JP2000153668A - Recording sheet for electrocoagulation printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recording sheet suitable for electrocoagulation printing without missing the emboss feeling or material feeling of the original sheet by forming protrusions and recesses previously on the original sheet and proving a coating layer principally comprising a filler and an adhesive having high transparency. SOLUTION: A tube 1 serving as an anode electrode is formed of an electrically inactive metal, e.g. stainless steel, and independent cathodes are arranged on a tubular box 2 while being insulated from the tube 1. The gap between both electrodes 1, 2 is filled with ink sprayed from an ink spray 3 and a coagulation colloidal part supported on the circumferential surface of a press roll 5 is transferred to a recording sheet 6 being fed between the anode 1 and the press roll 5. When the recording sheet 6 for electrocoagulation printing is formed by providing a coating layer principally comprising a filler and an adhesive having high transparency onto an original sheet previously formed with protrusions and recesses, material feeling of the original sheet is not missed in electrocoagulation printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet having an embossed feeling and a material feeling of paper and suitable for electrocoagulation printing.

[0002]

2. Description of the Related Art The electrocoagulation printing method is disclosed in U.S. Pat. Nos. 3,892,645, 4,555,320, 4,764,264, and Japanese Patent Application Laid-Open No. 4-504688. It is disclosed, and the ink used for this is a water-based ink. Its composition consists of water, an electrolytically coagulating polymer, a soluble electrolyte and a colorant. The electrolytically coagulable polymer is, for example, albumin, gelatin, casein, agar, polyacrylic acid, polyacrylamide, polyvinyl alcohol and the like, and the soluble electrolyte is, for example, lithium chloride, sodium chloride, calcium chloride, Potassium chloride, nickel chloride, copper chloride, magnesium sulfate and the like.

The basic mechanism of the electrocoagulation printing method is as follows. When a potential difference is generated between the electrodes while the ink layer having the above composition is sandwiched between the positive and negative electrodes, coagulation of the colloid and adhesion of the coagulated colloid to the anode occur. This coagulation is a color coagulation that occurs in a state where the colorant in the ink is contained. By appropriately arranging the color coagulation colloid, an arbitrary image can be reproduced, and the reproduced image is transferred to a recording sheet by any method. This makes it possible to record an arbitrary image on a recording sheet.

[0004] The construction of a printing machine utilizing the electrocoagulation printing method is described in detail in the above-cited Japanese Patent Publication No. 4-504688, but will be briefly described with reference to FIG. FIG.
Schematically shows the configuration of a printing machine that forms a one-color image and transfers it to a recording sheet. In the case of multi-color printing,
One printing press is configured by connecting a plurality of similar devices. In FIG. 1, reference numeral 1 denotes a metal cylinder serving as a positive electrode, and is made of, for example, an electrically inactive metal such as stainless steel. Insulated from the anode 1 and independent cathodes are arranged on the cylindrical box 2, respectively.
The ink ejected from the ink ejector 3 fills between the two electrodes. The anode 1 rotates continuously in the clockwise direction in the drawing, and intermittently generates a potential difference between the anode 1 and the cathode 2, thereby forming a coagulated colloid portion and a non-coagulated ink portion in the ink filling between the two electrodes. The coagulated colloid adheres to the anode 1,
Only the non-coagulated ink is selectively removed from above the anode with a wiper or the like indicated by.

[0005] A press roll 5 is pressed against the anode 1, and a recording sheet 6 is fed between the two. Therefore, the solidified colloid part supported on the peripheral surface of the press roll 5 reaches the position of the press roll 5 with the rotation of the anode 1 and is transferred onto the recording sheet 6 in contact. At this time, the nip pressure between the press roll 5 and the anode 1 is 30 to 50 kg /
cm. The anode 1 after the transfer is further rotated to be cleaned by the cleaning device 7 while being further rotated, and then the corrosion inhibitor is applied by the corrosion inhibitor coating device 8 to complete one cycle.

[0006] This printing method is replaced by a conventional printing method, for example,
A major difference compared with offset printing, letterpress printing, screen printing, gravure printing, and the like is that the electrocoagulation printing method falls in the category of so-called “plateless printing”. Although the advantages of "plateless printing" are many, the step of raising the plate is indispensable in the conventional printing method, and the ratio of the plate making cost to the cost per printed material is extremely large. Since "printing" does not require a plate making process, plate making costs are not required, and in the case of conventional "printing with a plate", printing is performed at high speed while printing the same printed material, but is switched to a different printing unit (exchanging a plate). In contrast, "plateless printing" requires reading data sent from a computer every time and printing, so the preparation time for printing different printed materials is extremely short. Can be As a result, it can be said that the electrocoagulation printing method is an overwhelmingly advantageous printing method as compared with the conventional method, especially in the printing of small lots.

[0007] Further, it is impossible with a conventional printing method that, for example, a common body of direct mail is printed at the same time as printing different addresses, while hardly any preparation time is required for printing different printed materials. To the so-called page variable.

Further, a printing machine using the electrocoagulation printing method is
The printing press consists of a relatively simple combination of sturdy components, and can easily be adapted to high speeds. The upper limit of the printing speed is determined by the information transmission speed from the computer rather than the printing press itself. Even at the current computer level, a speed of several hundred m / min is a sufficiently high figure, and is considerably faster than other "plateless printing" such as an ink jet method which has been rapidly progressing in recent years, and the productivity is high. high.

As the coloring agent used in the electrocoagulation printing method, the same coloring agent used in the ink of the conventional printing method can be used, and the shape and size of the aggregated colloid are determined by the size of the cathode (tip of the wire). The shape and size are almost the same, and the dot gain on the recording sheet cannot be considered. Therefore, clear image reproduction by fine and sharp dots is possible.

[0010] As described above, the electrocoagulation printing method is an excellent printing method which has high productivity and high image quality comparable to the conventional printing method, and also supports small lots and page variable properties which cannot be achieved by the conventional method. It can be said that there is.

The present inventors have proposed a recording sheet suitable for the above-mentioned electrocoagulation printing in Japanese Patent Application Laid-Open No. Hei 10-131091,
Wetting time (millisecond), absorption coefficient (ml / m ² s ^-1/2 ) determined from the absorption curve in pure water by a dynamic scanning absorptiometer, and pressure of 40 kg / cm ^{2 by} a specular reflection type smoothness meter It has been disclosed that three physical properties of the contact ratio (%) when measured with a light beam having an applied wavelength of 0.5 μm are important. Furthermore, Japanese Patent Application No. 1
0-62311, Japanese Patent Application No. Hei 10-36212, and a recording sheet for electrocoagulation printing suitable for high-grade printing,
It is disclosed that the Beck smoothness (second) specified in JIS P 8119 in the surface coating layer is also important.

On the other hand, there is a demand for a recording sheet for electrocoagulation printing having an embossed design and a design property, but such a recording sheet has not been proposed yet.

Therefore, an attempt has been made to use as-is a recording sheet for electrocoagulation printing, as is, a paper having irregularities, such as existing embossed design paper, but at present it is not possible to obtain a satisfactory ink color density. Was. This is because the time when the ink composed of the coagulated colloid is transferred from the positive electrode to the recording sheet, i.e., the time when the recording sheet is sandwiched between the press roll and the positive electrode, Is not sufficiently absorbed by the recording sheet, and a certain amount of water in the ink composed of the coagulated colloid is not sufficiently absorbed by the recording sheet. It is presumed that the ink transfer rate was low.

On the other hand, an ordinary papermaking pigment is applied to a paper having irregularities, such as an existing embossed design paper, and is intended to be used as a recording sheet. However, due to the whiteness and opacity of the pigment, The coating layer becomes white and the appearance is significantly different from the embossed design paper before coating.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording sheet suitable for electrocoagulation printing without losing the embossing feeling or material feeling of the base paper.
That is, an object of the present invention is to provide a recording sheet suitable for electrocoagulation printing having an embossed feeling and a paper material feeling.

[0015]

As a result of the study by the present inventors, the base paper is provided with irregularities in advance, and the base paper is provided with a coating layer mainly containing a specific filler and an adhesive having high transparency. The present inventors have found that a recording sheet suitable for electrocoagulation printing can be obtained without losing the embossing feeling or material feeling of the base paper, and completed the present invention.

That is, the recording sheet for electrocoagulation printing of the present invention comprises a coating layer containing a filler and an adhesive as main components.
It is characterized in that it is provided on a base paper on which irregularities are formed in advance.

The center line average roughness specified in JIS _B0601-1982 of the irregularities is preferably 2 μm or more and 6 μm or less. The filler used is preferably one or more of synthetic amorphous silica, alumina sol, silica sol and plastic pigment.

The ink receiving layer thus formed has a wetting time of 30 milliseconds or less and an absorption coefficient of 5 ml / m ² , which is determined from an absorption curve of pure water by a dynamic scanning absorptiometer.
s ^-1/2 or more, the contact ratio when measured by ray specular-type smoothness meter wavelength 0.5μm under a pressure of 40 kg / cm ² with of 25% or more, good ink color density It is preferable to

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The base paper having irregularities formed in advance used in the present invention can be of various types depending on the use and purpose of the product, and is not particularly limited. For example, paper with rough skin having low smoothness, paper with felt marks or emboss marks can be used. These can be manufactured by forming irregularities on a paper machine with a dandy roll or blanket. Further, it can be manufactured by pressing the paper on a paper machine or using an embossing machine with an engraving roll or a mold roll to form irregularities.

On the other hand, a sheet made of a material other than wood pulp fibers, such as a film having an emboss mark or a color, a synthetic fiber paper, a synthetic pulp paper, or the like can be used. Further, resin-coated paper coated with an acrylic emulsion or the like to give an emboss mark or color may be used as the base paper.

JIS B0601 for unevenness of the base paper
_The center line average roughness specified in _-1982 is 2μm or more and 6μ
When it is less than m, a design emboss and paper texture are exhibited. If the center line average roughness is larger than 6 μm, the surface roughness of the printed paper becomes conspicuous, and the use as printing paper is reduced. Further, the transfer rate of the ink composed of the coagulated colloid is deteriorated, and the suitability as printing paper is impaired. On the other hand, when the average roughness is less than 2 μm, the emboss feeling and the material feeling are impaired.

The paper used as the base paper of the present invention is a papermaking fiber having a freeness of 250 to 700 ml. S. F.
(Canadian standard freeness), and the paper is formed by a conventional method using a known paper machine such as a round paper machine or a fourdrinier paper machine. In addition, one or more kinds of inorganic fibers such as glass fiber, rock wool, silica / alumina silicate fiber, alumina fiber, zirconia fiber, calcium titanate fiber and the like can be appropriately used in a range not to impair the purpose.

The fibers used for papermaking include softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), and hardwood unbleached kraft pulp (LUKP).
P), bleached hardwood kraft pulp (LBKP), softwood sulfite pulp (NBSP), thermomechanical pulp (TMP), wood pulp such as groundwood pulp (GP), or hemp, bamboo, straw, kenaf, mulberry, mitsumata, ganpi , Non-wood pulp such as cotton, synthetic pulp such as polyolefin, synthetic fiber such as rayon, vinylon, nylon, polyester, etc., and singly or mixed materials such as deinked pulp (DIP).

When the paper of the present invention is made, various fillers for papermaking, fixing agents, retention improvers, dry paper strength enhancers, wet paper strength enhancers are used, if necessary, as long as the desired performance is not impaired. ,
A binder, a dispersant, a flocculant, a plasticizer, and an adhesive may be appropriately used.

[0025] The paper of the present invention may be a round paper machine, a fourdrinier paper machine,
The paper is usually formed at a basis weight of 40 to 200 g / m ² using an inclined paper machine, a twin wire paper machine or the like. Further, a size press treatment may be performed as needed.

The film used as the base paper of the present invention includes an organic resin such as viscose, acetate, polyethylene, polypropylene, polyvinyl chloride, polystyrene, nylon, polyacetal, polycarbonate and polyethylene terephthalate, if necessary. It is a sheet-like material obtained by adding a filler or a chemical and thinning by a known method such as a melt extrusion method, a calendar method, a stretching method, and a melt casting method, and so-called synthetic paper also falls into this category.

The non-woven fabric used as the base paper of the present invention includes wood fibers, cotton, rayon, polyethylene terephthalate, acrylic, acetate, nylon, polypropylene and other fibers as raw materials, spunbonding, papermaking, carding machines and garnets. It is formed into a sheet by a known method such as a dry method using a machine.

The base paper of the present invention can be produced by forming irregularities on a paper machine using a dandy roll or blanket. In addition, it can be produced by forming an unevenness by pressing on a paper machine or using an embossing machine using an engraving roll or a mold roll.

In the coating layer of the present invention, kaolin, light calcium carbonate, titanium oxide, synthetic amorphous silica, silica sol, alumina sol, aluminum hydroxide, plastic pigment, and the like can be used as fillers. In order to obtain a high ink color density without losing the texture or texture, a material having high transparency and a large amount of water absorption is preferable, and synthetic amorphous silica, alumina sol, silica sol, and plastic pigment are preferably used.

In the case where synthetic amorphous silica is used, if the aggregated particle system is 1 μm or less, the transparency is high, so that a high ink color density can be obtained without impairing the emboss feeling or material feeling of the base paper. Such a synthetic amorphous silica can be obtained by, for example, wet-milling ordinary synthetic amorphous silica obtained by neutralizing sodium silicate.

In the case of using an alumina sol, in particular, if a boehmite or pseudo-boehmite structure is used, the ink formed of the coagulated colloid has high absorbency, so that it is excellent in the color density, dot reproducibility, and gradation expression of the image, and further high. Transparency is also obtained.

The silica sol used in the present invention refers to colloidal silica or a combination thereof. In the present invention, it is particularly preferable that the spherical colloidal silica be linked to have a long chain bead shape, or that these have a branched shape, a bent shape, or a pearl necklace shape. As a more preferred shape, spherical colloidal silica having a particle size of 10 to 50 nm is 50
One having a pearl necklace having a length of 400 nm can be used. When such a silica sol is used, the emboss feeling and material feeling of the base paper are not lost, and the dot reproducibility, gradation expression and color density of an image are excellent.

These silica sols are described, for example, in Patent No. 2
It can be manufactured by the methods disclosed in JP-A-803134 and JP-A-7-118008. That is, primary particles of spherical colloidal silica are connected between particles by interposing polyvalent metal ions, and at least 3 or more, preferably 5 or more are connected, and the connected colloidal silica particles are branched. Includes broken, bent, and pearl necklace-shaped ones. Examples of polyvalent metal ions to be interposed include Ca, Sr, and B as divalent ones.
a, Zn, Sn, Pb, Cu, Fe, Ni, Co, Mn
And trivalent ones such as Al, Fe, Cr, Y, Ti
And tetravalent compounds such as Ti, Zr, and Sn.

The plastic pigment which can be used in the present invention is mainly composed of a synthetic resin, for example, acrylonitrile-butadiene-styrene copolymer, styrene-acrylonitrile copolymer, polypropylene resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, vinyl Copolymers, urea formalin resins, and the like can be used, and commercially available products can be used. In order not to lose the embossing feeling and the material feeling of the base paper, those having high transparency are preferably used.

As the shape and properties, various shapes and properties such as a sphere, a flat shape, a hollow shape, a fine particle aggregate, a binder pigment and the like can be used. It is effective and preferable.
The particle size is preferably 2 μm or less.

The plastic pigment is rich in elasticity, easily deformed easily, has good restoring force after pressure release, and has high cushioning properties. For this reason, when the ink composed of the coagulated colloid is pressure-transferred to the recording sheet, it is presumed that a high smoothness of the recording sheet is obtained, a high ink transfer rate, and a high ink color density of an image are obtained.

The above fillers may be used alone or in combination of two or more.

When the coating layer is provided in the present invention, the above filler and the adhesive are used in combination.

Known adhesives can be used, for example, polyvinyl alcohol and modified products thereof, starch and modified products thereof, casein, NR, SBR, NBR, acrylic resins, urethane resins, polyester resins, ultrafine An aqueous dispersion of binder particles composited with a filler can be used alone or as a mixture or copolymer of two or more.

Among the adhesives used in the present invention, the aqueous dispersion of binder particles composited with ultrafine fillers refers to colloidal silica, alumina sol or the like as ultrafine particles, and acrylic binder as the binder. Emulsions, silane group-added olefin polymerization emulsions, polyvinyl alcohol, modified polyvinyl alcohol, ethylene-vinyl acetate copolymer emulsions and the like can be used. A particularly preferred embodiment is an aqueous dispersion of acrylic polymer emulsion particles having a particle size of 30 to 70 μm, which are composited with ultrafine colloidal silica.

As a method for producing an aqueous dispersion of the acrylic emulsion particles, for example, JP-B 8-193
There is a method described in No. 11. That is, the degree of polymerization 15
In the presence of an emulsifier consisting of polyvinyl alcohol having a particle diameter of 0.1 μm or less, an emulsion of acrylic polymer particles having a particle diameter of several μm or less obtained by emulsion polymerization of an acrylic ester and / or a methacrylic ester is used.
The following aqueous dispersion of colloidal silica particles was added and uniformly stirred and mixed, and the acrylic polymer particles and colloidal silica particles were combined to form a particle size of 30 to 70 μm.
An aqueous dispersion containing the acrylic polymer composite particles is obtained.

The above-mentioned adhesive is used in an amount of 3 to 60 parts by weight based on 100 parts by weight of the filler. If the amount is less than 3 parts by weight, the strength of the surface coating layer is not sufficient, causing troubles such as destruction of the surface coating layer during contact transfer of the ink. If the amount exceeds 60 parts by weight, the transfer rate of the ink is deteriorated.

However, when an aqueous dispersion of binder particles composited with an ultrafine filler is used as an adhesive, it must be used alone without being used in combination with a filler, since it contains the filler itself. Is also possible.

In the present invention, a water retention agent, a cross-linking agent, a curing agent, a defoaming agent, a thickener, a water-proofing agent, a lubricant, a coloring agent may be added, if necessary, to a coating solution for forming a coating layer. And the like.

The coating amount of the coating layer is sufficient if it is 0.5 g / m ² or more, but 2 g / m ² or more in order to obtain excellent image color density and excellent image gradation expression. Preferably, there is.

In preparing the coating solution, a stirrer such as various mixers, kneaders, ball mills and the like can be appropriately used according to the composition of the coating solution.

The coating layer can be provided on both sides or one side of the base paper.
Various known coating apparatuses such as a gravure coater, a blade coater, a roll coater, a gate roll coater, a bar coater, a curtain coater, a size press coater, and a bill blade coater can be appropriately used.
In particular, an air knife coater is suitable as a means for applying a uniform coating layer on the entire surface of the unevenness while substantially maintaining the shape of the unevenness of the base paper.

The recording sheet for electrocoagulation printing obtained in the present invention has a wetting time of 30 milliseconds or less and an absorption coefficient of 5 ml / min, as determined from an absorption curve of pure water by a dynamic scanning absorptiometer.
The contact ratio is preferably at least 25% when measured with a light having a wavelength of 0.5 μm by applying a pressure of 40 kg / cm ² with a specular reflection smoothness meter at m ² s ^−1/2 or more.

[0049] The present inventors have wetting time t ₀ and the absorption coefficient K _a of Bristow plot is the transfer rate to the recording sheet of the ink consisting of coagulated colloid, it grabbed the importance absorbent. The dynamic scanning absorptiometer has the measurement principle of JAPAN
TAPPI No. 51-87 (Bristow method) and higher measurement accuracy than the Bristow method. In a recording sheet whose wetting time exceeds 30 milliseconds or whose absorption coefficient is less than 5 ml / m ² s ^-1/2 , liquid absorption occurs within the time between the press roll and the positive electrode. The transferability of the ink composed of the coagulated colloid to the recording sheet is not improved because it is not present or occurs in an insufficient amount.

On the other hand, a press roll 5 is pressed onto the anode 1 of the electrocoagulation printing machine shown in FIG. 1, and a recording sheet 6 is fed between the two. The solidified colloid part supported on the peripheral surface of the press roll 5 reaches the position of the press roll 5 with the rotation of the anode 1 and is contact-transferred onto the recording sheet 6. At this time, the nip pressure between the press roll 5 and the anode 1 is 30 to 50 kg / cm. In order to transfer the ink composed of the coagulated colloid onto the recording sheet at a high transfer rate, the inventors of the present invention have studied. As a result, a pressure of 40 kg / cm ² was applied by a specular reflection type smoothness meter and a light beam having a wavelength of 0.5 μm. It was found that the contact ratio as measured by the above was preferably 25%. A specular reflection type smoothness meter is a device that measures the degree of smoothness when pressurized by an optical method.The specular reflection when a glass surface and a sample surface are brought into pressure contact with each other and oblique light at a specific angle is irradiated from the glass surface. It is to measure the smoothness of the sample during pressurization from the amount.

In order to satisfy the above-mentioned contact ratio measured by a specular reflection type smoothness meter, for example, it is preferable that the base paper has flexibility and cushioning properties, and the raw materials are DIP, TMP, G
P, esparto pulp, linter pulp, cotton pulp, crimp pulp and the like are suitable. By making the configuration of the base paper as described above, JIS B06
_Even with embossed paper having a center line average roughness of 2 μm or more and 6 μm or less specified in _01-1982 , ink composed of coagulated colloid is transferred to a recording sheet at a high transfer rate, and as a result, a high ink color density is obtained. Can be

The printed matter obtained by subjecting the thus obtained recording sheet to electrocoagulation printing has a feeling of embossing and paper, so that commercial art prints such as posters, calendars and pamphlets, visual magazines, photo books, It can be suitably used for printed publications such as art books, paper containers for pharmaceuticals and cosmetics, and printed packaging materials such as shopping bags and labels.

[0053]

Examples of the present invention will be described below. “Parts by weight” in the examples indicates a solid content conversion amount.

Example 1 100 parts by weight of boehmite (trade name "Alumina Sol-520", manufactured by Nissan Chemical Industries, Ltd.) and 20 parts by weight of polyvinyl alcohol (trade name "PVA-110", manufactured by Kuraray Co., Ltd.) A coating solution having a concentration of 16% was prepared. This coating solution was applied to a felt-marked base paper having a basis weight of 108 g / m ² , a density of 0.65 g / cm ³ , and a center line average roughness of 2.7 μm, which was obtained by forming a blanket in a press section during papermaking. Coating was performed using an air knife coater so that the coating amount was 5 g / m ² to obtain a recording sheet.

Example 2 100 parts by weight of silica sol (trade name "Snowtex PS-M", manufactured by Nissan Chemical Industries, Ltd.) in which colloidal silica was chained in a pearl necklace, and polyvinyl alcohol (trade name "PVA-110") A coating solution having a concentration of 16%, consisting of 10 parts by weight of Kuraray Co., Ltd., was prepared. This coating solution was applied to a felt-marked base paper having a basis weight of 108 g / m ² , a density of 0.65 g / cm ³ , and a center line average roughness of 2.7 μm, which was obtained by forming a blanket in a press section during papermaking. Coating was performed using an air knife coater so that the coating amount was 5 g / m ² to obtain a recording sheet.

Example 3 A plastic pigment (trade name "Grossdale 840")
-L ", 100 parts by weight of Mitsui Chemicals, Inc., 5 parts by weight of phosphorylated ester (trade name" MS # 4600 ", manufactured by Japan Food Processing Co., Ltd.), and styrene-butadiene latex (trade name" Polylac ") 750 "(manufactured by Nippon A & L Co., Ltd.) in a weight ratio of 20%. This coating liquid was applied to a blanket in a press section during papermaking to obtain a basis weight of 108 g / m ² and a density of 0.65 g.
/ Cm ³ , a center line average roughness of 2.7 μm, and a coating amount of 5 g /
m ² to obtain a recording sheet.

Example 4 100 parts by weight of pseudo-boehmite (prepared by hydrolyzing aluminum isopropoxide, adding nitric acid and treating with an ultrasonic homogenizer) and polyvinyl alcohol (trade name “PVA-110”, Kuraray) A 16% concentration coating liquid consisting of 20 parts by weight was prepared. Using an air knife coater, this coating solution was applied to base paper having a basis weight of 108 g / m ² , a density of 0.70 g / cm ³ , and a center line average roughness of 3.8 μm, which was obtained by applying a mold with an engraving roll during papermaking. The coating was performed so that the coating amount was 5 g / m ² to obtain a recording sheet.

Example 5 An adhesive composed of an aqueous dispersion of a polyacrylate emulsion composited with colloidal silica (trade name "Movinyl 1430", Clariant Polymer Co., Ltd.)
Co., Ltd.) and 100 parts by weight of a plastic pigment (trade name "Grossdale 840-L", manufactured by Mitsui Chemicals, Inc.) were prepared at a concentration of 20%. This coating solution was applied to a felt-marked base paper having a basis weight of 108 g / m ² , a density of 0.65 g / cm ³ , and a center line average roughness of 2.7 μm, which was obtained by forming a blanket in a press section during papermaking. Coating was performed using an air knife coater so that the coating amount was 5 g / m ² to obtain a recording sheet.

Example 6 An adhesive composed of an aqueous dispersion of a styrene / acrylic copolymer emulsion complexed with colloidal silica (trade name "LX-623C3", Clariant Polymer Co., Ltd.)
Of a blanket obtained by applying a blanket in a press section at the time of papermaking to obtain a basis weight of 108 g / m ² , a density of 0.65 g / cm ³ , and a center line average roughness of 2.7 μm. The felt-marked base paper was coated using an air knife coater to a coating amount of 5 g / m ² to obtain a recording sheet.

Example 7 100 parts by weight of colloidal silica (trade name "Snowtex OL", manufactured by Nissan Chemical Industries, Ltd.) and polyvinyl alcohol (trade name "PVA-110", manufactured by Kuraray Co., Ltd.) 1
A coating solution of 0% by weight with a concentration of 16% was prepared. An air knife coater is used to apply this coating liquid to an embossed base paper having a basis weight of 108 g / m ² , a density of 0.65 g / cm ³ , and a center line average roughness of 2.7 μm, which is obtained by applying an embossing machine after paper making. Was used to give a coating amount of 5 g / m ² to obtain a recording sheet.

Example 8 Kaolin (trade name “ULTRA WHITE 90”,
39 parts by weight of titanium oxide (trade name "Taipaek R-820", manufactured by Ishihara Sangyo Co., Ltd.)
10 parts by weight, esterified starch (trade name “MS-46”
00 ", manufactured by Japan Food Processing Co., Ltd.) 2 parts by weight, styrene-
Butadiene copolymer latex (trade name “Polylac 7
50 ", manufactured by Mitsui Chemicals, Inc.) and 47 parts by weight of red disperse dye (CI Disperse Red 146)
A coating solution consisting of 2 parts by weight was coated on a high-quality paper base paper using a Meyer bar so that the coating amount per side was 8 g / m ² , dried with hot air, embossed, and then centered. A resin-coated paper having an average roughness of 3.0 μm was obtained. Next, 100 parts by weight of pseudoboehmite (prepared by hydrolyzing aluminum isopropoxide, adding nitric acid and treating with an ultrasonic homogenizer) and polyvinyl alcohol (trade name “PVA-110”, manufactured by Kuraray Co., Ltd.) ) A 16% concentration coating solution consisting of 10 parts by weight was prepared. This coating liquid was applied using the resin-coated paper obtained above as a base paper using an air knife coater so as to have a coating amount of 5 g / m ² to obtain a recording sheet.

Comparative Example 1 100 parts by weight of boehmite (trade name "Alumina Sol-520", manufactured by Nissan Chemical Industries, Ltd.) and 20 parts by weight of polyvinyl alcohol (trade name "PVA-110", manufactured by Kuraray Co., Ltd.) A coating solution having a concentration of 16% was prepared. This coating solution was applied to a base paper having a basis weight of 120 g / m ² , a density of 0.90 g / cm ³ and a center line average roughness of 0.9 μm using an air knife coater so as to have a coating amount of 5 g / m ^2. Coating was performed to obtain a recording sheet.

Comparative Example 2 100 parts by weight of boehmite (trade name "Alumina Sol-520", manufactured by Nissan Chemical Industries, Ltd.) and 20 parts by weight of polyvinyl alcohol (trade name "PVA-110", manufactured by Kuraray Co., Ltd.) A coating solution having a concentration of 16% was prepared. This coating solution was subjected to molding with an engraving roll using an embossing machine after papermaking to obtain a basis weight of 108 g / m ² and a density of 0.80 g.
/ Cm ³ , and a center line average roughness of 6.5 μm was coated using an air knife coater so that the coating amount was 5 g / m ² to obtain a recording sheet.

The following items were evaluated for the above Examples and Comparative Examples. Table 1 shows the results. (1) Dynamic scanning liquid absorption meter (“KM350” manufactured by Kyowa Seiko Co., Ltd.)
-D1 ”), the wetting time and absorption coefficient determined from the liquid absorption curve of pure water. (2) Contact ratio when measured with a regular reflection type smoothness meter (manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a pressure of 40 kg / cm ² and a light beam having a wavelength of 0.5 μm. (3) Color density (solid color checker manufactured by Macbeth) of a solid printing portion of a three-color superimposed black of Y, M, and C performed by an electrocoagulation printing machine (manufactured by Elcorthy). ４, △, Δ, and × were also indicated, and ◎ and ○ were made practical. (4) Emboss feeling and texture of the recording sheet.段 階, △, Δ, and × were visually evaluated, and ◎ and ○ were made practical.

[0065]

[Table 1]

From the results in Table 1, the following has been found.

(1) As can be seen from Examples 1 to 8, the recording sheet of the present invention has an embossed feeling and a high ink color density can be obtained.

(2) As can be seen from Comparative Example 1, when a base paper having a center line average roughness of less than 2 μm is used, the recording sheet has no emboss feeling.

(3) As can be seen from Comparative Example 2, if the center line average roughness exceeds 6 μm, even if the recording sheet has an embossed feeling, the ink color density is inferior.

[0070]

As described above, according to the present invention,
A recording sheet suitable for electrocoagulation printing with a feeling of embossing and paper texture can be obtained, commercial art prints such as posters, calendars, brochures, published prints such as visual magazines, photo books, and art books, paper containers for pharmaceuticals, cosmetics, etc. It can be suitably used for packaging materials such as shopping bags and labels.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of an electrocoagulation printing machine using a recording sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Colloid ejector 4 Wiper 5 Press roll 6 Recording sheet 7 Cleaning device 8 Corrosion inhibitor application device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yutaka Hattori 501 Honjuku, Nagaizumi-cho, Sunto-gun, Shizuoka Pref.

Claims (10)

[Claims] 1. A recording sheet for electrocoagulation printing comprising a base paper provided with a coating layer containing a filler and an adhesive as main components,
A recording sheet for electrocoagulation printing, wherein irregularities are formed in advance on the surface of a base paper before a coating layer is provided. 2. The recording sheet for electrocoagulation printing according to claim 1, wherein the center line average roughness of the irregularities specified in JIS _B0601-1982 is 2 μm or more and 6 μm or less. 3. The method according to claim 1, wherein the filler contains one or more of synthetic amorphous silica, alumina sol, silica sol and plastic pigment. Recording sheet. 4. The recording sheet for electrocoagulation printing according to claim 3, wherein the alumina sol is at least one of boehmite and pseudo-boehmite. 5. The method according to claim 3, wherein the silica sol is in the form of a long bead, or a branched, bent or pearl necklace of long-chain colloidal silica connected to each other. Recording sheet for electrocoagulation printing. 6. The electrocoagulation printing method according to claim 3, wherein the silica sol has a shape in which spherical colloidal silica having a particle diameter of 10 to 50 nm is bound in a pearl necklace having a length of 50 to 400 nm. Record sheet. 7. The recording sheet for electrocoagulation printing according to claim 1, wherein the adhesive comprises an aqueous dispersion of binder particles composited with an ultrafine filler. 8. An electrocoagulation printing method according to claim 3, wherein said adhesive comprises an aqueous dispersion of acrylic emulsion particles having a particle size of 30 to 70 μm, which are composited with ultrafine colloidal silica. Recording sheet. 9. A recording sheet having a wetting time of 30 milliseconds or less, an absorption coefficient of 5 ml / m ² s ^-1/2 or more, obtained from a pure water absorption curve measured by a dynamic scanning absorptiometer, and a specular reflection smoothing. The electrocoagulation according to any one of claims 1 to 8, wherein a contact rate when measured with a light meter having a pressure of 40 kg / cm ² and a light beam having a wavelength of 0.5 µm is 25% or more. Recording sheet for printing. 10. The recording sheet for electrocoagulation printing according to claim 1, wherein the coating layer is applied using an air knife coater.