JP2003293284A - Uncoated printing paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide uncoated printing paper having excellent strength though the paper is bulky and has softness. <P>SOLUTION: The uncoated printing paper comprises bulky pulp produced by subjecting raw material pulp to a mercerization treatment with an aqueous solution of an alkali at ≤9 and ≥50 wt.% concentration so as to preferably provide 80-100 wt.% of the content of cellulose II and then a hot water treatment with hot water at pH 3-12 and 50-100°C. The bulky pulp is contained in an amount within the range of preferably ≥5 and ≤50 wt.% based on the whole pulp component. Since the strength is reduced by compounding the bulky pulp, a paper strengthening agent is preferably contained or the paper is preferably coated with a surface treating agent. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bulky uncoated printing paper, and more particularly to printing paper suitable for use in books.

[0002]

2. Description of the Related Art With the increasing environmental protection, it is inevitable to reduce the weight of paper in order to effectively use the pulp for papermaking manufactured from forest resources. It is becoming a big flow. Here, reducing the weight of paper means reducing the weight while maintaining the thickness of the paper, that is, low density (bulky) paper.

First, as a method for reducing the density (bulking) of paper, paper pulp, which is the main raw material for paper, is being studied. Wood pulp is generally used as the pulp for papermaking. As pulp for lowering the density, chemical pulp is used to extract lignin, which is a reinforcing material in the fiber, and chemical pulp is used. Mechanical pulp such as thermomechanical pulp obtained has more rigid fibers and is more effective for lowering the density, and groundwood pulp in particular contributes to lowering the density. However, groundwood pulp is a mechanical pulp, and there is a problem in terms of specifications for blending with high-quality paper. Also, due to the blending, there is also a problem with paper quality, such as discoloration over time, and it cannot be blended. . Similarly, the incorporation of thermomechanical pulp into high-quality paper is also a problem.

In the case of high-quality paper, only the chemical pulp is mixed on the pulp side, but the density of the paper is greatly affected by the raw material tree species. That is, when the wood fibers themselves are coarse, the density can be reduced. Hardwood pulp is mainly mixed with hardwood pulp, but gumwood, maple, and birch are among the hardwood species that can be relatively low in density. However, it is difficult to identify, collect, and pulp only these tree species under the current trend of environmental protection.

On the other hand, in medium-quality paper or lower-grade paper, mechanical pulp is blended, which is usually a lower density than fine-quality paper. However, blending rigid fibers makes it difficult to print paper when printing (from mechanical pulp). The amount of the binding fiber is limited, and the mechanical strength of the bleached chemical pulp is lowered. Further, increasing the mechanical pulp, which usually has a lower degree of whiteness than the bleached chemical pulp, lowers the whiteness. Further, in recent years, there has been a demand for an increase in the content of waste paper pulp due to an increase in environmental protection and a need for resource protection. Recycled paper pulp is rarely pulped by being clearly classified according to the type such as high-quality paper, newspaper, magazines, leaflets, coated paper, etc., because it is pulped as it is mixed,
The nature of pulp tends to be higher than that of virgin mechanical pulp. The reason for this is that the fiber content of waste paper pulp is a mixture of chemical pulp and mechanical pulp. In addition, talc, kaolin, clay, and calcium carbonate, which are commonly used as a filler component contained in paper or a pigment component of the coating layer of coated paper, have a higher density than pulp, so the density of Tends to be high.
Therefore, increasing the blending ratio of waste paper pulp tends to increase the paper density. As described above, it is extremely difficult to achieve a sufficiently low paper density only from the pulp side, considering the situation of wood resources and paper quality design.

[0006] Usually, the pulp for papermaking softens the fibers by the beating treatment to fibrillize it, but the beating treatment tends to reduce the bulk, so that it is desirable not to do it as much as possible in order to increase the bulk. However,
If the beating process is insufficient, the strength will decrease.

As a method for lowering the density during papermaking, the press pressure should be as low as possible in the pressing step during papermaking, and no calendering should be performed to impart smoothness to the paper surface. Is mentioned. Further, it is desirable that the surface coating of the water-soluble polymer such as starch, which is carried out for the purpose of imparting the surface strength of the paper at the time of printing, to be as low as possible.

In addition to such contrivances at the time of pulping and papermaking, studies have also been conducted on fillers to be added to paper next to pulp. For example, Japanese Patent Application Laid-Open No. 5-339898 discloses a method of achieving a low density by blending hollow synthetic organic material capsules as a filler. In addition, a synthetic organic foaming filler (for example, trade name: EXPANSEL, manufactured by Nippon Philite Co., Ltd.) that achieves bulkiness by expanding with the heat of the dryer section of the papermaking machine is also proposed. However, the methods using these synthetic organic foaming fillers have problems that it is difficult to set the drying conditions during papermaking, the surface strength is weak, and the printing glossiness is lowered.

Japanese Patent Publication No. 52-39924 has proposed a method using a shirasu balloon. However, it has a poor mixing property with pulp for papermaking, and the paper containing the same causes uneven printing. There is.

Further, JP-A-8-13380 discloses a method of adding fine fibrillated cellulose, but it is necessary to specially prepare fine fibrillated cellulose, and further, the pulp freeness at the time of papermaking is improved. CSF40
It is necessary to adjust the amount to 0 ml or more, preferably CSF 500 ml or more, and it is difficult to adjust the freeness with a stock material containing a large amount of mechanical pulp, and it is difficult to implement with medium-quality paper or lower grade paper.

Further, although the paper thickness is increased by these methods, the stiffness of the paper exponentially increases as the paper thickness increases, so that the flexibility of the paper is not improved, so that the texture, the feel and the ease of turning are improved. It was insufficient.

Recently, as bulking agents for paper, ethylene and / or propylene oxide adducts of higher alcohols, polyhydric alcohol type nonionic surfactants disclosed in WO98 / 03730, JP-A No. 11-200284 have been disclosed. Higher fatty acid ethylene oxide adducts as shown,
-350380, an ester compound of a polyhydric alcohol and a fatty acid, an ethylene oxide adduct of an ester compound of a polyhydric alcohol and a fatty acid, or a fatty acid polyamidoamine has been reported. However, these bulking agents have a significant decrease in paper strength, and may have an inhibitory action depending on the type of sizing agent, which causes a problem of reduction in sizing property.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide an uncoated printing paper which has a low paper density (bulkness), high flexibility, less paper breaks during printing, and excellent printability. That is.

[0014]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result,
After immersing in an alkaline aqueous solution of 9% by weight or more and 50% by weight or less and performing mercerization treatment, the pH is 3 to 12, 50 to 100
The present invention has been completed by blending a bulky pulp having an excellent bulkiness produced by treating with warm water at ℃. It is possible to make the pulp bulky to some extent by simply mercerizing the pulp.
By treating with warm water of ~ 100 ° C, it is possible to produce a bulky pulp having extremely excellent bulkiness.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The bulky pulp used in the uncoated printing paper of the present invention has a pH of 3 after mercerization of a raw material pulp with an alkaline aqueous solution having a concentration of 9% by weight or more and 50% by weight or less. It is produced by treatment with warm water of 50 to 100 ° C at -12.

The raw material pulp of the bulky pulp is not particularly limited, and softwood, hardwood, non-wood fiber and the like can be used. Non-wood fibers can be selected from, for example, kenaf, jute, linter, manila hemp, bamboo, straw, bagasse, espart, and the like. As a raw material for the bulky pulp of the present invention, a chemical pulp obtained by converting these materials into a sulfite pulp (sulfite method, SP) or a sulfate pulp (kraft method, KP), or S.
It is preferable to further chemically purify P or KP and use a dissolving pulp (DP) having an increased α-cellulose content.

The mercerization treatment of the raw material pulp can be performed by immersing it in an alkaline aqueous solution, or by impregnating the alkaline aqueous solution by spraying or the like. As the alkaline aqueous solution, sodium, potassium,
It is preferable to use a caustic alkali such as calcium or an aqueous alkali solution such as a carbonate thereof. As the mercerization proceeds, the cellulose swells significantly, and the crystal structure of the cellulose also changes from cellulose I to alkali cellulose I and then to the more stable crystal form, alkali cellulose II. The alkali celluloses I and II are changed to cellulose II by being washed and dried.
Further, it is said that the cellulose II has an increased adsorptivity and is likely to react with various reagents. In the present invention, the content of cellulose II in the raw material pulp is 50 to 100% by weight, preferably 80 to 1 in order to impart sufficient bulkiness.
It is preferable to carry out a series of treatments so that the amount becomes 00% by weight. The mercerization treatment may be performed by a known method,
Normally, the pulp is dipped in an alkaline aqueous solution and left at room temperature for 10
It only needs to be processed for about a minute to 24 hours.

The content of cellulose II is calculated by the following formula.

Cellulose II content (%) = (I-
_{I I) / (I II -I} I) × 100

Here, _II is a raw material pulp (cellulose I
Content 100% by weight), I _II is 2θ = 19.8 ° of the sample (cellulose II content 100%) completely mercerized.
It is the crystalline interference intensity after subtracting the background intensity in. In addition, I is 2θ = 1 of the sample to be measured
This is the crystalline interference intensity at 9.8 °. (Hokkaido University Faculty of Engineering Research Report No. 75, p125). Taking sodium hydroxide as an example, the content of cellulose II in bulky pulp is
The concentration of the alkaline aqueous solution required to achieve 50 to 100% by weight is 9% by weight or more and 50% by weight or less, preferably 12 to 2%
5% by weight. If the mercerization treatment has an alkaline aqueous solution concentration of 9% by weight or more and 25% by weight or less, 10 to 40%
It is preferable to carry out at ℃.

The alkaline aqueous solution after treating the pulp is
If necessary, it can be separated from the pulp by filtration or centrifugation and reused. In the present invention, since a large amount of the alkali content remains due to the mercerization treatment with the alkali aqueous solution, it is preferable to remove the alkali content by washing with water or an acid aqueous solution. The aqueous acid solution is a mineral acid of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid or an acid salt thereof, for example, ammonium salts such as ammonium sulfate, ammonium chloride and ammonium nitrate, magnesium salts such as magnesium chloride and magnesium nitrate, zinc chloride and zinc nitrate. It is prepared by dissolving the zinc salt of

Next, the hot water treatment in the present invention will be described. It is necessary to use hot water at 50 to 100 ° C, preferably 70 to 100 ° C for this treatment. 50 ° C
Even if it is treated with warm water of less than 1, a sufficiently bulky pulp cannot be obtained. When the treatment with hot water is performed after the step of removing the alkali component is obtained, the treatment with warm water at 50 to 100 ° C. may be continuously performed to perform the treatment with hot water substantially in one step. The pH in the hot water treatment is 3 to 12, preferably 5
Is ~ 10. If the pH is out of this range, hydrolysis of the cellulose becomes remarkable, which not only adversely affects the bulkiness but also lowers the yield.

The hot water treatment is preferably carried out for 30 minutes or longer, more preferably 2 hours or longer. However, even if the treatment time exceeds 5 hours, the effect of further bulking reaches a ceiling. Further, it is preferable to bend the pulp fibers to some extent by a means such as stirring during the hot water treatment because a pulp having a higher bulk can be obtained. It is possible to make the pulp bulky only by the mercerization treatment, but if it is not further treated with warm water of 50 to 100 ° C after the mercerization treatment, the bulkiness of the pulp against external force such as a press or calender during the sheet formation is increased. It is difficult to maintain.

In the non-coated printing paper of the present invention, the amount of bulky pulp is not particularly limited, but is preferably 5% by weight or more and 50% by weight or less with respect to all pulp components. If the blending amount is less than 5% by weight, the effect of increasing the bulkiness is insufficient, and if it exceeds 50% by weight, the strength is largely reduced and it is difficult to use it as a printing paper.

Although sufficient bulkiness can be obtained by using the bulky pulp of the present invention, the fiber surface is hydrophobized, interfiber bonds are less likely to form, and paper strength tends to decrease. Therefore, it is desirable to include a paper strength enhancer in order to improve the paper strength. Examples of the paper strengthening agent include starch, modified starch, polyacrylamide, polyvinyl alcohol, polyamide / polyamine resin, urea / formalin resin, melamine / formalin resin, and polyethyleneimine. The content of the paper strengthening agent is preferably 0.1% by weight or more and 2% by weight or less per absolute dry weight of pulp.

The non-coated printing paper of the present invention has a chemical pulp (bleached kraft pulp of softwood (NBKP) or unbleached kraft pulp (NU) as raw material pulp in addition to bulky pulp.
KP), bleached hardwood kraft pulp (LBKP) or unbleached kraft pulp (LUKP), mechanical pulp (ground pulp (GP), thermomechanical pulp (TM)
P), chemithermo mechanical pulp (CTMP), etc.),
Deinked pulp (DIP) is used alone or mixed in any ratio. The pH during papermaking may be acidic, neutral or alkaline.

Further, the uncoated printing paper of the present invention may contain a filler. As the filler, known fillers such as white carbon, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium oxide and synthetic resin filler can be used.

Further, the non-coated printing paper of the present invention may contain a sulfuric acid band, a sizing agent, a retention improver, a drainage improver, a colorant, a dye, an antifoaming agent, etc., if necessary. .

The uncoated printing paper of the present invention is a printing paper which is not coated at all or is coated with a surface treatment agent containing no pigment. The non-coated printing paper of the present invention,
For the purpose of improving the surface strength and size, it is desirable to apply a surface treatment agent containing a water-soluble polymer as a main component. As the water-soluble polymer, starch, oxidized starch, modified starch, carboxymethyl cellulose, polyacrylamide, polyvinyl alcohol and the like which are usually used as a surface treatment agent can be used alone or in a mixture thereof. In addition to the water-soluble polymer, a paper strength enhancer for water resistance and surface strength improvement and an externally added sizing agent for sizing can be added to the surface treatment agent. As the coating amount of the surface treatment agent, the surface treatment agent can be applied by a coating machine such as a two roll size press coater, a gate roll coater, a blade metalling coater, and a rod metalling coater. It is preferable to use such a coating transfer type coating machine because the surface treatment agent remains on the surface of the paper and the increase in density is reduced. The coating amount of the surface treatment agent is preferably 0.1 g / m ² or more and 3 g / m ² or less per one surface.

As described above, by adding the bulky pulp, it is possible to obtain a non-coated printing paper which is bulky, lightweight and excellent in flexibility. Non-coated printing papers containing the bulky pulp of the present invention include book papers, offset printing papers, letterpress printing papers, gravure printing papers, electrophotographic papers, or coated papers, ink jet recording papers, thermal recording papers, and printing papers. It can also be used as a base paper such as pressure recording paper.

[0031]

The present invention is described in detail below with reference to examples, but the present invention is not limited to these. The paper quality of the following items was measured for the papers prepared in Examples and Comparative Examples. The method of measuring these paper qualities is as follows. -Basis weight: according to JIS P 8124: 1998. -Paper thickness and density: according to JIS P 8118: 1998. -Tear length: Measured according to JIS P 8113: 1998 for the handmade papers of Examples 1 to 4 and Comparative Examples 1 to 8. -Steckigt sizing degree: The handmade papers of Examples 1 to 4 and Comparative Examples 1 to 8 were measured according to JIS P 8122: 1976.・ Clark stiffness: according to JIS P 8143: 1996
The papermaking direction (MD) and the papermaking width direction (CD) of the uncoated printing papers of Examples 5-9 and Comparative Examples 9-10 were measured.

<Manufacture of Bulky Pulp> To a non-beaten softwood bleached kraft pulp (NBKP), a sodium hydroxide aqueous solution having a concentration of 15% was added so that the pulp concentration became 5%, and 20
It was immersed at 30 ° C. for 30 minutes for mercerization. Next, after sufficiently washing with water to adjust the pH to 7, hot water was added so that the pulp concentration became 5%, the pulp was treated at 70 ° C. for 2 hours, and then the pulp and hot water were separated using a centrifugal dehydrator. The bulky pulp thus obtained had a cellulose II content of 100% by weight.

[Example 1] Bulky pulp 10 as pulp content
And hardwood bleached kraft pulp (LBKP) (freeness
410 ml) 90 parts were used to prepare the prepared paper material according to JIS P
8222: 1998, paper was made with a Tappi standard square type hand machine with a target of a basis weight of 64 g / m ² , hand-made paper was prepared, and the results of paper quality are shown in Table 1.

[Example 2] Bulky pulp 10 as pulp content
Part and LBKP (freezing degree 410 ml) 90 parts are used, and as a sizing agent, alkiketene dimer (trade name: AS26
3. Made by Japan PMC Co., Ltd. 0.2 per dry weight of pulp
% By weight, amphoteric starch for internal addition as a paper strengthening agent (trade name: C
ATO315, manufactured by Nippon NSC Co., Ltd.
A handmade paper was prepared in the same manner as in Example 1, and the results of the paper quality are shown in Table 1.

[Example 3] Bulky pulp 20 as pulp content
And 50 parts of LBKP (freeness 410 ml) were used to prepare handmade paper in the same manner as in Example 1, and the results of paper quality are shown in Table 1.

[Example 4] Bulky pulp 20 as pulp content
Part and LBKP (freezing degree 410 ml) 80 parts, and used as a sizing agent Alkyketene dimer (trade name: AS26
3. Made by Japan PMC Co., Ltd. 0.2 per dry weight of pulp
% By weight, amphoteric starch for internal addition as a paper strengthening agent (trade name: C
ATO315, manufactured by Nippon NSC Co., Ltd.
A handmade paper was prepared in the same manner as in Example 1, and the results of the paper quality are shown in Table 1.

[Comparative Example 1] LBKP (freeness of 410 ml) was used as a pulp component, and a paper material prepared in the following manner was used to prepare a handmade paper in the same manner as in Example 1. Is shown in Table 1.

[Comparative Example 2] LBKP (freezing degree 410 ml) was used as the pulp component, and Alkyketene dimer (trade name: AS263, Japan PMC Co., Ltd.) as the sizing agent.
0.2% by weight based on absolute dry weight of pulp, and amphoteric starch for internal addition (trade name: CATO315, manufactured by Nippon NSC Co., Ltd.) as a paper strength enhancer to 1.0% by weight based on absolute dry weight of pulp. The prepared paper materials were used to prepare handmade paper in the same manner as in Example 1, and the results of paper quality are shown in Table 1.

[Comparative Example 3] Bleaching of aspen material as pulp content Chemi-thermo-mechanical pulp (BCTMP) (freeness
A paper stock prepared using 20 parts of 250 ml) and 80 parts of LBKP (freeness 410 ml) was made into handmade paper in the same manner as in Example 1, and the results of paper quality are shown in Table 1.

[Comparative Example 4] 20 parts of BCTMP (freeness 250 ml) and 80 parts of LBKP (freeness 410 ml) of aspen materials were used as pulp, and Alkyketene dimer (trade name: AS263, Japan) was used as a sizing agent. PMC
0.2% by weight based on absolute dry weight of pulp, and amphoteric starch for internal addition (trade name: CATO315, as a paper strength enhancer).
Nippon NSC Co., Ltd.) 1.
A handmade paper was prepared in the same manner as in Example 1 using the stock material prepared to be 0% by weight, and the results of paper quality are shown in Table 1.

[Comparative Example 5] LBKP (freeness of 410 ml) was used as the pulp component, and amorphous silica (trade name: Tixolex 17, manufactured by Rhodia) as a filler was adjusted to 12% by weight based on the weight of the paper. Using the prepared paper material, handmade paper was prepared in the same manner as in Example 1, and the results of paper quality are shown in Table 1.

[Comparative Example 6] LBKP (freeness of 410 ml) was used as the pulp component, and amorphous silica (trade name: Thixolex 17, manufactured by Rhodia) was used as the filler so as to be 12% by weight based on the weight of the paper. In addition, as a sizing agent, alkiketene dimer (trade name: AS263, manufactured by Japan PMC Co., Ltd.) is used in an amount of 0.2% by weight based on the dry weight of pulp, and as a paper strength agent, amphoteric starch for internal addition (trade name: CAT).
O315, manufactured by Nippon NSC Co., Ltd.) was prepared as a paper material in an amount of 1.0% by weight based on the absolute dry weight of pulp to prepare handmade paper in the same manner as in Example 1, and the results of paper quality are shown in Table 1.
It was shown to.

[Comparative Example 7] LBKP (freeness of 410 ml) was used as the pulp component, and a bulking agent (trade name: KB-1
15, a paper material prepared by Kao Co., Ltd. so as to be 1.0% by weight based on the absolute dry weight of pulp was made into handmade paper in the same manner as in Example 1, and the results of paper quality are shown in Table 1. It was

[Comparative Example 8] A bulking agent (trade name: KB-1) was prepared by using LBKP (freeness of 410 ml) as a pulp component.
15, Kao Co., Ltd. 1.0% by weight based on absolute dry weight of pulp, and Alkyketene dimer (trade name: A) as a sizing agent.
S263, Nippon PMC Co., Ltd.) 0.2% by weight per pulp absolute dry weight, and amphoteric starch for internal addition (trade name: CATO315, Japan NSC Co., Ltd.) 1.0 per pulp absolute dry weight as a paper strength enhancer. A handmade paper was prepared in the same manner as in Example 1 using the stock material prepared to have a weight percentage, and the results of paper quality are shown in Table 1.

[0045]

[Table 1] As shown in Table 1, the density of the handmade papers of Examples 1 to 4 in which the bulky pulp of the present invention was blended was remarkably reduced. Further, as shown in Examples 2 and 4, the addition of amphoteric starch for internal addition improved the breaking length, and the addition of alkylketene dimer improved the size. On the other hand, the handmade papers containing BCTMP of Comparative Examples 3 to 4 also had a lower density, but the effect was inferior to the bulky pulp of the present invention. The handmade papers containing the low-density fillers of Comparative Examples 5 to 6 have the same reduction in density as the bulky pulp of the present invention, but even if the amphoteric starch for internal addition and the alkyl ketene dimer are added, the breaking length and the The sizing did not improve and the addition of these chemicals had no effect. The handmade papers containing the bulking agents of Comparative Examples 7 to 8 have the same decrease in density as the bulky pulp of the present invention, but the decrease in breaking length is large, and even if the amphoteric starch for internal addition is added. Sufficient breaking length was not obtained.

Examples 5-9 and Comparative Examples 9-10 shown below
The non-coated printing paper of No. 2 was evaluated for printing by the method shown below. -Printing evaluation: Roland offset sheet-fed printing press, Hyecho LZ Indigo, Beni (Toyo Ink Mfg. Co., Ltd.)
Manufactured) and a printing test chart was printed in two colors on both sides of the paper under the condition of a printing speed of 7,000 sheets / hour, and the printing quality on both sides at that time was also visually evaluated. Fibers on the surface of Example 5 when printed on paper not coated with oxidized starch,
Based on the appearance of white spots due to the peeling of the filler, this is set as △, and if it is slightly better (when the number of white spots due to the peeling of the surface of the filler and the filler is less than the standard), it is ◯, and the white spots are even smaller The case was evaluated as ⊚.

[Example 5] Bulk pulp 20 as pulp content
Part, LBKP (freeness 460 ml) 80 parts, and alkyl ketene dimer (trade name: AS26
3. Made by Japan PMC Co., Ltd. 0.2 per dry weight of pulp
% By weight, amphoteric starch for internal addition as a paper strengthening agent (trade name: C
ATO3210, manufactured by Nippon NSC Ltd., 0.3% by weight based on the dry weight of pulp, and a yield improver (trade name:
DR3700, Hymo Co., Ltd.) 0.015 wt% per absolute dry weight of pulp, and light calcium carbonate as a filler adjusted to 15 wt% per paper weight, the pH of the stock was adjusted to 8 by sulfuric acid band. After that, the paper quality was made by a Fourdrinier paper machine at a paper making speed of 20 m / min, and the results of the paper quality of the obtained uncoated printing paper and the results of printing evaluation are shown in Table 2.

[Example 6] Using the paper made in Example 5 as a base paper, an oxidized starch (trade name: SK-) was applied by a two-roll type size press coater so that the coating amount was 5 g / m ^2.
Table 2 shows the results of the paper quality of the uncoated printing paper obtained by applying No. 20, manufactured by Nippon Corn Starch Co., Ltd., and the results of printing evaluation.

[Embodiment 7] The same amount of paper as the paper used in Embodiment 5 was used as a base paper, and the amount of coating was set to 0 by a gate roll coater.
7g / ^{m 2} to become as oxidized starch (trade name: SK-2
Table 2 shows the results of the paper quality of the non-coated printing paper obtained by coating No. 0, manufactured by Nippon Corn Starch Co., Ltd., and the results of printing evaluation.

[Example 8] The coating amount of oxidized starch was 1.6 g /
except that was coated so as to m ² will produce a non-coated printing paper in the same manner as in Example 7, the results of the paper quality of the non-coated printing paper obtained, and the result of printing evaluation shown in Table 2 It was

[Example 9] The coating amount of oxidized starch was 2.3 g /
except that was coated so as to m ² will produce a non-coated printing paper in the same manner as in Example 7, the results of the paper quality of the non-coated printing paper obtained, and the result of printing evaluation shown in Table 2 It was

[Comparative Example 9] LBKP (freeness 460 ml) was used as the pulp component, and alkyl ketene dimer (trade name: AS263, Japan PMC Co., Ltd.) as the sizing agent.
0.2% by weight per absolute dry weight of pulp, amphoteric starch for internal addition (trade name: CATO3210, manufactured by Nippon NSC Co., Ltd.) as a paper strength agent is 0.3% by weight per absolute dry weight of pulp, and a bulking agent (commodity). Name: KB-110, manufactured by Kao Corporation
0.8% by weight per absolute dry weight of pulp, yield improver (trade name: DR3700, manufactured by Hymo Co., Ltd.) is 0.015% by weight per absolute dry weight of pulp, and light calcium carbonate as a filler is 15% by weight per weight of paper. After adjusting the pH of the stock material adjusted to to pH 8 with a sulfuric acid band,
Paper was made by a Fourdrinier paper machine at a paper making speed of 20 m / min. Table 2 shows the results of the paper quality of the obtained uncoated printing paper and the results of the printing evaluation.

[Comparative Example 10] Using the paper prepared in Comparative Example 9 as a base paper, an oxidized starch (trade name: SK) was applied by a 2-roll type size press coater so that the coating amount was 5 g / m ^2.
Table 20 shows the results of the paper quality of the uncoated printing paper obtained by applying -20, manufactured by Nippon Corn Starch Co., Ltd., and the results of printing evaluation.

[0054]

[Table 2] The non-coated printing paper containing the bulky pulp of the present invention had a significantly lower density than the non-coated printing paper containing the bulking agent of Comparative Example 9 and was excellent in bulkiness. Further, it is apparent that the print quality is significantly improved by externally coating the oxidized starch as a surface treatment agent. Also,
In Comparative Example 10 in which the oxidized starch was externally applied to the non-coated printing paper of Comparative Example 9, the print quality was improved, but the density was increased and the Clark stiffness was also increased, so that the flexibility was deteriorated.

Further, from the non-coated printing paper coated with the surface treatment agent by the 2-roll type size press coater of Example 5, the surface treatment agent was applied by the gate roll coater which is the film transfer method of Examples 6 to 9. Since the surface treatment agent stays on the surface of the coated non-coated printing paper, the effect of improving the surface strength is high even if the coating amount is small, so it is possible to reduce the coating amount and maintain the density low. Therefore, it is advantageous in terms of bulkiness.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoichi Miyawaki             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Technical Research Institute Co., Ltd. (72) Inventor Yoichi Yamazaki             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Product Research Institute Co., Ltd. (72) Inventor Aya Kikuchi             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Product Research Institute Co., Ltd. F-term (reference) 4L055 AA02 AA03 AC06 AF09 AF44                       AG40 AG48 AH12 AH13 AH16                       AH37 BE08 EA20 EA25 EA31                       FA15 FA16 GA15 GA17 GA50

Claims (3)

[Claims] 1. A non-coated printing paper containing bulky pulp, wherein the bulky pulp contains raw material pulp in a concentration of 9% by weight or more 5
A non-coated printing paper, which is produced by mercerizing with an alkaline aqueous solution of 0% by weight or less, and then with hot water having a pH of 3 to 12 and 50 to 100 ° C. . 2. The uncoated printing paper according to claim 1, which contains a paper strength enhancer. 3. The uncoated printing paper according to claim 1, which is coated with a surface treatment agent.