JP2013129948A - Colored paper board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a colored paper board which has superior water resistance and reduces color fading when gets wet with water.SOLUTION: The colored paper board has two layers or more of paper layers and has a first paper layer located on a surface, which contains dye, water resistant additives and water-repellent agents internally added thereto. It is preferable that the first paper layer further contains fixing agents internally added thereto. It is preferable that coating liquid containing water-repellent agents is applied on a surface of the first paper layer. It is preferable that the water resistant additive is polyamide-epichlorohydrin resin.

Description

  The present invention relates to colored paperboard.

  Paperboard is a thick paper used for paper containers, packaging materials, building materials, and the like and having a plurality of paper layers. From the viewpoint of fashionability, functionality, sales promotion, and the like, such paperboard is also used which has been visualized by adding a dye to the surface layer and coloring it darkly.

  The dark colored paperboard is suitably used for cosmetic cases and the like used for gifts and simple packaging. This paperboard is required to have water resistance in order to cope with rainy weather during delivery and inadvertent water wetting. In particular, in the case of a dark colored paperboard having a lightness of 60 or less, it is particularly required that the color fading or color transfer is small even when wetted with water in order to maintain visualization. Under such circumstances, for the purpose of merely ensuring water resistance without being restricted by dark colors, a paperboard in which a water repellent is internally added to the surface layer or the like (see JP-A-2005-206957), a specific fixing agent for dyes is used. An internally added paperboard (see Japanese Patent Application Laid-Open No. 2011-21283) has been proposed. By adding the water repellent in this way, the water repellency of the paperboard is increased, and as a result, the water resistance is increased. Further, by adding an appropriate fixing agent to the dye, the fixing property of the dye is enhanced, and the color fading of the colored paper board when wet with water is reduced. However, in the case of a colored paperboard having a lightness of 60 or less, it is not a sufficient measure against discoloration simply by ensuring water resistance.

  Further, from the above prior art, it is considered that by adding a fixing agent and a water repellent together with a dye, it is possible to obtain a colored paperboard having excellent water resistance and little color fading even when wet. However, even when such an additive is internally added, it is insufficient to impart sufficient water repellency to a dark colored paperboard having a lightness of 60 or less, and the color fading cannot be eliminated. And the ability to prevent discoloration is not sufficient.

JP 2005-206957 A JP 2011-21283 A

  The present invention has been made on the basis of the above-described circumstances, and is colored with excellent water resistance and reduced color fading when wet when it is a dark color having a lightness of 60 or less. The purpose is to provide paperboard.

  The present inventor initially assumed that the colorability of the internally added dye was poor as a cause of discoloration when the dark colored paperboard was wet with water. The present inventors have found that the hydrophilicity of the internally added dye inhibits the water repellent function of the water repellent, and that the water-resistant agent can control the hydrophilicity of the dye, leading to the completion of the present invention. It was.

That is, the invention made to solve the above problems is
A colored paperboard comprising two or more paper layers,
The first paper layer (hereinafter also referred to as “surface layer”) located on the surface is internally added with a dye, a water-resistant agent and a water-repellent agent.

  According to the colored paperboard, in addition to the dye and the water repellent agent, the water resistance agent is internally added to the first paper layer. Therefore, the water resistance agent suppresses the hydrophilicity of the dye and functions as a water repellent agent. It can be expressed effectively. Therefore, the colored paperboard is excellent in water repellency on the surface even when the lightness is a dark color having a brightness of 60 or less.

  It is preferable that a fixing agent is further internally added to the first paper layer. In this way, by further adding a fixing agent to the first paper layer, the fixing property of the dye is improved, so that the color fading when wet with water can be further reduced.

  It is preferable that a coating liquid containing a water repellent is applied to the surface of the first paper layer. Thus, by externally adding a water repellent to the surface of the first paper layer, the water repellency of the surface is further increased, so that the water resistance is further increased and the color fading can be further reduced.

  The water-proofing agent may contain a polyamide / epichlorohydrin resin. Thus, by using a polyamide / epichlorohydrin resin as a water-proofing agent, the hydrophilicity of the dye is appropriately controlled, and the above-described action can be exhibited more effectively.

  It is preferable that the content ratio (solid content ratio) of the dye and the water-resistant agent in the first paper layer is 1: 1 or more and 3: 1 or less. Thus, by making the content ratio of the dye and the water-proofing agent in the first paper layer within the above range, the water-proofing agent can moderately control the hydrophilicity of the dye, and the above action is more effective. Can be demonstrated.

  As described above, according to the colored paperboard of the present invention, it is excellent in water resistance, and color fading when wet with water is reduced. Therefore, the colored paperboard is required to be visualized, and can be suitably used for a liner or a packaging bag that is colored darkly.

  Hereinafter, embodiments of the colored paperboard of the present invention will be described in detail.

  The colored paperboard of the present invention comprises two or more paper layers. The number of paper layers is not particularly limited as long as it is 2 or more, but is preferably 3 or more, more preferably 4 or more and 6 or less, and even more preferably 5 layers. With such a multilayer structure, the type and amount of pulp and additive for each layer can be adjusted, and the functionality of the paperboard can be enhanced, and each layer has a unique solution for solving problems. Thus, a synergistic effect due to the characteristics of each layer can be obtained as compared with a single layer. In addition, when the number of layers exceeds six layers, the cost may increase.

(First paper layer)
The 1st paper layer located in the surface has pulp fiber as a main component, and dye, a water-proofing agent, and a water repellent are added internally. According to the colored paperboard, in addition to the dye and the water repellent agent, the water resistance agent is internally added to the first paper layer. Therefore, the water resistance agent suppresses the hydrophilicity of the dye and functions as a water repellent agent. It can be expressed effectively. Therefore, since the colored paperboard is excellent in water repellency on the surface, it is excellent in water resistance, and color fading when wet with water is reduced.

(Pulp fiber)
The pulp fiber as the main component of the surface layer is not particularly limited. For example, waste paper pulp (DIP), chemical pulp (for example, hardwood kraft pulp: LBKP, softwood kraft pulp: NBKP, etc.), mechanical pulp (for example, thermomechanical pulp: TMP) And pulp fibers obtained from non-wood pulp such as kenaf, bagasse, hemp, cotton, and the like), pressured kraft pulp: PGW, refiner ground pulp: RGP, ground pulp and the like. Among these, pulp fibers derived from waste paper pulp are preferable. Waste paper pulp contains a large amount of ash and has a relatively low freeness, so that water is less likely to permeate and has an effect of improving water resistance. Furthermore, it is preferable to use upper white waste paper pulp as the pulp fiber used for the surface layer. In addition, by using white waste paper pulp, colors such as dyes can be faithfully reproduced.

(dye)
It does not specifically limit as said dye, Well-known dyes, such as an anionic direct dye, a cationic direct dye, a basic dye, an acidic dye, can be employ | adopted according to the objective.

  The anionic direct dye is generally an azo dye having an azo group (—N═N—) as a chromophore, and other examples include stilbene, thiazole, dioxazine, and phthalocyanine. The cationic direct dye is one in which the end of the chromophore is a cationic group, and has, for example, a sulfone group, a phenolic hydroxyl group, a carboxyl group, etc. in the molecule, such as sodium salt, potassium salt, ammonium salt, etc. It is a dye having a molecular structure.

  Among these dyes, when a cationic direct dye is used, the fixing property to the pulp fiber is improved by itself during the production process, and the fading property of the obtained colored paperboard is improved. On the other hand, in the case of an anionic direct dye, since the fixability of the dye itself is not sufficient, the effect of adding the water-resistant agent of the present invention can be enjoyed more.

  The content of the dye in the surface layer is not particularly limited, but in order to perform sufficient color development, the amount added to the raw pulp slurry is preferably 10 kg or more and 30 kg or less with respect to 1 t of pulp fibers. When the addition amount is less than the lower limit, it may not be possible to obtain a darkly colored paperboard. If the dye content exceeds the above upper limit, the amount of dye that is not fixed increases and color fading is likely to occur.

(Waterproofing agent)
The water-resistant agent is not particularly limited, and is polyamide / epichlorohydrin resin, polyamide / polyamine resin, polyamide / epoxy resin, urea-formaldehyde resin, melamine-formaldehyde resin, polyamide polyurea-formaldehyde resin, glyoxal. And cyclic urea-glyoxal reactants, acrylamide-reactant copolymers, epoxy compounds such as glycerin diglycidyl ether, and polyvalent metal compounds such as zirconium compounds.

  Examples of commercially available water-resistant agents include WS4024 (manufactured by Seiko PMC), HR-SA-30 (manufactured by Hornen), SP resin (manufactured by Sugawara Shoji), S16460 (manufactured by Seiko PMC), and the like.

  Among these, a resin-based water-proofing agent is preferable, a polyamide-based water-proofing agent is more preferable, and a polyamide-epichlorohydrin resin is more preferable. By using such a water-resistant agent, the hydrophilicity of the dye is appropriately controlled, and the above action can be exhibited more effectively.

  The content of the water-proofing agent in the surface layer is not particularly limited, but the amount added to the raw pulp slurry is preferably 1 kg or more and 100 kg or less, more preferably 2 kg or more and 30 kg or less with respect to 1 t of the pulp fibers. When the content of the water-resistant agent is less than the above lower limit, the function of the water-resistant agent may not be sufficiently exhibited. On the other hand, when the content of the water-resistant agent exceeds the above upper limit, the paper may turn yellow or the paper machine or the leveling equipment may become dirty.

  The content ratio of the dye and the water-proofing agent in the first paper layer (addition ratio to pulp slurry: solid content ratio) is preferably 1: 1 or more and 3: 1 or less. Thus, by making the content ratio of the dye and the water-proofing agent in the first paper layer within the above range, the water-proofing agent can moderately control the hydrophilicity of the dye, and the above action is more effective. Can be demonstrated.

(Water repellent)
The water repellent is not particularly limited, and waxes such as paraffin wax and natural wax; synthetic resins such as polyamide resin and polyamine resin; fluororesins such as polytetrafluoroethylene and polychlorotrifluoroethylene; polymethyl Mention may be made of silicone resins such as hydrogen siloxane and polydimethylsiloxane. Among these, when used together with a water-resistant agent, wax is preferable from the viewpoint of effectively exhibiting a function of suppressing water repellency and suppressing elution of a dye.

  The content of the water repellent in the surface layer is not particularly limited, but the amount added to the raw pulp slurry is preferably 2 kg or more and 100 kg or less, more preferably 5 kg or more and 20 kg or less with respect to 1 t of the pulp fibers. When the content of the water repellent is less than the above lower limit, the function of the water repellent may not be sufficiently exhibited. On the other hand, when the content of the water repellent exceeds the above upper limit, the paper may be yellowed or the printability may be lowered.

(Fixing agent)
It is preferable that a fixing agent is further internally added to the first paper layer. In this way, by further adding a fixing agent to the first paper layer, the fixing property of the dye is improved, so that the color fading when wet with water can be further reduced.

The fixing agent is not particularly limited, but 1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, and 2) acrylic polymers having secondary or tertiary amino groups or quaternary ammonium groups. 3) Polyvinylamine, polyvinylamidine, 5-membered ring amidines, 4) Dicyan-based cationic resins such as dicyandiamide-formalin copolymer, 5) Polyamine-based cationic resins such as dicyandiamide-polyethyleneamine copolymer, 6) Dimethylamine - epichlorohydrin copolymer, 7) diallyldimethylammonium -SO ₂ copolymer, 8) diallylamine salt -SO ₂ copolymer, 9) dimethyldiallylammonium chloride polymer, 10) polymers of allylamine salts, 11) dialkylamino ethyl( T) Acrylate quaternary salt copolymer, 12) Acrylamide-diallylamine salt copolymer, 13) Aluminum salt such as polyaluminum chloride and polyaluminum acetate, 14) Polyhydric phenol-formalin polycondensate derivative, 15) Carboxylic acid One or more amide condensate quaternary ammonium compounds can be used.

  Among these, the polyphenol-formalin polycondensate derivative and the carboxylic acid amide condensate quaternary ammonium compound are also preferable in combination with a water-resistant agent because of good color development and fixing properties of the dye.

  The content of the fixing agent in the surface layer is not particularly limited, but the addition amount to the raw pulp slurry is preferably 3 kg or more and 40 kg or less with respect to 1 t of the pulp fibers. When the content of the fixing agent is less than the lower limit, the function of the fixing agent may not be sufficiently exhibited. On the other hand, when the content of the fixing agent exceeds the above upper limit, the paper may be yellowed or the printability may be lowered.

  The first paper layer may further contain other additives. Examples of other additives include a sulfuric acid band, an internal sizing agent, a paper strength agent, and a pigment.

  Examples of the internal sizing agent include rosin sizing agents and synthetic polymer sizing agents.

  Examples of the paper strength agent include starch such as starch, oxidized starch, and carboxymethylated starch; plant gum; polyvinyl alcohol; carboxymethylcellulose and the like.

  Examples of the pigment include inorganic pigments and organic pigments.

(Other paper layers)
Other paper layers other than the surface layer also contain pulp fibers as a main component, similarly to the surface layer. The pulp fiber which is the main component of the other paper layer is not particularly limited, and each of the pulps described above can be used. Among these, waste paper pulp is preferable, and soot waste paper pulp is more preferable. Such a pulp contains a large amount of ash and has a relatively low freeness, so that it is difficult for water to permeate and has an effect of improving water resistance.

  The paper layer other than the surface layer can also contain various additives similar to the surface layer.

  In the paper layer other than the surface layer, particularly in the second paper layer adjacent to the surface layer, the content of the sizing agent is preferably smaller than the content (addition amount) in the surface layer. In this case, even when water permeates into the surface layer, the water easily moves to another paper layer such as the second paper layer. Therefore, according to such a colored paperboard, the surface layer hardly contains moisture, and color fading when wetted with water can be further reduced.

(Coating)
The colored paper board is preferably coated with a coating liquid containing a water repellent on the surface of the first paper layer. Thus, by externally adding a water repellent to the surface of the first paper layer, the water repellency of the surface is further increased, so that the water resistance is further increased and the color fading can be further reduced.

  The water repellent contained in the coating liquid is not particularly limited, and examples thereof include wax-based, synthetic resin-based, acrylic-based, paraffin-based, fluorine-based, and silicone-based. Can be used. In addition, the water repellent may be used alone or in combination with other coating chemicals. Commercially available water repellents include the product name “WR3932” manufactured by Seiko PMC, the product name “Ripax A240” manufactured by Modern Chemical Co., Ltd., and the product names “Palatex NS6” and “Palatex” manufactured by Seiko Chemical Industry Co., Ltd. NS630 "and the like.

  Among the water repellents, wax-based water repellents that have good water dispersibility in the coating solution and are excellent in water repellent effect even when the surface layer contains a dye are preferable. In particular, by adding a wax-based water repellent to the surface layer and coating the surface with a wax-based water repellent, the dye added to the surface layer is effectively protected by the water-repellent agent. As a result, a higher color fading prevention function can be expressed.

The coating amount of the water repellent is not particularly limited, and can be 0.01 to 1.5 g / m ^{2 in} terms of solid content, for example, and preferably 0.02 to 1.0 g / m ² . By setting the coating amount of the water repellent to 0.02 g / m ² or more, more sufficient water repellency can be obtained, and by setting it to 1.0 g / m ² or less, the slip angle caused by the water repellent This is preferable because the decrease in the thickness can be reduced.

  In addition to the water repellent, the coating liquid may contain other additives. Examples of other additives include an anti-slip agent and a surface sizing agent.

(Production method)
Although the manufacturing method of the colored paperboard of this invention is not specifically limited, For example, it can manufacture using a well-known multilayer paper machine by the following processes.
(1) To the slurry obtained by dispersing pulp fibers in water, additives corresponding to each paper layer are added and mixed as necessary to prepare a paper stock for each paper layer.
(2) Each paper stock is made on a wire and combined.
(3) Press with a pressure roll to remove moisture.
(4) Dry with a dryer cylinder, and if necessary, apply a coating solution containing a water repellent with a calendar.
(5) Winding on a reel to obtain colored paperboard.

  In the step (1), at least a dye, a water-proofing agent and a water-repellent agent are used as additives in the slurry for the surface layer, and a fixing agent is preferably used.

  In the step (1), the dye is preferably added before the water-proofing agent and water-repellent agent are added. By doing in this way, after fixing dye to pulp fiber, the hydrophilicity of this dye can be lowered | hung with a water-proofing agent, and the function of a water repellent material can be expressed effectively. In order to exhibit the above action more effectively, it is preferable to add (1) a dye (and a fixing agent if necessary), (2) a sulfuric acid band, (3) a water-resistant agent and a water-repellent agent in this order. . Furthermore, instead of adding the whole amount of dye in (1) above, the majority of the dye is added in (1) above, while (4) finally a small amount of dye is added for color adjustment. It is preferable to add.

(Quality etc.)
The brightness on the surface side of the colored paperboard is preferably 60 or less, and more preferably 55 or less. The colored paperboard can be suitably adapted to recent visualization by making such a dark color. On the other hand, even if it is such a dark color, the color loss is reduced. The lower limit of the brightness is not particularly limited, but is, for example, 30 and 40 is preferable. The lightness is a value measured according to JIS-Z8722.

The colored paperboard preferably has a Cobb water absorption of 50 g / m ² or less, more preferably 40 g / m ² or less, at a contact time of 120 seconds defined by JIS-P8140 on the surface. Suppressing permeation of the water repellent agent into the base paper when the water repellent agent is applied when the Cobb water absorption at a contact time of 120 seconds is 50 g / m ² or less as defined in JIS-P8140 on the surface of the base paper. It is possible to improve the water repellency.

  The paper surface pH of the colored paperboard is preferably 3.5 to 6.0. If the paper surface pH is less than 3.5, the paper strength deteriorates with time. On the other hand, if it exceeds 6.0, the water repellent effect is low, and the water repellent degree deteriorates with time and heat deteriorates. In addition, paper surface pH is the value measured by the coating method (J.TAPPI paper pulp test method No.6-75) of the surface pH test method of paper and paperboard. Although there is no restriction | limiting in particular in the method of making paper surface pH into the said range, For example, it can achieve by making the paper stock used in order to manufacture a base paper contain a sulfuric acid band. The sulfuric acid band means aluminum sulfate, and active aluminum (cationic) is contained in the obtained base paper by containing the sulfuric acid band in the stock. Therefore, when a sulfuric acid band is used, it is preferable to use a water repellent composed of an anionic compound. By using a water repellent composed of an anionic compound, active aluminum contained in the base paper and the water repellent composed of an anionic compound are electrically bonded to each other, and the water repellent is fixed on the surface of the base paper. Water content can be obtained.

In the colored paperboard, it is preferable that the surface layer having a basis weight of between 20 to 35 g / ^{m 2,} more preferably to 20 to 30 g / ^{m 2,} and even more preferably from 20-25 g / ^{m 2.} If the basis weight of the surface layer exceeds 35 g / m ² , a large amount of chemicals and raw materials are used, resulting in an increase in cost. If the basis weight is less than 20 g / m ² , the thickness of the surface layer is difficult to be uniform. As the basis weight of the surface layer is smaller, the color tone of the second paper layer appears on the surface of the paperboard, so that the appearance is lowered. In such a case, the middle layer in contact with the surface layer can be colored in a color close to the surface layer to improve the formation.

The basis weight per layer of the other paper layers is not particularly limited, but is preferably 35 to 100 g / m ² , for example.

The basis weight of the colored paperboard is not particularly limited, preferably to 100 to 400 g / ^{m 2,} and more preferably a 100~340g / ^{m 2.}

  Although it does not restrict | limit especially as thickness of the said colored paperboard, It is preferable to set it as 120-480 micrometers, and it is more preferable to set it as 120-410 micrometers.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. “Kg / t” indicates mass (kg) per 1 t of pulp.

[Example 1]
In the dyeing batch tank having a stirring device,
Raw material pulp (upper white paper: white pulp content 100%)
As the coloring agent, the following dyes (referred to as coloring agent A),
Blue BHL (dye: solid content 65%: manufactured by Toa Kasei Co., Ltd.)
11.22 kg / t (7.29 kg / t in terms of solid content),
Violet R (dye: solid content 64%: manufactured by Toa Kasei Co., Ltd.)
4.84 kg / t (3.07 kg / t in terms of solid content),
Turkis MP (dye: solid content 61%: manufactured by Toa Kasei Co., Ltd.)
6.801 kg / t (4.15 kg / t in terms of solid content),
Violet 3BF (dye: solid content 51%: manufactured by Clariant Japan)
3.286 kg / t (solid content: 1.68) and TOAFix3A (manufactured by Toa Kasei Co., Ltd.) 60 kg / t as a fixing agent, followed by sulfuric acid band 45.5 kg / t,
NES-780H (manufactured by Harima Kasei Co., Ltd.) 53.4 kg / t as an internal sizing agent,
RB-36 (manufactured by Harima Kasei Co., Ltd.) 59.1 kg / t as a paper strength agent
Coated Sizer MN2L (a wax emulsion with a solid content concentration of 50%, manufactured by Daiwa Chemical Co., Ltd.) 27.3 kg / t [13.7 kg / t in terms of solid content] as an internally added water repellent,
WS4024 (polyamide-epichlorohydrin resin with a solid content concentration of 25%, manufactured by Seiko PMC) 40 kg / t [10 kg / t in terms of solid content]
Was added to obtain a raw material pulp slurry for the first paper layer.

  Colorant A is all a dye, and the total amount is 16.19 kg / t in terms of solid content. Moreover, the mass ratio (solid content) of the added dye and the waterproofing agent is 16.19: 10, that is, 1.62: 1.

  The ground paper waste paper pulp was disaggregated to obtain a raw material pulp slurry for the second to fifth paper layers.

The internal additive sizing agent is added to the raw pulp slurry for the second paper layer at 21.0 kg / t,
The raw pulp slurry for the third paper layer is 22.5 kg / t,
The raw pulp slurry for the fourth paper layer is 29.0 kg / t,
The raw pulp slurry for the fifth paper layer is 49.7 kg / t.
Each was added.

In addition, the above water-resistant agent is added to the raw paper slurry for the second paper layer at 27.1 kg / t,
The raw pulp slurry for the third paper layer is 27.1 kg / t,
The raw material pulp slurry for the fourth paper layer is 27.1 kg / t,
The raw pulp slurry for the fifth paper layer is 33.9 kg / t
Each was added.

  The raw pulp slurry for the first to fifth paper layers was supplied to a paper machine to obtain a colored paperboard base paper consisting of five paper layers.

38.9% paraffinic wax (WR3932 manufactured by Seiko PMC, solid content: 10%) as an externally added water repellent agent on the surface of the colored paperboard
Styrenic polymer as an anti-slip agent (AT3802 by Seiko PMC: solid content 25%) 4.3%,
1.6% surface sizing agent (KN-275P, Harima Chemicals)
Wet10g / ^{m 2} a coating solution containing (coating amount of the water repellent (solid content) 0.4 g / ^{m 2)} was coated on the surface, to obtain a colored paperboard of Example 1.

[Examples 2 to 11, Comparative Example 1]
In the same manner as in Example 1 except that the type and amount of water-resistant agent, the type of internally added water repellent, the type of externally added water repellent and the coating amount were as shown in Table 1, Example 2 11 and Comparative Example 1 were obtained.

The chemicals in the table are as follows.
・ Waterproofing agent Polyamide-polyamine resin: Arafix (Arakawa Chemical Industries)
Polyamide / epoxy resin: Sumirez Resin 650 (30) (Taoka Chemical Industries)
-Internally added water repellent styrene / acrylic acid ester copolymer resin: Polysol AM-610 (manufactured by Showa Polymer Co., Ltd.)
-Externally added water repellent olefin resin: Coat Sizer M8-115 (manufactured by Daiwa Chemical Industry Co., Ltd.)

[Example 12]
The colored paperboard of Example 12 was prepared in the same manner as in Example 1 except that the amount of the internal sizing agent added to the raw pulp slurry for the second paper layer was 51.0 kg / t. Obtained.

[Example 13]
Example 13 was carried out in the same manner as Example 1 except that the following Colorant B was used instead of Colorant A, and the carboxylic acid amide condensate quaternary ammonium compound (Cartaletin: manufactured by Clariant Japan) was used as the fixing agent. Colored paperboard was obtained.

Coloring agent B
BNF (dye: solid concentration 77%: manufactured by Clariant Japan)
3.509 kg / t (2.70 kg / t in terms of solid content),
Red 2BP (dye: solid content concentration 78%: manufactured by Toa Kasei Co., Ltd.)
7.726 kg / t (6.03 kg / t in terms of solid content)
Yellow G (dye: solid content concentration 78%: manufactured by Nippon Chemical Industry Co., Ltd.)
14.238 kg / t (11.11 kg / t in terms of solid content),
YT-100 (pigment: solid content concentration 61%: manufactured by Mikuni Color Co., Ltd.)
12.329 kg / t (7.52 kg / t in terms of solid content),
Black RP (dye: solid content concentration 78%: manufactured by Nippon Chemical Industry Co., Ltd.)
1.2kg / t (0.94kg / t in terms of solid content)

  In addition, the total amount of the dye in the colorant B is 20.78 kg / t in terms of solid content. (In Colorant B, YT-100 is a pigment. Further, the mass ratio (solid content) of the added dye to the water-resistant agent is 20.78: 10, that is, 2.08: 1. .

[Evaluation]
Each colored board obtained was evaluated as follows.

[brightness]
The lightness (L) of the surface was measured in accordance with JIS-Z8722.

[Color transfer resistance]
(1) A colored paperboard is sandwiched between the bump size tester (test area: 100 cm ² ) and immersed in 50 ml of water for 15 minutes.
(2) Next, the colored paperboard is sandwiched between the filter papers in a constant temperature test chamber and sandwiched at a constant pressure.
(3) After 2 hours, 12 hours, and 24 hours, the color transfer state is confirmed and evaluated according to the following criteria. The evaluation results are shown in Table 1.
○: No color transfer
Δ: Slight color migration can be confirmed.
X: Color transfer is conspicuous.

  As shown in Table 1, according to the colored paperboard of the present invention, it is understood that the occurrence of color fading (color transfer) when wetted with water is reduced while being colored dark.

  As described above, the colored paperboard of the present invention is suitable for packaging materials, building materials, etc. even if it is a dark color with a lightness of 60 or less, for example, it is difficult to discolor even when wet. it can.

Claims (5)

A colored paperboard comprising two or more paper layers,
A colored paperboard, wherein a dye, a water-resistant agent and a water-repellent agent are internally added to a first paper layer located on the surface.   The colored paperboard according to claim 1, wherein a fixing agent is further internally added to the first paper layer.   The colored paperboard according to claim 1 or 2, wherein a coating liquid containing a water repellent is applied to the surface of the first paper layer.   The colored paperboard according to claim 1, 2 or 3, wherein the water-proofing agent comprises a polyamide / epichlorohydrin resin. The colored paperboard according to any one of claims 1 to 4, wherein a content ratio of the dye and the waterproofing agent in the first paper layer is 1: 1 or more and 3: 1 or less.