JP2008002023A - Coated paper for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated paper for printing, which has whiteness and appearance caused by foreign materials comparable to those of conventional coated paper composed mainly of chemical pulp even if a large amount of DIP produced mainly from waste newspaper or waste magazine paper is blended, and sufficiently meets the recent requirements of the lowering of the grade and improvement of the quality of coated paper. <P>SOLUTION: The coated paper for printing, which has a coating composition composed mainly of a pigment and an adhesive and applied to a base paper, uses the base paper contains 5-100 mass% waste paper pulp produced from waste newspaper and/or waste magazine paper and has an ISO whiteness of 78-95% and a number of dirt materials per 0.05-5.0 mm<SP>2</SP>of 5-200 pieces/m<SP>2</SP>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a coated paper for printing in which used paper pulp is blended with base paper and has high whiteness and little dirt.

For coated paper for printing, a pigment coating layer consisting mainly of a white pigment and an adhesive is formed on the surface of the base paper, and smoothing treatment is performed with a super calender or gloss calender depending on the target product to improve printability. Art paper, coated paper, finely coated paper, and the like are typical examples. In recent years, the way consumers think about paper selection has changed. Conventionally, consumers who have used art paper are A2 coat, consumers who have used A3 coat are fine coated paper, and so on. The grade reduction in the product type is progressing. For this reason, the thickness of the coating layer is decreasing, the base paper hiding property is lowered, and the influence of the base paper quality on the appearance quality of the coated paper is greater than before. While product grades are becoming lower grades, consumer quality requirements are still high, and high quality of each grade is desired.

Another demand from consumers is the response to environmental problems. So far, the base paper of coated paper has been mainly used with 100% chemical pulp as the base paper for coated paper. However, in recent years, the use of waste paper pulp has become an important theme from the viewpoint of maintaining the global environment, and deinked pulp regenerated from waste paper (hereinafter referred to as “DIP”) is also frequently used in the coated paper market for printing. There is a demand for products that have been made.

Of the waste paper generated in Japan, the largest amount of waste paper is used in newspapers and magazines. Conventionally, paper manufacturers have produced DIPs that use these waste papers as raw materials, and have mainly used intermediate and lower grade papers.

On the other hand, coated paper for printing using DIP-rich base paper made from used newspaper and magazine waste paper is inevitably whiteness compared to coated paper using 100% chemical pulp base paper. However, there was a problem that there were many impurities.
Moreover, these difficulties become more apparent as the coated paper has a thinner coating layer. For this reason, in the recent trend toward lower grades in terms of product varieties and higher quality in terms of quality, it has become difficult to mix multiple DIPs using old newspapers and magazines as raw materials.

As a method of obtaining high-quality printing paper in terms of whiteness and impurities using waste paper as a raw material, it contains waste paper pulp, and has a whiteness of 70% or more, and a single area of 0.005 mm ² or more. Has been proposed in which the total area is 0.15 mm ² or less per 10 cm ^{2 of} transfer paper (see, for example, Patent Document 1). However, since the coated paper has a certain degree of concealment, a coarse contaminant of 0.05 to 5.0 mm ² is more important in terms of appearance quality than such a fine impurity. There is no provision for area contamination. Further, in the examples, when 60% of used newspapers were blended, the total area of the impurities was exceeded, but no method for effectively reducing the wastes of waste paper pulp was presented.

In addition, a method has been proposed in which recycled pulp is used as a raw material, and the remaining ink area of the base paper surface is 0.03 mm ² or more is defined as 80 mm ² / m ² or less (see, for example, Patent Document 2). ). However, even in this method, a method for effectively reducing the waste of used paper pulp used has not been proposed.

While 10% by mass or more of the pulp constituting the base paper of the coated paper for printing is recycled pulp made from old magazine paper, the area of impurities on the surface of the coated paper for printing is set to 5. A method of 0 mm ² / m ² or less has been proposed (see, for example, Patent Document 3). However, in this method, no method for reducing impurities in the waste paper is presented except for adjusting the blending amount.
For this reason, DIP having a quality equivalent to or equivalent to that of chemical pulp with respect to impurities and whiteness has been desired using waste newspaper and magazine waste as raw materials, but it has been extremely difficult to produce such DIP. .

As a conventional DIP manufacturing technique with little dirt and high whiteness, there is a technique in which bleaching is performed with an oxidizing bleaching agent at a pulp concentration of 25% or more, and further bleaching at a pulp concentration of 8 to 20% with thiourea dioxide. (For example, refer to Patent Document 4). According to the embodiment of this technique, a whiteness as high as 81% is obtained, but the dispersion effect of the dirt is not specified.

In addition, this technology uses a mixer that has a feed blade and a return blade on the uniaxial rotor collecting surface, and a sufficient gap between the stator blade and each blade, such as a miker processor, for mixing hydrogen peroxide. In such a mixer, the actual power load obtained by subtracting the idling power load at a high speed gives a weak mechanical force of about 5 to 25 kW / t, and a dart reduction effect cannot be expected. Further, since thiourea dioxide bleaching requires 10 to 90 minutes, there is a problem that a large storage device or the like is required.

Further, after adding an oxidizing bleaching agent with a pulp concentration of 20 to 35%, mechanically stirring and oxidizing bleaching, the fiber suspension after bleaching is made with a pulp concentration of 10 to 30% and reducing bleaching. After adding an agent, there is one that is mechanically stirred and subjected to reduction bleaching (for example, see Patent Document 5). However, according to the embodiment of the present technology, the effect is not obvious, and it is possible to increase the whiteness by bleaching twice, but the double treatment by the disperser can sufficiently reduce the dirt. I can't.

In addition, in the ink peeling process, a technique for adding thiourea dioxide and diluting the pulp immediately after treatment using a kneader such as a kneader at 100 to 1000 rpm and a treatment time of 1 to 30 minutes is disclosed. (For example, refer to Patent Document 6). However, according to the embodiment of the present technology, the whiteness of the obtained waste paper pulp is 70%, which is not different from the conventional DIP, and the whiteness increase due to thiourea dioxide is as low as 4.5 points. Furthermore, the disc type is not suitable because it is not aimed at reducing dirt.

In addition, techniques using hydrogen peroxide and thiourea dioxide in combination have been disclosed (see, for example, Patent Documents 7 to 9), but all are methods for increasing whiteness and are not effective as a measure for reducing darts. Absent.
Japanese Patent No. 2887003 Japanese Patent Laid-Open No. 6-35221 JP 2004-124279 A Japanese Patent No. 3098021 JP 2005-281914 A JP 2002-69877 A JP 7-61439 A JP-A-7-112658 JP-A-9-64333

In other words, the present invention is similar to conventional coated paper mainly made of chemical pulp in whiteness and appearance quality even if it contains a lot of DIP mainly made from newspaper waste and magazine waste paper. The purpose of this paper is to provide coated paper for printing that can satisfactorily meet the demands for lowering the grade and quality of coated paper.

In order to solve the above problems, the present inventors have intensively studied, and as a base paper of the coated paper for printing, contain 5 to 100% by mass of waste newspaper and / or magazine waste paper as a fiber component, and have an ISO whiteness of 78 It was found that the purpose can be effectively achieved by using a base paper having a dart count of 0.05 to 5.0 mm ² and 5 to 200 mm / m ² .

That is, the present invention includes the following inventions.
(1) A coated paper for printing in which a coating composition mainly composed of a pigment and an adhesive is coated on a base paper, and contains 5 to 100% by weight of waste paper pulp made from newspaper waste paper and / or magazine waste paper. And a coated paper for printing using a base paper having an ISO whiteness of 78 to 95% and a dart number of 0.05 to 5.0 mm ² of 5 to 200 / m ² .

(2) Waste paper pulp is added with 0.5 to 5% hydrogen peroxide, treated at 40 ° C to 90 ° C for the first time with a low-speed, high-concentration shaft type disperser, and aged for 1 to 6 hours. After that, the second treatment with a low-speed, high-concentration shaft type disperser is performed, and further 0.1 to 2% of thiourea dioxide is added, and the treatment with a disk-type disperser is performed at 90 to 140 ° C. The coated paper for printing according to (1), which is a waste paper pulp produced by a waste paper pulp production process characterized by

The coated paper for printing of the present invention contains 5 to 100% by weight of waste paper pulp made from newspaper waste paper and / or magazine waste paper, has an ISO whiteness of 78 to 95%, and 0.05 to 5.0 mm ^2. By using a base paper with a dart count of 5 to 200 / m ² , the quality and quality of the latest coated paper is reduced and quality is comparable to conventional coated paper made from chemical pulp. Coated paper for printing that can respond satisfactorily to the demand for higher quality in terms of surface was obtained.

In the appearance quality of the coated paper, the coating layer has a certain concealment concealing performance according to its thickness, so that it is less than the amount of fine impurities less than 0.05 mm ^{2 in} the base paper. The appearance quality is governed by the number of relatively coarse impurities in the range of 05 to 5.0 mm ² . Therefore, the purpose can be achieved by reducing to a specific range of contaminants in the base paper, and further, even if used paper pulp is blended by increasing the whiteness to 78-95%, the conventional chemical pulp It is estimated that compared to 100% coated paper, coated paper with inferior quality can be obtained.

As the most effective method for increasing the whiteness of DIP made of used newspaper and magazine paper as a raw material and reducing impurities, treatment with three dispersers is preferred. The treatment by the three dispersers applied to the used paper pulp manufacturing method of the present invention is desirably performed twice in this order by the shaft type disperser and once by the disc type disperser in this order. Even with other combinations, the effect of reducing the dirt can be obtained by three disperser treatments, but when aiming for both high whiteness and low dirt, in order to suppress ink kneading and overdispersion, this order It is desirable to process. Further, there is no problem even if the above-described known steps are applied before and / or during the three times of processing and / or after the processing.

The most preferable three times of dispersion treatment is the addition of 0.5% to 5% hydrogen peroxide, and the first low-speed / high-concentration shaft type treatment is performed at 40 ° C to 90 ° C. After aging for 6 hours, perform treatment with a low-speed, high-concentration shaft type disperser for the second time, add 0.1 to 2% thiourea dioxide, and use a disc-type disperser at 90 to 140 ° C. We think that both reduction of impurities and high whiteness can be achieved by processing.

It is preferable to perform hydrogen peroxide bleaching after the treatment by the low-speed and high-concentration shaft type disperser, which is the first dispersion treatment.
The amount of hydrogen peroxide added in the hydrogen peroxide bleaching step is 0.5 to 5% by mass with respect to the mass of the absolutely dry pulp. When the amount is less than 0.5% by mass, a sufficient bleaching effect cannot be obtained. Moreover, even when more than 5 mass% is added, it is difficult to further improve the whiteness. Furthermore, the system pH after bleaching is preferably 8 to 13.5. If the pH is less than 8, the bleaching effect is reduced due to a decrease in oxidation ability. If the pH is 13.5 or more, the activity of hydrogen peroxide is increased, and hydrogen peroxide is consumed in a short time, which may cause so-called alkali burning. .

The bleaching time in the hydrogen peroxide bleaching step after the treatment by the low-speed / high-concentration shaft type disperser, which is the first dispersion treatment, is 1 to 6 hours. When bleaching for less than 1 hour, hydrogen peroxide cannot react sufficiently, and the bleaching effect is reduced. When bleaching for 6 hours or more, hydrogen peroxide is consumed unless the addition rate is excessive. Causes color development of lignin.

In the hydrogen peroxide bleaching step after the treatment by the first axial type disperser of the present invention, in addition to hydrogen peroxide, an alkaline chemical and a deinking agent may be used in combination. As alkaline chemicals, sodium hydroxide and sodium silicate are preferred.

The second dispersion treatment with a low-speed / high-concentration shaft type disperser is performed without dilution immediately after the hydrogen peroxide bleaching step. When diluted, it is difficult to apply a mechanical load, and the temperature is lowered and the ink peeling effect is lowered, which is not preferable.

The temperature at the time of the process by the disk-type disperser which is the third dispersion process of the present invention is 80 to 140 ° C. If the treatment is less than 80 ° C., sufficient dart reduction effect and bleaching effect of thiourea dioxide cannot be obtained. On the other hand, if it exceeds 140 ° C., yellowing of the pulp occurs, which is not suitable. Furthermore, in addition to thiourea dioxide, an alkaline chemical may be added. As the alkaline chemical, sodium hydroxide is preferable. The addition amount of thiourea dioxide is 0.1 to 2% by mass with respect to the mass of the absolutely dry pulp. If the addition is less than 0.1% by mass, a sufficient bleaching effect cannot be obtained. Moreover, even when more than 2% by mass is added, it is difficult to further improve the whiteness.

As the low-speed / high-concentration shaft type disperser here, a uniaxial or biaxial kneader type disperser is preferable. It has a rotary blade attached to a shaft-like rotor and a fixed blade attached to a casing, at a low speed of 50 to 300 rpm, a high treatment concentration of 20% to 50%, and a treatment temperature of room temperature to 100 ° C. To process. In the shaft type disperser, the frictional action between the fibers is the main, and the ink peeling and dirt dispersion occur.
A treatment concentration of 20% or less is not suitable because it is difficult to apply a mechanical load, and ink dispersibility / dirt dispersibility is lowered, and energy required for temperature rise is enormous. In addition, it is difficult to mechanically squeeze water to a treatment concentration of 50% or more.

In general, Nieding Disperser KD (trade name: manufactured by IH IFOIT Paper Technology), Disperser (trade name: manufactured by Aikawa Tekko Co., Ltd.), Disperser (trade name: product name: uniaxial kneader) ASEC), disperser (trade name: manufactured by Sanei Regulator Co., Ltd.), CCE type kneading machine (trade name: manufactured by Nihama Pump Manufacturing Co., Ltd.), kneader (product name: manufactured by Yamamoto Hyakuma Manufacturing Co., Ltd.) Further, as the biaxial kneader, those manufactured by Niihama Pump Mfg. Co., Ltd. and Yamamoto Hyakuma Mfg. Co., Ltd. are used, but are not limited to specific models. However, a so-called mica processor that performs agitation while applying a weak mechanical force at a processing concentration of 10 to 25%, a high speed of 1200 to 1800 rp, an actual power load of about 5 to 30 kW / t after subtracting the idling power load. Such a high-speed stirring device is not suitable in the present invention because a high dart reduction effect and a high peeling effect cannot be obtained.

Further, the disk type disperser is not particularly limited as long as it is a disk type disperser or a conical type disperser. Structurally similar to a disc refiner, but the disc plate has a different structure. Further, the conical type disperser has a rotating blade in a conical shape. Processing is performed at a rotational speed of 300 rpm to 2500 rpm and a processing concentration of 20% or more.
The difference from the shaft type disperser is that the ink and the dirt are dispersed mainly by the collision action of the fiber and the blade. Generally, as a disk-type disperser, a disperser HTD (trade name: manufactured by IH / IFOIT Paper Technology), a KRIMA hot dispersion facility (trade name: manufactured by Cellwood), etc. are used. As conical type dispersers, conical discs (trade name: manufactured by Aikawa Tekko Co., Ltd.), conical dispersion systems / HI pre-heaters / Optifiner dispersers (product name: manufactured by Metso SHI), etc. are used. It is not limited.

Regarding the effects of hydrogen peroxide and thiourea dioxide, hydrogen peroxide is aged under alkaline conditions in addition to whiteness increase due to the bleaching effect, so the pulp swells during aging and the adhesion with the ink relaxes, It is considered that high whiteness can be obtained because the effect of enhancing the ink peeling effect in the disperser is also obtained. Furthermore, in thiourea dioxide bleaching, it is considered that a high bleaching effect can be obtained because the reduction potential can be increased by treating at a high temperature of 80 to 120 ° C.

The reason why high whiteness was effectively achieved in this treatment is thought to be because hydrogen peroxide and thiourea dioxide were added in order. First, in hydrogen peroxide bleaching, in addition to the increase in whiteness due to the bleaching effect, aging under alkaline conditions, the pulp swells during aging, loosening adhesion with the ink, and the ink peeling effect in the disperser is enhanced. It is considered that high whiteness can be obtained. Furthermore, in thiourea dioxide bleaching, the reduction potential can be increased by processing at a high temperature of 90 to 140 ° C., and therefore, it is considered that a high bleaching effect can be obtained even in used newspapers and magazines. In addition, it is considered that a high ink peeling effect was obtained by processing with a shaft type disperser, which has a high ink peeling effect before and after aging, and that it was easy to remove in the post-process and high whiteness was obtained. ing.

Furthermore, the used paper pulp manufacturing process to which the present invention is applied is not particularly limited, and can be applied to an existing process in which known processes are combined. Specifically, for example, the present invention can be applied to an existing process in which any one of a disaggregation process, a dust removal process, a deinking process, a washing process, a concentration process, and a bleaching process, or all processes are combined. Furthermore, the order and the number of times of these existing processes are not limited. However, preferably the disaggregation process, dust removal process 1, deinking process 1, washing process 1, concentration process 1, dispersion process 1, bleaching process 1, dispersion process 2, deinking process 2, washing process 2, dust removal process 2, concentration It is desirable to process in order of the process 2, the dispersion | distribution process 3, the bleaching process 2, the washing | cleaning process 3, and the concentration process 3.

The disaggregation step is a wet disaggregation step in which raw paper and dilution water are added and the used paper is dissolved in a slurry state, and the solid content concentration during disaggregation is not particularly limited to 2 to 30%, so-called low concentration pulper, It is not limited to specific models such as high-concentration pulper and fiber flow.

The dust removal step is a step aimed at removing foreign substances such as pressure-sensitive adhesive, adhesive, pressure-sensitive adhesive tape, magazine back glue, vinyl tape, poly string, film, etc. contained in the slurry. Although there are so-called screens and cleaners, the dust removing process of the present invention is not limited to these, and various dust removing devices may be combined.

The first deinking step is a step of removing ink separated by a mechanical action and / or a chemical action in the disaggregation step and the dispersion step. As a known deinking device, there is a so-called flowator, but the present invention The deinking process is not limited to these, and various deinking apparatuses may be combined.

The previous washing step is a step of removing ink that has been peeled off by mechanical action and / or chemical action in the disaggregation step and the dispersion step. Known cleaning devices include so-called extractors and fall washers. The cleaning process of the invention is not limited to these, and various cleaning apparatuses may be combined.

The pre-concentration step is a step of removing ink and ash and dehydrating, and known concentrating devices include a so-called double nip thickener, screw press, disc thickener, valveless thickener, and the like. It is not limited to these, and various concentrators may be combined.

Waste paper pulp used for the base paper of the coated paper for printing of the present invention can be blended in an amount of 5 to 100% by mass in the total pulp. Since it is a pulp with few impurities and high whiteness, it can be compounded in a large amount, and preferably 50 to 100% by mass. In addition, the waste paper used as the main raw material of the present invention is a waste paper, magazine waste paper, miscellaneous paper, etc. containing a large amount of lignin and having a high yield in the waste paper treatment process. Flyer waste paper, Kent waste paper, colored waste paper, etc. are not preferred because they have high whiteness, but have a lot of dust that cannot be removed in the process, and contain a large amount of ash, resulting in a low yield and a small amount of generation. As pulp other than the used paper pulp used for the coated paper for printing of the present invention, LBKP (hardwood bleached kraft pulp), NBKP (conifer bleached kraft pulp), LBSP (hardwood sulfite pulp), NBSP (conifer sulfite pulp), etc. Any conventionally known chemical pulp can be used.

The coated paper for printing of the present invention has an ISO whiteness of 78 to 95%. A whiteness of less than 78% is not preferable because it gives an impression of medium quality paper. In addition, bleaching pulp with a whiteness higher than 95% consumes a lot of energy, which is not preferable.

As a pigment used in the coating layer of the printing coated paper of the present invention, kaolin, clay, calcium carbonate, aluminum hydroxide, zinc oxide, barium sulfate, which are used when producing a normal printing coated paper, White inorganic pigments such as titanium dioxide, calcium sulfate, silica, activated clay, talc, satin white and lake, and organic pigments such as plastic pigments are appropriately used.

The adhesive used together with the white inorganic pigment is not particularly limited. However, casein, soybean protein, synthetic protein and other proteins: conjugated diene polymer latex such as styrene / butadiene copolymer, acrylic Acrylic polymer latex such as acid ester and / or methacrylic acid ester polymer / copolymer, vinyl polymer latex such as ethylene / vinyl acetate copolymer, or these various polymer latexes with functional groups such as carboxyl groups. Alkali-soluble or alkali-insoluble polymer latex modified with a group-containing monomer: Synthetic resin adhesive such as polyvinyl alcohol, olefin / maleic anhydride resin, melamine resin: positive starch, oxidized starch, enzyme-modified starch, Starch such as thermochemically modified starch, etherified starch, esterified starch, cold water soluble starch Carboxymethylcellulose, coated paper for adhesives such as cellulose derivatives such as hydroxyethyl cellulose may be appropriately selected and used.

The blending ratio of the adhesive is about 5 to 25 parts by mass, more preferably about 10 to 20 parts by mass with respect to 100 parts by mass of the pigment in terms of solid content. In the pigment coating composition, a dispersant, a thickener, a water retention agent, a flow modifier, an antifoaming agent, a release agent, a water-resistant lubricant, a dye, a fluorescent whitening agent, and a pH adjuster as necessary. Various auxiliary agents such as an agent can also be appropriately blended.

Examples of the pigment coating composition prepared under the above conditions include a blade coater, an air knife coater, a roll coater, a reverse roll coater, a bar coater curtain coater, a die rod coater, a gravure coater, a Chanplex coater, and a gate roll coater. The coating is performed by an on-machine or off-coater provided with a known coating apparatus such as a size press. When finishing a coated paper with high glossiness, it is preferable to employ a blade coater, a rod blade coater or the like.

In this case, the solid content concentration of the pigment coating composition is generally about 40 to 75% by mass, but considering the operability, the range of 45 to 70% by mass is preferable. The coating amount of the pigment coated composition is per side 3 to 20 g / ^{m 2} approximately by dry weight, and preferably from 3 to 15 g / ^{m 2.} Incidentally, if it is less than 3 g / m ² , the printability becomes insufficient. On the other hand, if it exceeds 20 g / m ² , the texture of the paper itself is lost, leading to high costs.

The pigment coating layer is dried and then finished through a finishing device such as a super calender, a gloss calender, or a soft calender.

EXAMPLES Next, although this invention is demonstrated in detail based on an Example, an Example does not limit this invention at all. In this example, the percentage (%) means mass% except whiteness, and the chemical addition rate is expressed as mass% per dry pulp. The quality of the used paper pulp was evaluated by the pulp whiteness according to JIS P 8212 and the pulp contaminant evaluation method shown below, and the appearance of the coated paper for printing was evaluated.

<Contaminant evaluation method>
Using a paper dust measuring device (trade name: manufactured by Oji Scientific Co., Ltd.), both front and back surfaces of 10 A4 size base papers for coating were measured. The measurement result was converted to the number per 1 m ² of the base paper and used as the number of impurities.

<Appearance quality>
Evaluation was made in comparison with coated paper prepared in the same manner as in Example with 100% chemical pulp base paper.
○: No fading.
Δ: A small amount of foreign matter is observed, but there is no problem.
X: Many impurities and whiteness are low.

Example 1
Raw material of 100% used newspaper was charged into a high-concentration pulper and disintegrated. The raw material after disaggregation was diluted to 1%, and as a dust removal process, it was sequentially processed with a screen having a hole basket and a slit basket. Furthermore, after processing in the deinking process with an OK floatator (trade name: manufactured by Oji Engineering) and the cleaning process with an extractor, it is then concentrated to 25% in a concentration process with a valveless thickener and screw press. %, Caustic soda 2% and sodium silicate 2%, heated to 70 ° C., and used a disperser (trade name: manufactured by Aikawa Tekko Co., Ltd.) as a shaft type disperser for the first time. It was. The treated pulp was bleached for 3 hours while maintaining the temperature, and then a second dispersion treatment was performed using a disperser (trade name: manufactured by Aikawa Tekko Co., Ltd.) as a shaft type disperser.

The pulp after the dispersion treatment is diluted to 1%, and further processed by a deinking process using an OK floatator (trade name: manufactured by Oji Engineering), a washing process using an extractor, and a dust removing process using a screen of a slit basket. It concentrated to 35% by the concentration process by a screw press. Add 1% thiourea dioxide (FAS) and 0.5% caustic soda to the concentrated pulp, raise the temperature to 110 ° C, and use a hot disperser (trade name: manufactured by KRIMA) as a disk-type disperser. A third dispersion process was performed. Furthermore, it was concentrated to 10% by a washing process using an extractor and a concentration process using a valveless thickener to obtain a finished waste paper pulp material having a whiteness of 81% and a foreign matter of 110 pieces / m ² . For the above-described disaggregation treatment, dust removal treatment, deinking treatment, and dehydration treatment, the above-described known apparatus for producing used paper pulp was used.
In addition, 50% of this finished waste paper pulp and 50% of LBKP (whiteness 85%), which has been whitened by multistage bleaching, are used as raw material pulp for papermaking, and the following fillers and papermaking chemicals are added to make paper stock. A base paper for coating having a basis weight of 95 g / m ² was produced by a net paper machine.

(Filler / Paper making chemicals) (Product name, manufacturer) (Amount added "% pulp" )
Filler (Precipitated calcium carbonate) 12%
Sizing agent (Fibrane 81, manufactured by NSC Japan) 0.02%
Starch (Ace K100, made by Oji Cornstarch) 0.8%
Acrylic amide polymer (Himoloc NR12MLS, made by Hymo) 0.005%
Fluorescent whitening dye (Brancohower BSU-PN, manufactured by Bayer) (2000PPm)

The following pigment coating solution (60%) was applied and dried on both sides of this coating base paper with a blade coater, and smoothed with a super calender (linear pressure 200 kg / cm) to prepare a coated paper for printing. . The coating amount was adjusted to 10 g / m ² (single side). Table 1 shows the whiteness and appearance quality of the coated paper for printing.

(Coating material) (Product name) (Manufacturer) (Blending amount)
Kaolin (UW-90) (Engelbird) 50 parts
Heavy calcium carbonate (self-made) 10 parts
Precipitated calcium carbonate (self-made) 35 parts
Titanium dioxide (FA 55W) (Furukawa Metal) 5 parts
Oxidized starch (Ace A) (Prince Corn Starch) 3 parts
SBR Latex (Latex L-1303) (Asahi Kasei) 10 parts
Dispersant (Aron F40) (Toa Gosei) 0.02 parts

Example 2
In Example 1, papermaking was carried out in the same manner as in Example 1 except that the ratio of waste paper pulp was 100%, and a coated paper for printing according to the present invention was obtained. The whiteness and appearance quality of the prepared coated paper for printing are shown in Table 1 as Example 2.

Example 3
In Example 1, paper was made in the same manner as in Example 1 except that waste paper in which the same amount of waste newspaper and magazine waste was mixed was used as a raw material to obtain a coated paper for printing according to the present invention. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Example 4
In Example 3, paper was made in the same manner as in Example 3 except that the ratio of waste paper pulp was 50%, and a coated paper for printing according to the present invention was obtained. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Example 5
In Example 1, 1% thiourea dioxide (FAS) and 0.5% caustic soda were added, the temperature was raised to 110 ° C., the third dispersion treatment was not carried out, and the procedure was carried out except for holding for 30 minutes. Papermaking was carried out in the same manner as in Example 1 to obtain a coated paper for printing according to the present invention. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Example 6
In Example 1, except that the coating amount was adjusted to 5 g / m ² (single side), paper was made in the same manner as in Example 1 to obtain a coated paper for printing according to the present invention. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Example 7
In Example 6, paper was made in the same manner as in Example 1 except that the ratio of the used paper pulp was 100%, and a coated paper for printing according to the present invention was obtained. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Comparative Example 1
In Example 1, a coated paper for printing was obtained in the same manner as in Example 1, except that thiourea dioxide (FAS) was not added and the waste paper pulp was not subjected to the third dispersion treatment. . The finished waste paper pulp had a whiteness of 72% and the number of contaminants was 250 pieces / m ² . Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Comparative Example 2
In Comparative Example 1, paper was made in the same manner as in Comparative Example 1 except that the ratio of waste paper pulp was 100%, and a coated paper for printing of Comparative Example was obtained. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Comparative Example 3
In Comparative Example 1, paper was made in the same manner as in Comparative Example 1 except that waste paper in which the same amount of waste newspaper and magazine waste was mixed was used as a raw material to obtain a coated paper for printing of Comparative Example. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Comparative Example 4
In Comparative Example 3, paper was made in the same manner as in Comparative Example 1 except that the mixing ratio of the used paper pulp was set to 100% to obtain a coated paper for printing of Comparative Example. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Comparative Example 5
In Comparative Example 1, paper was made in the same manner as in Comparative Example 1 except that the coating amount was adjusted to 5 g / m ² (single side) to obtain a coated paper for printing of Comparative Example. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

Comparative Example 6
In Comparative Example 5, paper was made in the same manner as in Comparative Example 5 except that the mixing ratio of the used paper pulp was set to 100%, and a coated paper for printing of Comparative Example was obtained. Table 1 shows the whiteness and appearance quality of the coated paper for printing.

The coated paper for printing of the present invention is not inferior to conventional coated paper made mainly from chemical pulp in terms of whiteness and appearance quality due to contaminants. We can respond satisfactorily to the demand for higher quality in terms of quality.

Claims (2)

A coated paper for printing in which a coating composition mainly composed of a pigment and an adhesive is coated on a base paper, containing 5 to 100% by weight of waste paper pulp made from newspaper waste paper and / or magazine waste paper, and ISO A coated paper for printing, wherein a base paper having a whiteness of 78 to 95% and a dart count of 0.05 to 5.0 mm ² is 5 to 200 / m ² is used. After the waste paper pulp is aged for 1 to 6 hours after adding hydrogen peroxide in an amount of 0.5 to 5%, treating with a low-speed, high-concentration shaft type disperser for the first time at 40 to 90 ° C. The second processing is performed with a low-speed, high-concentration shaft type disperser, and further 0.1 to 2% of thiourea dioxide is added, and the processing is performed with a disk-type disperser at 90 to 140 ° C. 2. The coated paper for printing according to claim 1, which is a waste paper pulp produced in the waste paper pulp production process.