Patent Application
20250171931
The present disclosure relates to the field of processing technology of polymer foamed fibers, and specifically relates to a polymer foamed fiber, and a preparation method and a use thereof.
Polymer foamed fibers combine advantages of fibers and porous structures, and have incomparable advantages over fiber materials, such as low density, high elasticity, large specific surface area. They have important application prospects in many emerging fields, such as functional clothing, wearables devices, consumer electronics, filtration and separation, catalysis. Existing methods for preparing polymer foamed fibers comprise phase separation in a coagulation bath and a high internal phase emulsion templating method, which involve usage of a lot of organic solvents and complex processing processes. Such processing processes are not environmentally friendly, can be applicable to limited polymer systems, and have low processing efficiency, which limits their application.
Supercritical fluids comprise supercritical carbon dioxide and supercritical nitrogen. They are widely available, residue-free and environmentally friendly, and have become one of the most important and most promising polymer physical foaming agents. In an academic article, Industrial & Engineering Chemistry Research, 2002, 41, 1195, studies on semi-continuous solid-state foamed polyetherimide (PEI) fibers are reported, wherein supercritical CO2 is used as a physical foaming agent and a foamed fiber in a micron/submicron porous structure is prepared through a two-step method comprising saturating polymer samples with a supercritical fluid in an autoclave and subjecting the polymer samples to a glycerol bath and heating to induce foam formation. However, the process is complicated to operate, and has high cost for equipment modification and narrow applicability to material systems. In addition, limited residence time of the supercritical fluids in solid fibers renders the process difficult to achieve large-scale production of solid fibers, so that the process cannot meet actual application requirements.
An objective of the present disclosure is to provide a polymer foamed fiber, a preparation method and a use thereof. The polymer foamed fiber prepared in the present disclosure has a plurality of advantages, such as, light weight, uniform fiber thickness, a porous structure, dense internal pores with uniform pore sizes, a controllable skin layer thickness and uniform pore distribution. Further, the preparation method of the present disclosure is simple to operate, low-cost, safe and environmentally friendly, and can achieve large-scale and continuous production.
In order to achieve the above objective, the present disclosure provides the following technical solution. A polymer foamed fiber is provided, wherein the polymer foamed fiber has a closed-pore structure in an interior, the closed-pore structure comprises uniform and dense pores and an average pore size of the pores in the closed-pore structure is in a range of from 1 μm to 50 μm; a diameter of the polymer foamed fiber is in a range of from 0.08 mm to 1.0 mm with an average deviation of the diameter of ±0.05 mm; a skin layer thickness of the polymer foamed fiber is in a range of from 0 to 0.1 mm, a density of the polymer foamed fiber is in a range of from 0.30 g/cm3 to 0.90 g/cm3, and an elongation at break of the polymer foamed fiber is in a range of from 0 to 600%.
Preferably, the polymer foamed fiber comprises following components in parts by weight: 90-100 parts of a polymer, 1-10 parts of a nucleating agent, 0-1 parts of a chain extender, and 0-0.5 parts of an antioxidant. More preferably, the polymer foamed fiber comprises the following components in parts by weight: 95-97 parts of the polymer, 3-5 parts of the nucleating agent, 0.2-0.3 parts of the chain extender, and 0.2-0.3 parts of the antioxidant.
Preferably, a melting point of the polymer is in a range of from 100° C. to 230° C. and a hardness of the polymer is in a range of from Shore 60A to Shore 64D.
Preferably, the polymer comprises one or more of a thermoplastic elastomer, polylactic acid (PLA), and polypropylene (PP), polyethylene terephthalate (PET) and nylon (PA).
More preferably, the thermoplastic elastomer comprises one or more of conventional thermoplastic elastomers in prior art, such as polyurethane (TPU), a polyester elastomer (TPEE) and a nylon elastomer (PEBA).
Preferably, the nucleating agent comprises at least one of calcium carbonate, talc, mica, montmorillonite, nano-silica, carbon black, and a carbon nanotube.
Preferably, a particle size of the nucleating agent is in a range of from 0.05 μm to 5 μm.
Preferably, the chain extender comprises at least one of a bisoxazoline chain extender and an epoxy chain extender.
Preferably, the antioxidant comprises at least one of an amine antioxidant and a phosphorus-containing antioxidant.
The present disclosure also provides a preparation method of the polymer foamed fiber, comprising following steps:
Preferably, the drying in step S1 is hot air drying, and a moisture content of the mixture after drying is less than 0.05 wt. %.
Preferably, the melt extrusion in step S1 is performed by using a twin-screw extruder, and temperatures from a feed port to an extrusion head of the twin-screw extruder are set to be 80° C., 180° C., 190° C., 205° C., 215° C., and 180° C.-190° C.
Preferably, a winding speed for winding the polymer fiber filament in step S1 is in a range of from 0.5 m/s to 2 m/s.
Preferably, a diameter of the polymer fiber filament in step S1 is in a range of from 0.08 mm to 0.80 mm.
Preferably, the polyvinyl alcohol solution in step S2 comprises following components in percentage by weight: 5-10 wt. % of polyvinyl alcohol (PVA), 70-80 wt. % of deionized water, 3-10 wt. % of hydrolyzed starch, and 3-10 wt. % of gypsum.
Preferably, a molecular weight of the polyvinyl alcohol is in a range of from 30,000 to 200,000, and an alcoholysis degree of the polyvinyl alcohol is 99%. More preferably, the molecular weight of the polyvinyl alcohol is in a range of from 50,000 to 150,000.
Preferably, the polyvinyl alcohol solution is prepared by uniformly mixing all components, thereby obtaining the polyvinyl alcohol solution.
Preferably, the inorganic filler comprises at least one of talc powder, graphene, micro-nano calcium carbonate, and nano silicon dioxide.
Preferably, an interval of coating time between the barrier layer and the isolation layer in step S2 is in a range of from 10 s to 20 s. More preferably, the interval of coating time between the barrier layer and the isolation layer is in a range of from 10 s to 15 s. Controlling the interval of coating time between the barrier layer and the isolation layer can ensure that the inorganic filler is effectively adhered to the surface.
Preferably, the supercritical fluid in step S3 comprises one of supercritical CO2, supercritical N2, and a mixed fluid of supercritical CO2 and supercritical N2.
Preferably, a solubility of the supercritical fluid in the primary product of the polymer foamed fiber in step S3 is in a range of from 0.5 wt. % to 5.0 wt. %. More preferably, the solubility of the supercritical fluid in the primary product of the polymer foamed fiber in step S3 is in a range of from 1.0 wt. % to 3.0 wt. %.
Preferably, a hardness of the primary product of the polymer foamed fiber in step S3 is in a range of from Shore 60A to Shore 64D. As the hardness of the polymer is different, the solubility of the supercritical fluid in the polymer is significantly different, and the foaming effect of conditional induction is also different.
Preferably, impregnating the primary product of the polymer foamed fiber in the supercritical fluid in step S3 is performed under a condition that a pressure is in a range of from 10 Mpa to 20 Mpa and a temperature is in a range of from 70° C. to 120° C.
More preferably, impregnating the primary product of the polymer foamed fiber in the supercritical fluid in step S3 is performed under the condition that the pressure is in a range of from 15 Mpa to 18 Mpa and the temperature is in a range of from 80° C. to 100° C.
Preferably, conditionally inducing the primary product of the polymer foamed fiber to foam is performed in a condition that the pressure and the temperature are rapidly changed, wherein a change rate for the pressure is in a range of from 10 Mpa/s to 15 Mpa/s and a change rate for the temperature is in a range of from 0 to 80° C./s.
In the process of conditional induction of the polymer fiber for foaming in the present disclosure, a level of conditional induction (i.e., a fast or slow change rate of the inducing condition) affects the growth degree of pores. If the inducing condition is changed too quickly, the pores in the fiber will be aggregated to form large pores, resulting in uneven pores; if the inducing condition is changed too slowly, the supercritical fluid dissolved in the fiber will be completely dissipated, resulting in a product with a poor foaming effect and a too high density.
Preferably, rinsing the induced polymer fiber in step S3 is performed with water, and a flow rate of the water is in a range of from 0 to 1 m/s and a rinsing time is in a range of from 0 to 30 s.
More preferably, the flow rate of the water is in a range of from 0 to 0.5 m/s, and the rinsing time is in a range of from 0 to 20 s.
In the present disclosure, the polymer fiber is conditionally induced to foam and form a porous structure, by inducing the supercritical fluid dissolved in the primary product of the polymer fiber to nucleate. Therefore, when conditional induction occurs, a loss rate of the supercritical fluid dissolved in the primary product of the polymer fiber dominates the porous structure of the polymer foamed fiber. The barrier layer formed on the surface of the polymer fiber by the PVA solution has an excellent gas barrier property, which can effectively prolong the residence time of the supercritical fluid in the polymer fiber and greatly improve the foaming effect of the polymer fiber. PVA with different molecular weights results in different viscosity of the PVA solutions and different gas barrier effects of the barrier layers. By defining the molecular weight of PVA, foamed fibers with more significant foaming effects and different porous structures can be obtained. At the same time, in order to obtain a foamed fiber with a lower density, it is required to induce the polymer fiber to foam at an appropriate temperature. Generally, in a certain range of temperature, the polymer will gradually be in a viscous state and a volume expansion effect caused by the foaming of the polymer fibers will make the polymer fibers adhere to each other, thereby affecting subsequent processing processes and formation of qualified products. Therefore, coating an isolation layer on the PVA barrier layer can effectively prevent the polymer fibers from adhering to each other, thereby ensuring that the obtained polymer fibers have a porous structure. Further, the barrier layer and the isolation layer formed in the preparation process will be removed in the subsequent rinsing process.
The present disclosure also provides a use of the polymer foamed fiber in a field of lightweight, functional clothing, military aerospace, electronic wearable devices, or thermal insulation.
Compared with the prior art, the present disclosure has the following beneficial effects.
In the present disclosure, a polymer foamed fiber having advantages of light weight, uniform fiber thickness, a porous structure and a multi-material system is prepared through selection of raw materials, innovative processing methods, induced foaming, and rewinding. The method can realize large-scale continuous production, and is low-cost, simple to operate, safe, and environmentally friendly. The present disclosure has provided an innovative method for preparing the polymer foamed fiber. By controlling the content of the supercritical fluid in the polymer fiber and the growth degree of the pores during the conditional induction process, the foamed fiber has a porous structure with uniform pores, uniform fiber thickness and a controllable skin layer thickness, thereby improving the production stability of the polymer foamed fiber by conditional induction. The polymer foamed fiber is weavable and wear-resistant, and has an excellent tensile property, so it is suitable for use in multiple fields, such as, lightweight, functional clothing, military aerospace, electronic wearable devices, and thermal insulation.
With reference to examples of the present disclosure, technical solutions in the examples of the present disclosure are clearly and completely described below. Obviously, the examples described are only a part of examples of the present disclosure, not all of them. Based on the examples of the present disclosure, all other examples obtained by those skilled in the art, without creative work, are within the scope of protection of the present disclosure.
In the examples and comparative examples, experimental methods used are conventional methods, and materials and reagents, etc. used are commercially available, unless otherwise specified.
Materials used in the examples and comparative examples are as follows:
According to the above preparation method, polyvinyl alcohol B1, polyvinyl alcohol B2, and polyvinyl alcohol B3 are selected to prepare polyvinyl alcohol solution C1, polyvinyl alcohol solution C2, and polyvinyl alcohol solution C3, respectively.
Components of the polymer foamed fibers, weight parts of the components and condition parameters in Examples 1-9 and Comparative Examples 1-6 were shown in Table 1, and performance parameters of the prepared polymer foamed fibers were shown in Table 2. A diameter of a polymer foamed fiber is measured by using an optical fiber diameter analyzer, according to Chinese National Standard GB/T20732-2006. A skin layer thicknesses and a pore size of a polymer foamed fiber are respectively determined, by measuring the skin layer thickness and the pore size (diameter) of the polymer foamed fiber in multiple images obtained by a scanning electron microscope (SEM) or by a microscope, repeating the measurement for several times, and averaging the results. Density of a polymer foamed fiber is measured according to Chinese National Standard GB/T14335.
Preparation method of the polymer foamed fiber in each of Examples 1-9 and Comparative Examples 1-6 comprises the following steps:
As can be seen from the data in Table 2, the polymer foamed fibers obtained in the examples of the present disclosure all have porous structures, suitable pore sizes, uniform pores, uniform fiber thickness, controllable skin layer thickness and low density.
In Comparative Example 1, the hardness of the polymer selected is not suitable, so the prepared polymer foamed fiber has a high density and cannot be foamed to form pores. In Comparative Example 2, the molecular weight of polyvinyl alcohol in the polyvinyl alcohol solution is not suitable, resulting in a reduced foaming effect, sparse pores, uneven distribution of pores and poor foaming effect. In Comparative Example 3, the solubility of supercritical CO2 in the primary product of the polymer foamed fiber is not suitable, resulting in a reduced foaming effect. Neither the change rate of pressure in Comparative Example nor the change rate of temperature in Comparative Example 5 is suitable, so the obtained polymer foamed fibers both have high skin layer thickness and high density. Further, the polymer foamed fiber prepared in Comparative Example 4 cannot be foamed to form pores and the polymer foamed fiber prepared in Comparative Example 5 has sparse pores, which are unevenly distributed. In Comparative Example 6, no nucleating agent is added, so the polymer foamed fiber prepared has sparse pores, which are unevenly distributed, and the foaming effect is poor.
As can be seen from
The above examples are only intended to illustrate the principles and effects of the present disclosure, rather than to limit the present disclosure. Any one skilled in the art can modify or change the above examples, without violating the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those skilled in the art, without departing from the spirit and technical ideas disclosed by the present disclosure, should still be covered by claims of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202310663168.X | Jun 2023 | CN | national |
The present application is a continuation-in-part application of PCT application No. PCT/CN2024/096648 filed on May 31, 2024, which claims the benefit of Chinese Patent Application No. 202310663168.X filed on Jun. 6, 2023. The contents of all of the aforementioned applications are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2024/096648 | May 2024 | WO |
| Child | 19031430 | US |
