JP6108266B2 - Comic paper for offset printing - Google Patents

Description

The present invention relates to comic paper for offset printing, which has a low basis weight, is bulky, and has good ink fillability.

Comic paper must be lightweight and bulky. In order to increase the bulk, it is necessary to loosen the calendering condition or to eliminate the calendering process. However, when this is done, the smoothness of the paper is deteriorated and the ink deposition property is deteriorated. Further, when the blending ratio of mechanical pulp is increased, since mechanical pulp is more rigid than kraft pulp, the surface of the paper becomes rough and the ink inking property deteriorates. When a bulking agent is added, the bulking agent inhibits inter-fiber bonding, and therefore there is a problem that the surface strength is lowered particularly when the amount added is increased.

Comic paper is actually produced by finding the optimum papermaking conditions while combining these measures. Among mechanical pulps, GP (groundwood pulp), PGW (pressured groundwood pulp) and RGP (refiner groundwood pulp) produced by grinding raw wood have flexible fibers and good printability. It has been known. However, since it is difficult to secure raw wood, the use of thermomechanical pulp (TMP) has become the mainstream as mechanical pulp made from wood chips. Among mechanical pulps, TMP has high strength, but the fibers are stiff and the printability is not so good.

In the case of using mechanical pulp, there are the following patent documents as techniques for improving the printability of paper. Patent Document 1 describes using hardwood mechanical pulp produced by chemical treatment. Further, it is described that fibers having a short fiber density index of 0.20 or more in hardwood mechanical pulp have a low short fiber density, so that a bulky structure is maintained and the density of the paper is lowered. However, broad-leaved trees generally have a hard and dense structure as compared with conifers, so that there is a problem that the power intensity is high for mechanical pulping. For this reason, in order to produce hardwood mechanical pulp, pretreatment with alkaline chemicals is necessary, and it is necessary to remodel the existing mechanical pulp manufacturing equipment.

Patent Document 2 describes that the proportion of mechanical pulp is 25 to 50% by mass, and PGW is used as mechanical pulp for conifers. PGW has few bundling fibers in mechanical pulp, is flexible and contains a lot of intermediate fibers in terms of fiber length distribution, and has high strength and is easy to express smoothness. Moreover, it is described that the color resistance is excellent. However, as mentioned above, it is difficult to obtain a stable supply economically because it is difficult to obtain raw wood.

Patent Document 3 describes that the fiber roughness of pulp obtained by breaking up printing paper is specified as 10 to 25 mg / 100 m, and if it exceeds 25 mg / 100 m, the formation deteriorates and the printability deteriorates. It is described that the bulk cannot be obtained at less than 10 mg / 100 m. However, the printing paper of Patent Document 3 has a high disintegration pulp freeness of 450 cc or more, and it is expected that the ink deposition property is poor. The basis weight of conventional comic paper was the 62,64,68g / m ^2, etc., 60 g / m ² less have come to a low basis weight paper is used, conventional level of bulk There is a need for weight reduction.

JP 2006-225774 A Japanese Patent No. 4868907 JP 2009-138308 A

An object of the present invention is to provide a comic paper for offset printing having a low basis weight, a bulk, and a good ink deposition property.

As a result of earnestly examining the means for improving the ink inking property of comic paper, the present inventor has found that the above-mentioned problems can be solved by specifying the characteristics of the pulp from which the comic paper has been disaggregated, and to complete the present invention. It came.

The first invention of the present application is:
Comic paper manufactured using mechanical pulp and waste paper deinked pulp as the main raw material, and the average fiber length of the disaggregated pulp is 0.95 to 1.05 mm, and the ratio of fibers having a fiber length of 0.2 mm or less is 7% of the total. Comic paper characterized in that it has a fiber roughness of 110 to 150 μg / m.

The second invention of the present application is the first invention,
In the fiber width distribution of the disaggregated pulp, the comic paper is characterized in that a fiber ratio in a range of 20 to 40 μm is 40 to 60%.

The third invention of the present application is the first invention or the second invention,
The comic paper is characterized in that the blending ratio of mechanical pulp is 50 to 100% and the freeness of mechanical pulp is adjusted to 75 to 100 ml CSF.

According to the present invention, it is possible to provide a comic paper for offset printing having a low basis weight and a large bulk, and having good ink fillability.

Embodiments of the present invention will be described below.
For the production of comic paper according to the present invention, a paper machine comprising the wire part, press part, dryer part and reel part processes is used.

In the comic paper according to the present invention, kraft pulp, waste paper deinked pulp, mechanical pulp, or the like can be used as a raw material pulp. As the kraft pulp, softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), and the like can be used. In addition, as waste paper deinking pulp, deinking pulp (DIP) such as newspaper waste paper deinking pulp and high-quality waste paper deinking pulp can be used. As the mechanical pulp, stone ground pulp (SGP), pressured ground wood pulp (PGW), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc. can be used. However, it is desirable to use conifer mechanical pulp because it is easy to manufacture.

The comic paper according to the present invention uses mechanical pulp and waste paper deinked pulp as main raw materials, and pulp obtained by disaggregating comic paper has an average fiber length of 0.95 to 1.05 mm and a fine fiber ratio (0. 2 mm or less) is 7 to 15%, and the fiber roughness is 110 to 150 μg / m.
The average fiber length, the fine fiber ratio, and the fiber roughness were measured using a fiber tester manufactured by Lorentzen & Wettre. The average fiber length was a length-weighted average fiber length, and the fine fiber ratio was expressed on a length basis. Is.

When the average fiber length is shorter than 0.95 mm, the bulk is insufficient. If it is longer than 1.05 mm, the texture becomes poor and the ink deposition property deteriorates. If the fine fiber ratio (0.2 mm or less) is less than 7%, the dents on the paper surface increase and the ink inking property deteriorates. If it exceeds 15%, the ratio of long fibers decreases and the bulk becomes insufficient. When the fiber roughness is smaller than 110 μg / m, the bulk is insufficient, and when the fiber roughness is larger than 150 μg / m, the ink inking property is deteriorated.

The comic paper of the present invention desirably has a fiber ratio of 40 to 60% in the fiber width range of 20 to 40 μm in the fiber width distribution of the separated pulp. The fiber ratio in the fiber width range of 20 to 40 μm is measured using a fiber tester manufactured by Lorentzen & Wettre, and is expressed on the basis of length. If the fiber ratio in the fiber width range of 20 to 40 [mu] m is 40 to 60%, the comic paper surface becomes dense and has no dents, and ink fillability can be improved. When the fiber ratio in the fiber width range of 20 to 40 μm is less than 40%, the ratio of the fibers having a small fiber width is large or the ratio of the fibers having a large fiber width is large. The bulk is insufficient, and the latter is bulky but the ink deposition property is poor. When the fiber ratio in the fiber width range of 20 to 40 μm is more than 60%, the bulk tends to be insufficient.

In order to make the characteristics of the pulp from which comic paper is disaggregated in this range, in the production of mechanical pulp, which is the raw material for comic paper, the selection of the tree species to be used, the presence or absence of chemical pretreatment, and grinding conditions are set. To do. Or it can adjust by the increase / decrease in the compounding rate of mechanical pulp.
For example, in the selection of a tree species, spruce shows a larger average fiber length, average fiber width, and fiber roughness than pine and cedar.

In the production of mechanical pulp (for example, TMP), when a pretreatment with chemicals is performed, the average fiber length is long and the average fiber width and fiber roughness can be reduced as compared with the case where no pretreatment is performed. As the grinding conditions, rapid grinding, that is, grinding that consumes a large amount of power in a short time, tends to reduce the average fiber length and the average fiber width, and slow grinding. If done, the average fiber length tends to be long and the average fiber width tends to be small. In comparison between mechanical pulp and waste paper deinked pulp, mechanical pulp has a longer average fiber length, a larger average fiber width, and a higher proportion of fine fibers.

The comic paper according to the present invention has a high mechanical pulp blending ratio of 50 to 100%. Therefore, the characteristics of the pulp from which the comic paper is disaggregated are generally determined by the characteristics of the mechanical pulp as described above. By investigating the pulp characteristics of the other pulps in advance, it becomes easy to determine the characteristics of the pulp from which the comic paper has been disaggregated.

In the comic paper of the present invention, the blending ratio of mechanical pulp as a main raw material is 50 to 100%. If it is less than 50%, the bulk is insufficient. Moreover, it is desirable that the freeness of the mechanical pulp is adjusted to 75 to 100 ml CSF. If the freeness of the mechanical pulp is lower than 75 ml CSF, the dewaterability in the paper machine is deteriorated, resulting in production problems such as a reduction in the paper making speed. If the freeness is higher than 100 ml CSF, the average fiber length of the pulp from which the comic paper is disaggregated becomes long, or the proportion of fine fibers decreases, resulting in poor ink fillability.

Ink fillability of printing paper is greatly affected by smoothness of printing paper represented by smoothness. If the ink deposition property is poor, it is necessary to increase the amount of ink adhering when printing, which causes a problem that the cost increases.

However, in the present invention, the average fiber length, the fine fiber ratio, the fiber roughness, and the fiber ratio in the range of 20 to 40 μm in the pulp obtained by separating the comic paper are set to a specific range, so that the smoothness is about the same. The present inventors have found that the ink inking property can be improved. Therefore, the ink deposition property can be improved while maintaining the bulk. The reason is expected as follows.

Mechanical pulp contains unfibered bundling fibers called shives, and the bundling fibers have a large fiber width. Therefore, poor inking is likely to occur due to the depressions formed on the paper surface around the shive. Normally, such depressions can be reduced by calendar processing, but comic paper is important for bulk, so the calendar processing conditions are loose and the depressions cannot be reduced. Mechanical pulp has a large proportion of fine fibers, and the size of the shive and fine fiber is too different, and the fine fiber cannot sufficiently fill the recesses around the shive, resulting in scumming due to poor inking. To do. If there are many fibers that are slightly larger than the fine fibers, it is considered that ink fillability can be improved by filling the gap formed between the shives and the fine fibers.

The comic paper of the present invention can contain waste paper deinked pulp as long as it does not violate the specific matters of the present invention. A higher mixing ratio of waste paper deinked pulp is desirable in terms of recycling, but the upper limit of the mixing ratio is also determined by the bulk, opacity and whiteness required for comic paper.

A filler can be added to the comic paper of the present invention. Specifically, 3 to 20% by mass of calcium carbonate can be added, and 0.5 to 2.0% by mass of white carbon may be added. Since white carbon has a high ink absorption capability, it contributes to improvement of ink inking property and opacity after printing, and calcium carbonate contributes to improvement of opacity, and can be used as a comic paper without back-through.

In addition, the type of filler used is not particularly limited, and fillers generally used for printing paper, such as inorganic fillers such as titanium dioxide, talc, clay, silica, and organic pigments, can be used as necessary. The ash content of the comic paper of the present invention is desirably 5 to 15%. If the ash content is too high, the surface strength becomes low, and paper dust and picking troubles are likely to occur. The filler fills the gaps between the pulp fibers, can impart smoothness to the paper, and ink inking properties are improved.

The comic paper thus obtained has an opacity of 87-97%. The opacity after printing is desirably 89 to 95%. General printing paper has a higher basis weight than newsprint (basis weight 43 g / m ² ), and it is not necessary to consider so much ink penetration. However, since comic paper has been reduced in weight, the influence of ink permeation on the back side is increased.

Comic paper is printed on an offset rotary press or offset sheet-fed press. The ink drying method is a heat set method using a drying device in a rotary press, and a cold set method without a drying device in a sheet-fed machine. In general, the cold setting method has a larger ink penetration. As comic paper becomes lighter in the future, the effect of ink penetration on the back of the paper will increase, so opacity after printing comic paper will be important for heat-set rotary presses. It can be said that it is very important for the sheet-fed machine.

The opacity after printing is lower than the opacity. When compared with papers having the same opacity, paper having a smaller difference between opacity and post-printing opacity (opacity−post-printing opacity) suppresses ink penetration in the thickness direction of the paper. It is more difficult to reduce the difference between opacity and post-print opacity with lower basis weight paper, but the difference between opacity and post-print opacity is reduced by 3% by blending mechanical pulp and adding highly oil-absorbing filler. In the following, it is further desirable that the content be 2% or less. By reducing the difference between opacity and post-printing opacity in this way, the post-printing opacity required when comic paper is used is increased without excessively increasing opacity, thereby preventing back-through. Comic paper can be obtained. In other words, in order to improve opacity, the strength is reduced by adding fillers, the quality is adversely affected by the increase in the ratio of mechanical pulp blending, and the cost of the waste ink deinked pulp blending ratio is reduced. The adverse effects of can be reduced.

In the comic paper of the present invention, a sulfuric acid band, a sizing agent, a paper strength enhancer, a yield improver, a dye and the like can be added to the pulp. As the sizing agent, a sizing agent such as rosin sizing agent, alkyl ketene dimer, alkenyl succinic anhydride can be used. As the paper strength enhancer, cationized starch, polyacrylamide resin and the like can be used. In addition, additives such as a slime control agent, a pitch control agent, and an antifoaming agent can be used.

The comic paper of the present invention is coated with a surface treatment agent containing a paper strength enhancer on at least one side for the purpose of improving the surface strength. Usually it is applied at the same coating amount on both sides. The coating amount of the paper strength enhancer is 0.5 to 1.5 g / m ² per side. Since the paper strength enhancer is applied, the surface strength can be increased even when the blending ratio of mechanical pulp and the addition ratio of filler are high. When the coating amount of the paper strength enhancer is less than 0.5 g / m ² on one side, the surface strength is insufficient. Even if the coating amount is more than 1.5 g / m ² , the effect of further improving the surface strength is hardly observed.

As a device for applying the surface treatment agent, a commonly used roll coater such as a two-roll size press coater or a gate roll coater, a blade coater, or a spray coater can be used. As the paper strength enhancer to be applied, oxidized starch, cationized starch, polyacrylamide, polyvinyl alcohol, carboxymethyl cellulose, styrene maleic acid copolymer, styrene acrylic acid copolymer and the like can be used. In addition to the paper strength enhancer, chemicals such as surface sizing agents, lubricants, and anti-slip agents can be mixed and applied to the surface treatment agent.

The coating concentration of the surface treatment agent is desirably 5 to 10% by mass. In order to increase the paper thickness, the coating concentration should be low. However, if the coating concentration is lower than 5% by mass, a sufficient coating amount cannot be obtained. If the coating concentration exceeds 10% by mass, uneven coating tends to occur, which is undesirable in terms of surface strength. The moisture content of the wet paper when applying the surface treatment agent is preferably 5 to 15%, more preferably 5 to 10%. If it is lower than 5%, due to the rapid change of the moisture content due to the application of the surface treating agent, the expansion and contraction of the paper in the paper making process is increased, so that wrinkles are concerned and the paper making stability is deteriorated. When the wet paper moisture at the time of application is higher than 15%, the penetration of the surface treatment agent into the paper layer increases, and the moisture content after application increases, resulting in a poor moisture profile and causing wrinkles. Sometimes.

When the comic paper of the present invention is produced, it is usually smoothed by a calendar device after being dried with a dryer. However, if the desired printability is obtained, it is desirable not to perform the calendering because it is bulky. As a device for calendar processing, a commonly used calendar device such as a chilled calendar, a soft calendar, or a gloss calendar can be used. The number of nips, nip pressure, roll temperature, roll material, roll hardness, etc. are set according to the required smoothness.

The basis weight of the comic paper of the present invention is 50 to 60 g / m ² , and more preferably 50 to 58 g / m ² . If the basis weight is less than 50 g / m ² , the thickness and opacity are insufficient, making it difficult to use for comic magazines. The comic paper of the present invention has a thickness of 120 to 150 μm. Preferably it is 120-145 micrometers. If comic paper in this range is used, the hand feeling and ease of turning pages will be good as a comic magazine.

The whiteness of the comic paper of the present invention is preferably 65 to 75%. This range is suitable for comic magazines. If the whiteness is less than 65%, the contrast with the printed image is weak and the printing effect is low. If the whiteness is higher than 75%, it becomes difficult to ensure opacity at a low basis weight. The smoothness of the comic paper of the present invention is preferably 5 to 20 seconds on both the front and back surfaces. If the smoothness is low, the ink inking property is inferior, and if it exceeds 20 seconds, the ink inking property is good but the density becomes high, and the thickness required for comic paper cannot be ensured with a low basis weight.

Comic paper of the invention, Clark stiffness (JISP8143: 2009 Paper - stiffness test method - Clark stiffness tester method) beside it is preferably 20 to 50 cm ^3/100. If less than 20cm ^3/100, to thereby provide an inexpensive impression there is no firm hand Nikkan, less likely to turn the page after bookbinding. After binding and higher than 50cm ^3/100, there is a problem that tends to even open the book naturally close is strong now handling is poor.

Hereinafter, the effects of the present invention will be specifically described by Examples and Comparative Examples. In addition, unless otherwise indicated,% represents the mass%, and the addition amount is represented by solid content or an active ingredient with respect to 100 mass parts of absolutely dry pulp.

Example 1
As raw material chips for thermomechanical pulp, spruce: domestic N-wood chips are used at a mass ratio of 60:40, 85 parts by mass of thermomechanical pulp (80 mlCSF), 10 parts by weight of hardwood bleached kraft pulp (420 mlCSF), As a filler, 5 mass% of calcium carbonate (Okutama Kogyo Co., Ltd., trade name: Tamapearl 121-6S) is added to a pulp dispersion composed of 5 parts by mass of black pulp (200 ml CSF), and cationized starch (GS 0.5% by mass of L Japan Co., Ltd., trade name: Geltron 24) was added, and 200 ppm of a yield improver (trade name: Hymo Lock ND-260, produced by Hymo Co., Ltd.) was added to make paper. Oxidized starch (product name: Oji Ace A, manufactured by Oji Cornstarch Co., Ltd.) dissolved in a wet roll with a gate roll coater to a concentration of 8% is applied to wet paper that has been dried to a moisture content of 11% at a rate of 0.8 g / m ² per side. After being applied to both sides of the paper as described above, the paper was dried and calendered, and a comic paper having a moisture content of 6.5%, a basis weight of 59.8 g / m ² and a whiteness of 69% was obtained.

(Example 2)
Comic as in Example 1 except that spruce: radiata pine: domestic N wood chips were used at a mass ratio of 15:25:60 and the freeness of the thermomechanical pulp was 90 ml CSF as the raw mechanical chip. Got the paper.

(Example 3)
Example except that PGW (pressured ground wood pulp, raw material: chili pine) was used as mechanical pulp, and a pulp dispersion consisting of 90 parts by weight of PGW (100 ml CSF) and 10 parts by weight of softwood bleached kraft pulp (480 ml CSF) was used. Comic paper was obtained as in 1.

(Comparative Example 1)
Comic paper was obtained in the same manner as in Example 2 except that the freeness of the thermomechanical pulp was changed to 110 ml CSF.

(Comparative Example 2)
The freeness of the thermomechanical pulp is 95 ml CSF, and from 40 parts by weight of thermomechanical pulp, 20 parts by weight of softwood bleached kraft pulp (480 ml CSF), 30 parts by weight of hardwood bleached kraft pulp (420 ml CSF) and 10 parts by weight of high quality waste paper deinked pulp (200 ml CSF) Comic paper was obtained in the same manner as in Example 1 except that the resulting pulp was used.

(Comparative Example 3)
Example 1 except that the freeness of the thermomechanical pulp was 70 ml CSF, and a pulp consisting of 40 parts by mass of thermomechanical pulp, 40 parts by mass of hardwood bleached kraft pulp (420 ml CSF) and 20 parts by mass of high-quality waste paper deinked pulp (200 ml CSF) was used. I got comic paper as well.

Table 1 shows the evaluation results of the comic papers of Examples 1 to 3 and Comparative Examples 1 to 3. The test method and evaluation method are as follows.

(Average fiber length of disaggregated pulp, fiber ratio of fiber length of 0.2 mm or less, fiber roughness, fiber width distribution)
Disaggregation was performed according to JISP8220: 1998 pulp-disaggregation method, and the measurement was performed using a fiber tester (CODE912) manufactured by Lorentzen & Wettre.
(Basis weight)
JISP 8124: 2011 paper and paperboard-Basis weight measurement method (thickness, density)
JISP 8118: 1998 paper and paperboard-Test methods for thickness and density (opacity)
JISP8149: 2000 paper and paperboard-Opacity test method (paper backing)-Diffuse illumination method (smoothness)
JISP 8119: 1998 paper and paperboard-smoothness test method using a Beck smoothness tester (evaluation of ink deposition)
Using an RI printing aptitude tester, solid printing was performed with offset ink, and the ink inking property was relatively evaluated in the following three stages.
◎ Excellent, ○ Good, △ Somewhat bad, × Inferior

As shown in Table 1, in Examples 1 to 3 of the present invention, comic paper having a low density and a good evaluation of ink fillability is obtained. In Comparative Example 1, the freeness of mechanical pulp is as high as 110 ml CSF, the average fiber length is as long as 1.12 mm, and the ratio of fibers having a fiber length of 0.2 mm or less is as low as 6.8%. Further, since the fiber roughness is as large as 152 μg / m and the ratio of the fiber width of 20 to 40 μm is as small as 38%, the evaluation of ink inking property is poor. In Comparative Example 2, the blending ratio of mechanical pulp is as low as 40% by mass, the density is high, the average fiber length is as long as 1.21 mm, so the texture is poor, and the evaluation of ink inking property is also slightly worse. . In Comparative Example 3, the blending ratio of mechanical pulp is as low as 40% by mass, the freeness of mechanical pulp is as low as 70 ml CSF, the average fiber length is as short as 0.93 mm, and the ratio of fibers having a fiber length of 0.2 mm or less is 15.3%. In many cases, the ratio of the fiber width of 20 to 40 μm is as high as 61%.

The comic paper of the present invention can also be used for printing paper for purposes other than comic magazines.

Claims (3)

Comic paper manufactured using mechanical pulp and waste paper deinked pulp as the main raw material, and the average fiber length of the disaggregated pulp is 0.95 to 1.05 mm, and the ratio of fibers having a fiber length of 0.2 mm or less is 7% of the total. Comic paper characterized by ˜15% and fiber roughness of 110˜150 μg / m. 2. The comic paper according to claim 1, wherein a fiber ratio in a fiber width range of 20 to 40 μm is 40 to 60% in the fiber width distribution of the separated pulp. The comic paper according to claim 1 or 2, wherein the blending ratio of mechanical pulp is 50 to 100%, and the freeness of mechanical pulp is adjusted to 75 to 100 ml CSF.