JP4971852B2 - Coated paper for gravure printing - Google Patents

Description

The present invention relates to a coated paper for gravure printing, which has good dimensional stability, solvent resistance, and excellent gravure printing suitability in both oil and water.

  Conventional water-based gravure paper for building materials has no shrinkage of paper and wrinkles associated therewith, can prevent paper breakage, and has excellent acceptability of water-based ink and has a good appearance (for example, see Patent Document 1). .) This is a paper that is bonded to the surface of the plywood and is gravure-printed with water-based ink on the surface, and L-BKP: N-BKP = 75: 25 to 95: 5, freeness 200 mlcsf Over 300 mlcsf, sizing agent 20-40 kg / T, paper strength enhancer 185-220 kg / T, wet paper strength enhancer 35-45 / T, sulfuric acid band 44-55 kg / T The paper-making technique is described.

In addition, some coated papers have good smoothness and glossiness, and are excellent in printability with aqueous gravure ink (see, for example, Patent Document 2). This contained 20 to 80 parts by weight of kaolin having an average particle size of 1.0 to 2.0 μm and 80 to 20 parts by weight of cubic light calcium carbonate having an average primary particle size of 0.15 μm or less as a pigment component. Aqueous solution in which a coating liquid containing 0.2 to 0.7 parts by weight of a dispersing agent as an auxiliary agent and 10 to 15 parts by weight of a latex as an adhesive is applied to 100 parts by weight of a coating composition. A gravure coated paper having an absorption coefficient Ka of 0.23 ml / m ² · ms ^1/2 or more measured by using Bristow tester and distilled water as an evaluation liquid for the aqueous gravure printed paper A technical configuration is described.

Furthermore, there exists what is suitable for the gravure printing which uses water-based ink (for example, refer patent document 3). Here, in a coated paper for printing in which a pigment coated layer mainly composed of a pigment and an adhesive is provided on at least one side of a base paper, water absorption at a contact time of 25 milliseconds is a characteristic of the coated paper. The amount is 10 ml / m ² or less, the contact angle 0.1 seconds after water is dropped on the pigment coating layer of the coated paper is 75 degrees or less, and TAPPI Paper Pulp Test Method No. 5 describes a technical configuration in which the Oken air permeability described in 5 is 10,000 seconds or more.

  In addition, there is an excellent water-based gravure printing aptitude as a cast-coated paper for gravure printing, in particular, an ink drying property and an ink coloring property (for example, see Patent Document 4). This includes a cast-coated paper provided with a coating layer composed of a pigment, a water-soluble and / or water-dispersible adhesive as a main component, and a specific sedimentation volume occupying 100 parts by weight of the total pigment as a pigment is 1.20 ml / The ratio of the pigment which is g or more is 10 to 80 parts by weight, and contains at least 1 to 30 parts by weight of an aqueous urethane resin as a water-soluble and / or water-dispersible adhesive per 100 parts by weight of the pigment. A technical configuration is described in which a coating layer containing 1 to 25 parts by weight of a polymer per 100 parts by weight of pigment is provided and then cast finish is performed.

Furthermore, some gravure printing papers having excellent dimensional stability have excellent water-based gravure printing suitability (see, for example, Patent Document 5). Here, 20 to 100% by mass of engineered kaolin containing 20 to 60% by mass of polyolefin-based synthetic pulp in the base paper and 75% or more of the particle size of 2.0 μm or less in the coating solution is contained, The technical configuration to be applied is described.
Japanese Patent No. 3103631 JP 2004-043991 A JP 2003-201697 A Japanese Patent No. 2817643 Japanese Patent Application No. 2006-038006

In the conventional coated paper for gravure printing described above, the printing registration occurs due to elongation with respect to the solvent when the gravure printing is performed using the oil-based ink. Absorption could not eliminate the occurrence of paper breakage due to a decrease in wet strength.

  The object of the present invention is to solve the problems of the conventional technical configuration, and prevent the paper from stretching with respect to the solvent, and the paper absorbs water. It is to provide a coated paper for gravure printing which prevents paper breakage due to a decrease in ink and eliminates ink reception failure. In addition, the coated paper for gravure printing of this invention can fully be used not only as oily but also as a coated paper for aqueous gravure printing.

  As a result of intensive studies to solve the above-described problems, the present invention intends to solve the above-described problems by the following invention.

That is, in order to achieve the above-mentioned object, the present invention provides a Tg 40-50 ° C. resin mixture of polyester and acrylic resin (hereinafter referred to as “anti-resisting”) only on the opposite surface (back surface) of the gravure printing surface (front surface, printing surface). say solvents of the resin mixture.) the dry weight (hereinafter, sometimes to omit the dry weight.) as ^{5g / m 2 ~20g / m 2} , 8g / m 2 ~19g / m 2, particularly preferably 10g ^{/ m 2} ~18g ^/ m 2 coated with the further in order to prevent sticking of the front and back, based on the solvent resistance of the resin mixture, added was coated liquid calcium carbonate 5-100 wt% ( Hereinafter, it is abbreviated as “back coating liquid”. Further, the solution of the present invention has a particle size of 2.0 μm or less as a pigment component of a gravure coating liquid (hereinafter abbreviated as “surface coating liquid”) used on the surface of a gravure printing coated paper. The engineered kaolin contained at 75% or more is configured to contain 20 to 100% by mass based on the total pigment of the surface coating solution. Furthermore, as a means for solving the present invention, the JAPAN TAPPI paper pulp test method No. 1 for the coated paper for gravure printing is used. 27: 2000 "Paper and board - elongation in water Test Method" lateral growth in acetic acid n- butyl immersion due is obtained by below 1.0%. Furthermore, it is natural that the water-based gravure printing coated paper is calendered.

The action by the above problem solving means is in a coated paper that is gravure-printed using oil-based ink or water-based ink on the surface, and is coated with 5-20 / m ² of a solvent-resistant resin mixture on the back surface , Similarly, by applying a coating solution containing 5 to 100% by weight of calcium carbonate on the back surface based on the solvent-resistant resin mixture, the elongation of the oil-based gravure printing ink or the aqueous gravure printing ink due to the solvent is performed. Can be prevented. Furthermore, by applying a surface coating solution containing 20 to 100% by mass of engineered kaolin having a particle diameter of 2.0 μm or less of 75% or more on the surface, the surface smoothness is increased, and the oily, aqueous It can solve problems such as acceptability of gravure printing ink.

As described above, the gravure-coated coated paper of the present invention is obtained by applying 20 to 100% by mass of a surface coating solution of engineered kaolin having a particle size of 2.0 μm or less of 75% or more on the surface of a normal base paper. By coating 5-20 / m ² with a solvent-resistant resin mixture on the back side, the dimensional stability by the solvent is improved and the generation of wrinkles by water is eliminated. Can provide an excellent coated paper for gravure printing. In addition, by blending engineered kaolin with the coating liquid, smoothness is increased, printability with gravure ink is improved, and a coated paper for gravure printing having excellent printability can be provided.

The present invention provides a gravure printing coating comprising a regular base paper provided with a surface coating layer mainly composed of pigment, auxiliary agent and adhesive, and coated with a solvent-resistant resin mixture on the back surface and calendered. It is paper.

Solvents used in oil-based gravure printing inks are generally low-boiling organic oils having a boiling point of 60 to 150 ° C., such as aliphatic hydrocarbons such as normal hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; alcohols such as Methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, etc .; esters, such as acetate ester, butyl acetate, etc .; ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, etc., and used in aqueous gravure printing inks The solvent used is water, and the solvent-resistant resin mixture in the present invention means a resin having durability against these solvents. Of course, some resins are durable in both oil-based and water-based gravure printing inks, while others are effective only for oil-based and water-based gravure printing inks. The solvent resistant resin mixture is selected for each purpose. In both oil-based gravure printing inks and water-based gravure printing inks, there are various types of resins that are resistant to solvents. In the present invention, a resin mixture of polyester and acrylic resin is used to compare the glass transition point (Tg). to have high, Tg 40 to 50 ° C. of the resin is preferably used. For example, what is marketed under the brand name of pesresin from Takamatsu Yushi Co., Ltd. can be used. Of course, the present invention is not limited to this pesresin.

  As the wood pulp used for the base paper in the present invention, wood bleached chemical pulp represented mainly by N-BKP (coniferous bleached kraft pulp) is used. If necessary, wood bleached chemical pulp L-BKP (hardwood bleached kraft pulp), mechanical pulp such as GP (ground wood pulp), TMP (thermomechanical pulp), BCTMP (bleached chemithermomechanical pulp), and DIP (depleted) Ink waste paper pulp) can be appropriately blended.

  The production method of the base paper used in the present invention is not particularly specified, and those manufactured by a normal paper machine can be used, but from the standpoint of the Containers and Packaging Recycling Law, combined with the coating liquid, the wood pulp content rate It is desirable to make it 51% or more. Further, the blending ratio of the hardwood pulp and the conifer pulp is not particularly limited.

  In the base paper, in addition to the above-mentioned pulp, various yield improvers, paper strength improvers, internal sizing agents, pitch control agents, antifoams are generally used within a range that does not impair the object effects of the present invention. Chemicals such as an agent can be used as appropriate.

  The base paper is manufactured by a general paper machine such as a long net paper machine, a circular net paper machine, a Yankee paper machine, and a long net and circular net combination machine.

  The pigment used for the surface coating liquid of the present invention is a gravure coated paper having a flat surface by blending 20 to 100% by mass of engineered kaolin having a particle size of 2.0 μm or less and 75% or more. be able to.

  Latex can be used for the adhesive used for the surface coating solution of the present invention. The latex is a conjugated diene copolymer latex such as a styrene / butadiene copolymer, a methacrylate / butadiene copolymer, a vinyl polymer latex such as a polymer or copolymer of an acrylate ester and / or a methacrylate ester, Alternatively, these are further modified with a functional group-containing monomer such as a carboxyl group.

  In addition to the dispersant, auxiliary agents used for the front and back surface coating liquids of the present invention include lubricants, preservatives, antifoaming agents, water resistance agents, dyes, and the like, and these can be appropriately added.

  The calendering of the coated paper for gravure printing of the present invention is performed after forming the coated layer on the base paper, and is performed for the purpose of uniforming the paper thickness, improving the surface smoothness, and improving the glossiness. For the calendar process, a machine calendar arranged on-machine, a super calendar, a friction calendar, a gloss calendar, a brush calendar, a mat calendar, a soft calendar, and the like can be used. is not.

  The coating apparatus used for producing the coated paper for gravure printing of the present invention is not particularly limited, and for example, a roll coater, a blade coater, a rod coater, a bar coater, an air knife coater, a gravure coater or the like is used. Can do.

  Regarding the method for producing a coated paper for gravure printing of the present invention, the surface and back surface coating liquid may be applied to the base paper off-machine or the surface and back surface coating liquid may be applied to the base paper on-machine. From the viewpoint of production efficiency, it is preferable to perform on-machine.

[Action]
In the coated paper for gravure printing of the present invention, the JAPAN TAPPI paper pulp test method No. 27: 2000 “Paper and paperboard—Test method for elongation in water” is preferably one in which the lateral elongation of n-butyl acetate immersion is 1.0% or less. Those having a lateral elongation of more than 1.0% are not preferred because of problems such as printing duplication.

[Example]
The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, unless otherwise indicated, the part or addition% in an example is a mass part or mass% in conversion of solid content.

<Manufacture of base paper>
A pulp blended with L-BKP / N-BKP = 70/30% was mixed to obtain 450 ml of Canadian standard freeness (hereinafter abbreviated as “freeness”). Starlight PMC, AL-120) with 0.3% pulp, 1% sulfate band with pulp, 1% cationized starch (Nihon Food Chemical Co., Neotac 40T) with 1% pulp, and the stock Prepared. The said paper charge at a round net paper machine, paper making and paper 232 g / m ² by the paper making four layers having a basis weight of 58 g / m ² in each layer, at the size press, modified polyacrylamide resin as a surface paper strength agent (ST-5000, manufactured by Seiko PMC Co., Ltd.) was applied as a 2.5% size press solution on both sides at 40 ml / m ² and dried with a drier to produce a base paper of the present invention.

<Formation of surface (printing surface) of coated paper for gravure printing>
The surface coating solution shown below was applied to the surface of the base paper by an air knife coater installed in the round net paper machine without applying the size press liquid shown above and winding the dried base paper once. m ² (solid content) was coated and dried to form the surface (printing surface) of the coated paper for gravure printing of the present invention.

<Manufacture of surface coating solution>
A dispersant (San Nopco, SN5034) is added to water in an amount of 0.1% with respect to the pigment, and 100 parts of engineered kaolin (Imeris Minerals Japan, Capim NP) is added at a concentration of 68% with a cowless disperser. A pigment slurry was prepared. Add additional water to this pigment slurry, put 7.5 parts of SBR latex (Asahi Kasei Co., Ltd., G-1578), 0.2 part of caustic soda and 27% starch solution (manufactured by Nippon Food Processing Co., Ltd., MS-4600). 0.0 part, 1.9 parts of a lubricant (manufactured by Sannopco, NH-237) and 0.1 part of a water retention agent (manufactured by Somar, Somalex 300) are added to obtain a surface coating solution having a solid content of 63%. It was.

<Formation of the back side (non-printed side) of coated paper for gravure printing>
After forming the 15 g / m 2 by an air knife coater to the surface shown in the above ^(solids) Nurihi dried surface (printing surface), 15 g backside coated liquid in the following by an air knife coater on the back surface of the paper / M ² (solid content) was coated and dried to form the back surface (non-printed surface) of the coated paper for gravure printing of the present invention.

<Manufacture of coated paper for gravure printing>
After forming the back surface (non-printing surface), an on-machine calendar process was performed to produce a coated paper for gravure printing of the present invention.

<Manufacture of backside coating solution>
Solvent resistant resin mixture (Takamatsu Oil & Fat Co., PESRESIN A-615GE, Tg = 47) with respect to, 30 weight percent calcium carbonate (Shiraishi Kogyo Co., PZ) placed and form conditioned at Cowles disperser. A 0.2% antifoaming agent (manufactured by Takamatsu Yushi Co., Ltd., CS-703) was added to the liquid and mixed to obtain a back coating solution.

The present invention will be described in more detail with reference to examples.
In addition, the smoothness, the underwater elongation, and the gravure printability in the examples were evaluated based on the following contents.

(Smoothness)
The smoothness of the coated surface was measured according to JIS P 8119: 1998 “Paper and paperboard—Smoothness test method using Beck smoothness tester”.

(Solvent elongation)
JAPAN TAPPI Paper Pulp Test Method No. 27: 2000 "Paper and paperboard-Underwater elongation test method", a lateral test piece having a width of 15 mm and a length of 150 mm was immersed in n-butyl acetate at 23 ° C for 5 minutes using a Fenchel stretch tester. The elongation was expressed in%.

(Underwater elongation)
JAPAN TAPPI Paper Pulp Test Method No. 27: 2000 According to the B method according to “Paper and paperboard—extensibility test in water”, a horizontal test piece having a width of 15 mm and a length of 150 mm was immersed in water at 23 ° C. for 5 minutes using a Fenchel stretch tester. The elongation was expressed in%.

(Suitability for gravure printing)
Water-based ink (Toyo Ink Co., Ltd., AQUAPLUS F15) and oil-based ink (printed by Toyo Ink Co., Ltd.) under conditions of a printing speed of 60 m / min, a printing pressure of 100 kg / cm ² , and a blade pressure of 2 kg / cm ² using a PM-9004GP OGH91) manufactured by Toyo Ink Co., Ltd. was printed, and the dot missing rate on the surface of the obtained printed matter was counted by counting the number of missing dots in 4557 dots of 10% halftone gravure, and the missing rate was displayed in%.

(Blocking property)
The front and back surfaces of four 5 cm × 5 cm samples were overlapped, 10 kg weights were placed on each sample, and after standing in a dryer at 40 ° C. for 12 hours, the attachment of the front and back surfaces was judged and evaluated according to the following conditions.
○: The front and back are not attached at all, and there is no practical problem.
Δ: Some sticking, but without peeling, there is a problem in practical use.
X: The front and back are completely adhered and peeled off, which causes a practical problem.

(Example 2)
The gravure printing coating of the present invention was carried out in the same manner as in Example 1 except that the coating solution containing 50% by mass of calcium carbonate was used for the solvent-resistant resin mixture of the backside coating solution of Example 1. A paper was obtained.

(Example 3)
The gravure printing coating of the present invention was carried out in the same manner as in Example 1 except that the coating solution containing 100% by mass of calcium carbonate was used for the solvent-resistant resin mixture of the backside coating solution of Example 1. A paper was obtained.

(Comparative Example 1)
A coated paper for gravure printing was obtained in the same manner as in Example 1 except that the back surface of Example 1 was coated with a surface coating solution instead of the back surface coating solution.

(Comparative Example 2)
Acrylic resin (Johnson Polymer Co., J-450) instead of the back surface coated liquid solvent resistant resin mixture in Example 1 except for using, in the same manner as in Example 1, a gravure printing coated paper Obtained.

(Comparative Example 3)
Example 1 styrene-butadiene + wax in place of solvent resistant resin mixture of the back coated liquid (DIC Co., HB-527) except for using, in the same manner as in Example 1, for gravure printing coated paper Got.

(Comparative Example 4)
Against solvent resistant resin mixture of the back coated liquid of Example 1, except that the rear surface coated liquid was blended for 110 wt% of calcium carbonate, in the same manner as in Example 1, for gravure printing coated paper Got.

As can be seen from Table 1, in the case of Example 1 coated with the back surface coating solution of the present invention, the lateral elongation was slight with respect to the water of the gravure printing solvent and n-butyl acetate. This is clearly superior to Comparative Examples 1 to 3 in which the solvent-resistant resin mixture of the present invention is not coated. In the case of Comparative Example 2 using an acrylic resin instead of the solvent-resistant resin mixture and Comparative Example 3 using styrene butadiene + wax, the transverse elongation in the liquid is comparable to Example 1 of the present invention. It can be seen that the blocking property is remarkable and cannot be practically used. It can be seen that by using the solvent-resistant resin mixture of the present invention, not only the elongation in liquid is improved, but also the blocking property is improved.

Based on the solvent-resistant resin mixture, Examples 2 and 3 using the back coating solution added with 50% by mass and 100% by mass (5 to 100% by mass) of calcium carbonate and 110% by mass of calcium carbonate were added. When compared with Comparative Example 4 using a coating solution, the blocking evaluation is good in Comparative Example 4 as well as in Examples 2 and 3, but it is bad when the elongation in liquid is particularly n-butyl acetate. . Therefore, it turns out that it is advantageous that the quantity of the calcium carbonate in a back surface coating liquid is 5-100 mass%.

Claims (4)

In a coated paper for gravure printing, a resin mixture of polyester and acrylic resin having a Tg of 40 to 50 ° C. (hereinafter referred to as a solvent-resistant resin mixture) only on the back surface of the coated paper is 5 g / dry weight . It is coated with m ^{2 to 20} g / m ² , and is similarly coated with a coating solution containing 5 to 100% by weight of calcium carbonate on the back surface based on the solvent-resistant resin mixture. Coated paper for gravure printing. As a coating solution used on the surface of the coated paper for gravure printing, engineered kaolin having a particle size of 75% or more of 2.0 μm or less in the pigment composition of the coating solution is used with reference to all pigments of the coating solution. gravure coated paper for printing according to claim 1, characterized in that it comprises 20 to 100 wt%. In the coated paper for gravure printing, the Japan TAPPI paper pulp test method No. The coated paper for gravure printing according to claim 1 or 2 , wherein the lateral elongation when immersed in n-butyl acetate according to No. 27 is 1.0% or less. In the coated paper for gravure printing, the Japan TAPPI paper pulp test method No. Water elongation in longitudinal 0.3% by 27 and claim 1, 2 or 3 for gravure printing coated paper, wherein a is greater than the horizontal 1.0%.