A gradient cellular soundproofing and shock absorbing polyurethane sponge and a preparation process thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG SHENGNUOMENG GUJIA SPONGE
- Filing Date
- 2026-04-09
- Publication Date
- 2026-05-26
Smart Images
Figure CN122078028A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polyurethane foam materials technology, and in particular to a gradient-cell sound-insulating and vibration-damping polyurethane sponge and its preparation process. Background Technology
[0002] Polyurethane foam, due to its lightweight, excellent elasticity, and ease of processing, is widely used in construction, transportation, and home appliances—scenarios requiring sound insulation and vibration damping. Currently, most polyurethane foams on the market have a single, uniform cell structure. The pore size and density cannot be graded, making it difficult to simultaneously meet the multiple needs of sound absorption, sound insulation, and vibration damping. This type of single-structure foam has a limited absorption frequency range for sound waves, failing to effectively attenuate mid-to-high frequency and low-frequency sound waves, making its sound insulation performance insufficient for high-end applications. Furthermore, the uniform cell structure has significant shortcomings in mechanical properties. It is prone to overall deformation under stress, and its support and cushioning properties cannot be coordinated. After long-term use, it is susceptible to permanent compression deformation, leading to a continuous decline in vibration damping performance and an inability to stably perform its cushioning and damping function. Existing products also lack internal reinforcement structures, resulting in weak overall impact resistance. In environments with frequent pressure, they are prone to collapse and damage, leading to a short service life.
[0003] Existing composite processes and structural designs for sound-insulating and vibration-damping foams also suffer from numerous defects. Most products use adhesive bonding after curing to add sound-insulating layers, resulting in poor interlayer adhesion and a tendency for delamination and detachment over long-term use, thus reducing sound insulation performance. Some composite structures with interlayers are poorly designed, blocking normal sound wave transmission and actually reducing the foam's sound absorption performance. In the manufacturing process, traditional constant-temperature foaming methods cannot create a vertical gradient cell structure. Some processes use flammable and explosive foaming agents, posing significant safety hazards. Furthermore, the crude temperature control methods for molds are insufficient to counteract the exothermic foaming reaction, making it impossible to stably produce gradient cell products. Overall, existing polyurethane foams suffer from poor sound insulation, weak vibration damping, easy detachment of composite layers, structural deformation, and limited manufacturing processes, failing to achieve a balance between high performance and long lifespan, significantly restricting their widespread application in high-end sound insulation and vibration damping fields. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention discloses a gradient-cell sound-insulating and vibration-damping polyurethane sponge with good sound insulation, strong shock absorption, non-detachable composite layers, and non-deformable structure, as well as its preparation process.
[0005] This invention discloses a gradient-cell sound-insulating and vibration-damping polyurethane foam, comprising:
[0006] The sponge body and the composite sound insulation layer;
[0007] The sponge body has a three-layer gradient open-pore structure, from top to bottom: upper sound-absorbing layer, middle transition layer and lower vibration-damping support layer;
[0008] The composite sound insulation layer includes a surface composite layer and a sandwich composite layer. The surface composite layer covers the outer surface of the upper sound-absorbing layer, and the sandwich composite layer is embedded in the middle transition layer.
[0009] The composite sound insulation layer is made of sound-insulating non-woven fabric and damping PET film. The sponge body and the composite sound insulation layer are tightly bonded together through an interlocking structure formed by integral molding during the foaming process.
[0010] Furthermore, the upper sound-absorbing layer has a large-pore open-cell structure, the middle transition layer has a medium-pore open-cell structure, and the lower vibration-damping support layer has a small-pore open-cell structure, with the pore size decreasing gradually from top to bottom.
[0011] Furthermore, local reinforcing ribs are provided in the lower shock-absorbing support layer. The material of the local reinforcing ribs is the same as that of the sponge body, and they are distributed in a matrix inside the lower shock-absorbing support layer. The diameter of the local reinforcing ribs is 0.45-1.05mm, and the matrix arrangement spacing is 1.8-3.2cm.
[0012] Furthermore, the local reinforcing ribs are inserted to a depth of 77%-83% of the thickness of the lower damping support layer.
[0013] Furthermore, the sound-insulating nonwoven fabric is a polyester fiber nonwoven fabric that has been activated by a plasma treatment of mixed oxygen and argon.
[0014] The plasma activation parameters are: oxygen-argon volume ratio 1:2-1:4, power 200-300W, and processing time 30-60s.
[0015] The surface of the damping PET film is coated with a polyurethane prepolymer layer that is homologous to the sponge body;
[0016] Sound-insulating non-woven fabric and damping PET film are hot-pressed together to form a composite sound-insulating layer;
[0017] The hot-pressing composite parameters are: temperature 80-100℃, pressure 0.2-0.4MPa, and time 10-20s.
[0018] Furthermore, the sponge body is foamed from polyurethane raw materials including basic raw materials, gradient adjustment raw materials and compounded raw materials;
[0019] The basic raw materials include polyether polyols and isocyanates;
[0020] Gradient-adjustable raw materials include chemical foaming agents, physical foaming agents, and foam stabilizers;
[0021] The compounded raw materials include catalysts, crosslinking agents, reinforcing agents, and anti-aging agents.
[0022] Furthermore, the polyether polyol is polyoxypropylene glycol with a molecular weight of 2000; the isocyanate is diphenylmethane diisocyanate;
[0023] The chemical foaming agent is deionized water, and the physical foaming agent is HFO-1234ze;
[0024] The foam stabilizer is an organosilicon surfactant;
[0025] The catalyst is a mixture of triethylenediamine and dibutyltin dilaurate;
[0026] The cross-linking agent is glycerol;
[0027] The reinforcing agent is nano-calcium carbonate modified with a silane coupling agent, and the anti-aging agent is a hindered phenolic anti-aging agent.
[0028] This invention discloses a preparation process for gradient-cell sound-insulating and vibration-damping polyurethane foam, which is used to prepare any of the gradient-cell sound-insulating and vibration-damping polyurethane foams mentioned above, including the following steps:
[0029] Step 1, Raw material pretreatment: The polyurethane raw material and the composite sound insulation material are pretreated respectively, and the mold is treated;
[0030] Step 2, Raw material mixing: Add the pretreated polyurethane raw materials into the mixing tank in sequence and mix to form a foaming slurry;
[0031] Step 3, initial formation of gradient foam cells: Inject the upper foaming slurry into the corresponding area of the mold and perform gradient temperature-controlled foaming until it reaches a semi-gel state;
[0032] Step 4, synchronous online foaming and reinforcing bar embedding: lay a sandwich composite layer on the surface of the upper semi-gel layer, and then pour the middle transition layer and the lower shock-absorbing support layer foaming slurry in sequence. Immediately embed local reinforcing bars before the lower slurry cures.
[0033] The surface composite layer is laid on the inner wall of the mold, and gradient foaming is continued to form an integral mold.
[0034] Step 5, Curing, Demolding and Curing: Curing the foamed product, cooling and demolding it, and then curing it to obtain the finished product.
[0035] Furthermore, in step 3, the specific parameters for gradient temperature controlled foaming are as follows:
[0036] The mold has independent temperature control in three zones: upper, middle and lower. The upper zone is maintained at 53-62℃ for 13-22 minutes.
[0037] Maintain the middle layer at 43-52℃ for 18-27 minutes;
[0038] Maintain the lower layer at 33-42℃ for 23-32 minutes.
[0039] Furthermore, in step 4, the criteria for determining the semi-gel stage are: the cells have initially formed but have not fully solidified, and the foaming height reaches 50%-65% of the total height of the mold, as monitored by the mold visualization window and height displacement sensor;
[0040] In step 5, the specific parameters for curing, demolding, and maturation are as follows: constant temperature curing at 70-80℃ for 70-80 minutes, demolding after cooling for 30 minutes, and maturation at 23-27℃ and 45%-55% humidity for 32-40 hours.
[0041] The beneficial effects of this invention are:
[0042] This invention enhances the full-frequency sound absorption and insulation performance of sponge through the synergistic design of a three-layer gradient open-pore structure and a double composite sound insulation layer, breaking through the acoustic performance limitations of traditional single-pore sponges. The sponge body forms a continuous pore structure with progressively decreasing pore sizes from top to bottom. The upper layer of large-pore pores quickly captures and dissipates low-frequency sound waves, the middle layer of medium-pore pores smoothly transitions and further weakens sound wave energy, and the lower layer of small-pore pores assists in blocking sound wave penetration. Combined with the surface and interlayer double composite sound insulation layers, a multi-level sound wave blocking system is formed, effectively eliminating interlayer sound wave leakage and achieving full-frequency attenuation of low-frequency and mid-to-high-frequency sound waves. The sound insulation performance represents a significant leap forward compared to traditional sponges, meeting the stringent requirements for high-efficiency sound insulation in various scenarios.
[0043] This invention leverages the mechanical properties of gradient foam cells and its internal reinforcement structure to achieve a balance between efficient shock absorption and stable support, optimizing the mechanical performance of the sponge. The middle layer, with its medium-sized foam cells, provides core shock absorption, rapidly dissipating vibration and impact energy. The lower layer, with its small-sized foam cells, offers robust support. Combined with matrix-distributed local reinforcement ribs, external pressure and impact are evenly distributed, preventing localized collapse or permanent deformation under long-term stress and reducing the compression set rate. When the sponge is under overall stress, it buffers and dissipates force layer by layer, retaining the soft feel of the upper sound-absorbing layer while possessing excellent resistance to deformation and load-bearing capacity. Its shock absorption performance far surpasses that of conventional sponges, maintaining a stable cushioning and shock absorption effect even after long-term use.
[0044] This invention employs a simultaneous foaming and integrated molding process, improving product stability and lifespan from both structural and manufacturing perspectives, while simplifying the production process for efficient mass production. The sponge body and composite sound insulation layer are integrated through the penetration and embedding of foaming slurry, eliminating the need for additional adhesives and completely solving the problem of easy detachment between layers in traditional composite sponges, thus enhancing the bonding strength of the composite layers. Zoned independent temperature control and dynamic temperature compensation processes ensure stable molding of gradient cells. Environmentally friendly, non-flammable components are used in the raw materials, meeting the requirements of industrialized safe production. The reinforcing ribs made of the same material are perfectly integrated with the coating layer and sponge matrix. Combined with the addition of anti-aging components, this delays material aging and degradation, resulting in a stable and durable overall product structure that maintains excellent sound insulation and vibration damping performance for a long time, effectively expanding the high-end application scenarios of polyurethane sponge. Attached Figure Description
[0045] Figure 1 This is a flowchart illustrating a process for preparing gradient-cell sound-insulating and vibration-damping polyurethane foam according to an embodiment of this application.
[0046] Figure 2 This is a product illustration of a gradient-cell sound-insulating and vibration-damping polyurethane foam according to an embodiment of this application.
[0047] Figure 3 This is another product image of a gradient-cell sound-insulating and vibration-damping polyurethane foam according to an embodiment of this application.
[0048] Figure 4 This is a diagram of a production equipment for a gradient-cell sound-insulating and vibration-damping polyurethane sponge according to an embodiment of this application. Detailed Implementation
[0049] To enable those skilled in the art to better understand the present invention, the technical solutions in the specific embodiments of the present invention will be clearly and completely described below.
[0050] This invention discloses a gradient-pore sound-insulating and vibration-damping polyurethane foam, comprising: a foam body and a composite sound-insulating layer; the foam body has a three-layer gradient open-pore structure, consisting of an upper sound-absorbing layer, a middle transition layer, and a lower vibration-damping support layer from top to bottom; the composite sound-insulating layer includes a surface composite layer and a sandwich composite layer, the surface composite layer being pre-laid on the inner wall of the mold and integrally bonded with the upper sound-absorbing layer during the foaming process; the sandwich composite layer is laid on the surface of the upper semi-gel layer, wrapped by the middle slurry, and embedded inside the middle transition layer; the composite sound-insulating layer is composed of a sound-insulating non-woven fabric and a damping PET film, and the foam body and the composite sound-insulating layer are tightly bonded by an interlocking structure formed integrally during the foaming process.
[0051] The gradient-cell sound-insulating and vibration-damping polyurethane foam of this invention completes its overall structure through a layered structure and an integrated molding process. First, the foam body is set into a three-layer continuous gradient open-cell shape, forming an upper sound-absorbing layer, a middle transition layer, and a lower vibration-damping support layer from top to bottom. Then, the composite sound insulation layer is divided into a surface composite layer and an interlayer composite layer. The surface composite layer is pre-laid on the inner wall of the mold, and the interlayer composite layer is embedded in the middle transition layer. The composite sound insulation layer is made of sound-insulating non-woven fabric and damping PET film. Finally, relying on the polyurethane foaming molding process, the foam body and the composite sound insulation layer are simultaneously combined into a complete structure.
[0052] The three-layer gradient open-pore structure of the sponge body is achieved through a gradient temperature-controlled foaming process. The upper sound-absorbing layer forms large-diameter open-pore bubbles, the middle transition layer forms medium-diameter open-pore bubbles, and the lower damping support layer forms small-diameter open-pore bubbles. The pore size decreases uniformly from top to bottom. This structure can fully utilize the physical properties of bubbles with different pore sizes. The large-diameter bubbles in the upper layer quickly absorb low-frequency sound waves, the medium-diameter bubbles in the middle layer complete sound wave transmission and core damping, and the small-diameter bubbles in the lower layer provide stable support.
[0053] The sponge body and the composite sound insulation layer are molded simultaneously and integrally during the polyurethane foaming process. The foaming slurry naturally seeps into the gaps of the composite sound insulation layer, forming an interlocking physical connection structure after curing. This bonding method eliminates the need for additional adhesives, ensuring a tight connection between the sponge body and the composite sound insulation layer, preventing delamination during use, and allowing the sound insulation performance of the composite sound insulation layer and the sound absorption and vibration damping performance of the sponge body to work synergistically. It also simplifies the production process and improves the overall stability and lifespan of the product.
[0054] In one implementation, the upper sound-absorbing layer has a large-pore open-cell structure, the middle transition layer has a medium-pore open-cell structure, and the lower vibration-damping support layer has a small-pore open-cell structure, with the pore size decreasing gradually from top to bottom.
[0055] In one implementation method, the present invention achieves a gradient arrangement of cell diameters through a gradient temperature controlled foaming process. The upper, middle and lower zones of the mold adopt independent constant temperature control and dynamic temperature control compensation. The upper zone uses a higher temperature to promote the full expansion of the cells to form a large-diameter open-cell structure. The middle zone uses a moderate temperature to form a uniform medium-diameter open-cell structure. The lower zone uses a lower temperature to limit the expansion of the cells to form a compact small-diameter open-cell structure, so that the cell diameters present a continuous and stable gradient decrease along the sponge body from top to bottom.
[0056] The progressively smaller pore size structure from top to bottom enables layered absorption and blocking of sound waves in different frequency bands. The large-pore size in the upper layer can quickly capture and dissipate low-frequency sound waves, preventing them from directly penetrating the sponge body. The medium-pore size in the middle layer provides a smooth transition and core damping, further weakening the sound waves and vibration energy, allowing the sound waves to be fully attenuated inside the sponge, thus improving the overall sound absorption and insulation effect of the sponge.
[0057] The lower layer's small-pore structure has higher density and support strength, effectively withstanding external pressure and preventing excessive deformation of the sponge. Combined with the gradient connection between the middle transition layer and the upper sound-absorbing layer, the sponge as a whole has both soft sound absorption and stable vibration reduction characteristics. When under stress, it can buffer and dissipate force layer by layer, ensuring the sound insulation and vibration reduction effect while improving the structural stability and durability of the sponge.
[0058] In one implementation method, local reinforcing ribs are provided within the lower damping support layer. These ribs are pre-formed elastomer rods made from the same polyurethane raw material system as the sponge body, and are distributed in a matrix within the lower damping support layer. The diameter of the reinforcing ribs is 0.45-1.05mm, the matrix spacing is 1.8-3.2cm, and the matrix rows and columns are evenly arranged to ensure uniform support.
[0059] In one implementation method, this invention completes the placement of local reinforcing ribs during the polyurethane foaming process. After sequentially pouring the upper, middle, and lower layers of foaming slurry, the ribs are pre-embedded immediately before the lower layer of slurry cures, arranged evenly in a matrix pattern. This ensures that the reinforcing ribs cure synchronously with the surrounding foaming material, ultimately forming a complete integral structure with the sponge body. The matrix-distributed local reinforcing ribs provide uniform internal support for the lower shock-absorbing support layer, dispersing the pressure and impact on the sponge, preventing local collapse or permanent deformation of the lower structure due to long-term stress, and ensuring that the sponge's support performance remains stable and consistent, without affecting the overall performance due to uneven stress.
[0060] Homogeneous materials refer to the use of the same polyurethane raw material system for the local reinforcing ribs, damping PET film coating layer, and sponge body. This ensures consistent chemical composition, interface compatibility, and seamless integration. The homogeneous material reinforcement is tightly bonded to the sponge body without gaps, preserving the internal pore structure of the sponge. Simultaneously, it strengthens the structural strength of the underlying shock-absorbing support layer, allowing the sponge to maintain its soft sound-absorbing properties while enhancing its shock-absorbing capacity. This ensures stable sound insulation and vibration damping effects over long-term use, extending the product's lifespan. Homogeneous materials mean that the reinforcing ribs, coating layer, and sponge body use the same polyurethane raw material system, with seamless interface integration.
[0061] In one implementation method, the local reinforcing ribs are inserted to a depth of 77%-83% of the thickness of the lower damping support layer. When the polyurethane foam is in the semi-gel stage, the insertion depth is controlled according to the overall thickness of the lower damping support layer, ensuring the reinforcing ribs are stably placed inside. The insertion depth is maintained between 77%-83% of the thickness of the lower damping support layer. Positioning control ensures that the insertion depth of each reinforcing rib is uniform. After the foam has fully cured, the reinforcing ribs are firmly bonded to the lower damping support layer.
[0062] This insertion depth range prevents the reinforcing ribs from penetrating the lower damping support layer, preserving the continuous structure of the bottom of the support layer. This keeps the bottom of the sponge flat and sealed, preventing damage or bulging, ensuring the sponge's fit and stability during placement, and maintaining the overall structural integrity. The appropriate insertion depth allows the reinforcing ribs to fully exert their internal support function without damaging the buffer foam structure at the bottom of the support layer. This gives the lower area sufficient structural strength and good elastic deformation capacity, effectively distributing stress under pressure and vibration, reducing permanent deformation, and continuously and stably performing sound insulation and vibration damping performance.
[0063] In one implementation method, the sound-insulating nonwoven fabric is a polyester fiber nonwoven fabric activated by a mixed oxygen and argon plasma treatment; the plasma activation parameters are an oxygen-argon volume ratio of 1:2-1:4, a power of 200-300W, and a treatment time of 30-60s; the surface of the damping PET film is coated with a polyurethane prepolymer layer that is homologous to the sponge body; the sound-insulating nonwoven fabric and the damping PET film are hot-pressed together to form a composite sound-insulating layer; the hot-pressing parameters are a temperature of 80-100℃, a pressure of 0.2-0.4MPa, and a time of 10-20s.
[0064] The sound-insulating non-woven fabric uses polyester fiber non-woven fabric as the base material. The surface of the non-woven fabric is modified through a plasma activation process using a mixture of oxygen and argon to enhance its surface activity and bonding ability. The surface of the damping PET film is uniformly coated with a polyurethane prepolymer of the same origin as the sponge body material, forming a continuous and complete coating. The treated sound-insulating non-woven fabric and the damping PET film are then laminated together and bonded tightly through a hot-pressing process, ultimately forming an integrated composite sound insulation layer.
[0065] Polyester fiber nonwoven fabric activated by oxygen-argon mixed plasma exhibits enhanced surface activity, enabling it to form a stronger physical and chemical bond with polyurethane foam material, preventing separation and detachment between the nonwoven fabric and the foam. The activated nonwoven fabric maintains unobstructed fiber gaps, ensuring both sound absorption and damping performance while enhancing the overall stability of the composite structure, allowing the sound insulation layer to maintain optimal performance over the long term.
[0066] The homologous polyurethane prepolymer layer on the surface of the damping PET film can quickly integrate with the foaming material of the sponge, further strengthening the bond between the composite sound insulation layer and the sponge. The hot-pressing composite process ensures a tight, gapless bond between the non-woven fabric and the damping PET film, eliminating sound wave leakage caused by interlayer gaps. This allows the composite sound insulation layer to combine the sound absorption properties of the non-woven fabric with the damping sound insulation performance of the PET film, synergistically improving the overall sound insulation and vibration reduction effect of the sponge.
[0067] In one embodiment, the sponge body is foamed from polyurethane raw materials including base raw materials, gradient regulating raw materials and compounded raw materials; the base raw materials include polyether polyol and isocyanate; the gradient regulating raw materials include chemical foaming agent, physical foaming agent and foam stabilizer; the compounded raw materials include catalyst, crosslinking agent and reinforcing agent and anti-aging agent.
[0068] The foam body is foamed using a multi-component compounded polyurethane raw material. The raw material system is divided into three categories: basic raw materials, gradient regulating raw materials, and compounded raw materials. The basic raw materials consist of polyether polyols and isocyanates as core components, which form the basic framework of the polyurethane foam through their polymerization reaction. The gradient regulating raw materials are composed of chemical foaming agents, physical foaming agents, and foam stabilizers, used to control the foaming process and cell morphology. The compounded raw materials include catalysts, crosslinking agents, reinforcing agents, and anti-aging agents. These components are mixed in specific proportions and participate in the reaction, ultimately forming a structurally stable foam body.
[0069] The base materials provide the core elasticity and mechanical foundation for the sponge, ensuring that the sponge has basic cushioning and deformation capabilities. Gradient-adjustable materials can control the foaming rate and cell growth state. Chemical and physical foaming agents work together to shape a gradient cell structure, while foam stabilizers maintain the integrity and uniformity of the cells, allowing the three-layer gradient open-cell structure to be formed smoothly, laying the structural foundation for sound absorption and vibration damping functions.
[0070] The compounded raw materials comprehensively optimize the molding effect and performance of the sponge. Catalysts accelerate the reaction process and improve production stability, crosslinking agents strengthen the internal structure and enhance resistance to deformation, reinforcing agents improve support and shock absorption, and anti-aging agents delay material aging and extend service life. The three types of raw materials each perform their specific functions while working together to achieve a comprehensive effect of controllable gradient structure, excellent mechanical properties, and long-term stable use in the sponge.
[0071] In one embodiment, the polyether polyol is polypropylene glycol with a molecular weight of 2000; the isocyanate is diphenylmethane diisocyanate; the chemical foaming agent is deionized water; the physical foaming agent is HFO-1234ze; the foam stabilizer is an organosilicon surfactant; the catalyst is a mixture of triethylenediamine and dibutyltin dilaurate; the crosslinking agent is glycerol; the reinforcing agent is nano-calcium carbonate modified with a silane coupling agent; and the anti-aging agent is a hindered phenolic anti-aging agent.
[0072] In this embodiment, the components of the polyurethane raw materials are selected. Polypropylene glycol with a molecular weight of 2000 is selected as the polyether polyol, and diphenylmethane diisocyanate is selected as the basic reaction raw material. Deionized water is selected as the chemical foaming agent, HFO-1234ze is selected as the physical foaming agent, and organosilicon surfactant is selected as the foam stabilizer. Triethylenediamine and dibutyltin dilaurate are used as a catalyst. Nano-calcium carbonate modified with silane coupling agent is selected as the reinforcing agent, and hindered phenolic anti-aging agent is selected as the anti-aging component. The above raw materials are uniformly mixed in a predetermined ratio and then participate in the foaming reaction to form a polyurethane system suitable for gradient cell molding.
[0073] Polypropylene glycol with a molecular weight in the 2,000s reacts with diphenylmethane diisocyanate to form flexible and stable polyurethane molecular chains, providing balanced elasticity and support for the sponge body. Deionized water and HFO-1234ze synergistic foaming control the cell growth rate in different regions, while silicone surfactants stabilize the cell morphology, preventing cell merging or rupture, ensuring a continuous and uniform three-layer gradient open-cell structure, and allowing the sponge's sound absorption and vibration damping structure to be stably formed.
[0074] The compound catalyst can simultaneously regulate chain growth and foaming rate, making the foaming process stable and controllable. Modified nano-calcium carbonate can effectively improve the structural strength and shock absorption performance of the sponge, and has good compatibility with the polyurethane system. Hindered phenolic anti-aging agents can inhibit material aging and degradation, maintaining the long-term stable performance of the sponge. The selected raw materials are mutually compatible, ensuring the smooth implementation of gradient foaming and online composite processes, while also improving the sound insulation and shock absorption effect and service life of the sponge.
[0075] This invention discloses a preparation process for preparing gradient-cell sound-insulating and vibration-damping polyurethane foam according to any one of the claims above, comprising the following steps: Step 1, raw material pretreatment: pretreatment of polyurethane raw materials and composite sound-insulating materials, and treatment of the mold; Step 2, raw material mixing: adding the pretreated polyurethane raw materials sequentially into a mixing tank to form a foaming slurry; Step 3, gradient cell molding: injecting the foaming slurry into the mold, using a gradient temperature control method with different temperatures for the upper, middle, and lower layers for foaming, and embedding local reinforcing ribs in the lower vibration-damping support layer during the foaming process to form a gradient cell structure; Step 4, simultaneous online foaming and lamination: first foaming the upper sound-absorbing layer to a semi-gel state, laying the sandwich composite layer, then pouring the middle and lower foaming slurries, and continuing gradient foaming for integrated molding; Step 5, curing, demolding, and maturation: curing the foamed product, cooling and demolding, and then maturation to obtain the finished product.
[0076] This manufacturing process utilizes a five-stage continuous operation to mold gradient-cell sound-insulating and vibration-damping polyurethane foam. First, the polyurethane raw materials undergo degassing and dispersion treatment. The composite sound-insulating material is then placed under constant temperature and humidity. Simultaneously, a release agent is evenly applied to the inner wall of the mold and allowed to dry. Next, the pre-treated raw materials are added to a mixing tank in a predetermined order and thoroughly stirred to form a foaming slurry with stable flowability and reactivity. The upper layer of slurry is poured and foamed to a semi-gel state. After laying the sandwich composite layer, the middle and lower layers of slurry are poured. Reinforcing ribs are embedded before the lower layer of slurry cures, allowing the slurry to fully penetrate the material gaps and form an interlocking structure. Finally, after constant temperature curing, cooling demolding, and environmental maturation, a complete finished product is obtained.
[0077] The specific method for pre-embedding local reinforcing ribs within the lower damping support layer during the foaming process is as follows: After the lower damping support layer slurry is poured and in the semi-gel stage before curing, a positioning and implantation mechanism pre-embedded in the top cover of the mold is activated. This mechanism consists of several sets of vertically distributed positioning pins, with pre-cut local reinforcing ribs fixed to the lower ends of the positioning pins. When the mold closes, the positioning pins move downwards at a uniform speed under the drive of the drive device. Utilizing the rigidity of the reinforcing ribs themselves and the guiding effect of the positioning pins, the reinforcing ribs are precisely pressed into the not-yet-fully-cured polyurethane foam matrix. Because the slurry is in a semi-gel state at this time, it has suitable viscosity and thixotropy. During the pressing process, the reinforcing ribs will displace the surrounding slurry rather than puncture the already formed cell walls. The slurry then flows back around the reinforcing ribs and fills the gaps. By controlling the downward pressure depth of the positioning pins or setting a limiting structure within the mold, the reinforcing ribs can be accurately implanted within the 77%-83% range. After the foaming reaction is complete and cured, the positioning pin is pulled out, and the reinforcing ribs are firmly embedded inside the sponge matrix, forming a gradient reinforcement structure that is seamlessly integrated with the matrix, effectively avoiding the damage to the cell structure caused by traditional post-processing insertion.
[0078] This process utilizes gradient temperature-controlled foaming to create a continuous cell structure with a large pore size in the upper layer, a medium pore size in the middle layer, and a small pore size in the lower layer. Pre-embedded reinforcing ribs during the foaming process allow the ribs to solidify synchronously with the sponge body, preventing damage to the cell morphology during subsequent processing. Online lamination during the semi-gel stage enables the sponge slurry and composite sound insulation material to form a physical bond and interface fusion, achieving a strong connection without the need for adhesives. This ensures the integrity and stability of the structure from the molding stage.
[0079] The integrated manufacturing process simplifies the multi-step processing of traditional sponges, reducing dimensional deviations and poor bonding caused by secondary lamination. The synergistic effect of gradient temperature control and online lamination allows sound absorption, sound insulation, and vibration damping to be achieved simultaneously during the molding process. The finished product has good structural uniformity and strong interlayer bonding, and is not prone to delamination, deformation, or detachment during long-term use. At the same time, it has higher production efficiency and is suitable for stable batch production of high-performance sound insulation and vibration damping sponges.
[0080] As one implementation method, in step 3, the specific parameters for gradient temperature control foaming are as follows: the upper, middle and lower zones of the mold are independently controlled at constant temperature. The upper layer is maintained at 53-62℃ for 13-22 minutes; the middle layer is maintained at 43-52℃ for 18-27 minutes; and the lower layer is maintained at 33-42℃ for 23-32 minutes. A gradient cell structure is formed by partitioned constant temperature and differentiated holding time.
[0081] To achieve precise and independent temperature control in the upper, middle, and lower layers, this process employs a zoned, independently temperature-controlled mold system. Each zone is equipped with forced circulation cooling and dynamic temperature compensation units to offset the heat of the foaming reaction in real time, maintaining a stable temperature gradient from top to bottom. The upper layer is set at 53-62℃, the middle layer at 43-52℃, and the lower layer at 33-42℃. By matching the temperatures and holding times of the upper and lower zones, the growth rate and molding state of each layer of foam cells are controlled. The mold is preheated to the set temperatures in all three zones before each layer of slurry is poured sequentially. After each layer is poured, foaming is independently controlled at the corresponding temperature.
[0082] The higher temperature in the upper layer accelerates the foaming reaction, allowing the cells to fully expand and form a large-diameter open-cell structure. The appropriate heat preservation time ensures that the upper layer cells are formed completely and do not break. The moderate temperature and heat preservation time in the middle layer can smoothly connect the foaming processes of the upper and lower layers, forming a uniform medium-diameter transition structure, so that the cells inside the sponge show a continuous and smooth gradient change.
[0083] The lower temperature of the lower layer can inhibit excessive expansion of the foam cells, forming a dense small-pore shock-absorbing support structure. The longer insulation time allows the lower layer material to fully cross-link and solidify, improving the overall support strength and deformation resistance. This set of gradient temperature control parameters works together to stably achieve a foam cell arrangement with gradually decreasing pore size from top to bottom, providing core structural support for the sponge's efficient sound absorption, sound insulation and stable shock absorption.
[0084] As one implementation method, in step 4, the criteria for judging the semi-gel stage are: the cells are initially formed but not completely cured, which can be monitored through the mold visualization window and / or height displacement sensor, and the foam volume of the sponge expands to 50%-65% of the mold volume; in step 5, the specific parameters for curing, demolding and maturation are: constant temperature curing at 70-80℃ for 70-80 min, demolding after cooling for 30 min, and maturation at 23-27℃ and 45%-55% humidity for 32-40 h.
[0085] During the foaming process, the sponge's forming status is monitored in real time. The pressure sensor inside the mold can determine when the foam cells have initially formed but the whole structure has not yet fully solidified, and when the upper foaming slurry has foamed to 50%-65% of the height of the corresponding area of the mold, the material is judged to have entered the semi-gel stage. At this time, the volume expansion ratio is used as the core judgment basis, and the optimal timing for composite operation is locked in conjunction with the foam cell forming status.
[0086] The material in the semi-gel stage has both a solid foundation and flow viscosity. The initial formation of cells can maintain the basic structural shape of the sponge and avoid structural collapse during the composite operation. The 50%-65% volume expansion ratio leaves enough space for subsequent foaming, which can ensure that the composite sponge can completely fill the mold and form a regular structure.
[0087] Implementing simultaneous online foaming and lamination at this stage allows the polyurethane slurry to fully penetrate the gaps in the composite sound insulation material, forming a strong interlocking structure after curing. This prevents premature foam cell formation from being damaged and delayed lamination from resulting in a loose bond, thereby enhancing the bonding strength between the sponge and the composite sound insulation layer and ensuring the stable performance of the overall sound insulation and vibration damping of the product.
[0088] Example 1 (Standard Parameter Set)
[0089] Raw material formula (by weight parts)
[0090] 100 parts of propylene glycol (molecular weight 2000), 50 parts of diphenylmethane diisocyanate, 2.5 parts of deionized water, 8 parts of HFO-1234ze, 1.5 parts of organosilicon surfactant, 0.3 parts of triethylenediamine, 0.1 parts of dibutyltin dilaurate, 1.2 parts of glycerol, 5 parts of silane coupling agent modified nano-calcium carbonate, and 0.5 parts of hindered phenolic anti-aging agent.
[0091] Preparation of composite sound insulation layer
[0092] The polyester fiber nonwoven fabric is activated by oxygen-argon mixed plasma, and the surface of the damping PET film is coated with a homologous polyurethane prepolymer layer. The two are combined into an integral composite sound insulation layer.
[0093] Preparation process
[0094] Raw material pretreatment: Polyether polyol is allowed to stand at room temperature for 10 minutes to remove bubbles; reinforcing agent is dispersed at 2200 r / min for 35 minutes; composite sound insulation material is allowed to stand at 25℃ and 50% humidity for 20 minutes; mold is coated with silicone release agent and dried for 15 minutes.
[0095] Raw material mixing: Polyether polyol, stabilizer, crosslinking agent, anti-aging agent are mixed in sequence, catalyst and deionized water are added, HFO-1234ze and isocyanate are added and stirred at high speed to obtain foaming slurry.
[0096] Gradient foaming: Slurry is injected into the mold, and the temperature is controlled by gradient foaming: upper layer 58℃ / 18min, middle layer 48℃ / 23min, lower layer 38℃ / 28min; 6.5min after injection, matrix-style local reinforcing ribs are pre-embedded with a diameter of 0.7mm and a spacing of 2.5cm, and the insertion depth is 80% of the thickness of the lower layer.
[0097] Simultaneous online foaming and lamination: First, foam the upper sound-absorbing layer to the semi-gel stage (volume reaches 60% of the mold), then lay the sandwich composite layer, then pour the middle and lower foaming slurry, and finally lay the surface composite layer on the outer surface of the upper sound-absorbing layer, and continue gradient foaming to form an integral mold.
[0098] Curing, demolding, and maturation: Curing at 75℃ for 75 minutes, cooling for 30 minutes, demolding and trimming, and maturation at 25℃ and 50% humidity for 36 hours to obtain the finished sponge.
[0099] Example 2 (Low Temperature Gradient Group)
[0100] Raw material formula
[0101] Completely consistent with Example 1.
[0102] Preparation process
[0103] Only the gradient temperature control parameters were adjusted: upper layer 53℃ / 22min, middle layer 43℃ / 27min, lower layer 33℃ / 32min; the local reinforcing rib insertion depth was 77%, and the rest of the process and parameters were exactly the same as in Example 1.
[0104] Example 3 (High Temperature Gradient Group)
[0105] Raw material formula
[0106] Completely consistent with Example 1.
[0107] Preparation process
[0108] Only the gradient temperature control parameters were adjusted: upper layer 62℃ / 13min, middle layer 52℃ / 18min, lower layer 42℃ / 23min; the local reinforcing rib insertion depth was 83%, and the rest of the process and parameters were exactly the same as in Example 1.
[0109] Example 4 (Small Diameter Reinforcing Rib Group)
[0110] Raw material formula
[0111] Completely consistent with Example 1.
[0112] Preparation process
[0113] The local reinforcing ribs have a diameter of 0.45 mm, a spacing of 1.8 cm, and an insertion depth of 80%. The gradient temperature control parameters are the same as in Example 1, and the remaining processes and parameters are exactly the same as in Example 1.
[0114] Example 5 (Large Diameter Reinforcing Rib Group)
[0115] Raw material formula
[0116] Completely consistent with Example 1.
[0117] Preparation process
[0118] The local reinforcing ribs have a diameter of 1.05 mm, a spacing of 3.2 cm, and an insertion depth of 80%. The gradient temperature control parameters are the same as in Example 1, and the remaining processes and parameters are exactly the same as in Example 1.
[0119] Comparative Example 1 (Conventional single-cell sponge)
[0120] Raw material formula
[0121] Completely consistent with Example 1.
[0122] Preparation process
[0123] Conventional constant temperature foaming (overall 45℃) was used, without gradient temperature control, local reinforcing ribs, or composite sound insulation layer. Only a single-pore polyurethane foam was prepared, and the remaining curing and maturation parameters were the same as in Example 1.
[0124] Comparative Example 2 (Conventional Post-attached Composite Sponge)
[0125] Raw material formula
[0126] Completely consistent with Example 1.
[0127] Preparation process
[0128] Gradient temperature controlled foaming is used, without local reinforcing ribs; after the sponge is fully cured, the sound insulation layer is pasted onto the sponge surface with environmentally friendly adhesive, without interlayer composite, without foaming online embedding, and the other parameters are the same as in Example 1.
[0129] Comparative Example 3 (Conventional Single-Layer Composite Sponge)
[0130] Raw material formula
[0131] Completely consistent with Example 1.
[0132] Preparation process
[0133] Gradient temperature controlled foaming and local reinforcing ribs were used; the sound insulation layer was only laminated on the surface of the sponge, without interlayer lamination, and an online foaming and lamination process was adopted. The remaining parameters were the same as in Example 1.
[0134] Performance tests were conducted in accordance with national standards under standard conditions. Sample conditioning and testing environment followed GB / T2918-2018 "Standard Environment for Conditioning and Testing of Plastic Samples," with a test temperature of 23℃±2℃ and relative humidity of 50%±5%. Sound insulation was tested using GB / T18696.1-2015 "Measurement of Sound Absorption Coefficient and Sound Insulation Ratio in Acoustic Impedance Tubes - Part 1: Standing Wave Tube Method," measuring airborne sound insulation in the 200Hz-1000Hz and 1000Hz-8000Hz frequency bands respectively. Vibration damping rate was tested according to the method specified in GB / T10802-2006 "Flexible Polyurethane Foam Plastics." Compression set was tested according to GB / T6669-2008 "Determination of Compression Set of Flexible Foam Polymer Materials." Peel strength was tested using GB / T16491-2008 "Determination of Peel Strength of Flexible Foam Polymer Materials."
[0135] The test results are shown in Table 1 below:
[0136]
[0137] Table 1
[0138] Test Conclusion
[0139] The sponges of Examples 1-5 of this invention have a sound insulation of ≥36dB in the 200-1000Hz frequency range, a sound insulation of ≥42dB in the 1000-8000Hz frequency range, a shock absorption rate of ≥68%, a compression set of ≤3.8%, and a peel strength of ≥19N / 25mm. All of these properties meet the preset targets.
[0140] Compared with existing technologies, the present invention significantly improves the sound insulation of the sponge, increases the shock absorption rate by more than 18%, reduces permanent compression deformation by more than 60%, and increases the peel strength of the composite layer by more than 100%.
[0141] Its core advantages stem from the synergistic effect of gradient foam structure, matrix-style local reinforcement ribs, surface + sandwich double composite sound insulation layer, and synchronous online foaming process, which solves the technical problems of poor sound insulation, weak shock absorption, and easy detachment of composite layers in traditional sponges.
[0142] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A gradient-cell sound-insulating and vibration-damping polyurethane sponge, characterized in that, include: The sponge body and the composite sound insulation layer; The sponge body has a three-layer gradient open-pore structure, from top to bottom: upper sound-absorbing layer, middle transition layer and lower vibration-damping support layer; The composite sound insulation layer includes a surface composite layer and a sandwich composite layer. The surface composite layer covers the outer surface of the upper sound-absorbing layer, and the sandwich composite layer is embedded in the middle transition layer. The composite sound insulation layer is made of sound-insulating non-woven fabric and damping PET film. The sponge body and the composite sound insulation layer are tightly bonded together through an interlocking structure formed by integral molding during the foaming process.
2. The gradient-cell sound-insulating and vibration-damping polyurethane sponge according to claim 1, characterized in that: The upper sound-absorbing layer has a large-pore open-cell structure, the middle transition layer has a medium-pore open-cell structure, and the lower vibration-damping support layer has a small-pore open-cell structure, with the pore size decreasing gradually from top to bottom.
3. The gradient-cell sound-insulating and vibration-damping polyurethane sponge according to claim 2, characterized in that: Local reinforcing ribs are installed inside the lower shock-absorbing support layer. The material of the local reinforcing ribs is the same as that of the sponge body, and they are distributed in a matrix inside the lower shock-absorbing support layer. The diameter of the local reinforcing ribs is 0.45-1.05mm, and the matrix arrangement spacing is 1.8-3.2cm.
4. The gradient-cell sound-insulating and vibration-damping polyurethane sponge according to claim 3, characterized in that: The depth to which the local reinforcing ribs are inserted into the lower damping support layer is 77%-83% of the layer thickness.
5. The gradient-cell sound-insulating and vibration-damping polyurethane sponge according to claim 1, characterized in that: The sound-insulating non-woven fabric is a polyester fiber non-woven fabric that has been activated by a plasma treatment of mixed oxygen and argon. The plasma activation parameters are: oxygen-argon volume ratio 1:2-1:4, power 200-300W, and processing time 30-60s. The surface of the damping PET film is coated with a polyurethane prepolymer layer that is homologous to the sponge body; Sound-insulating non-woven fabric and damping PET film are hot-pressed together to form a composite sound-insulating layer; The hot-pressing composite parameters are: temperature 80-100℃, pressure 0.2-0.4MPa, and time 10-20s.
6. The gradient-cell sound-insulating and vibration-damping polyurethane sponge according to claim 1, characterized in that: The sponge body is made of polyurethane raw materials including basic raw materials, gradient adjustment raw materials and compounded raw materials; The basic raw materials include polyether polyols and isocyanates; Gradient-adjustable raw materials include chemical foaming agents, physical foaming agents, and foam stabilizers; The compounded raw materials include catalysts, crosslinking agents, reinforcing agents, and anti-aging agents.
7. The gradient-cell sound-insulating and vibration-damping polyurethane sponge according to claim 6, characterized in that: The polyether polyol is polyoxypropylene glycol with a molecular weight of 2000; the isocyanate is diphenylmethane diisocyanate; The chemical foaming agent is deionized water, and the physical foaming agent is HFO-1234ze; The foam stabilizer is an organosilicon surfactant; The catalyst is a mixture of triethylenediamine and dibutyltin dilaurate; The cross-linking agent is glycerol; The reinforcing agent is nano-calcium carbonate modified with a silane coupling agent, and the anti-aging agent is a hindered phenolic anti-aging agent.
8. A preparation process for a gradient-cell sound-insulating and vibration-damping polyurethane sponge, characterized in that, The method for preparing any one of the gradient-cell sound-insulating and vibration-damping polyurethane foams according to claims 1-7 includes the following steps: Step 1, Raw material pretreatment: The polyurethane raw material and the composite sound insulation material are pretreated respectively, and the mold is treated; Step 2, Raw material mixing: Add the pretreated polyurethane raw materials into the mixing tank in sequence and mix to form a foaming slurry; Step 3, initial formation of gradient foam cells: Inject the upper foaming slurry into the corresponding area of the mold and perform gradient temperature-controlled foaming until it reaches a semi-gel state; Step 4, synchronous online foaming and reinforcement pre-embedding: lay a sandwich composite layer on the surface of the upper semi-gel, and then pour the middle transition layer and the lower shock-absorbing support layer foaming slurry in sequence. Pre-embedding local reinforcement ribs immediately before the lower slurry cures. The surface composite layer is laid on the inner wall of the mold, and gradient foaming is continued to form an integral mold. Step 5, Curing, Demolding and Curing: Curing the foamed product, cooling and demolding it, and then curing it to obtain the finished product.
9. The preparation process according to claim 8, characterized in that: In step 3, the specific parameters for gradient temperature controlled foaming are as follows: The mold has independent temperature control in three zones: upper, middle and lower. The upper zone is maintained at 53-62℃ for 13-22 minutes. Maintain the middle layer at 43-52℃ for 18-27 minutes; Maintain the lower layer at 33-42℃ for 23-32 minutes.
10. The preparation process according to claim 8, characterized in that: In step 4, the criteria for judging the semi-gel stage are: the cells have initially formed but have not been completely cured, and the foaming height reaches 50%-65% of the total height of the mold, as monitored by the mold visualization window and height displacement sensor; In step 5, the specific parameters for curing, demolding, and maturation are as follows: constant temperature curing at 70-80℃ for 70-80 minutes, demolding after cooling for 30 minutes, and maturation at 23-27℃ and 45%-55% humidity for 32-40 hours.