A washable composite thermal material for garments and process for its production

Abstract

This invention discloses a washable composite thermal insulation material for clothing and its manufacturing process. The manufacturing process includes: mixing polyimide short fibers and three-dimensional hollow polyester short fibers, followed by opening, carding, web formation, and reinforcement to obtain a composite fiber layer; impregnating the mixture in a treatment solution containing a mercaptosilane coupling agent and a carbon-carbon double-bond silane coupling agent; in-situ polymerization initiated by ultraviolet light irradiation under inert gas protection; and finally, drying, condensation, and hot pressing to obtain the finished product. This invention produces a composite thermal insulation material that combines high bulkiness, breathability, softness, and excellent washability.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials technology, specifically to a washable composite thermal insulation material for clothing and its manufacturing process. Background Technology

[0002] In existing technologies, single-layer composite wadding is typically prepared by mixing polyimide short fibers with three-dimensional hollow polyester short fibers. However, pure polyimide fibers have extremely strong chemical inertness, a smooth surface, lack of active groups, and very low surface energy. This results in a lack of effective bonding between fibers within the composite fiber layer, relying mainly on physical entanglement. During repeated washing, the fibers are prone to relative slippage, leading to a loose wadding structure, reduced thickness, and a significant decrease in thermal insulation performance. Conventional low-melting-point resins also struggle to effectively spread and wet their surface.

[0003] To address these issues, those skilled in the art typically consider chemically modifying the fiber surface. For example, immersing the fiber flakes in a treatment solution containing a mercaptosilane coupling agent aims to utilize the high reactivity of the mercapto groups to form chemical bonds during subsequent hot pressing, thereby improving wash resistance. However, in actual production, after treatment with a mercaptosilane coupling agent, the large number of mercapto groups (-SH) introduced onto the fiber surface are highly susceptible to uncontrolled premature oxidation under air and subsequent drying and heating conditions, rapidly forming disulfide bonds (-SS-). This results in severe "premature cross-linking" and localized adhesion and hardening between fibers before the hot pressing and setting process, completely destroying the required fluffiness and soft feel of the clothing insulation material, and also greatly reducing the smoothness and yield of production processes. On the other hand, spontaneously generated disulfide bonds are extremely unstable under the humid heat of repeated washing and mechanical rubbing, easily breaking and rearranging, causing the interlayer bonding force to rapidly decrease with increasing washing cycles.

[0004] In existing technologies, the chemical bonding of fibers is often spontaneous, lacking effective spatiotemporal control. This fails to prevent premature oxidation of thiol groups and cannot simultaneously meet the multiple performance requirements of thermal insulation wadding, such as fluffiness, breathability, and softness. Therefore, developing a composite thermal insulation material that can solve the problem of poor inter-fiber bonding, effectively prevent premature cross-linking in actual production, and ultimately achieve excellent washability and a highly fluffy and soft feel has become an urgent technical problem to be solved in this field. Based on this, the present invention provides a washable composite thermal insulation material for clothing and its manufacturing process. Summary of the Invention

[0005] The purpose of this invention is to provide a washable composite thermal insulation material for clothing and its production process. By in-situ polymerization of carbon-carbon double-bond silane coupling agents induced by ultraviolet light to form a cross-linked network, the problem of premature cross-linking and hardening caused by mercaptosilane coupling agents is solved. At the same time, the flexible network formed by the carbon-carbon double-bond silane coupling agent is used to reversely improve the washability of mercaptosilane coupling agents, thereby obtaining a highly fluffy, soft and washable thermal insulation material.

[0006] In a first aspect, the present invention provides a manufacturing process for a washable composite thermal insulation material for clothing, comprising the following steps: (1) Preparation of polyimide composite fiber layer: By weight, take 75-90 parts of polyimide staple fiber and 10-25 parts of three-dimensional hollow polyester staple fiber; The above fibers are mixed and then opened, carded, and laid into a web. A single-layer polyimide composite fiber layer with a basis weight of 80-180 g / m² is obtained through physical reinforcement. 2 ; (2) Preparation of composite silane treatment solution: A mercaptosilane coupling agent and a carbon-carbon double bond silane coupling agent are mixed at a weight ratio of 1:0.5-1:2, and a photoinitiator, catalyst and nano-silica are added. The mixture is then dispersed in a water-alcohol mixed solvent to prepare a composite silane treatment solution with a solid content of 3-10%. The mercaptosilane coupling agent is at least one of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; The carbon-carbon double bond-containing silane coupling agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane; The photoinitiator is at least one of 2-hydroxy-2-methyl-1-phenylpropanone and 1-hydroxycyclohexylphenyl ketone; (3) Impregnation treatment: The polyimide composite fiber layer obtained in step (1) is immersed in the composite silane treatment solution prepared in step (2) for 30-120 seconds, and then excess liquid is removed by roll extrusion, with the roll residue rate controlled at 60-90%. (4) Ultraviolet light-induced in-situ polymerization: The polyimide composite fiber layer impregnated in step (3) is then irradiated with ultraviolet light of wavelength 320-400 nm under nitrogen or inert gas protection for 30-180 seconds at an intensity of 10-50 mW / cm². 2 ; The photoinitiator decomposes under ultraviolet light to generate free radicals, which initiate free radical polymerization of silane coupling agents containing carbon-carbon double bonds, forming a polysiloxane crosslinking network in situ on the fiber surface. This network, like a microcapsule, encapsulates and fixes the mercapto-containing silane coupling agent molecules, thereby completely isolating the mercapto groups from contact with air and preventing their oxidation to form disulfide bonds. This successfully overcomes the uncontrollable "premature crosslinking" and adhesion hardening between fibers.

[0007] (5) Drying and in-situ condensation reaction: The polyimide composite fiber layer after UV treatment in step (4) is dried at 80-120℃ for 5-15 minutes to further hydrolyze and condense the hydrolyzable groups in the silane coupling agent to form a Si-O-Si cross-linked structure and form a chemical bond with the polar groups on the fiber surface. (6) Hot pressing and shaping: The polyimide composite fiber layer dried in step (5) is hot-pressed and shaped at a hot-pressing temperature of 120-150℃ and a hot-pressing pressure of 0.1-0.4MPa for 30-120 seconds. At this time, the encapsulated thiol groups form stable chemical bonds with the fibers and adjacent networks under hot pressing, which completely solves the problem of poor bonding between fibers. After cooling, rolling, and slitting, a washable composite insulation material for clothing is obtained.

[0008] Further, in step (2), the weight ratio of the mercaptosilane coupling agent to the carbon-carbon double bond silane coupling agent is 1:0.8-1:1.5.

[0009] Further, in step (2), the amount of photoinitiator added is 0.5-3% of the total weight of the silane coupling agent.

[0010] Further, in step (2), the catalyst is acetic acid, hydrochloric acid or ammonia water, used to adjust the pH of the treatment solution to 3-5 or 8-10.

[0011] Further, in step (2), the average particle size of the nano-silica is 10-80 nm, and the amount added is 5-25% of the total weight of the silane coupling agent.

[0012] Further, in step (1), the main cylinder speed of the combing is 800-1200 rpm, the working roller speed is 60-120 rpm, and the stripping roller speed is 100-200 rpm; the web laying adopts cross-laying or parallel laying method, and the number of web layers is 1-3 layers.

[0013] Further, in step (1), the reinforcement method is needle reinforcement, the needle density is 100-250 needles / cm², and the needle depth is 5-10mm.

[0014] Furthermore, in step (4), the wavelength of the ultraviolet light is 365nm and the irradiation time is 60-120 seconds.

[0015] Furthermore, in step (4), the nitrogen or inert gas protection is to prevent oxygen from inhibiting the free radical polymerization reaction.

[0016] Furthermore, in step (6), the hot pressing and shaping is performed using a flatbed hot press or a hot roller pressing device.

[0017] Secondly, the present invention also provides a washable composite thermal insulation material for clothing, which is prepared using the aforementioned production process.

[0018] The beneficial effects of this invention are as follows: To address the technical challenge of premature oxidation and cross-linking of thiol groups in air when introducing mercaptosilane coupling agents into polyimide flocs, leading to material adhesion and hardening, this invention introduces an ultraviolet-induced in-situ polymerization reaction of silane coupling agents containing carbon-carbon double bonds. This in-situ polymerization rapidly forms a polysiloxane cross-linked network on the fiber surface without interfering with the activity of the mercaptosilane coupling agent, physically encapsulating the easily oxidized thiol groups and achieving spatiotemporal blocking of the reaction. The reaction does not occur before ultraviolet irradiation; after irradiation, the in-situ network is instantly generated and protects the thiol groups, ensuring the flocs maintain absolute fluffiness and softness before entering the hot-pressing and setting process, greatly improving operability and yield in actual production.

[0019] Simple mercaptosilane coupling agents can only provide basic rigid crosslinking to solve the problem of poor wash resistance. However, this invention introduces UV-induced in-situ polymerization of silane coupling agents containing carbon-carbon double bonds. The resulting polysiloxane network not only protects the mercapto groups but also contains a large number of highly flexible, hydrolysis-resistant Si-O-Si backbones. This composite connection mechanism of mercapto chemical bonds and flexible physical bridging of Si-O-Si produces a synergistic effect. Under the wet and hot mechanical impact of repeated washing, the flexible Si-O-Si segments not only do not break but also absorb stress and undergo network conformation rearrangement and stretching, making the stress points between fibers more uniform. This makes the bonding force, which would normally decrease with washing, increase instead, achieving a significant strengthening effect, resulting in a thickness retention rate of over 93% after 30 machine washes.

[0020] In the field of thermal insulation filament modification, mercaptosilanes are usually used exclusively for metal corrosion protection or rubber vulcanization, and their application in the modification of polyimide fibers is itself subject to cross-border obstacles; furthermore, this invention uses ultraviolet light to trigger in-situ polymerization of vinyl silane to "microencapsulate" mercapto groups, thus solving the drawbacks of single modification.

[0021] This invention employs a single-layer fiber structure, without introducing a dense reinforcing membrane layer or a large-area resin adhesive layer, thus preserving the microporous structure between the fibers. Simultaneously, the polysiloxane network exists only on the fiber surface and does not fill the gaps between fibers, maintaining the material's high air and moisture permeability and excellent softness. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0023] It should also be noted that, in the specific embodiments of the present invention, the main raw materials used and their sources are as follows: polyimide staple fiber, with a fineness of 1.5-7D and a length of 32-64mm, purchased from Jiangsu Aoshen New Material Co., Ltd.; three-dimensional hollow polyester staple fiber, with a fineness of 1.5-7D and a length of 32-74mm, purchased from Sinopec Yizheng Chemical Fiber Co., Ltd.; and nano-silica, with an average particle size of 20-50nm and a specific surface area of ​​150-300m². 2 / g, purchased from Shanghai McLean Biochemical Technology Co., Ltd. Example 1

[0024] This embodiment provides a production process for a washable composite thermal insulation material for clothing, specifically including the following steps: (1) Preparation of polyimide composite fiber layer: By weight, 82 parts of polyimide staple fiber and 18 parts of three-dimensional hollow polyester staple fiber (both fineness / length 3D / 51mm) were taken. The above fibers were mixed and then opened, carded, and laid into a web, and a single-layer polyimide composite fiber layer was obtained by physical reinforcement.

[0025] The carding process uses a main cylinder speed of 1000 rpm, a working roller speed of 90 rpm, and a stripping roller speed of 150 rpm; the web laying adopts a cross-laying method with two web layers; the reinforcement method is needle punching reinforcement with a needle punching density of 180 needles / cm² and a needle punching depth of 8 mm; the basis weight of the polyimide composite fiber layer is 100 g / m².

[0026] (2) Preparation of composite silane treatment solution: Take 5g of 3-mercaptopropyltrimethoxysilane and 5g of vinyltrimethoxysilane and dissolve them in 300mL of ethanol and 200mL of deionized water. The weight ratio of the mercaptosilane coupling agent to the carbon-carbon double bond silane coupling agent is 1:1.

[0027] Add 0.2g of photoinitiator (2-hydroxy-2-methyl-1-phenylpropanone, Darocur 1173), the amount of which is 2% of the total weight of the silane coupling agent.

[0028] Add 1.5g of nano-silica, wherein the average particle size of the nano-silica is 20-50nm, and the amount added is 15% of the total weight of the silane coupling agent.

[0029] Acetic acid was added as a catalyst to adjust the pH of the treatment solution to 4.5.

[0030] The above components were dispersed in a water-alcohol mixed solvent to prepare a composite silane treatment solution with a solid content of 6%, and stirred for 30 minutes.

[0031] (3) Impregnation treatment: The polyimide composite fiber layer obtained in step (1) is immersed in the composite silane treatment solution prepared in step (2) for 60 seconds. Then, excess liquid is removed by roller extrusion, and the roll residue rate is controlled to be 75%.

[0032] (4) Ultraviolet light-induced in-situ polymerization: The polyimide composite fiber layer after impregnation in step (3) was irradiated with ultraviolet light with a wavelength of 365nm under nitrogen protection for 90 seconds and with an irradiation intensity of 30mW / cm².

[0033] During this process, the photoinitiator decomposes under ultraviolet light to generate free radicals, which trigger the free radical polymerization reaction of the silane coupling agent containing carbon-carbon double bonds. This forms a polysiloxane crosslinking network in situ on the fiber surface, encapsulating and fixing the mercapto-containing silane coupling agent molecules within it, thus isolating the mercapto groups from contact with air.

[0034] (5) Drying and in-situ condensation reaction: The polyimide composite fiber layer after UV treatment in step (4) is dried at 110°C for 8 minutes to further hydrolyze and condense the hydrolyzable groups in the silane coupling agent to form a Si-O-Si crosslinked structure, and form chemical bonds with the polar groups on the fiber surface.

[0035] (6) Hot pressing and shaping: The dried polyimide composite fiber layer from step (5) was hot-pressed at a temperature of 135°C and a pressure of 0.25 MPa for 60 seconds. During this time, the encapsulated thiol groups formed stable chemical bonds with the fibers and adjacent networks under hot pressing. After cooling, winding, and slitting, a washable composite thermal insulation material for clothing was obtained.

[0036] The resulting composite insulation material is a single-layer polyimide composite fiber layer structure, which is composed of polyimide short fibers and three-dimensional hollow polyester short fibers. The fiber surface is coated with a polysiloxane crosslinking network in situ, and mercaptosilane coupling agent molecules are wrapped and fixed in the polysiloxane network. The fibers are chemically connected through the flexible segments of the polysiloxane network.

[0037] The finished product weighs approximately 118g / m² and has a thickness of 8mm. Example 2

[0038] (1) Preparation of polyimide composite fiber layer: By weight, 75 parts of polyimide staple fiber and 10 parts of three-dimensional hollow polyester staple fiber (both fineness / length 3D / 51mm) were taken. The above fibers were mixed and then opened, carded, and laid into a web, and a single-layer polyimide composite fiber layer was obtained by physical reinforcement.

[0039] The carding process uses a main cylinder speed of 800 rpm, a working roller speed of 60 rpm, and a stripping roller speed of 100 rpm; the web laying adopts a parallel web laying method with one web layer; the reinforcement method is needle punching reinforcement with a needle punching density of 100 needles / cm² and a needle punching depth of 5 mm; the basis weight of the polyimide composite fiber layer is 80 g / m².

[0040] (2) Preparation of composite silane treatment solution: Take 4g of 3-mercaptopropyltriethoxysilane (containing mercaptosilane coupling agent) and 6g of vinyltriethoxysilane (containing carbon-carbon double bond silane coupling agent) and dissolve them in 250mL of methanol and 250mL of deionized water. The weight ratio of the mercaptosilane coupling agent to the carbon-carbon double bond silane coupling agent is 1:0.5.

[0041] Add 0.15g of photoinitiator (1-hydroxycyclohexylphenyl ketone), wherein the amount of photoinitiator added is 0.5% of the total weight of the silane coupling agent.

[0042] 1.2g of nano-silica with an average particle size of 10-30nm was added, and the amount added was 5% of the total weight of the silane coupling agent.

[0043] Acetic acid was added as a catalyst to adjust the pH of the treatment solution to 3.

[0044] The above components were dispersed in a water-alcohol mixed solvent to prepare a composite silane treatment solution with a solid content of 3%, and stirred for 30 minutes.

[0045] (3) Impregnation treatment: The polyimide composite fiber layer obtained in step (1) is immersed in the composite silane treatment solution prepared in step (2) for 30 seconds. Then, excess liquid is removed by roller extrusion, and the roll residue rate is controlled to be 60%.

[0046] (4) Ultraviolet light-induced in-situ polymerization: The polyimide composite fiber layer after impregnation in step (3) was irradiated with ultraviolet light with a wavelength of 320 nm under nitrogen protection for 30 seconds and with an irradiation intensity of 10 mW / cm².

[0047] During this process, the photoinitiator decomposes under ultraviolet light to generate free radicals, which trigger the free radical polymerization reaction of the silane coupling agent containing carbon-carbon double bonds. This forms a polysiloxane crosslinking network in situ on the fiber surface, encapsulating and fixing the mercapto-containing silane coupling agent molecules within it, thus isolating the mercapto groups from contact with air.

[0048] (5) Drying and in-situ condensation reaction: The polyimide composite fiber layer after UV treatment in step (4) is dried at 80°C for 5 minutes to further hydrolyze and condense the hydrolyzable groups in the silane coupling agent to form a Si-O-Si crosslinked structure, and form chemical bonds with the polar groups on the fiber surface.

[0049] (6) Hot pressing and shaping: The polyimide composite fiber layer dried in step (5) was hot-pressed at a temperature of 120°C and a pressure of 0.1 MPa for 30 seconds. At this time, the encapsulated thiol groups formed stable chemical bonds with the fiber and adjacent network under hot pressing.

[0050] After cooling, rolling, and slitting, a washable composite insulation material for clothing is obtained.

[0051] The resulting composite insulation material is a single-layer polyimide composite fiber layer structure, which is composed of polyimide short fibers and three-dimensional hollow polyester short fibers. The fiber surface is coated with a polysiloxane crosslinking network in situ, and mercaptosilane coupling agent molecules are wrapped and fixed in the polysiloxane network. The fibers are chemically connected through the flexible segments of the polysiloxane network.

[0052] The finished product weighs approximately 95g / m² and has a thickness of 6mm. Example 3

[0053] (1) Preparation of polyimide composite fiber layer: By weight, 90 parts of polyimide staple fiber and 25 parts of three-dimensional hollow polyester staple fiber (both fineness / length 3D / 51mm) were taken. The above fibers were mixed and then opened, carded, and laid into a web, and a single-layer polyimide composite fiber layer was obtained by physical reinforcement.

[0054] The carding process uses a main cylinder speed of 1200 rpm, a working roller speed of 120 rpm, and a stripping roller speed of 200 rpm. The web laying adopts a cross-laying method with 3 layers. The reinforcement method is needle punching reinforcement with a needle punching density of 250 needles / cm² and a needle punching depth of 10 mm. The basis weight of the polyimide composite fiber layer is 180 g / m².

[0055] (2) Preparation of composite silane treatment solution: Take 6g of 3-mercaptopropyltrimethoxysilane (containing mercaptosilane coupling agent) and 4g of γ-methacryloyloxypropyltrimethoxysilane (containing carbon-carbon double bond silane coupling agent) and dissolve them in 350mL of ethanol and 250mL of deionized water. The weight ratio of the mercaptosilane coupling agent to the carbon-carbon double bond silane coupling agent is 1:2.

[0056] Add 0.25g of photoinitiator (2-hydroxy-2-methyl-1-phenylpropanone, Darocur 1173), the amount of which is 3% of the total weight of the silane coupling agent.

[0057] Add 2.0g of nano-silica, the average particle size of which is 50-80nm, and the amount added is 25% of the total weight of the silane coupling agent.

[0058] Ammonia was added as a catalyst, and the pH of the treatment solution was adjusted to 10.

[0059] The above components were dispersed in a water-alcohol mixed solvent to prepare a composite silane treatment solution with a solid content of 10%, and stirred for 30 minutes.

[0060] (3) Impregnation treatment: The polyimide composite fiber layer obtained in step (1) is immersed in the composite silane treatment solution prepared in step (2) for 120 seconds. Then, excess liquid is removed by roller extrusion, and the roll residue rate is controlled to be 90%.

[0061] (4) Ultraviolet light-induced in-situ polymerization: The polyimide composite fiber layer after impregnation in step (3) was irradiated with ultraviolet light with a wavelength of 400 nm under nitrogen protection for 180 seconds and with an irradiation intensity of 50 mW / cm².

[0062] During this process, the photoinitiator decomposes under ultraviolet light to generate free radicals, which trigger the free radical polymerization reaction of the silane coupling agent containing carbon-carbon double bonds. This forms a polysiloxane crosslinking network in situ on the fiber surface, encapsulating and fixing the mercapto-containing silane coupling agent molecules within it, thus isolating the mercapto groups from contact with air.

[0063] (5) Drying and in-situ condensation reaction: The polyimide composite fiber layer after UV treatment in step (4) is dried at 120°C for 15 minutes to further hydrolyze and condense the hydrolyzable groups in the silane coupling agent to form a Si-O-Si crosslinked structure, which then forms a chemical bond with the polar groups on the fiber surface.

[0064] (6) Hot pressing and shaping: The polyimide composite fiber layer dried in step (5) was hot-pressed at a temperature of 150°C and a pressure of 0.4 MPa for 120 seconds. At this time, the encapsulated thiol groups formed stable chemical bonds with the fiber and adjacent network under hot pressing.

[0065] After cooling, rolling, and slitting, a washable composite insulation material for clothing is obtained.

[0066] The resulting composite insulation material is a single-layer polyimide composite fiber layer structure, which is composed of polyimide short fibers and three-dimensional hollow polyester short fibers. The fiber surface is coated with a polysiloxane crosslinking network in situ, and mercaptosilane coupling agent molecules are wrapped and fixed in the polysiloxane network. The fibers are chemically connected through the flexible segments of the polysiloxane network.

[0067] The finished product weighs approximately 142g / m² and has a thickness of 10mm.

[0068] Comparative Example 1 The difference between this comparative example and Example 1 is that no silane coupling agent containing carbon-carbon double bonds is added to the composite silane treatment solution, that is, only mercaptosilane coupling agent is added, and ultraviolet irradiation treatment is not performed in step (4). The remaining steps are the same as in Example 1.

[0069] Comparative Example 2 The difference between this comparative example and Example 1 is that: in step (4), no ultraviolet irradiation treatment is performed. Although a mercaptosilane coupling agent and a carbon-carbon double bond silane coupling agent are added at the same time, in-situ polymerization is not triggered. The remaining steps are the same as in Example 1.

[0070] Comparative Example 3 The difference between this comparative example and Example 1 is that no mercaptosilane coupling agent is added to the composite silane treatment solution, while the remaining steps are the same as in Example 1.

[0071] Comparative Example 4 The difference between this comparative example and Example 1 is that the impregnation treatment in step (3) is not performed, that is, the polyimide composite fiber layer is not impregnated with any silane treatment solution, and the remaining steps are the same as in Example 1.

[0072] Comparative Example 5 The difference between this comparative example and Example 1 is that the weight ratio of the mercaptosilane coupling agent to the carbon-carbon double bond silane coupling agent in step (2) is changed to 1:4 (exceeding the range of 1:0.5-1:2 as defined in claim 1 of this invention), and the remaining steps are the same as in Example 1.

[0073] Comparative Example 6 The difference between this comparative example and Example 1 is that: in step (2) when preparing the composite silane treatment solution, no nano-silica is added, the other components and amounts remain unchanged, and the other steps are the same as in Example 1.

[0074] Except for the corresponding parameters, the processes of Examples 2, 3 and Comparative Examples 1-6 are consistent with those of Example 1, and will not be described in detail due to space limitations.

[0075] Experimental Example: Performance Testing The performance of the composite thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-6 was tested, and the results are shown in Table 1.

[0076] 1. Thermal conductivity: The test was conducted in accordance with GB / T10295-2008 "Determination of steady-state thermal resistance and related properties of thermal insulation materials by heat flux meter method". The sample size was 300mm×300mm, the thickness was the original thickness of the sample, the cold plate temperature was 15℃, the hot plate temperature was 35℃, and the heat flux density was recorded after the test stabilized. The thermal conductivity was calculated, and the unit was W / (m·K).

[0077] 2. Air permeability: The test was conducted in accordance with GB / T5453-1997 "Determination of air permeability of textile fabrics". The test pressure drop was 100 Pa, the test area was 20 cm², and 10 different locations were tested for each sample. The average value was taken, and the unit was mm / s.

[0078] 3. Moisture permeability: The test was conducted in accordance with GB / T12704.2-2009 "Textiles - Test Methods for Moisture Permeability of Fabrics - Part 2: Evaporation Method". The positive cup method was adopted, the test temperature was 38℃, the relative humidity was 90%, the test time for the sample was 1 hour, and the unit was g / (m²·24h).

[0079] 4. Softness: A subjective rating method was used, with 10 trained testers conducting a double-blind touch rating of the samples, and the average score was taken. The rating scale was 1-10, with 10 points representing excellent softness (fluffy, smooth, and without any stiffness), and 1 point representing extreme stiffness (hard, almost non-flexible). Intermediate scores corresponded to different degrees of softness. Each sample was independently rated by each tester, and the average of the 10 ratings was taken as the final softness score.

[0080] 5. Thickness Retention Rate: The test was conducted according to GB / T3820-1997 "Determination of Thickness of Textiles and Textile Products". The original thickness of the sample before standard machine washing and the thickness after 30 standard machine washes and hanging to dry were measured. A thickness gauge with a presser foot area of ​​2500 mm² and an applied pressure of 0.5 kPa was used. Five different locations were tested for each sample, and the average value was taken. The thickness retention rate was calculated using the following formula: Thickness retention rate (%) = (average thickness after washing / average thickness before washing) × 100%.

[0081] 6. Thermal Insulation Retention Rate: The original thermal insulation rate of the samples before standard machine washing and the thermal insulation rate after 30 standard machine washes and hanging to dry were tested separately. The test plate temperature was 35℃, the ambient temperature was 20℃, the relative humidity was 65%, the sample size was 300mm×300mm, and 3 samples were tested for each sample, and the average value was taken. The thermal insulation retention rate was calculated according to the following formula: Thermal insulation retention rate (%) = (average thermal insulation rate after washing / average thermal insulation rate before washing) × 100%.

[0082] 7. Storage Stability (30-day storage condition): The sample was laid flat and stored under standard atmospheric conditions (temperature 20±2℃, relative humidity 65±4%) for 30 days, avoiding direct sunlight and any external pressure. After 30 days, the sample was removed and evaluated using a combination of visual observation and tactile testing. The main observations and records were made regarding the presence of fiber adhesion, localized hardening, crusting, discoloration, etc., on the sample surface. The results were comprehensively assessed and recorded as "no adhesion, loose," "slight adhesion," or "adhesive, hardened," etc.

[0083] 8. Peel strength change rate after washing: The test was conducted according to FZ / T80007.1-2023 "Test Method for Peel Strength of Adhesive-backed Garments". The original peel strength of the samples before standard machine washing and the peel strength after 30 standard machine washes and hang drying were tested separately. Sampling was performed along the longitudinal direction (MD), with a sample size of 50mm × 200mm and a peeling speed of 100mm / min. The test result is the peak peel strength. Five samples were tested for each sample, and the average value was taken. The peel strength change rate after washing was calculated using the following formula: Strength change rate after washing (%) = [(average peel strength after washing - average peel strength before washing) / average peel strength before washing] × 100%; A positive result indicates that the peel strength is higher after washing than before washing, while a negative result indicates that the peel strength is lower after washing than before washing. Five samples were tested for each sample, and the average value was taken as the final result, expressed as a percentage.

[0084] 9. Washability (30 standard machine washes): The test was conducted according to GB / T8629-2017 "Test Procedures for Textiles - Household Washing and Drying", using the 4N program (normal washing program) with ECE phosphate-free standard detergent. The washing water temperature was 40±3℃, and the washing time was (45±5) minutes. After washing, the samples were hung to dry. This washing-drying procedure was repeated a total of 30 times. After 30 machine washes, the appearance changes of the samples were observed and recorded, including but not limited to whether the fiber layer showed delamination, peeling, pilling, significant thickness reduction, hardening, etc.

[0085] The test results are shown in Table 1 below: Table 1 sample Thermal conductivity (W / m·K) Air permeability (mm / s) Moisture permeability (g / m²·24h) Softness (points) Thickness retention rate (%) Thermal insulation retention rate (%) 30-day storage status Strength change rate after washing (%) Example 1 0.036 188 6980 8.6 94.1 93.2 Non-sticky, fluffy 8.7 Example 2 0.038 215 7150 8.9 92.5 91 Non-sticky, fluffy 6.5 Example 3 0.035 162 6700 8.3 95 94.1 Non-sticky, fluffy 10.2 Comparative Example 1 0.036 192 7020 7.2 82.5 80.1 Adhesion, hardening -12.3 Comparative Example 2 0.036 190 7000 7.8 83 81.5 slight adhesion -5.2 Comparative Example 3 0.037 185 6900 8.5 85.3 83.6 Non-sticky, fluffy -8.6 Comparative Example 4 0.039 198 7100 8.7 65.8 62.3 Non-sticky, fluffy — Comparative Example 5 0.037 178 6820 8 78.6 76.2 Non-sticky, fluffy -4.3 Comparative Example 6 0.036 205 7120 8.9 89.2 87.5 Non-sticky, fluffy +3.2 Based on the foregoing, Comparative Example 1 only used a combination of polyimide flocculants and mercaptosilane coupling agents. To address the poor bonding strength of the basic fibers, mercaptosilane coupling agents were added, but this resulted in severe adhesion and hardening of the material after 30 days of storage (softness plummeted to 7.2 points). This demonstrates that premature oxidative crosslinking of the mercaptosilane led to premature crosslinking and hardening. In contrast, Example 1 introduced UV-induced in-situ polymerization of a silane coupling agent containing carbon-carbon double bonds, constructing an encapsulation network under UV light induction. After 30 days, the material remained fluffy and soft (8.6 points).

[0086] In Comparative Example 4, the unmodified polyimide composite fiber layer retained only 65.8% of its thickness after machine washing. In Comparative Example 3, only polyimide flakes and a silane coupling agent containing carbon-carbon double bonds were combined and in-situ polymerized under UV light, without the mercaptosilane coupling agent. Although the peel strength decreased by 8.6% after washing, the thickness retention increased to 85.3%. However, when the in-situ polymerized network of the mercaptosilane coupling agent and the silane coupling agent containing carbon-carbon double bonds constituted Example 1, the peel strength after washing not only did not decrease but actually increased by 8.7%, and the thickness retention reached as high as 94.1%. This clearly demonstrates that the flexible polysiloxane network constructed by the silane coupling agent containing carbon-carbon double bonds not only protects the mercaptosilane coupling agent but also synergizes with it, generating stress buffering and network rearrangement during wet and hot washing, achieving a "the more you wash, the stronger it becomes" effect and significantly improving water resistance.

[0087] Although all the ingredients were added in Comparative Example 2, the lack of ultraviolet irradiation to trigger the polymerization reaction prevented the formation of an encapsulation network in situ, resulting in slight adhesion and significantly lower washability than in Example 1.

[0088] Although Comparative Example 5 simultaneously includes polyimide flakes, mercaptosilane coupling agent, silane coupling agent containing carbon-carbon double bonds, and ultraviolet light triggering conditions, the ratio of mercaptosilane coupling agent to silane coupling agent containing carbon-carbon double bonds deviates significantly from the scope defined in this invention. This results in an excessive polysiloxane network hindering the effective bonding of the mercaptosilane coupling agent, making it impossible to achieve the synergistic effect of "the more you wash, the stronger it becomes." This demonstrates that there is a strict synergistic dependency between the various technical features of this invention, and they cannot be simply superimposed or substituted.

[0089] Comparative Example 6 material remained fluffy and soft after 30 days of storage, proving that the UV-induced encapsulation network remained effective and that premature oxidation and adhesion of thiol groups did not occur. However, its thickness retention rate and heat retention rate were significantly lower than those of Example 1, and the strength change rate after washing was only +3.2%, far lower than that of Example 1. Nanoparticles not only enhance the mechanical strength of the polysiloxane network as physical crosslinking points, but also form a micro-rough structure on the fiber surface, increasing the anchoring sites of the silane coupling agent and promoting the tight bonding between the network and the fiber matrix. At the same time, the silanol groups on the surface of nano-silica can participate in the condensation reaction and form covalent bonds with the Si-O-Si network, further enhancing the cohesion and washability of the network. Without nano-silica, although the chemical encapsulation still exists, the mechanical strength and interfacial bonding of the network itself are insufficient, leading to the slippage or breakage of some flexible segments under repeated mechanical rinsing, thus significantly reducing the washability.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention; those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A manufacturing process for a washable composite thermal insulation material for clothing, characterized by the following steps: include: (1) Take 75-90 parts of polyimide short fiber and 10-25 parts of three-dimensional hollow polyester short fiber by weight; mix the above fibers and then open, comb, and lay the web, and then obtain a single layer of polyimide composite fiber layer by physical reinforcement. (2) Mix mercaptosilane coupling agent and carbon-carbon double bond silane coupling agent at a weight ratio of 1:0.5-1:2, add photoinitiator, catalyst and nano silica, disperse in water-alcohol mixed solvent, and prepare composite silane treatment solution; (3) The polyimide composite fiber layer obtained in step (1) is immersed in the composite silane treatment solution with a solid content of 3-10% prepared in step (2); (4) The polyimide composite fiber layer after impregnation in step (3) is irradiated with ultraviolet light with a wavelength of 320-400nm under the protection of inert gas; (5) Dry the polyimide composite fiber layer after UV treatment in step (4) at 80-120℃ for 5-15 minutes; (6) The polyimide composite fiber layer dried in step (5) is hot-pressed and shaped, cooled, rolled up and cut to obtain a washable composite thermal insulation material for clothing.

2. The production process according to claim 1, characterized in that, In step (2), the mercaptosilane coupling agent is at least one of 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.

3. The production process according to claim 1, characterized in that, In step (2), the carbon-carbon double bond-containing silane coupling agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

4. The production process according to claim 1, characterized in that, In step (2), the photoinitiator is 2-hydroxy-2-methyl-1-phenylpropanone or 1-hydroxycyclohexylphenyl ketone, and the amount added is 0.5-3% of the total weight of the silane coupling agent.

5. The production process according to claim 1, characterized in that, In step (2), the average particle size of the nano-silica is 10-80 nm, and the amount added is 5-25% of the total weight of the silane coupling agent.

6. The production process according to claim 1, characterized in that, In step (2), the weight ratio of the mercaptosilane coupling agent to the carbon-carbon double bond silane coupling agent is 1:0.8-1:1.

5.

7. The production process according to claim 1, characterized in that, In step (4), the wavelength of the ultraviolet light is 365nm, the irradiation time is 30-180 seconds, and the irradiation intensity is 10-50mW / cm².

8. The production process according to claim 1, characterized in that, In step (1), the basis weight of the polyimide composite fiber layer is 80-180 g / m²; the reinforcement method is needle punching reinforcement, the needle punching density is 100-250 needles / cm², and the needle punching depth is 5-10 mm.

9. The production process according to claim 1, characterized in that, In step (6), the hot pressing and shaping is performed using a flat hot press or a hot roller pressing device.

10. A washable composite thermal insulation material for clothing, characterized in that, It is prepared using the production process described in any one of claims 1-9.