WO2002025009A1

WO2002025009A1 - Method of manufacturing newsprint

Info

Publication number: WO2002025009A1
Application number: PCT/JP2001/008179
Authority: WO
Inventors: Hitoshi Ishizawa; Takashi Yuhara; Masaaki Oba; Kazuhiro Nojima
Original assignee: Oji Paper Co,. Ltd.
Priority date: 2000-09-21
Filing date: 2001-09-20
Publication date: 2002-03-28
Also published as: JP3978567B2; JP2002088690A; KR100496053B1; CN1216204C; KR20030036597A; CN1461369A

Abstract

A method of manufacturing newsprint for offset print having no difference between the front and rear surfaces thereof and providing an excellent workability of printing by optimizing press conditions in a paper-making process and soft calendar processing conditions, comprising the steps of making paper with a materials formed mainly of wood pulp, used paper, and filler, drying the paper, and treating the paper by passing through a soft calendar, characterized in that the paper passing processing is formed of one-nip processing, and a paper surface coming into contact with the metal roll side of the soft calendar is the surface coming into contact with a felt in the final press roll of a paper making process press part.

Description

Description New question paper manufacturing method Technical field

The present invention relates to newsprint, particularly to newsprint containing a high percentage of waste paper pulp (DIP), and to a method for producing newsprint for offset printing having excellent print quality with no difference between front and back. Background art

For newsprint, raw pulp mainly composed of pulp and waste paper pulp is used.Recently, from the viewpoint of environmental issues such as increased garbage and resource conservation, the use of high percentages of waste paper and the reduction of rice floor area Is being requested. On the other hand, offset printing, color printing, and high-speed printing of newsprint are progressing rapidly, and concomitantly, newsprint, which is a printing medium, has better color than ever before. Improvements in printability and workability are required.

Offset printing is a method in which dampening water and printing ink are supplied to a printing plate, and then the ink is transferred to a rubber plate called a blanket and then transferred to paper for printing. In addition, the use of relatively high-viscosity inks has the advantage of reducing the penetration of the ink into the paper layer and reducing ink strike-through (high opacity) after printing.

However, with the recent reduction in weight of newsprint, higher opacity after printing has been required even more, and with the introduction of color, good ink inking has also been required. I got it. The most widely used method of smoothing by calendering is to increase the ink inking property of the paper during printing '; the smoothing by increasing the ep pressure of the calendering process or increasing the number of nips If this is the case, the ink adhesion will be good, but the bulkiness of the paper will be impaired, and the opacity after printing will decrease, and the stiffness will decrease, resulting in poor runnability such as wrinkles during printing It causes trouble. Also, force render processing Even if bulky paper can be obtained by reducing the surface roughness, the difference between the front and back sides of the inking property of the paper surface increases, and the inking property deteriorates, especially on the low smoothness side paper. A problem arises in that the image densities are significantly different. This is because during the papermaking process, the dewatering conditions in the wire part and the press part are slightly different between the front and back sides, so there is a difference in the smoothness of the paper, and the distribution of fillers and fine fibers in the thickness direction It is thought that the difference in the ink transferability between the front and the back occurs because the state is different between the front and the back.

On the other hand, as a method for increasing the opacity after printing, inorganic pigments such as hydrated silicate and titanium oxide, and organic pigments such as urea-formaldehyde resin are widely used as papermaking fillers. However, if the filler addition ratio of these fillers is increased, there is a tendency for a difference between the front and back sides of the ink adhesion, and the dampening solution used in the printing process at the time of offset printing easily oozes out of the paper layer and the blanket. There is a limit to the rate of addition, as this can lead to troubles of piling (accumulation) as paper powder. In addition, the high proportion of DIP (deinked waste paper pulp), which is regarded as important in the environment, has a higher opacity than that of mechanical pulp such as 0P and TMP. Due to the difficulty, it is extremely difficult to achieve both improvement in opacity and high proportion of DIP. In view of the circumstances described above, the present inventors have found that, particularly in newsprint paper containing a high percentage of waste paper pulp, both the front and back sides show good inking inking property and print opacity at the time of rotary offset printing. A study was conducted on a method for obtaining excellent printing workability.

As a result, the present invention is to provide newsprint for offset printing which has excellent printing quality with no difference between front and back sides and excellent printing workability by optimizing the pressing conditions and the soft calendering conditions in the paper making process. is there. Disclosure of the invention

The present invention relates to a method for producing newsprint in which a raw material mainly composed of wood pulp, waste paper pulp, and filler is made, dried, and then passed through a soft power renderer. The present invention relates to a method for producing a new paper sheet, characterized in that the paper surface in contact with the metal pallet side of the soft calendar is the surface that comes into contact with the felt by the final press roll in the press part during the papermaking process. Newsprint is made on various paper machines, but if it is manufactured using a twin-wire type paper machine, which is usually called a gap former, a well-formed paper can be obtained at high speed. Is being done. The wire part of the gap former has a structure in which the stock is run between two wires and dewatered almost equally from both sides.Therefore, it has a uniform formation and relatively little difference between front and back . In the press part following the wire part, the paper is pressed and dewatered by being sandwiched between metal rolls and felt, but the water in the paper is only pressed in one direction to the felt side, and the fine fibers and filler in the paper layer Distribution is biased toward the water squeezing direction, that is, the felt side surface, and the other is pressed against smooth hard rolls (granite, metal rolls, etc.) to capture the smooth surface. For this reason, the smoothness of the surface where the final breath hits the smooth hard roll side is usually high, and if a two-nip process is performed with a machine calender and a soft force renderer that smoothes both surfaces almost evenly, the difference between the front and back sides will be maintained Or it will be enlarged.

Then, after drying the paper in the dryer part, apply a surface treatment agent mainly composed of starch, PVA, polyacrylamide, etc. to the surface to increase the strength of the paper surface and prevent paper dust during printing. Is commonly done. This surface treating agent is applied to a coating device generally used in the papermaking field, such as a size press, a blade metallizing size breath, a mouth metalling size press, a gate roll recorder, a blade coater, a bar coater, and a rod blade coater. The material is applied to the surface of the base paper using a device selected from known and publicly used devices such as an air knife coater and an air knife coater.

When the surface treating agent is applied using such an apparatus, the amount of application is 0.05 to 1 g Zm ² per one side by dry weight, and the coating is dried.

After the surface treatment agent is applied and dried, it is passed through a calendar as necessary, and is pressed and smoothed to finish the product. In such a case, a machine calendar using a combination of a normal metal roll and a metal roll as a calendering device promotes the difference between the front and back sides of the smoothness and the inking property generated in the above-described process up to the press pad. There is a tendency and it is not preferable.

The calendar used in the present invention is a metal roll and an elastic roll (generally covered with a highly durable resin material such as wool paper roll or polyamide resin). Roll) This is a so-called soft calender composed of force, and can reduce the unevenness in density after the calendar caused by unevenness in the formation of the paper layer, compared with the conventional machine calendar consisting of only metal rolls. In offset printing, especially in multicolor printing, it is possible to obtain a printing surface of uniform density without ink absorption unevenness.

The above soft calenders have been widely used in the past, but in order to eliminate the difference between the front and back by processing with metal rolls and elastic rolls of different materials, usually the same paper surface is made of metal rolls and elastic rolls. Two or more nips have been passed so that they touch each other alternately. On the other hand, in the present invention, in order to eliminate the front-back difference that has already occurred before the press part, and to maintain bulkiness and ensure opacity, it is necessary to pass only one nip. At this time, the paper surface in contact with the metal roll side is made to correspond to the surface in contact with the felt by the final press roll in the papermaking process press part, so that there is no difference between the front and back, and good ink deposition is obtained. be able to. In other words, a metal roll with a smoother surface of a soft calender is pressed against the paper surface on the side in contact with the felt with the final press knurl of the press part with poor smoothness, so that the smoothness of the ink can be obtained. The difference can be eliminated.

At this time, the hardness (Shore hardness D: JIS Z2246) of the elastic roll of the soft calender is preferably 87 to 95 °. If it exceeds 95 °, it is difficult to obtain a uniform profile, and if it is less than 87 °, the durability of the elastic roll is poor, and the smoothness is hardly obtained. Further, the surface roughness (JIS B0S01) of the elastic roll is particularly preferably less than 0.5 μπι (Rmax) in order to reduce unevenness in ink deposition on paper. Further, it is preferable to heat the metal jaw in order to smooth the surface in contact with the metal roll. In this case, the surface temperature of the metal jaw is 40 to 150 ° C., preferably 50 ° C. Up to 120 ° C, more preferably at 60 ° C to 100 ° C, even in multicolor printing where slight density unevenness is affected, the printed surface with uniform density can be It is possible to get.

The newsprint thus obtained has a preferred physical property value of 0.55 to 0.63 g / cm ² , and Oken-type smoothness (Japan Tappi No. 5) of 15 to 1 It is adjusted so that the difference between the front and back (%) of the smoothness is less than 20%. The difference between the front and back sides (%) of the smoothness is calculated by dividing the absolute value of the difference between the front and back sides (smallness) by the smoothness (seconds) of the back side. Physically according to the following equation.

Front-back difference (%) = [I (Smoothness of front surface-Smoothness of back surface) 1 / (Smoothness of back surface)]

X 100

Here, the surface of the paper is the surface in contact with the metal roll in the final press roll in the papermaking process press part, and the back surface is the surface in contact with the felt.

The pulp composing the base paper may be any ratio of chemical pulp (bleached or unbleached NKP or LKP), mechanical pulp (GP, CGP, RGP, PGW, TMP, etc.), waste paper pulp (DIP), etc. Used mixed. In addition, when making paper, it is necessary to appropriately add an inorganic siliceous inorganic pigment such as white carbon, calcining power, structured kaolin, titanium dioxide, and urea formaldehyde resin to the paper material. They can be added as appropriate.

Further, in the paper stock, generally known sizing agents such as a sulfuric acid band, a paper strength enhancer, a retention aid, a reinforced rosin sizing agent, an emulsion sizing agent, a water-proofing agent, an ultraviolet ray inhibitor, etc., together with the filler described above. The official papermaking chemicals are added, and the paper is made by the paper machine described above. In the case of the present invention, the basis weight of the base paper is not particularly limited, but is usually in the range of about 30 to 45 g / m ² . BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described specifically with reference to examples. Of course, the present invention is not limited to these embodiments. Parts and% in the examples are parts by weight and% by weight, respectively, unless otherwise specified.

(Preparation of base paper)

Refining a pulp slurry consisting of 10 parts of softwood craft pulp (NKP), 40 parts of samomechanical pulp (TMP), 10 parts of ground pulp (GP), and 40 parts of newspaper deinked waste paper panolep (DIP) Then, a pulp slurry having a freeness (CS F) of 12 Om 1 was prepared. The pulp slurry thus obtained is compared with the pulp in terms of the solid content per rosin emulsion size (Product name: SPN-773 / Rough (Kawa Chemical Co., Ltd.) 0.3%, a 1% sulfuric acid band, and 1% white carbon with an average particle size of 15 m were added and mixed to prepare a stock. Next, papermaking was performed using a gap-former type papermaking machine to obtain base paper of 40 g / m ^{2 in} rice tsubo. The pressing conditions at this time were such that the paper surface hit the felt side in the final press (the back surface hit the smooth roll).

(Preparation of newsprint)

Oxidized starch (trade name: Ace A / Oji Cornstarch) heated and dissolved in hot water was used as a surface treatment agent on both sides of the base paper obtained above. coated to a ² gZm 2, dried, under the following conditions render soft power, on so that the surface of the paper that Sessu elastic roll side (rear surface metal roll side), subjected to first nip paper feed, Newsprint paper for offset printing was obtained.

Metal roll surface temperature 80 ° C

Elastic orifice hardness 93 ° (Product name: Eragrass ZE, manufactured by Kyoyo) Elastic orifice surface roughness 0.3; m (R max)

Nib pressure 70 kg Z cm

Newspaper was obtained in the same manner as in Example 1, except that the force render specifications were set as follows.

Metal mouth surface temperature 70 ° C

Elastic roll hardness 93.

Elastic roll surface roughness 0.45 / m (Rmax)

Nip pressure 70 kg / cm. <Example 3>

A newsprint was obtained in the same manner as in Example 1 except that the specifications of the force render were set as follows.

Metal mouth surface temperature 70 ° C Elastic roll hardness: 8 9 ° (Product name: Mirror Max YCR5400 manufactured by Yamauchi)

Soft roll surface roughness 0.3 μm (R max)

Nip pressure 70 kg / cm

Metal roll surface temperature 1 20 ° C

Elastic roll hardness 9 3 °

Elastic roll surface roughness 0.α μ (Rmax)

Nip pressure 70 kg g m

Metal mouth surface temperature 50. C

Elastic roll hardness 9 3 °

Elastic roll surface roughness 0.3 μm (Rmax

Nip pressure 70 kg / cm

A pulp slurry having a ratio of 20 parts of thermomechanical pulp (TMP) and 80 parts of newspaper deinked waste paper pulp (DIP) was beaten with a refiner to prepare a pulp slurry having a freeness (csf) of 12 Om 1. The pulp slurry thus obtained was compared with the solid content in terms of solid content, and the size of the pulp was about 0.1% in size. Example 2 except that 2% carbon was added and mixed to obtain paper stock and make paper. Newsprint paper for offset printing was obtained in the same manner as in 1.

In the first embodiment, the soft calender (1) instead of 2-pass paper passing (2) Ep-paper passing , 2 two Tsu _u the surface of the paper-flop th was sheet passing] in contact with the elastic opening Lumpur side (back side metal port Lumpur surface side)

In Example 1, in place of the soft calender 1 nib passing, a machine calender 1 1 nip (metal knurling, surface temperature of the smoothing roll 60 ° C, nip pressure 70 kg / cm) was passed. Mr. went.

<Comparative Example 3)

In Example 1,! -Calender 1-sheet passing was performed upside down [so that the surface of the paper was in contact with the metal roll side (the back side was the elastic roll side)].

<Comparative Example 4)

In Example 1, a soft calender was replaced by a machined render instead of one ep-sheet passing. — 4 nips (metal knurling, surface temperature of the smoothing roll 60 ° C, nip pressure 90 kg / cm) The paper was used (a lot of paper was crushed by two-step nips, the front and back sides were different, and the meat was good, but the opacity was poor.) The surface of the newsprint paper thus obtained in Examples and Comparative Examples, The quality evaluation shown below is performed for each of the back surfaces, and the obtained results are shown in Table 1.

Smoothness

The smoothness (seconds) of each side of the printing paper was measured by the Oken-type smoothness measurement method, and the difference between the front and back sides (%) of the smoothness was calculated from the measured value by the following formula. In Table 1, this front and back The difference (%) is indicated by I% I. .

Front / back difference (%) [I Smoothness of back surface—Smoothness of front surface I / (Smoothness of back surface)]

X 1 0 0

Ink deposition

Using an offset printing machine (Komori SYSTEMC-20 / Komori Corporation), continuous printing of 100,000 copies in 4-color printing was performed, and then the ink-inking of the light-colored portions was visually judged. In Table 1, 〇, △, and X indicate the following properties.

〇: The image is clear, the ink deposition is good, and there is almost no shading unevenness. Δ: Inferiority of ink is slightly inferior, slightly lacking in sharpness, and there is little shading unevenness _u X: Image is thin and inking is thin, and Δ is inferior and shading is large.

Printing surface reflectance

0.3 ml of black ink was applied, RI printing was performed, and the reflectance (%) of the printed surface was measured using a standard color difference meter (Spectro Color Meter SE2000 / Nippon Denshoku). The surface reflectivity (smoothness, glossiness) of white paper has a large effect on the printing surface reflectance, and newer paper with a smaller value indicates better suitability for full-page printing and multicolor printing.

The difference between the front and back printing surface reflectance% is calculated by dividing the absolute value of the difference between the front and back printing surface reflectance (%) by the printing surface reflectance (%) on the back surface. In Table 1, this difference between front and back (%) is /. Indicated by 1.

Front-back difference (%) = [Degree of reflectance of the printed surface on the front surface—reflectance of the printed surface on the back surface I Z (reflectance of the printed surface on the back surface) X 100

Opacity after printing (%)

The reflectance was measured using a standard color difference meter (Spectro Color Meter SE2000 / Nippon Denshoku), and the opacity (%) after printing was determined from the measured value by the following formula. The lower the value (especially 85% or less), the lower the strikethrough and show-through.

Opacity after printing (%) =

(Printed backside reflectance after printing) Z (Printed backside reflectance before printing) X100 Table] ζ medium 5¾- force Ιώ Shinya τΛ 1 data ίί Li Ι 1丄j¾ Rikiya 1 data ¹ J Otsu夹Rikiya 1 Tari 0; ¾) t l1 Tari 4; 9:! Rikiya 1 Tari! 3 ； ¾¾ カ 1111 リ 1 1 kit kit Jil 9 ■ Cui |! 1 3 3 お / fiiil A Smoothness seconds 31 31 30 30 33 27 37 34 40 28

32 35 32 36 30 29 30 28 31 23

-1 -4-2-6 3 -2 7 6 9 5

|% | 3.1 11.4 6.2 16.6 10 6.8 23.3 21.4 29.0 21.7 Ink 〇〇〇〇〇〇〇 X 〇 △ 〜X o

Inkability 〇〇〇〇〇〇〇 X Δ △ ~ X Printed surface% 12.58 12.12 11.65 12.54 11.92 12.52 10.83 12.48 10.81 13.4 Reflectivity 12.56 11.58 12.32 10.42 12.76 12.42 12.39 13.43 13.15 13.13

0.02 0.54-0.67 2.12 -0.84 0.1 -1.56 -0.92 -2.34 0.27

|% | 0.1 4.6 5.4 20.3 6.5 0.8 12.5 7.0 17.7 2.0 After printing% 88.2 88.1 88.2 87.5 88.4 87.2 87.3 86.6 87.9 83.5 Opacity

As is evident from the results shown in Table 1, in the papermaking process, where the raw material is made, dried, and then passed through a soft calender, the paper surface in contact with the metal roll side of the soft calender is replaced by the papermaking process press part. The newsprint of the present invention, which is obtained by passing through one or two papers as a surface in contact with the felt at the final press knurl, has a good ink opacity with no difference between the front and back sides, and gives a printed matter excellent in opacity.

Claims

The scope of the claims

1. In the method of producing newsprint paper, in which the raw material mainly consisting of wood pulp, waste paper pulp, and filler is made, dried, and then passed through a soft calender, the paper passing process is one Ep.

5. A method for producing newsprint, wherein the paper surface in contact with the metal roll side of the soft calender is a surface which comes into contact with felt by a final press roll in a paper making process press part.

2. The hardness of the elastic roll of the soft calender (Shore D: JIS Z 2246) is 87 to 95 °, the surface roughness (Rmax: JIS B0601) is less than 0.5 / m, and the metal roll is

.0 method for producing newsprint Claims paragraph 1, wherein the the temperature is 4 0~ 1 5 0 ° C Le _u

3. The tension of newsprint after soft calendering is 0.55 to 0.63 g / cm2, and the Oken type smoothness (Japan Tappi No.5) is 15 to 100 seconds. The new L5 paper _u manufactured by the method according to claim 1, wherein the difference between the front and back sides of the smoothness is 20% or less.