Method for producing a foamed material and use thereof

Abstract

The application provides a preparation method and application of a foamed material, and belongs to the foaming field.The application provides a preparation method of a foamed material, wherein the foamed material is a three-dimensional reticular structure with three-dimensional through channels, and the method comprises the following steps: printing a blank with a three-dimensional reticular structure by mixing raw materials of the foamed material; and performing supercritical foaming on the blank to form micron-level closed pores, so that the foamed material is obtained.The foamed material prepared by the application has the advantages of high overall air permeability and heat dissipation, overall washing, easy cleaning, lightweight, long-term anti-collapse, high elasticity and silence, personalized customization, and high structure size precision.

Description

Technical Field

[0001] This invention relates to the field of foaming, and more specifically to a method for preparing and applying foamed materials. Background Technology

[0002] Traditional sleep support products mainly use polyurethane memory foam and ordinary sponge molding foaming processes, which have long suffered from several industry shortcomings: First, poor support. The solid, homogeneous structure cannot provide zoned gradient support according to the pressure of the head, neck, shoulders, waist, hips, and soles of the feet, easily causing the cervical and lumbar vertebrae to be suspended and subjected to stress, leading to strain with long-term use; ordinary honeycomb and columnar lattice structures also have the problems of stress concentration and skin irritation when in close contact with the body. Second, insufficient breathability. Traditional solid structures lack ventilation channels, leading to heat accumulation and sweating in summer, which easily breeds mites and mold, resulting in poor hygiene. Third, difficult cleaning and maintenance. Traditional products are prone to deformation and dirt accumulation when they absorb water, and cannot be washed as a whole, only the surface can be wiped, leaving dirt and bacteria for a long time. Fourth, weak durability. Traditional memory foam has a rapid decline in elasticity, collapsing and denting after a short period of use, resulting in a significant decrease in support performance. Fifth, rigid processes. Traditional molding foaming is highly homogenized, making it impossible to achieve personalized and customized body-fitting production.

[0003] While existing technologies include 3D printing combined with supercritical permeation and steam foaming, these are two-step processes that rely on steam equipment and external molds. They lack multi-type lattice and zoned gradient ergonomic designs specifically for sleep and cushioning products, and do not possess core functions such as full-area breathability and washability. They can only be applied to ordinary industrial products and cannot solve the industry pain points of high-end sleep support products. Summary of the Invention

[0004] This invention provides a method for preparing foamed materials and their applications. The foamed materials prepared by this invention are breathable, washable, and do not require external molds during the preparation process. Furthermore, they can be customized.

[0005] This invention provides a method for preparing a foamed material, comprising the following steps: The raw materials for foaming are mixed and then printed to obtain a blank with a three-dimensional mesh structure. The blank is subjected to supercritical foaming to form micron-sized closed pores, thereby obtaining the foamed material; The foamed material has a three-dimensional mesh structure with three-dimensional through channels.

[0006] Preferably, the three-dimensional mesh structure includes one or more of the following: a mesh structure formed by multiple layers of S-shaped corrugations arranged in an alternating pattern; a square mesh structure; a body-centered cubic mesh structure; and a face-centered cubic mesh structure.

[0007] Preferably, the raw materials include one or more of thermoplastic polyurethane, modified thermoplastic SEBS, polyether block amide, and flexible nylon.

[0008] Preferably, the raw materials for preparing the thermoplastic polyurethane, by mass fraction, include 35-40% MDI-type diisocyanate, 50-55% polyether diol, and 5-15% 1,4-butanediol; The modified thermoplastic SEBS raw materials, by weight, include 70 parts SEBS, 15 parts PP, 20 parts naphthenic oil, 3 parts compatibilizer, 0.3 parts antioxidant, and 5 parts phthalate-free plasticizer; By weight, the raw materials of the flexible nylon include 45 parts of nylon 11, 45 parts of nylon 12, 10 parts of toughening agent, 8 parts of flexibility modifier, and 2 parts of wear-resistant additive.

[0009] Preferably, the supercritical foaming process includes placing the blank in a supercritical gas and sequentially performing saturated adsorption and depressurization foaming.

[0010] Preferably, the supercritical gas includes supercritical carbon dioxide.

[0011] Preferably, the saturation adsorption temperature is 80~90℃, the pressure is 18~22MPa, and the time is 45~75min.

[0012] Preferably, the depressurization rate of the depressurization foam is 0.2~12MPa / min.

[0013] Preferably, the porosity of the three-dimensional network structure in the blank is 40-65%; the diameter of the micropores is 10-40 μm, and the closed-cell rate is ≥90%.

[0014] The present invention also provides the application of the foamed material prepared by the preparation method described above in pillows, mattress cores, lumbar supports, seat cushions or insoles.

[0015] The foaming material prepared by this invention has the following advantages: High breathability and heat dissipation throughout: The foaming material of this invention has a three-dimensional through hollow channel, allowing airflow to pass through without dead angles in both horizontal and vertical directions. It is not stuffy or sweaty when used, and effectively inhibits the growth of mites and mold, solving the industry pain point of stuffiness and dampness in traditional memory foam and sponge products. It is washable and easy to clean: the product is molded in one piece without glue, inner liner, splicing, or hardware parts, so it can be washed as a whole, dries quickly and does not trap dirt; the hollow structure has excellent drainage, and it dries quickly after washing without leaving any dirt or bacteria, solving the defects of traditional sponges and memory foam that cannot be washed and are prone to trapping dirt. Lightweight and long-lasting anti-collapse: The three-dimensional mesh structure design with three-dimensional through channels saves materials, making the product 40-60% lighter than traditional memory foam of the same volume; Supercritical foaming forms a micron-level closed-cell buffer layer, which greatly improves resilience and fatigue resistance, and will not deform, dent, or lose resilience after more than 5 years of continuous use. High elasticity and quietness: The internal structure forms a uniform micron-level closed-cell buffer layer with excellent cushioning and energy absorption effect. There is no abnormal noise during turning over or being under pressure, avoiding the noise generated by traditional mattresses and soft cushions, and ensuring deep sleep. It can be customized and has high structural dimensional accuracy: No mold is required. The lattice wall thickness, aperture and arrangement density can be adjusted according to different heights, weights and body shapes to achieve ergonomic personalization.

[0016] Furthermore, the foaming material prepared by this invention is environmentally friendly, safe, and harmless: no chemical foaming agents are used throughout the process, no steam foaming is employed, and only supercritical carbon dioxide is used as the foaming medium; the limited raw materials are skin-friendly and safe, water-resistant, aging-resistant, formaldehyde-free, and odorless, making them suitable for use by infants, sensitive individuals, and in medical rehabilitation settings. Attached Figure Description

[0017] Figure 1 For pillows; Figure 2 For baby stroller mats; Figure 3 For shoe insoles; Figure 4 For seat cushions; Figure 5 For mattresses; Figure 6 For mattresses. Detailed Implementation

[0018] This invention provides a method for preparing a foamed material, the foamed material having a three-dimensional network structure, comprising the following steps: The raw materials for foaming are mixed and then printed to obtain a blank with a three-dimensional mesh structure. The blank is subjected to supercritical foaming to form micron-sized closed pores, thereby obtaining the foamed material.

[0019] This invention involves mixing raw materials for foaming and then printing them to obtain a blank with a three-dimensional mesh structure.

[0020] In this invention, the three-dimensional mesh structure preferably includes one or more of the following: a mesh structure formed by multiple layers of interlaced S-shaped corrugations, a square mesh structure, a body-centered cubic mesh structure, and a face-centered cubic mesh structure. Specifically, the body-centered cubic mesh structure and the face-centered cubic mesh structure are three-dimensional periodic lattice crystals with a three-dimensional interlaced hollow framework, exhibiting extremely high specific strength, lightweight, and enhanced stress dispersion and shock absorption performance. The repeated array of single body-centered / face-centered lattice units and the nested micro-porous layers, after foaming, result in a uniform stress distribution due to the nesting of micro and macro lattices. Furthermore, the body-centered cubic mesh structure and the face-centered cubic mesh structure have no sharp corners and feel comfortable against the skin; the mesh structure formed by multiple layers of interlaced S-shaped corrugations provides strong spring-like rebound; and the square mesh structure, with its regularly interlaced horizontal and vertical bars, offers high support strength and good air permeability.

[0021] In this invention, the cross angle of the S-shaped corrugations between adjacent layers in the mesh structure formed by the interlacing of multiple S-shaped corrugations is preferably 45°.

[0022] In this invention, the raw materials preferably include one or more of thermoplastic polyurethane, modified thermoplastic SEBS, polyether block amide, and flexible nylon.

[0023] In this invention, the raw materials for preparing the thermoplastic polyurethane preferably include, by mass fraction, 35-40% MDI-type diisocyanate, 50-55% polyether diol, and 5-15% 1,4-butanediol. The thermoplastic polyurethane prepared from the above raw materials has a Shore hardness of 80-90A, is highly elastic and hydrolysis-resistant, and is suitable for 3D printing and supercritical foaming processes.

[0024] In this invention, the polyether block amide is a block polymer formed by copolymerizing polyamide hard segments nylon 6 or nylon 12 with polyether soft segments. It is ultra-lightweight, highly elastic, resilient, quiet, and resistant to low temperatures without hardening.

[0025] The raw materials for the modified thermoplastic SEBS, by weight, preferably include 70 parts SEBS, 15 parts PP, 20 parts naphthenic oil, 3 parts compatibilizer, 0.3 parts antioxidant, and 5 parts phthalate-free plasticizer. In this invention, the compatibilizer is preferably maleic anhydride-grafted SEBS, the antioxidant is preferably a compound system of antioxidant 1010 and antioxidant 168 with a mass ratio of 1:2, and the phthalate-free plasticizer is preferably tributyl acetyl citrate environmentally friendly plasticizer.

[0026] The raw materials of the flexible nylon, by weight, preferably include 45 parts of nylon 11, 45 parts of nylon 12, 10 parts of toughening agent, 8 parts of flexibility modifier, and 2 parts of wear-resistant additive.

[0027] In this invention, the toughening agent is maleic anhydride-grafted POE elastomer, the flexibility modifier is preferably a polyether block amide elastomer, and the wear-resistant additive is preferably an organosilicon wear-resistant masterbatch. The flexible nylon prepared from the above raw materials exhibits strong support, resistance to deformation, long-term non-collapse, and resistance to water washing and aging.

[0028] In this invention, after printing, the invention preferably further includes annealing the resulting blank.

[0029] In this invention, the annealing temperature is preferably 60~70℃, and the annealing time is preferably 2~4 hours. Annealing can eliminate printing internal stress and improve the structural dimensional stability and mechanical uniformity.

[0030] After obtaining a blank with a three-dimensional network structure, the present invention performs supercritical foaming on the blank to form micron-level closed pores, thereby obtaining the foamed material.

[0031] In this invention, the supercritical foaming preferably includes placing the blank in a supercritical gas for saturated adsorption and depressurization foaming in sequence.

[0032] In this invention, the supercritical gas preferably includes supercritical carbon dioxide.

[0033] In this invention, the preferred saturation adsorption temperature is 80-90℃, the preferred pressure is 18-22 MPa, and the preferred time is 45-75 min. In specific embodiments of this invention, the saturation adsorption temperature can be 85℃ or 88℃, the pressure can be 19 MPa, 20 MPa, or 21 MPa, and the time can be 50 min, 55 min, 60 min, 65 min, or 70 min. This invention uses the above parameters to cause the billet to soften and deform due to high temperature.

[0034] In this invention, the pressure relief rate of the pressure relief foam is preferably 0.2~12MPa / min, and in specific embodiments of this invention, it can be 1MPa / min, 2MPa / min, 3MPa / min, 4MPa / min, 5MPa / min, 6MPa / min, 7MPa / min, 8MPa / min, 9MPa / min, 10MPa / min or 11MPa / min.

[0035] This invention achieves full-area gas permeation through saturated adsorption, and pressure relief foaming enables uniform micropore formation, fully filling the hollow gaps inside the three-dimensional lattice, significantly improving the material's soft and comfortable feel and its quiet cushioning and shock absorption effect.

[0036] After the pressure relief foaming, the present invention preferably further includes: natural cooling.

[0037] The preparation method of this invention requires no water vapor foaming, no chemical foaming agent, no mold constraint, no glue bonding, no sewing assembly, one-piece molding without glue, no inner liner, no splicing, and no hardware parts; it is fully hollowed out for ventilation, can be washed as a whole, dries quickly and is mildew-proof, mite-proof and antibacterial, and is environmentally friendly and recyclable.

[0038] The micron-scale closed-cell layer formed by supercritical foaming can achieve the properties of high elasticity, sound insulation and anti-collapse of foamed materials.

[0039] In this invention, the porosity of the foamed material is preferably 40-65%, and in specific embodiments of this invention it can be 45%, 50%, 55% or 60%.

[0040] In this invention, the diameter of the micron-sized closed pore is preferably 10~40μm, and the closed pore rate is preferably ≥90%.

[0041] In this invention, the density of the foaming material is preferably 0.15~0.5 g / cm³. 3 .

[0042] The present invention also provides the application of the foamed material prepared according to the above technical solution in pillows, mattress cores, lumbar supports, seat cushions or insoles.

[0043] Figures 1-6 Here is a picture of the corresponding prepared physical object: Figure 1 For pillows, Figure 2 For baby stroller mats, Figure 3 For shoe insoles, Figure 4 For seat cushions, Figure 5 For mattresses, Figure 6 For mattresses.

[0044] The preferred applications include ergonomic zoning and gradient design to achieve uniform force distribution, ergonomic gradient support, full-area breathability, lightweight, and customizability.

[0045] Specifically: pillows are divided into head pressure relief zones, neck support zones, and shoulder pressure relief zones; mattress cores are divided into lumbar support zones and hip buffer zones; insoles are divided into forefoot zones, midfoot rebound zones, and heel cushioning zones.

[0046] In this invention, different lattice apertures, wall thicknesses, and densities are used in the aforementioned regions to achieve a soft-hard gradient transition. Specifically: The head pressure relief zone of the pillow has a pore size of 10-12 mm and a wall thickness of 0.8 mm; the neck pressure-bearing zone has a pore size of 6-8 mm and a wall thickness of 1.2 mm; and the shoulder pressure relief zone has a pore size of 8-10 mm and a wall thickness of 1.0 mm.

[0047] The lumbar support area has a corrugation period of 60mm, a wall thickness of 1.2mm, and a porosity of 45-50% to strengthen lumbar support and maintain the physiological curvature of the spine; the lumbar pressure relief area has a corrugation period of 80mm; and the general area has a corrugation period of 70mm, a wall thickness of 1.0mm, and a porosity of 55-60%. The insole has a pore size of 2-3mm and a wall thickness of 0.6mm in the forefoot area, with a porosity of 40-45%; a pore size of 3-4mm and a wall thickness of 0.8mm in the midfoot rebound area, with a porosity of 50-55%; and a pore size of 4-5mm and a wall thickness of 0.7mm in the heel cushioning area, with a porosity of 60-65%. The lattice unit in the central main support area of ​​the seat cushion has a side length of 15mm, a wall thickness of 1.5mm, and a porosity of 40~45%; the lattice unit in the edge protection area has a side length of 20mm, a wall thickness of 1.2mm, and a porosity of 50~55%; and the lattice unit in the general transition area has a side length of 18mm, a wall thickness of 1.3mm, and a porosity of 45~50%.

[0048] Multiple types of three-dimensional mesh structures combined with ergonomic zoned support: one or more of the following can be selected: lattice (the grid in the three-dimensional mesh structure) / porous lattice structure, continuous curved surface lattice, wave-shaped flexible lattice, foot-zoned gradient lattice, and square grid lattice. The zoned gradient design is based on the pressure distribution of the human head, neck, shoulders, waist, hips, and feet. The soft and hard gradients are smoothly transitioned, conforming to the physiological curves of the human body. It does not compress or leave any gaps, and the support comfort is far superior to that of ordinary honeycomb and columnar lattice structures.

[0049] The following detailed description of the preparation method and application of the foaming material provided by the present invention, in conjunction with the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0050] Example 1: A partitioned continuous curved porous lattice neck pillow This embodiment provides a washable, moldable neck support pillow. The main support structure is a continuous curved porous lattice, with a smooth, continuous transition and no sharp edges, resulting in uniform stress distribution. By setting differentiated structural parameters for different zones, it achieves zoned support and pressure relief. The pillow is ergonomically divided into a head pressure-reducing zone, a neck pressure-bearing zone, and a shoulder pressure-relieving zone. The specific parameters of the lattice in each zone are as follows: The head decompression zone is used for flexible support and to disperse head pressure. The lattice (the lattice is the mesh in a three-dimensional grid structure) has a pore size of 10~12 mm and a wall thickness of 0.8 mm.

[0051] The neck pressure zone is designed to provide stable support and maintain the normal physiological curvature of the cervical spine. The lattice aperture is 6-8 mm and the wall thickness is 1.2 mm.

[0052] The shoulder pressure relief area is designed to alleviate shoulder pressure and improve fit comfort. The lattice aperture is 8~10 mm and the wall thickness is 1.0 mm.

[0053] Materials and molding processes 1. Raw material pretreatment and consumable preparation TPU matrix raw material synthesis Raw material pretreatment: Polyether diol was placed in a vacuum drying oven at 110℃ for 2 hours to dehydrate, and the moisture content was controlled to be ≤0.05%; MDI type diisocyanate and 1,4-butanediol were stored at room temperature in a sealed, light-proof container.

[0054] Polymerization reaction: The following materials were fed in a mass ratio of 35% MDI diisocyanate, 55% polyether diol, and 10% 1,4-butanediol. The reaction was carried out using a one-step twin-screw bulk polymerization process. The reaction temperature was controlled at 180~190℃, the screw speed was 150~200rpm, and the material residence time was 3~5min.

[0055] Granulation and maturation: After the reaction is completed, the material is water-cooled, stretched, and granulated to obtain TPU granules; the granules are placed in an 80℃ forced-air drying oven for maturation for 12 hours to finally obtain TPU printing raw material with a Shore hardness of 80A±5A and a moisture content controlled ≤0.03%.

[0056] 2. FDM integrated 3D printing molding Using an Alibaba Cool FDM 3D printer, with a nozzle diameter of 1mm and a layer thickness of 0.6mm, the neck pillow blank is continuously printed in one piece according to the differentiated three-dimensional mesh structure parameters of the head, neck and shoulders, without any splicing gaps, ensuring the dimensional accuracy of the crystal lattice and the consistency of the overall structural mechanics.

[0057] 3. Annealing and shaping of the billet The lattice preform was annealed in a 60-70℃ forced-air drying oven for 4 hours to eliminate printing internal stress and improve structural dimensional stability and mechanical uniformity; after treatment, it was cooled to room temperature in the furnace and then removed.

[0058] 4. Supercritical CO2 high-pressure saturated osmosis The printed blank is placed into a sealed high-pressure reactor, and supercritical carbon dioxide gas is introduced. The process parameters are set as follows: processing temperature 85℃, system pressure 20MPa, and constant temperature and pressure holding time 60min, so that the supercritical fluid can fully penetrate into the gaps between material molecules and the three-dimensional lattice gaps.

[0059] 5. Uniform pressure release, in-situ foaming and shaping The pressure inside the vessel is slowly released at a constant decompression rate of 0.25 MPa / min, and the material foams rapidly and uniformly inside, forming a micron-level closed-cell structure, which simultaneously fills the gaps in the crystal lattice, thereby achieving overall structural soft-hard gradient optimization.

[0060] 6. Cooling and processing of finished products After the pressure is released, the billet is naturally cooled and shaped at room temperature to obtain a finished product of a gradient foamed three-dimensional mesh neck pillow with high resilience, high breathability, and water resistance.

[0061] Usage effect Tests have shown that this partitioned continuous curved porous lattice structure, compared to a single-size lattice structure, provides more balanced pressure distribution at the neck, outstanding pressure dispersion at the head and shoulders, and no localized stress concentration. It is less prone to collapse or deformation with long-term use, significantly improving user comfort.

[0062] Product performance: 45% lighter than memory foam of the same volume, breathability ≥75%, closed cell rate 95%; fully washable, quick-drying and mildew-free, formaldehyde-free and odorless, service life of more than 5 years without sagging; continuous curved structure fits the body without discomfort, providing even and comfortable support.

[0063] Example 2: 3D-printed wave-shaped flexible lattice washable mattress comfort layer This embodiment provides a 3D-printed wave-shaped flexible lattice washable mattress comfort layer. The overall structure uses a three-dimensional wave-shaped continuous flexible lattice as the main support structure, with multiple S-shaped corrugations arranged in an interlaced manner, forming a through-pore channel between the layers, which has excellent breathability, support and flexible pressure relief effect.

[0064] The comfort layer is designed differently based on ergonomic stress distribution, with specific partitions and corresponding lattice parameters as follows: Lumbar support zone (high support, low deformation, precisely supporting the physiological curvature of the lumbar spine and preventing lumbar collapse and suspension): The crystal structure is dense, the corrugation period is 60mm, the wall thickness is 1.2mm, and the porosity is 45~50% to strengthen lumbar support and maintain the physiological curvature of the spine. Buttock pressure relief zone (high flexibility, high resilience, conforms to the curve of the buttocks, disperses concentrated stress in the buttocks due to prolonged sitting / lying): widened lattice structure, 80mm corrugation period, 0.8mm wall thickness, porosity 60~65%, to achieve flexible pressure relief and reduce concentrated pressure in the buttocks; General areas (other body contact areas besides the lumbar support area and hip pressure relief area, such as the back, legs and other areas that do not require high pressure / high support; balancing support and breathability, adaptable to the torso, limbs and other regular contact areas to ensure overall comfort): adopts a standard wave-shaped lattice with a wave period of 70mm, a wall thickness of 1.0mm and a porosity of 55~60%, taking into account both support and breathability.

[0065] The three-dimensional wave-shaped continuous flexible lattice is realized through parametric modeling: S-shaped corrugated units are constructed based on sine wave curves, and multiple layers of units are arranged in an alternating manner at an intersection angle (45°), with interconnected pores naturally formed between the layers; by adjusting the corrugation period, amplitude, wall thickness and porosity parameters, it can be adapted to the support and decompression requirements of different regions.

[0066] In terms of materials, the comfort layer uses TPU material with a Shore hardness of 80A±5A, which is polymerized from MDI-type diisocyanate, polyether diol, and 1,4-butanediol in the following weight ratio: 35% MDI-type diisocyanate, 55% polyether diol, and 10% 1,4-butanediol. This TPU material has excellent elasticity, fatigue resistance, and water resistance, and can be repeatedly washed without significant performance degradation.

[0067] TPU matrix raw material synthesis Raw material pretreatment: Polyether diol was placed in a vacuum drying oven at 110℃ for 2 hours to dehydrate, and the moisture content was controlled to be ≤0.05%; MDI type diisocyanate and 1,4-butanediol were stored at room temperature in a sealed, light-proof container.

[0068] Polymerization reaction: The following materials were fed in a mass ratio of 35% MDI diisocyanate, 55% polyether diol, and 10% 1,4-butanediol. The reaction was carried out using a one-step twin-screw bulk polymerization process. The reaction temperature was controlled at 180~190℃, the screw speed was 150~200rpm, and the material residence time was 3~5min.

[0069] Granulation and maturation: After the reaction is completed, the material is water-cooled, stretched, and granulated to obtain TPU granules; the granules are placed in an 80℃ forced-air drying oven for maturation for 12 hours to finally obtain TPU printing raw material with a Shore hardness of 80A±5A and a moisture content controlled ≤0.03%.

[0070] II. FDM Particle 3D Printing of Lattice Preforms Pre-printing drying: Place the cured TPU particles in an 80℃ vacuum drying oven for 4~6 hours to completely remove residual moisture and avoid defects such as bubbles and broken filaments during the printing process.

[0071] Printing process parameters: One-piece molding using a pellet-feed FDM 3D printer. Nozzle diameter 0.6mm, print layer thickness 0.3mm, print line width 0.7mm; Nozzle temperature 210~230℃, heated bed temperature 50~60℃; Printing speed 40~60mm / s, interlayer rotation and stagger angle 45°; The parameters of corrugation period, wall thickness, and porosity are set separately for each functional zone, and the S-shaped corrugation path is continuously laid out.

[0072] Rough processing of the blank: After printing, the blank is naturally cooled to room temperature, and the edge burrs and a small amount of auxiliary support are removed to obtain a lattice blank with a three-dimensional through-network structure.

[0073] III. Annealing and Shaping of the Green Body The lattice preform was annealed in a 60-70℃ forced-air drying oven for 4 hours to eliminate printing internal stress and improve structural dimensional stability and mechanical uniformity; after treatment, it was cooled to room temperature in the furnace and then removed.

[0074] IV. Supercritical CO2 foaming molding Saturated adsorption: The annealed preform is placed in a supercritical foaming reactor, CO2 is introduced and the temperature and pressure are increased to the supercritical state. The saturation temperature is controlled at 80~90℃ and the saturation pressure at 22MPa. The adsorption is carried out for 4 hours under heat and pressure to allow CO2 to dissolve uniformly into the TPU matrix.

[0075] Depressurization foaming: After reaching saturation time, the pressure is rapidly reduced to atmospheric pressure at a rate of 10 MPa / s, and the temperature of the vessel is kept stable during the depressurization process; after depressurization, the sample is taken out to obtain a finished product of a wave-shaped flexible lattice comfort layer containing micron-sized closed pores.

[0076] Tests have shown that, compared to traditional foam mattresses, the wave-shaped flexible lattice comfort layer of this embodiment offers the following advantages: the lumbar support area has approximately 25% higher support stiffness, effectively reducing lumbar sagging; the contact pressure in the buttocks pressure relief area has decreased by approximately 20%, resulting in significant pressure dispersion; and overall breathability has increased by approximately 40%, allowing for rapid wicking away of body moisture and enhancing sleep comfort.

[0077] Example 3: 3D Printed Partitioned Lattice Washable Cushioning Insole This embodiment provides a 3D-printed partitioned lattice washable shock-absorbing insole. The overall design adopts a foot pressure partitioned lattice design. According to the stress characteristics of different areas during walking and running, different lattice structures and parameters are matched to achieve a synergistic effect of shock absorption, support and breathability.

[0078] I. Structural and Zonal Design: The insole is divided into three functional zones according to the force distribution on the sole of the foot. The lattice structure and parameters of each zone are as follows: Forefoot area: It adopts a fine small-pore lattice with a pore size of 2~3mm, a wall thickness of 0.6mm, and a porosity of 40~45%, which mainly provides support and anti-slip performance, while ensuring the breathability of the forefoot; Midfoot region: A rhomboid medium-aperture lattice with a pore size of 3-4 mm, a wall thickness of 0.8 mm, and a porosity of 50-55% is used, which mainly plays the role of stabilizing the arch of the foot and transmitting force. Heel area: It adopts a large-pore, highly elastic lattice with a pore size of 4~5mm, a wall thickness of 0.7mm, and a porosity of 60~65%. The large-pore structure absorbs the impact force of landing and achieves excellent shock absorption effect.

[0079] II. Material Formula The insole is made of TPU material with a Shore hardness of 85A, polymerized from MDI diisocyanate, polyether diol, and 1,4-butanediol in the following weight ratio: MDI diisocyanate: 35%; polyether diol: 60%; 1,4-butanediol: 15%. This TPU material formulation combines excellent elasticity, fatigue resistance, and hydrolysis resistance, and can be repeatedly washed without significant performance degradation, making it suitable for washable applications.

[0080] Raw material pretreatment: Polyether diol was placed in a vacuum drying oven at 110℃ for 2 hours to dehydrate, and the moisture content was controlled to be ≤0.05%; MDI type diisocyanate and 1,4-butanediol were stored at room temperature in a sealed, light-proof container.

[0081] Polymerization reaction: MDI type diisocyanate, polyether diol and 1,4-butanediol are fed in the mass ratio and a one-step bulk polymerization is carried out using a twin-screw extruder; the reaction temperature is controlled at 180~190℃, the screw speed is 150~200rpm, and the material residence time is 3~5min.

[0082] Granulation and maturation: After the reaction is completed, the material is water-cooled, stretched, and granulated to obtain TPU granules; the granules are placed in an 80℃ forced-air drying oven for maturation for 12 hours to finally obtain TPU printing raw material with a Shore hardness of 80A±5A and a moisture content controlled ≤0.03%.

[0083] III. Molding and Post-processing Technology Molding process: FDM particles are used for one-piece 3D printing. The printing nozzle diameter is 0.4mm and the printing layer thickness is 0.2mm. It can achieve precise molding of the crystal structure in different regions, ensuring the consistency of parameters and structural stability of each region.

[0084] Annealing and shaping of the billet The lattice preform was placed in a 60-70℃ forced-air drying oven for constant-temperature annealing for 4 hours to eliminate printing internal stress and improve structural dimensional stability and mechanical uniformity; after treatment, it was cooled to room temperature in the furnace and then removed.

[0085] Supercritical foaming process: The printed insoles are treated with a supercritical CO2 foaming process with the following parameters: temperature 80℃, pressure 18MPa, holding time 60min, and decompression rate 0.2MPa / min. After treatment, a uniform microbubble structure is formed inside the material, which can further improve the resilience and cushioning performance of the insole, while optimizing the feel.

[0086] IV. Product Performance Verification Tests have shown that the partitioned lattice insole of this embodiment has the following performance advantages: it can be washed as a whole, with no dead corners for dirt and grime to hide, and can be dried quickly after washing; its rebound rate is ≥70%, and its shock absorption performance is better than that of traditional EVA insoles, reducing the impact force upon landing by about 25%; it is not easily deformed or collapsed after long-term wear, and its support retention rate is ≥90%; its overall breathability is improved by more than 50%, which can effectively expel moisture from the feet and reduce stuffiness.

[0087] Example 4: 3D Printed Square Lattice Washable Mattress Support Layer This embodiment provides a 3D printed square lattice washable mattress support layer. The whole uses a square porous lattice as the main support structure. The lattice units are arranged in a regular array, which has high support, structural stability and washability, and can be used as the core load-bearing layer of the mattress.

[0088] I. Structural and Zoning Design The support layer adopts a square lattice structure, with differentiated lattice parameters set according to the stress requirements of different areas of the mattress. The specific partitions are as follows: The central main support area is divided according to the high-pressure stress area of ​​the human body's core when lying down. It covers the main weight-bearing parts of the human body's waist, back, and hip spine. This area bears most of the body's own weight pressure for a long time. Therefore, a high-density, dense square lattice structure is adopted to ensure long-term deformation resistance support with high structural strength.

[0089] The general transition zone is the connecting structure between the central main support zone and the edge protection zone. It adopts a standard square lattice to achieve a smooth transition in the softness and hardness of the adjacent zones, avoid sudden changes in local stress in the mattress, and ensure uniform and consistent force distribution when lying down.

[0090] Central main support area: adopts a dense square lattice with a lattice unit side length of 15mm, a wall thickness of 1.5mm, and a porosity of 40~45% to provide high support strength and adapt to the main stress areas of the human torso. Edge protection zone: A widened square lattice is adopted, with a lattice unit side length of 20mm, a wall thickness of 1.2mm, and a porosity of 50~55%, which improves the flexible transition and impact resistance of the edge while ensuring support. General transition zone: adopts a standard square lattice with a lattice unit side length of 18mm, a wall thickness of 1.3mm, and a porosity of 45~50%, to achieve a smooth transition between different regions and ensure uniform stress distribution.

[0091] The square lattice is generated through parametric modeling. It uses regular cubes as basic units and expands into an overall structure through an array. By adjusting parameters such as unit side length, wall thickness, and porosity, it can be adapted to different support strength and hardness requirements.

[0092] II. Material Formula The support layer is made of high-support TPU material with a Shore hardness of 90A, polymerized from MDI diisocyanate, polyether diol, and 1,4-butanediol in the following weight ratio: MDI diisocyanate: 40%; polyether diol: 52%; 1,4-butanediol: 12%. This TPU formulation exhibits excellent rigidity and creep resistance, resisting deformation under long-term pressure. It also possesses good hydrolysis and fatigue resistance, making it suitable for the long-term use requirements of washable mattresses.

[0093] III. Molding and Post-processing Technology Raw material pretreatment: Polyether diol is added to the reactor, heated to 110~120℃, vacuum dehydrated for 2~3h, and the moisture content is tested to be ≤0.05% before cooling to 60℃ for later use; MDI and 1,4-butanediol are dehydrated by molecular sieve, and the moisture content is controlled to be ≤0.03%.

[0094] Continuous polymerization: The twin-screw one-step bulk polymerization process is adopted. The three components are precisely metered according to the ratio and fed into the twin-screw extruder simultaneously. The temperature of each section of the screw is set to 170℃, 180℃, 190℃, 195℃, 190℃ and 185℃ respectively, the screw speed is 180~220rpm, and the material residence time is 4~6min to complete the polymerization reaction.

[0095] Granulation and maturation: The molten material is extruded through a die, water-cooled and stretched into strips, and then cut into granules to obtain native TPU granules; the granules are placed in an 85~90℃ forced-air drying oven for 16 hours to allow the molecular chains to fully react and become uniform, ultimately obtaining high-support TPU printing granules with a Shore hardness of 90A.

[0096] II. 3D Printing Process of Square Lattice Support Layer The process uses a pellet-feed FDM 3D printer for one-piece molding. Specific process parameters are as follows: Drying before printing: Dry the TPU particles in an 85℃ vacuum drying oven for 6~8 hours to ensure that the moisture content is ≤0.03% to avoid defects such as air holes and broken filaments during printing.

[0097] Core printing parameters Nozzle diameter: 0.6mm Printing layer thickness: 0.3mm, printing line width: 0.65~0.7mm Nozzle temperature: 220~240℃, heated bed temperature: 60~70℃ Printing speed: 35~50mm / s Lattice arrangement: Square orthogonal grid, with layers arranged perpendicularly at 90° intervals, allowing for precise control of wall thickness and porosity according to design parameters. Rough processing of the blank: After printing, the blank is naturally cooled to room temperature, the base plate is peeled off, and the edge flash is removed to obtain a square three-dimensional through lattice blank.

[0098] III. Supercritical CO2 foaming process Loading, pressurizing, and heating: Place the lattice blank flat into the supercritical foaming reactor, seal it, and introduce CO2. Gradually increase the temperature and pressure to the supercritical state; control the saturation temperature at 85~95℃ and the saturation pressure at 20~24MPa.

[0099] Saturated adsorption: Adsorption for 5 hours under heat and pressure conditions allows CO2 to diffuse uniformly into the TPU matrix, forming a homogeneous system.

[0100] Rapid depressurization foaming: After reaching saturation time, the pressure is rapidly reduced to atmospheric pressure at a rate of 12 MPa / s; during the depressurization process, the temperature fluctuation of the vessel is maintained at ≤±2℃ to ensure uniform and fine foam cells.

[0101] Cooling and shaping: After depressurization, the sample is immediately taken out and allowed to cool and shape at room temperature to obtain the finished product of the foamed lattice support layer containing micron-level closed pores.

[0102] IV. Post-processing and shaping (enhancing creep resistance) The foamed support layer is annealed in a 70-80℃ forced-air oven for 4 hours to eliminate printing and foaming internal stress, stabilize the lattice size, and further improve the long-term pressure resistance and creep resistance. After the treatment is completed, it can be cooled to room temperature in the oven.

[0103] V. Product Performance Verification Tests have shown that the square lattice support layer of this embodiment has the following performance advantages: it is washable as a whole, with no dead corners for dirt to hide, and the dimensional change rate after washing is ≤1%, exhibiting excellent structural stability; it has high support strength, with a static compression rate of ≤10%, and does not collapse under long-term pressure, maintaining the long-term support performance of the mattress; its overall breathability is improved by more than 60%, allowing for rapid expulsion of body moisture and reducing stuffiness; its structure is uniform, with even stress distribution and no localized stress concentration, making it less prone to dents or deformation after long-term use.

[0104] Comparative Example 1: Traditional polyurethane memory foam sleep products Made using chemical foaming molding, it has a solid, unpartitioned lattice structure; the support is singular and cannot achieve ergonomic gradient support; the solid structure has poor breathability, and in summer, it is hot and sweaty, which can easily breed mites and mold; the chemical foaming process leaves residual formaldehyde and irritating odor, making it unsuitable for sensitive people and infants; it cannot be washed with water as a whole, and can only be wiped on the surface; it loses its elasticity and becomes dented and deformed after 1-2 years of use, resulting in a short service life.

[0105] Comparative Example 2: Existing 3D printed products with supercritical two-step foaming It employs a two-step process of infiltration and steam foaming, requiring an external foaming chamber, steam generator, mold, and air nozzle equipment; it lacks an ergonomic partitioned lattice design and a gradient support structure for the head, neck, shoulders, waist, hips, and feet, making it only suitable for shoe soles, toys, and general industrial products; it does not have washable, silent pressure relief, or ergonomic sleep support functions, and cannot be applied to high-end pillows, mattresses, cushions, or insoles.

[0106] Figure 1 For use as a pillow.

[0107] Figure 2 For baby stroller mats.

[0108] Figure 3 For shoe insoles.

[0109] Figure 4 For use as a seat cushion.

[0110] Figure 5 For mattresses.

[0111] Figure 6 For mattresses.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a foamed material, characterized in that, Includes the following steps: The raw materials for foaming are mixed and then printed to obtain a blank with a three-dimensional mesh structure. The blank is subjected to supercritical foaming to form micron-sized closed pores, thereby obtaining the foamed material; The foamed material has a three-dimensional mesh structure with three-dimensional through channels.

2. The preparation method according to claim 1, characterized in that, The three-dimensional mesh structure includes one or more of the following: a mesh structure formed by multiple layers of S-shaped corrugations arranged in an alternating pattern; a square mesh structure; a body-centered cubic mesh structure; and a face-centered cubic mesh structure.

3. The preparation method according to claim 1, characterized in that, The raw materials include one or more of thermoplastic polyurethane, modified thermoplastic SEBS, polyether block amide, and flexible nylon.

4. The preparation method according to claim 3, characterized in that, The raw materials for preparing the thermoplastic polyurethane, by mass fraction, include 35-40% MDI-type diisocyanate, 50-55% polyether diol, and 5-15% 1,4-butanediol; The modified thermoplastic SEBS raw materials, by weight, include 70 parts SEBS, 15 parts PP, 20 parts naphthenic oil, 3 parts compatibilizer, 0.3 parts antioxidant, and 5 parts phthalate-free plasticizer; By weight, the raw materials of the flexible nylon include 45 parts of nylon 11, 45 parts of nylon 12, 10 parts of toughening agent, 8 parts of flexibility modifier, and 2 parts of wear-resistant additive.

5. The preparation method according to claim 1, characterized in that, The supercritical foaming process involves placing the billet in a supercritical gas and sequentially performing saturated adsorption and depressurization foaming.

6. The preparation method according to claim 5, characterized in that, The supercritical gas includes supercritical carbon dioxide.

7. The preparation method according to claim 5, characterized in that, The saturation adsorption temperature is 80~90℃, the pressure is 18~22MPa, and the time is 45~75min.

8. The preparation method according to claim 5, characterized in that, The depressurization rate of the depressurization foam is 0.2~12MPa / min.

9. The preparation method according to claim 1, characterized in that, The porosity of the three-dimensional network structure in the blank is 40-65%; the diameter of the micropores is 10-40 μm, and the closed-pore rate is ≥90%.

10. The use of the foamed material prepared by the preparation method according to any one of claims 1 to 9 in pillows, mattress cores, lumbar supports, seat cushions or insoles.

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