JP2005256205A - Printing paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing paper, having a sufficient bulkiness, further printing quality excellent in flexibility and touch feeling, also excellent in printing aptitude such as smoothness, sizing property, surface strength, etc., and especially suitable for a book paper. <P>SOLUTION: This printing paper is characterized by applying a surface-treating agent containing a softening chemical, water soluble polymer and surface-sizing agent by 2-6 g/m<SP>2</SP>, and having 0.50-0.65 g/cm<SP>2</SP>density and 30-55 cm<SP>3</SP>/100 Clark stiffness in its crossing direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printing paper having a sufficient bulkiness, a printing quality excellent in flexibility and touch, and excellent in printability.

  Paper is desired to be reduced in weight from the viewpoints of resource saving and logistics cost reduction, and social demands such as an increasing environmental protection movement. However, when the paper is lightened, the paper thickness decreases, and as a printed matter, the opacity decreases and the printing on the back side becomes transparent, which not only makes it difficult to read, but also impairs the high-quality paper. There is a demand for weight reduction, that is, bulkiness while maintaining the above.

Bulky printing paper is demanded not only by bulkiness and printability, but also by the demand from the consumer side for the flexibility and feel of the paper due to the ease of turning pages when making magazines and books. .
As a method for increasing the bulk of paper, firstly, paper pulp, which is the main raw material of paper, is studied. Mechanical pulp is excellent as a pulp for increasing the bulk. However, blending has a problem of fading over time, and in the case of high-quality paper, blending is difficult due to the problem of specifications.

  For fine paper, chemical pulp is used. While it is possible to increase the bulk by selecting the tree species used for chemical pulp, it is difficult to select and pulp specific tree species while the current environmental protection movement is increasing.

  Usually, paper pulp is subjected to a beating process to make paper. By refining and shortening the pulp fibers by beating, the strength when made into paper is increased, and smoothness and uniformity (texture) are imparted. However, since the volume tends to decrease due to the beating process, it is preferable to suppress the beating process in order to increase the bulk. However, if the beating process is insufficient, the strength and smoothness of the paper are reduced.

  Studies are also being conducted to improve the bulkiness when paper is made by applying an additional treatment to paper pulp. For example, a technique of using a pulp that has been subjected to mercerization treatment for papermaking pulp, or using a pulp that has been twisted, such as curled fiber treatment, has been disclosed. Many of them are not improved touch feeling as printing paper, and no sufficient effect is recognized at present.

  Examples of the method for increasing the bulk during papermaking include lowering the pressing pressure in the pressing step and suppressing calendar treatment for imparting smoothness to the paper. When the bulk is increased only by these methods, the strength and smoothness of the paper are lost, so that sufficient bulk and flexibility cannot be obtained.

  In addition to dealing with such pulp and papermaking, increasing the bulk from chemicals and fillers added to the papermaking raw materials has been studied. In recent years, a technique for increasing the bulk by adding a bulking agent to a papermaking raw material has been performed. JP-A-2002-155494 (see Patent Document 1) defines a bulky soft paper which has a high bulkiness and has flexibility by specifying the melting point and HLB value of the bulky softener and containing it in paper. It is disclosed. As the bulking agent, a surfactant which is a compound having a hydrophilic group and a hydrophobic group is generally used. The bulking agent is fixed to the pulp fiber during papermaking, and the distance between the fibers is increased, thereby increasing the volume of the paper. It is believed that flexibility is imparted. Therefore, when bulking with a bulking agent, the strength of the paper is greatly reduced. Moreover, even if the addition amount of the bulking agent is increased, the bulkiness effect reaches a peak at a certain level or more, so that a sufficient bulkiness effect cannot be obtained with the bulking agent alone. Moreover, the touch feeling of paper cannot be improved completely only by containing a soft bulking agent.

Examples of the method for increasing the bulk from the filler include a method of blending the bulk filler. Bulky fillers are fillers with a high aspect ratio such as those having microporous in filler particles, such as amorphous silica, amorphous silicate, zeolite, etc. The bulk specific gravity is small. Japanese Patent Application Laid-Open No. 10-226982 (see Patent Document 2) contains amorphous silica or silicate having a bulk specific gravity of 0.3 g / mL or less as a bulky and high printing strength printing paper, and contains a water-proofing agent. A method of applying a surface treatment agent is disclosed. Although a bulky paper can be obtained by blending a bulky filler, it does not lead to an improvement in suppleness and feel.
JP 2002-155494 A Japanese Patent Laid-Open No. 10-226982

  An object of the present invention is to provide a printing paper that has sufficient bulkiness and printability, and is excellent in flexibility and touch feeling.

As a result of intensive research on the above problems, the present inventors have blended a filler having a specific pore volume, and further applied a surface treatment agent containing a softening agent, so that it is bulky, printable, and supple. Now, I have found that I can achieve all the touch feelings. That is, the present invention is as follows.
1 to 6 g / m of a surface treatment agent containing 3 to 10% by mass of a filler having a pore volume of 1.5 to 4.0 mL / g per paper mass and containing a softening chemical, a water-soluble polymer and a surface sizing agent. ² was applied, printing paper, wherein the density of 0.50~0.65g / cm ^3, the cross-direction Clark stiffness is 30~55cm ^3/100.

  The present invention provides a printing paper that has sufficient bulkiness and printability, and is excellent in flexibility and touch feeling.

The pore volume of the filler in the present invention is preferably 1.5 to 4.0 mL / g (measured using a mercury intrusion porosimeter). When the pore volume is less than 1.5 mL / g, sufficient bulkiness cannot be obtained even when blended with paper. Further, even when the pore volume exceeds 4.0 mL / g, a sufficient bulky effect cannot be obtained, but this is because the pores of the filler are reduced due to the share during paper making. That is, the larger the pores of the filler, the smaller the bulk specific gravity and the higher the bulk. On the other hand, the nano-order particles are aggregated to form a three-dimensional structure like amorphous silica or amorphous silicate. Then, as the pore size of the filler increases, the structural stability of the particles decreases. When the pore volume exceeds 4.0 mL / g, the structural stability of the particles is drastically reduced, and the particles collapse due to the shear or pressure applied during papermaking, and the pores disappear. It was found that could not be obtained.
The blending amount of the filler in the present invention is preferably 3 to 10% by mass per dry paper mass. When the blending amount of the filler is less than 3% by mass, the bulking effect is not sufficient, and when the blending amount exceeds 10% by mass, the paper strength is remarkably reduced, and the powder falls on the blanket during printing.

  The filler used in the present invention is not particularly limited as long as it satisfies the pore volume and average pore diameter. However, in consideration of optical characteristics and strength characteristics, amorphous silica, amorphous silicate, alumino Silicate is preferred. The particle size is 5 to 30 μm, preferably about 10 to 20 μm.

  As the softening chemical used in the present invention, it belongs to a surfactant, sulfosuccinic acid dialkyl ester salt type (anion), glycerin fatty acid ester type, pentaerythritol fatty acid ester type, sorbitan fatty acid ester type (nonion), A quaternary ammonium salt type, a polyamide polyamine type (cation), etc. are mentioned. For example, as currently sold, FineSoft 70 (Daiichi Kogyo Pharmaceutical Co., Ltd.), Ginsoft 100 (Daiichi Kogyo Pharmaceutical Co., Ltd.), Sofnon SSK-15 (Toho Chemical Co., Ltd.), High Softer PS-18 (Meisei Chemical Co., Ltd.), etc. In the range which does not inhibit the effect of the surface treating agent used together, it selects suitably. In recent years, surfactants called bulking agents have also been developed. However, when these are used, although the flexibility and feel of the paper can be obtained, the strength of the paper is greatly reduced.

  In general, the softening chemical in the present invention is preferably applied in combination with a water-soluble polymer or a surface sizing agent that is used as a surface treatment agent in the papermaking process. The reason for improving the flexibility and feel of the paper by applying softening chemicals instead of adding them internally is not clear, but keeps more softening chemicals on the surface of the paper than when they are internally added. Therefore, it is considered that the touch feeling is improved. Moreover, it is thought that by using the softening chemical in combination with the water-soluble polymer, it may also act as a plasticizer for the water-soluble polymer that serves as a binder for fixing the paper tissue.

In the present invention, as a result of intensive studies to satisfy both sufficient surface strength and flexibility, a surface treatment agent containing a softening chemical, a water-soluble polymer and a surface sizing agent is applied in a total amount of 2 to 6 g / m ² on both sides. It has been found that sufficient flexibility and good printability such as surface strength and size can be obtained.
If it is less than 2 g / m ² , the size, surface strength, and flexibility cannot be obtained. Even if it is applied in excess of 6 g / m ² , the surface strength and size will reach its peak, and the flexibility will be impaired. It is not preferable because the density increases.

  The water-soluble polymer used in the present invention is not particularly limited as long as the effect is not inhibited by gelation of the surface treatment agent when used in combination with the softening chemical, for example, oxidized starch, hydroxyethyl, etc. Any of etherified starch, enzyme-modified starch, polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose, or a mixture thereof can be used.

Examples of the surface sizing agent used in the present invention include alkyl ketene dimer compounds, styrene-acrylic compounds, petroleum resin compounds, higher fatty acid compounds, and rosin sizing agents. It is preferable to apply m ² . If it is less than 0.02 g / m ² , there is no size effect, and if it exceeds 0.3 g / m ² , the size development effect reaches its peak, leading to an increase in cost.

There is no particular limitation on the method of applying the surface treatment agent, but on-machine coating is economically preferable. For example, a gate roll coater, a two roll size, a blade metalling size press coater, a rod metalling size press, a blade coater, and a bar. Examples include coaters, rod blade coaters, and air knife coaters. In the 2-roll size press method, the base paper passes through the liquid pool of the coating solution, so the penetration of the coating solution into the base paper is large. However, in the gate roll coater method, the coating solution forms a film in advance and the film is transferred. Less penetration into the coating solution,
Which coating method is used is selected depending on the density and stiffness of the base paper.

The density of the printing paper of the present invention is preferably 0.50 to 0.65 g / cm ³ . If it is less than 0.50 g / cm ³ , the touch feeling on the surface is deteriorated, the flexibility is impaired, and operational problems such as running out of paper tend to occur. Further, if it exceeds 0.65 g / cm ³ , it is difficult to reduce the weight of magazines and books, which is not preferable.

The cross direction Clark stiffness of the printing paper of the present invention is preferably ^{30 to} 55 cm 3/100. When a printing paper is used as a magazine or a book, it is usually bound so that the vertical direction of the magazine or the book is aligned with the paper making direction of the printing paper. For this reason, the flexibility when turning pages has a large correlation with the Clark stiffness in the cross direction. Cross direction Clark stiffness is greater than 55cm ^3/100, to feel the hardness when the magazines and books, is not preferable because the flexibility is impaired. Moreover, even if it is less than 30 cm < ³ > / 100, since the high-grade feeling of paper is impaired conversely, it is unpreferable.

  As the cellulose fiber raw material used in the present invention, chemical pulp such as kraft pulp (KP), sulfite pulp (SP) and soda pulp (AP), semi-chemical such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP) Examples thereof include mechanical pulps such as pulp, groundwood pulp (GP), and thermomechanical pulp (TMP, BCTMP), non-wood pulps made from straw, miso, hemp, kenaf and the like, and deinked pulps made from waste paper. These may be used alone or in combination.

  In the present invention, it is possible to add a filler other than a filler having a specific pore volume such as amorphous silica, amorphous silicate, aluminosilicate, and a papermaking chemical used in normal papermaking, for example, a sizing agent, A size fixing agent, a dry paper strength enhancer, a wet paper strength enhancer, a yield improver, a drainage improver, an antifoaming agent, a slime control agent, a dye, and the like may be added as necessary.

  The paper for printing in the present invention is produced by a known paper machine, for example, a long-mesh type, a circular net-type, a short-net type, or a twin-wire type paper machine.

Printing paper obtained by the present invention are bulky with suppleness, excellent in print quality such as hand feeling preferably 60g / m ² ~100g / m ² as a basis weight. When it is less than 60 g / m ^{2 or more} than 100 g / m ² , it is difficult to feel the supple effect when used for book paper. In view of the suitability for smooth printing, 15 seconds or longer is preferable and the smoothness is preferably high. However, the smoothing treatment such as a calendar is appropriately performed in consideration of the density. Since the present invention can obtain a material excellent in printability, it can be used as writing paper, office paper, etc., and can also be used as a coating base paper.

The present invention will be specifically described below with reference to examples. Of course, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example show a mass part and mass%.
The evaluation methods of various physical properties in Examples and Comparative Examples are as follows.
(1) Filler pore volume Measured using a mercury intrusion porosimeter (pore sizer 9320, manufactured by Shimadzu Corporation).
(2) Paper density Measured according to JIS P 8118.
(3) Clark stiffness The clerk stiffness in the cross direction was measured according to JIS P 8143.
(4) Smoothness JAPAN TAPPI No. 5 was measured with a Oken type smoothness meter.

(5) Printing strength Measurement was performed using an offset ink T13 with an RI printer (manufactured by Meisei Seisakusho), and the result was evaluated and displayed.
A: High in strength, practically satisfactory, and excellent in quality.
○: Strength is high and there is no practical problem.
Δ: The strength is slightly inferior, and there is a problem in practical use.
X: The strength is remarkably inferior, it is a problem in practical use, and the quality is remarkably inferior.

(6) Texture evaluation The print paper bundle direction is aligned so that the vertical direction and the paper-making direction of the print paper are aligned, and the touch feeling of the paper and the ease of turning the page are as follows. It was evaluated according to the evaluation criteria.
◎: Very good ○: Excellent △: Somewhat problematic ×: There is a problem

Example 1
An aqueous pulp slurry containing 100 parts of LBKP (Freeness (CSF) = 400 mL), 8 parts of white carbon having a pore volume of 3.0 mL / g (trademark: Tokusir GU-N, manufactured by Tokuyama), and 0.8 mL 20 parts of light calcium carbonate (trade name: TP121, manufactured by Okutama Kogyo Co., Ltd.) having a pore volume of / g, and 1.0 part of starch, 0.05 part of alkyl ketene dimer, and 0.5 part of sulfuric acid band The added stock is made using an on-top paper machine, and softening chemicals (trademark: Fine Soft 70, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.5 g / m ² , starch (on-machine size press coater) trademark: Ace a, Oji cornstarch Co., Ltd.) and 4.0 g / ^{m 2,} a surface sizing agent (trademark: SKS296, Arakawa chemical industrial Ltd.) 0.08 g / ^{m 2} was coated, basis weight 7 .6g / ^{m 2,} a density 0.58 g / cm ^3, to obtain a printing paper smoothness 16 seconds.

Example 2
To an aqueous pulp slurry containing 100 parts of LBKP (Freeness (CSF) = 400 mL), 5 parts of white carbon (trademark: Toxeal GU-N, manufactured by Tokuyama) having a pore volume of 3.0 mL / g, and 0.8 mL 23 parts of light calcium carbonate (trade name: TP121, manufactured by Okutama Kogyo Co., Ltd.) having a pore volume of / g, and 1.0 part of starch, 0.05 part of alkyl ketene dimer, and 0.5 part of sulfate band The added stock is made using an on-top type paper machine, and softened chemicals (trademark: Fine Soft 70, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with an on-machine size press coater, 1.0 g / m ² , starch ( trademark: Ace a, Oji cornstarch Co., Ltd.) and 3.0 g / ^{m 2,} a surface sizing agent (trademark: SKS296, Arakawa chemical Industries, Ltd.) 0.08 g / ^{m 2} was coated, basis weight 8 .4g / ^{m 2,} a density 0.62 g / cm ^3, to obtain a printing paper smoothness 16 seconds.

Example 3
Aqueous pulp slurry containing 100 parts of LBKP (Freeness (CSF) = 400 mL) 8 parts of amorphous silicate (trademark: Thixorex, Rhodia) having a pore volume of 1.7 mL / g, and 0.8 mL / 20 parts of light calcium carbonate (trade name: TP121, manufactured by Okutama Kogyo Co., Ltd.) having a pore volume of g is added, and further 1.0 part of starch, 0.05 part of alkyl ketene dimer, and 0.5 part of sulfuric acid band are added. The paper stock was made using an on-top type paper machine, and softened chemicals (trademark: Finesoft 70, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.5 g / m ² , starch (trademark) using an on-machine size press coater. : Ace a, Oji cornstarch Co., Ltd.) and 4.0 g / ^{m 2,} a surface sizing agent (trademark: SKS296, Arakawa chemical Industries, Ltd.) 0.08 g / ^{m 2} was coated, basis weight 79 4g / ^{m 2,} a density 0.62 g / cm ^3, to obtain a printing paper smoothness 16 seconds.

Comparative Example 1
An aqueous pulp slurry containing 100 parts of LBKP (freeness (CSF) = 400 mL), 1 part of white carbon having a pore volume of 3.0 mL / g (trademark: Tokusir GU-N, manufactured by Tokuyama), and 0.8 mL 27 parts of light calcium carbonate (trade name: TP121, manufactured by Okutama Kogyo Co., Ltd.) having a pore volume of / g, and 1.0 part of starch, 0.05 part of alkyl ketene dimer, and 0.5 part of sulfuric acid band The added stock is made using an on-top paper machine, and softening chemicals (trademark: Fine Soft 70, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.5 g / m ² , starch (on-machine size press coater) trademark: Ace a, Oji cornstarch Co., Ltd.) and 4.0 g / ^{m 2,} a surface sizing agent (trademark: SKS296, Arakawa chemical Industries, Ltd.) 0.08 g / ^{m 2} was coated, basis weight 8 .3g / ^{m 2,} a density 0.69 g / cm ^3, to obtain a printing paper smoothness 14 seconds.

Comparative Example 2
Aqueous pulp slurry containing 100 parts of LBKP (Freeness (CSF) = 400 mL), 12 parts of white carbon (trademark: Toxeal GU-N, manufactured by Tokuyama) having a pore volume of 3.0 mL / g, and 0.8 mL 16 parts of light calcium carbonate (trade name: TP121, manufactured by Okutama Kogyo Co., Ltd.) having a pore volume of / g is added, and 1.0 part of starch, 0.05 part of alkyl ketene dimer, and 0.5 part of sulfuric acid band are added. The paper stock was made using an on-top type paper machine, and softened chemicals (trademark: Finesoft 70, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.5 g / m ² , starch (trademark) using an on-machine size press coater. : Ace a, Oji cornstarch Co., Ltd.) and 4.0 g / ^{m 2,} a surface sizing agent (trademark: SKS296, Arakawa chemical Industries, Ltd.) 0.08 g / ^{m 2} was coated, basis weight 8 .3g / ^{m 2,} a density 0.69 g / cm ^3, to obtain a printing paper smoothness 17 seconds.

Comparative Example 3
To an aqueous pulp slurry containing 100 parts of LBKP (Freeness (CSF) = 400 mL), 5 parts of white carbon (trademark: Toxeal GU-N, manufactured by Tokuyama) having a pore volume of 3.0 mL / g, and 0.8 mL / G of light calcium carbonate (trade name: TP121, manufactured by Okutama Kogyo Co., Ltd.) having a pore volume of 23 g was added to 23 parts, and 1.0 part of starch, 0.05 part of alkyl ketene dimer, and 0 parts of sulfate band were added. The paper stock with 5 parts added was made using an on-top type paper machine, and softening chemicals (trademark: Fine Soft 70, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were 1.5 g / m ² using an on-machine size press coater. , starch (trademark: Ace a, Oji cornstarch Co., Ltd.) and 6.0 g / ^{m 2,} a surface sizing agent (trademark: SKS296, Arakawa chemical Industries, Ltd.) 0.08 g / ^{m 2} coated Basis weight 83.9 g / ^{m 2,} a density 0.65 g / cm ^3, to obtain a printing paper smoothness 16 seconds.

Comparative Example 4
An aqueous pulp slurry containing 100 parts of LBKP (Freeness (CSF) = 400 mL), 8 parts of white carbon having a pore volume of 3.0 mL / g (trademark: Tokusir GU-N, manufactured by Tokuyama), and 0.8 mL 20 parts of light calcium carbonate (trade name: TP121, manufactured by Okutama Kogyo Co., Ltd.) having a pore volume of / g, and 1.0 part of starch, 0.05 part of alkyl ketene dimer, and 0.5 part of sulfuric acid band The added stock is made using an on-top type paper machine, and softened chemicals (trade name: Fine Soft 70, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) are added with an on-machine size press coater to 0.1 g / m ² , starch ( trademark: Ace a, Oji cornstarch Co., Ltd.) and 0.6 g / ^{m 2,} a surface sizing agent (trademark: SKS296, Arakawa chemical industrial Ltd.) 0.08 g / ^{m 2} was coated, basis weight 7 .0g / ^{m 2,} a density 0.54 g / cm ^3, to obtain a printing paper smoothness 16 seconds.

Comparative Example 5
28 parts of light calcium carbonate (trade name: TP121, manufactured by Okutama Kogyo) having a pore volume of 0.8 mL / g was added to an aqueous pulp slurry containing 100 parts of LBKP (freeness (CSF) = 400 mL), and starch. Using an on-top type paper machine, 1.0 part, 0.05 part of alkyl ketene dimer, 0.5 part of sulfuric acid band, and 1.0 part of bulking agent (trademark: KB115, manufactured by Kao) were added. Paper is made, and starch (trademark: Ace A, manufactured by Oji Cornstarch) is applied with 4.0 g / m ² and surface sizing agent (trademark: SKS296, manufactured by Arakawa Chemical Industries) is applied with 0.08 g / m ² using an on-machine size press coater. Thus, a printing paper having a basis weight of 89.1 g / m ² , a density of 0.67 g / cm ³ , and a smoothness of 14 seconds was obtained.

Claims (1)

2 to 6 g / m of a surface treatment agent containing 3 to 10% by mass of a filler having a pore volume of 1.5 to 4.0 mL / g per paper mass and containing a softening chemical, a water-soluble polymer and a surface sizing agent. ² was applied, density of 0.50~0.65g / cm ^3, printing paper cross direction Clark stiffness is characterized by a 30~55cm ^3/100.