JP2011206987A - Paper for reclaimed postcard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide paper for reclaimed postcards reducing paper waviness even when much used paper is compounded, reducing defects during offset printing, having excellent work efficiency and preventing paper feeding failure and paper peeling due to curls in an automatic sorting machine after posting the postcards.SOLUTION: The paper for the reclaimed postcards includes 40 mass% or more of used paper pulp, and is made by multilayer combination at least including three layers which are a surface layer, an intermediate layer and a back layer. The surface layer includes LBKP, and the intermediate layer includes used paper pulp more than that of the surface layer. In the paper for the reclaimed postcards, basis weight is 170-300 g/m, inner bond strength defined in JAPAN TAPPI No. 18 is 500 kPa or more, Taber stiffness defined in JIS P 8125 is 2.5 mN*m or more and a measurement value of paper moisture defined in JIS P 8127 is 6.0-8.0%.

Description

  The present invention relates to a recycled postcard paper containing 40% by mass or more of waste paper pulp. The postcard paper is printed with a postal code column, a stamp mark, or the like by offset printing on one side (address side), and then cut to the size of the postcard to become a postcard. The present invention relates to a postcard paper before offset printing.

  In recent years, the use of waste paper pulp has become an important theme from the viewpoint of maintaining the global environment, and postcards using waste paper pulp regenerated from waste paper are also required in postcards. At present, small-scale activities to produce 100% recycled postcards using recycled paper pulp derived from milk cartons are being carried out, but they are mainly made by hand-drawing, and mass production is difficult. Moreover, it is impossible to produce a homogeneous product. Some recycled postcards are manufactured by mechanical papermaking. However, in order to satisfy various printability, writing suitability, whiteness, etc., it was necessary to reduce the blending amount of the used paper.

  When waste paper pulp is blended with postcard paper, if the amount is small, a decrease in whiteness is allowed. However, when waste paper pulp is contained in an amount of 40% by mass or more, it is because of dust contained in waste paper. However, the decrease in whiteness is remarkable, and a postcard paper that is acceptable as a postcard cannot be obtained. Increasing the capacity of bleached paper and dust removal treatment of used paper pulp results in postcard paper with improved whiteness. However, since waste paper pulp contains many fluorescent substances that cannot be removed by waste paper processing including a general deinking process in addition to dust, it is easy to misidentify stealth barcodes used in postcard sorting operations. A stealth barcode is a barcode that is added to the address of the collected postcards using invisible ink. The barcode is read and selected by an automatic sorting machine. If it is strong, there will be many cases of misidentification. Waste paper pulp with almost no fluorescent substance remaining is extremely small, and when such pulp is gathered up to 40% by mass or more, whiteness and suitability of an automatic reader are acceptable, but only special waste paper pulp is selected. This is not preferable from the viewpoint of maintaining the global environment.

  Various techniques have been disclosed for postcards containing wastepaper pulp, but the postcard with 40% by weight or more of wastepaper pulp has not been put into practice. For example, there is a proposal for a postcard paper that is made by multi-layered three or more layers and uses waste paper pulp inside (see Patent Documents 1 and 2), but the described postcard paper is made of waste paper pulp. The blending amount is 30% by mass or less of the paper, and the evaluation as a postcard describes only printability. However, nothing is disclosed about various problems when waste paper pulp is blended by 40% by mass or more.

Japanese Patent No. 2763868 Japanese Patent No. 3253259

  Recycled postcard paper containing 40% by weight or more of waste paper pulp in the paper was manufactured, and there was a problem that paper could not be fed or had a printing defect during offset printing on the address side. During the sorting by the automatic sorter, it has been found that there are troubles such as paper feeding failure and paper peeling. It is also necessary for the postcard obtained from the recycled postcard paper to have recordability during ink jet recording. The present invention aims to solve these problems.

  As a result of intensive studies to solve the above problems, the present inventors have found that this can be achieved by satisfying the following constitution and physical properties.

“Configuration of recycled postcard paper”
The present invention is a recycled postcard paper containing 40% by mass or more of waste paper pulp, and is made by multi-layer stitching having at least a surface layer, a middle layer, and a back layer. At least three layers of the surface layer, the middle layer, and the back layer are, for example, those made by multi-layered stitching having five layers of the surface layer, the front layer, the middle layer, the back layer, and the back layer. Also includes papers. 40% by weight of recycled paper pulp is obtained by adopting multi-layer paper making of 3 or more layers, making the surface layer essential LBKP, making waste paper pulp essential in the middle layer, and satisfying the condition that the middle layer contains more waste paper pulp than the surface layer. Even if it mix | blends above, it can be set as the paper for postcards which reduced the influence of the dust and fluorescent substance which remain | survive in waste paper pulp.

The surface layer needs to contain LBKP. By including LBKP, the suitability of the automatic reader is improved.
The middle layer contains waste paper pulp and contains more waste paper pulp than the surface layer. Since the surface layer containing LBKP as an essential component is employed, the waste paper pulp used for the middle layer may contain dust or a fluorescent material.
Moreover, it is preferable to use recycled paper pulp for the inner layers other than the surface layer and the back layer, such as the front and lower layers and the back and lower layers, because it becomes a postcard paper in which the amount of used paper pulp is increased.
The back layer is not particularly limited with respect to the blending of the pulp, but it is preferable to use the same paper material as that of the surface layer because curling can be prevented.

“Physical properties of recycled postcard paper”
The recycled postcard paper of the present invention uses a paper base material having three or more layers as described above, and further has a basis weight of 170 to 300 g / m ² , JAPAN TAPPI No. The internal bond strength specified by 18 is 500 kPa or more, the Taber stiffness specified by JIS P 8125 is 2.5 mN · m or more, and the paper moisture is a measured value specified by JIS P 8127. It is necessary to satisfy that it is 0.0%.

The basis weight needs to be 170 to 300 g / m ² for the feeling of mass as a postcard, the texture, and the paper feedability of an inkjet printer. The basis weight of each layer including the surface layer, the middle layer, and the back layer is adjusted so as to satisfy this condition. In addition, since the middle layer contains a large amount of waste paper pulp, it is necessary to adjust the basis weight of the surface layer to such an extent that it is not affected by fluorescent substances, dust, and low whiteness.

  The internal bond strength needs to be 500 kPa or more. Since the recycled postcard paper is manufactured by multilayer papermaking, the adhesive strength between each layer is insufficient, and more than 40 mass% of wastepaper pulp is used, so fine fiber components derived from wastepaper pulp In many cases, paper dust at the time of cutting, paper peeling at the time of processing by offset printing or automatic sorting machine, or the like is likely to occur. In the present invention, these can be solved by setting the internal bond strength to 500 kPa or more. The upper limit of the internal bond strength is not particularly limited, but is preferably 700 kPa or less. When it exceeds 700 kPa, the adhesive cost in the layer and between the layers is increased, which is not practical.

  In addition, the Taber stiffness specified by JIS P 8125 in the paper machine flow direction (MD direction) needs to be 2.5 mN · m or more. 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 during delivery. The upper limit is not particularly limited, but if it exceeds 4.5 mN · m, there is a risk of poor conveyance in the automatic sorting machine, so it is preferably 4.5 mN · m or less. In particular, the stiffness with a large amount of waste paper pulp tends to decrease. As a method for adjusting the stiffness, the decrease in the stiffness can be suppressed by adjusting the blending amount of the used paper other than the surface layer, the ash content, and the fine fiber content. Furthermore, the rigidity of the flow direction (MD) of the papermaking machine can be adjusted by adjusting the strength of the papermaking machine, adjusting the J / W ratio during papermaking, adjusting the inlet concentration, and the like.

  However, even for recycled postcard paper that satisfies the conditions of basis weight, internal bond strength, and Taber stiffness, the paper feed process in the paper feed process is required for offset printing of postal code fields and stamp marks. It was found that defects, poor adhesion with the printing plate, etc. occurred, resulting in a significant decrease in operability and insufficient print quality. After investigating the cause, it was found that such a trouble would occur when the recycled postcard paper wavy. In the waving, the paper base material rapidly absorbs moisture and the pulp fiber constituting the paper base absorbs and swells. In particular, in the direction perpendicular to the paper machine flow direction (MD direction) (lateral direction: CD direction). A large stretch occurs and appears as a wave. Normally, offset printing is performed with attention to humidity and the like so as not to generate undulations. Actually, offset printing can be performed without problems on recycled postcard paper with a small amount of waste paper pulp. However, in recycled postcard paper blended in an amount of 40% by mass or more, the amount of used paper pulp is large, so that the waviness is likely to occur and the tendency to cause troubles during printing is remarkable.

  Recycled postcard paper blended in an amount of 40% by mass or more, 23 ° C.-50% R.D. H-28 ° C-85% R.V. The equilibrium moisture of the H paper was measured and found to be 23 ° C.-50% R.D. For H, about 6.0%, 28 ° C.-85% R.D. H was found to change to about 11%. Therefore, as a result of testing the rippling of various papers at a printing company that performs offset printing, if the paper moisture is 6.0 to 8.0%, the rippling of recycled postcard paper can be suppressed to a small level and trouble can occur. I also found that it can be prevented. If the paper moisture exceeds 8.0%, the paper is not sufficiently dried, the surface strength of the address surface is weak in offset printing, and piling occurs.

About the present invention
The present invention must satisfy the above-described configuration and physical properties. That is, the present invention is as follows.
(1) Recycled postcard paper containing 40% by mass or more of waste paper pulp, and the recycled postcard paper is made by multi-layer stitching having at least three layers of a surface layer, a middle layer, and a back layer, and the surface layer is LBKP The middle layer contains waste paper pulp, the middle layer contains more waste paper pulp than the surface layer, the basis weight is 170 to 300 g / m ² , and JAPAN TAPPI No. The internal bond strength specified by 18 is 500 kPa or more, the Taber stiffness specified by JIS P 8125 is 2.5 mN · m or more, and the paper moisture is a measured value specified by JIS P 8127. Recycled postcard paper characterized by 0.0%.
(2) Recycled postcard paper as described in (1) which contains 50 mass% or more of waste paper pulp.
(3) The recycled postcard paper according to (1) or (2), which contains 60% by mass or more of waste paper pulp.
(4) The recycled postcard paper according to any one of (1) to (3), wherein the middle layer includes waste paper pulp derived from magazine waste paper, newspaper waste paper, and miscellaneous paper waste paper.
(5) The recycled postcard paper according to any one of (1) to (4), wherein the layer in contact with the surface layer contains waste paper pulp derived from Kent waste paper.
(6) The recycled postcard paper according to any one of (1) to (5), which has a recording layer on the surface of the back layer.

  Although the postcard paper of the present invention is a paper containing a large amount of waste paper pulp, it can perform offset printing on the address side without any problem, and has a good sorting ability with an automatic sorter. Furthermore, a postcard obtained from recycled postcard paper has recording suitability during ink jet recording.

The recycled postcard paper of the present invention contains 40% by mass or more of waste paper pulp, and is made by multi-layer stitching having at least three layers of a surface layer, a middle layer, and a back layer, the surface layer includes LBKP, and the middle layer is a waste paper. It contains pulp, the middle layer contains more waste paper pulp than the surface layer, the basis weight is 170 to 300 g / m ² , JAPAN TAPPI No. The internal bond strength specified by 18 is 500 kPa or more, the Taber stiffness specified by JIS P 8125 is 2.5 mN · m or more, and the paper moisture is a measured value specified by JIS P 8127. 0.0%.

  In the present invention, the material to be used is not particularly limited as long as the above configuration and physical properties are satisfied. The number of layers of multi-layer papermaking is determined by the basis weight, thickness, texture of each layer, composition of raw materials, amount applied, etc. for each recycled postcard paper. Each layer contains chemicals such as raw material pulp composition, freeness and sizing agent, sulfuric acid band, filler, etc. Since the type and addition rate can be changed, the quality characteristics of the front and back surfaces can be changed. For example, the front layer, middle layer, and back layer are mainly composed of the middle layer, and the front layer, front layer, lower layer, middle layer, back layer, and back layer are mainly blended with recycled paper pulp in each of the lower layer, middle layer, and back layer. The recycled postcard paper can contain 40% by mass or more, preferably 50% by mass or more, and more preferably 60% by mass or more.

  As a raw material of waste paper pulp, it is possible to use various waste papers. For example, white paper, ruled white, etc. that have been used once, but have very few printed parts, card, imitation, color, 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 special cutting, medium-quality anti-old, Kent Manila, etc. It can be obtained from general medium-sized waste paper such as used medium-quality waste paper, newspapers, magazines, and miscellaneous paper, and tea-based used paper such as cut tea, plain tea, miscellaneous bags, and cardboard.

  As a method for producing waste paper pulp, a known method is adopted and is not particularly limited. For example, the above waste paper is mixed and disaggregated with water or an aqueous solution containing an alkali component such as sodium hydroxide. After that, in the dust removal process (cleaner or screen), foreign matters other than pulp fibers are removed, and after the ink separation process called a flotator, the bleaching process is performed to achieve the desired whiteness, and then the binder and disperser are used. It can be obtained through a dispersion step of finely dispersing with a so-called disperser. Moreover, the washing | cleaning process can also be provided in any location in this process. In the cleaning step, for example, a cleaning device such as a DNT washer, a compact washer, a hole washer, a vario split, an SP filter, a DP cosmo, a cap washer can be appropriately used.

  The surface layer needs to contain LBKP. By including LBKP, the suitability of the automatic reader is improved. The use of LBKP is preferably used as a main component of the pulp component because smoothness is improved and the texture is excellent, and 100% by mass of LBKP is preferably blended. On the surface layer, as long as the effects of the present invention are not impaired, chemical pulp such as waste paper pulp, NBKP, and SP, mechanical pulp such as SGP, RGP, BCTMP, and CTMP, or non-like materials such as Kefna, bamboo, straw, and hemp Organic synthetic fibers such as wood pulp, polyamide fibers, polyester fibers, and polynosic fibers, and inorganic fibers such as glass fibers, ceramic fibers, and carbon fibers can also be used in combination. When using waste paper pulp together, it is necessary to limit the blending amount to a range that does not interfere with the automatic reader. However, waste paper pulp that has been fluorescently decolored from waste paper pulp that contains fluorescent material, or that does not contain or contain fluorescent material Waste paper pulp derived from a small amount of waste paper is a preferred waste paper pulp because the blending amount can be increased.

  The fluorescence decoloring treatment of waste paper pulp here refers to 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, with 100% used paper, there is a risk of problems due to insufficient rigidity in the automatic sorting processor, so at present, the upper limit is about 80% by weight of used paper pulp.

  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, in the polyvalent metal treatment, for example, an aluminum foil is inserted into the waste paper pulp slurry, and the treatment can be performed at 20 ° C. for 24 hours, so that the fluorescence can be extinguished. 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. The 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. Come out.

  The back layer is not particularly limited with respect to the blending of the pulp, but it is preferable to use the same paper material as that of the surface layer because curling can be prevented. In addition, when LBKP is included in the back layer, the back layer can also show suitability for the automatic reader, and the case where the back layer is the address side and the front layer is the communication side is one of the embodiments of the present invention.

The middle layer contains waste paper pulp and contains more waste paper pulp than the surface layer. Since the surface layer containing LBKP as an essential component is employed, the waste paper pulp used for the middle layer may contain dust or a fluorescent material. Waste paper pulp derived from general medium waste paper such as newspapers, magazines, miscellaneous paper, etc., which has a small burden on the global environment due to the deinking agent and bleaching agent, can be used positively. In the case where the surface layer is affected by dust or fluorescent material of used paper pulp used in the middle layer, other used paper pulp or non-used paper pulp may be used in combination in the middle layer. Of course, it is also possible to use a waste paper pulp that has been subjected to fluorescence decoloring treatment exemplified in the surface layer, a pulp derived from waste paper that does not contain a fluorescent material, and a waste paper pulp derived from waste paper with a small amount of fluorescent material.
In the middle layer, chemical pulp such as LBKP, NBKP, and SP, mechanical pulp such as SGP, RGP, BCTMP, and CTMP, or non-wood pulp such as kefna, bamboo, straw, hemp, polyamide fiber, polyester fiber, polynosic fiber Organic synthetic fibers such as glass fibers, ceramic fibers, carbon fibers, and other inorganic fibers can be appropriately blended.

  Moreover, it is preferable to use recycled paper pulp for the inner layers other than the surface layer and the back layer, such as the front and lower layers and the back and lower layers, because it becomes a postcard paper in which the amount of used paper pulp is increased. In addition, the middle layer, the front lower layer, and the back lower layer do not need to be the same paper material, the compounding quantity of used paper pulp may differ, and the kind of used paper pulp to use may differ. For example, if waste paper pulp with a high dust content is used in the middle layer and less waste paper pulp is used in the front and lower layers, the effect on the front and back layers can be suppressed. It is also possible to use waste paper pulp that was difficult to use. Mechanical pulp can also be blended in the middle layer, the front lower layer and the back lower layer in order to improve the cushioning properties of the postcard paper.

The layer in contact with the surface layer (the middle layer in the case of three-layer stitching and the lower layer in the case of five-layer stitching) preferably contains 8% or more and 20% or less of fine fibers of 0.1 mm or less. The surface layer contains a lot of good quality LBKP, and the layer in contact with the surface layer contains a lot of waste paper pulp, so the strength between the layers of the combined portion tends to decrease. By making the fine fibers of 0.1 mm or less in the waste paper pulp of the layer in contact with the surface layer 8 to 20%, it becomes possible for the surface layer and the surface layer or the middle layer fibers to be entangled to suppress a decrease in internal bond strength. .
The fine fiber referred to here 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”.

  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. Waste paper pulp is preferably used after being processed to 250 to 450 ml by Canadian Standard Freeness. By setting the amount to 450 ml or less, it is possible to prevent the internal bond strength from being lowered, and to stop beating so as to be in the range of 250 ml or more, it is possible to prevent a decrease in pulp yield and an increase in density of the base paper.

Further, the layer in contact with the surface layer preferably has an ash content of 5% to 15%. By setting it to 5% or more, cushioning properties are improved, and by setting it to 15% or less, a decrease in internal bond strength can be suppressed. It is more preferable to satisfy both the above ash content and the amount of fine fibers of 0.1 mm or less. In addition, it is preferable from the point of effective utilization of resources that ash content is a thing derived from raw material waste paper. The amount of ash derived from the used waste paper can be adjusted in the cleaning process of the used paper pulp.
The waste paper pulp used for the layer in contact with the surface layer preferably includes waste paper pulp derived from Kent waste paper.

  In each layer, a filler can be blended as necessary. 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 fiber and filler, various anionic, nonionic, cationic or amphoteric yield improvers, freeness improvers, paper strength enhancers, internal sizing agents, etc. An internal additive for papermaking 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 internal bond strength to 500 kPa or more, it is effective to add a paper strength enhancer as a method 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. Furthermore, the formulation of the paper strength enhancer also has an effect of increasing the Taber stiffness.

  The papermaking method is multi-layered, and is not particularly limited as long as the physical properties specified in the present invention are satisfied. For example, an acidic papermaking method in which the papermaking pH is around 4.5, an alkaline filler such as calcium carbonate is mainly used. It can be applied to all papermaking methods including weakly acidic papermaking pH of about 6 to weakly alkaline neutral papermaking method of papermaking pH of about 9, paper machine is also a long net paper machine, twin wire paper machine, circle A net paper machine and a short net paper machine can be used in appropriate combination. The Taber stiffness in the flow direction (MD) of the papermaking machine can be adjusted by adjusting the J / W ratio and inlet concentration during papermaking, and the paper moisture can be adjusted depending on the drying conditions.

  The front and back surfaces of the paper base that has been made can also be subjected to surface sizing. For example, it is good to process with the liquid which contains starch, a surface sizing agent, etc. suitably. Further, the surface of the paper substrate can be smoothed with a calendar or the like.

  The present invention relates to recycled postcard paper before offset printing, and the above physical properties need to be satisfied when the recycled postcard paper is used in an environment with an offset printing machine. Therefore, the recycled postcard paper has physical properties when it is stored and transported in a moisture-proof packaging, kept in moisture, and taken out of the moisture-proof packaging.

  In one embodiment of the recycled postcard paper of the present invention, an ink jet printer, an electrophotographic printer, or a recording layer capable of offset printing can be provided on the communication surface (the back surface of the address). The physical properties in this case are values in the state having the recording layer, and are physical properties when taken out from the moisture-proof packaging.

  Examples of the pigment used in the recording 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, non- Mineral pigments such as crystalline silica, magnesium aluminosilicate, particulate calcium silicate, particulate magnesium carbonate, particulate light calcium carbonate, white carbon, bentonite, zeolite, sericite, smectite, polystyrene resin, styrene-acrylic co Organic pigments such as hollow type, solid type and through-hole type resins such as polymer resins, urea resins, melamine resins, acrylic resins, vinylidene chloride resins, and benzoguanamine resins can also be used. There is one of The two or more kinds appropriately selected and used.

  As the adhesive for the recording layer, a water-soluble and / or water-dispersible polymer compound can be used, 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, soy protein, natural rubber, polyvinyl alcohol, isoprene, neoprene, polybutadiene, etc. Polyalkylenes such as polydienes, polybutene, polyisobutylene, polypropylene, and polyethylene, vinyl polymers such as vinyl halide, vinyl acetate, styrene, (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamide, and methyl vinyl ether 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 mixing ratio of the adhesive in the recording layer is in the range of 5 to 50 parts by weight (solid part) with respect to 100 parts by weight of pigment (solid part). Incidentally, if it is less than 5 parts by weight, the strength of the coating film of the recording layer is weak, which may cause the recording layer to peel off. On the other hand, if it exceeds 50 parts by weight, printing blurring may occur during ink jet printer printing, and blistering may occur during electrophotographic printer printing.

  In this coating liquid, in addition to these pigments and adhesives, various auxiliary agents such as ink fixing agents, surfactants, pH regulators, viscosity modifiers, softeners, gloss imparting agents, waxes, dispersants, Flow modifier, antistatic agent, stabilizer, antistatic agent, cross-linking agent, sizing agent, fluorescent brightener, colorant, UV absorber, antifoaming agent, water-resistant agent, plasticizer, lubricant, preservative, A fragrance | flavor etc. can also be used suitably as needed. The ink fixing agent increases the water resistance of the recorded matter output by the ink jet printer, and examples thereof include cationic compounds such as cationic resins and polyvalent metal salts known in the field of ink jet recording paper.

Laydown in the case of providing the recording layer in correspondence plane is preferably 1 to 30 g / ^{m 2,} more preferably 1 to 10 g / ^{m 2.} If the coating amount is less than 1 g / m ² , the unevenness on the surface of the sheet-like paper substrate cannot be sufficiently covered, and the acceptability of the printing ink may be significantly reduced. On the other hand, if it exceeds 30 g / m ² , the operability such as the drying property during coating deteriorates, and the production cost may increase.

  As a coating method for forming the recording layer, generally known coating apparatuses such as blade coaters, air knife coaters, roll coaters, reverse roll coaters, bar coaters, curtain coaters, die slot coaters, gravure coaters, Champlex coaters, brushes A device such as a coater, a two-roll or metering blade type size press coater, a bill blade coater, a short dwell coater, a gate roll coater or the like is appropriately used.

  The recording layer may have a multilayer structure by providing one layer or two or more intermediate layers as necessary. In the case of a multi-layer structure, each coating solution need not be the same or the same coating amount, and may be appropriately adjusted and blended according to a required quality level, and is not particularly limited.

  Furthermore, it is possible to provide, on the recording layer, a gloss developing layer mainly composed of fine particles capable of developing an inorganic or organic gloss and an organic or inorganic binder.

  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 the binder 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 acid ester and methacrylic acid 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.

Various coaters 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 for coating the glossy layer coating liquid. If the coating amount of the glossy layer is 0.5 g / m ² or more in terms of the dry coating amount, the gloss is developed.

  In the recycled postcard paper of the present invention, the recording layer or glossy layer can be finished by a casting method. The casting method is a method in which a coating liquid for forming a recording layer or a gloss developing layer is applied, and the coated surface is pressed against a heated mirror roll (cast drum) while the coated surface is in a wet state. It is a method that forms a surface with improved glossiness by copying the surface shape of the mirror roll on the surface of the coating layer, and then applying a wet method depending on the drying and solidification state of the coating layer when it is pressure-bonded to the cast drum. , Gelation method and rewet method. 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 cost reduction, and it is appropriately selected according to the purpose.

When a recording layer or a recording layer and a glossy expression layer are provided on the communication surface side, curling is likely to occur on the communication surface side. In this case, if a coating liquid mainly composed of starch is used on the destination surface side, This is preferable because curling can be suppressed. In addition, in order to impart inkjet recording suitability to the address surface, it is preferable to use a coating liquid in which starch and polyvinyl alcohol are used in combination. Because the polyvinyl alcohol is swollen by the ink, the ink jet ink is quickly absorbed by the paper base material, and ink jet recording suitability suitable for printing characters and the like is obtained. Further, it is preferable to use a surface sizing agent in combination since ink blurring can be suppressed.
Examples of the starch include cationic starch, amphoteric starch, oxidized starch, enzyme-modified starch, thermochemically modified starch, esterified starch, etherified starch, etc., and polyvinyl alcohol includes saponification degree, polymerization degree, Silylca modification etc. can also be used. Examples of the surface sizing agent include styrene-acrylic, styrene-maleic acid polymers, and olefinic surface sizing agents.

  As for the compounding quantity of starch, polyvinyl alcohol, and a surface sizing agent, 5-20 mass parts of polyvinyl alcohol and 2-15 mass parts of surface sizing agents are preferable with respect to 100 mass parts of starch. Polyvinyl alcohol is preferably 5 parts by mass or more in order to increase the ink absorbability during ink jet recording and speed up drying, and when it is 20 parts by mass or less, the adhesiveness with the recording layer on the communication surface is suppressed, This is preferable because double feeding is less likely to occur. When the surface sizing agent is used in an amount of 2 parts by mass or more, it is preferable because it can prevent blurring at the time of ink jet recording, and by setting it to 15 parts by mass or less, it is preferable to prevent the drying property of the ink from being deteriorated. .

  In the coating solution for the address side, a polyoxyethylene type, sorbitan type, sulfonate type, quaternary ammonium salt, betaine type surfactant, antistatic agent, salt, and sodium sulfate are added as a conductive agent. I can do it. Other components include natural or semi-synthetic polymer compounds such as natural rubber, polydienes such as polyisoprene, polyneoprene and polybutadiene, polyalkenes such as polybutene, polyisobutylene, polypropylene and polyethylene, vinyl halides, vinyl acetate, Styrene, (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamide, vinyl-based polymers and copolymers such as methyl vinyl ether, styrene-butadiene-based, synthetic rubber latex such as methyl methacrylate-butadiene-based, Synthetic polymer compounds such as polyurethane resins, polyester resins, polyamide resins, olefin-maleic anhydride resins, melamine resins, and the like can be appropriately blended.

As a coating method for forming the coating liquid for the address surface, a known coating means can be adopted, and it is not particularly limited, but it is a coating facility installed in a coating machine for coating the communication surface. It is preferable to apply the address surface following the application and drying of the communication surface.
The coating amount of the coating liquid for the address surface is preferably 0.01 to 1.0 g / m ² (solid content). More preferably, it is 0.05-0.80 g / m < ² >. If it is less than 0.01 g / m ² , the target effect cannot be achieved. If it exceeds 1.0 g / m ² , the price increases, which is not preferable.

  After applying the coating solution for the address surface, the coating is dried by a normal drying process and finished so that the water content is 6.0 to 8.0%. In addition, it can be smoothed by a surface treatment process or the like. When the smoothing process is performed, it is performed by a smoothing processing device such as a normal super calendar, gloss calendar, soft calendar, etc., and is appropriately used on-machine or off-machine. The number, heating, etc. are also adjusted as appropriate according to a normal smoothing apparatus.

  The recycled postcard paper obtained as described above is cut into sheets having a size suitable for an offset printing machine, and is moisture-proof wrapped in a stacked state. The physical properties defined in the present invention must be satisfied when recycled postcard paper is used in an environment with an offset printing machine. Therefore, the recycled postcard paper has physical properties when it is stored and transported in a moisture-proof packaging, kept in moisture, and taken out of the moisture-proof packaging. The physical properties may be obtained immediately before moisture-proof packaging.

  In the cutting process, it is preferable to insert a guillotine blade from the address side. Inserting a guillotine blade from the address side has the effect of preventing cracking of the recording layer on the communication side.

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.

(Taber stiffness)
Taber stiffness was measured according to JIS P 8125 in the machine flow direction (MD direction) of the obtained recycled postcard paper.

(Internal bond strength)
The internal bond strength of the obtained recycled postcard paper was measured using the 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.

(Paper moisture)
The water content of the obtained recycled postcard paper was measured in accordance with JIS P 8127.

(Offset printing aptitude)
The obtained recycled postcard paper was measured for moisture, then laminated in units of 100 sheets, covered with a nylon bag, then externally packaged with polyla tea dress and sealed. The packaged recycled postcard paper is unpacked in five different printing press rooms with different installation locations and environments, and four-color flat-format offset printing is performed to eliminate paper feed defects and printing section defects during printing. Observed and evaluated according to the following criteria.
(1) Paper feedability during printing ○: No paper feed failure is observed.
Δ: Slight feeding failure is observed, but there is no practical problem.
X: Poor paper feed occurs and causes a practical problem.
(2) Print defect ○: No printed portion defect is observed.
Δ: Printed portion defects are slightly observed, but there is no practical problem.
X: Printed portion defects are severely generated and become a practical problem.

(Evaluation of paper peeling and paper feed failure when processing automatic sorting machine after posting)
The recycled postcard paper after the 4-color machine flat format offset printing according to the present invention was processed by an automatic sorting machine, observed for edge peeling and paper feed failure, and evaluated according to the following criteria.
(1) Edge paper peeling ○: No paper peeling at all.
Δ: Paper peeling is slightly observed, but there is no practical problem.
X: Peeling of paper is severe, which causes a practical problem.
(2) Paper feed failure ○: No paper feed failure is observed at all.
Δ: Slight feeding failure is observed, but there is no practical problem.
X: The paper feeding failure is severe, which causes a practical problem.
(3) Readability The fluorescence intensity of the address surface was evaluated by quantifying it by the following method.
○: Stable reading is possible.
×: “Fluorescence intensity” that may be misread
Using a fluorescent microscope (manufactured by ECLIPSE E600 NIKON), the address surface is irradiated with (365 nm: red fluorescence) to capture the reflected image. Next, the intensity of (365 nm: red fluorescence) is quantified using analysis software (IO-MATE) for the captured image. If the fluorescence intensity (red fluorescence 365 nm) observed with a fluorescence microscope is 110 or less, it can be read stably.

(Evaluation of ink jet aptitude for communication)
Using a dye ink type ink jet printer (Seiko Epson G860) and a pigment ink type ink jet printer (Seiko Epson PC-G930), 100 postcards of the present invention are printed in full color on the communication surface, and the image quality The paper feeding suitability and curl were confirmed and evaluated according to the following criteria.
(1) Image quality The state of image blur was visually observed.
◯: Good with no bleeding.
Δ: Slight bleeding is observed, but there is no practical problem.
X: Severe bleeding, causing a problem in practical use.
(2) Feeding suitability The occurrence of non-feed troubles due to double feeding and curling during output was evaluated.
○: No trouble occurred.
Δ: Five troubles are observed, but there is no practical problem.
X: Trouble occurs over 5 sheets, which is a practical problem.
(3) Paper discharge suitability An evaluation was made of paper jams and print stains due to curling during output.
○: No trouble occurred.
X: Trouble occurs over 5 sheets, which is a practical problem.

(Evaluation of ink-jet aptitude for address)
With a dye ink type ink jet printer (PM-G860 manufactured by Seiko Epson Corp.) and a pigment ink type ink jet printer (PX-G930 manufactured by Seiko Epson Corp.), characters are printed in monocolor on the address side of 100 postcards of the present invention. Then, the print quality, paper feedability, and curl were confirmed and evaluated according to the following criteria.
(1) Print quality The state of bleeding of the print was visually observed.
◯: Good with no bleeding.
Δ: Slight bleeding is observed, but there is no practical problem.
X: Severe bleeding, causing a problem in practical use.
(2) Feeding suitability The occurrence of non-feed troubles due to double feeding and curling during output was evaluated.
○: No trouble occurred.
Δ: Five troubles are observed, but there is no practical problem.
X: Trouble occurs over 5 sheets, which is a practical problem.
(3) Paper discharge suitability An evaluation was made of paper jams and print stains due to curling during printing.
○: No trouble occurred.
X: Trouble occurs over 5 sheets, which is a practical problem.

"Pen writing size evaluation method"
JAPAN TAPPI No. 12 was measured.

"Production method of waste paper pulp"
(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 pulp had an ash content of 10.5% and fine fibers of 0.1 mm or less in 13%.

(Waste paper pulp B)
The magazine waste paper (ash content 20.3%) was disaggregated with a pulper, passed through a dust removing device (cleaner and screen), the freeness was adjusted to 350 ml with a double disc refiner, and waste paper pulp B was obtained. The pulp had an ash content of 19.5%, and fine fibers of 0.1 mm or less were 9.5%.

(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 26.0%, and the fine fibers of 0.1 mm or less were 30%.

(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 4.5%, and the fine fibers of 0.1 mm or less were 7.0%.

(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
"Creating Paper"
Recycled postcard paper having a paper thickness of 220 μm composed of five layers was prepared using a multi-layered long web paper machine with the following materials and conditions. In addition, 0.3 g / m ^{2 of a} 3.0% aqueous solution of oxidized starch was applied between the surface layer, the front layer, the lower layer, and the middle layer, and the interlayer between the middle layer, the back layer, and the back layer, the back layer. Each was coated with 0.3 g / m ^{2 of a} 3.0% aqueous solution of oxidized starch in an absolutely dry solid content.
Moreover, as a sizing solution for the front and back size treated paper, the ratio of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) and surface sizing agent (trade name: Polymaron 1329K, manufactured by Arakawa Chemical Industries, Ltd.) is 9: A 13.5% mixed aqueous solution having a solid content of 1 was applied to the front and back surfaces with a load blade so that the dry solid content was 2 g / m ² , dried, and smoothed with a calendar. Subsequently, it was cut into a predetermined size for an offset printing machine to obtain a recycled postcard paper. The paper moisture was adjusted to 7.0%.

(Surface and back layers)
Basis weight: 35 g / m ²
Pulp formulation: 100% hardwood bleached kraft pulp (LBKP) with a freeness adjusted to 520 ml.
Sizing agent: Add rosin emulsion sizing agent in solid form and 0.3% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.025% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O _{3 and} 0.5% added to pulp.
(Front lower layer and back lower layer)
Basis weight: 40 g / m ²
Pulp formulation: 100% recycled paper pulp A.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.0% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: 0.07% added to pulp with high molecular weight polyacrylamide.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.
(Middle layer)
Basis weight: 40 g / m ²
Pulp composition: Waste paper pulp B 100%
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Yield improver: High molecular weight polyacrylamide in solid form and 0.02% added to pulp.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.

Example 2
"Creating Paper"
Recycled postcard paper having a paper thickness of 220 μm composed of three layers was prepared using a multi-layered long web paper machine with the following materials and conditions. In addition, 0.3 g / m ^{2 of a} 3.0% aqueous solution of oxidized starch was applied between the surface layer, the middle layer, and the back layer, respectively, in an absolutely dry solid content, and they were combined.
Further, the ratio of the oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) and the surface sizing agent (trade name: Polymaron 1329K, manufactured by Arakawa Chemical Industries, Ltd.) as the size liquid on the front and back surface of the front and back size treated paper is 9: 1. The solid aqueous solution having a solid content of 13.5% was applied to the front and back surfaces with a load blade so that the dry solid content was 2 g / m ² , dried, and smoothed with a calendar. Subsequently, it was cut into a predetermined size for an offset printing machine to obtain a recycled postcard paper. The paper moisture was adjusted to 7.0%.

(Surface and back layers)
Basis weight: 50 g / m ²
Pulp formulation: 100% hardwood bleached kraft pulp (LBKP) with a freeness adjusted to 520 ml.
Sizing agent: Add rosin emulsion sizing agent in solid form and 0.3% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.025% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O _{3 and} 0.5% added to pulp.
(Middle layer)
Basis weight: 90 g / m ²
Pulp formulation: Waste paper pulp A 100%
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Yield improver: High molecular weight polyacrylamide in solid form and 0.02% added to pulp.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.

Example 3
A recycled postcard paper was prepared by combining five layers in the same manner as in Example 1 except that the formulation of each layer was changed to the following. The paper moisture was adjusted to 7.0%.
(Surface and back layers)
Basis weight: 35 g / m ²
Pulp blend: Hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp E50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 0.3% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.025% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O _{3 and} 0.5% added to pulp.

(Front lower layer and back lower layer)
Basis weight: 40 g / m ²
Pulp blend: Hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp E50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.0% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: 0.07% added to pulp with high molecular weight polyacrylamide.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.

(Middle layer)
Basis weight: 40 g / m ²
Pulp composition: Waste paper pulp B 100%
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Yield improver: High molecular weight polyacrylamide in solid form and 0.02% added to pulp.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.

Example 4
Recycled postcard paper was prepared in the same manner as in Example 1 except that the pulp of all layers was 30% hardwood bleached kraft LBKP, 70% waste paper pulp E, and the paper moisture was adjusted to 7.5%.

Example 5
On the communication side of the recycled postcard paper obtained in Example 1, the following recording layer coating solution was coated with an air knife coater so that the solid content was 5 g / m ² and dried, Subsequently, the following coating liquid for the address surface is adhered to the address surface with the attached roll coater (water coating device), the paper moisture is adjusted to 7.0%, and then the predetermined size is used for the offset printer. The paper was cut to make a recycled postcard paper. In addition, cutting was performed from the address side.

<Coating liquid for recording layer>
Amorphous silica (trade name: Fine Seal (R) X-30, manufactured by Tokuyama Corporation): 80 parts light calcium carbonate (trade name: Tama Pearl TP121, manufactured by Okutama Kogyo Co., Ltd.): 20 parts cationic resin (trade name: UNISENCE CP103 10 parts surfactant (trade name: Emulgen A-60, manufactured by Kao Corporation): 0.3 parts vinyl acetate adhesive (trade name: Polysol AM3150, Showa Polymer Co., Ltd.): 15 parts Polyvinyl alcohol (trade name: PVA R-1130, manufactured by Kuraray Co., Ltd.): 25 parts The coating liquid was adjusted to 20%.

<Coating solution for address surface>
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.): 13.5 parts NaCl (conductive agent): 6.5 parts The coating liquid was adjusted to 4%.

Comparative Example 1
In Example 1, a recycled postcard paper was prepared in the same manner as in Example 1 except that the paper moisture was adjusted to 5%.

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. The paper moisture was adjusted to 7.0%.

Comparative Example 3
Recycled postcard paper was prepared in the same manner as in Example 1 except that the used paper pulp used in the front and lower layers and the back lower layer in Example 1 was changed to used paper pulp D. The paper moisture was adjusted to 7.0%.

Comparative Example 4
In Example 2, a recycled postcard paper was prepared in the same manner as in Example 2 except that the paper moisture was adjusted to 9%.

Example 6
Recycled postcard paper with 5 layers was obtained in the same manner as in Example 1 except that the formulation of each layer was changed as follows. The paper moisture was adjusted to 6.5%.
Recycled postcard paper was made.
(Surface and back layers)
Basis weight: 35 g / m ²
Pulp formulation: Hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp F 50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 0.3% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.025% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O _{3 and} 0.5% added to pulp.

(Front lower layer and back lower layer)
Basis weight: 40 g / m ²
Pulp formulation: Hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp F 50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.0% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: 0.07% added to pulp with high molecular weight polyacrylamide.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.

(Middle layer)
Basis weight: 40 g / m ²
Pulp composition: Waste paper pulp B 100%
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Yield improver: High molecular weight polyacrylamide in solid form and 0.02% added to pulp.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.

Example 7
A recycled postcard paper was prepared by combining five layers in the same manner as in Example 1 except that the prescription for each layer was changed to the following. The paper moisture was adjusted to 7.0%.
(Surface and back layers)
Basis weight: 35 g / m ²
Pulp formulation: Hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp G 50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 0.3% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: High molecular weight polyacrylamide is added and 0.025% of pulp is added.
Sulfuric acid band: 8% aqueous solution as Al ₂ O _{3 and} 0.5% added to pulp.

(Front lower layer and back lower layer)
Basis weight: 40 g / m ²
Pulp formulation: Hardwood bleached kraft pulp (LBKP) 50%, waste paper pulp G 50%.
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.0% to pulp.
Paper strength enhancer: Polyacrylamide in solid form and 5.0% added to pulp.
Yield improver: 0.07% added to pulp with high molecular weight polyacrylamide.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.

(Middle layer)
Basis weight: 40 g / m ²
Pulp composition: Waste paper pulp B 100%
Sizing agent: Add rosin emulsion sizing agent in solid form and 1.5% of pulp.
Yield improver: High molecular weight polyacrylamide in solid form and 0.02% added to pulp.
Sulfuric acid band: As an Al ₂ O ₃ solution, an 8% aqueous solution product is added to the pulp in an amount of 10.0%.

Example 8
Using the recycled postcard paper obtained in Example 1 as a support, it was produced as follows to produce a recycled postcard paper having a recording layer and a glossy layer.
<Creation of recording layer>
A 5% borax solution was applied to the communication surface of the recycled postcard paper obtained in Example 1 with a bar so that the dry weight was 1 g / m ² and dried. Next, the following recording layer coating solution was applied and dried with a die coater so that the dry mass was 12 g / m ² . On the surface of the recording layer, the gloss developing layer described below was applied at the nip portion of the mirror drum so that the dry coating amount was 1 g / m ^2, and pressed and dried to the heated mirror drum as it was. Subsequently, the address surface coating liquid having the following prescription was attached to the address surface at 0.5 g / m ² with an absolutely dry solid content using the attached roll coater (water coating device), and then the moisture of the paper was supplied to the humidifier. Adjusted to 7.0%. Subsequently, it was cut into a predetermined size for an offset printing machine to obtain a recycled postcard paper. In addition, cutting was performed from the address side.

“Adjusting the recording layer coating solution”
Commercially available vapor phase 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, then nanomizer (trade name: Nanomizer, Using a nanomizer), pulverization and dispersion were repeated, and after classification, a 10% dispersion having an average secondary particle diameter 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 recording layer coating solution having a solid content concentration of 12%.

"Adjustment of glossy layer coating liquid"
Composite emulsion of acrylic emulsion and glass colloidal silica having a glass transition point of 100 ° C. (trade name: Aquabrid 906, manufactured by Daicel Chemical Industries, Ltd., acrylic emulsion and colloidal silica are 20:80 by mass, and the particle size of the emulsion is 40 nm) 100 parts, casein 5 parts, thickener 6 parts, release agent (stearic acid) 5 parts were added and stirred, and water was further added to obtain a coating solution having a solid content concentration of 5%.
“Adjustment of coating solution for address surface”
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.): 13.5 parts NaCl (conductive agent): 6.5 parts A 4% coating solution containing the above formulation was prepared.

Example 9
Using the recycled postcard paper obtained in Example 4 as a support, it was produced as follows to produce a recycled postcard paper having a recording layer.
<Creation of recording layer>
A 5% borax solution was applied to the communication surface of the recycled postcard paper obtained in Example 4 with a bar so that the dry weight was 1 g / m ² and dried. Next, the following recording layer coating solution was coated with a die coater so as to have a dry mass of 12 g / m ^2, and was pressed onto a heated mirror drum and dried while in a wet state. Subsequently, the address surface coating liquid having the following prescription was attached to the address surface at 0.5 g / m ² with an absolutely dry solid content using the attached roll coater (water coating device), and then the moisture of the paper was supplied to the humidifier. Adjusted to 7.0%. Subsequently, it was cut into a predetermined size for an offset printing machine to obtain a recycled postcard paper. In addition, cutting was performed from the address side.

“Adjusting the recording layer coating solution”
Commercially available vapor phase 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, then nanomizer (trade name: Nanomizer, Using a nanomizer), pulverization and dispersion were repeated, and after classification, a 10% dispersion having an average secondary particle diameter 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%.
Cloth and

“Adjustment of coating solution for address surface”
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.): 13.5 parts NaCl (conductive agent): 6.5 parts A 4% coating solution containing the above formulation was prepared.

  As apparent from Tables 1 to 3, the recycled postcard paper of the present invention is excellent in offset printing suitability, automatic sorter processing suitability, communication surface and addressability ink jet suitability.

  The recycled postcard paper of the present invention is subjected to offset printing such as a postal code frame on the address side, and then cut to the size of the postcard to become a postcard. This postcard can be used for New Year's cards, direct mail, and the like because the communication side is suitable for image output by the ink jet recording method and the address side is suitable for character output by the ink jet recording method.

Claims (6)

Recycled postcard paper containing 40% by weight or more of waste paper pulp, and the recycled postcard paper is made by multi-layer stitching having at least three layers of a surface layer, a middle layer and a back layer, and the surface layer contains LBKP. The middle layer contains waste paper pulp, the middle layer contains more waste paper pulp than the surface layer, and has a basis weight of 170 to 300 g / m ² , JAPAN TAPPI No. The internal bond strength specified by 18 is 500 kPa or more, the Taber stiffness specified by JIS P 8125 is 2.5 mN · m or more, and the paper moisture is a measured value specified by JIS P 8127. Recycled postcard paper characterized by 0.0%. The recycled postcard paper according to claim 1, which contains 50% by mass or more of waste paper pulp. The recycled postcard paper according to claim 1 or 2, which contains 60% by mass or more of waste paper pulp. The recycled postcard paper according to any one of claims 1 to 3, wherein the middle layer includes waste paper pulp derived from waste magazine paper, newspaper waste paper, and miscellaneous paper waste paper. The recycled postcard paper according to any one of claims 1 to 4, wherein the layer in contact with the surface layer contains waste paper pulp derived from Kent waste paper. The recycled postcard paper according to any one of claims 1 to 5, further comprising a recording layer on the surface of the back layer.