WO2021024917A1 - Coated paper and method for producing same - Google Patents
Coated paper and method for producing same Download PDFInfo
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- WO2021024917A1 WO2021024917A1 PCT/JP2020/029304 JP2020029304W WO2021024917A1 WO 2021024917 A1 WO2021024917 A1 WO 2021024917A1 JP 2020029304 W JP2020029304 W JP 2020029304W WO 2021024917 A1 WO2021024917 A1 WO 2021024917A1
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- Prior art keywords
- dextrin
- paper
- present
- coated paper
- kda
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Classifications
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H19/00—Coated paper; Coating material
- D21H19/36—Coatings with pigments
- D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
- D21H19/54—Starch
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H19/00—Coated paper; Coating material
- D21H19/36—Coatings with pigments
- D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
Definitions
- the present invention relates to coated paper and a method for producing coated paper.
- the present invention relates to a coated paper containing dextrin as an adhesive (binder) for a pigment coating layer.
- a coating layer mainly composed of a pigment and an adhesive for binding the pigment is formed in order to improve printability.
- an adhesive it is mainly petroleum-based from the viewpoints of good paint fluidity, good coating suitability in coating equipment, and easy imparting print surface strength as coated paper quality. Adhesives derived from synthetic materials are used.
- the paint concentration is low and the water retention of the paint is lowered, so that the paint permeates into the base paper greatly, and the glossiness of the blank paper is lowered and the surface strength is lowered. Quality deterioration is inevitable.
- Patent Document 2 proposes a technique of using a starch-based polymer having a low viscosity after a lapse of a certain period of time from the start of steaming as an adhesive when an aqueous slurry containing a starch-based polymer is steamed. Further, Patent Document 3 proposes to improve the water retention property of the coating liquid by using a plurality of dextrins having different average molecular weights of 50 kDa or more in combination.
- Blanket pyring is the accumulation of paper dust and ink on the periphery of the image area on the blanket and causing it to rise. Further, in the technique described in Patent Document 3, the glossiness of the coated paper tends to decrease.
- Increasing the concentration of the coating liquid contributes to the improvement of productivity by reducing the drying load because the water content is reduced, and the reduction of the penetration of the coating liquid into the base paper to improve the surface strength.
- concentration of the coating liquid is high, the viscosity increases and the operability and coating suitability deteriorate. Therefore, it is recommended to dilute the coating liquid to the extent that it does not adversely affect the drying load and surface strength. It is the actual situation.
- the subject of the present invention is to improve the blank paper glossiness and print glossiness of the coated paper without increasing the paint viscosity so much even if it is highly blended in the paint, and to obtain a blanket at the time of offset printing.
- the purpose is to search for a starch-based adhesive that can suppress the piring of paper, and to develop a technology for producing high-quality coated paper with high operability.
- the present invention includes, but is not limited to, the following inventions.
- a coated paper having a pigment coating layer containing a pigment and an adhesive on a base paper, wherein the adhesive contains a first dextrin and a second dextrin, and the first dextrin.
- the coated paper having a weight average molecular weight (M1) and a weight average molecular weight (M2) of the second dextrin of less than 500 kDa and M1-M2 of 60 kDa or less.
- M1 and M2 weight average molecular weight of the second dextrin of less than 500 kDa and M1-M2 of 60 kDa or less.
- a method for producing coated paper which comprises a step of adjusting a coating liquid containing a pigment and an adhesive and a step of applying the coating liquid to a base paper, wherein the adhesive is the first.
- It contains 1 dextrin and 2nd dextrin, and the weight average molecular weight (M1) of the 1st dextrin and the weight average molecular weight (M2) of the 2nd dextrin are both less than 500 kDa, and M1-M2 is 60 kDa or less.
- the fluidity of the coating liquid is good, and the coating liquid is easy to handle, so that the coating suitability is excellent, and the operating efficiency in the production of coated paper is improved.
- the water retention of the coating liquid is improved, the penetration of the coating liquid into the base paper is suppressed, so that the glossiness of the obtained coated paper is improved, and various coatings such as suppression of pilling are performed. Paper quality is improved.
- the coated paper of the present invention is not particularly limited as long as it is a coated paper in which a pigment coating layer containing a white pigment and an adhesive is provided on the base paper, and is used for offset printing, gravure printing, letterpress printing, and the like.
- the coated paper may be a white paperboard having a pigment coating layer on the paperboard base paper.
- one or more pigment coating layers containing pigments are provided on the base paper.
- a coating liquid (size press liquid) containing no pigment may or may not be applied on the base paper.
- the ash content in the coated paper of the present invention is preferably 10% by weight or more, and more preferably 30% by weight or more. In the case of coated paper for printing, it is preferable to increase the ash content to increase the opacity.
- a pigment coating liquid containing mainly a pigment, an adhesive (binder) and water is used, but a specific molecular weight (weight average molecular weight) is used as the adhesive (binder).
- dextrin is used as a starch-based polymer, but since the viscosity after a certain period of time has passed after steaming is particularly low, the viscosity does not increase significantly even when blended in a pigment coating solution, and the pigment.
- the concentration of the coating liquid can be increased, whereby the print quality of the coated paper can be improved. That is, since the penetration of the paint into the base paper is suppressed and the effective coating layer is increased, the quality of various coated papers such as improvement of gloss development and improvement of surface strength is improved.
- the adhesive used for the pigment coating layer comprises the first dextrin and the second dextrin, and the weight average molecular weight (M1) of the first dextrin and the second dextrin.
- the weight average molecular weight (M2) of each is less than 500 kDa, and M1-M2 is 60 kDa or less.
- the molecular weight of the two dextrin mixtures used in the present invention is less than 500 kDa by weight average molecular weight. It is preferably 450 kDa or less, more preferably 400 kDa or less, still more preferably 350 kDa or less, and may be 300 kDa or less. If the molecular weight is too large, the viscosity of the paste solution becomes high, and the viscosity at the time of blending the paint increases, resulting in poor workability.
- the molecular weight of the mixture of the two dextrins used in the present invention is preferably 100 kDa or more, more preferably 150 kDa or more, and even more preferably 200 kDa or more.
- the weight average molecular weight of the dextrin used in the present invention is preferably 100 kDa or more, more preferably 150 kDa or more, and further preferably 200 kDa or more. If the molecular weight is too small, blanket pileing is likely to occur when printing with an offset rotary press. The reason for this is that the water retention of the coating liquid is reduced and the binder sinks, and the binder does not stay on the surface of the coating layer, resulting in insufficient strength of the coating layer, and the coating layer is peeled off during printing on the blanket. It is thought that it will be deposited in. To prevent this, the coating liquid concentration may be increased, but there is a problem that the operability deteriorates when the coating liquid concentration is increased.
- the weight average molecular weight of each of the two types of dextrins used in combination is 100 kDa or more and less than 500 kDa.
- the viscosity of the coating liquid is lowered, so that the surface strength may be lowered.
- the molecular weight of the high molecular weight dextrin is 500 kDa or more, the viscosity of the dextrin paste solution may increase too much and the workability may be deteriorated, and the viscosity at the time of blending the paint may become too high.
- the advantages of using a dextrin having a high molecular weight and a dextrin having a low molecular weight can be enjoyed. That is, the surface strength of the paper can be improved without impairing workability.
- the difference in molecular weight between the two types of dextrin is preferably less than 60 kDa.
- the difference in molecular weight between the two types of dextrin exceeds 60 kDa, the high molecular weight dextrin causes shrinkage of the paper surface, which may reduce the glossiness.
- the difference in molecular weight between the two dextrins may be small, but may be, for example, 10 kDa or more.
- the weight average molecular weight can be measured by, for example, size exclusion chromatography multi-angle light scattering method (SEC-MALS method).
- the dextrin of the present invention has a slurry viscosity of 1000 mPa ⁇ s or less after being steamed under certain conditions.
- the dextrin of the present invention has a low viscosity of the slurry after steaming, so that the concentration of the slurry can be increased.
- a starch compound is usually suspended in water and heated, the starch granules absorb water and gradually expand. When heating is continued, the starch granules eventually disintegrate and change into a gel. This phenomenon is called gelatinization.
- the starch suspension gradually becomes transparent from a cloudy state and rapidly increases in viscosity.
- the viscosity becomes maximum when the particles absorb the maximum amount of water, and the viscosity decreases due to the decay of the particles.
- the viscosity is in a certain range when the temperature is lowered and the mixture is allowed to stand.
- cold water-soluble starch typified by pregelatinized starch also has a low slurry viscosity, but these cold water-soluble starches are treated so as to be soluble in cold water, and dextrin and the like have higher surface strength. Is high and advantageous. Therefore, the starch-based polymer compound of the present invention preferably has a solubility in water at 20 ° C. of less than 20%.
- the behavior of such starch-based polymers can be measured using a measuring device called Rapid Visco Analyzer (RVA, model RVA-4, manufactured by NewPort Scientific).
- RVA Rapid Visco Analyzer
- dextrin having a viscosity at 50 ° C. of 1000 mPa ⁇ s or less 16 minutes after the start of steaming is used. ..
- dextrin is used as an adhesive for the pigment coating layer, and the adhesive force as a binder is developed by steaming (cooking) the slurry.
- ⁇ RVA viscosity measurement conditions The paddle is rotated under the following conditions, the torque applied to the stirring paddle is measured, and the viscosity is calculated.
- (Stirring conditions) ⁇ 10 seconds after the start of measurement: 960 rpm ⁇ After that: 160 rpm (Steaming conditions) ⁇ 0 to 5 minutes: temperature rise to 98 ° C in 5 minutes ⁇ 5 to 9 minutes: hold at 98 ° C ⁇ 9 to 12 minutes: lower to 50 ° C in 3 minutes ⁇ 12 to 16 minutes: hold at 50 ° C
- the viscosity of the dextrin measured as described above at the stage of holding at 50 ° C. 16 minutes after boiling is preferably 1000 mPa ⁇ s or less, and more preferably 850 mPa ⁇ s or less.
- the dextrin of the present invention preferably has a maximum viscosity of 2000 mPa ⁇ s or less due to gelatinization of starch when the viscosity is measured under the above conditions using RVA, and more preferably 1600 mPa ⁇ s or less.
- a maximum viscosity 2000 mPa ⁇ s or less due to gelatinization of starch when the viscosity is measured under the above conditions using RVA, and more preferably 1600 mPa ⁇ s or less.
- the dextrin of the present invention preferably has the above viscosity, but the modification method and the like are not particularly limited, and the varieties of raw materials and the like are also free.
- preferred raw materials for dextrin used in the present invention include corn, potato, tapioca and the like, and waxy corn (waxy corn) and tapioca are particularly preferable.
- roasted dextrin such as white dextrin is preferable as the adhesive because of its low viscosity and high viscosity stability.
- Dextrin is a general term for starch-based macromolecules obtained by hydrolyzing starch, and ⁇ -glucose is polymerized by glycosidic bonds, and is also called paste.
- Normal starch has a large molecular weight, but dextrin is an intermediate product produced in the process of hydrolyzing starch, and conventionally, the molecular weight is generally about an oligomer (a combination of several to several tens of glucose). there were.
- Roasted dextrin is a dextrin produced by adding acid and baking it with dry heat, and there are various types such as white dextrin, yellow dextrin, and British gum. In the present invention, it is particularly preferable to use white dextrin. Further hydrolysis of white dextrin results in so-called yellow dextrin, but yellow dextrin has low stability and may color the pigment coating layer. Therefore, the use of white dextrin is preferable in the present invention.
- the white dextrin of the present invention preferably has many branches in the dextrin.
- the degree of branching is related to the radius of inertia, and if the molecular weight is the same, it is considered to be linear with many branches when the radius of inertia is small and few branches when the radius of inertia is large. Therefore, the white dextrin of the present invention preferably has a small radius of inertia.
- the dextrin of the present invention has good fluidity when blended in the coating liquid.
- the fluidity is improved, it becomes possible to increase the concentration of the coating liquid, suppress the penetration of the coating liquid, and increase the effective coating layer, so that various things such as improvement of gloss development, improvement of whiteness, improvement of surface strength, etc.
- the quality of coated paper is improved.
- the blending amount of the dextrin of the present invention is used in the range of 0.1 to 30 parts by weight, more preferably 0.5 to 15 parts by weight per 100 parts by weight of the pigment.
- the above-mentioned dextrin can be used as the adhesive, but in addition to the above-mentioned dextrin, an adhesive conventionally used for coated paper can also be used in combination.
- the above-mentioned adhesives other than starch include various copolymers (latex) such as styrene / butadiene type, styrene / acrylic type, ethylene / vinyl acetate type, butadiene / methyl methacrylate type, vinyl acetate / butyl acrylate type, etc.
- Synthetic adhesives such as polyvinyl alcohol, maleic anhydride copolymers, and acrylic acid / methyl methacrylate copolymers; proteins such as casein, soybean protein, and synthetic proteins; oxidation other than the above starch-derived polymer compounds
- Starches such as starch, positive starch, urea phosphoric acid esterified starch, etherified starch such as hydroxyethyl etherified starch
- ordinary coating paper adhesives such as cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose and hydroxymethyl cellulose are included. Is done.
- One or more kinds of adhesives can be appropriately selected and used.
- latex having characteristics different from those of the starch-based polymer compound as an adhesive, and in that case, it is preferable to use more dextrin than the amount of latex used.
- dextrin and latex can be obtained by the combined use, it is preferable to use a large amount of dextrin in order to maximize the effect of the present invention.
- latex is not used as an adhesive, or the amount of latex used is 4 parts by weight or less with respect to 100 parts by weight of the pigment. Further, it is preferable that the amount of latex used is 2.5 parts by weight or less.
- the total amount of the adhesive blended in the coating liquid is not particularly limited, but is preferably 5 to 50 parts by weight, more preferably about 5 to 30 parts by weight, and further preferably 5 to 12 parts by weight per 100 parts by weight of the pigment. Is preferable.
- the total amount thereof is preferably in the above range.
- the method for preparing the coating liquid is not particularly limited, and can be appropriately adjusted depending on the type of coater.
- the solid content concentration of the coating liquid is preferably 40 to 70% by weight, more preferably 50 to 65% by weight.
- the viscosity of the coating liquid is preferably 50 to 3500 mPa ⁇ s, more preferably 100 to 2500 mPa ⁇ s, and may be 150 to 1500 mPa ⁇ s or 200 to 500 mPa ⁇ s with a JIS K 7117-1 B-type viscometer. ..
- auxiliary agents blended in ordinary coated paper pigments such as dispersants, thickeners, water retention agents, defoamers, water resistant agents, and colorants can be appropriately used, if necessary. ..
- the pigment (white pigment) used for the coating layer of the present invention is not particularly limited, and those conventionally used for coated paper can be used, for example, kaolin, clay, engineered kaolin. , Delaminated clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, satin white and other inorganic pigments and solid type, hollow type , Or an organic pigment such as a core-shell type can be used alone or in combination of two or more, if necessary.
- heavy calcium carbonate and light calcium carbonate are preferable from the viewpoint of low binder requirement and a small amount of adhesive can improve surface strength and high whiteness, and also improve opacity.
- light calcium carbonate having a uniform particle size and shape is particularly preferable. This is because the bulky coating layer structure scatters light efficiently.
- the total content of light calcium carbonate, heavy calcium carbonate, or both is preferably 50 parts by weight or more, more preferably 70 parts by weight or more per 100 parts by weight of the pigment. 80 weight or more is more preferable.
- the average particle size is preferably 0.2 to 5 ⁇ m, which is a value measured by a laser diffraction type particle size distribution measuring machine such as Mastersizer S manufactured by Malvern. .3 to 3 ⁇ m is more preferable.
- any commonly used coater may be used. It can be an on-machine coater or an off-machine coater, and if it is an on-machine coater, it can be a roll coater such as a size press coater, a gate roll coater, a rod metering size press coater, a bill blade coater, a blade metering size press coater, or a short duel blade. Coaters such as coaters and jet fountain blade coaters can be used.
- the coating speed is not particularly limited, but in the current technology, it is preferably 500 to 1800 m / min for a blade coater and 500 to 2000 m / min for a size press coater.
- the method of drying the wet coating layer there is no limitation on the method of drying the wet coating layer, and various methods such as a steam superheating cylinder, a heated hot air air dryer, a gas heater dryer, an electric heater dryer, and an infrared heater dryer can be used alone or in combination. it can.
- the amount of the coating liquid applied in the present invention can be appropriately selected depending on the intended use, but generally, the solid content per side is 2 to 13 g / m 2 , and 4 to 11 g / m 2 or 6 to 9 g. It may be / m 2 .
- the concentration of the coating liquid of the present invention is not particularly limited, but in consideration of print quality, it is preferably 40% by weight or more, preferably 55% by weight or more and 75% by weight or less. Since a specific dextrin is used as an adhesive in the present invention, the concentration of the coating liquid can be increased. However, if the concentration of the coating liquid is too high, the coating liquid becomes thickened and the operability deteriorates. In the present invention, more preferably 65% by weight or less, it is possible to maintain good operability.
- the Brookfield viscosity (B-type viscosity, 60 rpm) of the coating liquid of the present invention is preferably 50 mPa ⁇ s or more and 3500 mPa ⁇ s or less, and is about 100 mPa ⁇ s or more and 3000 mPa ⁇ s or less from the viewpoint of operability and the like. Is preferable, 150 mPa ⁇ s or more and 2000 mPa ⁇ s or less is more preferable, and 200 mPa ⁇ s or more and 1000 mPa ⁇ s or less may be used.
- the coated paper of the present invention has at least a base paper layer.
- the base paper can be produced by a known method.
- a papermaking raw material paper material
- the base paper used in the present invention may be single-layer paper or multi-layer paper, but when producing white paperboard, it is preferable to use multi-layer paper.
- the method for producing the base paper of the present invention is not particularly limited, and a known method can be used using a known raw material.
- the base paper used in the present invention is not particularly limited, with the exception of commonly used high-quality paper, medium-quality paper, stencil paper, machine-coated paper, art paper, cast-coated paper, synthetic paper, resin-coated paper, plastic film, and the like. Can be used without.
- the basis weight of the base paper of the present invention is not particularly limited and can be appropriately selected depending on the intended use. For example, it can be 30 to 150 g / m 2 , 33 to 100 g / m 2 or 35 to 75 g / m 2. May be good.
- Chemical pulp can be used as the pulp raw material used for the base paper of the present invention.
- various types of pulp can be used depending on the application.
- deinked pulp DIP
- crushed wood pulp GP
- refiner crushed wood pulp RGP
- thermomechanical pulp TMP
- chemithermo examples thereof include mechanical pulp (CTMP), chemigrand pulp (CGP), and semi-chemical pulp (SCP).
- CMP mechanical pulp
- CGP chemigrand pulp
- SCP semi-chemical pulp
- selected waste paper such as high-quality paper, medium-quality paper, low-grade paper, newspaper, leaflets, and magazines, and deinking pulp made from unsorted waste paper in which these are mixed can be used.
- a known filler can be arbitrarily used as a filler for the base paper, and for example, heavy calcium carbonate, light calcium carbonate, clay, silica, light calcium carbonate-silica complex, kaolin, calcined kaolin, delamikaolin, white.
- Inorganic fillers such as silica and organic fillers such as urea-formalin resin, melamine resin, polystyrene resin, and phenol resin can be used alone or in combination.
- heavy calcium carbonate and light calcium carbonate which are typical fillers in neutral papermaking and alkaline papermaking, are preferably used for improving opacity.
- the filling ratio in paper is not particularly limited, but is preferably 1 to 40% by weight of solid content, and more preferably 10 to 35% by weight of solid content.
- known papermaking additives can be used.
- a sulfuric acid band various anionic, cationic, nonionic, or amphoteric yield improvers, drainage improvers, various paper strength enhancers, internal sizing agents, and other papermaking aids as needed.
- the dry paper strength improver include polyacrylamide and cationized starch
- examples of the wet paper strength improver include polyamideamine epichlorohydrin. These chemicals are added within a range that does not affect the formation or operability.
- the neutral sizing agent include alkyl ketene dimers, alkenyl succinic anhydride, and neutral rosin sizing agents.
- a dye, a fluorescent whitening agent, a pH adjusting agent, a defoaming agent, a pitch control agent, a slime control agent and the like can be added as needed.
- the method of making the base paper in the present invention is not particularly limited, and a long net paper machine including a top wire, an on-top former, a gap former, a round net paper machine, a long net paper machine and a round net paper machine are used in combination. This can be done using a paperboard machine, a Yankee dryer machine, or the like.
- the pH at the time of papermaking may be acidic, neutral or alkaline, but neutral or alkaline is preferable.
- the papermaking speed is not particularly limited.
- the coated paper of the present invention may have a clear (transparent) coating layer on one side or both sides of the above-mentioned base paper.
- the clear coating layer may contain the starch-derived polymer compound of the present invention as a binder.
- the amount of clear coating is preferably 0.1 to 4.0 g / m 2 and more preferably 0.5 to 2.5 g / m 2 in terms of solid content per side.
- clear coating refers to various types of starch such as starch and oxidized starch using a coater (coating machine) such as a size press, a gate roll coater, a pre-metering size press, a curtain coater, and a spray coater.
- a coater coating machine
- Polyacrylamide, polyvinyl alcohol and other water-soluble polymers as the main component coating liquid (surface treatment liquid) is applied (size press) on the base paper.
- the processing linear pressure is preferably 30 to 100 kN / m, more preferably 50 to 100 kN / m.
- the moisture content of the base paper during the pre-calendar treatment is also important, and the moisture content is preferably 3 to 5%.
- the paper produced as described above is surface-treated as necessary.
- a smoothing processing device such as a normal super calendar, a gloss calendar, a soft calendar, a thermal calendar, or a shoe calendar can be used.
- the smoothing processing device is appropriately used on-machine or off-machine, and the form of the pressurizing device, the number of pressurizing nips, heating, and the like are appropriately adjusted.
- the coated paper of the present invention can be surface-treated with a calendar such as a super calendar or a high temperature soft nip calendar.
- the surface treatment can improve the smoothness and glossiness of the coated paper.
- soft nip calendar processing is preferable.
- the linear pressure at which the surface temperature of the metal roll is 20 ° C. to 60 ° C. is 30 to 60 kN / m, more preferably 40 to 60 kN / m.
- the linear pressure is 60 to 400 kN / m, preferably 150 to 300 kN / m, and more preferably 100 to 350 kN / m. is there. Increasing the temperature improves the gloss and smoothness of the surface of the coated paper.
- the weight average molecular weight of roasted dextrin can be measured using GPC under the following measurement conditions.
- -Separation column 2 Shodex GPC KB-806M, 1 Shodex GPC KB-802-Column temperature: 40 ° C.
- -Mobile phase solvent Sodium nitrate aqueous solution (0.1 mol / L)
- -Mobile phase flow velocity 0.5 mL / min ⁇
- Injection amount 300 ⁇ L
- -Detector 1 Multi-angle light scattering detector (Wyatt, "DAWN HELEOS II")
- -Detector 2 Refractive index (RI) detector (manufactured by Waters, "2414 type”)
- RI Refractive index
- B-type viscosity of paint The prepared coating liquid was measured with a B-type viscometer (model: LVDV-I, manufactured by Eiko Seiki Co., Ltd.) at a liquid temperature of 30 ° C. and a rotation speed of 60 rpm.
- High Shear Viscosity of Paint The prepared coating liquid was measured with a Hercule High Shear Viscometer (model: DV-10, manufactured by Kaltec Scientific) at a liquid temperature of 30 ° C., a rotation speed of 8800 rpm, and a bob of F2.5.
- paper is made with a roll-and-blade former type gap former paper machine at a paper making speed of 1500 m / min, and two tandem shoe presses (press linear pressure 1000 kN / m) are used for the press part.
- the wet paper was squeezed and dried using a transfer belt contacting the wire surface side of the paper) to obtain a medium-quality coated base paper of 35.7 g / m 2 .
- the above coating liquid was continuously applied to both sides with a jet fountain type blade coater so that the amount of coating was 7.0 g / m 2 per side of the base paper, and dried.
- a 2-roll / 6-stack soft calendar having an elastic roll with a shore hardness of D94 ° was used, the surface temperature of each metal roll was 130 ° C, and the nip wire pressure was 250 kN / m on the surface of the coated paper. Processing was performed.
- the coating speed and calendar speed were also 1500 m / min.
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Abstract
Description
(1) 顔料と接着剤とを含む顔料塗工層を原紙上に有する塗工紙であって、該接着剤が、第1のデキストリンと第2のデキストリンを含んでなり、第1のデキストリンの重量平均分子量(M1)と第2のデキストリンの重量平均分子量(M2)がいずれも500kDa未満であり、M1-M2が60kDa以下である、上記塗工紙。
(2) 第1のデキストリンと第2のデキストリンの併用比率(重量比)が、2:8~8:2である、(1)に記載の塗工紙。
(3) 第1のデキストリンと第2のデキストリンが、いずれも白色デキストリンである、(1)または(2)に記載の塗工紙。
(4) M1とM2がいずれも150~400kDaである、(1)~(3)のいずれかに記載の塗工紙。
(5) 顔料と接着剤とを含む塗工液を調整する工程と、塗工液を原紙に塗工する工程と、を含む、塗工紙の製造方法であって、該接着剤が、第1のデキストリンと第2のデキストリンを含んでなり、第1のデキストリンの重量平均分子量(M1)と第2のデキストリンの重量平均分子量(M2)がいずれも500kDa未満であり、M1-M2が60kDa以下である、上記方法。 The present invention includes, but is not limited to, the following inventions.
(1) A coated paper having a pigment coating layer containing a pigment and an adhesive on a base paper, wherein the adhesive contains a first dextrin and a second dextrin, and the first dextrin. The coated paper having a weight average molecular weight (M1) and a weight average molecular weight (M2) of the second dextrin of less than 500 kDa and M1-M2 of 60 kDa or less.
(2) The coated paper according to (1), wherein the combined use ratio (weight ratio) of the first dextrin and the second dextrin is 2: 8 to 8: 2.
(3) The coated paper according to (1) or (2), wherein the first dextrin and the second dextrin are both white dextrins.
(4) The coated paper according to any one of (1) to (3), wherein both M1 and M2 are 150 to 400 kDa.
(5) A method for producing coated paper, which comprises a step of adjusting a coating liquid containing a pigment and an adhesive and a step of applying the coating liquid to a base paper, wherein the adhesive is the first. It contains 1 dextrin and 2nd dextrin, and the weight average molecular weight (M1) of the 1st dextrin and the weight average molecular weight (M2) of the 2nd dextrin are both less than 500 kDa, and M1-M2 is 60 kDa or less. The above method.
本発明においては、顔料塗工層を設けるため、主として顔料、接着剤(バインダー)、水を含む顔料塗工液を用いるが、接着剤(バインダー)として、特定の分子量(重量平均分子量)を有する澱粉系高分子を添加する。本発明では、澱粉系高分子としてデキストリンを使用するが、蒸煮後の一定時間経過後における粘度が特に低いため、顔料塗工液に配合してもその粘度を大幅に増大させることがなく、顔料塗工液の濃度を高くすることができ、それにより、塗工紙の印刷品質を向上させることができる。すなわち、原紙への塗料のしみこみを抑制し、有効塗工層が増えることから、光沢発現性向上、表面強度向上など、種々の塗工紙品質が向上する。 Dextrin In the present invention, in order to provide the pigment coating layer, a pigment coating liquid containing mainly a pigment, an adhesive (binder) and water is used, but a specific molecular weight (weight average molecular weight) is used as the adhesive (binder). Add the starch-based polymer to have. In the present invention, dextrin is used as a starch-based polymer, but since the viscosity after a certain period of time has passed after steaming is particularly low, the viscosity does not increase significantly even when blended in a pigment coating solution, and the pigment. The concentration of the coating liquid can be increased, whereby the print quality of the coated paper can be improved. That is, since the penetration of the paint into the base paper is suppressed and the effective coating layer is increased, the quality of various coated papers such as improvement of gloss development and improvement of surface strength is improved.
以下の条件でパドルを回転させ、攪拌しているパドルにかかるトルクを測定し、粘度を算出する。
(攪拌条件)
・測定開始後10秒:960rpm
・その後 :160rpm
(蒸煮条件)
・ 0~ 5分:5分間で98℃まで昇温
・ 5~ 9分:98℃にて保持
・ 9~12分:3分間で50℃まで降温
・12~16分:50℃にて保持
上記の通り測定したデキストリンの蒸煮後16分後の50℃にて保持する段階における粘度は、好ましくは1000mPa・s以下であり、より好ましくは850mPa・s以下である。 <RVA viscosity measurement conditions>
The paddle is rotated under the following conditions, the torque applied to the stirring paddle is measured, and the viscosity is calculated.
(Stirring conditions)
・ 10 seconds after the start of measurement: 960 rpm
・ After that: 160 rpm
(Steaming conditions)
・ 0 to 5 minutes: temperature rise to 98 ° C in 5 minutes ・ 5 to 9 minutes: hold at 98 ° C ・ 9 to 12 minutes: lower to 50 ° C in 3 minutes ・ 12 to 16 minutes: hold at 50 ° C The viscosity of the dextrin measured as described above at the stage of holding at 50 ° C. 16 minutes after boiling is preferably 1000 mPa · s or less, and more preferably 850 mPa · s or less.
本発明の塗工層に用いる顔料(白色顔料)は特に制限されず、塗工紙用に従来から用いられているものを使用することができ、例えば、カオリン、クレー、エンジニアードカオリン、デラミネーテッドクレー、重質炭酸カルシウム、軽質炭酸カルシウム、タルク、二酸化チタン、硫酸バリウム、硫酸カルシウム、酸化亜鉛、珪酸、珪酸塩、コロイダルシリカ、サチンホワイトなどの無機顔料および密実型、中空型、またはコアーシェル型などの有機顔料などを必要に応じて単独または2種類以上混合して使用することができる。また、顔料の種類としては、バインダー要求量が少なく少量の接着剤で表面強度を向上できることと、高い白色度の観点から、重質炭酸カルシウムおよび軽質炭酸カルシウムが好ましく、また不透明度をも向上させる観点から、粒子径や形状が揃った軽質炭酸カルシウムが特に好ましい。嵩高な塗工層構造は光を効率的に散乱するためである。 Coating Pigment The pigment (white pigment) used for the coating layer of the present invention is not particularly limited, and those conventionally used for coated paper can be used, for example, kaolin, clay, engineered kaolin. , Delaminated clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, satin white and other inorganic pigments and solid type, hollow type , Or an organic pigment such as a core-shell type can be used alone or in combination of two or more, if necessary. Further, as the type of pigment, heavy calcium carbonate and light calcium carbonate are preferable from the viewpoint of low binder requirement and a small amount of adhesive can improve surface strength and high whiteness, and also improve opacity. From the viewpoint, light calcium carbonate having a uniform particle size and shape is particularly preferable. This is because the bulky coating layer structure scatters light efficiently.
本発明においては、通常用いられるコータであればいずれを用いても良い。オンマシンコータでもオフマシンコータでも良く、オンマシンコータであれば、サイズプレスコータ、ゲートロールコータ、ロッドメタリングサイズプレスコーターなどのロールコータ、ビルブレイドコータ、ブレードメタリングサイズプレスコータ、ショートドゥエルブレードコーター、ジェットファウンテンブレードコーターなどのコータを使用できる。塗工速度は、特に限定されないが、現在の技術ではブレードコータでは500~1800m/分、サイズプレスコータでは500~2000m/分が好ましい。 Coating In the present invention, any commonly used coater may be used. It can be an on-machine coater or an off-machine coater, and if it is an on-machine coater, it can be a roll coater such as a size press coater, a gate roll coater, a rod metering size press coater, a bill blade coater, a blade metering size press coater, or a short duel blade. Coaters such as coaters and jet fountain blade coaters can be used. The coating speed is not particularly limited, but in the current technology, it is preferably 500 to 1800 m / min for a blade coater and 500 to 2000 m / min for a size press coater.
本発明の塗工紙は少なくとも原紙層を有する。原紙は公知の方法により製造することができ、例えば、抄紙原料(紙料)をワイヤーパートにて抄紙し、次いでプレスパート、プレドライヤーパートに供して原紙を製造することができる。本発明に用いる原紙は、単層抄きであっても多層抄きであってもよいが、白板紙を製造する場合は多層抄き原紙を用いることが好ましい。本発明の原紙の製法は特に制限されず、公知の原料を用いて公知の方法によることができる。本発明で使用される原紙は特に制限されず、一般に使用される上質紙、中質紙、更紙、マシンコート紙、アート紙、キャストコート紙、合成紙、レジンコーテッド紙、プラスチックフィルム等を例外なく使用できる。 Base Paper The coated paper of the present invention has at least a base paper layer. The base paper can be produced by a known method. For example, a papermaking raw material (paper material) can be made in a wire part and then used in a press part and a pre-dryer part to produce the base paper. The base paper used in the present invention may be single-layer paper or multi-layer paper, but when producing white paperboard, it is preferable to use multi-layer paper. The method for producing the base paper of the present invention is not particularly limited, and a known method can be used using a known raw material. The base paper used in the present invention is not particularly limited, with the exception of commonly used high-quality paper, medium-quality paper, stencil paper, machine-coated paper, art paper, cast-coated paper, synthetic paper, resin-coated paper, plastic film, and the like. Can be used without.
本発明においては、以上のように製造した紙を必要に応じて表面処理する。平滑化処理には、通常のスーパーカレンダー、グロスカレンダー、ソフトカレンダー、熱カレンダー、シューカレンダー等の平滑化処理装置を用いることができる。平滑化処理装置は、オンマシンやオフマシンで適宜用いられ、加圧装置の形態、加圧ニップの数、加温等も適宜調整される。好ましい態様において、本発明の塗工紙は、スーパーカレンダーや高温ソフトニップカレンダー等のカレンダーで表面処理を行うことができる。表面処理により、塗工紙の平滑度や光沢性を向上させることができる。本発明においては、ソフトニップカレンダー処理が好ましい。ソフトニップカレンダー処理をすることにより、白色度、不透明度共に向上する。ソフトニップカレンダー処理において、金属ロールの表面温度が20℃~60℃の線圧は、30~60kN/m、より好ましくは、40~60kN/mである。また、金属ロールの表面温度が40℃~250℃の高温ソフトニップカレンダー処理であれば、線圧は60~400kN/m、好ましくは、150~300kN/m、より好ましくは100~350kN/mである。温度を上げると、塗工紙の表面の光沢、平滑度が向上する。 Surface treatment In the present invention, the paper produced as described above is surface-treated as necessary. For the smoothing process, a smoothing processing device such as a normal super calendar, a gloss calendar, a soft calendar, a thermal calendar, or a shoe calendar can be used. The smoothing processing device is appropriately used on-machine or off-machine, and the form of the pressurizing device, the number of pressurizing nips, heating, and the like are appropriately adjusted. In a preferred embodiment, the coated paper of the present invention can be surface-treated with a calendar such as a super calendar or a high temperature soft nip calendar. The surface treatment can improve the smoothness and glossiness of the coated paper. In the present invention, soft nip calendar processing is preferable. By performing soft nip calendar processing, both whiteness and opacity are improved. In the soft nip calendar processing, the linear pressure at which the surface temperature of the metal roll is 20 ° C. to 60 ° C. is 30 to 60 kN / m, more preferably 40 to 60 kN / m. Further, in the case of high temperature soft nip calendar processing in which the surface temperature of the metal roll is 40 ° C. to 250 ° C., the linear pressure is 60 to 400 kN / m, preferably 150 to 300 kN / m, and more preferably 100 to 350 kN / m. is there. Increasing the temperature improves the gloss and smoothness of the surface of the coated paper.
生コーンデンプンに塩酸を添加し、プロシェアミキサ(大平洋機工)を用いて130℃で90分間加熱して焙焼デキストリンを製造した。具体的には、以下のように塩酸添加量を変えて分子量が異なる白色焙焼デキストリンを得た。 Method for producing roasted dextrin Hydrochloric acid was added to raw corn starch and heated at 130 ° C. for 90 minutes using a Prosheer mixer (Pacific Machinery & Engineering Co., Ltd.) to produce roasted dextrin. Specifically, white roasted dextrins having different molecular weights were obtained by changing the amount of hydrochloric acid added as follows.
・分離カラム:Shodex GPC KB-806M 2本、Shodex GPC KB-802 1本
・カラム温度:40℃
・移動相溶媒:硝酸ナトリウム水溶液(0.1mol/L)
・移動相流速:0.5mL/min
・注入量:300μL
・検出器1:多角度光散乱検出器(Wyatt社製、「DAWN HELEOSII」)
・検出器2:屈折率(RI)検出器(Waters社製、「2414型」)
・試料:[蒸煮]100℃で20分間攪拌、[濃度]0.4w/v%、[濾過]クロマトディスク 孔径0.45μm(クラボウ製)
・データ処理:ASTRA(Wyatt社製) The weight average molecular weight of roasted dextrin can be measured using GPC under the following measurement conditions.
-Separation column: 2 Shodex GPC KB-806M, 1 Shodex GPC KB-802-Column temperature: 40 ° C.
-Mobile phase solvent: Sodium nitrate aqueous solution (0.1 mol / L)
-Mobile phase flow velocity: 0.5 mL / min
・ Injection amount: 300 μL
-Detector 1: Multi-angle light scattering detector (Wyatt, "DAWN HELEOS II")
-Detector 2: Refractive index (RI) detector (manufactured by Waters, "2414 type")
-Sample: [Steamed] Stir at 100 ° C. for 20 minutes, [Concentration] 0.4 w / v%, [Filtration] Chromatodisc Pore diameter 0.45 μm (manufactured by Kurabo Industries)
-Data processing: ASTRA (manufactured by Wyatt)
(1)坪量:JIS P 8124に準じて測定した。
(2)紙厚:JIS P 8118に準じて測定した。
(3)密度:JIS P 8118に準じて坪量と紙厚から求めた。
(4)白紙光沢度
JIS P-8142に従い、角度75度で測定した。
(5)印刷光沢度
オフセット輪転機(東芝オフセットBT600)、オフセット印刷用インキ(東洋インキ製造(株)製:レオエックスM)を使用し4色(墨、藍、紅、黄)印刷した後、印刷物の藍ベタ部の表面をJIS P 8142に基づいて測定した。
(6)灰分:JIS P8251に従い測定した。
(7)塗料のB型粘度
調製した塗液をB型粘度計(型式:LVDV-I、英弘精機社製)により、液温30℃、回転数60rpmで測定した。
(8)塗料のハイシェア粘度
調製した塗液をハーキュリー・ハイシェア粘度計(型式:DV-10、Kaltec Scientific社製)により、液温30℃、回転数8800rpm、F2.5のボブで測定した。 Evaluation method (1) Basis weight: Measured according to JIS P 8124.
(2) Paper thickness: Measured according to JIS P 8118.
(3) Density: Obtained from the basis weight and paper thickness according to JIS P 8118.
(4) Blank sheet glossiness Measured at an angle of 75 degrees according to JIS P-8142.
(5) Printing gloss After printing in 4 colors (ink, indigo, red, yellow) using an offset rotary press (Toshiba offset BT600) and offset printing ink (manufactured by Toyo Ink Mfg. Co., Ltd .: Leox M), The surface of the solid indigo portion of the printed matter was measured based on JIS P 8142.
(6) Ash content: Measured according to JIS P8251.
(7) B-type viscosity of paint The prepared coating liquid was measured with a B-type viscometer (model: LVDV-I, manufactured by Eiko Seiki Co., Ltd.) at a liquid temperature of 30 ° C. and a rotation speed of 60 rpm.
(8) High Shear Viscosity of Paint The prepared coating liquid was measured with a Hercule High Shear Viscometer (model: DV-10, manufactured by Kaltec Scientific) at a liquid temperature of 30 ° C., a rotation speed of 8800 rpm, and a bob of F2.5.
古紙パルプ65部とNBKP20部、LBKP15部とからなるパルプスラリーに、填料として軽質炭酸カルシウムを紙中灰分が16%になるように添加し、内添紙力剤としてカチオン化澱粉を0.7部、ポリアクリルアミド(PAM)を0.3部添加して紙料を調整した。 Manufacture and evaluation of pigmented paper To a pulp slurry consisting of 65 parts of used paper pulp, 20 parts of NBKP, and 15 parts of LBKP, light calcium carbonate is added as a filler so that the ash content in the paper is 16%, and it is used as an internal paper strength agent. 0.7 parts of cationized starch and 0.3 parts of polyacrylamide (PAM) were added to adjust the paper material.
Claims (5)
- 顔料と接着剤とを含む顔料塗工層を原紙上に有する塗工紙であって、
該接着剤が、第1のデキストリンと第2のデキストリンを含んでなり、第1のデキストリンの重量平均分子量(M1)と第2のデキストリンの重量平均分子量(M2)がいずれも500kDa未満であり、M1-M2が60kDa以下である、上記塗工紙。 A coated paper having a pigment coating layer containing a pigment and an adhesive on a base paper.
The adhesive comprises a first dextrin and a second dextrin, and the weight average molecular weight (M1) of the first dextrin and the weight average molecular weight (M2) of the second dextrin are both less than 500 kDa. The coated paper having M1-M2 of 60 kDa or less. - 第1のデキストリンと第2のデキストリンの併用比率が、2:8~8:2である、請求項1に記載の塗工紙。 The coated paper according to claim 1, wherein the combined ratio of the first dextrin and the second dextrin is 2: 8 to 8: 2.
- 第1のデキストリンと第2のデキストリンが、いずれも白色デキストリンである、請求項1または2に記載の塗工紙。 The coated paper according to claim 1 or 2, wherein the first dextrin and the second dextrin are both white dextrins.
- M1とM2がいずれも150~400kDaである、請求項1~3のいずれかに記載の塗工紙。 The coated paper according to any one of claims 1 to 3, wherein both M1 and M2 are 150 to 400 kDa.
- 顔料と接着剤とを含む塗工液を調整する工程と、
塗工液を原紙に塗工する工程と、
を含む、塗工紙の製造方法であって、
該接着剤が、第1のデキストリンと第2のデキストリンを含んでなり、第1のデキストリンの重量平均分子量(M1)と第2のデキストリンの重量平均分子量(M2)がいずれも500kDa未満であり、M1-M2が60kDa以下である、上記方法。 The process of adjusting the coating liquid containing the pigment and the adhesive,
The process of applying the coating liquid to the base paper and
It is a manufacturing method of coated paper including
The adhesive comprises a first dextrin and a second dextrin, and the weight average molecular weight (M1) of the first dextrin and the weight average molecular weight (M2) of the second dextrin are both less than 500 kDa. The above method, wherein M1-M2 is 60 kDa or less.
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JPH05195489A (en) * | 1992-01-22 | 1993-08-03 | Honen Corp | Starch composition for coating paper |
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