried out except that the base material layer was produced as follows. The results obtained are shown in Table 1. Production of base material layer Paper for base material of commercially available cup ramen lid ("Cormorant" (trade name) of Fuji Kako Co., Ltd. (wall thickness 90 μm,
A weighed amount of 82.4 g / m ² )) was used.

Example 4 The procedure of Example 1 was repeated except that the substrate layer was produced as follows. The results obtained are shown in Table 1. Production of base material layer (1) 81% by weight of polypropylene having a melt index (MI) of 0.8 (melting point of 164 ° C.), 3% by weight of high-density polyethylene and calcium carbonate having an average particle size of 1.5 μm 1
The composition (A) containing 6 wt% was kneaded by an extruder set at 270 ° C., extruded into a sheet, and cooled by a cooling device to obtain an unstretched sheet. Then, this sheet was heated again to a temperature of 140 ° C. and then stretched 5 times in the machine direction. (2) A composition (B) in which 54% by weight of polypropylene having an MI of 4.0 and 46% by weight of calcium carbonate having an average particle size of 1.5 μm are mixed and kneaded in another extruder, It was extruded in a sheet form from a die and laminated on one side of the 5-fold stretched film of (1) to obtain a laminated film having a two-layer structure. Then, this composition (B) and polypropylene (C) having MI of 4.0 are melt-kneaded in another extruder and then laminated in two layers in a die. The laminated film having the four-layer structure was obtained by laminating the composition (B) on the side of the laminated film having the two-layer structure, on which the sheet layer was not laminated, so that the polypropylene (C) was on the outside. Then, after cooling the laminated film having the four-layer structure to 60 ° C., it is heated again to a temperature of about 160 ° C., stretched 7.5 times in the transverse direction using a tenter, and annealed at a temperature of 165 ° C. Then, cool to a temperature of 60 ° C. and slit the ears (C / B / A / B = 5 μm / 16 μm / 4
A base material layer having a four-layer structure of 8 μm / 11 μm) was obtained. The void ratio of each layer is (C / B / A / B = 0% / 45% / 16%
/ 45%). The printing surface was the surface of the C layer.

[0029]

[Table 1]

[0030]

EFFECTS OF THE INVENTION The lid of the container of the present invention as described above is heated by the steam supplied to the container, whereby the bimetal effect works and the container can be automatically sealed. There is no need to close the lid after the hot water is supplied and put a weight on it.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a container lid of the present invention.

FIG. 2 is a perspective view of the lid and the container of the present invention in a state where hot water is poured into the container and the lid is closed.

FIG. 3 is a perspective view of the lid and the container of the present invention in a state in which the lid is opened, tools are put in the container, and hot water is not poured.

FIG. 4 is a plan view of a laminated sheet when trimming the lid of the container of the present invention from the laminated sheet.

FIG. 5 is an enlarged cross-sectional view of a conventional lid.

FIG. 6 is a perspective view of a conventional lid and container in a state where hot water is poured into the container and the container is further opened.

FIG. 7 is a perspective view of an improper lid and container in a state where hot water is poured into the container and the container is overly closed and curved inward.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Container lid 2 Base material layer 2a Biaxially stretched resin microporous film 2b, 2c Uniaxially stretched resin microporous film 3 Adhesive layer 4 Metal layer 5 Heat sealable resin layer 6 Laminated sheet 7 Inorganic fine powder 8 Void 9 Container 10 Gap 11 Tension part 12 Dried noodles 13 Tool α Peeling direction β Direction with large value of thermal expansion coefficient γ Direction with small value of thermal expansion coefficient θ Angle within 45 ° to direction β showing large thermal contraction rate

[Procedure amendment]

[Submission date] March 26, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

However, in such a lid of an instant food container, when the lid of the container is partially opened and boiling water is poured, the steam of the boiling water passes through the aluminum layer on the inside of the lid to form a base material. As a result of heating the high-quality paper and releasing the water content in the high-quality paper, the high-quality paper contracts, the lid curls upward and warps (see FIG. 6). Therefore, the lid of an instant food container cooked with this kind of boiling water conventionally requires the trouble of pouring boiling water and then closing the lid of the opened lid by weighting the lid. It was As a container lid, a lid made by laminating a transparent biaxially oriented polyethylene film or a biaxially oriented nylon film on a paper or aluminum base material is automatically operated by the bimetal effect due to the heat of the steam of the hot water poured into the container. It has been proposed to close it (Japanese Utility Model Laid-Open No. 58-133574). However, with this lid, the shrinkage rate of the biaxially stretched film is too large, and
As shown in (4), the lid curls inward and the container cannot be closed tightly with the lid.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

Inorganic Fine Powder As the above inorganic fine powder, there can be mentioned calcined clay, calcium carbonate, diatomaceous earth, titanium oxide, vermiculite, talc and the like, and the inorganic fine powder generally has a particle size of 0.03 to. Those having a thickness of 15 μm, preferably 0.1 to 5 μm are used.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Physical Properties <Void> In the container lid of the present invention, the stretched resin film used for the base material layer 2 has a large number of fine voids (voids) 8 with the inorganic fine powder 7 as a core. Such a stretched resin film has a porosity of 4 to 60% calculated by the following formula,
It preferably has 8 to 50%. Porosity = [(ρ ₀ −ρ) / ρ ₀ ] × 100 ρ ₀ : Density of film before stretching ρ: Density of film after stretching <Coefficient of thermal expansion> In the lid of the container of the present invention, The coefficient of thermal expansion (L _e ) is important. The coefficient of thermal expansion of such a base material layer is measured by a thermomechanical analyzer “TM-70” manufactured by Vacuum Riko Co., Ltd.
00 "(trade name), width: 5 mm, length: 25 mm
This test piece was fixed to a chuck, the span distance (L ₀ ) was 15 mm, and the load was 1 g.
The value obtained by the following equation: the temperature was raised from 30 ° C. to 80 ° C. over 5 minutes at a temperature of 80 ° C./minute, and the span length (L) of the test piece at the temperature of 80 ° C. was measured. (TMA method) is shown. Thermal expansion coefficient = [(L−L ₀ ) / L ₀ ] × 100 The value of this thermal expansion coefficient is 0.40 to 1.0%, preferably 0.55 to 0.85%. The value of this coefficient of thermal expansion is 1.
When it exceeds 0%, as shown in FIG. 7, the self-closing speed of the lid after pouring hot water into the container is too fast, and the contents have been steamed (before the cup noodles are ready to eat). In this case, the pulling part of the lid, which is closed too much, is excessively caught inside, and a gap 10 is formed between the container 9 and the lid 1. Further, when the value of the coefficient of thermal expansion is less than 0.40%, the time required for self-closing is too slow, which causes irritation to the eater. Base layer T
The value of the coefficient of thermal expansion obtained by the MA method is a value obtained by subtracting the coefficient of thermal contraction of the stretched resin film from the coefficient of thermal expansion of the material resin of the stretched resin film.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

[0020]

Example 1 Production of base material layer (1) Melt flow rate (MFR) 0.8 g / 10
81% by weight of polypropylene (melting point about 164-167 ° C.), 3% by weight of high-density polyethylene and an average particle size of 1.
The composition (A) in which 16% by weight of calcium carbonate of 5 μm was mixed was kneaded by an extruder set at 270 ° C., extruded into a sheet, and cooled by a cooling device to obtain an unstretched sheet. Then, this sheet was heated again to a temperature of 150 ° C. and then stretched 5 times in the machine direction. (2) 54% by weight of polypropylene having an MFR of 4 g / 10 min (agglomeration about 164-167 ° C.) and an average particle size of 1.5 μm
The composition (B) containing 46% by weight of calcium carbonate was kneaded in another extruder, and then extruded into a sheet form from a die, which was laminated on both sides of the 5 × stretched film of (1). A laminated film having a three-layer structure was obtained. Then, after cooling the laminated film having the three-layer structure to 60 ° C., it is heated again to a temperature of about 175 ° C., stretched 7.5 times in the transverse direction using a tenter, and annealed at a temperature of 165 ° C. Then, it is cooled to a temperature of 60 ° C., and the ears are slit to form a three-layer structure (uniaxial stretching / biaxial stretching / uniaxial stretching) with a wall thickness of 80 μm (B / A / B = 20 μm / 40 μm / 20 μ).
A base material layer of m) was obtained. The void ratio of each layer is (B /
A / B = 4.6% / 13.9% / 4.6%).

[Procedure Amendment 5]

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[Correction method] Change

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Example 2 The procedure of Example 1 was repeated, except that the base layer was manufactured as follows. The results obtained are shown in Table 1. Production of base material layer (1) Polypropylene 81 with MFR 0.8 g / 10 min
After kneading the composition (A) in which 3% by weight of high-density polyethylene and 16% by weight of calcium carbonate having an average particle diameter of 1.5 μm were mixed with the weight% with an extruder set at 270 ° C.,
The sheet was extruded and cooled by a cooling device to obtain a non-stretched sheet. Then, this sheet was heated again to a temperature of 140 ° C. and then stretched 5 times in the machine direction. (2) 54% by weight of polypropylene having an MFR of 4 g / 10 min and 46% by weight of calcium carbonate having an average particle size of 1.5 μm.
A composition (B) in which MFR was 4.0 g / 10 min, 81% by weight of polypropylene, 3% by weight of high-density polyethylene and 16% by weight of calcium carbonate having an average particle size of 1.5 μm. C) and are melt-kneaded in another extruder, and then melt-extruded in a sheet form from a die,
This was laminated on both sides of the (1) 5-fold stretched film to obtain a laminated film having a three-layer structure. Then, after cooling the laminated film having the three-layer structure to 60 ° C., the laminated film is heated again to a temperature of about 160 ° C., and then 7.5 mm in the lateral direction using a tenter.
Double stretching and annealing at 165 ° C.
Cooled to a temperature of 0 ° C, slit the ears, and have a three-layer structure (uniaxially stretched / biaxially stretched / uniaxially stretched) with a wall thickness of 80 μm.
A base material layer (B / A / C = 16 μm / 48 μm / 16 μm) was obtained. The void ratio of each layer is (B / A / C = 3
0% / 29.7% / 3.0%). The printing surface was applied to the surface of layer B.

[Procedure Amendment 6]

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Example 3 A substrate layer was produced in the same manner as in Example 1 except that it was produced as follows. The results obtained are shown in Table 1. Production of base material layer (1) 77% by weight of polypropylene (melting point of about 164 ° C.) having an MFR of 2 g / 10 min, 10% by weight of high-density polyethylene, 10% by weight of calcium carbonate having an average particle size of 1.5 μm,
Further, a resin composition containing 3% by weight of titanium oxide is melt-kneaded by an extruder and extruded into a sheet shape at a temperature of 200 ° C., which is cooled by a cooling device, and then the sheet is again
After heating to a temperature of 50 ° C., it was stretched 5 times in the machine direction to obtain a stretched film. Then, after heating again to a temperature of 158 ° C, it is stretched 7 times in the transverse direction, annealed at a temperature of 164 ° C, cooled to a temperature of 60 ° C, and the ears are slit to reduce the wall thickness. A 50 μm monolayer biaxially oriented film was obtained. The void ratio of this monolayer biaxially stretched film was 44.7%.

[Procedure Amendment 7]

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Example 5 A substrate layer was produced in the same manner as in Example 1 except that it was produced as follows. The results obtained are shown in Table 1. Production of base material layer (1) Polypropylene 8 with MFR of 0.8 g / 10 min
After kneading 1% by weight, 3% by weight of high-density polyethylene and 16% by weight of calcium carbonate having an average particle diameter of 1.5 μm (A) with an extruder set at 270 ° C.,
The sheet was extruded and cooled by a cooling device to obtain a non-stretched sheet. Then, this sheet was heated again to a temperature of 140 ° C. and then stretched 5 times in the machine direction. (2) Polypropylene 54 with MFR of 4.0 g / 10 min
The composition (B) in which 40% by weight of calcium carbonate having an average particle size of 1.5 μm was mixed with the composition by weight was kneaded in another extruder, and then extruded into a sheet form from a die, which was (1). Was laminated on both sides of the 5-fold stretched film to obtain a laminated film having a three-layer structure. Then, after cooling the laminated film having the three-layer structure to 60 ° C., it is heated again to a temperature of about 160 ° C., stretched 7.5 times in the transverse direction using a tenter, and annealed at a temperature of 165 ° C. Then, it is cooled to a temperature of 60 ° C., and the ears are slit to form a three-layer structure (uniaxially stretched / biaxially stretched / uniaxially stretched) having a wall thickness of 80 μm (B / A
/ B = 16 μm / 48 μm / 16 μm) was obtained. The void ratio of each layer is (B / A / B = 30% /
33.7% / 30%).

[Procedure Amendment 8]

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Example 6 A substrate layer was produced in the same manner as in Example 1 except that it was produced as follows. The results obtained are shown in Table 1. Manufacture of base layer Synthetic paper "Yupo FPG #" made by Oji Yuka Synthetic Paper Co., Ltd., which is made of multi-layer stretched polypropylene film containing inorganic fine powder
80 "(trade name, wall thickness 80 μm) was used. (Void rate of base material layer: 33%) Comparative Example 1 A base material layer was produced in the same manner as in Example 1 except that it was produced as follows. The results obtained are shown in Table 1. Production of Base Layer A transparent unstretched polypropylene film “Taiko FHK2” (trade name, wall thickness 60 μm) manufactured by Nimura Sansho Co., Ltd. was used. (Void rate of base material 0%) Comparative Example 2 The same procedure as in Example 1 was carried out except that the base material layer was produced as follows. The results obtained are shown in Table 1. Production of base material layer Paper for base material of commercially available cup ramen lid ("Cormorant" (trade name) of Fuji Kako Co., Ltd. (wall thickness 90 μm,
A weighed amount of 82.4 g / m ² )) was used.

[Procedure Amendment 9]

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Example 4 The procedure of Example 1 was repeated except that the substrate layer was produced as follows. The results obtained are shown in Table 1. Production of base material layer (1) 81% by weight of polypropylene (melting point 164 ° C.) with MFR of 0.8 g / 10 min, high density polyethylene 3
The composition (A) in which 16% by weight of calcium carbonate having an average particle diameter of 1.5 μm was mixed with the composition (A) was kneaded by an extruder set at 270 ° C., extruded into a sheet, and cooled by a cooling device to obtain nothing. A stretched sheet was obtained. Then, this sheet was heated again to a temperature of 140 ° C. and then stretched 5 times in the machine direction. (2) Polypropylene 54 with MFR of 4.0 g / 10 min
The composition (B) in which 46 wt% of calcium carbonate having an average particle size of 1.5 μm was mixed by weight with another extruder and then extruded into a sheet form from a die, ) Was laminated on one side of the 5 times stretched film to obtain a laminated film having a two-layer structure. Then, this composition (B) and M
A polypropylene (C) having an FR of 4.0 g / 10 min was melt-kneaded in another extruder and then laminated in two layers in a die to obtain the two-layered laminate of (2) above. Polypropylene (C) was laminated on the side of the composition (B) on which the sheet layer was not laminated, to obtain a laminated film having a four-layer structure. Then, after cooling the laminated film having the four-layer structure to 60 ° C., the laminated film is heated again to a temperature of about 160 ° C. and is laterally heated to 7.5 using a tenter.
Double stretching and annealing at 165 ° C.
Cool to 0 ° C and slit the ears (C / B /
A / B = 5 μm / 16 μm / 48 μm / 11 μm) was obtained as a base material layer having a four-layer structure. The void ratio of each layer is (C / B /
A / B = 0% / 45% / 16% / 45%). The printing surface was the surface of the C layer.

[Procedure Amendment 10]

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[0029]

[Table 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Funato 23, Towada, Kamisu-cho, Kashima-gun, Ibaraki Prefecture, Okaka Synthetic Paper Co., Ltd. Kashima Plant (72) Inventor Takashi Miyaji, Kashima-gun, Kashima-gun, Ibaraki Prefecture 23, Towada, Oji Oka Synthetic Paper Co., Ltd., Kashima Plant (72) Inventor, Yukio Kohama 826, Hagien, Fukuda, Chigasaki City, Kanagawa Tokai Metal Co., Ltd. Wan, 826 Hagiden, Fukuda, Chigasaki, Kanagawa Prefecture, Tokai Metals Co., Ltd., Chigasaki Plant (72) Inventor, Toshiaki Watanabe, 826, Hagien, Chigasaki, Kanagawa Prefecture, Kaigasaki, Tokai Metal Co., Ltd. (72) Inventor Chiaki Kanai 826 Fukuda, Hagien, Chigasaki-shi, Kanagawa Tokai Metal Co., Ltd. Chigasaki factory

Claims (2)

[Claims] 1. A lid which is composed of a laminated sheet of a base material layer / adhesive layer / metal layer / heat-sealable resin layer and is used for sealing a container, the lid having the heat-sealable resin layer interposed therebetween. In a lid of a container having a pulling part at the end for peeling the lid from the container when heat-sealed to the container, the base material layer is a stretched resin film having many fine voids therein. It is formed by a layer or a layer made of a laminated sheet including a stretched resin film having a large number of fine voids inside, and the position formed on the lid portion of the pulling portion has a temperature raising rate of 10 ° C. of the base material layer of the lid portion. The lid of the container, which is provided so as to match the direction in which the coefficient of thermal expansion is large when the temperature is raised from 30 ° C. to 80 ° C. over 5 minutes. 2. The lid of the container according to claim 1, wherein the base material layer has the following properties (1) to (3). (1) The substrate layer is heated at a temperature rising rate of 10 ° C./min for 5 minutes to 30 ° C.
When the temperature is increased from 80 ° C. to 80 ° C., the coefficient of thermal expansion in the direction in which the tensile portion of the base material layer is provided is 0.4.
Within the range of 0 to 1.0%. (2) The tensile elastic modulus in the direction in which the tensile portion of the base material layer is provided is within the range of 10,000 to 45,000 kg / cm ² . (3) The thickness of the base material layer is thicker than the thickness of the metal layer.