Paper processing equipment, paper preparation method and paper

Abstract

The invention discloses paper processing equipment, a paper preparation method and paper, relates to the technical field of papermaking, and aims at solving the problems that waste is large during paper changing, and white water treatment burden is large. The paper processing equipment comprises a pulp processing part, a paper forming part, a dyeing part and a drying part which are connected in sequence; the dyeing part comprises two dyeing rollers which are oppositely arranged and is used for dyeing the two surfaces of the base paper dried by the paper forming part; the drying part comprises a first drying device and a second drying device, and a water outlet of the first drying device is connected with a water inlet of the second drying device.

Description

Technical Field

[0001] The present application relates to the technical field of papermaking, and in particular to a paper processing device, a method for preparing paper, and paper. Background Art

[0002] With the improvement of the consumption level, colored paper is used more and more in the existing segmented market. At present, the common preparation processes of colored paper include in-pulp dyeing and post-processing dyeing of white paper. However, since the in-pulp dyeing process includes the re-forming, drying, wrinkling, coiling of the pulp fibers after dyeing, and finally to the finished product, there are problems such as color difference in the transition of each color, color difference between batches, and waste such as the cleaning of each pulp tank system caused by the shutdown when switching to white paper. In addition, there is the problem of high chemical consumption in the in-pulp dyeing of the paper web, which brings a heavy load on wastewater treatment.

[0003] In the preparation method of dyeing other patterns after post-processing dyeing of white paper, due to the vacuum suction circular hole marks formed on the paper surface by the action of vacuum pressing, these marks have no problem in the normal use of white paper, but in the process of pure-color printing and dyeing using white paper as the base paper, after the paper web is wetted, due to the uneven absorption of dyes / pigments caused by the vacuum suction circular hole marks, it is easy to cause the problem of printing mottling. Since the original paper has been put on the machine at this time and there is no room for adjustment, it will cause unnecessary waste. And there is no detection means to detect the vacuum suction circular hole marks during the production process, which brings great uncertainty to the production of the base paper used for this printing and dyeing. Summary of the Invention

[0004] The purpose of the present application is to provide a paper processing device, a method for preparing paper, and paper for preparing dyed paper.

[0005] In order to achieve the above purpose, the present application provides the following technical solutions:

[0006] A paper processing device, the paper processing device includes a pulp processing part, a paper forming part, a dyeing part, and a drying part connected in sequence;

[0007] The dyeing part includes two relatively arranged dyeing rollers for dyeing both sides of the paper web dried by the paper forming part;

[0008] The drying part includes a first drying device and a second drying device, and the water outlet of the first drying device is connected to the water inlet of the second drying device.

[0009] Compared with the prior art, in the paper processing equipment provided by the present application, by arranging a dyeing section behind the paper forming section, and the dyeing section includes two relatively arranged dyeing rollers, the two relatively arranged dyeing rollers can be used to perform online dyeing on both sides of the base paper obtained after drying the paper forming section. In this case, only by injecting the dye into the dyeing rollers and performing online dyeing on the already formed base paper, dyed paper can be obtained. When it is necessary to convert the color of the paper, only by replacing the dye in the dyeing rollers can the color change of the paper be achieved, and the replacement method of the dye in the dyeing rollers is relatively simple. For example, the dyeing rollers can be disconnected, cleaned, and then injected with the target dye to re-dye the base paper, thus avoiding the waste of the sizing material and the dye during the paper modification by internal sizing dyeing, the waste of cleaning each sizing tank system caused by the downtime when switching to white paper production, and the problem of the wastewater treatment load during internal sizing dyeing.

[0010] Meanwhile, by arranging a drying section behind the dyeing section, it is possible to judge whether the dyeing result of the dyed paper after drying by the drying section meets the expectation, and make timely adjustments, so as to flexibly adjust the paper color and the paper dyeing effect, solve the problem of large color difference during the transition of each color and the color difference between batches, and improve the paper dyeing effect. Based on this, by arranging the dyeing section behind the paper forming section and arranging a drying section behind the dyeing section, the paper dyeing effect can be visually seen. If there is a problem of printing mottling, timely adjustments can be made, reducing unnecessary waste and lowering the cost.

[0011] The present application also provides a method for preparing paper, and the method for preparing paper includes:

[0012] Pre-treating fiber raw materials and additives in a sizing material treatment section to obtain a base paper;

[0013] Feeding the base paper into the paper forming section for pressing treatment;

[0014] Feeding the pressed base paper into the dyeing section for dyeing treatment to obtain a dyed base paper;

[0015] Drying the dyed base paper to obtain dyed paper.

[0016] Compared with the prior art, the beneficial effects of the method for preparing paper provided by the present application are the same as those of the paper processing equipment described in the above technical solution, and will not be elaborated here.

[0017] The present application also provides a kind of paper, and the paper is prepared by the method for preparing paper provided by the embodiments of the present application.

[0018] Compared with the prior art, the beneficial effects of the paper provided by the present application are the same as those of the paper processing equipment described in the above technical solution, and will not be elaborated here. Description of the Drawings

[0019] The accompanying drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0020] Figure 1 A schematic structural diagram of a paper processing device provided by an embodiment of the present application is shown;

[0021] Figure 2 A flowchart of a method for preparing paper provided by an embodiment of the present application is shown. Detailed implementation manners

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] With the improvement of the consumption level, colored paper is used more and more in the existing market segments, mainly including solid-color tissue paper of various colors, color printing, and dyed-printing napkins. The preparation methods of the colored paper may include in-pulp dyeing, printing patterns after in-pulp dyeing provides the source of the background color, and dyeing the white paper in post-processing and then laminating other patterns. Among them, because in-pulp dyeing can ensure less dye consumption at low grammage to ensure uniform dyeing, good lightfastness and bleeding fastness of the formed paper, and less white water load, in-pulp dyeing is used as the mainstream method for preparing colored paper.

[0024] However, the inventors found that since the process of in-pulp dyeing includes the re-forming, drying, wrinkling, and winding of the pulp fibers after dyeing, and finally to the finished product, there are problems such as color difference in the transition of each color, color difference between batches, and waste problems such as the cleaning of each pulp tank system caused by the shutdown when switching to white paper. In addition, there is a problem of wastewater treatment load caused by large chemical consumption in the in-pulp dyeing of the paper web.

[0025] In the preparation method of dyeing the white paper in post-processing and then laminating other patterns, due to the vacuum suction round hole marks formed on the paper surface by the action of vacuum pressing, there is no problem with these marks in the normal use of white paper. However, during the process of pure-color printing using white paper as the base paper, uneven absorption of dyes / pigments is caused by the vacuum suction round hole marks after the paper web is wetted, which easily leads to the problem of printing mottling. Since the base paper has been put on the machine at this time and there is no room for adjustment, it will cause unnecessary waste. And there is no detection means for detecting the vacuum suction round hole marks during the production process, which brings great uncertainty to the production of the base paper used for this printing.

[0026] Figure 1 shows a schematic structural diagram of a paper processing device provided by an embodiment of the present application. As Figure 1 shown, in order to overcome the above problems, an exemplary embodiment of the present application provides a paper processing device 100, which includes a pulp processing unit 110, a paper forming unit 120, a dyeing unit 130, and a drying unit 140 connected in sequence.

[0027] As Figure 1 shown, the above-mentioned dyeing unit 130 includes two relatively arranged dyeing rollers 131 for dyeing both sides of the base paper dried by the paper forming unit 120. It should be understood that the two relatively arranged dyeing rollers 131 here can be stacked along the gravity direction or stacked in a direction with a certain angle to the gravity direction, so that the base paper dried by the paper forming unit 120 can pass through the middle of the two dyeing rollers 131 and be dyed. The dyeing roller 131 involved in the embodiment of the present application is a dyeing reticulated roller, which is a commercially available product. As long as the dyeing roller that can meet the requirements of the present application can be used in the present application, its specific model and manufacturer are not limited here.

[0028] As Figure 1 shown, the above-mentioned drying unit 140 includes a first drying device 141 and a second drying device 142, and the water outlet of the first drying device 141 is connected to the water inlet of the second drying device 142. By setting two drying devices and connecting the water outlet of the first drying device 141 to the water inlet of the second drying device 142, the high-temperature condensed water in the first drying device 141 can continue to flow into the second drying device 142 for utilization, so that the high-temperature wastewater can be reused, reducing the production cost. At the same time, since the temperature of the first drying device 141 is higher than that of the second drying device 142, when the dyed base paper is dried in drying devices at different temperatures, the warping of the paper can be adjusted, which is convenient for subsequent processes to carry out reprocessing and improves the yield of dyed paper.

[0029] As a possible implementation manner, as Figure 1 shown, the above-mentioned paper forming unit 120 includes a pressing device 121 and a third drying device 122. The third drying device 122 is located between the paper forming unit 120 and the dyeing unit 130, and the water outlet of the third drying device 122 is connected to the water inlet of the first drying device 141. By setting the third drying device 122, the pulp pressed by the pressing device 121 can be initially dried, greatly improving the strength of the paper web and providing transmission support for the paper web during the drying process. At the same time, the condensed water in the third drying device 122 is introduced into the first drying device 141 and the second drying device 142 for continuous use, so that the high-temperature wastewater can be reused, reducing the production cost and being more environmentally friendly.

[0030] As a possible implementation manner, asFigure 1 As shown, the above-mentioned formed paper section 120 may include a vacuum press roll.

[0031] As a possible implementation, as Figure 1 shown, the drying temperature of the above-mentioned first drying device 141 is 88°C to 98°C. For example, the drying temperature of the first drying device 141 may be 88°C, 92°C, 98°C, etc., and is not limited thereto. The drying temperature of the second drying device 142 is 65°C to 98°C. For example, the drying temperature of the second drying device 142 may be 65°C, 72°C, 98°C, etc., and is not limited thereto.

[0032] The embodiment of the present application also provides a method for preparing paper, which is used to prepare dyed paper. Figure 2 shows a flowchart of the method for preparing paper provided by the embodiment of the present application. As Figure 2 shown, the method for preparing paper may include:

[0033] Step 210: Pretreat the fiber raw material and the additive in the pulp processing section to obtain wet paper.

[0034] In practical applications, softwood pulp and bamboo pulp can be ground to obtain pretreated pulp, then additives are added to the pretreated pulp to obtain pulp, and finally the pulp is formed to obtain wet paper. It should be noted that the aspect ratio of the selected softwood pulp ≥ 60 and the coarseness ≤ 0.16 mg / m. By selecting softwood pulp with a smaller coarseness, its fibers are slender and the cell walls are thinner, which is easier to beat and more power-saving. At the same time, it avoids the phenomenon of uneven dyeing caused by the possible shedding of broad-leaved ducts during dyeing. Based on this, using bamboo pulp with a longer fiber length in combination with softwood pulp to prepare a mixed sauce can improve the dyeing uniformity of the paper.

[0035] The above pulping treatment may include first pulping softwood pulp using a low-consistency refiner to obtain softwood pulp stock, pulping bamboo pulp using a high-consistency refiner to obtain bamboo pulp stock, and then mixing the softwood pulp stock and the bamboo pulp stock and using a low-consistency refiner for finishing pulping to obtain pretreated pulp. Among them, the pulping consistency of the softwood pulp is 4.2% - 4.8%, and the beating degree is 27°SR - 32°SR. For example, the pulping consistency of the softwood pulp can be 4.2%, 4.5%, 4.8%, etc., which is not limited to this; the beating degree of the softwood pulp is 27°SR, 30°SR, 32°SR, etc., which is not limited to this. The pulping consistency of the bamboo pulp is 20% - 24%, and the beating degree is 23°SR - 26°SR. For example, the pulping consistency of the bamboo pulp can be 20%, 22%, 24%, etc., which is not limited to this; the beating degree of the bamboo pulp is 23°SR, 25°SR, 26°SR, etc., which is not limited to this. Among them, due to the slender fibers of the softwood pulp, low-consistency pulping can be used to reduce fiber cutting and avoid excessive fines in the pulp. At the same time, due to the relatively long fiber length of the bamboo pulp, high-consistency pulping can be used to reduce the content of fines, retain the length of the bamboo pulp as much as possible, improve the strength of the formed paper, and avoid the situation of affecting dehydration due to the increase in fines. The pulping consistency selected for finishing pulping is 3.2% - 3.6%, and the beating degree is 26°SR - 34°SR. For example, the pulping consistency selected for finishing pulping can be 3.2%, 3.5%, 3.6%, etc., which is not limited to this; the beating degree selected for finishing pulping is 26°SR, 32°SR, 34°SR, etc., which is not limited to this.

[0036] Since the roll coating time of the paper in the preparation process of the present application is short, the use effect of the wet strength agent is poor, and starch needs to be used to improve the wet strength of the paper. In this case, the above additives may include a wet strength agent and starch. Among them, the addition amount of the wet strength agent per ton of paper is 3 kg / t - 5 kg / t, and the addition amount of starch per ton of paper is 0.5 kg / t - 1 kg / t. For example, the addition amount of the wet strength agent per ton of paper can be 3 kg / t, 4 kg / t, 5 kg / t, etc., which is not limited to this; the addition amount of starch per ton of paper is 0.5 kg / t, 0.7 kg / t, 1 kg / t, etc., which is not limited to this.

[0037] Exemplarily, the above starch can be cationic starch. By adding cationic starch to the pretreated pulp, the wet paper web can obtain the necessary temporary wet strength to reduce the occurrence of paper breakage during online roll coating and facilitate the coating operation. At the same time, as a starch raw material with a positive charge, it can adsorb negatively charged papermaking fibers, and improve the retention of fines through charge neutralization and patch mechanism, etc., playing a role in retention and filtration aid. Moreover, the wet strength provided by the starch is beneficial to reducing the dosage of the wet strength agent and improving the biodegradability of the paper.

[0038] Step 220: Feed the wet paper into the paper forming section to obtain a dried base paper. It should be understood that the paper forming section here may include a pressing section and a third drying device, where the pressing section may be a vacuum pressing roll. At this time, the wet paper can be fed into the vacuum pressing roll for pressing treatment to reduce the moisture in the wet paper, facilitating subsequent drying treatment to obtain a dried base paper.

[0039] To improve the dryness of the base paper before dyeing, avoid paper breakage, and improve the dyeing effect, after the wet paper is fed into the pressing device of the paper forming section for pressing treatment, a base paper to be dried is obtained. Then, the base paper to be dried can be fed into the third drying device for drying treatment to obtain a dried base paper. It should be understood that the third drying device here may be equipment such as a Yankee dryer, and there is no limitation here.

[0040] Step 230: Feed the dried base paper into the dyeing section for dyeing treatment to obtain a dyed base paper.

[0041] In practical applications, the dried base paper can be output through the relatively arranged dyeing rollers to obtain a dyed base paper. At this time, the relatively arranged dyeing rollers contain pre-dyed dyes. When it is necessary to change the paper color, only the dyes in the dyeing rollers need to be changed, reducing the waste of pulp and dyes and the burden of white water treatment, reducing production costs and being more environmentally friendly.

[0042] Step 240: Dry the dyed base paper to obtain a dyed paper. Exemplarily, the dyed base paper can be fed into the first drying device for drying treatment to obtain a pre-dried dyed paper; the pre-dried dyed paper is fed into the second drying device for drying treatment to obtain a dyed paper. Among them, the water inlet of the first drying device is connected to the water outlet of the third drying device, so as to introduce the high-temperature condensed water generated after drying by the third drying device into the second drying device to preheat the second drying device. At the same time, the water inlet of the second drying device is connected to the water outlet of the first drying device. By drying through two drying devices with gradually decreasing temperatures, it is possible to adjust the warping of the paper sheet while reducing energy consumption and cost.

[0043] Compared with the prior art, the beneficial effects of the method for preparing paper provided by the embodiments of the present application are the same as those of the above-mentioned paper processing equipment, and will not be elaborated here.

[0044] Since the surface of the paper after pressing treatment by the pressing device usually has multiple round hole-shaped imprints, and there is a situation of uneven absorption of dyes / pigments during dyeing, which is likely to cause printing mottling problems. To avoid the above problems, before drying the dyed base paper to obtain a dyed paper, the paper forming parameters of the paper forming section can be adjusted according to the feedback of the paper surface of the dyed base paper.

[0045] For example, when the above-mentioned paper forming section includes a pressing device and a third drying device, the vacuum degree of the pressing device included in the paper forming section can be adjusted to achieve adjustment of the spacing, size, etc. of the circular hole-type imprints, thereby improving the problem of printing flowery spots and improving the dyeing effect of the dyed paper.

[0046] In practical applications, the vacuum degree of the vacuum pressing roller can be adjusted in real time according to the feedback of the paper surface of the dyed base paper before being sent to the first drying device, the feedback of the paper surface of the pre-dried dyed paper before being sent to the second drying device, or the feedback of the paper surface of the dyed paper after being dried by the second drying device, so as to balance the relationship between the pressing line pressure and the circular hole type mark, thereby maximizing the pressing line pressure, increasing the mechanical dehydration efficiency, and reducing the energy consumption of the drying section.

[0047] The embodiment of the present application also provides a paper, which is made by the method for making paper provided by the exemplary embodiment of the present application.

[0048] Compared with the prior art, the beneficial effects of the paper provided in the embodiment of the present application are the same as the beneficial effects of the above-mentioned method for preparing the paper, which will not be described in detail here.

[0049] The present application is further described below by way of examples, but the present application is not limited to the scope of the examples. The experimental methods without specific conditions in the following examples are selected according to conventional methods and conditions, or according to the product instructions.

[0050] Example 1

[0051] This embodiment is used to first prepare 16g / ㎡ sapphire blue paper napkin base paper and then change the color to prepare 16g / ㎡ dark green paper napkin base paper. The selected fiber raw materials include Norwegian red pine bleached sulphate conifer pulp and bleached bamboo pulp with a mass ratio of 15:85. The Norwegian red pine bleached sulphate conifer pulp has an aspect ratio of 80, a coarseness of 0.15, a whiteness of 88.0, a pulping concentration of 4.2%, and a beating degree of 27°SR. The bleached bamboo pulp has a whiteness of 85.0, a pulping concentration of 24%, and a beating degree of 26°SR. The pulping concentration selected during the leveling mill is 3.6%, and the beating degree is 34°SR. The amount of wet strength agent added per ton of paper is 4kg / t, and the amount of cationic starch added per ton of paper is 0.6kg / t. By observing the surface of the paper sheet after dyeing in the latter stage, the pressing vacuum degree is adjusted to -30kpa, and the pressing line pressure is 86N / mm to ensure that there is no vacuum roller suction mark.

[0052] Step 1: Preparation of wet paper

[0053] The softwood pulp is fed into a low-consistency refiner for refining to obtain softwood pulp stock. The bamboo pulp is fed into a high-consistency refiner for refining to obtain bamboo pulp stock. The softwood pulp stock and the bamboo pulp stock are mixed and evenly refined using a low-consistency refiner to obtain pretreated pulp. Additives are added to the pretreated pulp to obtain pulp, and the pulp is formed to obtain wet paper.

[0054] Step 2: Treatment of the paper before dyeing

[0055] The wet paper is fed into a vacuum press roll for pressing treatment, and then the pressed wet paper is fed into a third drying device for drying treatment to obtain a dried base paper. Among them, the vacuum degree of the vacuum press roll is -30 Kpa, and the line pressure is 86 N / mm.

[0056] Step 3: Dyeing treatment of the dried base paper

[0057] The dried base paper is fed into a relatively arranged dyeing engraved roll for dyeing treatment to obtain a dyed base paper. The dyed base paper is fed into a first drying device for drying treatment to obtain a pre-dried dyed paper, and then the pre-dried dyed paper is fed into a second drying device for drying treatment to obtain a dyed paper. Among them, the engraving pattern of the dyeing engraved roll is 120 mesh, the drying temperature of the first drying device is 98 °C, and the drying temperature of the second drying device is 98 °C. The dye used is a sapphire blue direct dye (Tianjin Xiangrui Company, sapphire blue 4BL), diluted with condensed water to 10%, filtered and then applied and transferred to the engraved roll, with an ink application amount of 8% (by weight). The color of the finished paper is L* = 54.4, a* = 1.75, b* = -28.5. Take 100 g from the dried dyed paper and conduct a weighing test according to relevant standard requirements. Determine the moisture content of the sample ≤ 9% based on the difference in mass before and after drying the sample, indicating that the dyed paper in this example meets the drying requirements.

[0058] Step 4: Color change of the dyed paper

[0059] The dye used is a dark green direct dye (Tianjin Xiangrui Company, product number dark green NF), diluted with condensed water to 9%, filtered and then applied and transferred to the engraved roll, with an ink application amount of 7.5% (by weight, that is, the dye addition amount is 7.5 kg / t of paper). The dried base paper in Step 2 is subjected to color change treatment to obtain a dyed base paper. The dyed base paper is fed into a first drying device for drying treatment to obtain a pre-dried dyed paper, and then the pre-dried dyed paper is fed into a second drying device for drying treatment to obtain a dyed paper. The drying temperature of the first drying device is 98 °C, and the drying temperature of the second drying device is 98 °C. Take 100 g from the dried dyed paper and conduct a weighing test according to relevant standard requirements. Determine the moisture content of the sample ≤ 9% based on the difference in mass before and after drying the sample, indicating that the dyed paper in this example meets the drying requirements. The color of the finished paper is L* = 31.2, a* = -10.0, b* = 16.0.

[0060] In this embodiment, after the gemstone blue napkin paper is wound up, the engraved roll is disengaged, and the dye in the feeding chamber is emptied and recycled and then cleaned. After re-injecting the prepared dark green dye, the dyeing process can be carried out. The overall equipment does not stop during this process. It takes 10 minutes to replace the dye, during which 10 minutes of undyed paper is produced. Calculated based on the set paper machine speed and width, and a production rate of 7.0 t / h, a total of 1.16 t of undyed finished paper is produced. Since this paper is disengaged from the dyeing roll and not dyed, it can be slit and sold as ordinary white paper without waste. The consumption of clear water for cleaning the dyeing engraved roll is 1 m 3 , no dye is wasted, and there is no additional white water treatment load.

[0061] Example 2

[0062] This embodiment is used to first prepare 20 g / ㎡ dark green paper napkin base paper and then change its color to prepare 20 g / ㎡ gemstone blue paper napkin base paper. The selected fiber raw materials include bleached sulfate softwood pulp of European spruce tree species and bleached bamboo pulp with a mass ratio of 10:90. Among them, the aspect ratio of the bleached sulfate softwood pulp of European spruce tree species is 75, the coarseness is 0.16, the whiteness is 87.8, the beating consistency is 4.6%, the beating degree is 28°SR, the whiteness of the bleached bamboo pulp is 85.0, the beating consistency is 20%, the beating degree is 23°SR. When performing refining, the selected beating consistency is 3.2% and the beating degree is 26°SR. The addition amount of wet strength agent per ton of paper is 3 kg / t, and the addition amount of cationic starch per ton of paper is 0.5 kg / t. By observing the surface condition of the paper sheet after dyeing in the later stage, the press vacuum is adjusted to -32 kPa and the press line pressure is 88 N / mm to ensure that there are no suction marks of the vacuum roll.

[0063] Step 1: Preparation of wet paper

[0064] The softwood pulp is fed into a low-consistency refiner for refining to obtain softwood pulp stock. The bamboo pulp is fed into a high-consistency refiner for refining to obtain bamboo pulp stock. The softwood pulp stock and the bamboo pulp stock are mixed and then refined using a low-consistency refiner to obtain pretreated pulp. Additives are added to the pretreated pulp to obtain pulp, and the pulp is formed to obtain wet paper.

[0065] Step 2: Treatment of the paper before dyeing

[0066] The wet paper is fed into a vacuum press roll for pressing, and then the pressed wet paper is fed into a third drying device for drying to obtain dried base paper. Among them, the vacuum of the vacuum press roll is -32 Kpa and the line pressure is 88 N / mm.

[0067] Step 3: Dyeing treatment of the dried base paper

[0068] Feed the dried base paper into the relatively arranged dyeing anilox rollers for dyeing treatment to obtain a dyed base paper. Feed the dyed base paper into the first drying device for drying treatment to obtain a pre-dried dyed paper. Then feed the pre-dried dyed paper into the second drying device for drying treatment to obtain a dyed paper. Among them, the screen pattern of the dyeing anilox roller is 120 mesh, the drying temperature of the first drying device is 94 °C, and the drying temperature of the second drying device is 90 °C. The dye used is dark green direct dye (Tianjin Xiangrui Company, product number dark green NF), diluted with condensed water to 9%, filtered and then applied and transferred to the anilox roller. The ink application amount is 7.5% (by weight, that is, the dye addition amount is 7.5 kg / t of paper). The color of the finished paper is L* = 31.2, a* = -10.0, b* = 16.0. Take 100 g from the dried dyed paper and conduct a weighing test according to the relevant standard requirements. Determine the moisture content of the sample ≤ 9% based on the difference in the mass of the sample before and after drying, indicating that the dyed paper in this example meets the drying requirements.

[0069] Step 4: Color change of the dyed paper

[0070] Use sapphire blue direct dye (Tianjin Xiangrui Company, sapphire blue 4BL), diluted with condensed water to 10%, filtered and then applied and transferred to the anilox roller. The ink application amount is 8% (by weight, that is, the dye addition amount is 7.5 kg / t of paper). Conduct a color change treatment on the dried base paper in step 2 to obtain a dyed base paper. Feed the dyed base paper into the first drying device for drying treatment to obtain a pre-dried dyed paper. Then feed the pre-dried dyed paper into the second drying device for drying treatment to obtain a dyed paper. The drying temperature of the first drying device is 94 °C, and the drying temperature of the second drying device is 90 °C. Take 100 g from the dried dyed paper and conduct a weighing test according to the relevant standard requirements. Determine the moisture content of the sample ≤ 9% based on the difference in the mass of the sample before and after drying, indicating that the dyed paper in this example meets the drying requirements. The color of the finished paper is L* = 54.4, a* = 1.75, b* = -28.5.

[0071] In this example, after the dark green napkin paper is wound up, disconnect the anilox roller to empty and recover the dye in the feeding chamber and clean it, and then re-inject the prepared sapphire blue dye to carry out the dyeing treatment. The whole equipment does not stop during this process. It takes 10 minutes to change the dye, that is, 10 minutes of un-dyed paper is produced. According to the set paper machine speed and width, with a production rate of 8.0 t / h, a total of 1.33 t of un-dyed finished paper is produced. Since this paper is disconnected from the dyeing roller and not dyed, it can be slit and sold as ordinary white paper without waste. The consumption of clean water for cleaning the dyeing anilox roller is 1 m 3 , no dye waste is generated, and there is no additional white water treatment load.

[0072] Example 3

[0073] This embodiment is used to first prepare 14 g / ㎡ orange napkin base paper and then carry out color modification to prepare 16 g / ㎡ gem blue paper napkin base paper. The selected fiber raw materials include bleached sulfate softwood pulp and bleached bamboo pulp from Norwegian red pine trees with a mass ratio of 22:78. Among them, the aspect ratio of the bleached sulfate softwood pulp from Norwegian red pine trees is 80, the coarseness is 0.15, the whiteness is 88, the grinding concentration is 4.8%, the beating degree is 32°SR, the whiteness of the bleached bamboo pulp is 85.0, the grinding concentration is 22%, the beating degree is 22°SR, the grinding concentration selected for refining is 3.5%, the beating degree is 27°SR, the addition amount of wet strength agent per ton of paper is 5.0 kg / t, and the addition amount of cationic starch per ton of paper is 1.0 kg / t. By observing the surface condition of the paper sheet after post-section dyeing, the pressing vacuum degree is adjusted to -30 kPa, and the pressing line pressure is 83 N / mm to ensure that there are no suction marks on the vacuum roll.

[0074] Step 1: Preparation of wet paper

[0075] Feed the softwood pulp into a low-consistency refiner for refining to obtain softwood pulp stock. Feed the bamboo pulp into a high-consistency refiner for refining to obtain bamboo pulp stock. After mixing the softwood pulp stock and the bamboo pulp stock and using a low-consistency refiner for refining, obtain pretreated pulp. Add additives to the pretreated pulp to obtain pulp. Carry out forming treatment on the pulp to obtain wet paper.

[0076] Step 2: Treatment of paper before dyeing

[0077] Feed the wet paper into a vacuum press roll for pressing treatment, and then feed the pressed wet paper into a third drying device for drying treatment to obtain dried base paper. Among them, the vacuum degree of the vacuum press roll is -30 Kpa, and the line pressure is 83 N / mm.

[0078] Step 3: Dyeing treatment of dried base paper

[0079] Feed the dried base paper into relatively arranged dyeing engraved rolls for dyeing treatment to obtain dyed base paper. Feed the dyed base paper into a first drying device for drying treatment to obtain pre-dried dyed paper. Then feed the pre-dried dyed paper into a second drying device for drying treatment to obtain dyed paper. Among them, the engraving of the dyeing engraved roll is 120 mesh, the drying temperature of the first drying device is 88 °C, and the drying temperature of the second drying device is 65 °C. The dye used is a blended orange direct dye (Tianjin Xiangrui Company), diluted with condensed water to 11%, filtered and then coated and transferred to the engraved roll, and the ink application amount is 8.2% (by weight, that is, the dye addition amount is 8.2 kg / t of paper). The color of the formed paper is L* = 58.8, a* = 42.25, b* = 35.4. Take 100 g from the dried dyed paper and conduct a weighing test according to relevant standard requirements. Determine the moisture content of the sample ≤ 9% based on the difference in mass before and after drying of the sample, indicating that the dyed paper in this embodiment meets the drying requirements.

[0080] Step 4: Color change of the dyed paper

[0081] Use direct sapphire blue dye (Tianjin Xiangrui Company, sapphire blue 4BL), dilute it with condensed water to 10%, filter it and then apply and transfer it to the anilox roller. The ink application amount is 8% (by weight, that is, the dye addition amount is 7.5 kg / t of paper). Perform color change treatment on the dried base paper in Step 2 to obtain a dyed base paper. Send the dyed base paper into the first drying device for drying treatment to obtain a pre-dried dyed paper, and then send the pre-dried dyed paper into the second drying device for drying treatment to obtain a dyed paper. The drying temperature of the first drying device is 88°C, and the drying temperature of the second drying device is 65°C. Take 100 g from the dried dyed paper and conduct a weighing test according to relevant standard requirements. Determine the moisture content of the sample ≤ 9% based on the difference in mass before and after drying of the sample, indicating that the dyed paper in this example meets the drying requirements. The color of the finished paper is L* = 54.4, a* = 1.75, b* = -28.5.

[0082] In this example, after the orange napkin paper is wound up, disconnect the anilox roller to empty and recover the dye in the feeding chamber and clean it, and then re-inject the configured sapphire blue dye to carry out the dyeing treatment. During this process, the whole equipment does not stop. It takes 10 minutes to replace the dye, that is, 10 minutes of undyed paper is produced. According to the set paper machine speed and width, calculated at a production rate of 6.2 t / h, a total of 1.03 t of undyed finished paper is produced. Since this paper is disconnected from the dyeing roller and not dyed, it can be slit and sold as ordinary white paper without waste. The consumption of clean water for cleaning the dyeing anilox roller is 1 m 3 , no dye waste is generated, and there is no additional white water treatment load.

[0083] Comparative Example 1

[0084] This comparative example is used to prepare a 16 g / ㎡ gemstone blue paper napkin base paper and perform color modification to prepare a 16 g / ㎡ red paper napkin base paper. The selected fiber raw materials include bleached sulfate softwood pulp from Norwegian red pine tree species and bleached sulfate hardwood pulp. Among them, the aspect ratio of the bleached sulfate softwood pulp from Norwegian red pine tree species is 80, the coarseness is 0.15, the whiteness is 88.0, the beating consistency is 4.6%, the beating degree is 42°SR, the aspect ratio of the bleached sulfate hardwood pulp is 48, the coarseness is 0.15, the whiteness is 88.0, the beating consistency is 4.6%, the beating degree is 30°SR, the beating consistency selected during refining is 4.6%, the beating degree is 38°SR, the addition amount of wet strength agent per ton of paper is 4 kg / t, and the addition amount of cationic starch per ton of paper is 0.6 kg / t. By observing the surface condition of the paper sheet after dyeing in the later stage, adjust the press vacuum to -30 kPa and the press line pressure to 86 N / mm to ensure that there are no vacuum roll suction marks.

[0085] Step 1, Slurry Preparation: Prepare the slurry through the processes of loosening the pulp and refining it to remove impurities.

[0086] Step 2, Pulp Blending and Dyeing: Add the dye to the mixing pulp tank for mixed dyeing.

[0087] Step 3, Re-refining and Fixing Color: Pump the wood pulp slurry in the mixing pulp tank into the refiner for re-refining, and add the fixing agent online by a screw pump at the outlet of the paper machine pulp tank pump. Then transfer the wood pulp slurry to the external white water tank, and add alkali solution to control the pH value to be 7.0 - 8.5.

[0088] Step 4, Forming on the Wire and Dehydration: Dilute and screen the slurry in the paper machine pulp tank through the external white water tank and the paper machine screen, then distribute the pulp by the headbox, form and dehydrate on the wire to form a uniform wet paper web. Then, through the conveyance of the felt, it enters the press section for further dehydration, and is extruded by the vacuum press roll to enhance the strength of the wet paper web. Among them, the press vacuum is -32 kPa, and the press line pressure is 88 N / mm.

[0089] Step 5, Drying and Creping Treatment: Use heated dryer cylinders and hot air hoods to dry the paper web. Peel the dried paper web from the dryer cylinder under the action of the creping blade, and the creping effect is brought about by the action of the creping blade, achieving the softness of the paper web and increasing the bulk of the finished paper to obtain dyed paper. The dye used is a sapphire blue direct dye (Tianjin Xiangrui Company, Sapphire Blue 4BL), diluted with condensate water to 6.5%. The color of the finished paper is L* = 56.5, a* = 1.92, b* = -29.5.

[0090] Step 6, Color Change Treatment: After the production of sapphire blue napkins is completed, according to the color matching principle, adding red dye will produce a purple color on the basis of the original blue dye, and will change from eggplant purple to cherry red as the amount of red dye increases until the purple dye is completely adsorbed and the red is completely transformed. This color matching principle directly causes the color of the finished paper to change with the amount of dye. Since this gradient color is unstable and cannot be sold normally. Among them, the dye transition time is 1 hour. Calculated at a paper production rate of 7.0 t / h, a total of 7 t of waste products are generated. To accelerate the color transition, it is necessary to replace the white water in the white water tower, and a total of about 200 m 3 , and the discharged white water is colored white water, which needs to be treated separately.

[0091] Comparative Example 2

[0092] The difference from Comparative Example 1 is that in this comparative example, the color change treatment is to switch to producing white paper. At this time, it is necessary to stop the machine and completely clean the pulp tank, water tank, pipeline, etc. of the whole machine to avoid the pollution of the white paper by colored fibers. Among them, the downtime when switching to white paper production is 5 h. Calculated at a production capacity of 7.0 t / h, the output is reduced by 35 t, and the water consumption for cleaning the equipment and pulp tank is 1500 m 3, and the discharged white water is colored white water, which requires additional treatment.

[0093] It can be seen from this that in the paper preparation method of the dyed paper in Embodiments 1-3 of the present application, when changing colors, the equipment does not stop, reducing the impact of color change on the equipment and improving production efficiency. And the time taken to replace the dye is short. During the dye replacement period, the uncolored white paper produced by the equipment can still be reused or sold, avoiding waste of paper and reducing costs. At the same time, since the method in the embodiments of the present application only needs to replace the dye in the dyeing roller and clean the dyeing roller when changing colors, compared with adding dyes to the slurry pool in the comparative document for color adjustment, the waste of paper generated is small, and the problem of white water pollution is overcome.

[0094] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any one or more embodiments or examples in a suitable manner.

[0095] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A paper processing device, characterized in that, The paper processing equipment includes a pulp treatment section, a paper forming section, a dyeing section, and a drying section that are connected in sequence; The dyeing section includes two relatively arranged dyeing rollers for dyeing both sides of the base paper dried by the paper forming section; The drying section includes a first drying device and a second drying device, and the water outlet of the first drying device is connected to the water inlet of the second drying device.

2. The paper processing equipment according to claim 1, wherein The paper forming section includes a pressing device and a third drying device. The third drying device is located between the pressing device and the dyeing section, and the water outlet of the third drying device is connected to the water inlet of the first drying device.

3. The paper processing equipment according to claim 1 or 2, characterized in that, The paper forming section includes a vacuum pressing roll; and / or, The drying temperature of the first drying device is 88°C to 98°C, and the drying temperature of the second drying device is 65°C to 98°C.

4. A method for preparing paper, characterized in that, The method for preparing the paper includes: Pre-treating fiber raw materials and additives in the pulp treatment section to obtain wet paper; Feeding the wet paper into the paper forming section to obtain a dried base paper; Feeding the dried base paper into the dyeing section for dyeing treatment to obtain a dyed base paper; Drying the dyed base paper to obtain dyed paper.

5. The method for preparing paper according to claim 4, characterized in that, Before drying the dyed base paper to obtain dyed paper, the method for preparing the paper further includes: Adjusting the paper forming parameters of the paper forming section according to the feedback of the paper surface of the dyed base paper.

6. The method for preparing paper according to claim 4, wherein The paper forming section includes a pressing device and a third drying device. The step of feeding the wet paper into the paper forming section to obtain a dried base paper includes: Feeding the wet paper into the pressing device for pressing treatment to obtain a base paper to be dried; Feeding the base paper to be dried into the third drying device for drying treatment to obtain a dried base paper.

7. The method for preparing paper according to claim 4, characterized in that, The step of drying the dyed base paper to obtain dyed paper includes: Feeding the dyed base paper into the first drying device for drying treatment to obtain a pre-dried dyed paper; Feeding the pre-dried dyed paper into the second drying device for drying treatment to obtain dyed paper.

8. The method for preparing paper according to any one of claims 4 to 7, characterized in that, The step of pre-treating fiber raw materials and additives in the pulp treatment section to obtain wet paper includes: Grinding softwood pulp and bamboo pulp to obtain pre-treated pulp; Adding additives to the pre-treated pulp to obtain pulp; Forming the pulp to obtain wet paper.

9. The method for preparing paper according to claim 8, wherein The aspect ratio of the softwood pulp is ≥60, the coarseness is ≤0.16 mg / m, the beating consistency of the softwood pulp is 4.2% to 4.8%, the freeness is 27°SR to 32°SR, the beating consistency of the bamboo pulp is 20% to 24%, and the freeness is 23°SR to 26°SR; and / or, The additives include a wet strength agent and starch. The addition amount of the wet strength agent per ton of paper is 3 kg / t to 5 kg / t, and the addition amount of the starch per ton of paper is 0.5 kg / t to 1 kg / t; and / or, The starch is cationic starch.

10. A kind of paper, characterized in that, The paper is prepared by the method for preparing the paper according to any one of claims 4 to 9.

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