JP2006062697A - Laminate paper for shading paper container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide laminate paper for a shading paper container capable of uniformly shading the entire wavelength range including a visible ray region, a near ultraviolet ray region and a near infrared ray region, preventing the degeneration of contents by light, excellent in hygiene, high in the degree of whiteness, and capable of preventing the impairment of appearance. <P>SOLUTION: In the laminate paper for the shading paper container formed of cardboard as a base material, a black resin layer containing a black material and a white resin layer containing a white material are formed in this order on the side of the base material forming the outer face of the container, and a white ink layer is further formed thereon. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement of a laminated paper for a light-shielding paper container having a high surface whiteness and an excellent printing effect.

Conventionally, a laminated body mainly composed of paper (hereinafter abbreviated as laminated paper) has been widely used as a material for cups, cartons, trays, and other packaging containers.
However, when this laminated paper is used as a packaging container, the light rays may pass through the paper base material to affect the quality of the contents, particularly food. For example, when the content is sake, green tea, yogurt, fats and oils or high-fat ice cream, the pigment value may change or the taste may be lowered, resulting in a significant reduction in commercial value.
In order to prevent the deterioration of the contents as described above, it is necessary to control the light transmission of the laminated paper used (hereinafter abbreviated as “light shielding”).
However, the wavelength that causes the taste of the contents to deteriorate depends on the components of the contents, and it is necessary to uniformly shield all the wavelength ranges of the visible light region, the near ultraviolet region, and the near infrared region.
Conventionally, a laminated paper (hereinafter abbreviated as “light-shielding laminated paper”) that imparts light-shielding properties by pasting aluminum foil (hereinafter abbreviated as “aluminum foil”) on paper for the purpose of shielding such areas. The paper container obtained from was made.
In the case of paper containers obtained from light-shielding laminated paper bonded with aluminum foil, all wavelengths in the visible light region, near-ultraviolet region, and near-infrared region can be uniformly shielded, and sufficient in light-shielding performance. Although effective, there was a problem that burned residue of aluminum foil remained in the incinerator during incineration, or because the aluminum foil was metal, the metal detector could not inspect the contents as part of quality control. .

In order to solve this problem, for example, Japanese Utility Model Publication No. 59-103800 proposes a light-shielding laminated paper having a pulp layer that is not exposed to the middle layer of a multi-layer base paper. When the base paper is used, the light-shielding performance is superior to the base paper with only the ordinary bleached pulp layer, but the light-shielding performance is considerably inferior to that of the light-shielding laminated paper with aluminum foil. The bleached pulp layer alone cannot conceal the color of the middle unbleached pulp layer, and the whiteness of the surface of the base paper is insufficient, resulting in a poor design and a loss of commercial value.
Other methods include, for example, a light-shielding laminated paper in which a black ink is applied to the surface of a base paper and a white ink layer is provided on the black ink layer to conceal the black ink layer (Japanese Patent Laid-Open No. 07-052328). Alternatively, a black resin is laminated on the surface of the base paper, and a light-shielding laminated paper (Japanese Patent Laid-Open No. 09-024583) provided with a white resin layer on the black resin layer to conceal the black resin layer, or black ink on the base paper surface. A light-shielding laminated paper (Japanese Patent Laid-Open No. 10-129740) and the like, which is coated and provided with a white resin layer thereon to conceal the black ink layer, has been proposed.

However, it was difficult to obtain a laminated paper having both light shielding properties and surface whiteness even by these methods, that is, to reduce the amount of black ink applied to improve the surface whiteness, or to reduce the thickness of the black resin layer. If the thickness is reduced, the light shielding performance will be insufficient. On the other hand, increasing the amount of black ink applied to obtain sufficient light shielding performance, or increasing the thickness of the black resin layer will make it difficult to conceal with white ink or white resin alone. The whiteness was insufficient. For this reason, in order to deteriorate the design and cosmetic properties and impair the product value, it is not possible to provide a light-shielding layer on the outer side of the base paper container, and only to provide a light-shielding layer on the inner side of the base paper container. It was.
In particular, when the paper container is cup-shaped, the top part of the cup is curled outwards so that the sealing surface with the lid is on the inner surface of the cup, and a light-shielding layer is provided on the inner surface of the container When peeling the sealed lid from the inner surface of the cup, part of the white ink layer or white resin layer is peeled off, and the black ink layer or black resin layer is exposed on the top curl of the cup. Caused hygiene problems.
Because of such problems, development of a light-shielding laminated paper with high whiteness that can provide a light-shielding layer on the side of the base paper that is the outer surface of the container has been awaited.
Japanese Patent Application Laid-Open No. 07-052328

As a result of intensive studies on the above problems, the present inventors have found that sufficient surface whiteness and light shielding performance can be obtained by using a laminated paper provided with a black resin layer, a white resin layer, and a white ink layer on the base paper. The headline and the present invention were completed.
The problem to be solved by the present invention is that the entire wavelength range of the visible light region, the near ultraviolet region, and the near infrared region can be uniformly shielded, the alteration of the contents due to light rays is prevented, and the hygiene is excellent. It is another object of the present invention to provide a laminated paper for paper containers that has high whiteness and does not impair the appearance.

In order to achieve the above object, in the invention of claim 1,
In laminated paper for light-shielding paper containers based on base paper,
A black resin layer containing a black material is formed on one side of the substrate that is the outer surface of the container, a white resin layer containing a white material is formed on the black resin layer, and a white color is formed on the white resin layer. An ink layer is provided.
In the invention of claim 2,
The black material is carbon black, the white material is titanium oxide, the black resin, and the resin component of the white resin is polyethylene.
Furthermore, in the invention of claim 3,
The base paper has a basis weight of 100 to 500 g / m ² , a black resin layer has a thickness of 10 to 30 μm, and a white resin layer has a thickness of 10 to 50 μm.

  The laminated paper for light-shielding paper containers of the present invention can be used to uniformly shield all wavelengths in the visible light region, near-ultraviolet region, and near-infrared region by using it as a substrate for paper containers. Thus, it is possible to provide a paper container that is excellent in hygiene, has high whiteness, and does not impair the appearance.

Hereinafter, preferred embodiments of the laminated paper for light-shielding paper container of the present invention will be described in detail with reference to the drawings.
1 is a resin layer in the order of a black resin layer 3 containing a black material and a white resin layer 4 containing a white material on the side of the base paper 2 serving as a base material which is the outer surface of the container. And a white ink layer 5 provided thereon.

  Here, the paper container is obtained by forming a base material containing a base paper after being subjected to printing, cutting, provision of ruled lines for bending, punching for forming into a predetermined shape, as necessary. Examples of the shape include a cup type, a gable top type, a flat top type, a tetra type, a cylindrical type, and an assembled box.

Further, the base paper 2 is obtained by making a natural fiber, a synthetic fiber or a mixture thereof.
As natural fibers used for paper making, fir, todomatsu, shirabe, taiwan hinoki, cypress, cedar, larch, spruce, spruce, red pine, black pine etc. pulped conifer pulp, itaya maple, tochinoki, mizume, camphor, beech, honoki, Wood fibers such as broad-leaved pulp obtained by pulping dolonoki, linden, yachidamo, sharpener, drill, mizunara, zelkova, red oak, etc., animals such as plant fibers, wool, silk, etc. pulped from kenaf, bagasse, sugarcane, bamboo, hemp, etc. Examples thereof include mineral fibers such as fibers and asbestos.
As synthetic fibers, fibers obtained by fiberizing polyethylene, polypropylene, polyester, polyamide, cellulose acetate, polyvinyl alcohol, polyacrylonitrile, polyurethane and the like can be used.

Additives for the above-mentioned slurry mixed with raw materials include various anionic, nonionic, cationic or amphoteric paper strengths that have been used for the purpose of improving paper strength and imparting size performance as needed. An enhancer, a sizing agent and the like can be appropriately selected and used.
For example, various paper strength enhancers such as polyacrylamide-based anionic, nonionic, cationic or amphoteric resins, polyamine polyamide and derivatives thereof, cationic and amphoteric starch can be used as the paper strength enhancer.

As the sizing agent, various sizing agents such as rosin, petroleum resin, alkyl ketene dimer, and alkenyl succinic anhydride can be used.
Furthermore, generally known fillers, for example, mineral fillers such as talc, kaolin, calcium carbonate and titanium dioxide can be appropriately selected and used.
For the purpose of fixing these chemicals, inorganic compounds such as sulfuric acid bands can be used in appropriate combination.

As a papermaking additive, a pH adjusting agent, an antifoaming agent, a sticking agent and the like can be used as necessary.
In addition, starch, polyvinyl alcohol, polyacrylamide-based paper strength enhancers, and various surface sizing agents by coating methods such as size press coat, gate roll coat, calendar coat, blade coat, roll coat, air knife coat, and bar coat It is also possible to apply a pigment or the like.

The basis weight of the base paper 2 is preferably in the range of 100 to 500 g / m ² .
If the basis weight of the base paper is less than 100 g / m ² , the strength of the container will be weak and the container will be easily deformed due to impact during distribution, etc., which may cause problems in actual use. If the amount exceeds 500 g / m ² , the thickness increases and the level difference during molding of the container becomes large. This level difference cannot be sufficiently filled with the molten resin, and there is a risk of content leakage.

Next, the black fat layer 3 is provided on the side of the base paper 2 that is the outer surface of the container.
There is no restriction | limiting in particular as a black material contained in this black resin layer 3, Although carbon black, activated carbon, etc. can be used, when the dispersibility in resin is taken into consideration, it is preferable to use carbon black.

  Moreover, it is preferable that the thickness of this black resin layer 3 exists in the range of 10-30 micrometers. If the thickness of the black resin layer 3 is less than 10 μm, there is a possibility that all wavelengths in the visible light region, near ultraviolet region, and near infrared region cannot be shielded uniformly. On the other hand, when the thickness of the black resin layer 3 exceeds 30 μm, it is difficult to conceal the color of the black resin layer 3 with the white resin layer 4 and the white ink layer 5, which may impair the commercial value.

Furthermore, the weight concentration of the black material in the black resin layer 3 is preferably in the range of 1 to 10%.
If this weight concentration is less than 1%, the light shielding performance may be insufficient. On the other hand, if this weight concentration exceeds 10%, the color of the black resin layer 3 is changed to the white resin layer 4 and the white ink layer 5. It may be difficult to conceal and damage the commercial value, and at the same time, film breakage or the like is likely to occur during film formation by extrusion lamination or the like, which may cause production trouble.

Next, the white resin layer 4 is provided on the black resin layer 3 laminated on the base paper 2.
The white material contained in the white resin layer 4 is not particularly limited, and titanium oxide, kaolin, satin white, aluminum hydroxide, calcium carbonate, etc. can be used, but the concealability and dispersibility in the resin are taken into consideration. It is preferable to use titanium oxide.

The thickness of the white resin layer 5 is preferably in the range of 10 to 50 μm.
If the thickness is less than 10 μm, it is difficult to conceal the black resin layer 3 and the commercial value may be impaired. On the other hand, if the thickness exceeds 50 μm, the cost increases and the repulsive force of the resin layer May increase molding trouble during container molding.

Furthermore, the weight concentration of the white material in the white resin layer 4 is preferably in the range of 5 to 40%.
If the weight concentration is less than 5%, it is difficult to conceal the black resin layer 3 and the commercial value may be impaired. On the other hand, if the weight concentration exceeds 40%, the film is formed during film formation by extrusion lamination or the like. Cutting is likely to occur, and manufacturing trouble may occur.

  In addition, there is no particular restriction on the resin for dispersing the black material and the white material for forming the black resin layer 3 and the white resin layer 4. Polyester such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyamide such as nylon, ethylene vinyl acetate A thermoplastic resin such as a copolymer, an ethylene vinyl alcohol copolymer, an ethylene methacrylic acid copolymer, or an ethylene acrylic acid copolymer may be used. It is preferable to use vinyl acetate.

In addition, there is no restriction | limiting in particular in the method of providing the black resin layer 3 and the white resin layer 4, The film formed into a single layer or multiple layers using the black material and the white material containing resin is dry-laminated, wet-laminated, and sand-laminated. It is obtained by laminating the surface of the base paper with a processing method such as the above, or by extruding and laminating the black material-containing resin on the side of the base paper that becomes the outer surface of the container, and then extruding and laminating the white material-containing resin.
Further, physicochemical treatment such as corona treatment, plasma treatment, and ozone treatment can be performed during or before the laminating process, and the molten film can be subjected to ozone treatment at the time of extrusion lamination.

Next, in order to improve the surface whiteness of the base paper 2, a white ink layer 5 is provided on the white resin layer 4.
The coating amount of the white ink layer 5 is also preferably in the range of 0.5 to 10 g / m ^{2 when} dry.
If the coating amount of the white ink layer 5 is less than 0.5 g / m ² , the hiding performance is insufficient and the commercial value may be impaired. On the other hand, if the coating amount of the white ink layer exceeds 10 g / m ² It is necessary to coat a plurality of times with a printing machine, which increases the cost and at the same time may cause the ink layer to become too thick and cause printing cracks during container molding.

Examples of the light-shielding paper container laminated paper 1 and comparative examples for the same will be described below. The present invention is not limited to these examples.
[Example 1]
A black polyethylene layer (PE-M SSC 90086 Black, manufactured by Dainichi Seika Co., Ltd.) containing 6% carbon black on one side of a general cup base paper (manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 250 g / m ² and a Tosoh low Density polyethylene “Petrocene 204” mixed at a weight ratio of 20/80) 20 μm was extruded and laminated at a resin temperature of 330 ° C., and then a white polyethylene layer containing 20% titanium oxide (a white masterbatch made by Dainippon Ink, “Peony” White L-10966M "and Tosoh low-density polyethylene" Petrocene 204 "mixed at a weight ratio of 20/40) 30 µm were extruded and laminated at a resin temperature of 330 ° C, and then white ink (" XOS1200 made by Dainippon Ink "). by printing at 4g / m ² white ") in a dry coat amount To obtain a light-shielding laminated paper Example 1.

[Example 2]
A black polyethylene layer containing 3% carbon black (Daiichi Seika black masterbatch “PE-M SSC 90086 Black”) and low-density polyethylene manufactured by Tosoh on one side of an acid-resistant cup base paper (manufactured by Tokyo Paper Co., Ltd.) having a basis weight of 270 g / m ² “Petrocene 204” mixed at a weight ratio of 10/90) 20 μm was extruded and laminated at a resin temperature of 330 ° C., and then a white polyethylene layer containing 20% titanium oxide (a white master batch “Peony White L- 10966M ”and Tosoh low density polyethylene“ Petrocene 204 ”mixed at a weight ratio of 20/40) 30 μm was extruded and laminated at a resin temperature of 330 ° C., and then white ink (“ XOS1200 White ”manufactured by Dainippon Ink) the implementation by printing at 4g / m ² by dry coating amount example 2 To obtain a light-shielding laminated paper.

[Comparative Example 1]
A basis weight of 250g / ^{m 2} of the general cup base paper for black ink on one side of the (Tokyo manufactured by Paper Co., Ltd.) (manufactured by Dainippon Ink "XOS1200 ink") is printed at 4g / ^{m 2} in the dry coating amount, from above Titanium oxide 20% -containing white polyethylene layer 30 μm prepared at the same blending ratio as in Example 1 was extruded and laminated at a resin temperature of 330 ° C. to obtain a light-shielding laminated paper.

[Comparative Example 2]
A black polyethylene layer containing 3% carbon black on one side of a general cup base paper (manufactured by Tokyo Paper Industries Co., Ltd.) with a basis weight of 250 g / m ² (a black masterbatch “PE-M SSC 90086 Black” manufactured by Dainichi Seika Co., Ltd.) Density polyethylene “Petrocene 204” mixed at a weight ratio of 10/90) 20 μm was extruded and laminated at a resin temperature of 330 ° C., and then a white polyethylene layer containing 20% titanium oxide was extruded at a resin temperature of 330 ° C. Lamination was performed to obtain a light-shielding laminated paper.

[Comparative Example 3]
Light-shielding base paper (manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 300 g / m ² was obtained by using unexposed pulp for the middle layer and making paper using the pulp exposed to the front and back layers.

FIG. 2 shows the results of the investigation of the light shielding performance and surface whiteness of the light shielding laminated paper and the light shielding base paper obtained in each of the above Examples and Comparative Examples.
The various evaluations were performed according to the methods described below.
As a result, it was confirmed that the light-shielding laminated papers of Examples 1 and 2 had excellent light-shielding performance and high surface whiteness.

[Light shielding evaluation method]
No. of quantitative filter paper with a spectrophotometer manufactured by JASCO Corporation. The light transmittance T was determined by measuring the laminated paper obtained in Examples 1-2 and Comparative Examples 1-3 on the basis of 5C (manufactured by Toyo Roshi Kaisha, Ltd.) in the wavelength range of 250 nm to 850 nm. The light transmittance T was determined by T = (Ti / To) × 100, where To is the light transmittance of the quantitative filter paper itself, and Ti is the light transmittance of the laminated paper itself.

[Surface whiteness evaluation method]
The whiteness (%) of the laminated paper obtained in Examples 1-2 and Comparative Examples 1-3 was measured with a Hunter whiteness tester according to JIS P8123.
In addition, since the surface whiteness of the base paper which did not perform printing on the surface at all using bleached pulp was 80 to 85%, it was judged that if this whiteness was 80% or more, it could be used on the outer surface of the container.

It is a schematic diagram which shows the cross section of the laminated paper for light-shielding paper containers. It is a table | surface which shows the result of evaluation of an Example and a comparative example.

Explanation of symbols

1 Laminated paper for light-shielding paper container 2 Base paper 3 Black resin layer 4 White resin layer 5 White ink layer

Claims (3)

In laminated paper for light-shielding paper containers based on base paper,
A black resin layer containing a black material is formed on one side of the substrate that is the outer surface of the container, a white resin layer containing a white material is formed on the black resin layer, and a white color is formed on the white resin layer. A laminated paper for a light-shielding paper container, which is provided with an ink layer.   The laminated paper for a light-shielding paper container according to claim 1, wherein the black material is carbon black, the white material is titanium oxide, a black resin, and the resin component of the white resin is polyethylene. ^2. The light-shielding paper container according to claim 1, wherein the base paper has a basis weight of 100 to 500 g / m ² , a black resin layer has a thickness of 10 to 30 μm, and a white resin layer has a thickness of 10 to 50 μm. Laminated paper.

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