JP2000006294A - Heat sealable cover material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit inspection by a metal detector and heating by a microwave oven and improve disposability after use by laminating a light blocking ink layer to the inner surface of a paper layer, specifying the optical transmittance of a cover material, and laminating an easy-peeling resin layer through an adhesive layer to the light blocking ink layer. SOLUTION: A heat sealable cover material 10 is constructed such that, as a base material of a paper layer 1 supplied with a water retentive, at the side of the outer surface an ink layer 2 such as letters or designs is printed, and a transparent over-printed layer 3 is printed thereon, while at the side of the inner surface of the paper layer 1 a light blocking ink layer is laminated, and an easy peeling resin layer 5 of the innermost layer is laminated thereon through an adhesive layer 5. The optical transmittance of the cover material 10 in the wavelength region of 200-800 nm is 15% or less, and the paper layer 1 is a double face coating paper having a basis weight of 80-110 g/m2. The easy peeling resin layer 6 of the innermost layer is polyethylene, and an uneven pattern is shaped to the cover plate 10, which is in the form of sheet punched to a predetermined shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sealing lid for a cup-type container for food, and more particularly, to a material mainly composed of paper and resin except for a metal such as aluminum foil from a constituent material of the lid. In addition to imparting inspection suitability with a metal detector, heating suitability with a microwave oven, etc., there is no curl, light shielding and good food preservability, and when opening, the paper layer of the lid material and The present invention relates to a heat-sealing lid material having excellent overall performance, in which the entire lid material can be opened cleanly without peeling between layers or the like, and furthermore, has excellent disposal properties after use.

[0002]

2. Description of the Related Art Conventionally, as a lid material for a food cup type container, for example, a heat-sealing lid material having a constitution of paper / polyethylene / aluminum foil / polyethylene / hot melt layer is generally used. . An aluminum foil having a thickness of 15 μm or more is used for the aluminum foil layer of the lid member having this configuration in terms of its rigidity, plastic deformation, curl prevention, and the like. Further, as the lid material having no aluminum foil, for example, a configuration such as paper / adhesive or polyethylene / biaxially stretched plastic film / polyethylene / hot melt layer is known.

[0003]

However, in the lid member using the aluminum foil, curling can be reduced due to rigidity and plastic deformability, which are characteristics of the aluminum foil. Partial opening of the lid material and good reclosability when it is returned,
Although it has advantages such as excellent light-shielding properties, it is not possible to inspect the contamination of metal foreign substances with a metal detector after filling the contents, and it is not possible to heat the contents with a microwave oven at the time of use, and the cost is also high, and after use There was also a problem with regard to the disposability of waste, such as the fact that incineration left a burnt residue and landfill did not decompose it.

[0004] The latter, which does not use an aluminum foil, eliminates the disadvantages caused by the use of the aluminum foil, but on the other hand, loses the advantages of using the aluminum foil and easily causes curling. In addition, at the time of opening, there is a problem that the opening property due to the bending of the lid material and the reclosability due to the return thereof are reduced, and the light-shielding property of the lid material is also reduced, so that the storage stability of the contents is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to remove paper such as aluminum foil from the constituent materials of the cover material and to mainly use paper and resin. By being made of a material, inspection by a metal detector and heating by a microwave oven are enabled, while improving disposability after use, curling is reduced, and at the time of opening, opening property by bending a lid material, and It is an object of the present invention to provide a heat-sealing lid material having excellent overall performance, that is, good reclosing property by return, good light-shielding property, and excellent easy peeling property with high productivity.

[0006]

The above objects can be attained by the present invention described below. That is, according to the invention described in claim 1, in a lid member using a laminated sheet including a paper layer to which a water retention agent is supplied and the innermost layer being an easy-peelable resin layer, at least the inner side of the paper layer is shielded from light. A lid having a light transmittance of 15% or less in a wavelength region of 200 to 800 nm, and the easy-peelable resin layer laminated on the light-shielding ink layer surface via an adhesive layer. It is made of a heat-sealing lid material characterized by being made.

[0007] By adopting such a configuration, the moisture content of the heat-sealing lid material becomes stable over time because the water retention agent is supplied to the paper layer as the base material. And
In the production of the lid material, a water retention agent is applied to the outer surface side of the paper, dried and supplied, and when the ink and overprint varnish are printed thereon, such as characters and pictures, the paper is dried.
The outer surface side shrinks, temporarily producing a concave curl on the outer surface side, and then printing a light-shielding ink layer on the inner surface side,
Furthermore, by laminating the innermost easy-peeling resin layer via an adhesive layer, a slight shrinkage occurs on the inner surface side, so that a concave curl force acts on the inner surface side, and the lid The balance of shrinkage can be taken on both sides of the material,
Curling can be prevented from occurring.

The light-shielding ink layer is laminated at least on the inner surface side of the paper layer, and the lid material has a thickness of 200 to 800.
Since the light transmittance in the wavelength region of nm is 15% or less, the deterioration of the oil component in the food susceptible to light can be prevented, and the preservability of the food can be improved. Furthermore, since the easy-peeling resin layer is laminated on the innermost layer via the adhesive layer, heat sealing and easy-peeling can be imparted to the cover material. In addition, since metal such as aluminum foil is not used for the component material of the lid material, it is possible to inspect metal foreign substances with a metal detector and heat it with a microwave oven, and it is inexpensive and has excellent disposal properties after use. I have.

[0009] In the invention described in claim 2, the paper layer comprises:
It consists of heat-sealing properties lid material according to claim 1, wherein a double-sided coated paper having a basis weight 80~110g / m ^2.

By adopting such a configuration, the paper layer has an appropriate thickness and rigidity, which contributes to prevention of curling. In addition, a part of the lid is bent at the time of opening to form an opening. Then, it is possible to easily return the bent portion and close the opening. Furthermore, the paper layer is a double-sided coated paper, and a so-called clay coat is applied to both surfaces thereof, so that the coated layer itself has a certain degree of light shielding properties,
Both sides of the paper layer have excellent surface smoothness and printability, and improve the printing effect of characters and pictures on the outer surface, and
It is possible to form a uniform film of the light-shielding ink layer on the inner surface side, and to improve the light-shielding property. In particular, since the light-shielding ink layer on the inner side also has a sealing effect on the paper surface,
When laminating the innermost easy-peeling resin layer via an adhesive layer, even if the adhesive is applied to the light-shielding ink layer surface, the adhesive is not absorbed by the paper layer etc., and the adhesive is effective And sufficient lamination strength can be obtained with a small amount of adhesive.

According to a third aspect of the present invention, in the heat sealing lid material according to the first or second aspect, the innermost easy-peeling resin layer is made of a polyethylene-based easy-peeling resin. Become.

[0012] The easy-peeling resin is originally formed by blending various resins, and therefore has many types and various components. For example, when ethylene is used as the main component of the main resin, Similarly, propylene can be classified as a polypropylene-based easy-peel resin, and styrene can be classified as a polystyrene-based easy-peel resin.

Among these, polyethylene-based easy-peeling resins are relatively versatile in heat sealing properties for containers made of various materials, are excellent in low-temperature sealing properties, and have a wide range of sealing conditions such as sealing temperature. In addition, the sealing strength can be easily adjusted, which is preferable because it can be suitably used not only for plastic molded containers but also for paper cup containers in which polyethylene is laminated on the inner surface. When used for a lid material of a paper cup container using such a polyethylene laminated paper, in order to obtain good easy-peeling properties, the sealing strength should be 200 to 500 g / l.
It is necessary to adjust the width to about 5 mm, but such adjustment is sufficiently possible.

Specific examples of such polyethylene-based easy-peeling resins include low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene and acrylic acid, or methacrylic acid, or a copolymer thereof with an ester thereof. And a resin in which a styrene-based polymer, a styrene-based elastomer, polybutene-1, and other tackifiers are appropriately blended. Therefore, by adopting such a configuration, workability of heat sealing is improved, and stable heat sealability and easy peelability can be obtained.

[0015] The invention according to claim 4 is a single-wafer form in which an uneven pattern is formed on the heat-sealing lid material, and the heat-sealing lid material is punched into a predetermined shape. The heat-sealing lid according to any one of claims 1 to 3, characterized in that:

The heat-sealable lid material of the present invention can of course be used in a filling sealing machine or the like using a roll-shaped lid material as the roll-shaped lid material. By taking, even if the heat-sealing lid material punched on a single sheet is stacked, the contact area between the lid materials decreases,
Since there is no blocking, and the sliding property between the front and back of the lid material is also improved, even when used in an automatic filling and sealing machine using a sheet-shaped lid material, the suitability of feeding the lid material is good. It can be used satisfactorily without troubles such as double insertion.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the heat-sealing lid material according to the present invention, such as the configuration and manufacturing method thereof, will be described with reference to the drawings. FIG. 1 and FIG. 2 are schematic cross-sectional views each showing the configuration of one embodiment of the heat-sealing lid material of the present invention. However, the present invention is not limited to these drawings.

The heat-sealing lid material 10 shown in FIG. 1 is based on a paper layer 1 to which a water retention agent has been supplied, and has a character,
Printing an ink layer 2 such as a picture, a transparent overprint layer 3 thereon, and a light-shielding ink layer 4 on the inner side of the paper layer 1 by printing or coating means;
It has a configuration in which an innermost easy-peeling resin layer 6 is laminated thereon via an adhesive layer 5.

In the above configuration, the paper layer 1 serves as a base material of the heat-sealing lid material 10 and has rigidity, excellent mechanical strength such as tensile strength and tear strength, and excellent interlayer strength. Since an ink layer is provided on both sides by printing or the like, it is preferable that the ink layer is also excellent in printability. Therefore, although not particularly limited, for example, when the grammage is 8
At about 0 to 110 g / m ² , a double-sided coated paper having a so-called clay coat on both sides can be suitably used. Basis weight 8
When the weight is less than 0 g / m ² , the rigidity and mechanical strength are insufficient, so that the lid material is likely to be curled or torn, and when the basis weight exceeds 110 g / m ² , the rigidity is already sufficient. There is no further need, and rather it takes time for heat sealing, and the interlayer strength of the paper tends to decrease, which is not preferable.

The water retention agent supplied to the paper layer 1 includes:
A water retention agent containing water, alcohols, polyethyleneimine or the like as a main component can be used, and as the alcohols, methanol, ethanol, isopropyl alcohol, butanol and the like can be used. As specific examples of the water retention agent, water 85% by weight, ethanol 14% by weight,
A water retention agent having a composition such as 1% by weight of polyethyleneimine may be used. A method of supplying such a water retention agent to the paper layer 1 is, for example, when printing characters, patterns, and the like on the outer surface side of the paper layer 1 by gravure printing or the like, using a multicolor gravure printing machine in the first unit. By printing a water retention agent using a solid plate, drying excess water and alcohol, followed by printing characters and pictures and printing overprint varnish,
The water retention agent can be supplied to the paper layer 1 in-line with the printing on the outer surface.

Next, the light-shielding ink layer 4 laminated on the inner surface side of the paper layer 1 is provided to improve the light-shielding property of the lid material and to improve the preservability of contents such as food. It is preferable to absorb or reflect light in the wavelength region of 200 to 800 nm to block the light, and to set the light transmittance of the cover member in this wavelength region to 15% or less. As the pigment used in the light-shielding ink layer 4, for example, a black pigment such as carbon black can be used to shield light substantially even if used alone. However, even if it is the inner surface of the lid, the black pigment alone is not necessarily preferable as a lid for a food container in terms of design and image.

Therefore, it is preferable to use a combination of a black pigment and a white pigment from the viewpoint of achieving both the light-shielding property and the design property of the cover material. In this case, the light-shielding ink layer 4 may be provided by, for example, printing an ink prepared by mixing a black pigment and a white pigment to form the light-shielding ink layer 4, or using a black pigment. A black ink and a white ink using a white pigment may be separately prepared, the black ink may be printed first, and the white ink may be overprinted thereon to cover the black ink layer. .

As the white pigment used in the light-shielding ink layer 4, titanium dioxide, zinc white, calcium carbonate, clay (kaolin), barium sulfate and the like can be used. These white pigments are mainly used. Ultraviolet light of 390 nm or less can be effectively blocked. Further, as the black pigment, in addition to carbon black, the following organic or inorganic pigments can be appropriately combined and used. Specifically, among the organic pigments, phthalocyanine pigments, insoluble azo pigments, azo lake pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, diketopyrrolopyrrole pigments, anthrapyridine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments , Perinone pigments, perylene pigments, isoindolinone pigments, thioindigo pigments and the like, and inorganic pigments,
Iron oxide, ultramarine, navy blue, cobalt oxide, strontium chromate, titanium yellow, zinc chromate, iron black,
Molybdenum red, emerald green, cadmium yellow, cadmium red, cobalt blue and the like.

Such a light-shielding ink layer 4 can be additionally provided below the ink layer 2 such as characters and pictures on the outer surface side of the paper layer 1 as necessary. However, in such a case, it is necessary to consider the color tone to the extent that the design of the design on the outer surface is not impaired. Further, such a light-shielding ink layer 4 may be provided by a coating means in addition to the printing means, and the coating amount is preferably 4 to 10 g / m ^{2 in} solid content.

Next, an innermost easy-peel resin layer 6 is laminated on the light-shielding ink layer 4 with an adhesive layer 5 interposed therebetween. As a method of laminating an easy-peelable resin layer, generally, after applying an anchor coat agent to the laminating surface thereof, in addition to a method of extruding and coating the easy-peelable resin and laminating, polyethylene and other polyolefin-based resins and the like An extrusion lamination method (also called a sandwich lamination method) in which an easy-peelable resin film formed in advance is press-bonded with a roll and laminated while extruding and coating an adhesive resin on a laminated surface, and furthermore,
There is a dry lamination method in which an easy-peeling resin film formed in advance through an adhesive such as a two-liquid curing type is bonded.

However, both of the above two methods are not preferable because the melted resin is coated on the lamination surface, so that the resin shrinks after lamination and the curl of the lid material becomes large.
In this regard, the third dry lamination method is not exposed to a high temperature at which the resin is melted during lamination, and by applying the adhesive application surface to the light-shielding ink layer surface on the substrate side, Since the tension applied to the easy-peeling resin film can also be reduced, a lid material without curl can be produced without causing significant shrinkage after bonding.

Accordingly, in the present invention, a dry lamination method is employed, an adhesive for dry lamination is applied to the surface of the light-shielding ink layer 4, and an easy-peeling resin film formed in advance is laminated thereon. It is to be laminated. For such an adhesive layer 5, for example, a known polyurethane-based adhesive composed of a polyol component and a polyisocyanate component can be used, and for the easy-peelable resin layer 6, as described above. It is preferable to use a film in which a suitable polyethylene-based easy-peeling resin is formed in advance, and its thickness is suitably in the range of 25 to 40 μm.

The heat-sealing lid 20 shown in FIG. 2 has the same laminated structure as that of the heat-sealing lid 10 shown in FIG. As shown, the cover member 20 is formed by shaping an uneven pattern. Such a concavo-convex pattern is provided in order to improve the blocking resistance of the lid member 20 and the suitability of the lid member 20 to be fed out in a filling and sealing machine in the case of a single wafer form. There is no limitation, and a void may be formed between the lid members 20 that are wound up or overlapped in a single-wafer form, the contact area may be reduced, and the lid member 20 may have a shape that does not impair the slipperiness of the stacked lid members 20. Any shape can be provided.

In the lid member 20 shown in FIG. 2, the pattern of the irregularities is relatively large, and is formed so as to cover all layers of the lid member 20 as shown by the concave and convex portions 7 and 7 '. The concavo-convex pattern may be made fine, such as a cloth shape or a line shape, and provided so as to be formed only on one of the inner surface and the outer surface of the lid member 20. It is not necessary to increase the height difference of such uneven portions, and particularly when the uneven pattern is a fine cloth or linear shape, 5 to 25 μm
A degree is enough. In addition, the method of providing the concavo-convex pattern can be easily provided by a known embossing method.

[0030]

The present invention will be described more specifically below with reference to examples. (Example 1) A heat-sealing lid material 10 having the structure shown in FIG. 1 was produced, and a double-color coated paper having a basis weight of 90 g / m ² was used as a base paper, and a multicolor gravure was formed on the outer surface thereof. Using a printing machine, 85% by weight of water and 1
A water retention agent consisting of 4% by weight and 1% by weight of polyethyleneimine was printed on a solid plate having a plate depth of 25 μm, dried, and supplied.
In the subsequent units, printing was performed on the ink layer 2 and the overprint layer 3 such as characters and pictures. In this step, a part of the water retention agent is dried from the outer surface side of the paper layer 1.

Next, using a multicolor gravure printing machine, a gray ink produced by adding a mixed pigment of carbon black and titanium oxide was used on the inner surface side of the paper layer 1 to obtain a plate depth of 35.
Using a solid μm plate, two units were overprinted to provide a light-shielding ink layer 4 having a coating amount of 6 g / m ² (solid content).
Next, a two-component curable polyurethane-based adhesive is used as the adhesive layer 5 on the light-shielding ink layer 4 by a dry lamination method so that the coating amount when dried is 3 g / m ^2. After removing the solvent component by hot air drying, a 30 μm-thick polyethylene easy film obtained by blending polybutene-1 and a polystyrene-based resin with low-density polyethylene as an innermost easy-peelable resin layer 6 thereon. Laminate and peel the peel resin film,
A heat-sealing lid material 10 of Example 1 was produced.

Example 2 A heat-sealing lid 20 having the structure shown in FIG. 2 was prepared. Using the embossed plate of the pattern combined with
The embossed pattern was formed by embossing in the direction in which the outer surface side of No. 0 swelled, and the heat-sealing lid material 20 of Example 2 was produced. still,
The height of the convex portion on the outer surface side of the lid member 20 and the depth of the concave portion on the inner surface side are approximately 20 μm.

Each of the heat-sealable lids of Examples 1 and 2 produced as described above was punched out into a circular shape having a diameter of 100 mm and a knob with a part of the outer periphery, and a sheet-shaped lid material. Were prepared, and the light-shielding property, the curl state, and the easy peel property after heat sealing were examined as described below.

(1) Light-Shielding Property The light transmittance in the wavelength region of 200 to 800 nm was measured using a self-recording spectrophotometer UV-2200 (manufactured by Shimadzu Corporation). Transmittance 10
% Or less.

(2) Measurement of curl Twenty samples were sampled at random for each lid material, and were placed on a horizontal glass plate one by one with the outer surface of the lid material facing up.
The height (mm) of the highest portion was measured, and the average value was taken as the curl value. As a result of the above measurement, the curl value of each of the samples of Examples 1 and 2 was as small as 4 mm, which was good. Incidentally, as a conventional result, when the curl value is 5 mm or less, the mechanical suitability of the automatic filling and sealing machine is good. In particular, since the lid material of Example 2 has a concave-convex pattern, it has not only a small curl but also a blocking resistance and a moderate sliding property. It could be used satisfactorily with an automatic filling and sealing machine.

(3) Easy Peelability Each lid material of Examples 1 and 2 was attached to the flange portion (joining surface of polyethylene) of a paper cup container having polyethylene laminated on the inner surface at 140 ° C. with a ring sealer at a pressure of 6 k.
Heat sealing was performed under the conditions of g / cm ² and a pressure bonding time of 1.0 second. After one day, the lid material was peeled off, and the condition of the peeled portion and easy peelability were examined. As a result, in both cases, the peeled portion is between the easy-peelable resin layer of the lid material and the flange portion (polyethylene layer) of the container, and the interlayer of the lid material and the container is not broken, and the peeled surface is It was in a beautiful condition. In addition, easy peelability was good because the film could be peeled off with an appropriate strength.

[0037]

As described in detail above, according to the present invention, the present invention has a light-shielding property, has a good preservability of contents such as foods, and has no curl even when used as a single-sheet punched sheet material. It has good mechanical suitability for automatic filling and sealing machine, and has good heat sealing and easy peeling properties. It is also possible to heat the contents, and it is also excellent in disposal after use,
The present invention has the effect of providing a heat-sealing lid material excellent in overall performance and suitability for use with good productivity.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration of an embodiment of a heat-sealing lid material of the present invention.

FIG. 2 is a schematic sectional view showing the configuration of another embodiment of the heat-sealing lid material of the present invention.

[Explanation of Signs] 1 Paper layer supplied with water retention agent 2 Ink layer for characters and pictures 3 Overprint layer 4 Light-shielding ink layer 5 Adhesive layer 6 Easy-peel resin layer 7, 7 'uneven portion 10, 20 Heat-sealing lid material

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 3E067 AB01 BA07A BB01A BB14A BB25A BC07A CA12 EA13 EB27 4F100 AA21H AA37H AK01B AK04B AK06 AK09 AK12 AK31H AK51G AL05 BA03 BA04 BA07 BA10BCA00 CCB CCB CAB CAB CAB CAB CAB CAB CCB CAB CAB CAB CAB CAB CAB CAB CAB CAB CAB CAB CAB CAB CAB CAB CAB CAB JL00 JL01 JL04 JL12 JL14B JN02C YY00A YY00C

Claims (4)

[Claims] 1. A lid comprising a laminated sheet including a paper layer to which a water retention agent is supplied and an innermost layer being an easy-peelable resin layer, wherein a light-shielding ink layer is laminated at least on the inner surface side of the paper layer. The light transmittance of the lid material in a wavelength region of 200 to 800 nm is 15% or less, and the easy-peelable resin layer is laminated on the light-shielding ink layer surface via an adhesive layer. Heat-sealing lid material. 2. The heat-sealing lid material according to claim 1, wherein said paper layer is a double-coated paper having a basis weight of 80 to 110 g / m ² . 3. The innermost easy-peeling resin layer,
3. The heat-sealing lid material according to claim 1, which is a polyethylene-based easy-peeling resin. 4. The heat-sealing lid material according to claim 1, wherein an uneven pattern is formed on the heat-sealing lid material, and the heat-sealing lid material is in a single-sheet form punched into a predetermined shape. 4. The heat-sealing lid material according to any one of 3.