JP2003165566A - Lid material and manufacturing method for molded lid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lid material which does not employ an aluminum foil, is excellent in suitability for drawing and packaging, can be collected as a plastic after use or easily incinerated. <P>SOLUTION: The lid material comprises a laminate film consisting of at least a base layer and a heat seal layer wherein the base layer employs a thermoplastic resin film instead of an aluminum foil is used as the base layer, and the base layer is made of such a thermoplastic resin that can be drawn. For example, the resin is selected among a polyolefin-based resin, a polystyrene- based resin or these resins filled with an inorganic filler, and a widening angle of the lid after the drawing is made to be 20° or less. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lid material for food containers such as various lactic acid beverages, yogurt, milk, jelly and other dairy products. In the present invention, the unit representing the composition of the resin composition is a mass-based value unless otherwise specified.

[0002]

2. Description of the Related Art The lid of a polystyrene or polyethylene container in which foods such as lactic acid bacteria drinks, yogurt, milk, jelly and other dairy products have been conventionally packed is generally a printed aluminum foil and a polyethylene film. Also, a multilayer laminate in which a heat seal layer and the like are laminated is used. For example, as shown in FIG.
An anchor coat (52) of polyurethane or the like is formed on the surface of the aluminum foil (51) having a thickness of μm to improve the adhesion if necessary, and printing is performed to form a printing layer (5).
3) is protected and an overcoat (54) of epoxy resin, cellulose, melamine resin or the like is applied to prevent corrosion of the aluminum foil. On the other hand, a low density polyethylene film (56) having a thickness of about 10 to 30 μm is bonded to the back surface side of the aluminum foil (51) through an anchor coat (55) similar to the above, and the polyethylene film (56) is hot-bonded. A melt adhesive is applied to form a heat seal layer (57).

In such a cover material, the aluminum foil has an excellent barrier property against air, and protects the contents and has a dead-hold property (a property in which a folded state is maintained when the cover is opened). ), It is used for the purpose of making it easier for consumers to open and eat. The heat seal layer is provided to heat seal the lid and the container body to the extent that they can be opened by hand. On the other hand, when a consumer eats or drinks, these lids may be peeled off and a mouth may be put on the container. In consideration of the hygiene of the mouth, the lid material (1) is a container as shown in FIG. It is generally formed by drawing so as to cover the side surface of the mouth portion of (2). At this time, one of the main reasons that the aluminum foil is used in the lid material is that the aluminum foil is easy to draw at room temperature and has a property of retaining its shape, like the dead hold property. is there. It is difficult to obtain such characteristics with a general thermoplastic resin film laminate, and the practicality thereof is poor.

On the other hand, in a food manufacturer, a lid material containing the aluminum foil layer is punched out from a roll-shaped roll and drawn at room temperature to form a lid (hereinafter referred to as "molding lid"), which is used as a container filled with food. A method of capping and heat-sealing at high speed and accurately, or with a pre-punched lid material, after suction-conveying and heat-sealing onto a container filled with food,
It is used by drawing so that it covers the mouth of the container. After these steps, it is important that the shape of the drawn lid is kept constant, and in particular, the molding lid of the former method keeps its shape constant during conveyance to the capping step after drawing. Is an important factor.

Further, the molded lid has been conventionally incinerated as a waste after being opened and eaten by a consumer. However, in order to collect and reuse the used packaging materials in recent years, the separate collection of waste has been progressing in each local government, and the molding lid made of the laminate of the aluminum foil and the resin film described above is used for both. Since it cannot be easily separated, it has the excellent characteristics as described above, but it cannot be separated and recovered and can only be incinerated. Even when incinerated, it is not completely incinerated if the aluminum foil is relatively thick. For,
The problem is that a large amount of unburned material remains. Furthermore,
Since aluminum foil is easy to tear, if it is accidentally mixed in food due to a problem in the packaging process, aluminum foil cannot be removed because it cannot be detected by a metal detector, and it is desired to develop an alternative material that is more difficult to tear. It is rare.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is a laminate of thermoplastic resin composition films which does not use aluminum foil and which can be drawn, and which can be recovered as a plastic or is easy. A lid material that can be incinerated is provided. Further, the present invention is to provide a molding lid made of a laminate of resin composition films whose shape formed by drawing does not substantially change with time even if it does not contain an aluminum foil.

[0007]

Means for Solving the Problems As a result of intensive studies aimed at solving the above-mentioned problems, the present inventors have found that a thermoplastic resin film is used as a base material layer in place of an aluminum foil in a specific structure. It was found that a lid material that can be drawn at room temperature can be obtained by forming a laminate, and the present invention has been completed. That is, it is a laminated film including at least a base material layer and a heat seal layer, and the base material layer does not include an aluminum foil and is made of a thermoplastic resin that can be drawn.
The thermoplastic resin is not particularly limited as long as it can be drawn at room temperature, for example, a polyolefin resin,
Examples thereof include polystyrene resins, and those filled with an inorganic filler may be used. The present invention is also a method of manufacturing a molding lid, which comprises drawing the lid material. On the other hand, the present invention includes a food container package having a molded lid made of these lid materials.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The lid material which is a laminate of the thermoplastic resin composition film of the present invention will be described in detail below.

Generally, the draw forming lid material is supplied to a maker that manufactures food products in the form of, for example, a laminated film or sheet having the above-described structure wound into a roll, and punched into a circular shape there, and then a molding machine is used. As shown in Fig. 3, the flat part (3
1) and a molding lid (3) provided with a skirt portion (32) having a rib. Then, the container is covered with a container made of a thermoplastic resin composition such as polyethylene or polystyrene filled with the content and heat-sealed. The lid material using the above-mentioned aluminum foil that has been conventionally used is easily processed into the shape shown in FIG. 3 at the time of drawing. In order to replace this with a thermoplastic resin laminate, at least the resin laminate must maintain the shape of the skirt portion (32) in the state of FIG. 3 even after drawing at room temperature.

The thermoplastic resin used in the present invention is a resin that can be melt-extruded by an ordinary extruder and has a characteristic that the shape of the skirt portion can be maintained after drawing at room temperature as described above. Although not particularly limited, for example, one kind or a mixture of two or more kinds of a polyolefin resin, a polystyrene resin, a styrene-butadiene copolymer resin, or a resin obtained by filling an inorganic filler in these resins. Therefore, a material that is likely to undergo plastic deformation at room temperature can be used.

Examples of the inorganic filler added to the thermoplastic resin include talc, calcium carbonate, silica, alumina, titanium oxide and barium sulfate. Among these, talc is preferably used from the viewpoints of stability against acid, handling thereof, and economy.

If the shape-holding property of the draw-molding is insufficient, the skirt portion of the molding lid will open with time (springback phenomenon), and the mouth of the container cannot be covered. Further, since it tends to be restored even during the production process, it may be difficult to accurately carry and cap the molding lid. Also,
If a large amount of inorganic filler is filled, the lid material becomes brittle and may break during drawing or opening, and in that case, the lid cannot function. It is desirable that the springback phenomenon after drawing is suppressed to within 20 ° as the skirt spreading angle (33) shown in FIG. If it exceeds 20 °, it will be a hindrance during the subsequent transportation or capping.

The lid member of the present invention comprises a base material layer (11) and a heat seal layer (13), and as an example, FIG.
An adhesive layer (12) may be provided between them as shown in FIG. This laminate having a three-layer structure can be manufactured by a usual method for manufacturing a multilayer film. For example, a method of subjecting a base material layer to a monolayer extrusion film formation by a T-die method, applying an anchor coat to one surface of the film, and then extruding and laminating a heat-sealing layer separately formed into a polyethylene film,
Alternatively, a method of co-extrusion laminating an adhesive layer and a heat seal layer on a base material layer by a feed block method or a multi-manifold method T-die, and further using a multi-manifold method T-die, a base material layer, an adhesive layer, a heat There is a method of coextruding the seal layer at the same time.

It is preferable that the ratio of the layer thickness of the base material layer (11) made of a thermoplastic resin layer that can be drawn at room temperature to the entire lid material layer is as large as possible in view of drawing formability.
It is preferable that the adhesive layer (12) and the heat seal layer (13) are thin. The thickness of the entire lid material layer is generally 100 to 300 μm. If it is less than 100 μm, the drawability and mechanical properties thereof may not be sufficient, and a thickness of 300 μm or more is not usually required as a mechanical property in a molding lid.

The thermoplastic resin composition constituting the base material layer (11) of the present invention does not have a problem in draw formability, and is required as long as it does not cause a problem in transfer to the surface of the base material layer. Additives such as stabilizers, lubricants and pigments can be added accordingly.

Further, the cover material of the present invention comprises a base material layer (1) for reinforcing the base material layer (11) or for printing.
Various film layers can be provided on the side opposite to the heat seal layer (13) of 1). For example, a non-stretched polypropylene film, a biaxially stretched polypropylene film, a biaxially stretched polyester film and the like can be mentioned. The biaxially stretched film has a high elastic modulus and is resistant to bending, pulling and the like, and therefore increases resistance to tearing of the lid when opened. However, it is preferable to use a film that is as thin as possible because it has an adverse effect on shape retention during drawing and causes a spring-bap phenomenon after drawing.

In the present invention, an adhesive layer (12) can be provided as described above, if necessary. The adhesive layer (12) is intended for joining the base material layer (11) and the heat seal layer (13), and is not particularly limited, but a case and anchor in which only an anchor coat of polyurethane resin or the like is used. There are cases in which a polyolefin film is further laminated on the coat layer, and cases in which a modified polyolefin film layer capable of directly adhering to the base material layer (11) without an anchor coat is provided. The polyolefin film has a function of increasing the adhesion of the heat seal layer (13) to the container, giving a cushioning property to the lid material, and ensuring airtightness.

The heat seal layer (13) of the present invention comprises
It is not particularly limited as long as it has an easily peelable property from the container material, but a hot-melt adhesive containing an ethylene vinyl acetate copolymer and a wax as a main component, an acrylic adhesive, an incompatible resin blend adhesive layer, etc. Is preferably used. Examples of incompatible resin blends include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, ethylene-propylene copolymer, ethylene-acetic acid. Examples thereof include vinyl copolymers, ethylene-acrylic acid ester copolymers, styrene-butadiene copolymers and hydrogenated products thereof, and blends of thermoplastic polyurethane and the like. The heat-sealing strength is preferably such that it can be easily opened by hand, and the maximum peeling strength to the container mouth is 10 N when the peeling speed is 300 mm / min.
Adjust the thickness and composition of the seal layer so that

The lid material of the present invention may be subjected to antistatic treatment, if necessary. As the antistatic agent, a surfactant type antistatic agent, a polymer type antistatic agent or the like can be applied by a gravure roll, a roll coater, a spray or the like. Further, in order to apply these antistatic agents uniformly, it is preferable to subject the surface to corona treatment or ozone treatment before the antistatic agent treatment.

The lid material of the present invention is obtained by subjecting a container having the shape shown in FIG. 2 obtained by blow molding a polystyrene resin or a high density polyethylene resin, a polystyrene resin or a polypropylene resin sheet to vacuum molding or the like. It can be used as a lid for a container produced by thermoforming.

For example, in the case of food container packaging, the draw-forming lid material of the present invention is supplied to a maker that manufactures food in the form of a laminated film or sheet wound in a roll shape,
Then, after punching into a circular shape, a molding machine (3) having a flat portion (31) in the shape of the container head and a skirt portion (32) having a ridge is used at room temperature using a molding machine as shown in FIG. Is drawn. Then, it is covered with a container made of the thermoplastic resin composition such as polyethylene or polystyrene filled with the contents and heat-sealed to be combined with the container to form a food container package.

Depending on the application, the lid material of the present invention, which is punched into the shape of the upper surface of the container in advance, is suction-conveyed onto a container filled with food and heat-sealed, and then squeezed so as to cover the mouth of the container. It can also be used by a method such as processing.

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. (Example 1) Polypropylene resin (manufactured by Grand Polymer Co., homopolymer grade; E-101MA, MF)
R 0.5g / 10min, 230 ° C, 21.2N) 65
%, Talc (Talc FVM manufactured by Shiraishi Calcium Co., Ltd.) 35
% Of the resin composition in a single screw extruder (cylinder diameter 65
mm) was used to form a film having a thickness of 100 μm at 230 ° C. After film formation, the laminate surface was subjected to corona treatment to obtain a film for the base material layer.

On the other hand, as the heat-sealing layer, (a) styrene-butadiene block copolymer resin (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Denkaclearene, styrene content 80)
%, Butadiene content 20%), (b) ethylene-butene-1 random copolymer (manufactured by Mitsui Chemicals, trade name: Toughmer A), (c) styrene-butadiene block copolymer (manufactured by JSR, trade name: STR resin, styrene 40
%, Butadiene 60%), and (d) high-impact polystyrene resin (manufactured by Toyo Styrene Co., trade name: Toyo Styrol HI-E6) are blended so as to be 40, 25, 25, and 10%, respectively. , A single screw extruder (cylinder diameter 40 mm) at a temperature of 200 ° C. to melt and knead to form compound pellets, and a single screw extruder (cylinder diameter 40 m)
m), extrusion temperature 200 ° C, blow-up ratio 2.0
A film having a thickness of 50 μm was formed at a double speed and a take-up speed of 20 m / min. Further, after the film formation, the laminate surface was subjected to corona treatment.

Next, using an extrusion laminator, the above-mentioned base layer film is fed out from one side, and an anchor coater on the corona-treated surface is used as an anchor coat agent of isocyanate two-component type (Takelac A971, Takenate, manufactured by Takeda Pharmaceutical Co., Ltd.). A3) is coated and dried, the heat-sealing layer film is fed from the other, and a low-density polyethylene resin (manufactured by Japan Polychem, extruded at a temperature of 320 ° C. by a single-screw laminator (cylinder diameter 65 mm) equipped with a T-die. Product name: Novatec LD) 30 μm thick
Extruded and laminated so that the total thickness is 180
A lid material stock having a thickness of μm was obtained.

The obtained raw material of the lid material is punched, drawn, conveyed, and commonly used for filling small beverage containers.
Evaluation was performed using a device for mounting a cap on the container (capping) and performing heat sealing (CH15 manufactured by Shikoku Kakoki Co., Ltd., changed to ultrasonic heating system). 1) Drawability: Diameter of 24mm when drawn at room temperature,
Immediately after molding a lid with a skirt length of 5.5 mm and 1
The spread of the tip of the skirt after the measurement was measured, and the spread was displayed from the diameter of the top surface by the spread angle (°) of the lid. 2) Transport / capping property: It was evaluated whether or not the draw-formed lid was smoothly transported when it was clogged in the shooter and was properly attached to the container. The evaluation results are shown in Table 1. The lid material produced according to the present invention has good draw formability,
The transport and capping properties were also appropriate.

[0026]

[Table 1]

(Example 2) Except that the thickness of the base material layer was 120 μm, the preparation was carried out in the same manner as in Example 1, and the total thickness was 200.
A lid material stock having a thickness of μm was obtained. Since this substrate had a thick base material layer, its drawability was further improved.

Example 3 A lid having a total thickness of 130 μm was prepared in the same manner as in Example 1 except that a uniaxially stretched HDPE film having a thickness of 50 μm (HIBRON C, manufactured by Mitsui Chemicals, Inc.) was used as the base material layer. I got a raw material. The skirt of this raw fabric was slightly spread, but it was usable without any trouble during transportation or capping.

(Comparative Example 1) A lid material stock having a total thickness of 180 µm was obtained in the same manner as in Example 1 except that talc of the base material layer was removed. This raw fabric had a springback phenomenon after drawing, and the shooter portion was clogged during transportation, and capping was not performed properly.

(Comparative Example 2) The talc content of the base material layer was 70%.
Fabrication was performed in the same manner as in Example 1 except that
An original lid material of 0 μm was obtained. In this raw material, the base material layer is brittle,
It could not be conveyed because it was torn when drawn.

(Comparative Example 3) 80 μm HI was used as a base material layer.
Fabrication was performed in the same manner as in Example 1 except that the PS film was used, and a lid material stock sheet having a total thickness of 160 μm was obtained. This material could not be formed by drawing and could not be conveyed.

Comparative Example 4 Table 1 shows the evaluation results using a commercially available aluminum lid material.

[0033]

The lid material obtained by the present invention is a laminate of a thermoplastic resin composition film which can be drawn by a lid material which does not use aluminum foil, and the shape of the drawn shape hardly changes with time. The lid is obtained. This molding lid has excellent packaging suitability, and the molding lid peeled off from the container after using the container is an environmentally friendly packaging material that can be recovered as plastic or can be easily incinerated without leaving an incineration residue that does not incinerate. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a layer structure of a lid member of the present invention.

FIG. 2 is a schematic diagram showing a state in which the molding lid covers the head of the container.

FIG. 3 is a perspective view showing the shape of a draw-formed lid.

FIG. 4 is a schematic diagram showing the definition of the spread angle of the skirt portion of the draw-formed lid.

FIG. 5 is a cross-sectional view showing a layer structure of a commonly used draw forming lid member using an aluminum foil.

[Explanation of symbols]

1 lid material 11 Base material layer 12 Adhesive layer 13 Heat seal layer 2 containers 3 Molding lid 31 Molded lid top surface 32 Molded lid skirt 33 Skirt spread angle 51 aluminum foil 52 Anchor coat 53 print layer 54 overcoat 55 anchor coat 56 polyethylene film 1 Hot melt adhesive

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3E067 AA04 AB26 BA07A BB14A                       BB25A BC07A CA24 CA30                       EA06 EA35 FA01 FC01                 3E084 AA04 AA12 AA24 AA25 AB01                       AB10 BA05 BA09 DA01 DC08                       FA09 FD13 GB08                 4F100 AK01A AR00B AT00A BA02                       DA03 GB16 GB23 JB16A                       JL01 JL12B JL16

Claims (3)

[Claims] 1. A draw-molding lid material comprising at least a base material layer and a heat-sealing layer, wherein the base material layer does not contain an aluminum foil and is made of a thermoplastic resin capable of draw-forming at room temperature. 2. A method of manufacturing a molding lid, which comprises drawing the laminated film according to claim 1. 3. A food package having a molded lid made of the lid material according to claim 1.