JP2009150012A - Coated paper for gravure printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated paper for gravure printing which is producible from inexpensive raw materials, has high cushioning property and smoothness, is excellent in not only color fading resistance but also gravure printability, and has high whiteness. <P>SOLUTION: The coated paper for gravure printing has a base paper and at least one pigment-coating layer composed mainly of a pigment and an adhesive and formed on the base paper. The pigment-coating layer contains a softener comprising an aliphatic polyether compound, and the regular reflection smoothness on the pigment-coated surface measured by a total reflection printing smoothness tester is 75% or more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coated paper for gravure printing. More specifically, the present invention relates to a coated paper for gravure printing that has high whiteness and can be suitably used for high-grade commercial prints such as high-quality art prints, catalogs, pamphlets, and calendars.

  In general, printing methods include lithographic printing (offset printing), intaglio printing (gravure printing), letterpress printing (flexographic printing), etc., but in women's magazines and high-quality art printed materials that require beautiful printing, gravure printing Printing is preferably used. This is because gravure printing expresses the density of printing in terms of ink density, and is superior in gradation expression power compared to offset printing expressed in halftone dots. However, on the other hand, the paper used for gravure printing is required to have smoothness and flexibility for uniformly transferring the ink of the intaglio part.

  In conventional gravure printing paper, in order to improve its flexibility, a measure that uses a lot of flexible mechanical pulp as the pulp component of the base paper, and in order to improve smoothness, coating pigment As a countermeasure, a method of frequently using kaolin clay, which has a good covering of the coating layer and is easily oriented, is employed.

  However, all of these measures tend to reduce the whiteness of the gravure coated paper. That is, the whiteness of mechanical pulp is lower than that of bleached kraft pulp generally used in conventional printing paper, and the whiteness of kaolin clay is lower than that of calcium carbonate generally used as a pigment in conventional printing paper. As a result, the whiteness of the conventional gravure printing coated paper is usually about 70 to 80%, and the current level of whiteness remains low compared to general coated paper (80 to 90%). is there.

  On the other hand, the general coated paper is certainly higher in whiteness than the coated paper for gravure printing, but the paper itself is not flexible, so it is not suitable for gravure printing and is not suitable for high-grade printing. Therefore, there is a demand for a coated paper having the advantages of both, that is, a coated paper having whiteness comparable to that of a general coated paper and having gravure printing suitability. By using, it becomes possible to realize a high-quality printed matter with higher contrast.

  In order to obtain coated paper for gravure printing with high whiteness, for example, mechanical pulp is blended and calcium sulfate is used as a pigment (Patent Document 1), or by blending a specific shape of calcium carbonate, Although a method for obtaining coated paper without using pulp (Patent Document 2) has been proposed, all of them require the use of a special pigment, and although the cost is high, a high white color suitable for it. Coated paper having gravure printability at a degree is not always obtained.

Thus, as a pigment, it uses inexpensive calcium carbonate and kaolin clay that are generally used for coated paper applications, and without using a large amount of mechanical pulp, it has a high whiteness gravure that is suitable for gravure printing. Actually, the coated paper for printing has not yet been obtained.
JP 2006-70374 A JP-A-6-73695

  The present invention was made to solve the problems of the prior art, inexpensive materials are used, cushioning and smoothness is high, not only excellent in fading resistance, but also excellent in gravure printing suitability, And it aims at providing the coated paper for gravure printing which has high whiteness.

The present invention
A coated paper for gravure printing having a base paper and at least one pigment coating layer mainly composed of a pigment and an adhesive on the base paper,
The pigment coating layer contains a softening agent composed of an aliphatic polyether compound,
The present invention relates to a coated paper for gravure printing, wherein the regular reflection smoothness of the pigment coating layer surface measured by a total reflection type printing smoothness meter is 75% or more.

  According to the present invention, a coating material for gravure printing having high cushioning properties and smoothness, not only excellent in fading resistance but also excellent in gravure printing suitability and having high whiteness can be obtained using an inexpensive raw material. It can be obtained at low cost.

(Embodiment)
The coated paper for gravure printing of the present invention has a base paper and at least one pigment coating layer on the base paper, and the pigment coating layer is mainly composed of a pigment and an adhesive. The pigment coating layer contains a specific softening agent.

  First, the base paper which comprises the gravure printing coated paper which concerns on this embodiment is demonstrated.

  The base paper should just be obtained by papermaking a normal raw material pulp. The raw material pulp is not particularly limited. For example, chemical pulp such as unbleached softwood pulp (NUKP), unbleached hardwood pulp (LUKP), bleached softwood pulp (NBKP), bleached hardwood pulp (LBKP), etc .; Stone Grand Pulp (SGP) ), Pressurized Stone Grand Pulp (PGW), Refiner Grand Pulp (RGP), Chemi Grand Pulp (CGP), Thermo Grand Pulp (TGP), Grand Pulp (GP), Thermo Mechanical Pulp (TMP), Chemi Thermo Mechanical Pulp ( CTMP), refiner mechanical pulp (RMP) and other mechanical pulp; tea waste paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, leaflet waste paper, office waste paper, corrugated waste paper, Kakuhishi waste paper, Kent waste paper, imitation waste paper, Jiju waste paper, Disaggregated waste paper pulp made from recycled paper, etc. Ink waste paper pulp, waste paper pulp such as disaggregation / deinking / bleached waste paper pulp, pulp bleached from these, etc. are selected, one or more of these are appropriately selected, and the ratio is adjusted and used be able to.

  However, in the present invention, in order to obtain a coated paper for high whiteness gravure printing having a whiteness of the pigment coating layer surface of 85% or more as described later, the content of mechanical pulp in the base paper is the total amount of pulp. It is desirable to keep it at 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. The amount of this mechanical pulp is the amount contained in the base paper of the gravure coated paper, and the content intentionally blended as a raw material and the content unintentionally mixed from waste paper pulp are combined. It is the amount relative to the total amount of pulp. Therefore, in order to suppress the content of mechanical pulp to 10% by mass or less, it is preferable that mechanical pulp is not intentionally blended as a raw material, and the content of waste paper pulp is also suppressed to 50% by mass or less. Thus, by controlling the content of the mechanical pulp in the base paper to 10% by mass or less of the total amount of the pulp, the whiteness of the pigment coating layer surface can be improved to 85% or more. Is added to the pigment coating layer to improve the gravure printing suitability, and a coated paper for gravure printing with a higher whiteness can be obtained.

  In this embodiment, the raw material pulp is mixed to prepare a papermaking raw material (stock slurry). For example, an internal additive sizing agent, a paper strength enhancer, a paper thickness improver, and a yield improver are added to the raw material pulp. Such various additives that are usually blended into the base paper of the coated paper can be internally added by appropriately adjusting the kind and blending amount thereof.

  After making the papermaking raw material as described above in the wire part and then supplying it to the press part and the pre-dryer part to produce the base paper, then after coating the base paper with the coating agent described later in the coater part It can be used for an after dryer part, a calendar part, a reel part, a winder part and the like to obtain a desired coated paper.

  In order to further improve the whiteness of the target coated paper for gravure printing, the whiteness of the base paper is measured by a color analyzer (model number: color i5, manufactured by Macbeth Gretag), 75% or more. It is preferable that it is 80% or more. When a gravure coated paper is produced from such a base paper, the whiteness of the pigment coated layer surface can be set to 90% or more, for example, as will be described later. And, when such a gravure coated paper having a whiteness of 90% or more is used, a high-quality printed material having a higher definition and a higher contrast than a gravure coated paper having a whiteness of less than 90%. It becomes possible to obtain.

Although there is no particular limitation on the basis weight of the base paper, as will be described later, considering that the basis weight of the target gravure printing coated paper is preferably 50 to 200 g / m ² , It is preferable to adjust the basis weight to be usually about 45 to 195 g / m ² .

  The base paper is preferably provided with an undercoat coating layer by applying an undercoat coating agent containing a sizing agent before providing a pigment coating layer to be described later. By providing the undercoat coating layer, it is possible to suppress moisture from the pigment coating agent from being absorbed into the base paper when a pigment coating agent mainly composed of a pigment and an adhesive described later is applied. It is possible to prevent the smoothness of the pigment coating layer from being deteriorated due to moisture absorption unevenness.

  In addition, it is not preferable to apply starch as the undercoat coating agent. This is because, by applying starch, the rigidity of the coated paper for gravure printing is improved, but there is a possibility that flexibility is lowered and gravure printing suitability is lowered.

Undercoat coating material (sizing agent solution) is, 0.1 to 1.5 g / m ² per one surface of the base paper at a solids coating weight, so preferably a 0.2~1.2g / m ^2, In the size press process in the paper making process, it is desirable to apply, for example, by a film transfer method. When the sizing agent is not blended or the solid content adhesion amount is less than 0.1 g / m ² , the base paper easily absorbs moisture when the pigment coating agent is applied, and the smoothness of the pigment coating layer. May decrease, and the gravure printability may also decrease. On the other hand, if the solid content adhesion amount exceeds 1.5 g / m ² , not only the size effect will reach a peak, but also the occurrence of mist during coating may cause defects such as foreign matter.

  As described above, the undercoating agent can be applied by various known methods in the size press process during the paper making process, but is preferably applied by a film transfer system. The film transfer system is a system in which an undercoat film in a wet state is formed on an applicator roll, and this undercoat film is transferred to the surface of the base paper. For example, a transfer roll coater, a rod metering size press coater, etc. Is used. Adopting the film transfer method allows you to apply an undercoat layer with a certain film thickness to the surface of the base paper, so that, for example, a method of forming a coating agent pound such as a two-roll size press In comparison, the penetration of the coating agent into the inside of the base paper is suppressed, and thin film coating on the base paper surface is possible. Therefore, when the primer coating agent is applied by the film transfer method, a uniform size effect is imparted to the surface of the base paper, and unevenness in the smoothness of the pigment coating layer is unlikely to occur due to moisture absorption unevenness. There is an effect. In the film transfer method, any method may be used for forming the undercoat coating film on the applicator roll.

  The type of sizing agent for forming the undercoat coating layer is not particularly limited. For example, styrene sizing agent, olefin sizing agent, acrylate sizing agent, styrene-acrylic sizing agent, etc. What is used for a use can be used suitably.

  There is no particular limitation on the method for preparing the undercoat coating agent, and it is preferable to add purified water as appropriate to the sizing agent so as to obtain a desired solid content concentration and stir at an appropriate temperature to obtain a uniform aqueous solution. .

  Next, the pigment coating layer formed on the base paper, preferably on the undercoat coating layer provided on the base paper will be described. On the base paper, preferably on the undercoat coating layer provided on the base paper, at least one pigment coating layer mainly composed of a pigment and an adhesive is formed.

  The type of the pigment is not particularly limited, and those generally used as papermaking pigments can be used. Examples of the pigment include heavy calcium carbonate, light calcium carbonate, kaolin clay, delaminated kaolin, talc and the like, and one or more of these can be appropriately selected and blended. Note that white carbon, titanium dioxide, calcium sulfate, and the like can be used as the special pigment having high whiteness. However, in the present invention, the target high pigment can be obtained without using the special pigment having high whiteness. Since a coated paper for gravure printing with whiteness can be obtained, it is preferable not to add the special pigment because cost can be reduced. Further, satin white, calcium sulfite, gypsum, barium sulfate, diatomaceous earth, magnesium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, magnesium oxide, as long as the effects of the present invention are not impaired. Inorganic pigments such as bentonite and sericite, and special pigments such as organic pigments such as polystyrene resin fine particles, urea formalin resin fine particles, fine hollow particles, and porous fine particles may be used in combination.

  Among the pigments excluding the special pigment, when heavy calcium carbonate is used, it is preferable because the whiteness of the coated paper for gravure printing is more easily improved. In particular, in the case of gravure coated paper, as a result of high blending of clay in order to improve the smoothness of the surface, the amount of heavy calcium carbonate is small and the whiteness is generally low, In the present invention, since the specific softening agent described later is contained in the pigment coating layer, sufficient smoothness can be imparted even when heavy calcium carbonate is blended in high, and the gravure printing suitability is improved. .

  The amount of the heavy calcium carbonate is preferably 30 parts by mass or more, more preferably 40 to 80 parts by mass, and particularly preferably 50 to 80 parts by mass with respect to 100 parts by mass of the total pigment. If the blending amount of heavy calcium carbonate is less than 30 parts by mass, the whiteness of the obtained gravure coated paper may not be sufficiently improved. Conversely, if it exceeds 80 parts by mass, the gravure printing suitability may be reduced. There is.

  In addition, although there is no limitation in particular in the kind of heavy calcium carbonate, What has an average particle diameter of about 5 micrometers or less which carried out the dry grinding | pulverization or wet grinding | pulverization of white crystalline limestone can be illustrated, for example.

  In addition, light calcium carbonate can be used instead of the heavy calcium carbonate. Examples of the light calcium carbonate include those having an average particle size of about several μm and those having an average particle size of about 0.02 to 0.1 μm, which are chemically produced by baking limestone, for example. Examples of the shape include a columnar shape, a needle shape, and a spindle shape, and a chestnut shape in which crystal structures having these shapes are aggregated and crystallized. Light calcium carbonate is more preferable because it has high pigment flexibility and can form a smoother pigment coating layer surface.

  Further, for example, kaolin clay can be used other than calcium carbonate such as heavy calcium carbonate and light calcium carbonate. Kaolin clay is preferable because the glossiness and smoothness of the coated paper for gravure printing is easy to improve and the gravure printing suitability is better. On the other hand, since whiteness is lower than calcium carbonate, The whiteness of the coated paper for printing may be reduced. Therefore, the blending amount of kaolin clay is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less with respect to 100 parts by mass of the total pigment.

  In addition, high whiteness clay that can be imparted with high whiteness and high whiteness that can be imparted with high whiteness obtained by firing or sufficiently removing impurities in the production process Although fine clay can be blended, in the present invention, the intended high whiteness gravure coated coated paper can be obtained without using these high whiteness clay and high whiteness fine clay. it can. When these are used, it is particularly preferable that the blending amount is 50 parts by mass or less with respect to 100 parts by mass of the total pigment, as in the case of the kaolin clay.

  There is no particular limitation on the type of adhesive compounded with the pigment, but in order to form a more flexible pigment coating layer, latex having high stability, latex containing a butadiene component as a monomer component is used. It can be particularly preferably used. Among them, in the present invention, it is preferable to use a latex containing a butadiene component in an amount of 50 to 80% by mass, further 55 to 75% by mass, particularly 60 to 70% by mass, based on the total amount of monomer components. When the butadiene component is less than 50% by mass, the flexibility of the pigment coating layer may be lowered, and the gravure printing suitability may be lowered. On the other hand, when the butadiene component exceeds 80% by mass, for example, when performing a flattening process with a super calender, the pigment coating layer may be taken on a metal roll and roll contamination may easily occur.

  When flexibility is required for the paper as in the present invention, in addition to the specific softening agent described later, the latex in which the butadiene component is contained in the specific range, particularly the butadiene component is in the specific range. The smoothness and flexibility of the pigment coating layer can be further improved by using, as an adhesive, a styrene-butadiene copolymer latex having a content of. Therefore, even if the content of mechanical pulp or kaolin clay is at least sufficient gravure printing suitability, the intended coated paper for gravure printing can be obtained.

  In addition to the styrene-butadiene copolymer latex, an adhesive that can be generally used for papermaking can be used in combination with the present invention. Examples of such adhesives include proteins such as casein and soybean protein; conjugated diene latexes such as methyl methacrylate-butadiene copolymer latex and styrene-methyl methacrylate-butadiene copolymer latex, acrylic acid esters and / or Acrylic latex such as polymer latex or copolymer latex of methacrylic acid ester, vinyl latex such as ethylene-vinyl acetate polymer latex, or a monomer containing functional groups such as carboxyl groups of these various copolymer latexes Latexes such as alkali partially soluble or non-soluble latex modified with 1; synthetic resin adhesives such as polyvinyl alcohol, olefin-maleic anhydride resin, melamine resin, urea resin, urethane resin; oxidized starch, positive starch Esthetic Starches such as modified starch and dextrin; examples of adhesives usually used in coated paper such as cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, and one or more of these are appropriately selected and used in combination can do.

  The blending ratio of the pigment and the adhesive in the pigment coating agent is preferably adjusted so that the adhesive is 3 parts by mass or more, more preferably 4 parts by mass or more, with respect to 100 parts by mass of the total pigment. It is preferable to adjust so that it may become 10 parts by mass or less. When the blending amount of the adhesive is less than 3 parts by mass, for example, when performing a flattening process with a super calender, the pigment coating layer may be taken on a metal roll and roll contamination may easily occur. On the other hand, when the blending amount of the adhesive exceeds 12 parts by mass, the adhesive forms a film in the pigment coating layer, making it difficult to transfer the ink, which may reduce the gravure printing suitability.

  One of the great features of the coated paper for gravure printing according to the present embodiment is that the pigment coating layer contains a softener made of an aliphatic polyether compound in addition to the pigment and the adhesive. It is.

  The aliphatic polyether compound has a performance as a surfactant, can improve the wettability of the pigment coating agent, and smoothes the pigment coating layer formed on the base paper There is an effect to.

  In general, in coated paper, smoothing (leveling) of the coated surface occurs immediately after coating of the coating agent and through a drying facility such as an infrared dryer or a scuff dryer. The softening agent comprising an aliphatic polyether compound can lower the surface tension of the pigment coating layer during this period and improve the flexibility of the pigment coating layer, and the smoothness of the resulting coated paper for gravure printing It is considered that the gravure printing aptitude is improved. Such an effect cannot be obtained with compounds other than aliphatic polyether compounds such as polyvinyl alcohol (aliphatic polyol) and carboxymethyl cellulose (alicyclic polyether polyol). Therefore, for the first time by including a softening agent composed of an aliphatic polyether compound in the pigment coating layer, even when no mechanical pulp is blended in the base paper, 50 mass% or more of calcium carbonate is blended as a pigment. Even in such a case, the regular reflection smoothness on the surface of the pigment coating layer can be improved to a gravure printing suitability of 75% or more, and a coated paper for gravure printing with high whiteness can be obtained.

  Representative examples of the aliphatic polyether compound include aliphatic polyether polyol compounds such as aliphatic polyether polyols and alkylene oxide adducts of aliphatic polyether polyols. Alkylene oxide adducts are particularly preferred because they have a high softening effect on the pigment coating layer and can further improve gravure printing suitability.

  In order to obtain a coated paper for gravure printing that is further excellent in gravure printing suitability, the content of the aliphatic polyether compound is 0.1 parts by mass or more, further 0.2. The amount is preferably at least part by mass, more preferably at most 3.0 parts by mass, even more preferably at most 1.0 part by mass. If the content of the aliphatic polyether compound is less than 0.1 parts by mass, a predetermined smoothing effect cannot be obtained, and the gravure printability may not be sufficiently improved. On the other hand, if the content of the aliphatic polyether compound exceeds 3.0 parts by mass, the ink absorbability is lowered by blocking the pores of the pigment coating layer, and the gravure printing suitability may not be sufficiently improved. .

  Further, by combining the softening agent comprising the aliphatic polyether compound with a styrene-butadiene copolymer latex containing 50 to 80% by mass of the butadiene component as an adhesive, the pigment coating layer can It can be softened and smoothed. Therefore, sufficient gravure printing suitability can be obtained even when mechanical pulp is not blended in the base paper and calcium carbonate is blended in an amount of 50% by mass or more as a pigment, for example, when whiteness is improved to 85% or more. Can do.

  Furthermore, in the pigment coating layer, a fluorescent dye generally used for papermaking can be contained for the purpose of further improving the whiteness.

  There are no particular limitations on the type of fluorescent dye, and those generally used for papermaking can be used. Examples of the fluorescent dye include fluorescent dyes such as aminostilbene, imidazole, oxazole, triazole, coumarin, naphthalimide, and pyrazoline, and one or more of these are appropriately selected. Can be used. Among these, aminostilbene fluorescent dyes are preferable, and aminostilbene sulfonic acid derivatives are particularly preferable. Furthermore, hexatypes in which six sulfonic acid groups are coordinated in one molecule and tetratype aminostilbene sulfonic acid derivatives in which four sulfonic acid groups are coordinated in one molecule have a high fluorescent whitening effect. preferable. In particular, hexa-type aminostilbene sulfonic acid derivatives are preferred because they have a higher fluorescent whitening effect.

  Since the aliphatic polyether compound also has an effect as a fixing agent for a fluorescent dye, it is possible to obtain a coated paper for gravure printing with higher whiteness by including the fluorescent dye in the pigment coating layer. it can.

  Generally, when a fluorescent dye is blended, color reversion called fading occurs, and the whiteness of the coated paper tends to decrease. In order to obtain coated paper with high whiteness, this fading must be minimized, and a fixing agent that can sufficiently hold the fluorescent dye is required. Conventional fixing agents for fluorescent dyes have a low fluorescent dye retention performance, so that they tend to fade and cannot provide coated paper with high whiteness. On the other hand, aliphatic polyether compounds have higher fluorescent dye retention performance and fading than conventional general fixing agents such as polyvinyl alcohol (aliphatic polyol) and carboxymethylcellulose (alicyclic polyether polyol). Hard to occur. The reason why the aliphatic polyether compound exhibits high retention performance is that the aliphatic polyether compound has the performance as a surfactant, and therefore the hydrophilic group and hydrophobic group of the fluorescent dye. This is considered to be because both can be sufficiently fixed.

  In this way, in addition to the aliphatic polyether compound, the fluorescent dye is included in the pigment coating layer, so that high whiteness due to the fluorescent whitening effect, gravure printing suitability due to the smoothing effect, and further fading resistance can be achieved. Since the improvement effect is obtained, a coated paper for gravure printing having whiteness of 90% or higher and higher whiteness can be obtained, for example.

  The content of the fluorescent dye in the pigment coating layer is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more with respect to 100 parts by mass of the total pigment, and 1.0 part by mass or less. Furthermore, it is preferable that it is 0.6 mass part or less. If the content of the fluorescent dye is less than 0.1 parts by mass, the whiteness improvement effect may not be sufficiently obtained. Conversely, when the content of the fluorescent dye exceeds 1.0 part by mass, not only the whiteness improvement effect reaches its peak, but the color of the fluorescent dye itself is reflected on the coated paper for gravure printing, and the whiteness is rather reduced. May fall.

  The pigment coating agent used in this embodiment contains a pigment and an adhesive as main components, and includes a softening agent composed of an aliphatic polyether compound, and preferably a fluorescent dye. Various auxiliary agents generally used in papermaking applications, such as an agent, a release agent, a colorant, and a water retention agent, can be appropriately blended within a range that does not impair the object of the present invention.

  The method for preparing the pigment coating agent is not particularly limited, and the blending ratio of the pigment, the adhesive and the softening agent, and the fluorescent dye and various auxiliary agents as necessary is appropriately adjusted, and uniform at an appropriate temperature. What is necessary is just to stir and mix so that it may become a composition. The solid content concentration of the pigment coating agent is not particularly limited, and is preferably adjusted to, for example, about 60 to 75% by mass according to the coating apparatus and the coating amount.

  Next, the pigment coating agent is coated on at least one surface of the base paper, preferably on the primer coating layer provided on the base paper, and at least one pigment coating layer is formed on the base paper. Form.

  The pigment coating agent is preferably applied to the base paper in a coater part between the dryer parts, which is performed in a plurality of stages, usually two stages of a pre-dryer part and an after dryer part. In the coater part, for example, on-machine coater or off-machine coater equipped with coating equipment such as blade coater, air knife coater, transfer roll coater, rod metering size press coater, curtain coater, etc. are divided into one layer or multiple layers on the base paper The pigment coating agent is applied. Among these, it is preferable to use a blade coater from the viewpoint that high smoothness of the surface of the pigment coating layer is ensured. In addition, as a drying method in the dryer part, for example, various heating drying methods such as hot air heating, gas heater heating, infrared heater heating and the like can be appropriately employed.

The coating amount of the pigment coating agent is preferably 5 g / m ² or more, more preferably 7 g / m ² or more, more preferably 9 g / m ² or more, more preferably 20 g / m ² per side of the base paper in terms of solid content. It is preferably ² or less, more preferably 18 g / m ² or less, and particularly preferably 15 g / m ² or less. When the coating amount is less than 5 g / m ² per side, the pigment coating layer is not sufficiently flattened, and it is difficult to obtain good gravure printing suitability, and the pigment-derived whiteness is a coating for gravure printing. It is not reflected on the paper, and the whiteness may not be improved sufficiently. On the other hand, when the coating amount exceeds 20 g / m ² per side, for example, when performing a flattening process with a super calender, the pigment coating layer is peeled off and taken on the roll, and roll contamination troubles are likely to occur. Productivity and quality may be reduced.

  In addition, as described above, at least one specific pigment coating layer containing a softening agent composed mainly of a pigment and an adhesive and composed of an aliphatic polyether compound is formed on the base paper. When two or more pigment coating layers are provided on paper, the two or more specific pigment coating layers may be provided, and only the outermost layer (top coat) is the specific pigment coating layer. The pigment coating layer below the surface layer may be another pigment coating layer. However, in order to obtain a coated paper for gravure printing with high whiteness and excellent gravure printing suitability, both the outermost layer and the pigment coating layer under the outermost layer should contain an aliphatic polyether compound as a softening agent. Is preferred.

  The pigment coating layer formed as described above is flattened by a flattening facility that combines an elastic roll and a metal roll, such as a super calender and a soft calender, for the purpose of further improving gloss, smoothness, and gravure printing suitability. Can be applied. Unlike conventional machine calenders, such flattening equipment treats the surface of the paper with a wide surface at a high temperature so that it can be flattened without excessively increasing the density of the base paper or the coating layer. For example, a suitable printing surface can be formed in offset printing, electrophotographic printing, and the like. Among them, a super calender that combines metal rolls and elastic rolls of a predetermined temperature in a plurality of stages in the vertical direction and pressurizes in the vertical direction is heated to about 70 ° C. using hot water. Since it is more economical than the above, it is particularly preferably used.

  The linear pressure, temperature, and speed of the flattening treatment by the calendar are not particularly limited, but the smoothness of the pigment coating layer after the treatment is sufficiently improved, and the final strength of the coated paper for gravure printing is increased. In order not to become excessive, it is preferable to adjust, for example, a super calender so that the linear pressure is 95 to 350 kN / m, the metal roll temperature is 50 to 90 ° C., and the speed is 500 to 1000 m / min.

The grammage of the coated paper for gravure printing thus obtained is measured in accordance with the method described in JIS P 8124 “Basis Weight Measurement Method” from the viewpoints of gravure printing suitability, ensuring paper strength, and ensuring opacity. Thus, it is preferably 50 g / m ² or more, more preferably 70 g / m ² or more, and 200 g / m ² or less, further preferably 170 g / m ² or less. When the basis weight is less than 50 g / m ² , for example, it may be difficult to ensure the paper quality strength while ensuring the gravure printability. On the other hand, when the basis weight exceeds 200 g / m ² , it may be difficult to achieve weight reduction and resource saving that have been required in recent years.

  The whiteness of the coated paper for gravure printing varies slightly depending on the application, but from the viewpoint of obtaining a sufficiently satisfactory aesthetic appearance as a printed matter or recorded matter, a color analyzer (model number: Color i5, manufactured by Macbeth Gretag) It is preferable that the whiteness of the pigment coating layer surface measured by the above is 85% or more, more preferably 88% or more, and particularly preferably 90% or more. The whiteness is preferably 100% or less so that the contrast between the image area and the non-image area becomes too high after printing and the appearance of the printed matter is not deteriorated.

  The gravure printing suitability of the coated paper for gravure printing can be evaluated by two methods of regular reflection smoothness and halftone dot (speckle).

  The regular reflection smoothness is an index of smoothness calculated from the contact ratio between the coated paper for gravure printing and the glass surface, and it is known that the higher the numerical value, the higher the smoothness and the better the gravure printing suitability. The regular reflection smoothness on the surface of the pigment coating layer measured by a total reflection type printing smoothness meter (Microtopograph, manufactured by Toyo Seiki Seisakusho Co., Ltd.) suitable for gravure printing is 75% or more, preferably 80%. More preferably, it is 85% or more. When the regular reflection smoothness is less than 75%, halftone dots (speckle) occur frequently, and the appearance of the printed matter is deteriorated.

The halftone dot (speckle) can be evaluated by the number of halftone dots generated by performing gravure printing on a coated paper for gravure printing. In gravure printing, the smaller the number of halftone dots, the better. The number of halftone dots suitable for gravure printing is preferably 80 or less, more preferably 50 or less, and most preferably 20 or less per 1 cm ^2. . If the number of halftone dots exceeds 80 per 1 cm ² , the appearance as a high-quality printed product may be deteriorated.

  As described above, the coated paper for gravure printing of the present invention achieves high whiteness while maintaining excellent gravure printing suitability, and is resistant to the problems with conventional high white coated paper. Since it is excellent in fading and excellent in appearance, it can be suitably used for high-grade commercial prints such as high-quality art prints, catalogs, pamphlets and calendars.

  Next, the coated paper for gravure printing of the present invention will be described in more detail based on the following examples, but the present invention is not limited to only these examples.

Preparation Examples 1-26 and Comparative Preparation Examples 1-2 (Preparation of coating agent)
Purified water was added to the sizing agent shown below and stirred at room temperature to obtain a primer coating agent that was a uniform sizing agent aqueous solution having a solid content concentration of 7.0% by mass.

  Next, the pigment and the adhesive, and the softener and fluorescent dye in the types and proportions shown in Tables 1 and 2 were mixed and stirred at room temperature to obtain a pigment coating agent having a solid content concentration of 60 to 75% by mass. . The pigments, adhesives, softeners and fluorescent dyes used are as follows. In addition, the compounding quantity of the softening agent and fluorescent dye which are shown to Tables 1-2 is a value with respect to 100 mass parts of pigment whole quantity. Although not described in Tables 1 and 2, the pigment is 50 parts by weight of kaolin clay and 50 parts by weight of heavy calcium carbonate, and 6 parts by weight of an adhesive is blended with 100 parts by weight of the pigment. Each pigment coating agent was prepared.

[1] Undercoat coating agent / size agent (Part No .: AK400, manufactured by Seiko PMC Co., Ltd.)

[2] Pigment coating agent (1) Pigment / Kaolin clay (Product number: CenturyHC, manufactured by PPSA)
・ Heavy calcium carbonate (Product number: Hydro curve 90K, manufactured by Omiya Korea)

(2) Adhesive / styrene-butadiene copolymer latex (Part No .: PA3024, manufactured by Nippon A & L Co., Ltd.)
Using the latex, the content of the butadiene component in the total amount of the monomer components was changed as shown in Tables 1 and 2 to obtain the target latex. Tables 1 and 2 also show the contents of methyl methacrylate and acrylonitrile.

(3) Softener / softener A: Alkylene oxide adduct of aliphatic polyether polyol (Product name: Optiact I-10, manufactured by San Nopco)
Softener B: Aliphatic polyether polyol (Product name: Polyethylene glycol # 200, manufactured by Lion Corporation)
Softener C: aliphatic polyol (polyvinyl alcohol)
(Product name: Gohsenol NL-05, manufactured by Nippon Synthetic Chemical Co., Ltd.)
Softener D: alicyclic polyether polyol (carboxymethyl cellulose)
(Product name: FINFIX300, CPkelco)

(4) Fluorescent dye, stilbene: Hexatype aminostilbene sulfonic acid derivative (product number: Kayahol EXN, manufactured by Nippon Kayaku Co., Ltd.)
・ Oxazole: Oxazole fluorescent dye (Product number: Keicol SN, manufactured by Nippon Soda Co., Ltd.)

Examples 1-26 and Comparative Examples 1-2 (production of coated paper for gravure printing)
LBKP, NBKP, and BPGW (bleached pressure stone grand pulp) are blended in the mass proportions shown in Table 3 as raw material pulp, and each 100% by mass (absolutely dry amount) of this pulp is solid content, and the internal size Agent (part number: AK-720H, manufactured by Harima Chemicals Co., Ltd.) 0.02 parts by mass, cationized starch (part number: amylofax T-2600, manufactured by Abebe Japan Co., Ltd.) 1.0 parts by mass, and yield improvement 0.02 part by mass of an agent (product number: NP442, manufactured by Nissan Eka Chemicals Co., Ltd.) was added to obtain a pulp slurry.

  Next, using a papermaking system that includes a wire part, press part, pre-dryer part, undercoater part, after-dryer part, and reel part, apply a pigment coating agent with a coating machine that includes a top coater part, and a calendar part. A flattening process was performed using a super calendar containing, and the product was finished in a winder part.

First, the pulp slurry was made with a wire part, and then subjected to a press part and a predryer part to produce a base paper having a basis weight of 49 to 51 g / m ² . Next, in the undercoater part, undercoat is applied to both sides of the base paper so that the solid content is 1.0 g / m ² per side and dried in the after dryer part. A construction layer was formed.

  Moreover, it was 83 to 86% when the whiteness of the base paper was measured by the method similar to the whiteness of the coating paper for gravure printing mentioned later.

Thereafter, the top coater part is coated with a pigment coating agent on the base coating layer on both sides of the base paper so that the solid content is 14 g / m ² per side. A layer was formed, and a coated paper having a basis weight of 79 to 81 g / m ² was obtained.

  Next, in the calendar part, the coated paper is flattened at a linear pressure of 300 kN / m, a metal roll temperature of 60 ° C., and a speed of 600 m / min. Obtained paper.

  The wire part made paper using a hybrid former, the undercoater part adopted a film transfer system using a rod metering size press coater, and the top coater part used a blade coater. In the calendar part, a super calendar was used.

  About the obtained coated paper for gravure printing, each physical property and characteristic were investigated with the following method. The results are shown in Table 4.

(1) Whiteness The whiteness of the pigment coating layer surface was measured with a color analyzer (model number: color i5, manufactured by Macbeth Gretag). The measurement conditions are UVIN (including ultraviolet light), SCI (including reflected light), C light source, and viewing angle 2 °.

(2) Fading resistance Using an irradiometer (model number: FAL-3, manufactured by Suga Test Instruments Co., Ltd.), xenon light having a wavelength of 340 nm was irradiated at a temperature of 63 ° C. and an irradiation intensity of 0.4 W / m ² for 24 hours. . Before and after irradiation with xenon light, L value, a value, and b value are measured, and for each of these L value, a value, and b value, the difference between values before and after irradiation, ΔL, Δa, and Δb are calculated. The ΔE value was determined and used as an index for fading resistance.
ΔE = (ΔL ² + Δa ² + Δb ² ) ^1/2
In addition, it shows that it is excellent in fading resistance, so that this (DELTA) E value becomes small.

(3) Gravure printability (a) Regular reflection smoothness Measured using a total reflection type print smoothness meter (Microtopograph, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The measured value 10 milliseconds after the start of pressurization at a pressurization pressure of 20 kgf / cm ^{2 was taken} as the regular reflection smoothness of the pigment coating layer surface.

(B) Halftone dot (speckle)
Using a printing station type gravure printing aptitude tester (manufactured by Kumagai Riki Kogyo Co., Ltd.), there is no halftone dot in the 20% halftone part of each side of the coated paper for gravure printing (F side and W side). The state was measured as the number of missing parts (number) per 1 cm ² .

(4) Roll stain The degree of stain was evaluated based on the following evaluation criteria for the dropped pigment coating layer attached to the metal roll of the super calender.
(Evaluation criteria)
5: The pigment coating layer did not adhere and there was no roll dirt.
4: The pigment coating layer was slightly adhered and some roll dirt was observed, but there was no problem in operation.
3: Although the pigment coating layer was adhered and some roll dirt was observed, operation was possible with simple roll cleaning, and workability was hardly deteriorated.
2: The pigment coating layer adhered and roll dirt was recognized, and roll cleaning was required, and workability was reduced.
1: A large amount of pigment coating layer adheres and roll dirt is remarkable, and sufficient roll cleaning is necessary.
Workability was greatly reduced.
Of the evaluation criteria, cases 5 to 3 are determined to be actually usable.

  Since all the coated papers for gravure printing of Examples 1 to 26 contain an aliphatic polyether-based compound as a softening agent in the pigment coating layer, gravure printing has a regular reflection smoothness of 75% or more. Excellent suitability, high whiteness, excellent fade resistance, no roll stain, good workability, good appearance for high-grade commercial prints It turns out that it is a coated paper for gravure printing.

  On the other hand, the coated paper for gravure printing of Comparative Examples 1 and 2 uses a conventional aliphatic polyol or alicyclic polyether polyol as a softening agent, not an aliphatic polyether compound. It can be seen that the whiteness is low, the color fading resistance and the gravure printing suitability are inferior, and it is not suitable as a high-grade commercial printed matter.

  The coated paper for gravure printing of the present invention can be suitably used for high-grade commercial prints such as high-quality art prints, catalogs, pamphlets and calendars.

Claims (5)

A coated paper for gravure printing having a base paper and at least one pigment coating layer mainly composed of a pigment and an adhesive on the base paper,
The pigment coating layer contains a softening agent composed of an aliphatic polyether compound,
A coated paper for gravure printing, wherein the regular reflection smoothness of the pigment coating layer surface measured by a total reflection type printing smoothness meter is 75% or more.   The coated paper for gravure printing according to claim 1, wherein the adhesive is a latex containing a butadiene component in an amount of 50 to 80% by mass based on the total amount of monomer components.   The coated paper for gravure printing according to claim 1 or 2, wherein the aliphatic polyether compound is an aliphatic polyether polyol compound.   The content of mechanical pulp in the base paper is 10% by mass or less of the total amount of pulp, and the whiteness of the surface of the pigment coating layer measured by a color analyzer is 85% or more. The coated paper for gravure printing as described in one.   The amino acid stilbene fluorescent dye is contained in the pigment coating layer, and the whiteness of the pigment coating layer surface measured by a color analyzer is 90% or more, according to any one of claims 1 to 4. Coated paper for gravure printing.