Basalt fiber composite down-like particle filling material and preparation method thereof

Abstract

The present application relates to the field of textile and home textile filling materials, and discloses a basalt fiber composite down-like particle filling material and a preparation method thereof. The filling material comprises basalt chopped fibers, low-melting-point sheath-core and three-dimensional spiral crimp cross-section polyester staple fibers, silane-terminated modified water-based polyurethane emulsion and latent thermal expansion microspheres. The material has a cross-shaped three-dimensional cross-linking skeleton composed of basalt and low-melting-point polyester inside, and the spiral crimp staple fibers form a core-shell structure by wrapping the periphery; the basalt surface is coated with a polyurethane flexible film and embedded with a closed-cell microbubble support network. Through the above cross-linking skeleton support and electrostatic assembly process, the present application limits the disordered sliding of the fibers, improves the washing clumping and collapse problems of the material, and combines the in-situ expansion of the microspheres and the basalt characteristics, so that the finished product has high loft, shape stability, far-infrared heat storage and antibacterial functions.

Description

Technical Field

[0001] This invention relates to the field of textile and home textile filling materials, specifically to a basalt fiber composite down-like particle filling material and its preparation method. Background Technology

[0002] Down-like particle filling materials are widely used in the apparel and home textile industries, typically utilizing the physical crimping of polyester fibers to mimic the fluffy structure and warmth retention of natural down. Basalt fiber, an inorganic non-metallic material produced by melting and drawing basalt ore, possesses high mechanical strength and exhibits far-infrared radiation and basic antibacterial properties. In the textile filling field, combining basalt fiber with traditional polyester fibers has become a common technological direction for expanding the functionality of materials.

[0003] Existing polyester down-like pellets mostly rely on physical processing methods such as mechanical kneading or friction to form clumps. The internal structure of these materials is relatively loose, with fibers maintaining their shape primarily through disordered entanglement, lacking a stable internal framework. After routine washing or prolonged external compression, the fiber monomers are prone to irreversible relative slippage and the formation of dead knots, resulting in macroscopic clumping and collapse of the pellets, and a decreased deformation recovery rate. Simultaneously, the molding process relying solely on applied mechanical force easily causes a physical reduction in the original crimp of the spiral polyester fibers, directly reducing the air storage space within the pellets and affecting the overall fluffiness and feel of the material.

[0004] In the field of multi-component material composites, when inorganic basalt fibers are directly physically blended with organic polyester fibers, the interfacial compatibility is usually low due to the differences in surface tension and chemical structure between the two. Under stress, the inorganic and organic phases are prone to microscopic delamination, making it difficult to construct a stable three-dimensional spatial structure. Furthermore, the micropore structure of conventional composite fillers is difficult to control, and the presence of heat convection channels between fibers prevents the full conversion and utilization of the far-infrared heat storage characteristics of basalt fibers, thus limiting the overall performance of the filler in terms of lightweighting and efficient warmth retention. Therefore, this invention provides a basalt fiber composite down-like particle filler material and its preparation method to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a basalt fiber composite down-like particle filling material and its preparation method, which solves the problems of existing polyester fiber filling materials having a loose structure, lacking a stable three-dimensional skeleton, and being prone to fiber entanglement, clumping and collapse after washing, resulting in a decrease in fluffiness and warmth retention.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a basalt fiber composite down-like particle filling material, which adopts the following technical solution: A basalt fiber composite down-like particle filling material is made from raw materials comprising the following parts by weight: 15-30 parts basalt chopped short fibers; 10-20 parts low-melting-point core-sheath polyester short fibers; 60-90 parts three-dimensional helical crimped cross-section polyester short fibers; silane-terminated modified waterborne polyurethane emulsion, wherein the amount of the silane-terminated modified waterborne polyurethane emulsion added, calculated based on solid content, is 2%-5% of the mass of the basalt chopped short fibers; latent thermally expandable microspheres, wherein the amount of the latent thermally expandable microspheres added is 1.5%-4% of the mass of the basalt chopped short fibers; the particle filling material has an interior composed of the basalt chopped short fibers and the low-melting-point core-sheath. A three-dimensional cross-linked skeleton is formed by the cross-linking of polyester short fibers, and the three-dimensional spirally coiled polyester short fibers are wrapped around the periphery of the cross-linked skeleton. The surface of the basalt short-cut fibers is coated with a flexible polyurethane film formed by the cross-linking of the end-silyl modified waterborne polyurethane emulsion. The particulate filler material also has a three-dimensional closed-cell microbubble support network structure. The three-dimensional closed-cell microbubble support network structure is composed of closed-cell microbubbles formed by the latent thermally expanded microspheres after thermal expansion, and hot-melt nodes formed by the melting and solidification of the skin layer of the low-melting-point sheath-core polyester short fibers, which are cross-linked and supported by each other. The closed-cell microbubbles are embedded in the flexible polyurethane film.

[0007] By adopting the above technical solution, in this skeleton structure, the high Young's modulus basalt chopped fibers play a major supporting role, and the low-melting-point core-sheath polyester short fiber sheath at the cross-linking nodes, after fusion and solidification, can effectively limit the relative slippage and disordered entanglement of fiber monomers under stress. This structural feature allows the filling material to maintain its overall shape by relying on the internal cross-linking nodes when subjected to washing or external force kneading, thereby reducing the occurrence of free fiber clumping and collapse. During the curing of the silane-modified waterborne polyurethane emulsion, the silane-terminated end-silanes undergo siloxane hydrolysis and condensation, cross-linking into a film on the surface of the basalt fibers, thus serving as the interfacial bonding phase between the organic polyester and the inorganic basalt. The latent thermally expandable microspheres embedded in the film expand in volume upon heating, pushing against the surrounding molten polyester sheath material, thereby forming a three-dimensional support network embedded with closed-cell microbubbles. The closed-cell air layer inside the structure can impede the heat conduction process; combined with the absorption and radiation characteristics of basalt fibers for far-infrared rays, as well as its own partial metal oxide components, this material exhibits the basic physical mechanism of heat storage, warmth preservation, and antibacterial properties while retaining the internal network support. The three-dimensional spiral-curled cross-section polyester short fibers wrapped around the outside further complement the fluffy feel of the macroscopic particle surface.

[0008] Preferably, the silane-terminated modified waterborne polyurethane emulsion is polymerized from the following components in parts by weight: 100 parts of polytetrahydrofuran ether diol with a number average molecular weight of 2000; 30-45 parts of isophorone diisocyanate; 0.05-0.1 parts of dibutyltin dilaurate catalyst; 5-10 parts of dimethylolpropionic acid; 21.5-35.0 parts of γ-aminopropyltriethoxysilane; 4-8 parts of triethylamine; and deionized water, wherein the amount of deionized water added is to adjust the solid content of the silane-terminated modified waterborne polyurethane emulsion to 20%-30%.

[0009] By employing the above technical solution, polytetrahydrofuran ether diol and isophorone diisocyanate undergo addition polymerization under catalysis to construct a polyurethane backbone. Dimethylolpropionic acid is introduced as a hydrophilic chain extender and forms an aqueous dispersion system after neutralization with triethylamine. The terminal isocyanate undergoes nucleophilic addition with γ-aminopropyltriethoxysilane, endowing the molecular chain with terminal siloxane groups. In the later water evaporation stage, the siloxane groups hydrolyze and dehydrate to form a siloxane-silicon crosslinked network. This network structure improves the stability of the coating film in an aqueous environment and inhibits interfacial delamination during the subsequent washing process.

[0010] Preferably, the particulate filling material is a core-shell structured spherical object; wherein, the cross-shaped three-dimensional intersecting skeleton forms a cross-shaped micro-core; and the three-dimensional spirally curled cross-section polyester short fibers wrapped around the periphery of the cross-shaped three-dimensional intersecting skeleton form the outer shell of the core-shell structured spherical object.

[0011] By adopting the above technical solution, the cross-shaped micronucleus forms a relatively dense physical support in the central region of the particle to resist external compression and shear loads; the three-dimensional spirally curled polyester short fibers on the outside utilize their own curling properties to form a relatively loose spherical shell shape, providing a gas storage layer and initial compression rebound space. This density distribution gradient, which is tight inside and loose outside, simulates a distribution pattern similar to natural structures while taking into account the physical requirements of internal morphological support and surface fluffy feedback.

[0012] Secondly, the present invention provides a method for preparing a basalt fiber composite down-like particle filling material, which adopts the following technical solution: A method for preparing a basalt fiber composite down-like particle filling material includes the following steps: S1. A working solution is prepared by diluting a silane-terminated modified waterborne polyurethane emulsion with deionized water. Latent thermal expansion microspheres are added to the working solution. Basalt short-cut fibers are immersed in the working solution for impregnation treatment, filtered and dried to obtain pretreated basalt short-cut fibers. S2. The basalt short-cut fibers pretreated in step S1 are mixed with the opened low-melting-point sheath-core polyester short fibers and granulated by airflow to obtain cross-shaped micronuclei. The cross-shaped micronuclei form a cross-shaped three-dimensional cross skeleton. The cross-shaped micronuclei are sent into a positive electric field region to obtain cross-shaped micronuclei with positive charges on the surface. S3. After opening the three-dimensional spiral crimped cross-section polyester short fibers, they are passed through a negative electric field in airflow to obtain three-dimensional spiral crimped cross-section polyester short fibers carrying negative charges; the cross-shaped micro-core with positive charges on the surface is sent into the granulation chamber, and the three-dimensional spiral crimped cross-section polyester short fibers carrying negative charges are blown in, so that the three-dimensional spiral crimped cross-section polyester short fibers are wrapped around the outer layer of the cross-shaped micro-core to obtain a core-shell structure spherical object; S4. The core-shell structured spherical object is subjected to infrared-assisted heat treatment, which causes the latent thermal expansion microspheres to expand in situ and the skin of the low-melting-point sheath-core polyester short fiber to melt. S5. The particles processed in step S4 are subjected to air-cooled solidification treatment, and free fibers are screened out to obtain the finished product.

[0013] By employing the above technical solution, the preparation process of this invention relies on a molding mechanism combining the Coulomb attraction of opposite charges and internal thermal triggering. After the polyurethane emulsion working fluid loads the expanded microspheres onto the surface of basalt fibers, an airflow granulation process promotes the interpenetration and collision of short fibers of different hardnesses, establishing a basic cross-shaped skeleton configuration. Based on this, an electric field environment is introduced, causing the microcore and the surrounding helical fibers to carry opposite charges. Charge adsorption guides the fiber layering and coating, reducing the damage to the original crimp of the outer fibers caused by traditional purely mechanical kneading. The subsequent heat treatment uses infrared-assisted heating, the mechanism of which utilizes the absorption characteristics of basalt fiber materials in specific infrared bands to generate a localized temperature rise in the central region of the structure. The heat conduction process, diffusing outward from the core, causes the low-boiling-point solvent inside the surrounding microspheres to evaporate and expand. At this time, the external convective hot air works in synergy to soften the low-melting-point polyester skin at the microcore, allowing the volume expansion stress generated by the microspheres to drive the polyester melt to shift and bridge. Finally, the polyester melt is cooled and crystallized under the action of forced cold air, which solidifies the topological relationship of the pores and nodes after expansion and shaping.

[0014] Preferably, before step S1, the preparation step of the silane-terminated modified waterborne polyurethane emulsion is included, comprising: cooling polytetrahydrofuran ether diol after vacuum dehydration, adding isophorone diisocyanate and dibutyltin dilaurate as catalysts to react and obtain isocyanate-terminated polyurethane prepolymer; cooling and adding dimethylolpropionic acid to react; when the isocyanate group content reaches the theoretical value, cooling and adding γ-aminopropyltriethoxysilane for end-capping reaction; cooling to room temperature, adding triethylamine for neutralization, and adding deionized water for phase dispersion at a rotation speed of 1500-3000 rpm to obtain the silane-terminated modified waterborne polyurethane emulsion.

[0015] By adopting the above technical solution, the stepwise controlled polymerization reaction helps maintain the relative order of the molecular chain structure. After the isocyanate group and hydroxyl group construct the prepolymer, the end group content is controlled and a silane coupling agent is added for end capping, which can avoid premature cross-linking and gelation in the system; the shear force applied in the dispersion stage can overcome the interphase surface tension and promote the formation of an emulsion dispersion system of polymer in the aqueous phase.

[0016] Preferably, in step S1, the working solution has a mass concentration of 1%-3% based on the polyurethane solid content; the impregnation treatment time is 10-30 min; and the drying conditions are: temperature 85-105℃, time 30-60 min.

[0017] By employing the above technical solution and controlling the working solution concentration within the range of 1%-3%, the aim is to ensure that the system possesses sufficient fluidity to wet the fiber micro-pores, while simultaneously reducing the probability of rigid adhesion between fiber monomers caused by excessive solid content. The drying temperature is set within the dehydration requirement range and below the initial phase transition temperature of the expanded microspheres to maintain their structural stability during surface film formation.

[0018] Preferably, in step S2, the operating parameters for the airflow granulation are: stirring speed 150-300 rpm, pulse compressed air pressure 0.2-0.5 MPa, and granulation time 15-40 s; the applied voltage in the positive electric field region is +30 kV to +50 kV, and the residence time of the cross-shaped micronucleus in the positive electric field region is 0.5-2.0 s.

[0019] By employing the above technical solution, the combination of stirring and pulsed airflow within the granulation chamber disrupts the parallel orientation of the fibers, causing the rigid basalt and polyester staple fibers to physically interlock at multiple angles. Specific electric field parameters are set to allow charge distribution to be acquired on the surface of the micro-core, while the residence time interval is set within the process boundary to prevent ionization and breakdown of the material.

[0020] Preferably, in step S3, the applied voltage of the negative electric field is -30kV to -50kV; the granulation chamber is a negative pressure rotary drum granulation chamber with a porous wall, the drum speed is 20-50rpm, the internal axial vacuum negative pressure is -5kPa to -15kPa, and the blowing treatment time is 10-30s.

[0021] By adopting the above technical solution, in the rotary drum granulation chamber with negative pressure environment, the axial vacuum negative pressure can weaken the irregular dispersion of fine denier fibers in the suspended airflow to a certain extent, causing their movement trajectory to move closer to the center; combined with the low-speed rotating equipment and the effect of charge attraction, the outer spiral fibers gradually attach around the micro core.

[0022] Preferably, in step S4, the operating parameters for the infrared-assisted heat treatment are: ambient convective hot air temperature 115-125℃, peak infrared radiation wavelength 6-15μm, and radiation surface power density 1.5-3.5kW / m². 2 Heat treatment time: 3-8 minutes.

[0023] By adopting the above technical solution, the 6-15μm infrared band is selected to match the absorption frequency of some inorganic components, thereby exciting lattice vibrations to generate heat. Combined with a hot air environment of 115-125℃, the superimposed temperature rise generated by infrared absorption promotes the melting of the polyester skin at the core intersection point; while the spiral crimped fibers on the periphery, being far from the central heating medium, are limited by the direct effect of the hot air, thus retaining their macroscopic morphology at room temperature.

[0024] Preferably, in step S5, the operating parameters for the air-cooled curing treatment are: forced convection air at a temperature of 15-25℃ is introduced, and the cooling treatment time is 1-3 minutes.

[0025] By employing the above technical solution, the temperature gradient around the system is eliminated after the introduction of convective cooling air, prompting the polymer melt to cross the glass transition range. After the macromolecular chain segments are frozen, the spatial distribution of microbubbles under pressure and the connection state between fibers are fixed at the microscopic level, mitigating the structural deformation caused by the release of internal stress during later use.

[0026] This invention provides a basalt fiber composite down-like particle filling material and its preparation method. It has the following beneficial effects: 1. This invention constructs a cross-shaped three-dimensional skeleton within the particles by cross-linking basalt chopped fibers with low-melting-point polyester short fibers. This structure utilizes the rigid support of the inorganic fibers and the adhesive effect of the melted low-melting-point polyester sheath to fix the cross nodes between fibers and limit the relative slippage of individual fibers under external forces. This feature improves the problems of washing clumping and collapse caused by disordered fiber entanglement in traditional filling cotton, and enhances the long-term morphological stability of the material.

[0027] 2. This invention introduces an electrostatic field environment during the preparation process, causing the cross-shaped microcore and the three-dimensional helical cross-section polyester short fibers to carry opposite charges. The attraction of these charges guides the outer helical fibers to attach and directionally coat the fibers. This molding method replaces conventional high-intensity mechanical kneading, reducing physical damage to the initial curl of the outer fibers. The resulting core-shell morphology allows the particles to possess internal support strength while retaining ample air storage space and a highly fluffy, down-like feel on the surface.

[0028] 3. This invention involves crosslinking a silane-modified waterborne polyurethane emulsion onto a basalt surface to form a film, which is then loaded with latent thermally expandable microspheres. Infrared-assisted heat treatment induces in-situ expansion of the microspheres due to internal heat. The expanding microspheres push against the polyester melt in the crosslinked regions of the skeletal framework, forming a three-dimensional closed-cell microbubble support network embedded within the film. The closed-cell air layer within the network impedes heat conduction. Combined with the far-infrared radiation characteristics and inorganic components of the basalt fiber itself, this invention achieves heat storage and insulation as well as basic antibacterial functions while reducing the particle physical density. Attached Figure Description

[0029] Figure 1 The Fourier transform infrared spectra of each fiber sample after Soxhlet extraction according to the present invention are shown. Figure 2 This is a representative temperature variation trend diagram of the down-like particle core and shell under different heat treatment processes of the present invention. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The following are specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher products.

[0032] Short-cut fibers are produced by mechanically cutting continuous basalt fiber precursors. The diameter of the single filament is 7-13 μm and the chopped length is 15-35 mm. The surface contains active hydroxyl groups with natural silicate structure.

[0033] This is a concentric circle core-sheath structure bicomponent composite polyester staple fiber with a linear density of 1.5–4.0D and a length of 32–51 mm. The sheath material is a low-melting-point copolyester randomly copolymerized from terephthalic acid, isophthalic acid, and ethylene glycol, with a melting point of 110℃–120℃. The core material is polyethylene terephthalate (CAS number 25038-59-9), with a melting point of 250℃–260℃.

[0034] The three-dimensional spiral crimped cross-section polyester staple fiber is made of polyethylene terephthalate, CAS number 25038-59-9, with a linear density of 0.7~3.0D, a length of 32~64mm, and no antistatic oil is attached to the surface.

[0035] Polytetrahydrofuran ether diol, CAS number 25190-06-1, has a number average molecular weight of 1000-2000.

[0036] Isophorone diisocyanate, CAS number 4098-71-9.

[0037] Dibutyltin dilaurate, CAS number 77-58-7.

[0038] Dimethylolpropionic acid, CAS number 4767-03-7.

[0039] γ-aminopropyltriethoxysilane, CAS number 919-30-2.

[0040] Triethylamine, CAS number 121-44-8.

[0041] The latent thermally expandable microspheres are core-shell structured foamed microcapsules. The thermoplastic resin outer shell material is polyacrylonitrile-methyl methacrylate copolymer, and the core foaming agent encapsulated inside is liquid isoparaffin. The initial expansion temperature of the microspheres is... The maximum expansion temperature is 125℃~135℃. The temperature range is 150℃~160℃, and the average particle size in the unexpanded state is 10~15μm.

[0042] Preparation Example 1: This preparation example provides a method for preparing a silane-terminated modified aqueous polyurethane emulsion, including the following steps: (1) 100 parts by mass of polytetrahydrofuran ether diol with a number average molecular weight of 2000 were dehydrated under vacuum at 105°C for 1.5 h and then cooled to 60°C. 38 parts by mass of isophorone diisocyanate and 0.08 parts by mass of dibutyltin dilaurate catalyst were added and reacted at 83°C for 2.5 h to obtain isocyanate-terminated polyurethane prepolymer. (2) Cool down to 65°C, add 8 parts by mass of dimethylolpropionic acid as a hydrophilic chain extender, react for 2 hours, and then cool down after the NCO content reaches the theoretical value. (3) Continue cooling to 45℃, add 27.5 parts by mass of γ-aminopropyltriethoxysilane, cap the reaction for 45 min, and continue the reaction until the mass fraction of NCO in the system is ≤0.1%; (4) Cool down to room temperature, add 6 parts by mass of triethylamine to neutralize and form salt, and then slowly add deionized water under high-speed shearing at 2000 rpm to disperse the phase and obtain a silane-modified waterborne polyurethane emulsion with a solid content of 25%.

[0043] Preparation Example 2: This preparation example provides a method for preparing a silane-terminated modified aqueous polyurethane emulsion, including the following steps: (1) 100 parts by mass of polytetrahydrofuran ether diol with a number average molecular weight of 2000 were dehydrated under vacuum at 100°C for 1 h and then cooled to 60°C. 30 parts by mass of isophorone diisocyanate and 0.05 parts by mass of dibutyltin dilaurate catalyst were added and reacted at 80°C for 2 h to obtain isocyanate-terminated polyurethane prepolymer. (2) Cool down to 65°C, add 5 parts by mass of dimethylolpropionic acid as a hydrophilic chain extender, react for 1.5 h, and then cool down after the NCO content reaches the theoretical value. (3) Continue cooling to 40℃, add 21.5 parts by mass of γ-aminopropyltriethoxysilane, cap the reaction for 30 min, and continue the reaction until the mass fraction of NCO in the system is ≤0.1%; (4) Cool down to room temperature, add 4 parts by mass of triethylamine to neutralize and form salt, and then slowly add deionized water under high speed shear at 1500 rpm to disperse the phase, and obtain a silane-modified waterborne polyurethane emulsion with a solid content of 20%.

[0044] Preparation Example 3: This preparation example provides a method for preparing a silane-terminated modified aqueous polyurethane emulsion, including the following steps: (1) 100 parts by mass of polytetrahydrofuran ether diol with a number average molecular weight of 2000 were dehydrated under vacuum at 110°C for 2 hours and then cooled to 60°C. 45 parts by mass of isophorone diisocyanate and 0.1 parts by mass of dibutyltin dilaurate catalyst were added and reacted at 85°C for 3 hours to obtain isocyanate-terminated polyurethane prepolymer. (2) Cool down to 65°C, add 10 parts by mass of dimethylolpropionic acid as a hydrophilic chain extender, react for 2.5 h, and after the NCO content reaches the theoretical value, cool down. (3) Continue cooling to 50℃, add 35.0 parts by mass of γ-aminopropyltriethoxysilane, cap the reaction for 60 min, and continue the reaction until the mass fraction of NCO in the system is ≤0.1%; (4) Cool down to room temperature, add 8 parts by mass of triethylamine to neutralize and form salt, and then slowly add deionized water under high-speed shearing at 3000 rpm to disperse the phase, and obtain a silane-terminated modified waterborne polyurethane emulsion with a solid content of 30%.

[0045] Example 1: This embodiment provides a method for preparing a basalt fiber composite down-like particle filling material, including the following steps: (1) The silane-modified aqueous polyurethane emulsion obtained in Preparation Example 1 was diluted with deionized water to a working solution with a mass concentration of 2% based on the polyurethane solid content. Simultaneously, latent thermal expansion microspheres were dispersed and added to the working solution and stirred evenly under ultrasonic assistance. The amount of silane-modified aqueous polyurethane emulsion added, based on the solid content, was 3.5% of the mass of the subsequent basalt chopped fibers, and the amount of latent thermal expansion microspheres added was 2.5% of the mass of the subsequent basalt chopped fibers. 22 parts by weight of basalt chopped fibers were immersed in the working solution and soaked at room temperature for 20 min. Then, excess liquid was removed by filtration, and the fibers were dried in a hot air oven at 95°C for 45 min. A cross-linked polyurethane flexible film was formed on the surface of the basalt chopped fibers, and the latent thermal expansion microspheres were embedded in the flexible film.

[0046] (2) 22 parts by weight of pretreated basalt chopped fibers and 15 parts by weight of opened low-melting-point core-sheath polyester staple fibers were mixed and fed into an inner ring granulation chamber with a flexible silicone stirring paddle. The paddle rotation speed was controlled at 220 rpm, and pulsed compressed air at 0.35 MPa was introduced for 25 s to assemble a dense cross-shaped micronucleus. The micronucleus was then sent into a pipe with a DC high-voltage positive electric field on the outer wall by airflow. A voltage of +40 kV was applied, and the residence time of the micronucleus in this area was 1.2 s, causing its surface to carry a positive charge.

[0047] (3) 75 parts by weight of three-dimensional spiral crimped cross-section polyester short fibers were finely opened and subjected to a DC high voltage negative electric field of -40kV during air transport to make them carry negative charge. The positively charged micronuclei were continuously fed into the negative pressure drum granulation chamber with porous walls. The drum speed was set to 35rpm and a vacuum negative pressure of -10kPa was applied axially inside. The negatively charged three-dimensional spiral crimped cross-section polyester short fibers were uniformly blown in from the outside of the drum and treated for 20s, and oriented to wrap around the outer layer of the micronuclei to form a core-shell structure spherical object.

[0048] (4) The core-shell spherical structure was placed into an infrared-assisted hot air oven. The ambient convection hot air temperature was set to 120°C. The mid- and far-infrared radiation generator was turned on, and the peak radiation wavelength was controlled at 8 μm. The power density of the radiation surface was 2.5 kW / m². 2The heat treatment time is 5 minutes. The basalt short-cut fibers in the microcore absorb infrared radiation and generate heat, causing the local core temperature to rise to 145℃. This triggers the in-situ volume expansion of the latent thermal expansion microspheres, which in turn pushes the low-melting-point sheath-core polyester short fiber skin and the core-shell interface thermal fusion nodes outward, forming a microbubble support network with closed-cell characteristics.

[0049] (5) Transfer the particles to the cooling zone and introduce forced convection cold air at 20°C for 2 minutes to cool and solidify the sheath melt of the low melting point core polyester short fiber. The microbubble support nodes lock the three-dimensional skeleton and microporous structure. After removing free fibers by vibration sieve, the finished product is obtained.

[0050] Example 2: This embodiment provides a method for preparing a basalt fiber composite down-like particle filling material, including the following steps: (1) The silane-modified aqueous polyurethane emulsion obtained in Preparation Example 2 was diluted with deionized water to a working solution with a mass concentration of 1% based on the polyurethane solid content. Simultaneously, latent thermal expansion microspheres were dispersed and added to the working solution and stirred evenly under ultrasonic assistance. The amount of silane-modified aqueous polyurethane emulsion added, based on the solid content, was 2% of the mass of the subsequent basalt chopped fibers, and the amount of latent thermal expansion microspheres added was 1.5% of the mass of the subsequent basalt chopped fibers. 15 parts by weight of basalt chopped fibers were immersed in the working solution and soaked at room temperature for 10 min. Then, excess liquid was removed by filtration, and the fibers were placed in a hot air oven and dried at 85°C for 30 min. A cross-linked polyurethane flexible film was formed on the surface of the basalt chopped fibers, and the latent thermal expansion microspheres were embedded in the flexible film.

[0051] (2) 15 parts by weight of pretreated basalt short-cut fibers and 10 parts by weight of opened low-melting-point core-sheath polyester short fibers were mixed and fed into an inner ring granulation chamber with a flexible silicone stirring paddle. The paddle rotation speed was controlled at 150 rpm, and pulsed compressed air at 0.2 MPa was introduced for 15 s to assemble a dense cross-shaped micronucleus. The micronucleus was then sent into a pipe with a DC high-voltage positive electric field on the outer wall by airflow. A voltage of +30 kV was applied, and the residence time of the micronucleus in this area was 0.5 s, so that its surface carried a positive charge.

[0052] (3) 60 parts by weight of three-dimensional spiral crimped cross-section polyester short fibers were finely opened and subjected to a DC high voltage negative electric field of -30kV during air transport to make them carry negative charge. The positively charged micronuclei were continuously fed into the negative pressure drum granulation chamber with porous walls. The drum speed was set to 20rpm and a vacuum negative pressure of -5kPa was applied axially inside. The negatively charged three-dimensional spiral crimped cross-section polyester short fibers were uniformly blown in from the outside of the drum and treated for 10s, and oriented to wrap around the outer layer of the micronuclei to form a core-shell structure spherical object.

[0053] (4) The core-shell spherical structure is placed into an infrared-assisted hot air oven. The ambient convection hot air temperature is set to 115℃. The mid- and far-infrared radiation generator is turned on, and the peak radiation wavelength is controlled at 6μm. The power density of the radiation surface is 1.5kW / m². 2 The heat treatment time is 3 minutes. The basalt short-cut fibers in the microcore absorb infrared radiation and generate heat, raising the local core temperature to 140℃. This effectively triggers the in-situ volume expansion of the latent thermal expansion microspheres, and pushes the low-melting-point sheath-core polyester short fiber skin and the core-shell interface thermal fusion nodes in a viscous flow state outward to form a microbubble support network with closed-cell characteristics.

[0054] (5) Transfer the particles to the cooling zone and introduce forced convection cold air at 15°C for 1 minute to cool and solidify the sheath melt of the low melting point core polyester short fiber. The microbubble support nodes lock the three-dimensional skeleton and microporous structure. After removing free fibers by vibration sieve, the finished product is obtained.

[0055] Example 3: This embodiment provides a method for preparing a basalt fiber composite down-like particle filling material, including the following steps: (1) The silane-modified aqueous polyurethane emulsion obtained in Preparation Example 3 was diluted with deionized water to a working solution with a mass concentration of 3% based on the polyurethane solid content. Simultaneously, latent thermal expansion microspheres were dispersed and added to the working solution and stirred evenly under ultrasonic assistance. The amount of silane-modified aqueous polyurethane emulsion added, based on the solid content, was 5% of the mass of the subsequent basalt chopped fibers, and the amount of latent thermal expansion microspheres added was 4% of the mass of the subsequent basalt chopped fibers. 30 parts by weight of basalt chopped fibers were immersed in the working solution and soaked at room temperature for 30 min. Then, excess liquid was removed by filtration, and the fibers were placed in a hot air oven and dried at 105°C for 60 min. A cross-linked polyurethane flexible film was formed on the surface of the basalt chopped fibers, and the latent thermal expansion microspheres were embedded in the flexible film.

[0056] (2) 30 parts by weight of pretreated basalt chopped fibers and 20 parts by weight of opened low-melting-point sheath-core polyester staple fibers were mixed and fed into an inner ring granulation chamber with a flexible silicone stirring paddle. The paddle rotation speed was controlled at 300 rpm, and pulsed compressed air at 0.5 MPa was introduced for 40 s to assemble a dense cross-shaped micronucleus. The micronucleus was then sent into a pipe with a DC high-voltage positive electric field on the outer wall by airflow. A voltage of +50 kV was applied, and the residence time of the micronucleus in this area was 2.0 s, causing its surface to carry a positive charge.

[0057] (3) 90 parts by weight of three-dimensional spiral crimped cross-section polyester short fibers were finely opened and then subjected to a DC high voltage negative electric field of -50kV during air transport to make them carry negative charges. The positively charged micronuclei were continuously fed into the negative pressure drum granulation chamber with porous walls. The drum speed was set to 50rpm and a vacuum negative pressure of -15kPa was applied axially inside. The negatively charged three-dimensional spiral crimped cross-section polyester short fibers were uniformly blown in from the outside of the drum and treated for 30s, and then oriented to wrap around the outer layer of the micronuclei to form a core-shell structure spherical object.

[0058] (4) The core-shell spherical structure is placed into an infrared-assisted hot air oven. The ambient convection hot air temperature is set to 125℃. The mid- and far-infrared radiation generator is turned on, and the peak radiation wavelength is controlled at 15μm. The power density of the radiation surface is 3.5kW / m². 2 The heat treatment time is 8 minutes. The basalt short-cut fibers in the microcore absorb infrared radiation and generate heat, causing the local core temperature to rise to 150°C. This triggers the in-situ volume expansion of the latent thermal expansion microspheres, which in turn pushes the low-melting-point sheath-core polyester short fiber skin and the core-shell interface thermal fusion nodes outward, forming a microbubble support network with closed-cell characteristics.

[0059] (5) Transfer the particles to the cooling zone and introduce forced convection cold air at 25°C for 3 minutes to cool and solidify the sheath melt of the low melting point core polyester short fiber. The microbubble support nodes lock the three-dimensional skeleton and microporous structure. After removing free fibers by vibration sieve, the finished product is obtained.

[0060] Comparative Example 1: Compared with Example 1, the difference is that in step (1), a regular waterborne polyurethane emulsion that has not been modified by γ-aminopropyltriethoxysilane is used instead of the silane-modified waterborne polyurethane emulsion, and all other aspects are the same.

[0061] Comparative Example 2: Compared with Example 1, the difference is that in steps (2) and (3), no DC high voltage positive electric field and DC high voltage negative electric field are applied to polarize and charge the micro-core and the three-dimensional spiral curled cross section polyester short fiber. The wrapping is carried out only by the vacuum negative pressure inside the drum and the physical blowing of the airflow. The rest are the same.

[0062] Comparative Example 3: Compared with Example 1, the difference is that in step (4), a conventional forced convection hot air oven is used instead of an infrared-assisted hot air oven, the ambient convection hot air temperature is set to 145°C and there is no infrared radiation generator, and the infrared absorption self-heating effect of basalt short-cut fibers is not used to construct a thermodynamic ladder, and the rest are the same.

[0063] Comparative Example 4: Compared with Example 1, the difference is that: in step (1), no latent thermal expansion microspheres were added to the working fluid, and no microbubble support network generated by the thermal expansion microspheres was formed during the subsequent heat treatment process. The other raw material ratios and operating conditions were the same as in Example 1.

[0064] Test Example 1: Experimental Description: Fourier transform infrared spectroscopy combined with Soxhlet extraction pretreatment was used to analyze the characteristic absorption changes of the extractable components on the fiber surface after removal, which helped to determine the interfacial bonding state of the silane-modified waterborne polyurethane emulsion on the basalt fiber surface.

[0065] Experimental steps: Take 4.5g of each of the following: untreated basalt short-cut fibers, core short-cut fibers extracted from the particles prepared in Comparative Example 1, and core short-cut fibers extracted from the particles prepared in Example 1, and use them as test samples.

[0066] The three samples were placed into neutral filter paper tubes and then into the extraction tubes of a Soxhlet extractor. 200 mL of analytical grade acetone was added to the lower flask as the extraction solvent.

[0067] The water bath heating temperature was set to 65℃, and acetone was continuously heated and refluxed to extract and wash the fiber sample. The washing time was maintained for 24 hours to reduce or remove free polymer and weakly bound polymer components that can be extracted by acetone from the fiber surface.

[0068] After the extraction process is complete, remove the filter paper tube and transfer the fiber sample inside into a vacuum drying oven. Set the temperature to 80℃ and the vacuum degree to -0.09MPa, and dry continuously for 12 hours to remove residual solvent.

[0069] The dried fiber samples were cut into small pieces and mixed with dried potassium bromide powder in an agate mortar at a mass ratio of 1:100. The mixture was then pressed into transparent test sheets using a tablet press under a pressure of 20 MPa.

[0070] The pellet was placed in the sample chamber of the Fourier transform infrared spectrometer, and the scanning range was set to 4000 cm⁻¹. -1 Up to 400cm -1 Spectral resolution of 4 cm -1 The cumulative scan count was set to 32 times. The transmission spectrum was recorded and converted into absorbance. The relative absorbance values ​​of the target wavenumber range were extracted.

[0071] The experimental data are shown in Table 1: Table 1: Relative absorbance of characteristic peaks in Fourier transform infrared spectra of various fiber samples after Soxhlet extraction

[0072] According to Table 1 and Figure 1 Data shows that untreated basalt fibers at 3342 cm⁻¹ -1 It exhibits a relatively distinct -OH-related absorption peak at 1723 cm⁻¹, with a relative absorbance of 0.413; its absorption peak at 1723 cm⁻¹ is also significant. -1 The relative absorbance at 3342 cm⁻¹ was 0.016, indicating that the absorption related to the polyurethane carbonyl group in this sample was weak. Comparative Example 1 used ordinary waterborne polyurethane emulsion treated with unmodified silanized fibers. After continuous reflux extraction with acetone, its absorbance at 3342 cm⁻¹ was... -1 1723cm -1 and 1084cm -1 The relative absorbances at these locations were 0.387, 0.045, and 0.141, respectively, which are generally similar to those of untreated basalt fibers. These results suggest that the polymer components remaining on the fiber surface in Comparative Example 1 are relatively few, indicating that the bonding stability of ordinary aqueous polyurethane emulsion on the basalt fiber surface is relatively limited.

[0073] The extracted sample from Example 1, after undergoing the same extraction conditions, reached a depth of 3342 cm⁻¹. -1 The relative absorbance at 1723 cm⁻¹ decreased to 0.179. -1 The relative absorbance at 1084 cm⁻¹ is 0.534. -1 The relative absorbance at 1723 cm⁻¹ was 0.678. Compared with untreated basalt fibers and fibers extracted in Comparative Example 1, the fibers extracted in Example 1 showed better absorbance at 1723 cm⁻¹. -1 The urethane carbonyl group still retains a relatively obvious absorption at 1084 cm⁻¹. -1 The Si-O-Si related absorption is enhanced at 3342 cm⁻¹, while the absorption at 3342 cm⁻¹ is enhanced. -1 The -OH-related absorption decreased. These results indicate that after treatment with silane-terminated modified waterborne polyurethane, an organic-inorganic interfacial layer exists on the surface of basalt fibers that is difficult to remove by acetone extraction. Considering the hydrolysis and condensation reaction characteristics of silane end groups, it can be inferred that this interfacial layer may contain silicon-oxygen bonds, condensation crosslinks, or strong interfacial interactions, thereby improving the retention stability of the polyurethane flexible film on the basalt fiber surface.

[0074] Based on the above test results, the basalt chopped fibers treated with silane-modified waterborne polyurethane emulsion exhibit relatively stable polymer retention characteristics. This flexible polyurethane membrane can act as an interfacial buffer for the rigid basalt fibers during granulation, helping to reduce stress concentration in the microcrack areas on the inorganic fiber surface, thereby reducing the risk of fiber breakage and pulverization. Furthermore, the polymer-modified layer retained on the fiber surface provides a dielectric response basis for subsequent electrostatic polarization and fiber coating processes, facilitating the implementation of a fluid dynamics and electric field coupled granulation process.

[0075] Test Example 2: Experimental Description: Using an in-situ heating test platform equipped with miniature thermocouples, the real-time temperature changes of the internal core and outer shell of down-like particles under different heat treatment processes were recorded. The effects of different heating methods on the internal temperature distribution and heating process of the particles were investigated, and the results were used to evaluate the participation of basalt short-cut fibers in the formation of local temperature gradients under infrared-assisted hot air technology.

[0076] Experimental steps: Intermediate samples from Examples 1 and 3, after being assembled into core-shell spherical structures but before entering the hot air oven, were used as test subjects.

[0077] Two K-type miniature thermocouple probes with a wire diameter of 0.15 mm were inserted into the geometric center of the same test sample as the core temperature measuring point, and about 0.5 mm below the surface layer as the shell temperature measuring point. A small amount of thermally conductive silicone grease was used to seal the puncture holes to reduce heat loss.

[0078] The test sample loaded with probes is placed on the ventilation mesh plate of the in-situ heating test platform and connected to a multi-channel temperature data acquisition instrument.

[0079] For the test sample in Example 1, the ambient convection hot air of the test platform was turned on, the temperature was set to a constant 120°C, and the mid- and far-infrared radiation generator above was turned on simultaneously to continuously record the temperature change data of the sample over 5 minutes, with the sampling frequency set to 2Hz.

[0080] For the test sample of Comparative Example 3, only the ambient convection hot air of the test platform was turned on, the temperature was set to a constant 145℃, the infrared radiation generator was kept off, and the temperature change data of the sample over time was continuously recorded over 5 minutes.

[0081] Extract the temperature values ​​of the data acquisition instrument at specific time points, and compare the heat transfer efficiency and temperature rise pattern of the sample core and shell under different heating mechanisms.

[0082] The experimental data are shown in Table 2: Table 2: Real-time temperature data of the down-like particle core and shell under different heat treatment processes

[0083] According to Table 2 and Figure 2According to the data, when using a single high-temperature hot air heating method in Comparative Example 3, the temperature of the outer shell measuring point was higher than that of the core measuring point at all test time points, showing a characteristic of heating from the outside to the inside. When the processing time reached 4.5 minutes, the core temperature rose to 134.6℃, reaching or approaching the initial expansion temperature range of the latent thermal expansion microspheres, but at this time the outer shell temperature had already risen to 143.7℃. This temperature is higher than the suitable softening and bonding range of 110℃ to 120℃ for the low-melting-point polyester short fiber skin layer. Therefore, under single high-temperature hot air heating conditions, the low-melting-point skin layer near the core-shell interface and the outer edge of the core may soften, flow, and form denser hot-melt nodes earlier; although the outer three-dimensional spiral coiled polyester fiber did not reach the melting temperature, its coiled pores may shrink to a certain extent due to thermal compression and node hardening, thus affecting the material's loose structure. At the same time, the outer fiber has a certain barrier effect on heat transfer, causing the core region to reach the initial expansion temperature of the microspheres relatively later.

[0084] In Example 1, when infrared-assisted hot air was used for processing, the temperature changes at the core and outer shell measuring points showed a different trend compared to Comparative Example 3. At 0.5 min, the temperature at the outer shell measuring point was 82.1℃, higher than the core measuring point temperature of 68.4℃, indicating that the outer shell was still mainly affected by the ambient hot air during the initial heating stage. When the processing time was extended to 1.5 min and beyond, the temperature at the core measuring point gradually exceeded that at the outer shell measuring point, suggesting that the core region produced a relatively more significant heating response under infrared radiation. When the processing time reached 4.5 min, the core temperature reached 146.1℃, which is within the temperature range that can trigger the expansion of latent thermal expansion microspheres; at the same time, the outer shell temperature was 120.8℃, close to the softening and bonding temperature range of the low-melting-point polyester short fiber skin layer. This temperature distribution is conducive to the volume expansion of the core microspheres, while reducing the risk of excessive thermal compression or overall collapse of the outer fiber shell.

[0085] Through the combined use of infrared radiation and medium-temperature hot air, the sample of Example 1 exhibited a temperature distribution characterized by a high core temperature and a relatively moderate temperature in the outer fibrous shell. This temperature distribution facilitates the core region reaching the expansion trigger temperature of the latent thermal expansion microspheres, while simultaneously maintaining the outer fibrous shell within a temperature range suitable for heat setting and softening bonding. Compared to a single high-temperature hot air treatment method, this approach can mitigate the core heating lag caused by heat transfer from the outside in to the inside to some extent. Under the aforementioned heat treatment conditions, the volume change of the thermal expansion microspheres acts on the softened thermally fused nodes, thereby forming a microbubble support structure with closed-cell characteristics. This structure helps reduce the apparent density of the intersecting nodes within the particles and improves the lightweight nature of the down-like particle skeleton.

[0086] Test Example 3: Experimental Description: Using a dynamic tumbling chamber and a high-precision analytical balance, the particle structure integrity of the material under simulated continuous mechanical external force was tested. The influence of flexible polymer membrane on the pulverization behavior of rigid inorganic fibers and the effect of electrostatic assisted coating process on the retention of core-shell structure were investigated.

[0087] Experimental steps: The down-like particles obtained from Examples 1 to 3, as well as Comparative Examples 1 and 2, were used as test objects. Each group of samples was placed in a standard environmental conditioning room and left to stand for 24 hours. The temperature of the conditioning room was 20°C and the relative humidity was 65%.

[0088] Weigh 100.0g of each group of samples using a high-precision analytical balance and record it as the initial test mass.

[0089] The weighed samples were placed into the test chamber of the dynamic tumbling chamber. The rotation speed of the tumbling chamber was set to 60 rpm. Five standard rubber test balls were loaded inside to increase mechanical collision and friction intensity. The continuous running time was set to 120 min.

[0090] After the operation is completed, the sample is taken out and all the material in the chamber is transferred to the surface of a standard test sieve with an aperture of 0.2 mm, and processed for 5 minutes using a vibrating sieve separator.

[0091] Collect fine dust from the bottom pan of a standard test sieve, weigh it using an analytical balance, calculate its percentage of the initial test mass, and record it as the pulverization rate of the sample.

[0092] One hundred complete core-shell structured particles were randomly selected from the particles retained on the sieve using the quartering method and observed one by one under a desktop magnifying glass with a magnification of 10x.

[0093] The number of particles with black basalt core fibers piercing through the white outer polyester fibers, resulting in visible exposed cores, was counted. This percentage of the total number of particles extracted was recorded as the puncture-drop rate. Each sample was tested in triplicate. The pulverization rate data in the table is the average of the three test results, and the puncture-drop rate data is the rounded integer value of the average of the three test results.

[0094] The experimental data are shown in Table 3: Table 3: Test data on mechanical pulverization rate and puncture-drop rate of each group of down-like particle samples

[0095] According to the data in Table 3, the pulverization rate of Comparative Example 1 was 3.85%, which was higher than that of Examples 1 to 3. Comparative Example 1 used a common aqueous polyurethane emulsion without silane end-group modification, which had relatively weak retention stability on the basalt fiber surface. Under dynamic mechanical tumbling and rubber ball collision conditions, the polyurethane coating layer on the fiber surface may be more prone to local desorption or damage, causing the basalt fiber to be subjected to more direct friction and impact under external forces. As a result, the probability of breakage or debris shedding at defective areas on the fiber surface increases, manifested as an increased pulverization rate.

[0096] The pulverization rates in Examples 1 to 3 ranged from 0.28% to 0.41%. This result indicates that the basalt chopped fibers treated with silane-modified waterborne polyurethane exhibited a low degree of pulverization under mechanical tumbling conditions. Combined with the interface characterization results of Test Example 1, it can be concluded that the flexible polyurethane layer retained on the fiber surface helps provide a certain degree of interfacial buffering during mechanical impact, reducing stress concentration in defect areas on the basalt fiber surface, thereby reducing the risk of powder precipitation.

[0097] Comparing the puncture and shedding rates, Comparative Example 2 showed a puncture and shedding rate of 28%. Comparative Example 2 did not undergo high-pressure electrostatic polarization treatment during the granulation and assembly stage; the microcore and surrounding polyester fibers mainly relied on physical adsorption and entanglement through negative pressure airflow within the drum. Due to the lack of adsorption by opposite charges, the coating of the microcore by the surrounding polyester fibers may not be uniform or dense enough, resulting in relatively low stability of the core-shell interface structure. Under mechanical tumbling and friction, the ends of the rigid basalt fibers were more prone to local exposure or puncture, thus exhibiting a high puncture and shedding rate.

[0098] The puncture and shedding rates of Examples 1 to 3 ranged from 1% to 3%. Compared to Comparative Example 2, the Examples introduced anisotropic charge adsorption between the microcore and the outer three-dimensional spirally coiled polyester staple fibers, and combined with negative pressure airflow guidance, making it easier for the outer coiled fibers to form a continuous coating and entanglement structure on the surface of the microcore. This coating structure helps to improve the coverage of the rigid core by the outer polyester fibers, reduce the probability of basalt fiber ends penetrating outward, and allow the particles to maintain better core-shell structural integrity after mechanical tumbling.

[0099] Test Example 4: Experimental Description: Using a test cylinder and a flat plate heat preservation instrument, the specific volume and thermal resistance of each group of materials under the same conditions were measured to investigate the influence of the internal thermal fusion node structure of the particles on the bulkiness and heat preservation performance of the materials, and to evaluate the effects of infrared-assisted heat treatment and thermal expansion microspheres on the lightweighting effect of the materials.

[0100] Experimental steps: The down-like particles prepared in Examples 1 to 3, Comparative Example 3 and Comparative Example 4 were selected as test objects and placed in a standard environmentally conditioned room for static pretreatment for 24 hours. The ambient temperature was controlled at 20 degrees Celsius and the relative humidity was controlled at 65%.

[0101] When conducting the volumetric test, 20.00g of each sample was accurately weighed using a high-precision analytical balance.

[0102] The weighed sample is evenly filled into a transparent standard acrylic test cylinder with an inner diameter of 150 mm, and a lightweight standard pressure plate with a mass of 50 g is placed stably on top of the sample.

[0103] After letting it stand for 3 minutes until the pressure plate descends and stabilizes, read the volume scale corresponding to the bottom of the pressure plate on the side wall of the cylinder. Divide this volume value by the sample mass to calculate the specific volume of the sample.

[0104] When conducting the Clo value test, each group of samples was evenly filled and sewn into a standard breathable and down-proof test bag with a uniform areal density of 250g per square meter.

[0105] The thermal resistance of the sewn test bag was measured using a flat plate thermal insulator. The temperature of the bottom test main board was set to 35.0 degrees Celsius, and the temperature of the ambient airflow above was set to 20.0 degrees Celsius.

[0106] Turn on the instrument and maintain thermal flow balance. Record the thermal resistance parameters after the system has been running stably for 30 minutes, and convert them into Clo value as the final evaluation index. Each group of samples was tested in parallel 3 times. The data in the table is the average of the 3 test results.

[0107] The experimental data are shown in Table 4: Table 4: Specific volume and Clo value test data of down-like particles in each group

[0108] According to the data in Table 4, the specific volume and Clo value of Comparative Example 4 are lower than those of Examples 1 to 3. Comparative Example 4 did not contain latent thermally expandable microspheres; the low-melting-point polyester at its internal interlacing nodes softened and bonded upon heating, forming relatively dense bonded nodes upon cooling. These nodes are difficult to form a microporous structure supported by thermally expandable microspheres, therefore the material's volume occupied per unit mass and its ability to retain still air are relatively low, resulting in a decrease in specific volume and Clo value.

[0109] The specific volume and Clo value of Comparative Example 3 were higher than those of Comparative Example 4, but lower than those of Examples 1 to 3. Comparative Example 3 used a single-environment high-temperature hot air process for heat treatment, with heat mainly transferred from the outside of the particles to the inside, resulting in a relatively delayed heating of the core region. When the core region reached or approached the thermal expansion trigger temperature of the microspheres, the low-melting-point core-sheath polyester short fiber skin and the core-shell interface thermal fusion nodes had already been subjected to high temperatures for a considerable period, potentially leading to higher softening, localized flow, and node densification. This phenomenon somewhat restricts the pore space inside the particles and affects the fluffy state of the outer three-dimensional spirally coiled polyester fiber shell, thus impacting the volume expansion effect of the internal microspheres.

[0110] The specific volume of Examples 1 to 3 was 181.5 cm³. 3 / g to 192.3cm 3 / g, with Clo values ​​ranging from 2.55clo to 2.81clo, all higher than Comparative Examples 3 and 4. Test results indicate that the infrared-assisted hot air treatment in the embodiment scheme facilitates reaching the expansion trigger temperature of the latent thermal expansion microspheres in the core region, while simultaneously maintaining a relatively suitable thermally set state in the outer fibrous shell. The thermally expansion microspheres distributed in the core region undergo in-situ volume expansion upon heating, providing some support to the softened, fused nodes, resulting in a relatively loose microporous structure in the node region.

[0111] Furthermore, in Example 2, the proportion of the core formed by basalt chopped fibers and low-melting-point sheath-core polyester staple fibers is relatively low, while the proportion of the outer three-dimensional spiral-curled polyester staple fibers is relatively high. Therefore, its bulk volume and thermal resistance per unit mass are relatively high. Although Example 3 uses a higher amount of thermally expanding microspheres, the amount of basalt chopped fibers and low-melting-point sheath-core polyester staple fibers is increased simultaneously, and the proportion of the core skeleton in the material per unit mass is increased. Therefore, its specific volume and Clo value are slightly lower than those of Example 2.

[0112] The above results demonstrate that the embodiment scheme can form a microbubble support structure with closed-cell characteristics and enriched with still air at the fiber interlacing points. This microporous structure, while maintaining the basic support function of the core-shell skeleton, can reduce the apparent density of the fused nodes and the effective solid content per unit volume, thereby increasing the space occupancy per unit mass of material. Simultaneously, the relatively closed still air layer inside the nodes helps reduce heat conduction, resulting in a higher Cro value for the material. Therefore, the combined use of infrared-assisted heat treatment and thermally expanding microspheres is beneficial for improving the lightweight and thermal insulation performance of composite down-like particles.

[0113] Test Example 5: Experimental Description: Using a standard washing machine and a thickness measuring instrument, the thickness changes of each group of materials after continuous washing and drying cycles were measured to investigate the thickness retention of the down-like particles after water flow impact, dehydration centrifugation and drying treatment, and to evaluate the influence of different structural designs on the volume stability of the materials after washing.

[0114] Experimental steps: The down-like particles prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were selected as test objects. According to the filling density standard of 250g per square meter, each group of samples was filled into a standard polyester fiber test bag with a size of 40cm by 40cm and then sewn together.

[0115] The sewn test pack was placed in a standard environment with a temperature of 20 degrees Celsius and a relative humidity of 65% and allowed to stand for 24 hours to equilibrate.

[0116] A thickness measuring instrument was used to measure the thickness of the test package at the center and four corners under a constant pressure of 2 cN / cm². The average value of the five test points was taken and recorded as the initial thickness.

[0117] The test kit was placed in a standard drum washing machine, set to the regular cotton fabric washing program, with the water temperature set to 40 degrees Celsius, a single wash time of 45 minutes, and a spin speed of 800 rpm, and the washing and spin-drying cycles were performed continuously for 10 cycles.

[0118] After the washing cycle is complete, the test pack is transferred to a tumble dryer and dried continuously at a constant temperature of 60 degrees Celsius for 90 minutes. After removal, it is left to stand in a standard environment for another 24 hours.

[0119] The thickness of each test point of the test package was measured again under the same constant pressure using a thickness measuring instrument. The average value was recorded as the thickness after washing. The percentage ratio of the thickness after washing to the initial thickness was calculated and recorded as the thickness retention rate. Each group of samples was tested in parallel 3 times. The data in the table is the average value of the 3 test results.

[0120] The experimental data are shown in Table 5: Table 5: Thickness Change and Retention Rate of Down-like Particles in Each Group Before and After Washing Cycles

[0121] According to the data in Table 5, the thickness retention rates of Comparative Example 1 and Comparative Example 2 were 55.3% and 50.3%, respectively, which were lower than those of Examples 1 to 3. Comparative Example 1 lacked silane end-group modification treatment, resulting in relatively low bonding stability of the polyurethane film on the basalt fiber surface. Under the action of water flow impact, dehydration centrifugation, and drying cycles, the fiber surface coating layer may experience local desorption or damage, causing the internal rigid inorganic skeleton to be subjected to more direct mechanical action, thus leading to a decrease in the test package thickness. Comparative Example 2 did not undergo high-voltage electrostatic polarization treatment during preparation, resulting in relatively insufficient coating and entanglement stability between the outer polyester fiber and the core. In the water washing test, relative fiber slippage, local loosening, or agglomeration were more likely to occur, thus resulting in a lower thickness retention rate after washing.

[0122] The thickness retention rates of Comparative Examples 3 and 4 were 63.3% and 55.5%, respectively, which were also lower than those of Examples 1 to 3. Comparative Example 4 did not introduce latent thermally expandable microspheres; its fiber interlacing nodes mainly formed a relatively dense thermoplastic bonded structure. The compressible space and elastic recovery space of this type of structure are relatively limited, making it difficult to recover to its initial fluffy state after washing and dehydration. Comparative Example 3 used a single convective hot air heating method. During heat treatment, the low-melting-point core-sheath polyester short fiber sheath and the core-shell interface thermoplastic nodes may experience higher softening, localized flow, and node densification. This phenomenon affects the internal pore space of the particles and the fluffy recovery ability of the outer three-dimensional helical coiled polyester fiber shell, thus reducing the thickness retention rate of the material after multiple washing and drying cycles.

[0123] The thickness retention rates of Examples 1 to 3 were 89.7% to 93.0%, significantly higher than those of the comparative examples. Test data indicate that the embodiments are beneficial for improving the volume stability of the material after continuous washing and drying cycles. At the skeleton interface, the stable interfacial bonding layer formed between the silane-modified waterborne polyurethane and the basalt fiber surface helps improve the wash resistance retention of the fiber surface coating, reducing the risk of loosening or damage to the main skeleton under water immersion and mechanical impact conditions. In the outer shell, the outer layer of crimped fiber coating structure formed with the assistance of opposite charge adsorption helps improve the contact and entanglement stability between fiber layers, thereby reducing the loosening of the outer coating structure during washing.

[0124] It should be noted that the thickness reduction in Comparative Example 2 is mainly related to the insufficient stability of the outer coating structure. Because this group of samples lacks the aid of opposite charge adsorption, the outer coating structure is relatively loose, making it more prone to particle disintegration, fiber slippage, or localized agglomeration under the effects of water washing shearing and dehydration centrifugation. Therefore, although Comparative Example 2 showed a lower pulverization rate than Comparative Example 1 in Test Example 3, its thickness retention rate after washing remained at a low level.

[0125] Furthermore, the microbubble support structure formed at the interlacing nodes may also participate in the material's compression recovery process. Under infrared-assisted heat treatment, thermally expanded microspheres form microbubble support structures with closed-cell characteristics and enriched with still air at the interlacing points. When the particles are subjected to centrifugal mechanical compression during the dehydration process, the microbubble structure and crimped fibers can undergo a certain degree of reversible compression; when the external force is removed and the drying process begins, the moisture is gradually removed, the adhesion of interfiber liquid bridges decreases, and the microbubble support nodes and three-dimensional crimped fibers help the particle structure recover its fluffy state. Therefore, this structural design can reduce the risk of permanent thickness loss of the material after washing cycles, enabling the material to maintain a high thickness retention rate.

[0126] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A basalt fiber composite down-like particle filling material, characterized in that, Made from the following ingredients in parts by weight: 15-30 parts of basalt short-cut fibers; 10-20 parts of low-melting-point core-sheath polyester staple fiber; 60-90 parts of three-dimensional spiral crimped cross-section polyester staple fiber; A silane-terminated modified waterborne polyurethane emulsion, wherein the amount of the silane-terminated modified waterborne polyurethane emulsion added, calculated based on solid content, is 2%-5% of the mass of the basalt chopped fibers; Latent thermally expandable microspheres, wherein the amount of latent thermally expandable microspheres added is 1.5%-4% of the mass of the basalt short-cut fibers; The interior of the granular filler material has a cross-shaped three-dimensional skeleton formed by the cross-linking of the basalt short-cut fibers and the low-melting-point sheath-core polyester short fibers, and the three-dimensional spiral-curled polyester short fibers wrap around the periphery of the cross-shaped three-dimensional skeleton. The surface of the basalt short-cut fibers is coated with a flexible polyurethane film formed by cross-linking the terminal silane-modified waterborne polyurethane emulsion; the particulate filling material also has a three-dimensional closed-cell microbubble support network structure, which is composed of closed-cell microbubbles formed by the latent thermally expanded microspheres after thermal expansion, and hot-melt nodes formed by the melting and solidification of the skin layer of the low-melting-point sheath-core polyester short fibers, which are cross-linked and supported by each other, and the closed-cell microbubbles are embedded in the flexible polyurethane film.

2. The basalt fiber composite down-like particle filling material according to claim 1, characterized in that, The silane-terminated modified waterborne polyurethane emulsion is polymerized from components comprising the following parts by weight: 100 parts of polytetrahydrofuran ether diol with a number average molecular weight of 2000; 30-45 parts of isophorone diisocyanate; 0.05-0.1 parts of dibutyltin dilaurate catalyst; 5-10 parts of dimethylolpropionic acid; γ-aminopropyltriethoxysilane 21.5-35.0 parts; 4-8 parts of triethylamine; Deionized water, wherein the amount of deionized water added is the amount used to adjust the solid content of the silane-terminated modified waterborne polyurethane emulsion to 20%-30%.

3. The basalt fiber composite down-like particle filling material according to claim 1, characterized in that, The particulate filling material is a core-shell structured spherical object; The cross-shaped three-dimensional skeleton forms a cross-shaped micro-core; the three-dimensional spiral-curved cross-section polyester short fibers surrounding the cross-shaped three-dimensional skeleton form the outer shell of the core-shell structure spherical object.

4. A method for preparing a basalt fiber composite down-like particle filling material as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. A working solution is prepared by diluting a silane-terminated modified waterborne polyurethane emulsion with deionized water. Latent thermal expansion microspheres are added to the working solution. Basalt short-cut fibers are immersed in the working solution for impregnation treatment, filtered and dried to obtain pretreated basalt short-cut fibers. S2. The basalt short-cut fibers pretreated in step S1 are mixed with the opened low-melting-point sheath-core polyester short fibers and granulated by airflow to obtain cross-shaped micronuclei. The cross-shaped micronuclei form a cross-shaped three-dimensional cross skeleton. The cross-shaped micronuclei are sent into a positive electric field region to obtain cross-shaped micronuclei with positive charges on the surface. S3. After opening the three-dimensional spiral crimped cross-section polyester short fibers, they are passed through a negative electric field in airflow to obtain three-dimensional spiral crimped cross-section polyester short fibers carrying negative charges; the cross-shaped micro-core with positive charges on the surface is sent into the granulation chamber, and the three-dimensional spiral crimped cross-section polyester short fibers carrying negative charges are blown in, so that the three-dimensional spiral crimped cross-section polyester short fibers are wrapped around the outer layer of the cross-shaped micro-core to obtain a core-shell structure spherical object; S4. The core-shell structured spherical object is subjected to infrared-assisted heat treatment, which causes the latent thermal expansion microspheres to expand in situ and the skin of the low-melting-point sheath-core polyester short fiber to melt. S5. The particles processed in step S4 are subjected to air-cooled solidification treatment, and free fibers are screened out to obtain the finished product.

5. The method for preparing the basalt fiber composite down-like particle filling material according to claim 4, characterized in that, Prior to step S1, the process also includes a step of preparing the silane-terminated modified aqueous polyurethane emulsion, including: Polytetrahydrofuran ether diol was dehydrated under vacuum and then cooled. Isophorone diisocyanate and dibutyltin dilaurate catalyst were added to react and obtain isocyanate-terminated polyurethane prepolymer. The mixture was then cooled and dimethylolpropionic acid was added to react. When the isocyanate group content reached the theoretical value, the mixture was cooled and γ-aminopropyltriethoxysilane was added to carry out the end-capping reaction. The mixture was cooled to room temperature and neutralized with triethylamine. Deionized water was added at a speed of 1500-3000 rpm to disperse the phase and obtain silane-terminated modified waterborne polyurethane emulsion.

6. The method for preparing the basalt fiber composite down-like particle filling material according to claim 4, characterized in that, In step S1, the working solution has a mass concentration of 1%-3% based on the polyurethane solid content; the impregnation treatment time is 10-30 min; and the drying conditions are: temperature 85-105℃, time 30-60 min.

7. The preparation method of the basalt fiber composite down-like particle filling material according to claim 4, characterized in that, In step S2, the operating parameters for airflow granulation are: stirring speed 150-300 rpm, pulse compressed air pressure 0.2-0.5 MPa, and granulation time 15-40 s; the applied voltage in the positive electric field region is +30 kV to +50 kV, and the residence time of the cross-shaped micronucleus in the positive electric field region is 0.5-2.0 s.

8. The method for preparing the basalt fiber composite down-like particle filling material according to claim 4, characterized in that, In step S3, the applied voltage of the negative electric field is -30kV to -50kV; the granulation chamber is a negative pressure rotary drum granulation chamber with a porous wall, the drum speed is 20-50rpm, the internal axial vacuum negative pressure is -5kPa to -15kPa, and the blowing treatment time is 10-30s.

9. The preparation method of the basalt fiber composite down-like particle filling material according to claim 4, characterized in that, In step S4, the operating parameters for the infrared-assisted heat treatment are: ambient convective hot air temperature 115-125℃, peak infrared radiation wavelength 6-15μm, and radiation surface power density 1.5-3.5kW / m². 2 Heat treatment time: 3-8 minutes.

10. The method for preparing the basalt fiber composite down-like particle filling material according to claim 4, characterized in that, In step S5, the operating parameters for the air-cooled curing process are: forced convection air at a temperature of 15-25℃ is introduced, and the cooling time is 1-3 minutes.

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