JP2006328564A - Method for producing newsprint for offset printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a newsprint manufacturing method for offset printing which prevents an increase in white spots due to an increase in the proportion of used paper pulp without making a major equipment modification to a high speed paper machine having a paper speed of 1400 m / min or more. provide.
In a newsprint papermaking method in which raw material pulp containing wastepaper pulp is used and papermaking is performed at a papermaking speed of 1400 m / min or more, the diameter of the roll as a wet paper is in direct contact with the final press of the press part of the papermaking machine. A method for producing newsprint for offset printing using a ceramic sprayed roll having a surface roughness Ra of 1.0 to 2.0 μm by ceramic spraying in a range of 1000 mm to 2000 mm.
[Selection figure] None

Description

  According to the present invention, a printing paper is produced when newspaper 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 by 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 the plate Adhere to the image area. Also, since the vessel is hydrophilic, it does not carry ink. Therefore, it is known that while the vessel is attached to the plate, the printed matter is continuously whitened and the printing surface quality is significantly deteriorated.

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 has been proposed in which air is supplied at the time of peeling off, and a reduction in surface strength is reduced by reducing the peeling force (see Patent Document 6). However, these methods have a problem that a high speed paper machine having a paper making speed of 1400 m / min or more cannot obtain a sufficient effect or 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

  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 present invention has been achieved. The present invention includes the following inventions.

(1) In a newspaper papermaking method in which raw paper pulp containing waste paper pulp is used and papermaking is performed at a papermaking speed of 1400 m / min or more, a diameter of 1000 mm is used as a roll in which wet paper is in direct contact with the final press of the paper machine press part. A method for producing newsprint for offset printing using a ceramic sprayed roll having a surface roughness Ra of 1.0 to 2.0 μm by ceramic spraying in a range of ˜2000 mm.

(2) The method for producing newsprint for offset printing according to (1), wherein the ceramic thermal spray roll has a surface porosity of 1% or more.

(3) After the press part, the wet paper is dried by the dryer part, and then the surface treatment agent is applied to the dried paper surface. The newspaper for offset printing described in (1) or (2) Production method.

(4) The method for producing newsprint for offset printing according to (3), wherein the surface treatment agent is at least one selected from treatment agents for improving surface strength, preventing paper dust, and improving printability.

(5) The raw material pulp contains at least one selected from the group consisting of a papermaking filler as a filler, and a papermaking chemical group consisting of a paper strength enhancer, a yield improver, a water-resistant agent, and an ultraviolet inhibitor ( A method for producing newsprint for offset printing according to any one of items 1) to (4).

(6) The raw material pulp is used for offset printing according to any one of items (1) to (5), wherein the proportion of the waste paper pulp exceeds 40%, and particularly the pulp with a high waste paper pulp content exceeds 50%. Newspaper production method.

  In the newspaper papermaking method of the present invention, the diameter of the roll in direct contact with the wet paper in the final press of the press part of the paper machine is in the range of 1000 mm to 2000 mm, and the surface is ceramic sprayed so that the surface roughness Ra is 1. It is a manufacturing method of newsprint for offset printing using a ceramic sprayed roll of 0.0 to 2.0 μm. According to the method of the present invention, a newspaper for offset printing that prevents an increase in white spots associated with an increase in the amount of waste paper pulp without making a major equipment modification to a high-speed paper machine with a paper speed of 1400 m / min or more. Paper can be manufactured.

  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 by being sandwiched between two wires and 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 the metal roll, hard rubber roll, etc. and felt, and the wet paper is squeezed and dehydrated. To do. 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.

  The present invention provides a ceramic whose diameter is in the range of 1000 mm to 2000 mm as a roll in direct contact with wet paper in the final press, and whose surface roughness Ra is adjusted to 1.0 to 2.0 μm by ceramic spraying. By using a thermal spraying roll, 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 so that the bonding of the vessel on the paper surface is not broken, and the vessel falls off in the printing process. This makes it possible to increase the 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.

  The ceramic and ceramic thermal spraying methods employed for adjusting the surface roughness Ra of the roll used in the method of the present invention to 1.0 to 2.0 μm include high-speed flame spraying and plasma spraying methods. It does not limit, and if it can adjust surface roughness Ra to 1.0-2.0 micrometers, it will not specifically limit.

  The surface roughness Ra is measured according to JIS B0633. When the surface roughness Ra is larger than 2.0 μm, the wet paper surface becomes rough, which may adversely affect the printing surface after offset printing. When the surface roughness Ra is less than 1.0 μm, friction occurs between the wet paper surface and the roll surface, resulting in an increase in peeling resistance, and at that time, the binding of the vessel on the paper surface is weakened. With this process alone, it is difficult to prevent the vessel from being disconnected, and white spots are likely to occur during printing. 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.

  Further, the surface porosity of the ceramic spray roll in the present invention is the porosity of the surface layer portion of the roll measured according to JIS R2205, and is preferably 1% or more, particularly 2 to 5%. If the surface porosity is less than 1%, the wet paper is brought into close contact with the roll surface at the time of pressing, and the peeling resistance is increased. At that time, the binding of the vessel on the paper surface is weakened. It is difficult to prevent disconnection of the ink, and white spots are likely to occur during printing. On the other hand, if it exceeds 5%, the releasability is good but the surface property is affected and the printability is inferior.

  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 1.0 to 2.0 μm, and the level difference Rk (JIS B0671-2) of the core portion of the roughness curve needs to be 1 μm or more.

  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 there is no particular limitation on the blending ratio. The method of the present invention is effective when the content of the used paper pulp is higher than 40%, and particularly effective when the content exceeds 50%.

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>
Pulp slurry mixed at a ratio of 15 parts of softwood semi-bleached kraft pulp (NSBKP), 20 parts of thermomechanical pulp (TMP), 10 parts of groundwood pulp (GP) and 55 parts of deinked pulp (DIP) made from waste newspaper Was refined with a refiner to prepare a 120-mL pulp slurry with Canadian Standard Freeness (CSF). 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 having 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, the surface roughness Ra is 1.0 μm, and the core level difference Rk of the roughness curve is 3.1 μm. The ceramic sprayed roll (product name: XG roll / manufactured by Yamauchi) with a porosity of 2%.

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

Example 2
Offset printing with 41.0 g / m ² of rice basis weight in the same manner as in Example 1 except that the pulp blending was 15 parts NSBKP, 20 parts TMP, 65 parts DIP, and 1600 m / min. I got newsprint paper.

Example 3
The roll blended with 20 parts of TMP and 80 parts of DIP, the roll with which the wet paper is in direct contact with the final press has a diameter of 1650 mm, the surface is ceramic sprayed, the surface roughness Ra is 1.2 μm, and the roughness curve In the same manner as in Example 1, except for the ceramic sprayed roll (product name: KX Rock / Kurashiki Boring) having a level difference Rk of 2.9 μm and a porosity of 3%. An offset printing newsprint of 0 g / m ² was obtained.

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 0.6 μm, the level difference Rk of the core portion of the roughness curve is 0.8 μm, the porosity is 3 % Newspaper printing paper for offset printing having a basis weight of 41.0 g / m ² was obtained in the same manner as in Example 1 except that it was a ceramic sprayed roll (product name: MH-Rock / Mitsubishi Heavy Industries).

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 0.6 μm, the level difference Rk of the core portion of the roughness curve is 0.8 μm, the porosity is 3 %, A newspaper sheet 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 a ceramic sprayed roll (product name: MH-Rock / Mitsubishi Heavy Industries).

Comparative Example 3
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 3 μm, the level difference Rk of the core portion of the roughness curve is 3.2 μm, and the porosity is 2%. Except that it was a ceramic sprayed roll, a newsprint paper for offset printing having a US basis of 41.0 g / m ² was obtained in the same manner as in Example 1.

Comparative Example 4
The roll in direct contact with the wet paper in the final press was a granite roll having a diameter of 1650 mm, a surface roughness Ra of 0.7 μm, and a core level difference Rk of the roughness curve of 1.2 μm. Except for the above, a newspaper paper for offset printing having a US basis of 41.0 g / m ² was obtained in the same manner as in Example 1.

  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 part speed] x 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 room temperature 24 ° C. and humidity 60% RH, newspaper ink (News Web Master 100X / manufactured by Sakata) was used as the ink, and printing speed was 200 sheets / min.

"White spots"
◯: 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.

"Comprehensive evaluation"
○: 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 apparent 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 generated during offset printing, and is a newsprint paper having an excellent printing surface.

Claims (3)

  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. A method for producing newsprint for offset printing using a ceramic sprayed roll having a surface roughness Ra of 1.0 to 2.0 μm by ceramic spraying.   The method for producing newsprint for offset printing according to claim 1, wherein the ceramic spray roll has a surface porosity of 1% or more.   The method for producing newsprint for offset printing according to claim 1 or 2, wherein the raw material pulp is a pulp with a high content of used paper pulp in which the proportion of used paper pulp exceeds 40%.