Improved papermaking process and device for high-bulk, high-water-absorption and high-strength moisture absorption paper

Abstract

The invention provides an improved papermaking process and device for high-bulkiness, high-water-absorption and high-strength moisture absorption paper, and relates to the technical field of pulping and papermaking engineering, and the improved papermaking process specifically comprises the following steps: defibering New Zealand thermo-mechanical pulp; after the defibered chemical long fibers and the defibered thermo-mechanical pulp are put into different pulp pools respectively, pulping operation is conducted through a complete dissociation sand removing machine and double-disc grinding equipment; mixing different pulps after beating, and adding polyester fibers, a wet strength agent and other wet end additives into the mixed pulp; performing fiber paper surface forming on the fed mixed pulp through a fourdrinier wire and a top wire forming device; squeezing and drying the formed fiber paper surface; the squeezed and dried paper is glued; and carrying out infrared drying on the gluing layer on the paper. According to the improved papermaking process and device for the high-bulk, high-water-absorption and high-strength moisture absorption paper, the water absorption efficiency and the water absorption capacity of the moisture absorption paper are improved, and the strength of the moisture absorption paper is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of pulping and papermaking engineering, and specifically relates to an improved papermaking process and a device for high-bulk, high-water-absorbent and high-strength hygroscopic paper. Background Art

[0002] There are many types of moisture-absorbing papers on the market, but they generally have problems such as poor strength, easy to break and easy to shed. After absorbing a large amount of water, it will become soft due to water immersion, resulting in reduced strength. Therefore, the development trend of moisture-absorbing paper is high performance, that is, to improve the moisture absorption capacity and moisture absorption speed, and also to enhance the strength and durability of paper and extend its service life to meet the needs of different fields, such as in the field of food packaging and storage, and the moisture-proof requirements of electronic products in production and transportation.

[0003] However, the current hygroscopic paper still has the following technical problems: (1) The current moisture-absorbing paper contains fewer pores and has a lower efficiency in absorbing moisture from the air; (2) The thickness of the current hygroscopic paper is difficult to control. If it is too thin, the hygroscopic capacity is limited, the strength is reduced, and it is easy to break. If it is too thick, it may affect the convenience of use and increase the cost. Therefore, how to keep the thickness of the hygroscopic paper in a relatively thin state while still having high bulk and strength, as well as excellent hygroscopic performance, becomes the key technical problem to be solved in this scheme.

[0004] This solution provides an improved papermaking process and device for high-bulk, high-absorbent, high-strength hygroscopic paper, which are used to simultaneously solve the above-mentioned technical problems. Summary of the invention

[0005] The purpose of the present invention is to provide an improved papermaking process and device for high-bulk, high-absorbent and high-strength hygroscopic paper, which solves the technical problem of how to increase the water absorption efficiency and water absorption capacity of hygroscopic paper and improve the strength of hygroscopic paper. By adjusting the fiber variety and adding synthetic fibers, the thickness performance and strength performance are increased, and a series of adjustments are also made in the production process and equipment to adjust the thickness and pore structure of the paper as a whole to optimize the thickness, hygroscopic performance and strength performance.

[0006] The improved papermaking process of high bulk, high water absorption and high strength hygroscopic paper comprises the following steps: Step 1: using a pulping pot to deflake chemical long fibers and deflaking New Zealand pulp to obtain thermomechanical pulp; Step 2: After the chemical long fibers and thermomechanical pulp after debonding in step 1 are placed in different pulp pools, the pulping operation is performed by equipment; Step 3: The pulp after beating in step 2 is passed through a complete separation sand remover to evenly disperse the fibers and maintain good water absorption uniformity; Step 4: After mixing the different pulps after beating in step 3, polyester fiber, wet end additives and wet strength agent are added to the mixed pulp at the same time according to the mass ratio of (9-12): (0.2-0.3): (5.0-10.0), and the mixed pulp is transported to the wire part through the dilution water headbox; Step 5: The mixed slurry is fed through a fourdrinier former and a top wire former to form the fiber paper surface; Step 6: Press and dry the fiber paper surface formed by the fourdrinier wire and the top wire to remove the moisture and bubbles inside; Step 7: Use a film transfer sizing machine to apply glue to the paper squeezed and dried in step 5; Step 8: Infrared drying is performed on the glue coating on the paper, and then the dried and hot-pressed paper is rolled into a tight and uniform paper roll using a drying cylinder for hot pressing.

[0007] In the step 2, the beating degree of the chemical long fibers after debonding is 54-56°SR, and the beating degree of the thermo-chemical pulp is 20-30°SR.

[0008] In the step 3, in the fourdrinier wire and top wire former, the ratio of the pulp speed to the wire speed is adjusted to 0.98.

[0009] In step 4, cellulose and acrylic resin are added simultaneously, and the mass ratio of cellulose and acrylic resin is (1.5-3.5): (2.0-3.0), and the ratio of the sum of the mass of cellulose and acrylic resin to the mass of polyester fiber is 0.3-0.7.

[0010] In step 4, during pressing, composite pressing for dehydration and light pressing for defect correction are used.

[0011] In the step 8, the adhesive layer is structural adhesive.

[0012] The improved papermaking device for high-bulk, high-absorbency and high-strength hygroscopic paper comprises a double-disc pulping machine, a fully separated sand removing machine, a dilution water headbox, a fourdrinier former, a top net former, a pressing and drying structure, a film transfer sizing machine, an infrared drying box, a drying cylinder and a curling device, wherein the fully separated sand removing machine comprises a power system, a grinding system and a sand removal system.

[0013] The deburring system comprises a stator and a rotor, and teeth or blades are distributed on the surface of the rotor; The stator is movably connected to the rotor and fixed on the housing or the frame.

[0014] The desanding system comprises a desanding cone for throwing heavy impurities in the slurry toward the inner wall of the cone, and a sand storage device for collecting and storing impurities separated from the slurry and cleaning them regularly. The desanding cone has a cone structure.

[0015] The dilution water type headbox includes a homogenizing chamber, a turbulence generator connected to the homogenizing chamber, an overflow chamber connected to the turbulence generator, a main pulp inlet pipe and a pulp distribution bundle pipe connected to the homogenizing chamber, an upper lip plate and a lower lip plate connected to the overflow chamber, and the upper lip plate and the lower lip plate are connected to a lip plate fine-tuning mechanism.

[0016] The positive effects of the present invention are as follows: (1) This scheme uses New Zealand thermomechanical pulp, which retains more natural fiber structure and makes the fiber relatively coarse, which gives the paper good stiffness and bulk; (2) In order to further increase the strength of the paper, polyester fiber is added, which not only increases the thickness of the paper, but also enhances the strength of the paper. At the same time, it forms a supporting structure in the paper, increases the fluffiness of the paper, and thus increases the thickness of the paper; With the fully separated sand dispersing machine, the uniformity problem is solved. It can make the fibers evenly dispersed and maintain good water absorption uniformity. In order to improve the strength of hygroscopic paper, the infrared dryer is used for rapid heating and drying, which can better remove moisture from the paper and maintain its thickness to the maximum, and also improve the strength of the paper surface, avoiding the hygroscopic paper from becoming soft and broken due to absorbing a large amount of moisture when wet; (3) Adding wet end additives in this scheme can improve the thickness and strength of paper. For example, cationic polyacrylamide can improve the retention and drainage performance of fibers, allowing paper to retain more water during the molding process, thereby forming thicker paper after drying; the wet strength agent is melamine formaldehyde resin, which forms a cross-linked structure between fibers through fiber chemical reaction, thereby improving the wet strength of paper; (4) The wood cellulose added in this scheme helps to improve water retention and enhance the strength of paper. The wood cellulose has a flocculent appearance, which plays an important role in achieving a high bulk effect. When combined with acrylic resin, it can absorb water repeatedly and can continue to absorb water after drying. The fiber structure of wood cellulose is relatively loose, and there are a large number of pores and capillaries between the fibers, which can form a capillary effect, allowing water to diffuse and penetrate quickly in the paper, thereby increasing the speed of moisture absorption; (5) The adhesive layer is structural adhesive, which helps to increase the bonding speed when heated and dried. The strength of structural adhesive is very high, which helps to improve the strength of paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the overall flow chart of Examples 1-4 of the present invention.

[0018] Figure 2Schematic diagram of the connection structure of the power system, the grinding system and the sand removal system in Examples 1-4 of the present invention.

[0019] Figure 3 Schematic diagram of the structure of the infrared drying oven in Examples 1-4 of the present invention.

[0020] Among them, the attached figures are as follows: 1. power system; 2. drive shaft; 3. grinding system; 4. sand removal system; 5. upper drying box; 6. generator; 7. lower drying box. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods.

[0022] Embodiment 1:

[0023] See also Figure 1 , the process of making high bulk, high water absorbency and high strength absorbent paper as shown in the figure includes the following steps: Step 1: Deflaking: Use a standard pulping pot to deflake the chemical long fiber and thermomechanical pulp separately to facilitate subsequent pulping.

[0024] Step 2: Pulping. After the different long fibers are deflated by the pulper, they are placed into the pulp pool and then pulped in different ways through a double disc mill.

[0025] Step 3: The flow system transports the mixed pulp after beating to the wire through the dilution water headbox Step 4: Fourdrinier and top wire forming, the pulp that flows in is mixed and then passed through the Fourdrinier and top wire formers to form the fiber paper surface Step 5: Pressing and drying: Pressing and drying the fiber paper surface after the fourdrinier mesh and the top mesh are formed to discharge the moisture and bubbles inside.

[0026] Step 6: Hot pressing and forming, the dried paper is processed through other equipment to roll the continuous paper into a tight and uniform roll.

[0027] In step 2, the beating degree of the thermomechanical pulp after deflaking is 20°SR; In step 4, the ratio of pulp speed to wire speed in the Fourdrinier wire and top wire former is adjusted to 0.98; In step 5, composite pressing for dehydration and light pressing for defect correction are used in pressing; In step 6, the paper sheet drying section requires a drying cylinder and infrared drying equipment.

[0028] Embodiment 2:

[0029] See also Figure 1 , the process of making high bulk, high water absorbency and high strength absorbent paper as shown in the figure includes the following steps: Step 1: Deflaking: Use a standard pulping pot to deflake the chemical long fiber and thermomechanical pulp separately to facilitate subsequent pulping; Step 2: beating, after the different long fibers are deflated by the pulper, they are placed in the pulp pool and then beaten differently by a double disc mill; Step 3: The flow conveying system conveys the mixed pulp after beating to the wire through the dilution water headbox; Step 4: Fourdrinier wire and top wire forming, the mixed slurry flowing through the Fourdrinier wire and top wire former is formed into a fiber paper surface; Step 5: Pressing and drying: Pressing and drying the fiber paper surface after the fourdrinier wire and the top wire are formed to remove the moisture and bubbles inside; Step 6: Hot pressing and forming, the dried paper is processed through other equipment to roll the continuous paper into a tight and uniform roll.

[0030] In step 2, the beating degree of the thermomechanical pulp after deflaking is 25°SR.

[0031] In step 4, the ratio of pulp speed to wire speed in the Fourdrinier wire and top wire former is adjusted to 0.98.

[0032] In step 5, composite pressing for dehydration and light pressing for defect correction are used in pressing.

[0033] In step 6, the paper sheet drying section requires a drying cylinder and infrared drying equipment.

[0034] Embodiment 3:

[0035] See also Figure 1 , the process of making high bulk, high water absorbency and high strength absorbent paper as shown in the figure includes the following steps: Step 1: Deflaking: Use a standard pulping pot to deflake the chemical long fiber and thermomechanical pulp separately to facilitate subsequent pulping; Step 2: beating, after the different long fibers are deflated by the pulper, they are placed in the pulp pool and then beaten differently by a double disc mill; Step 3: The flow conveying system conveys the mixed pulp after beating to the wire through the dilution water headbox; Step 4: Fourdrinier wire and top wire forming, the mixed slurry flowing through the Fourdrinier wire and top wire former is formed into a fiber paper surface; Step 5: Pressing and drying: Pressing and drying the fiber paper surface after the fourdrinier wire and the top wire are formed to remove the moisture and bubbles inside; Step 6: Hot pressing and forming, the dried paper is processed through other equipment to roll the continuous paper into a tight and uniform roll.

[0036] In step 2, the beating degree of the thermomechanical pulp after deflaking is 30°SR; In step 4, the ratio of pulp speed to wire speed in the Fourdrinier wire and top wire former is adjusted to 0.98; In step 5, composite pressing for dehydration and light pressing for defect correction are used in pressing; In step 6, the paper sheet drying section requires a drying cylinder and infrared drying equipment.

[0037] Embodiment 4:

[0038] See also Figure 2-Figure 3 The main equipment for the process of producing high-bulk, high-absorbent and high-strength hygroscopic paper includes double-disc refiner, complete separation sand remover, dilution water headbox, long wire, top wire former, film transfer sizing machine, infrared drying oven, drying cylinder and curling equipment.

[0039] The fully separated sand remover mainly consists of three parts: power system 1, grinding system 3, and sand removal system 4. Its power system 1 is mainly composed of motor and transmission device (including drive shaft 2), and the main functions are grinding system 3 and sand removal system 4. The grinding system 3 mainly consists of two parts: stator and rotor. The rotor is the core component of the grinding system 3. Its surface is distributed with teeth or blades of various shapes and sizes. Under high-speed rotation, it generates strong shear force, which can deaggregate and beat the pulp. The stator is mainly matched with the rotor and fixed on the housing or frame of the equipment. The sand removal system 4 mainly consists of a sand removal cone and a sand storage device. The sand removal cone has a conical structure, and the pulp enters the cone part at a certain pressure tangent. The heavy impurities in the pulp are thrown to the inner wall of the cone by the centrifugal force of the cone. The sand storage device is used to collect and store impurities separated from the pulp, and is cleaned regularly to ensure the normal operation of the sand remover.

[0040] The dilution water headbox is mainly composed of the main inlet pipe, the pulp distribution bundle pipe, the homogenizing chamber, the turbulence generator, the overflow chamber, the convergence zone, the upper and lower lips, the lip plate fine-tuning mechanism and the side flow. The function of the main inlet pipe is to evenly distribute the pulp sent from the round tube according to the width of the paper machine. The inner wall of the pulp distribution tube bundle is relatively rough, which can avoid the accumulation of fibers and the premature disappearance of micro-turbulence. The homogenizing chamber can ensure the ideal turbulence while effectively attenuating the pulse brought by the system and eliminating bubbles in the pulp. The turbulence generator prevents the occurrence of fiber flocculation and improves the uniformity of paper. There is also an overflow chamber to maintain the temperature of the liquid surface to release the air and floating pulp inside the pulp; the upper and lower lips are used to form a triangular convergence zone to achieve the ideal pulp distribution state. The fine-tuning mechanism divides the pulp distribution area into control intervals with a spacing of 70mm, and each interval is controlled by a separate regulating valve to control the flow of dilution water. The operator switches the valves at the corresponding position according to the quantitative banner displayed on the QCS system, and adjusts the amount of dilution water to achieve the purpose of controlling the quantitative banner. The paper machine has a small quantitative difference in banner, a smooth and good paper surface, and a significant increase in the uniformity value, which greatly improves the printing performance of the paper sheet. The dilution water headbox is an existing device and will not be described in detail.

[0041] The infrared drying box mainly heats and dries the paper by heat conduction, heat radiation and heat convection, and includes an upper drying box 5, a lower drying box 7, and a generator 6 arranged between the upper drying box 5 and the lower drying box 7. Heat conduction: The heating element transfers heat to the inner wall of the infrared drying box and the air. When the paper contacts the inner wall of the infrared drying box or the hot air, the heat is transferred to the paper by conduction, so that the moisture in the paper is heated and evaporated.

[0042] Thermal radiation: The infrared lamp radiant heat from the heating element directly irradiates the paper surface, causing the paper to absorb the radiation energy and heat up, accelerating the evaporation of water. Thermal convection: The circulating fan in the infrared drying box makes the hot air circulate continuously in the drying box, and the hot air exchanges heat with the paper surface, transferring heat to the paper through convection, while taking away the evaporated water on the paper surface.

[0043] Table 1 describes the effect of different New Zealand pulp and chemical fiber ratios on thickness data. In Table 1, data is compared by adding different materials of groundwood pulp and different ratios.

[0044] Table 2 describes the effect of different beating degrees on thickness and absorbent paper energy data.

[0045] Table 3 describes the data on the effect of press section pressure adjustment and infrared temperature adjustment on thickness.

[0046] Table 4 describes the effect of adding different amounts of amide and wet strength agent on thickness and wet strength.

[0047] Table 5 describes the effect of adding lignocellulose and acrylic resin on thickness data.

[0048] From the data in Tables 1 to 5, we can directly see the effects of different components and their different proportions on paper thickness, bulk, breaking length, water absorption height, wet strength and other properties.

[0049] Table 1 Effect of different New Zealand pulp and chemical fiber ratios on thickness data

[0050] Table 2 Effect of different beating degrees on thickness and moisture-absorbing paper energy data

[0051] Table 3 Data on the influence of pressure adjustment and infrared temperature adjustment on thickness in the press section

[0052] Table 4 Effect of adding different amounts of amide and wet strength agent on thickness and wet strength

[0053] Table 5 Effect of adding wood cellulose and acrylic resin on thickness data

[0054] As can be seen from Table 1, the thickness, bulk and breaking length of the three materials increase in turn, which means that compared with the original groundwood, New Zealand groundwood and New Zealand groundwood + polyester, New Zealand groundwood + polyester can produce better results. It can be seen from Table 2 that with the increase of beating degree, the data of thickness and moisture absorption paper energy gradually decrease, which indicates that a larger beating degree will have a counter-effect on papermaking; As can be seen from Table 3, the infrared drying process has better performance parameters of thickness and bulk than the previous compound press section drying; It can be seen from Table 4 that the performance parameters of thickness and bulk are better when cationic polyacrylamide dry powder and wet strength agent are added, and the performance parameters of thickness and bulk also gradually increase with the increase of the content of cationic polyacrylamide dry powder and wet strength agent; It can be seen from Table 5 that compared with the technical effect produced by polyester fiber alone, the addition of cellulose and acrylic resin, and as the content of the two increases, the thickness and bulk properties also increase. Therefore, the addition of cellulose and acrylic resin is of great significance for high-quality production.

[0055] It should be noted that the manufacturer of New Zealand thermomechanical pulp is New Zealand Winston International Pulp Company. Its advantages are that the fibers are stiff, providing good stiffness to the paper sheets; the bulk is high, the fibers are stiff and not easily flattened, and the gaps between them are large, which makes the paper have a higher bulk; it has good printing adaptability, good fiber morphology, and can improve the opacity and ink absorbency of the paper.

[0056] Technical features not described in the present invention can be achieved through or by adopting existing technologies and will not be described in detail here. Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. An improved papermaking process for high bulk, high water absorption and high strength hygroscopic paper, characterized in that: The specific steps include: Step 1: using a standard pulping pot to separately deflake the chemical long fiber pulp and the thermomechanical pulp; Step 2: After the chemical long fibers and thermomechanical pulp after debonding in step 1 are placed in different pulp pools, the pulping operation is performed by equipment; Step 3: The pulp after beating in step 2 is passed through a double-disc refiner and a complete separation sand remover to evenly disperse the fibers and maintain good water absorption uniformity; Step 4: After mixing the different pulps after beating in step 3, polyester fiber, wet end additives and wet strength agent are added to the mixed pulp at the same time according to the mass ratio of (9-12): (0.2-0.3): (5.0-10.0), and the mixed pulp is transported to the wire part through the dilution water headbox; Step 5: The mixed slurry is passed through a fourdrinier wire and a top wire former to form a fiber paper surface; Step 6: Press and dry the fiber paper surface formed by the fourdrinier wire and the top wire to remove the moisture and bubbles inside; Step 7: Use a film transfer sizing machine to apply glue to the paper squeezed and dried in step 6; Step 8: Infrared drying is performed on the glue coating on the paper, and then the dried and hot-pressed paper is rolled into a tight and uniform paper roll using a drying cylinder for hot pressing.

2. The improved papermaking process of high bulk, high water absorption and high strength moisture-absorbing paper according to claim 1, characterized in that: In the step 2, the beating degree of the chemical long fibers after debonding is 54-56°SR, and the beating degree of the thermo-chemical mechanical pulp is 20-30°SR.

3. The improved papermaking process of high bulk, high water absorption and high strength moisture-absorbing paper according to claim 1, characterized in that: In the step 3, in the fourdrinier wire and top wire former, the ratio of the pulp speed to the wire speed is adjusted to 0.

98.

4. The improved papermaking process of high bulk, high water absorption and high strength moisture-absorbing paper according to claim 1, characterized in that: In step 4, cellulose and acrylic resin are added simultaneously, and the mass ratio of cellulose and acrylic resin is (1.5-3.5): (2.0-3.0), and the ratio of the sum of the mass of cellulose and acrylic resin to the mass of polyester fiber is 0.3-0.

7.

5. The improved papermaking process of high bulk, high water absorption and high strength moisture-absorbing paper according to claim 1, characterized in that: In step 4, during pressing, composite pressing for dehydration and light pressing for defect correction are used.

6. The improved papermaking process of high bulk, high water absorption and high strength moisture-absorbing paper according to claim 1, characterized in that: In the step 8, the adhesive layer is structural adhesive.

7. An improved papermaking device for high-bulk, high-absorbent, high-strength hygroscopic paper, using the improved papermaking process for high-bulk, high-absorbent, high-strength hygroscopic paper as claimed in any one of claims 1 to 4, characterized in that: The invention comprises a double-disc pulping machine, a fully separated sand removing machine, a dilution water type pulping box, a fourdrinier former, a top net former, a pressing and drying structure, a film transfer sizing machine, an infrared drying box, a drying cylinder and a curling device which are connected in sequence. The fully separated sand removing machine comprises a power system, a grinding system (3) and a sand removing system (4).

8. The improved papermaking device for high bulk, high water absorption and high strength moisture-absorbing paper according to claim 7, characterized in that: The deburring system (3) comprises a stator and a rotor, teeth or blades are distributed on the surface of the rotor, and the rotor is connected to the power system (1) via a drive shaft (2); The stator is movably connected to the rotor and fixed on the housing or the frame.

9. The improved papermaking device for high bulk, high water absorption and high strength moisture-absorbing paper according to claim 7, characterized in that: The desanding system (4) comprises a desanding cone for throwing heavy impurities in the slurry toward the inner wall of the cone, and a sand storage container for collecting and storing impurities separated from the slurry and cleaning them regularly. The desanding cone has a cone-shaped structure.

10. The improved papermaking device for high bulk, high water absorption and high strength moisture-absorbing paper according to claim 7, characterized in that: The dilution water type headbox includes a homogenizing chamber, a turbulence generator connected to the homogenizing chamber, an overflow chamber connected to the turbulence generator, a main pulp inlet pipe and a pulp distribution bundle pipe connected to the homogenizing chamber, an upper lip plate and a lower lip plate connected to the overflow chamber, and the upper lip plate and the lower lip plate are connected to a lip plate fine-tuning mechanism.

Images