Green, environment-friendly and economical ultra-high molecular weight polyethylene fiber paper and preparation method thereof

Abstract

The invention relates to the technical field of ultra-high molecular weight polyethylene fibers, in particular to environment-friendly and economical ultra-high molecular weight polyethylene fiber paper and a preparation method thereof. The preparation method comprises the following steps: dispersing ultra-high molecular weight polyethylene short fibers by using ultra-high molecular weight polyethylene fiber dispersion liquid to obtain mixed slurry, and performing natural filtration, wet pressure dehydration and drying to obtain a fiber paper skeleton; and dipping the fiber paper skeleton into an adhesive solution for sizing treatment, drying, and carrying out hot pressing treatment to obtain the ultra-high molecular weight polyethylene fiber paper. Wherein a solute of the UHMWPE fiber dispersion liquid comprises polyoxyethylene and an emulsifier, a solvent is a mixed solution of water and alcohol, and generation of a large amount of corrosive liquid or waste liquid in the UHMWPE fiber paper manufacturing process can be avoided. According to the preparation method of the ultra-high molecular weight polyethylene fiber paper, the bonding strength between the UHMWPE fibers can be improved, meanwhile, hot press molding can be conducted at the low temperature, and fiber softening deformation caused by the fact that the processing temperature is too high is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-high molecular weight polyethylene fibers, and in particular to a green, environmentally friendly and economical ultra-high molecular weight polyethylene fiber paper and a preparation method thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) fiber, as a high-performance material, has become a core material in the fields of ballistic protection, marine engineering, biomedicine, etc. due to its excellent specific strength, corrosion resistance, wear resistance and impact resistance. At present, UHMWPE fiber-reinforced composite materials are mainly in the form of unidirectional cloth, woven fabrics or short-cut fiber filling, and their products have outstanding performance in terms of lightweight and mechanical properties. However, the product form of existing UHMWPE composite materials is highly dependent on traditional fiber processing technology, and the development of new structural materials (such as paper-based materials, porous films, etc.) has not yet achieved a large-scale breakthrough, resulting in its application in high value-added fields being limited.

[0003] Paper-based materials, due to their lightweight, highly designable, and porous and breathable properties, offer irreplaceable advantages in insulation, filter media, and functional composite materials. For example, aramid paper, produced through a wet-laid forming process, offers high-temperature resistance and strength. However, the production process requires the use of large amounts of adhesive fibers, reinforcing agents, organic solvents, or acid. This results in the need for additional recycling of the residual filtrate after filtration, a process that is not only complex and costly, but also poses environmental risks.

[0004] The development of UHMWPE fiber-based paper materials is still in its infancy. This is primarily due to factors such as UHMWPE's inherent hydrophobicity, low melting temperature, and density less than water. This precludes the use of the same dispersion and bonding processes as high-density, high-temperature-resistant organic fibers such as aramid, carbon, and PBO. Existing UHMWPE fiber dispersion processes utilize hydrophilic osmotic treatment and re-dispersion to address these issues. However, the osmotic treatment and the addition of reinforcing agents to the dispersion liquid in this method result in the generation of significant amounts of waste liquid. The existing UHMWPE fiber bonding process prepares UHMWPE fiber paper through hot pressing and EVA resin reinforcement technology. During the hot pressing and resin reinforcement process, on the one hand, the melting temperature of UHMWPE fiber is about 134°C, while the processing / melting temperature of most resins is higher than the melting temperature of UHMWPE fiber. Excessive hot pressing temperature will cause the fiber to soften and deform, resulting in a loss of fiber body strength. For example, "Structure and performance characterization of HMWPE fiber paper, Wang Changhong, Long Zhu, Zhang Fengshan, et al." used the micromorphology of fiber paper after hot pressing under conditions above the softening temperature of UHMWPE (150°C) ( Figure 1 ); On the other hand, due to the chemical inertness of the UHMWPE fiber surface, it is difficult for general resins to produce strong bonding.

[0005] Therefore, there is an urgent need to find a new green, environmentally friendly, low-cost UHMWPE fiber dispersion process, as well as a bonding process with a low processing / melting temperature and the ability to produce a strong bonding effect on UHMWPE fibers, in order to solve the problem of insufficient strength of fiber paper. Summary of the Invention

[0006] To address the technical issues existing in the prior art UHMWPE fiber dispersion and bonding processes, the present invention provides an ultra-high molecular weight polyethylene fiber dispersion and a method for preparing ultra-high molecular weight polyethylene fiber paper. The ultra-high molecular weight polyethylene fiber dispersion provided by the present invention can disperse ultra-high molecular weight polyethylene fibers while avoiding the generation of large amounts of corrosive liquids or waste liquids during the UHMWPE fiber paper manufacturing process. The method for preparing ultra-high molecular weight polyethylene fiber paper provided by the present invention can improve the bonding strength between UHMWPE fibers and can be hot-pressed at relatively low temperatures, avoiding fiber softening and deformation caused by using excessively high processing temperatures.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention is an ultra-high molecular weight polyethylene fiber dispersion, wherein the solute of the ultra-high molecular weight polyethylene fiber dispersion includes polyethylene oxide (PEO) and an emulsifier, and the solvent is a mixed solution of water and alcohol.

[0009] In the present invention, the water-alcohol mixture reduces the buoyancy of ultra-high molecular weight polyethylene fibers, allowing low-density UHMWPE fibers to settle freely during filtration, thus preventing fiber agglomeration caused by floating UHMWPE fibers. The polyethylene oxide molecular chains can hydrogen bond with the polyethylene oxide segments of the emulsifier (Tween series) through water molecules to form PEO-water-emulsifier polyethylene oxide segments. The water molecules hydrogen bond with the PEO and emulsifier polyethylene oxide segments, respectively, to form longer macromolecular segments. The hydrophilic ends contact water, while the hydrophobic ends bond to the fibers through van der Waals forces, thereby increasing the steric hindrance effect and promoting uniform dispersion of the UHMWPE fibers.

[0010] Preferably, the ratio of the polyethylene oxide, emulsifier, water and alcohol is (0.2-6.7 g): (0.6-15 mL): 100 mL: 100 mL.

[0011] Under the above-mentioned proportion conditions, the concentration of polyethylene oxide is moderate, and the synergistic effect of polyethylene oxide and emulsifier can be maximized, so that the dispersion effect of ultra-high molecular weight polyethylene fibers is better, and the uniformity of subsequent fiber paper is improved; the ratio of water to alcohol is set to 1:1, which can ensure that the ultra-high molecular weight polyethylene fibers can achieve natural sedimentation effect under the action of gravity during filtration, and minimize the amount of alcohol used, saving costs. In addition, a sufficient proportion of water can also ensure the dissolution rate of polyethylene oxide. If only alcohol is used as a solvent, since polyvinyl alcohol is insoluble in alcohol, it is impossible to prepare a dispersion liquid. Moreover, if the fibers are added to a single alcohol, they will only be suspended when stirred, and will all sink to the bottom a few seconds after stopping, and a mixed slurry cannot be made.

[0012] Preferably, the emulsifier is one or more of Tween 20, Tween 40, Tween 60 and Tween 80.

[0013] As emulsifiers, Tween series products have better compatibility with non-polar ultra-high molecular weight polyethylene than other surfactants, and have stronger binding ability with the surface of ultra-high molecular weight polyethylene fibers.

[0014] Optionally, the alcohol is methanol, ethanol or tert-butanol.

[0015] Preferably, the molecular weight of the polyethylene oxide is 1 million to 7 million.

[0016] Appropriate polyethylene oxide molecular weight can improve dissolution efficiency and increase dispersion viscosity, and achieve appropriate steric hindrance effect to promote the dispersion of ultra-high molecular weight polyethylene fibers.

[0017] Technical solution 2 of the present invention: The method for preparing the above-mentioned ultra-high molecular weight polyethylene fiber dispersion comprises the following steps:

[0018] dissolving polyethylene oxide in water to obtain a polyethylene oxide aqueous solution;

[0019] Alcohol and an emulsifier are added to the polyoxyethylene aqueous solution to obtain the ultra-high molecular weight polyethylene fiber dispersion.

[0020] The invention first dissolves polyethylene oxide in water and then adds alcohol and an emulsifier, which can promote better uniform mixing of polyethylene oxide and the emulsifier. The prepared ultra-high molecular weight polyethylene fiber dispersion has stable performance and better dispersion effect.

[0021] The third technical solution of the present invention: use of the above-mentioned ultra-high molecular weight polyethylene fiber dispersion in dispersing ultra-high molecular weight polyethylene fibers or preparing ultra-high molecular weight polyethylene fiber paper.

[0022] The ultra-high molecular weight polyethylene fiber dispersion provided by the present invention can well disperse the ultra-high molecular weight polyethylene fibers, so that the fibers in the prepared ultra-high molecular weight polyethylene fiber paper are more evenly dispersed and have better performance.

[0023] Technical solution 4 of the present invention: A method for preparing ultra-high molecular weight polyethylene fiber paper, comprising the following steps:

[0024] Using the ultra-high molecular weight polyethylene fiber dispersion to disperse ultra-high molecular weight polyethylene short fibers to obtain a mixed slurry;

[0025] filtering the mixed slurry, wet-pressing and dehydrating the mixture, and drying the mixture to obtain a fiber paper skeleton;

[0026] Dipping the fiber paper skeleton into an adhesive solution for gluing, and drying to obtain a fiber paper precursor;

[0027] The fiber paper precursor is subjected to hot pressing to obtain the ultra-high molecular weight polyethylene fiber paper.

[0028] Optionally, the dispersion is carried out under stirring conditions with a stirring speed of 2000 r / min.

[0029] Preferably, the usage ratio of the ultra-high molecular weight polyethylene fiber dispersion and the ultra-high molecular weight polyethylene short fibers is (160-240 mL): 0.2 g.

[0030] The appropriate amount of ultra-high molecular weight polyethylene fiber dispersion can ensure the dispersion effect of ultra-high molecular weight polyethylene short fibers and the sedimentation effect in the subsequent sedimentation process, making the fiber dispersion in the prepared fiber paper skeleton more uniform and avoiding fiber agglomeration to the greatest extent.

[0031] Preferably, the pressure of the wet pressing dehydration is 2000-6000g.

[0032] Appropriate wet pressing and dehydration pressure can ensure that the fiber paper skeleton has a certain strength and stability after drying, and prevent the skeleton from collapsing during the subsequent dipping process.

[0033] Preferably, the immersion temperature is 10-30° C. and the immersion time is 3-35 seconds.

[0034] Preferably, the usage ratio of the fiber paper skeleton and the adhesive solution is 1g:(10-500mL).

[0035] The above-mentioned impregnation temperature, time and dosage can ensure that the fiber paper skeleton and the adhesive solution are in full contact, so that the adhesive solution is maintained at the optimal fluidity, and the adhesive solution will not evaporate too quickly and the fiber will not be softened and damaged due to high temperature. In addition, it can also prevent bubbles from being retained inside the skeleton, which will cause unstable mechanical properties of the fiber paper after forming.

[0036] Preferably, the adhesive solution is a polyvinyl alcohol aqueous solution with a mass concentration of 7-10%.

[0037] Preferably, the hot pressing parameters are: 60-120° C., 5-20 MPa, 8-15 min.

[0038] The long-term operating temperature of UHMWPE fiber is 80-100°C, and its melting point is approximately 134°C. When the processing temperature is higher than 134°C, the UHMWPE fiber will soften, and after high-pressure pressing, the fiber cross-sectional morphology will change from a round shape to a flat shape, which will seriously affect the mechanical properties of the fiber itself and thus affect the properties of the paper material. In addition, considering the chemical inertness of the UHMWPE fiber itself and the processing temperature of the binder, the present invention selects polyvinyl alcohol with a low melting temperature and high compatibility with UHMWPE as the binder resin. This resin not only can produce sufficient bonding effect on the UHMWPE fiber to improve the bonding force between the fibers, but also reduces the hot pressing temperature, avoiding UHMWPE fiber deformation caused by excessively high processing temperature and damage to the mechanical properties of the fiber and fiber paper. The paper strength can be enhanced under conditions not exceeding the tolerance temperature of UHMWPE.

[0039] Preferably, the preparation method further comprises the step of collecting the filtered dispersion and reusing it.

[0040] During the dispersion step, the dispersion does not contain any chemical components other than those having a dispersing effect. Therefore, no other components such as adhesive fibers, reinforcing agents, adhesives, etc. will remain in the filtered liquid, ensuring the purity of the dispersion and facilitating its reuse.

[0041] Preferably, the filtration is natural filtration.

[0042] Technical solution five of the present invention: ultra-high molecular weight polyethylene fiber paper obtained by the above preparation method.

[0043] Technical solution six of the present invention: A method for reducing the hot pressing temperature in the preparation process of ultra-high molecular weight polyethylene fiber paper, using the above-mentioned ultra-high molecular weight polyethylene fiber dispersion to disperse ultra-high molecular weight polyethylene fibers, and using polyvinyl alcohol as the binding resin of the ultra-high molecular weight polyethylene fibers.

[0044] The present invention uses the above-mentioned ultra-high molecular weight polyethylene fiber dispersion to disperse ultra-high molecular weight polyethylene fibers, and uses polyvinyl alcohol as the bonding resin of the ultra-high molecular weight polyethylene fibers. After the skeleton is dried, molecular groups in the dispersant will remain on the fiber surface, which can improve the compatibility and bonding strength of the ultra-high molecular weight polyethylene fibers and polyvinyl alcohol, thereby increasing the amount of glue applied. Subsequently, the thermoplastic polyvinyl alcohol entering the skeleton will be subjected to high temperature and fiber extrusion to produce flow during the hot pressing process, and will be redistributed inside the skeleton and filled between the fibers to achieve efficient bonding. Paper forming can be achieved without the need for fiber melting to produce bonding, and ultimately the hot pressing temperature can be reduced to below 120°C, thereby reducing energy consumption while avoiding the impact of softening and deformation of the UHMWPE fibers on performance.

[0045] The present invention discloses the following technical effects:

[0046] The present invention uses polyethylene oxide as a dispersant, combined with an emulsifier and a mixed solution of water and alcohol to prepare an ultra-high molecular weight polyethylene fiber dispersion. Water and alcohol are used to reduce the buoyancy of the dispersion on the fibers, and polyethylene oxide and the emulsifier are used to reduce the interaction force on the fiber surface, thereby promoting uniform dispersion of the UHMWPE fibers. Using the ultra-high molecular weight polyethylene fiber dispersion of the present invention to disperse ultra-high molecular weight polyethylene fibers can ensure the dispersion effect while omitting the hydrophilic penetration treatment step before fiber dispersion. At the same time, the use of ingredients such as reinforcing agents and defoaming agents during the dispersion process is avoided. The dispersion obtained by filtering after dispersing the fibers can be recycled, thereby avoiding the generation of waste liquid to the greatest extent. The method of the present invention can omit the fiber pretreatment step in the UHMWPE fiber paper manufacturing process, prevent the waste of pretreatment liquid and the generation of highly corrosive waste liquid, maintain green environmental protection, and greatly reduce papermaking costs.

[0047] The present invention adopts polyvinyl alcohol with a melting temperature lower than 100° C. and high bonding properties with UHMWPE as a bonding resin, and prepares UHMWPE fiber paper with well-preserved fiber morphology integrity at a safe hot pressing temperature.

[0048] In the preparation method of the ultra-high molecular weight polyethylene fiber paper of the present invention, ultra-high molecular weight polyethylene fibers are dispersed using a dispersion prepared from polyethylene oxide, an emulsifier, water and alcohol, and polyvinyl alcohol is used as a bonding resin. The fiber surfaces in the skeleton will contain molecular groups of polyethylene oxide and the emulsifier, which can improve the compatibility and bonding strength between the ultra-high molecular weight polyethylene fibers and the polyvinyl alcohol, thereby increasing the amount of glue applied. Subsequently, the thermoplastic polyvinyl alcohol retained inside the skeleton will be subjected to high temperature and fiber extrusion to produce flow during the hot pressing process, and will be redistributed inside the skeleton and filled between the fibers to achieve efficient bonding. There is no need for the fibers to melt to generate bonding strength, so the hot pressing temperature can be reduced to below 120°C, reducing energy consumption while avoiding the impact of softening and deformation of the UHMWPE fibers on performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0050] Figure 1 This is the microscopic morphology of fiber paper after hot pressing under conditions above the softening temperature of UHMWPE (150°C) in the existing technology;

[0051] Figure 2 DSC curve of UHMWPE short fiber used in the embodiment of the present invention;

[0052] Figure 3 This is a microscopic morphology of the fiber paper after hot pressing in Example 1 of the present invention;

[0053] Figure 4 This is a photo of the fiber paper prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0054] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0055] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0056] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0057] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0058] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0059] The raw materials involved in the following examples of the present invention are all commercially available products. Their sources do not affect the technical effects of the present invention. The room temperature described in the examples of the present invention is 23±2°C.

[0060] The polyethylene oxide used in the following examples of the present invention has a molecular weight of 4,000,000 and is produced by Sumitomo Corporation of Japan.

[0061] UHMWPE staple fiber: specification model 1200D, T80, produced by Changshu Xiupo Fiber Co., Ltd. Figure 2 This is the DSC curve of the UHMWPE short fiber used in the embodiment of the present invention. Figure 2 It shows that the melting temperature of UHMWPE fiber is greater than 134℃.

[0062] Polyvinyl alcohol: molecular weight: 70,000-85,000, commercially available.

[0063] The natural filtration described in the embodiment of the present invention is specifically to pour the dispersed fiber dispersion slurry into the filtration device at one time, let it stand, and filter it naturally under the action of gravity. The fibers gradually settle to form a wet fiber skeleton, and the dispersion liquid is filtered out and recovered by the collector.

[0064] The wet pressing dehydration in the embodiment of the present invention specifically involves applying pressure to the wet fiber skeleton formed by filtration to squeeze out the residual dispersion in the skeleton and densify the loose skeleton structure.

[0065] Example 1

[0066] A method for preparing UHMWPE fiber paper, the specific steps are as follows:

[0067] (1) Fiber dispersion: Weigh 0.5 g of polyethylene oxide and 100 mL of deionized water, add polyethylene oxide to the water at room temperature, and stir magnetically until completely dissolved. Then, add 100 mL of anhydrous ethanol and 5 mL of Tween 80 to the above solution and mix evenly under magnetic stirring. Finally, weigh 0.2 g of UHMWPE short fibers, add the UHMWPE short fibers to the mixture, and disperse under magnetic stirring for 30 min. The magnetic stirring speed is 2000 r / min.

[0068] (2) Skeleton forming: The mixed slurry obtained in the above step (1) is naturally filtered, wet pressed for dehydration and dried at room temperature to obtain a fiber paper skeleton, with a wet pressing pressure of 2000g.

[0069] (3) Dipping and molding: Add polyvinyl alcohol to deionized water at 80°C and mechanically stir for 30 minutes. The polyvinyl alcohol concentration is 10 wt%. After cooling to room temperature, 0.2 g of the fiber paper skeleton obtained in step (2) is immersed in 50 mL of the above solution for gluing. Then, the fiber paper precursor is naturally dried at room temperature to obtain a fiber paper precursor (gluing amount 55%).

[0070] (4) Hot pressing: The fiber paper precursor obtained in step (3) was hot pressed at 60° C. and 9 MPa for 10 min to obtain UHMWPE fiber paper.

[0071] Figure 3 This is a microscopic morphology of the fiber paper after hot pressing in Example 1 of the present invention; Figure 3 It shows that the UHMWPE fibers in the fiber paper prepared in Example 1 still maintain their original fiber morphology and are not softened or deformed, thereby minimizing the loss of UHMWPE fiber body strength during the hot pressing process.

[0072] Figure 4 This is a photo of the fiber paper prepared in Example 1 of the present invention.

[0073] Example 2

[0074] The same as Example 1, except that in step (4), hot pressing treatment is performed at 60° C. and 12 MPa for 10 min to obtain UHMWPE fiber paper.

[0075] Example 3

[0076] The same as Example 1, except that in step (4), hot pressing treatment is performed at 60° C. and 15 MPa for 10 minutes to obtain UHMWPE fiber paper.

[0077] Example 4

[0078] The same as Example 1, except that in step (4), hot pressing treatment is performed at 90° C. and 12 MPa for 10 min to obtain UHMWPE fiber paper.

[0079] Example 5

[0080] The same as Example 1, except that in step (4), hot pressing treatment is performed at 100° C. and 12 MPa for 10 minutes to obtain UHMWPE fiber paper.

[0081] Example 6

[0082] The same as Example 1, except that in step (4), hot pressing treatment is performed at 110° C. and 12 MPa for 10 min to obtain UHMWPE fiber paper.

[0083] The experiments verified that the UHMWPE fiber papers prepared in Examples 2-6 still maintained their original fiber morphology and were not softened or deformed.

[0084] Example 7

[0085] (1) Fiber dispersion: Same as Example 1.

[0086] (2) Skeleton forming: same as in Example 1.

[0087] (3) The dispersion filtered in step (2) is collected and reused 10 times, and new UHMWPE fibers are dispersed according to the same steps as steps (1) and (2) to prepare a fiber paper skeleton. A small amount of dispersion needs to be replenished during the reuse of the dispersion after collection. However, since the polyethylene oxide and emulsifier have been dissolved or evenly dispersed, the content or concentration of the two in the dispersion does not change with the number of uses. Only a part of them will remain in the skeleton after wet pressing and dehydration.

[0088] (4) Dipping and molding: Add polyvinyl alcohol to deionized water at 80°C and mechanically stir for 30 minutes. The polyvinyl alcohol concentration is 10 wt%. After cooling to room temperature, 0.2 g of the fiber paper skeleton obtained in step (3) is immersed in 50 mL of the above solution for gluing. Then, the mixture is naturally dried at room temperature to obtain a fiber paper precursor.

[0089] (5) Hot pressing: The fiber paper precursor obtained in step (4) was hot pressed at 60° C. and 9 MPa for 10 min to obtain UHMWPE fiber paper.

[0090] Performance verification test 1

[0091] The performance of the UHMWPE fiber paper prepared in Examples 1-7 was verified:

[0092] The verification method is as follows:

[0093] Performance Verification: Paper dimensions were measured using a vernier caliper, tensile strength was measured using an electronic universal testing machine, and the fiber paper mass was weighed using an electronic balance. Tensile strength, thickness, density, and adhesive content were then calculated. These test methods are routine techniques for those skilled in the art and will not be detailed here.

[0094] The verification results are shown in Table 1.

[0095] Table 1

[0096]

[0097] Example 8

[0098] Same as Example 1, except that ethanol is replaced by methanol.

[0099] Example 9

[0100] Same as Example 1, except that ethanol is replaced by tert-butanol.

[0101] Comparative Example 1

[0102] The same as Example 1, except that the adhesive solution is adjusted to a polyvinyl alcohol aqueous solution with a mass concentration of 0.2%.

[0103] Comparative Example 2

[0104] The same as Example 1, except that the adhesive solution is adjusted to a polyvinyl alcohol aqueous solution with a mass concentration of 15%.

[0105] Performance verification was conducted on the examples and comparative examples using the method of Performance Verification Test 1. The results showed that even after replacing the alcohol solution in Examples 8 and 9, uniform fiber dispersion and paper uniformity were still achieved, with virtually no change in the properties of the resulting fiber paper. However, in Comparative Example 1, the reduced concentration of polyvinyl alcohol in the adhesive solution resulted in a severe shortage of adhesive, weakening the bond strength between fibers and ultimately reducing the mechanical properties of the paper. In Comparative Example 2, the excessive 15% polyvinyl alcohol concentration led to a significant decrease in the fiber ratio, a stiffer material, and reduced paper flexibility.

[0106] Comparative Example 3

[0107] The same as Example 1, except that the hot pressing parameters are: 30° C., 12 MPa, 10 min.

[0108] The performance of the prepared product was verified using the method of performance verification test 1. The results showed that after the hot pressing temperature dropped to room temperature, the thickness of the fiber paper increased and the mechanical properties were severely reduced. This is because when the hot pressing temperature does not reach the melting temperature of polyvinyl alcohol, the redistribution and bonding effects of polyvinyl alcohol during the hot pressing process cannot be achieved, and forced hot pressing at this time will destroy the already solidified polyvinyl alcohol, causing defects or direct destruction; in addition, under 30°C conditions, the structure of the already shaped fiber paper cannot be changed, causing its structure to remain fluffy and unable to densify, so its thickness also increases significantly.

[0109] Comparative Example 4

[0110] The same as Example 1, the only difference is that in step (1), anhydrous ethanol is replaced by an equal amount of deionized water, that is, only water is used as the solvent of the dispersion.

[0111] The results show that the dispersion effect is weakened compared with Example 1, and the fibers are prone to floating during the filtration process. The reason is that when water is used alone as the solvent of the dispersion liquid, the density of the dispersion liquid is greater than the density of the fiber, resulting in increased buoyancy. In addition, ethanol has good compatibility with fibers, and the lack of ethanol will also have a certain negative effect on the fiber dispersibility, which may easily cause the fibers to fail to settle during the filtration and sedimentation process, ultimately affecting the uniformity of the paper.

[0112] The performance of the prepared UHMWPE fiber paper was verified using the method of performance verification test 1. The results showed that the parameters such as density, thickness, and glue amount of the fiber paper did not change much, but due to the low uniformity, the strength would decrease.

[0113] Comparative Example 5

[0114] The same as Example 1, except that in step (1), Tween 80 is omitted, that is, only polyethylene oxide is used as the solute of the dispersion.

[0115] The results showed that the dispersion effect was poor and there was fiber agglomeration. This was due to the lack of synergistic effect between Tween 80 and polyethylene oxide, which reduced the steric hindrance effect and led to insufficient fiber dispersion.

[0116] The performance of the prepared UHMWPE fiber paper was verified using the method of performance verification test 1. The results showed that the parameters such as density, thickness, and glue amount of the fiber paper did not change much, but due to the low uniformity, the strength would decrease.

[0117] Comparative Example 6

[0118] The same as Example 1, except that in step (1), the amount of polyethylene oxide is adjusted to 0.05 g and the amount of Tween 80 is adjusted to 5 mL.

[0119] The results showed that the dispersion effect was poor and fiber agglomeration occurred. This was due to the insufficient synergistic effect between Tween 80 and polyethylene oxide and the insufficient steric hindrance effect, which led to a decrease in the dispersion liquid's ability to disperse fibers.

[0120] The performance of the prepared UHMWPE fiber paper was verified using the method of performance verification test 1. The results showed that the parameters such as density, thickness, and glue amount of the fiber paper did not change much, but due to the low uniformity, the strength would decrease.

[0121] Comparative Examples 5-6 show that the emulsifier and polyethylene oxide can produce a synergistic effect. By hydrogen bonding with water molecules, a macromolecular chain with a stronger steric hindrance effect is formed, one end of which is anchored to the fiber surface through van der Waals force, and the other end is combined with the solvent through hydrophilic effect, ultimately forming a stable UHMWPE fiber dispersion system. The dispersion effect can be guaranteed within the dosage range specified by the present invention, thereby improving the performance of fiber paper.

[0122] Comparative Example 7

[0123] Same as Example 1, except that polyethylene oxide with a molecular weight of 100,000 is used.

[0124] The results showed that the dispersion effect was better than that in Example 1, but there was a phenomenon of fiber agglomeration. This was because the molecular chain length of the low-molecular-weight polyethylene oxide was relatively short, and the steric hindrance effect produced by the low-molecular-weight polyethylene oxide and Tween 80 was reduced, thus reducing the dispersibility.

[0125] The performance of the prepared UHMWPE fiber paper was verified using the method of performance verification test 1. The results showed that the paper parameters such as density, thickness, and glue amount did not change much, but due to the low uniformity, the strength would decrease.

[0126] This shows that the molecular weight of polyethylene oxide will affect the length of the molecular chain segment produced after it combines with Tween 80. The smaller the molecular weight, the shorter the length of the molecular chain combined with the fiber surface, and the worse the steric hindrance effect, which in turn affects the dispersion effect and fiber paper performance.

[0127] Comparative Example 8

[0128] Same as Example 1, except that the polyethylene oxide in step (1) is replaced by an equal amount of sodium carboxymethyl cellulose.

[0129] The results showed that the dispersion effect was poor and there were small fiber agglomerations. This was because sodium carboxymethyl cellulose carried a large number of anionic charges and polar groups, had poor compatibility with UHMWPE fibers, and could not be effectively adsorbed on the non-polar UHMWPE surface.

[0130] The performance of the prepared UHMWPE fiber paper was verified using the method of performance verification test 1. The results showed that the paper parameters such as density, thickness, and glue amount did not change much, but due to the low uniformity, the strength would decrease.

[0131] Comparative Example 9

[0132] The same as Example 1, except that the polyvinyl alcohol in step (3) is replaced by polyurethane.

[0133] The performance of the prepared UHMWPE fiber paper was verified using the method of performance verification test 1. The results showed that the fiber paper was thicker and stronger than the paper using polyvinyl alcohol resin. The reason was that the hot pressing temperature was too low, resulting in the polyurethane not entering the softened or melted state to produce a bonding effect, thus affecting the strength of the paper.

[0134] Comparative Examples 8-9 show that the use of polyethylene oxide as a dispersant in the dispersion can produce a synergistic effect with the subsequent bonding resin (polyvinyl alcohol). After dispersion with polyethylene oxide, certain polar groups remain on the fiber surface, which can increase the compatibility with water-soluble polyvinyl alcohol, improve the retention rate and bonding force of polyvinyl alcohol, and thus improve the bonding strength.

[0135] Comparative Example 10

[0136] The same as Comparative Example 9, except that the hot pressing temperature was adjusted to 130°C.

[0137] The performance of the prepared UHMWPE fiber paper was verified using the method of Performance Verification Test 1. The results showed that the fiber paper thickness decreased, and the tensile strength increased compared to Comparative Example 9, but still lower than the optimal polyvinyl alcohol solution. This is because the increased hot pressing temperature allows the polyurethane to reach a molten state, enabling redistribution and bonding, which promotes strength improvement. However, 130°C is close to the fiber softening point, which easily causes fiber deformation and destroys the original crystal and molecular structure of the UHMWPE fiber, resulting in a loss of fiber strength and an inability to provide sufficient mechanical properties. In addition, due to its insufficient polarity, poor wettability, and over-reliance on a highly active surface, polyurethane has lower bonding strength than polyvinyl alcohol under the same conditions.

[0138] The specific experimental results of the above embodiments and comparative examples are shown in Table 2.

[0139] Table 2

[0140]

[0141] In combination with the above embodiments and comparative examples, the present invention provides an ultra-high molecular weight polyethylene fiber dispersion, and a method for preparing ultra-high molecular weight polyethylene fiber paper. The ultra-high molecular weight polyethylene fiber dispersion provided by the present invention can disperse ultra-high molecular weight polyethylene fibers while avoiding the generation of a large amount of corrosive liquid or waste liquid in the UHMWPE fiber paper manufacturing process. The method for preparing ultra-high molecular weight polyethylene fiber paper provided by the present invention can improve the bonding strength between UHMWPE fibers, and prevent the fibers from softening and deforming due to excessively high processing temperatures. At the same time, the ultra-high molecular weight polyethylene fiber dispersion provided by the present invention and the adhesive solution used in the preparation process of ultra-high molecular weight polyethylene fiber paper have a synergistic effect. The dispersant can chemically modify the fiber surface while dispersing the fibers, provide polar groups, and thereby improve the retention rate and bonding force of the adhesive solution. The two are used in combination, so that the prepared fiber paper has better strength and tensile properties, thereby being able to meet the application of UHMWPE fiber paper as a thin paper-based material in the fields of electronics, electrical engineering, energy, aerospace, etc.

[0142] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. An ultra-high molecular weight polyethylene fiber dispersion, characterized in that: The solute of the ultra-high molecular weight polyethylene fiber dispersion includes polyethylene oxide and an emulsifier, and the solvent is a mixed solution of water and alcohol.

2. The ultra-high molecular weight polyethylene fiber dispersion according to claim 1, characterized in that: The ratio of the polyethylene oxide, emulsifier, water and alcohol is (0.2-6.7) g: (0.6-15) mL: 100 mL: 100 mL; And / or, the emulsifier is one or more of Tween 20, Tween 40, Tween 60 and Tween 80; and / or, the alcohol is methanol, ethanol or tert-butanol; And / or, the molecular weight of the polyethylene oxide is 1 million to 7 million.

3. A method for preparing an ultra-high molecular weight polyethylene fiber dispersion according to claim 1 or 2, characterized in that: The following steps are involved: dissolving polyethylene oxide in water to obtain a polyethylene oxide aqueous solution; Alcohol and an emulsifier are added to the polyoxyethylene aqueous solution to obtain the ultra-high molecular weight polyethylene fiber dispersion.

4. Use of the ultra-high molecular weight polyethylene fiber dispersion according to claim 1 or 2 in dispersing ultra-high molecular weight polyethylene fibers or preparing ultra-high molecular weight polyethylene fiber paper.

5. A method for preparing ultra-high molecular weight polyethylene fiber paper, characterized in that: The following steps are involved: Dispersing ultra-high molecular weight polyethylene short fibers using the ultra-high molecular weight polyethylene fiber dispersion according to claim 1 or 2 to obtain a mixed slurry; filtering the mixed slurry, wet-pressing and dehydrating the mixture, and drying the mixture to obtain a fiber paper skeleton; Dipping the fiber paper skeleton into an adhesive solution for gluing, and drying to obtain a fiber paper precursor; The fiber paper precursor is subjected to hot pressing to obtain the ultra-high molecular weight polyethylene fiber paper.

6. The preparation method according to claim 5, characterized in that The usage ratio of the ultra-high molecular weight polyethylene fiber dispersion and the ultra-high molecular weight polyethylene short fiber is (160-240 mL): 0.2 g; And / or, the pressure of the wet pressing dehydration is 2000-6000g; and / or, the immersion temperature is 10-30° C. and the immersion time is 3-35 s; And / or, the usage ratio of the fiber paper skeleton and the adhesive solution is 1g:(10-500mL).

7. The preparation method according to claim 5, characterized in that The adhesive solution is a polyvinyl alcohol aqueous solution with a mass concentration of 7-10%; And / or, the parameters of the hot pressing treatment are: 60-120° C., 5-20 MPa, 8-15 min.

8. The preparation method according to claim 5, characterized in that The method also includes the steps of collecting the filtered dispersion and reusing it.

9. An ultra-high molecular weight polyethylene fiber paper obtained according to the preparation method according to any one of claims 5 to 8.

10. A method for reducing the hot pressing temperature in the process of preparing ultra-high molecular weight polyethylene fiber paper, characterized in that: Ultra-high molecular weight polyethylene short fibers are dispersed using the ultra-high molecular weight polyethylene fiber dispersion according to any one of claims 1 to 2, and polyvinyl alcohol is used as a binder resin for the ultra-high molecular weight polyethylene fibers.

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