JPH1112994A - White paperboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a white paperboard capable of surely dissolving a printing trouble by 'back fuzz', and useful for wrapping such as a box for a cleaner, box for a medicine, etc., by forming the white paperboard comprising a surface layer, a medium layer and a back layer, and further providing a pigment coating layer on the surface of the surface layer. SOLUTION: This white paperboard comprising of three or more layers of a surface layer, a medium layer and a back layer, and further having a pigment coating layer such as clay has the back layer consisting essentially of an old paper hardly causing removal of ink, and formed out of a disaggregated pulp having 100-300 ml freeness. The disaggregated pulp of the back layer contains <=10/(100 g dried pulp) number of fasciated fibers, and <=10 number of ash contents having >=0.0025 mm<2> , per area of 1.8 mm×2.38 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to white paperboard used for packaging boxes and the like.

[0002]

2. Description of the Related Art White paperboard is widely used as a packaging box for articles such as a detergent box, a tissue paper box, a photographic film box, and a commercially available medicine box. It is also used for applications other than packaging, such as book covers and picture books.

[0003] White paperboard is generally composed of at least three layers of a surface layer, a middle layer and a back layer. For the middle layer, non-deinked waste paper pulp is used. Used. The back layer differs depending on the application. When whiteness is required on both surfaces, the back layer is made the same as the surface layer. When whiteness is not required, waste paper pulp having low whiteness is used.
In order to conceal the color of the middle layer, the surface layer needs to have a concealing property and needs a certain thickness. However, there is a problem in terms of cost if concealing properties are required only for the surface layer. Therefore, a lower surface layer having a certain degree of whiteness is often provided between the middle layer and the surface layer. When a more beautiful appearance is required, a paint using a pigment having high whiteness is applied to the surface of the surface layer, similarly to a general coated paper for printing.

[0004]

The white paperboard is stored and transported by winding or sheet-fed until it is applied to a printing machine after papermaking and coating, but the coated surface of the surface layer and the backing layer are under load. The surface of the back layer may be partially transferred to the surface coated surface when the film is peeled off. This phenomenon is called “back fluff”. When the "backside fluff" occurs,
A problem occurs in that printing is impaired by impurities adhering to the surface during printing. SUMMARY OF THE INVENTION It is an object of the present invention to eliminate a printing trouble caused by "back fringing".

[0005]

In order to solve the above problems, the present invention employs the following constitution. That is, the first invention of the present invention consists of three or more layers of a surface layer, a middle layer, and a back layer, and in a white paperboard having a pigment-coated layer on the surface layer, mainly used paper whose back layer is not deinked. The present invention relates to a white paperboard, wherein the freeness of the disintegrated pulp of the back layer is 100 to 300 ml.

The second invention of the present invention relates to the white paperboard according to the first invention, wherein the number of binding fibers in the disintegrated pulp of the back layer is 10 / (100 g dry pulp) or less. . Still further, the third invention of the present invention is the method of the present invention, wherein the number of ash particles having a particle diameter of 0.0025 mm ² or more present in the disintegrated pulp of the back layer is 10 mm per area of 1.8 mm × 2.38 mm.
The present invention relates to a white paperboard according to the first invention or the second invention, which is not more than one piece.

[0007] According to the study of the present inventors, the back fluff is generated depending on the kind and lot of used waste paper of the back layer.
As means for solving the back fluff, a method by changing the physical properties of a binder of a paint applied to the surface layer, addition of an additive, and the like, and a method by studying a coating substance on the back surface can be considered. However, the back fluff is essentially due to variations in the quality of the raw material, and it is desirable to take fundamental measures on the raw material. The present inventors have studied from such a viewpoint, and as a result, the freeness of the used paper pulp disintegrated by peeling the back layer, the number of binding fibers, the number of large ash particles having a particle size of a certain particle size or more are large. It was discovered that this was a factor and arrived at the present invention.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The white paperboard to be used in the present invention comprises at least three layers: a surface layer, a middle layer, and a back layer. In many cases, a lower layer is provided between the surface layer and the middle layer. The lower layer pulp is a layer whose whiteness is lower than that of the surface layer and whose main purpose is to mask the coloring of the middle layer. Each layer may be two or more layers, and a total of 5 to 9
The most common case is layer making.

[0009] The surface layer is the outermost layer, and uses pulp having high whiteness to completely hide the coloring inside. The pulp used for the surface layer is bleached pulp, and may be any of hardwood and softwood, and may be any of chemical pulp and mechanical pulp. Also, deinked waste paper pulp can be used, and these may be mixed and blended.

The present invention is directed to a white paperboard provided with a pigmented layer on the surface of a surface layer. The pigment coating is performed with the same paint as that used for general printing coated paper. The paint is composed of clay, pigment such as calcium carbonate, binder such as SBR latex, starch, polyvinyl alcohol and the like.

For the middle layer, used newspaper, old magazine paper, old used paper, etc. are used without deinking. The back layer is generally similar to the middle layer. In special cases, a pulp similar to the surface layer may be used for the back layer to provide cosmetics on both sides. However, the back layer defined in the present invention refers to the outermost layer on the side opposite to the surface coated surface. The present invention is directed to a case where waste paper pulp which is not deinked is mainly used for the back layer, and specifically, waste paper pulp which is not deinked by 50% by weight or more of the entire pulp of the back layer. In the present invention, "freeness of the disintegrated pulp of the back layer", "number of binding fibers in the disintegrated pulp of the back layer",
“The number of ash particles having a particle size of 0.0025 mm ² or more in the disintegrated pulp of the back layer” refers to the freeness, the number of binding fibers, and the number of ash components of the used paper pulp that has been separated and re-disintegrated by peeling the back layer of the paperboard. .

The "freeness" of the present invention refers to the freeness according to JIS P 8121 "Canadian Standard Freeness Test Method". In the present invention, it is necessary that the freeness of the disintegrated pulp used for the back layer is in the range of 100 to 300 ml. If the freeness is less than 100 ml, the strength of the back layer surface decreases, and if it exceeds 300 ml, the number of binding fibers and ash taken on the surface coating surface increases due to an increase in binding fibers on the back layer surface and undispersed ash. I do. In the present invention, the freeness of the disintegrated pulp used for the back layer is 100 to 300 m.
As a method for setting the range of l, a method of removing fine fibers and ash using a cleaner, washer, filter, separator, etc., a refiner, a disperser,
Examples of the method include a method of subdividing binding fibers and ash using a kneader or the like.

In the present invention, in order to further prevent back fluffing, the number of binding fibers in the disintegrated pulp used for the back layer is desirably 10 / (100 g dry pulp) or less. As a method of adjusting the number of the binding fibers in the disintegrated pulp used for the back layer to 10 or less / (100 g dry pulp), a method of removing the binding fibers by a screen,
Examples of the method include a method of subdividing the bundled fibers using a refiner, a disperser, a kneader, or the like. The measuring method of the binding fiber is based on the method described in Examples.

In the present invention, in order to further prevent the back fluffing, the particle size of the backing pulverized pulp present in the pulped pulp may be reduced to 0.1.
The number of ash components of 0025 mm ² or more is 1.8 mm × 2.
It is desirable that the number is 10 or less per area of 38 mm. 0.0025mm particle size in the disintegrated pulp used for the back layer
^As a method of controlling the ash content of ² or more to 10 or less per 1.8 mm × 2.38 mm area, a chemical ash dispersion method using a disaggregation accelerator such as caustic soda and a surfactant,
A mechanical ash dispersion method using a refiner, a disperser, a kneader, or the like can be given. Ash content is measured by the method described in the examples.

[0015]

The present invention will be described in more detail with reference to the following examples. The measuring method is as follows. <Production method of waste paper pulp in which the back layer of the white paperboard was peeled off and redissolved> After the white paperboard was sufficiently immersed in water at a temperature of 20 to 80 ° C., only the back layer was peeled off and redissolved. As the disintegration method, a standard disintegrator specified in JIS P8209 "Method for preparing handsheet paper for pulp test" was used. <Freeness Measuring Method> The freeness of the used paper pulp obtained by peeling the back layer of the white paperboard and re-disintegrating was measured. Measurement method is JI
The SP 8121 "Canadian Standard Freeness Test Method" was used. <Measurement method of binding fiber> A slurry of used paper pulp (absolute dry weight: 100 g), which is obtained by peeling the back layer of white paperboard and re-disintegrating, is 6c.
ut flat screen. The residue remaining on this screen was taken on filter paper, and the GP reaction solution was removed to count the number of tie fibers that turned reddish purple. <Method of measuring area of ash having large particle size> An electron micrograph of waste paper pulp obtained by peeling the back layer of white paperboard and re-disintegrating was taken, and a particle size of 0.8 mm x 2.38 mm in an area of 1.8 mm x 2.38 mm was obtained.
The number of ash components of 0025 mm ² or more was counted.

<Examples 1 to 5, Comparative Examples 1 and 2> Waste paper in a ratio of newspaper / weekly magazine = 2/1 was used as a backing layer material.
The ash content after disintegrating the used paper and passing through ordinary cleaning and screening steps was 15 to 25%. The slurry is processed by changing the processing conditions such as a screen, a refiner, a disperser, and a kneader, and the back layer of white paperboard having a total rice area of 230 to 500 g / m ² (rice area of 40 g / m ² )
m ² ). The raw material for this backing layer was treated so that the freeness, binding fibers, and ash content of the used paper pulp obtained by peeling the backing layer of the manufactured white paperboard and re-disintegrating were as shown in Table 1. (Bundling fiber and ash are the average values measured 10 times each.) On the surface layer, a pigment coating layer was formed by a paint having the following formulation.
9.5 g / m ^{2 was} provided.

<Coating of paint> Top coat: kaolin (Ultra White 90) / calcium carbonate (Brilliant 15) / titanium oxide (TCA33)
3) = 50/35/15 (parts) and latex 22
Parts, starch 6 parts. Undercoat: kaolin (Ixylon) / tansan calcium (ace 25) / calcium carbonate (TI121S) = 2
0/60/20 (parts), 14 parts of latex, 4 parts of starch.

The back fluff of each white paperboard was evaluated as follows. Table 1 shows the results. <Method for evaluating back fluff> RI method: The back surface of white paperboard is printed by an RI printing machine (30 rotations), the number of fibers taken on a rubber roll is copied on a transfer paper, and the number is measured. Hot pressing method: The front and back sides of white paperboard are overlapped,
After controlling the humidity in an environment of 60 ° C and 85%, 70 ° C by hot press,
Pressurization (30 kg / cm ² ) is performed for 20 minutes. Peel it off,
At that time, the number of fine fibers, the number of binding fibers, the number of coat lees, the number of clumps of pigment, and the like of the back layer taken on the coating surface are measured by an image analyzer.

[0019]

[Table 1]

[0020]

According to the present invention, there is no need to change the pigment coating layer, the coating material on the back surface, and the like, and the back fluff can be reliably prevented.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Kirita 2-3-2 Higashishinozaki, Edogawa-ku, Tokyo Oji Paper Co., Ltd. Edogawa Mill

Claims (3)

[Claims] A white paperboard comprising three or more layers of a surface layer, a middle layer, and a back layer, and having a pigment coating layer on a surface of the surface paper.
A white paperboard, wherein the back layer is a layer mainly composed of waste paper which is not deinked, and the freeness of the disintegrated pulp of the back layer is 100 to 300 ml. 2. The number of binding fibers in the disintegrated pulp of the backing layer is 10.
The white paperboard according to claim 1, which is not more than individual pieces / (100 g dry pulp). 3. A particle size of 0.0 present in the disintegrated pulp of the back layer.
The number of ash components of 025 mm ² or more is 1.8 mm × 2.3
The white paperboard according to claim 1 or 2, wherein the number of the white paperboard is 10 or less per 8 mm area.