JP2011062974A - Glossy postcard paper with multilayer structure for inkjet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glossy postcard paper for inkjet in which glossiness is high, foreign substances is few, writing property in an address face is excellent, problem of defect of reading barcodes by fluorescent light which increases when blending regenerated pulp is not caused, and printing adequacy such as printing strength is good, in the glossy postcard paper for inkjet produced by blending the regenerated pulp. <P>SOLUTION: In the glossy postcard with a multilayer structure for inkjet, the base paper has the multilayer structure constituted by three or more layers having a front face layer, one or more of middle layers and a rear face layer, wherein an ink receiving layer and glossiness developing layer are arranged on the front face layer, the base paper is exposed in the rear face layer, and the content of the regenerated pulp in the whole base paper is not less than 20 mass% and not more than 70 mass%. The regenerated pulp blending ratio of the middle layer is not less than 50 mass% and not more than 100 mass%, and the water absorbing capacity of the front face layer is not more than 30 g/m<SP>2</SP>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a glossy postcard paper for inkjet containing waste paper pulp, which has a high glossiness, a small amount of foreign matter, excellent writing performance with an aqueous pen on the address side, and printability such as printing strength. It relates to a good inkjet postcard paper.

  In recent years, as the ink jet recording system has spread to the general public, it has come to be used for postcards, and there is also a technique related to postcards for ink jet recording (see, for example, Patent Document 1 or Patent Document 2). .

  Postcards usually have a postal code frame, stamp pasting frame, lottery number for New Year's postcards with New Year's cards, etc. printed on the address side. There is a growing demand for printability.

  In recent years, it has been important for paper products to be recycled as environmental considerations, that is, it is important to add a large amount of waste paper pulp, and demands from users have increased.

  With regard to postcards containing waste paper pulp, for example, a technique using a specific filler or a technique focusing on the disaggregation freeness of the pulp to be used is disclosed (for example, see Patent Document 3 or Patent Document 4).

  Furthermore, a technique for forming a multilayer paper-jet ink jet paper is also disclosed (see, for example, Patent Documents 5 and 6 or Patent Document 7).

JP-A-10-297148 Japanese Patent Laid-Open No. 2005-67166 JP 2001-260527 A JP 2006-289813 A JP 2002-127582 A JP-A-8-267907 JP-A-8-258400

“Information Paper '95”, Paper Industry Times, April 20, 1995, p. 176 http: // www. post. Japanpost. jp / whats_new / 2008 / 0822_02_c01. pdf

When the ratio of waste paper pulp is increased, the following adverse effects occur.
1. Contamination increases due to the residual ink contained in waste paper pulp and the effects of dust that cannot be removed.
2. As recycling progresses, various strengths (for example, paper strength, internal bond strength, tensile strength, tear strength, burst strength, etc.) decrease due to the effects of keratinization and shortening of fibers.
3. In order to eliminate the above 2, it is necessary to use an excessive paper strength enhancer and to beat the pulp excessively, but as a result, the suitability for inkjet printing is lowered.
4). Surfactant such as deinking agent used in the used paper processing process remains, so that feathering occurs when the base paper is printed on the exposed address surface (feathering is described in Non-Patent Document 1). As described above, it represents bleeding on the surface of a paper base material in which a so-called ink receiving layer is not particularly provided.
5. Even when a glossy layer is provided, the penetration of the coating solution is large, resulting in low gloss.
6). A postcard prints a barcode with colorless and transparent fluorescent dye ink (invisible ink) when it passes through an automatic sorting machine on its address side (reads the zip code and address at the same time, and reads the read address information as a barcode) Since most of the used paper on the market uses fluorescent dyes, this will naturally result in postcard paper with high fluorescence intensity, so this barcode can be read. First, it causes troubles when it is automatically classified later (postcards are rearranged in order of delivery (route assembly)) (see, for example, Non-Patent Document 2).

  As a countermeasure for reducing the influence of the impurities of the base paper using waste paper pulp, there is a method of providing an ink receiving layer on the communication surface. However, on the address side, the influence of impurities in the waste paper pulp comes out as it is. As a countermeasure for reducing impurities in the waste paper pulp, there is a method of providing a waste paper processing step. However, since the dust removal in the waste paper treatment process is enhanced, and deinking chemicals and bleaching chemicals are increased, the waste paper pulp fibers are damaged and deteriorated. Damaged waste paper pulp becomes unsuitable for recycling. In particular, an increase in the deinking agent also adversely affects ink jet aptitude such as water pen bleeding and feathering.

  As a measure for increasing the printing strength, there is a method of increasing the surface strength, and as a means for that, there is an application of polyvinyl alcohol or the like having a high covering property. However, when the air permeability deteriorates and the casting process is performed, minute crater-like holes called pits are generated.

  Also, there is a method to improve the strength by pushing the pulp, but since the base paper becomes dense, the air permeability deteriorates and the crater-like holes called pits are generated when casting. .

  In addition, there is a method of using a sizing agent as a countermeasure against penetration of a coating liquid for providing a glossy expression layer on a support using waste paper pulp. However, in order to obtain the desired permeability, a large amount of sizing agent is required, and the substrate is not easily produced due to the occurrence of soiling in the production process and the cost.

  Recently, with the widespread use of inkjet printers and higher resolution, a photo-like high-definition image with high glossiness is desired on the side opposite to the address side, that is, the so-called communication side.

  As described above, there are a wide variety of characteristics required for postcards, and the prior art has not yet fully satisfied these characteristics.

  With the technique using the specific filler described in Patent Document 3 or Patent Document 4 or the technique focusing on the disaggregation freeness of the pulp to be used, the printing durability of the non-coated surface is poor and printing cannot be performed in practice.

  Furthermore, the glossy postcard paper for multilayer paper-jet inkjet described in Patent Literature 5, 6 or Patent Literature 7 does not touch on the composition of waste paper pulp, and this production method has the problem of sufficiently satisfying the above characteristics. It cannot be solved. In addition, no technology has been reported on ink jet postcards with high glossiness in ink jet postcards containing waste paper pulp.

  Therefore, as described above, the present invention is intended to solve the problems of the prior art, and relates to glossy postcard paper for inkjet containing a waste paper pulp. Glossy postcard for inkjet with excellent writing performance with brush and water-based pen, without causing the problem of barcode reading failure due to fluorescence that increases when waste paper pulp is included, and also with good printability such as printing strength. The purpose is to provide paper.

As a result of intensive studies, the present inventors have made the base paper into a multi-layered paper when the ratio of the used paper pulp in the whole base paper is 20% by mass or more and 70% by mass or less. By providing an expression layer and mixing a large amount of waste paper pulp with an intermediate layer containing 50% by weight or more of waste paper pulp, the glossiness is high, there are few contaminants on the front and back of the postcard, and printability such as printing strength is good. High glossy postcard paper for inkjet. Specifically, the glossy postcard paper for multilayer paper-jet according to the present invention is a multilayer paper-making of three or more layers in which the base paper has a surface layer, one or more intermediate layers, and a back layer, Provided on the surface layer is one or more ink-receiving layers, and a glossy expression layer formed by a cast coating method containing a pigment and a binder on the outermost layer of the ink-receiving layer, and the back layer Is a multilayer post-printing glossy postcard paper for ink-jet printing in which the base paper is in a bare state and the waste paper pulp content of the whole base paper is 20% by mass or more and 70% by mass or less. The blending ratio is 50% by mass or more and 100% by mass or less, and the water absorption of the surface layer (JIS P-8140: 1998, set time 15 seconds) is 30 g / m ² or less.

  In the glossy postcard paper for multilayer paper-jet inkjet according to the present invention, the surface gloss of the surface layer (JIS Z-8741: 1997, 20 degrees) is preferably 25% or more. When the glossiness is 25% or more, a photographic-like high-detail image can be printed.

In the glossy postcard paper for multilayer paper-jet ink according to the present invention, the dry coating amount of the glossy layer is preferably 3 to ²⁰ g / m2. By setting it as 3-20 g / m < ² >, a sufficient glossy surface can be formed.

  In the glossy postcard paper for multilayer paper-jet inkjet according to the present invention, it is preferable that the ratio of the used paper pulp in the surface layer is 0% by mass or more and less than 50% by mass. By setting the content to 0% by mass or more and less than 50% by mass, impurities can be concealed by the ink receiving layer, and the influence of residual surfactant and residual ash derived from waste paper is minimized, resulting in high Glossiness can be demonstrated.

  In the glossy postcard paper for multilayer paper-jet inkjet according to the present invention, the ratio of the used paper pulp in the back layer is preferably 0% by mass or more and less than 20% by mass. By setting the content to 0% by mass or more and less than 20% by mass, the influence of the deinking agent remaining on the waste paper pulp is reduced, and size can be imparted to the outermost part. As a result, the occurrence of feathering can be prevented.

  In the glossy postcard paper for multilayer paper-jet inkjet according to the present invention, it is preferable that the waste paper pulp blending ratio of the intermediate layer is higher than the waste paper pulp blending ratio of the front surface layer or the back surface layer. It is possible to prevent various adverse effects such as deterioration of appearance due to wastes derived from waste paper pulp on the front surface layer and the back surface layer of paper, reading failure in an automatic sorting machine, reading failure of various information, and brown color.

  The glossy postcard paper for multilayer paper-jet inkjet according to the present invention includes a case where the surface layer side is a communication surface and the back surface layer side is an address surface.

  The glossy postcard paper for multilayer paper-jet ink jet according to the present invention has a high glossiness and a small amount of impurities even when the waste paper pulp content ratio of the entire base paper is 20% by mass or more by taking the above configuration. It has excellent writing properties with a writing brush or water-based pen on the address side, and has good printability including printing strength. Further, there is no problem of barcode reading failure due to fluorescence which increases when the ratio of waste paper pulp is increased.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

The postcard paper for multi-layer inkjet according to the present embodiment is a multi-layer multi-layer paper having a base paper having a surface layer, one or more intermediate layers, and a back layer, on the surface layer, One or more ink-receiving layers, and a glossy layer formed by a cast coating method containing a pigment and a binder are provided on the outermost layer of the ink-receiving layer, and the back layer comprises a base paper A glossy postcard paper for multilayer paper-jet printing in which the waste paper pulp content of the entire base paper is 20% by mass or more and 70% by mass or less, and the intermediate layer has a waste paper pulp blending ratio of 50% by mass. % To 100% by mass and the water absorption of the surface layer (JIS P-8140: 1998, set time 15 seconds) is 30 g / m ² or less. Furthermore, in this embodiment, it is preferable that the used paper pulp compounding ratio of the intermediate layer is higher than the used paper pulp compounding ratio of the front surface layer or the back surface layer. In the multilayer post-printing ink jet postcard according to this embodiment, the case where the front surface layer side is a communication surface and the back surface layer side is an address surface will be described below.

  In this embodiment, the waste paper pulp content of the entire base paper is 20% by mass or more and 70% by mass or less. If it is less than 20% by mass, it becomes difficult to achieve the object of the present invention by recycling waste paper, increasing the recycling rate and considering the environment. The higher the proportion of waste paper pulp in the entire base paper, the higher the environmental consideration. However, in order to give good printing suitability such as printing strength, as described later, there are few contaminants, there is no bleeding after ink jet printing, excellent writing property with a brush on the address side, water-based pen, etc. The upper limit of the ratio of the used paper pulp in the entire base paper is preferably 70% by mass.

  When waste paper pulp is blended uniformly in the surface layer, intermediate layer, and back layer, or in the case of single-layer papermaking, impurities increase in correlation with the waste paper pulp blending ratio. Furthermore, if the ratio of the used paper pulp to the front surface layer or the back surface layer is increased, the impurities are further increased. Not only does the appearance worsen when the number of miscellaneous items increases, but in the case of the back layer, the postal code cannot be read by the automatic sorting machine, the lottery number of New Year's postcards with New Year's cards cannot be read, and the address becomes difficult to read. Such harmful effects occur. Therefore, the used paper pulp blending ratio of the intermediate layer is set to 50% by mass or more and 100% by mass or less. Furthermore, it is preferable that the recycled paper pulp compounding ratio of the intermediate layer is higher than the recycled paper pulp compounding ratio of the front surface layer or the back surface layer. When the proportion of waste paper pulp is increased, it is preferable to blend more waste paper pulp into the intermediate layer from the viewpoint of reducing the adverse effects of discoloration. Further, in order not to cause the problem of poor barcode reading due to the fluorescence that increases when the used paper pulp is included, it is preferable to use the used paper pulp for the intermediate layer which is further inside.

In addition, a waste paper pulp mixing | blending ratio is calculated by Formula 1.
(Equation 1) Waste paper pulp blending ratio (mass%) = used paper pulp blending amount / (virgin pulp blending amount + waste paper pulp blending amount) × 100

  Further, self-flowing waste paper is generated during production, but there is no problem even if this self-flowing waste paper is used. However, since the self-circulating waste paper substantially contains waste paper pulp even though it is not included in the amount of waste paper pulp, it is preferably used in the intermediate layer so as not to appear on the front and back of the base paper. Furthermore, when the ink receiving layer is applied on-machine, self-rotating paper with the ink receiving layer applied is used, so it can be used in the intermediate layer to reduce press part and dryer stains. More preferred. From the above, in the case of single-layer papermaking, it is disadvantageous not only in terms of impurities but also in terms of soiling of the paper machine in the papermaking process.

  When recycled paper pulp is blended uniformly in the surface layer, the intermediate layer, and the back layer, or in the case of single-layer papermaking, the printing strength decreases in correlation with the recycled paper pulp blending ratio. Furthermore, if the proportion of waste paper pulp in the back layer increases, the printing strength further decreases. When the printing strength decreases, not only quality problems such as paper peeling and picking, but also a blanket piling, etc. occur, which hinders printing workability.

  When the desired amount of recycled paper pulp can be achieved by blending recycled paper pulp only in the intermediate layer, that is, when the recycled paper pulp blending ratio of 20 to 70% by mass with respect to the entire base paper can be achieved, recycled pulp is not blended in the surface layer and the back surface layer. Also good.

  When it is desired to increase the ratio of the used paper pulp to the entire base paper or when the desired ratio is not reached only by adding the used paper pulp only to the intermediate layer, the used paper pulp can also be added to the surface layer. For example, it is a case where it is desired to set the ratio of the used paper pulp to the entire base paper to be 25% by mass or more. In this case, the waste paper pulp is blended so that the ratio of the waste paper pulp to the surface layer is less than 50% by mass, preferably less than 40% by mass, more preferably less than 30% by mass. Here, blending is determined based on a policy of increasing the proportion of waste paper pulp blended in the intermediate layer so that the proportion of waste paper pulp blended into the surface layer is less than 50% by mass. In the glossy postcard paper for multilayer paper-jet ink jet according to this embodiment, the ratio of the used paper pulp in the surface layer is preferably 0% by mass or more and less than 50% by mass. When the waste paper pulp content of the surface layer is 50% by mass or more, even if an ink receiving layer is provided, impurities cannot be concealed, and it becomes difficult to impart the size of the base paper surface due to the effect of the deinking agent remaining on the waste paper pulp. When the glossy layer is applied, the penetration becomes excessive and the glossiness is lowered. In addition, the negative effect of fading is likely to occur.

  When it is desired to further increase the ratio of the used paper pulp to the entire base paper, or when the used paper pulp is not reached simply by adding the used paper pulp to the intermediate layer and the surface layer, the used paper pulp can also be added to the back layer. For example, it is a case where it is desired to set the ratio of the used paper pulp to the entire base paper to be 30% by mass or more. In that case, the waste paper pulp is blended so that the ratio of the waste paper pulp to the back layer is less than 20% by mass, preferably less than 15% by mass. Here, the policy is to increase the ratio of waste paper pulp to be blended in the intermediate layer so that the ratio of waste paper pulp to the surface layer is less than 50% by mass and the ratio of waste paper pulp to the back layer is less than 20% by mass. Determine the formulation. In the glossy postcard paper for multilayer paper-jet inkjet according to the present embodiment, it is preferable that the ratio of the waste paper pulp in the back layer is 0% by mass or more and less than 20% by mass. If the recycled paper pulp content of the back layer is 20% by mass or more, not only will there be a lot of impurities, but the postal code will not be readable by the automatic sorting machine in the case of the back side of the address. Etc. will be unreadable, and it will be difficult to read the address. Further, it becomes difficult to impart the size of the base paper surface due to the effect of the deinking agent remaining on the waste paper pulp, and problems such as the occurrence of feathering also occur when writing with an aqueous pen or ink jet printing. In addition, the negative effect of fading is likely to occur.

  In addition, in the said description, although the form which decreases the waste paper pulp contained in a surface layer and a back surface layer by including many waste paper pulp in an intermediate | middle layer was shown, in the range which does not have a bad influence on a surface layer and a back surface layer Alternatively, waste paper pulp may be blended and the remainder may be blended in the intermediate layer. In actual operation, considering the use of self-circulating paper and the balance of each layer, the preferred waste paper pulp blending ratio of the entire base paper is 20 to 35% by mass when the waste paper pulp is blended only in the intermediate layer. When the waste paper pulp is blended into the layer, or the intermediate layer and the back layer, the preferred waste paper pulp blending ratio of the entire base paper is 20 to 50% by mass, and the waste paper pulp is added to all of the intermediate layer, the front layer and the back layer. In the case of blending, the preferred recycled paper pulp blending ratio of the entire base paper is 25 to 70% by mass. In this case, it is preferable that the ratio of the used paper pulp in the intermediate layer is higher than the ratio of the used paper pulp in the entire base paper.

  The disaggregation freeness of the base paper is obtained by separating the base paper into each layer, and using a Tappi disintegrator (conforming to JIS P 8220: 1998) to a solid content concentration of 1% by mass, and the slurry prepared by disaggregation for 25 minutes is a Canadian standard filtered water It is obtained by measuring with a degree tester (based on JIS P 8121: 1995). In this embodiment, it is preferable that the disaggregation freeness of the pulp of each layer used for the base paper is CSF 350 ml or more and CSF 600 ml or less. More preferably, the CSF is 400 ml or more and CSF 570 ml or less. If the CSF is less than 350 ml, when the base paper becomes dense and cast processing, minute crater-like holes called pits are generated. On the other hand, when the CSF exceeds 600 ml, the fiber-to-fiber bond is weakened, the paper strength is lowered, and the printing cannot be endured, resulting in trouble.

  In this embodiment, it is preferable that the used paper pulp used for the base paper is a beaten waste paper pulp having a freeness difference value within 100 ml of CSF based on the freeness of the unbeaten waste paper pulp or the unbeaten waste paper pulp. The difference value between the unbeaten freeness and the freeness due to beating (hereinafter abbreviated as “freeness difference value”) is preferably within CSF 100 ml, and more preferably within 80 ml of CSF. Waste paper pulp has been shortened and keratinized more than fresh pulp because it has been disaggregated, beaten, and dried at least once. For this reason, it is presumed that waste paper pulp that has been subjected to excessive beating rapidly becomes a dense base paper. Therefore, when the difference in freeness of waste paper pulp exceeds 100 ml of CSF, when cast processing is performed, a minute crater shape called a pit is formed. The hole will be generated.

  Waste paper pulp used for the base paper is largely classified into high-quality and medium-quality paper. In this embodiment, it is preferable to use high-quality waste paper pulp to avoid discoloration. Examples of the high-quality waste paper pulp include pulps prepared from waste paper such as fine white, ruled white, curd, imitation, color, Kent, white art, and milk carton. The used paper used in the present embodiment is not only a disaggregation process and a dust removal process, but preferably, used paper pulp that has undergone a used paper processing process such as a deinking process, a bleaching process, an ink dispersion process, and a washing process. It is preferable. In particular, in the case of multilayer papermaking, fine ink may move to another layer when pressure dewatering is performed in the press part after papermaking. Therefore, it is more preferable to install a cleaning device capable of removing fine ink in the used paper processing step and go through the cleaning step by the device.

  The used paper processing process has various processes such as a disaggregation process, a dust removal process, a deinking process, a bleaching process, a dispersion process, and a washing process. The deinking agent is used at the disaggregation process, before the deinking process or before the bleaching process. Examples of deinking agents include nonionic surfactant deinking agents such as polyoxyethylene alkylphenyl ether and polyoxyethylene alkyl ether, fatty acid deinking agents, polyalkylene oxide derivatives of fatty acids, and polyalkylene oxides of higher alcohols. It is a dealkylating agent for polyalkylene oxide derivatives of derivatives and oils.

  Typical examples of the medium-sized waste paper pulp include pulps prepared from newspapers, magazines, cutting, medium-size antiquarian, tea imitation, corrugated cardboard, backing paper, ground paper, cardboard and the like. In addition, from the viewpoint of fading properties, the ratio of medium-sized waste paper pulp in all waste paper pulp is preferably 20% by mass or less, and more preferably 10% by mass or less.

  In the glossy postcard paper for inkjet according to the present embodiment, the content of the surfactant remaining in the back layer is preferably 500 ppm by mass or less, and more preferably 300 ppm by mass or less. When the content of the surfactant remaining in the back surface layer exceeds 500 mass ppm, feathering may occur when ink-jet printing is performed on the address surface, or the writing property with a water-based pen is reduced, and the printing plate may be held. Deteriorate. As specific means for setting the content of the surfactant remaining in the back layer to 500 ppm by mass or less, for example, the use of a surfactant system as a deinking agent used in the used paper processing step is refrained. It is to use a deinking agent other than the system, to install a cleaning device capable of removing the surfactant in the used paper processing step, to pass through the cleaning step by the device, and to increase the number of times of the cleaning step. In addition, it is preferable to set it as 1 mass ppm as a minimum of the content rate of surfactant which remains in the back surface layer of the glossy postcard paper for inkjets concerning this embodiment. This is because in order to obtain the deinking effect, it is necessary to add a slight amount of deinking agent, and if the cleaning is strengthened excessively, the yield decreases. The amount of the deinking agent used in the used paper processing step is 0.05 to 0.4% by mass, but it is preferable to increase or decrease the addition rate from the viewpoint of the quality of the finished used paper pulp and the residual deinking agent. .

  In the inkjet postcard paper according to the present embodiment, the content of the surfactant remaining in the surface layer is preferably 1000 ppm by mass or less, and more preferably 700 ppm by mass or less. By setting the content of the surfactant remaining in the surface layer to 1000 ppm by mass or less, it is possible to suppress the penetration of the coating liquid for forming the glossy expression layer, and no migration occurs, resulting in a glossiness. improves.

  As pulp used for the base paper, in addition to waste paper pulp, virgin pulp as hardwood bleached sulfite pulp (LBSP), hardwood bleached kraft pulp (LBKP), softwood bleached sulfite pulp (NBSP), softwood bleached kraft pulp (NBKP) , Mechanical pulp (GP, TMP, BCTMP) and the like are advantageously used. In addition to wood pulp, non-wood pulp, synthetic pulp, synthetic fiber, or the like may be used as necessary.

  In the present invention, a filler may be added to the base paper. Specifically, known fillers such as hydrated silicic acid, white carbon, talc, kaolin, clay, calcium carbonate, titanium oxide, aluminosilicate, calcined clay, and synthetic resin filler can be used in combination.

  The pulp slurry beaten to a predetermined freeness is made into a multilayer of 3 or more layers by a long net paper machine, a twin wire paper machine or a circular net paper machine. In the present embodiment, the paper making method is not limited. For example, paper may be produced by a combination of these paper machines. In this case, a dispersion aid, a dry paper strength enhancer, a sizing agent, a fixing agent, a pH adjuster, a dye, a colored pigment, a fluorescent brightening agent, and the like can be appropriately added as necessary. Moreover, in this embodiment, it does not ask | require about the beating method of a pulp. For example, a method of performing so-called mixed beating in which fresh pulp and waste paper pulp are mixed and then beating, or a method of performing so-called single beating in which fresh pulp and waste paper pulp are separately beaten and mixed may be used.

  The glossy postcard paper for multilayer paper-jet inkjet according to this embodiment is paper-made with three or more layers provided with a front layer, one or more intermediate layers, and a back layer, but the basis weight of each layer must be equal. There is no. For example, it is possible to make the basis weight of the intermediate layer relatively larger than the basis weight of the surface layer and the basis weight of the back layer. Furthermore, it is possible to make the front layer and the back layer one layer each and the intermediate layer to be two layers or more. In the present embodiment, the basis weight of each layer is not limited.

  In the present embodiment, a sizing liquid may be applied to the surface layer or the back layer of the base paper that has been made into three or more layers as described above, as necessary. The sizing liquid may be applied only on the front surface layer or only on the back surface layer. Furthermore, you may apply | coat to both surfaces on a surface layer and a back surface layer. Specifically, the sizing liquid is a known surface sizing agent such as oxidized starch, self-modified starch, urea-phosphorylated starch, polyacrylamide, polyvinyl alcohol, pH regulator, dye, colored pigment, fluorescent whitening agent, etc. Materials can be used.

  As a method for applying the size liquid, a conventional size press, a gate roll size press, a film transfer type size press, an air knife coater, a rod coater, or the like can be used as appropriate.

  Moreover, you may apply | coat only on a back surface layer (address side) using a film transfer type size press, an air knife coater, a rod coater, etc. as needed.

  Although the ink receiving layer may be provided directly on the thus manufactured base paper (paper support), in this embodiment, in order to smooth the base paper surface, a machine calendar, soft calendar, It is preferable to perform a treatment such as a calendar or a raster press.

In this embodiment, it is preferable that the water absorption (JIS P 8140: 1998, set time 15 seconds) of the surface layer (communication surface side) of the base paper is 30 g / m ² or less. More preferably, it is 25 g / m ² or less, and further preferably 20 g / m ² or less. In order to control the water absorption, it affects the size of the surface layer, such as the ratio of the sizing agent added to the surface layer, the ratio of the sizing agent added to the intermediate layer, and the ratio of the surface sizing agent added to the sizing liquid. Often done by adjusting the affecting factors. When the water absorption exceeds 30 g / m ² , the penetration of the coating solution for forming the glossy layer is large and migration occurs, resulting in a decrease in gloss. However, in order to make the water absorption less than 10 g / m ² , it is necessary to add an excessively large sizing agent, so that the manufacturing process is contaminated and disadvantageous in terms of cost. Other methods for controlling the water absorption include the following means. The water absorption increases as the ash content in the base paper increases, as the freeness of the pulp used for the base paper decreases, and as the used paper content increases, it may be controlled using these. In addition, this embodiment is not limited to the method of controlling water absorption.

The sizing agent is, for example, alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), neutral rosin, reinforced rosin, saponified rosin, or acidic rosin, and is appropriately selected according to the pH of the papermaking. As a means to make a water absorption 30 g / m < ² > or less, it can carry out by making an acidic rosin sizing agent into 0.2-0.8 mass part with respect to 100 mass parts of pulp of a surface layer, for example. Moreover, it can carry out by making AKD or ASA into 0.05-0.4 mass part with respect to 100 mass parts of pulp of a surface layer. However, the addition amount of the sizing agent varies depending on the configuration state of the surface layer such as the type and addition rate of the filler used in the surface layer and the type of pulp used in the surface layer.

  The gloss developing layer contains a pigment and a binder as main components. Examples of pigments to be included in the glossy layer include synthetic amorphous silica, spherical colloidal silica, aggregated colloidal silica in which a plurality of spherical colloidal silicas are combined, pearl necklace-shaped colloidal silica in which a plurality of spherical colloidal silicas are combined in a chain, Vapor phase method silica, alumina modified silica, γ-alumina, θ-alumina, σ-alumina, pseudoboehmite and the like can be used, and they can be used alone or in combination. As for the particle diameter of the pigment, it is preferable that the pigment has an average particle diameter of 1 μm or less from the balance between glossiness and ink absorbability. More preferably, those having an average particle diameter of 5 nm to 800 nm, and more preferably 10 nm to 500 nm are contained. When the average particle diameter exceeds 1 μm, glossiness may be lowered. In addition, in this embodiment, it is not restrict | limited to the kind of pigment used for a glossiness expression layer, an average particle diameter, and addition amount.

  Further, the binder contained in the glossy layer includes polyvinyl alcohol, polyvinyl acetal, oxidized starch, etherified starch, carboxymethyl cellulose, hydroxyethyl cellulose, casein, gelatin, soybean protein, polyethylene imide resin, polyvinyl pyrrolidone resin, poly Acrylic acid or its copolymer, maleic anhydride copolymer, acrylamide resin, acrylate resin, polyamide resin, acrylic resin, styrene-acrylic resin, polyurethane resin, polyester resin, polyvinyl butyral Resin, alkyd resin, epoxy resin, epichlorohydrin resin, urea resin, melamine resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic ester, Acrylic polymer latex such as polymer or copolymer of acrylic ester, vinyl polymer latex such as ethylene-vinyl acetate copolymer, composite resin of colloidal silica and acrylic resin, colloidal silica and styrene An acrylic resin composite resin or the like is exemplified and used alone or in combination. Polyvinyl alcohol is preferably contained from the viewpoint of achieving both ink absorbability and excellent gloss. The amount of the binder used is determined in consideration of the printability of the recording medium, the strength of the glossy layer, the surface glossiness, the paint liquid property, and the like. Usually, it is added in the range of 1 to 100 parts by mass with respect to 100 parts by mass of the pigment. Preferably, it is added in the range of about 5 to 60 parts by mass, more preferably 10 to 50 parts by mass. If the amount is less than 1 part by mass, the coating layer strength may decrease. If it exceeds 100 parts by mass, the ink absorbability may decrease. In the present embodiment, the type, average particle size, and addition amount of the binder used for the glossy layer are not limited.

  In addition, the glossy layer has a cationic polymer, a dispersant, a thickener, an antiseptic, an antifoaming agent, a coloring dye, a coloring pigment, a fluorescent whitening agent, and a water-proofing agent for fixing ink for inkjet recording. Additives such as antioxidants and ultraviolet absorbers can be appropriately selected and added.

The glossy postcard paper for multilayer paper-jet inkjet according to this embodiment preferably has a dry coating amount of 3 to 20 g / m ² for the glossy layer. When the coating amount exceeds 20 g / m ² , the productivity is inferior, and when the coating amount is less than 3 g / m ² , it is difficult to form a sufficiently glossy surface. In particular, it is preferably 5 to 15 g / m ² . As a coating method of the coating liquid for forming the glossy layer, there are known coating machines such as an air knife coater, roll coater, reverse roll coater, bar coater, comma coater, blade coater, and simultaneous multilayer coater. In this embodiment, it does not matter.

  The gloss developing layer is formed by a known cast coating method. As the cast coating method, a wet method, a coagulation method, and a rewet method are known, and in this embodiment, the coagulation method is preferable. The coagulation method is a method of applying a gloss developing layer and applying a coagulation liquid while it is in a wet state to coagulate it and press the cast drum. In the coagulation treatment, it is important to select a coagulant that effectively coagulates with the binder component of the coating layer. In this embodiment, a boron compound is preferable. More preferred are sodium borate, boric acid or sodium borate and boric acid. A high concentration of the coagulating liquid is preferable because the coagulation force is increased and the scratch resistance is further improved. The content of the coagulant is preferably 5% by mass or more with respect to 100% by mass of the binder capable of coagulation. If it is less than 5% by mass, the surface strength may be lowered. Especially preferably, it is 10 mass% or more. It is also possible to add auxiliary agents such as a lubricant and an ink fixing agent to the coagulation liquid.

  In addition, calendar processing such as machine calendar, soft calendar, super calendar, etc. may be performed after cast processing, and for curl adjustment, water, curling agent etc. are coated on the back side or humidified to adjust curl. Can also be done.

  The multilayer post-printing glossy postcard paper for inkjet according to this embodiment has one or more ink receiving layers under the glossy expression layer. The ink receiving layer contains a white pigment and a binder component as main components.

  The pigment used in the ink receiving layer preferably contains one or more known white pigments. For example, kaolin, talc, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, titanium dioxide, zinc oxide, zinc sulfate, zinc carbonate, calcium silicate, aluminum silicate, magnesium silicate, diatomaceous earth, aluminum hydroxide, magnesium hydroxide, satin Examples include white inorganic pigments such as white, synthetic silica, colloidal silica, and alumina, or organic pigments such as acrylic, styrene, ethylene, vinyl chloride, and nylon. In the present embodiment, the type, average particle diameter, and addition amount of the pigment used in the ink receiving layer are not limited.

  The binder contained in the ink receiving layer is polyvinyl alcohol, polyvinyl acetal, oxidized starch, etherified starch, carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soybean protein, polyethyleneimide resin, polyvinylpyrrolidone resin, polyacrylic acid Or a copolymer thereof, a maleic anhydride copolymer, an acrylamide resin, an acrylate resin, a polyamide resin, a polyurethane resin, a polyester resin, a polyvinyl butyral resin, an alkyd resin, an epoxy resin, and an epichlorohydrin resin. Acrylic resins such as urea resin, melamine resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic acid ester, methacrylic acid ester polymer or copolymer Polymer latices, ethylene - vinyl polymer latex such as vinyl acetate copolymer and the like, used alone or in combination. The amount of the binder used is determined in consideration of the printability of the recording medium, the strength of the ink receiving layer, and the coating liquid property. Usually, it is added in the range of 1 to 200 parts by mass with respect to 100 parts by mass of the pigment. Preferably, it is added in the range of about 5 to 100 parts by mass. If the amount is less than 1 part by mass, the coating layer strength may decrease. If it exceeds 200 parts by mass, the ink absorbability may decrease. In the present embodiment, the type, average particle diameter, and addition amount of the binder used for the ink receiving layer are not limited.

  It is preferable to add a cationic polymer to the ink receiving layer in addition to the pigment and the binder. As an action of the cationic polymer, it reacts with an anionic component in the dye used in the ink to form a water-insoluble salt, so that the ink is more firmly fixed on the ink receiving layer, Water resistance is improved. Such cationic polymers include polyethyleneimine, epichlorohydrin modified polyalkylamine, polyamine, polyamine polyamide epichlorohydrin, dimethylamine ammonia epichlorohydrin, polyvinylbenzyltrimethylammonium halide, polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride, polyvinyl Pyridium halide, cationic polyacrylamide, cationic polystyrene copolymer, diallyldimethylammonium chloride polymer, diallyldimethylammonium chloride sulfur dioxide copolymer, diallyldimethylammonium chloride amide copolymer, dicyandiamide formalin polycondensate, dicyandiamide diethylenetriamine Polycondensate Polyallylamine, polyallylamine hydrochloride, polyacrylamide resin, polyamide epoxy resin, melamine resin acid colloid, urea resin, cation-modified polyvinyl alcohol, amino acid type amphoteric surfactant, betaine type compound, and other quaternary ammonium salts Used. Although the addition amount is not particularly limited, it is used in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. Preferably, it is added in the range of about 5 to 40 parts by mass. If it is less than 1 part by mass, the water resistance of the printed part may be lowered. If it exceeds 50 parts by mass, the ink absorbability may be inferior.

  Other additives include antifoaming agents, dispersants, wetting agents, fluorescent whitening agents, colored dyes, coloring pigments, thickeners, preservatives, water-resistant agents, UV absorbers, antioxidants as necessary May be used.

Examples of the coating method of the coating liquid for forming the ink receiving layer include known coating machines such as an air knife, a roll coater, a bar coater, a comma coater, a blade coater, and a simultaneous multilayer coating machine. Any of these may be used. The coating amount is not particularly limited, but is preferably 5 g / m ² or more and 20 g / m ² or less. If it is less than 5 g / m ² , the ink absorbability is inferior. On the other hand, if it exceeds 20 g / m ² , binder migration may occur during coating of the glossy layer, and the scratch resistance on the surface of the glossy layer may be reduced. More preferably 6 to 15 g / ^{m 2.} Alternatively, the ink receiving layer may be composed of two or more layers by coating the coating liquid for forming the ink receiving layer twice or more.

  Further, in order to obtain a certain smoothness after coating, it can be processed by a known calendar device such as a super calendar, a machine calendar, or a soft calender that provides a certain smoothness after coating the ink receiving layer.

  Next, although an example of the present invention is given and explained, the present invention is not limited to these examples. Further, “parts” and “%” indicate parts by mass and mass% unless otherwise specified. In addition, the number of parts shown in a mixing | blending is the quantity of a real component.

Example 1
<Preparation of base paper>
100 parts of hardwood bleached kraft pulp (500 ml of surface layer disaggregation freeness) and 10 parts of hardwood bleached kraft pulp and 90 parts of unbeaten fine quality old paper pulp (500 ml of intermediate layer disaggregation freeness) , Cationized starch (Neotac 40T, Nippon Food Processing Co., Ltd.) common to the surface layer, intermediate layer, and back layer for each pulp raw material of 100 parts of hardwood bleached kraft pulp (500 ml of disintegration freeness of the back layer) Made of 1.0), 0.4 parts of acidic rosin sizing agent (AL1212, made by Seiko PMC), 1 part of liquid sulfuric acid band, and paper containing talc adjusted to an amount of 5% ash. papermaking at each length paper machine, basis weight of 60 g / ^{m 2} of the surface layer, a basis weight of 60 g / ^{m 2} of the intermediate layer, the basis weight of the back layer and 60 g / ^{m 2} 3-layer was produced base paper 180 g / ^{m 2} combined paper making the.
<Application of size liquid>
Oxidized starch (Oji Ace A: manufactured by Oji Cornstarch Co., Ltd.) was used as a sizing solution, applied to both sides of the base paper with a size press so that the dry coating amount was 1 g / m ² per side, and dried with a cylinder dryer. . Surface treatment was performed using a steel calender under conditions of a linear pressure of 40 kg / cm, 25 ° C., and 2 nips and 1 pass.
<Formation of ink receiving layer>
On a size-pressed support, 100 parts of synthetic silica (Mizukasil P-78A, manufactured by Mizusawa Chemical Co., Ltd.) as a pigment, 10 parts of polyvinyl alcohol (PVA117: manufactured by Kuraray Co.) as a binder, and ethylene-vinyl acetate (Polysol EVA) 40 parts of AD-10 (manufactured by Showa Polymer Co., Ltd.) and 30 parts of cationic polymer (Papiogen P-105: manufactured by Senka Corporation) were used to obtain a coating solution for an ink receiving layer having a solid concentration of 22%. Subsequently, this ink receiving layer coating solution was applied and dried with an air knife coater so that the dry coating amount was 10 g / m ² to form an ink receiving layer.
<Formation of glossy layer>
Next, a pearl necklace-shaped colloidal silica which is a kind of aggregate colloidal silica as a pigment for the glossy layer coating material (Snowtex PS-M, primary particle diameter 18 to 25 nm, secondary particle diameter 80 to 150 nm: manufactured by Nissan Chemical Industries, Ltd.) Gloss of 20% solid content using 100 parts, 6 parts of polyvinyl alcohol (PVA-124: manufactured by Kuraray Co., Ltd.) and 6 parts of acrylic resin (Vinyl Blanc 2684, glass transition temperature 20 ° C .: manufactured by Nissin Chemical Co., Ltd.) as a binder. An expression layer coating solution was obtained. This glossy layer coating solution was applied with an air knife coater so that the dry coating amount was 10 g / m ² . Next, an aqueous solution containing 1% boric acid as a coagulant and 1% sodium borate as a coagulant is applied onto the coated surface of the coating liquid for the glossy layer so that the coating amount is 1.5 g / m ^2. After the coating and coagulation treatment, while the surface of the obtained coating layer was wet, it was pressure-bonded to a cast drum having a surface temperature of 105 ° C. to produce glossy paper for ink jet recording. Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Example 2)
The pulp composition of the surface layer is 60 parts of hardwood bleached kraft pulp and 40 parts of unbeaten fine paper waste paper (40 ml of surface layer disintegration freeness 500 ml), and the pulp composition of the intermediate layer is 50 parts of hardwood bleached kraft pulp and unbeaten fine paper pulp An ink jet postcard paper was prepared in the same manner as in Example 1 except that the amount was 50 parts (500 ml of disintegration freeness of the intermediate layer). Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Example 3)
The pulp composition of the surface layer is 80 parts of hardwood bleached kraft pulp and 20 parts of unpulverized fine pulp (20 ml of surface layer disintegration freeness), and the pulp composition of the intermediate layer is 30 parts of broadleaf bleached kraft pulp and unpulverized fine pulp An ink jet postcard paper was prepared in the same manner as in Example 1 except that the amount was 70 parts (intermediate layer disaggregation freeness of 500 ml). Here, the proportion of waste paper pulp in the entire base paper was 30%.

Example 4
The pulp composition of the intermediate layer is 25 parts of hardwood bleached kraft pulp and 75 parts of unbeaten fine paper waste pulp (intermediate layer disintegration freeness 500 ml), and the pulp composition of the back layer is 85 parts of hardwood bleached kraft pulp and unbeaten fine paper pulp An ink jet postcard paper was prepared according to Example 1 except that the amount was 15 parts (back surface disaggregation freeness 500 ml). Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Example 5)
The pulp composition of the intermediate layer is 20 parts of hardwood bleached kraft pulp and 80 parts of unbeaten fine pulp pulp (intermediate layer disintegration freeness 500 ml), and the pulp composition of the back layer is 90 parts of hardwood bleached kraft pulp and unbeaten fine pulp An ink jet postcard paper was prepared in the same manner as in Example 1 except that the amount was 10 parts (back surface disaggregation freeness 500 ml). Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Example 6)
The pulp composition of the surface layer is 60 parts of hardwood bleached kraft pulp and 40 parts of unbeaten fine paper waste pulp (40 ml of surface layer disintegration freeness 500 ml), and the pulp composition of the intermediate layer is 20 parts of hardwood bleached kraft pulp and unbeaten fine paper pulp Example 1 except that 80 parts (intermediate layer disaggregation freeness 500 ml) and the back layer pulp composition was hardwood bleached kraft pulp 85 parts and unbeaten high quality waste paper pulp 15 parts (back surface disaggregation freeness 500 ml) An ink jet postcard paper was prepared. Here, the proportion of waste paper pulp in the entire base paper was 45%.

(Example 7)
The pulp composition of the surface layer is 80 parts of hardwood bleached kraft pulp and 20 parts of unpulverized fine paper waste paper (20 ml of surface layer disintegration freeness 500 ml), and the pulp composition of the intermediate layer is 100 parts of unbeaten fine paper waste paper pulp (dissolving of the intermediate layer) A postcard paper for inkjet was prepared according to Example 1 except that the pulp composition of the back layer was 85 parts of hardwood bleached kraft pulp and 15 parts of unpulverized fine-quality waste paper pulp (500 ml of disintegration freeness of the back layer). did. Here, the proportion of waste paper pulp in the entire base paper was 45%.

(Example 8)
The pulp composition of the surface layer is 60 parts of hardwood bleached kraft pulp and 40 parts of unpulverized fine paper pulp (500 ml of surface layer disintegration freeness), and the pulp composition of the intermediate layer is 15 parts of hardwood bleached kraft pulp and unbeaten fine paper pulp Example 1 except that 85 parts (intermediate layer disaggregation freeness 500 ml) and the back layer pulp composition was 90 parts of hardwood bleached kraft pulp and 10 parts of unbeaten high-quality waste paper pulp (back surface disaggregation freeness 500 ml) An ink jet postcard paper was prepared. Here, the proportion of waste paper pulp in the entire base paper was 45%.

Example 9
The pulp composition of the intermediate layer is set to 40 parts of hardwood bleached kraft pulp and 60 parts of unpulverized fine-quality waste paper pulp (500 ml of disintegration freeness of the intermediate layer). The surface layer is provided with a basis weight of 45 g / m ² A postcard paper for inkjet was prepared according to Example 1 except that four layers having a basis weight of 45 g / m ² and a back layer of 45 g / m ² were combined to form a base paper of 180 g / m ^2. did. Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Example 10)
The pulp composition of the surface layer is 55 parts of hardwood bleached kraft pulp and 45 parts of unbeaten fine paper waste pulp (500 ml of disintegration freeness of the surface layer), and the pulp composition of the back layer is 85 parts of hardwood bleached kraft pulp and unbeaten fine paper pulp 4 layers with 15 parts (back surface disaggregation freeness of 500 ml), surface layer with a basis weight of 45 g / m ² and ^two intermediate layers, each with a basis weight of 45 g / m ² and a back layer with a basis weight of 45 g / m ² Inkjet postcard paper was prepared in the same manner as in Example 1 except that the sheet was made into 180 g / m ² . Here, the proportion of waste paper pulp in the entire base paper was 60%.

(Example 11)
Postcard paper for inkjet according to Example 10, except that the acid rosin sizing agent (AL1212, manufactured by Starlight PMC) for the front and back layers used in the preparation of the base paper was changed from 0.4 part to 0.6 part. Was made. Here, the proportion of waste paper pulp in the entire base paper was 60%.

(Comparative Example 1)
The pulp composition of the surface layer is 35 parts of broad-leaved bleached kraft pulp and 65 parts of unpulverized fine quality old paper pulp (500 ml of disintegration freeness of the surface layer), and the pulp composition of the intermediate layer is 100 parts of broad-leaf bleached kraft pulp (500 ml of disintegration freeness of the intermediate layer) Ink jet postcard paper was prepared in accordance with Example 1, except that the pulp composition of the back surface layer was changed to 75 parts of hardwood bleached kraft pulp and 25 parts of unbeaten fine quality old paper pulp (back surface disaggregation freeness 500 ml). Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Comparative Example 2)
The pulp composition of the surface layer is 25 parts of hardwood bleached kraft pulp and 75 parts of unbeaten fine quality old paper pulp (surface layer disaggregation freeness 500 ml), and the pulp composition of the intermediate layer is 100 parts of hardwood bleached kraft pulp (intermediate layer disaggregation freeness 500 ml). Ink jet postcard paper was prepared according to Example 1, except that the pulp composition of the back layer was 85 parts of hardwood bleached kraft pulp and 15 parts of unpulverized fine waste paper pulp (500 ml of disintegration freeness of the back layer). Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Comparative Example 3)
The pulp composition of the surface layer is 60 parts of broad-leaved bleached kraft pulp and 40 parts of unpulverized fine quality old paper pulp (500 ml of disintegration freeness of the surface layer), and the pulp composition of the intermediate layer is 100 parts of hardwood bleached kraft pulp (500 ml of disintegration freeness of the intermediate layer) Ink jet postcard paper was prepared in accordance with Example 1 except that the composition of the back layer pulp was 50 parts of hardwood bleached kraft pulp and 50 parts of unbeaten high-quality waste paper pulp (500 ml of disintegration freeness of the back layer). Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Comparative Example 4)
In Example 1, except that 70 parts of hardwood bleached kraft pulp and 30 parts of unbeaten fine quality old paper pulp (500 ml of disintegration freeness of the surface layer) were produced in a single layer, and a base paper of 180 g / m ² was produced. An ink jet postcard paper was prepared. Here, the proportion of waste paper pulp in the entire base paper was 30%.
It became.

(Comparative Example 5)
An ink jet postcard paper was prepared in the same manner as in Example 1 except that the intermediate layer was blended with 45 parts of hardwood bleached kraft pulp and 55 parts of non-beaten high quality waste paper pulp (intermediate layer disintegration freeness 500 ml). Here, the waste paper pulp content of the entire base paper was 18%.

(Comparative Example 6)
Postcard paper for ink jet according to Example 1 except that the acid rosin sizing agent (AL1212, manufactured by Starlight PMC) for the front and back layers used in the preparation of the base paper was changed from 0.4 part to 0.1 part. Was made. Here, the proportion of waste paper pulp in the entire base paper was 30%.

(Comparative Example 7)
Postcard for inkjet according to Example 10 except that the acid rosin sizing agent (AL1212, manufactured by Starlight PMC) for the front surface layer and the back surface layer used in the preparation of the base paper was changed from 0.4 part to 0.2 part. A paper was prepared. Here, the proportion of waste paper pulp in the entire base paper was 60%.

  Regarding the postcard paper for ink jet obtained in the above examples and comparative examples, Table 1 shows the visual evaluation of impurities on the front surface (communication surface) and back surface (address surface), ink jet printing suitability, back layer (address surface) pen writing. The results of sizing evaluation and printability (printing strength and workability) evaluation are shown. Table 2 shows the ratio of used paper pulp in Examples and Comparative Examples.

<Evaluation method>
The obtained postcard paper for inkjet was subjected to humidity control in a constant temperature and humidity chamber of 23 ° C.-50% RH for 24 hours, and then evaluated by the following methods under the same environment.

<Measurement of impurities>
The total area of impurities was measured using a paper dust measuring device DF1000 (Ver3.00) (manufactured by Oji Scientific Instruments). As measurement conditions, M.M. D. A. (Minimum detection area) = 0.05 mm ² and the threshold value was 34.

Based on the above results and visual evaluation, the following procedure was used.
◎… Very little visual perception of foreign matter, total area of foreign matter is less than 3.0 mm ² / m ² (practical level), ○… There is little visual perception of foreign matter, and total area of foreign matter is 3.0 mm ² / m ² or more and less than 10.0 mm ² / m ² (practical level), Δ ... The visual appearance of the contaminants is slightly larger, and the total area of the contaminants is 10.0 mm ² / m ² or more and 20.0 mm ² / m ^2. Less than (lower limit for practical use), x ... The visual appearance of impurities is very large, and the total area of the impurities is 20.0 mm ² / m ² or more (not suitable for practical use).

<Pen writing size evaluation>
According to the measurement method prescribed | regulated by JTAPPI paper pulp test method No12-76, the pen writing size degree of the back surface layer (address surface) was measured and evaluated.

According to the test method, what was reported in grades 0 to 6 will be described in the following manner.
A: 6 (practical and good), B: 5 (lower practical limit), B: 4 (unsuitable), X: 3 or less (unsuitable)

<Glossiness measurement>
According to the measuring method prescribed | regulated to JISZ-8741: 1997, the specular glossiness of the glossiness expression layer formed on the surface layer of the glossy postcard for inkjet was measured. The incident angle was measured at 20 °.

<Measurement of water absorption of support surface layer>
The water absorption of the surface layer (communication surface side) was measured according to the measurement method defined in JIS P-8140: 1998. The set time was 15 seconds. The sample is peeled off between the surface layer and the intermediate layer, and here the surface layer that has been in contact with the intermediate layer is measured.

<Printability evaluation>
Using an actual printing press (Ryobi 3302M: manufactured by Ryobi), print a postal code frame, a stamp attachment frame, and a test pattern on the back layer (address side), and evaluate the printing strength based on the presence or absence of white spots or peeling. The workability was evaluated according to the degree of dirt on the blanket.

The printing strength and workability evaluation were described in the following manner. The printing strength was evaluated by visual evaluation of picking and peeling of the printing surface, and workability by blanket stain and plate stain.
Evaluation of printed surface: ◎ ... practical level or better, ○ ... practical level, △ ... somewhat hindered (practical lower limit), x ... no printing possible.
Evaluation of workability: ◎ ... above practical level, ○ ... practical level, Δ… somewhat hindered (practical lower limit), ×… difficult to work.

In all of Examples 1 to 11, the waste paper pulp content of the entire base paper is 20% by mass or more and 70% by mass or less, and the recycled paper pulp content of the intermediate layer is 50% by mass or more and 100% by mass or less. The water absorption of the layer was 30 g / m ² or less, and the glossiness of the glossy layer formed on the surface layer was 25% or more. In addition, the front layer and back layer contaminants and the back layer (address surface) pen writing size and various printability were also within the practical range. It was confirmed that the water absorption became 20 g / m ² or less and the glossiness of the gloss developing layer tended to increase as the ratio of the used paper pulp in the surface layer approached 0%. Examples 10 and 11 are cases in which two intermediate layers are provided and four layers are made. As in Examples 10 and 11, even when the proportion of the used paper pulp in the entire base paper is increased by providing two or more intermediate layers, there are few contaminants in the front surface layer and the back surface layer, and the gloss of the gloss expressing layer It was confirmed that a glossy postcard paper for ink jet with a degree of writing and a pen writing size of the back layer and various printability within the practical range could be produced. In order to increase the proportion of waste paper pulp in the entire base paper and increase the glossiness of the glossy layer, the amount of sizing agent added to each layer may be increased as in Example 11.

  On the other hand, in Comparative Example 1, since the waste paper pulp blending ratio of the intermediate layer was set to 0%, the waste paper pulp blending ratio of the front surface layer and the back surface layer was high. As a result, contaminants on the front and back layers are out of the practical range, and the back layer is inferior in size due to the effect of the deinking agent derived from waste paper pulp, and the pen writing size and various printability are out of the practical range. there were.

  In Comparative Example 2, the waste paper pulp blending ratio of the intermediate layer was set to 0%, the waste paper pulp blending ratio of the surface layer was increased from that of Comparative Example 1, while the waste paper pulp blending ratio of the back layer was decreased from that of Comparative Example 1. . As a result, the contaminants on the surface layer were outside the practical range, but the contaminants on the back layer were within the practical range, and the pen writing size and various printability were within the practical range.

  In Comparative Example 3, the waste paper pulp blending ratio of the intermediate layer is set to 0%, and the waste paper pulp blending ratio of the surface layer is less than those of Comparative Examples 1 and 2. On the other hand, the waste paper pulp blending ratio of the back layer is compared with Comparative Examples 1 and 2. More than that. As a result, the contaminants on the surface layer were within the practical range, but the contaminants on the back layer, the pen writing size, and various printability were out of the practical range. From Comparative Examples 1, 2, and 3, the waste paper pulp blending ratio of the back layer is preferably 0% or more and 20% or less, and the waste paper pulp blending ratio of the surface layer is preferably 0% or more and 50% or less. I was able to confirm.

  Comparative Example 4 is a case of single layer papermaking. Pen writing size and various printability on the back layer were out of the practical range.

  Comparative Example 5 is a case where the ratio of the used paper in the entire base paper is 20% or less. The glossiness of the surface layer, the impurities on the surface layer and the back surface layer, the pen writing size of the back surface layer, and various printability are within the practical range. However, it is difficult to say that the object of the present invention, in which waste paper is reused, the recycling rate is increased, and the environment is considered, can be achieved.

In Comparative Example 6, the sizing agent added to each layer is less than that in Example 1. Since the sizing agent was reduced, the water absorption of the surface layer was 30 g / m ² or more, and as a result, the glossiness of the glossy real expression layer formed on the surface layer was lowered to 25% or less. Although the pen writing size and various printability in the back surface layer were within the practical range, the glossiness of the gloss developing layer is low, and it cannot be said that the demand for high-detail images is met.

Comparative Example 7 is a case where two intermediate layers are provided to make four layers, and the sizing agent added to each layer is less than in Example 10. Since the sizing agent was reduced, the water absorption of the surface layer was 30 g / m ² or more, and as a result, the glossiness of the glossy expression layer formed on the surface layer was lowered to 25% or less. The pen writing sizing degree and various printability in the back layer were within the practical range, but it cannot be said that the demand for highly detailed images can be met.

  The present invention relates to glossy postcard paper for ink-jet, high glossiness, few impurities, excellent writing performance with a water-based pen on the address side, and good printing suitability including printing strength and postcard post-printing. As a result, it was possible to obtain the same performance as that of postcard paper using virgin pulp in the efficiency of bar code reading work (route assembly) by automatic sorting. Therefore, it has applicability to ink jet glossy postcard paper containing waste paper pulp.

Claims (7)

The base paper is a multi-layered paper having three or more layers having a surface layer, one or more intermediate layers, and a back surface layer. On the surface layer, one or more ink receiving layers and the ink receiving layer A glossy expression layer formed by a cast coating method containing a pigment and a binder on the outermost layer is provided,
And the back layer is in a state where the base paper is exposed,
And the waste paper pulp content of the whole said base paper is the glossy postcard paper for multilayer paper-jet inkjet whose 20 mass% or more and 70 mass% or less,
The waste paper pulp blending ratio of the intermediate layer is 50% by mass or more and 100% by mass or less,
A glossy postcard paper for multilayer paper-jet inkjet, wherein the water absorption of the surface layer (JIS P-8140: 1998, set time 15 seconds) is 30 g / m ² or less.   2. The glossy postcard paper for multilayer paper-jet ink jet according to claim 1, wherein the surface gloss of the surface layer (JIS Z-8741: 1997, 20 degrees) is 25% or more. 3. The glossy postcard paper for multilayer paper-jet ink jet according to claim 1, wherein a dry coating amount of the glossy layer is 3 to 20 g / m ² .   4. The glossy postcard paper for multilayer paper-jet ink jet according to claim 1, wherein the ratio of waste paper pulp in the surface layer is 0% by mass or more and less than 50% by mass.   The multilayer post-printing glossy postcard paper according to any one of claims 1 to 4, wherein a ratio of waste paper pulp in the back layer is 0% by mass or more and less than 20% by mass.   6. The glossy postcard paper for multilayer paper-jet ink jet according to claim 1, wherein a mixing ratio of the used paper pulp of the intermediate layer is higher than a mixing ratio of the used paper pulp of the front surface layer or the back layer.   The glossy postcard paper for multilayer paper-jet ink jet according to any one of claims 1 to 6, wherein the surface layer side is a communication surface, and the back surface layer side is an address surface.