JP2015148025A - Black color paper board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black color multilayered paper board having low color unevenness and clear color tone.SOLUTION: There is provided a multilayered paper board consisting of a surface layer, a back layer, and a middle layer formed between the surface layer and the back layer, each of the layers mainly containing pulp. The surface layer and the back layer contain 1 to 8 pts.mass of a black color direct dye based on 100 pts.mass of pulp, and 5 to 15 pts.mass of a black pigment based on 100 pts.mass of the pulp. The total content of the black dye and the black pigment is 10 pts.mass or more based on 100 pts.mass of the pulp.

Description

  The present invention relates to black paperboard. More specifically, the present invention relates to black paperboard that can be suitably used for luxury packages (jewelry, cosmetics), mounts, price tags, and the like.

  Colored paper obtained by coloring paper, paperboard, etc. with a predetermined color has been used for various purposes, and among them, glossy black paperboard is used for jewelry and cosmetic packages, mounts, and price tags. It is also used in many applications that require a high-class feeling.

  As a method for producing such a colored paper, an internal addition method and a coating method are known. The internal addition method is a production method in which a dye and / or pigment is added as a colorant to a pulp slurry, and a fixing agent such as a sulfuric acid band is added thereto to fix the colorant to pulp fibers. Using the internal addition method, it is easy to obtain uniform colored paper, but on the other hand, the colorant flows into the white water, causing loss of the colorant and color blur due to the circulation of white water. There are disadvantages such as the occurrence of color differences.

  Examples of the colorant used in the internal addition method include direct dyes, basic dyes, and pigments. Direct dyes have the advantage that the fastness to light, water resistance, etc. is superior to basic dyes, but they also have the disadvantage that the color tone is less sharp than basic dyes. On the other hand, the advantage of the basic dye is that the color tone is highly clear, and in particular, it is characterized by higher dyeability for unbleached pulp than for bleached pulp. On the other hand, basic dyes have a great disadvantage that they are inferior in light resistance, and particularly dark colored paper has a large fading due to light. In addition, there is also a problem that the water resistance is low and the liquid tends to flow out when wet.

  The coating method is a method of coloring by applying a colorant (dye / pigment) on one or both sides of the paper, which is mixed with oxidized starch, polyvinyl alcohol, surface sizing agent, etc. and applied by a size press of a paper machine. It is common. The coating method has less colorant loss than the internal addition method, and has the advantage that various colors can be easily dyed by changing the composition of the coating solution. Is difficult, and color unevenness tends to occur.

  As such a colored paper, Patent Document 1 discloses a colored paper board which has a clear color tone and is particularly excellent in cosmetic properties by improving the abrasion resistance of the bent portion. Specifically, it is a paperboard having a single-layer or multiple-layer paper layer, the surface layer of the raw material pulp is internally added with a dye / pigment to color the surface layer, and the surface layer is coated with a paint containing at least the pigment. A pigment layer having the same color as that of the surface layer is applied, and a glossy resin layer is further provided on the surface of the pigment layer. Patent Document 2 discloses a colored sheet and a manufacturing method thereof. Specifically, after the dye and the pigment are uniformly dispersed by the colloidal property of the humic acid salt, the dye and the pigment are obtained by chelate adsorption action of the humic acid salt and the divalent or higher water-soluble polyvalent metal salt. The present invention relates to a colored sheet that is efficiently fixed on the fiber surface and insolubilized, and a method for producing the same.

JP 2006-169707 A JP 58-76596 A

  However, in the configuration described in Patent Document 1, since a pigment layer, a glossy resin layer, and a plurality of layers are provided on the surface of the base paper, the number of manufacturing steps is likely to increase the cost. Unevenness is also likely to occur. Moreover, in the structure described in patent document 2, since the insoluble chelate complex arises, a formation is liable to worsen and it was unsuitable for the use for which a high-class feeling is calculated | required. In other words, it has been difficult to obtain a black board having a high-class feeling with the prior art.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide a black multilayer paperboard having a small color unevenness and a clear color tone.

  Another object of the present invention is to provide a black multilayer paperboard having high gloss.

  Still another object of the present invention is to provide a black multilayer paperboard having various strengths suitable for use in packages, mounts, price tags, etc. and capable of being suitably offset printed.

  Further, other objects and operational effects of the present invention will be easily understood by those skilled in the art by referring to the following description.

  In order to solve the above-mentioned problems, the black multilayer paperboard of the present invention comprises a surface layer, a back layer, and one or more middle layers provided between the surface layer and the back layer, and each layer comprises pulp. It is a multilayer paperboard as a main component, and the surface layer and the back layer are 1 to 8 parts by mass of black direct dye with respect to 100 parts by mass of pulp and 5 to 15 parts by mass with respect to 100 parts by mass of pulp. Part of the black pigment, and the total content of the black dye and the black pigment is 10 parts by mass or more with respect to 100 parts by mass of the pulp.

  In addition, about the structure of a surface layer and a back layer here, as long as the structure of both layers is in the above-mentioned range, the structure of both layers may be the same and may be different.

  And according to such a structure, the black multilayer paperboard which has few color nonuniformity, a clear color tone, is excellent in glossiness, and has a high-class feeling is obtained.

  In preferable embodiment of this invention, it is preferable that 1-5 mass parts black pigment is contained in the said middle layer with respect to 100 mass parts of pulp.

  According to such a configuration, the black layer is also included in the middle layer, so that the cross section also becomes black, so that the white hue is not exposed from the end of the package or price tag, and the appearance is not impaired, and a consistent impression is obtained. The resulting black multilayer paperboard is obtained.

  In preferable embodiment of this invention, it is preferable that 1-10 mass parts dyeing assistant is contained in the said surface layer and the said back layer with respect to 100 mass parts of pulp.

  According to such a configuration, the black pigment is more easily fixed to the pulp by using the dyeing aid, and the black does not easily flow out into the fountain solution even when used for offset printing, and has a black color having preferable offset printability. A multilayer paperboard is obtained.

  In a preferred embodiment of the present invention, the surface hues of the surface layer and the back layer have an L * value of 23.0 or less, an a * value of −1 to +1, and ab * as measured by the method of JIS P 8150. The value is preferably in the range of -2 to +1. According to such a configuration, a black multilayer paperboard having a clear color tone can be obtained.

  In a preferred embodiment of the present invention, the surface layer and the back layer preferably have a Beck smoothness of 20 seconds or more according to JIS P8119 and a 75-degree specular glossiness of 15 or more according to JIS P8142.

  According to such a configuration, a black multilayer paperboard having a high printability due to a smooth surface, a stronger gloss, and a high quality feeling can be obtained.

  In a preferred embodiment of the present invention, the surface layer and the back layer are made of J.P. TAPPI Paper Pulp Test Method No. The surface strength by 1 m-72 is preferably 10 A or more.

  According to such a configuration, a black multilayer paperboard suitable for applications such as packages and price tags can be obtained due to the high surface strength.

  In preferable embodiment of this invention, 0.1-1.0 mass part acidic rosin sizing agent with respect to 100 mass parts of pulp as a sizing agent, and paper strength are further added to the said surface layer and the said back layer. As an agent, 1 to 2 parts by mass of cationized starch with respect to 100 parts by mass of pulp and 0.01 to 0.1 parts by mass of polyacrylamide-based paper strength agent with respect to 100 parts by mass of pulp may be included. preferable.

  According to such a configuration, the black direct dye and the black pigment are more easily fixed because the pulp slurry becomes acidic by the addition of the acidic rosin sizing agent. Further, by using a cationized starch that is a paper strength agent and a polyacrylamide type paper strength agent in combination, the strength is increased as compared with the case where it is used alone, and the suitability for a package, a mount, a price tag, etc. is improved.

  In preferable embodiment of this invention, it is preferable that the beating degree of the pulp used for the said surface layer and the said back layer is 400-600 ml by Canadian standard freeness (CSF).

  According to such a configuration, a black multilayer paperboard having an excellent balance between printability and paper strength can be obtained.

In a preferred embodiment of the present invention, the total basis weight is in the range of 200 to 500 g / m ² , and the surface area of the surface layer and the back layer is in the range of 30 to 150 g / m ^2. preferable.

  According to such a configuration, a black multilayer paperboard having a thickness suitable for use in a package, a mount, a price tag, or the like can be obtained in which the color of the middle layer cannot be seen through from the front surface and the back surface.

  The present invention can also be understood as a method for producing a black multilayer paperboard.

  The manufacturing method of the black multilayer paperboard which concerns on this invention is 1-8 mass parts black direct dye with respect to 100 mass parts of pulp, black pigment of 5-15 mass parts with respect to 100 mass parts of pulp. A pulp slurry for the front and back layers, a step of adjusting the pulp slurry for the front and back layers, a step of adjusting the pulp slurry for the middle layer, and a paper machine. A paper making step of making a black multilayer paperboard by combining the surface layer used, one or more middle layers using the middle layer pulp slurry, and the back layer using the front and back layer pulp slurry; Is included.

  Moreover, another embodiment of the manufacturing method of the black multilayer paperboard which concerns on this invention is 1-8 mass parts black direct dye with respect to 100 mass parts of pulp, and 5 with respect to 100 mass parts of pulp. Mixing a papermaking raw material containing ˜15 parts by mass of a black pigment, adjusting the pulp slurry for the surface layer, pulp, 1 to 8 parts by mass of black direct dye with respect to 100 parts by mass of pulp, and 100 parts by mass of pulp Mixing a papermaking raw material containing 5 to 15 parts by mass of a black pigment with respect to part, adjusting a back layer pulp slurry, mixing a papermaking raw material containing pulp, and adjusting a middle layer pulp slurry; and In a paper machine, the surface layer using the surface layer pulp slurry, the one or more intermediate layers using the intermediate layer pulp slurry, and the back layer using the back layer pulp slurry are made together, and black Multi-layer paper It is intended to include a paper making step of papermaking the paperboard, the.

  According to such a configuration, it is possible to efficiently produce a black multilayer paperboard having less color unevenness, a clear color tone, excellent gloss, and a high-class feeling.

  The black multilayer paperboard according to the present invention has little unevenness in color and has a high gloss feeling, so it can be suitably used for applications such as jewelry and cosmetic packages, mounts, and price tags that require a high-class feel. It is.

It is a graph (the 1) which shows the physical property and evaluation result in an Example and a comparative example. It is a chart (the 2) which shows the physical property and evaluation result in an Example and a comparative example.

  Hereinafter, preferred embodiments of the black multilayer paperboard according to the present invention will be described in detail.

  The black multilayer paperboard according to the present invention comprises a surface layer, a back layer, and one or more middle layers provided between the surface layer and the back layer, and each layer is a multilayer paper mainly composed of pulp. In the board, the surface layer and the back layer have 1 to 8 parts by mass of black direct dye with respect to 100 parts by mass of pulp and 5 to 15 parts by mass of black pigment with respect to 100 parts by mass of pulp. In addition, the total content of the black dye and the black pigment is 10 parts by mass or more with respect to 100 parts by mass of the pulp.

  As the pulp used for the surface layer, middle layer and back layer, wood bleached chemical pulp represented by softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), and waste paper pulp can be mainly used. As used paper pulp, for example, corrugated used paper, tea used paper, craft envelope used paper, magazine used paper, newspaper used paper, flyer used paper, office used paper, upper white used paper, Kent used paper, structured used paper, ground paper used paper, etc. Disaggregated / deinked waste paper pulp, deinked / bleached waste paper pulp, and the like can be used. Moreover, you may use mechanical pulps, such as a groundwood pulp (GP), a thermomechanical pulp (TMP), a bleached chemi thermomechanical pulp (BCTMP), as needed.

  The beating degree of the pulp used for the surface layer, the middle layer, and the back layer is not particularly limited, but is preferably 400 to 600 ml in terms of Canadian Standard Freeness (CSF), and particularly preferably in the range of 400 to 500 ml. If the CSF is less than 400 ml, the formation as a paperboard becomes too dense and the water absorption is lowered, which may impair the offset printability. On the other hand, if it exceeds 600 ml, the sheet will be unsatisfactory and paper strength may be reduced.

  As described above, in the present invention, both the black direct dye and the black pigment are contained in the surface layer and the back layer. Since glossy black gives a high-class feeling, black paperboard is suitable for packaging of products that require a high-class feeling such as jewelry and cosmetics, while black is recognized as uneven color even with a slight discoloration. When used in applications that are easy and require a high-class feeling, it is important that the fastness such as light resistance and water resistance is high. Therefore, as a black dye used for coloring the front layer and the back layer, it is preferable to use a direct dye having a high fastness, but a paper colored using only the direct dye has a low color clarity, There is a problem that it is difficult to obtain glossiness.

  Black pigments, on the other hand, have high fastness, excellent color tone, and glossiness. On the other hand, paper colored with only black pigments has color irregularities such as white spots. There is a problem that it is likely to occur.

  Therefore, in the present invention, the surface layer and the back layer are colored using a black direct dye and a black pigment in combination. By using a black direct dye and a black pigment in combination, both the problem of the black direct dye that the color tone is low and glossiness is difficult to obtain, and the problem of the black pigment that color unevenness easily occurs are solved. Thus, it is possible to obtain a black multilayer paperboard having little color unevenness, clear color tone and excellent gloss.

  The black direct dye used in the present invention is not particularly limited, and one or more kinds of known dyes can be appropriately selected and used. Examples of commercially available products include Rebasel Fast Black G (Blanco For Japan), Direct Paper Black KEL (Nippon Chemical Industry Co., Ltd.), Direct Paper Black DXL (Nippon Chemical Industry Co., Ltd.), KURO- There is MH-HPN (manufactured by Tokyo Aniline Dye Manufacturing Co., Ltd.). Further, the black pigment is not particularly limited, and one or more kinds of known pigments such as aniline black, iron oxide, and carbon black can be appropriately selected and used. Among these, dark black It is preferable to use carbon black because it is less likely to cause color unevenness and has good fixability and workability in the paper layer.

  In this invention, the compounding quantity of the black direct dye in a surface layer and a back layer shall be the range of 1-8 mass parts with respect to 100 mass parts of pulp in conversion of solid content, and if it is the range of 4-6 mass parts, it is more preferable. If the amount of black direct dye is less than 1 part by mass, the amount of black direct dye is too small and color unevenness is likely to occur. On the other hand, the effect reaches a peak even if the amount of black direct dye exceeds 8 parts by mass. Thus, the paper strength is reduced due to excessive blending, which is disadvantageous in terms of cost.

  Moreover, the compounding quantity of the black pigment in a surface layer and a back layer shall be 5-15 mass parts with respect to 100 mass parts of pulp in conversion of solid content, and if it is the range of 8-12 mass parts, it is more preferable. When the amount of the black pigment is less than 5 parts by mass, the amount of the black pigment is too small, so that the glossiness and color tone are inferior. On the other hand, the effect reaches a peak even when the amount of the black pigment exceeds 15 parts by mass. Thus, the paper strength is reduced due to excessive blending, which is disadvantageous in terms of cost.

  The total content of the black direct dye and the black pigment is 10 parts by mass or more with respect to 100 parts by mass of the pulp. When the total content of the black direct dye and the black pigment is less than 10 parts by mass, the pulp is not sufficiently colored, color unevenness is likely to occur, and glossiness is inferior.

  Black multi-layered paper with less color unevenness and excellent glossiness due to the above-mentioned range of the total amount of black direct dye, black pigment, and black direct dye and black pigment. It can be a paperboard. In the above, the blending amount of the black direct dye and the black pigment in the surface layer and the back layer has been described together. However, if both layers are in the above-mentioned range, the structure of both layers may be the same. It may be good or different.

  In the present invention, it is preferable to color not only the front and back layers but also the middle layer in black. When the middle layer is not colored black, the cross section of the paperboard looks white, which may impair the appearance. However, since the middle layer is a layer that does not appear, glossiness and clearness of color tone are not required unlike the front and back layers, and some color unevenness is allowed. Therefore, the coloring method of the middle layer is not particularly limited, and it may be colored black according to the desired coloring condition. As a method of coloring in black, black dyes and black pigments can be used, and among these, it is preferable to use black pigments because dark coloring can be achieved with a small amount. For example, the coloring sufficient for an intermediate layer is obtained by mix | blending 1-5 mass parts of black pigments with respect to 100 mass parts of pulp in solid content conversion.

  In the coloring of the surface layer, the middle layer, and the back layer, a dyeing aid may be used. By using the dyeing assistant, the affinity between the dye and the pulp fiber is increased, and the fixing property of the black pigment can be further improved. Examples of the dyeing aid used herein include cationic fixatives such as anhydrous sodium sulfate (sodium sulfate) and polyamine resins. In particular, when a dyeing assistant is used for the front layer and the back layer, it is preferable to use anhydrous sodium sulfate because of its excellent dyeing fastness, and the amount used is based on 100 parts by mass of pulp in each layer in terms of solid content. It is preferably 1 to 10 parts by mass, and more preferably 6 to 7 parts by mass.

  In the present invention, it is preferable to add a sizing agent and a paper strength agent to the surface layer, the middle layer and the back layer in order to improve paper strength. Sizing agents that can be used here include styrene-based sizing agents, alkyl ketene dimers (AKD), alkenyl succinic anhydrides (ASA), neutral rosin sizing agents, acidic rosin sizing agents, and the like. It is preferable to use an acidic rosin sizing agent for papermaking. Since the black multilayer paperboard of the present invention needs to contain a relatively large amount of black direct dye and black pigment in at least the surface layer and the back layer, the black direct dye and black pigment added to the papermaking raw material are efficiently added. It is required to be fixed to the pulp, and the black direct dye and the black pigment can be efficiently fixed to the pulp by performing acidic papermaking.

  In this invention, it is preferable that the compounding quantity of an acidic rosin sizing agent is the range of 0.1-1.0 mass part with respect to 100 mass parts of pulp of each layer, 0.4-0.5 mass part If it is a range, it is more preferable. In particular, it is preferably used for paper making of the front and back layers with a large amount of black direct dye and black pigment, and by giving the amount of acidic rosin sizing agent the above range, sufficient water resistance is imparted to the black board. The aptitude for offset printing can be improved. If the blending amount of the acidic rosin sizing agent is less than 0.1 parts by mass, it is difficult to obtain the desired water resistance. Conversely, if the compounding amount exceeds 1.0 parts by mass, the improvement in water resistance is almost flat. The excessive addition increases the cost.

  Examples of paper strength agents that can be used in the present invention include starch based paper strength agents, polyacrylamide based paper strength agents, polyvinyl alcohol based paper strength agents, polyamide epoxy based paper strength agents, and the like. It is preferable to use a modified starch and a polyacrylamide-based paper strength agent in combination. By adding a paper strength agent, various strengths suitable for use in packages, mounts, price tags, etc., and various paper strengths can be imparted so that offset printing can be suitably performed.

  The blending amount of cationized starch as a paper strength agent is preferably in the range of 1.0 to 2.0 parts by mass, and in the range of 1.0 to 1.5 parts by mass with respect to 100 parts by mass of pulp in each layer. Is particularly preferable. Moreover, it is preferable that the compounding quantity of a polyacrylamide type | system | group paper strength agent is the range of 0.01-0.1 mass part with respect to 100 mass parts of pulp of each layer, The range of 0.06-0.08 mass part Is particularly preferable. In paper making of each layer, cationized starch and polyacrylamide-based paper strength agent are used in combination, and by using the amounts within the above ranges, various paper strengths such as interlaminar strength are imparted to black paperboard to various packages. Suitability and offset printing suitability can be improved. If the amount of each of the cationized starch and the polyacrylamide-based paper strength agent is less than the above range, there is a possibility that various paper strengths such as interlayer strength may not be satisfied. The improvement of various paper strengths such as the above has almost reached its peak, and the cost increases due to excessive addition.

  In the present invention, each of the surface layer, the middle layer, and the back layer may contain various papermaking additives as long as the effects of the present invention are not impaired. For example, yield improver, pigment dispersant, pH adjuster, thickener, fluidity improver, antifoam agent, foam suppressor, mold release agent, penetrating agent, UV absorber, antioxidant, preservative, Known additives such as a binder, a water-resistant agent, a fluorescence quencher, a pitch control agent, and a slime control agent can be added alone or in combination of two or more.

The black multilayer paperboard of the present invention is made of paper with three or more layers having a surface layer, a back layer, and one or more middle layers provided between the surface layer and the back layer. The basis weight of the middle layer is not necessarily equal, and for example, the basis weight of the middle layer can be relatively larger than the basis weight of the surface layer and the back layer. Furthermore, the surface layer and the back layer can each be one layer, and the middle layer can be two or more layers. The basis weight of the surface layer, the back layer, and the middle layer is not particularly limited, but if the middle layer is not colored black, the surface layer and the back layer should be 30 g / m ² or more for the purpose of concealing the middle layer. It is considered preferable.

Further, preferably in the range of 200-500 g / m ² as the basis weight of the whole of the black board, particularly preferably ranges from 300 to 500 g / m ^2. By setting the rice tsubo within this range, it can be suitably used for applications such as packages, mounts, and price tags.

  The papermaking method of the black paperboard of the present invention is not particularly limited, and papermaking is carried out in three or more layers using a known paper machine, that is, a long net, a circular net, a hybrid former, a gap former, or the like. In the paper making process, using a coating device such as a size press, metering size press, gate roll coater, etc., the surface of black paperboard is coated with starch, polyvinyl alcohol, polyacrylamide, surface sizing agent, etc. alone or mixed. The working fluid can be applied. Additives such as colorants, water retention agents, water resistance agents, fluidity improvers, antifungal agents, preservatives, and antifoaming agents can be further added to the coating solution.

  Further, after papermaking and drying, a smoothing process may be performed using a calendar device such as a super calendar, a machine calendar, or a soft calendar. By performing the smoothing treatment, high glossiness is imparted to the black paperboard, and it is suitable for use in a package or the like that requires a high-class feeling.

  The black paperboard of the present invention has a Steecht sizing degree of 500 seconds or more according to JIS P 8122. TAPPI Paper Pulp Test Method No. It is preferable that the surface strength by 1 m-72 is 10 A or more, the Beck smoothness by JIS P8119 is 20 seconds or more, and the 75 degree specular gloss by JIS P 8142 is 15 or more. With such a configuration, it is possible to obtain a black paperboard having glossiness and various strengths suitable for use in high-quality packages, mounts, price tags, and the like, and suitable for offset printing. When the Steecht sizing degree is less than 500 seconds, there is a possibility that, when the paste is processed and pasted into a package or the like, the paste soaks up and sufficient adhesive strength cannot be obtained.

  Here, the surface strength of 10 A or more can be achieved by adjusting the pulp beating degree as described above or using a paper strength agent. However, since the surface strength tends to decrease when the content ratio of the used paper pulp is increased as the pulp used in each layer, the ratio of the used paper pulp to the total amount of the pulp in each layer is preferably 30% by mass or less, and 25% by mass. % Or less is more preferable.

  Further, the black paperboard of the present invention uses a black direct dye and a black pigment in the above-mentioned range. The hue of the surface of the black paperboard (surface of the front layer and the back layer) is a method of JIS P 8150. It is preferable that the L * value is 23.0 or less, the a * value is −1 to +1, and the b * value is −2 to +1.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, unless otherwise indicated, the part and addition% in an example show the mass part or mass% in conversion of solid content.

<Example 1>
(Preparation of raw slurry)
After blending 25 parts of softwood bleached kraft pulp (N-BKP), 54 parts of hardwood bleached kraft pulp (L-BKP), and 21 parts of deinked waste paper pulp (DIP) for the surface layer and the back layer, The beating process was performed by a beating machine so that the Canadian standard freeness (CSF) was 470 ml. 6.4 parts anhydrous sodium sulfate (Na ₂ SO ₄ ), 2.89 parts black direct dye (Direct First Black Conk, Taoka Chemical Co., Ltd.), and black direct 1.93 parts of a dye (KURO-MH-HPN, manufactured by Tokyo Aniline Dye Manufacturing Co., Ltd.), 10 parts of a black pigment (Sundai NP Black 7901, carbon black, manufactured by Sanyo Color Co., Ltd.), and an acidic rosin sizing agent (AL1300 as a sizing agent) , Nippon PMC Co., Ltd.) 0.4 parts, sulfuric acid band 1.0 part, and cationized starch (Neotac 40T, Nihon Shokuhin Kako Co., Ltd.) 1.26 parts as a paper strength enhancer was added to the raw material slurry. Prepared.
After blending 26 parts of softwood bleached kraft pulp (N-BKP), 53 parts of hardwood bleached kraft pulp (L-BKP), and 21 parts of deinked pulp (DIP) for the middle layer, a Canadian standard filter is used by a beating machine. The beating process was performed so that the water content (CSF) was 470 ml. 5 parts of black pigment (SP black YT-100, carbon black, manufactured by Gokoku Color Co., Ltd.) and sizing agent (AL1300, acidic rosin sizing agent, manufactured by Japan PMC) 0 in terms of solid content with respect to 100 parts of this raw material pulp .4 parts, 1.0 part of sulfuric acid band, 1.26 parts of paper strength enhancer (Neotac 40T, cationized starch, Nippon Shokuhin Kako Co., Ltd.), paper strength enhancer (DH4160, modified polyacrylamide, Japan PMC) 0.06 part) was added to prepare a raw material slurry.
(Manufacture of black paperboard)

Next, these raw material slurries are used to make a paper by a four-layer composition of a surface layer, a two-layer middle layer, and a back layer with a circular mesh type four-layer composition paper machine, and a solid having the following composition in a size press: A size press solution having a concentration of 6.5% was applied so that the coating amount on both sides of the base paper was 3 g / m ² (solid content), and the surface layer basis weight was 62 g / m ² and the back layer basis weight was 62 g / m ^2. A four-layer base paper having a basis weight of 310 g / m ² with a middle layer basis weight of 186 g / m ² ( ^two layers of 93 g / m ² ) was made, and on-machine, 3-nip calendering with a linear pressure of 100 kN / m The desired black multilayer paperboard was obtained.
(Size press liquid)
Oxidized starch (Nippon Cornstarch: SK-20) 2.5 parts PVA (Kuraray: Kuraray Poval PVA117) 4.0 parts Water 93.5 parts

<Example 2>
In preparation of the raw material slurry for the surface layer and the back layer, the blending amount of the black direct dye (Direct First Black Conk, manufactured by Taoka Chemical Co., Ltd.) was changed to 2.4 parts, and the black direct dye (KURO-MH-HPN, Example 1 except that the blending amount of Tokyo Aniline Dye Manufacturing Co., Ltd.) was changed to 1.6 parts and the blending amount of black pigment (Sundai NP Black 7901, Carbon Black, Sanyo Dyeing Co., Ltd.) was changed to 8 parts. Similarly, a black multilayer paperboard was obtained.

<Example 3>
In preparation of the raw material slurry for the surface layer and the back layer, the blending amount of the black direct dye (Direct First Black Conk, Taoka Chemical Co., Ltd.) was changed to 3.6 parts, and the black direct dye (KURO-MH- Example except that the blending amount of HPN (manufactured by Tokyo Aniline Dye Manufacturing Co., Ltd.) was changed to 2.4 parts and the blending amount of black pigment (Sundai NP Black 7901, carbon black, Sanyo Pigment Co., Ltd.) was changed to 12 parts. In the same manner as in Example 1, a black multilayer paperboard was obtained.

<Example 4>
In preparation of the raw material slurry for the surface layer and the back layer, the blending amount of the black direct dye (Direct First Black Conk, manufactured by Taoka Chemical Co., Ltd.) was changed to 2.4 parts, and the black direct dye (KURO-MH-HPN, Example 1 except that the blending amount of Tokyo Aniline Dye Manufacturing Co., Ltd.) was changed to 1.6 parts and the blending amount of black pigment (Sundai NP Black 7901, Carbon Black, Sanyo Dyeing Co., Ltd.) was changed to 12 parts. Similarly, a black multilayer paperboard was obtained.

<Example 5>
In preparation of the raw material slurry for the surface layer and the back layer, the blending amount of the black direct dye (Direct First Black Conk, manufactured by Taoka Chemical Co., Ltd.) was changed to 3.6 parts, and the black direct dye (KURO-MH-HPN, Example 1 except that the blending amount of Tokyo Aniline Dye Manufacturing Co., Ltd.) was changed to 2.4 parts and the blending amount of black pigment (Sundai NP Black 7901, carbon black, Sanyo Dyeing Co., Ltd.) was changed to 8 parts. Similarly, a black multilayer paperboard was obtained.

<Example 6>
In the production of black paperboard, the basis weight of the surface layer is changed to 93 g / m ² , the basis weight of the back layer is changed to 93 g / m ² , and the basis weight of the middle layer is changed to 280 g / m ² (140 g / m ² layers are two layers). A black multilayer paperboard was obtained in the same manner as in Example 1 except that a four-layer base paper having a basis weight of 466 g / m ² was made.

<Example 7>
In preparation of the raw slurry, the amount of deinked waste paper pulp (DIP) in each surface layer, middle layer, and back layer was changed to 30 parts, and the linear pressure of on-machine 3 nip calendering treatment was changed from 100 kN / m. A black multilayer paperboard was obtained in the same manner as in Example 1 except that it was changed to 80 kN / m.

<Comparative Example 1>
A black multilayer paperboard was obtained in the same manner as in Example 1 except that the black direct dye was not added in preparation of the raw material slurry for the surface layer and the back layer.

<Comparative Example 2>
A black multilayer paperboard was obtained in the same manner as in Example 1 except that no black pigment was added in the preparation of the raw material slurry for the surface layer and the back layer.

  About black multilayer paperboard obtained in each Example and Comparative Example, after adjusting humidity at 23 ° C. and 50% RH, measurement of each physical property (basis weight, thickness, density, Steecht sizing degree, surface strength, Beck smoothness, 75 degree specular gloss, hue) were performed according to the following methods, and the results are shown in FIGS.

[Basis weight]
Conforms to the basis weight measurement method for paper and paperboard specified by JIS P 8124.

[Thickness, density]
Conforms to paper and paperboard thickness and density test methods specified in JIS P 8118.

[Stick human sizing degree]
Paper and board sizing test method specified in JIS P 8122-Conforms to the Steecht method.

[Surface strength]
J. et al. TAPPI Paper Pulp Test Method No. 1 Conforms to surface strength test method by m-72.

[Beck smoothness]
Conforms to the smoothness test method by Beck smoothness tester for paper and paperboard specified by JIS P 8119.

[75 degree specular gloss]
Conforms to the 75-degree specular gloss measurement method for paper and paperboard specified by JIS P 8142.

[Hue (L *, a *, b *)]
In accordance with a method for measuring the color of paper and paperboard defined in JIS P 8150, the color difference meter PF-10 manufactured by Nippon Denshoku Co., Ltd. was used to measure with a light source including ultraviolet light.

[Color unevenness]
The surface of the black multilayer paperboard obtained in each example and comparative example was visually determined based on the following criteria.
A: Almost no color unevenness and passed.
○: Some color unevenness, but acceptable and acceptable level.
X: There is color unevenness and it is rejected.

  The black multilayer paperboard obtained in each example was excellent in glossiness and smoothness, had a high glossiness, had little color unevenness, had a clear color tone and a high-class feel. . The surface strength was also good, and it was a level at which offset printing could be suitably performed. On the other hand, the black paperboard obtained in Comparative Example 1 and Comparative Example 2 had color unevenness and poor quality.

  Regarding surface strength, Beck smoothness, glossiness, and hue, slight differences between the front and back surfaces are due to environmental differences during papermaking. The side is in contact with the wire, and it is considered that the difference is caused by the fact that the filler, fibers, pigments and the like are easily removed from the surface in contact with the wire.

  As described above, according to the present invention, it is possible to obtain a black multilayer paperboard having little color unevenness, a clear color tone and a glossy appearance, and excellent printability and strength. It can be suitably used for applications such as mounts and price tags.

Claims (11)

It consists of a surface layer, a back layer, and one or more middle layers provided between the surface layer and the back layer, and each layer is a multilayer paperboard mainly composed of pulp,
The surface layer and the back layer contain 1 to 8 parts by mass of black direct dye with respect to 100 parts by mass of pulp, and 5 to 15 parts by mass of black pigment with respect to 100 parts by mass of pulp, and A black multilayer paperboard, wherein the total content of the black dye and the black pigment is 10 parts by mass or more with respect to 100 parts by mass of pulp.   The black multilayer paperboard according to claim 1, wherein the middle layer contains 1 to 5 parts by mass of a black pigment with respect to 100 parts by mass of pulp.   The black multilayer paperboard according to claim 1 or 2, wherein the surface layer and the back layer contain 1 to 10 parts by mass of a dyeing assistant with respect to 100 parts by mass of pulp.   The surface hues of the front and back layers are in the range of L * value of 23.0 or less, a * value of −1 to +1, and b * value of −2 to +1 as measured by the method of JIS P 8150. The black multilayer paperboard according to any one of claims 1 to 3.   The surface layer and the back layer have a Beck smoothness of 20 seconds or more according to JIS P8119 and a 75-degree specular glossiness of 15 or more according to JIS P8142, respectively. Black multilayer paperboard.   The surface layer and the back layer are formed according to J.H. TAPPI Paper Pulp Test Method No. The black multilayer paperboard according to any one of claims 1 to 5, wherein the surface strength by 1 m-72 is 10 A or more.   The surface layer and the back layer further have an acid rosin sizing agent in an amount of 0.1 to 1.0 part by weight with respect to 100 parts by weight of pulp as a sizing agent, and a paper strength agent with respect to 100 parts by weight of pulp. The cationized starch of 1 to 2 parts by mass, and 0.01 to 0.1 parts by mass of a polyacrylamide-based paper strength agent with respect to 100 parts by mass of pulp are contained. Black multilayer paperboard according to crab.   The black multilayer paperboard according to any one of claims 1 to 7, wherein the beating degree of pulp used for the surface layer and the back layer is 400 to 600 ml in Canadian Standard Freeness (CSF). The total basis weight is in the range of 200 to 500 g / m ² , and the rice basis weight of the surface layer and the back layer is in the range of 30 to 150 g / m ^2. Black multilayer paperboard according to crab. The pulp slurry for front and back layers is mixed with pulp, 1 to 8 parts by mass of black direct dye with respect to 100 parts by mass of pulp, and 5 to 15 parts by mass of black pigment with respect to 100 parts by mass of pulp. Adjusting steps,
Mixing a papermaking raw material containing pulp and adjusting a pulp slurry for middle layer;
In a paper machine, the surface layer using the front and back layer pulp slurry, the middle layer of one or more layers using the middle layer pulp slurry, and the back layer using the front and back layer pulp slurry are combined, And a papermaking step for making the multilayer paperboard. A method for producing a black multilayer paperboard. A pulp slurry for surface layer is prepared by mixing pulp, a papermaking raw material containing 1 to 8 parts by mass of black direct dye with respect to 100 parts by mass of pulp, and 5 to 15 parts by mass of black pigment with respect to 100 parts by mass of pulp. Adjusting steps,
A pulp slurry for a back layer comprising pulp, 1 to 8 parts by weight of black direct dye with respect to 100 parts by weight of pulp, and 5 to 15 parts by weight of black pigment with respect to 100 parts by weight of pulp. Adjusting steps,
Mixing a papermaking raw material containing pulp and adjusting a pulp slurry for middle layer;
In a paper machine, the surface layer using the surface layer pulp slurry, the one or more intermediate layers using the intermediate layer pulp slurry, and the back layer using the back layer pulp slurry are made together, and a black multilayer A method for producing a black multilayer paperboard, comprising: a papermaking step for making the paperboard.

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