JP4952628B2 - Coating liner and corrugated cardboard sheet using the same - Google Patents

Description

  The present invention relates to a coating liner and a corrugated cardboard sheet using the liner. In particular, the present invention relates to a liner for a cosmetic corrugated cardboard having excellent ink color development properties for flexographic printing.

  In general, the liner is a cardboard made up of 2 to 9 layers. In the case of 2 layers, waste paper pulp that is not deinked is used for the back layer, and in the case of 3 layers or more, for the purpose of cost and resource saving. The Liners are processed into cardboard sheets in combination with core base paper and used in various packaging boxes. However, in recent years, the function of cardboard boxes has only to be protected from physical forces that are received during the distribution process such as storage and transportation. In addition, many multi-color printing has been carried out in order to add a function as a product face so that the product can be seen on display or in a cellar with the product packed. For this reason, flexo printing, which has made remarkable technological progress compared to offset and gravure printing, is a recent wave of digitization in response to market issues such as the increase in variety of small lots, environmental and safety issues, and cost reduction. At the same time, it is attracting attention with its innovative and innovative technology. Furthermore, the print quality is comparable to other printing methods, and has a great advantage in terms of water-based and solvent-free. Flexo printing has already become mainstream in the packaging field in Europe and the United States. There are signs of dissemination. Under such circumstances, a liner called a cosmetic liner, in which multi-color printing is performed using a conspicuous and attractive print as a color liner other than a normal craft color, is blended with bleached pulp or upper white paper pulp on the surface layer, or white It was manufactured by applying a pigment paint and increasing the whiteness of the surface. Further, since measures for the surface layer alone are costly, pulp having a certain degree of whiteness may be used for the surface lower layer (layer immediately below the surface layer) to conceal the color of the intermediate layer. Those having such a high whiteness appearance give not only a blank paper surface but also an effect that the printed surface looks beautiful and vivid when printed on it. For this reason, corrugated cardboard boxes that have been color-printed using this type of liner have a high eye-catching effect, and in order to faithfully represent the contents, the contents are excellent. There is an excellent aspect that can appeal strongly. In recent years, it has become common to sell products packed in cardboard boxes at stores, mainly from mass retailers. From this point of view, a beautiful and vivid liner has been printed. It has been demanded.

  For this reason, a liner that provides a calm visual effect with a deep white paper appearance and printed appearance by adjusting the whiteness and hue of the liner surface to a predetermined range is disclosed. (See Patent Document 1) Further, as a liner having excellent white paper appearance and sharpness of printed image, the brightness of the surface layer is in the range of 60 to 73, and the ash content of the surface layer is 3% by weight or more and less than 9%. It is disclosed. (See Patent Document 2) In addition, the coating layer containing pigment and binder as main components adjusts the whiteness, hue, and gloss to a specific range, thereby giving a calm visual effect on a blank sheet and printing characters. A cosmetic liner is disclosed that is easy to read, and has good color development, good printing gloss, and a clear printed surface when printed in color. However, all of these disclosures merely define the hue as a liner, and are not proposals that sufficiently satisfy the printability in flexographic printing. In addition, there is a method in which a large amount of white ink is printed on a general brown liner and then multicolor is printed to add cosmetics. In this case, the surface of the brown liner is made white, red or indigo. In order to improve the finish of multi-color inks and the like, it is necessary to print a large amount of expensive white ink, and this method is also a large economical burden. There is disclosed a liner in which a coating layer containing a pigment and a binder is provided on the surface layer of the liner, and the oil resistance (the number of kits) is 12 or more. (Refer to Patent Document 4) This type of liner has an oil resistance level that is too high to provide excellent flexo ink colorability.

  Furthermore, as a method for obtaining a liner having excellent flexographic printability, a technique for improving the printing effect by applying a cationic resin to the liner surface is disclosed. (See Patent Documents 5 and 6) However, the color development of the ink and the finish of the printed surface are not satisfactory.

Moreover, as a pigment composition in the aqueous composition when the aqueous composition mainly composed of a pigment and an adhesive is applied to the liner base paper, (a) 20 to 70 parts by weight of calcined kaolin, (b) structured 15 to 77 parts by weight of kaolin and / or delaminated kaolin, and (c) 3 to 20 parts by weight of plastic pigment, and the total of (a) + (b) + (c) is 70 parts by weight or more A coating liner is disclosed (see Patent Document 7). However, its purpose is to obtain a coating liner suitable for gravure printing and excellent in blank paper gloss and printing gloss, and when a liner having a coating layer of this pigment composition is subjected to aqueous flexographic printing, Only inks with inferior ink density and inferior print finish can be obtained. Furthermore, in order to obtain a coating liner excellent in blank paper gloss and printing gloss without occurrence of flexo printing mottling, as a smoothness characteristic of the coating layer surface, a pressure type smoothness meter was used under a pressure condition of 5 kgf / cm ² . A coating liner having a smoothness of 3.0 μm or less when measured and a ratio of 0.3 to 0.8 with the smoothness measured at 20 kgf / cm ² has been proposed (see Patent Document 8). This proposal solves the problem by specifying appropriate smoothing because normal coating liners are low in smoothness and tend to cause mottling and to increase printing gloss. In this case, the ink absorption of the coating layer is inferior, and in particular, the ink coloring property can be obtained only at an insufficient level. In addition, in gravure printing, flexographic printing, offset printing, and inkjet recording methods, high printing gloss is obtained, and for the purpose of preventing ink from peeling off due to friction after printing, an inorganic pigment, binder, In addition, it has been proposed to apply a coating agent containing three of the surface sizing agent. (See Patent Document 9) In particular, since the surface sizing agent is blended in order to suppress the absorption of water and solvent, the absorption of the ink is suppressed and a high ink coloring property cannot be obtained.

  On the other hand, to form a corrugated cardboard sheet, a sheet called a core processed on a wave by a corrugator (bonding machine) is glued to the back side of the liner, and another liner is pasted to the opposite side. In order to form the sheet, the sheet is folded with a ruled line for folding, but the surface of the corrugated cardboard sheet is stretched at the time of folding or assembling in a box. Therefore, the liner surface on the front side may break. This breakage is called “ruled line cracking”.

  Various proposals have been made as countermeasures against this ruled line breakage. For example, a method of applying a soft calender treatment after applying water and a water-soluble substance on the liner surface as required (see Patent Document 10), a liner manufactured by adding an amphoteric surfactant to a pulp slurry (Patent Document) 11), a method of containing a cationic surfactant on the liner surface (see Patent Document 12), or a water-soluble lignin and (meth) acrylamide amphoteric or cationic copolymer in pulp slurry containing waste paper pulp. However, in particular, a liner produced by adding a secondary diallylamine-based polymer salt to the essential component of the copolymer (see Patent Document 13) has been proposed. None of these countermeasures for ruled line cracking is provided with a pigment coating layer on the liner surface, and it is difficult to apply when a pigment coating layer is provided, or satisfactory results cannot be obtained. .

JP 2001-146697 A Japanese Patent Laid-Open No. 2007-100300 JP 2002-317395 A JP 2007-154360 A JP 2004-232158 A JP 2004-231901 A Japanese Patent Application Laid-Open No. 11-279989 JP 2000-314095 A Japanese Patent Laying-Open No. 2005-089931 JP 2000-303384 A Japanese Patent Laid-Open No. 2001-262496 JP-A-11-200209 Japanese Patent Laid-Open No. 06-184983

  The present invention provides a liner excellent in color developability with respect to flexographic printing inks, particularly aqueous flexographic inks, excellent in printing uniformity, and excellent in ruled line cracking, and a corrugated cardboard sheet using the same.

In a coating liner in which a coating layer containing a pigment and an adhesive is provided on one side of a base paper composed of at least two or more layers, a pulp used as a surface layer of the base paper 5 to 30 % by mass of kraft pulp and 70 to 95% by mass of deinked pulp and / or hardwood bleached kraft pulp, and 30 to 95 parts by mass of calcined kaolin per 100 parts by mass of pigment in the coating layer and a coating liner, characterized in that it contains 5 to 50 parts by weight of talc.
The whiteness of the coating liner surface is preferably 50 to 85%.
A cardboard sheet using the coating liner as described above is preferred.

  According to the present invention, it is possible to provide a liner excellent in ink color development in flexographic printing, excellent in printing uniformity, and excellent in ruled line cracking, and a corrugated cardboard sheet using the liner.

  In general, flexographic printing is performed using a water-type ink, so that the ink penetration varies depending on the degree of water absorption of the printed surface. For this reason, the color developability, printing uniformity, and halftone dot reproducibility in flexographic ink are greatly affected by the degree of water absorption on the printed surface and the flexographic ink amount. When calcined kaolin is present in the coating layer formed on the liner surface, the flexographic ink absorbability is extremely improved. By adjusting the blended quantity of this calcined kaolin and other pigments, it can be applied to various flexographic printing presses. It is possible to obtain a liner with good ink color development. Regarding the ruled line cracking of the coating liner provided with the pigment coating layer, 5% or more of softwood bleached kraft pulp (hereinafter referred to as NBKP) is contained as the pulp type used for the surface layer, and as other pulp, deinked pulp And / or hardwood bleached kraft pulp (hereinafter LBKP).

Here, the reason why the calcined kaolin is contained in the coating layer to improve the flexibility of flexographic printing is not necessarily clear, but the calcined kaolin is obtained by treating the naturally produced kaolin with a kiln or the like at a high temperature of about 800 ° C. The crystal water that is present in the crystal structure of kaolin is released, and the crystal structure collapses to become an amorphous structure, which is opaque, porous, and has excellent ink absorbability. From this, the porosity of the calcined kaolin allows the ink to be taken into the pigment, and the solvent in the ink is absorbed uniformly, resulting in ink color development and uniformity, and a halftone dot due to improved adhesion. It is considered that reproducibility can be obtained. The content of the calcined kaolin is 30 to 95 parts by weight, preferably 60 to 90 parts by weight, per 100 parts by weight of the pigment.

Moreover, talc is essential as a pigment contained in the coating layer. The reason for this is that when a foreign object comes into contact with the liner surface and rubs when the corrugated cardboard sheet or cardboard box is manufactured, if the liner surface has a high frictional resistance, the liner surface is likely to be contaminated due to foreign matter adhesion. This is a flat pigment, because it has the property of reducing frictional resistance when it is present in the coating layer, thereby reducing dirt due to foreign matter. In general, talc for papermaking has an average particle size of 1 to 5 μm and a chlorite content of 0 to 90% as measured by sedigraph. Among them, the use of talc with a chlorite content of 5 to 50% is This is more preferable because the balance between the dispersibility of the pigment and the effect of reducing dirt during processing is balanced. The content of talc, pigment 100 parts by weight per 5 to 50 parts by weight. Although the talc content varies depending on the chlorite content, it is more preferably 15 to 40 parts by mass. Here, as content of the preferable baking kaolin in a talc compounding, it is 40-95 weight part, More preferably, it is 60-85 weight part.

In the present invention, the coating layer of the paint containing calcined kaolin and talc may be a single layer or a multilayer, but the total coating amount is preferably ² to 10 g / m ² . When the coating amount is within this range, it is possible to obtain a liner which is excellent in economic efficiency and excellent in the color developability of the water-based flexographic ink. A more preferable coating amount is 3 to 7 g / m ² .

  As a pigment for paints to be coated on the liner base paper surface, calcined kaolin, pigments other than talc, pigments commonly used in the papermaking field, such as clay, structured kaolin, engineered kaolin, aluminum hydroxide, titanium dioxide, Use one or more of light calcium carbonate, heavy calcium carbonate, barium sulfate, zinc oxide, satin white, calcium sulfate, etc., within the range that does not impair the desired effect of the present invention from the viewpoint of absorbency of flexographic ink can do. Here, organic pigments such as plastic pigments are not preferred because of their poor ink absorbability.

Furthermore, it is preferable to add a water retention agent to the coating material to be coated on the liner base paper surface because the coating suitability is improved. As the water retention agent to be added, sodium salt of carboxymethyl cellulose, which is generally called CMC in the papermaking field, hydroxyethyl cellulose, polyvalent carboxylic acid acrylic copolymer called synthetic water retention agent, methacrylic acid and acrylic ester And the like. Among them, sodium salt of carboxymethyl cellulose is easy to apply uniformly on the coated surface, and particularly has a degree of etherification of 0.60 to 1.00 and a degree of polymerization of 600 to 1200.
The thing of the range of is preferable. In general, CMC is provided in a powder bag, and must be dissolved before use in a paint. In the process of preparing the paint, dissolving CMC with another melting equipment requires two stirring tanks, and the paint adjustment process is complicated. Moreover, when CMC is dissolved and allowed to stand, the viscosity may decrease, and the stability of the physical properties of the paint is inferior. Therefore, it is only necessary to add at the final stage of the paint preparation, and the use of a synthetic water retention agent having good stability of the paint properties after the addition and easy handling is also an aspect in which the paint adjustment is performed efficiently.

The adhesive in the paint of the present invention is not particularly limited, and a known adhesive used in the general coated paper manufacturing field is appropriately used. For example, styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, conjugated diene copolymer latex such as styrene-methyl methacrylate-butadiene copolymer latex, acrylic ester and / or methacrylate ester Acrylic polymer latex such as a polymer or copolymer latex, vinyl polymer latex such as ethylene-vinyl acetate polymer latex, or these various polymer latexes were modified with a functional group-containing monomer such as a carboxyl group. Examples include water-dispersible adhesives such as polymer or copolymer latex, synthetic resin adhesives such as polyvinyl alcohol and olefin-maleic anhydride resins, and starches such as oxidized starch, positive starch, esterified starch, and dextrin. The One or more of these water-dispersible and / or water-soluble adhesives can be appropriately selected and used. It is preferable to use 10 to 50 parts by mass of the adhesive with respect to 100 parts by mass of the pigment. More preferably, it is 15-40 mass parts. Incidentally, if the content of the adhesive is less than 10 parts by mass, the strength of the coating layer cannot be maintained. If the amount is 50 parts by mass or more, the ratio of the pigment in the coating layer becomes small, so that ink color development in flexographic printing and / or printing uniformity are inferior.

  Additives such as anti-slip agents and dyes may be used in combination in the paint used in the present invention as long as the effects of improving the ink coloring property and finishing the printing uniformity are not impaired.

When coating the paint of the present invention on the liner base paper, a coating device generally used for coated paper production can be used, for example, blade coater, air knife coater, roll coater, reverse roll coater, bar coater, curtain. On-machine or off-machine liners using coating equipment such as coaters, die slot coaters, gravure coaters, chaplex coaters, 2 roll size press coaters, gate roll size press coaters, film metallizing size press coaters, etc. The base paper is coated with a single layer or multiple layers. The solid content concentration of the pigment composition at the time of coating can be selected in the range of 10 to 75% by weight, but the coater to be coated should be applied so that the coating amount remains in the range of ² to 10 g / m ^2. It is preferable to adjust appropriately in consideration.

  In order to further improve the coating surface and printability, the coating liner coated in the present invention is a calender device such as a super calender using a cotton roll as an elastic roll and a soft nip using a synthetic resin roll as an elastic roll. The smoothing process can be performed. The soft nip calender can set the heat-resistant temperature on the surface of the synthetic resin roll higher than that of the cotton roll, so it can be processed at high temperatures, and compared with the super calender when the same smoothness is targeted. This is a preferred embodiment because the treatment linear pressure can be set low.

The pulp constituting the surface layer of the base paper for the coating liner of the present invention contains 5% to 30 % by mass of NBKP, and the beating degree is preferably 300 to 500 ml. Other types of pulp include waste paper (collectively referred to as Kent waste paper) collected from cutting of coated paper for printing generated from bookbinding and printing factories, magazine waste paper, flyer waste paper, waste newspaper waste, office waste paper, information waste paper It is used by blending 70 to 95% by mass of pulp and / or LBKP obtained by deinking waste paper such as corrugated waste paper and paperboard waste paper.

  The pulp constituting the lower layer, middle layer, and back layer is not particularly limited. For example, unbleached, bleached chemical pulp, mechanical pulp, non-wood pulp, and Kent waste paper, magazine waste paper, flyer waste paper, which are wood pulp One kind or two or more kinds selected from pulp obtained by deinking waste paper such as newspaper waste paper, office waste paper, information paper waste paper, cardboard waste paper, and paper container waste paper, and pulp such as manila hemp are suitably used. For the middle layer and the back layer, it is desirable to appropriately select and use the pulp to be used depending on the grade of the liner. For example, when the strength is required, it is preferable to use unbleached kraft pulp or used corrugated paper. Further, since the surface lower layer is a layer in contact with the liner surface layer, it tends to affect the whiteness of the surface, and therefore it is preferable to use bleached kraft pulp or deinked pulp.

  Internally added chemicals can also be used as necessary, for example, sizing agents such as sulfuric acid bands and rosins, paper strength enhancers such as polyamide and starch, drainage yield improvers, water resistance agents such as polyamide polyamine epichlorohydrin, Dyes are used.

  The liner base paper of the present invention has a multilayer structure formed by combining two or more pulp layers, and can be produced by a known multilayer paper machine.

  Here, the whiteness of the liner base paper surface is applied to the present invention in the range of 40 to 80%. The higher the whiteness of the base paper, the higher the visual whiteness after coating, and the higher the contrast of the portions with and without flexographic printing, so the printed finish is improved. In order to increase the whiteness of the base paper, it is necessary to whiten the pulp used, which increases the economic burden. Considering the balance between printing finish and economy, the base paper whiteness is preferably in the range of 50 to 70%. In addition, it is desirable to add a sizing agent to the surface layer of the base paper to be coated in order to suppress the penetration of the paint.

  The flexographic ink for printing on the coating liner of the present invention is not particularly limited, and examples thereof include an alcohol type, a cosolvent type, an aqueous type, and a UV curable type. Among these flexographic inks, an aqueous type is also included. However, it is also excellent in safety, workability, and economical efficiency, and is an embodiment in which the effects of the present invention are most prominent.

  Also, the flexographic printing press used is classified into three types, stack type, line type, and central impression type, depending on the arrangement of printing units, but any type can be used.

  The coated liner obtained by the present invention can be used as a cardboard liner provided on at least one outermost surface, and the cardboard sheet of the present invention is provided. As a corrugated cardboard sheet, a single-sided cardboard sheet in which a liner is bonded only to one side of the core, a double-sided cardboard sheet in which a liner is bonded to both sides of the core, and a plurality of core / liner laminates provided in a plurality of stages Although there are corrugated cardboard sheets, the present invention is applicable to any corrugated cardboard sheet.

  There is no restriction | limiting in particular as a core of the corrugated member which comprises a corrugated board sheet with a liner, What is used for the general corrugated board sheet can be used. As raw material pulp, semi-chemical pulp (SCP), Chemi-ground pulp (CGP), corrugated waste paper pulp, magazine waste paper pulp, unbleached kraft pulp, kraft pulp, synthetic fiber, etc. can be used. It is preferable to use a lot of waste paper pulp such as corrugated waste paper pulp and magazine waste paper pulp. The core may be a laminated paper, and may further be a laminated paper having a synthetic resin adhesive layer between layers.

  The corrugated board sheet of the present invention can be produced by applying a conventionally known corrugated board production method as it is, for example, through a corrugator treatment in which a core and a liner are bonded via an adhesive substance. Adhesive materials include starch paste and synthetic resins (polyethylene, polypropylene, polyamide, polyester, ethylene-unsaturated carboxylic acid copolymer, styrene-butadiene copolymer, butadiene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer). Polymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyacrylate copolymer, styrene-acrylate copolymer, etc.).

  Specifically, (1) A method in which an adhesive layer is formed on the surface of the core or liner by extrusion lamination or application of a synthetic resin emulsion, etc., and then these are stacked, pressed and heated to be bonded, (2) A method in which a synthetic resin film is interposed between the core / liner and the pressure is applied to heat the film, and (3) an adhesive such as a synthetic resin emulsion or solution is interposed between the core / liner. And a method of applying pressure and heating to bond them. In the method (2), a pre-molded synthetic resin film can be fed out and supplied between the core and the liner, or the synthetic resin film can be supplied between the core and the liner while being melt-extruded. You can also

  A single-sided cardboard sheet is manufactured by performing the corrugator process once, and a double-sided cardboard sheet or a multi-stage cardboard sheet is manufactured by repeatedly performing a plurality of times. The double-sided corrugated cardboard sheet is, for example, a single facer (SF) in which a core and a liner are bonded with a heat and pressure roll to form a single-sided cardboard sheet, and a liner is further provided on the core side of the single-sided cardboard sheet obtained by SF. It can be manufactured using a corrugator having a double facer (DF) that travels on a hot plate while being stacked and pressed. The heating and pressing conditions are not particularly limited. For example, the heating temperature of SF is 150 to 200 ° C., the linear pressure is 20 to 40 kN / m, the pressing time is 0.01 to 0.20 seconds, and the heating temperature of DF is 150 to 200 ° C. A linear pressure of 0.1 to 1.0 kN / m, a pressurization time of 2 to 7 seconds, and the like are preferable.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these ranges. In the examples, “parts” and “%” indicate parts by mass and mass% unless otherwise specified.

Example 1
As surface pulp, NBKP 15%, LBKP 30%, Kent waste paper 55%, US basis weight 30g / m ² , Kent waste paper 100% Kent waste paper 30g / m ² , middle layer, back lower layer, back layer As a pulp, a liner base paper having a basis weight of 170 g / m ² made into five layers was obtained with a basis weight of 110 g / m ² combined with 70% waste newspaper and 30% magazine waste paper. The surface layer has a paper strength agent (trade name: Polystron P-1222, manufactured by Arakawa Chemical Industries Co., Ltd.) 1.3%, a sulfuric acid band 3%, and a sizing agent (trade name: Size Pine SPN-815, Arakawa Chemical Industries). 2.5%). In addition, 0.1% of a paper strength agent (trade name: Polystron P-1222, supra) was added to the front, lower, middle and back layers.

Next, calcined kaolin (trade name: Ansilex 93, manufactured by BASF) 80 parts, talc (trade name: NK-KCL, manufactured by Kanematsu Chemical Co.) 20 parts, adhesive (trade name: B-1535, manufactured by Asahi Kasei Co., Ltd.) ) And 28 parts of a water retention agent (trade name: SN924, manufactured by San Nopco) 0.4 parts (all in terms of solid content) were prepared to a concentration of 40%. The prepared coating liquid is coated on the above-mentioned 170 g / m ² liner base paper with a bar coater so that the dry weight becomes 6 g / m ² (solid content), dried, and then subjected to a 2Nip calendering treatment. Got.

Example 2
In Example 1, NBKP 30% and Kent waste paper 70% are used as the surface pulp, 70% newspaper waste paper and 30% magazine waste paper are used as the lower layer pulp, sulfuric acid band 2%, paper strength agent (trade name: Police A coated liner was obtained in the same manner as in Example 1 except that TRON P-1222, supra) 0.8% was added.

Reference example 1
In Example 1, 15 parts of calcined kaolin (trade name: Ancilex 93, supra), 65 parts of talc (trade name: NK-KCL, supra), heavy calcium carbonate (trade name) : FMT90 (manufactured by Phimatech) 20 parts, coated liner obtained in the same manner as in Example 1 except that 0.4 part of CMC (trade name: BSH, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was blended It was.

Example 3
In Example 1, 70 parts of calcined kaolin (trade name: Ancilex 93, supra), 25 parts of talc (trade name: NK-KCL, supra), titanium dioxide (trade name: KA-100, manufactured by COSMO CHEMICAL) ) A coated liner was obtained in the same manner as in Example 1 except that the amount was 5 parts.

Comparative Example 1
Only 0.2 g / m ² of a surface sizing agent (trade name: PM385, manufactured by Arakawa Chemical Industries, Ltd.) was applied to the liner base paper used in Example 1.

Comparative Example 2
A coated liner was obtained in the same manner as in Example 1 except that the surface layer pulp in Example 1 was LBKP 50% and Kent waste paper 50%.

Comparative Example 3
In Example 1, a coating liner was prepared in the same manner as in Example 1 except that 100 parts of secondary kaolin (trade name: HT-GAS, manufactured by BASF) was used and the coating amount was 5.2 g / m ^2. Obtained.

Comparative Example 4
In Example 1, a coated liner was obtained in the same manner as in Example 1, except that 100 parts of calcined kaolin (trade name: Ancilex 93, supra) and the coating amount was 6.0 g / m ² .

  The obtained coating liner was evaluated by the following evaluation method, and the results are shown in Table 1. The measurement and evaluation of the printing liner in the present invention were performed in an environment of 23 ° C. and 50% RH unless otherwise specified.

(Whiteness)
The whiteness was determined according to JIS P 8148 (2001) using a spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd.).

(Smoothness)
JAPAN TAPPI No. According to 5-2: 2000, it was measured using a Oken type smoothness meter (manufactured by ASAHI-SEIKO).

(Rule cracking evaluation method)
After putting a ruled line with a ruled line forming machine having a convex / concave structure having a convex part of 0.5 to 1 mm and a concave part of 1 to 2 mm, the humidity is adjusted for 24 hours at 20 ° C. and 15% RH. After humidity control, the ruled line part is bent 180 degrees, and the top is reciprocated five times with a 5 kg roller, the length of the broken part of the bent ruled line part is measured, and the total value of the broken length is divided by the total length of the ruled line. The ruled line cracking rate was calculated.

(Dynamic friction coefficient)
In accordance with JIS P 8147: 1994, using a tensile tester (measuring instrument: Autograph AGS-500NG, manufactured by Shimadzu Corporation), the tensile speed is 100 mm / min, the weight is 1 kg, and the liner surfaces are rubbed together. The dynamic friction coefficient was measured.

(Color development and uniformity of ink in flexographic printing)
K printing proofer (manufactured by RK Print-Coat Instruments), obtained by using an aqueous flexo indigo ink (trade name: AQUA CONTE GN39SA indigo, manufactured by Toyo Ink) with an anilox plate engraved at 100 lines / inch Printed on the coating liner. The printed surface was measured for cyan ink density with a color reflection densitometer (Model 404G, manufactured by X-Rite).
The following visual evaluation was performed for flexographic printing uniformity.
A: The uniformity of the flexographic printing surface is excellent.
○: Slight unevenness is observed on the flexographic printing surface.
X: Light and shade unevenness is remarkably seen on the flexographic printing surface.

(Halftone dot reproducibility)
Ink is printed using a water-based flexographic ink (trade name: FK-99D-260 Kuro PR-7, manufactured by Sakata Inx Corporation) with a printing station type gravure printing tester (based on JAPAN TAPPI paper pulp test method No. 24). The 50% gradation part was enlarged 25 times, and the halftone dot state was subjected to sensory evaluation based on the following criteria.
○: The shape of the halftone dots is clearly recognized, but there are some defects.
Δ: A halftone dot shape is recognized, but there are more than half of the defects.
X: The shape of a halftone dot is not recognized.

(Evaluation of dirt during processing)
The obtained coated liner and non-coated liner were bonded with a corrugator using a core (product name: S120, manufactured by Oji Paperboard Co., Ltd.) and a back liner (product name: SF210, manufactured by Oji Paperboard Co., Ltd.). Corrugated sheet was made in the flute form. Thereafter, a cardboard case was prepared through a box making process. The dirt in the bonding and box making process was subjected to sensory evaluation based on the following criteria.
○: No dirt due to adhesion of foreign matter is observed on the liner surface.
Δ: Slight contamination due to adhesion of foreign matter is seen on the liner surface, but there is no practical problem.
X: Dirt due to adhesion of foreign matter is remarkably observed on the liner surface, and there is a practical problem.

At the time of pasting, the hot plate was removed and the situation was not much different in the coated and non-coated liner corrugated cardboard sheets obtained in Examples, Reference Examples and Comparative Examples. When printed, the coating liners of Examples 1 to 3 and Reference Example 1 were markedly conspicuous in visual whiteness, ink color development and uniformity in flexographic printing, and the like.

As apparent from Table 1 above, Examples 1, 2, and 3 have high whiteness and excellent ink density, printing uniformity, and halftone dot reproducibility in flexographic printing. In Reference Example 1 , although the ink density of flexographic printing is slightly inferior, printing uniformity and halftone dot reproducibility are good. In contrast, Comparative Example 1 has a low ink density, inferior flexographic printing quality, and inferior halftone dot reproducibility. Since the comparative example 2 does not have N material pulp in the surface layer, the ruled line cracking rate is high. In Comparative Example 3 in which the calcined kaolin and talc are not blended at all in the pigment, the ink density is low because the absorbency of flexographic ink is poor. Furthermore, in Comparative Example 4 in which the pigment composition is only calcined kaolin, the surface friction coefficient is high, and the dirt during processing is poor.
As described above, according to the present invention, it is possible to obtain a liner and a corrugated cardboard sheet using the same, which have excellent color development and uniformity of printed surface for flexographic inks, particularly aqueous flexographic inks, and have excellent ruled line cracking. It was.

Claims (3)

In a coating liner in which a coating layer containing a pigment and an adhesive is provided on one side of a base paper composed of at least two or more layers, a pulp used as a surface layer of the base paper 5 to 30 % by mass of kraft pulp and 70 to 95% by mass of deinked pulp and / or hardwood bleached kraft pulp, and 30 to 95 parts by mass of calcined kaolin per 100 parts by mass of pigment in the coating layer and coating the liner, characterized in that it contains 5 to 50 parts by weight of talc.   The coating liner according to claim 1, wherein the whiteness of the coating liner surface is 50 to 85%. Corrugated sheet using coating liner according to any one of claims 1-2.