JP2004075111A - Colored dampproofing corrugated board box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To give a color for setting off contents, such as fruit and vegetables, to the interior of a box without using an extra packaging material. <P>SOLUTION: The dampproofing corrugated box has a dampproofing coating layer, which is made of a dampproofing coating material mainly composed of a synthetic resin emulsion and a plate pigment having an aspect ratio of 5 or more, on the interior or the exterior thereof, and the coating layer contains a dye or a colored pigment, which has a solid portion ratio of 0.5 to 10%. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a colored moisture-proof and moisture-proof cardboard box mainly used for packing fruits and vegetables.
[0002]
[Prior art]
Conventionally, a moisture-proof corrugated cardboard box has been used mainly for packing fruits and vegetables. The moisture-proof corrugated cardboard box has a moisture-proof layer provided on at least one surface of the cardboard box, and has a freshness-retaining effect due to the effect of the moisture-proof layer on the evaporation of fruits and vegetables.
As a method for imparting moisture resistance, there is known a method in which a thermoplastic synthetic resin film such as polyethylene is laminated on a corrugated cardboard liner surface.
However, it is difficult to recover such cardboard as waste paper and reuse it as a raw material for pulp, and at present, most of the cardboard must be landfilled or incinerated as industrial waste.
[0003]
For this reason, as the trend of resource recycling has been fostered in recent years, various cardboards that have a waterproof function, become a raw material of waste paper pulp after use, and can be recycled have been proposed.
For example, Japanese Patent Publication No. 2-1671 discloses that a waterproof layer is formed by coating a synthetic resin emulsion and a wax emulsion on the surface of a corrugated cardboard.
However, when such a corrugated cardboard is used as raw material waste paper, problems such as pitch trouble due to wax and occurrence of blot on the paper surface occur. Further, for example, when a liner base paper is manufactured, there is a problem that the surface of the liner becomes slippery. In addition, when the core base paper is manufactured, there is a problem in that poor adhesion is likely to occur when the core base paper is bonded to the liner.
[0004]
Then, as a technique of moisture-proof corrugated cardboard which solves the above-mentioned problem, there are Japanese Patent Application Laid-Open No. 10-194326 and Japanese Patent Application No. 2001-187519.
These techniques, the corrugated board sheet surface, synthesized by the resin emulsion and the flat pigment to form a moisture barrier to the main component, the moisture permeability 10~500g ^/ m 2 · 24hr (typically corrugated sheet is 1000 to 3000 g / m it is an ² · 24hr).
[0005]
Since these do not use a film, they can be easily disintegrated and are waxless, so they have excellent recyclability without problems such as pitch trouble caused by wax and occurrence of spots on the reproduced paper surface. Things.
[0006]
By the way, usually, the outer surface of cardboard for fruits and vegetables is printed. The printing not only shows the type, quantity, production area, quality, etc. of the contents, but also plays a role in increasing the commercial value of the contents through advertising and promotional effects and cosmetics. In order to improve the appearance of the product and enhance the value of the product, it is required to color the inside of the cardboard box with a color that enhances the product.
However, since a moisture-proof cardboard box for keeping freshness of fruits and vegetables is provided with a moisture-proof layer on at least one surface (usually the inner surface of the box), if a printed layer is provided on one side, the other side which is a moisture-proof layer is provided. Was difficult to color.
Therefore, when a color is required inside the box, it is widely practiced to pre-lay a sheet-like packaging material such as colored wax-impregnated paper inside the cardboard box and wrap the contents such as fruits and vegetables. ing. For example, when packaging eggplants, a method has been adopted in which wax-impregnated paper colored in purple or the like is placed in advance in a cardboard box, the eggplant is wrapped therein, and the cardboard box is sealed.
However, this method requires extra packaging materials, which is time-consuming and costly.
[0007]
[Problems to be solved by the invention]
Therefore, there is a demand for a colored moisture-proof cardboard box that can give a color that enhances the contents such as fruits and vegetables inside the box without using an extra packaging material.
[0008]
[Means for Solving the Problems]
The present invention employs the following method to solve the above problems.
That is, the present invention relates to a moisture-proof corrugated cardboard box having a moisture-proof coating layer in which a synthetic resin emulsion and a flat pigment having an aspect ratio of 5 or more are coated on the inner or outer surface of the box. It is a colored moisture-proof cardboard box containing a dye and / or a colored pigment in the working layer.
[0009]
A second aspect of the present invention is the colored moisture-proof cardboard box according to the first aspect, wherein the solid content ratio of the dye and / or the color pigment in the moisture-proof coating layer is 0.5 to 10%.
[0010]
The third aspect of the present invention is the colored moisture-proof cardboard box according to the first or second aspect of the present invention, wherein the moisture-proof coating layer contains a particulate pigment having an aspect ratio of 3 or less and an average particle diameter of 5 to 15 μm. .
[0011]
A fourth aspect of the present invention is a package obtained by packaging fruits and vegetables in the colored moisture-proof cardboard box according to any one of the first to third aspects of the present invention.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described specifically.
The present invention is a colored moisture-proof cardboard box provided with a coating layer made of a synthetic resin emulsion, a tabular pigment having an aspect ratio of 5 or more, and a dye or a colored pigment, and a moisture-proof paint.
[0013]
The tabular pigment in the present invention refers to those having an aspect ratio of 5 or more, and those having an aspect ratio of 10 or more are more preferably used.
Since the pigment having an aspect ratio of less than 5 has insufficient flatness, the pigment cannot be oriented in parallel with the coating surface during coating, and therefore, excellent moisture resistance cannot be obtained. The higher the aspect ratio, the greater the number of layers in the coating layer of the tabular pigment, so that high moisture-proof performance is exhibited.
[0014]
Specific examples of the tabular pigment include a phyllosilicate compound (a layered silicate compound having a layered structure). Those belonging to the phyllosilicate compounds are plate-like or flaky and have distinct cleavages, and mica, pyrophyllite, talc, chlorite, septe chlorite, serpentine, stilpnomeraine , There are clay minerals. Of these, mica and talc are preferred. Mica includes muscovite (muscovite), sericite (sericite), phlogopite (flokopite), biotite (biotite), fluorophlogopite (artificial mica), red mica, soda mica, vanadin mica, illite, Chin mica, paragonite, brittle mica and the like.
Among these phyllosilicate compounds, muscovite, phlogopite or sericite is more preferable in terms of the particle size, aspect ratio, and the like.
[0015]
The average particle size of the tabular pigment suitably used in the present invention is from 1 to 100 μm, more preferably from 5 to 50 μm.
In the case of a tabular pigment having an average particle diameter of less than 5 μm, the orientation of the tabular pigment in the coating layer is unlikely to be parallel to the support, and when it exceeds 50 μm, a part of the tabular pigment protrudes from the coating layer. In addition, as the thickness of the tabular pigment becomes about several μm, the number of layers of the oriented tabular pigment in the coating layer decreases, and the effect of improving the moisture-proof performance decreases.
[0016]
Examples of the synthetic resin used in the synthetic resin emulsion of the present invention include a styrene-butadiene copolymer, an acryl-styrene copolymer, a methacrylate-butadiene copolymer, an acrylonitrile-butadiene copolymer, and an acrylic copolymer. Examples include a polymer, a polyester-based copolymer, and a polyurethane-based copolymer. Among these, a styrene-butadiene copolymer is preferred.
[0017]
Styrene-butadiene copolymer (SBR) is composed of an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, chlorostyrene, butadiene, 1,3-butadiene, isoprene, And a conjugated diene compound such as 1,3-dimethyl-1,3-butadiene and 1,3-pentadiene, and a copolymer latex obtained by emulsion polymerization of a monomer composed of another compound copolymerizable therewith.
Styrene is preferred as the aromatic vinyl compound, and 1,3-butadiene is preferred as the conjugated diene compound.
The glass transition temperature (Tg), particle size, gel fraction (weight of the insoluble portion when tetrahydrofuran is used as a solvent), molecular weight, and the like of the synthetic resin are not particularly limited, but generally Tg is -10 ° C to 40 ° C. C., more preferably -5.degree. C. to 35.degree. C., a particle size of 50 to 500 nm, and a gel fraction of 10 to 90%, and particularly preferably 90% or more in order to improve disintegration.
The blending ratio (solid content weight) of the “plate-like pigment: synthetic resin” used in the present invention is 30:70 to 70:30, preferably 35:65 to 60:40.
When the content of the tabular pigment is less than 30%, sufficient disintegration cannot be obtained because a large amount of synthetic resin is present. When the amount of the tabular pigment exceeds 70%, the state of the coating film deteriorates, and sufficient moisture-proof properties cannot be obtained.
[0018]
In order to enhance the moisture-proof effect of the moisture-proof paint in the present invention, it is preferable to use a coupling agent.
Examples of such a coupling agent include a silane coupling agent containing Si in the hydrophilic group, a titanate coupling agent containing Ti in the hydrophilic group, and an aluminum coupling agent containing Al in the hydrophilic group.
Examples of such a coupling agent include γ-glycidoxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, and isopropyl tri (N-aminoethylaminoethyl) titanate.
[0019]
The structure of the coupling agent is roughly classified into a hydrophilic group that interacts with an inorganic compound such as a plate-like pigment such as a phyllosilicate compound, and a hydrophobic group that interacts with an organic compound such as a resin. The portion is obtained by hydrolyzing a metal element such as Ti or Al or an alkoxy group bonded to Si.
On the other hand, as for the hydrophobic group portion of the coupling agent, when the hydrophobic group portion is an organic oligomer, a high molecular organic film is formed on the surface of the inorganic compound, and the surface is completely hydrophobized to enhance the adhesion with the resin matrix. effective. When the hydrophobic group has a reactive organic functional group such as an epoxy group, a vinyl group, or an amino group, the functional group and the reactive functional group of the resin matrix are cross-linked to further improve the adhesiveness with the resin matrix. Increase.
[0020]
With such a coupling agent, the tabular pigment is used after being surface-treated by an integral blending method, a pretreatment method, or the like.
The integral blending method is a method in which a coupling agent is directly added to a paint containing a tabular pigment and a synthetic resin latex.
Further, the pretreatment method is a method in which a tabular pigment is previously treated with a coupling agent. The amount of the coupling agent to be added is 0.1 to 5 parts by mass, preferably 0.5 to 2 parts by mass, per 100 parts by mass of the tabular pigment. When the addition amount is less than 0.1 part by mass, the surface of the tabular pigment is not sufficiently coated with the coupling agent, which is not preferable. When the addition amount is more than 5 parts by mass, the effect of the coupling agent reaches a peak and is uneconomical. It is.
[0021]
As the dye or pigment used in the present invention, those approved to be added to food additives or food packaging materials are preferably used. Further, the dye and / or pigment contained in the coating layer is more preferably 0.5 to 10% in solid content ratio.
[0022]
It is more desirable that the colored moisture-proof layer of the present invention contains a particulate pigment having an aspect ratio of 3 or less and an average particle size of 5 to 15 μm.
The granular pigment having an aspect ratio of 3 or less used in the present invention is roughened by exposing the pigment to the surface of the coating layer by blending it into a moisture-proof coating, and reduces the contact area between the surface of the coating layer and the surface of the calender roll. To prevent adhesion of the moisture-proof paint to the surface of the calender during on-machine application.
Further, the range of the aspect ratio of the granular pigment is more preferably from 3 to 1, more preferably from 2 to 1, as close to 1 as possible. If the aspect ratio exceeds 3, the pigment may not be exposed on the coating surface of the moisture-proof layer, and there may be a problem that the effect of preventing adhesion of the moisture-proof layer cannot be obtained.
[0023]
The average particle diameter of the particulate pigment is desirably in the range of 5 to 15 μm. When the average particle size is less than 5 μm, the granular pigment is not sufficiently exposed on the coated surface and the contact area between the coated surface and the machine calender becomes large, so that it is difficult to obtain an anti-adhesion effect.
If it exceeds 15 μm, the surface properties of the coated surface of the moisture-proof layer may be deteriorated, and the moisture-proof property may be reduced.
[0024]
Further, it is desirable that the particulate pigment is blended in an amount of 3 to 15% by mass with respect to the total solid content in the paint. If the amount is less than 3% by mass, the amount of the particulate pigment is too small, so that the effect of preventing adhesion in a machine calendar may not be sufficiently obtained. If the content exceeds 15% by mass, the surface properties of the coating layer of the moisture-proof layer may deteriorate, and the moisture-proof property may decrease.
In addition, since the granular pigment protects the coated surface from the heat and pressure of the machine calendar, it is desirable that the granular pigment itself has heat resistance.
Specifically, as such a granular pigment, calcium carbonate, heavy calcium carbonate, silica, clay and the like can be used. Particularly, heavy calcium carbonate is preferably used.
[0025]
In addition, the average particle diameter in the present invention is measured by a laser diffraction method. The aspect ratio is a value obtained by dividing the average particle diameter by the average thickness of the plate-like particles. The particle size can be measured by a laser diffraction method using a “laser diffraction type particle size distribution analyzer SALD2000J” manufactured by Shimadzu Corporation.
[0026]
The above materials are mixed to form a colored moisture-proof paint. At this time, if necessary, a dispersant such as polycarboxylic acid, an antifoaming agent, and a surfactant can be added.
[0027]
The colored moisture-proof paint thus prepared can be applied by an on-machine coating facility. That is, a coating facility is provided between a dryer part and a calendar part of a paper machine for producing liner base paper, and a moisture-proof paint is applied by the coating facility.
The coating equipment that can be used in the present invention is not particularly limited, and known coating equipment can be arbitrarily employed.Blade coaters, bar coaters, air knife coaters, and the like, a coating method for scraping a coating surface is a flat pigment. Is more preferable since the orientation tends to be promoted.
The coating amount for this moisture-proof coating of the liner, as solid per side content, 5~35g / ^{m 2,} more preferably from 7~30g / ^{m 2.}
The moisture-proof liner thus coated with the moisture-proof paint of the present invention on-machine and dried at 110 to 150 ° C. for 30 seconds to 120 seconds normally passes through a machine calendar (usually at a linear pressure of about 10 to 30 kg / cm). It can be operated normally as it does not cause adhesion problems due to paint.
[0028]
As the liner base paper used in the present invention, a commonly used liner base paper can be used arbitrarily.However, in order to impart more water resistance, the paper is mixed with a waterproofing agent, or dried in a paper machine. It is also possible to use a water-resistant liner base paper obtained beforehand by impregnating with a water-proofing agent.
The moisture permeability of the moisture-proof liner of the present invention is measured by JISZ0208 cup method (B method) 10~500g ^/ m 2 · 24hr, further preferably 15~350g ^/ m 2 · 24hr.
[0029]
A colored moisture-proof corrugated cardboard sheet is prepared using the colored moisture-proof liner obtained as described above.
To manufacture a corrugated cardboard sheet, it is necessary to bond a liner base paper and a core base paper, and the bonding is performed by a corrugated sheet manufacturing apparatus called a corrugator.
The corrugator mainly includes an SF section for bonding the liner base paper and the core base paper, and a DF section for further bonding the liner base paper to the center side of the single-cardboard sheet bonded in the SF section. At the time of lamination in a corrugator, the corrugated cardboard sheet is heated at a temperature of 150 to 200 ° C. at a press roll part of the SF part, at a linear pressure of 20 to 40 kg / cm, for a pressurization time of 0.01 to 0.20 second, at a temperature of 150 at a hot plate part of the DF part. to 200 DEG ° C., although stuck on the condition that a linear pressure 0.3 kg / cm ^2, moisture-proof liner base paper of the present invention, since the particulate pigment in the coating layer surface is roughened to expose the press corrugator Since the contact area of the coated surface with the roll and hot platen is small and it has heat resistance, there is no fusing trouble of the coated surface to the press roll or hot platen, and it can be manufactured exactly like normal liner base paper. it can.
When producing a colored moisture-proof corrugated cardboard sheet, a colored moisture-proof liner provided with a colored moisture-proof layer on one side is used, and a core base paper is adhered to the non-coated side of the paint by a corrugator.
The colored moisture-proof liner can be used as a liner on both the SF side and the DF side of the corrugated cardboard sheet. It is also possible to use one of the liners and use a general liner for the other.
[0030]
The colored moisture-proof corrugated cardboard sheet thus obtained can be printed, punched and glued with a flexo folder gluer (FFG) to produce a colored moisture-proof cardboard box.
In the present invention, it is more desirable to use a colored corrugated cardboard sheet having a colored moisture-proof layer only on one side surface, and to make the box such that the colored moisture-proof layer faces the inner side of the box.
[0031]
【Example】
The present invention is described in more detail by the following examples.
<Example 1>
100 parts by mass of SBR latex (HOJ4027, solid content 48%: manufactured by Nippon Zeon), 50 parts by mass of muscovite (mica A21, average particle size 22 μm, aspect ratio 20-30: manufactured by Mica Yamaguchi MFG), aminosilane coupling agent (KBM603, 98% or more of active ingredient: manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 parts by mass, heavy calcium carbonate (BF300, average particle diameter 8 μm, aspect ratio 1-2: manufactured by Bihoku Powder Chemical Industry) 5 parts by mass, coloring pigment (SA blue-purple # 800: manufactured by Okuni Pigment Co.) A coating material was prepared with a blending amount of 5 parts by mass.
Next, a 220 g / m ² liner base paper (NRK220: manufactured by Oji Paper Co., Ltd.) was used as a base material, and the paint was applied to the surface of the base material so that the coating amount after drying with a Mayer bar was 8 g / m ^2. Thus, a colored moisture-proof liner of the present invention was obtained.
The colored moisture-proof liner obtained as described above, the core base paper (S160, 160 g / m ² ), and the corrugated cardboard liner base paper (ONRK220, 220 g / m ² ) are stuck together by a conventional method using a corrugator, A colored moisture-proof cardboard sheet having a colored moisture-proof layer on one surface was obtained. The colored moisture-proof layer was blue-violet.
Further, the colored moisture-proof cardboard sheet was prepared as an A-type box with a box-making machine so that the colored moisture-proof layer was on the inside to obtain a colored moisture-proof cardboard box. The present colored moisture-proof cardboard box is suitable for packaging eggplants and the like.
[0032]
<Example 2>
A colored moisture-proof liner and a colored moisture-proof cardboard box were obtained in exactly the same manner as in Example 1 except that SA Black DY-6 (manufactured by Mikuni Pigment) was used as the coloring pigment. The colored moisture-proof layer was black. The present colored moisture-proof cardboard box is suitable for packaging eggplants and the like.
[0033]
<Example 3>
A colored moisture-proof liner and a colored moisture-proof cardboard box were obtained in exactly the same manner as in Example 1 except that GP White # 101 Conch (manufactured by Mikuni Pigment) was used as the coloring pigment. The colored moisture-proof layer was white. In addition, the present colored moisture-proof cardboard box is suitable for packaging of persimmon, flowers and the like.
[0034]
<Example 4>
A colored moisture-proof liner and a colored moisture-proof cardboard box were obtained in exactly the same manner as in Example 1, except that SA Blue DY-12 (manufactured by Mikuni Pigment) was used as the coloring pigment. The colored moisture-proof layer was blue. The colored moisture-proof cardboard box is suitable for packaging eggplants and the like.
【The invention's effect】
According to the present invention, it has become possible to provide a colored moisture-proof cardboard box capable of giving a color that enhances contents such as fruits and vegetables to the inside of the box without using an extra packaging material.

Claims (4)

In a moisture-proof corrugated cardboard box having a moisture-proof coating layer in which a synthetic resin emulsion and an aspect ratio of 5 or more are coated on the inner surface or outer surface of the box with a flat pigment having a major component, the dye in the moisture-proof coating layer Alternatively, a colored moisture-proof cardboard box containing a colored pigment. The colored moisture-proof cardboard box according to claim 1, wherein the solid content ratio of the dye and / or the color pigment in the moisture-proof coating layer is 0.5 to 10%. 3. The colored moisture-proof cardboard box according to claim 1, wherein the moisture-proof coating layer contains a particulate pigment having an aspect ratio of 3 or less and an average particle diameter of 5 to 15 [mu] m. A package in which fruits and vegetables are packaged in the colored moisture-proof cardboard box according to claim 1.