JP5077373B2 - Recycled postcard paper - Google Patents

Description

The present invention relates to a recycled postcard paper containing a lot of waste paper pulp , which does not cause a problem in reading and sorting of stealth barcode printing.

Although various technologies have been disclosed for postcard paper containing waste paper, it has not yet been implemented.
As a postcard paper, various printing aptitudes and writing aptitudes are required, and further, paper dust, rigidity, curl aptitude and the like are required, and as a postcard paper, single-layer papermaking has been mainstream.
In order to achieve both the offset printability of the address surface and the printability of the message description surface, there is a technology that discloses a technique for preventing ink bleeding by blending a filler having a high oil absorption amount in the back layer (Patent Documents 1 and 2). reference). In Patent Documents 1 and 2, there is a description in which waste paper pulp is blended in the middle layer by multi-layer stitching , but the blending amount is 30% by mass or less of the paper , and the evaluation as a postcard describes only printability. Has been.
In recent years, postcards are sorted by an automatic sorting machine by printing a stealth barcode on the postcard. However, in postcards using waste paper pulp, there are many misidentifications of stealth barcodes, and it is difficult to use paper containing a lot of waste paper pulp for postcards.

Japanese Patent No. 2763868 Japanese Patent No. 3253259

Even if the recycled paper contains 40% by mass or more of used paper in the base paper, the stealth barcode printed on the addressing surface is good, and further, cutting after offset printing and automatic after posting Providing paper with excellent handling properties that does not cause paper peeling in sorting machines.

The present inventors have carried out intensive investigations and found that the regeneration postcard paper that has multi-blended paper, thereby completing the present invention the following (1) to (4).
(1) Waste paper pulp is contained by 40% by mass or more in paper, and is made by multi-layered lamination of 3 or more layers, and the Taber stiffness in the MD direction defined by JIS P 8125 is 2.5 to 4.5 mN · m. , The opacity specified by JIS P 8138 is 97% or more, JAPAN TAPPI No. A recycled postcard paper having an internal bond strength of 500 to 700 KPa as defined in No. 18 and a fluorescence intensity of 110 or less observed with a fluorescence microscope.
(2) The recycled postcard according to (1), wherein in the multilayer structure formed by the multilayer paper making, used paper pulp containing 10% or more of fine fibers having an ash content of 10 to 20% and 0.1 mm or less is used for the layer in contact with the surface layer. Paper.
(3) The recycled postcard paper according to any one of (1) and (2), wherein the outermost layer is 20% by mass or less of the whole postcard paper in the multilayer structure by the multilayer papermaking.
(4) The said recycled paper pulp is the recycled postcard paper of any one of (1)-(3) containing the pulp by which the fluorescence decoloring process was carried out.

This is a recycled postcard paper that can read stealth barcode prints well and does not cause paper peeling in an automatic sorting machine.

Play postcard paper of the invention, the used paper pulp containing more than 40 wt% in the feed pulp is papermaking by three or more layers paper making alignment, MD direction Taber stiffness defined by JIS P 8125 is 2.5 -4.5 mN · m, the opacity specified by JIS P 8138 is 97% or more, JAPAN TAPPI No. 18 is a recycled postcard paper having an internal bond strength defined by No. 18 of 500 to 700 KPa and a fluorescence intensity observed with a fluorescence microscope of 110 or less. If the Taber stiffness is less than 2.5 mN · m, the postcard may be easily broken during posting or in the middle of delivery. If it exceeds 4.5 mN · m, there will be poor conveyance in the automatic sorting machine. Occur. Also, the opacity needs to be high. Further, when the interlayer strength is less than 500 KPa, paper dust occurs at the time of cutting, and paper peeling occurs at the time of printing or processing by an automatic sorting machine. When it exceeds 700 KPa, the adhesive cost in the layer and between the layers becomes high, which is not practical.

In the present invention, since a large amount of waste paper pulp of 40% by mass or more is blended in the postcard paper, a paper having a multi-layer structure of three or more layers of surface layer, middle layer and back layer is formed. Besides dust in the used paper pulp, in general deinking process can not be removed by waste paper processing including of paper making one layer for the fluorescent material contains a large paper are affected stealth bar code printing surface, the amount of waste paper pulp Is limited.
By using three or more layers of multi-ply paper , it is possible to mix waste paper pulp in a layer that does not include the stealth barcode printing surface. The number of layers of multi-layer papermaking is determined by the basis weight, thickness, texture of each layer, blending of raw materials, amount of paper, etc., and each layer is mixed with raw pulp, freeness and sizing agent, types of chemicals such as sulfuric acid bands, fillers, etc. Since the rate can be changed, the quality characteristics of the front and back surfaces can be changed. For example, in paper making combined in the middle of the three layers of tables layer, medium layer and back layer, the table under layer in combined paper making five layers in Table layer-table under layer, medium layer and back under layer and back layer, medium layer, a paper recycling pulp layers of the backing under layer was respectively blended, 40 wt% or more on the paper, more preferably may contain more than 60 wt%. Moreover, it is also possible to mix each layer with LBKP or NBKP and mix them into the paper so as to contain 40% by mass or more.
The surface layer including the address description surface (surface) on which stealth printing is performed is preferably LBKP 100%, which is smooth and easy to take.
LBKP 100% is also preferable for the back layer, but depending on the paint to be applied, waste paper pulp can be blended.

As a result of intensive studies on the reading of stealth barcode printing, the present inventors have found that a good stealth barcode can be obtained by adjusting the fluorescence intensity so that the reproduction postcard paper has a fluorescence intensity of 110 or less observed with a fluorescence microscope. It was determined that print readability was obtained.

A method for measuring the fluorescence intensity observed with the fluorescence microscope of the present invention will be described. In the present invention, a fluorescence image (ECLIPSE E600, manufactured by Nikon Corporation) is used as a postcard paper, and a fluorescent image of visible light generated when irradiated with ultraviolet rays having a wavelength of 365 nm is captured by a camera and stored in a file. Next, the fluorescence intensity of the stored image is digitized using analysis software (IO-MATE 2007, manufactured by I-Spec Co., Ltd.).
In the present invention, as read the stealth bar code printing to be printed on reproduction postcard paper, fluorescence intensity to 110 or less.

In this invention, it describes below as a method of adjusting so that the fluorescence intensity observed with a fluorescence microscope may be 110 or less.

Waste paper pulp contains a large amount of fluorescent dye, so in order to reduce the fluorescence intensity of recycled postcard paper containing many waste paper pulps to 110 or less, the surface layer is composed of high-quality kraft pulp, etc. it may raise but by raising the surface layer of the composition ratio, so that the mixing ratio of the waste paper pulp is limited.
In the present invention, by adjusting the waste paper pulp used in other than the surface layer, the blending ratio of the waste paper pulp can be high Kusuru. Mechanical pulp blended for imparting cushioning properties and other writing properties may be blended, but mechanical pulp is not preferred because it has poor fading. In the present invention, not only cushioning properties, but also to improve the opacity and prevent the interlaminar strength from becoming a problem in multilayer papermaking, the amount of ash content and the amount of fine fibers in waste paper pulp are regulated and the balance is adjusted. Thus, the composition ratio of the surface layer (address surface) composed of high-quality kraft pulp or the like can be reduced, and for example, it can be 20% by mass or less of the entire postcard paper.

In the recycled postcard paper of the present invention, it is important that the interlayer strength is 500 to 700 KPa. If the interlaminar strength is less than 500 KPa, paper dust occurs during cutting, and paper peeling occurs during printing or processing by an automatic sorter. When it exceeds 700 KPa, the adhesive cost in the layer and between the layers becomes high, which is not practical.
Further, as a method for adjusting the interlaminar strength, blending of a paper strength enhancer is effective. In order to further increase the adhesive strength between the respective layers, it is possible to spray starch or other adhesives with a spray.

In the present invention, used paper pulp is adjusted and used for the layer in contact with the surface layer.
It is preferable to contain 50% or more of waste paper pulp.
該古paper pulp 10-20% ash content, preferably a benzalkonium be containing the following fine fibers 0.1mm 10% or more. In general, as compared with the same material, considered interlaminar strength is reduced if Conform paper making those different quality, the layer of the surface layer and used paper pulp say kraft pulp quality are used It is conceivable that the interlayer strength decreases. In the present invention , by using 10% or more of fine fibers of 0.1 mm or less in the used paper pulp used for the layer in contact with the surface layer, and by containing 8% or more in the layer in contact with the surface layer, the surface layer and the lower layer, or the middle layer It becomes possible for the fibers to be entangled to suppress a decrease in interlayer strength. Further, using a material obtained by the ash in the waste paper pulp used for the layer in contact with the surface for opacity improvement of improvement and cushioning of 10 to 20%, and preferably is contained 5% or more layers in contact with the surface layer. If the ash content of the layer in contact with the surface layer is less than 5%, the effect of improving opacity cannot be expected, and if it exceeds 20%, the decrease in interlayer strength can not be suppressed. If the amount of ash in the layer in contact with the surface layer is in the above range, it is possible to suppress these reductions due to the presence of 8% or more of fine fibers of 0.1 mm or less. The ash is preferably derived from raw material waste paper from the viewpoint of effective utilization of resources.

Fine fiber is JAPAN TAPPI No. The fiber length distribution at the time of the number average calculation of the fiber length measured by the pulp fiber length test method in the optical automatic measurement method defined in 52 is defined as a ratio of 0.1 mm or less, and the fiber length manufactured by kajaani It means a measured value of 0.1 mm or less when measured with a distribution measuring instrument “Fiber Lab”. 0.1mm the following proportion of the fine fibers in waste paper pulp is preferably 10% to 30%, more preferably from 10 to 20%, when Many blended paper pulp exceeds 30%, strength is lowered Therefore, it is not preferable.

The amount of fine fibers and ash content of waste paper pulp can be adjusted in the waste paper treatment process.
Various types of used paper can be used as a raw material for used paper pulp. For example, white paper, ruled white, etc. are used once, but there are very few printed parts. Cards, imitations, colors, Kent, white Art and other printed materials, colored paper that has been used once, coated paper for printing, used packs for beverages, used high-quality used paper such as office paper, as well as business systems such as special cutting, medium-quality anti-old, Kent Manila, etc. It is obtained from general medium-sized waste paper such as medium-quality waste paper, newspapers, magazines, and miscellaneous paper, and tea-based waste paper such as cut tea, plain tea, miscellaneous bags, and cardboard. Among them, waste paper having an ash content of 10% or more is preferable.

Recovered paper pulp construed mixed and separated in an aqueous solution containing an alkaline component, such as water or sodium hydroxide, in a subsequent dust step (cleaners or screen), stripped foreign substances other than pulp fibers, ink separation called flotation after the bleaching process to a desired whiteness after step, it is finely dispersed by a dispersing machine called knee loaders and disperser. It is possible to adjust the ash content to a range of 10 to 20% by a pulp washing process installed at any point in this process. DNT washer, compact washer, hole washer, vario split, SP filter, DP Cosmo An example is a cleaning device such as a cap washer, but is not limited thereto.

The amount of fine fibers can be adjusted by the dispersion step and the washing step, but can also be adjusted by a beating process after the used paper processing step. There are no particular limitations on the beater, and various beaters such as a beater, Jordan, a deluxe finer (DF), and a double disc refiner (DDR) are used. The waste paper pulp of the present invention is used after being processed to 250 to 450 ml by Canadian Standard Freeness. If it exceeds 450 ml, the interlayer strength decreases, which is not preferable. Further, if the beating is carried out over 250 ml, the yield of the pulp is lowered and the density of the base paper is increased, which is not preferable.

Furthermore, fluorescent paper can be subjected to fluorescent decoloring treatment . Even if such waste paper pulp is blended in the surface layer , the fluorescence intensity observed with a fluorescence microscope can be reduced to 110 or less . Fluorescent decoloring treatment of used paper pulp as used here means adding waste paper pulp after deinking treatment with sodium thiosulfate pentahydrate (hypo), chlorine dioxide or sodium chlorite at a pulp concentration of 10% or more The treatment is performed at a rate of 1% or more, a temperature of 40 degrees or more, and a reaction time of 60 minutes or more. Of these, chlorine dioxide is preferred because of the safety of the working environment. By the above treatment, the fluorescence intensity of the used paper pulp can be reduced by 90% or more, and the used paper pulp can be blended in the surface layer, and the ratio of the used paper pulp can be increased. However, at 100% by weight of waste paper pulp , there is a possibility that a problem due to insufficient rigidity occurs in the automatic sorting processor, so at present, about 80% by weight of waste paper pulp is considered the upper limit.

In addition to the above, the method of fluorescent decoloring treatment includes polyvalent metal treatment, enzyme treatment, peroxide treatment, ozone treatment, masking treatment and the like, and any treatment can be used in the present invention. Specifically, the polyvalent metal processing, the waste paper pulp slurry, for example by inserting an aluminum foil, by treatment with 20 ° C. 24 hours, as possible out to extinguish fluorescence. The enzyme treatment can decompose the fluorescent whitening agent by further containing laccase at a redox mediator presence pH of 2 to 12 and a temperature ranging from room temperature to 70 ° C. In the peroxide treatment, 1% ammonium persulfate and 0.2% iron sulfate are mixed with 2% -concentrated waste paper pulp slurry, and the reaction is performed at a reaction temperature of 60 ° C. or more, a reaction time of 2 hours or more, and a pH of 8 or less. Fluorescence is extinguished by oxidative decomposition. The ozone treatment can be decolorized by stirring the slurry in the presence of ozone in a state where the slurry having a pulp concentration of 0.5 to 3% by weight is maintained at pH 9 to 11.5. In the masking treatment, an appropriate amount of polyalkyl quaternary ammonium salt of a polyalkylene polyamine / dicarboxylic acid condensate is added and stirred in a state where the pH of the waste paper slurry having a concentration of about 1% is maintained at 7 or less. kill at.

In the recycled postcard paper of the present invention, the Taber stiffness specified by JIS P 8125 in the paper machine flow direction (MD direction) is preferably 2.5 to 4.5 mN · m. Generally, the vertical direction of the postcard is the paper machine flow direction (MD direction).
If the Taber stiffness is less than 2.5 mN · m, the postcard may be easily broken during posting or in the middle of delivery. If it exceeds 4.5 mN · m, there will be poor conveyance in the automatic sorting machine. Occur. When waste paper pulp is blended in a large amount, the stiffness decreases in the case of one layer, but the reduction in stiffness can be suppressed by using a multilayer structure. In the present invention, the decrease in stiffness is suppressed by adjusting the amount of waste paper other than the surface layer, the amount of ash, and the amount of fine fibers.
Furthermore, the stiffness of the flow direction (MD) of the papermaking machine is adjusted by adjusting the strength of the papermaking machine, adjusting the J / W ratio during papermaking, and adjusting the inlet concentration.

In the present invention , the pulp used in addition to the waste paper pulp is not particularly limited, and it is not limited to chemical pulp such as KP and SP, mechanical pulp such as SGP, RGP, BCTMP, and CTMP, or kefna, bamboo, straw, hemp, etc. non-wood pulp, polyamide fibers, polyester fibers, such as organic synthetic fibers such as polynosic fibers, more glass fibers, ceramic fibers, Ru can be used inorganic fibers such as carbon fibers.

Also, during each layer as necessary, filler is Ru can formulation. The filler in this case is not particularly limited, but is generally used for high-quality paper. For example, kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, carbonate Organic materials such as magnesium, magnesium oxide, silica, white carbon, bentonite, zeolite, sericite, smectite, and other minerals, polystyrene resin, urea resin, melamine resin, acrylic resin, vinylidene chloride resin and their fine hollow particles Is mentioned.

In addition to pulp fibers and fillers, the paper stock includes various anionic, nonionic, cationic or amphoteric yield improvers, drainage improvers, paper strength enhancers, and internal sizing agents. The internal additive aid can be appropriately selected and used as necessary. Furthermore, internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be appropriately added depending on the use of the paper. In particular, in order to adjust the interlayer strength to 500 to 700 KPa, the addition of a paper strength enhancer is effective as a technique for increasing the strength in the layer. It is also effective to spray starch or other adhesives with a spray between the layers in order to increase the adhesive strength between the layers.

The papermaking method is not particularly limited except for multilayer papermaking. For example, acidic papermaking with a papermaking pH of around 4.5, an alkaline filler such as calcium carbonate as a main component, and a weakly acidic papermaking pH of about 6 Can be applied to all papermaking methods such as neutral alkaline papermaking with a weak alkaline pH of about 9, and the paper machine can be a long paper machine, a twin wire paper machine, a circular paper machine, or a short paper machine as appropriate. Can be used in combination.

Playback postcard of the invention, the rear surface of the address plane, Ru can also be provided with a coating layer capable inkjet printer or an electrophotographic printer or offset printing. Examples of the pigment used in the coating layer include heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, delaminated kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide, Mineral pigments such as silica, magnesium aluminosilicate, particulate calcium silicate, particulate magnesium carbonate, particulate light calcium carbonate, white carbon, bentonite, zeolite, sericite, smectite, polystyrene resin, styrene-acrylic copolymer system Organic pigments such as hollow resin, solid resin and through-hole resin such as resin, urea resin, melamine resin, acrylic resin, vinylidene chloride resin, and benzoguanamine resin can also be used. 1 type or 2 Or selected and used appropriately.

As the adhesive of the coating layer, it is possible to use a water-soluble and / or water-dispersible polymer compound, for example, cationic starch, amphoteric starch, oxidized starch, enzyme modified starch, thermochemically modified starch, esterified Starch, starches such as etherified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, natural or semi-synthetic polymer compounds such as gelatin, casein, soybean protein, natural rubber, polyvinyl alcohol, isoprene, neoprene, polybutadiene, etc. Polydienes, polybutenes, polyisobutylenes, polyalkenes such as polypropylene and polyethylene, vinyl halides such as vinyl halides, vinyl acetate, styrene, (meth) acrylic acid, (meth) acrylic acid esters, (meth) acrylamide, and methyl vinyl ether Copolymers and copolymers Styrene - butadiene, methyl methacrylate - synthetic rubber latex butadiene etc., polyurethane resins, polyester resins, polyamide resins, olefin - maleic anhydride resins, synthetic polymer compounds such as melamine resins and the like. Among these, one or more kinds are appropriately selected and used according to the purpose.

The blending ratio of the adhesive in the coating layer is in the range of 5 to 50 parts by weight (solid part) with respect to 100 parts by weight (solid part) of the pigment. Incidentally, if it is less than 5 parts by weight, the strength of the coating layer of the coating layer is weak, which may cause the coating layer to peel off. On the other hand, if it exceeds 50 parts by weight, printing blurring may occur during ink jet printer printing, blistering may occur during electrophotographic printer printing, and ink drying properties may deteriorate during offset printing.

In this coating liquid, in addition to these pigments and adhesives, various auxiliary agents such as surfactants, pH adjusters, viscosity adjusters, softeners, gloss imparting agents, waxes, dispersants, flow modifiers, Anti-conductive agent, stabilizer, antistatic agent, cross-linking agent, sizing agent, fluorescent brightening agent, colorant, UV absorber, antifoaming agent, water-resistant agent, plasticizer, lubricant, preservative, fragrance, etc. are required It is also possible to use it appropriately according to.

Laydown if the present invention play postcard paper provided coating layer is preferably from 1 to 20 g / m ^2, more preferably 1 to 10 g / m ^2. When the coating amount is less than 1 g / m ² , the unevenness on the surface of the sheet-like paper substrate can not be sufficiently covered, and the acceptability of the printing ink may be significantly reduced. On the other hand, when it exceeds 20 g / m ² , the operability such as poor drying at the time of coating is lowered, and the production cost may be increased.

As the coating method for forming the coating layer is generally known coating device, for example a blade coater over, et yer knife coater over, roll coater chromatography, reverse roll coater over, bar coater, curtain coater over, the die slot coater over , gravure coater chromatography, champlex coater over, brush coater chromatography, Tsuroru or metering blade type of size press coater over, bill blade coater over, short dwell coater over, apparatus such as a gate roll coater over is appropriately used.

The coating layer may have a multilayer structure by providing one layer or two or more intermediate layers as necessary, if necessary. In the case of double-sided coating or multi-layer structure, each coating solution does not need to be the same or the same coating amount, and may be appropriately adjusted according to the required quality level and is particularly limited. is not. In addition, when a coating layer is provided on one side of a sheet-like paper substrate, a synthetic resin layer, a coating layer made of pigment and adhesive, an antistatic layer, etc. are provided on the back side to prevent curling, impart printability, and supply / discharge It is also possible to impart paper suitability and the like. Furthermore, it is of course possible to use the sheet-like paper substrate with application suitability by applying various processes such as adhesion, magnetism, flame resistance, heat resistance, water resistance, oil resistance, and slip resistance to the back surface of the sheet-like paper substrate. .

In the present invention, after the coating layer is provided, it is smoothed by a normal drying process, a surface treatment process, etc., and adjusted so that the water content is 3 to 10%, preferably about 4 to 8%. It is done.
Also when smoothing processing is usually super calender over, gloss calender over, it conducted smoothing processing apparatus such as a soft calender over, be optionally employed in on-machine or off-machine in the form of a pressure device, The number of pressure nips, heating, and the like are also adjusted as appropriate according to a normal smoothing apparatus.

The recycled postcard paper of the present invention is glossy by a so-called casting method, in which a wet coating layer is pasted on the back surface of the addressed surface on a high-temperature cast drum, and steam is released from the back surface to dry and copy the mirror surface of the drum. By providing the expression layer, it is also possible to obtain a more beautiful inkjet printing finish.

The gloss developing layer in the present invention contains inorganic or organic gloss developing fine particles and an organic or inorganic binder as main components.

Examples of the fine particles capable of developing gloss include inorganic fine particles produced by a dry process such as fumed silica and fumed alumina, colloidal suspensions such as colloidal silica, boehmite and pseudoboehmite, and colloidal suspensions typified by alumina sol, gels. Amorphous silica, calcium carbonate, magnesium carbonate, aluminum hydroxide, white pigments such as titanium dioxide obtained by the chemical conversion method or precipitation method, natural minerals such as kaolin, talc, diatomaceous earth, etc. Surface-treated inorganic fine particles, polystyrene, methyl methacrylate, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic acid ester and methacrylic acid ester copolymer, microcapsule, urea resin, melamine resin Etc. Fine particles can be exemplified, it is also possible to use a combination of two or more of them.

Examples of binders used in the glossy layer include polyvinyl alcohol or derivatives thereof, cellulose derivatives such as polyvinylpyrrolidone, methylcellulose, carboxymethylcellulose, and hydroxyethylcellulose, proteins such as casein, gelatin, and gluten, starch, oxidized starch, etherified starch, and phosphoric acid. Starch derivatives such as esterified starch, polymers or copolymers of acrylic ester and methacrylic ester, conjugated diene copolymers such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, vinyl acetate, ethylene Vinyl-based polymers such as vinyl acetate, vinyl chloride-vinyl acetate copolymer, urethane resins, or functional group-modified polymers thereof, thermosetting resins such as melamine resin, urea resin, sodium silicate, silicate carbonate Silicic acid metal salt such as um, alumina sol, polyaluminum chloride, aluminum biphosphate, can be exemplified inorganic binder of zinc phosphate and the like. As the binder content, an appropriate amount is 5 to 70 parts by weight with respect to 100 parts by weight of the pigment. If the binder is less than 5 parts by weight, the coating strength is insufficient, and if the binder exceeds 70 parts by weight, the ink absorbency is increased. descend.

In the glossy layer, as an additive, an ink fixing agent, a release agent, a thickener, a fluidity improver, a dispersant, an antifoaming agent, a penetrating agent, a water resistance agent, a pH adjusting agent, a coloring dye, a coloring pigment Fluorescent dyes, ultraviolet absorbers, antioxidants, preservatives and the like may be added as necessary.

Examples of the coating of the glossy layer coating solution thus prepared include various types such as a blade coater, a roll coater, an air knife coater, a rod coater, a lip coater, a curtain coater, a spray coater, a die coater, and a champless coater. Can be used. The coating amount of the glossy layer varies depending on the composition and smoothness of the ink receiving layer of the undercoat, the liquid absorbency and smoothness of the base paper, and the required glossy surface quality, but is generally 0.5 g / m in dry coating amount. If it is ² or more, gloss is developed.

Casting is a process in which a coating liquid for forming a glossy layer is applied, and the coated surface is pressed and dried on a heated mirror roll (cast drum) while the coated surface is in a wet state. The surface shape of the mirror roll is copied onto the surface of the coating layer to form a glossy layer. Depending on the dry and solidified state of the coating layer when it is pressure-bonded to the cast drum, the wet method, gelation method, rewetting method Can be classified. Any casting method can be applied to the present invention, but in order to obtain a particularly beautiful glossy surface, it is preferable to use a gelling method. Moreover, the rewetting method is preferable for high-speed processing and low cost, and is appropriately selected according to the purpose.

Moreover, you may perform a calendar process as needed after a cast process. As the calendar, general devices such as a super calendar, a machine calendar, and a soft calendar can be used. Also, post-processing treatments according to various product appearances such as embossing, drilling, and back surface tacking are possible.

Examples of the present invention will be described below, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the Examples and the specification indicate parts by mass and mass% unless otherwise specified.
Tables 1 and 2 show the results of measuring the following measurement methods for the recycled postcard papers obtained in Examples 1 to 11 and Comparative Examples 1 to 4 below.

(Taber stiffness)
The machine flow direction (MD direction) was measured according to JIS P 8125.
(Opacity)
It measured based on JISP8138.
(Interlayer strength)
JAPAN TAPPI Paper Pulp Test Method No. 18-1 Paper and paperboard-Internal bond strength test method-Part 1: Measured according to the Z-axis direction tensile test.
(ash)
“Paper, paperboard and pulp-ash content test method 525 ° C. combustion method” JIS P 8251
(Fine fiber content)
JAPAN TAPPI No. 52 Measured by “Fiber length test method for paper and pulp (automatic optical measurement method)”.
Fiber length distribution measuring instrument “Fiber Lab” manufactured by kajaani is used. * The layer in contact with the surface layer is immersed in a beaker containing hot water for 5 minutes in a sample and immersed for several minutes. If not, a layer that was further immersed in hot water and divided into layers was used.

(Fluorescence intensity)
Using a fluorescent microscope (ECLIPSE E600, manufactured by Nikon Corporation) in a dark room, a fluorescent image of visible light generated when ultraviolet rays with a wavelength of 365 nm are irradiated onto a postcard is displayed in color on the camera control unit (DS-L1). Save to a file in JPEG format. Next, after the stored image was converted into the TIFF format, the average value of the level values of the pixels was defined as the fluorescence intensity using analysis software (IO-MATE 2007, manufactured by Aspec Co., Ltd.).

Image capturing condition device: ECLIPSE E600, Nikon Corporation camera head: DS camera head DS-5M
Camera control unit: DS-L1
TV LENSE: C-0.6x
Magnification: Objective lens x4 Eyepiece lens x10
Display mode: 1.3Mp
Exposure mode: MANU
Shutter speed: 1/90 seconds Camera gain (C_gn): 170
Image level adjustment (GAIN): Y100 R100 B100
Color intensity (CHRM): +25
Hue adjustment (HUE): -25 SFT +50

* Image analysis
Processing software: General-purpose image processing and image analysis software IO-METE 2007, version 3.3.0 (IO Ver. 2.0.0.0), manufactured by I-Spec Co., Ltd. ”, The measurement location, the average value of the level values of the pixels of the displayed image, and the fluorescence intensity (256 levels from 0 to 255).

(Evaluation of paper peeling when cutting after offset printing)
Four-color machine flat offset printing was performed on the recycled postcard paper of the present invention, and the paper peeling at the edge after printing was visually observed and evaluated according to the following criteria.
○: No paper peeling is observed.
Δ: Some peeling of paper is observed, but there is no practical problem.
X: Peeling of paper is severe, which causes a practical problem.

(Evaluation of paper peeling during processing of automatic sorting machine after posting)
The recycled postcard paper after the four-color machine size offset printing of the present invention was processed by an automatic sorting machine, and the edge peeling was visually observed and evaluated according to the following criteria.
○: No paper peeling is observed.
Δ: Some peeling of paper is observed, but there is no practical problem.
X: Peeling of paper is severe, which causes a practical problem.

(Inkjet printing quality evaluation of the back layer)
Epson G860 (dye ink) and Epson PX930 (pigment ink) were printed on the back layer and the coating layer of the recycled postcard paper of the present invention.
○: No blurring is observed at all.
Δ: Slight blurring is observed, but there is no practical problem.
X: Scratching is severe and causes a practical problem.

Waste paper pulp manufacturing method (waste paper pulp A)
Kent waste paper (ash content: 33.2%) is disaggregated with a pulper, passed through a dust remover (cleaner and screen), then concentrated to a solids concentration of about 30% with a tilt extractor and screw press dehydrator. Disperse with a disperser while adding sulfonamidine (FAS) and bleaching, and after passing through a pulp washer (DNT washer: Aikawa Tekko) while diluting with water, adjust the freeness to 300 ml. Waste paper pulp A was obtained. The ash content of this pulp was 11.8%, and the fine fibers of 0.1 mm or less were 14.5%.

(Waste paper pulp B)
Magazine paper (ash content 20.3%) was disaggregated with a pulper, passed through a dust remover (cleaner and screen), freeness was adjusted to 350 ml with a double disk refiner, and used paper pulp B was obtained. The ash content of this pulp was 18.8%, and the fine fibers of 0.1 mm or less were 9.8%.

(Waste paper pulp C)
Dissolve old colored paper (34.3%) with a pulper, pass through a dust remover (cleaner and screen), dilute with water to a solids concentration of 1%, add deinking agent, and use a flowmeter Apply deinking treatment, concentrate to a solids concentration of about 30% with a tilt extractor and screw press dehydrator, disperse using a kneader, pass through a screen, then pass through a double refiner to reduce freeness. Waste paper pulp C adjusted to 350 ml was obtained. The ash content of this pulp was 24.2%, and the fine fibers of 0.1 mm or less were 33%.

(Waste paper pulp D)
Disintegrate old newspaper (12.7%) with a pulper, pass through a dust remover (cleaner and screen), dilute with water to a solid content of 1%, add deinking agent, and remove with a flowmeter. Apply black ink, concentrate to about 30% solid content with an inclined extractor and screw press dehydrator, add FAS and disperse using Disperser (TL1 manufactured by Aikawa Tekko), then double Through a disk refiner, 350 ml free paper pulp D was obtained. The ash content of this pulp was 5.2%, and the fine fibers of 0.1 mm or less were 10.5%.

(Waste paper pulp E)
After adjusting the waste paper pulp A to a pulp concentration of 10%, chlorine dioxide was added so as to be 1% with respect to the pulp, and a pulp E having a fluorescence intensity reduced by 97% was obtained by treating at 60 ° C. for 1 hour.

(Waste paper pulp F)
After adjusting the waste paper pulp A to a pulp concentration of 2%, ammonium persulfate to pulp 1% (Kayclean AW: Nippon Kayaku Co., Ltd.) and iron sulfate 0.4% pulp (Kayclean IK: Nippon Kayaku Co., Ltd.) The mixture was blended and treated at 60 ° C. for 5 hours under the conditions of pH 2.5, whereby the fluorescence intensity was reduced by 97% to obtain Pulp F.

(Waste paper pulp G)
After adjusting the waste paper pulp A to a pulp concentration of 1%, a polyalkyl quaternary ammonium salt of a polyalkylene polyamine / dicarboxylic acid condensate (OP-603: Pulp G having a fluorescence intensity reduced by 97% was obtained by adding 1 wt.

Example 1
The combined paper making five layers by handsheet paper making method described below was created play postcard paper.
Formulated pulp for surface and back layers: 100% hardwood bleached kraft pulp (LBKP).
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Table below layer, formulations pulp of subplantar layer: paper pulp A 100%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Middle layer prescription pulp composition: Waste paper pulp B 100%
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

The raw materials for each layer formulated as described above were hand-sheeted with a 150 mesh wire square sheet machine with a target basis weight of 35 g / m ^{2 for} the front layer and back layer, and a target basis weight of 40 g / m ² for the lower layer, back layer and lower layer. I did. This wet paper was applied to the surface layer, front layer, lower layer, middle layer, back layer, and back layer by applying an aqueous solution of 2.5% oxidized starch in an absolutely dry solid content of 0.3 g / m ² and superposing them at 105 ° C. A hand-dried paper was obtained by drying with a drum dryer for 3 minutes.

Front and back size treated paper A mixed aqueous solution of 2.5% oxidized starch, 1.1% polyvinyl alcohol and 0.4% olefin-based surface sizing agent was prepared as the front and back size liquid. The front and back surface sizing solution surface Meyer bar 2 g / m ² (the offset surface) absolute dry solids, and air dried after 2 g / m ² coated on the back surface and smoothed with a small calender.

Example 2
3-ply together to create a reproduction postcard paper by handsheet paper making method described below.
Formulated pulp for surface and back layers: 100% hardwood bleached kraft pulp (LBKP).
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Middle layer formula pulp composition: Bleached waste paper pulp A 100%
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Add 8% aqueous solution as sulfuric acid band Al ₂ O _{3 and} add 2.5% to pulp.

The raw materials for each layer formulated as described above were hand-sheeted with a 150 mesh wire square sheet machine so that the surface layer and the back layer had a target basis weight of 50 g / m ² and the middle layer had a target basis weight of 90 g / m ² . This wet paper was coated with 0.3 g / m ^{2 of} an aqueous solution of oxidized starch 2.5% in the dry solid content between the surface layer, the middle layer and the back layer, and overlapped with a drum dryer at 105 ° C. for 3 minutes. The paper was made by drying.

Front and back size treated paper A mixed aqueous solution of 2.5% oxidized starch, 1.1% polyvinyl alcohol and 0.4% olefin-based surface sizing agent was prepared as the front and back size liquid. The front and back sizing solution Meyer bar surface 2 g / m ² absolute dry solids (offset surface), after 2 g / m ² coated on the backside and those air-dried smoothed compact calender.

Reference example 1
Recycled postcard paper was prepared by laminating five layers in the same manner as in Example 1 except that the formulation of each layer was changed as follows.
Formulated pulp for surface and back layers: hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp E 50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Table below layer, the backing under layer formulation pulp: hardwood bleached kraft pulp (LBKP) 50%, E50% recycled pulp.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Middle layer prescription pulp composition: Waste paper pulp B 100%
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Reference example 2
Recycled postcard paper was prepared in the same manner as in Example 1 except that the pulp of all layers was changed to hardwood bleached kraft LBKP 30% and waste paper pulp E70%.

Example 5
On the back layer of the reproduction postcard paper obtained in Example 1, provided the lower Kinuri coating layer to prepare a reproduction postcard paper having a coating layer. Similar to Example 1, blank paper quality, fluorescence intensity, and inkjet printing quality are summarized in Table 1 .

< Creation of coating layer>
Amorphous silica Fine seal X-30 100 parts Cationic resin Unisense CP103 10 parts Surfactant Emulgen A-60 0.3 parts Vinyl acetate adhesive Polysol AM3150 15 parts

The above coating solution was adjusted to 10%, and an air dry coater was used to coat 5 g / m ^{2 of} an absolutely dry solid content and dried to prepare a coating layer .

Comparative Example 1
Pulp formulation: Hardwood bleached kraft pulp (LBKP) 50%, recycled paper pulp A 50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.
One layer of recycled postcard paper was prepared using the above-mentioned stock. The size liquid and coating amount on the front and back surfaces, and the small calender treatment were the same as in Example 1.

Comparative Example 2
In Example 1, recycled postcard paper was prepared in the same manner as in Example 1 except that the used paper pulp used for the front and lower layers and the back lower layer was changed to used paper pulp C.

Comparative Example 3
Recycled postcard paper was prepared in the same manner as in Example 1 except that the used paper pulp used for the front and lower layers and the back lower layer in Example 1 was changed to used paper pulp D.

Comparative Example 4
In Example 2, recycled postcard paper was prepared in the same manner as in Example 2 except that the used paper pulp A was changed to the used paper pulp B.

Example 6
Except for changing the formulation of each layer below was prepared playback postcard paper combined paper making five layers in the same manner as in Example 1.
Formulated pulp for surface and back layers: hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp F 50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Table below layer, the backing under layer formulation pulp: hardwood bleached kraft pulp (LBKP) 50%, F50% recycled pulp.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Middle layer prescription pulp composition: Waste paper pulp B 100%
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Example 7
Except for changing the formulation of each layer below was prepared playback postcard paper combined paper making five layers in the same manner as in Example 1.
Prescription pulp composition of surface layer and back layer: Hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp G 50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Table below layer, the backing under layer formulation pulp: hardwood bleached kraft pulp (LBKP) 50%, G50% recycled pulp.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.8% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Middle layer prescription pulp composition: Waste paper pulp B 100%
Paper strength enhancer: Polyacrylamide is added in the form of 2.0% pulp.
Sulfuric acid band: 8% aqueous solution as Al ₂ O ₃ in solid form and 2.5% added to pulp.

Example 8
A coated post layer was provided on the recycled postcard paper of Example 6 in the same manner as in Example 5 to produce a recycled postcard paper having a coated layer. Table 1 summarizes blank paper quality, fluorescence intensity, and inkjet printing quality.

Example 9
The recycled postcard paper of Example 7 was provided with a coating layer in the same manner as in Example 5 to produce a recycled postcard paper having a coating layer. Table 1 summarizes blank paper quality, fluorescence intensity, and inkjet printing quality.

Example 10
On the back layer of the recycled postcard paper obtained in Example 1, the following ink fixing layer and gloss developing layer were provided to produce a recycled postcard paper having an ink fixing layer and a gloss developing layer. Table 1 summarizes blank paper quality, fluorescence intensity, and inkjet printing quality.
[Create ink fixing layer]
Application of borax liquid 5% borax liquid is applied with a bar to the back layer of the above recycled postcard paper (the back side of the address of the five-layer combined recycled postcard paper ) so that the dry weight is 1 g / m ² . Dried.
Preparation and coating of ink receiving layer coating solution "Preparation of silica sol"
Commercially available gas phase method silica (trade name: Leolosil QS-30, average primary particle size 9 nm, specific surface area 300 m ² / g, manufactured by Tokuyama Corporation) was dispersed and pulverized with a sand grinder and then nanomizer (trade name: Nanomizer) , Manufactured by Nanomizer Co., Ltd.), and repeated pulverization and dispersion. After classification, a 10% dispersion having an average secondary particle size of 80 nm was prepared.
10 parts of diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd.) is added as a cationic compound to the dispersion to agglomerate the pigment and increase the dispersion. After causing viscosity, pulverization and dispersion were repeated using a nanomizer again to prepare an 8% dispersion having an average secondary particle size of 300 nm to obtain a silica sol.
100 parts of the silica sol and 15 parts of polyvinyl alcohol (trade name: PVA135, manufactured by Kuraray Co., Ltd.). Addition and stirring were performed, and water was further added to obtain a coating solution having a solid concentration of 12%. The ink receiving layer liquid was applied and dried with an air knife coater so that the dry mass was 12 g / m ² .

On the address side, the treatment liquid having the following formulation was adjusted to 2%, and 0.5 g / m ^{2 was} provided at an absolute dry solid content using a Meyer bar.
<Prescription of treatment liquid>
Starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) 100 parts polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.) 13.5 parts Surface sizing agent (trade name: Polymeralon 1329K, manufactured by Arakawa Chemical Industries, Ltd.) 3.5 Part NaCl (conductive agent) 6.5 parts

[Create glossy layer]
Preparation and application of glossy layer coating liquid Composite emulsion of acrylic emulsion and colloidal silica with a glass transition point of 100 ° C (trade name: Aquabrid 906, manufactured by Daicel Chemical Industries, Ltd., acrylic emulsion and colloidal silica are in mass The ratio is 20:80, the particle size of the emulsion is 40 nm), 100 parts of casein, 5 parts of thickener, 6 parts of thickener, 5 parts of release agent (stearic acid) are added and stirred, and water is added, and the solid content concentration A 5% coating solution was obtained.
The gloss developing layer is applied onto the surface of the ink receiving layer side so that the dry coating amount is 1 g / m ^2, and while being in a wet state, it is pressed against a heated mirror drum and dried to finish. , Made recycled postcard paper.

Example 11
The following glossy expression layer was provided on the back layer of the recycled postcard paper obtained in Example 4 to prepare a recycled postcard paper having a glossy expression layer . Table 1 summarizes blank paper quality, fluorescence intensity, and inkjet printing quality.
[Create glossy layer]
Application of borax liquid 5% borax liquid is applied with a bar to the back layer of the above recycled postcard paper (the back side of the address of the five-layer combined recycled postcard paper ) so that the dry weight is 1 g / m ² . Dried.

Preparation and coating of glossy layer coating liquid “Preparation of silica sol”
Commercially available gas phase method silica (trade name: Leolosil QS-30, average primary particle size 9 nm, specific surface area 300 m ² / g, manufactured by Tokuyama Corporation) was dispersed and pulverized with a sand grinder and then nanomizer (trade name: Nanomizer) , Manufactured by Nanomizer Co., Ltd.), and repeated pulverization and dispersion. After classification, a 10% dispersion having an average secondary particle size of 80 nm was prepared.
10 parts of diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd.) is added as a cationic compound to the dispersion to agglomerate the pigment and increase the dispersion. After causing viscosity, pulverization and dispersion were repeated using a nanomizer again to prepare an 8% dispersion having an average secondary particle size of 300 nm to obtain a silica sol.
100 parts of the silica sol and 15 parts of polyvinyl alcohol (trade name: PVA135, manufactured by Kuraray Co., Ltd.) were added and stirred, and water was further added to obtain a coating solution having a solid content concentration of 18%. The gloss developing layer solution was applied so as to have a dry mass of 12 g / m ² , and while in a wet state, it was pressed against a heated mirror drum and dried (wet casting method) to finish.

On the address side, the treatment liquid having the following formulation was adjusted to 2%, and 0.5 g / m ^{2 was} provided at an absolute dry solid content using a Meyer bar.
<Prescription of treatment liquid>
2. Starch (trade name: Ace A, manufactured by Oji Cornstar) 100 parts polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.) 13.5 parts Surface sizing agent (trade name: Polymaron 1329K, manufactured by Arakawa Chemical Industries) 5 parts NaCl (conductive agent) 6.5 parts

Claims (4)

Waste paper pulp is contained in the paper at 40% by mass or more and is made by multi-layered lamination of 3 or more layers. The layer in contact with the surface layer contains 10% to 30% of fine fibers having a number average fiber length of 0.1 mm or less. In the used paper pulp, the layer in contact with the surface layer contains 8% or more of fine fibers having a number average fiber length of 0.1 mm or less, and the Taber stiffness in the MD direction defined by JIS P 8125 is 2.5-4. .5 mN · m, opacity defined by JIS P 8138 is 97% or more, JAPAN TAPPI No. A recycled postcard paper having an internal bond strength of 500 to 700 KPa as defined in No. 18 and a fluorescence intensity observed with a fluorescence microscope of 110 or less. In the multi-layer structure by the multi-layered sheeting, used paper pulp containing 10% or more of fine fibers having an ash content of 10 to 20% and a number average fiber length of 0.1 mm or less is used for a layer in contact with the surface layer. Item 1. Recycled postcard paper according to item 1. The recycled postcard paper according to claim 1 or 2, wherein the waste paper pulp contains a fluorescently decolored material. The recycled postcard paper according to any one of claims 1 to 3, wherein a surface layer is 20% by mass or less of the whole postcard paper in the multi-layer structure formed by the multi-layer stitching.