Preparation method of multi-layer soft sofa

Abstract

The invention relates to the technical field of furniture manufacturing, and discloses a preparation method of a multi-layer soft sofa, which comprises the following steps: mixing inorganic non-metal functional particles and a liquid adhesive to prepare slurry, infiltrating the slurry into a flexible porous fiber base material by adopting an impregnation process, and drying to form a functional composite layer; constructing a contact comfort layer, a main buffer layer and a bottom support layer capable of dispersing body pressure and preventing grounding; the functional composite layer is used as a middle layer, is arranged between the main buffer layer and the bottom supporting layer, and is covered with the contact comfortable layer to form a four-layer laminated body; all the layers of the four-layer combination body are combined into a whole to form the sofa inner container; and mounting the sofa liner on the sofa frame to obtain the multi-layer soft sofa. The sofa prepared by the invention has excellent soft comfort, lasting supporting property, intrinsic flame-retardant safety and long-acting structural durability.

Description

Technical Field

[0001] This invention relates to the field of furniture manufacturing technology, and in particular to a method for preparing a multi-layered soft sofa. Background Technology

[0002] The core value of upholstered furniture, especially sofas, lies in providing users with a comfortable sitting and lying experience. To achieve this goal, existing technologies generally adopt a multi-layered flexible material composite structure, such as using high-resilience foam, slow-resilience memory foam, doll foam, and individually pocketed springs, etc., to shape the seating feel by combining different materials with varying degrees of firmness.

[0003] However, this layered structure based on traditional organic polymer materials has inherent technical bottlenecks. First, there is an irreconcilable contradiction between the mechanical properties of the material and its comfort: while overly soft materials may initially feel comfortable, they lack support, easily leading to unstable posture, muscle fatigue, and even cushion collapse after prolonged use; conversely, increasing the material's hardness to improve support significantly sacrifices the sofa's softness and comfort. Second, core materials such as polyurethane foam and plush toy cotton are flammable, posing a fire hazard, and their combustion produces large amounts of toxic fumes.

[0004] To improve performance, existing technologies have attempted to introduce functional materials, such as embedding flame-retardant felt or rigid insulation boards within the sponge layer. However, these solutions often introduce new problems: the introduction of rigid or semi-rigid functional materials can severely compromise the overall softness and deformation consistency of the sofa, resulting in localized hard lumps on the seat surface. Furthermore, after long-term use, the significant difference in modulus between the functional layer and the flexible cushioning layer makes them prone to peeling and rattling at the interface, seriously affecting the lifespan and user experience.

[0005] Therefore, existing technologies lack a systematic solution that can seamlessly integrate high-strength, high-flame-retardant, and high-heat-insulating properties without sacrificing or even enhancing the softness and comfort of a sofa, while ensuring long-term stability of the interlayer bonding. Therefore, this invention proposes a method for manufacturing a multi-layered soft sofa. Summary of the Invention

[0006] The purpose of this invention is to address the problems in existing technologies, such as easy separation between layers, imbalance between support and comfort, and difficulty in effectively combining inorganic functional materials with flexible sofa structures, by proposing a method for preparing a multi-layered soft sofa.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a multi-layered soft sofa, comprising the following steps: Step S1, in-situ construction of the functional composite layer: Inorganic non-metallic functional particles with a particle size distribution satisfying D50 between 10-100 micrometers and D90 not exceeding 200 micrometers are mixed with an environmentally friendly water-based polymer adhesive under constant speed stirring to form a uniform slurry with a solid content of 30%-60%; Subsequently, a flexible porous fiber substrate with a three-dimensional interconnected network structure is completely immersed in the slurry and placed in a negative pressure environment with a vacuum degree of -0.08MPa to -0.1MPa for 3-10 minutes to drive the slurry to fully penetrate and fill most of the pores of the fiber substrate; Afterwards, the impregnated composite is transferred to a circulating hot air drying oven at 80℃-120℃ and cured for 1 to 3 hours to complete the curing and shaping, finally forming a functional composite layer that can be freely bent and folded on a macroscopic scale and has durable functional properties on a microscopic scale; Step S2, Precise Configuration of the Gradient Buffer System: Based on the ergonomic sitting posture pressure distribution model, three flexible materials with different mechanical properties are prepared to construct a continuous gradient buffer system from a soft outer layer to a solid inner layer. Specifically, this includes: selecting a slow-rebound polyurethane foam with a density of 30-50 kg / m³ and a rebound time greater than 5 seconds as the contact comfort layer that comes into direct contact with the human body; selecting a high-rebound polyurethane foam with a density of 40-60 kg / m³ and a rebound rate greater than 60% as the main buffer layer that supports the weight of the human body and disperses body pressure; and selecting a high-density sponge with a density of not less than 60 kg / m³ or an elastic system composed of multiple independent pocket springs as the bottom support layer that provides ultimate support and prevents the sitting sensation from hitting the bottom. The static compression modulus of the contact comfort layer, the main buffer layer, and the bottom support layer must meet the requirement of increasing sequentially, with their ratio controlled within the range of 1:(1.5 to 3.0):(3.0 to 8.0). Step S3: Complete the construction of the four-layer composite structure: The functional composite layer prepared in step S1 is used as the core intermediate layer and is precisely placed between the main buffer layer and the bottom support layer prepared in step S2, ensuring that its planar projection area is less than 90% of the area of ​​the main buffer layer, so that it is covered inside the buffer system in a non-continuous "island" form; then, the contact comfort layer is completely covered on the main buffer layer to form a four-layer composite structure from bottom to top: "bottom support layer - functional composite layer - main buffer layer - contact comfort layer"; Step S4, Integrated molding of the sofa inner lining: The four-layer composite formed in step S3 is integrated using any one of the three physical methods: needle punching, quilting, or high-frequency heat fusion. When needle punching is used, a special needle with side barbs is used to repeatedly puncture the composite at a puncture density of 20-50 needles / square centimeter and a puncture depth of 70%-95% of the total thickness of the composite. This forces the fibers of each layer of material to be hooked together and entangled, forming a mechanically interlocked, chemical-free integral structure in three-dimensional space, i.e., the sofa inner lining. Step S5, final assembly of the sofa: The integrated sofa liner obtained in step S4 is fixed to the corresponding load-bearing surface of a pre-prepared wooden or metal sofa frame through mechanical connectors. Then, the flexible shape of the armrests and the top of the backrest is filled, and the flame-retardant pre-treated outer fabric is fitted on. Finally, the sofa legs are installed to complete the final production of the multi-layer soft sofa.

[0008] The beneficial effects of the technical solution provided by this invention include at least the following: This invention introduces a functional composite layer composed of inorganic non-metallic functional particles into the interior of the sofa cushion, which can fundamentally improve the inherent safety and physical function of the product. It can simultaneously endow the sofa with excellent flame retardant properties and efficient heat insulation performance, solving the technical problems of traditional organic materials being flammable and having limited functions.

[0009] This invention constructs a scientific gradient buffer system by using a contact comfort layer, a main buffer layer, and a bottom support layer with progressively increasing compression modulus. This system can achieve gradual dispersion and gentle support of human body pressure, providing an extremely soft and enveloping feel on the contact surface, while effectively preventing unstable sitting posture and bottoming out through solid support at the bottom layer, thus perfectly balancing the inherent contradiction between comfort and support.

[0010] This invention abandons traditional chemical adhesives and instead uses physical composite methods such as needle punching, quilting, or high-frequency hot melting to bond the layers together. This completely solves the problem of interlayer delamination caused by differences in material properties. This three-dimensional mechanical interlocking or interface anchoring bonding method has a lifespan equal to that of the material itself, thereby greatly improving the structural durability and reliability of the product under long-term dynamic loads and avoiding abnormal noises and local collapse. Attached Figure Description

[0011] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the method flow provided in an embodiment of the present invention; Figure 2 A flowchart illustrating the sofa assembly process provided in an embodiment of the present invention. Detailed Implementation

[0013] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a method for preparing a multi-layer soft sofa according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0015] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0016] Traditional sofa manufacturing processes face inherent technical contradictions and performance limitations in balancing a soft seating experience with long-term durability. Existing technologies cannot systematically integrate advanced functions such as fire resistance and heat insulation while maintaining the overall softness and comfort of the sofa, nor can they guarantee the structural durability under long-term dynamic loads.

[0017] For example, suppose that during the manufacturing process of a home living room sofa, the manufacturer attempts to improve the product's safety by incorporating a rigid fireproof board. This fireproof board is simply laminated between the layers of foam in the seat cushion. In short-term static testing, the sofa might meet basic fire resistance requirements. However, in long-term daily use, this design will trigger a series of chain reactions: when users repeatedly sit on the edge of the sofa, due to the mismatch in mechanical properties between the rigid fireproof board and the surrounding flexible foam, and the fact that the two are only bonded by adhesive, a noticeable localized hardness will gradually develop in that edge area, compromising comfort. More seriously, under long-term, repeated sitting pressure and deformation, the rigid board and flexible foam will generate shear stress at the interface due to deformation incompatibility, eventually leading to aging and failure of the interlayer adhesive, internal delamination, abnormal noise, and even localized collapse.

[0018] If these issues are not resolved, manufacturers will face a dilemma: either abandon the introduction of functional materials, accepting the lack of safety and added features in their products; or sacrifice comfort and lifespan, bearing the resulting customer complaints and high return rates. These issues of decreased comfort and structural durability caused by material interface failure and mismatched mechanical properties directly impact the user experience and market lifecycle of sofa products, hindering technological upgrades and value enhancement. The following describes in detail, with reference to the accompanying drawings, a specific scheme for the preparation method of a multi-layer soft sofa provided by the present invention.

[0019] Please see Figure 1 and Figure 2 It illustrates a method flow diagram and a sofa assembly flowchart of a method for preparing a multi-layer soft sofa according to an embodiment of the present invention, including the following steps: Step S1: Inorganic non-metallic functional particles are mixed with liquid adhesive to form a slurry, and an impregnation process is used to allow the slurry to penetrate into the flexible porous fiber substrate. After drying, a functional composite layer is formed. Step S2: Prepare flexible materials with progressively increasing compression modulus to construct a contact comfort layer, a main buffer layer, and a bottom support layer that can disperse body pressure and prevent bottoming out. Step S3: Place the functional composite layer as an intermediate layer between the main buffer layer and the bottom support layer, and then cover it with the contact comfort layer to form a four-layer composite. Step S4: Through physical methods such as needle punching, quilting, or high-frequency heat melting, the layers of the four-layer composite are joined together to form the sofa inner lining. Step S5: Install the sofa inner liner onto the sofa frame to obtain a multi-layered soft sofa.

[0020] It should be noted that inorganic non-metallic functional particles refer to a class of micron or nano-sized solid particles that do not contain a carbon chain skeleton and can provide specific functions to materials through physical or chemical processes. In this invention, the core objective is to upgrade the traditional sofa's single "softness" function to a composite structure and integrated functional characteristic. The particles can be selected from, but are not limited to: hollow ceramic microspheres (for lightweight thermal insulation), aluminum hydroxide or magnesium hydroxide (for flame retardancy), and natural mineral powders such as tourmaline or kiwistone (for releasing negative ions or far-infrared rays). These particles can be used alone or in combination to achieve synergistic and multiplicative functional effects.

[0021] Flexible porous fiber substrate refers to a carrier material with a three-dimensional interconnected network structure, capable of being permeated by slurry, and providing macroscopic flexibility. Its purpose is to provide a stable, deformable support framework for functional particles, and its high porosity ensures a high loading capacity for the functional particles. The substrate can be selected from, but is not limited to, three-dimensional mesh structures such as polyester cotton, doll cotton, or hot-air cotton. The fibers of these materials are physically entangled or thermally bonded to form an elastic spatial structure capable of withstanding repeated bending and compression.

[0022] A gradient cushioning system with progressively increasing compressive modulus refers to a scientific structure consisting of a comfort contact layer, a main cushioning layer, and a bottom support layer, where the material's resistance to compressive deformation (i.e., compressive modulus) increases progressively. The mechanical principle behind this design is as follows: when a person sits down, the soft comfort contact layer undergoes large deformation first, providing a feeling of envelopment and distributing pressure over a larger area; subsequently, the firmer main cushioning layer provides core rebound and support, further optimizing pressure distribution; finally, the high-modulus bottom support layer prevents the entire structure from being completely compressed (i.e., hitting the bottom). This "soft-medium-firm" gradient design is the structural basis for achieving a balance between soft seating comfort and stable support.

[0023] The island-shaped embedded structure is a specific spatial configuration where the planar projection outline of the functional composite layer is completely contained within the projection outline of its adjacent layer (specifically the main cushioning layer), and its periphery maintains a safe distance from the periphery of the main cushioning layer. The core purpose of this structure is to create a flexible buffer zone without functional layers. This design ensures that when a user sits on the edge of the sofa, the area where their buttocks and upper thighs come into contact with and are compressed is always made entirely of flexible cushioning material, thus physically eliminating the edge hardness or discomfort that functional composite layers might cause.

[0024] Physical bonding is an interlayer bonding technology distinct from traditional chemical adhesives, relying on mechanical interlocking or physical field effects to achieve bonding. Its core value lies in avoiding the interlayer delamination failure mode caused by long-term aging and fatigue of chemical adhesives. The needle punching, quilting, and high-frequency hot-melt methods protected by this invention respectively form three-dimensional fiber entanglement, through-hole stitching, and interface anchoring microstructures between layers. The lifespan of these structures is equivalent to that of the material itself, thereby greatly improving the product's durability.

[0025] The sofa inner liner refers to the core module of the sofa after all functional and cushioning layers have been laminated and integrated, but before the outer cover and legs are installed. Producing and quality-controlling it as an independent "sub-component" facilitates standardized and modular production, makes it easier to identify defects before final assembly, and improves production efficiency and product consistency. This solution systematically overcomes the bottlenecks in traditional sofa manufacturing through a series of synergistic technical means.

[0026] First, a functional composite layer is prepared through slurry impregnation and drying. This step aims to resolve the contradiction between functional integration and maintaining flexibility. The key lies in breaking down and anchoring the originally rigid inorganic functional particles (such as aerogel and flame retardants) within a flexible three-dimensional fiber network. This creates a completely new material: macroscopically, it can be bent and folded like a piece of cloth or thick cotton, adapting to the deformation of the sofa; microscopically, it is filled with functional particles. This avoids the overall rigidity problem caused by simply placing a rigid functional board, achieving a unity of function and flexibility.

[0027] Subsequently, the synergistic design of the gradient buffer system and the island-shaped embedded structure resolved the contradiction between support, comfort, and localized hardness.

[0028] The gradient cushioning system (increasing compression modulus) ensures that when a person sits down, the pressure starts from the softest contact comfort layer, is effectively dispersed by the main cushioning layer, and is finally firmly supported by the bottom support layer. This "soft-medium-firm" transition fundamentally prevents instability and collapse caused by an overly soft single material, and also avoids sacrificing comfort due to an overall overly firm material.

[0029] The island-shaped embedding is a clever design that ensures comfort. By ensuring that the functional composite layer has a smaller area and is completely surrounded by the soft main cushioning layer, it physically isolates the functional layer from direct contact with the human body. No matter where the user sits on the sofa seat, their body is in contact with soft foam cushioning material, thus completely eliminating the discomfort caused by introducing functional rigid materials, such as edge chafing and localized hard lumps.

[0030] Next, a physical composite method is used to replace chemical adhesives, aiming to fundamentally solve the durability problem of easy peeling between layers. Whether it is the mechanical interlocking of fibers formed by needle punching or the interface anchoring points formed by high-frequency heat melting, the bonding strength is equivalent to the material's lifespan, and it will not age or powder over time like organic adhesives. This ensures that under long-term, repeated pressure deformation, heterogeneous materials will not separate, misalign, or produce abnormal noises, greatly improving the product's service life and structural integrity.

[0031] Finally, through modular assembly, the fully functional integrated inner liner and frame are combined, achieving efficient and reliable production.

[0032] In some preferred embodiments, this application is implemented as follows: In step S1, hollow glass microspheres with a particle size distribution satisfying a D50 of 50 micrometers and a D90 not exceeding 150 micrometers are selected as inorganic non-metallic functional particles. These particles are mixed with an aqueous polyurethane dispersion with a solid content of 40%, and stirred at 400 rpm for 40 minutes to form a uniform slurry. A three-dimensional mesh polyester cotton with an areal density of 300 g / m² is completely immersed in the slurry and placed in a vacuum environment of -0.08 MPa to -0.1 MPa for 3-10 minutes to drive slurry penetration. Subsequently, the vacuum is released, and the impregnated composite is transferred to a circulating hot air drying oven at 100°C for curing for 2 hours, ultimately forming a macroscopically flexible functional composite layer.

[0033] In step S2, a defined gradient system is configured: a slow-rebound sponge with a compression modulus of 30 kPa is selected as the contact comfort layer (4 cm thick); a high-rebound sponge with a compression modulus of 75 kPa is selected as the main cushioning layer (7 cm thick); and a high-density sponge with a compression modulus of 200 kPa is selected as the bottom support layer (8 cm thick). The ratio of the compression moduli of the three is approximately 1:2.5:6.7.

[0034] In step S3, the bottom support layer and the main cushioning layer are first stacked one on top of the other. Then, the functional composite layer is cut into a rectangle 8 cm smaller in both length and width than the main cushioning layer, and precisely placed in the center of the upper surface of the main cushioning layer. During placement, it is ensured that the indentation distance between each side of the composite layer and the corresponding side of the main cushioning layer is within the range of 3 to 6 cm, and that the indentation distance of any boundary is greater than the maximum deformation depth of the main cushioning layer at the edge of the sofa seat when a person sits on it. This achieves uniform boundary coverage and ensures comfort, forming a standard island-shaped embedded structure. Finally, the contact comfort layer is completely covered on top, forming a four-layer composite structure from bottom to top: "bottom support layer - functional composite layer - main cushioning layer - contact comfort layer".

[0035] In step S4, a high-frequency hot melt method is selected, and a layer of low-melting-point (110℃) copolyamide hot melt adhesive web is laid at the interface between the functional composite layer and the upper and lower sponge layers. The composite is placed under a high-frequency electric field and heated for 20 to 40 seconds in the frequency range of 26MHz to 28MHz, so that the adhesive film melts and penetrates into the pores of the adjacent materials. After cooling, a strong interface anchoring structure is formed.

[0036] In step S5, L-shaped metal connectors are used to securely connect the sofa inner lining to the mortise and tenon structure of the ash wood frame. The curved shapes of the armrests and the top of the backrest are filled with a combination of plush cotton to achieve a natural transition. Finally, flame-retardant linen fabric with a limiting oxygen index greater than 32% is fitted on top, and height-adjustable metal sofa legs are installed to complete the production of the multi-layered soft sofa.

[0037] Step S1 further includes the following sub-steps: S1-1, Inorganic non-metallic functional particles are mixed with environmentally friendly liquid binders to form a uniform slurry; the inorganic non-metallic functional particles include hollow ceramic microspheres, metal hydroxides, and natural mineral powders with far-infrared emission or negative ion release functions; the environmentally friendly liquid binders include water-based polymer dispersions and bio-based binders. S1-2, a flexible porous fiber substrate with a three-dimensional interconnected network structure is immersed in slurry and a vacuum negative pressure is applied to allow the slurry to penetrate and fill the pores of the fiber substrate to form an impregnated composite. S1-3, the impregnated composite is dried to cure the liquid adhesive, fixing the inorganic non-metallic functional particles into the fiber network of the flexible porous fiber substrate to form a functional composite layer.

[0038] Furthermore, in sub-step S1-2, after applying vacuum negative pressure, a secondary pressure impregnation step is also included: After the vacuum is released, the flexible porous fiber substrate and the slurry are transferred together into a sealed pressure vessel; Compressed gas is injected into the pressure vessel to create a static positive pressure environment inside that is higher than atmospheric pressure. Under this positive pressure environment, the slurry is driven by pressure to penetrate and fill the deep pores of the fiber substrate and the gaps between fiber bundles; Release the pressure and complete the second pressurized impregnation.

[0039] It should be noted that the functional composite layer refers to a macroscopically flexible and microscopically functional composite material layer formed by fixing inorganic non-metallic functional particles into a flexible porous fiber substrate with an adhesive. Its purpose is to endow the sofa with additional properties such as heat insulation, flame retardancy or health functions without sacrificing the sofa's softness.

[0040] Environmentally friendly liquid adhesives refer to liquid adhesive materials that use water as a dispersion medium or are biodegradable themselves. They include water-based polymer dispersions (such as water-based polyurethane and water-based acrylic emulsions) and bio-based adhesives (such as starch-based and cellulose derivative adhesives). Their purpose is to achieve a strong and environmentally friendly bond between functional particles and fiber substrates.

[0041] Vacuum negative pressure refers to a pressure environment lower than the local atmospheric pressure. Its purpose is to use the pressure difference to drive the slurry into and fill the pores of the fiber substrate, expel the air, and achieve the initial penetration of the slurry.

[0042] Secondary pressure impregnation refers to the process step of applying static positive pressure higher than atmospheric pressure immediately after vacuum impregnation. Its purpose is to use the positive pressure environment to drive the slurry to further penetrate and compact into the deep pores of the fiber substrate and the tiny gaps between fiber bundles, so as to ensure high loading and uniform distribution of functional particles.

[0043] Impregnated composites refer to intermediate products of fiber-based substrates that have been impregnated with slurry but have not yet been cured, and are precursors for forming functional composite layers.

[0044] This solution achieves its function through the following steps: First, by mixing functional inorganic non-metallic particles with an environmentally friendly liquid adhesive, a stable functionalized slurry is formed. Then, a flexible porous fiber substrate is immersed in this slurry and subjected to alternating vacuum negative pressure and static positive pressure. Through the synergistic driving force of positive and negative pressure, the slurry ensures that it fully and densely fills all spaces in the fiber network, from macroscopic pores to microscopic gaps, thus forming an impregnated composite. Finally, the impregnated composite is dried to cure the liquid adhesive, permanently fixing the inorganic non-metallic functional particles to the surface and pores of the fiber network, thereby forming a functional composite layer that integrates flexibility and functionality. This functional composite layer, as the core functional unit, lays the material foundation for the subsequent construction of a high-performance, multi-layered soft sofa.

[0045] Step S2 further includes the following sub-steps: S2-1, based on the human body pressure distribution in a sitting posture, configures the static compression modulus of the contact comfort layer, the main buffer layer and the bottom support layer to satisfy a gradient relationship that increases sequentially. S2-2, based on the gradient relationship, slow rebound polyurethane foam is selected as the contact comfort layer, high rebound polyurethane foam is selected as the main cushioning layer, and high-density sponge or independent pocket spring system is selected as the bottom support layer. S2-3, through a progressively increasing compression modulus gradient, enables the contact comfort layer, main buffer layer and bottom support layer to work together under pressure, achieving gradual dispersion and support of body pressure, and preventing the feeling of sitting on the bottom.

[0046] It should be noted that the gradient cushioning system refers to a composite structure consisting of a contact comfort layer, a main cushioning layer, and a bottom support layer, with the material's resistance to compression deformation increasing sequentially. Its purpose is to achieve scientific distribution and gentle support of human body pressure through gradient design of mechanical properties, thereby providing an extremely soft touch while ensuring stable support and avoiding local pressure concentration and sitting fatigue.

[0047] The static compressive modulus refers to the ratio of stress to strain of a material under quasi-static compressive load. It is a core mechanical parameter characterizing the softness and hardness of a material and its support strength. In this invention, it is mainly used to quantify and define the gradient relationship of the softness and hardness differences between the contact comfort layer, the main buffer layer and the bottom support layer.

[0048] Human body pressure distribution in a sitting position refers to the magnitude and distribution of pressure generated on the contact surface between the buttocks and thighs when the human body is in a sitting position. It can be obtained based on anthropometric data or pressure mapping tests. Its main purpose is to provide a scientific basis for the configuration of the compression modulus of each layer in the gradient buffer system, so as to ensure the effectiveness of pressure management.

[0049] The comfort layer refers to the outermost flexible material that comes into direct contact with the human body. It typically has the lowest compression modulus and the slowest rebound speed. Its purpose is to provide an initial soft, enveloping feel and an immersive sinking experience, achieving initial pressure dispersion.

[0050] The main buffer layer refers to the intermediate flexible material set below the contact comfort layer. It has a moderate compression modulus and excellent resilience. Its purpose is to serve as the core hub for pressure transmission and conversion, to bear the pressure from the contact comfort layer and distribute it more evenly over a larger area, while providing the main dynamic rebound support.

[0051] The bottom support layer refers to the flexible material or elastic system set at the bottom of the cushioning system. It has the highest compression modulus and its purpose is to provide solid ultimate support, prevent users from feeling the bottom when sitting or lying down due to the complete compression of the cushioning layer, and maintain the overall structural stability of the sofa.

[0052] The compression modulus gradient relationship refers to the mathematical relationship that the static compression modulus of the contact comfort layer, the main buffer layer and the bottom support layer must satisfy in successive increasing order. The ratio range is usually controlled between 1:(1.5 to 3.0):(3.0 to 8.0). Its main purpose is to build a continuous mechanical transition from extremely soft to solid support, which is the structural basis for achieving scientific pressure management.

[0053] The gradual dispersion and support of body pressure refers to the coordinated working mechanism in which the contact comfort layer, the main buffer layer and the bottom support layer work in sequence according to their compression modulus gradient when the human body sits down, transforming the concentrated load into a distributed load. The ultimate effect is to avoid the generation of local high pressure areas and ensure effective support in any normal sitting posture, completely eliminating the bottoming phenomenon.

[0054] This solution achieves its function in the following way: First, based on a biomechanical model of human body pressure distribution in a sitting posture, a defined gradient relationship is established between the contact comfort layer, the main cushioning layer, and the bottom support layer, with the static compression modulus increasing sequentially. Based on this gradient relationship, specific materials with corresponding mechanical properties are selected: slow-rebound polyurethane foam is selected as the contact comfort layer, high-rebound polyurethane foam as the main cushioning layer, and high-density sponge or an independent pocket spring system as the bottom support layer. When a user sits on the sofa, their body weight is first borne by the contact comfort layer with the lowest compression modulus. This layer undergoes significant deformation, providing a soft, enveloping feel and initial pressure dispersion. Subsequently, the pressure is transferred to the main cushioning layer with a higher compression modulus. This layer, through moderate deformation and excellent rebound, further optimizes the pressure distribution and provides core elastic support. Finally, the residual pressure is completely absorbed by the bottom support layer with the highest compression modulus. This layer undergoes only minor deformation, providing rock-solid ultimate support and effectively preventing the user from experiencing an uncomfortable bottoming sensation. Through the synergistic effect of these three layers of materials driven by the compression modulus gradient, the body pressure is gradually and smoothly dispersed and scientifically supported, thereby achieving both ultimate comfort and long-term structural stability.

[0055] Step S3 further includes the following sub-steps: S3-1, the bottom support layer and the main buffer layer are stacked one on top of the other to form a basic buffer body; S3-2, the functional composite layer is placed on the upper surface of the main buffer layer of the base buffer body in such a way that its planar projected area is smaller than that of the main buffer layer, so that its periphery is surrounded by the material of the main buffer layer, forming an island-shaped embedded structure. S3-3, the contact comfort layer is covered on the island-shaped embedded structure and combined with the upper surface of the main buffer layer on the periphery to complete the construction of the four-layer composite, which consists of the bottom support layer, the main buffer layer, the functional composite layer and the contact comfort layer from bottom to top.

[0056] Furthermore, in sub-step S3-2, before or simultaneously with placing the functional composite layer on the upper surface of the main buffer layer, a step of prefabricating an anti-displacement structure is also included: One or more limiting protrusions are fixedly disposed on the lower surface of the functional composite layer; On the upper surface of the main buffer layer, corresponding to the position of the limiting protrusion, a limiting groove adapted to the shape of the limiting protrusion is formed by molding or cutting. When the functional composite layer is placed on the upper surface of the main buffer layer, the limiting protrusion is embedded in the corresponding limiting groove, forming an anti-offset structure that restricts the horizontal movement of the functional composite layer.

[0057] It should be noted that the basic buffer body refers to the preliminary assembly formed by the bottom support layer and the main buffer layer by stacking them one on top of the other. Its purpose is to provide a stable support platform with a clear hierarchical relationship for the precise positioning and embedding of subsequent functional composite layers.

[0058] The fact that the planar projection area is smaller than that of the main buffer layer means that the projection outline of the functional composite layer on the horizontal plane is completely contained within the projection outline of the main buffer layer, and its perimeter maintains a certain safe distance from the perimeter of the main buffer layer. This distance can be determined according to the size of the sofa and the depth of human body pressure deformation, mainly to ensure the formation of an effective edge buffer protection zone.

[0059] Anti-displacement structure refers to a positioning device that restricts the horizontal movement of the functional composite layer through mechanical interlocking. Its purpose is to prevent the functional composite layer from shifting, misaligning, or twisting relative to the buffer layer during long-term use, vibration, or stress on the sofa, thus ensuring the long-term stability and functionality of the island-shaped embedded structure.

[0060] Limiting bumps refer to one or more protruding structures fixedly set on the lower surface of the functional composite layer. Their material can be integrally formed with the functional composite layer or be independent components that are bonded later. They mainly serve as active mating components of the anti-displacement structure.

[0061] The limiting groove refers to a recessed structure formed on the upper surface of the main buffer layer by molding, cutting or engraving, which is adapted to the shape of the limiting protrusion. It mainly serves as a passive mating component of the anti-displacement structure, and achieves mechanical interlocking through precise mating with the limiting protrusion.

[0062] The four-layer composite refers to a complete composite structure consisting of a bottom support layer, a main buffer layer, a functional composite layer, and a contact comfort layer arranged in a specific spatial order. It is the direct precursor to the sofa liner, and its structural quality directly determines the seating comfort and functional stability of the final product.

[0063] This solution achieves its function through the following steps: First, the bottom support layer and the main buffer layer are stacked vertically to form a stable basic buffer. Based on this, through an anti-displacement structure prefabrication step, limiting protrusions are set on the lower surface of the functional composite layer, and corresponding limiting grooves are machined on the upper surface of the main buffer layer. Then, the functional composite layer, with its planar projected area smaller than that of the main buffer layer, is precisely aligned and embedded into the upper surface of the main buffer layer of the basic buffer through the limiting protrusions and grooves. At this point, the periphery of the functional composite layer is completely surrounded by the main buffer layer material, forming a stable island-shaped embedded structure, and the anti-displacement structure effectively restricts any horizontal movement. Finally, the contact comfort layer completely covers the island-shaped embedded structure and combines with the upper surface of the main buffer layer at its periphery, completing the construction of a four-layer composite structure from bottom to top: the bottom support layer, the main buffer layer, the functional composite layer, and the contact comfort layer. The entire process employs a three-step configuration method: building a basic buffer structure, precisely positioning and ensuring anti-displacement through island embedding, and finally covering the surface. This ensures that the resulting composite structure possesses clear functional zoning, excellent edge comfort, and long-term structural integrity. In step S4, when needle puncture is used as the physical composite method, a needle with side barbs is used to puncture the four-layer composite. The needle penetrates the comfort layer, the main cushioning layer, the functional composite layer and enters the bottom support layer in sequence, so that the fibers of each layer of material are intertwined and entangled, thereby fixing the island-shaped embedded functional composite layer between the main cushioning layer and the bottom support layer, forming a three-dimensional mechanically interlocked sofa liner.

[0064] When quilting is chosen as the physical composite method, sewing thread is used to sew the four layers together along the sewing path that runs through the functional composite layer, the main cushioning layer, and the bottom support layer to form the sofa lining. The tension of the sewing thread binds the functional composite layer, the main cushioning layer, and the bottom support layer together to prevent them from separating during use.

[0065] When high-frequency hot-melt is selected as the physical composite method, a hot-melt material is set at the interface between the functional composite layer, the main buffer layer, and the bottom support layer. The hot-melt material is melted by high-frequency heating and penetrates into the porous structure of the functional composite layer and the fiber gaps of adjacent layers. After cooling, an anchoring structure that penetrates the interface is formed, thereby solidifying each layer into the sofa liner. The hot-melt material includes hot-melt adhesive powder, hot-melt adhesive mesh, and low-melting-point polymer fibers.

[0066] It should be noted that the needle-punching composite method refers to a physical composite process that uses a special needle with side barbs to repeatedly puncture a multilayer composite at a preset puncture density and depth. The purpose is to force the fibers of different layers to interlock and entangle with each other through the mechanical action of the needle, thereby forming a three-dimensional mechanical interlocking structure between the layers.

[0067] A barbed needle is a special piercing tool with unidirectional or bidirectional inclined barbs on the surface of the pointer shaft. The main function of its barb structure is to effectively hook and pull the fibers of flexible materials during the piercing process and the return stroke, promoting the crossing and entanglement of fibers at different layers.

[0068] Three-dimensional mechanical interlocking refers to a strong bonded structure formed by fiber entanglement at the interfaces of various material layers, which mutually restricts each other in three-dimensional space. This structure does not rely on chemical adhesives, and its bond strength is comparable to the lifespan of the material itself, effectively resisting interlayer delamination.

[0069] Quilting composite refers to a physical composite process that uses high-strength sewing thread to sew multiple layers together according to a preset sewing trajectory. Its purpose is to achieve a tight bond between layers through the tension generated by the sewing thread and the fiber friction caused by the sewing thread passing through the material.

[0070] The sewing trajectory that penetrates the functional composite layer refers to the design path of the sewing needle that ensures the sewing thread can penetrate the functional composite layer and its adjacent buffer layer. The purpose is to form a direct physical constraint on the functional composite layer through the sewing thread, preventing it from detaching from the flexible buffer layer during use.

[0071] High-frequency hot-melt composite refers to a physical composite process in which a hot-melt material is pre-set at the interlayer interface, and heat is generated by the high-speed vibration of polar molecules inside the material through a high-frequency electric field, thereby selectively melting and flowing the hot-melt material. Its purpose is to achieve an environmentally friendly interlayer bonding without the need for chemical solvents.

[0072] An anchoring structure that penetrates the interface refers to a composite material formed after molten hot melt material penetrates into the porous structure of the functional composite layer and the fiber gaps of the adjacent buffer layer under pressure, and then cools and solidifies. This structure has macroscopic continuity and microscopic mechanical interlocking effect, and can effectively transfer interlayer stress and prevent interface slippage.

[0073] This application achieves its functionality in the following ways: When needle piercing is chosen as the physical composite method, a needle with lateral barbs is used to pierce the four-layer composite material at full thickness according to a preset piercing pattern. The needle sequentially penetrates the comfort layer, the main cushioning layer, the functional composite layer, and enters the bottom support layer. During this process, the barbs of the needle hook the fibers of each layer of material, and on the return stroke, they cause these fibers to intertwine and entangle, ultimately forming a strong three-dimensional mechanical interlocking network between the layers. This network firmly anchors the island-shaped embedded functional composite layer between the main cushioning layer and the bottom support layer, forming a structurally stable sofa liner.

[0074] When quilting is chosen as the physical bonding method, high-strength polyester or nylon sewing thread is used to sew the four-layer composite together along a pre-set sewing path. The sewing path is designed to penetrate the functional composite layer, the main cushioning layer, and the bottom support layer, ensuring that the sewing thread can directly and effectively constrain the functional composite layer. The continuous tension generated by the sewing thread tightly bonds the functional composite layer to the upper and lower cushioning layers, effectively preventing interlayer separation during long-term use.

[0075] When high-frequency hot-melt bonding is used as the physical composite method, hot-melt adhesive powder, hot-melt adhesive web, or low-melting-point polymer fibers are first laid at the interface between the functional composite layer, the main buffer layer, and the bottom support layer. The composite is then placed in a high-frequency electric field. Due to dielectric loss, the hot-melt material rapidly melts into a viscous flow state and, under pressure, penetrates into the porous structure of the functional composite layer and the fiber gaps between adjacent buffer layers. After heating is stopped, the molten material cools and solidifies, forming numerous through-hole anchor points at the interface. These anchor points together constitute a strong mechanical connection, thus solidifying the layers into a highly integral sofa liner.

[0076] Please see Figure 2 A flowchart illustrating the sofa assembly process provided in an embodiment of the present invention.

[0077] Step S5 further includes the following sub-steps: S5-1, The prepared sofa inner liner is installed and fixed onto the corresponding load-bearing surface of the pre-prepared sofa frame using mechanical connectors; S5-2, Flexible molding filling is applied to the armrests and backrest areas of the fixed sofa inner core and frame, and then covered with a flame-retardant pre-treated outer fabric. S5-3, Install the sofa legs to complete the production of the multi-layered soft sofa.

[0078] It should be noted that mechanical connectors refer to physical connection elements used to achieve detachable or permanent fixation between the sofa liner and the frame, including but not limited to screws, bolts, corner brackets, Velcro, or snap-fit ​​structures.

[0079] The corresponding load-bearing surface of the sofa frame refers to the contact surface in the frame structure that is specifically designed to support the sofa liner and transmit loads, and its structural strength must meet the long-term load-bearing requirements. Flexible molding filling refers to the process of shaping non-load-bearing areas such as armrests and backrests with flexible materials after the sofa inner core is fixed. Its purpose is to improve the appearance of the sofa and enhance local comfort.

[0080] Flame-retardant pre-treated outer fabric refers to woven materials that have been impregnated with flame retardants, coated, or have inherent flame-retardant properties. Their limiting oxygen index is usually greater than 28%, and the purpose is to improve the fire safety level of the sofa.

[0081] Sofa legs are components installed at the bottom of the sofa frame to provide support, adjust height, or protect the ground. They can be made of wood, metal, or polymer materials.

[0082] This solution achieves its function through the following steps: First, the prepared sofa inner liner is precisely installed and fixed to the designated load-bearing area of ​​the sofa frame using mechanical connectors, establishing a stable main support structure. Then, flexible materials are used to fill and shape the non-load-bearing areas such as the armrests and backrest of the fixed inner liner and frame, creating ergonomic curved transitions through the combination of materials of different densities. After shaping, a flame-retardant pre-treated outer fabric is fitted, achieving a balance between safety and aesthetic decoration. Finally, the sofa legs are installed, completing the final assembly of the entire chair. The entire process forms a complete assembly flow from core functional modules to finished furniture, ensuring product structural stability and functional integrity through standardized assembly procedures.

[0083] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for preparing a multi-layered soft sofa, characterized in that, Includes the following steps: Step S1: Inorganic non-metallic functional particles are mixed with liquid adhesive to form a slurry, and an impregnation process is used to allow the slurry to penetrate into the flexible porous fiber substrate. After drying, a functional composite layer is formed. Step S2: Prepare flexible materials with progressively increasing compression modulus to construct a contact comfort layer, a main buffer layer, and a bottom support layer that can disperse body pressure and prevent bottoming out. Step S3: Place the functional composite layer as an intermediate layer between the main buffer layer and the bottom support layer, and then cover it with the contact comfort layer to form a four-layer composite. Step S4: Through physical methods such as needle punching, quilting, or high-frequency heat melting, the layers of the four-layer composite are joined together to form the sofa inner lining. Step S5: Install the sofa inner liner onto the sofa frame to obtain a multi-layered soft sofa.

2. The method for preparing a multi-layered soft sofa according to claim 1, characterized in that: Step S1 further includes the following sub-steps: S1-1, Inorganic non-metallic functional particles are mixed with environmentally friendly liquid binders to form a uniform slurry; the inorganic non-metallic functional particles include hollow ceramic microspheres, metal hydroxides, and natural mineral powders with far-infrared emission or negative ion release functions; the environmentally friendly liquid binder includes aqueous polymer dispersions and bio-based binders. S1-2, a flexible porous fiber substrate with a three-dimensional interconnected network structure is immersed in slurry and a vacuum negative pressure is applied to allow the slurry to penetrate and fill the pores of the fiber substrate to form an impregnated composite. S1-3, the impregnated composite is dried to cure the liquid adhesive, fixing the inorganic non-metallic functional particles into the fiber network of the flexible porous fiber substrate to form a functional composite layer.

3. The method for preparing a multi-layered soft sofa according to claim 2, characterized in that: In sub-step S1-2, after applying vacuum negative pressure, a secondary pressure impregnation step is also included: After the vacuum is released, the flexible porous fiber substrate and the slurry are transferred together into a sealed pressure vessel; Compressed gas is injected into the pressure vessel to create a static positive pressure environment inside that is higher than atmospheric pressure. Under this positive pressure environment, the slurry is driven by pressure to penetrate and fill the deep pores of the fiber substrate and the gaps between fiber bundles; Release the pressure and complete the second pressurized impregnation.

4. The method for preparing a multi-layered soft sofa according to claim 1, characterized in that: Step S2 further includes the following sub-steps: S2-1, based on the human body pressure distribution in a sitting posture, configures the static compression modulus of the contact comfort layer, the main buffer layer and the bottom support layer to satisfy a gradient relationship that increases sequentially. S2-2, based on the gradient relationship, slow rebound polyurethane foam is selected as the contact comfort layer, high rebound polyurethane foam is selected as the main cushioning layer, and high-density sponge or independent pocket spring system is selected as the bottom support layer. S2-3, through a progressively increasing compression modulus gradient, enables the contact comfort layer, main buffer layer and bottom support layer to work together under pressure, achieving gradual dispersion and support of body pressure, and preventing the feeling of sitting on the bottom.

5. The method for preparing a multi-layered soft sofa according to claim 1, characterized in that: Step S3 further includes the following sub-steps: S3-1, the bottom support layer and the main buffer layer are stacked one on top of the other to form a basic buffer body; S3-2, the functional composite layer is placed on the upper surface of the main buffer layer of the base buffer body in such a way that its planar projected area is smaller than that of the main buffer layer, so that its periphery is surrounded by the material of the main buffer layer, forming an island-shaped embedded structure. S3-3, the contact comfort layer is covered on the island-shaped embedded structure and combined with the upper surface of the main buffer layer on the periphery to complete the construction of the four-layer composite, which consists of the bottom support layer, the main buffer layer, the functional composite layer and the contact comfort layer from bottom to top.

6. The method for preparing a multi-layered soft sofa according to claim 5, characterized in that: In sub-step S3-2, before or simultaneously with placing the functional composite layer on the upper surface of the main buffer layer, a step of prefabricating an anti-displacement structure is also included: One or more limiting protrusions are fixedly disposed on the lower surface of the functional composite layer; On the upper surface of the main buffer layer, corresponding to the position of the limiting protrusion, a limiting groove adapted to the shape of the limiting protrusion is formed by molding or cutting. When the functional composite layer is placed on the upper surface of the main buffer layer, the limiting protrusion is embedded in the corresponding limiting groove, forming an anti-offset structure that restricts the horizontal movement of the functional composite layer.

7. The method for preparing a multi-layered soft sofa according to claim 1, characterized in that: In step S4, when needle puncture is used as the physical composite method, a needle with side barbs is used to puncture the four-layer composite. The needle penetrates the comfort layer, the main cushioning layer, the functional composite layer and enters the bottom support layer in sequence, so that the fibers of each layer of material are intertwined and entangled, thereby fixing the island-shaped embedded functional composite layer between the main cushioning layer and the bottom support layer, forming a three-dimensional mechanically interlocked sofa liner.

8. The method for preparing a multi-layered soft sofa according to claim 1, characterized in that: In step S4, when quilting is selected as the physical composite method, sewing thread is used to sew the four layers together through the sewing path of the functional composite layer, the main cushioning layer and the bottom support layer to form the sofa liner; the tension of the sewing thread binds the functional composite layer, the main cushioning layer and the bottom support layer together to prevent them from separating during use.

9. The method for preparing a multi-layered soft sofa according to claim 1, characterized in that: In step S4, when high-frequency hot-melt is selected as the physical composite method, a hot-melt material is set at the interface between the functional composite layer, the main buffer layer, and the bottom support layer. The hot-melt material is melted by high-frequency heating and penetrates into the porous structure of the functional composite layer and the fiber gaps of adjacent layers. After cooling, an anchoring structure that penetrates the interface is formed, thereby solidifying each layer into a sofa liner. The hot-melt material includes hot-melt adhesive powder, hot-melt adhesive mesh, and low-melting-point polymer fibers.

10. The method for preparing a multi-layered soft sofa according to claim 1, characterized in that: Step S5 further includes the following sub-steps: S5-1, The prepared sofa inner liner is installed and fixed onto the corresponding load-bearing surface of the pre-prepared sofa frame using mechanical connectors; S5-2, Flexible molding filling is applied to the armrests and backrest areas of the fixed sofa inner core and frame, and then covered with a flame-retardant pre-treated outer fabric. S5-3, Install the sofa legs to complete the production of the multi-layered soft sofa.

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