A method for manufacturing high-strength impregnation-dyed base paper

Abstract

The present application discloses a method for manufacturing high-strength impregnation-dyed base paper, comprising the following steps: S1, using bleached kraft softwood chemical pulp and insoluble polyacrylamide fiber as fiber raw materials for papermaking; S2, subjecting the product obtained in step S1 to sequential processing through a thick stock screen, seasoning, pulping, sand removal and degassing, sizing, paper machine screen, headbox, fourdrinier paper machine wire section dehydration and forming, pressing, drying, calendering, winding, and packaging to produce the high-strength impregnation-dyed base paper. The product produced by the method for manufacturing high-strength impregnation-dyed base paper provided in the present application has excellent air permeability and ink absorbency, excellent thickness and softness, good uniformity, excellent burst index and breaking length, good wet strength, and strong mechanical properties during dyeing.

Description

Technical Field

[0001] The present application relates to the technical field of base paper preparation, and in particular to a method for manufacturing high-strength impregnation-dyed base paper. Background Art

[0002] High-strength impregnated-dyed base paper undergoes post-processing (including dyeing, embossing, die-cutting, and hot stamping) to create leather-filled dyed paper, honeycomb-grid dyed paper, origami-style paper, and other applications. These are ultimately used in a variety of packaging applications, including high-end boxes, books, and notebooks, as well as cushioning and shock-absorbing packaging and flower packaging. This product requires strong ink absorbency and uniform dyeing, resulting in vibrant, saturated colors. The impregnated-dyed paper also exhibits softness, excellent toughness, high bulk, tear, tensile, and scratch resistance, and high wet strength. The dyed paper must be completely impregnated, with no visible white spots on the cross-section. Products made from high-strength impregnated-dyed base paper possess an aesthetically pleasing, leather-like texture. This base paper is highly priced, leading to significant domestic demand, but the market is largely dominated by foreign companies. High-strength impregnated-dyed base paper requires both excellent strength and good softness and high bulk, which conflict with each other and presents significant development challenges. However, developing this high-strength impregnated-dyed base paper is of great significance for improving product quality, profitability, and corporate image, while also filling a domestic gap. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a method for manufacturing high-strength impregnation dyeing base paper. The product has excellent air permeability and ink absorbency, excellent thickness and softness, good uniformity, excellent burst resistance index and breaking length, as well as good wet strength and strong mechanical properties during dyeing processing.

[0004] The technical solutions provided by the present invention are as follows:

[0005] A method for manufacturing high-strength impregnation-dyed base paper comprises the following steps:

[0006] S1. Bleached kraft softwood chemical pulp and insoluble polyacrylamide fiber are used as fiber raw materials for blending;

[0007] S2. The product obtained in step S1 is sequentially subjected to thick stock screening, seasoning, pulping, sand removal and degassing, sizing, paper machine screen, headbox, fourdrinier paper machine wire section dehydration and forming, pressing, drying, calendering, winding, and packaging to produce high-strength impregnated and dyed base paper.

[0008] Preferably, the pulp weight ratio in step S1 is: 85-95% bleached kraft softwood chemical pulp and 5-15% insoluble polyacrylamide fiber.

[0009] Preferably, the average length of the insoluble polyacrylamide fibers in step S1 is not less than 3 mm.

[0010] Preferably, the beating concentration of the bleached kraft softwood chemical pulp in step S1 is 5-8%, and 10-25 kg / t of pulp water-retaining agent is added during beating, wherein the pulp water-retaining agent comprises a methacrylate polymer, and the beating degree of the bleached kraft softwood chemical pulp is controlled at 26-30 SR°.

[0011] Preferably, in step S2, 3 to 8 kg / t of paper of anionic polyacrylamide is added between the paper machine screen and the headbox as a dispersant.

[0012] Preferably, the molecular weight of the dispersant is 150,000 to 350,000, and the viscosity of the dispersant is 10 to 50 mpas (solid content 1%).

[0013] Preferably, in step S2, the sizing concentration of the headbox is controlled at 0.3-0.5%.

[0014] Preferably, in step S2, the wire portion of the Fourdrinier paper machine is provided with a V-shaped scraper.

[0015] Preferably, no cationic dry strength agent is used during sizing in the headbox in step S2.

[0016] Preferably, in step S2, 20-40 kg / t of a wet strength agent is added before the paper machine screen, wherein the wet strength agent comprises a polyamide polyamine epichlorohydrin resin, and has a pH value of 2-4 and a viscosity of 20-35 mpas (solid content 12.5%).

[0017] This application has the following advantages over the prior art:

[0018] 1. The method for manufacturing high-strength impregnation-dyed base paper of the present invention comprises insoluble polyacrylamide fibers having an average length of 3 mm or more, ensuring that the interior of the paper sheet has a porous structure to improve air permeability and ensure good ink absorption;

[0019] 2. The method for manufacturing high-strength impregnated dyed base paper of the present invention increases the beating concentration of bleached softwood kraft pulp (NBKP) to 5-8% as much as possible, and simultaneously adds 10-25 kg / t of pulp of a pulp water-retaining agent (methacrylate polymer) to assist in the beating of the NBKP. This improves the strength while preventing fiber cuts, thus laying the foundation for achieving good paper permeability and ink absorption properties.

[0020] 3. The method for manufacturing high-strength impregnated dyed base paper of the present invention includes adding 3-8 kg / t of paper of anionic polyacrylamide dispersant between the paper machine screen and the headbox. The dispersant has a molecular weight of 150,000-350,000 and a viscosity of 10-50 mPas (1% solid content). Its negative charge prevents fiber aggregation, thereby improving uniformity. A V-shaped scraper is added to the wire section of the Fourdrinier paper machine to create micro-turbulence on the slurry, thereby improving uniformity.

[0021] 4. The main parameters of the products obtained by the manufacturing method of high-strength impregnation dyeing base paper of the present invention are: basis weight 75, 90, 110 g / m 2 , bulk thickness is 75g / m 2 Product: ≥1.7cm 3 / g, 90g / m 2 Product: ≥1.6cm 3 / g, 110g / m 2 Product: ≥1.4cm 3 / g, air permeability is: 75g / m 2 Product: ≥1400ml / min, 90g / m 2 Product: ≥800ml / min, 110g / m 2 Product: ≥500ml / min, longitudinal tear length ≥5000m; transverse tear index ≥6.0mNm 2 / g, burst resistance index: ≥3.0kPam 2 / g, longitudinal wet tensile strength ≥1.0KN / m, paper whiteness 84~86%ISO. DETAILED DESCRIPTION

[0022] In order to help those skilled in the art better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of this application.

[0023] The present invention provides a method for manufacturing high-strength impregnation-dyed base paper, comprising the following steps:

[0024] S1. Bleached kraft softwood chemical pulp and insoluble polyacrylamide fiber are used as fiber raw materials for blending;

[0025] S2. The product obtained in step S1 is sequentially subjected to thick stock screening, seasoning, pulping, sand removal and degassing, sizing, paper machine screen, headbox, fourdrinier paper machine wire section dehydration and forming, pressing, drying, calendering, winding, and packaging to produce high-strength impregnated and dyed base paper.

[0026] In this embodiment, the pulp ratio by weight in step S1 is: 85-95% bleached kraft softwood chemical pulp and 5-15% insoluble polyacrylamide fiber. Since high-strength impregnation-dyed base paper requires excellent ink absorbency, the paper sheet must have a porous structure, high bulk, and high air permeability. The internal fibers must be primarily long. Therefore, the average length of the insoluble polyacrylamide fibers must be no less than 3 mm. The paper machine used in the embodiment of the present invention is a traditional multi-cylinder cultural paper machine. Low-concentration pulping is used for pulping, and the fiber cutting is serious. Therefore, the pulping concentration of bleached sulfate softwood chemical pulp (NBKP) is increased as much as possible. The pulping concentration of bleached sulfate softwood chemical pulp is 5-8%. During the pulping, 10-25 kg / t of pulp water-retaining agent is added. The pulp water-retaining agent includes methacrylate polymer. Methacrylate polymer has excellent water-retaining properties. After mixing with the fiber before pulping, it enters the interior of the fiber and uses its water-retaining properties to increase the water content of the fiber. During the pulping process, the flexibility of the fiber itself is enhanced, and the lubrication between the fibers is promoted, thereby promoting fiber swelling and surface fibrillation. While improving the strength, the fiber cutting is prevented, laying the foundation for obtaining good paper permeability and ink absorption properties. Table 1 is the comparative experimental results of the effect of methacrylate polymer-assisted softwood chemical pulp on pulp fiber cutting. It can be seen from Table 1 that when using full softwood chemical pulp for beating, when the beating degree is close, the amount of beating aid methacrylate polymer is changed. With the increase of beating aid, the average length of the pulp fiber after beating increases significantly, and the permeability increases significantly. The appropriate amount is 10-25 kg / t pulp, and the NBKP beating degree is controlled at 26-30SR°.

[0027] Table 1 Effect of methacrylate polymer-assisted softwood chemical pulp on pulp fiber cutting

[0028]

[0029] In this embodiment, the pulp structure is made of long-fiber chemical pulp and long-fiber polyvinyl alcohol fiber, and the average fiber length is long. During the papermaking process, the fibers are difficult to disperse, which easily leads to poor uniformity and uneven dyeing. Therefore, the method for manufacturing high-strength impregnation-dyed base paper in this embodiment specifically adopts the following method to ensure good paper uniformity:

[0030] (1) Add 3-8 kg / t of anionic polyacrylamide dispersant between the paper machine screen and the headbox. Its molecular weight is 150,000-350,000 and its viscosity is 10-50 mpas (1% solid content). Anionic polyacrylamide has low molecular weight and low viscosity. Its negative charge can prevent the aggregation between fibers, thereby improving the uniformity.

[0031] (2) In order to improve the paper sheet formation and evenness, a low-concentration sizing method is adopted, and the concentration of the headbox is controlled at 0.3-0.5% to allow the fibers to be fully dispersed and improve evenness;

[0032] (3) To improve the uniformity, do not use cationic retention aids that cause slurry flocculation, and do not use cationic dry strengthening agents;

[0033] (4) Add a V-shaped scraper to the mesh section of the fourdrinier paper machine. The V-shaped scraper can cause micro-turbulence on the pulp on the mesh, thereby improving the uniformity.

[0034] In this embodiment, in order to achieve excellent water-based dye absorption performance of paper, no surface sizing was used during papermaking, and no calendering was performed. 2 The bulk of the product reaches 1.7cm 3 / g or above, and the air permeability reaches more than 1400ml / min.

[0035] In this embodiment, to ensure the strength of paper during immersion dyeing and prevent paper breakage during subsequent processing, 20-40 kg / t of a wet strength agent is added before the paper machine screen in step S2. The wet strength agent includes a polyamide polyamine epichlorohydrin resin, has a pH value of 2-4, and a viscosity of 20-35 mpas (solid content 12.5%).

[0036] The main parameters of the products obtained by the manufacturing method of the high-strength impregnation dyeing base paper of the embodiment of the present invention are: basis weight 75, 90, 110g / m 2 , bulk thickness is 75g / m 2 Product: ≥1.7cm 3 / g, 90g / m 2 Product: ≥1.6cm 3 / g, 110g / m 2 Product: ≥1.4cm 3 / g, air permeability is: 75g / m 2 Product: ≥1400ml / min, 90g / m 2 Product: ≥800ml / min, 110g / m 2 Product: ≥500ml / min, longitudinal tear length ≥5000m; transverse tear index ≥6.0mNm 2 / g, burst resistance index: ≥3.0kPam 2 / g, longitudinal wet tensile strength ≥1.0KN / m, paper whiteness 84~86%ISO.

[0037] The following is a specific embodiment of the method for manufacturing high-strength impregnation-dyed base paper according to an embodiment of the present invention.

[0038] Example 1:

[0039] The beating degree of bleached kraft softwood chemical pulp (NBKP) is controlled at 26SR°. The beating of NBKP is assisted by methacrylate polymer, with a dosage of 17kg / t pulp. The pulp is prepared according to the pulp weight ratio of NBKP85% and polyacrylamide fiber15%. After mixing, the pulp is prepared into a mixed pulp with a concentration of 1.5%. After the pulp is screened, seasoned, and punched, the concentration is controlled at 0.3%. Then, it goes through desanding, degassing, and sizing. Before the paper machine screen, 20kg / t of paper is added to the wet strength agent. After the paper machine screen, 3kg / t of paper is added to the anionic polyacrylamide dispersant. After passing through the headbox, the concentration on the screen is controlled at 0.32%. Then, it goes through the wire dehydration, forming, pressing, drying, calendering, winding, and packaging to produce high-strength impregnated and dyed base paper.

[0040] The measured value of the high-strength impregnation dyeing base paper prepared in this embodiment is 75g / m 2 , bulk 1.75cm 3 / g, air permeability 1450ml / min, longitudinal tear length 6231m; transverse tear index 7.0mNm 2 / g, burst resistance index: 3.6kPam 2 / g, longitudinal wet tensile strength 1.4KN / m, paper whiteness 85.2%ISO.

[0041] Example 2:

[0042] The beating degree of bleached kraft softwood chemical pulp (NBKP) is controlled at 28SR°. The beating of NBKP is assisted by methacrylate polymer, with a dosage of 20kg / t pulp. The pulp is prepared according to the pulp weight ratio of 90% NBKP and 10% polyacrylamide fiber. After mixing, the pulp is prepared into a mixed pulp with a concentration of 1.5%. After the pulp is screened, seasoned, and flushed, the concentration is controlled at 0.33%. Then, it is desanded, deaerated, and sizing. Before the paper machine screen, 30kg / t of wet strength agent is added, and after the paper machine screen, 5kg / t of anionic polyacrylamide dispersant is added. After passing through the headbox, the concentration on the screen is controlled at 0.41%. Then, it goes through the wire dehydration, forming, pressing, drying, calendering, winding, and packaging to produce high-strength impregnated and dyed base paper.

[0043] The measured value of the high-strength impregnation dyeing base paper prepared in this embodiment is 90g / m 2 , bulk 1.63cm3 / g, air permeability 850ml / min, longitudinal tear length 5950m; transverse tear index 6.8mNm 2 / g, burst resistance index 3.3kPam 2 / g, longitudinal wet tensile strength 1.3KN / m, paper whiteness 85.3%ISO.

[0044] Example 3:

[0045] The beating degree of bleached kraft softwood chemical pulp (NBKP) is controlled at 30SR°. The beating of NBKP is assisted by methacrylate polymer, with a dosage of 25kg / t pulp. The pulp is prepared according to the pulp weight ratio of NBKP95% and polyacrylamide fiber 5%. After mixing, the pulp is prepared into a mixed pulp with a concentration of 1.3%. After the pulp is screened, seasoned, and punched, the concentration is controlled at 0.46%. Then, it is desanded, deaerated, and sizing. Before the paper machine screen, 38kg / t of paper is added to the wet strength agent. After the paper machine screen, 7kg / t of paper is added to the anionic polyacrylamide dispersant. After passing through the headbox, the concentration on the screen is controlled at 0.43%. Then, it goes through the wire dehydration, forming, pressing, drying, calendering, winding, and packaging to produce high-strength impregnated and dyed base paper.

[0046] The measured value of the high-strength impregnation dyeing base paper prepared in this embodiment is 110g / m 2 , bulk 1.46cm 3 / g, air permeability 580ml / min, longitudinal tear length 5950m; transverse tear index 6.8mNm 2 / g, burst resistance index 3.2kPam 2 / g, longitudinal wet tensile strength 1.5KN / m, paper whiteness 85.5%ISO.

[0047] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing high-strength impregnation-dyed base paper, characterized in that: The steps are as follows: S1. Bleached kraft softwood chemical pulp and insoluble polyacrylamide fiber are blended as fiber raw materials, wherein the beating concentration of the bleached kraft softwood chemical pulp is 5-8%, and 10-25 kg / t of pulp water-retaining agent is added during beating, wherein the water-retaining agent comprises a methacrylate polymer, the beating degree of the bleached kraft softwood chemical pulp is controlled to be 26-30SR°, and the average length of the insoluble polyacrylamide fiber is not less than 3 mm; S2. The product obtained in step S1 is sequentially subjected to a thick stock screen, seasoning, pulping, sand removal and degassing, sizing, paper machine screen, headbox, dehydration and forming in the Fourdrinier paper machine wire section, pressing, drying, calendering, winding, and packaging to produce high-strength impregnated and dyed base paper; 20-40 kg / t of a wet strength agent is added before the paper machine screen, wherein the wet strength agent comprises a polyamide polyamine epichlorohydrin resin, and the pH value of the wet strength agent is 2-4 and the viscosity is 20-35 mpas.

2. The method for producing high-strength impregnation-dyed base paper according to claim 1, characterized in that: The pulp weight ratio in step S1 is: 85-95% bleached kraft softwood chemical pulp and 5-15% insoluble polyacrylamide fiber.

3. The method for producing high-strength impregnation-dyed base paper according to claim 1, characterized in that: In step S2, 3 to 8 kg / t of paper of anionic polyacrylamide is added between the paper machine screen and the headbox as a dispersant.

4. The method for producing high-strength impregnation-dyed base paper according to claim 3, characterized in that: The molecular weight of the dispersant is 150,000 to 350,000, and the viscosity of the dispersant is 10 to 50 mpas.

5. The method for producing high-strength impregnation-dyed base paper according to any one of claims 1 to 4, characterized in that: In step S2, the sizing concentration of the headbox is controlled at 0.3-0.5%.

6. The method for producing high-strength impregnation-dyed base paper according to any one of claims 1 to 4, characterized in that: In the step S2, a V-shaped scraper is provided on the wire portion of the fourdrinier paper machine.

7. The method for producing high-strength impregnation-dyed base paper according to any one of claims 1 to 4, characterized in that: In step S2, no cationic dry strengthening agent is used during sizing in the headbox.

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