CN1461369A - Method of mfg. newsprint - Google Patents

Abstract

The present invention optimizes the pressing conditions and soft calender processing conditions in the papermaking process to provide a newsprint for offset printing that has no difference between the inside and the outside and has excellent printability. The manufacturing method of this kind of paper uses wood pulp, waste paper pulp, and fillers as the raw materials of the main components, and in the paper manufacturing method of newspapers in which the raw materials are made into paper, dried, and treated on a soft calender, The threading process is a nip process, and the paper surface that is brought into contact with the metal roll side of the soft calender is the surface that the final press roll and the felt are in contact with in the press section of the papermaking process.

Description

How Newsprint is Made

technical field

The present invention relates to newsprint, especially a newsprint capable of blending waste paper pulp (DIP (Deinked Pulp)) in a high proportion; it is a newsprint for offset printing with excellent printing quality and no difference between the inside and the outside Manufacturing method.

Background technique

The raw material pulp used in newsprint is mainly mechanical pulp or waste paper pulp. Recently, from the perspective of environmental problems caused by increased garbage and resource conservation, there are special requirements for increasing the blending ratio of waste paper and reducing the weight per unit area. strong. On the other hand, offset printing, color printing, and high-speed printing are being developed at a high speed recently. With this development, there are more requirements for newsprint constituting printing media than before, and it is also required to improve excellent color printing adaptability and printing quality. Workability.

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 paper after being transferred to a rubber plate called a blanket. Compared with the previous letterpress printing method, due to the use of relatively high-viscosity ink, it has the advantages of less ink penetration into the paper layer and less ink bleeding after printing (greater opacity).

However, with the development of lightweight newsprint in recent years, higher requirements have been placed on high opacity after printing, and with the development of colorization, ink repellency has also been required. In order to improve the ink receptivity of paper during printing, the most common method is to use a calender to smooth it. However, if the clamping pressure of the calender is increased and the number of clamps is increased to smooth it If this is the case, the ink retentivity of the ink can be improved, but because the bulkiness of the paper is damaged, the opacity after printing will be reduced, and the rigidity will also be reduced, so that it will be damaged during printing due to wrinkles, etc. Malfunctions that cause poor travel. And even if the paper with appropriate bulk can be obtained by lightening the calender treatment, the difference between the front and the back of the paper surface is increased, especially due to the deterioration of the ink receptivity of the paper surface on the side where the smoothness is reduced. There occurs a problem that the image density is clearly different between the surface and the inside. This is considered to be because in the papermaking process, the dehydration conditions on the wire section and the press section have subtle differences between the surface and the inside, so the difference in the smoothness of newsprint between the surface and the inside occurs because of fillers in the thickness direction, fine fibers The distribution state is different between the surface and the inside, so there is a difference between the surface and the inside of the ink transfer property.

On the other hand, inorganic dyes such as hydrated silicic acid or titanium oxide, talc, or organic dyes such as urea-formaldehyde resins are commonly used as paper-making fillers as a method of improving the opacity after printing. However, when the addition rate of these fillers is increased, differences in the ink receptivity between the surface and the inside of the paper are likely to occur; and it is also related to the following failure, that is, during offset printing, the wetting water used in the printing process The filler is leached from the paper layer due to the effect of the paper powder and accumulated on the rubber felt as paper powder, so the addition rate is limited. Due to the high proportion of DIP (deinked waste paper pulp) compared with GP, RGP, TMP and other mechanical pulps, it is difficult to show high opacity, so the high proportion of DIP (deinked waste paper pulp) that is more important in the environment Proportional matching, in fact, it is difficult to make both the improvement of opacity and the high ratio of DIP to be established.

According to the situation described above, the present inventor has studied a method particularly emphatically, and it is in the newsprint that mixes waste paper pulp in a high proportion, can show good ink inking on the paper surface and inside during offset rotary printing Sex, printing opacity, and can get good printing workability. The present inventors have made the present invention based on the results of research.

The object of the present invention is to provide a newsprint which can be used in offset printing, by making the pressing conditions in the papermaking process and the processing conditions of the soft calendering machine the most suitable, so that there is no difference in printing quality between the surface and the inside of the paper, And has excellent printing workability.

disclosure of invention

The manufacturing method of the newsprint of the present invention made in order to achieve the above-mentioned purpose of the invention, it is to use wood pulp, waste paper pulp, filler as the raw material of main component to carry out papermaking, after drying, carry out the manufacture of the newsprint of paper threading treatment on the soft calender The method is characterized in that the paper threading treatment is a nip treatment, and the paper surface in contact with the metal roll side of the above-mentioned soft calender (Softocalender-) is the final press roll and felt in the press section of the papermaking process. contacting surfaces.

Newsprint can be manufactured by various paper machines. Since a double-wire paper machine commonly known as gap forming is used for manufacturing, high-speed paper with good texture can be obtained, so this machine is widely used. It forms such a structure. In other words, the gap-formed wire portion moves the paper stock between two wires, and dewaters it approximately equally from both sides. Thus having a uniform texture with less variation between the surface and the inside of the paper. On the press section after the wire section, the paper is clamped between the metal roller and the felt for press dehydration, and the moisture in the paper is pressed to the felt side in one direction, and the distribution of fine fibers and fillers in the paper layer is also It is biased to the direction of pressing and dehydration, that is, to the side surface of the felt, and the other side is pressed on a smooth hard roller (granite, metal roller, etc.) to make a smooth surface. Therefore, in the final press, the smoothness of the surface that is in contact with the smooth hard roll side is generally improved, and the paper machine calender and the soft calender that make both sides approximately equally smooth are used for secondary nip treatment. , the above-mentioned difference between the surface and the inside is maintained or amplified.

Next, after the paper is dried in the dryer part, in order to improve the surface strength of the paper and prevent paper dust during printing, a surface treatment agent is generally applied to the surface of the paper. This surface treatment agent is starch, PVA or polyester. Acrylamide etc. are used as the main components; it is a coating device generally used in the field of papermaking, such as from the known public sizing press, scraper metering sizing press, bar metering sizing press, door roller coating It is a device selected from glue machine, scraper gluing machine, bar gluing machine, bar scraper gluing machine, air knife gluing machine and other devices to apply it to the surface of the base paper.

When applying the surface treatment agent using the above-mentioned apparatus, the application amount is to be applied and dried to a dry weight of 0.05 to 1 g/m ² on one side.

After applying a surface treatment agent and drying it, if necessary, threading, pressing, and smoothing are performed on a calender to finish it into a product. As the calender device used at this time, it is usually a paper machine calender composed of a metal roll/metal roll combination. Tendency to disparate, not very ideal device.

The calender used in the present invention is a so-called soft calender, which is made of a metal roll and an elastic roll (generally a roll covered with a pulp roll or a durable resin material such as polyamide resin) Compared with the finishing of the previous paper machine calender composed of only metal rollers, it can reduce the uneven density after calendering caused by the uneven texture of the paper layer. As a result, in offset printing, especially In printing with many colors, it is possible to obtain a printing surface with uniform density without uneven ink absorption.

The above-mentioned soft calender has been widely used so far, but in order to eliminate the usual difference between the surface and the inside through the roll treatment of two materials with different properties, the metal roll and the elastic roll, the same paper surface is alternately contacted with the metal roll and the elastic roll. Threading more than 2 clamps. On the other hand, in the present invention, in order to eliminate the difference between the surface and the back that has occurred before the pressing part, and to maintain the bulkiness and ensure the opacity, only one nip threading is required. At this time, the paper surface of the paper that is in contact with the metal roll side corresponds to the surface of the final press roll in the press section of the papermaking process that is in contact with the felt, so that smoothness without differences between the inside and the outside can be obtained. ink retentivity. That is, the smoother surface of the metal roll of the soft calender is pressed against the paper surface on the side of the final press roll in contact with the felt in the less smooth press section, thereby eliminating smoothness and inking Sexual differences.

At this time, the hardness of the elastic roll of the soft calender (Shore hardness D: JIS Z2246) is preferably 87-95°. When it exceeds 95°, it becomes difficult to obtain a uniform shape; when it is less than 87°, the durability of the elastic roller deteriorates, making it difficult to exhibit smoothness. In addition, the surface roughness (JISB0601) of the elastic roller is preferably less than 0.5 μm (Rmax), in which case the unevenness of ink receptivity on the paper surface can be reduced. In order to increase the smoothness of the paper surface in contact with the metal roll, it is preferable to heat the metal roll. However, the surface temperature of the metal roller at this time can be taken as 40-150°C, preferably 50-120°C, and preferably treated at a temperature of 60-100°C. Even in multi-color printing affected by the influence, a printed surface with uniform density without difference between the front and the back can be obtained.

Among the physical properties of newsprint obtained in this way, the compactness is preferably 0.55 to 0.63 g/cm ² , the Wangyan type smoothness (Japan Tappi No. 5) is 15 to 100 seconds, and the difference (%) between the front and back of the smoothness is determined by Adjust to below 20%. Here, the difference (%) of the smoothness is calculated by dividing the absolute value of the difference between the smoothness (seconds) by the inner smoothness (seconds), and the specific numerical value can be calculated by the following formula.

Difference between surface and interior (%)=[|(Smoothness of surface - smoothness of inside)|/(Smoothness of inside)]×100

Here, the surface of the paper refers to the surface in contact with the metal roll of the final press roll in the press section of the papermaking process; the so-called inner surface refers to the surface in contact with the felt.

Chemical pulp (bleached or unbleached NKP or LKP, etc.), mechanical pulp (GP, CGP, RGP, PGW, TMP, etc.), waste paper pulp (DIP), etc., are mixed in any proportion and used as constituent base paper pulp. When making paper, amorphous silicon-based inorganic dyes such as white carbon, calcined kaolin, structured kaolin, and titanium dioxide, urea-formaldehyde resin, etc. filler.

Moreover, in the above-mentioned paper materials, sizing agents such as (alum) alum, paper strength enhancer, yield-enhancing agent, reinforced rosin sizing agent, emulsion sizing agent, water resistance agent, and ultraviolet ray prevention agent can also be added together with the above-mentioned filler. Commonly known and commonly used chemicals for papermaking, such as chemicals, are used to make paper with the above-mentioned paper machine. In 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 .

The best way to practice the invention

Hereinafter, the present invention will be described concretely by way of examples. Of course, the present invention is not limited to these examples. Moreover, the parts and % in the examples only represent parts by weight and % by weight, respectively, unless there is a reminder in advance.

(Example 1)

(Creation of base paper)

The ratio of 10 parts by weight of coniferous kraft pulp (NKP), 40 parts by weight of thermomechanical pulp (TMP), 10 parts by weight of substrate pulp (GP), and 40 parts by weight of news deinked paper pulp (DIP) constitutes liquid slurry. The refiner beats this slurry to produce a slurry with a freeness (CSF) of 120 ml. In the liquid slurry thus obtained, according to the comparison of the solids, 0.3% of the pulp rosin latex filler (trade name: SPN-773/Arakawa Chemical Industry Co., Ltd.), 1% of (alum) alum, and an average particle diameter of 15 μm were added respectively. White carbon ink 1%, and mixed to make paper stock. Next, papermaking was carried out with a gap forming paper machine to obtain base paper with a basis weight of 40 g/m ² . The pressing condition at this time is that the surface of the paper is in contact with the felt side in the final press (the inner surface is in contact with the smooth roll).

(making newsprint)

With a gate roll coater, the oxidized starch (trade name: エ-スA/Oji Ko-nsta-chi company) that has been heated and dissolved with hot water is coated on both sides of the base paper prepared above, and dried to form After the dry weight on one side is 0.2 g/m ² , the surface of the paper is brought into contact with the elastic roll side (the back side is with the metal roll side) on a soft calender under the following conditions, and the nip drawing is performed once. paper, resulting in newsprint for offset printing.

Metal roller surface temperature 80℃

Elastic roller hardness 93° (trade name: エラグラスZE, manufactured by Kinyosha)

Surface roughness of elastic roller 0.3μm(Rmax)

Clamping pressure 70kg/cm

(Example 2)

Newsprint was produced in the same manner as in Example 1, except that the calender specifications in Example 1 were set to the following conditions.

Metal roller surface temperature 70℃

Elastic roller hardness 93°

Surface roughness of elastic roller 0.45μm(Rmax)

Clamping pressure 70kg/cm

(Example 3)

Newsprint was produced in the same manner as in Example 1, except that the calender specifications in Example 1 were set to the following conditions.

Metal roller surface temperature 70℃

Elastic roller hardness 89° (product name: ミラ-マツクス YCR5400, manufactured by Yamauchi)

Surface roughness of elastic roller 0.3μm(Rmax)

Clamping pressure 70kg/cm

(Example 4)

Newsprint was produced in the same manner as in Example 1, except that the calender specifications in Example 1 were set to the following conditions.

Metal roller surface temperature 120℃

Elastic roller hardness 93°

Surface roughness of elastic roller 0.3μm(Rmax)

Clamping pressure 70kg/cm

(Example 5)

Newsprint was produced in the same manner as in Example 1, except that the calender specifications in Example 1 were set to the following conditions.

Metal roller surface temperature 50℃

Elastic roller hardness 93°

Surface roughness of elastic roller 0.3μm(Rmax)

Clamping pressure 70kg/cm

(Example 6)

A liquid slurry is formed with a ratio of 20 parts by weight of thermomechanical pulp (TMP) and 80 parts by weight of deinked newspaper pulp (DIP), and this liquid slurry is beaten with a refiner to produce a liquid with a freeness (CSF) of 120ml pulp. In the liquid slurry thus obtained, according to the comparison of the solids, 0.3% of the pulp rosin latex filler (trade name: SPN-773/Arakawa Chemical Industry Co., Ltd.), 1% of (alum) alum, and an average particle diameter of 15 μm were added respectively. Light-colored carbon 2%, and mixed to obtain paper stock and papermaking. Except for the rest, newsprint for offset printing was produced in the same manner as in Example 1.

(comparative example 1)

Instead of the soft calender in Example 1, nip the paper once and carry out the paper nip twice [that is, make the surface of the paper and the metal roll side (the inner side and the elastic roll side) correspond to each other when the first nip is done. Contact, during the second nip, the surface of the paper is in contact with the side of the elastic roller (the inner side is in contact with the side of the metal roller), and the paper is threaded].

(comparative example 2)

Instead of the soft calender in Example 1 clamping the paper once, and carrying out the paper machine calender once clamping (that is, processing with metal rolls, smooth (summing) roll surface temperature 60 ° C, clamping pressure 70 kg/ cm) lead paper.

(comparative example 3)

Instead of the soft calender in Example 1, which clamps the paper once, and carries out the opposite of the front and back described in Example 1 [making the surface of the paper contact with the metal roll side (the inner side is in contact with the elastic roll side)] Paper.

(comparative example 4)

Instead of the soft calender in Example 1 clamping the paper once, carry out the paper machine calender 4 times clamping (i.e., processing with metal rolls, smooth roll surface temperature 60°C, clamping pressure 90kg/cm) Paper (Multi-stage clamping is used, and the paper is quite looped; this comparative example is an example in which the front-to-back difference and ink retentivity are improved, but the opacity is deteriorated).

Table 1 shows the results obtained by performing the following quality evaluations on the surface and back of the newsprints described in the above Examples and Comparative Examples, respectively.

smoothness

The smoothness (seconds) of the surface and the back of the paper used for printing was measured by the Oken-type smoothness measurement method, and the difference (%) of the smoothness between the front and back was obtained from the measured values according to the following formula. These differences (%) are shown in Table 1 in %.

The difference between the surface and the inside (%)=[|Smoothness of the inside-Smoothness of the surface|/(Smoothness of the inside)]×100

ink repellency

Using an offset printing machine (Komori SYSTEMC-20/Komori Corporation), 10,000 pieces of 4 kinds of color printing were continuously performed, and the ink retentivity of the light-colored portion was visually judged. Marks of ◯, △ and × in Table 1 indicate the following properties.

○: The image is clear, the ink retentivity is good, and there is almost no unevenness in shading.

△: The ink settling property is slightly deteriorated, the vividness is slightly inferior, and the unevenness of shading is small.

×: The image is light, and the ink retentivity is deteriorated, and the unevenness of shading is large. Reflectivity of printed surface

RI printing was performed with 0.3 ml of black ink, and the reflectance (%) of the printed surface was measured using a standard color difference meter (Spectrocarra-Me-Ta-SE2000/Nippon Denshoku). The surface properties (smoothness, glossiness) of white paper have a great influence on the reflectivity of the printing surface. Newsprint with a small value has excellent adaptability to full-surface printing and multi-color printing.

The front-to-back difference % of the printed surface reflectance is calculated by subtracting the absolute value of the difference between the surface and the back printed surface reflectance (%) by the inner printed surface reflectance (%), and is specifically determined by the following formula. In Table 1, |%| represents the above-mentioned difference (%) between the inside and outside of the table.

Difference between front and back (%)=[|reflectance of printing surface on the surface-reflectance of printing surface inside|/(reflectance of printing surface inside)]×100

Opacity after printing (%)

The reflectance was measured using a standard color difference meter (Spectrocara-Me-ta-SE2000/Nippon Denshoku), and the opacity (%) after printing was calculated|required from this measured value with the following formula. The lower the value (especially below 85%), the stronger the ink bleeding and permeability.

Opacity after printing (%) = (reflectance of printed surface after printing) / (reflectance of printed surface before printing) × 100

Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 smoothness Second The difference between the inside and the outside of the surface |%| 3132-13.1 3135-411.4 3032-26.2 3036-616.6 3330310 2729-26.8 3730723.3 3428621.4 4031929.0 2823521.7 ink repellency surface inside ○○ ○○ ○○ ○○ ○○ ○○ ○○ ×× ○△ △～×△～× Printing surface reflectance % The difference between the inside and the outside of the surface |%| 12.5812.560.020.1 12.1211.580.544.6 11.6512.32-0.675.4 12.5410.422.1220.3 11.9212.76-0.846.5 12.5212.420.10.8 10.8312.39-1.5612.5 12.4813.43-0.927.0 10.8113.15-2.3417.7 13.413.130.272.0 Opacity after printing % 88.2 88.1 88.2 87.5 88.4 87.2 87.3 86.6 87.9 83.5

As can be seen from the results shown in Table 1, with the method of the present invention, that is, after the raw material is made into paper and dried, in the paper manufacturing method for newspapers that carries out the paper threading process on the soft calender, the soft calender is combined with the soft calender. The paper surface that is in contact with the metal roll side of the papermaking process is used as the surface that is in contact with the felt on the final press roll in the press section of the papermaking process, and is treated with a nip thread, and the ink used for newspaper paper obtained thereby There is no difference in ink receptivity, and a printed matter with excellent opacity can be given.

Claims (3)

1. the manufacture method of newsprint, be with wood pulp, old paper stock, filler raw material as main component, after with this raw material papermaking, drying, on soft press-polishing machine, carry out the manufacture method of the newsprint of paper injection processing, it is characterized in that, it is that 1 clamping is handled that paper injection is handled, and with the contacted paper of metallic roll side of soft press-polishing machine be contacted of final pressure roller in papermaking operation press sections and felt.

2. the manufacture method of newsprint as claimed in claim 1 is characterized in that, the hardness of the resilient roller of soft press-polishing machine (Shao Er D:JIS Z 2246) is that 87～95 °, surface roughness (Rmax:JIS B0601) are less than 0.5 μ m; And, the temperature of metallic roll is 40～150 ℃.

3. the newsprint made from the described method of claim 1 is characterized in that, the tightness of the newsprint after soft press-polishing machine is handled is 0.55～0.63g/cm ², Wang Yan formula smoothness (JapanTappi No.5) is that difference is below 20% in 15～100 seconds, the table of smoothness.