Water-permeable and air-permeable sponge and preparation method thereof

Abstract

The invention belongs to the field of high polymer materials, and provides a water-permeable and air-permeable sponge and a preparation method thereof. According to the preparation method, collaborative design of a cross-linked polydimethylsiloxane continuous phase and a directional through-hole network is adopted, the through-hole network with the aperture ratio of 85-92% and the orientation index not lower than 0.60 is formed through dissolution of a directional soluble particle template, and silane coupling modified cellulose nanocrystals with the mass fraction of 0.50-2.00% are introduced to enhance the network, so that the specific surface area of the cellulose nanocrystals is increased, and the specific surface area of the cellulose nanocrystals is increased; meanwhile, 0.10-1.00 wt% of hydrophilic functional silane is covalently fixed, so that surface hydrophilic modification is realized, and double-medium high-flux water and air permeability of which the air permeability is not lower than 400 L.m.s and the aperture gradient is 150-250 [mu] m on the near skin side to 400-600 [mu] m on the far skin side is realized; the problems of coupling contradiction between high aperture ratio and mechanical bearing resilience attenuation and between directional through hole network circulation stability and double-medium high flux and low VOC are solved, and the composite material has wide application value in the fields of lactation and sports underwear, masks, underpants, eyeshades, shoes, mattresses and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high polymer materials, in particular to a water-permeable and air-permeable sponge and a preparation method thereof. BACKGROUND

[0002] With the in-depth application of ergonomic design concepts in textiles and personal protective products, intimate products such as nursing and sports underwear, masks, briefs, and eye masks have put forward strict comprehensive performance requirements for supporting materials. Such products need to be in contact with the skin for a long time, and the use scenarios involve complex working conditions such as sweating during exercise, breast secretion, high temperature and high humidity environment, etc. The supporting material not only needs to have excellent mechanical bearing and rebounding performance to provide effective support and comfortable experience, but also needs to realize high-efficiency water-permeable and air-permeable capacity at the same time to ensure that sweat and liquid are quickly drained and air is freely circulated, avoiding stuffiness and microbial breeding. Although traditional silicone sponge materials have good elasticity and biocompatibility, their inherent hydrophobicity leads to liquid retention, and low air permeability causes heat and moisture accumulation, which is difficult to meet the comfort requirements of long-term wearing. The development of new silicone sponge materials with high water-permeable and air-permeable capacity, excellent mechanical properties, and low VOC release is of great significance for improving the wearing experience of intimate textiles and expanding the application range of silicone materials in the field of personal protection and health. The performance optimization of such materials not only concerns the market competitiveness of products, but also directly affects the health and comfort of users, so it has become a research hotspot in the fields of material science and textile engineering.

[0003] At present, the development of water-permeable and air-permeable silicone rubber sponge faces multiple technical bottlenecks and essential contradictions. On the one hand, although increasing the open porosity can significantly improve the air permeability, the high open porosity leads to the weakening of the continuity of the silicone rubber network, and the hole wall is prone to collapse, the permanent deformation increases and the bearing capacity decays in repeated compression-rebound cycles, and the coupling contradiction between mechanical properties and air permeability is prominent. On the other hand, the inherent hydrophobicity of silicone rubber makes it difficult to achieve rapid water permeation with high open structure, and the traditional surface hydrophilic modification methods such as plasma treatment and surface coating have the problems of poor durability of the modified layer and weak adhesion with the matrix, which are easy to fall off and fail under the action of washing and mechanical friction, and cannot meet the long-term use requirements. For example, the Chinese patent with publication number CN112940335A discloses a preparation method of a porous silicone rubber material, but the random foaming method used leads to disordered pore orientation, wide pore size distribution and high tortuosity of the air permeation path, which cannot realize directional high flux transmission, and the problem of durability of hydrophilic modification is not solved. In addition, in order to enhance the mechanical properties of the high open porosity silicone rubber network, researchers try to introduce nano-reinforcing fillers, but the addition of rigid nanoparticles significantly increases the viscosity of the rubber, which is difficult to fully penetrate into the pre-formed pore template in the low-pressure infiltration process, leading to uneven filling, increasing the defects of the pore structure, and even deteriorating the material performance. At the same time, the interface compatibility between the nano-filler and the silicone rubber matrix is poor, which is easy to form stress concentration points at the interface, reducing the fatigue resistance of the material. More importantly, how to realize the synergistic optimization of hydrophilic modification, nano-reinforcement and low viscosity processing window while ensuring the high open porosity and pore size gradient structure, construct a directional through-hole network to ensure the high flux transmission of the double medium, and meet the low VOC release and biological safety requirements in the A class standard of textiles, is still the core problem to be broken through in this field. SUMMARY

[0004] The purpose of the present application is to provide a water-permeable and air-permeable sponge and a preparation method thereof, which solves the coupling contradiction between high open porosity and mechanical bearing and rebound decay, directional through-hole network cycle stability and high flux and low VOC of double medium of the current water-permeable and air-permeable silicone rubber sponge.

[0005] The present application adopts the synergistic design idea of cross-linked polydimethylsiloxane continuous phase and directional through-hole network, constructs a through-hole structure with pore size gradient and orientation control through directional soluble particle template technology, introduces cellulose nanocrystals modified by silane coupling as a flexible nano-reinforcing phase, and realizes the persistent hydrophilic modification of the surface and the bulk phase by chemical covalent fixation of hydrophilic functional silane and silicone rubber network, which realizes the significant improvement of mechanical bearing capacity and rebound performance under the condition of high open porosity, the cycle stability guarantee of directional through-hole network, the high flux rapid transmission of air and liquid double medium, and the synergistic optimization of low contact angle hydrophilicity and low VOC release, which breaks through the restriction bottleneck between water permeability and air permeability and mechanical properties of traditional silicone rubber sponge.

[0006] To achieve the above object, the present application provides the following technical solution: a water-permeable and air-permeable sponge, comprising a cross-linked polydimethylsiloxane continuous phase and a network of through-holes, comprising the following features: a. The through-holes are formed by dissolving a directional soluble particle template, the opening rate is 85-92%, the through-hole orientation index is not less than 0.60, the thickness is 2-8 mm, and the pore size gradient is 150-250 μm for the average pore size near the skin side and 400-600 μm for the average pore size far from the skin side; b. The continuous phase is a silicone rubber network formed by cross-linking vinyl-terminated polydimethylsiloxane and hydrogen-containing siloxane, wherein the hydrogen-containing siloxane is dimethylmethylhydrogen siloxane or methylhydrogen siloxane-dimethylsiloxane copolymer; and the cross-linking is a platinum-catalyzed silicon-hydrogen addition reaction; c. The sponge contains silane-coupling modified cellulose nanocrystals, and the mass fraction is 0.50-2.00%; d. The sponge surface or body phase contains a covalently fixed layer of hydrophilic functional silane, the hydrophilic functional silane is selected from 3-aminopropyl triethoxysilane and / or 3-glycidoxypropyl trimethoxysilane, and the total mass fraction of the hydrophilic functional silane in the finished sponge is 0.10-1.00%; e. The air permeability of the sponge is not less than 400 L·m⁻²·s⁻¹ according to GB / T 5453-1997, measured at a pressure difference of 100 Pa.

[0007] Further, the silane-coupling modified cellulose nanocrystals are prepared by the following steps: A1. Raw materials: 100 parts by mass of microcrystalline cellulose, 60-65% by mass of sulfuric acid, sodium hydroxide, and deionized water; A2. Acidolysis: at 40-50°C, the microcrystalline cellulose is treated with 60-65% by mass of sulfuric acid at a mass ratio of acid solution to microcrystalline cellulose of 8:1-12:1 for 30-90 minutes to obtain a cellulose nanocrystal dispersion; A3. Neutralization and washing: after neutralization with a sodium hydroxide solution to pH 6.0-8.0, the dispersion is washed multiple times with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 2-5%; A4. Coupling: the dispersion is adjusted to pH 4.5-5.5, 3-(methacryloyloxy)propyl trimethoxysilane or 3-glycidoxypropyl trimethoxysilane is added at a silane to cellulose nanocrystal mass ratio of 2-10% at 25-35°C, and stirring is performed for 1-3 hours to promote alkoxy hydrolysis-condensation / ring-opening reaction, followed by washing and drying to obtain the silane-coupling modified cellulose nanocrystal powder.

[0008] Further, the directional soluble particle template is prepared by the following steps: C1. Raw materials: sodium chloride or sucrose; C2. Classification: two grades of particles were prepared, one with an average particle size of 150-250 μm and the other with an average particle size of 400-600 μm; C3. Directional paving and pre-pressing: small-particle-size layers and large-particle-size layers were sequentially paved in the order of near-skin side to far-skin side, and the mass ratio of near-skin side to far-skin side particles was 1.0-2.0. The whole was uniaxially pre-pressed to form a directional dissolvable particle template with a thickness of 2-8 mm. The uniaxial pre-pressing direction of the template was parallel to the long axis orientation direction of the through holes.

[0009] Further, the covalent fixation of the hydrophilic functional silane was achieved by mixing 0.10–1.00 wt.% of 3-aminopropyltriethoxysilane and / or 3-glycidoxypropyltrimethoxysilane into the composite compound, and during the curing process, the alkoxyl groups were hydrolyzed and condensed with the surface silanols of the cellulose nanocrystals to form a covalent bond.

[0010] Further, the thickness of the near-skin side layer accounted for 30-60% of the total thickness, and the average pore size was 150-250 μm. The average pore size of the far-skin side layer was 400-600 μm.

[0011] Further, the mass ratio of the hydrophilic functional silane to the cellulose nanocrystals modified by silane coupling was 0.20-1.00.

[0012] As an idea of the present application, the present application adopts the design of a continuous phase of cross-linked polydimethylsiloxane and a directional through-hole network, which is mainly used to realize the synergistic optimization of water-permeable and air-permeable performance, mechanical bearing capacity, and hydrophilic wetting performance. The directional dissolvable particle template technology forms a through-hole network with a pore size gradient and a high orientation index after dissolution by controlling particle size classification and directional paving. The pore size gradient design enables the small-pore-size layer on the near-skin side to achieve soft fitting to the skin and rapid absorption of liquid, and the large-pore-size layer on the far-skin side provides a high-throughput air flow passage and a rapid liquid discharge passage. The orientation control ensures that the pores are through in the thickness direction, significantly reducing the tortuosity of the air and water permeation path. Vinyl-terminated polydimethylsiloxane and dimethylmethylhydrogen siloxane form a three-dimensional silicone rubber network through platinum-catalyzed addition cross-linking reaction, which gives the material excellent elastic recovery and fatigue resistance, and still maintains sufficient mechanical strength under the condition of high porosity. The cellulose nanocrystals modified by silane coupling serve as a flexible nanoreinforcing phase, and the surface silane coupling layer forms a chemical bond with the silicone rubber matrix, significantly improving the interfacial bonding strength. The high aspect ratio and nanoscale dispersion of the cellulose nanocrystals effectively enhance the modulus and tear resistance of the network without significantly increasing the viscosity of the compound. The hydrophilic functional silane realizes persistent hydrophilic modification of the surface and bulk phase through covalent fixation with the silicone rubber network, giving the sponge a low contact angle characteristic, promoting the rapid spreading and transmission of liquid, and solving the problem of liquid retention caused by the inherent hydrophobicity of silicone rubber.

[0013] The application also discloses a preparation method of the water-permeable and air-permeable sponge, comprising the following steps: S1. preparing a directional soluble particle template; S2. preparing a composite sizing material: 100 parts by mass of vinyl-terminated polydimethylsiloxane; a hydrogen-containing siloxane crosslinking agent is added according to an equivalent ratio of Si-H / C=C of 0.80-1.20; 0.50-2.00 parts by mass of cellulose nanocrystals modified by silane coupling; 0.10-1.00 parts by mass of a hydrophilic functional silane; and 5-50 ppm of a platinum complex catalyst in terms of platinum content, wherein the platinum complex catalyst is platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane; and the mixture is defoamed under low pressure conditions; S3. impregnating the composite sizing material into the directional soluble particle template under a low pressure environment of 10-50 kPa until the template is filled; S4. curing the template under a condition of 80-120 ℃ for 0.50-2.00 hours to obtain a composite template body; S5. dissolving the directional soluble particle template with deionized water and drying to obtain the water-permeable and air-permeable sponge.

[0014] Further, the impregnation time of S3 is 10-20 minutes.

[0015] Further, the directional soluble particle template is dissolved by using multi-stage countercurrent washing, and the washing liquid volume is 10-30 times the volume of the template.

[0016] The application also discloses water-permeable and air-permeable sponge in the application of water permeability and air permeability and support resilience in mammal and sports underwear, masks, briefs and eye masks.

[0017] Further, when the water-permeable and air-permeable sponge is used as a chest cup gasket, the single-piece thickness is 2-6 mm, and the edge thickness gradient ratio is 1.5-3.0.

[0018] Further, according to GB / T 2912.1-2009, the formaldehyde content of the water-permeable and air-permeable sponge is ≤20 mg / kg; according to GB / T 17592-2024 (the detection limit of the method is 5 mg / kg), no decomposable carcinogenic aromatic amine dye is detected; according to GB / T 7573-2009, the pH of the extraction liquid is 4.0-7.5; according to GB 18401-2010, no peculiar smell is detected; and the water-permeable and air-permeable sponge meets the A-class requirements of GB 18401-2010.

[0019] The water fastness (GB / T 5713-2013) is ≥4 levels; the perspiration fastness (acidic and alkaline, GB / T 3922-2013) is ≥4 levels; and the dry rubbing fastness (GB / T 3920-2008) is ≥4 levels.

[0020] The cellulose nanocrystals modified by silane coupling and the hydrophilic functional silane play a complementary and synergistic role in the present application, which solves the problems of insufficient mechanical strength and hydrophobicity of high open-cell rate silicone rubber sponge. The cellulose nanocrystals, as a flexible nano-reinforcing phase, mainly function to improve the modulus, tear resistance and fatigue resistance of the silicone rubber network. Through surface silane coupling modification, the hydroxyl groups on the surface of the cellulose nanocrystals react with the silane coupling agent to form a chemical bonding layer. When 3-(methacryloyloxy)propyltrimethoxysilane (MPS) is used, the methacryloyl C=C can undergo addition with Si-H under platinum catalysis, so that the cellulose nanocrystals are chemically anchored to the silicone rubber network through the coupling layer. When 3-glycidoxypropyltrimethoxysilane (GPTMS) is used, it mainly forms a bond with the cellulose surface hydroxyl group through ring opening / condensation, and does not participate in Si-H / olefin addition. The interfacial bonding is changed from physical adsorption to chemical bonding, which significantly improves the stress transfer efficiency. The high aspect ratio and nanoscale dispersion of the cellulose nanocrystals in the silicone rubber network form physical crosslinking points, effectively dispersing stress, inhibiting crack propagation and reducing permanent deformation in the compression-rebound cycle. The hydrophilic functional silane focuses on improving the surface wettability and water permeability of the material. Its molecular structure contains both alkoxy or silicon hydrogen groups that can react with the silicone rubber network and hydrophilic amino or epoxy groups. During the crosslinking process, the reactive groups of the hydrophilic functional silane participate in the construction of the crosslinked network, and the hydrophilic groups spontaneously migrate to the surface and inner surface of the sponge pore wall to form a hydrophilic interface layer. The synergistic effect of the two is that the cellulose nanocrystals enhance the mechanical properties of the network, and at the same time, the residual part of the hydroxyl groups on the surface of the cellulose nanocrystals form hydrogen bond interactions with the amino or epoxy groups of the hydrophilic functional silane, promoting the uniform distribution of the hydrophilic functional silane on the inner surface of the pore wall and enhancing the uniformity of the hydrophilic modification layer. The addition of the hydrophilic functional silane reduces the surface tension of the rubber compound, improves the wettability of the rubber compound to the oriented template pores, and cooperates with the low-pressure infiltration process to improve the uniformity of the dispersion of the cellulose nanocrystals in the pore structure, avoiding stress concentration caused by aggregation.

[0021] Beneficial technical effects 1. Directional through-hole network realizes high flux transmission of double medium: The through-hole network constructed by the directional soluble particle template technology has a high open-cell rate of 85-92% and an orientation index of not less than 0.60. The pore size gradient design ensures that the pores are through along the thickness direction, significantly reducing the tortuosity of the air and water permeation path. The air permeability reaches not less than 400 L·m⁻²·s⁻¹, realizing directional and efficient transmission of air and liquid double medium, which can quickly discharge sweat and heat in the mammal and sports scenarios, and significantly improves the wearing comfort; 2. Synergistic effect of high porosity and mechanical properties by cellulose nanocrystal reinforcement: Cellulose nanocrystal modified by silane coupling as flexible nano-reinforcement, the silane coupling layer on its surface forms chemical bonding with the silicone rubber network, the interfacial bonding strength is high, the nano-scale dispersion and high aspect ratio effectively enhance the modulus and tear resistance of the network without significantly increasing the viscosity of the compound, and the excellent mechanical bearing capacity and resilience can be maintained under high porosity conditions, the compression permanent deformation is significantly reduced, the cycle stability is improved, and the inherent contradiction between high porosity and mechanical properties is broken through; 3. Covalent fixation of hydrophilic modification to achieve long-lasting hydrophilic performance: hydrophilic functional silane is hydrolyzed and condensed with alkoxyl group during curing and is condensed with silanol on the surface of the pore wall / cellulose nanocrystal to form a covalent hydrophilic layer; if an olefin functional hydrophilic silane is used, it can be further grafted to the network through Si-H / olefin addition, the hydrophilic groups are distributed on the surface of the sponge and the inner surface of the pore wall, the water contact angle is reduced from the inherent >100° of silicone rubber to <30°, realizing rapid wetting and capillary transport, and the covalent fixation ensures the durability of the hydrophilic performance, the hydrophilic performance retention rate is >80% after repeated water washing and mechanical rubbing, solving the problem of easy failure of traditional surface modification methods; 4. Low-pressure infiltration process to achieve uniform filling and structural integrity: The preparation method of low-pressure infiltration combined with directional template dissolution, uses negative pressure to drive the composite compound to fill into the template pores, effectively reduces the residual bubbles, promotes the complete wetting of the compound to the template pores, the infiltration uniformity is high, the pore structure defect is less, the continuity of the silicone rubber network after curing is good, the pore wall thickness is uniform, ensuring the mechanical consistency of the sponge and the stability of the air permeability and water permeability performance; 5. Low VOC and biological safety meet A class textile standards: The silicone rubber system and cellulose nanocrystal used in the present application are both low VOC releasing materials, platinum catalytic addition crosslinking reaction has no byproduct generation, multi-stage countercurrent washing ensures the complete removal of the residual template, the formaldehyde content of the final product is ≤20 mg / kg, the decomposable carcinogenic aromatic amine dye is not detected, the extraction liquid pH is 4.0-7.5, there is no odor, the water resistance, perspiration resistance, and dry rubbing fastness are all ≥4 levels, meeting the strict requirements of GB 18401-2010 A class textiles. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The influence of porosity on air permeability and compression permanent deformation rate; Figure 2 The influence of cellulose nanocrystal mass fraction on tensile strength and elongation at break; Figure 3 The influence of hydrophilic functional silane mass fraction on contact angle and water vapor transmission rate; Figure 4 The influence of curing temperature on tensile strength and compression permanent deformation rate; Figure 5 Pore size distribution of the sponge of Example 1 of the present application; Figure 6 FTIR transmission spectrum of the cellulose nanocrystals of the present application modified by silane coupling (3-methacryloxypropyltrimethoxysilane) unmodified cellulose nanocrystals; Figure 7 Sponge morphology of the near skin side of Example 1 of the present application; Figure 8 Sponge morphology of the far skin side of Example 1 of the present application. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.

[0024] Example 1 The present embodiment provides a water-permeable and air-permeable sponge, which comprises a continuous phase of crosslinked polydimethylsiloxane and a network of through-holes. The through-holes of the present embodiment are formed by dissolution of a directional soluble particle template, the open hole rate is 88.5%, the orientation index of the through-holes is 0.70, the thickness is 5 mm, and the pore size gradient is that the average pore size of the near skin side is 200 μm and the average pore size of the far skin side is 500 μm. The continuous phase of the present embodiment is a silicone rubber network obtained by crosslinking of vinyl-terminated polydimethylsiloxane and dimethylmethylhydrogen siloxane, and the crosslinking reaction of the present embodiment is promoted by a platinum complex catalyst. The sponge of the present embodiment contains cellulose nanocrystals modified by silane coupling, and the mass fraction is 1.25%. The sponge of the present embodiment contains a covalently immobilized layer of hydrophilic functional silane on the surface or in the bulk phase, and the hydrophilic functional silane of the present embodiment is 3-aminopropyltriethoxysilane, and the total mass fraction is 0.55%. The air permeability of the sponge of the present embodiment is determined according to GB / T 5453-1997 at a pressure difference of 100 Pa, and is 450 L·m⁻²·s⁻¹.

[0025] The cellulose nanocrystals modified by silane coupling of the present embodiment are prepared by the following steps: the raw materials are microcrystalline cellulose 100 parts by mass, sulfuric acid with a mass fraction of 62.5%, sodium hydroxide, and deionized water. The acidolysis step is carried out at 45°C for 60 minutes by treating the microcrystalline cellulose with sulfuric acid with a mass fraction of 62.5% at a mass ratio of acid solution to microcrystalline cellulose of 10:1 to obtain a cellulose nanocrystal dispersion. The neutralization and washing step is neutralized to pH 7.0 with sodium hydroxide solution and washed with deionized water multiple times to obtain a cellulose nanocrystal dispersion with a solid content of 3.5%. In the coupling step, 3-methacryloxypropyltrimethoxysilane is added to the dispersion of the present embodiment, the mass ratio of silane to cellulose nanocrystals of the present embodiment is 6%, and the stirring reaction is carried out for 2 hours, followed by washing and drying to obtain the cellulose nanocrystals modified by silane coupling of the present embodiment.

[0026] The oriented dissolvable granular template of the present example was prepared by the following steps: the raw material was sodium chloride. Two grades of granules were prepared by the grading step, one with an average particle size of 200 μm and the other with an average particle size of 500 μm. The oriented laying and pre-pressing step laid the small particle size layer and the large particle size layer in the order of the near-skin side to the far-skin side, with a mass ratio of the near-skin side to the far-skin side of 1.5, and the whole was uniaxially pre-pressed into a 5 mm thick oriented dissolvable granular template under a pressure of 12.5 MPa. The uniaxial pre-pressing direction of the template was parallel to the long axis orientation direction of the through holes of the present example.

[0027] The covalent fixation of the hydrophilic functional silane in the present example was achieved by mixing 0.55 wt% of 3-aminopropyl triethoxysilane into the siloxane-based composite prepolymer system and fixing it to the pore wall / cellulose nanocrystal surface through alkoxy hydrolysis-condensation during the curing process. In the present example, the thickness of the near-skin side layer accounted for 50% of the total thickness, the average pore size of the near-skin side layer was 200 μm, and the average pore size of the far-skin side layer was 500 μm. In the present example, the mass ratio of the hydrophilic functional silane to the cellulose nanocrystal modified by silane coupling was 0.44.

[0028] The preparation method of the water-permeable and air-permeable sponge of the present example comprises the following steps: S1. preparing an oriented dissolvable granular template; S2. preparing a composite sizing material, taking 100 parts by mass of a vinyl-terminated polydimethylsiloxane, a hydrogen-containing siloxane crosslinking agent of dimethylmethylhydrogen siloxane, which was added in an Si-H / C=C equivalent ratio of 1.00, 1.25 parts by mass of cellulose nanocrystal modified by silane coupling, 0.55 parts by mass of hydrophilic functional silane, and 27.5 ppm of platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane as a platinum complex catalyst in terms of platinum content, and then defoaming under low pressure after mixing; S3. impregnating the composite sizing material of the present example into the oriented dissolvable granular template of the present example under a low pressure of 30 kPa until it is full, with an impregnation time of 15 minutes; S4. curing at 100°C for 1.25 hours to obtain a composite template body; S5. dissolving the oriented dissolvable granular template with deionized water and drying to obtain a water-permeable and air-permeable sponge. The dissolution of the oriented dissolvable granular template used a multi-stage countercurrent washing process, with a washing liquid volume of 20 times the volume of the template.

[0029] The water-permeable and air-permeable sponge of the present embodiment is used for water-permeable and air-permeable and supporting and rebounding applications in nursing and sports underwear, masks, briefs, eye masks, clothing, shoes, and mattresses. When used as a bra cup liner, the water-permeable and air-permeable sponge of the present embodiment has a single-piece thickness of 5 mm and an edge thickness gradient ratio of 2.0. The formaldehyde content of the present embodiment is 8 mg / kg as determined according to GB / T 2912.1-2009, no decomposable carcinogenic aromatic amine dyes are detected as determined according to GB / T 17592-2024, the pH of the extract is 6.5 as determined according to GB / T 7573-2009, no odor is determined according to GB 18401-2010, and it meets the A-class requirements of GB 18401-2010. The water color fastness is 4-5 grade, the sweat stain color fastness (acidic and alkaline) is 4-5 grade, and the dry rubbing color fastness is 4-5 grade.

[0030] Features of Example 1: The present embodiment uses moderate parameter configuration, with all parameters selected in the middle range of the range, ensuring process stability and product repeatability. The opening rate of 88.5% provides good air permeability, and the air permeability of 450 L·m⁻²·s⁻¹ meets the high air permeability requirement. The moderate cellulose nanocrystal content of 1.25% ensures the balance of mechanical strength and softness, and the crosslinking reaction with a stoichiometric ratio of 1.00 ensures the integrity and uniformity of the network structure. The through-hole orientation index of 0.70 reflects good directional air permeability effect. The present embodiment uses sodium chloride as a template material, which has high dissolution efficiency and is environmentally friendly. The formaldehyde content is only 8 mg / kg, which is much lower than the limit of 20 mg / kg, the pH of the extract is 6.5, which is in the moderate position of the range of 4.0-7.5, and all color fastnesses reach the excellent level of 4-5 grade. The thickness of 5 mm and the edge gradient ratio of 2.0 are particularly suitable for use as a bra cup liner, which can provide moderate support while maintaining good air permeability and comfort. The process parameter combination of the present embodiment is mature and reliable, suitable for industrial batch production, especially suitable for daily wear nursing underwear, sports bras and other close-fitting clothes that need to be worn for a long time, as well as daily protective masks and other application scenarios that require high air permeability and comfort.

[0031] Example 2 The embodiment provides a water-permeable and air-permeable sponge, which comprises a crosslinked polydimethylsiloxane continuous phase and a network of through-holes. The through-holes of the embodiment are formed by dissolution of a directional soluble particle template, the opening rate is 91%, the orientation index of the through-holes is 0.75, the thickness is 3 mm, and the pore size gradient is that the average pore size on the near-dermal side is 180 μm and the average pore size on the far-dermal side is 550 μm. The continuous phase of the embodiment is a silicone rubber network obtained by crosslinking of vinyl-terminated polydimethylsiloxane and dimethylmethylhydrogen siloxane, and the crosslinking reaction of the embodiment is promoted by a platinum complex catalyst. The sponge of the embodiment contains cellulose nanocrystals modified by silane coupling, and the mass fraction is 0.80%. The sponge of the embodiment contains a covalently immobilized layer of hydrophilic functional silane on the surface or in the bulk phase, and the hydrophilic functional silane of the embodiment is 3-glycidyloxypropyltrimethoxysilane, and the total mass fraction is 0.75%. The air permeability of the sponge of the embodiment is 520 L·m⁻²·s⁻¹, which is determined according to GB / T 5453-1997 under a pressure difference of 100 Pa.

[0032] The cellulose nanocrystals modified by silane coupling of the embodiment are prepared by the following steps: the raw materials are microcrystalline cellulose 100 parts by mass, sulfuric acid with a mass fraction of 60%, sodium hydroxide, and deionized water. The acidolysis step is carried out at 42°C for 40 minutes by treating the microcrystalline cellulose with sulfuric acid with a mass fraction of 60% at a mass ratio of acid solution to microcrystalline cellulose of 8:1 to obtain a cellulose nanocrystal dispersion. The neutralization and washing step is carried out by neutralizing with a sodium hydroxide solution to pH 6.5 and then washing with deionized water multiple times to obtain a cellulose nanocrystal dispersion with a solid content of 2.5%. In the coupling step, 3-glycidyloxypropyltrimethoxysilane is added to the dispersion of the embodiment, the mass ratio of silane to cellulose nanocrystals of the embodiment is 3%, and the stirring reaction is carried out for 1.2 hours, followed by washing and drying to obtain the cellulose nanocrystals modified by silane coupling of the embodiment.

[0033] The directional soluble particle template of the embodiment is prepared by the following steps: the raw material is sucrose. The grading step prepares two grades of particles, one with an average particle size of 180 μm and the other with an average particle size of 550 μm. The directional paving and pre-pressing step sequentially paves the small particle size layer and the large particle size layer in the order of the near-dermal side to the far-dermal side, and the mass ratio of the near-dermal side to the far-dermal side is 1.8. The whole is uniaxially pre-pressed at 8 MPa to form a 3 mm thick directional soluble particle template, and the uniaxial pre-pressing direction of the template is parallel to the long axis orientation direction of the through-holes of the embodiment.

[0034] The covalent fixation of the hydrophilic functional silane of the present example is achieved by mixing 0.75 wt% of 3-glycidoxypropyltrimethoxysilane into the silicone-based composite prepolymer system and hydrolysis-condensation fixation on the pore wall / cellulose nanocrystal surface during the curing process. The near-skin side layer thickness of the present example accounts for 55% of the total thickness, and the average pore diameter is 180 μm, and the average pore diameter of the far-skin side layer is 550 μm. The mass ratio of the hydrophilic functional silane to the cellulose nanocrystal modified by silane coupling in the present example is 0.94.

[0035] The preparation method of the water-permeable and air-permeable sponge of the present example includes the following steps: S1. preparing a directional soluble particle template; S2. preparing a composite sizing material, taking 100 parts by mass of a vinyl-terminated polydimethylsiloxane, a hydrogen-containing siloxane crosslinking agent of dimethylmethylhydrogen siloxane, which is added according to a Si-H / C=C equivalent ratio of 0.90, 0.80 parts by mass of cellulose nanocrystal modified by silane coupling, 0.75 parts by mass of a hydrophilic functional silane, and 10 ppm of platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane as a platinum complex catalyst, and then mixing and defoaming under low pressure; S3. impregnating the composite sizing material of the present example into the directional soluble particle template of the present example under a low pressure environment of 15 kPa until it is full, and the impregnation time is 12 minutes; S4. curing at 90°C for 1.50 hours to obtain a composite template body; S5. dissolving the directional soluble particle template with deionized water and drying to obtain a water-permeable and air-permeable sponge, and the directional soluble particle template is dissolved by multi-stage countercurrent washing, and the washing liquid volume is 15 times the volume of the template.

[0036] The water-permeable and air-permeable sponge of the present example is applied to water-permeable and air-permeable and supporting and rebounding applications in mammal and sports underwear, masks, briefs, eye masks, clothing, shoes, and mattresses. When the water-permeable and air-permeable sponge of the present example is used as a chest cup liner, the single-piece thickness is 3 mm, and the edge thickness gradient ratio is 1.8. The formaldehyde content of the present example is 5 mg / kg as determined according to GB / T 2912.1-2009, no decomposable carcinogenic aromatic amine dye is detected as determined according to GB / T 17592-2024, the pH of the extract is 6.0 as determined according to GB / T 7573-2009, no odor is determined according to GB 18401-2010, and it meets the A-class requirements of GB 18401-2010. The water color fastness is 4-5 grade, the sweat stain color fastness (acidic and alkaline) is 5 grade, and the dry rubbing color fastness is 5 grade.

[0037] Features of Example 2: This example is biased towards high air permeability optimization, with an open porosity of 91% close to the upper limit region, combined with a relatively thin 3mm thickness design, achieving excellent air and moisture permeability, with an air permeability of 520 L·m⁻²·s⁻¹ being the highest among the four examples. The through-hole orientation index of 0.75 exhibits a more optimal directional air permeation effect. The lower content of cellulose nanocrystals of 0.80% and the appropriate surplus of Si-H equivalent ratio of 0.90 make the sponge have better softness and skin comfort. The higher content of hydrophilic functional silane of 0.75% significantly improves the moisture absorption and perspiration capacity, and the mass ratio of hydrophilic silane to cellulose nanocrystals of 0.94 close to the upper limit enhances the surface hydrophilicity. This example uses sucrose as the template material, and the dissolution process is more gentle, which is suitable for applications with high purity requirements. The lower pre-pressing pressure of 8 MPa maintains a relatively loose structure, which is beneficial to air permeability. The lower curing temperature of 90°C and the appropriate extension of the curing time of 1.50 hours are beneficial to the formation of a more uniform cross-linked network. The formaldehyde content of only 5 mg / kg is the lowest among the four examples, and the pH of the extraction liquid is 6.0, and the color fastness reaches the excellent level of 4-5 grade to 5 grade. This example is particularly suitable for high-intensity sports bras, summer thin nursing underwear, sports masks and other application scenarios that require extreme air permeability and rapid moisture transfer, and is also suitable for use in eye masks and other products that require lightweight and breathable. The ultra-thin design of 3mm and the edge gradient ratio of 1.8 make it particularly suitable for making seamless underwear and lightweight chest cups.

[0038] Example 3 This example provides a water-permeable and air-permeable sponge, comprising a cross-linked polydimethylsiloxane continuous phase and a through-hole network. The through-holes of this example are formed by directional dissolving of the template of soluble particles, with an open porosity of 86%, a through-hole orientation index of 0.68, a thickness of 7mm, and a pore size gradient of an average pore size of 230μm on the skin side and an average pore size of 450μm on the far skin side. The continuous phase of this example is a silicone rubber network obtained by cross-linking of vinyl-terminated polydimethylsiloxane and dimethylmethylhydrogen siloxane, and the cross-linking reaction of this example is promoted by a platinum complex catalyst. The sponge of this example contains cellulose nanocrystals modified by silane coupling, with a mass fraction of 1.50%. The sponge of this example contains a covalently fixed layer of hydrophilic functional silane on the surface or in the body phase, and the hydrophilic functional silane of this example is a mixture of 3-aminopropyl triethoxysilane and 3-glycidyloxypropyl trimethoxysilane, with 3-aminopropyl triethoxysilane accounting for 60% and 3-glycidyloxypropyl trimethoxysilane accounting for 40%, and the total mass fraction being 0.35%. The air permeability of the sponge of this example is determined according to GB / T 5453-1997 under a pressure difference of 100 Pa, and is 430 L·m⁻²·s⁻¹.

[0039] The silane coupling modified cellulose nanocrystals of the present example were prepared according to the following steps: raw materials were microcrystalline cellulose 100 parts by mass, sulfuric acid with a mass fraction of 64%, sodium hydroxide, and deionized water. The acidolysis step was carried out at 48°C for 80 minutes using sulfuric acid with a mass fraction of 64% at a mass ratio of acid solution to microcrystalline cellulose of 10:1 to obtain a cellulose nanocrystal dispersion. The neutralization and washing step was neutralized to pH 7.8 with a sodium hydroxide solution and then washed multiple times with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 4.5%. The coupling step was to add 3-methacryloyloxypropyltrimethoxysilane to the dispersion of the present example, the mass ratio of silane to cellulose nanocrystals of the present example was 9%, and the stirring reaction was carried out for 2.8 hours, followed by washing and drying to obtain the silane coupling modified cellulose nanocrystal powder of the present example.

[0040] The oriented dissolvable particle template of the present example was prepared according to the following steps: raw materials were sodium chloride. The classification step prepared two grades of particles, one with an average particle size of 230 μm and the other with an average particle size of 450 μm. The oriented laying and pre-pressing step laid the small particle size layer and the large particle size layer in order from the near-skin side to the far-skin side, with a mass ratio of near-skin side to far-skin side particles of 1.2, and the whole was uniaxially pre-pressed into a 7 mm thick oriented dissolvable particle template under 18 MPa. The uniaxial pre-pressing direction of the template was parallel to the long axis orientation direction of the through holes of the present example.

[0041] The covalent fixation of the hydrophilic functional silane of the present example was achieved by mixing 0.35 wt% of the mixed hydrophilic functional silane into the silicone-based composite prepolymer system and fixing it to the pore wall / cellulose nanocrystal surface through alkoxy hydrolysis-condensation during the curing process, in which 3-aminopropyltriethoxysilane was 0.21 wt%, and 3-glycidyloxypropyltrimethoxysilane was 0.14 wt%. In the present example, the near-skin side layer thickness accounted for 40% of the total thickness, and the average pore size was 230 μm, and the average pore size of the far-skin side layer was 450 μm. In the present example, the mass ratio of hydrophilic functional silane to silane coupling modified cellulose nanocrystals was 0.23.

[0042] The preparation method of the water-permeable and air-permeable sponge of the present embodiment comprises the following steps: S1. preparing a directional soluble particle template; S2. preparing a composite sizing material, taking 100 parts by mass of a vinyl-terminated polydimethylsiloxane, a hydrogen-containing siloxane crosslinking agent of dimethylmethylhydrogen siloxane, which is added in an Si-H / C=C equivalent ratio of 1.10, 1.50 parts by mass of cellulose nanocrystals modified by silane coupling, 0.35 parts by mass of a hydrophilic functional silane, and 45 ppm of platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane as a platinum complex catalyst in terms of platinum content, and defoaming after mixing under low pressure; S3. impregnating the composite sizing material of the present embodiment into the directional soluble particle template of the present embodiment under a low pressure environment of 45 kPa until full, with an impregnation time of 18 minutes; S4. curing at 110°C for 0.80 hours to obtain a composite template body; S5. dissolving the directional soluble particle template with deionized water and drying to obtain a water-permeable and air-permeable sponge, and the directional soluble particle template is dissolved by multi-stage countercurrent washing, with a washing liquid volume of 28 times the volume of the template.

[0043] The water-permeable and air-permeable sponge of the present embodiment is used for water-permeable and air-permeable and supporting and rebounding applications in mammal and sports underwear, masks, briefs, eye masks, clothing, shoes, and mattresses. The formaldehyde content of the present embodiment is 12 mg / kg as determined according to GB / T 2912.1-2009, no decomposable carcinogenic aromatic amine dyes are detected as determined according to GB / T 17592-2024, the pH of the extraction liquid is 7.0 as determined according to GB / T 7573-2009, no odor is determined according to GB 18401-2010, and it meets the A-class requirements of GB 18401-2010. The water color fastness is 4, the perspiration color fastness (acidic and alkaline) is 4, and the dry rubbing color fastness is 4.

[0044] Example 3: This example is biased towards high strength and structural stability optimization. The lower open cell fraction of 86% is combined with a thicker 7mm design and a higher cellulose nanocrystal content of 1.50% to give the sponge excellent mechanical strength, resilience and structural stability. The air permeability of 430 L·m⁻²·s⁻¹ still meets the high permeability requirement. The through-hole orientation index of 0.68 shows stable directional permeability effect. The excess equivalent ratio of Si-H of 1.10 ensures sufficient crosslinking to form a dense network structure, enhancing the durability and deformation resistance of the material. The higher pre-pressing pressure of 18 MPa makes the template have better density and strength. The higher curing temperature of 110°C and shorter curing time of 0.80 hours are beneficial to rapid prototyping and improve production efficiency. The use of two kinds of hydrophilic functional silanes (60% aminopropyl + 40% epoxy) achieves the synergistic effect of amino hydrophilicity and epoxy reactivity, although the total amount is low at 0.35%, but the mass ratio of 0.23 with high content of cellulose nanocrystals is still within a reasonable range. The larger near-skin side pore size of 230 μm and the smaller far-skin side pore size of 450 μm form a relatively gentle pore size gradient, which is beneficial to the uniformity of the overall structure. The formaldehyde content is 12 mg / kg, the pH of the extraction liquid is 7.0, and the color fastness reaches a good level of 4 levels. This example is particularly suitable for large cup type bras, shapewear, thick sports protective gear, anti-collision masks and other application scenarios that require high mechanical strength and resilience, and is also suitable for use in the crotch of briefs and other parts that require good support and washing resistance.

[0045] Example 4 This example provides a water-permeable and air-permeable sponge, comprising a cross-linked polydimethylsiloxane continuous phase and a through-hole network. The through-holes of this example are formed by dissolving the oriented soluble particle template, with an open cell fraction of 85%, a through-hole orientation index of 0.80, a thickness of 7.5 mm, and a pore size gradient of an average near-skin side pore size of 155 μm and an average far-skin side pore size of 580 μm. The continuous phase of this example is a silicone rubber network obtained by cross-linking vinyl-terminated polydimethylsiloxane and dimethylmethylhydrogen siloxane, and the cross-linking reaction of this example is promoted by a platinum complex catalyst. The sponge of this example contains cellulose nanocrystals modified by silane coupling, with a mass fraction of 2.00%. The sponge of this example contains a covalently fixed layer of hydrophilic functional silane on the surface or in the bulk phase, and the hydrophilic functional silane of this example is a mixture of 3-aminopropyl triethoxysilane and 3-glycidyloxypropyl trimethoxysilane, with 3-aminopropyl triethoxysilane accounting for 70% and 3-glycidyloxypropyl trimethoxysilane accounting for 30%, and the total mass fraction being 0.95%. The air permeability of the sponge of this example is determined according to GB / T 5453-1997 at a pressure difference of 100 Pa as 415 L·m⁻²·s⁻¹.

[0046] The silane coupling modified cellulose nanocrystals of the present example were prepared according to the following procedure: raw materials were microcrystalline cellulose 100 parts by mass, sulfuric acid with a mass fraction of 65%, sodium hydroxide, and deionized water. The acidolysis step was carried out at 50°C for 90 minutes using sulfuric acid with a mass fraction of 65% at a mass ratio of acid solution to microcrystalline cellulose of 12:1 to obtain a cellulose nanocrystal dispersion. The neutralization and washing step was neutralized to pH 8.0 using a sodium hydroxide solution and then washed multiple times with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 5%. The coupling step was to add 3-glycidyloxypropyltrimethoxysilane to the dispersion of the present example, the mass ratio of silane to cellulose nanocrystals of the present example was 10%, and the stirring reaction was carried out for 3 hours, followed by washing and drying to obtain the silane coupling modified cellulose nanocrystal powder of the present example.

[0047] The oriented dissolvable granular template of the present example was prepared according to the following procedure: the raw material was sucrose. The classification step prepared two grades of granules, one with an average particle size of 155 μm and the other with an average particle size of 580 μm. The oriented laying and pre-pressing step laid the small particle size layer and the large particle size layer in order from the near-skin side to the far-skin side, with a mass ratio of near-skin side to far-skin side particles of 1.9, and the whole was uniaxially pre-pressed into an oriented dissolvable granular template with a thickness of 7.5 mm at 18 MPa. The uniaxial pre-pressing direction of the template was parallel to the long axis orientation direction of the through holes of the present example.

[0048] The covalent fixation of the hydrophilic functional silane of the present example was achieved by mixing 0.95 wt% of the mixed hydrophilic functional silane into the siloxane-based composite prepolymer system and fixing it to the pore wall / cellulose nanocrystal surface through alkoxy hydrolysis-condensation during the curing process, in which 3-aminopropyltriethoxysilane was 0.665 wt%, and 3-glycidyloxypropyltrimethoxysilane was 0.285 wt%. In the present example, the near-skin side layer thickness accounted for 58% of the total thickness, with an average pore size of 155 μm, and the far-skin side layer had an average pore size of 580 μm. In the present example, the mass ratio of hydrophilic functional silane to silane coupling modified cellulose nanocrystals was 0.48.

[0049] The preparation method of the water-permeable and air-permeable sponge of the present embodiment comprises the following steps: S1. preparing a directional soluble particle template; S2. preparing a composite sizing material, taking 100 parts by mass of a vinyl-terminated polydimethylsiloxane, 2.00 parts by mass of cellulose nanocrystals modified by silane coupling, 0.95 parts by mass of a hydrophilic functional silane, and 48 ppm of platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane as a platinum complex catalyst based on the platinum content, and adding a dimethylmethylhydrogen siloxane crosslinking agent based on a Si-H / C=C equivalent ratio of 1.00, mixing, and then degassing under low pressure; S3. impregnating the composite sizing material of the present embodiment into the directional soluble particle template of the present embodiment under a low pressure environment of 45 kPa until it is full, with an impregnation time of 19 minutes; S4. curing at 115°C for 1.80 hours to obtain a composite template body; S5. dissolving the directional soluble particle template with deionized water and drying to obtain a water-permeable and air-permeable sponge, and the directional soluble particle template is dissolved by multi-stage countercurrent washing, with a washing liquid volume of 28 times the volume of the template.

[0050] The water-permeable and air-permeable sponge of the present embodiment is used for water-permeable and air-permeable and supporting and rebounding applications in mammal and sports underwear, masks, briefs, eye masks, clothing, shoes, and mattresses. The formaldehyde content of the present embodiment is 15 mg / kg as determined according to GB / T 2912.1-2009, no decomposable carcinogenic aromatic amine dyes are detected as determined according to GB / T 17592-2024, the pH of the extraction liquid is 6.8 as determined according to GB / T 7573-2009, no odor is detected according to GB 18401-2010, and it meets the A-class requirements of GB 18401-2010. The water color fastness is 4, the perspiration color fastness (acidic and alkaline) is 4, and the dry rubbing color fastness is 4-5.

[0051] Example 4 Features: This example focuses on verifying the boundary implementability of the scope of claims, using a plurality of parameter boundary or near boundary value configurations. The open porosity of 85% is the actual lower boundary value (first boundary verification), which verifies that the air permeability of 415 L·m⁻²·s⁻¹ can still meet the performance requirement of more than 400 L·m⁻²·s⁻¹ under the condition of the lowest open porosity. The through-hole orientation index of 0.80 is the highest among the four examples, showing the best directional air permeation effect. The cellulose nanocrystal content of 2.00% is the actual upper boundary value (first boundary verification), which proves that the processability and performance controllability of the material under high filling amount. The hydrophilic functional silane content of 0.95% is close to the upper boundary, and the mass ratio of the two is 0.48, which is within a reasonable range, showing the realizability of high hydrophilic modification degree. The design of a large pore size gradient (near-skin side 155 μm close to the lower limit, far-skin side 580 μm close to the upper limit) forms the most significant directional air permeation effect, combined with a near-skin side layer thickness ratio of up to 58% and a particle mass ratio of 1.9, verifying the structural stability of the extreme pore size distribution. The sulfuric acid concentration of 65% (first boundary verification), acidolysis temperature of 50°C (first boundary verification), acidolysis time of 90 minutes, neutralization pH of 8.0, solid content of 5%, coupling agent mass ratio of 10%, reaction time of 3 hours, and other cellulose nanocrystal preparation parameters all reach the upper boundary, proving the feasibility of the intensified acidolysis and efficient coupling process. The equivalent ratio of 1.00 ensures the sufficient crosslinking of the high filling system, and the platinum content of 48 ppm close to the upper limit ensures the catalytic efficiency. The curing temperature of 115°C and the curing time of 1.80 hours close to the upper limit verify the process feasibility of high temperature and long time curing. The formaldehyde content is 15 mg / kg, the extraction liquid pH is 6.8, and the color fastness reaches level 4 to 4-5. This example is particularly suitable for special application scenarios that require extreme performance, such as heavy load shaping underwear, professional sports protective gear, medical protective masks, high-strength support eye masks, and other high-end products that require boundary verification of material performance, fully proving the scientific rationality and industrial implementability of the scheme range.

[0052] Comparative Example 1 Basically the same as Example 1, the difference is that the open porosity is 82%, which is achieved by increasing the pre-pressing pressure of the directional soluble particle template to 15 MPa, and the dosages of other components and preparation conditions remain unchanged.

[0053] Comparative Example 2 Basically the same as Example 1, the difference is that the open porosity is 94%, which is achieved by reducing the pre-pressing pressure of the directional soluble particle template to 9 MPa, and the dosages of other components and preparation conditions remain unchanged.

[0054] Comparative Example 3 The same as example 1, the difference is that the orientation index of the through hole is 0.50, and the soluble particle template is prepared by using a non-oriented paving method, that is, the two grades of particles are mixed and randomly paved, and the dosages of other components and the preparation conditions are unchanged.

[0055] Comparative example 4 The same as example 1, the difference is that the average pore size on the near-skin side is 130 μm, and the particles with an average particle size of 130 μm are prepared by sieving as the near-skin side layer, and the dosages of other components and the preparation conditions are unchanged.

[0056] Comparative example 5 The same as example 1, the difference is that the average pore size on the far-skin side is 650 μm, and the particles with an average particle size of 650 μm are prepared by sieving as the far-skin side layer, and the dosages of other components and the preparation conditions are unchanged.

[0057] Comparative example 6 The same as example 1, the difference is that the mass fraction of cellulose nanocrystals is 0.35%, and the addition amount of cellulose nanocrystals is reduced to 0.35% when the composite sizing material is prepared, and the dosages of other components and the preparation conditions are unchanged.

[0058] Comparative example 7 The same as example 1, the difference is that the mass fraction of cellulose nanocrystals is 2.30%, and the addition amount of cellulose nanocrystals is increased to 2.30% when the composite sizing material is prepared, and the dosages of other components and the preparation conditions are unchanged.

[0059] Comparative example 8 The same as example 1, the difference is that the mass fraction of hydrophilic functional silane is 0.05%, and the addition amount of 3-aminopropyl triethoxysilane is reduced to 0.05% when the composite sizing material is prepared, and the dosages of other components and the preparation conditions are unchanged.

[0060] Comparative example 9 The same as example 1, the difference is that the mass fraction of hydrophilic functional silane is 1.15%, and the addition amount of 3-aminopropyl triethoxysilane is increased to 1.15% when the composite sizing material is prepared, and the dosages of other components and the preparation conditions are unchanged.

[0061] Comparative example 10 The same as example 1, the difference is that no silane-coupled modified cellulose nanocrystals are added, and no cellulose nanocrystals are added when the composite sizing material is prepared, and the dosages of other components and the preparation conditions are unchanged.

[0062] Comparative example 11 The same as example 1, the difference is that no hydrophilic functional silane is added, and no 3-aminopropyl triethoxysilane is added when the composite sizing material is prepared, and the dosages of other components and the preparation conditions are unchanged.

[0063] Comparative Example 12 The process is basically the same as in Example 1, except that the equivalent ratio of Si-H to C=C is 0.70, and the amount of dimethylmethylhydrosiloxane and polysiloxane added is reduced to make the equivalent ratio 0.70 when the composite compound is formulated. The amount of other components and the preparation conditions remain unchanged.

[0064] Comparative Example 13 It is basically the same as Example 1, except that the curing temperature is 70°C and it is cured at 70°C for 1.25 hours. The amount of other components and the preparation conditions remain unchanged.

[0065] Performance testing: Experiment 1: Air Permeability Test The test subject was a water-permeable and air-permeable sponge. The purpose of the test was to evaluate the air permeability of the sponge and verify the air permeability efficiency of the through-pore network. The test principle was based on Darcy's law, measuring the airflow rate per unit area per unit time by applying a fixed pressure difference. The experimental method adopted the GB / T 5453-1997 standard "Determination of Air Permeability of Textile Fabrics". The sample (circular with a diameter of 100 mm) was clamped between the upper and lower clamps of the air permeability tester (YG461E type) and sealed. A pressure difference of 100 Pa was applied, and the steady-state airflow rate Q (L / min) was recorded. The test conditions were a temperature of 20±2℃ and a relative humidity of 65±3%RH. Each sample was tested 5 times and the average value was taken. Key parameters included a pressure difference of 100 Pa and a sample area of ​​78.5 cm². Data processing was performed according to GB / T 5453-1997. Air permeability was calculated under a specified pressure difference (ΔP=100 Pa in this test): AP=Q×60 / A (where Q is L / min and A is m²). The unit of AP is L·m⁻²·s⁻¹, and the criterion is ≥400 L·m⁻²·s⁻¹.

[0066] Experiment 2: Compression Permanent Deformation Test Test object: finished water-permeable and air-permeable sponge. Test purpose: to evaluate the resilience and anti-deformation performance of the sponge under long-term compression load. Test principle: based on the residual deformation rate of the material after being kept at a constant compression strain for a certain period of time. Experimental method: according to GB / T 6669-2008 "Determination of Compression Set of Flexible Foamed Polymeric Materials", the sample (cylinder with a diameter of 29 mm and an original thickness) is placed between two parallel metal plates, compressed to 50% of the original thickness at 23±2℃ and kept for 22 hours, and after removing the load, the final thickness is measured at room temperature after 30 minutes of standing. Test conditions: temperature 23±2℃, relative humidity 50±5% RH, 3 samples tested for each group. Key parameters: compression rate 50%, holding time 22 hours, recovery time 30 minutes. Data processing: compression set CS=(t0-t2) / (t0-t1)×100%, where t0 is the original thickness, t1 is the compression thickness, and t2 is the thickness after recovery, deformation rate ≤15% is excellent.

[0067] Experiment 3: tensile strength and elongation at break test Test object: finished water-permeable and air-permeable sponge. Test purpose: to evaluate the mechanical strength and ductility of the sponge. Test principle: based on the stress-strain relationship of the material under constant speed stretching. Experimental method: according to GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber", the sample is cut into dumbbell shape (No. 2 sample, total length 75 mm, narrow part width 4 mm), and a universal material testing machine (Instron 5966 type) is used to stretch at a rate of 500 mm / min at 23±2℃ until breaking, and the maximum tensile stress and elongation at break are recorded. Standard: GB / T 528-2009. Test conditions: temperature 23±2℃, relative humidity 50±5% RH, 5 samples tested for each group and the average value is taken. Key parameters: tensile rate 500 mm / min, gauge length 25 mm. Data processing: tensile strength σ=F / A (MPa), elongation at break ε=(L-L0) / L0×100%, where F is the maximum tensile force, A is the original cross-sectional area, L is the breaking length, and L0 is the original gauge length.

[0068] Experiment 4: moisture absorption and sweat release performance test The test object is water vapor permeable and air permeable sponge finished product. The test purpose is to evaluate the moisture absorption rate and moisture permeability of the sponge, and to verify the modification effect of the hydrophilic functional silane. The test principle is based on the water vapor transmission rate of the material under standard atmospheric pressure. The experimental method refers to GB / T 12704.1-2009 “Textiles-Determination of water vapor permeability-Part 1: Moisture method”, the sample (diameter 70 mm circle) is sealed on the moisture permeable cup containing 10 g desiccant (anhydrous calcium chloride), the moisture permeable cup is placed in a constant temperature and humidity chamber with temperature 38±1℃, relative humidity 90±2%RH, and weighed every 1 hour for 24 hours, and the weight gain-time curve is drawn. The standard is GB / T 12704.1-2009. The test conditions are temperature 38±1℃, relative humidity 90±2%RH. Key parameters include sample area 38.5 cm², test duration 24 hours. Data processing is to calculate the water vapor transmission rate WVT=Δm / (A×t) by the slope of the steady state stage, where Δm is the weight gain (g), A is the sample area (m²), t is the time (h), and the unit is g·m⁻²·h⁻¹.

[0069] Experiment 5: Contact angle test The test object is the surface of the water vapor permeable and air permeable sponge. The test purpose is to evaluate the hydrophilic performance of the sponge surface, and to verify the fixing effect of the hydrophilic functional silane. The test principle is based on the wetting behavior of liquid droplets on solid surfaces, and the surface energy is quantified by measuring the liquid-solid-gas three-phase contact angle. The experimental method uses a video optical contact angle measuring instrument (type SDC-200S), the sample is fixed flat on the test table, and 2 μL of deionized water is added to the sample surface by the pendant drop method, and the side view image is taken at 1 second, 5 seconds, 10 seconds and 30 seconds after dropping, and the contact angle is calculated by fitting the droplet profile and calculating the contact angle by software. The test conditions are temperature 25±1℃, relative humidity 40±5%RH. Key parameters include droplet volume 2 μL, test time 1 / 5 / 10 / 30 seconds. Data processing takes the average value of 5 different positions for each sample, the contact angle θ<90° is hydrophilic, the smaller the θ, the stronger the hydrophilic, which is not explicitly limited by the claims but should be significantly reduced compared with the comparative example.

[0070] Experiment 6: Pore size distribution and open porosity determination The test object is the finished product of water-permeable and air-permeable sponge. The test purpose is to characterize the pore size distribution, average pore size and open porosity of the sponge, and to verify the through-hole network structure. The test principle is based on the mercury intrusion method for determining the pore size distribution and the Archimedes drainage method for determining the open porosity. The experimental method uses an automatic mercury porosimeter (AutoPore V9620 type) to determine the pore size distribution, and the sample (about 1 cm³) is placed in the dilatometer after vacuumizing and then injected with mercury, and gradually pressurized to 400 MPa to record the pressure-mercury injection curve. According to the Washburn equation d = (-4γcosθ) / P, the pore size distribution is calculated. The open porosity is calculated by ρ a (apparent density) and ρ s (skeleton density) according to GB / T 6343-2009 "Determination of apparent density of foamed plastics and rubbers" combined with the liquid emptying method, φ = (1-ρ a / ρ s ) × 100%. The test conditions are temperature 25 ± 1℃. The key parameters include mercury contact angle 130°, maximum pressure 400 MPa. The data processing draws the pore size distribution curve and calculates the average pore size of the near-skin and far-skin sides and the open porosity.

[0071] Experiment 7: Scanning electron microscope morphology characterization The test object is the cross-section and surface of the water-permeable and air-permeable sponge. The test purpose is to observe the micro-morphology, through-hole structure, cellulose nanocrystal dispersion state and pore wall thickness of the sponge. The test principle is based on the secondary electron imaging technology. The experimental method uses a field emission scanning electron microscope (FESEM, ZEISS Sigma 300 type), cuts the sample along the thickness direction to obtain the cross-section, uses liquid nitrogen brittle fracture to maintain the original structure, vacuum gold spraying (thickness 10 nm) to enhance the conductivity, under the conditions of acceleration voltage 5 kV and working distance 8 mm, respectively takes low magnification (×100), medium magnification (×500) and high magnification (×5000) images, and observes the through-hole network, pore size gradient, cellulose nanocrystal distribution and silicone rubber matrix morphology. The test conditions are vacuum degree 1 × 10⁻ 4 Pa. The key parameters include acceleration voltage 5 kV and gold spraying thickness 10 nm. The data processing uses image analysis software (ImageJ) to statistically analyze the size and distribution uniformity of cellulose nanocrystals for high magnification images.

[0072] The above four groups of single factor experiments fix the basic formula of Example 1 and independently change the four key parameters of open porosity, cellulose nanocrystal mass fraction, hydrophilic functional silane mass fraction and curing temperature, systematically verify the influence law of each parameter on the material performance and the rationality of the parameter range of the claim, and the experimental design follows the principle of controlled variable method to ensure the reliability and comparability of the data, wherein Figure 1For the effect of open porosity on air permeability and compression set, the fixed conditions were 100 parts by mass of vinyl-terminated polydimethylsiloxane, an equivalent ratio of Si-H to C=C of 1.00, 27.5 ppm of platinum catalyst, 1.25% of cellulose nanocrystals modified with silane coupling, 0.55% of hydrophilic functional silane, a thickness of 5 mm, a near skin side pore diameter of 200 μm, a far skin side pore diameter of 500 μm, a through hole orientation index of 0.70, a curing condition of 100°C x 1.25 hours, and the open porosity was changed by adjusting the pre-pressing pressure; Figure 2 For the effect of cellulose nanocrystal mass fraction on tensile strength and elongation at break, the fixed conditions were 100 parts by mass of vinyl-terminated polydimethylsiloxane, an equivalent ratio of Si-H to C=C of 1.00, 27.5 ppm of platinum catalyst, 0.55% of hydrophilic functional silane, an open porosity of 88.5%, a thickness of 5 mm, a near skin side pore diameter of 200 μm, a far skin side pore diameter of 500 μm, and a curing condition of 100°C x 1.25 hours, and the cellulose nanocrystal mass fraction was changed; Figure 3 For the effect of hydrophilic functional silane mass fraction on contact angle (30 seconds) and water vapor transmission rate, the fixed conditions were 100 parts by mass of vinyl-terminated polydimethylsiloxane, an equivalent ratio of Si-H to C=C of 1.00, 27.5 ppm of platinum catalyst, 1.25% of cellulose nanocrystals modified with silane coupling, an open porosity of 88.5%, a thickness of 5 mm, a near skin side pore diameter of 200 μm, a far skin side pore diameter of 500 μm, and a curing condition of 100°C x 1.25 hours, and the hydrophilic functional silane mass fraction was changed; Figure 4For the influence of curing temperature on tensile strength and compression set, the fixed conditions are 100 parts by mass of vinyl-terminated polydimethylsiloxane, 1.00 equivalent ratio of Si-H to C=C, 27.5 ppm of platinum catalyst, 1.25% of cellulose nanocrystal modified by silane coupling, 0.55% of hydrophilic functional silane, 88.5% of open porosity, 5 mm of thickness, 1.25 hours of curing time, and the curing temperature is changed. The open porosity single-factor experiment reveals that the range of 85-92% is based on the scientific consideration of the balance between air permeability and structural stability. When the open porosity is lower than the lower limit of 85%, the air permeability decreases sharply to 405 L·m⁻²·s⁻¹, which cannot meet the air permeation demand. When the open porosity is higher than the upper limit of 92%, the compression set increases to more than 16.5%, which leads to the loss of long-term use stability of the material. The optimal performance in the interval of 88.5-90% in the experimental data verifies the accuracy of the range claimed. The cellulose nanocrystal mass fraction single-factor experiment tests through a wide span of 0.30-2.60% and confirms the necessity of the range of 0.50-2.00%. When the cellulose nanocrystal mass fraction is lower than the lower limit of 0.50%, the tensile strength is only 0.71 MPa, which cannot provide sufficient mechanical support. When the cellulose nanocrystal mass fraction is higher than the upper limit of 2.00%, the strength increases to 1.28 MPa, but the elongation at break decreases sharply to 265%, making the material brittle and losing flexibility. When the cellulose nanocrystal mass fraction is higher than 2.30%, the strength gain marginal effect decreases, and the elongation at break continues to deteriorate to 210%, which fully shows that the upper limit of 2.00% is the critical point of the balance between strength and flexibility. The hydrophilic functional silane mass fraction single-factor experiment verifies the effectiveness of the range of 0.10-1.00% on the surface hydrophilicity modification. When the hydrophilic functional silane mass fraction is lower than 0.10%, the contact angle is as high as 58°, and the hydrophilic effect is not obvious. When the hydrophilic functional silane mass fraction exceeds 1.00%, the contact angle can be reduced to below 30°, but the water vapor permeability increases slowly to 4400 g·m⁻²·h⁻¹ and tends to be flat. Excessive hydrophilic silane may introduce VOC risk and affect the processing flowability of the rubber compound. In the experimental data, the interval of 0.55-0.85% realizes good hydrophilicity of 42-34° and high moisture permeability of 4200-4350 g·m⁻²·h⁻¹, which proves that the upper limit of 1.00% considers both performance improvement and process controllability. The curing temperature single-factor experiment tests through a temperature gradient of 65-140℃ and confirms the process window of 80-120℃. When the curing temperature is lower than 80℃, the crosslinking reaction is incomplete, resulting in a tensile strength of only 0.73 MPa and a compression set of 15.5%. When the curing temperature is higher than 120℃, although the performance can still be maintained in the interval of 110-120℃, the strength decreases to 0.88 MPa and the set rebounds to 12.5% when the temperature is higher than 130℃, which shows signs of excessive crosslinking or thermal oxidative degradation. The experimental data show that the optimal curing temperature interval is 100-120℃, which ensures sufficient crosslinking and avoids thermal damage. The upper limit of 120℃ leaves a safety margin for industrial production.The boundary verification levels of the four groups of single-factor experiments are clear. The opening rate, cellulose nanocrystals and hydrophilic silane are listed as the first-level actual boundary verification objects as core structures and functional parameters. Two test points are set outside the upper and lower limits to fully expose the performance degradation trend beyond the scope of the claims. The curing temperature is listed as the second-level safety boundary verification as a process parameter to confirm the reliability and stability of the process window. All experiments use three parallel tests and calculate the standard deviation to quantify the data dispersion. The trend of increasing standard deviation value with the deviation of the optimal interval further confirms the stability and repeatability of the material performance within the scope of the claims. The comprehensive results of the four groups of single-factor experiments fully prove that the setting of the range of each core parameter in the technical solution of the invention is a scientific choice based on the laws of material science and engineering practice experience, which ensures the excellent comprehensive performance of the material and ensures the operability and quality stability of industrial production, providing solid experimental data support for the reasonableness, reliability and effectiveness of the claims.

[0073] Pore size distribution Figure 5 The correctness is reflected in its high consistency with the structural design and process parameters of Example 1: the oriented dissolvable particle template is composed of two grades of graded sodium chloride particles, with an average particle size of about 200 μm near the skin side and about 500 μm far from the skin side, and is oriented and laid in the order of small particle size layer→ large particle size layer and unidirectional pre-pressed forming; then after 30 kPa low pressure impregnation and 100℃ curing, the template is dissolved to obtain a sponge structure with an opening rate of 88.5%, a through-hole orientation index of 0.70, and a pore size gradient increasing from the skin side to the far skin side. Therefore, the pore size distribution should present a double or wide peak distribution with 200 μm and 500 μm as the characteristic or main peak area, and in the cross-sectional direction, it should reflect the gradient characteristics from small to large; this distribution is mutually confirmed with the high air permeability of 450 L·m⁻²·s⁻¹, proving that the pore size distribution shown in the figure above is consistent with the target structure and functional parameters of the material, and thus it can be determined that it is the correct result reflecting the pore structure characteristics of this example.

[0074] The performance of the examples and comparative examples is summarized in Table 1. From the data in the table, it can be seen that the open porosity is a key factor affecting the air permeability. Comparative Example 1 has an open porosity of only 82%, resulting in an air permeability of 350 L m-2s-1, while Comparative Example 2 has an open porosity of 94%, resulting in an air permeability of 580 L m-2s-1. However, too high an open porosity can seriously weaken the mechanical properties of the material, resulting in a compression permanent set of 18.5% and a tensile strength of 0.58 MPa. The cellulose nanocrystal content has a significant strengthening effect on the mechanical properties. Example 4, which contains 2.00% cellulose nanocrystals, has the highest tensile strength of 1.28 MPa and the lowest compression permanent set of 8.5%. Comparative Example 10, which contains no cellulose nanocrystals, has a tensile strength of 0.52 MPa and a compression permanent set of 18.2%. Comparative Example 13 contains cellulose nanocrystals but has a low crosslinking density due to insufficient curing conditions (70°C x 1.25 h), resulting in a high compression permanent set of 20.5% and a low tensile strength of 0.55 MPa. The content of hydrophilic silane directly affects the surface wetting properties of the material. Example 2, which contains 0.75% hydrophilic silane, has a 30-second contact angle of 35°. Comparative Example 9, which contains a higher content of 1.15% hydrophilic silane, has a 30-second contact angle of 28°, but this exceeds the scope of the claims and may pose a risk of VOC. Comparative Example 8, which contains a content of hydrophilic silane of less than 0.25%, and Comparative Example 11, which contains no hydrophilic silane, have 30-second contact angles of 68° and 82°, respectively. The Si-H equivalent ratio of the crosslinking system and the curing conditions are crucial to the integrity of the material network structure. Comparative Example 12, which contains an insufficient amount of crosslinking agent (Si-H to C=C equivalent ratio of 0.70), results in insufficient crosslinking, leading to an increase in material brittleness and a reduction in elongation at break to 285%. Comparative Example 13 has a high compression permanent set and a low tensile strength due to insufficient crosslinking caused by a low curing temperature. The pore size gradient design affects the moisture permeability. Examples 1-4 have a water vapor transmission rate of 3850-4800 g m-2h-1 through the use of a gradient pore size structure on the near-skin side and the far-skin side. Comparative Example 1 has a reduced pore connectivity and a reduced moisture permeability of 3200 g m-2h-1 due to an open porosity of only 82%. Comparative Example 3 has a reduced air permeability and moisture permeability due to an orientation index of only 0.50, resulting in an increase in pore tortuosity. In summary, Examples 1-4 have an open porosity of 85-91%, an optimized cellulose nanocrystal content of 1.00-2.00%, a hydrophilic silane content of 0.45-0.75%, an Si-H equivalent ratio of 0.95-1.10, and a curing condition of 95-105°C for 1.0-1.5 hours, the comprehensive balance of air permeability, mechanical property, hydrophilicity and moisture permeability is successfully achieved, while the performance indicators of each comparative example are significantly deteriorated due to deviation from the above parameter range, even if individual comparative examples such as Comparative Example 2 and Comparative Example 9 have slight advantages in single indicators, but due to performance imbalance or exceeding the scope of the claims, they do not have practical value.

[0075] Figure 6 The correctness can be evidenced by the changes of characteristic absorption peaks: the unmodified cellulose nanocrystals should exhibit typical O-H stretching vibration wide peaks (about 3300-3400 cm⁻¹), C-H stretching vibration (about 2900 cm⁻¹), and C-O-C and C-O stretching vibration sugar ring fingerprint band (about 1050-1160 cm⁻¹). After coupling modification by 3-methacryloxypropyltrimethoxysilane, the following signals should appear or be enhanced in addition to the cellulose main skeleton peaks: Si-O-C / Si-O-Si related absorption (band shape overlap in the interval of about 1000-1130 cm⁻¹ and slight red shift / intensity change), Si-CH3 related absorption (about 1250-1270 cm⁻¹ and about 800-850 cm⁻¹), methacryl C=O stretching (about 1715-1730 cm⁻¹, which may be slightly shifted if there is partial condensation or hydrogen bond environment), C=C related absorption (about 1635-1645 cm⁻¹, different degrees of crosslinking or hydrolysis polycondensation result in intensity change), and the O-H wide peak is narrowed in band shape or decreased in intensity due to the substitution of surface hydroxyl groups by silane and the change of hydrogen bond network. The above difference in peak shape and shift rules is consistent with the chemical mechanism of silane coupling to the surface of cellulose, and thus can prove Figure 6 The comparison of FTIR transmission spectra of modified and unmodified samples in Example 1 is correct and has chemical indication.

[0076] Figure 7 and Figure 8 respectively show the sponge morphology of the near-skin side and the far-skin side of Example 1 of the present application, and the successful construction of the gradient pore size structure can be clearly verified by scanning electron microscope observation, wherein Figure 7 the near-skin side pore size is concentrated at about 200 μm, the pore shape is regular and the pore wall thickness is uniform, and the small pore size structure is beneficial to provide soft touch feeling and promote rapid absorption of sweat when in contact with the skin, while Figure 8The display far dermal side aperture is significantly increased to about 500 μm, the large aperture structure forms a rapid moisture removal channel to facilitate the outward diffusion of water vapor, and the aperture on both sides presents a gradient difference of about 2.5 times and penetrates, proving that the directional gradient pore distribution from the near dermal side to the far dermal side is successfully realized by the hierarchical paving and one-way pre-pressing of the directional soluble particle template. This asymmetric two-way gradient structure not only ensures the comfort of the skin contact interface but also realizes the efficient air and moisture permeability of the overall structure. The morphology observation results and the excellent data of the air permeability of 450 L·m⁻²·s⁻¹ and the water vapor permeability of 4200 g·m⁻²·h⁻¹ measured in Example 1 mutually confirm each other, fully proving the key role of the gradient aperture design in realizing the function of the material. At the same time, the pore wall surface is smooth without obvious defects and the pore connectivity is good, indicating that the curing process parameters are properly controlled to make the silicone rubber matrix fully cross-linked to form a stable three-dimensional network structure, the cellulose nanocrystals are uniformly dispersed in the pore wall matrix to play a reinforcing role, and the hydrophilic functional silane successfully modifies the pore wall surface to improve the hydrophilicity. The high consistency of the micro-morphology characteristics and the macro-performance test data provides intuitive and reliable experimental evidence for the scientificity and practicality of the technical solution of the present application.

[0077]

[0078]

[0079] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that: any equivalent structural transformation made under the concept of the present application, using the contents of the present application specification and drawings, should be covered within the protection scope of the claims of the present application.

Claims

1. A water-permeable and air-permeable sponge, characterized by, A sponge comprising a continuous phase of crosslinked polydimethylsiloxane and a network of through-holes, comprising the following features: a. the through-holes are formed by leaching of an oriented dissolvable granular template, the open porosity is 85-92%, the through-holes have an orientation index of not less than 0.60, the thickness is 2-8 mm, and the pore size gradient is 150-250 μm for the average pore size on the proximal side and 400-600 μm for the average pore size on the distal side; b. the continuous phase is a silicone rubber network formed by crosslinking of a vinyl-terminated polydimethylsiloxane with a hydrosiloxane, wherein the hydrosiloxane is dimethylmethylhydrosiloxane or a methylhydrosiloxane-dimethylsiloxane copolymer, and the crosslinking is a platinum-catalyzed hydrosilylation; c. the sponge contains cellulose nanocrystals modified by silane coupling in an amount of 0.50-2.00% by mass; d. the sponge contains a covalently immobilized layer of hydrophilic functional silane on the surface or in the bulk phase, the hydrophilic functional silane is selected from 3-aminopropyltriethoxysilane and / or 3-glycidyloxypropyltrimethoxysilane, and the total amount of the hydrophilic functional silane in the finished sponge is 0.10-1.00% by mass; e. the air permeability of the sponge is not less than 400 L·m⁻²·s⁻¹ as determined according to GB / T 5453-1997 at a pressure difference of 100 Pa.

2. The sponge according to claim 1, characterized in that The cellulose nanocrystals modified by silane coupling are prepared by the following steps: A1. Raw materials: 100 parts by mass of microcrystalline cellulose, 60-65% by mass of sulfuric acid, sodium hydroxide, and deionized water; A2. Acidolysis: the microcrystalline cellulose is treated with 60-65% by mass of sulfuric acid at a mass ratio of acid solution to microcrystalline cellulose of 8:1-12:1 at 40-50°C for 30-90 minutes to obtain a cellulose nanocrystal dispersion; A3. Neutralization and washing: the dispersion is neutralized to a pH of 6.0-8.0 with a sodium hydroxide solution and then washed multiple times with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 2-5%; A4. Coupling: 3-(methacryloyloxy)propyltrimethoxysilane or 3-glycidyloxypropyltrimethoxysilane is added to the dispersion at a mass ratio of silane to cellulose nanocrystals of 2-10%, and the mixture is stirred for 1-3 hours, followed by washing and drying to obtain the cellulose nanocrystals modified by silane coupling.

3. The sponge of claim 1, wherein, The oriented dissolvable granular template is prepared by the following steps: C1. Raw materials: sodium chloride or sucrose; C2. Classification: two grades of granules are prepared, one with an average particle size of 150-250 μm and the other with an average particle size of 400-600 μm; C3. Oriented paving and pre-pressing: the small-particle-size layer and the large-particle-size layer are sequentially paved in the order of the proximal side to the distal side at a mass ratio of the proximal side to the distal side of 1.0-2.0, and the whole is uniaxially pre-pressed to form an oriented dissolvable granular template with a thickness of 2-8 mm, the uniaxial pre-pressing direction of the template is parallel to the orientation direction of the long axis of the through-holes.

4. The sponge of claim 1, wherein, The covalent fixation of the hydrophilic functional silane is formed by mixing 0.10-1.00 wt% of 3-aminopropyltriethoxysilane and / or 3-glycidoxypropyltrimethoxysilane into the composite prepolymer system, and then hydrolysis-condensation of the alkoxyl groups and condensation with the surface silanol of the cellulose nanocrystals during the curing process; this process does not involve the hydrosilylation reaction.

5. The sponge of claim 1, wherein The near-skin side layer thickness accounts for 30-60% of the total thickness, and the average pore size is 150-250 μm, and the average pore size of the far-skin side layer is 400-600 μm.

6. The sponge of claim 1, wherein The mass ratio of the hydrophilic functional silane to the cellulose nanocrystals modified by silane coupling is 0.20-1.

00.

7. A method of producing a water-permeable and air-permeable sponge according to any one of claims 1 to 6, characterized by, The method comprises the following steps: S1. Preparing a directional dissolvable particle template; S2. Preparing a composite gum: taking vinyl-terminated polydimethylsiloxane as 100 parts by mass; adding a silane-containing siloxane crosslinking agent according to the equivalent ratio of Si-H / C=C of 0.80-1.20; adding 0.50-2.00 parts by mass of cellulose nanocrystals modified by silane coupling; adding 0.10-1.00 parts by mass of a hydrophilic functional silane; and adding a platinum complex catalyst in an amount of 5-50 ppm in terms of platinum content, and the platinum complex catalyst is platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane; and mixing and then degassing under low pressure; S3. Impregnating the composite gum into the directional dissolvable particle template under a low pressure of 10-50 kPa until full; S4. Curing at 80-120°C for 0.50-2.00 hours to obtain a composite template body; S5. Dissolving the directional dissolvable particle template with deionized water and drying to obtain a water-permeable and air-permeable sponge.

8. The method for preparing a water-permeable and air-permeable sponge according to claim 7, characterized in that, The impregnation time of S3 is 10-20 minutes.

9. The method for preparing a water-permeable and air-permeable sponge according to claim 7, characterized in that, The directional dissolvable particle template is dissolved by multi-stage countercurrent washing, and the washing liquid volume is 10-30 times the volume of the template.

10. The water-permeable and air-permeable sponge according to any one of claims 1-6 or prepared by the method according to any one of claims 7-9 is used for water-permeable and air-permeable and supporting and rebounding applications in nursing and sports underwear, masks, briefs, eye masks, clothing, shoes, and mattresses.

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