Papermaking felt for cultural paper

Abstract

The invention discloses a papermaking felt for cultural paper, and relates to the technical field of papermaking felts.The papermaking felt is formed by compounding fibers and a bottom net on a needling machine through a needling technology, and the papermaking felt is divided into surface layer fibers, middle layer fibers 2, middle layer fibers 1, a surface layer bottom net, a middle layer bottom net, a lower layer bottom net and reverse side fibers from top to bottom; by means of optimized mixing of the chinlon 6 fibers and the two-component fibers and addition of the compatilizer, the flatness of the surface of the blanket is remarkably improved, then the surface quality of paper is greatly improved, flaws are reduced, and due to unique combination of the middle-layer fibers, especially pre-stretching treatment of the spandex fibers, the surface smoothness of the blanket is greatly improved. The stability of the blanket and the dehydration effect of paper in the papermaking process are ensured, the overall structural strength and the dehydration performance of the blanket are enhanced through staggered laying of the nanoscale hydrophobic coating of the monofilament bottom net and the reverse side fibers, and meanwhile the service life is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking felts, in particular to a papermaking felt for cultural paper. Background Art

[0002] In the papermaking industry, papermaking felts are key auxiliary materials in the paper production process. Their quality and performance directly affect the production efficiency and quality of paper. Traditional papermaking felts are mostly made of single fiber materials and compounded through a simple needle punching process. They have problems such as low surface flatness, poor elastic recovery performance, severe fiber shedding and poor dehydration performance, which make it difficult to meet the modern papermaking industry's demand for high-quality paper.

[0003] Specifically, the surface fibers of traditional papermaking felts are often made of single nylon fibers, which lack sufficient flatness and fineness, resulting in defects on the paper surface and affecting the overall quality of the paper. At the same time, due to the lack of elasticity of traditional felts, they cannot adapt well to the changes in tension during the papermaking process, which can easily cause the felts to deform, thereby affecting the production efficiency and stability of the paper. In addition, traditional felts also have prominent problems of fiber shedding and clogging, which not only shortens the service life of the felts, but also increases downtime and maintenance costs during the papermaking process.

[0004] In order to solve the above problems, the industry began to explore new papermaking felt structures and manufacturing processes. Among them, the use of multi-layer fiber composite structures and special combing processes has become an effective way to improve the performance of papermaking felts. However, the existing multi-layer fiber papermaking felts still have some problems, such as loose bonding between fibers, insufficient elastic recovery performance, unstable dehydration performance, etc. These problems limit the further application and development of papermaking felts.

[0005] Therefore, the present invention proposes a brand-new papermaking felt for cultural paper to solve the above-mentioned problems existing in traditional papermaking felts. Summary of the invention

[0006] The purpose of the present invention is to make up for the shortcomings of the prior art and provide a papermaking felt for cultural paper. The present invention significantly improves the flatness of the felt surface by utilizing the optimized mixing of nylon 6 fiber and two-component fiber and the addition of a compatibilizer, thereby greatly improving the surface quality of the paper and reducing defects. Secondly, the unique combination of middle-layer fibers, especially the pre-stretching treatment of spandex fibers, ensures the stability of the felt and the dehydration effect of the paper during the papermaking process. The nano-scale hydrophobic coating of the monofilament bottom mesh and the staggered laying of the back fibers enhance the overall structural strength and dehydration performance of the felt, while extending its service life.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a papermaking felt for cultural paper, the felt is compounded by fibers and a bottom net on a needle punching machine through a needle punching process, and is divided from top to bottom into surface fibers, middle fibers 2, middle fibers 1, surface bottom net, middle bottom net, lower bottom net and back fibers;

[0008] The surface fiber is a nylon 6 fiber mixed with a bicomponent fiber with a mixing ratio of 90 / 10-70 / 30 between 11-17 dtex, the inner layer of the bicomponent fiber is a conventional nylon 6 fiber, and the outer layer is a fusible fiber with a melting point of about 140°C. The surface fiber is designed to be two layers, and the gram weight is between 100-120gsm;

[0009] The middle layer fiber 2 is 44dtex nylon 6 fiber mixed with spandex fiber, the mixing ratio is 50 / 50-70 / 30, it is designed as two layers, and the gram weight is between 150-170gsm. The spandex fiber molecular chain in the middle layer fiber 2 contains amino (-NH2) and carboxyl (-COOH) as specific functional groups. Under the conditions of temperature 25°C and relative humidity 65%, the amino and carboxyl groups can form hydrogen bonds with water molecules. The surface of the spandex fiber is treated by plasma etching to form a unique microscopic rough structure with an average roughness (Ra) of 0.5-1.5 microns.

[0010] The middle layer fiber 1 is 110dtex nylon 6 fiber with a gram weight of about 200gsm;

[0011] The surface bottom mesh material is nylon 6, 3 / 1 broken twill structure, warp yarn 0.23, weft yarn 0.23, warp density 96, weft density 80, and gram weight is about 280gsm;

[0012] The middle bottom net and the lower bottom net are the same bottom net, the raw material is nylon 6, 1 / 1 plain weave, warp yarn 0.451, weft yarn 0.41, warp density 80, weft density 80, and weight about 260;

[0013] The back layer material is 44dtex nylon 6 fiber with a gram weight of about 200gsm;

[0014] The blanket is shaped by applying hot oil rollers on both sides to spray water and apply pressure.

[0015] Furthermore, the warp and weft yarns of the surface bottom net are twisted yarns, the middle bottom net and the lower bottom net are monofilament bottom nets, and the twist of the twisted yarns is specially designed. The twist range of the twisted yarns of the surface bottom net is 15-25 twists / 10cm. Through this bottom net combination selection and twist design of the twisted yarn, it is ensured that the blanket has good adhesion and dehydration channel. The surface of the monofilament of the monofilament bottom net has a nano-scale hydrophobic coating, which can reduce the adhesion of water on the surface of the bottom net and further optimize the performance of the dehydration channel.

[0016] Furthermore, the two-component fiber in the surface fiber is melted by the outer layer fusible fiber after shaping, and a trace amount of compatibilizer is added during the melting process. The compatibilizer is an organic compound containing an ester group (-COO-) and an ether bond (-O-), wherein the molar ratio of the ester group to the ether bond is 1:2. The compatibilizer can promote the fusion between the fusible fiber and the nylon 6 fiber, so that the floating hair on the surface of the blanket is evenly attached to the blanket, thereby achieving a smoother and more delicate blanket surface.

[0017] Furthermore, the mixing ratio of the spandex fiber in the middle layer fiber 2 is 50 / 50-70 / 30, and before the spandex fiber is mixed with the nylon 6 fiber, the spandex fiber is pre-stretched with a pre-stretching multiple of 1.2-1.5 times. The good elastic recovery of the spandex fiber and the characteristics after pre-stretching are utilized to further shorten the initial adaptability of the blanket. The spandex fiber after pre-stretching can adapt to tension changes more quickly during the use of the blanket.

[0018] Furthermore, the middle layer fiber 1 adopts 110dtex coarse fiber, the surface of which is coated with a thin flexible polymer layer made of polyurethane, which makes the interior of the blanket open and not easy to be blocked, while improving the wear resistance of the fiber, thereby extending the service life of the blanket.

[0019] Furthermore, the mixing ratio of nylon 6 fiber and bicomponent fiber in the surface fiber is 90 / 10-70 / 30, and an antioxidant is added during the mixing process, and the added amount of the antioxidant is 0.1%-0.3% of the total weight of the fiber. The antioxidant is a hindered phenol antioxidant. By setting the ratio range and adding the antioxidant, the balance of the surface performance and the overall performance of the blanket is ensured, and the fiber is prevented from aging due to oxidation during use.

[0020] Furthermore, the gram weight ranges of nylon 6 fiber and spandex fiber in the middle layer fiber 2 are 150-170gsm and 75-113.3gsm respectively, and a special combing process is adopted in the production of the middle layer fiber 2, and the combing process is as follows: first, the fibers are preliminarily combed using a cylinder with a needle cloth density of 400-500 teeth / square inch, and then the fibers are transferred through a configuration in which the speed ratio between the doffer and the cylinder is 1:1.5-1:2, and finally, fine combing is performed under the condition that the spacing between the cover plate and the cylinder is 0.2-0.3mm. The combing angle in the combing process is 70°-80°, so as to ensure that the middle layer fiber 2 plays a corresponding role in the blanket structure and makes the fiber distribution more uniform.

[0021] Furthermore, the warp yarn specification of the middle bottom net and the lower bottom net is 0.451, the weft yarn specification is 0.41, the warp density and weft density are both 80, the gram weight is about 260, and the warp yarn and weft yarn are plasma treated during the bottom net production process. The power of the plasma treatment is 300-500W, and the treatment time is 30-60 seconds. This parameter setting and plasma treatment are helpful to the dehydration performance and overall structural stability of the blanket, improve the activity of the fiber surface, and enhance the bonding force between fibers.

[0022] Furthermore, the back fiber has a gram weight of about 200gsm and is 44dtex nylon 6 fiber, and the back fiber is laid in an interlaced manner during the laying process, and the laying angle between two adjacent layers of back fibers is 30°-60°, which provides corresponding support and performance supplement for the back of the blanket, thereby improving the structural strength and stability of the back of the blanket.

[0023] Compared with the prior art, the papermaking felt for cultural paper has the following beneficial effects:

[0024] 1. The papermaking felt of the present invention adopts a mixture of carefully proportioned nylon 6 fiber and bicomponent fiber as the surface fiber, and through a specific shaping process and the use of a compatibilizer, the floating hair on the surface of the felt is evenly fitted, which significantly improves the surface flatness, reduces the defects of paper in the production process, and effectively improves the overall quality of the paper.

[0025] 2. The present invention adds spandex fiber to the middle layer fiber and undergoes pre-stretching and plasma etching treatment, which not only has excellent elastic recovery performance and can quickly adapt to tension changes in the papermaking process and reduce deformation, but also significantly improves the friction between fibers and enhances the overall structural stability of the blanket.

[0026] 3. The papermaking felt of the present invention adopts a specially designed bottom mesh structure and a nano-scale hydrophobic coating, which significantly optimizes the performance of the dehydration channel and reduces the adhesion of water on the bottom mesh surface. At the same time, by adopting highly wear-resistant fibers and a fine combing process, the wear resistance and service life of the felt are improved.

[0027] Other advantages, objectives and features of the present invention will be set forth in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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 prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 The present invention is a structural diagram of a papermaking felt for cultural paper;

[0030] Figure 2 A schematic diagram of nylon 6 for a papermaking felt for cultural paper.

[0031] Among them: 1. Surface fiber; 2. Middle fiber 2; 3. Middle fiber 1; 4. Surface bottom net; 5. Middle bottom net; 6. Lower bottom net; 7. Back fiber; 8. Nylon 6; 9. Fusible fiber. DETAILED DESCRIPTION

[0032] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0033] 1. The structure of papermaking felt:

[0034] Fiber layer structure:

[0035] Surface fiber:

[0036] Choose nylon 6 fiber with a dtex of 11-17 and mix it with the two-component fiber, with a mixing ratio of 90 / 10-70 / 30. The inner layer of the two-component fiber is conventional nylon 6 fiber, and the outer layer is fusible fiber with a melting point of about 140°C. It is designed as two layers with a gram weight of 100-120gsm. For example, when the mixing ratio is 80 / 20, prepare the corresponding weight of nylon 6 fiber and two-component fiber respectively, put them into professional fiber mixing equipment, set the mixing time to 30-60 minutes, and the mixing speed to 100-200 rpm to ensure that the fibers are fully mixed and evenly mixed.

[0037] Middle fiber 2:

[0038] It is a mixture of 44dtex nylon 6 fiber and spandex fiber in a mixing ratio of 50 / 50-70 / 30. It is also designed as two layers with a gram weight between 150-170gsm. The spandex fiber molecular chain contains amino (-NH2) and carboxyl (-COOH) functional groups. At a temperature of 25°C and a relative humidity of 65%, the amino and carboxyl groups can form hydrogen bonds with water molecules. The surface of the spandex fiber is treated with plasma etching to form a microscopic rough structure with an average roughness (Ra) of 0.5-1.5 microns. Taking a mixing ratio of 60 / 40 as an example, the spandex fiber is first pre-stretched with a pre-stretching multiple of 1.2-1.5 times. Professional stretching equipment is used to slowly stretch the spandex fiber with a stretching speed controlled at 1-2 meters / minute. The stretching multiple is monitored in real time during the stretching process to ensure that the requirements are met. The pre-stretched spandex fiber is mixed with nylon 6 fiber in proportion and then combed.

[0039] Middle fiber 1:

[0040] 110dtex nylon 6 fiber is used with a gram weight of about 200gsm. The surface of the crude fiber is coated with a thin flexible polymer layer made of polyurethane. First, the 110dtex nylon 6 fiber is prepared, and then the polyurethane is evenly coated on the fiber surface through a special coating process. During the coating process, the coating amount of polyurethane is controlled to be 5%-10% of the fiber weight, and the coating speed is 0.5-1m / min to ensure that the coating layer is uniform and thin, so that the interior of the blanket is open and not easy to be blocked, while improving the wear resistance of the fiber.

[0041] Back fiber:

[0042] The nylon 6 fiber of 44dtex has a gram weight of about 200gsm. The staggered laying method is adopted during the laying process. The laying angle between the two adjacent layers of reverse fibers is 30°-60°. For example, the first layer of reverse fibers is laid in the horizontal direction, and the second layer is laid at an angle of 45° to the horizontal direction. During laying, the laying density of each layer of fibers is controlled at 50-100 fibers / square centimeter, which is achieved through precise laying equipment to ensure good support and performance supplement for the reverse side of the blanket, thereby improving the structural strength and stability of the reverse side of the blanket.

[0043] Bottom net structure:

[0044] Surface bottom net:

[0045] The raw material is nylon 6, with a 3 / 1 broken twill structure, warp yarn 0.23, weft yarn 0.23, warp density 96, weft density 80, and a gram weight of about 280gsm. The warp and weft yarns are plied yarns, and the twist range of the plied yarns is 15-25 twists / 10cm. When making the surface bottom net, the nylon 6 raw material is first made into plied yarns. During the twisting process, the twist is accurately controlled within the range of 15-25 twists / 10cm through the twist adjustment equipment, and the twisting speed is 50-100 rpm. Then it is woven according to the 3 / 1 broken twill structure. During the weaving process, the tension of the warp and weft yarns is controlled between 5-10 Newtons to ensure that the bottom net structure is stable and has good cohesion and dehydration channels.

[0046] Middle bottom net and lower bottom net:

[0047] It is the same bottom net, the raw material is nylon 6, 1 / 1 plain weave, warp yarn 0.451, weft yarn 0.41, warp density and weft density are both 80, gram weight is about 260, warp yarn and weft yarn are monofilament bottom net, the surface of monofilament has nano-scale hydrophobic coating, in the process of making the bottom net, firstly, the warp yarn and weft yarn are plasma treated, the power of plasma treatment is 300-500W, the treatment time is 30-60 seconds, the warp yarn and weft yarn are placed in the plasma treatment equipment, the power and time are set, the surface activity of the treated yarn is enhanced, and then 1 / 1 plain weave is carried out, the weaving speed is controlled at 20-30 cm / min, after weaving, the nano-scale hydrophobic coating is coated on the surface of the monofilament, the coating thickness is 0.1-0.2 micron, the coating method can be dipping or spraying to ensure uniform coating, reduce the adhesion of water on the surface of the bottom net, and optimize the performance of the dehydration channel.

[0048] 2. Production process of papermaking felt:

[0049] Fiber blending and carding:

[0050] For the surface fibers, nylon 6 fiber and two-component fiber are mixed in a mixing device according to the above mixing ratio, and then combed. During combing, a carding machine with a needle cloth density of 300-400 teeth / square inch and a combing speed of 30-50 meters / minute are used to initially straighten and parallel the fibers.

[0051] The combing process of the middle layer fiber 2 is as follows: first, the fibers are preliminarily combed using a cylinder with a needle cloth density of 400-500 teeth / square inch, and the combing speed is 20-40 m / min. Then, the fibers are transferred through a configuration with a speed ratio of 1:1.5-1:2 between the doffer and the cylinder. Finally, fine combing is performed under the condition that the spacing between the cover plate and the cylinder is 0.2-0.3 mm. The combing angle in the combing process is 70°-80°. During the entire combing process, the parameters of each device are strictly controlled to ensure a more uniform fiber distribution.

[0052] When combing the middle layer fiber 1 and the back side fiber, a carding machine with a card cloth density of 350-450 teeth / square inch and a carding speed of 25-45 meters / minute can be used to make the fibers straight and parallel to facilitate subsequent laying and needle punching compounding.

[0053] Acupuncture composite process:

[0054] The combed surface fibers, middle fibers 2, middle fibers 1 and back fibers are laid on the workbench of the needle loom in a top-down order, and the surface bottom net, middle bottom net and lower bottom net are also placed in corresponding positions.

[0055] Start the needling machine, set the needling frequency to 800-1200 times / minute, and the needling depth to 8-12 mm. During the needling process, gradually increase the needling density from the initial 50-80 needles / square centimeter to 150-200 needles / square centimeter, so that the fibers and the bottom net are entangled and consolidated through needling to form an integral structure. During the needling process, monitor the thickness and density of the blanket in real time to ensure that it meets the design requirements.

[0056] Molding process:

[0057] After the needle-punched composite of the blanket is completed, it is subjected to shaping treatment. The shaping is carried out by pressing the hot oil rollers on both sides. The front and back sides of the blanket are pressed against the hot oil rollers respectively. The temperature of the hot oil rollers is controlled at 120-160℃. At the same time, water is sprayed on the surface of the blanket. The water spray volume is 50-100 ml / m2. A certain pressure is applied while spraying water. The pressure range is 0.5-1.5 MPa. The structure of the blanket is further stabilized under the action of heat and pressure, and the fusible fibers in the surface fibers are melted.

[0058] During the melting process of the fusible fiber, a small amount of compatibilizer is added. The compatibilizer is an organic compound containing an ester group (-COO-) and an ether bond (-O-), wherein the molar ratio of the ester group to the ether bond is 1:2. The amount of the compatibilizer added is 0.1%-0.3% of the total weight of the fiber. The compatibilizer is dissolved in an appropriate amount of organic solvent to prepare a solution with a concentration of 10%-20%, which is then evenly sprayed on the surface of the blanket through a spray device to promote the fusion between the fusible fiber and the nylon 6 fiber, so that the floating hair on the surface of the blanket is evenly attached to the blanket, making the blanket surface smoother and more delicate.

[0059] 3. Function and effect verification of each part of the papermaking felt structure:

[0060] Surface fiber:

[0061] Function: The surface fibers are in direct contact with the paper, and their structure and performance have a great influence on the surface quality of the paper. Nylon 6 fiber has high strength and wear resistance, which can ensure the durability of the blanket during use. The fusible fiber in the two-component fiber melts during the shaping process and fuses with the nylon 6 fiber, making the blanket surface smoother and more delicate, reducing defects on the paper surface.

[0062] Effect verification:

[0063] Surface smoothness test: A high-precision surface roughness meter was used to test the surface of the blanket. Ten test points were selected at different locations to measure the roughness value (Ra) of the blanket surface. After actual testing, the blanket made using the surface fiber structure and process of the present invention had a surface roughness value (Ra) between 0.5 and 1.0 microns, which was significantly improved compared to traditional blankets (surface roughness value Ra between 1.5 and 2.5 microns), indicating that the blanket surface was smoother and more delicate.

[0064] Observation of fiber fusion: By observing the fusion of fibers on the surface of the blanket through a scanning electron microscope (SEM), it can be seen that after adding the compatibilizer, the fusion between the fusible fiber and the nylon 6 fiber is tighter, the gap between the fibers is reduced, and the fiber distribution is more uniform, which helps to improve the surface performance of the blanket and thus improve the surface quality of the paper.

[0065] Middle fiber 2:

[0066] Function: The addition of spandex fiber gives the felt good elasticity, which can adapt to the tension changes in the papermaking process and reduce the deformation of the felt. The amino and carboxyl groups in the spandex fiber molecular chain form hydrogen bonds with water molecules, which can adjust the humidity of the felt and help the dehydration process of paper. The unique microscopic rough structure increases the friction between fibers and further improves the structural stability of the felt.

[0067] Effect verification:

[0068] Elastic recovery performance test: The blanket samples were cut into specimens of a certain size and subjected to a tensile test on a tensile testing machine. The stretching speed was set to 50 mm / min and the stretching amplitude was set to 20%-50%. The blanket was then unloaded and the elastic recovery rate was measured. After multiple tests, the elastic recovery rate of the blanket with the middle layer fiber 2 structure of the present invention was between 90% and 95%, while the elastic recovery rate of the traditional blanket was between 80% and 85%, indicating that the blanket of the present invention has better elastic recovery performance and can adapt to tension changes more quickly.

[0069] Humidity regulation performance test: The blanket sample was placed in a humidity-controlled environmental chamber with the initial humidity set at 30%-40%, and then the ambient humidity was gradually increased to 80%-90%. A humidity sensor was used to monitor the humidity changes inside the blanket in real time. The test results showed that the blanket of the present invention can reach humidity balance in a shorter time (1-2 hours), and the humidity change range is smaller (±5%). Compared with traditional blankets (humidity balance time 3-4 hours, humidity change range ±10%), its humidity regulation performance is better, which is conducive to the stable progress of the paper dehydration process.

[0070] Middle fiber 1:

[0071] Function: 110dtex coarse fiber provides good support strength for the felt, making it difficult for the felt to deform when it is under the pressure of paper and equipment. The polyurethane flexible polymer layer coated on the surface not only improves the wear resistance of the fiber, but also keeps the internal structure of the felt open and not easy to be blocked, which is conducive to the transfer of paper fibers and the long-term use of the felt.

[0072] Effect verification:

[0073] Wear resistance test: The Martindale abrasion tester was used to test the wear resistance of the blanket. The test pressure was set to 500-1000 grams and the number of frictions was set to 5000-10000 times. After the test, the wear on the surface of the blanket was observed and the wear depth was measured. After testing, the wear depth of the blanket with the middle layer fiber 1 structure of the present invention was between 0.2-0.5 mm, while the wear depth of the traditional blanket was between 0.8-1.2 mm, indicating that the wear resistance of the blanket of the present invention is significantly improved.

[0074] Internal structure observation: By observing the internal structure of the blanket through an optical microscope, it can be seen that the gaps between the internal fibers of the blanket of the present invention are relatively large, there is no obvious blockage, and the fibers are arranged neatly and orderly, which is conducive to the transfer of paper fibers in the blanket, reduces problems such as paper linting, and extends the service life of the blanket.

[0075] Surface bottom net, middle bottom net and lower bottom net:

[0076] Function: The twisted yarn structure and specific twist design of the surface bottom net make it have good cohesion, which can better fix the surface fibers and prevent them from falling off. The monofilament structure and nano-scale hydrophobic coating of the middle bottom net and the lower bottom net help the water to pass through quickly, optimize the dehydration channel performance, and improve the overall structural stability of the blanket.

[0077] Effect verification:

[0078] Adhesion performance test: The blanket was subjected to a fiber shedding test. The blanket sample was vibrated at a certain vibration frequency (100-200 Hz) and amplitude (5-10 mm) for 1-2 hours, and the shed fibers were collected and weighed. After testing, the fiber shedding amount of the blanket of the present invention was between 0.5-1.0 grams, while the fiber shedding amount of the traditional blanket was between 2-3 grams, indicating that the surface bottom net had good adhesion.

[0079] Dehydration performance test: In an experimental device simulating the papermaking dehydration process, a felt is installed in the device, and pulp containing a certain amount of moisture (moisture content 30%-40%) is allowed to pass through the felt, and the moisture content of the pulp after passing through the felt is measured. The test results show that the moisture content of the pulp treated with the felt with the bottom mesh structure of the present invention can be reduced to 10%-15%, while the moisture content of the pulp treated with the traditional felt is between 20%-25%, indicating that the dehydration performance of the felt of the present invention is significantly improved. At the same time, by monitoring the structural stability of the felt during use, it is found that the felt structure of the present invention is less deformed and can still maintain good performance after long-term use.

[0080] Back fiber:

[0081] Function: The staggered laying of the back fibers provides sufficient support strength for the back of the blanket, enhances the overall structural stability of the blanket, prevents the blanket from delamination during use, and also helps to improve the performance of the back of the blanket, such as fit with the equipment.

[0082] Effect verification:

[0083] Structural strength test: A universal material testing machine was used to perform a tensile test on the blanket. The tensile direction was perpendicular to the laying direction of the fibers on the back of the blanket. The tensile speed was set to 10-20 mm / min. The tension was gradually increased until the blanket broke. The tension value at the time of fracture was recorded. After testing, the breaking tension of the blanket with the back fiber structure of the present invention was between 500-800 Newtons, while the breaking tension of the traditional blanket was between 300-500 Newtons, indicating that the structural strength of the back of the blanket of the present invention is significantly improved.

[0084] Observation of stratification: The blanket samples were repeatedly folded and unfolded for 50-100 times, and then the back of the blanket was observed to see if there was any stratification. After the test, no obvious stratification was found on the back of the blanket of the present invention, while stratification began to occur on the traditional blanket after 30-50 folds, indicating that the back fiber laying method of the present invention effectively improves the structural stability of the blanket.

[0085] In summary, the papermaking felt for cultural paper of the present invention has significant advantages in improving the surface quality of paper, improving the performance of the felt and extending the service life through the careful design of the structure of each part and the optimization of the production process. It can meet the high quality requirements in the production process of cultural paper. In the actual production and application process, the structure and process parameters of the felt can be appropriately adjusted according to the specific paper variety and production equipment conditions to achieve the best use effect.

[0086] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A papermaking felt for cultural paper, characterized in that: The blanket is formed by compounding fibers and a bottom net on a needle punching machine through a needle punching process, and is divided from top to bottom into a surface fiber (1), a middle fiber 2 (2), a middle fiber 1 (3), a surface bottom net (4), a middle bottom net (5), a lower bottom net (6) and a back fiber (7); The surface fiber (1) is a nylon 6 (8) fiber mixed with a bicomponent fiber with a dtex of 11-17, and the mixing ratio is 90 / 10-70 / 30. The inner layer of the bicomponent fiber is a conventional nylon 6 (8) fiber, and the outer layer is a fusible fiber (9) with a melting point of about 140° C. The surface fiber (1) is designed to be two layers, and the gram weight is between 100-120 gsm. The middle layer fiber 2 (2) is a 44dtex nylon 6 (8) fiber mixed with spandex fiber, the mixing ratio is 50 / 50-70 / 30, and it is designed as two layers with a gram weight between 150-170gsm. The spandex fiber molecular chain in the middle layer fiber 2 (2) contains amino (-NH2) and carboxyl (-COOH) as specific functional groups. Under the conditions of temperature 25°C and relative humidity 65%, the amino and carboxyl groups can form hydrogen bonds with water molecules. The surface of the spandex fiber is treated with plasma etching to form a unique microscopic rough structure with an average roughness (Ra) of 0.5-1.5 microns. The middle layer fiber 1 (3) is 110dtex nylon 6 (8) fiber with a gram weight of about 200gsm; The surface bottom mesh (4) is made of nylon 6 (8), 3 / 1 broken twill structure, warp yarn 0.23, weft yarn 0.23, warp density 96, weft density 80, and a gram weight of about 280gsm; The middle bottom net (5) and the lower bottom net (6) are the same bottom net, made of nylon 6 (8), 1 / 1 plain weave, warp yarn 0.451, weft yarn 0.41, warp density 80, weft density 80, and weight about 260 grams; The back layer material is 44dtex nylon 6(8) fiber with a gram weight of about 200gsm; The blanket is shaped by applying hot oil rollers on both sides to spray water and apply pressure.

2. A papermaking felt for cultural paper according to claim 1, characterized in that: The warp and weft yarns of the surface bottom net (4) are twisted yarns, the middle bottom net (5) and the lower bottom net (6) are monofilament bottom nets, and the twist of the twisted yarns is specially designed. The twist of the twist of the surface bottom net (4) is in the range of 15-25 twists / 10cm, and the surface of the monofilaments of the monofilament bottom net has a nano-scale hydrophobic coating.

3. A papermaking felt for cultural paper according to claim 1, characterized in that: The two-component fiber in the surface fiber (1) is melted by the outer fusible fiber (9) after being shaped, and a small amount of a compatibilizer is added during the melting process. The compatibilizer is an organic compound containing an ester group (-COO-) and an ether bond (-O-), wherein the molar ratio of the ester group to the ether bond is 1:

2. The compatibilizer can promote the fusion between the fusible fiber (9) and the nylon 6 (8) fiber, so that the floating hair on the surface of the blanket is evenly attached to the blanket.

4. A papermaking felt for cultural paper according to claim 1, characterized in that: The mixing ratio of the spandex fiber in the middle layer fiber 2 (2) is 50 / 50-70 / 30, and before the spandex fiber is mixed with the nylon 6 (8) fiber, the spandex fiber is pre-stretched with a pre-stretching multiple of 1.2-1.5 times.

5. A papermaking felt for cultural paper according to claim 1, characterized in that: The middle layer fiber 1 (3) is a coarse fiber of 110 dtex, the surface of which is coated with a thin flexible polymer layer, and the material of the flexible polymer layer is polyurethane.

6. A papermaking felt for cultural paper according to claim 1, characterized in that: The mixing ratio of nylon 6 (8) fiber and bicomponent fiber in the surface fiber (1) is 90 / 10-70 / 30. An antioxidant is added during the mixing process. The added amount of the antioxidant is 0.1%-0.3% of the total weight of the fiber. The antioxidant is a hindered phenol antioxidant.

7. A papermaking felt for cultural paper according to claim 1, characterized in that: The gram weights of the nylon 6(8) fibers and the spandex fibers in the middle layer fibers 2(2) are in the range of 150-170 gsm and 75-113.3 gsm, respectively. A special combing process is adopted in the production of the middle layer fibers 2(2). The combing process is as follows: firstly, the fibers are preliminarily combed using a cylinder with a needle cloth density of 400-500 teeth / square inch, and then the fibers are transferred by configuring the speed ratio between the doffer and the cylinder to be 1:1.5-1:

2. Finally, fine combing is performed under the condition that the spacing between the cover plate and the cylinder is 0.2-0.3 mm. The combing angle in the combing process is 70°-80°.

8. The papermaking felt for cultural paper according to claim 1, characterized in that: The warp yarn specification of the middle bottom net (5) and the lower bottom net (6) is 0.451, the weft yarn specification is 0.41, the warp density and weft density are both 80, and the gram weight is about 260. In addition, during the bottom net production process, the warp yarn and the weft yarn are subjected to plasma treatment, the power of the plasma treatment is 300-500W, and the treatment time is 30-60 seconds.

9. A papermaking felt for cultural paper according to claim 1, characterized in that: The back surface fiber (7) has a gram weight of about 200 gsm and is a 44 dtex nylon 6 (8) fiber. The back surface fiber (7) is laid in an interlaced manner, and the angle between the laying directions of two adjacent layers of back surface fiber (7) is 30°-60°.

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