JP2007119990A - Method for producing coated paper for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a coated paper for printing contributing to environmental preservation and having excellent printing suitability. <P>SOLUTION: The method for producing the coated paper for printing comprising a coated layer consisting essentially of a pigment and a cationic binder and formed on at least one surface is provided. The method is characterized as follows. A regenerated pigment aggregate is obtained by passing deinked floss discharged from a waste paper treating step as a main raw material through a dehydration step, a drying step, a burning step and a pulverization step and aggregating the resultant particles in the burning step. The regenerated pigment aggregate having the following composition in an elementary analysis of the surface of the coated paper with an X-ray micro-analyzer is contained as at least a pigment for coating in the pigment to coat base paper with the regenerated pigment aggregate. Aluminum, silicon and calcium are contained in the incorporation ratio of (8-40):(10-40):(20-82) expressed in terms of oxides in particle constituent components of the regenerated pigment aggregate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a coated paper for printing used in offset printing or the like.

Along with the trend of zero factory waste (zero emission), technological development for effectively utilizing papermaking sludge such as deinking floss, drainage and dewatered sludge, or incineration ash is being promoted. Under such circumstances, the present applicant has proposed a technique of manufacturing and using papermaking sludge as a regenerated pigment (see, for example, Patent Document 1). However, such regenerated pigments still have drawbacks such as brittleness and low whiteness as compared with natural pigments, and it is difficult to realize excellent printability even when used as an additive for papermaking. .
JP 2002-275785 A

  The present invention has been made in view of such circumstances, and an object thereof is to provide a method for producing a coated paper for printing excellent in printability while contributing to environmental conservation.

The present invention
In the method for producing a coated paper for printing in which a coating layer containing a pigment and a cationic binder as essential components on at least one side is formed,
In the pigment, the main raw material is deinking floss discharged from the waste paper processing step,
The main raw material is obtained through a dehydration step, a drying step, a firing step and a pulverization step,
In the elemental analysis by the X-ray microanalyzer on the coated paper surface, at least a regenerated pigment aggregate having the following composition is contained as a coating pigment, and the regenerated pigment aggregate is applied,
In the elemental analysis by the X-ray microanalyzer of the coated paper surface, aluminum, silicon, and calcium are converted into oxides as the particle constituents of the regenerated pigment aggregate in the range of 8-40: 10-40: 20-82. It is related with the manufacturing method of the coated paper for printing contained by the inclusion rate of.

  According to the above configuration, since the regenerated pigment aggregate having aluminum (Al), silicon (Si), and calcium (Ca) as elements is used for the outermost coating layer that greatly affects printability, it is cationic. High compatibility with the binder makes it possible to increase the surface strength of the coating layer compared to conventional pigments, resulting in the formation of a coating layer with excellent cushioning properties, which can contribute to environmental conservation, and as a result In addition, it is possible to easily produce a coated paper for printing that achieves high printability.

  In the method for producing a coated paper for printing of the present invention, the total inclusion ratio of aluminum, silicon and calcium in terms of oxides in the particle constituents of the regenerated pigment aggregate is preferably 90% by weight or more. . By making the total inclusion ratio of aluminum, silicon, and calcium in terms of oxides 90% by weight or more, the effectiveness as a pigment aggregate containing each element of aluminum, silicon, and calcium can be exhibited. it can. Aluminum provides strong cationic properties, silicon provides ink absorption and ink drying properties due to the secondary aggregation effect of fine silica particles, and calcium improves whiteness.

  In the coated coated paper obtained by the production method of the present invention, the average particle size of the regenerated pigment aggregate in the coated layer is set within a range of 0.1 to 10 μm, and the coated paper The average particle diameter of the regenerated pigment aggregate in the working layer is preferably set to be smaller than the average particle diameter of the other pigments in the coating layer. In this case, the regenerated pigment aggregate that is relatively flexible in the flattening treatment is combined flatly with the shape of the other pigment in the coating layer, and the unevenness and waviness on the surface of the coating layer derived from the pigment are reduced. Therefore, the surface of the coating layer can be further flattened.

  According to the production method of the present invention, in the elemental analysis by the X-ray microanalyzer on the surface of the coated paper, the particle constituents include aluminum, silicon, and calcium in terms of oxides of 8 to 40:10 to 40: Since a coating layer containing a regenerated pigment aggregate contained in an inclusion ratio of 20 to 82 is formed, it is possible to provide a coated paper for printing excellent in printability while contributing to environmental conservation. it can.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a coated paper for printing manufactured by a manufacturing method according to an embodiment of the present invention. The coated paper T for printing according to the present embodiment includes a paper base 1, a lower coating layer 2 formed on each of both surfaces thereof, and an upper side formed on each of the lower coating layers 2, respectively. A coating layer (outermost layer coating layer) 3 is provided.

The paper substrate 1 is not particularly limited, and various known materials can be used. Specifically, it may be only a single-layer base paper, or may be a multi-layered structure of two or more layers by overlapping different or similar base papers. As raw material pulp, for example, mechanical pulp, kraft pulp, and recycled pulp are suitably used as main raw materials, and known non-wood pulp such as kenaf, bamboo, hemp, and straw can be used in combination. These may be used alone or in combination of two or more. Further, the basis weight of the base paper is not particularly limited, and for example, a base paper having a basis weight of about 40 to 130 g / m ² is preferably used. As a papermaking method of the base paper, a twin wire former machine, a long net machine, a method using an on-line machine that can perform a series of processes from base paper to coating layer formation and coating layer surface treatment, etc. Can be adopted.

  Each lower coating layer 2 is formed using a coating liquid for forming the lower coating layer 2 (hereinafter, referred to as “lower coating liquid”) mainly composed of a pigment and an adhesive. Suitable pigments used in the lower coating liquid include calcium carbonate (heavy calcium carbonate, light calcium carbonate), delaminated clay, calcined clay, satin white, titanium dioxide, aluminum hydroxide, zinc oxide, sulfuric acid Inorganic pigments such as barium, calcium hydroxide, calcium sulfate, calcium sulfite, magnesium carbonate, magnesium hydroxide, bentonite, sericite, silica, talc, activated clay, polystyrene resin fine particles, urea formalin resin fine particles, fine hollow particles, porous Organic pigments such as fine particles can be used. These can be used alone or in combination of two or more. Of these, calcium carbonate and clay are preferably used. And a pigment is used in the appropriate ratio from which the solid content concentration of a coating liquid will be about 50 to 70%.

  Moreover, as an adhesive agent used for the lower side coating liquid, although it does not restrict | limit, a water-soluble adhesive agent is used suitably. Specific examples include starches such as oxidized starch, cationic starch, esterified starch, and dextrin, synthetic resin adhesives such as polyvinyl alcohol (PVA), proteins such as casein, soybean protein, and synthetic protein. Also, conjugated diene copolymer latex such as styrene-butadiene copolymer, acrylic copolymer latex such as acrylate polymer or copolymer, and vinyl polymer such as ethylene-vinyl acetate copolymer. Latex, or alkali-soluble, alkali-swellable or alkali-insoluble polymer latex obtained by modifying these polymer latexes with a functional group-containing monomer such as a carboxyl group may be used. These adhesives may be used alone or in combination of two or more. And although the mixture ratio of an adhesive agent is suitably set by the kind etc. of the adhesive agent to be used, it is preferable to set normally in the range of 5-30 weight part with respect to 100 weight part of pigments. This is because if the blending amount of the adhesive is too small, the predetermined adhesive force may not be obtained, and conversely if too large, the coatability may be adversely affected.

  In addition to the above-described components, the lower coating liquid includes various conventionally known assistants such as a dispersant, a thickener, a lubricant, an antifoaming agent, a water-resistant agent, a colorant, and a pH adjuster. The agent can be appropriately blended according to the purpose of use and needs.

  The upper coating layer (outermost layer coating layer) 3 formed on each of the lower coating layers 2 is a coating solution for forming the upper coating layer 3 mainly composed of a pigment and a cationic binder. (Hereinafter referred to as “upper coating liquid”). In the pigment blended in the upper coating liquid, aluminum, silicon, and calcium are converted into oxides in terms of oxides in the elemental analysis using an X-ray microanalyzer on the coated paper surface. Regenerated pigment aggregates contained in an inclusion ratio of 10-40: 20-82 are contained.

  Here, the regenerated pigment aggregate will be described in detail.

  Recycled pigment is obtained by calcining waste. Examples of waste include waste sludge containing fillers and pigments discharged in the wastewater treatment process of a paper mill, wastepaper dissolution process and foreign matter removal process in the wastepaper treatment process. Examples of papermaking sludge to be discharged, papermaking sludge to be discharged in the waste paper deinking process, papermaking sludge to be discharged in the raw material adjustment process, etc. can be exemplified. Aggregation is obtained by using the deinked floss discharged from the waste paper processing process as the main raw material, and the main raw material is obtained through a dehydration process, a drying process, a firing process, and a pulverization process. It was manufactured without doing.

  Paper sludges other than deinking floss are likely to cause fluctuations in product properties because their constituent components tend to fluctuate. On the other hand, deinking floss has almost no change in the constituent components, so that it is easy to control the quality such as whiteness of the obtained regenerated pigment aggregate, and is suitable for papermaking. The components of the deinking floss are stable with almost no change, because the stability of the properties of the used paper pulp leads to the stability of the quality of the recycled paper. This is to make it homogeneous.

  In order to suppress the fluctuation of the constituent components, in addition to the use of the deinking floss, a predetermined amount of sludge having a stable property, such as a coating process sludge and a papermaking process sludge, may be mixed.

  Here, the deinking floss is a residue after deinking and taking out the pulp in the used paper processing step. It mainly contains inorganic particles such as kaolin, calcium carbonate, talc and titanium dioxide, residual ink particles, fibers, organic compounds such as coating agents, and water. The deinking floss is, for example, solid-liquid separated by a method such as precipitation or pressurized flotation, collected solids, dried to a predetermined moisture, and adjusted to a predetermined unburned rate in the first firing step And fired. Thereby, it becomes the porous raw material aggregated in the lump shape.

  Below, the example of the manufacturing method of the regenerated pigment aggregate which uses deinking froth is explained in full detail.

1. Flocking and dehydration Normally, deinking floss has a moisture content of about 95 to 98% by mass, and a floc is formed by adding a flocculant to perform dehydration treatment. The dehydration process can be performed in one or more stages, but if the floc is solidified, it causes firing unevenness in the second firing step, which is a subsequent process. It is preferred to dehydrate to the extent.

2. Drying / classification The dehydrated product is dried in advance. As the drying means, known drying means such as hot air drying can be used, but hot air drying means which can be loosened while drying the deinking floss and further can be classified by specific gravity can be most preferably used.

  Specific examples of the hot air drying means that can be suitably used include hot air drying by blowing hot air with hot air blowing means provided below the impeller equipment while loosening the dewatered paper froth with a loosening equipment such as an impeller. Drying and classification can be performed by discharging the papermaking floss having a low specific gravity out of the loosened and dried papermaking floss from a take-out port provided at the upper part of the hot air drying means.

  As a suitable means for classification of the deinked floss that has been dried, classification by a cyclone can be employed.

3. Baking The dried and classified deinking floss is then sent to the first baking step. In the first firing step, it is important to adjust the unburned rate to be 10% by mass or more and less than 15% by mass. By setting the unburned rate to 10% by mass or more, it is possible to impart porosity to the particles in the subsequent firing in the second firing step. Furthermore, by setting the unburned ratio to less than 15% by mass, it becomes possible to prevent the particles from being hardened by over-baking due to self-combustion in the next second baking step.

  Firing is preferably performed at 650 ° C. or less, and in particular, in order to avoid a decrease in whiteness due to residual carbon, it is preferable to perform the steps in a range of 450 to 650 ° C. When calcination is performed at a high temperature exceeding 650 ° C., calcium carbonate is decomposed to become calcium oxide, and the inorganic substance may be melted to become inorganic particles having extremely high hardness and low porosity. In addition, since calcium oxide is water-soluble, it dissolves when added in the paper making process, and there is a possibility that, for example, chemical effects such as a sizing agent may be hindered.

  The regenerated pigment aggregate of the present embodiment contains 90% by weight or more of the above porous raw material, and this porous raw material contains an oxide as a particle component in the elemental analysis of the coated paper surface by an X-ray microanalyzer. In conversion, aluminum, silicon, and calcium in a weight ratio of 8-40: 10-40: 20-82, preferably in a weight ratio of 9-30: 10-30: 40-82, more preferably It is included in a weight ratio of 9-20: 9-20: 60-82.

  In the first firing step and the second firing step, as a method for adjusting to the ratio of the present invention, the main point is to adjust the raw material composition in the deinking floss, but the drying / classifying step, the first firing step, In the second firing step, it is also possible to adjust the coating floss and the adjustment step floss, which have a clear origin, by means such as spraying or the like, or by means including the incinerator scrubber lime.

  For example, neutral papermaking wastewater sludge and coated paper manufacturing process wastewater sludge are used to adjust calcium in the regenerated pigment aggregate, and a large amount is added as an opacity improver to adjust silicon. Newspaper manufacturing wastewater sludge can be appropriately used for adjustment of aluminum. Papermaking wastewater sludge such as acidic papermaking system that uses sulfuric acid band or wastewater sludge in high quality papermaking process that often uses talc can be used.

  As a means to make the total inclusion ratio of aluminum, silicon and calcium in terms of oxides 90% by weight or more, the manufacturing equipment process using an iron-free coagulant used for the coagulation treatment of the drainage sludge is iron. It can be adjusted by designing or lining with other materials, preventing iron from being mixed into the system due to wear, etc., and installing and removing high magnetic materials such as magnets in the drying / classifying equipment. In particular, it is preferable to selectively remove iron, because it becomes a causative substance for decreasing whiteness due to oxidation.

4). Dissolution / Pulverization The inorganic materials fired in the first firing step and the second firing step have irregular particle sizes for use in the papermaking or coating steps, and as such, there is a problem in using them as pigments.

  In the use for pigment applications, it is necessary to make the particle size uniform and fine, but as a result of earnest investigation on the optimum particle size and pigment diameter for the pigment application etc. in the regenerated pigment aggregate based on the present invention In the regenerated pigment aggregate of this embodiment, it is preferable that the primary particles have an average particle diameter of 0.01 to 0.1 μm, and the secondary particles in which the primary particles are aggregated have an average particle diameter of 0.1 to 10 μm. I found out.

  The regenerated pigment aggregate of this embodiment preferably has an oil absorption of 30 to 100 mL / 100 g measured according to the method described in JIS K 5101. When used as an internal additive in a papermaking process, the average particle diameter Is 0.1 to 10 μm, and when used as a pigment in the coating process, the average particle size is preferably adjusted to 0.3 to 5 μm.

In the present invention, the regenerated pigment aggregate is preferably treated by the above-mentioned drying / classification / calcination method so that particles of 40 μm or less are already 90% or more before pulverization. This makes it possible to perform a one-stage pulverization process by a wet process without performing a multi-stage pulverization process such as the pulverization of large particles by dry pulverization and the atomization by wet pulverization which are generally performed conventionally. Thereby, the peak height of the average particle diameter in the differential curve of the particle size distribution by the Coulter counter method can be set to 30% or more. Furthermore, calcium, silicon and aluminum in the raw material sludge can be converted into oxides in an amount of 30 to 82: By adjusting the weight ratio of 9 to 35: 9 to 35, the pore volume of the regenerated pigment aggregate is 0.15 to 0.60 cc / g, the pore surface area is 10 to 25 m ² / g, and the pore radius is It can be 300-1000 Angstroms.

  When clay is used as the other pigment, an equal amount of calcium carbonate and clay blended on a weight basis can be used as a standard pigment, but the weight basis blending ratio of heavy calcium carbonate and clay is When it is set within the range of 3: 7 to 7: 3, it is possible to obtain excellent printing glossiness, excellent operability, and produce a coated paper for printing at a lower cost. Particularly preferred.

  The average particle diameter of the regenerated pigment aggregate in the upper coating layer (outermost layer coating layer) 3 is set within a range of 0.1 to 10 μm, and the regenerated pigment in the upper coating layer 3 The average particle diameter of the aggregate is smaller than the average particle diameter of all the pigments in the upper coating layer 3. Since the average particle size of the pigment is set in this way, the relatively soft regenerated pigment aggregate is flatly combined with the shape of the other pigment in the upper coating layer 3 in the flattening treatment, and the upper coating derived from the pigment is applied. Irregularities and undulations on the surface of the work layer 3 are reduced. Therefore, the surface of the upper coating layer 3 can be made even more flat.

  Various conventionally known cationic binders are used as the cationic binder to be blended in the upper coating solution, and styrene / butadiene latex is particularly preferably used. In addition to cationic binders, starches such as oxidized starch, cationic starch, dextrin, synthetic resin adhesives such as polyvinyl alcohol (PVA), other adhesives such as casein, soy protein, and proteins such as synthetic proteins May be appropriately blended.

  Among various types of styrene-butadiene latex, it is a latex that does not contain acrylonitrile as a monomer component or is set to 10% by weight or less, and has a glass transition temperature (Tg) of −30. Those having an average particle diameter of 100 to 170 nm and a gel content of 80 to 90% at ˜0 ° C. are preferable. This is because latex containing a large amount of acrylonitrile as a monomer component easily yellows in the surface treatment process, and also easily yellows over time.Therefore, there is a problem in weather resistance, which causes variations in color tone in the final product. This is because there is a tendency to end up. However, the inclusion of acrylonitrile as a monomer component has the advantage that the required surface hardness can be imparted to the coated paper for printing while reducing the amount of latex in the coating liquid, and the printing gloss is increased. Therefore, in order to obtain these advantages, a small amount of 10% by weight or less may be included. Considering these, latexes having an acrylonitrile content of 1 to 10% by weight, more preferably 3 to 8% by weight, are more preferably used. In addition, such a predetermined latex can be produced by appropriately using a monomer component such as butadiene, acrylonitrile, styrene, acrylic acid, butylacrylic acid, methacrylic acid, methyl methacrylic acid, or vinyl acetate. it can.

  The reason why the latex has a glass transition temperature (Tg) in the range of -30 to 0 ° C is as follows. That is, when the glass transition temperature (Tg) exceeds 0 ° C., the stickiness resistance deteriorates and the operability tends to deteriorate. More specifically, when the content of acrylonitrile as a monomer component is large, it is possible to suppress the deterioration of stickiness resistance even if the glass transition temperature (Tg) is high, but it is not contained in acrylonitrile or acrylonitrile. This is because, since the latex is contained in a small amount, it is difficult to suppress the deterioration of stickiness resistance unless the glass transition temperature (Tg) is lowered. On the other hand, even if the glass transition temperature (Tg) is lower than −30 ° C., there is almost no difference in the effect of improving the stickiness resistance compared to the case of −30 ° C. For this reason, the glass transition temperature (Tg) is preferably set within the above range. A latex film was prepared at a glass transition temperature (Tg) of 20 ° C. and 65% (relative humidity), and 20 mg of that was measured with a differential scanning calorimeter (DSC) at a rate of temperature increase of 5 ° C./min and a measurement temperature of 0 to It can obtain | require from the characteristic curve obtained at 100 degreeC.

  Further, the latex having an average particle diameter in the range of 100 to 170 nm is preferable for the following reason. That is, if the average particle diameter is less than 100 nm, the coatability tends to be reduced and the covering property tends to deteriorate, and conversely if the average particle diameter exceeds 170 nm, sufficient adhesive strength and surface strength cannot be obtained, This is because the stickiness resistance tends to deteriorate. In other words, when the average particle size is within the above range, there are advantages that adhesive strength and surface strength necessary for a coated paper for printing can be obtained and good coating properties can be secured. The average particle size is diluted so that the concentration is 0.05 to 0.2%, the absorbance at a wavelength of 525 nm of each diluted sample is measured, and a calibration curve prepared in advance is used. Can be measured.

The reason why the latex gel content is in the range of 80 to 90% is preferable for the following reason. That is, when the gel content is less than 80%, there is a tendency that the operability is deteriorated due to insufficient surface strength. On the other hand, even if the gel content is higher than 90%, there is almost no difference in the effect of improving the stickiness resistance compared to the case of 90%. And the gel content is an index of adhesive strength, and by setting within a high range of 80 to 90%, even if acrylonitrile that imparts surface strength to the coated paper for printing is not contained or contained in a small amount, It becomes possible to ensure the required surface strength. The gel content is a value calculated by the following mathematical formula (1).
Gel content (%) = (dry film weight-toluene soluble weight) × 100
/ Dry film weight (1)
Here, the dry film weight is the weight of a dry film obtained by spreading about 0.3 g of latex thinly on a slide glass and drying it to a film with a dryer at 50 ° C. The toluene soluble weight means that the obtained dry film is immersed in about 50 mL of toluene for 24 hours, filtered through a glass filter, separated into a filtrate and a filtrate, and then the filtrate is dried at 105 ° C. It is the value which dried with the machine and measured the weight of toluene soluble part.

  And it is preferable that the mixing | blending ratio of the said predetermined latex is set in the range of 8-15 weight part with respect to 100 weight part of pigments. That is, if the blending amount is too small, the adhesive strength and surface strength required for the coated paper for printing are insufficient, and the user tends to cause picking troubles (peeling of the coating layer) when printing. Because. On the contrary, if the blending amount is too large, the absolute amount of acrylonitrile in the coating liquid increases, which tends to cause problems such as deterioration in weather resistance and high production costs. In other words, by setting the blending ratio of the predetermined latex within the above range, it is possible to obtain a coated paper for printing excellent in weather resistance while ensuring the necessary minimum adhesive strength and surface strength. it can. However, it goes without saying that other adhesives may be used in combination with the predetermined latex to increase the adhesive strength and surface hardness. In particular, it is preferable to use esterified starch such as urea phosphate esterified starch and carbamic acid starch together with a predetermined latex. The blending ratio of the esterified starch is preferably set in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the pigment.

  In addition to the above-mentioned components, the coating solution includes conventional acrylic acid / acrylamide copolymers, dispersants, thickeners, lubricants, antifoaming agents, water resistance agents, colorants, pH adjusters, and the like. Various known auxiliaries can be appropriately blended according to the purpose of use and needs. In particular, the acrylic acid / acrylamide copolymer is preferably blended within a range of 0.01 to 0.1 parts by weight with respect to 100 parts by weight of the pigment. The amount of acrylic acid / acrylamide copolymer added to the outermost coating layer varies depending on the coating method, coating speed, viscosity before adding the compound, etc., but the solid content is 100 parts by weight of pigment. The range of 0.01 to 0.1% by weight is preferable, and the range of 0.04 to 0.08% by weight is particularly preferable. When the amount of the compound added is less than 0.01% by weight, the thickening effect is insufficient and a uniform surface shape cannot be obtained. When the addition amount exceeds 0.1% by weight, the thickening effect becomes excessive, and the coating solution exhibits a remarkable spinnability, so that the operability deteriorates and the stretching in the coating becomes unstable. A surface shape cannot be obtained.

  The printing coated paper T according to the present embodiment can be manufactured, for example, as follows. That is, first, after preparing the paper substrate 1, the lower coating solution, and the upper coating solution, the lower coating solution is applied to both sides of the paper substrate 1 with a predetermined coating amount. Here, the coating treatment can be performed using various known coating apparatuses such as a blade coater, a bar coater, a roll coater, an air knife coater, a reverse roll coater, and a curtain coater. Next, drying is performed by various known heating and drying methods such as hot air heating, steam heating, infrared heater heating, gas heater heating, and electric heater heating. In addition, about drying conditions, it adjusts suitably according to a heat drying system, the mixing | blending of the lower side coating liquid, etc. In addition, after the drying process, a smoothing process that smoothes the surface by crushing fine irregularities generated during coating or drying using various known smoothing processing apparatuses such as a thermal soft calender and a super calender. You may perform as needed. Thus, the lower coating layer 2 having a thickness of about 5 to 25 μm can be formed. Subsequently, on the lower coating layer 2 formed on both surfaces of the paper substrate 1, the upper coating liquid is applied in a predetermined amount in the same manner, followed by drying. By performing the smoothing treatment, an upper coating layer (outermost layer coating layer) 3 having a thickness of about 5 to 25 μm is formed. In addition, an appropriate method is employ | adopted for a coating process, a drying process, and a smoothing process according to the mixing | blending of the upper side coating liquid, etc. Thus, the coated paper for printing T according to the present embodiment can be obtained.

  The coated coated paper T manufactured as described above and manufactured by the manufacturing method according to the present embodiment is oxidized into its particle constituents in the elemental analysis by the X-ray microanalyzer on the coated paper surface. Using a coating liquid containing a regenerated pigment aggregate containing aluminum, silicon, and calcium in an inclusion ratio of 8 to 40:10 to 40:20 to 82 in terms of physical properties, the printability is greatly increased. Since the affected upper coating layer 3 is formed, the occurrence of cracks and the like of the coating layer is suppressed while ensuring excellent cushioning properties, and the printability is excellent. Moreover, since the regenerated pigment aggregate which uses the deinking floss discharged | emitted from a used paper processing process as a main raw material is utilized, it can contribute to environmental conservation.

  In addition, this invention is not limited to the said embodiment. For example, the lower coating layer 2 and the upper coating layer 3 may be formed on only one side of the paper substrate 1 instead of both sides. Further, the coating layer is not limited to two layers, that is, the lower coating layer 2 and the upper coating layer 3, and may have a multilayer structure of more than that. Moreover, the layer of only the upper side coating layer 3 in which the lower side coating layer 2 does not exist may be sufficient. In that case, in the elemental analysis by the X-ray microanalyzer on the coated paper surface, the outermost layer is composed of 8 to 40:10 to 40:20 to aluminum, silicon, and calcium in terms of oxides as the particle constituents. It is formed with a coating liquid containing regenerated pigment aggregates contained in an inclusion ratio of 82. Moreover, the coated paper for printing by the manufacturing method of this invention can be used as various printing papers, such as offset printing.

  Hereinafter, the present invention will be described in more detail with reference to examples in which two coating layers are provided, and examples and comparative examples. However, the present invention is not limited to these examples.

Example 1
First, a regenerated pigment aggregate was produced according to Example 1 described in JP-A-2002-275785. That is, first, raw materials (DIP froth and first settling sludge) were prepared and then dehydrated to obtain a dehydrated product. Subsequently, it was fired at 450 ° C. for 2 hours under low oxygen conditions, and further fired at a firing temperature of 650 ° C. for 2 hours. Thereafter, the fired ash obtained was pulverized by a pulverizer and classified to obtain a regenerated pigment aggregate having an average particle size of 5 μm.

  Next, 20 parts by weight of regenerated pigment aggregates as pigments with respect to 100 parts by weight of all pigments (all pigments in the coating liquid for forming the outermost layer coating layer), heavy calcium carbonate (average particle diameter of 1.4 μm) ) Is blended with 50 parts by weight based on 100 parts by weight of the total pigment, and 30 parts by weight of clay (average particle size 0.8 μm) with respect to 100 parts by weight of the total pigment, and styrene-butadiene latex ( 5 parts by weight of acrylonitrile content: 5% by weight, Tg: −10 ° C., average particle size: 130 nm, gel content: 85%) is added to 100 parts by weight of the total pigment, and urea phosphate starch is added to the total pigment 100. 5 parts by weight with respect to parts by weight, 0.08 parts by weight of acrylic acid / acrylamide copolymer with respect to 100 parts by weight of the total pigment and dispersed, and an upper coating liquid having a solid content concentration of 50% ( For forming the outermost coating layer Coating solution) was prepared.

  On the other hand, 100 parts by weight of calcium carbonate with an average particle diameter of 11 μm is blended as a pigment, 0.1 part of Aron T-40 manufactured by Toa Gosei Chemical Co., Ltd. as a polyacrylic acid dispersant, and Asahi Kasei as a styrene-butadiene latex. 9 parts of L1301 manufactured by Co., Ltd., 1.0 part of MS4600 manufactured by Nippon Shokuhin Kako Co., Ltd. as phosphate esterified starch, and 0.4 part of calcium stearate as a lubricant are mixed to a solid content concentration of 60. % Lower coating solution was prepared.

Subsequently, a lower coating solution, dried and coated with a coating amount of 8 g / m ² on both surfaces of a basis weight of 62 g / m ² base paper (paper substrate), the lower coating on both surfaces of the base paper A work layer (lower layer) was formed. Subsequently, the upper coating solution was applied onto each lower coating layer at a coating amount of 8 g / m ² and dried to form an upper layer (outermost layer coating layer). Thus, the intended coated paper for printing was produced. The specifications of Example 1 are shown in Tables 1 and 2.

(Examples 2 to 10)
Tables 1 and 2 show the specifications of each example. Except for the points shown in these tables, the coated paper for printing of Examples 2 to 10 was produced in the same manner as in Example 1.

(Comparative Examples 1-4)
Tables 1 and 2 show the specifications of each example. Except for the points shown in these tables, the coated paper for printing of Comparative Examples 1 to 4 was produced in the same manner as in Example 1.

  In addition, the meaning of each item in Table 1 and Table 2 is as follows.

  The number of parts (C) is the weight part of the regenerated pigment aggregate with respect to 100 parts by weight of the total pigment (total pigment in the outermost coating layer), and the number of parts (A) is the total pigment (in the outermost coating layer). The total pigment) is 100 parts by weight of heavy calcium carbonate, and the number of parts (B) is the weight of the clay with respect to 100 parts by weight of the total pigment (total pigment in the outermost coating layer). The cationic binder varieties SBR means styrene / butadiene latex, the acrylonitrile content is the content (% by weight) of acrylonitrile in the styrene / butadiene latex, and the gel content is the above formula. This is the value (%) obtained in (1). Although not shown in the table, the blending amount of the styrene-butadiene latex as the cationic binder was 5 parts by weight in all of Examples 1 to 10 and Comparative Examples 1 to 4 (based on 100 parts by weight of the total pigment). 5 parts by weight). Moreover, the number of parts of the esterified starch in the table refers to parts by weight with respect to 100 parts by weight of the total pigment in the outermost coating layer. Furthermore, the number of parts of the acrylic acid / acrylamide copolymer is also part by weight with respect to 100 parts by weight of the total pigment in the outermost coating layer.

  Moreover, the average particle diameter or average particle diameter in the table means a volume load average particle diameter measured with a Microtrac 7995-30 SPA type manufactured by Leeds and Northrop.

The quality evaluation method is as follows.
[Glossiness of white paper]: Measured at an angle of 75 degrees according to JIS P 8142.

[Glossiness in heavy-duty printing]: A sample was printed on a Roland offset printing machine, left at room temperature all day and night, and the sample was printed at 60 degrees on a four-color overprint solid printing section of black, magenta, cyan, and yellow. Gloss was measured at an angle. (unit:%).

[Ink fillability]: Printing was performed with a commercially available oxidation polymerization type printing ink using an RI printer (Ming Seisakusho), and the uniformity and density of the printed surface were visually determined by a four-step evaluation according to the following criteria. A: Very good, B: Excellent, B: Somewhat problematic, B: Some problem. The allowable limit is Δ or more. Note that “◯ to Δ” means that ○ evaluation and Δ evaluation are mixed.

[Coater operability]: The topcoat coating liquid was smeared on a paper substrate using a blade coater, the occurrence of streaks in the coater head was observed, and visually judged by a four-step evaluation. The allowable limit is Δ or more. The following criteria were evaluated using the streak, scratch and fluidity of the coating liquid during blade coating as indicators. A: Very good, B: Good, B: Slightly inferior, X: Inferior Note that “◯ to Δ” means that ○ evaluation and Δ evaluation are mixed.

  As shown in the table, as a result of actually performing offset printing etc. on the coated paper for printing of each Example and Comparative Example, and evaluating each evaluation item comprehensively, the Example is higher than the Comparative Example became.

It is sectional drawing which shows typically the coated paper for printing manufactured with the manufacturing method which concerns on one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper base material 2 Lower side coating layer 3 Upper side coating layer (outermost layer coating layer)
T coated paper for printing

Claims (3)

In the method for producing a coated paper for printing in which a coating layer containing a pigment and a cationic binder as essential components on at least one side is formed,
In the pigment, the main raw material is deinking floss discharged from the waste paper processing step,
The main raw material is obtained through a dehydration step, a drying step, a firing step and a pulverization step,
Printing element characterized in that it contains at least a regenerated pigment aggregate having the following composition in elemental analysis by X-ray microanalyzer on the surface of the coated paper, and coats the regenerated pigment aggregate. Production method of coated paper:
(composition)
In the elemental analysis by the X-ray microanalyzer of the coated paper surface, aluminum, silicon, and calcium are converted into oxides as the particle constituents of the regenerated pigment aggregate in the range of 8-40: 10-40: 20-82. It is included in the inclusion ratio.   2. The production method according to claim 1, wherein in the regenerated pigment aggregate, a total inclusion ratio of the aluminum, the silicon, and the calcium in terms of oxide is 90% by weight or more of a particle constituent component. The average particle diameter of the regenerated pigment aggregate in the coating layer is set within a range of 0.1 to 10 μm,
The average particle size of the regenerated pigment aggregate in the coating layer is set to be smaller than the average particle size of other pigments in the coating layer. Manufacturing method.

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