JP2010065349A - Coated liner and corrugated sheet using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated liner which can especially be used as a liner excellent in halftone dot reproducibility and uniformity of water-based gravure printing and excellent in processing suitability and used for beautified corrugated boards, and to provide a corrugated sheet using the liner. <P>SOLUTION: There is provided the coated liner produced by disposing a coating layer comprising a pigment and an adhesive on one side of raw paper comprising at least two made layers, containing calcined kaolin and talc as pigments in the coating layer, being subjected to a smoothing treatment with a calender after coated, and having Oken type smoothness of 50 to 1,000 sec on the coating layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coating liner and a corrugated cardboard sheet using the same. In particular, it can be used as a liner for cosmetic corrugated cardboard, which has excellent dot reproducibility and uniformity in aqueous gravure printing and excellent processing suitability.

  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. In addition to the usual craft colors, a liner called a cosmetic liner, which performs multi-colored printing with a good appearance, is blended with bleached pulp or upper white waste paper pulp on the surface layer or coated with a white pigment paint, and the whiteness of the surface It was manufactured by raising. 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) In addition, the coating layer containing pigment and binder as main components adjusts the whiteness, hue, and gloss to a specific range, thereby providing a calm visual effect on a blank sheet and printing characters. Is a cosmetic liner that is easy to read, and has good color development and printing gloss when printed in color and has a clear printed surface (see Patent Document 2). However, these disclosures only specify the hue as a liner, and are not proposals that sufficiently satisfy halftone dot reproducibility in gravure printing. 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 (see Patent Document 3). This liner has an oil resistance level that is too high to provide excellent waterborne gravure halftone dot reproducibility.

Furthermore, in order to obtain a coating liner excellent in white paper gloss and printing gloss, the smoothness of the coated layer surface is 3.3 when measured with a pressure type smoothness meter under a pressure condition of 5 kgf / cm ² . A coating liner having a ratio of 0 to less than 0 μm and a smoothness measured at 20 kgf / cm ² of 0.3 to 0.8 has been proposed (see Patent Document 4). This proposal is aimed at eliminating the occurrence of motoring in flexographic printing, and in aqueous gravure printing, the specified smoothness results in inferior ink transfer of the coating layer and can only be obtained at an insufficient level of halftone dot reproducibility. I can't.

  By blending a pigment coating layer with a sizing agent having an alkyl ketene dimer as a main component and a zeta potential of -5 mV to 5 mV, the pigment is compared with 100 parts by weight of the pigment, and 0.2 to 0.8 parts by weight of the alkyl ketene dimer component A coated paper excellent in gravure halftone dot reproducibility, water resistance improvement during offset printing, printing processing suitability, and surface processing suitability has been proposed (see Patent Document 5). This proposal does not suggest anything about water-based gravure printing, and depending on the pigment used, there is a risk that the viscosity of the paint may increase even with the above-mentioned blending number, and stable production is possible. Have difficulty.

As a coating liner having few blank dots in gravure printing and excellent in white paper gloss and printing gloss, an aqueous composition mainly comprising a pigment and an adhesive is applied to a liner base paper in the aqueous composition. The pigment composition contains (a) 20-70 parts by weight of calcined kaolin, (b) 15-77 parts by weight of structured kaolin and / or delaminated kaolin, and (c) 3-20 parts by weight of organic pigment. And the coating liner whose sum total of (a) + (b) + (c) is 70 weight part or more is disclosed (refer patent document 6). However, this proposal is directed to oil-based gravure because there is a description that organic pigment absorbs the solvent in the ink and swells, and there is a large difference in quality required between water-based and oil-based, and water-based gravure. Does not exhibit excellent effects on printing.

  As a coated white paperboard that can be used for both offset and gravure printing and has excellent printability, it has two coating layers, and as a pigment for the undercoat layer, calcined clay, structured kaolin and delaminated clay An adhesive for the topcoat layer, containing a polymer latex having a glass transition temperature of -50 to -5 [deg.] C. as an adhesive containing at least one pigment selected from It has been proposed to use a latex having a glass transition temperature of 0 ° C. or higher. In order to support both printing methods, the undercoat layer has a cushioning property to promote adhesion with the plate during gravure printing, and the overcoat layer has a function to prevent offset piling. (See Patent Document 7). However, there is no description of water-based gravure printing. In water-based gravure printing, ink is hard to be absorbed in the coating layer compared to oil-based printing, and this proposal provides excellent quality for water-based gravure printing. I can't.

JP 2001-146697 A JP 2002-317395 A JP 2007-154360 A JP 2000-314095 A JP-A-11-269798 Japanese Patent Application Laid-Open No. 11-279989 JP 2002-363877 A

  The present invention provides a coating liner having excellent halftone dot reproducibility and uniformity with respect to aqueous gravure printing and excellent in workability, and a corrugated cardboard sheet using the same.

The present invention relates to 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 layers, and calcined kaolin as a pigment in the coating layer. And a talc-coated coating liner that is smoothed with a calender after coating, and the coated surface has a Wangken-style smoothness in the range of 50 to 1000 seconds.
The content of calcined kaolin in the coating layer is preferably 30 to 95 parts by mass with respect to 100 parts by mass of the pigment.
The content of talc in the coating layer is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the pigment.
It is preferable that the content of the adhesive in the coating layer is 10 to 50 parts by mass with respect to 100 parts by mass of the pigment.
A corrugated cardboard sheet using the coating liner is preferred.

  According to the present invention, it has become possible to provide a coating liner excellent in halftone dot reproducibility and uniformity of aqueous gravure printing and excellent in workability, and a corrugated cardboard using the same.

  In general, water-based gravure printing has different ink penetration depending on the degree of water absorption on the printing surface, and greatly affects the color development, printing uniformity and halftone dot reproducibility of the ink. For this reason, an object is to provide a coating layer containing an appropriate pigment in order to suppress water absorption and ink vehicle. As a result of repeated studies to satisfy the water absorption characteristics of aqueous gravure printing, the coating layer contains calcined kaolin and talc, and the coating layer is calendered to adjust to a specific surface smoothness. It has been found that a printing effect with extremely excellent color developability, printing uniformity and halftone dot reproducibility can be obtained.

  The reason why the reproducibility of the water gravure dot is improved by including calcined kaolin and talc in the coating layer is not necessarily clear, but calcined kaolin is a high-temperature treatment of naturally produced kaolin at about 800 ° C with a kiln or the like. By releasing the crystal water existing in the crystal structure of kaolin, the crystal structure collapses to become an amorphous structure, and it is opaque, porous, and has excellent ink absorption properties. . 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 the color development and uniformity of the ink, and also the reproducibility of the halftone dot. Think of things. However, calcined kaolin is harder than ordinary pigments, and when it is contained in the coating layer, it increases the frictional resistance of the coating layer surface. On the other hand, talc for papermaking is generally a flat pigment with excellent coverage and excellent ink receptivity, an average particle size of 1 to 5 μm measured by sedigraph, and a chlorite content of 0. Although it is ˜90%, the use of talc having a chlorite content of 5 to 50% is more preferable because the balance between the dispersibility of the pigment and the effect of reducing dirt during processing is balanced. Further, when talc is present in the coating layer, it has a property of reducing frictional resistance, and the coating layer surface becomes slippery. Thus, the coexistence of calcined kaolin and talc allows water-based gravure ink to absorb water and talc with excellent ink receptivity due to the porosity of calcined kaolin, and the friction resistance of the coating layer surface is adjusted in a well-balanced manner. The However, calcined kaolin is bulky and talc is flat and large in particle size, so the smoothness after coating of any pigment is not good, so calendering is performed after coating to smooth the coating layer surface. It is essential to make it. By this calendering treatment, the adhesion to the gravure plate can be improved and the halftone dot reproducibility of the excellent aqueous gravure printing can be expressed.

In order to exhibit excellent halftone dot reproducibility of aqueous gravure printing, the Oken type smoothness of the coating layer surface after the calendar treatment needs to be in the range of 50 to 1000 seconds. If the smoothness is less than 50 seconds, the halftone dot reproducibility of the aqueous gravure is inferior. Conversely, if it exceeds 1000 seconds, the adhesion to the gravure plate is excellent, but the calendering conditions are too strong, and the air permeability of the liner There is a risk that the moisture balance will be lost and curling will occur, or when a corrugated sheet is produced, adhesion failure may occur in the process of heating and pressure bonding the liner and the core.

  Here, the content of calcined kaolin in the coating layer is preferably 30 to 95 parts by mass, more preferably 60 to 90 parts by mass per 100 parts by mass of the pigment. As content of talc, 5-50 mass parts is preferable per 100 mass parts of pigments. More preferably, it is 15-40 mass parts by chlorite content rate. As mentioned above, the coating layer containing talc has the property of making the surface easy to slip, so it has the function of reducing dirt generated at the time of contact between the liner surfaces and the machine at the time of corrugated sheet processing or boxing, It exhibits excellent properties in processability.

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 having excellent economical efficiency and excellent dot reproducibility. A more preferable coating amount is 3 to 7 g / m ² .

  As pigments other than calcined kaolin and talc, which are paint pigments applied to the liner base paper surface, pigments commonly used in the papermaking field, such as clay, structured kaolin, engineered kaolin, aluminum hydroxide, titanium dioxide, One kind or two or more kinds of light calcium carbonate, heavy calcium carbonate, barium sulfate, zinc oxide, satin white, calcium sulfate and the like can be used. It should be noted that pigments other than calcined kaolin and talc are preferably used in the range that does not impair the desired effect of the present invention from the viewpoint of the absorbability of aqueous gravure ink, but organic pigments such as plastic pigments are ink-absorbing. Is not preferable because it is inferior.

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.
Those in the range are preferable in terms of good handleability.

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. The adhesive is preferably used in an amount of 10 to 50 parts by mass 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. When the amount exceeds 50 parts by mass, the ratio of the pigment in the coating layer becomes small, so that the absorbability of the aqueous gravure ink is inferior and the reproducibility of the halftone dot is also adversely affected.

  Additives such as surface sizing agents, anti-slip agents, and dyes may be used in combination in the coating material used in the present invention as long as the effects of the halftone dot reproducibility and 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 mass, but the coater to be applied 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.

  The coated liner coated in the present invention needs to be smoothed by a calendar device such as a super calender using a cotton roll as an elastic roll or a soft nip using a synthetic resin roll as an elastic roll. The soft nip calender can set the heat resistance temperature on the surface of the synthetic resin roll higher than that of the cotton roll, the temperature of the metal roll to be paired can be processed at a high temperature (50 to 150 ° C), and the same smoothness This is a preferable mode because the treatment linear pressure can be set lower than that of the super calendar when the property is targeted. The processing conditions depend on the calendar to be adopted, but the linear pressure is generally in the range of 10 to 400 kN / m, more preferably in the range of 10 to 200 kN / m so that the Oken smoothness is in the range of 50 to 1000 seconds. It is processed.

  The pulp constituting the liner base paper used in the present invention is not particularly limited. For example, unbleached kraft pulp such as softwood unbleached kraft pulp and hardwood unbleached kraft pulp, which are wood pulp, softwood bleached kraft pulp (NBKP) ), Bleached kraft pulp such as hardwood bleached kraft pulp (LBKP), mechanical pulp such as thermomechanical pulp, groundwood pulp, refining groundwood pulp, non-wood pulp such as hemp, bamboo, straw, bagasse and magazine waste paper, flyers A variety of known pulps such as waste paper, waste paper, office waste paper, information paper waste paper, corrugated paper waste, waste paper pulp such as paperboard waste paper, etc., or a mixture of two or more of them may be used as appropriate. When using these pulps, it is desirable to adjust the freeness to 200 to 500 ml.

  Internally added chemicals can be added to the pulp slurry as necessary. For example, sizing agents such as sulfuric acid band and rosin, paper strength enhancers such as polyamide and starch, drainage retention improvers, polyamide polyamine epichlorohydrin, etc. Water resistance agents, dyes and the like are used. Using the illustrated pulp and internal chemicals, a base paper that has been combined into two or more layers by a paper machine combining a known long net former and circular net former that can be combined in multiple layers is used. It is also possible to increase the strength between the layers by spraying or applying an adhesive such as starch between the layers when the sheets are combined.

  The whiteness of the liner base paper surface is preferably 40 to 80%. The higher the whiteness of the base paper, the higher the visual whiteness after coating, and the greater the contrast of the portions with and without gravure 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 more 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 whiteness of the coated liner after coating on the base paper is preferably 50 to 85% from the viewpoint of printing finish.

  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 cardboard with a liner, The thing currently used for the general cardboard can be used. As raw material pulp, semi-chemical pulp, chemiground pulp, corrugated waste paper pulp, magazine waste paper pulp, synthetic fiber, etc. can be used. Of these, waste paper pulp such as corrugated waste paper pulp and magazine waste paper pulp is often used from the viewpoint of resource protection. It is preferable. 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 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 through 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.).

  Specific bonding methods for corrugated cardboard sheets are as follows: (1) An adhesive layer is formed on the surface of the core or liner by extrusion lamination, synthetic resin emulsion application, etc., and then these are stacked, pressed and heated (2) A method in which a synthetic resin film is interposed between the core and the liner, and the pressure is applied and heated to bond, and (3) an emulsion or solution of the synthetic resin between the core and the liner. And a method of adhering them by pressurization and heating. 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 is manufactured by performing the corrugator process once, and a double-sided cardboard or a multi-stage cardboard is manufactured by repeatedly performing the process multiple times. Double-sided cardboard, for example, is 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, and a liner is further stacked on the core side of the single-sided cardboard obtained by SF. It can manufacture using the corrugator which has the double facer (DF) which runs on a hot plate | board and presses it while pressing. 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 “%” are parts by mass unless otherwise specified.
Mass% is shown.

Example 1
As the surface layer pulp, NBKP 15%, Kent waste paper 85%, rice basis weight 30g / m ² , As the lower layer, Kent waste paper 100%, middle layer, back layer pulp, newspaper waste paper 60%, magazine waste paper 40%, back As the pulp of the layers, 100% of the corrugated cardboard was used to fabricate 5 layers using 35 g / m ² of rice tsubo to obtain a liner base paper of 170 g / m ² of rice tsubo. 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%). Further, 0.1% of a paper strength agent (trade name: Polystron P-1222, supra) was added to the front lower layer, middle layer, back lower layer, and back layer.

70 parts of calcined kaolin (trade name: Ancilex 93, manufactured by BASF), 30 parts of talc (trade name: Microtouch, manufactured by Nippon Mystron), 28 parts of adhesive (trade name: B-1535, manufactured by Asahi Kasei) A paint composed of 0.4 parts of a synthetic water retention agent (trade name: SN-924, manufactured by San Nopco) (all in terms of solid content) was prepared to a concentration of 40%. The prepared coating material is coated on the above-mentioned 170 g / m ² liner base paper with a bar coater so that the dry mass becomes 6 g / m ² (solid content), dried, and then a calendar composed of an elastic roll and a metal roll is used. The coated liner was obtained by calendaring under the calendar conditions of 2Nip, the temperature of the metal roll at 70 ° C., and the linear pressures of 25 kN / m and 30 kN / m, respectively.

Example 2
In Example 1, 50 parts of calcined kaolin (trade name: Ancilex 93, supra), 25 parts of talc (trade name: Microtouch, supra), heavy calcium carbonate (trade name: FMT90, manufactured by Pimatech) A coated liner was obtained in the same manner as in Example 1 except that 25 parts, the calendar condition was 3Nip, the temperature of the metal roll was 70 ° C., and the linear pressure was all 20 kN / m.

Example 3
In Example 1, the pulp of the back layer was 60% used newspaper and magazine 40%, the calendar was 1 nip, the temperature of the metal roll was 70 ° C., and the linear pressure was 50 kN / m. A coated liner was obtained by various methods.

Example 4
In Example 1, 20 parts of calcined kaolin (trade name: Ancilex 93, supra), 60 parts of talc (trade name: Microtouch, supra), 5 parts of heavy coal (trade name: FMT90, manufactured by PMMA Tech) , 5 parts of titanium dioxide (trade name: KA-100, manufactured by COSMO CHEMICAL), 10 parts of kaolin (trade name: Konzer 1500, manufactured by Imeris), calendar condition: 2Nip, metal roll temperature of 50 ° C., and linear pressure A coating liner was obtained in the same manner as in Example 1 except that all of the above were set to 50 kN / m.

Example 5
In Example 1, 80% Kent waste paper, LBKP 20% on the surface layer, 50% cardboard waste paper and 50% newspaper waste paper on the bottom layer, and 90 parts of calcined kaolin (trade name: Ancilex, supra), 10 parts of talc (trade name: Micro Touch, supra), 29 parts of adhesive (trade name: B-1535, supra), 0.8 part of carboxymethylcellulose (trade name: BSH, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Each of them was prepared so as to have a concentration of 30%. The prepared paint was applied to the liner base paper of Example 1 with a bar coater so as to be 5.0 g / m ^2, and after drying, 1 Nip, the temperature of the metal roll was 50 ° C., and the linear pressure was 50 kN / m. The coated liner was obtained by calendaring.

Comparative Example 1
A coating liner was obtained in the same manner as in Example 1 except that 100 parts of calcined kaolin (trade name: Ancilex 93, supra) was used.

Comparative Example 2
A coating liner was obtained in the same manner as in Example 1, except that 100 parts of talc (trade name: Microtouch, supra) was used.

Comparative Example 3
Only the surface sizing agent (trade name: PM385, manufactured by Arakawa Chemical Industry Co., Ltd.) was applied to the liner base paper used in Example 1 at 0.2 g / m ² to obtain a coated liner that was calendered under the conditions of Example 1.

Comparative Example 4
In Example 1, a coating liner was prepared in the same manner as in Example 1 except that 80 parts of kaolin (trade name: Konzer 1500, supra) and 20 parts of titanium dioxide (trade name: KA-100, supra) were used. Obtained.

Comparative Example 5
In Example 1, a coating liner was obtained without calendering.

  The coating liner obtained above 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 using a spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd.).

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

(Halftone dot reproducibility and uniformity in gravure printing)
After performing gravure printing using a water-based gravure ink (trade name: DIC Safe WH Process Ink, manufactured by DIC Corporation) with a printing station type gravure printing tester (based on JAPAN TAPPI paper pulp test method No24), The degree of dot missing and uniformity were visually evaluated.
(Evaluation of halftone dot reproducibility)
A: There are no missing dots.
○: The shape of the halftone dots is clearly recognized, but there are some defects.
(Triangle | delta): Although the shape of a halftone dot is recognized clearly, a defect | deletion part has more than half of the whole.
X: The shape of a halftone dot is not recognized.
(Uniformity evaluation)
A: The transfer of the ink onto the coated surface is uniform and there is no uneven absorption.
○: Some absorption unevenness is recognized depending on the gradation part.
(Triangle | delta): Transferability is somewhat non-uniform | heterogenous and some absorption unevenness is recognized.
X: Transfer is poor and uneven absorption is poor.

(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.

As is apparent from Table 1, Examples 1 to 5 contain calcined kaolin and talc in the coating layer, and are smoothed by calendering, so that they are excellent in halftone dot reproducibility and printing uniformity in gravure printing. Also, no stains are seen during processing. In Example 4, the amount of calcined kaolin is slightly small, so that the halftone dot reproducibility and uniformity are slightly inferior, but no stain is seen during processing. On the other hand, since the talc is not mix | blended in the coating layer, the comparative example 1 has generate | occur | produced the stain | pollution | contamination at the time of a process significantly. In Comparative Example 2, calcined kaolin is not blended in the coating layer, so that the halftone dot reproducibility and uniformity of gravure printing are inferior. Since Comparative Example 3 is not provided with a pigment coating layer, the halftone dot reproducibility and uniformity are inferior. Since Comparative Example 4 contains neither calcined kaolin nor talc, it is inferior in the uniformity of gravure printing, and Comparative Example 5 is not calendered so that the smoothness is low and the adhesion with the gravure printing plate is inferior. The result is poor point reproducibility.
As described above, according to the present invention, the water-gravure printing halftone dot reproducibility is excellent, the printing uniformity is excellent, and the corrugated cardboard sheet and the corrugated cardboard using the coating liner are free from troubles caused by dirt during the processing process of the corrugated cardboard box. It became possible to provide sheets.

Claims (5)

  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 layers of multi-layer paper, contains calcined kaolin and talc as pigments in the coating layer And a smoothing treatment with a calendar after coating, wherein the coated surface has a Wangken-type smoothness in the range of 50 to 1000 seconds.   The coating liner according to claim 1, wherein the content of the calcined kaolin in the coating layer is 30 to 95 parts by mass with respect to 100 parts by mass of the pigment.   The coating liner according to claim 1 or 2, wherein the content of talc in the coating layer is 5 to 50 parts by mass with respect to 100 parts by mass of the pigment.   The coating liner according to any one of claims 1 to 3, wherein the content of the adhesive in the coating layer is 10 to 50 parts by mass with respect to 100 parts by mass of the pigment.   A cardboard sheet using the coating liner according to claim 1.