Wrapping paper

Abstract

To provide wrapping paper which has better printing finish feeling in printability against gravure printing than conventional wrapping paper, and has more improved missed dots than conventional wrapping paper.SOLUTION: Wrapping paper has kraft paper containing kraft pulp, and one or two or more coating layers on at least one surface of the kraft paper, wherein the outermost coating layer positioned at an outermost place based on the kraft paper in the coating layer contains at least kaolin, a hollow type white organic pigment, a binder, and an acetylene glycol-based surface active agent.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a packaging paper having a coating layer on at least one side of kraft paper and having printability for gravure printing. [Background technology]

[0002] One type of packaging paper available on the market is kraft paper. Kraft paper is made from kraft pulp produced by the kraft process. There are two types of kraft paper: unbleached kraft paper, which is usually brown in color, and bleached kraft paper, which is made from kraft pulp that has been bleached. There is also one-sided gloss kraft paper, which is made glossy by pressing one side. For example, bleached kraft paper with improved printability is known as kraft paper (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-100623 A Summary of the Invention [Problem to be solved by the invention]

[0004] There has been a growing call to move away from plastic in the field of packaging materials, such as packaging sheets, packaging bags and containers, and carrier bags. As a result, there are efforts to replace packaging materials that use resins such as polypropylene with packaging materials that use paper, i.e., packaging paper. Traditionally, kraft paper is chosen as packaging paper from the viewpoint of paper strength. Meanwhile, traditionally, multicolor printing on kraft paper has been rare. This is because traditional kraft paper, which is chosen from the viewpoint of paper strength, has problems with printability. Printing on packaging materials is usually done by gravure printing, and kraft paper has two problems with printability for gravure printing. One of the problems is that kraft paper has a lower print finish in terms of color density, color saturation, and color vividness compared to packaging materials using resins such as polypropylene. The lower print finish is an obstacle when replacing packaging materials using resins such as polypropylene with kraft paper. The remaining problem is miss dots (missing halftone dots) that occur specifically in gravure printing, which forms color gradations with ink dot patterns. Miss dots lead to defects in printed images.

[0005] The object of the present invention is to provide a packaging paper based on kraft paper, which overcomes the two problems mentioned above in terms of printability for gravure printing, i.e., a print finish that is better than conventional ones, and improved levels of missed dots compared to conventional ones. [Means for solving the problem]

[0006] The present inventors have invented the wrapping paper according to the present invention as a result of intensive research.

[0007] [1] A packaging paper comprising kraft paper containing kraft pulp and one or more coating layers on at least one side of the kraft paper, the outermost coating layer being located outermost relative to the kraft paper and containing at least kaolin, a hollow white organic pigment, a binder, and an acetylene glycol-based surfactant.

[0008] In some embodiments, the wrapping paper of the present invention is: [2] The packaging paper described in [1] above, wherein the outermost coating layer further contains a salt of a higher fatty acid. Effect of the Invention

[0009] According to the present invention, it is possible to provide a wrapping paper having a base material of kraft paper, which has printability for gravure printing, a print finish feeling better than before, and has improved miss dots compared to before. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below. The packaging paper of the present invention comprises a kraft paper containing kraft pulp and one or more coating layers on at least one side of the kraft paper. The layer located outermost relative to the kraft paper is called the outermost coating layer. When there is only one coating layer, this layer is the outermost coating layer. When the coating layer is two or more layers, the coating layer located between the kraft paper and the outermost coating layer is not particularly limited as long as it does not impair the effects of the present invention. Examples of the coating layer located between the kraft paper and the outermost coating layer include a coating layer containing a white pigment and a binder that is conventionally known in the field of coated paper.

[0011] In some embodiments, the wrapping paper has one or more coating layers on both sides of the kraft paper. The reason for this is that, whereas wrapping paper is usually printed on only one side, the kraft paper can be used as a printing surface regardless of the front or back. In some embodiments, the wrapping paper has one or more coating layers only on one side of the kraft paper. The reason for this is that it is advantageous in terms of the manufacturing cost of the wrapping paper. In some embodiments, the wrapping paper has one or more coating layers on the surface of the kraft paper, and has a backcoat layer conventionally known in the field of coated paper on the back side of the kraft paper. The backcoat layer has, for example, a function of improving dimensional stability and / or preventing curling. This improves the dimensional stability and / or curl prevention of the wrapping paper. In some embodiments, the wrapping paper has one or more coating layers on the surface of the kraft paper, and has a water-coating and drying treatment conventionally known in the field of coated paper on the back side of the kraft paper. The water-coating and drying treatment is, for example, effective in preventing curling of the wrapping paper.

[0012] In some embodiments, the wrapping paper has one or more coating layers on the surface of the kraft paper, and has a heat seal layer containing a heat sealable resin conventionally known in the packaging material field on the back side of the kraft paper, because the wrapping paper can be used as a heat seal paper. Examples of heat-sealable resins include polyester-based resins, polyvinyl alcohol-based resins, vinyl-based resins, vinylidene chloride-based resins, (meth)acrylic-based resins, polyurethane-based resins, cellulose-based resins, melamine-based resins, polyamide-based resins, polyolefin-based resins, and polystyrene-based resins.

[0013] In some embodiments, the packaging paper has one or more coating layers on the surface of the kraft paper, and has a barrier layer on the back side of the kraft paper that contains a barrier material conventionally known in the field of packaging materials. This is because the packaging paper can have barrier properties. Examples of the barrier layer include a gas barrier layer such as an oxygen gas barrier layer, a water vapor barrier layer, a moisture permeable barrier layer, and an oil barrier layer. Barrier materials that exhibit these functions are known. Examples of gas barrier materials include polyvinyl alcohol resins such as fully saponified or partially saponified polyvinyl alcohol and modified polyvinyl alcohol, urethane resins, acrylic resins, vinylidene chloride resins, proteins such as casein, soy protein, and synthetic protein, starches such as oxidized starch, cationized starch, urea phosphate esterified starch, and hydroxyethyl etherified starch, celluloses such as carboxymethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose, polyvinylpyrrolidone, and sodium alginate. Examples of water vapor barrier materials and / or moisture permeable barrier materials include olefin-based resins such as polyethylene and polypropylene, acrylic-based resins, vinyl chloride-based resins, styrene-based resins, styrene-butadiene-based resins, olefin-unsaturated carboxylic acid-based resins, styrene-unsaturated carboxylic acid-based resins, vinyl acetate-based resins, styrene-vinyl acetate-based resins, acrylonitrile-styrene-based resins, acrylonitrile-olefin-based resins, maleic acid-based resins, ABS-based resins, AAS-based resins, AES-based resins, vinylidene chloride-based resins, urethane-based resins, vinylidene fluoride-based resins, vinyl fluoride-based resins, fluorine-based resins, polycarbonate-based resins, polyamide-based resins, polyacetal-based resins, polyphenylene oxide-based resins, polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate, polyphenylene sulfide-based resins, polyimide-based resins, polysulfone-based resins, polyethersulfone-based resins, and waxes. Examples of the oil barrier material include polyvinyl alcohol-based resins, styrene-acrylic resins, and fluorine-based resins.

[0014] In this specification, the terms "front side" and "back side" of the kraft paper are expressions for convenience of distinguishing the sides of the kraft paper, and do not mean the front side and back side of the support based on a specific difference. The printability for gravure printing relates to the side having the outermost coating layer of the packaging paper.

[0015] The outermost coating layer contains at least kaolin, a hollow white organic pigment, a binder, and an acetylene glycol-based surfactant. Kaolin is a white inorganic pigment that has been conventionally known in the field of coated paper. Kaolin is usually produced by industrially refining and processing naturally occurring kaolin ore, and is produced through processes such as crushing, washing, iron removal, and classification. Kaolin also includes highly processable kaolin, such as delaminated kaolin, which is made into a thin plate shape by applying shear force to improve the aspect ratio, engineered kaolin, which has a narrow particle size distribution range, and calcined kaolin, which has improved cohesiveness.

[0016] The hollow white organic pigment is a type of white organic pigment. The hollow white organic pigment is conventionally known in the field of coated paper. Examples of hollow white organic pigments include white organic pigments produced by a method of controlling particle morphology during emulsion polymerization or an alkali / acid two-stage treatment method. Examples of monomers to be emulsion polymerized include styrene, (meth)acrylic acid and its salts, (meth)acrylic acid esters, (meth)acrylonitrile, vinyl chloride, vinyl acetate, ethylene, and butadiene. For emulsion polymerization, for example, one or more monomers selected from the group consisting of the above monomers are selected. Hollow white organic pigments are commercially available from, for example, Asahi Kasei Corporation, JSR Corporation, and The Dow Chemical Company. The hollow white organic pigment is not particularly limited as long as it has a particle-like apparent overall shape and has a hollow portion inside. In some embodiments, the hollow white organic pigment has one or more hollow portions per particle having a particle-like apparent overall shape. In some embodiments, the hollow white organic pigment has one or more openings connecting the outside of the shell of the particle to the hollow portion in a particle having a particle-like apparent overall shape. In some embodiments, the hollow white organic pigment has a particle-like apparent overall shape having a hollow portion inside, and the shape of the shell is not limited.

[0017] The outermost coating layer of the packaging paper may contain a white pigment conventionally known in the field of coated paper in addition to kaolin and hollow white organic pigments. Examples of the white pigment include white inorganic pigments such as heavy calcium carbonate, light calcium carbonate, talc, satin white, lithopone, titanium oxide, zinc oxide, amorphous silica, colloidal silica, alumina, aluminum hydroxide, zinc oxide, activated clay, and diatomaceous earth. Examples of the white pigment include white organic pigments other than hollow white organic pigments, such as solid pigments made of urea resin.

[0018] In some embodiments, the outermost coating layer of the wrapping paper contains 78 to less than 100 parts by mass of kaolin, relative to 100 parts by mass of the total white pigments contained in the outermost coating layer, including kaolin and hollow white organic pigments, and contains a hollow white organic pigment. In at least one embodiment, the outermost coating layer of the wrapping paper contains 78 to 99 parts by mass of kaolin, 1 to 6 parts by mass of the hollow white organic pigment, and 0 to 21 parts by mass of white pigments other than kaolin and hollow white organic pigments, relative to 100 parts by mass of the total white pigments contained in the outermost coating layer, including kaolin and hollow white organic pigments. The reason for this is that the print finish for gravure printing is improved.

[0019] The binder is a conventionally known binder in the field of coated paper. Examples of the binder include starches and celluloses, naturally occurring resins such as casein, gelatin, soybean protein, pullulan, gum arabic, karaya gum, and albumin, and modified products thereof, various synthetic resins such as polypropylene glycol, polyethylene glycol, maleic acid resin, acrylic resin, olefin unsaturated carboxylic acid resin, styrene butadiene resin, and ethylene vinyl acetate resin, thermosetting resins such as melamine resin and urea resin, urethane resin, polyester resin, polyvinyl alcohol resins such as fully or partially saponified polyvinyl alcohol and modified polyvinyl alcohol, polyvinyl butyral, and alkyd resin.

[0020] The acetylene glycol surfactant is a nonionic surfactant represented by the following general formula (1).

[0021] [ka]

[0022] In the formula, R1, R2, R3, and R4 are alkyl groups having 1 to 5 carbon atoms, OE is an oxyethylene chain, OP is an oxypropylene chain, m and n are integers of 1 to 24, and m+n is 2 to 44.

[0023] In some embodiments, the acetylene glycol surfactant is a compound represented by the above general formula (1), in which R1 and R4 are isobutyl groups, and R2 and R3 are methyl groups. In at least one embodiment, the acetylene glycol surfactant is a compound represented by the above general formula (1), in which R1 and R4 are isobutyl groups, R2 and R3 are methyl groups, (OEorOP) is OE, and m+n is 10. The reason for this is that printability in gravure printing improves the print finish and / or reduces dot misses.

[0024] Such acetylene glycol surfactants are commercially available, for example, as Surfynol (registered trademark) and Olfine (registered trademark) from Nissin Chemical Industry Co., Ltd., Dynol (registered trademark) from Evonik Corporation, and Acetylenol (registered trademark) from Kawaken Fine Chemicals.

[0025] In some embodiments, the amount of the acetylene glycol surfactant in the outermost coating layer is 0.1 parts by mass or more and 0.5 parts by mass or less based on 100 parts by mass of the total white pigment contained in the outermost coating layer, including kaolin and hollow white organic pigments. This is because the printability for gravure printing is improved, and the print finish feeling and / or the improvement of the missing dots are improved.

[0026] In addition to the white pigment, binder, and acetylene glycol surfactant, the outermost coating layer of the packaging paper may contain additives conventionally known in the field of coated paper, if necessary and to the extent that does not impair the effects of the present invention. Examples of additives include printability improvers, fixing agents, dispersants, thickeners, water retention agents, defoamers, lubricants, water resistance agents, colorants, ultraviolet absorbers, fluorescent agents, surfactants other than acetylene glycol surfactants, and waxes.

[0027] In some embodiments, the outermost coating layer of the packaging paper further contains a higher fatty acid salt. Examples of higher fatty acids that form the higher fatty acid salt include lauric acid, oleic acid, palmitic acid, stearic acid, and myristic acid. Examples of salts include sodium salts, potassium salts, zinc salts, calcium salts, and ammonium salts. In at least one embodiment, the higher fatty acid salt is higher fatty acid calcium salt such as calcium stearate or higher fatty acid zinc salt such as zinc stearate. The reason for this is that the combination of higher fatty acid calcium salt or higher fatty acid zinc salt with the acetylene glycol surfactant improves the printability for gravure printing and improves the print finish. In some embodiments, the content of the higher fatty acid salt in the outermost coating layer is 0.7 parts by mass or more and 1.2 parts by mass or less per part by mass of the acetylene glycol surfactant in the outermost coating layer, because the printability for gravure printing is improved, resulting in improved print finish.

[0028] The quality of gravure printing depends on the quality of the transfer of the ink present in the recesses of the gravure printing plate to the paper. The surface of the paper that receives the ink in gravure printing needs to have both wettability to allow the ink in the recesses to come into uniform contact with the paper, and lipophilicity for the transfer of the ink. In this regard, surface activity is important. The present inventors have found that acetylene glycol surfactants are excellent in this function, and further found that a combination of an acetylene glycol surfactant and a higher fatty acid salt further improves this function.

[0029] The coating layers, including the outermost coating layer, can be obtained by applying and drying a coating solution containing a predetermined material. For example, the coating and drying can be performed using a coating device and a drying device that are conventionally known in the field of coated paper. Examples of the coating device include a Comma Coater (registered trademark), a film press coater, an air knife coater, a rod blade coater, a bar coater, a blade coater, a gravure coater, a curtain coater, an E-bar coater, and a film transfer coater, etc. Examples of coating include coating using a wire bar for manual coating, which is an experimental method. Examples of the drying device include various drying devices such as hot air dryers such as a linear tunnel dryer, an arch dryer, an air loop dryer, and a sine curve air float dryer, an infrared heating dryer, and a dryer that utilizes microwaves.

[0030] After the application of the coating layers, including the outermost coating layer, the wrapping paper may be subjected to a calendering treatment, which is conventionally known in the papermaking art, since this improves the final smoothness of the kraft paper. Calendering may be achieved using a calendering device conventionally known in the papermaking art, such as the same calendering device as the example given below for the calendering of kraft paper.

[0031] Kraft paper, which is the base material for packaging paper, is made by papermaking a stock in which pulp produced by the Kraft process is dispersed in water. Papermaking can be achieved, for example, by a method using a papermaking machine conventionally known in the papermaking field. Examples of papermaking machines include a Fourdrinier papermaking machine, a cylinder papermaking machine, and a twin-wire papermaking machine. The raw material of the pulp produced by the Kraft process is wood or non-wood conventionally known in the papermaking field. The raw material of the pulp can be, for example, wood of coniferous and broad-leaved trees, and non-wood such as hemp, linter, straw, bamboo, sugarcane, reed, fruit, paper mulberry, Mitsumata and gampi. In some embodiments, the raw material of the pulp is one or more selected from coniferous and broad-leaved trees. In at least one embodiment, the kraft pulp is one or two selected from bleached coniferous kraft pulp (NBKP) and bleached broad-leaved kraft pulp (LBKP). This is because the strength of the packaging paper is improved.

[0032] The above-mentioned paper stock may contain, in addition to kraft pulp, conventionally known pulps such as mechanical pulp, deinked waste paper pulp, and pulp obtained by disintegrating broke generated in paper mills. In some embodiments, the content of kraft pulp in the kraft paper is 900 parts by weight or more based on 1000 parts by weight of the total pulp contained in the kraft paper. In at least one embodiment, the content of kraft pulp in the kraft paper is 1000 parts by weight based on 1000 parts by weight of the total pulp contained in the kraft paper. The reason for this is that the strength of the packaging paper is improved.

[0033] The above-mentioned paper stock may contain, as necessary, additives for papermaking conventionally known in the papermaking field, such as sizing agents, paper strength agents, paper strength enhancers, fixing agents, retention agents, retention improvers, colorants, fillers, waterproofing agents, dispersants, thickeners, flow improvers, defoamers, foam suppressors, release agents, foaming agents, penetrating agents, fluorescent brightening agents, ultraviolet absorbing agents, antioxidants, preservatives, and mold inhibitors.

[0034] The kraft paper can be subjected to a size press treatment with a size press liquid containing a surface sizing agent conventionally known in the papermaking field. The kraft paper can also be subjected to a calendar treatment conventionally known in the papermaking field. The kraft paper can be subjected to a size press treatment and a calendar treatment with a size press liquid containing a surface sizing agent conventionally known in the papermaking field. Here, the order of the size press treatment and the calendar treatment is not particularly limited. In some embodiments, the kraft paper is subjected to a size press treatment with a size press liquid containing a surface sizing agent conventionally known in the papermaking field, and then the calendar treatment. The reason for this is that the final smoothness of the kraft paper is improved.

[0035] Examples of the surface sizing agent include starch-based sizing agents, alkyl ketene dimer-based sizing agents, cellulose-based sizing agents, polyvinyl alcohol-based sizing agents, styrene acrylic-based sizing agents, olefin-based sizing agents, styrene maleic acid-based sizing agents, and acrylamide-based sizing agents.

[0036] The size press treatment can be achieved using a size press device conventionally known in the papermaking field. Examples of the size press device include an inclined size press, a horizontal size press, a rod metering size press, a roll metering size press, and a blade metering size press as film transfer methods, a shim sizer, an opti sizer, a speed sizer, and a film press as rod metering size presses, and a gate roll coater as a roll metering size press. Other examples of the size press device include a bill blade coater, a twin blade coater, a velbapa coater, a tab size press, and a calendar size press.

[0037] Calendering can be accomplished using any calendering device known in the papermaking art, such as a machine calender, a soft nip calender, a super calender, a multi-stage calender, and a multi-nip calender.

[0038] In some embodiments, the density of the wrapping paper is 0.85 g / cm 3 More than 1.10g / cm 3 The reason is that, for example, the paper can have resistance to folding and cracking without impairing the strength required for packaging paper. The density of packaging paper is a value determined in accordance with ISO534:2011 "Paper and board-Determination of thickness, density and specific volume".

[0039] The density of the packaging paper is a physical quantity conventionally known in the papermaking field, and can be adjusted by a method conventionally known in the papermaking field. The density of the packaging paper can be adjusted, for example, by the type and beating degree of the pulp for the kraft paper, the supply amount of the paper material, the conditions of the press part in the papermaking process, the conditions of the dryer part in the papermaking process, and the presence or absence and conditions of calendaring, and further, the coating amount and the presence or absence and conditions of calendaring for the coating layer. The density of the packaging paper can be reduced, for example, by low-beating the pulp, reducing the press pressure of the press part, reducing the drying strength of the dryer part, not performing calendaring, performing calendaring with a small number of nips, or performing calendaring with a lighter line pressure, and reducing the coating amount of the coating layer.

[0040] In some embodiments, the total coating weight, including the outermost coating layer of the wrapping paper, is 6 g / m2 in terms of dry solids. 2 More than 12g / m 2 In at least one embodiment, the total coating weight, including the outermost coating layer of the wrapping paper, is 6 g / m2 or less in terms of dry solids. 2 More than 12g / m 2 The reason for this is that printability in gravure printing is improved, resulting in improved print finish and improved reduction of dot misses. EXAMPLES

[0041] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. Here, "parts by mass" and "% by mass" represent the amount of dry solids or the amount of substantial components, respectively. The coating amount of the coating layer represents the amount of dry solids.

[0042] <Kraft paper> A pulp slurry consisting of 800 parts by mass of LBKP with a CSF freeness of 470 ml and 200 parts by mass of NBKP with a CSF freeness of 580 ml was mixed with 4 parts by mass of a rosin-based sizing agent, 12 parts by mass of a starch-based strength agent, 10 parts by mass of an aluminum sulfate fixing agent, and 0.1 parts by mass of an acrylamide-based retention agent to prepare a paper stock. The paper stock was made into a paper sheet using a fourdrinier paper machine. Both sides of the paper sheet were size-pressed with a size press liquid containing starch as a surface sizing agent, and then calendered using a machine calender to obtain kraft paper as the base material. The amount of surface sizing agent attached was 1 g / m per side. 2 The final density of the packaging paper was 0.97 to 0.99 g / cm 3 The supply amount of paper material, the conditions of the press part and the dryer part of the papermaking process, and the calendering conditions were set so that the density of the packaging paper was within the range of . The density of the packaging paper was measured in accordance with ISO534:2011.

[0043] <Coating liquid for the outermost coating layer> The coating solution for the outermost coating layer was prepared according to the following: White pigment (kaolin) Mass parts are listed in Table 1 White pigment (light calcium carbonate) Mass parts are listed in Table 1 White pigment (organic pigment) Type and mass part are listed in Table 1 Polyvinyl alcohol (saponification degree 98-99mol%, average polymerization degree 400) 1.2 parts by mass Styrene butadiene resin 11 parts by weight Surfactant (nonionic surfactant) Type and mass part are shown in Table 1 Surfactant (calcium stearate) parts by weight are listed in Table 1 The above ingredients were mixed and dispersed in water to adjust the concentration to 60% by mass.

[0044] The kaolin used in the coating liquid for the outermost coating layer was a mixture of kaolin with an average particle size of 1.22 μm and kaolin with an average particle size of 0.25 μm in a mass ratio of 1:1. The "hollow-cavity" listed in Table 1 is a hollow styrene-acrylic white organic pigment. The "solid pigment" listed in Table 1 is a solid type styrene acrylic white organic pigment. “AceG10” in Table 1 is a compound in which R1 and R4 are isobutyl groups, R2 and R3 are methyl groups, (OEorOP) is OE, and m+n is 10 in the above general formula (1). "AceG44" in Table 1 is a compound represented by the above general formula (1), in which R1 and R4 are isobutyl groups, R2 and R3 are methyl groups, (OEorOP) is OE, and m+n is 44. "POELa" in Table 1 is polyoxyethylene lauryl ether in the above general formula (1). In Table 1, "SteCa" is calcium stearate and "SteZn" is zinc stearate.

[0045] <Wrapping paper> The wrapping paper was prepared according to the following procedure. The coating solution for the outermost coating layer was applied to one side of the above kraft paper using a blade coater, and then dried. After drying, the paper was subjected to a calendaring treatment using a super calendar. The coating amount was 9 g / m per side. 2 It was decided.

[0046] The printability of each wrapping paper was evaluated for gravure printing in terms of "print finish" and "missed dots."

[0047] <Print finish> The finish was evaluated by printing on the outermost coating layer side of the packaging paper using Gravoproof CM (Nissho Gravure Co., Ltd.) using water-based gravure ink, and visually observing the resulting print. A gravure plate for image evaluation was used for the gravure printing. The evaluation was performed based on the impression of the printed image in terms of color density, color saturation, and color vividness as the print finish, using a print on a corona discharge-treated biaxially oriented polypropylene film as a comparison subject, and was performed according to the following criteria. In the present invention, a packaging paper that is rated A, B, or C is considered to have a print finish that is better than conventional ones. A: It doesn't make a bad impression compared to the comparison target. B: Although it is inferior to A above, the impression is not bad overall. C: Inferior to B above, the impression is slightly worse, but still within the acceptable level for practical use. D: Less impressive than C above.

[0048] <Miss Dot> Miss dots were printed on the outermost coating layer side of the packaging paper using Gravoproof CM (Nissho Gravure Co., Ltd.) using water-based gravure ink, and the resulting print was visually observed and evaluated. A halftone dot gravure plate was used for the gravure printing. The evaluation was made based on the observation results of the occurrence of miss dots (missing halftone dots) in the printed halftone, according to the following criteria. In the present invention, if the packaging paper is rated A or B, it is considered that the miss dots have been improved compared to conventional paper. A: Good condition with no missing dots. B: Inferior to A above, Although there are some very slight missing dots in some places, the condition is still close to good. C: Inferior to B above, Although there are some areas where dots are missing, the image is still usable. D: Inferior to C above, with missing dots observed.

[0049] The evaluation results are shown in Table 1.

[0050] [Table 1]

[0051] From Table 1, it can be seen that Examples 1 to 12, which correspond to the present invention, are wrapping papers with printability for gravure printing that is better than conventional ones, and with improved miss dots than conventional ones. On the other hand, it can be seen that Comparative Examples 1 to 6, which do not satisfy the configuration of the present invention, are unable to achieve the above-mentioned effects regarding printability for gravure printing, printability, and miss dots.

[0052] Mainly, by comparing Example 8 with Examples 11 and 12, it can be seen that by combining an acetylene glycol surfactant with a higher fatty acid salt in the outermost coating layer, the printability for gravure printing is improved, resulting in an improvement in the print finish.

Claims

1. A packaging paper comprising a kraft paper containing kraft pulp and one or more coating layers on at least one side of the kraft paper, the outermost coating layer being located outermost relative to the kraft paper and containing at least kaolin, a hollow white organic pigment, a binder and an acetylene glycol-based surfactant.

2. The packaging paper according to claim 1 , wherein the outermost coating layer further comprises a salt of a higher fatty acid.

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