Non-crimped continuous filament bundle phenolic fiber and its preparation method and application

Abstract

The application provides a process equipment for non-crimped continuous filament bundle phenolic aldehyde fibers, comprising a spinning unit, a guide unit and a collecting unit, the spinning unit comprises a double screw mechanism, a gear pump and a spinneret, the gear pump is arranged between the double screw mechanism and the spinneret, the guide unit comprises guide rollers and oil grooves, the number of the guide rollers is multiple, the oil grooves are arranged between adjacent two guide rollers, the collecting unit comprises tension rollers and a collecting roller, the tension rollers are arranged between the guide rollers and the collecting roller. The double screw mechanism in the process equipment can improve the mixing effect and stability of raw material melting, the oil grooves can improve the flexibility of the phenolic aldehyde resin raw filament bundle, the gear pump and the tension rollers can guarantee the continuity and uniformity of the phenolic aldehyde resin raw filament bundle, and the combination of the tension rollers and the collecting roller can avoid the fluctuation and instability of the collecting gun in the related art. The application further discloses a non-crimped continuous filament bundle phenolic aldehyde fiber and a preparation method and application thereof.

Description

Technical Field

[0001] This invention belongs to the field of phenolic fiber technology, and particularly relates to a non-crimped continuous filament bundle phenolic fiber, its preparation method and application. Background Technology

[0002] Currently, phenolic fiber is a three-dimensional cross-linked organic fiber made from phenolic resin. It has broad application prospects in fields such as flame retardancy, high-temperature thermal protection, thermal insulation, sound insulation, chemical protection, and high-end flame-retardant decorative materials for aircraft and submarines. Internationally, only Kynol Corporation of Japan has achieved industrial-scale production and sales of phenolic fiber. In China, phenolic fiber research is still in the laboratory research stage, primarily focusing on short fibers with fixed filament lengths. Compared to long-filament bundles, short fibers have significant shortcomings in textile manufacturing such as spinning and weaving.

[0003] Regarding reports on phenolic fiber bundles, patents CN115386975A and CN115341298A employ a two-component raw material melt spinning method, utilizing the difference in thermal properties between the two components to obtain crimped phenolic filaments. However, the crimped filament bundles prepared by this method impose certain limitations on the fiber's performance and applications compared to non-crimped long fibers. Furthermore, the excessive content of low-heat-resistant organic polymers mixed in during the preparation process significantly negatively impacts the heat resistance and flame retardancy of phenolic fibers. Secondly, the airflow filament collector used suffers from issues with filament suction stability, which significantly affects fiber uniformity. Moreover, the lack of an oiling unit in the preparation system leads to problems such as fiber bundle dispersion and excessive fuzz during fiber bundling, making it impossible to obtain high-quality phenolic fiber bundles.

[0004] While wet spinning can theoretically produce long-tow phenolic fibers, current research indicates that due to the lack of breakthroughs in tow solidification technology, the resulting fibers exhibit significant defects in shape and performance. The fibers are not regularly round or elliptical, and internal defects are also present, leaving their performance far from practical application. Furthermore, the wet spinning process requires the addition of large amounts of organic spinning auxiliaries, which negatively impacts the fiber's heat resistance and flame retardancy.

[0005] To solve the above-mentioned technical problems, this invention designs a non-curled continuous filament bundle phenolic fiber, its preparation method, and its application. Summary of the Invention

[0006] This invention provides a non-curled continuous filament bundle phenolic fiber, its process equipment, preparation method, and application. The filament bundle phenolic fiber prepared by this method has a circular cross-section, few internal defects, a dense structure, outstanding heat resistance and flame retardancy, and is easy to mass-produce industrially.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a process equipment for producing non-curled continuous filament bundles of phenolic fibers, comprising a spinneret unit, a guide unit, and a take-up unit. The spinneret unit includes a twin-screw mechanism, a gear pump, and a spinneret plate. The gear pump is located between the twin-screw mechanism and the spinneret plate. The guide unit includes guide rollers and an oiling tank. The number of guide rollers is multiple. The oiling tank is located between two adjacent guide rollers. The take-up unit includes a tension roller and a take-up roller. The tension roller is located between the guide rollers and the take-up rollers.

[0008] Based on the above technical solution, the temperature of the twin-screw mechanism is 120-220℃.

[0009] Based on the above technical solution, the gear pump provides a pressure of 0.5-10 MPa.

[0010] Based on the above technical solution, the spinneret has 250, 500, 750 or 1000 spinneret holes.

[0011] Based on the above technical solution, the tension of the tension roller is 0.02-0.2N.

[0012] Secondly, this application provides a method for preparing non-crimped continuous filament phenolic fibers, using a process device for non-crimped continuous filament phenolic fibers as described in any of the above embodiments, comprising the following steps: mixing phenolic monomers, aldehyde monomers, modifiers, and catalysts, heating and reacting to obtain modified spinnable thermoplastic phenolic resin; adding the modified spinnable thermoplastic phenolic resin to a twin-screw extruder for melting, removing free phenols and low-polymerization-degree small molecules, conveying it to a gear pump, pressurizing the melt with the gear pump, and extruding it through a spinneret to obtain raw filaments; drawing and bundling the raw filaments through a guide roller and an oiling tank, applying a constant tension through a tension roller, and winding it through a take-up roller to obtain a filament phenolic resin raw filament bundle; placing the raw filament bundle and the take-up roller in a curing liquid for curing and crosslinking, acetylifying the phenolic hydroxyl groups in an acetic acid and acetic anhydride solution, washing, drying, and finally spinning to obtain non-crimped continuous filament phenolic fibers.

[0013] Based on the above technical solution, the phenolic monomer is one or more of phenol, bisphenol A, benzophenol, hydroquinone, resorcinol, diphenyl ether, vinylphenol, and xylenol; the aldehyde monomer is one or more of formaldehyde and oligooxyformaldehyde; the modifier is one or more of epichlorohydrin, nonylphenol, epoxy cashew phenol, triphenyl phosphate, and xylene; and the catalyst is oxalic acid or hydrochloric acid.

[0014] Based on the above technical solution, the content of the free phenol is less than or equal to 0.5%.

[0015] Thirdly, this application provides a non-crimped continuous filament bundle phenolic fiber, which is prepared according to the preparation method of the non-crimped continuous filament bundle phenolic fiber described in any of the above embodiments.

[0016] Fourthly, this application provides a non-curled continuous filament bundle phenolic fiber obtained by the preparation method according to any one of the above embodiments, for use in flame-retardant decorative materials.

[0017] Compared with related technologies, the beneficial effects of the present invention are as follows: This invention uses a spinneret mechanism to spin raw filaments. A twin-screw mechanism melts the raw material to obtain a melt, which is then transported to a gear pump. The gear pump provides pressure, preventing pressure instability in the twin-screw mechanism. This pressure provides a continuous and stable pressure to the spinneret, ensuring the continuity and uniformity of spinning. The guide roller collects and draws the raw filament bundle. The oil tank helps to bundle and soften the raw filament bundle. The tension roller provides a constant drawing force for spinning. Under the constant extrusion pressure of the gear pump and the constant drawing force of the tension roller, the continuity and uniformity of the raw filament bundle are ensured. The take-up roller collects the phenolic resin raw filament bundle and winds it regularly. The combination of the tension roller and the take-up roller avoids the fluctuations and instabilities of take-up using a take-up gun in related technologies. Furthermore, the take-up roller is made of corrosion-resistant materials such as PTFE to ensure its integrity in acidic curing solutions. Finally, we can obtain non-crimped continuous filament bundle phenolic fibers with circular cross-sections, fewer internal defects, dense structure, and higher strength and elongation at break. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other embodiments can be derived from the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the process equipment for non-curled continuous filament bundle phenolic fiber provided by the present invention; Figure 2 This is a scanning electron microscope image of the cross-section of a non-curled continuous filament bundle phenolic fiber prepared by the method provided in this invention.

[0020] In the diagram: 1. Twin screw mechanism; 2. Gear pump; 3. Spinneret; 4. Guide roller; 5. Oil tank; 6. Tension roller; 7. Take-up roller. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and examples: Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents, materials, instruments, etc. used in the following examples are all commercially available.

[0025] Combination Figure 1 As shown, the present invention provides a process equipment for producing non-crimped continuous filament bundles of phenolic fibers, including a spinneret unit, a guide unit, and a take-up unit. The spinneret unit includes a twin-screw mechanism 1, a gear pump 2, and a spinneret plate 3. The gear pump 2 is located between the twin-screw mechanism 1 and the spinneret plate 3. The guide unit includes guide rollers 4 and an oil tank 5. There are multiple guide rollers 4, and the oil tank 5 is located between two adjacent guide rollers 4. The take-up unit includes a tension roller 6 and a take-up roller 7. The tension roller 6 is located between the guide rollers 4 and the take-up roller 7.

[0026] This invention uses a spinning mechanism to spin raw yarn. A twin-screw mechanism 1 melts the raw material to obtain a melt, which is then transported to a gear pump 2. The gear pump 2 provides pressure, preventing pressure instability in the twin-screw mechanism. The gear pump 2 provides continuous and stable pressure to the spinneret 3, ensuring continuous and uniform spinning. Guide rollers 4 are used for collecting and drawing the raw yarn filament bundles; the number of guide rollers 4 is 3-6. An oiling tank 5 facilitates the bundling and softening of the raw yarn filament bundles; the oiling tank 5 can be located near the second guide roller 4. Between any two guide rollers 4 and the last guide roller 4, the tension roller 6 provides a constant stretching force for spinning. Under the constant extrusion pressure of the gear pump 2 and the constant stretching force of the tension roller 6, the continuity and uniformity of the raw filament bundle are ensured. The take-up roller 7 collects the phenolic resin raw filament bundle and regularly winds it onto the take-up roller 7. The combination of tension roller 6 and take-up roller 7 avoids the fluctuations and instabilities of take-up using a take-up gun in related technologies. In addition, the take-up roller 7 cylinder is made of corrosion-resistant materials such as polytetrafluoroethylene to ensure the integrity of the take-up roller 7 in acidic curing liquid.

[0027] Based on the above technical solution, the temperature of the twin-screw mechanism 1 is 120-220℃.

[0028] Based on the above technical solution, the gear pump 2 provides a pressure of 0.5-10MPa.

[0029] Based on the above technical solution, the number of spinneret holes 3 is 250 holes, 500 holes, 750 holes or 1000 holes.

[0030] Based on the above technical solution, the tension of the tension roller 6 is 0.02-0.2N.

[0031] This invention also provides a method for preparing non-crimped continuous filament phenolic fibers, using the process equipment applied to the non-crimped continuous filament phenolic fibers described in any of the above embodiments, comprising the following steps: Phenolic monomers, aldehyde monomers, modifiers and catalysts are mixed and heated to react, resulting in modified spinnable thermoplastic phenolic resin. Modified spinnable thermoplastic phenolic resin is added to twin-screw mechanism 1 for melting, free phenol and low-polymerization small molecules are removed, and it is conveyed to gear pump 2. After the gear pump 2 pressurizes the melt, it is extruded through spinneret 3 to obtain raw yarn. The raw filaments are drawn and bundled through the guide roller 4 and the oil trough 5, and a constant tension is applied by the tension roller 6. After being wound by the take-up roller 7, a long filament bundle of phenolic resin raw filaments is obtained. The raw filament bundle and take-up roller 7 are placed in a curing solution for curing and cross-linking. After being placed in a solution of acetic acid and acetic anhydride for phenolic hydroxyl acetylation, the bundle is cleaned, dried, and finally filaments are drawn together to obtain non-crimped continuous filament bundles of phenolic fibers.

[0032] This invention uses modified spinnable thermoplastic phenolic resin as raw material because phenolic resin precursor fibers produced by ordinary phenolic resin have extremely poor strength and toughness. Although they can meet the minimum requirements for spinning short fiber filaments, they cannot meet the requirements for drawing, bundling, guiding, winding, and winding of long filament bundles of phenolic resin precursor fibers. This invention employs a co-heated reaction of phenolic monomers and aldehyde monomers with modifiers and catalysts. Through the internal toughening mechanism of alkylation, alkylation, and phenolic hydroxyl etherification of phenolic resin, and using grafting and block polymerization methods, flexible groups or flexible chains are introduced and added to the phenolic resin to achieve reinforcement and toughening of the phenolic resin precursor fibers.

[0033] In this invention, the raw fiber bundle, along with the take-up roller 7, is cured and crosslinked in a curing solution at a high temperature. This ensures that the raw fiber bundle undergoes curing and crosslinking under tension, avoiding the drawback of conventional curing processes where the phenolic resin raw fiber is cured and crosslinked in a relaxed state after being removed from the roller, which affects the mechanical properties of the fiber. The phenolic hydroxyl acetylation described in this invention is because the phenolic hydroxyl groups in phenolic resin are easily oxidized to quinones, thus affecting fiber properties and appearance. Through the phenolic hydroxyl acetylation reaction between the fiber and acetic acid and acetic anhydride solutions, the antioxidant properties and strength of the phenolic fiber are improved. Figure 2 As shown, the cross-section of the long filament phenolic fiber obtained in this application is circular, with few internal defects and a dense structure.

[0034] Specifically, in the step of removing free phenols and low-polymerization-degree small molecules, the degree of polymerization of the low-polymerization-degree small molecules is ≤2.

[0035] The purpose of cleaning and drying is to remove harmful chemical components such as formaldehyde, hydrochloric acid, acetic acid, and acetic anhydride that remain in the curing and cross-linking process.

[0036] The purpose of doubling is to achieve the target specification of the filament bundle through doubling. Through doubling, high-performance phenolic fibers with non-crimped continuous long filament bundles of specifications such as 0.5K, 1K, 3K and 6K can be obtained.

[0037] Based on the above technical solution, the phenolic monomer is one or more of phenol, bisphenol A, benzophenol, hydroquinone, resorcinol, diphenyl ether, vinylphenol, and xylenol; the aldehyde monomer is one or more of formaldehyde and oligooxyformaldehyde; the modifier is one or more of epichlorohydrin, nonylphenol, epoxy cashew phenol, triphenyl phosphate, and xylene; and the catalyst is oxalic acid or hydrochloric acid.

[0038] Preferably, the modifier is epichlorohydrin and nonylphenol. When the modifier is epichlorohydrin, after chemical reaction with phenolic resin, epoxy groups are introduced through phenolic hydroxyl etherification, which increases the proportion of flexible segments in phenolic resin, thereby improving the toughness and spinnability of modified spinnable thermoplastic phenolic resin.

[0039] Based on the above technical solution, the content of free phenol is less than or equal to 0.5%. Since free phenol and phenolic resin are two immiscible phases, the presence of free phenol will cause more fiber breakage and discontinuous spinning. Controlling the content of free phenol to below 0.5% can avoid the impact of excessive free phenol content on the quality and performance of subsequent products.

[0040] The present invention also provides a non-crimped continuous filament bundle phenolic fiber, which is prepared according to the preparation method of the non-crimped continuous filament bundle phenolic fiber according to any one of the above embodiments.

[0041] The present invention also provides a non-crimped continuous filament phenolic fiber obtained by the preparation method according to any one of the above embodiments, for use in flame-retardant decorative materials.

[0042] Example 1 This embodiment provides a method for preparing non-crimped continuous filament bundle phenolic fibers, including the following steps: A modified spinnable thermoplastic phenolic resin with a softening point greater than 110℃ was synthesized by reacting phenol, bisphenol A, formaldehyde, nonylphenol, and oxalic acid (molar ratio 0.5:0.5:0.85:0.05:0.015) at 95℃ for 3.5 hours.

[0043] The modified spinnable thermoplastic phenolic resin is melted and light components are removed through a twin-screw mechanism 1, wherein the free phenol content is removed to 0.35%. The temperature of the twin screw is 170°C. Then it is conveyed to a gear pump 2, which pressurizes it to 1.5MPa. The gear pump 2 conveys it to a spinneret 3 for extrusion. The spinneret 3 has 500 spinneret holes.

[0044] The filaments spun from the spinneret are guided by the first guide roller 4 and the second guide roller 4 and then enter the oiling tank 5 for bundling and softening. After passing through the third guide roller 4, they enter the tension roller 6, which applies a tension of 0.75N. Finally, they are taken in by the PTFE take-up roller 7 to obtain a long filament bundle of phenolic resin filaments regularly wound on the take-up roller 7.

[0045] The raw filament bundle, under the winding tension of take-up roller 7, is placed together with take-up roller 7 into a curing solution of hydrochloric acid (15%) and formaldehyde (18%) for curing and cross-linking. Then, it is placed in a solution of acetic acid and acetic anhydride (molar ratio of 1:1) and subjected to phenolic hydroxy acetylation reaction at 60°C for 1.5 hours. After washing with deionized water and drying, residual formaldehyde, hydrochloric acid, acetic acid, acetic anhydride, etc. are removed. Finally, the two rollers are combined to obtain a non-crimped continuous long filament bundle of high-performance phenolic fiber with specifications of 1K, diameter of 12μm, strength of 220MPa, and breaking elongation of 20%.

[0046] Example 2 The synthesis method in this embodiment is the same as that in Example 1, with the identical parts omitted. The difference from Example 1 lies in that the phenolic monomers are hydroquinone and benzophenol, the aldehyde monomer is polyoxymethylene, the modifiers are triphenyl phosphate and epichlorohydrin, the catalyst is hydrochloric acid (2% by mass of reactants), the molar ratio of hydroquinone, benzophenol, polyoxymethylene, triphenyl phosphate, and epichlorohydrin is 0.3:0.7:0.88:0.07:0.02, and the reaction conditions are 98°C for 3.0 hours. The synthesized modified spinnable thermoplastic material has a softening point greater than 130°C. The temperature of the phenolic resin twin-screw extruder is 190℃, the gear pump 2 pressurizes to 3.0MPa, the spinneret 3 has 750 spinneret holes, the tension roller 6 applies a tension of 0.15N, the curing liquid is hydrochloric acid (14%) and hexamethylenetetramine (16%), the molar ratio of acetic acid and acetic anhydride is 1:1.5, the phenolic hydroxy acetylation reaction conditions are 65℃ for 2.0 hours, and finally the four-roller filament bundle is filamentized to obtain a non-crimped continuous long filament high-performance phenolic fiber with specification 3K, diameter 15μm, strength 280MPa, and breaking elongation of 30% through filament doubling.

[0047] Example 3 The synthesis method in this embodiment is the same as that in Example 1, with the identical parts omitted. The difference from Example 1 lies in that the phenolic monomers are resorcinol, vinylphenol, and xylenol; the aldehyde monomers are formaldehyde and polyoxymethylene; the modifier is epoxy cashew phenol; the catalyst is hydrochloric acid; the molar ratio of resorcinol, vinylphenol, xylenol, formaldehyde, polyoxymethylene, epoxy cashew phenol, and hydrochloric acid is 0.3:0.3:0.4:0.4:0.45:0.05:0.012; the reaction conditions are 96°C for 4.5 hours. The synthesized modified material with a softening point greater than 135°C can be... Thermoplastic phenolic resin was spun at a temperature of 210℃ using a twin-screw extruder, pressurized to 2.0MPa by a gear pump 2, and had 250 spinneret holes on a spinneret 3. Tension roller 6 applied a tension of 0.05N. The curing solution consisted of hydrochloric acid (15%) and hexamethylenetetramine (15%), with a molar ratio of acetic acid to acetic anhydride of 2:1. The phenolic hydroxyl acetylation reaction was carried out at 55℃ for 3.0 hours. Finally, the four-roller tow was filament-coated to obtain high-performance phenolic fibers with a specification of 0.5K, a diameter of 10μm, a strength of 250MPa, and an elongation at break of 25%, which were non-crimped continuous filaments.

[0048] Comparative Example 1 The synthesis method in this embodiment is the same as that in Example 1, with the identical parts omitted. The difference from Example 1 is that no modifier was added. Finally, the two rollers of filaments were combined to obtain high-performance phenolic fibers with a specification of 1K, a diameter of 12μm, a strength of 160MPa, and a breaking elongation of 8%, which are non-crimped continuous filaments. Compared with the phenolic fibers obtained in Example 1, the strength and breaking elongation are significantly reduced.

[0049] The present invention has been described above by way of example, but the present invention is not limited to the specific embodiments described above. Any modifications or variations made based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing non-crimped continuous filament bundle phenolic fibers, and process equipment applied to non-crimped continuous filament bundle phenolic fibers, characterized in that, The process equipment includes a spinneret unit, a guide unit, and a take-up unit. The spinneret unit includes a twin-screw mechanism, a gear pump, and a spinneret plate. The gear pump is located between the twin-screw mechanism and the spinneret plate. The guide unit includes guide rollers and an oil tank. There are multiple guide rollers, and the oil tank is located between two adjacent guide rollers. The take-up unit includes a tension roller and a take-up roller. The tension roller is located between the guide rollers and the take-up rollers. The preparation method includes the following steps: Phenolic monomers, aldehyde monomers, modifiers and catalysts are mixed and heated to react, resulting in modified spinnable thermoplastic phenolic resin. Modified spinnable thermoplastic phenolic resin is added to a twin-screw extruder to melt, remove free phenol and low-polymerization-degree small molecules, and then sent to a gear pump. The gear pump pressurizes the melt and then extrudes it through a spinneret to obtain the precursor fiber. The raw filaments are drawn and bundled through the guide roller and the oil trough, and a constant tension is applied by the tension roller. After being wound by the tetrafluoroethylene take-up roller, a long filament bundle of phenolic resin raw filaments is obtained. The original filament bundle and the tetrafluoroethylene take-up roller are placed in a curing solution for curing and cross-linking. After being placed in an acetic acid and acetic anhydride solution for phenolic hydroxyl acetylation, they are cleaned, dried, and finally filaments are drawn together to obtain non-crimped continuous filament bundle phenolic fiber. The gear pump provides a pressure of 0.5-10 MPa, and the tension roller has a tension of 0.02-0.2 N.

2. The preparation method according to claim 1, characterized in that, The temperature of the twin-screw mechanism is 120-220℃.

3. The preparation method according to claim 1, characterized in that, The spinneret has 250, 500, 750 or 1000 spinneret holes.

4. The preparation method according to claim 1, characterized in that, The phenolic monomers are one or more of phenol, bisphenol A, benzophenol, hydroquinone, resorcinol, diphenyl ether, vinylphenol, and xylenol; the aldehyde monomers are one or more of formaldehyde and oligooxyformaldehyde; the modifiers are one or more of epichlorohydrin, nonylphenol, epoxy cashew phenol, triphenyl phosphate, and xylene; and the catalysts are oxalic acid or hydrochloric acid.

5. The preparation method according to claim 1, characterized in that, The content of free phenols is reduced to less than or equal to 0.5%.

6. A non-crimped continuous filament tow phenolic fiber, characterized in that, The non-curled continuous filament bundle phenolic fiber is prepared by any one of claims 1 to 5.

7. The application of the non-curled continuous filament bundle phenolic fiber obtained by the preparation method according to any one of claims 1 to 5 in flame-retardant decorative materials.

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