JP2014043653A - Colored cardboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a colored cardboard having an excellent water resistance whose color fading when wetted with water is mitigated.SOLUTION: The colored cardboard provided by the present invention includes multiple paper layers, whereas a dye, a pigment, a water resistance enhancer, and a water-repellent agent are internally added to the first paper layer positioned on the surface thereof. It is desirable for the inclusion ratio of the dye and pigment within the first paper layer to be 2 : 1 or above and 4 : 1 or below and for the content, in terms of solid content, of the pigment within a raw pulp ingredient forming the first paper layer with respect to 1 t of the pulp to be 3 kg or above and 9.2 kg or below. Moreover, it is desirable for a fixative to be also added internally to the first paper layer and for the surface of the first paper layer to be coated with a coating solution including a water-repellent agent.

Description

  The present invention relates to colored paperboard.

  Paperboard is a relatively 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, etc., such paperboards are also used which are visualized by adding a dye or pigment to the surface layer to make it dark and visualized.

  The dark-colored paperboard is generally suitably used for a cosmetic case used for gifts or simple packaging. For this reason, this paperboard is required to have water resistance in order to cope with delivery in rainy weather and inadvertent water wetting. Therefore, for the purpose of improving water resistance, a paperboard (see Japanese Patent Application Laid-Open No. 2005-206957) in which a water repellent is internally added to the surface layer or the like 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, in the case of dark paperboard having a lightness of 60 or less, it is further required that there is little color unevenness and little color fading or color transfer even when wetted with water in order to maintain visualization. In view of this, a paperboard (see Japanese Patent Application Laid-Open No. 2011-21283) has been proposed in which a specific fixing agent for a dye is internally added to prevent color fading when wet. Thus, by adding an appropriate fixing agent to the dye, the fixing property of the dye is improved, and the color fading when wetted with water is reduced.

  From the above prior art, it is considered that a colored paperboard having excellent water resistance and little color fading even when wet is obtained by adding a fixing agent and a water repellent together with a dye. However, even when such an additive is added internally, for example, in the case of a dark-colored paperboard having a lightness of 60 or less, it is possible to impart sufficient water repellency and dye fixing property to eliminate color fading. Have difficulty. For this reason, there is still room for improvement in water resistance and color transfer resistance of dark paperboard.

JP 2005-206957 A JP 2011-21283 A

  The present invention has been made on the basis of the circumstances as described above, and is excellent in water resistance, even if it is darkly colored, color unevenness is suppressed, and coloring with reduced color loss such as when it gets wet with water is reduced. The purpose is to provide paperboard.

  As a cause of discoloration when dark paperboard is wet with water, the present inventors have found that the hydrophilicity of the internally added dye hinders the water repellent function of the water repellent, and the water resistance. It has been found that the agent can control the hydrophilicity of the dye. Furthermore, the inventor of the present invention, in terms of the fixability of dyes and pigments added internally, the dye is better than the pigment at the time of papermaking, but the dye is superior to the dye in the case of being wet with water after papermaking. However, it was found that the pigment is superior in fixability, that is, the pigment once swollen into the paper is less likely to spill out, and the present invention has been completed.

That is, the invention made to solve the above problems is
A colored paperboard comprising a plurality of paper layers,
It is characterized in that a dye, pigment, water-proofing agent and water-repellent agent are internally added to the first paper layer located on the surface.

  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 in the case of a dark-colored paperboard having a lightness of 60 or less, for example, so that it is excellent in water resistance and color loss when wet with water is reduced. The The colored paperboard is colored not only with dyes but also with pigments. Since the pigment has better fixability to the pulp after papermaking than the dye, the amount of the dye added can be relatively reduced by using the pigment, and the color loss due to the dye can be reduced. It is not clear why the pigment after papermaking has better fixability to the pulp than the dye, but the pigment that has entered between the pulps during papermaking is probably firmly fixed by the shrinkage of the pulp during drying. Therefore, it is estimated that it will be difficult to spill. As a result, the colored paperboard has less color fading when wetted with water than a colored paperboard colored using only a dye, and the colored paperboard is colored even if it is darkly colored so that the brightness is 60 or less. Unevenness can be suppressed.

  Furthermore, regarding the blending ratio of the dye and the pigment suitable for obtaining a colored paper board with little color unevenness while using the water repellent and the water resistant agent together, the content ratio of the dye and the pigment in the first paper layer is 2: It is preferably 1 or more and 4: 1 or less. Thus, by setting the content ratio of the dye and the pigment in the first paper layer within the above range, the paperboard can be darkly colored without using the dye excessively. As a result, the colored paperboard has a dark color tone, and the color fading when wetted with water is further reduced, and a colored paperboard that does not cause color unevenness while using a water repellent and a water-resistant agent is obtained. Can do.

  The content of the pigment in the raw material pulp forming the first paper layer is preferably 3 kg or more and 9.2 kg or less per 1 t of pulp in terms of solid content. Thus, by making the content of the pigment in the first paper layer within the above range, the coloring effect by the pigment can be effectively obtained with little color unevenness, and the lightness that is difficult to develop with the dye alone is compensated for by the pigment. Can do. Moreover, since the content of the dye can be relatively reduced, the color loss due to the dye can be further reduced.

  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 fixability of the dye and the pigment is increased, so that the color fading when wetted 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 the water repellent to the surface of the first paper layer, the water repellency of the surface is further increased, so that the water resistance of the colored paperboard is further increased and the color fading can be further reduced.

  As described above, according to the colored paperboard of the present invention, it is excellent in water resistance, and color fading when wetted with color unevenness or 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 darkly colored.

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

  The colored paperboard of the present invention has a multilayer structure having a plurality of 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 still 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.

(First paper layer)
The 1st paper layer located in the surface has pulp fiber as a main component, and dye, a pigment, a water-resistant agent, and a water repellent are added internally. According to the colored paperboard, since the water-proofing agent is internally added to the first paper layer, the water-proofing agent suppresses the hydrophilicity of the dye and effectively exhibits the function of the water repellent. it can. 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. In addition, the colored paperboard can be colored deeply without excessive use of a dye due to the internal addition of the pigment. Once the paper is made, the pigment has better fixability to the pulp after paper making than the dye, and therefore can suppress color fading. Therefore, the colored paperboard can effectively reduce color fading when wetted with water, compared to colored paperboard colored using only a dye.

(Pulp fiber)
The pulp fiber that is the main component of the first paper 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, thermo) And pulp fibers obtained from non-wood pulp such as kenaf, bagasse, hemp, cotton, etc.) and mechanical pulp: TMP, pressure-modified 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 in the first paper 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 itself in the production process is good 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-proofing agent of the present invention can be enjoyed more.

  The content of the dye in the first paper layer is not particularly limited, but in order to obtain a sufficient coloring effect, the amount added to the raw pulp slurry is 10 kg or more and 50 kg in terms of solid content with respect to 1 t of pulp fibers. The following are preferable, 15 kg or more and 40 kg or less are more preferable, and 20 kg or more and 35 kg or less are more preferable. When the content of the dye in the first paper layer is less than the lower limit, it may be difficult to darkly color the paperboard. On the other hand, if the content of the dye exceeds the above upper limit, the amount of dye that is not fixed increases, and there is a risk that discoloration is likely to occur.

(Pigment)
The pigment is not particularly limited, and a known pigment such as an organic pigment or an inorganic pigment can be used depending on the purpose.

  Examples of organic pigments include lake pigments and toner pigments. Specifically, rhodamine lakes, methyl violet lakes, quinoline yellow lakes, malachite green lakes, alizarin lakes, carmine 6B, lakelets, disazo yellows, chromophthal yellows, chromoses. Phthascarlet, Nickel Azo Yellow, Permanent Orange, Phthalocyanine Blue, Phthalocyanine Green, Flavanthrone Yellow, Thioindigo Bordeaux, Perinone Red, Dioxadone Violet, Quinacridone Red, Naphthol Yellow, Pigrant Green, Lummogen Yellow, Signal Red, Alkaline Blue, Aniline Black etc. are mentioned.

  Examples of inorganic pigments include natural inorganic pigments and artificial inorganic pigments. Specific examples include titanium dioxide, zinc white (zinc oxide), iron oxide, chromium oxide, iron black, cobalt blue, alumina white, and iron oxide yellow. , Viridian, zinc sulfide, lithopone, cadmium yellow, yellow lead, cadmium red, molybdate orange, zinc chromate, strontium chromate, white carbon (anhydrous silicic acid), clay, talc, ultramarine, barium sulfate, barite powder, calcium carbonate, Examples include ferrocyanide, lead white, manganese violet, and carbon black.

  Among these, organic pigments are preferable as chromatic pigments such as red, yellow, green, blue, purple, etc., in terms of excellent fixability to pulp and water resistance, such as white and black As the achromatic pigment, an inorganic pigment is preferable.

  The content of the pigment in the first paper layer is not particularly limited, but in order to obtain a sufficient coloring effect, the amount added to the raw pulp slurry is 3 kg or more and 9.2 kg or less in terms of solid content per 1 t of pulp fibers. Is preferably 3.5 kg or more and 8.5 kg or less, more preferably 4 kg or more and 8 kg or less. When the pigment content is less than the lower limit, a desired dark color tone may not be obtained. On the other hand, when the pigment content exceeds the above upper limit, the ratio of the pigment to the pulp becomes excessive, and there is a possibility that discoloration or uneven color due to spillage of the pigment is likely to occur.

  Further, the average particle diameter of the pigment is preferably 10 μm or less, more preferably 5 μm or less, further preferably 0.03 μm or more and 1.5 μm or less, and a particle size distribution having a particle diameter of 0.05 μm or more and 1.0 μm or less is 90%. The above inorganic, azo, or polycyclic color pigments are particularly preferable in that the occurrence of uneven color is small. When the average particle diameter of the pigment is less than the above lower limit, it is difficult to uniformly disperse in the pulp slurry and is likely to aggregate, so that a uniform coloring effect cannot be obtained and color unevenness may be caused. On the other hand, when the average particle diameter of the raw material exceeds the above upper limit, there is a possibility that discoloration due to the pigment is likely to occur due to an increase in spillage between the pulp fibers after papermaking.

  Further, in the colored paperboard, the content ratio of the dye and the pigment in the first paper layer is preferably 2: 1 or more and 4: 1 or less, and preferably 2.5: 1 or more and 3.8: 1 or less. More preferred. When the content ratio is less than the above lower limit, there is a possibility that the content ratio of the dye may be relatively reduced and coloring may not be sufficiently dark, and the pigment content ratio may be relatively increased to cause spillage of the pigment after papermaking. May increase. On the other hand, when the said content ratio exceeds the said upper limit, there exists a possibility that the color fading derived from a dye may increase by the content ratio of a dye increasing relatively.

(Waterproofing agent)
The water-proofing agent is not particularly limited. For example, polyamide / epichlorohydrin resin, polyamide / polyamine resin, polyamide / epoxy resin, urea-formaldehyde resin, melamine-formaldehyde resin, polyamide polyurea-formaldehyde resin. , Glyoxal, cyclic urea-glyoxal reactant, acrylamide-reactant copolymer, 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, as the water-resistant agent, a resin-based water-resistant agent is preferable, a polyamide-based water-resistant 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 function of the water repellent described later can be effectively expressed.

  The content of the water-proofing agent in the first paper layer is not particularly limited, but the addition amount to the raw pulp slurry is preferably 1 kg or more and 60 kg or less in terms of solid content with respect to 1 t of pulp fibers, and 2 kg or more and 30 kg. The following is more preferable. 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-proofing agent exceeds the above upper limit, paper yellowing, soiling of a paper machine or flattening equipment, and uneven color of the resulting colored paperboard may occur.

  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 appropriately control the hydrophilicity of the dye, and the function of the water-repellent agent can be improved. It can be expressed more effectively.

(Water repellent)
The water repellent is not particularly limited, for example, wax such as paraffin wax and natural wax; synthetic resin such as polyamide resin and polyamine resin; fluorine resin such as polytetrafluoroethylene and polychlorotrifluoroethylene; Examples thereof include silicone resins such as polymethylhydrogensiloxane and polydimethylsiloxane. Among these, a wax is preferable from the viewpoint of effectively exhibiting a function of suppressing elution of a dye while maintaining water repellency when used with a water-resistant agent.

  The content of the water repellent in the first paper layer is not particularly limited, but the amount added to the raw pulp slurry is preferably 2 kg or more and 50 kg or less in terms of solid content with respect to 1 t of pulp fibers, and 5 kg or more and 20 kg or less. Is more preferable. When content of a water repellent is less than the said minimum, there exists a possibility that the function of a water-resistant agent may not fully be exhibited. On the other hand, when the content of the water repellent exceeds the above upper limit, the paper may be yellowed, the printability may be deteriorated, and the color board may be uneven in color.

(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 fixability of the dye and the pigment is increased, so that the color fading when wetted 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-SO2 copolymer, 8) diallylamine salt-SO2 copolymer, 9) dimethyldiallylammonium chloride polymer, 10) polymer of allylamine salt, 11) dialkylaminoethyl ( Me ) Acrylate quaternary salt copolymer, 12) acrylamide-diallylamine salt copolymer, 13) aluminum salt such as polyaluminum chloride, polyaluminum acetate, 14) polyhydric phenol-formalin polycondensate derivative, 15) carboxylic acid amide One or more condensate quaternary ammonium compounds can be used.

  Among these, as the fixing agent for dyes, when a polyhydric phenol-formalin polycondensate derivative and a carboxylic acid amide condensate quaternary ammonium compound are used in combination with a water-resistant agent, the color development property and fixing property of the dye are good. It is preferable for the reason that color unevenness hardly occurs.

  The content of the dye fixing agent in the first paper layer is not particularly limited, but the amount added to the raw pulp slurry is preferably 1.0 kg or more and 4.0 kg or less in terms of solid content with respect to 1 t of the pulp fiber. 1.5 kg or more and 3.5 kg or less are more preferable, and 2.0 kg or more and 3.0 kg or less are more preferable. When the content of the dye fixing agent is less than the lower limit, the function of the dye fixing agent may not be sufficiently obtained. On the other hand, if the content of the dye fixing agent exceeds the above upper limit, the paper may be yellowed, the printability may be deteriorated, or the color may be uneven.

  As a fixing agent for pigments, a carboxylic acid amide condensate quaternary ammonium compound is preferable because it has good compatibility with pigments and good fixing properties, and color unevenness is less likely to occur.

  The content of the pigment fixing agent in the first paper layer is not particularly limited, but the addition amount to the raw pulp slurry is preferably 0.1 kg or more and 1.0 kg or less in terms of solid content with respect to 1 t of the pulp fiber, 0.15 kg or more and 0.8 kg or less is more preferable, and 0.2 kg or more and 0.5 kg or less is more preferable. When the content of the pigment fixing agent is less than the lower limit, the function of the pigment fixing agent may not be sufficiently obtained. On the other hand, when the content of the pigment fixing agent exceeds the above upper limit, the texture may be deteriorated or the color may be uneven.

(Other additives)
The first paper layer may further contain other additives. Examples of other additives include a sulfuric acid band, an internally added sizing agent, and an internally added paper strength agent.

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

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

(Other paper layers)
The other paper layers other than the first paper layer also contain pulp fibers as a main component in the same manner as the first paper 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.

  Other paper layers can also contain various additives similar to the first paper layer.

  In other paper layers, particularly in the second paper layer laminated on the back side of the first paper layer, the content of the sizing agent is preferably smaller than the content (addition amount) in the first paper layer. By doing so, when water soaks into the first paper layer, the water easily moves to the second paper layer. Therefore, according to such a colored paperboard, it is difficult for the first paper layer to retain moisture, and color fading when wet with water can be further reduced.

(surface treatment)
The colored paperboard may be subjected to a surface treatment, and is preferably subjected to a surface treatment by applying a coating liquid containing a water repellent 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 of the colored paperboard is further increased and the color fading can be further reduced.

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

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

The coating amount of the water repellent is not particularly limited and can be, for example, 0.01 g / m ² or more and 1.5 g / m ² or less in terms of solid content, and 0.02 g / m ² or more and 1. 0 g / m ² or less is preferable. By setting the coating amount of the water repellent to the above lower limit or higher, more sufficient water repellency can be obtained, and by setting the amount to the upper limit or lower, it is preferable because a decrease in the slip angle caused by the water repellent can be alleviated.

  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 pigment, a water-proofing agent, and a water-repellent agent are used as additives in the slurry for the first paper layer, and a fixing agent is preferably used.

  In the step (1), the dye and the pigment are preferably added before the water-resistant agent and the water-repellent agent are added. By doing in this way, after fixing dye and a pigment to a pulp fiber, the hydrophilic property of 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, (i) a dye (and a fixing agent if necessary), (b) a pigment (and a fixing agent if necessary), (c) a sulfuric acid band, (d) It is preferable to add a water-resistant agent and a water-repellent agent in this order. Furthermore, instead of adding the entire amount of the dye and / or pigment in the above (a) and / or (b), most of the dye and / or pigment is added in the above (a) and / or (b). On the other hand, it is preferable to add a small amount of dye and / or pigment (complementary color) for color adjustment after (d). In particular, it is most preferable to add most of the pigment in the above (b) and adjust the color with the pigment after (d).

(Quality etc.)
The brightness on the surface of the colored paperboard on the first paper layer side 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 when the colored paperboard is such a dark color, uneven color and discoloration are reduced. The lower limit of lightness 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 as defined by JIS-P8140. The Cobb water absorption at a contact time of 120 seconds defined by JIS-P8140 on the surface is 50 g / m ² or less, so that when the water repellent is applied, the water repellent penetrates into the base paper. It can suppress and can improve a water repellency more.

  The paper surface pH of the colored paperboard is preferably 3.5 or more and 6.0 or less. If the paper surface pH is less than 3.5, the paper strength may deteriorate with time, while if it exceeds 6.0, the water repellent effect is low, and the water repellency may deteriorate with time or heat. There is. 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. There is no restriction | limiting in particular as a method of making paper surface pH into the said range, For example, it can adjust 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 using a sulfuric acid band, it is preferable to perform a surface treatment using a water repellent composed of an anionic compound. By coating the surface with a water repellent comprising an anionic compound, the active aluminum contained in the base paper and the water repellent comprising the anionic compound are electrically coupled, and the water repellent is fixed on the surface of the base paper. Therefore, a high water repellency can be obtained.

In the colored paperboard, the basis weight of the first paper layer is preferably 20 g / m ^{2 to} 35 g / m ^2, more preferably 20 g / m ^{2 to} 30 g / m ^2, and more preferably 20 g / m. and even more preferably from ² or more 25 g / ^{m 2} or less. If the basis weight of the first paper layer exceeds the above upper limit, a large amount of chemicals and raw materials may be used, which may increase the cost. On the other hand, if the basis weight of the first paper layer is less than the lower limit, the thickness of the first paper layer may not be uniform. Further, the smaller the basis weight of the first paper layer, the more the color tone of the second paper layer appears on the surface of the paperboard, which may reduce the appearance. In such a case, the middle layer in contact with the first paper layer can be colored in a color close to the first paper layer to improve the formation.

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

The basis weight of the colored paperboard is not particularly limited, but is preferably, for example, 100 g / m ² or more and 400 g / m ² or less, and more preferably 100 g / m ² or more and 340 g / m ² or less.

  The thickness of the colored paperboard is not particularly limited, but is preferably 120 μm or more and 480 μm or less, and more preferably 120 μm or more and 410 μm or less.

  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]
(First paper layer)
Raw material pulp (upper white waste paper: white pulp content: 100%) is put into a dyeing batch tank having a stirring device, and a dye A composed of dyes of the types and blending amounts shown in Table 1 is 34 kg / t, “YT-100 (manufactured by Gokoku Color Co., Ltd .: solid concentration 61%)” as a pigment, 12.329 kg / t, “WS4024 (polyamide-epichlorohydrin resin with a solid content concentration of 25%, Starlight PMC) 40 kg / t [10 kg / t in terms of solid content], “Coat Sizer MN2L (wax emulsion with a solid content concentration of 50%, manufactured by Daiwa Chemical Co., Ltd.)” 27.3 kg / t [solid] 13.7 kg / t in terms of minute], “Cartaletin (carboxylic acid amide condensate quaternary ammonium compound having a solid content concentration of 25%: manufactured by Clariant Japan)” as a pigment fixing agent. 32 kg / t [0.31 kg / t in terms of solid content], “Carta FixTPS (polyamine having a solid content of 50%: manufactured by Clariant Japan)” 5.0 kg / t [2.5 kg in terms of solid content] / T], sulfuric acid band 45.5 kg / t, “NES-780H (made by Harima Chemicals)” 53.4 kg / t as an internal sizing agent, “RB-36 (made by Harima Chemicals)” 59 as a paper strength agent .1 kg / t was added to obtain a raw pulp slurry for the first paper layer.

Details of the dyes shown in Table 1 are shown below.
BFN (solid content concentration 77%: manufactured by Clariant Japan)
Red 2BP (Solid content 78%: Toa Kasei Co., Ltd.)
Yellow G (solid content concentration 78%: manufactured by Nippon Chemical Industry Co., Ltd.)
Black RP (Solid content: 78%, manufactured by Nippon Chemical Industry Co., Ltd.)

(2nd to 5th paper layers)
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.

(surface treatment)
A coating liquid containing the following chemicals is wet 10 g / m ² (the coating amount of water repellent (solid content) is 0.4 g / m ² ) on the surface of the colored paperboard base paper on the first paper layer side. The colored paperboard of Example 1 was obtained.
Externally added water repellent: “WR3932 (manufactured by Seiko PMC, paraffin wax, solid content 10%) 38.9%,
Anti-slip agent: “AT3802 (manufactured by Seiko PMC, styrene polymer, solid content 25%) 4.3%,
Surface sizing agent: “KN-275P (made by Harima Chemicals)” 1.6%

[Examples 2-34]
Example 1 except that the amount of pigment added, the solid content ratio of dye to pigment, the type of water-resistant agent, the type of internally added water repellent, and the type of externally added water repellent were changed as shown in Table 2. Thus, colored paperboard of Examples 2-34 was obtained. In Examples 3 to 12, the amount of dye A added was adjusted so that the solid content ratio of the dye and the pigment would be the values shown in Table 2.

In addition, the chemical | medical agent used in Examples 2-34 is as follows.
・ Waterproofing agent Polyamide-polyamine resin: “Arafix (Arakawa Chemical Industries)”
Polyamide / epoxy resin: “Sumirez Resin 650 (30) (manufactured by Taoka Chemical Co., Ltd.)”
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 35]
Internal sizing agent
A colored paperboard of Example 15 was obtained 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.

[Example 36]
Example 1 was used except that Dye B was used instead of Dye A and 1.429 kg / t of “Cartaletin (Carboxamide Condensate Quaternary Ammonium Compound: Clariant Japan)” was used as the fixing agent. Thus, a colored paperboard of Example 16 was obtained.

[Comparative Example 1]
A colored paperboard of Comparative Example 1 was obtained in the same manner as in Example 1 except that no pigment was added.

[Comparative Example 2]
A colored paperboard of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that the amount of dye A added was 1.5 times that of Comparative Example 1.

[Comparative Example 3]
A colored paperboard of Comparative Example 3 was obtained in the same manner as in Example 1 except that the water-resistant agent was not added.

[Comparative Example 4]
A colored paperboard of Comparative Example 4 was obtained in the same manner as in Example 1 except that the water repellent was not added.

[Evaluation]
The following items were evaluated for each of the obtained colored paperboards.

[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 results are shown in Table 2.
A: There is no color transfer.
○: Slight color migration can be confirmed.
Δ: Color transfer can be confirmed.
X: Color transfer is conspicuous.

[Color unevenness]
The color unevenness of the colored paperboard obtained in the examples and comparative examples was visually evaluated according to the following evaluation criteria. The results are shown in Table 2.
A: There is no uneven color.
○: Color is uneven but not noticeable.
Δ: Color unevenness is slightly noticeable.
X: Color irregularity is conspicuous.

[brightness]
In accordance with JIS-Z8722, the lightness (L) of the surface on the first paper layer side was measured. The results are shown in Table 2.

  As shown in Table 2, according to the colored paperboard of the present invention, the color unevenness is suppressed and the color fading (color transfer) occurs when it gets wet with water even though it is darkly colored so that the lightness is 60 or less. It can be seen that the occurrence of is reduced.

  As described above, the colored paperboard of the present invention can suppress color unevenness even when it is a dark-colored paperboard having a lightness of 60 or less, for example. It can be suitably used for building materials and the like.

Claims (5)

A colored paperboard comprising a plurality of paper layers,
A colored paperboard, wherein a dye, a pigment, a water-resistant agent and a water-repellent agent are internally added to the first paper layer located on the surface.   The colored paperboard according to claim 1, wherein the content ratio of the dye and the pigment in the first paper layer is 2: 1 or more and 4: 1 or less.   The colored paperboard according to claim 1 or 2, wherein the content of the pigment in the raw material pulp forming the first paper layer is 3 kg or more and 9.2 kg or less per 1 t of pulp in terms of solid content.   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 any one of claims 1 to 4, wherein a coating liquid containing a water repellent is applied to the surface of the first paper layer.