High-efficiency production process of high-whiteness offset paper to produce off-white offset paper

Abstract

This invention belongs to the field of papermaking technology, specifically involving a process for efficiently converting high-whiteness double-sided offset paper into natural white double-sided offset paper. This invention involves online conversion on the paper machine, including the following processes: (1) Pre-conversion preparation: 30 minutes before the high-whiteness paper roll is unwound, the rewinder is stopped, and the pulper, waste paper tower, and waste paper treatment system are cleaned. The liquid levels in the pulping white water tower and the papermaking white water tower are controlled to be below 40%. (2) Conversion process: Maintaining the pulp ratio for producing high-whiteness double-sided offset paper, after the high-whiteness paper roll is produced, discontinuing the use of OBA, blue dye, and purple dye in high-whiteness double-sided offset paper production, and switching to yellow dye; reducing the waste paper ratio; adding sodium hypochlorite to the waste water tank; stopping drainage from the white water tower and adding sodium hypochlorite; adding sodium hypochlorite to the white water tank outside the paper machine; and adding yellow dye stock solution to the white water tank below the wire and the white water tank respectively. This invention improves production efficiency, reduces conversion losses, and saves production costs.

Description

Technical Field

[0001] This invention belongs to the field of papermaking technology, specifically relating to a process for efficiently converting high-whiteness double-sided offset paper into natural white double-sided offset paper. Background Technology

[0002] High-whiteness offset paper and natural white offset paper are two different types of paper. The content of fluorescent substances is an important difference between the two. Natural white offset paper usually has a much lower content of fluorescent substances than high-whiteness offset paper.

[0003] Both high-whiteness offset paper and natural white offset paper require high-whiteness paper rolls as the base layer material. During the production of high-whiteness offset paper, a large amount of OBA (Original Oil Absorbent Composite) remains in the production system. After switching to natural white offset paper production, a significant amount of OBA remains, causing the fluorescence value of the produced natural white offset paper to exceed the standard for a considerable period after the switch. This substandard product can only be used as waste paper, and the long transition time after the switch severely impacts production efficiency. Therefore, it is necessary to explore a production process that can remove OBA from the system in a short time, ensuring that the quality requirements are met quickly after switching from high-whiteness offset paper to natural white offset paper. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a process for efficiently converting high-whiteness double-sided offset paper into natural white double-sided offset paper, which improves production efficiency, reduces conversion losses, and saves production costs.

[0005] The process for efficiently converting high-whiteness offset paper to off-white offset paper according to the present invention involves online conversion on the paper machine and includes the following processes:

[0006] (1) Modify the pre-production preparation process:

[0007] Stop the rewinder 30 minutes before the high whiteness paper roll is unwound, clean the pulper, paper loss tower and paper loss system of each machine, and control the liquid level of the pulping white water tower and papermaking white water tower to be below 40% to reduce the impact of white water from the high whiteness double-sided offset paper production system on the production conversion.

[0008] (2) Process modification:

[0009] Maintain the pulp ratio for producing high-whiteness offset paper. After the high-whiteness paper roll is unwound, stop using OBA, blue dye and purple dye, and switch to using yellow dye.

[0010] Reduce the waste paper ratio to 0%;

[0011] Sodium hypochlorite was added to the catalytic cracking tank until the mass concentration reached 0.2%-0.3% to remove residual OBA in the tank.

[0012] Stop draining water from the clean water tower, add sodium hypochlorite until the mass concentration reaches 0.02%-0.03%, and remove OBA from the clean water tower;

[0013] Sodium hypochlorite is added to the white water tank outside the paper machine until the mass concentration reaches 0.02%-0.03% to remove OBA from the white water tank outside the machine;

[0014] Yellow dye stock solution was added to the white water pool and the clear water pool at a mass concentration of 25-50 ppm, respectively.

[0015] The surface adhesive is emptied and replaced with new surface adhesive solution;

[0016] During the production process modification, the amount of yellow dye added at the dye addition point was adjusted to maintain the paper's b-value at 6.0-7.0.

[0017] (3) Modified production process:

[0018] As processes (1) and (2) proceed, the obtained double-sided coated paper is scanned by a color sensor for online fluorescence value detection. Double-sided coated paper with a fluorescence value higher than 0.5 is used as high whiteness waste paper. After the fluorescence value is lower than 0.5, the waste paper ratio is adjusted to 4%-5% to consume the high whiteness waste paper until it is completely consumed.

[0019] Preferably, in step (1), cleaning the pulpers, waste paper towers and waste paper treatment systems of each machine specifically includes: washing and evacuating the pulpers of each machine, and washing the waste paper towers and waste paper treatment systems in series to avoid the waste paper of the high-whiteness double-sided offset paper production system affecting the production change.

[0020] Preferably, the yellow dye is GR Yellow produced by Luoyang Taixue Dyeing & Chemical Co., Ltd.

[0021] Preferably, the surface adhesive is KSK728 produced by Zhejiang Kesike High-Tech Materials Co., Ltd.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. Significantly reduced the time required to convert high-whiteness offset paper to natural white offset paper, enabling the rapid production of natural white offset paper with qualified fluorescence values, thus improving production efficiency;

[0024] 2. It reduced the amount of high-whiteness paper produced, lowered production losses, and saved production costs. Attached Figure Description

[0025] Figure 1 This is the FI curve diagram at the start of the production modification in Example 1;

[0026] Figure 2 This is the FI curve graph at the end of the production modification in Example 1;

[0027] Figure 3 This is the FI curve diagram at the start of the production modification in Example 2;

[0028] Figure 4This is the FI curve graph at the end of the production modification in Example 2;

[0029] Figure 5 This is the FI curve diagram for the start of production modification in Example 1;

[0030] Figure 6 This is the FI curve diagram after the production modification of Example 1;

[0031] Figure 7 This is the FI curve diagram for the start of production modification in Comparative Example 2;

[0032] Figure 8 This is the FI curve diagram after the completion of the production modification in Comparative Example 2; Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments.

[0034] Unless otherwise specified, all raw materials used in the examples were commercially available. The yellow dye was GR Yellow produced by Luoyang Taixue Dyeing & Chemical Co., Ltd.; the surface sizing agent was KSK728 produced by Zhejiang Kesike High-Tech Materials Co., Ltd.

[0035] The paper machine uses a Valmet wire paper machine with a width of 9600mm, a maximum operating speed of 1500m / min, and a basis weight of 60-120g / m³. 2 .

[0036] Example 1

[0037] The process for efficiently converting high-whiteness offset paper to off-white offset paper according to the present invention involves online conversion on the paper machine and includes the following processes:

[0038] (1) Modify the pre-production preparation process:

[0039] 30 minutes before the high-whiteness paper roll is unwound, the rewinder is stopped and the pulpers, waste paper towers and waste paper treatment systems of each machine are cleaned. The cleaning process is as follows: the pulpers of each machine are washed and evacuated, and the waste paper towers and waste paper treatment systems are washed in series.

[0040] The liquid levels in both the pulping white water tower and the papermaking white water tower should be controlled below 40%.

[0041] (2) Process modification:

[0042] Maintain the pulp ratio for producing high-whiteness offset paper. After the high-whiteness paper roll is unwound, stop using OBA, blue dye and purple dye, and switch to using yellow dye.

[0043] Reduce the waste paper ratio to 0%;

[0044] Add sodium hypochlorite to the voltammetric tank until the mass concentration reaches 0.3%;

[0045] Stop draining water from the water tower and add sodium hypochlorite until the mass concentration reaches 0.02%.

[0046] Sodium hypochlorite was added to the white water tank outside the paper machine until the mass concentration reached 0.03%.

[0047] Yellow dye stock solution was added to the white water pool and the clear water pool at a mass concentration of 25 ppm.

[0048] The surface adhesive is emptied and replaced with new surface adhesive solution;

[0049] During the production process modification, the amount of yellow dye added at the dye addition point was adjusted to maintain the paper's b-value at 6.0-7.0.

[0050] (3) Modified production process:

[0051] As processes (1) and (2) proceed, the obtained double-sided coated paper is subjected to fluorescence value detection. Double-sided coated paper with fluorescence value higher than 0.5 is used as high whiteness waste paper. After the fluorescence value is lower than 0.5, the waste paper ratio is adjusted to 4.5% to consume high whiteness waste paper until it is completely consumed.

[0052] Example 2

[0053] The process for efficiently converting high-whiteness offset paper to off-white offset paper according to the present invention involves online conversion on the paper machine and includes the following processes:

[0054] (1) Modify the pre-production preparation process:

[0055] 30 minutes before the high-whiteness paper roll is unwound, the rewinder is stopped and the pulpers, waste paper towers and waste paper treatment systems of each machine are cleaned. The cleaning process is as follows: the pulpers of each machine are washed and evacuated, and the waste paper towers and waste paper treatment systems are washed in series.

[0056] The liquid levels in both the pulping white water tower and the papermaking white water tower should be controlled below 40%.

[0057] (2) Process modification:

[0058] Maintain the pulp ratio for producing high-whiteness offset paper. After the high-whiteness paper roll is unwound, stop using OBA, blue dye and purple dye, and switch to using yellow dye.

[0059] Reduce the waste paper ratio to 0%;

[0060] Add sodium hypochlorite to the voltammetric tank until the mass concentration reaches 0.2%;

[0061] Stop draining water from the water tower and add sodium hypochlorite until the mass concentration reaches 0.03%;

[0062] Sodium hypochlorite was added to the white water tank outside the paper machine until the mass concentration reached 0.02%.

[0063] Yellow dye stock solution was added to the white water pool and the clear water pool at a mass concentration of 25 ppm.

[0064] The surface adhesive is emptied and replaced with new surface adhesive solution;

[0065] During the production process modification, the amount of yellow dye added at the dye addition point was adjusted to maintain the paper's b-value at 6.0-7.0.

[0066] (3) Modified production process:

[0067] As processes (1) and (2) proceed, the obtained double-sided coated paper is subjected to fluorescence value detection. Double-sided coated paper with fluorescence value higher than 0.5 is used as high whiteness waste paper. After the fluorescence value is lower than 0.5, the waste paper ratio is adjusted to 4.5% to consume high whiteness waste paper until it is completely consumed.

[0068] Comparative Example 1

[0069] Comparative Example 1 illustrates a production modification process without employing the modified process of this invention. The modification is performed online on a paper machine and includes the following processes:

[0070] (1) Modify the pre-production preparation process:

[0071] 30 minutes before the high-whiteness paper roll is unwound, the rewinder is stopped and the pulpers, waste paper towers and waste paper treatment systems of each machine are cleaned. The cleaning process is as follows: the pulpers of each machine are washed and evacuated, and the waste paper towers and waste paper treatment systems are washed in series.

[0072] The liquid levels in both the pulping white water tower and the papermaking white water tower should be controlled below 40%.

[0073] (2) Process modification:

[0074] Maintain the pulp ratio for producing high-whiteness offset paper. After the high-whiteness paper roll is unwound, stop using OBA, blue dye and purple dye, and switch to using yellow dye.

[0075] Reduce the waste paper ratio to 0%;

[0076] The surface adhesive is emptied and replaced with new surface adhesive solution;

[0077] During the production process modification, the amount of yellow dye added at the dye addition point was adjusted to maintain the paper's b-value at 6.0-7.0.

[0078] (3) Modified production process:

[0079] As processes (1) and (2) proceed, the obtained double-sided coated paper is subjected to fluorescence value detection. Double-sided coated paper with fluorescence value higher than 0.5 is used as high whiteness waste paper. After the fluorescence value is lower than 0.5, the waste paper ratio is adjusted to 4.5% to consume high whiteness waste paper until it is completely consumed.

[0080] Comparative Example 2

[0081] Comparative Example 2 is another production modification process using the same technology as Comparative Example 1.

[0082] The FI curves of the production processes in Examples 1-2 and Comparative Examples 1-2 are shown below. Figure 1-8 As shown in the figure, the horizontal axis represents time and the vertical axis represents the FI value. When the FI value drops to 2.0, the production modification is considered to be completed and the product is qualified. The production modification time of Examples 1-2 and Comparative Examples 1-2 is shown in Table 1.

[0083] Table 1. Production conversion duration for Examples 1-2 and Comparative Examples 1-2

[0084] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Start time 8:58 AM 8:22 AM 9:11 AM 7:13 AM End time 9:51 AM 9:17 AM 11:26 AM 9:57 AM Duration / min 53 55 135 164

[0085] As can be seen from Table 1, the present invention effectively reduces the production conversion process time and reduces the conversion loss by about 80 tons / time. Calculated based on two production conversions per month, the monthly loss is reduced by about 160 tons, and the production cost is reduced by about 64,960 yuan / month, with an annual cost saving of 779,520 yuan.

Claims

1. A process for efficiently converting high-whiteness offset paper into off-white offset paper, characterized in that, Online conversion of paper machines includes the following processes: (1) Modify the pre-production preparation process: Stop the rewinder 30 minutes before the high-whiteness paper roll is unwound, clean the pulper, waste paper tower and waste paper treatment system of each machine, and control the liquid level of the pulping white water tower and the papermaking white water tower to be below 40%. (2) Process modification: Maintain the pulp ratio for producing high-whiteness offset paper. After the high-whiteness paper roll is produced, discontinue the use of OBA, blue dye and purple dye used in high-whiteness offset paper, and switch to the use of yellow dye. Reduce the proportion of waste paper; Add sodium hypochlorite to the catalytic cell; Stop draining water from the water tower and add sodium hypochlorite; Sodium hypochlorite was added to the white water tank outside the paper machine; Yellow dye stock solution was added to both the white water pool and the clear water pool. The surface adhesive is emptied and replaced with new surface adhesive solution; During the production process modification, the amount of yellow dye added at the dye addition point was adjusted to maintain the paper's b-value at 6.0-7.

0. (3) Modified production process: As processes (1) and (2) proceed, the obtained double-sided coated paper is subjected to fluorescence value detection. Double-sided coated paper with fluorescence value higher than 0.5 is used as high whiteness waste paper. After the fluorescence value is lower than 0.5, the waste paper ratio is adjusted to 4%-5% to consume high whiteness waste paper until it is completely consumed.

2. The process for efficiently converting high-whiteness double-sided offset paper into off-white double-sided offset paper according to claim 1, characterized in that, In step (1), cleaning the pulpers, waste paper towers and waste paper treatment systems of each machine specifically includes: washing and evacuating the pulpers of each machine, and washing the waste paper towers and waste paper treatment systems in series.

3. The process for efficiently converting high-whiteness double-sided offset paper into off-white double-sided offset paper according to claim 1, characterized in that, In step (2), the waste paper ratio is reduced to 0%.

4. The process for efficiently converting high-whiteness offset paper into off-white offset paper according to claim 1, characterized in that, In step (2), sodium hypochlorite is added to the voltammetric tank until the mass concentration reaches 0.2%-0.3%.

5. The process for efficiently converting high-whiteness double-sided offset paper into off-white double-sided offset paper according to claim 1, characterized in that, In step (2), sodium hypochlorite is added to the clean water tower until the mass concentration reaches 0.02%-0.03%.

6. The process for efficiently converting high-whiteness double-sided offset paper into off-white double-sided offset paper according to claim 1, characterized in that, In step (2), sodium hypochlorite is added to the white water tank outside the paper machine until the mass concentration reaches 0.02%-0.03%.

7. The process for efficiently converting high-whiteness offset paper into off-white offset paper according to claim 1, characterized in that, In step (2), yellow dye stock solution is added to the white water pool and the clear white water pool at a mass concentration of 25-50 ppm.

8. The process for efficiently converting high-whiteness offset paper into off-white offset paper according to claim 1, characterized in that, The yellow dye is GR Yellow.

9. The process for efficiently converting high-whiteness offset paper into off-white offset paper according to claim 1, characterized in that, The surface adhesive is KSK728.

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