JP4228903B2 - Method for producing coated paper for printing - Google Patents

Description

The present invention relates to a method of manufacturing a coated paper for printing, bulky, yet excellent gloss, a method of manufacturing a coated paper for printing having a high smoothness.

  In recent years, the visualization and colorization of printed materials has progressed, and the demand for higher quality of coated paper for printing has increased. In the printing finish such as white paper quality such as white paper glossiness, smoothness, whiteness, and printing gloss. Although quality such as appearance is regarded as important, it has become more important for merchandise such as touch feeling when turning pages (paper waist), thickness of publications, volume feeling, etc. As a result, there is an increasing demand for more bulky coated paper as well as better blank paper quality and printability.

  In general, a coated paper for printing is produced by applying a coating liquid mainly composed of a pigment and an adhesive on a base paper and drying it, followed by a supercalender treatment. However, since the calendering process is performed at a high nip pressure, the paper layer is crushed and the density becomes high, and the overall bulk is difficult to be obtained, so that only so-called coated paper can be obtained, and printing on such coated paper is possible. However, there is a disadvantage that a feeling of weight does not appear even if applied.

  In order to increase the bulk of the coated paper, it can be achieved by reducing the coating amount of the coating composition. This is because the ratio of the coating layer to the entire coated paper is small. However, reducing the coating layer also reduces the coverage of the base paper by the coating layer, so the printing quality such as blank paper glossiness, smoothness, and printing glossiness is lowered, so the target quality is maintained. However, there is a limit to reducing the coating amount.

  Furthermore, generally, as a method for producing a bulky coated paper, a heat calender treatment (high temperature soft calender) using a high temperature roll for the purpose of imparting surface smoothness while minimizing the decrease in bulk due to the calender treatment. ) Is used (see Patent Documents 1, 2, and 3). However, in order to obtain a light-weight, bulky, and conventional white paper glossy printing paper as required in recent years, the processing temperature of the thermal calendar should be as high as possible and a lower linear pressure. Must be handled with. Therefore, according to the unevenness of the paper surface, there is a tendency that the problem that not only the paper thickness but also the gloss profile deteriorates becomes more prominent. Further, since the chilled roll is used at a high temperature, the life of the elastic roll tends to be further shortened. In recent years, the development of heat-resistant resins has progressed, but basically, increasing the heat resistance tends to increase the hardness of the resin layer, which is bulky and has excellent gloss and smoothness. Coated paper has not been obtained.

Japanese Patent No. 3371422 JP 09-1119090 A Japanese Patent No. 3448863

  There is a shoe calendar (long nip calendar) as the latest calendar format. As for the surface treatment of paper after papermaking, compared with chilled nip calender, soft nip calender and super calender, the shoe calender can maintain bulk and can obtain excellent surface smoothness. (See Patent Documents 4 and 5). In addition, it is described that a shoe calendar process is performed after coating and drying a coating liquid (see Patent Documents 6 and 7), but these are mainly used for cardboard and paperboard, and maintain bulk. It focuses on the uniformity of surface quality. Moreover, it is described that the shoe calendar is more bulky and has better uniformity in paper thickness and white paper gloss than the soft calendar (see Non-Patent Document 1). Thus, the shoe calendar process is beginning to be recognized as a calendar process for base paper, cardboard, and paperboard because a bulky and uniform profile can be obtained. However, the nip pressure of the shoe calender is not necessarily sufficient for producing a high gloss, so it is not currently used as a means for obtaining a coated paper for printing having an excellent gloss.

Japanese Patent No. 2800908 JP 2000-314941 A Special table 2002-519525 gazette Special Table 2002-544409 Paper magazine, 53, (12), 71-77 (1999)

An object of the present invention is to provide a method for producing a coated paper for printing that is bulky, has high white paper gloss, and high smoothness.

The present invention provides an outermost coating layer in a method for producing a coated paper for printing having at least one layer of a coating liquid mainly composed of a pigment and an adhesive on at least one side of a base paper and having a dried coating layer. The nip width formed by the metal roll and the sleeve comprising at least one selected from plastic pigment or satin white, and comprising a metal roll and a tubular sleeve made of an elastic synthetic resin. Is processed with a shoe calendar having a diameter of 50 to 300 mm.
The white paper gloss of the coated paper for printing is 65% or more in terms of gloss according to JIS P 8142 (75 ° gloss), the tension is 1.05 g / cm ³ or less, and the PPS smoothness is 0.2 to 1.3 μm. It is.
The basis weight of the coated paper for printing is 60 to 500 g / m ² .

The coated paper for printing according to the present invention has excellent white paper gloss and excellent smoothness while having a low tension (bulky) of 1.05 g / cm ³ or less.

  In the printing coated paper of the present invention, at least one coating layer is provided on at least one side of the base paper, and at least one selected from plastic pigment or satin white is provided in the outermost coating layer as the outermost coating layer. It is necessary to make it contain 2-30 mass% of a pigment, and it is more preferable to make it contain in 5-15 mass%. Incidentally, if it is less than 2% by mass, a sufficient gloss development effect cannot be obtained, and if it exceeds 30% by mass, the effect becomes saturated, and there is a problem in cost and fluidity of the coating liquid.

  The manufacturing method, form, composition, etc. of the plastic pigment to be contained in the outermost coating layer are not particularly limited, but the average particle diameter is 0.1 to 1.0 μm, and the hollow type is heated and heated. Deformation by plasticization is easy and easy to arrange when subjected to pressure, and the inclusion of this is preferable because the glossiness of blank paper can be further improved.

  Further, by containing satin white in the outermost coating layer, not only the white paper glossiness improving effect but also the smoothness can be further improved. The average particle diameter of satin white is preferably in the range of 0.1 to 1.3 μm, and more preferably in the range of 0.3 to 1.0 μm, in the X-ray transmission type particle size distribution measurement.

  In the present invention, from the viewpoint of enhancing smoothness and gloss, it is preferable to provide a base coat layer that is coated with a coating solution and dried on the base paper. By adding satin white in the base coat layer, white paper Since gloss and smoothness increase, it is more preferable. In addition, it is more preferable that satin white having an average particle size of 0.1 to 1.3 μm in X-ray transmission type particle size distribution measurement is contained in an amount of 2 to 30% by mass relative to the total pigment.

  As pigments contained in the coating layer (undercoat coating layer to outermost coating layer) in the present invention, in addition to the plastic pigment and satin white, heavy calcium carbonate, light calcium carbonate, clay, calcined kaolin, structured Kaolin, Delami Kaolin, Talc, Calcium sulfate, Barium sulfate, Aluminum hydroxide, Titanium dioxide, Zinc oxide, Alumina, Magnesium carbonate, Magnesium oxide, Silica, Alumina magnesium silicate, Calcium silicate, Bentonite, Zeolite, Sericite, Sukutite, etc. Inorganic pigments, organic pigments such as binder pigments, and the like can be used as usual pigments used in the field of coated paper, and one or more of these can be appropriately selected and used.

  Among these, as the pigment other than the plastic pigment and satin white contained in the outermost coating layer, it is preferable to use a pigment having an average particle diameter of 1.0 μm or less from the viewpoint of further increasing the glossiness of the blank paper. In particular, fine kaolin is preferable, and the average particle diameter is 0.5 μm or less, more preferably 0.3 μm or less, and is about 50 to 95% by mass of the total pigment.

  The adhesive contained in the coating layer (undercoat coating layer to outermost coating layer) in the present invention is not particularly limited, and is an adhesive used in the ordinary coated paper field, for example, water-soluble adhesive. As an agent, various starches such as oxidized starch, esterified starch, cold water soluble starch, proteins such as casein, soy protein, synthetic protein, cellulose derivatives such as carboxymethylcellulose and methylcellulose, polyvinyl alcohol and modified products thereof, etc. As dispersion-type adhesives, vinyl polymers such as conjugated diene polymer latex such as styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer, acrylic polymer latex, and ethylene-vinyl acetate copolymer. Latex etc. can be used, and if necessary, one of these or Using more than a suitably selected and.

  In the present invention, in order to express the printing strength required as a coated paper for printing, an adhesive is contained in the coating layer, but the adhesive in the coating layer is 5 to 5 times the total pigment. It is especially preferable to set it as 20 mass% and 8-15 mass%. If it is less than 5% by mass, it will be difficult to impart sufficient printing strength to the coated paper. On the other hand, if it exceeds 20% by mass, the smoothness will be poor and economically Further use is less necessary.

  For the coating layer of the present invention, as necessary, blue or purple dyes or colored pigments, fluorescent dyes, thickeners, water retention agents, antioxidants, anti-aging agents, conductive inducers, antifoaming agents Various auxiliary agents such as an ultraviolet absorber, a dispersant, a pH adjuster, a mold release agent, a water-proofing agent, and a water repellent can be appropriately blended.

Further, the total coating amount of the coating layer provided on the base paper in the present invention is the tightness (density) when the coating layer is provided on the base paper in order to express the bulkiness (low density property) of the coated paper. ) Must be set to 1.02 g / cm ³ or less. Since the density of the coating layer is higher than the density of the base paper layer, increasing the coating amount inevitably increases the tightness (density) of the coated paper, thereby reducing the bulkiness of the coated paper. Although it is necessary to reduce the coating amount, if the coating amount is too small, it becomes impossible to cover the base paper, and the coated paper surface becomes worse, so the total coating amount per side is 10 g / m ² or more. There is a need to.

  With respect to the coating method in providing the coating layer in the present invention, various coating apparatuses used in the ordinary coated paper manufacturing field, such as air knife coaters, various blade coaters, gate roll coaters, curtain coaters. Etc. can be used as appropriate.

Further, in the present invention, it is effective to use a base paper having a low tension (density) in order to express the bulkiness of the coated paper, and the base paper has a tension (density) of 0.75 g / cm ³ or less. If there is no problem, it is particularly preferable that the tension (density) of the base paper is 0.7 g / cm ³ or less in order to obtain a desired effect. Incidentally, the base paper used for general coated paper has a tenacity (density) of 0.7 to 0.9 g / cm ³ , but the base paper layer has a tenacity (density) of over 0.75 g / cm ^3. If it is used, it is difficult to obtain a desired low tension (density) when finished into a final product, which is not preferable. It should be noted that, as the base paper rice basis is about 40~470g / cm ^3.

  The base paper in the present invention is not particularly limited except for the tension of the base paper, and a base paper of high quality, medium quality, and deinked pulp blended produced by acidic, neutral to alkaline papermaking can be used as appropriate. In addition, as a method for lowering the tension of the base paper, a pulp having a thick cell membrane is selected and used, a pulp beating is roughened, a hard pulp such as aramid fiber is blended, a bulky filler is used, and a bulking agent There are means such as using surfactant-based chemicals that inhibit interfiber bonding, reducing initial dewatering in the press, reducing the calender pressure of the paper machine, and counting the quality specifications of the final product, By combining one or more of the above-mentioned means, it is possible to adjust the desired base paper tension (density). Furthermore, before providing the undercoat coating layer, it is also possible to perform a size treatment on the base paper using a natural adhesive such as starch or a synthetic adhesive such as polyvinyl alcohol with various size presses and roll coaters. .

  The coated paper thus obtained is subjected to shoe calendar processing in an on-machine or off-machine format.

  The shoe calender used in the present invention has a shoe roll and an endless belt made of an elastic resin, and further has other members as necessary. The endless belt as used in the present invention includes a cylindrical sleeve in addition to the general concept of an endless belt. In addition to the endless belt (sleeve), the shoe roll is provided with a pressure unit and a circulation system for circulating the lubricant.

  The endless belt made of elastic resin can be formed by using, for example, a thick cloth as a support and covering the support with an elastic resin. Examples of the elastic resin include epoxy resins, polyamide resins, polyimide resins, polyimide amide resins, polyurethane resins, butadiene resins, polyester resins, nylon resins, polyether resins, and the like. These resins may be used alone or in combination of two or more.

  The hardness of the endless belt (sleeve) is preferably a shear hardness D of 30 to 80 degrees, more preferably 40 to 70 degrees. If the shear hardness is less than 30 degrees, the endless belt undergoes plastic deformation during use, and the life of the shoe roll may be shortened. Moreover, a coated paper for printing having high surface smoothness and gloss may not be obtained. On the other hand, if the shear hardness exceeds 80 degrees, the hardness of the endless belt may be too high, and the curvature of the shoe roll shape may be difficult to obtain.

  The metal roll corresponding to these shoe rolls is a cylindrical or columnar roll having a smooth surface, and there is no particular limitation on the material and the like as long as it has a heating means inside, and a known metal A roll can be appropriately selected and used. The surface roughness of the metal roll is preferably as smooth as possible. Specifically, the surface roughness Ra specified by JIS B0601-1994 is preferably 0.2 μm or less and 0.15 μm or less.

  The nip width formed by the metal roll and the shoe roll is 30 to 300 mm, and preferably 50 to 200 mm. When the nip width is less than 30 mm, the time required for the coated paper to pass through the nip portion is shortened, the calendar processing effect is reduced, and a desired white paper gloss cannot be obtained. On the other hand, when the nip width exceeds 300 mm, the linear pressure during the calendering process of the coated paper is lowered, and the calendering effect is lowered, which is not preferable.

  The passing speed when passing through the nip portion of the shoe calender is preferably 100 to 2000 m / min, and more preferably 300 to 1500 m / min. When the passing speed is less than 100 m / min, the production efficiency is deteriorated, the passing time through the nip portion becomes long, and the tightness of the finished coated paper becomes too high. On the other hand, when it exceeds 2000 m / min, the time for passing through the nip portion is shortened, so that the calendar processing effect may not be achieved.

  The linear pressure during shoe calender treatment is preferably from 100 to 500 kN / m, more preferably from 200 to 400 kN / m. When it is less than 100 kN / m, the calendering effect is low, and when it exceeds 500 kN / m, the tightness of the finished coated paper becomes too high.

  100-350 degreeC is preferable and, as for the surface temperature of the metal roll in a shoe calendar, 150-250 degreeC is more preferable. When the surface temperature of the metal roll is less than 100 ° C., the coating layer cannot be plasticized appropriately. On the other hand, when the surface temperature is 350 ° C. or more, the so-called burning phenomenon occurs and the whiteness of the coated paper decreases. There are difficulties.

The coated paper obtained by applying and drying the coating solution on the base paper is subjected to shoe calender treatment under the above conditions, so that the glossiness of the white paper is 65% or more in accordance with JIS P 8142 (75 ° glossiness), A coated paper for printing having a tenacity of 1.05 g / cm ³ or less and a PPS smoothness of 0.2 to 1.3 μm can be obtained.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “parts” and “%” in the examples represent “parts by mass” and “mass%”, respectively. Moreover, the particle diameter of the pigment used by the Example and the comparative example was measured with the following method.

-Average particle diameter of pigment Dispersion treatment of pigment in 0.1% solution of sodium pyrophosphate with ultrasonic waves for 5 minutes, X-ray transmission particle size distribution analyzer (model name: Cedigraph 5100, manufactured by Micromeritics) Was measured by the sedimentation method. The average particle size is shown by the particle size at the point where the cumulative mass from the coarse particles corresponds to 50%.

Example 1
・ Preparation of coating solution for outermost coating layer Fine kaolin with a mean particle size of 0.24 μm (trade name: Hydra gloss, Huber: USA) as a pigment, heavy calcium carbonate with a mean particle size of 0.8 μm (Trade name: Hydrocurve 90, manufactured by Bihoku Flour Chemical Co., Ltd.) 10% and hollow plastic pigment having an average particle size of 1.0 μm (trade name: AE851, manufactured by JSR Corporation) 10% in a pigment slurry, 100 parts of pigment On the other hand, oxidized starch (trade name: Oji Ace B, manufactured by Oji Cornstarch Co., Ltd.) 2 parts, styrene-butadiene copolymer latex (trade name: Smartex PA2323, manufactured by Nippon A & L Co., Ltd.) 13 parts (all in terms of solid content) ), And auxiliary agents such as antifoaming agents and dyes were added to finally prepare a coating solution having a solid concentration of 58%.

-Preparation of coated paper for printing The above coating liquid for outermost coating layer is dried per side on high-quality base paper (US basis weight 72.5 g / m ² ) having a tension of 0.73 g / cm ^3. Double-sided coating and drying were performed using a blade coater so that the weight was 16 g / m ² to provide an outermost coating layer. The tension at this time was 1.02 g / cm ³ . The coated paper thus obtained was passed through a two-tack shoe calender with a blanket hardness share D50 °, nip width 50 mm, metal roll temperature 200 ° C., linear pressure 350 kN / m, speed 1000 m / min, A coated paper for printing was obtained by treating both surfaces of the outermost coated layer with a metal roll.

Example 2
In the preparation of the outermost layer coating solution of Example 1, the plastic pigment was changed to Sachin White (trade name: Sachin White BL, manufactured by Shiroishi Kogyo Co., Ltd.) having an average particle size of 0.5 μm, and was the same as Example 1. Thus, a coated paper for printing was obtained.

Example 3
・ Preparation of coating liquid for undercoat coating layer in contact with base paper As a pigment, a pigment slurry composed of 100% heavy calcium carbonate having an average particle diameter of 1.3 μm (trade name: Hydrocurve 60, manufactured by Bihoku Flour Industries Co., Ltd.) , 100 parts of pigment, 4 parts of oxidized starch (trade name: Oji Ace B, supra), 8 parts of styrene-butadiene copolymer latex (trade name: Smartex PA2182-2, manufactured by Nippon A & L Co., Ltd.) Were also added in the form of solid content) and auxiliary agents such as an antifoaming agent and a dye were added to finally prepare a coating solution having a solid content concentration of 60%.

- In the preparation example 2 of the coated paper for printing, a blade the undercoat coating layer for coated liquid on the base paper prior to forming the outermost coating layer as one surface per dry weight is 8 g / m ² Using a coater, double-side coating and drying were performed to provide an undercoat coating layer. Next, the same outermost coating layer coating solution as in Example 2 was coated on both sides using a blade coater and dried so that the dry weight per side was 8 g / m ^2, and the outermost coating was applied. A coated paper for printing was obtained in the same manner as in Example 2 except that a layer was provided.

Example 4
-Preparation of coated paper for printing In Example 1, before forming the outermost coated layer, the same undercoat layer coating liquid as in Example 3 was applied on the base paper to a dry weight of 8 g / m ² per side. Thus, both sides were coated and dried using a blade coater to provide an undercoat coating layer. Next, the same outermost coating solution as in Example 1 was coated on both sides using a blade coater and dried so that the dry weight per side was 8 g / m ^2. A coated paper for printing was obtained in the same manner as in Example 1 except that a layer was provided.

Example 5
In the production of the coated paper of Example 4, it was carried out except that a coated paper was produced using a high-quality base paper having a tenacity of 0.67 g / cm ³ (US basis weight 70.0 g / m ² ) as the base paper. A coated paper was prepared in the same manner as in Example 4. The tension at this time was 0.95 g / cm ³ . The obtained coated paper was passed through a shoe calendar at a metal roll temperature of 250 ° C., a linear pressure of 350 kN / m, and a speed of 500 m / min to obtain a coated paper for printing.

Example 6
In the production of the coated paper for printing of Example 5, the coating for printing was performed in the same manner as in Example 5 except that the paper was passed through a shoe calendar at a metal roll temperature of 150 ° C., a linear pressure of 300 kN / m, and a speed of 1000 m / min. I got paper.

Example 7
In the coating solution for the undercoat coating layer of Example 4, 90% of heavy calcium carbonate having an average particle size of 1.3 μm (trade name: Hydrocurve 60, manufactured by Bihoku Flour & Chemical Co., Ltd.) and an average particle size are used as pigments. A coated paper for printing was obtained in the same manner as in Example 4 except that 1.0% of satin white (trade name: Sachin White B, manufactured by Shiroishi Kogyo Co., Ltd.) was changed to 10%.

Example 8
In the coating solution for the outermost coating layer of Example 3, 5% of hollow plastic pigment (trade name: AE851, manufactured by JSR) with an average particle size of 1.0 μm was added, and satin with an average particle size of 0.5 μm. A coated paper for printing was obtained in the same manner as in Example 3 except that white (trade name: Sachin White BL, manufactured by Shiroishi Kogyo Co., Ltd.) was changed to 5%.

Comparative Example 1
In the coating solution for the outermost coating layer of Example 4, the plastic pigment was changed to fine kaolin (trade name: Hydra Gloss, Huber: USA) having an average particle size of 0.24 μm. Thus, a coated paper for printing was obtained.

Comparative Example 2
In the production of the coated paper for printing of Example 4, except that the paper was passed through a super calender (arranged of chilled rolls and cotton rolls) at a metal roll surface temperature of 70 ° C., a linear pressure of 200 kN / m, and a speed of 1200 m / min. In the same manner as in Example 4, a coated paper for printing was obtained.

Comparative Example 3
In the production of the coated paper for printing of Example 4, except that the metal roll surface temperature was room temperature, the linear pressure was self-weight, and the paper was passed through a super calender (arrangement of chilled roll and cotton roll) at a speed of 1200 m / min. In the same manner as in Example 4, a coated paper for printing was obtained.

Comparative Example 4
Example 4 except that the coated paper for printing of Example 4 was passed through a soft calender at an elastic roll hardness share D91 °, a metal roll surface temperature of 200 ° C., a linear pressure of 100 kN / m, and a speed of 1000 m / min. In the same manner, a coated paper for printing was obtained.

Comparative Example 5
Example 4 except that the coated paper for printing of Example 4 was passed through a soft calender at an elastic roll hardness share D91 °, a metal roll surface temperature of 150 ° C., a linear pressure of 80 kN / m, and a speed of 1000 m / min. In the same manner, a coated paper for printing was obtained.

  The coated papers for printing of Examples 1 to 8 and Comparative Examples 1 to 5 thus obtained were evaluated as follows, and the obtained results are summarized in Table 1. The measurement and evaluation of the coated paper for printing in the present invention were performed in an environment of 23 ° C. and 50 RH% unless otherwise specified.

-White paper gloss According to JIS P 8142, both sides were measured using a gloss meter (model: GM-26D type, manufactured by Murakami Color Research Laboratory Co., Ltd.), and the average was obtained.

-PPS smoothness Using a Parker Print Surf (PPS) surface smoothness tester (model: MODEL M-569, manufactured by MESSMER BUCHEL / UK), backing disk: soft rubber, measurement of smoothness 5 times at 1 MPa. And the average was obtained.

Claims (3)

In a method for producing a coated paper for printing having at least one layer of a coating liquid mainly composed of a pigment and an adhesive on at least one side of a base paper, and having a dried coating layer, the pigment in the outermost coating layer 2 to 30% by mass is at least one selected from plastic pigment or satin white, and includes a metal roll and a tubular sleeve made of an elastic synthetic resin, and a nip width formed by the metal roll and the sleeve is 50 to 300 mm. A method for producing a coated paper for printing, which has been treated with a shoe calender. The white paper gloss of the coated paper for printing is 65% or more in terms of gloss according to JIS P 8142 (75 ° gloss), the tension is 1.05 g / cm ³ or less, and the PPS smoothness is 0.2 to 1.3 μm. The method for producing a coated paper for printing according to claim 1. Method for producing a coated paper for printing according to claim 1 or 2 basis weight of the coated paper for printing is from 60 to 500 g / m ^2.