JP2009046772A - Method for producing newsprint for offset printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing newsprint paper for offset printing by which voids caused by vessels increasing the amount present in the surface of the newsprint paper according to an increase in amount of blended waste paper pulp are prevented. <P>SOLUTION: The method for producing the newsprint paper for offset printing comprises employing a ceramic flame sprayed roll having a diameter within the range of 1,000-2,000 mm and the surface with a surface roughness Ra of 0.1 to 1.0 μm and a HV (Vickers hardness) of 1,200 or more by ceramic flame spraying using chromia as a roll in direct contact with a wet web in the final press of a press part of a paper machine in the method for papermaking the newsprint paper comprising carrying out papermaking at a papermaking speed of 1,400 m/min or more by using raw material pulp containing the waste paper pulp. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a method for producing white paper on a printing surface when a newsprint paper produced by papermaking, drying, and passing through a calendar after printing a raw material mainly composed of wood pulp, waste paper pulp and filler is printed on an offset rotary press. The present invention relates to a method for producing newsprint paper that prevents printing and improves printing quality.

  In recent years, the quality of the printing surface of newsprint has been improved, especially with the trend toward colorization. Improvement in printing density and printing gloss and uniformity thereof, sharpness and color reproduction of printed images. The improvement of the property, reduction of white spots resulting from fine paper peeling on the paper surface, and the like are achieved. As specific methods, application of a polymer material such as oxidized starch or PAM (polyacrylamide) to the paper surface called a size press, or a change from a metal roll calender to a soft calender is performed.

  On the other hand, as a result of the increased use of wastepaper pulp due to recent social demands such as resource protection, a large amount of hardwood pulp derived from leaflets contained in recovered recovered paper is contained in newsprint paper raw pulp is what happened. Hardwood pulp contains a rectangular fiber structure with poor binding, called a vessel, and if this poorly-bonded vessel exists on the surface of newsprint, it peels off from the paper surface due to ink tack during printing, and Since this vessel adheres to the image area and the vessel is hydrophilic, ink does not get on the attached portion, and while the vessel is attached to the plate, the printed matter is continuously whitened to improve the printing surface quality. It is known to significantly reduce.

  As a technique for preventing the increase in white spots due to the multiple mixing of waste paper, a method of selecting and applying a surface treatment agent for enhancing the binding property of the vessel to the paper surface (see Patent Document 1), strengthening the wet paper squeezing A method for increasing the original binding of raw pulp (see Patent Documents 2 and 3), a method for drying a paper surface in which wet paper is insufficiently squeezed, and increasing the paper layer density to increase the paper layer strength ( Patent Document 4), a method of applying a release agent to the roll to reduce the decrease in surface strength that occurs when the wet paper is peeled from the roll in the press part (see Patent Document 5), and the wet paper from the roll in the press part. A method of reducing the strength of the surface by supplying air when peeling the surface to reduce the decrease in surface strength (see Patent Document 6), the surface roughness Ra of the ceramic spray roll of the final press of the press part is 1.0 to 2.0 And a method to m (see Patent Document 7) it has been proposed.

However, even with the above-described method, there are problems that a high-speed paper machine having a paper making speed of 1400 m / min or more cannot obtain a sufficient effect and requires a large facility.
Japanese Patent Laid-Open No. 10-2559591 JP 2002-115192 A JP 2004-190153 A JP 2004-11066 A JP 2004-270123 A JP 2004-353136 A JP 2006-328564 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a newsprint for offset printing that does not have white spots by increasing the binding force of vessels existing on the surface of the newsprint that causes white spots. Another object of the present invention is to provide offset printing that prevents an increase in white spots due to an increase in the amount of used paper pulp without major equipment modification to a high speed paper machine having a paper speed of 1400 m / min or more. An object of the present invention is to provide a manufacturing method for newsprint paper.

  As described above, the problem of white spots that occur when printing newsprint for offset printing is conventionally solved by introducing a technology that enhances the connectivity of the paper surface to the paper surface that causes white spots. Has been. However, attention has been paid to the fact that the effect of the newspaper paper making method with a paper making speed of 1400 m / min or more is insufficient, and as a result of extensive research, the following invention has been achieved.

(1) In a newsprint paper making method using raw pulp containing waste paper pulp at a paper making speed of 1400 m / min or more, a diameter of 1000 mm is used as a roll in direct contact with wet paper in the final press of the paper machine press part. Manufacture of newsprint for offset printing using a ceramic sprayed roll having a surface roughness Ra of less than 0.1 to 1.0 μm and a Vickers hardness (HV) of 1200 or more by ceramic spraying in a range of ˜2000 mm. Method.

(2) The ceramic spray roll is a ceramic whose surface has a surface roughness Ra of 0.1 to less than 1.0 μm and a Vickers hardness (HV) of 1200 or more by ceramic spraying using chromia (chromium oxide). The method for producing newsprint for offset printing according to item (1), which is a thermal spray roll.

(3) The method for producing newsprint paper for offset printing according to (1) or (2), wherein the ceramic sprayed roll is a ceramic sprayed roll that has been surface protected by impregnating an epoxy resin.

(4) The offset according to any one of items (1) to (3), wherein the wet paper is dried by a dryer part following the press part, and then a surface treatment agent is applied to the dried paper surface. A method for producing newsprint for printing.

(5) Manufacture of newsprint for offset printing according to any one of items (1) to (4), wherein the raw material pulp is a pulp with a high content of used paper pulp with a proportion of used paper pulp exceeding 40%. Method.

  According to the newspaper papermaking method of the present invention, in the final press of the press part of the paper machine, the diameter of the roll in direct contact with the wet paper is in the range of 1000 mm to 2000 mm, and the surface is subjected to ceramic spraying to obtain a surface roughness. By using a ceramic sprayed roll with a Ra of less than 0.1 to 1.0 μm and a Vickers hardness (HV) of 1200 or more, a large-scale facility modification is performed on a high-speed paper machine having a papermaking speed of 1400 m / min or more. Accordingly, it is possible to manufacture newsprint for offset printing that prevents the increase in white spots caused by increasing the amount of used paper pulp.

  As a paper machine that produces newsprint at high speed, there is usually a twin-wire paper machine called a gap former. In the wire part of this gap former, the paper stock is run while being sandwiched between two wires, and is dehydrated almost evenly from both the front and back surfaces to form wet paper. Also, following the wire part, the press part is sandwiched between a metal roll, a hard rubber roll, etc. and felt, and the wet paper is squeezed and dehydrated. . Subsequent to the press part, the wet paper is dried in the dryer part and the moisture is removed, whereby the bonding between the fibers further proceeds and a paper layer is formed. After the dryer part, in order to increase the strength of the paper surface and prevent paper dust at the time of printing, a surface treatment agent mainly composed of starch, PVA, polyacrylamide or the like is generally applied to the surface.

  In the case of such a conventional papermaking method, when the papermaking speed is 1400 m / min or more, when the wet paper web is peeled off from the roll in direct contact with the wet paper paper at the final press in the press part, the wet paper web surface is separated from the roll surface. The resulting peeling resistance is high, and the bonding of the vessel on the paper surface that has progressed in the press part is cut off, and the vessel remains on the paper surface due to the drying and surface treatment agent in the subsequent process, but the paper is caused by ink tack in the printing process. Since it peels off from the surface and is transferred to the image portion of the plate and causes white spots, it is difficult to blend a lot of waste paper pulp with many vessels.

  In the present invention, the roll is in direct contact with the wet paper in the final press, the diameter is in the range of 1000 mm to 2000 mm, the surface roughness Ra is less than 0.1 to 1.0 μm by ceramic spraying, and the Vickers hardness ( By using a ceramic sprayed roll whose HV is adjusted to 1200 or more, the peeling resistance generated between the wet paper surface and the roll surface is reduced at a paper making speed of 1400 m / min or more, and the binding of the vessel on the paper surface is reduced. This prevents the vessel from falling off and prevents the vessel from falling off in the printing process, and enables the increased distribution of waste paper pulp.

  The diameter of the roll used in the method of the present invention is preferably in the range of 1000 mm to 2000 mm. When the roll diameter is less than 1000 mm, when the papermaking speed is 1400 m / min or more, it becomes difficult to adjust the crown of the roll, which is not preferable. On the other hand, if the roll diameter exceeds 2000 mm, the power load increases, which is not preferable for high-speed papermaking.

  As a ceramic thermal spraying method employed for adjusting the surface roughness Ra of the roll used in the method of the present invention to less than 0.1 to 1.0 μm and adjusting the Vickers hardness (HV) to 1200 or more, For example, there is a high-speed flame spraying method or a plasma spraying method using chromia (chromium oxide) as a ceramic material.

  The surface roughness Ra is measured according to JISB0633. When the surface roughness Ra is 1.0 μm or more, the surface of the wet paper becomes rough, which may adversely affect the printing surface after offset printing. In continuous operation for about 150 days, when the surface roughness Ra is less than 1.0 μm, the particle hardness of conventional alumina is low, so the surface roughness is likely to decrease due to wear, and between the wet paper and the roll. The peeling resistance was increased and the bonding of the vessel was weakened. In the present invention, by using chromia with high particle hardness, the surface property of the roll is maintained uniformly, and the peeling resistance is kept small and constant, so that white spots are continuously generated without weakening the bonding of the vessel. It became possible to suppress it. A surface roughness Ra of less than 0.1 μm is difficult to manufacture because it is affected by a bare metal. Therefore, the surface roughness Ra is preferably 0.1 μm to less than 1.0 μm. The magnitude of the peeling resistance can be known from the draw calculated from the paper making speed of the final press and the paper making speed of the dryer part, and it can be said that the larger the draw, the higher the peeling resistance.

  In addition, the Vickers hardness of the ceramic sprayed roll in the present invention is preferably HV1200 or more in order to prevent the roll surface from being worn and to keep the surface roughness Ra constant. Even after the operation, the surface roughness Ra is difficult to decrease. As the ceramic material for ceramic spraying, chromia (chromium oxide) is preferable.

After ceramic spraying, surface treatment such as impregnation with an epoxy resin may be performed for the purpose of protecting the roll surface, and the roll may be polished after impregnation, but the surface roughness Ra is 0.1 to It must be maintained at less than 1.0 μm.

  In the method of the present invention, the pulp constituting the newsprint is not particularly limited. For example, chemical pulp such as NUKP, LUKP, NBKP, and LBKP, mechanical pulp such as TMP, CTMP, CGP, RGP, GP, PGW, and SCP, Used paper pulp such as newspapers, magazines, flyers, office papers, information papers, etc. can be used, and the blending ratio is not particularly limited. The method of the present invention is particularly effective when the proportion of waste paper pulp is as high as more than 40%.

In addition, there are no restrictions on the internal chemicals to be used. As fillers, inorganic silica-based inorganic pigments such as white carbon, calcined kaolin, structured kaolin, and inorganic fillers for papermaking such as titanium dioxide are used as necessary. It can be added as appropriate.
Furthermore, in addition to the above fillers, publicly known publicly used sizing agents such as sulfate bands, reinforced rosin, emulsion sizing agents, paper strength enhancers such as polyacrylamide and starch, yield improvers, water resistance agents, UV protection agents, etc. The paper chemicals can be added.

  There is no restriction | limiting in particular as a surface treating agent, The improvement of surface strength, paper dust prevention, and the improvement of printability should just be anticipated. For example, a material mainly composed of a water-soluble polymer is used. As water-soluble polymers, those used as normal surface treatment agents such as oxidized starch, etherified starch, ester starch, oxygen-modified starch, cationized starch, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl alcohol, polyacrylamide are used. Is possible.

  There is no restriction | limiting in particular in the coating method of a surface treating agent and / or other additives. Transfer coaters, air doctor coaters, blade coaters, rod coaters, etc. can be used. In particular, a transfer roll coater type coating apparatus, for example, a gate roll coater, a rod metalling size press, a blade metalling size press, or the like can be employed.

Regarding the paper passing process using a calendar, the type of calendar is not particularly limited, and any commonly used calendar can be used. In order to maintain and improve printability corresponding to multiple blending of waste paper, weight reduction, and color printing, a soft calender that can obtain the same tightness and high smoothness at a low nip pressure is preferable. The basis weight is not particularly limited, but is usually in the range of 37 to 50 g / m ² .

  Hereinafter, the present invention will be specifically described 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 and a comparative example show each mass part and mass%.

Example 1
<Preparation of base paper>
A pulp slurry mixed with 20 parts of softwood semi-bleached kraft pulp (NSBKP), 40 parts of thermomechanical pulp (TMP), and 40 parts of deinked pulp (DIP) made from newspaper waste paper is beaten with a refiner, Canadian Standard A pulp slurry having a freeness (CSF) of 120 mL was prepared. In the obtained pulp slurry, white carbon 1.5% (with respect to absolute dry pulp content), sulfuric acid band 1% (with respect to absolute dry pulp content), and emulsion type rosin size (product name: SPN-773 / Arakawa Chemical Industries) 0.3% (vs. dry pulp content) was added to make a paper stock. Next, using this paper stock, a paper was made with a gap former type paper machine at a paper making speed of 1530 m / min to obtain a base paper with a rice floor of 40.5 g / m ² . In the pressing process at this time, the roll in direct contact with the wet paper in the final press has a diameter of 1650 mm, the surface is ceramic sprayed, surface roughness Ra 0.8 μm, material chromia (chromium oxide), material hardness HV1200. It was a ceramic sprayed roll (product name: KX Rock-R / Kurashiki Boring Machine).

<Production of newsprint>
As a surface treatment agent, a phosphate esterified starch (trade name; GRC40 / manufactured by Oji Cornstarch) aqueous solution was used on both sides of the base paper obtained by the gap former type paper machine using a gate roll coater. After coating and drying so as to be 0.25 g / m ² per side, a smoothing process was performed with a soft calender to obtain newsprint paper for offset printing having a US basis of 41.0 g / m ² .

Example 2
Same as Example 1, except that NSBKP was 15 parts, TMP was 15 parts, groundwood pulp (GP) was 5 parts, DIP was 65 parts, and the paper making speed was 1600 m / min. An offset printing newsprint of 41.0 g / m ² was obtained.

Example 3
An offset printing newsprint with a weight of 41.0 g / m ² was obtained in the same manner as in Example 1 except that the pulp formulation was 0 part NSBKP, 20 parts TMP, and 80 parts DIP.

Comparative Example 1
The roll in direct contact with the wet paper in the final press has a diameter of 1650 mm, the surface is ceramic sprayed, the surface roughness Ra is 1.5 μm, the material is alumina, and the material hardness is HV950 (product name: XG roll) The newspaper for offset printing was obtained in the same manner as in Example 1 except that the weight was 40.5 g / m ² .

Comparative Example 2
The roll in direct contact with the wet paper in the final press has a diameter of 1650 mm, the surface is ceramic sprayed, the surface roughness Ra is 1.5 μm, the material is alumina, and the material hardness is HV950 (product name: XG roll) The newspaper for offset printing was obtained in the same manner as in Example 2 except that the weight was 41.0 g / m ² .

Comparative Example 3
The roll directly contacted with wet paper in the final press has a diameter of 1650 mm, the surface is ceramic sprayed, the surface roughness Ra is 0.7 μm, the material is alumina, and the material hardness is HV800 (product name: MH- A newspaper for offset printing having a weight of 40.5 g / m ² was obtained in the same manner as in Example 1 except that it was (Lock II / Mitsubishi Heavy Industries).

Comparative Example 4
The roll directly contacted with wet paper in the final press has a diameter of 1650 mm, the surface is ceramic sprayed, the surface roughness Ra is 0.7 μm, the material is alumina, and the material hardness is HV800 (product name: MH- A newspaper for offset printing having a weight of 41.0 g / m ² was obtained in the same manner as in Example 2 except that it was (Lock II / Mitsubishi Heavy Industries).

  The following quality evaluation was performed on the newsprint for offset printing obtained in each of the examples and comparative examples. The obtained results are shown in Table 1.

<Draw calculation method>
It was calculated from the following formula.
[(Dryer part speed-Final press speed) / Dryer speed]
× 100 = Draw (%)

<Printing evaluation>
Use an offset printing machine (Komori SYSTEM C-20 / Komori Corporation) to print 10,000 copies of color in four colors, and then check the number of white spots (white spots) (longer diameter 0.5 mm or more) in the ink section. The following evaluation was performed. Note that printing was performed in an environment of a room temperature of 24 ° C. and a humidity of 60% RH, newspaper ink (News Web Master 100X / manufactured by Sakata) was used as the ink, and the printing speed was 200 sheets / minute.

"White spots"
A: The number of white spots was 200 / m ² or less, and white spots were not confirmed, which was good.
Δ: The number of white spots was 200 to 400 / m ² , and white spots were slightly confirmed.
X: The number of white spots was 400 / m ² or more, and there were many white spots.

"durability"
(Circle): The reduction | decrease of surface roughness Ra in 150 day continuous operation was less than 0.1 micrometer.
(Triangle | delta): The fall of surface roughness Ra in 150 day continuous operation was less than 0.1-0.2 micrometer.
X: The decrease of the surface roughness Ra in 150 day continuous operation was 0.2 μm or more.

"Comprehensive evaluation"
A: The image was clear and the ink inking property was good.
Δ: Image was slightly inferior in sharpness, but ink depositability was slightly good.
X: The image was lacking in sharpness and the ink deposition property was inferior.

As is clear from Table 1, the newsprint paper for offset printing obtained by the method of the present invention has a very low level of white spots occurring during offset printing for a long time, and becomes a newsprint paper excellent in printing surface.

Claims (4)

  In the papermaking method for newsprint, which uses raw material pulp containing wastepaper pulp and is made at a papermaking speed of 1400 m / min or more, the roll has a diameter of 1000 mm to 2000 mm as a roll in which the wet paper is in direct contact with the final press of the paper machine press part Offset printing using a ceramic spray roll having a surface roughness Ra of less than 0.1 to 1.0 μm and a Vickers hardness (HV) of 1200 or more by ceramic spraying using chromia (chromium oxide) on the surface. Method for producing newspaper.   The method for producing newsprint for offset printing according to claim 1, wherein the ceramic sprayed roll is a ceramic sprayed roll that has been surface-protected by impregnating with an epoxy resin.   The method for producing newsprint for offset printing according to claim 1 or 2, wherein the wet paper is dried by a dryer part following the press part, and then a surface treatment agent is applied to the dried paper surface. The method for producing newsprint for offset printing according to any one of claims 1 to 3, wherein the raw material pulp is a pulp having a high content of used paper pulp with a mixing ratio of used paper pulp exceeding 40%.