JP2010077552A - Coated liner and corrugated sheet using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated liner; to provide a corrugated sheet using the liner; especially to provide a coated liner which can be used as a liner for a decorated corrugated sheet excellent in the color-developing property of a water-based flexographic ink and is used for a corrugated box strong in impact and compression on transportation; and to provide the corrugated sheet using the same. <P>SOLUTION: The coated liner is prepared by disposing a coating layer containing a pigment and an adhesive on one side of base paper composed of a plurality of embedded layers of at least three, wherein pulp used in either of the middle layer and back layer of the base paper is waste corrugated board and/or coniferous un-bleached kraft pulp; the coating layer contains calcined kaolin and talc as pigments in the coating layer, and the coated liner has a burst index of 2.0 to 5.0 kPa×m<SP>2</SP>/g. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coating liner and a corrugated cardboard sheet using the liner. In particular, it is a front liner for cardboard boxes that can be used as a liner for cosmetic cardboard sheets having excellent ink color development properties for flexographic printing and is resistant to impact and compression during transportation.

  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 corrugated cardboard sheets in combination with core base paper and used in various packaging boxes, etc. In recent years, the function of corrugated cardboard boxes can be seen in the display of goods packed or displayed on the face of goods. In order to add the function as a multi-color printing, a lot of multi-color printing has been performed. 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, in addition to the usual craft colors, liners called cosmetic liners, which perform multi-colored printing with outstanding appearance, are blended with bleached pulp or upper white waste paper pulp on the surface, or coated with white pigment paint. It was manufactured by working 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. Even when a liner having a cosmetic property is formed as a corrugated cardboard box, it is a necessary function to protect the product from physical forces that are received in the distribution process such as storage and transportation.

  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). Furthermore, as a liner excellent in white paper appearance and printed image sharpness, surface layer brightness is within a certain range (60-73), and ash content of the surface layer is disclosed to be 3% by weight or more and less than 9%. (See Patent Document 2). In addition, the coating layer containing pigments and binders as main components adjusts the whiteness, hue, and gloss to specific ranges, giving a calm visual effect on white paper, making the printed characters easy to read, and color A cosmetic liner is disclosed which has a good ink colorability when printed and a clear printing surface with a good printing gloss (see Patent Document 3). However, all of these disclosures only define the hue and brightness 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. A liner having a coating layer containing a pigment and a binder on the surface layer of the liner and having an oil resistance (number of kits) of 12 or more is disclosed (see Patent Document 4). This liner has an oil resistance level that is too high to provide excellent flexo ink color development.

  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 finished print surface are not fully satisfactory.

Further, (a) 20 to 70 parts by weight of calcined kaolin (b) structured kaolin as a pigment composition in the aqueous composition when an aqueous composition mainly composed of a pigment and an adhesive is applied to liner base paper And / or 15 to 77 parts by weight of 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, the purpose is to obtain a coating liner that is suitable for gravure printing and excellent in white paper gloss and printing gloss. When a liner having a coating layer of this pigment composition is water-based flexographically printed, Only inferior 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, only a level at which the color development of the ink is insufficient is obtained. In gravure printing, flexographic printing, offset printing, and inkjet recording methods, high printing gloss is obtained, and inorganic pigments, binders, and surfaces are used on the surface layer for the purpose of preventing ink from peeling off due to friction after printing. It has been proposed to apply a coating agent containing three sizing agents (see Patent Document 9). Among these, since the surface sizing agent is blended in order to suppress the absorption of water and solvent, the ink absorption is suppressed and a high ink color developability cannot be obtained.

  Moreover, the proposal which prescribed | regulated both the specific bursting strength of the liner used for a corrugated cardboard sheet, and the pulp water retention in the layer of the thickness from the bonding surface to 1/3 of the whole thickness is made (refer patent document 10). ). However, this proposal is aimed at improving the initial bonding strength when the corrugated sheet core is formed by laminating with a corrugated core. Further, a corrugated cardboard sheet and a corrugated cardboard box with improved vertical compressive strength in a double-sided corrugated cardboard sheet are disclosed (Patent Document 11).

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 2003-247199 A JP 2007-253490 A

  TECHNICAL FIELD The present invention relates to a coated liner and a corrugated cardboard sheet using the liner, and more particularly, a corrugated cardboard that can be used as a liner for a cosmetic corrugated cardboard sheet having excellent ink color development properties of a water-based flexographic ink and is resistant to impact and compression during transportation. A coating liner for a box and a corrugated cardboard sheet using the same are provided.

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 three layers, it is used as at least one of the middle layer and the back layer of the base paper. The pulp used is corrugated waste paper and / or softwood unbleached kraft pulp, and contains calcined kaolin and talc as pigments in the coating layer, and the specific burst strength of the coating liner is 2.0 to 5 It is a coating liner characterized by the fact that it is 0.0 kPa · m ² / g.
The coating liner preferably has a specific compressive force of 115 to 300 N · m ² / g.
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.
A corrugated cardboard sheet using the coating liner is preferred.

  According to the present invention, it is possible to provide a liner and a corrugated sheet for a corrugated cardboard box, which are excellent in ink color development in flexographic printing, have good printing uniformity, and are resistant to impact and compression during transportation.

  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 influenced 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.

  The reason why the calcined kaolin is contained in the coating layer to improve the flexibility of flexographic printing is not necessarily clear. However, the calcined kaolin is produced by treating kaolin produced in nature with a kiln or the like at a high temperature of about 800 ° C. The crystal water that is present in the crystal structure is released, the crystal structure is collapsed to become an amorphous structure, and it 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 preferably 30 to 95 parts by mass, more preferably 60 to 90 parts by mass.

Moreover, talc is required in the coating layer. The reason for this is that when foreign matter comes into contact with the liner surface and rubs during the production of corrugated cardboard sheets or boxes, the liner surface is likely to be contaminated with foreign matter if the frictional resistance of the liner surface is high. Is a flat pigment and 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 measured by sedigraph and a chlorite content of 0 to 90%. 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. Further, the content of talc is preferably 5 to 50 parts by mass per 100 parts by mass of the pigment. More preferably, it is 15-40 mass parts by chlorite content rate. Here, the content of the calcined kaolin in the case of containing talc is 40 to 95 parts by mass, more preferably 60 to 85 parts by mass.

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 water-based flexo ink color development. A more preferable coating amount is 3 to 7 g / m ² .

  As pigments other than calcined kaolin and talc, which are paint pigments to be coated on 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. In addition, it is desirable that the pigments excluding calcined kaolin and talc are used within a range that does not impair the desired effect of the present invention from the viewpoint of the absorbability of the flexographic ink, but organic pigments such as plastic pigments have an ink absorbability. Since it is inferior, it is not preferable.

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, amphoteric 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. If the amount exceeds 50 parts by mass, the ratio of the pigment in the coating layer becomes small, so that the ink color development in flexographic printing and / or the 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 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.

  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.

  Corrugated used paper and / or softwood unbleached kraft pulp (NUKP) is used as the pulp constituting the middle layer and the back layer of the base paper for coated liner of the present invention, and the beating degree is preferably 250 to 500 ml. The reason why these pulps are selected is that the fiber length of the pulp is long, so that the fibers are entangled, and as a result, the required specific burst strength and good specific compression force can be obtained.

By selecting the above pulp, the specific burst strength in the resulting coating liner is in the range of 2.0 to 5.0 kPa · m ² / g, formed into a cardboard box, and impact during product transportation. And strength against compression is maintained. Furthermore, if the specific compressive force in the lateral direction of the coating liner is in the range of 115 to 300 N · m ² / g, the strength against impact and compression during product transportation can be maintained as well as the specific burst strength. So it is more preferable.

  In addition, in the case of multilayer paper making of the surface layer and four or more layers, the pulp constituting the surface layer is not particularly limited, for example, unbleached, bleached chemical pulp, mechanical pulp, non-wood pulp, which is wood pulp, Kent waste paper, magazine waste paper, flyer waste paper, newspaper waste paper, office waste paper, information paper waste paper, cardboard waste paper, waste paper pulp such as paper container waste paper, one or more selected from pulp obtained from deinking, pulp such as manila hemp Are appropriately blended and used. However, since the surface layer is a layer in contact with the coating layer, it is preferable to use bleached pulp or deinked pulp. This is because if the whiteness of the surface layer is high, the whiteness becomes higher when the coating layer according to the present invention is provided, and a coating liner having excellent cosmetic properties can be obtained. In the case of four or more layers, it is preferable to use bleached pulp or deinked pulp because the lower surface layer is also a layer in contact with the liner surface layer and the surface whiteness is easily affected. Their beating degree is preferably 250 to 500 ml. As other pulp types, pulp obtained by deinking waste paper pulp such as waste magazine paper, flyer waste paper, newspaper waste paper, office waste paper, information paper waste paper, corrugated waste paper, paper waste paper, etc. is used.

  Here, the internal chemicals used for the liner coated base paper can be used as necessary, for example, sizing agent such as sulfate band and rosin, paper strength enhancer such as polyamide and starch, drainage retention improver, polyamide Water resistant agents such as polyamine epichlorohydrin, dyes and the like are used. The exemplified pulp and internal chemicals can be used.

  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 coating liner obtained according to the present invention is used as a liner for corrugated cardboard sheets provided on at least one outermost surface. 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 cardboard sheet | seat with a liner, What is used for the general corrugated cardboard sheet | seat 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 sheet 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.).

  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 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 “%” are parts by mass unless otherwise specified.
Mass% is shown.

Example 1
As surface pulp, NBKP 15%, Kent waste paper 85%, USP 35g / m ² , Kent waste paper 100% Kent waste 35G / m ² , NMPP 60%, magazine waste paper 40 % the basis weight and 120 g / ^{m 2,} as the pulp of the back layer, 60% waste newspaper, the amount put at 40% magazine paper combined paper making in five layers as 90 g / ^{m 2,} the basis weight 280 g / m ² liner I got the base paper. The surface layer contains a paper strength agent (trade name: Polystron P-1222, manufactured by Arakawa Chemical Industries) 1.3%, a sulfuric acid band 3%, a sizing agent (trade name: Size Pine SPN-815, Arakawa Chemical). 2.5%) was added. Further, 0.1% of a paper strength agent (trade name: Polystron P-1222, supra) was added to the front, lower, middle and back layers.

70 parts of talc (trade name: NK-KCL, manufactured by Kanematsu Chemical Co.) and 70 parts of adhesive (trade name: B-1535, manufactured by Asahi Kasei Co., Ltd.) with respect to 70 parts of calcined kaolin (trade name: Ansilex 93, manufactured by BASF) ) And 28 parts of a synthetic water retaining agent (trade name: SN-924, manufactured by San Nopco) 0.4 parts (all in terms of solid content) were prepared to a concentration of 40%. The prepared paint is coated on the above 280 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 subjected to 2Nip calendar treatment to obtain a coated liner. It was.

Example 2
In Example 1, 50 parts of calcined kaolin (trade name: Ancilex 93, supra), 25 parts of talc (trade name: Microtouch, supra), 25 parts of heavy coal (trade name: FMT90, manufactured by PMMA Tech) A coated liner was obtained in the same manner as in Example 1 except that.

Example 3
In Example 1, a coated liner was obtained in the same manner as in Example 1 except that the back layer pulp was 100% used corrugated paper.

Example 4
In Example 1, the middle layer is 60% waste paper, the magazine waste paper 40%, the back layer is cardboard waste paper 100%, fired kaolin (trade name: Ansilex 93, supra) 20 parts, talc (trade name: micro touch, front Out) 60 parts, heavy coal (trade name: FMT90, manufactured by Pimatech) 5 parts, titanium dioxide (trade name: KA-100, manufactured by COSMO CHEMICAL) 5 parts, kaolin (trade name: Conzer 1500, manufactured by Imeris) ) A coating liner was obtained in the same manner as in Example 1 except that the amount was 10 parts.

Example 5
In Example 1, a coated liner was obtained in the same manner as in Example 1 except that the surface pulp was LBKP 20% and Kent waste paper 80%. Paints include 90 parts of calcined kaolin (trade name: Ancilex, supra), 10 parts of talc (trade name: Microtouch, supra), 29 parts of adhesive (trade name: B-1535, supra), carboxy A paint composed of 0.8 parts of methyl cellulose (trade name: BSH, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) (both in terms of solid content) was prepared to a concentration of 30%. A coated liner was obtained in the same manner as in Example 1, except that the prepared paint was applied to the liner base paper of Example 1 at 5.0 g / m ² with a bar coater.

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

Comparative Example 4
In Example 1, 80 parts of kaolin (trade name: Konzer 1500, supra), 20 parts of titanium dioxide (trade name: KA-100, supra), 20 parts of adhesive (trade name: B-1535, supra) A coated liner was obtained in the same manner as in Example 1 except that.

Comparative Example 5
In Example 1, a coated liner was obtained in the same manner as in Example 1 except that the surface layer pulp was Kent waste paper 100%, the middle layer and the back layer pulp was newspaper waste paper 50%, magazine waste paper 50%.

  The resulting coated 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 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.

(Specific burst strength)
The obtained coating liner was measured according to JIS P 8131 (1995).

(Specific compression strength)
The obtained coating liner was measured according to JIS P 8126 (2005).

(Evaluation of dirt during processing)
The obtained coated liner and non-coated liner were bonded with a corrugator using a core (trade name: OPM200, manufactured by Oji Paperboard Co., Ltd.) and a back liner (trade name: OFK280, 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.

(Vertical compressive strength)
Corrugated cardboard prepared for evaluation of dirt during processing was measured according to JIS Z-0403-2 (1999).

(Color development and uniformity of ink in flexographic printing)
K printing proofer (manufactured by RK Print-Coat Instruments), an anilox plate engraved at 100 lines / inch, obtained using aqueous flexo indigo ink (trade name: AQUACONTE GN39SA indigo, manufactured by Toyo Ink Co., Ltd.) 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 magnified 25 times, and the halftone dot state was subjected to the following sensory evaluation.
○: 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.

As is clear from Table 1, Examples 1 to 5 contain calcined kaolin and talc in the coating layer, so that the ink density of flexographic printing is high, and the uniformity and halftone dot reproducibility are excellent. Since the corrugated cardboard and softwood unbleached kraft pulp are used for the back layer, it is excellent in terms of strength. In Example 4, since the amount of calcined kaolin is slightly small, the ink density, 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, since calcined kaolin is not blended in the coating layer, the flexographic printing uniformity and halftone dot reproducibility are poor. In Comparative Example 3, the flexo ink soaks because there is no pigment coating layer, and it is difficult to see as unevenness, and the printing uniformity is excellent, but the ink density is low, and the flexo printing quality is inferior. Also, the halftone dot reproducibility is poor. Since Comparative Example 4 which does not contain calcined kaolin in the pigment formulation has poor ink absorbability, the ink concentration is low. Comparative Example 5 is inferior in strength because no corrugated paper or softwood unbleached kraft pulp is used for the middle layer and the back layer. In addition, the vertical compressive strength of the corrugated board sheet produced from the coating liner of the present invention was excellent.
As described above, according to the present invention, it is possible to obtain a coating liner that can provide a corrugated cardboard box having excellent ink color development and a printed surface finish for flexographic inks, particularly aqueous flexographic inks, and strong against impact and compression during transportation. I was able to.

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 three layers, it is used for at least one of the base layer and the back layer of the base paper. The pulp used is corrugated waste paper and / or softwood unbleached kraft pulp, and contains calcined kaolin and talc as pigments in the coating layer, and the specific burst strength of the coating liner is 2.0 to 5 A coating liner, characterized in that the coating liner is 0.0 kPa · m ² / g. The coating liner according to claim 1, wherein a specific compressive force in a lateral direction of the coating liner is 115 to 300 N · m ² / g.   The coated liner according to claim 1 or 2, wherein the content of calcined kaolin in the coating layer is 30 to 95 parts by mass with respect to 100 parts by mass of the pigment.   The content of the talc in the said coating layer is 5-50 mass parts with respect to 100 mass parts of pigments, The coating liner of any one of Claims 1-3.   A cardboard sheet using the coating liner according to claim 1.