JP5762726B2 - Recording paper and recording paper manufacturing method - Google Patents

Description

  The present invention relates to a recording sheet used for large-sized postings and wallpaper, and a method for manufacturing the recording sheet.

  In the past, fabrics and synthetic resin sheets have been used as base materials for recording materials used for large-scale postings and wallpaper applications, particularly on one side of 350 mm or more. For example, Patent Document 1 proposes a composite synthetic paper in which a synthetic resin sheet is used as a base material. Patent Document 2 proposes an inkjet recording material in which a fabric is used as a base material. A recording material in which a cloth or a synthetic resin sheet is used as a base material has excellent ink absorbability, high print density, moderate gloss, and excellent color reproducibility and image reproducibility. Yes. In addition to these characteristics, as a recording material having the characteristics of being inexpensive and excellent in recyclability, recording paper in which paper is used instead of synthetic paper or fabric as a base material (hereinafter referred to as “billboard paper”) (Also referred to as Patent Document 3, for example).

JP 7-227941 A JP 2005-256213 A Japanese Patent Laid-Open No. 2002-200842

  However, when paper is used as the substrate, there is a problem that the dimensions become unstable due to the water paste applied at the time of posting. In addition, there is a problem that the strength against tearing and pulling during the posting operation is insufficient.

  Examples of a method for improving the dimensional stability degradation due to water paste at the time of posting and the strength against tearing or pulling at the time of posting work include a method of applying a paint having high water resistance on the surface to which the water paste is applied. Moreover, the method of thickening the suppression layer provided in order to suppress permeation | transmission of the water paste to a base material is mentioned.

  However, in the above-described method, there is a problem that the water paste is repelled on the surface of the base material or the coated surface, and the base material cannot be uniformly impregnated and applied with water paste, and workability at the time of sticking is deteriorated. On the other hand, if the water resistance of the paint is lowered or the thickness of the suppression layer is reduced, water paste can be applied evenly on the paper, but the occurrence of wavy phenomena (cockling) and the strength of the paper The processability at the time of sticking will worsen by the fall. Therefore, there is a demand for a recording paper that has both good water resistance and workability while having good characteristics by using paper as a base material.

  An object of the present invention is a recording paper having excellent recyclability, printability, dimensional stability at the time of object pasting, strength against tension or tearing at the time of posting, affinity with glue, and recording paper It is in providing the manufacturing method of.

The present invention which solved this problem is as follows.
[Invention of Claim 1]
It is a recording paper made of wood pulp, an ink receiving layer is provided on one side of the base material, and a water resistant agent layer is provided on the other side of the base material,
In the ink receiving layer,
Polyvinyl alcohol is included as a binder, silica and aluminum hydroxide are included as inorganic pigments,
In the waterproofing agent layer,
At least an acrylic synthetic rubber, are included kaolin and calcium carbonate as the inorganic pigment,
A recording paper, wherein a wet paper strength enhancer is contained in the base material, or is coated between the base material and the waterproofing agent layer.

(Function and effect)
In the present invention, since the ink receiving layer is provided on one side of the substrate and the water-proofing agent layer is provided on the other side, the recording medium is provided with water resistance and dimensional stability. In addition to having excellent cockling resistance when water glue is applied, it has excellent ink absorption, high print density and moderate gloss, and excellent color reproducibility and image reproducibility. It is made. In addition, the wet paper strength enhancer is contained in the base material, or is coated between the base material and the water-proofing agent layer, so wood pulp is used as the base paper due to the synergistic effect with the water-proofing agent layer. Even when the recording paper is posted, it has water resistance, and there is no decrease in the strength of the paper. In addition, it has an excellent effect on the transportability when printing the recording paper.

[Invention of Claim 2]
The wet paper strength enhancer is
At least one of urea-formaldehyde resin, polyamide-polyamine epichlorohydrin resin, and melamine-formaldehyde resin is included, and the wet strength (longitudinal) of the recording paper according to JIS P 8135 is 1.5 kN / m or more. Further, it is contained in the base material at a ratio of 0.3% by mass or more and 1.5% by mass or less, or is coated by 1.0 g / m ² or more and 5.0 g / m ² or less. The recording paper according to claim 1.

(Function and effect)
The wet paper strength enhancer is contained in the base paper so that the wet strength (longitudinal) is 1.5 kN / m or more, or the base paper and the water-resistant agent layer are coated. The paper strength can be prevented from being reduced and cockling can be prevented, so that the recording paper is excellent in workability and dimensional stability at the time of pasting the object.

[Invention of claim 3]
The waterproofing agent layer is
One or more kinds of acrylic synthetic rubber having a glass transition temperature in the range of −40 ° C. or more and 25 ° C. or less are contained, and at least one kind of inorganic pigment is 10 parts by weight or more and 120 parts per 100 parts by weight of the acrylic synthetic rubber. The recording paper according to claim 1 or 2, wherein the recording paper contains not more than 1 part by weight and not less than 0.1 parts by weight of a crosslinking agent.

(Function and effect)
The water-resistant agent layer includes an acrylic synthetic rubber excellent in water resistance having a glass transition temperature of −40 ° C. to 25 ° C. and paper transportability, and includes a predetermined amount of an inorganic pigment and a crosslinking agent. Dimensional stability at the time of object pasting, tension at the time of posting, tear strength maintenance effect and affinity effect with paste can be obtained, and an effect of improving transportability in a printing machine can also be achieved.

[Invention of claim 4]
The coating amount of the waterproofing agent layer is 4.0 g / m ² or more and 15.0 g / m ² or less, and the contact angle on the surface of the waterproofing agent layer is 60 ° or less measured according to JIS K 3211. The water absorption after 2 minutes on the surface of the waterproofing agent layer, measured according to JIS P 8140, is 5.0 g / m ² or less, and the JAPAN TAPPI paper pulp test method No. 27, the underwater elongation of the recording paper measured in accordance with No. 27 is 1.0% or less in length and 4.5% or less in width, and the air permeability of the recording paper measured in accordance with JIS P 8117 is 4. The recording paper according to claim 1, wherein the recording paper is 18,000 seconds or less.

(Function and effect)
Since the coating amount of the water-resistant agent layer is 4.0 g / m ² or more and 15.0 g / m ² or less, no repelling occurs at the time of water glue application, and the water glue coating has an affinity for water glue. The dimensional stability improvement effect at the time of cloth is produced. Further, the contact angle on the surface of the waterproofing agent layer is 60 ° or less, the water absorption after 2 minutes on the surface of the waterproofing agent layer is 5.0 g / m ² or less, the elongation in water is 1.0% or less in length and 4 in width. .5% or less, water resistance, excellent dimensional stability without occurrence of cockling, etc., and air permeability of 18,000 seconds or less, so water paste applied at the time of application The workability improvement effect can be achieved without slowing the drying speed.

[Invention of Claim 5]
A method for producing recording paper made of wood pulp,
An ink receiving layer containing polyvinyl alcohol as a binder and silica and aluminum hydroxide as an inorganic pigment is provided on one surface of the substrate, and at least an acrylic synthetic rubber and an inorganic material are provided on the other surface of the substrate. a step of providing a water resistant adhesive layer containing kaolin and calcium carbonate as a pigment,
A method for producing a recording paper, comprising: a wet paper strength enhancer contained in the base material, or a step of being applied between the base material and the waterproofing agent layer.

(Function and effect)
The same effect as that of the first aspect of the invention can be achieved.

  According to the present invention, it is possible to provide a recording paper that is excellent in printability, dimensional stability at the time of object pasting, tensile and tear strength at the time of posting, affinity with glue, and the like.

  The billboard paper of the present invention uses paper as a base material. Since paper is used as the base material, it is excellent in recyclability. In this embodiment, an ink receiving layer is provided on one surface side of the substrate. A wet paper strength enhancer is contained in the substrate or applied to the other side of the substrate. The term “coating” means not only coating on the surface of the substrate but also impregnation into the substrate. When the wet paper strength enhancer is contained in the substrate, a water-resistant agent layer made of a water-resistant agent is provided on the other surface side of the substrate. When the wet paper strength enhancer is applied to the other side of the substrate, the waterproofing agent layer is provided by being applied over the applied wet paper strength enhancer.

  The ink receiving layer is excellent in ink absorbability, has high print density and moderate gloss, and is excellent in color reproducibility and image reproducibility. The water-resistant agent layer and the wet paper strength enhancer layer prevent cockling and decrease the strength of the paper after applying the water paste, and improve the affinity with the paste. Hereinafter, each structure and the manufacturing method of billboard paper are demonstrated in detail.

<Paper>
The raw material of the paper used for a base material is demonstrated. Examples of paper raw materials include waste paper pulp (DIP), chemical pulp (for example, hardwood kraft pulp: LBKP, conifer kraft pulp: NBKP, etc.), mechanical pulp (for example, thermomechanical pulp: TMP, pressured ground pulp: PGW, refiner) Any pulp such as non-wood pulp such as kenaf, bagasse, hemp, and cotton can be used.

  In addition to the basis weight, average fiber length, base material tension, papermaking method, factors contributing to the printability of billboard paper, especially when using emulsion-type water-based ink (latex ink), There is the structure of the pulp fiber itself. The pulp fiber has a lumen, and when the fiber itself is crushed, it leads to an ink absorbing function of the entire paper. For this reason, the ratio between the lumen and the thickness of the cell wall serving as the outer ring is important for the ink absorption function.

  There is a Runkel ratio R as an index for evaluating the ink absorption function of pulp fibers. The Runkel ratio R is a value determined by the width L of the fiber lumen (lumen) and the thickness t of the cell wall, and is represented by R = 2t / L. The lower the numerical value of the Runkel ratio R, the smaller the fiber wall thickness with respect to the same diameter, and the more flexible the fiber. If the Runkel ratio is 0.8 or less, the emulsion-like ink particles are easily absorbed into the paper under printing conditions using an emulsion-type water-based ink. In order to obtain a pulp fiber having a Runkel ratio R of 0.8 or less, it is preferable to use a planted tree or the like that grows relatively quickly as a raw material. Further, in order to maintain the original shape of the pulp fiber, which is important as an ink absorbing function, it is desirable to suppress beating as much as possible and to make the raw material freeness 300 cc or more, preferably 350 cc or more.

  The average fiber length of the pulp raw material to be used is 1.0 mm or more and less than 1.6 mm, and the blending mass ratio of NBKP and LBKP is 20 to 40:60 to 80, which is an index of dimensional stability. It is possible to produce an elongation in water of preferably 1.0% or less in length and 4.5% or less in width, more preferably 0.8% or less in length and 3.5% or less in width. Billboard paper with good dimensional stability by water glue is preferably obtained. If the elongation in water exceeds 1.0% in length and 4.5% in width, the paper stretches when moisture is absorbed, and the possibility of generating wrinkles and tarmi increases. If paper with wrinkles and tarmi is used as billboard paper, there is a possibility that wrinkles and doubles are likely to occur at the time of posting.

  The paper surface pH is preferably adjusted to be 5.0 or more. When a sulfuric acid band is added so that the pH of the paper surface is less than 5.0, the pulp is agglomerated and flocs are likely to be generated, resulting in poor formation. When applying the aqueous paste for bonding, the aqueous paste is present in the base material. May be easier to enter. Although it is desirable not to add the sulfuric acid band in consideration of the formation, 0.05% by weight or less may be added in consideration of dryer peelability and fixing of other chemicals.

  The paper pH can be measured with a pH meter for measuring paper (model MPC, manufactured by Kyoritsu Riken). Coloring with a BCP solution with a pH measurement range of 4.6 to 6.8, or with a BTB solution with a pH measurement range of 6.0 to 8.0, attached to the pH meter for paper measurement, is standard. The paper surface PH can be measured by comparing with the plate.

  The thickness of the paper is preferably 100 μm or more and 180 μm or less, and more preferably 150 μm or more and 180 μm or less. If the paper thickness exceeds 180 μm, the rigidity is too high, and the transportability in the billboard paper inkjet printer may be deteriorated. On the other hand, when the thickness is less than 100 μm, the rigidity is lowered and the transportability of the billboard paper-dedicated ink jet printer may be deteriorated, and the dimensional stability during paste application or ink jet recording may be deteriorated.

The rice base of the paper base is preferably 100 g / m ² or more and 200 g / m ² or less. If the rice tsubo is less than 100 g / m ² , the rigidity of the paper becomes low, and the dimensional stability at the time of pasting the object and the workability at the time of pasting may be deteriorated. On the other hand, if the weight per square meter exceeds 200 g / m ² , the transportability and workability at the time of bonding in the billboard paper-dedicated inkjet printer may be deteriorated.

  A neutral rosin sizing agent may be used as an internal sizing agent to be internally added to paper. Examples of the sizing agent used in the neutral region using light calcium carbonate as a filler include alkenyl succinic anhydride (ASA) and alkyl ketene dimer (AKD) in addition to the neutral rosin sizing agent. In addition, when the alkyl ketene dimer is used, the friction coefficient of the paper is lowered, which may cause a slip problem in the printing, printing process and post-processing of billboard paper. In addition, in the case of alkenyl succinic anhydride, size development is greatly influenced by other additive chemicals at the time of papermaking, so handling may be difficult to ensure stable quality. For this reason, it is preferable to use a neutral rosin sizing agent that is stable in size and has no problem of slipping.

  The addition rate of the neutral rosin sizing agent is preferably 0.1 to 2.0% by mass, particularly preferably 0.5 to 1.5% by mass, based on the raw material pulp. If the addition rate is less than 0.1% by mass, the ink has good drying properties, but there is a possibility that the feathering resistance (scratching of the printed portion) and the back-through will be inferior. On the other hand, if it exceeds 2.0% by mass, the ink drying property when printed by an ink jet printer may be lowered. Further, since the spread of ink droplets on the paper is suppressed, there is a possibility that an original pattern is not formed and a white printed matter is generated.

  The neutral rosin sizing agent is an emulsion-type rosin sizing agent in which a rosin-based material is dispersed with various emulsifying dispersants, which are used in a weakly acidic to weakly antaritic region (neutral region) having a pH of 6 to 9. Examples of rosin substances include rosins such as gum rosin, wood rosin, tall oil rosin, etc., modified rosins modified with α, β-unsaturated carboxylic acids such as fumaric acid, maleic acid, and acrylic acid, or anhydrides thereof, and the above rosins. A rosin ester obtained by reacting polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, diglycerin and the like can be used. In addition, one obtained by emulsifying alone or a mixture thereof, or one obtained by emulsifying alone may be used. Furthermore, what added various polymers to the said rosin emulsion in order to improve size developability can also be used.

  Instead of the internal sizing agent, a surface sizing agent may be added to the ink receiving layer coating liquid described later. As the surface sizing agent, a styrene acrylate system can be used. Use of a styrene acrylate-based sizing agent is preferable because high ink fixing properties and ink absorption drying properties can be imparted during printing. The surface sizing agent used in the present invention is of a solution type or an emulsion type. The addition amount of the surface sizing agent is preferably 0.5% by mass or more in terms of solid content with respect to the solid content of the coating liquid for the ink receiving layer. This is because if the amount is less than 0.5% by mass, no effect is observed on the absorption drying property of the inkjet ink.

<Wet paper strength enhancer>
As the wet paper strength enhancer, those mainly composed of urea-formaldehyde resin, polyamide-polyamine epichlorohydrin resin, and melamine-formaldehyde resin can be used. When the wet paper strength enhancer is contained in the substrate, it is preferably contained in the substrate at a ratio of 0.3 to 1.5% by mass. When it is less than 0.3% by mass, sufficient wet paper strength cannot be obtained. Even if contained in an amount of 1.5% by mass or more, the wet paper strength is not further increased, and not only the cost is increased, but the disaggregation property at the time of recycling may be deteriorated. On the other hand, when the wet paper strength enhancer is applied to the substrate, it is preferably applied under the condition of 1.0 to 5.0 g / m ² . If the coating amount is less than 1.0 g / m ² , sufficient wet paper strength may not be obtained. If it is 5.0 g / m ² or more, there may be a problem that the coating workability is lowered and the covering property of the waterproofing agent layer is lowered. The billboard paper of this embodiment contains a wet paper strength enhancer on the base material or is coated with the wet paper strength enhancer on the base material. Dimensional stability and strength against tension and tear after applying water paste can be maintained.

<Waterproofing agent layer>
As a coating solution for the water resistant agent layer, a binder containing an inorganic pigment can be used. The inorganic pigment is contained in order to improve the transportability of billboard paper during printing while maintaining appropriate water absorption. An acrylic synthetic rubber can be used as the binder. As acrylic synthetic rubber, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, styrene acrylic, acrylamide, acrylonitrile, etc. can be used, for example. Further, synthetic rubber emulsions such as styrene / butadiene (SBR), acrylonitrile / butadiene (NBR), butadiene (BR), and polyvinyl alcohol (PVA) may be used in combination. Among these, those using styrene / butadiene emulsions or acrylonitrile / butadiene emulsions as synthetic rubber emulsions are more preferred because they improve water resistance, surface strength, heat resistance, pigment fixing properties and the like.

  The glass transition temperature of the acrylic synthetic rubber is preferably in the range of -40 to 25 ° C. Below -40 ° C, the water resistance is good, but the shape is easily changed by heat, so the paper transportability becomes worse and the coating film becomes soft and difficult to shear. There is a possibility that the disaggregation of will deteriorate. When the temperature exceeds 25 ° C., the disintegration property under the shearing force of the coating film is improved, but the water resistance may be deteriorated because the film forming property is deteriorated.

  Examples of inorganic pigments include calcium bicarbonate, light calcium carbonate, calcium sulfite, gypsum, talc, kaolin, clay, calcined kaolin, white carbon, amorphous silica, deramikaolin, diatomaceous earth, magnesium carbonate, titanium dioxide, and oxidation. Zinc, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, or the like can be used. It is more preferable to use kaolin having a high covering property and light calcium carbonate having an effect of improving the friction coefficient in combination.

  The particle diameter of kaolin is 0.1 μm to 8.0 μm, preferably 0.2 μm to 5.0 μm. The particle diameter of light calcium carbonate is 0.2 μm to 8.5 μm, preferably 0.2 μm to 5.0 μm. By setting these particle diameters, it is possible to form fine irregularities on the water-proofing agent layer and increase the frictional resistance value on the surface of the water-proofing agent layer, thereby preventing slipping during printing. If any particle size exceeds the upper limit, the gap in the water-resistant agent layer becomes large and the paste easily penetrates, so that cockling may easily occur when applying the water paste during the pasting process. There is. Conversely, if any particle size is below the lower limit, the gap in the water-resistant agent layer becomes small, so that cockling is less likely to occur, but the surface of the water paste is likely to be repelled. In this embodiment, since the water-proofing agent layer contains at least a binder and an inorganic pigment in this way, the billboard paper is excellent in water resistance, resistance to cockling, and transportability in a printing machine.

  The particle diameter of the inorganic pigment is a volume average particle diameter measured by a laser analysis type particle size distribution measuring apparatus “SALD-2200 type” manufactured by Shimadzu Corporation.

  The content of the inorganic pigment relative to the acrylic synthetic rubber is preferably in the range of 10 to 120 parts by weight with respect to 100 parts by weight of the acrylic synthetic rubber. If the amount is less than 10 parts by weight, the paper transportability may be deteriorated or the water resistance may be increased, and surface repellency may occur. If it exceeds 120 parts by weight, the water resistance may decrease.

  A crosslinking agent may be blended in the waterproofing agent layer. Examples of the crosslinking agent include ammonium zirconium carbonate, zirconium alkoxide, zirconium chloride, zirconium acetate, zirconium nitrate zirconium sulfate, glyoxal, methylol melamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, chloride. Use ammonium, formalin, glycine, glycidyl ester, glycidyl ether, dimethylol urea, ketene dimer, boric acid, borax, dialdehyde, polyamide resin, melamine resin, polyamide-epifluorohydrin resin, ketone-aldehyde resin polyethyleneimide resin . The reason for adding the cross-linking agent is that by adding it, the water retention of the paint can be improved and binder migration can be suppressed. Thereby, the continuity of the coating film is improved and the water resistance of the coating film is improved by the crosslinking action with the binder. Therefore, the printability required for billboard paper can be satisfied, and the dimensional stability at the time of bonding the object, the maintenance of the tensile and tear strength at the time of posting, and the weather resistance can be sufficiently exhibited.

  The amount of the crosslinking agent is preferably 0.1 parts by weight or more with respect to 100 parts by weight of the acrylic synthetic rubber. If the amount is less than 0.1 parts by weight, contribution to water resistance is not observed, and transportability may not be improved.

The coating amount of the waterproofing agent layer is preferably 4.0 to 15.0 g / m ² . If the coating amount is less than 4.0 g / m ² , the water absorption may exceed 5.0 g / m ² , and the dimensional stability may be lowered to cause unevenness. When the coating amount exceeds 15.0 g / m ² , surface repellency of the water paste at the time of application is generated, and the water paste cannot be applied evenly, which may deteriorate the workability and workability.

<Ink receiving layer>
An inorganic pigment and a binder can be used as a coating liquid for the ink receiving layer. As the inorganic pigment, it is preferable that silica, particularly silica and aluminum hydroxide coexist. Due to the presence of silica, the absorption drying property of the latex ink can be secured. The presence of aluminum hydroxide can suppress a decrease in color density of the ink-jet ink.

  PVA or latex can be used as the binder, but PVA is more preferable than latex in terms of ink drying properties and film properties. When PVA is used as the binder, the degree of polymerization is preferably 1,500 or more, and more preferably 2,000 or more. When the degree of polymerization is less than 1,500, a sufficient film cannot be obtained, and a crack (crack) occurs in the ink receiving layer during the pasting operation, and the finish after pasting may be deteriorated. The saponification degree is preferably complete saponification. If the degree of saponification is low, a sufficient film cannot be obtained, and a crack (crack) is generated in the ink receiving layer at the time of application work, and the finish after application may be deteriorated.

  The kind of silica used as the inorganic pigment is not particularly limited, and precipitation method silica, precipitation method silica, gel method silica, colloidal silica and the like, which are amorphous synthetic silica, are used, and gel method silica is particularly preferable. The reason is that the ink is easily absorbed into the pores of the primary particles. Further, the particle diameter is 1.0 to 7.0 μm, preferably 2.0 to 5.0 μm. If it is less than 1.0 μm, there is no void in the ink receiving layer, and the ink absorbability tends to decrease. If it exceeds 7.0 μm, the voids in the ink receiving layer are large, and printing unevenness tends to occur. Aluminum hydroxide used as the inorganic pigment may be crystalline or non-crystalline. As the shape, an arbitrary shape such as an irregular particle, a spherical particle, or an acicular particle can be used. The particle diameter is in the range of 0.5 to 15.0 μm, preferably 0.5 to 5.0 μm. If it exceeds 15.0 μm, ink bleeding occurs, and if it is less than 0.5 μm, the effect reaches its peak. The content of the inorganic pigment is 40 to 80% by mass, preferably 50 to 70% by mass with respect to 100% by mass of the ink receiving layer. If the content of the inorganic pigment is less than 40% by mass, the ink density, ink drying property, and ink color density may decrease. If the content exceeds 80% by mass, the surface strength may decrease and a sufficient film may be obtained. Otherwise, the ink receiving layer may crack during the pasting operation, and the finish after pasting may be deteriorated. The ratio of silica and aluminum hydroxide is, by mass blending ratio, preferably 1: 0.5 to 1: 3, more preferably 1: 1 to 1: 2. By setting the ratio of silica and aluminum hydroxide within this range, the ink drying property and the ink concentration are well balanced, and the billboard paper has good printability.

The coating amount of the ink receiving layer is preferably 5 to 15 g / m ² in consideration of a decrease in dimensional stability due to inkjet ink, a decrease in ink concentration, excess quality, and the like. If the coating amount of the ink receiving layer is less than 5 g / m ² , the ink concentration and the ink drying property may be insufficient, and the dimensional stability in the inkjet ink may be reduced. On the other hand, if it exceeds 15 g / m ² , the ink density and ink drying properties are good, but there is a risk that the quality will be excessive and the cost will be high, and cracks may easily occur in the ink receiving layer during the pasting operation.

<Manufacturing method>
The ink receiving layer is provided by coating the ink receiving layer on one side of the paper. Various methods such as blade coater, air knife coater, roll coater, brush coater, champlex coater, bar coater, lip coater, gravure coater, curtain coater, slot die coater, slide coater, spray, etc. A publicly known coating apparatus can be used. Among these, air knife coaters, lip coaters, slide coaters, curtain coaters, and slot die coaters are preferably used. When these coating apparatuses are used, the coating layer can be formed with a uniform thickness that is not easily affected by minute irregularities of the air-permeable base material or the undercoat layer, and thus the glossiness tends to be improved.

  The wet paper strength enhancer is mixed with a pulp raw material at a predetermined ratio before paper making, and then paper is made. Alternatively, the wet paper strength enhancer is applied to the surface opposite to the side on which the ink receiving layer is provided by on-machine size press, spray coating, off-machine dipping impregnation, coating by various coating machines, etc. Coated.

  By applying a coating solution containing at least an acrylic synthetic rubber and an inorganic pigment on the other surface side of the paper, a water-resistant agent layer is provided. In addition, when the wet paper strength enhancer is coated, the waterproofing agent layer is applied to the coated wet paper strength enhancer. As a method of coating the water-proofing agent layer, blade coater, air knife coater, roll coater, brush coater, Champex coater, bar coater, lip coater, gravure coater, curtain coater, slot die coater, slide coater, spray, etc. Various known coating devices can be used. Among these, air knife coaters, lip coaters, slide coaters, curtain coaters, and slot die coaters are preferably used. When these coating apparatuses are used, the coating layer can be formed with a uniform thickness that is not easily affected by minute irregularities of the air-permeable base material or the undercoat layer, and thus the glossiness tends to be improved.

<Characteristic>
Properties of billboard paper prepared as described above (opacity, wet strength, elongation in water, contact angle, water resistance (water absorption), air permeability, transportability, ink concentration, ink drying property, cock resistance (Ring property, surface repellency, film brittleness) will be described below.

Opacity The opacity of the paper substrate measured according to JIS P 8149 is preferably 95% or more, more preferably 98% or more. This is because if the opacity is less than 95%, when a board or wall to be pasted has characters or patterns on it, it is reflected on the printed surface of the billboard paper. In addition, when using a paper base material having an opacity of less than 95%, a dye is added to the water-resistant agent layer in order to prevent show-through. Alternatively, the paper may have a two-layer structure of a white paper layer and a colored paper layer, and a wet paper strength enhancer and a water resistant agent layer may be applied to the colored paper layer. In this embodiment, the opacity can be adjusted by, for example, the basis weight, the blending mass ratio of the pulp raw material, the coating amount of the ink receiving layer and the water resistant agent layer, and the like.

Wet strength It is preferable that the wet strength measured according to JIS P 8135 is in the range of 1.5 N / m or more in length and 0.9 N / m or more in width. This is because if the wet strength is less than 1.5 N / m in length and less than 0.9 N / m in width, the strength is too weak and the billboard paper may be broken at the time of application. In this embodiment, the wet strength can be adjusted by basis weight, the addition amount of the wet paper strength enhancer, the addition amount of the sizing agent, the coating amount of the water resistant agent layer, and the like.

Elongation in water It is desirable that the elongation in water measured according to JAPAN TAPPI paper pulp test method No. 27: 2000 is 1.0% or less in length and 4.5% or less in width. This is because, when the elongation in water exceeds 1.0% in length and exceeds 4.5% in width, the curling of the paper at the time of pasting may not be prevented. In this embodiment, the elongation in water can be adjusted by, for example, the blending mass ratio of the pulp raw material, the basis weight, the addition amount of the wet paper strength enhancer, the coating amount of the water resistant agent layer, and the like.

Contact angle The contact angle on the surface of the waterproofing agent layer measured according to JIS K 3211 is preferably in the range of 60 ° or less. Moreover, the range of 40-60 degrees is more preferable. If it exceeds 60 °, surface repellency of the water paste is generated and the processability is lowered, and if it is less than 40 °, cockling may occur. In this embodiment, the contact angle can be adjusted by the coating amount of the water resistant agent layer, the ratio of the inorganic pigment and the binder in the water resistant agent layer, and the like.

Water resistance (water absorption)
The water absorption after 2 minutes on the surface of the waterproofing agent layer according to the water absorption test method of JIS P 8140 is preferably 5.0 g / m ² or less. This is because if the water absorption exceeds 5.0 g / m ² , the corrugation on the paper surface becomes large, which may cause a problem in the finish after pasting billboard paper. In the present invention, the water absorption can be adjusted by the coating amount of the waterproofing agent layer, the ratio of the inorganic pigment and binder in the waterproofing agent layer, and the like.

Air permeability The air permeability measured according to JIS P 8117 is preferably in the range of 18,000 seconds or less. If it exceeds 18,000 seconds, there is a possibility that the drying speed of the water paste applied at the time of pasting will be slow and workability may be deteriorated. If it is 18,000 seconds or less, the performance as billboard paper can be ensured. . In this embodiment, the air permeability can be adjusted by the basis weight, the coating amount of the waterproofing agent layer, the ratio of the inorganic pigment and binder in the waterproofing agent layer, and the like.

  Thus, even if the billboard paper in this embodiment is a base material made of wood pulp, an ink receiving layer is provided on one side of the base material, and a water-resistant agent layer is provided on the other side. In addition, the wet paper strength enhancer is contained in the base material or coated between the base and the water-proofing agent layer, and the water-proofing agent layer contains at least an acrylic synthetic rubber and an inorganic pigment. , Excellent dimensional stability when pasting objects, strength against tension and tear when posting, affinity with glue, and excellent printability such as ink density, ink drying property, transportability in printing machine, etc. Yes.

In addition, the billboard paper in this embodiment has an ink receiving layer on one side of the substrate and a water-resistant agent layer on the other side, and has a wet strength (vertical) of 1.5 kN / m. As described above, the wet paper strength enhancer is contained in the base material in an amount of 0.3% by mass or more and 1.5% by mass or less, or is applied by 1.0 g / m ² or more and 5.0 g / m ² or less. The water-resistant agent layer contains at least acrylic synthetic rubber and inorganic pigments, so there is no cockling when water-impregnated and coated, and paper strength is not reduced. Is good. Moreover, it is excellent in printability, such as ink density, ink drying property, and transportability in a printing machine.

Moreover, the billboard paper in this embodiment has an ink receiving layer on one side of the substrate and a water-resistant agent layer on the other side, and has a wet strength (vertical) of 1.5 kN / m, the wet paper strength enhancer is contained in the substrate in an amount of 0.3% by mass to 1.5% by mass, or 1.0 g / m ² or more and 5.0 g / m ² or less. The waterproofing agent layer includes at least one acrylic synthetic rubber having a glass transition temperature in the range of −40 ° C. or more and 25 ° C. or less, and at least one or more types per 100 parts by weight of the acrylic synthetic rubber. 10 parts by weight or more and 120 parts by weight or less of the inorganic pigment and 0.1 part by weight or more of the cross-linking agent are included, so that the water resistance and cockling resistance are better, and the paste has an appropriate water absorption. The aptitude is better.

Furthermore, the billboard paper in this embodiment has an ink receiving layer on one side of the substrate and a water-resistant agent layer on the other side, and has a wet strength (vertical) of 1.5 kN / m, the wet paper strength enhancer is contained in the substrate in an amount of 0.3% by mass to 1.5% by mass, or 1.0 g / m ² or more and 5.0 g / m ² or less. The waterproofing agent layer includes at least one acrylic synthetic rubber having a glass transition temperature in the range of −40 ° C. or more and 25 ° C. or less, and at least one or more types per 100 parts by weight of the acrylic synthetic rubber. 10 parts by weight or more and 120 parts by weight or less of the inorganic pigment, and 0.1 parts by weight or more of the crosslinking agent, and the coating amount of the waterproofing agent layer is 4.0 g / m ² or more and 15.0 g / m ² or less. A contact angle on the surface of the water-resistant agent layer is 60 ° or less; Water absorption after 2 minutes is at 5.0 g / m ² or less at the surface, the elongation in water of the recording paper, vertical 1.0% and not more than horizontal 4.5%, air permeability of the recording sheet Since the degree is 18,000 seconds or less, even if it is a base paper made of wood pulp, water glue is impregnated and applied, so that the water glue is not repelled on the mirror surface of the coating surface and the occurrence of cockling or paper There is no decrease in strength, the processability at the time of sticking is good, and both the water resistance and workability are provided. At the same time, it is excellent in printability such as ink density, ink drying property, and transportability in a printing machine.

  The present invention will be described in detail with reference to examples, but the contents of the present invention are not limited to the examples. In addition, in a present Example, the numerical value which shows a mixing | blending, a density | concentration, etc. is a numerical value of the mass reference | standard of solid content or an active ingredient. Hereinafter, “1. Material creation”, “2. Evaluation method”, and “3. Evaluation result” will be described in order. Details of Examples 1 to 39 and Comparative Examples 1 and 2 are shown in Tables 1 to 9.

1. Sample preparation <paper>
Softwood kraft pulp (NB) and hardwood kraft pulp (LB) were used in the proportions shown in the table to obtain paper as a substrate. The Runkel ratio and freeness were as shown in the table. If necessary, an internal sizing agent was contained in the paper. As the internal sizing agent, a neutral rosin sizing agent (product name: CC-1401, manufactured by Seiko PMC Co., Ltd.) was used.

  At the time of paper production, the basis weight and paper thickness shown in the table were adjusted. As the paper machine, a long mesh multi-cylinder paper machine or a long mesh Yankee type paper machine was used. A sulfuric acid band was blended and adjusted so that the paper surface pH shown in the table was obtained. In the table, the long mesh multi-cylinder paper machine is denoted as “H”, and the long mesh Yankee type paper machine is denoted as “I”.

<Wet paper strength enhancer>
Urea-formaldehyde resin (product name: Sumirez Resin 8% AC, manufacturing company name: Taoka Chemical Co., Ltd.), polyamide-polyamine epichlorohydrin resin (product name: WS4024, manufacturing company name: Seiko PMC) And melamine-formaldehyde resin polyamide (product name: P-1500, manufacturing company name: Mitsui Chemicals, Inc.) were used. The wet paper strength enhancer was contained in the paper at the concentration shown in the table, or was applied to the paper surface by the amount shown in the table. When the wet paper strength enhancer was contained in the paper, the paper was made after mixing with the pulp raw material at the concentration shown in the table before paper making. When applying the wet paper strength enhancer, it was applied to the paper surface by dipping impregnation off-machine. In the table, urea-formaldehyde resin is expressed as “D”, polyamide-polyamine epichlorohydrin resin is expressed as “E”, and melamine-formaldehyde resin polyamide is expressed as “F”.

<Ink receiving layer>
As inorganic pigments constituting the ink receiving layer, wet silica (product name: AZ series, manufacturer name: Tosoh Silica Co., Ltd.) and aluminum hydroxide (product name: B-703, manufacturer name: Nippon Light Metal Co., Ltd.) )). The volume average particle diameter of wet silica and aluminum hydroxide and the weight part ratio of wet silica and aluminum hydroxide were as shown in the table. Further, the content of the inorganic pigment in 100% by mass of the ink receiving layer described later was as shown in the table. In the table, wet silica is expressed as “J” and aluminum hydroxide is expressed as “K”.

  Further, PVA (product name: PVA-120, manufacturer name: Kuraray Co., Ltd.) was used as a binder constituting the ink receiving layer. The polymerization degree and saponification degree of PVA were as shown in the table. In the table, PVA is expressed as “L”. In the table, the case of complete saponification at a rate of 98.5 mol% is expressed as “complete”, the case of partial saponification at a rate of 88 mol% is expressed as “partial”, and the rate is as low as 80 mol%. The case of saponification was expressed as “low”. The content of PVA in 100% by mass of the ink receiving layer was as shown in the table. Further, SBR latex (product name: NipolPPT651, manufacturing company name: Nippon Zeon Co., Ltd.) was added as necessary. The content of the SBR latex in 100% by mass of the ink receiving layer was as shown in the table. In the table, SBR latex was indicated as “M”. The SBR latex can suppress a decrease in water-resistant printing density, but when it is excessively contained, there is a problem that printing suitability is lowered. Further, a fixing agent (product name: DK6584, manufacturing company name: Starlight PMC) as an auxiliary was blended in an amount of 5% by mass in 100% by mass of the ink receiving layer. The ink receiving layer was coated with an air knife coater at a coating amount shown in the table.

<Waterproofing agent layer>
As inorganic pigments constituting the water-resistant agent layer, kaolin (product name: kao gloss, manufacturing company name: THIELE) and light calcium carbonate (product name: TP-121-6S, manufacturing company name: Okutama Kogyo Co., Ltd.) It was used as a raw material by appropriately adjusting the volume average particle diameter as shown in the table with a wet pulverizer. In the table, kaolin was represented as “N” and light calcium carbonate was represented as “O”. The content of kaolin and light calcium carbonate and the proportion by weight of kaolin and light calcium carbonate with respect to 100 parts by weight of acrylic synthetic rubber to be described later were as shown in the table. As the binder, an acrylic synthetic rubber (product name: PDX7341, manufacturer: BASF) was used. The glass transition point of the acrylic synthetic rubber was used by changing the glass transition point of this latex as shown in the table based on PDX7341 (Tg15 ° C., manufactured by BASF).

  A crosslinking agent (product name: Epocross WS700, manufacturer name: Nippon Shokubai Co., Ltd.) was blended with acrylic synthetic rubber and inorganic pigment. The content of the crosslinking agent relative to 100 parts by weight of the acrylic synthetic rubber was as shown in the table.

Inorganic pigment, binder, and cross-linking agent were mixed before coating. The waterproofing agent layer was coated on paper with the coating amount shown in the table. In addition, when the wetting enhancer was coated on the paper, the waterproofing agent layer was applied on the coated wetting enhancer. The waterproofing agent layer was applied with a blade coater.

2. Evaluation method For each of opacity, wet strength, elongation in water, contact angle, water absorption, air permeability, transportability, ink concentration, ink drying property, cockling resistance, surface repellency, and film fragility The sample was measured by the method. The evaluation results are shown in Table 7 to Table 9.

  The opacity was measured based on JIS P 8149. The wet strength was measured based on JIS P 8135. The underwater elongation is measured by JAPAN TAPPI No. 27: 2000. The contact angle was measured based on JIS K 3211. The water absorption was measured based on JIS P 8140. The air permeability was measured based on JIS P 8117.

Regarding transportability, printing was performed on 1,000 A4 sheets using a household inkjet printer MP-520 (manufactured by Canon), and the following was evaluated.
5: Paper jam 0 sheet 4: Paper jam 1-2 sheets 3: Paper jam 3-4 sheets 2: Paper jam 4-5 sheets 1: Paper jam 6-7 sheets If the evaluation is 3-5, billboard paper It was evaluated as usable.

<Ink density>
Printing was performed using a home inkjet printer MP-520 (manufactured by Canon), and it was evaluated whether the total print density of each color (black, cyan, magenta, yellow) corresponds to the following.
5: Print density 4.00 or more 4: Print density 3.80 or more and less than 4.00 3: Print density 3.60 or more and less than 3.80 2: Print density 3.40 or more and less than 3.60 1: Print density Less than 40 If the evaluation is 3 or more, the color development is good and can be used practically. If the evaluation is 2 or less, the color development is inferior and the appearance is poor, so that it cannot withstand actual use.

<Ink drying properties>
Using a home inkjet printer MP-520 (manufactured by Canon) in an environment of 23 ° C. and 50% RH, black, cyan, magenta and yellow colors are printed on each test piece (each size is 3.0 cm). × 3.0 cm). And after the test piece discharge | emission, the stain | pollution | contamination degree of the tissue paper at the time of rubbing a printing part with tissue paper 5 seconds after was visually determined, and it was evaluated whether it corresponds to either of the following.
5: No ink stains 4: Ink stains are slightly conspicuous 3: Ink stains are slightly conspicuous 2: Ink stains are conspicuous 1: Ink stains are quite conspicuous If the evaluation is 3-5, it is used as billboard paper Evaluated as possible.

<Cockling resistance>
By evaluating the cockling, it was confirmed that the billboard paper was not wet. 20 g of water paste (PVA-417, solid content 10%) was evenly applied to the surface of the waterproofing agent layer of billboard paper cut to A4 size. After 30 minutes, the state of the cock ring was visually observed to evaluate which of the following applies.
5: No cockling at all 4: Cockling is slightly conspicuous 3: Cock ring is slightly conspicuous 2: Cock ring is conspicuous a lot 1: Cock ring conspicuously conspicuous Evaluation 3-5 can be used as billboard paper It was evaluated.

<Surface repellent>
20 g of water paste (PVA-417, solid content 10%) was evenly applied to the surface of the waterproofing agent layer of billboard paper cut to A4 size. After 30 minutes, the condition of the surface repelling was visually observed to evaluate which of the following was true.
5: No surface repelling 4: Surface repelling is slightly conspicuous 3: Surface repelling is slightly conspicuous 2: Surface repelling is conspicuous a lot 1: Surface repelling is conspicuous considerably Remarks 3 to 5 are used as billboard paper Evaluated as possible.

<Vulnerability of film>
Each billboard paper was formed into a cylindrical shape with a diameter of 60 mm so that the printing surface would be outside at 20 ° C. and a relative humidity of 20%. After storing in this state for 24 hours, the surface cracked state was confirmed visually and with a magnifying glass to evaluate which of the following was true.
5: No cracks 4: Slightly conspicuous cracks 3: Slightly conspicuous cracks 2: Conspicuous many cracks 1: Conspicuously many conspicuous evaluations If evaluation 3-5, evaluation is possible as billboard paper did.

  The billboard papers of Examples 1 to 39 have an ink receiving layer and a water-proofing agent layer, and the water-proofing agent layer contains at least an acrylic synthetic rubber and an inorganic pigment. Is contained in the base material or is coated between the base material and the water-resistant agent layer, so that wet paper strength, dimensional stability, cockling resistance, strength against tension or tear at the time of posting, Billboard paper with excellent compatibility with glue and water resistance and workability. In addition, the billboard paper was excellent in ink density, ink drying property, and transportability in a printing machine.

On the other hand, Comparative Examples 1 and 2 have no wet paper strength enhancer added, and are inferior in wet strength, dimensional stability, cockling resistance, or do not contain an inorganic pigment in the waterproofing agent layer. Therefore, it became billboard paper inferior in surface repellency and transportability.

Claims (5)

It is a recording paper made of wood pulp, an ink receiving layer is provided on one side of the base material, and a water resistant agent layer is provided on the other side of the base material,
In the ink receiving layer,
Polyvinyl alcohol is included as a binder, silica and aluminum hydroxide are included as inorganic pigments,
In the waterproofing agent layer,
At least an acrylic synthetic rubber, are included kaolin and calcium carbonate as the inorganic pigment,
A recording paper, wherein a wet paper strength enhancer is contained in the base material, or is coated between the base material and the waterproofing agent layer. The wet paper strength enhancer is
At least one of urea-formaldehyde resin, polyamide-polyamine epichlorohydrin resin, and melamine-formaldehyde resin is included, and the wet strength (longitudinal) of the recording paper according to JIS P 8135 is 1.5 kN / m or more. Further, it is contained in the base material at a ratio of 0.3% by mass or more and 1.5% by mass or less, or is coated by 1.0 g / m ² or more and 5.0 g / m ² or less. The recording paper according to claim 1. The waterproofing agent layer is
One or more kinds of acrylic synthetic rubber having a glass transition temperature in the range of −40 ° C. or more and 25 ° C. or less are contained, and at least one kind of inorganic pigment is 10 parts by weight or more and 120 parts per 100 parts by weight of the acrylic synthetic rubber. The recording paper according to claim 1 or 2, wherein the recording paper contains not more than 1 part by weight and not less than 0.1 parts by weight of a crosslinking agent. The coating amount of the waterproofing agent layer is 4.0 g / m ² or more and 15.0 g / m ² or less, and the contact angle on the surface of the waterproofing agent layer is 60 ° or less measured according to JIS K 3211. The water absorption after 2 minutes on the surface of the waterproofing agent layer, measured according to JIS P 8140, is 5.0 g / m ² or less, and the JAPAN TAPPI paper pulp test method No. 27, the underwater elongation of the recording paper measured in accordance with No. 27 is 1.0% or less in length and 4.5% or less in width, and the air permeability of the recording paper measured in accordance with JIS P 8117 is 4. The recording paper according to claim 1, wherein the recording paper is 18,000 seconds or less. A method for producing recording paper made of wood pulp,
An ink receiving layer containing polyvinyl alcohol as a binder and silica and aluminum hydroxide as an inorganic pigment is provided on one surface of the substrate, and at least an acrylic synthetic rubber and an inorganic material are provided on the other surface of the substrate. a step of providing a water resistant adhesive layer containing kaolin and calcium carbonate as a pigment,
A method for producing a recording paper, comprising: a wet paper strength enhancer contained in the base material, or a step of being applied between the base material and the waterproofing agent layer.