JP2010084241A - Method for producing coating liner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing coating liner which is excellent in the color development of flexographic printing inks, especially water-based flexographic inks, and is good in printing uniformity. <P>SOLUTION: The method for producing the coating liner includes coating one side of base paper including at least two or more layers with a coating liquid containing pigments and an adhesive, wherein the base paper using at least one selected from bleached softwood kraft pulp, bleached hardwood kraft pulp, and kent waste paper pulp as pulp used in the surface layer is coated with a coating liquid containing calcined kaolin in an amount of 30-95 pts.wt. per 100 pts.wt. of the pigments and talc in an amount of 5-50 pts.wt. per 100 pts.wt. of the pigments as the pigments by a bar coating method. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a coating liner. In particular, it is a method for producing a coating liner for a cosmetic corrugated cardboard, which is excellent in flexographic ink color development.

  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 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). In addition, the coating layer containing pigments and binders as the main components adjusts the whiteness, hue, and gloss to a specific range, giving a calm visual effect on white paper, making the printed characters easy to read, and color A cosmetic liner is disclosed which has good ink color development, good print gloss when printed, and a clear printed surface (see Patent Document 2). However, all of these disclosures only 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.

  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 3 and 4). However, the color development of the ink and the finish of the printed surface were not 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 5). 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 flexographic 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 . smoothness when measured at 3.0μm or less, coating the liner has been proposed ratio of smoothness measured at 20 kgf / cm ² is 0.3 to 0.8 (see Patent Document 6). This proposal solves the problem by specifying appropriate smoothing because normal coating liners are low in smoothness and easily cause mottling, and want 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.

JP 2001-146697 A JP 2002-317395 A JP 2004-232158 A JP 2004-231901 A Japanese Patent Application Laid-Open No. 11-279989 JP 2000-314095 A

  The present invention is a method for producing a coating liner excellent in color developability of flexographic inks, particularly aqueous flexographic inks, and having good printing uniformity.

The present invention relates to a method for producing a coating liner in which a coating liquid containing a pigment and an adhesive is applied to one side of a base paper composed of at least two layers of multilayer papermaking. To the base paper using at least one selected from softwood bleached kraft pulp, hardwood bleached kraft pulp and Kent waste paper pulp, calcined kaolin as a pigment is 30 to 95 parts by weight per 100 parts by weight of pigment, and talc is 100 parts by weight of pigment It is a manufacturing method of the coating liner characterized by coating the coating liquid containing 5-50 mass parts per hit by a bar coating system.
It is preferable that the dry coating amount of the coating liquid in the previous period is ² to 10 g / m2.
It is preferable that the coating liquid contains a starch derivative and / or polyvinyl alcohol, and the viscosity of the coating liquid at 60 rotations measured with a B-type viscometer is 50 to 500 mPa · s.

  According to the present invention, it has become possible to produce a coating liner excellent in ink color development in flexographic printing and excellent in printing uniformity.

  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 material comes into contact with the liner surface during the corrugated cardboard and rubs, if the frictional resistance of the liner surface is high, dirt due to foreign matter adhesion tends to occur on the liner surface, whereas talc is a flat pigment, This is to reduce contamination due to foreign matter because it has the property of reducing frictional resistance when present in the coating layer. 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. Although the talc content varies depending on the chlorite content, it is more preferably 15 to 40 parts by mass. 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.

  Examples of pigments other than calcined kaolin and talc that are used as the coating liquid coating on the liner base paper surface include pigments commonly used in the papermaking field, such as clay, structured kaolin, engineered kaolin, aluminum hydroxide, One or more of titanium, 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 to use the calcined kaolin and the pigment excluding talc in a range that does not impair the flexographic printing quality from the viewpoint of the flexographic ink absorbability, but organic pigments such as plastic pigments are preferred because the ink absorbability is poor. Absent.

Note that calcined kaolin is a pigment that is generally inferior in water retention, and the coating solution containing calcined kaolin has a poor coating property when coated on the liner surface, and a uniform coated surface is obtained. However, when flexographic printing is performed, the uniformity is lowered and the cosmetics are inferior. In order to apply such coating liquid to liner base paper, the pressure applied to the surface during coating is relatively low, it can be installed at low cost in a space-saving manner, and the coating amount can be changed simply by changing the bar. The best bar coater is available. Other coaters such as blade coaters and air knife coaters, such as post-weigh type coaters, are used to scrape off excess coating liquid, and also to film transfer type rolls such as two rolls, gate rolls, and metal ring size presses. In the coater, when the paper is transferred to the paper after pre-weighing, each paper is supported by a backing roll, so a high pressure is applied during coating, especially in the case of a coating liquid with low water retention. Penetrates deeply from the surface of the base paper, resulting in poor coverage with the surface coating solution. Furthermore, when coating with a curtain coater or die slot coater that does not have a backing roll, the coating liquid has little penetration into the base paper, and a coating layer with excellent coverage can be obtained, but the equipment is expensive and the coating is In adjusting the work amount, there are difficult points such as adjustment of the slit width and adjustment of the liquid feeding amount. In these respects, the bar coater is more economical and efficient.

Thus, suitable coating by a bar coater is applied on the surface of the liner base paper in a single layer or a multilayer by an on-machine method or an off-machine method. 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 coating amount is preferably in the range of ² to 10 g / m ² . By the way, if it is less than 2 g / m ² , the flexo ink cannot be sufficiently absorbed, the printing uniformity is poor at the time of printing, and if it exceeds 10 g / m ² , the flexographic printing performance is excellent, but the effect is saturated, Economically unfavorable. A more preferable coating amount is 3 to 7 g / m ² .

  Furthermore, it is preferable to increase the water retention in order to improve the coating suitability of the coating liquid, and it is preferable to contain a starch derivative and / or polyvinyl alcohol. Examples of the starch derivative include oxidized starch, esterified starch, etherified starch, dextrin, and cold water-soluble starch. The content is preferably 1 to 40 parts by mass, more preferably 5 to 30 parts by mass per 100 parts by mass of the pigment. Incidentally, when the blending amount of the starch derivative is less than 1 part by mass, the water retention of the coating liquid becomes insufficient, and when it exceeds 40 parts by mass, depending on the degree of polymerization of the starch derivative, the viscosity of the coating liquid is excessive. As a result, the coating with the bar coater becomes difficult.

  Here, polyvinyl alcohol is obtained by polymerizing an aliphatic vinyl ester by a known method such as bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization, for example, alcohols such as methanol, esters such as methyl acetate and ethyl acetate. It can be obtained by saponification by a known method using an alkali metal hydroxide such as sodium hydroxide or an alcoholate such as sodium methylate as a saponification catalyst in a mixed solvent of alcohol and alcohol. The saponified product is dried and pulverized by various known methods. Examples of the aliphatic vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate and the like, and industrially preferred is vinyl acetate. Moreover, you may copolymerize the unsaturated monomer copolymerizable with the said aliphatic vinyl ester, and aliphatic vinyl ester. Examples of unsaturated monomers copolymerizable with aliphatic vinyl esters include α-olefins such as ethylene and propylene, unsaturated monobasic acids such as crotonic acid and acrylic acid or salts thereof, maleic acid, and itacone. Unsaturated dibasic acids such as acids and fumaric acid or salts thereof, or unsaturated dibasic acid monoalkyl esters such as monomethyl maleate and monomethyl itaconate, (meth) acrylic acid esters, acrylamide, dimethylacrylamide, N- Amide group-containing monomers such as methylolacrylamide and N-vinyl-2-pyrrolidone, alkyl vinyl ethers such as lauryl vinyl ether and stearyl vinyl ether, silyl group-containing monomers such as trimethoxyvinylsilane, allyl alcohol, dimethylallyl alcohol, isopropenyl Allyl alcohol, etc. Hydroxyl group-containing monomers, acetyl group-containing monomers such as allyl acetate, dimethyl allyl acetate, isopropenyl allyl acetate, vinyl sulfonate group-containing monomers such as sodium vinyl sulfonate and sodium acrylamide-2-methylpropane sulfonate And halogen-containing monomers such as vinyl chloride and vinylidene chloride, and aromatic monomers such as styrene, but are not limited thereto. As a compounding quantity of polyvinyl alcohol, 1-40 mass parts is preferable per 100 mass parts of pigments, and it is more preferable to mix | blend in the ratio of 5-30 mass parts. Incidentally, when the blending amount of the starch derivative is less than 1 part by mass, the water retention of the coating liquid becomes insufficient, and when it exceeds 40 parts by mass, depending on the degree of polymerization of the starch derivative, the viscosity of the coating liquid is excessive. It rises and it becomes difficult to apply with a bar coater.

  The polyvinyl alcohol used in the production method of the present invention includes different types of polyvinyl alcohol such as those having different saponification degrees, those having different polymerization degrees, those not copolymerized and modified, and those modified by copolymerization. Two or more types may be blended. The blending may be performed in a powder state, in an aqueous solution state, or in a polyvinyl ester state before saponification.

  Other water-retaining agents include sodium salt of carboxymethyl cellulose, which is generally referred to as CMC in the papermaking field, hydroxyethyl cellulose, polyhydric carboxylic acid acrylic copolymers, which are called synthetic water-retaining agents, and methacrylic acid and acrylic esters. Copolymers and synthetic water retention agents that are easy to handle can also be used.

  The adhesive in the coating liquid in the production method of the present invention is not particularly limited, and a known adhesive used in a 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. 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 coating liquid used in the present invention as long as the effects of improving the ink coloring property and the finish of printing uniformity are not impaired.

  The coating liner manufactured by the manufacturing method of the present invention is a super calender using a cotton roll as an elastic roll or a soft nip using a synthetic resin roll as an elastic roll in order to further improve the coating surface and printability. Smoothing processing can be performed by a calendar device. 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 surface layer pulp used in the present invention includes softwood bleached kraft pulp, hardwood bleached kraft pulp, deinked pulp that is a waste paper collected from cutting of printing coated paper generated from bookbinding, printing factories, etc. Hereinafter, at least one selected from Kent waste paper is used, and the beating degree is preferably 250 to 500 ml. The reason why these pulps are selected is that the whiteness of the surface layer in contact with the coating 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 is obtained. Because it is. 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.

  The pulp constituting the layer other than the surface layer is not particularly limited, for example, unbleached wood pulp, bleached chemical pulp, mechanical pulp, non-wood pulp, Kent waste paper, magazine waste paper, leaflet waste paper, newspaper waste paper, One or two or more kinds selected from pulp obtained by deinking waste paper pulp such as office waste paper, information paper waste paper, cardboard waste paper, and paper container waste paper, and pulp such as manila hemp are used as appropriate. When the base paper has a structure of three or more layers, it is desirable to appropriately select and use the pulp to be used depending on the grade of the liner for the middle layer and the back layer. For example, when the strength is required, it is preferable to use unbleached kraft pulp or used corrugated paper. It is preferable to use bleached pulp or deinked pulp because the surface lower layer in contact with the liner surface layer tends to affect the whiteness of the surface. When using these pulps, it is desirable to adjust the beating degree to 200 to 500 ml.

  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%.

  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. 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 penetration of the coating liquid. Using the illustrated pulp and internal chemicals, the base paper made into a multilayer structure by combining two or more pulp layers with a paper machine combining a known long net former and round net former that can be laminated in multiple layers. Is done. 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 flexographic ink for printing on the coated liner produced in the present invention is not particularly limited, and examples thereof include alcohol type, cosolvent type, aqueous type, and UV curable type. Among these, the water-based type is excellent in terms of safety, workability, and economy, and is an embodiment in which the printing effect of the coating liner produced in the present invention is most noticeable.

  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 produced according to the present invention can be used as a cardboard liner provided on at least one outermost surface. Corrugated cardboard includes single-sided cardboard with a liner bonded to only one side of the core, double-sided cardboard with liners bonded to both sides of the core, and multiple-level cardboard with multiple layers of core / liner laminates. However, the coated liner produced in the present invention is applicable to any cardboard.

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 (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.

  A corrugated board sheet is produced through a corrugator treatment in which the above core and the coating liner produced in the present invention are bonded via an adhesive substance. Examples of the adhesive substance include starch paste and synthetic resin ( Polyethylene, polypropylene, polyamide, polyester, ethylene-unsaturated carboxylic acid copolymer, styrene-butadiene copolymer, butadiene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, polyvinyl acetate, ethylene-vinyl acetate copolymer Polymer, polyacrylate copolymer, styrene-acrylate copolymer, etc.).

  As a concrete example of the corrugator treatment method, (1) an adhesive layer is formed on the surface of the core or liner by extrusion lamination, application of a synthetic resin emulsion, etc., and then these are overlaid, pressed and (2) A method in which a synthetic resin film is interposed between the core and the liner, and this is pressurized and heated to bond. (3) An emulsion or solution of the synthetic resin between the core and the liner. For example, there may be mentioned a method in which an adhesive such as, for example, is interposed, and this is pressurized and heated to adhere. 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 “%” indicate parts by mass and mass% unless otherwise specified.

Example 1
Using NBKP 15%, LBKP 30%, Kent waste paper 55%, Kent waste paper 100%, middle layer, back lower layer, back layer pulp 70% newspaper waste paper 30% the machine speed 400 meters / minute, to give respectively the basis weight of each layer, the liner base paper 40,35,30,30,35g / ^{m 2} and paper making in the five-layered combined 170 g / ^{m 2.} 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. As a pigment, 70 parts of calcined kaolin (trade name: Ancilex 93, manufactured by BASF), 30 parts of talc (trade name: Microtouch, manufactured by Nippon Mystron), adhesive (trade name: B-1535, manufactured by Asahi Kasei) A coating solution consisting of 28 parts of water and 0.4 part of a water retention agent (trade name: SN924, manufactured by San Nopco) (all in terms of solid content) was prepared to a concentration of 40%, and the dry weight was 6 g / m. ^{2 With an} on-machine bar coater (solid content) so that it becomes 2Nip on the calendar composed of an elastic roll and a metal roll after coating and drying, the linear pressure is 25 kN / m and 30 kN / m respectively. The coated liner was obtained by processing.

Example 2
In Example 1, the amount of the water retaining agent in the coating solution was 0.2 parts, and 2 parts of polyvinyl alcohol (trade name: JF25, manufactured by Nippon Pobier Co., Ltd.) was added, and the coating amount was 5.5 g / A coated liner was obtained in the same manner as in Example 1 except that m ² was used.

Example 3
In Example 1, the amount of the water retaining agent in the coating solution is 0.2 parts, 3 parts of oxidized starch (trade name: Ace C, manufactured by Oji Cornstarch) is added, and the coating amount is 5.5 g / m ^2. A coated liner was obtained in the same manner as in Example 1 except that.

Comparative Example 1
On the base paper of Example 1, the coating liquid of Example 1 was blade-coated at a blade angle of 30 ° using a Cylindrical Laboratory Coater (trade name: CLC-6000, manufactured by Simutetech International). A coated liner was obtained in the same manner as in Example 1 except that the amount was 6 g / m ² .

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
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.

  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.

(viscosity)
Using a B-type viscometer, the viscosity at 60 rpm was measured.

(Coating liquid water retention)
Using a water retention measuring device (AA-GWA, manufactured by Kaltec Scientific), the amount of water absorbed by the filter paper after 10 seconds of pressurization was measured through a membrane filter (5 μm). The smaller the value, the better the water retention.

(Coverability evaluation)
After immersing the coating liner in a 10% ammonium chloride solution for 60 minutes, blot the excess solution with filter paper, leave it in a dryer at 150 to 160 ° C. for 2 hours, and bake the base paper until it becomes dark brown. The coated surface of the processed sample was captured with a scanner at 250 gradations, and the average luminance was measured. Since the pigment in the coating liquid is white, the whiter the coating liquid covers the surface, the higher the average luminance. That is, the higher the value, the better the coating solution coverage.

(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.

  As apparent from Table 1, Examples 1 to 3 have high coverage and high whiteness. Flexo printability and halftone dot reproducibility are also excellent. Moreover, since Example 2, 3 is coated with the coating liquid which was more excellent in water retention, coverage is more favorable. However, Comparative Example 1 is inferior in whiteness, coverage, and halftone dot reproducibility because the coating liquid penetrates the base paper surface due to blade coating. Comparative Examples 2 and 3 are bar coatings, but since calcined kaolin is not contained, flexographic printing density and uniformity are inferior.

Claims (3)

  In the manufacturing method of a coating liner in which a coating liquid containing a pigment and an adhesive is applied to one side of a base paper composed of at least two layers of multilayer paper, the pulp used for the surface layer is a softwood bleached kraft pulp In the base paper using at least one selected from hardwood bleached kraft pulp and Kent waste paper pulp, 30 to 95 parts by mass of calcined kaolin as a pigment per 100 parts by mass of pigment, and 5 to 50 per 100 parts by mass of pigment The manufacturing method of the coating liner characterized by coating the coating liquid containing a mass part by a bar coating system. The method for producing a coating liner according to claim 1, wherein a dry coating amount of the coating liquid is ² to 10 g / m ² .   The coating liner according to claim 1 or 2, wherein the coating liquid contains a starch derivative and / or polyvinyl alcohol, and the viscosity of the coating liquid at 60 revolutions measured with a B-type viscometer is 50 to 500 mPa · s. Manufacturing method.