Production process for manufacturing high-performance low-basis-weight wet-strength regenerated kraft linerboard with secondary fibers

Abstract

The invention discloses a production process for papermaking high-performance low-basis-weight wet-strength regenerated craft paper with secondary fibers, which is used for solving the technical problems of high raw material cost and high production energy consumption caused by the fact that the existing high-strength wet-strength paper is generally made of 100% raw wood pulp as a raw material. The method comprises the following steps: preparing raw materials, wherein the raw materials comprise American waste regenerated pulp boards or American waste 12 / 13 # and native softwood pulp; the preparation method comprises the following steps: preparing first pulp from American waste regenerated pulp boards or American waste 12 / 13 # through a preset first pulping process, preparing second pulp from original softwood pulp through a preset second pulping process, and mixing the first pulp and the second pulp on a feeding system of a paper machine to obtain paper making pulp; adding a retention and drainage aid, an internal sizing agent and a wet strength agent into the paper making pulp; the paper making pulp is conveyed to a paper machine through a paper machine feeding system, the paper machine conducts papermaking, squeezing dehydration, drying, sizing and calendaring procedures on the paper making pulp, and then the craft paper finished product can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking, and in particular to a production process for making high-performance low-quantity wet-strength recycled kraft paper from secondary fibers. Background Art

[0002] Traditional high-strength wet-strength paper is generally made of 100% virgin wood pulp (usually mechanical pulp and chemical pulp) as raw material. Its raw material cost and production energy consumption are relatively high. The production of traditional high-strength wet-strength paper still faces problems such as high consumption of virgin wood pulp, high pollution, and high energy consumption.

[0003] Therefore, finding a technical solution that can solve the above technical problems has become an important topic studied by technical personnel in this field. Summary of the invention

[0004] The embodiment of the present invention discloses a production process for secondary fiber papermaking of high-performance low-weight wet-strength recycled kraft paper, which is used to solve the technical problem that the existing high-strength wet-strength paper is generally produced and papermade using 100% virgin wood pulp as raw material, resulting in high raw material costs and production energy consumption.

[0005] The present invention provides a production process for making high-performance low-weight wet-strength recycled kraft paper from secondary fibers, comprising the following steps:

[0006] S1. Prepare raw materials, wherein the raw materials include 50%%-60% of U.S. waste recycled pulp or U.S. waste 12 / 13# and 40%-50% of virgin coniferous wood pulp;

[0007] S2, using the US waste recycled pulp board or US waste 12 / 13# to make a first pulp through a preset first pulping process, using the original coniferous wood pulp to make a second pulp through a preset second pulping process, and mixing the first pulp and the second pulp at the paper machine feeding system to form a papermaking pulp;

[0008] S3, adding retention and drainage aids, sizing agents and wet strength agents into the papermaking pulp;

[0009] S4. The papermaking pulp is transported to the paper machine through the paper machine feeding system. The wire section of the paper machine dehydrates and integrates the papermaking pulp to form a wet paper web. The press section of the paper machine presses and dehydrates the wet paper web. Subsequently, the front drying device of the paper machine dries the paper web to obtain base paper. The sizing device of the paper machine applies sizing to the surface of the base paper. Finally, the back drying device of the paper machine dries the base paper for a second time. The base paper is then calendered by the calendering device to obtain the finished kraft paper.

[0010] Optionally, the step S2 and the step S1 further include:

[0011] A solvent consisting of 1.3% sodium hydroxide and 0.7% disodium hydrogen phosphate is added to the clean water in the treatment pool to form an alkaline solution, the pH value of the alkaline solution is controlled between 8-10, and the temperature of the alkaline solution is greater than 65°C;

[0012] Place the US waste regenerated paddle board or US waste 12 / 13# into the treatment tank and soak it in alkali solution for a preset time.

[0013] Optionally, in step S2, the first pulping process specifically includes the following steps:

[0014] a1. Pulp the US waste regeneration paddle or US waste 12 / 13# and transport them to the high-concentration cleaner;

[0015] a2. The slurry after being treated by the high-concentration cleaner is subjected to coarse screening and graded screening in sequence, and the graded screened slurry is transported to the low-concentration cleaner;

[0016] a3. The slurry treated by the low-concentration cleaner is finely screened, and the finely screened slurry is sent to a multi-disc concentrator. After being treated by the multi-disc concentrator, it is thermally dispersed, and finally treated by a disc grinding pulping to form a first slurry.

[0017] Optionally, the first pulping process includes the following parameters:

[0018] The crushing concentration of the first slurry is controlled between 4-6%;

[0019] The pressure difference during the coarse screening process is controlled at 20-30kpa; the pressure difference during the graded screening process is controlled at 10-20kpa; the pressure difference during the fine screening process is controlled at 15-25kpa;

[0020] The inlet concentration of the multi-disc thickener is controlled at 0.5-0.8%, the dryness of the pressing screw is not less than 30%, and the torque is controlled between 30-50%;

[0021] The preheating temperature during the heat dispersion process is not less than 95°C, and the back pressure is controlled at 150-180kpa;

[0022] The feed power of the disc grinding pulping process is controlled at 600-800kw, the pulping concentration of the first pulp is controlled at 4-6%, and the beating degree of the first pulp is controlled at 28-33°SR.

[0023] Optionally, in step S2, the second pulping process specifically includes the following steps:

[0024] b1. Pulping the original coniferous wood pulp and conveying it to a high-consistency cleaner;

[0025] b2. The slurry treated by the high-concentration cleaner is subjected to disc grinding in a disc grinding system to form a second slurry.

[0026] Optionally, the disc grinding system comprises a primary disc grinding assembly and a secondary disc grinding assembly in sequence;

[0027] The primary refiner assembly includes two first wood pulp refiners connected in parallel, and the secondary refiner assembly includes two second wood pulp refiners connected in series.

[0028] Optionally, the second pulping process includes the following parameters:

[0029] The feed power of the disc grinding system is controlled at 500-700 kW, the pulping concentration of the second slurry is controlled at 4-6%, and the beating degree of the second slurry is controlled at 20-25° SR.

[0030] Optionally, the retention and drainage aid is cationic polyacrylamide CPAM;

[0031] The sizing agent in the slurry is an AKD emulsion with a cationic charge, wherein the amount of the AKD emulsion is controlled at 20-30 kg / t, and the pH is controlled at 6-8;

[0032] The wet strength agent is a high-solid PAE type cationic wet strength agent, wherein the addition amount of the PAE type cationic wet strength agent is controlled at 8-15 kg / t.

[0033] Optionally, in step S4, the press section of the paper machine uses two consecutive shoe presses to press and dehydrate the wet paper web, wherein the pressure of the first shoe press is controlled at 600-800 KN, and the pressure of the second shoe press is controlled at 1000-1200 KN, the dryness of the wet paper web after leaving the wire section of the paper machine is controlled at 20-23%, and the dryness of the wet paper web leaving the press section of the paper machine is controlled at 49-53%.

[0034] Optionally, in step S4, the step of applying sizing to the surface of base paper by the sizing device of the paper machine specifically includes:

[0035] c1. preparing a colloid for sizing, mixing starch, a surface sizing agent, a starch catalyst enhancer and aluminum sulfate to prepare a colloid, wherein the surface sizing agent accounts for 15-20% of the starch, the starch catalyst enhancer accounts for 0.5-0.6% of the starch, and the aluminum sulfate accounts for 15-20% of the starch;

[0036] c2. Add the colloid into a sizing device, and the sizing device applies sizing to the surface of the base paper.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] In the production process of this embodiment, the high-performance wet-strength recycled kraft paper is produced by using recycled paddles or recycled 12 / 13# from US waste to replace about 40-50% of the original wood pulp, which is more environmentally friendly and has lower production costs. At the same time, the product quality and performance can also greatly meet market demand. In addition, using waste paper raw materials to replace most of the original wood pulp can not only save original materials, such as grass, forests, etc., but also reduce pollution to the environment. Compared with mechanical pulp and chemical pulp, the production process of this embodiment has a better carbon reduction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 The present invention provides a flow chart of a production process for making high-performance, low-weight, wet-strength recycled kraft paper from secondary fibers. DETAILED DESCRIPTION

[0041] The present invention discloses a production process for secondary fiber papermaking of high-performance low-weight wet-strength recycled kraft paper, which is used to solve the technical problem that the existing high-strength wet-strength paper is generally produced and papermade using 100% virgin wood pulp as raw material, resulting in high raw material costs and production energy consumption.

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] See also Figure 1 The present invention provides a production process for secondary fiber papermaking of high-performance low-weight wet-strength recycled kraft paper, comprising the following steps:

[0044] S1. Prepare raw materials, wherein the raw materials include 50%%-60% of U.S. waste recycled pulp or U.S. waste 12 / 13# and 40%-50% of virgin coniferous wood pulp;

[0045] S2, using the US waste recycled pulp board or US waste 12 / 13# to make a first pulp through a preset first pulping process, using the original coniferous wood pulp to make a second pulp through a preset second pulping process, and mixing the first pulp and the second pulp at the paper machine feeding system to form a papermaking pulp;

[0046] S3, adding retention and drainage aids, sizing agents and wet strength agents into the papermaking pulp;

[0047] S4. The papermaking pulp is transported to the paper machine through the paper machine feeding system. The wire section of the paper machine dehydrates and integrates the papermaking pulp to form a wet paper web. The press section of the paper machine presses and dehydrates the wet paper web. Subsequently, the front drying device of the paper machine dries the paper web to obtain base paper. The sizing device of the paper machine applies sizing to the surface of the base paper. Finally, the back drying device of the paper machine dries the base paper for a second time. The base paper is then calendered by the calendering device to obtain the finished kraft paper.

[0048] It should be noted that the U.S. waste recycled paddle board or U.S. waste 12 / 13# and virgin coniferous wood pulp in this embodiment are raw materials that can be purchased on the market. The properties of the U.S. waste recycled paddle board or U.S. waste 12 / 13# and virgin coniferous wood pulp are shown in the following table:

[0049]

[0050] In the production process of this embodiment, the high-performance wet-strength recycled kraft paper is produced by using recycled paddles or recycled 12 / 13# from US waste to replace about 40-50% of the original wood pulp, which is more environmentally friendly and has lower production costs. At the same time, the product quality and performance can also greatly meet market demand. In addition, using waste paper raw materials to replace most of the original wood pulp can not only save original materials, such as grass, forests, etc., but also reduce pollution to the environment. Compared with mechanical pulp and chemical pulp, the production process of this embodiment has a better carbon reduction efficiency.

[0051] Furthermore, in this embodiment, step S2 and step S1 further include:

[0052] A solvent consisting of 1.3% sodium hydroxide and 0.7% disodium hydrogen phosphate is added to the clean water in the treatment pool to form an alkaline solution, the pH value of the alkaline solution is controlled between 8-10, and the temperature of the alkaline solution is greater than 65°C;

[0053] Place the US waste regenerated paddle board or US waste 12 / 13# into the treatment tank and soak it in alkali solution for a preset time.

[0054] It should be noted that, through the above design, the fibers in the American waste recycled paddle or American waste 12 / 13# can be fully stretched, the fiber separation and brooming effect can be improved, and pulping can be easier. Therefore, in the subsequent first pulping process, the disc grinding feed power can be lower, thereby achieving lower energy consumption and improving the pulp bursting strength.

[0055] Furthermore, in step S2 of this embodiment, the first pulping process specifically includes the following steps:

[0056] a1. Pulp the US waste regeneration paddle or US waste 12 / 13# and transport them to the high-concentration cleaner;

[0057] a2. The slurry after being treated by the high-concentration cleaner is subjected to coarse screening and graded screening in sequence, and the graded screened slurry is transported to the low-concentration cleaner;

[0058] a3. The slurry treated by the low-concentration cleaner is finely screened, and the finely screened slurry is sent to a multi-disc concentrator. After being treated by the multi-disc concentrator, it is thermally dispersed, and finally treated by a disc grinding pulping to form a first slurry.

[0059] It should be noted that in the first pulping process, a high-concentration cleaner and a low-concentration cleaner are used to remove heavy impurities in the pulp to avoid affecting the quality of the subsequent finished product;

[0060] In the above pulping process, coarse screening is used to remove light residues and larger impurities, and fine screening is used to remove some adhesives. Among them, the coarse screening is done by outflow, and the pulp passes through the screen under the work of the high-speed rotating rotor, and large pieces of plastic impurities are squeezed out of the barrel tail pulp pipe. KADANT's UV500 series screen frame is used for coarse screening, and the hole screen and the slot screen are selected to be used in combination. While ensuring the throughput of the pulp, it also has a more reasonable average service life. KADANT's UV500 series screen frame is used for fine screening, and the screen slot is selected at 0.15mm-0.25mm, which can separate the pulp into good pulp and long, medium and short fibers.

[0061] Specifically, the first pulping process includes the following parameters:

[0062] The crushing concentration of the first slurry is controlled between 4-6%;

[0063] The pressure difference during the coarse screening process is controlled at 20-30kpa; the pressure difference during the graded screening process is controlled at 10-20kpa; the pressure difference during the fine screening process is controlled at 15-25kpa.

[0064] The inlet concentration of the multi-disc thickener is controlled at 0.5-0.8%, the dryness of the pressing screw is not less than 30%, and the torque is controlled between 30-50%;

[0065] The preheating temperature during the heat dispersion process is not less than 95°C, and the back pressure is controlled at 150-180kpa;

[0066] The feed power of the disc grinding pulping process is controlled at 600-800kw, the pulping concentration of the first pulp is controlled at 4-6%, and the beating degree of the first pulp is controlled at 28-33°SR.

[0067] Furthermore, in step S2 of this embodiment, the second pulping process specifically includes the following steps:

[0068] b1. Pulping the original coniferous wood pulp and conveying it to a high-consistency cleaner;

[0069] b2. The slurry treated by the high-concentration cleaner is subjected to disc grinding in a disc grinding system to form a second slurry.

[0070] It should be noted that the virgin coniferous pulp adopts a multi-stage series disc grinding operation scheme of light pulping, controlling the beating degree of the pulp to no more than 25, ensuring the fiber strength while allowing the fibers to be fully broomed and loosened, and ensuring the tear strength of the finished paper through the wood pulp.

[0071] The specific disc grinding scheme is as follows: the disc grinding system used in the disc grinding includes a primary disc grinding assembly and a secondary disc grinding assembly in sequence;

[0072] The primary refiner assembly includes two first wood pulp refiners connected in parallel, and the secondary refiner assembly includes two second wood pulp refiners connected in series.

[0073] It should be noted that the first-level disc refiner assembly is the main stage of wood pulp beating. Two first wood pulp disc refiners are connected in parallel, and the disc refiners have the same specific energy consumption. The two second wood pulp disc refiners of the second-level disc refiner assembly are connected in series for pulping. The specific energy consumption of one second wood pulp disc refiner is controlled at 60% of the specific energy consumption of the first-level disc refiner assembly, and the specific energy consumption of the other second wood pulp disc refiner is controlled at 80% of the specific energy consumption of the first-level disc refiner assembly.

[0074] In addition, the use of the above-mentioned first-level disc grinding assembly and the second disc grinding assembly to achieve differentiated pulping can improve the bursting strength while ensuring the tearing strength. In terms of paper strength effect, the bursting strength can be increased by about 40%, and the breaking length can be increased by about 30%.

[0075] Specifically, the second pulping process in this embodiment includes the following parameters:

[0076] The feed power of the disc grinding system is controlled at 500-700 kW, the pulping concentration of the second slurry is controlled at 4-6%, and the beating degree of the second slurry is controlled at 20-25° SR.

[0077] Furthermore, the retention and drainage aid in this embodiment is cationic polyacrylamide CPAM;

[0078] It should be noted that the above-mentioned cationic polyacrylamide CPAM can improve the retention of fine fibers of paper pulp and paper fillers on the wire, reduce the interference of paper fillers on the papermaking system, and improve the cleanliness of the white water system, making the papermaking system run more stably.

[0079] Furthermore, the sizing agent in the present embodiment is a cationic AKD emulsion, wherein the amount of AKD emulsion is controlled at 20-30 kg / t, and the pH is controlled at 6-8;

[0080] It should be noted that in the prior art, rosin glue is generally added to the papermaking pulp to improve the water resistance and water retention of paper. Rosin glue requires an acidic environment to exert a good sizing effect, but the disadvantage is that a continuous acidic environment will affect the charge balance of the wet-end system, affect the effects of other wet-end chemicals, and be detrimental to maintaining a good cleanliness of the system.

[0081] In this embodiment, AKD emulsion with cationic charge is used for internal sizing, the dosage is controlled at 20-30 kg / t, the pH is controlled at about 6-8, and the wet end system can be maintained in a moderately alkaline environment, providing good water and moisture resistance for the paper;

[0082] Furthermore, the wet strength agent in this embodiment is a PAE type cationic wet strength agent with a high solid content (30%), wherein the addition amount of the PAE type cationic wet strength agent is controlled at 8-15 kg / t.

[0083] It should be noted that the addition amount is controlled at 8-15kg / t by diluting the paper 10-20 times in the dilution water system and adding it at the thick stock position to fully retain the amine group, epoxy group and azetidine, and by reacting with the negatively charged pulp fiber to limit the fiber stretching. The main purpose of adding is to allow the paper to maintain a certain strength under water immersion conditions and improve the wet strength effect of the paper.

[0084] Furthermore, in step S4 of this embodiment, the press section of the paper machine uses two consecutive shoe presses to press and dehydrate the wet paper web, wherein the pressure of the first shoe press is controlled at 600-800 KN, and the pressure of the second shoe press is controlled at 1000-1200 KN, and the dryness of the wet paper web after leaving the wire section of the paper machine is controlled at 20-23%, and the dryness of the wet paper web leaving the press section of the paper machine is controlled at 49-53%.

[0085] It should be noted that through the above design, the press section of the paper machine adopts two continuous shoe presses, which improves the dehydration efficiency by increasing the peak pressure and rapidly reducing the pressure at the end of the press area, reduces the rewetting effect to the minimum level, improves the dryness of the exit press area, and thus reduces the steam consumption of the dryer. At the same time, a cross-section steam box is added at the first press position, and by observing the deviation of the cross-section moisture, a single-point local adjustment is performed to reduce the cross-section deviation and improve the uniformity of the base paper.

[0086] Furthermore, in step S4 of this embodiment, the step of applying glue to the surface of the base paper by the sizing device of the paper machine specifically includes:

[0087] c1. preparing a colloid for sizing, mixing starch, a surface sizing agent, a starch catalyst enhancer and aluminum sulfate to prepare a colloid, wherein the surface sizing agent accounts for 15-20% of the starch, the starch catalyst enhancer accounts for 0.5-0.6% of the starch, and the aluminum sulfate accounts for 15-20% of the starch;

[0088] c2. Add the colloid into a sizing device, and the sizing device applies sizing to the surface of the base paper.

[0089] The purpose of the above-mentioned sizing treatment on the surface of the base paper is:

[0090] 1. Pre-finish the surface of the finished paper and improve the strength of the finished paper.

[0091] 2. Improve paper properties and further increase production efficiency. The retention rate of the added chemicals by surface sizing is almost 100%.

[0092] 3. In terms of environmental friendliness, surface sizing has more advantages than wet-end additives. Surface sizing can reduce or eliminate chemicals in white water, which helps improve the environment.

[0093] It should be further explained that the sizing device used in this embodiment is specifically a film transfer sizing machine, which uses glue to pre-treat the paper surface. The starch in the glue can form a starch film to fill the surface pores of the paper, reduce the micropore diameter, and thus reduce the penetration of liquid, thereby improving the water resistance of the paper surface, improving the printing performance, preventing hair loss and powder loss, and effectively improving the strength and dimensional stability of the finished paper. At the same time, in order to reduce starch consumption and improve the surface film forming property, the film transfer sizing machine uses a small-meter scraper combination in the selection of scrapers to control the amount of glue on the surface layer to be about 20-30% less than the amount of glue on the bottom layer, and the sizing state is relatively stable.

[0094] By using starch catalytic enhancer to replace traditional amylase, the hydrogen bonds in the starch molecular chain can be cut during cooking. Its free radicals are the same as those in starch, and can quickly rearrange with starch to form grafted starch, thereby improving the slurry hanging property of starch slurry and the strength of finished paper;

[0095] In addition, the amount of surface sizing agent added is controlled at 40-60L / H, the amount of bottom surface sizing agent added is controlled at 60-80L / H; the amount of aluminum sulfate added as surface glue is controlled at 3-5L / min. The purpose of adding: a. Improve the water absorption performance of paper, prevent water penetration, and improve the dimensional stability of paper; b. Optimize the paper machine system environment and reduce the interference of anionic garbage on the papermaking environment; c. Promote the sizing effect of the sizing agent and improve the surface film forming property of the film transfer sizing.

[0096] Furthermore, in step S4 of this embodiment, after obtaining the finished kraft paper, a coating machine is used to coat the finished paper, thereby reducing the influence of the external environment on the paper and extending the storage time of the finished paper.

[0097] Furthermore, the performance parameters of the kraft paper produced by the above-mentioned secondary fiber papermaking high-performance low-weight wet-strength recycled kraft paper are as follows:

[0098]

[0099] Note: The wet burst test means that under specified test conditions, after the sample is immersed in water for 1 hour, uniform pressure is applied perpendicular to the surface of the sample to test the maximum resistance until the sample breaks.

[0100] In summary, the kraft paper produced by the production process of secondary fiber papermaking high-performance low-weight wet-strength recycled kraft paper has the following advantages:

[0101] 1. In terms of raw material structure, high-performance low-weight wet-strength recycled kraft paper is made from recycled paddle board or recycled 12 / 13# from US waste as the main raw material, which greatly reduces the raw material cost while meeting the quality requirements.

[0102] 2. Using waste paper raw materials to replace most of the original wood pulp can not only save original materials (grass, forests, etc.), but also reduce pollution to the environment. Compared with mechanical pulp and chemical pulp, the carbon reduction efficiency of waste paper pulp production is better.

[0103] 3. In the pulping process, the recycled paddles from US waste or US waste 12 / 13# and the original coniferous wood pulp are used for differentiated pulping, which can reduce the mechanical damage to the fiber and play the role of fiber separation and brooming;

[0104] 4. The disc mill adopts the light beating method of the original coniferous wood pulp, which makes the original wood pulp slightly cut, and greatly saves electricity while retaining the fiber length and strength.

[0105] 5. In the sizing process, the AKD in-pulp sizing method is adopted to maintain a long-term neutral alkaline environment in the wet end, so that other chemicals in the wet end are more adaptable and the effects of the attenuation of the functional additives (such as wet strength agents) and process additives (such as retention agents) are reduced; at the same time, the heavy sizing method is adopted to greatly improve the water resistance and anti-penetration performance of the paper.

[0106] 6. In the pressing process, two continuous shoe presses and a horizontal steam box are used to improve the dehydration efficiency and horizontal uniformity, improve the dryness of the press area, and thus reduce the steam consumption of the dry part.

[0107] 7. In terms of wet strength retention, high solid content PAE wet strength agent is selected, which can be adjusted to any proportion through the dilution water system to achieve the wet strength retention effect required by the customer;

[0108] 8. When the paper is packaged off-line, a film wrapping machine is used to wrap the paper, which reduces the impact of the external environment on the paper and extends the storage time of the finished paper.

[0109] The production process of this embodiment uses American waste recycled paddles or American waste 12 / 13# to replace about 40-50% of the original wood pulp to produce high-performance wet-strength recycled kraft paper by innovating the raw material ratio, optimizing the pulping process, chemical process and sizing process control, etc., which is more environmentally friendly and has lower production costs. At the same time, the product quality and performance can also greatly meet market demand. In addition, using waste paper raw materials to replace most of the original wood pulp can not only save original materials, such as grass, forests, etc., but also reduce pollution to the environment. Compared with mechanical pulp and chemical pulp, the production process of this embodiment has a better carbon reduction efficiency.

[0110] The above is a detailed introduction to the production process of secondary fiber papermaking high-performance low-weight wet-strength recycled kraft paper provided by the present invention. For general technicians in this field, according to the ideas of the embodiments of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A production process for making high-performance low-weight wet-strength recycled kraft paper from secondary fibers, characterized in that: The following steps are involved: S1. Prepare raw materials, wherein the raw materials include 50%%-60% of U.S. waste recycled pulp or U.S. waste 12 / 13# and 40%-50% of virgin coniferous wood pulp; S2, using the US waste recycled pulp board or US waste 12 / 13# to make a first pulp through a preset first pulping process, using the original coniferous wood pulp to make a second pulp through a preset second pulping process, and mixing the first pulp and the second pulp at the paper machine feeding system to form a papermaking pulp; S3, adding retention and drainage aids, sizing agents and wet strength agents into the papermaking pulp; S4. The papermaking pulp is transported to the paper machine through the paper machine feeding system. The wire section of the paper machine dehydrates and integrates the papermaking pulp to form a wet paper web. The press section of the paper machine presses and dehydrates the wet paper web. Subsequently, the front drying device of the paper machine dries the paper web to obtain base paper. The sizing device of the paper machine applies sizing to the surface of the base paper. Finally, the back drying device of the paper machine dries the base paper for a second time. The base paper is then calendered by the calendering device to obtain the finished kraft paper.

2. The production process of secondary fiber papermaking high-performance low-weight wet-strength recycled kraft paper according to claim 1, characterized in that: The step S2 and the step S1 also include: A solvent consisting of 1.3% sodium hydroxide and 0.7% disodium hydrogen phosphate is added to the clean water in the treatment pool to form an alkaline solution, the pH value of the alkaline solution is controlled between 8-10, and the temperature of the alkaline solution is greater than 65°C; Place the US waste regenerated paddle board or US waste 12 / 13# into the treatment tank and soak it in alkali solution for a preset time.

3. The production process of secondary fiber papermaking high-performance low-weight wet-strength recycled kraft paper according to claim 1, characterized in that: In the step S2, the first pulping process specifically includes the following steps: a1, pulping the American waste regeneration paddle or American waste 12 / 13# and conveying it to a high-concentration cleaner; a2. The slurry after being treated by the high-concentration cleaner is subjected to coarse screening and graded screening in sequence, and the graded screened slurry is transported to the low-concentration cleaner; a3. The slurry treated by the low-concentration cleaner is finely screened, and the finely screened slurry is sent to a multi-disc concentrator. After being treated by the multi-disc concentrator, it is thermally dispersed, and finally treated by a disc grinding pulping to form a first slurry.

4. The production process of secondary fiber papermaking high-performance low-weight wet-strength recycled kraft paper according to claim 3, characterized in that: The first pulping process includes the following parameters: The crushing concentration of the first slurry is controlled between 4-6%; The pressure difference during the coarse screening process is controlled at 20-30kpa; the pressure difference during the graded screening process is controlled at 10-20kpa; the pressure difference during the fine screening process is controlled at 15-25kpa; The inlet concentration of the multi-disc thickener is controlled at 0.5-0.8%, the dryness of the pressing screw is not less than 30%, and the torque is controlled between 30-50%; The preheating temperature during the heat dispersion process is not less than 95°C, and the back pressure is controlled at 150-180kpa; The feed power of the disc grinding pulping process is controlled at 600-800kw, the pulping concentration of the first pulp is controlled at 4-6%, and the beating degree of the first pulp is controlled at 28-33°SR.

5. The production process of secondary fiber papermaking high-performance low-weight wet-strength recycled kraft paper according to claim 1, characterized in that: In step S2, the second pulping process specifically includes the following steps: b1. Pulping the original coniferous wood pulp and conveying it to a high-consistency cleaner; b2. The slurry treated by the high-concentration cleaner is subjected to disc grinding in a disc grinding system to form a second slurry.

6. The production process of secondary fiber papermaking high-performance low-weight wet-strength recycled kraft paper according to claim 5, characterized in that: The disc grinding system comprises a primary disc grinding assembly and a secondary disc grinding assembly in sequence; The primary refiner assembly includes two first wood pulp refiners connected in parallel, and the secondary refiner assembly includes two second wood pulp refiners connected in series.

7. The process for producing high-performance low-weight wet-strength recycled kraft paper made of secondary fibers according to claim 5, characterized in that: The second pulping process includes the following parameters: The feed power of the disc grinding system is controlled at 500-700 kW, the pulping concentration of the second slurry is controlled at 4-6%, and the beating degree of the second slurry is controlled at 20-25° SR.

8. The process for producing high-performance low-weight wet-strength recycled kraft paper made of secondary fibers according to claim 1, characterized in that: The retention and drainage aid is cationic polyacrylamide CPAM; The sizing agent in the slurry is an AKD emulsion with a cationic charge, wherein the amount of the AKD emulsion is controlled at 20-30 kg / t, and the pH is controlled at 6-8; The wet strength agent is a high-solid PAE type cationic wet strength agent, wherein the addition amount of the PAE type cationic wet strength agent is controlled at 8-15 kg / t.

9. The process for producing high-performance low-weight wet-strength recycled kraft paper made of secondary fibers according to claim 1, characterized in that: In the step S4, the press section of the paper machine uses two consecutive shoe presses to press and dehydrate the wet paper web, wherein the pressure of the first shoe press is controlled at 600-800 KN, and the pressure of the second shoe press is controlled at 1000-1200 KN, and the dryness of the wet paper web after leaving the wire section of the paper machine is controlled at 20-23%, and the dryness of the wet paper web leaving the press section of the paper machine is controlled at 49-53%.

10. The process for producing high-performance low-weight wet-strength recycled kraft paper made of secondary fibers according to claim 1, characterized in that: In step S4, the step of applying glue to the surface of the base paper by the sizing device of the paper machine specifically includes: c1. preparing a colloid for sizing, mixing starch, a surface sizing agent, a starch catalyst enhancer and aluminum sulfate to prepare a colloid, wherein the surface sizing agent accounts for 15-20% of the starch, the starch catalyst enhancer accounts for 0.5-0.6% of the starch, and the aluminum sulfate accounts for 15-20% of the starch; c2. Add the colloid into a sizing device, and the sizing device applies sizing to the surface of the base paper.

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