A composite foam material filled with biocrystal powder, its preparation method, and its application in a sleep pillow.

Abstract

This invention discloses a composite foam material filled with biocrystal powder, its preparation method, and its application in a sleep-aid pillow, belonging to the field of functional filler technology and patent classification number C08K3 / 34. The method includes first depositing polyphosphate ammonium onto the surface of melamine-formaldehyde prepolymer and acidified expandable graphite, followed by curing to obtain an intumescent flame retardant; synthesizing a castor oil-based flexible segment prepolymer via transesterification; and modifying aluminosilicate fibers with a silane coupling agent. The polyol, flexible prepolymer, biocrystal powder, flame retardant, modified fibers, catalyst, etc., are mixed and foamed with polyisocyanate to obtain the composite material. This invention achieves high-efficiency flame retardancy through the synergistic effect of the flame retardant's microscopic carbon source-acid source-gas source; the castor oil-based flexible segments impart high resilience and sustained compression recovery to the material; and the biocrystal powder helps improve sleep quality, thus combining flame retardancy, high resilience, and sleep-aiding functions.

Description

Technical Field

[0001] This invention relates to the field of functional filler technology, belonging to patent classification number C08K3 / 34, specifically to a composite foam material filled with biocrystal powder, its preparation method, and its application in a sleep-inducing pillow. Background Technology

[0002] Polyurethane foam is a polymer material formed by the addition polymerization reaction of polyols and polyisocyanates. It possesses excellent properties such as low density, good elasticity, sound insulation, noise reduction, and cushioning energy absorption, and has long been widely used in home furnishings, car seats, and medical care. Especially in sleep products such as pillows and mattresses, polyurethane foam has become one of the most favored core materials by consumers due to its excellent body pressure dispersion ability and comfortable feel. However, with the continuous improvement of people's requirements for sleep quality and home safety, two prominent technical shortcomings of traditional polyurethane foam have increasingly attracted the attention and concern of the industry. The first shortcoming is its severely insufficient flame retardant performance. Polyurethane foam is an organic polymer material, containing a large amount of carbon and hydrogen elements in its molecular chain. Its limiting oxygen index is typically only 16-18%, making it a flammable material. Once exposed to open flames or high-temperature heat sources, polyurethane foam will burn and spread rapidly, releasing large amounts of toxic fumes such as carbon monoxide and hydrogen cyanide during combustion, not only accelerating the spread of fire but also posing a serious threat to human life. The second shortcoming is the significant decrease in resilience after long-term use. After repeated compression-recovery cycles, the molecular chains in the cell walls of ordinary polyurethane foam undergo irreversible plastic deformation and stress relaxation, resulting in the pillow gradually collapsing and deforming, reducing its support, and making it difficult to continuously provide effective cervical spine support and fit for the user. For bedding products such as sleep pillows that need to withstand repeated head pressure over a long period, the foam's resilience and compression set directly affect the product's lifespan and sleep experience. Insufficient resilience has become a key bottleneck restricting the application of polyurethane foam in the mid-to-high-end bedding market. Inorganic flame-retardant fillers (such as aluminum hydroxide, magnesium hydroxide, and ammonium polyphosphate) introduced into polyurethane foam materials to improve flame retardancy are rigid particles. After embedding into the cell walls, they disrupt the original uniform cell structure of the foam, increase the rigidity of the cell walls, and restrict the free extension and retraction of molecular chains, thus leading to a decrease in resilience and an increase in compression set. How to coordinate and resolve the contradiction between flame retardancy and high resilience in the same material system, while ensuring the functionality of bio-crystal powder, is a current technical challenge facing the industry. Summary of the Invention

[0003] The purpose of this invention is to provide a composite foam material filled with biocrystal powder and its preparation method, so as to solve the technical problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a composite foam material filled with biocrystal powder includes the following steps: 1) Preparation of biocrystal powder; 2) Melamine and formaldehyde aqueous solution are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer solution; expandable graphite is acidified and modified with concentrated sulfuric acid and potassium permanganate to obtain acidified expandable graphite; the melamine-formaldehyde prepolymer solution, acidified expandable graphite and ammonium polyphosphate are mixed and heated to allow the prepolymer to deposit and condense on the particle surface to form a resin coating layer; then the system is adjusted to acidity to carry out curing and crosslinking reaction; after washing, drying and grinding, melamine-formaldehyde resin-coated intumescent flame retardant is obtained. 3) Castor oil polyol and polycaprolactone diol undergo transesterification under the protection of a catalyst and nitrogen, and byproducts are removed by depressurization to obtain castor oil-based flexible segment prepolymer. 4) Surface grafting modification treatment of aluminosilicate fibers was performed using an aminosilane coupling agent to obtain modified aluminosilicate fibers; 5) Mix polyether polyol, polymer polyol, castor oil-based flexible segment prepolymer obtained in step 3), hydroxyl-terminated polybutadiene, biocrystal powder obtained in step 1), melamine-formaldehyde resin-coated intumescent flame retardant obtained in step 2), nano-montmorillonite, modified aluminum silicate fiber obtained in step 4), foaming agent, foam stabilizer and catalyst evenly to obtain a mixture; 6) Mix the mixture with polyisocyanate, inject it into a mold for foaming and curing, demold and then perform post-curing to obtain the composite foam material.

[0005] The principle behind this invention's improvement of the flame retardancy of composite foam materials is as follows: the melamine-formaldehyde resin coating layer integrates expandable graphite and ammonium polyphosphate, two flame-retardant components, into the same microparticle structure, achieving precise coordination of the three elements—carbon source, acid source, and gas source—at the microscale. When the material is heated, ammonium polyphosphate decomposes to release polyphosphoric acid, catalyzing the carbonization of melamine-formaldehyde resin to form a dense charcoal protective layer. Simultaneously, expandable graphite expands upon heating, generating numerous worm-like expanded carbon layers. These expanded carbon layers intertwine and nest with the carbon layers catalyzed by ammonium polyphosphate, forming a multi-layered barrier structure that effectively isolates heat transfer and the diffusion of combustible gases. Furthermore, the non-flammable gases such as ammonia released by the sublimation and decomposition of melamine at high temperatures dilute the concentration of combustible gases, further inhibiting the continued combustion reaction. The increased interlayer spacing of the acid-modified expandable graphite significantly improves thermal expansion efficiency, enabling the formation of a more fluffy and complete expanded carbon layer upon heating, enhancing the oxygen-barrier effect. The melamine-formaldehyde resin coating also improves surface compatibility, allowing flame-retardant particles to be uniformly dispersed in the polyurethane matrix. This avoids weak flame-retardant areas caused by agglomeration, thus ensuring the uniformity and reliability of flame-retardant performance at the macroscopic level.

[0006] The principle behind this invention for improving the resilience of composite foam materials is as follows: starting with the soft segment structure of the polyurethane molecular chain, the microphase separation morphology of the foam is controlled by introducing a castor oil-based flexible segment prepolymer. The C18 long-chain fatty acid segments, primarily composed of ricinoleic acid, in the castor oil molecular structure provide excellent flexibility and internal rotational capability for the polyurethane soft segments, allowing the molecular chains to smoothly extend and coil under external forces. The ester bond flexible units in polycaprolactone diol synergistically work with the long-chain alkyl groups of castor oil to further lower the glass transition temperature of the soft segments and broaden the high-elasticity response window of the material at room temperature. The castor oil-based flexible segment prepolymer, prepared through a prepolymerization reaction, has precisely controlled molecular weight and branching degree, enabling it to be uniformly embedded in the soft segment phase during polyurethane foaming, optimizing the molecular chain packing density and free volume distribution of the soft segment phase. This optimization enhances the conformational recovery driving force of the soft segment molecular chains during repeated compression-recovery cycles, accelerating the rebound speed and reducing permanent deformation. Meanwhile, the secondary hydroxyl groups contained in castor oil polyol participate in the construction of the polyurethane cross-linking network, forming a moderately cross-linked elastic network structure, which not only ensures sufficient mechanical strength, but also endows the foam with excellent compression resilience.

[0007] Preferably, in step 1), the biocrystal powder comprises the following components in parts by weight: 81-81.3 parts silicon dioxide, 4.2-4.5 parts aluminum oxide, 3.1-3.5 parts calcium oxide, 0.8-1.2 parts iron oxide, and 2.2-2.6 parts magnesium oxide.

[0008] This invention incorporates biocrystal powder filler into polyurethane foam materials. Biocrystal powder can release specific and stable physical signals, which are believed to have a positive regulatory effect on human physiological state, including helping to improve immune system function, promoting metabolism, relieving muscle tension, regulating heart rate and respiratory rhythm, improving body oxygenation level, reducing mental stress, and improving sleep quality.

[0009] Preferably, in step 2), the mass ratio of the melamine-formaldehyde prepolymer solution, acidified expandable graphite, and ammonium polyphosphate is 27:(2-5):(4-8).

[0010] Preferably, in step 2), the curing and crosslinking reaction temperature is 50–65°C, and the curing and crosslinking reaction time is 0.8–1.5 h.

[0011] Preferably, in step 3), the catalyst is tetrabutyl titanate; and the mass ratio of castor oil polyol to polycaprolactone diol is (2.5-3.5):1.

[0012] Preferably, in step 4), the aminosilane coupling agent is aminopropyltriethoxysilane; The amount of aminopropyltriethoxysilane used is 1.5% to 3.5% of the mass of aluminum silicate fiber.

[0013] Preferably, in step 5), the mass ratio of the hydroxyl-terminated polybutadiene to the modified aluminum silicate fiber is 1.2:(0.6-1.0).

[0014] This invention discovered in experiments that the prepared melamine-formaldehyde resin-coated intumescent flame retardant, as a rigid inorganic-organic composite particle, embeds itself in the cell walls during foaming, creating stress concentration points. The rigid particles in the cell walls significantly restrict the extension and retraction of the flexible molecular chains constructed from the castor oil-based flexible segment prepolymer. This leads to the easy initiation of microcracks in the cell walls at the interface between the rigid particles and the flexible matrix during repeated compression. The foam's resilience decreases significantly with increasing compression cycles, indicating that the flame-retardant filler in the composite foam material negatively impacts its high resilience performance. To address this technical problem, this invention introduces modified aluminosilicate fibers and hydroxyl-terminated polybutadiene into the technical solution. In this process, the aluminum silicate fiber surface treated with γ-aminopropyltriethoxysilane coupling agent introduces amino active groups. These amino groups can form chemical bonds with the isocyanate groups in the rigid segments of polyurethane, firmly anchoring the fiber in the cell wall matrix. The bridging effect of the fiber effectively disperses the local stress around the rigid flame-retardant particles, inhibiting the initiation and propagation of microcracks. Hydroxyl-terminated polybutadiene, with its non-polar long-chain hydrocarbon backbone structure and extremely low glass transition temperature, provides high flexibility, forming a flexible transition interface layer between the rigid flame-retardant particles and the flexible polyurethane matrix. This flexible buffer layer absorbs and dissipates the interfacial stress caused by the modulus difference between the rigid particles and the flexible matrix, allowing the cell wall to maintain structural integrity during repeated compression-recovery processes. The skeletal reinforcement effect of modified aluminosilicate fiber and the interfacial buffering effect of hydroxyl-terminated polybutadiene work synergistically to simultaneously enhance the structure and soften the interface, effectively mitigating the negative impact of rigid flame-retardant fillers on the long-lasting resilience of foam. This allows the material to achieve excellent flame-retardant properties while maintaining a high resilience rate with minimal attenuation after multiple compression cycles.

[0015] Preferably, in step 5), the foaming agent is deionized water; the foam stabilizer is silicone oil; and the catalyst is composed of dibutyltin dilaurate and triethylenediamine.

[0016] A composite foam material filled with biocrystal powder is prepared by the method described above.

[0017] Application of a composite foam material filled with biocrystal powder in a sleep pillow.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. Expandable graphite and ammonium polyphosphate are encapsulated together using melamine-formaldehyde resin, achieving microscopic synergy between carbon source, acid source, and gas source. When heated, it forms a dense and expandable multi-layered carbonaceous barrier, effectively isolating oxygen and heat and diluting flammable gases, significantly improving the flame retardancy rating and reliability of the material.

[0019] 2. By introducing castor oil-based flexible segment prepolymers, the synergistic compliance effect of their long carbon chains and ester bonds is utilized to lower the glass transition temperature of the soft segments and broaden the elastic response window. This enhances the driving force for conformational recovery of the foam after compression, resulting in faster rebound speed and lower permanent deformation.

[0020] 3. Biocrystalline powder can continuously release specific physical signals, which can help reduce mental stress, relieve muscle tension, regulate heart rate and breathing rhythm, thereby increasing the body's oxygen content and helping to improve sleep quality.

[0021] 4. By combining the stress dispersion of modified aluminum silicate fiber with the flexible interface buffer of hydroxyl-terminated polybutadiene, the damage to the foam's resilience caused by rigid flame-retardant particles is effectively mitigated. This allows the material to maintain a high resilience rate with minimal attenuation after repeated compression, while also possessing high flame retardancy. Attached Figure Description

[0022] Figure 1 This is a SEM image of the microstructure of the composite foam material prepared in Example 4 of the present invention at a magnification of 50×.

[0023] Figure 2 This is a SEM image of the microstructure of the composite foam material prepared in Example 4 of the present invention at a magnification of 500×.

[0024] Figure 3 This is a SEM image of the microstructure of the composite foam material prepared in Example 4 of the present invention at a magnification of 5000×.

[0025] Figure 4 The image shows the XRD pattern of the composite foam material prepared in Example 4 of this invention. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for preparing a composite foam material filled with biocrystal powder includes the following steps: Step 1) Weigh out 81.2 parts by weight of silicon dioxide, 4.4 parts by weight of aluminum oxide, 3.4 parts by weight of calcium oxide, 1.1 parts by weight of iron oxide and 2.5 parts by weight of magnesium oxide. Mix the above components and put them into a planetary ball mill and ball mill at 400 r / min for 2.5 h. Then pass them through a 1000 mesh sieve to obtain biocrystal powder.

[0029] Step 2) Add 10g of melamine and 17g of a 37% (w / w) formaldehyde aqueous solution to a three-necked flask. Adjust the pH to 8.2 by adding triethanolamine dropwise. React for 1.5h in a 72℃ water bath with stirring at 350r / min to obtain a melamine-formaldehyde prepolymer solution. Separately, add 10g of 80-mesh expandable graphite to 35g of concentrated sulfuric acid. Add 0.7g of potassium permanganate in three portions, stir at room temperature for 2.5h, filter, wash with water until the pH of the filtrate is 6.5, and dry at 80℃ for 4h to obtain acidified expandable graphite. Heat 27g of the above melamine-formaldehyde prepolymer solution to 82℃, add 4g of acidified expandable graphite and 7g of ammonium polyphosphate sequentially, and stir at 82℃ for 2.5h to allow the prepolymer to deposit and condense on the particle surface to form a resin coating layer. The reaction product was cooled to room temperature, and 10% citric acid aqueous solution was added to adjust the pH to 4.8. The product was then stirred and cured at 60°C for 1 hour to carry out the curing and crosslinking reaction. The product was then filtered, washed with water 3 times, vacuum dried at 60°C for 8 hours, and ground through a 200-mesh sieve to obtain melamine-formaldehyde resin coated intumescent flame retardant (MF@IFR).

[0030] Step 3) Add 32g of castor oil polyol (hydroxyl value 160mgKOH / g) and 10g of polycaprolactone diol (molecular weight 1000) to a four-necked flask at a mass ratio of 3:1. Add 0.04g of tetrabutyl titanate as a catalyst. Under nitrogen protection, heat to 155℃ and stir at normal pressure for 1 hour. Then turn on the vacuum pump to reduce the pressure to -0.095MPa and continue the reaction for 2 hours to remove the transesterification byproducts glycerol and small molecule alcohol. Cool down to below 60℃ and discharge to obtain castor oil-based flexible segment prepolymer.

[0031] Step 4) Disperse 5g of aluminosilicate fiber in 100mL of ethanol / water (volume ratio 9:1), and add 0.15g of... Aminopropyltriethoxysilane was stirred at 62°C for 1.5 h, filtered, and dried at 80°C for 4 h to obtain modified aluminum silicate fibers.

[0032] Step 5) Mix 55 parts of polyether polyol (hydroxyl value 33 mg KOH / g) and 20 parts of polymer polyol (hydroxyl value 28 mg KOH / g) at 52°C until homogeneous. Then add 10 parts of castor oil-based flexible segment prepolymer obtained in Step 3), 1.2 parts of hydroxyl-terminated polybutadiene (number average molecular weight 2500), 15 parts of biocrystal powder obtained in Step 1), 8 parts of MF@IFR flame retardant obtained in Step 2), 2 parts of nano-montmorillonite, 0.9 parts of modified aluminum silicate fiber obtained in Step 4), 3 parts of deionized water, 2.0 parts of silicone oil foam stabilizer, 0.1 parts of dibutyltin dilaurate, and 0.45 parts of triethylenediamine. Stir at 1800 r / min for 2.5 min to obtain the mixture.

[0033] Step 6) Add 55 parts of modified MDI (PM-200 type, NCO content 30.5%) to the mixture in Step 5), stir rapidly at 2800 r / min for 10s, immediately pour into a mold preheated to 48℃, allow free foaming, cure at 52℃ for 18min, demold and place at room temperature for 24h for post-curing to obtain the composite foam material filled with biocrystal powder.

[0034] Example 2

[0035] A method for preparing a composite foam material filled with biocrystal powder includes the following steps: Step 1) Weigh out 81.1 parts by weight of silicon dioxide, 4.3 parts by weight of aluminum oxide, 3.2 parts by weight of calcium oxide, 0.9 parts by weight of iron oxide and 2.3 parts by weight of magnesium oxide. Mix the above components and put them into a planetary ball mill and ball mill at 400 r / min for 2.5 h. Then pass them through a 1000 mesh sieve to obtain biocrystal powder.

[0036] Step 2) Add 10g of melamine and 17g of a 37% (w / w) formaldehyde aqueous solution to a three-necked flask, and adjust the pH to 8.2 by adding triethanolamine dropwise. React for 1.5h in a 72℃ water bath with stirring at 350r / min to obtain a melamine-formaldehyde prepolymer solution. Separately, add 10g of 80-mesh expandable graphite to 35g of concentrated sulfuric acid, and add 0.7g of potassium permanganate in three portions. Stir at room temperature for 2.5h, filter, wash with water until the pH of the filtrate is 6.5, and dry at 80℃ for 4h to obtain acidified expandable graphite. Heat 27g of the above melamine-formaldehyde prepolymer solution to 82℃, and add 3g of acidified expandable graphite and 5g of ammonium polyphosphate sequentially. Stir and react at 82℃ for 2.5h to allow the prepolymer to deposit and condense on the particle surface to form a resin coating layer. The reaction product was cooled to room temperature, and 10% citric acid aqueous solution was added to adjust the pH to 4.8. The product was then stirred and cured at 60°C for 1 hour to carry out the curing and crosslinking reaction. The product was then filtered, washed with water 3 times, vacuum dried at 60°C for 8 hours, and ground through a 200-mesh sieve to obtain melamine-formaldehyde resin coated intumescent flame retardant (MF@IFR).

[0037] Step 3) 28g of castor oil polyol (hydroxyl value 160mgKOH / g) and 10g of polycaprolactone diol (molecular weight 1000) were added to a four-necked flask at a mass ratio of 3:1. 0.04g of tetrabutyl titanate was added as a catalyst. The mixture was heated to 155℃ under nitrogen protection and stirred at normal pressure for 1 hour. Then, the vacuum pump was turned on to reduce the pressure to -0.095MPa and the reaction was continued for 2 hours to remove the transesterification byproducts glycerol and small molecule alcohols. The mixture was then cooled to below 60℃ and discharged to obtain castor oil-based flexible segment prepolymer.

[0038] Step 4) Disperse 5g of aluminosilicate fiber in 100mL of ethanol / water (volume ratio 9:1), and add 0.10g of... Aminopropyltriethoxysilane was stirred at 62°C for 1.5 h, filtered, and dried at 80°C for 4 h to obtain modified aluminum silicate fibers.

[0039] Step 5) Mix 55 parts of polyether polyol (hydroxyl value 33 mg KOH / g) and 20 parts of polymer polyol (hydroxyl value 28 mg KOH / g) at 52°C until homogeneous. Then add 10 parts of castor oil-based flexible segment prepolymer obtained in Step 3), 1.2 parts of hydroxyl-terminated polybutadiene (number average molecular weight 2500), 15 parts of biocrystal powder obtained in Step 1), 8 parts of MF@IFR flame retardant obtained in Step 2), 2 parts of nano-montmorillonite, 0.7 parts of modified aluminum silicate fiber obtained in Step 4), 3 parts of deionized water, 2.0 parts of silicone oil foam stabilizer, 0.1 parts of dibutyltin dilaurate, and 0.45 parts of triethylenediamine. Stir at 1800 r / min for 2.5 min to obtain the mixture.

[0040] Step 6) Add 55 parts of modified MDI (PM-200 type, NCO content 30.5%) to the mixture in Step 5), stir rapidly at 2800 r / min for 10s, immediately pour into a mold preheated to 48℃, allow free foaming, cure at 52℃ for 18min, demold and place at room temperature for 24h for post-curing to obtain the composite foam material filled with biocrystal powder.

[0041] Example 3

[0042] A method for preparing a composite foam material filled with biocrystal powder includes the following steps: Step 1) Weigh out 81.2 parts by weight of silicon dioxide, 4.4 parts by weight of aluminum oxide, 3.3 parts by weight of calcium oxide, 1.0 part by weight of iron oxide and 2.4 parts by weight of magnesium oxide. Mix the above components and put them into a planetary ball mill and ball mill at 400 r / min for 2.5 h. Then pass them through a 1000 mesh sieve to obtain biocrystal powder.

[0043] Step 2) Add 10g of melamine and 17g of 37% formaldehyde aqueous solution to a three-necked flask, adjust the pH to 8.2 by adding triethanolamine dropwise, and react for 1.5h in a 72℃ water bath with stirring at 350r / min to obtain a melamine-formaldehyde prepolymer solution. Separately, add 10g of 80-mesh expandable graphite to 35g of concentrated sulfuric acid, add 0.7g of potassium permanganate in three portions, stir at room temperature for 2.5h, filter, wash with water until the pH of the filtrate is 6.5, and dry at 80℃ for 4h to obtain acidified expandable graphite. Heat the above 27g of melamine-formaldehyde prepolymer solution to 82℃, add 3.5g of acidified expandable graphite and 6g of ammonium polyphosphate sequentially, and stir at 82℃ for 2.5h to allow the prepolymer to deposit and condense on the particle surface to form a resin coating layer. The reaction product was cooled to room temperature, and 10% citric acid aqueous solution was added to adjust the pH to 4.8. The product was then stirred and cured at 60°C for 1 hour to carry out the curing and crosslinking reaction. The product was then filtered, washed with water 3 times, vacuum dried at 60°C for 8 hours, and ground through a 200-mesh sieve to obtain melamine-formaldehyde resin coated intumescent flame retardant (MF@IFR).

[0044] Step 3) Add 30g of castor oil polyol (hydroxyl value 160mgKOH / g) and 10g of polycaprolactone diol (molecular weight 1000) to a four-necked flask at a mass ratio of 3:1. Add 0.04g of tetrabutyl titanate as a catalyst. Under nitrogen protection, heat to 155℃ and stir at normal pressure for 1 hour. Then turn on the vacuum pump to reduce the pressure to -0.095MPa and continue the reaction for 2 hours to remove the transesterification byproducts glycerol and small molecule alcohol. Cool down to below 60℃ and discharge to obtain castor oil-based flexible segment prepolymer.

[0045] Step 4) Disperse 5g of aluminosilicate fiber in 100mL of ethanol / water (volume ratio 9:1), and add 0.12g of... Aminopropyltriethoxysilane was stirred at 62°C for 1.5 h, filtered, and dried at 80°C for 4 h to obtain modified aluminum silicate fibers.

[0046] Step 5) Mix 55 parts of polyether polyol (hydroxyl value 33 mg KOH / g) and 20 parts of polymer polyol (hydroxyl value 28 mg KOH / g) at 52°C until homogeneous. Then add 10 parts of castor oil-based flexible segment prepolymer obtained in Step 3), 1.2 parts of hydroxyl-terminated polybutadiene (number average molecular weight 2500), 15 parts of biocrystal powder obtained in Step 1), 8 parts of MF@IFR flame retardant obtained in Step 2), 2 parts of nano-montmorillonite, 0.8 parts of modified aluminum silicate fiber obtained in Step 4), 3 parts of deionized water, 2.0 parts of silicone oil foam stabilizer, 0.1 parts of dibutyltin dilaurate, and 0.45 parts of triethylenediamine. Stir at 1800 r / min for 2.5 min to obtain the mixture.

[0047] Step 6) Add 55 parts of modified MDI (PM-200 type, NCO content 30.5%) to the mixture in Step 5), stir rapidly at 2800 r / min for 10s, immediately pour into a mold preheated to 48℃, allow free foaming, cure at 52℃ for 18min, demold and place at room temperature for 24h for post-curing to obtain the composite foam material filled with biocrystal powder.

[0048] Example 4

[0049] A method for preparing a composite foam material filled with biocrystal powder includes the following steps: Step 1) Weigh out 81.3 parts by weight of silicon dioxide, 4.5 parts by weight of aluminum oxide, 3.5 parts by weight of calcium oxide, 1.2 parts by weight of iron oxide and 2.6 parts by weight of magnesium oxide. Mix the above components and put them into a planetary ball mill and ball mill at 400 r / min for 2.5 h. Then pass them through a 1000 mesh sieve to obtain biocrystal powder.

[0050] Step 2) Add 10g of melamine and 17g of 37% formaldehyde aqueous solution to a three-necked flask, adjust the pH to 8.2 by adding triethanolamine dropwise, and react for 1.5h in a 72℃ water bath with stirring at 350r / min to obtain a melamine-formaldehyde prepolymer solution. Separately, add 10g of 80-mesh expandable graphite to 35g of concentrated sulfuric acid, add 0.7g of potassium permanganate in three portions, stir at room temperature for 2.5h, filter, wash with water until the pH of the filtrate is 6.5, and dry at 80℃ for 4h to obtain acidified expandable graphite. Heat the above 27g of melamine-formaldehyde prepolymer solution to 82℃, add 5g of acidified expandable graphite and 8g of ammonium polyphosphate sequentially, and stir at 82℃ for 2.5h to allow the prepolymer to deposit and condense on the particle surface to form a resin coating layer. The reaction product was cooled to room temperature, and 10% citric acid aqueous solution was added to adjust the pH to 4.8. The product was then stirred and cured at 65℃ for 1.5h to carry out the curing and crosslinking reaction. The product was then filtered, washed with water 3 times, vacuum dried at 60℃ for 8h, and ground through a 200-mesh sieve to obtain melamine-formaldehyde resin coated intumescent flame retardant (MF@IFR).

[0051] Step 3) Add 35g of castor oil polyol (hydroxyl value 160mgKOH / g) and 10g of polycaprolactone diol (molecular weight 1000) to a four-necked flask at a mass ratio of 3:1. Add 0.04g of tetrabutyl titanate as a catalyst. Under nitrogen protection, heat to 155℃ and stir at normal pressure for 1 hour. Then turn on the vacuum pump to reduce the pressure to -0.095MPa and continue the reaction for 2 hours to remove the transesterification byproducts glycerol and small molecule alcohol. Cool down to below 60℃ and discharge to obtain castor oil-based flexible segment prepolymer.

[0052] Step 4) Disperse 5g of aluminosilicate fiber in 100mL of ethanol / water (volume ratio 9:1), and add 0.175g of... Aminopropyltriethoxysilane was stirred at 62°C for 1.5 h, filtered, and dried at 80°C for 4 h to obtain modified aluminum silicate fibers.

[0053] Step 5) Mix 55 parts of polyether polyol (hydroxyl value 33 mg KOH / g) and 20 parts of polymer polyol (hydroxyl value 28 mg KOH / g) at 52°C until homogeneous. Then add 10 parts of castor oil-based flexible segment prepolymer obtained in Step 3), 1.2 parts of hydroxyl-terminated polybutadiene (number average molecular weight 2500), 15 parts of biocrystal powder obtained in Step 1), 8 parts of MF@IFR flame retardant obtained in Step 2), 2 parts of nano-montmorillonite, 1.0 part of modified aluminum silicate fiber obtained in Step 4), 3 parts of deionized water, 2.0 parts of silicone oil foam stabilizer, 0.1 parts of dibutyltin dilaurate, and 0.45 parts of triethylenediamine. Stir at 1800 r / min for 2.5 min to obtain the mixture.

[0054] Step 6) Add 55 parts of modified MDI (PM-200 type, NCO content 30.5%) to the mixture in Step 5), stir rapidly at 2800 r / min for 10s, immediately pour into a mold preheated to 48℃, allow free foaming, cure at 52℃ for 18min, demold and place at room temperature for 24h for post-curing to obtain the composite foam material filled with biocrystal powder.

[0055] Example 5

[0056] A method for preparing a composite foam material filled with biocrystal powder includes the following steps: Step 1) Weigh out 81 parts by weight of silicon dioxide, 4.2 parts by weight of aluminum oxide, 3.1 parts by weight of calcium oxide, 0.8 parts by weight of iron oxide and 2.2 parts by weight of magnesium oxide. Mix the above components and put them into a planetary ball mill and ball mill at 400 r / min for 2.5 h. Then pass them through a 1000 mesh sieve to obtain biocrystal powder.

[0057] Step 2) Add 10g of melamine and 17g of a 37% (w / w) formaldehyde aqueous solution to a three-necked flask. Adjust the pH to 8.2 by adding triethanolamine dropwise. React for 1.5h in a 72℃ water bath with stirring at 350r / min to obtain a melamine-formaldehyde prepolymer solution. Separately, add 10g of 80-mesh expandable graphite to 35g of concentrated sulfuric acid. Add 0.7g of potassium permanganate in three portions. Stir at room temperature for 2.5h. Filter, wash with water until the pH of the filtrate is 6.5, and dry at 80℃ for 4h to obtain acidified expandable graphite. Heat 27g of the above melamine-formaldehyde prepolymer solution to 82℃, and add 2g of acidified expandable graphite and 4g of ammonium polyphosphate sequentially. Stir at 82℃ for 2.5h to allow the prepolymer to deposit and condense on the particle surface to form a resin coating layer. The reaction product was cooled to room temperature, and 10% citric acid aqueous solution was added to adjust the pH to 4.8. The product was then stirred and cured at 50℃ for 0.8h to carry out the curing and crosslinking reaction. The product was then filtered, washed with water 3 times, vacuum dried at 60℃ for 8h, and ground through a 200-mesh sieve to obtain melamine-formaldehyde resin coated intumescent flame retardant (MF@IFR).

[0058] Step 3) Add 25g of castor oil polyol (hydroxyl value 160mgKOH / g) and 10g of polycaprolactone diol (molecular weight 1000) to a four-necked flask at a mass ratio of 3:1. Add 0.04g of tetrabutyl titanate as a catalyst. Under nitrogen protection, heat to 155℃ and stir at normal pressure for 1 hour. Then turn on the vacuum pump to reduce the pressure to -0.095MPa and continue the reaction for 2 hours to remove the transesterification byproducts glycerol and small molecule alcohol. Cool down to below 60℃ and discharge to obtain castor oil-based flexible segment prepolymer.

[0059] Step 4) Disperse 5g of aluminosilicate fiber in 100mL of ethanol / water (volume ratio 9:1), and add 0.075g of... Aminopropyltriethoxysilane was stirred at 62°C for 1.5 h, filtered, and dried at 80°C for 4 h to obtain modified aluminum silicate fibers.

[0060] Step 5) Mix 55 parts of polyether polyol (hydroxyl value 33 mg KOH / g) and 20 parts of polymer polyol (hydroxyl value 28 mg KOH / g) at 52°C until homogeneous. Then add 10 parts of castor oil-based flexible segment prepolymer obtained in Step 3), 1.2 parts of hydroxyl-terminated polybutadiene (number average molecular weight 2500), 15 parts of biocrystal powder obtained in Step 1), 8 parts of MF@IFR flame retardant obtained in Step 2), 2 parts of nano-montmorillonite, 0.6 parts of modified aluminum silicate fiber obtained in Step 4), 3 parts of deionized water, 2.0 parts of silicone oil foam stabilizer, 0.1 parts of dibutyltin dilaurate, and 0.45 parts of triethylenediamine. Stir at 1800 r / min for 2.5 min to obtain the mixture.

[0061] Step 6) Add 55 parts of modified MDI (PM-200 type, NCO content 30.5%) to the mixture in Step 5), stir rapidly at 2800 r / min for 10s, immediately pour into a mold preheated to 48℃, allow free foaming, cure at 52℃ for 18min, demold and place at room temperature for 24h for post-curing to obtain the composite foam material filled with biocrystal powder.

[0062] Comparative Example 1: The difference from Example 4 is that MF@IFR flame retardant is not added in step 5), while the remaining steps and dosages are exactly the same as in Example 4.

[0063] Comparative Example 2: The difference from Example 4 is that castor oil-based flexible segment prepolymer is not added in step 5), while the remaining steps and dosages are exactly the same as in Example 4.

[0064] Comparative Example 3: The difference from Example 4 is that in step 5), the modified aluminosilicate fibers added are replaced with an equal amount of unmodified aluminosilicate fibers. The aluminum silicate fibers treated with aminopropyltriethoxysilane were identical to those in Example 4 in terms of the remaining steps and dosages.

[0065] Comparative Example 4: The difference from Example 4 is that in step 2), 5g of unmodified expandable graphite, 8g of ammonium polyphosphate and 8g of melamine powder are directly physically mixed and ground through a 200-mesh sieve as a flame retardant, without melamine-formaldehyde resin coating treatment. The remaining steps and dosages are exactly the same as in Example 4.

[0066] Comparative Example 5: The difference from Example 4 is that modified aluminum silicate fiber and hydroxyl-terminated polybutadiene are not added in step 5), while the remaining steps and dosages are exactly the same as in Example 4.

[0067] Comparative Example 6: The difference from Example 4 is that in step 5), only 1.2 parts of hydroxyl-terminated polybutadiene are added instead of modified aluminum silicate fiber. The remaining steps and amounts are exactly the same as in Example 4.

[0068] Comparative Example 7: The difference from Example 4 is that in step 5), only 1.0 part of modified aluminum silicate fiber is added instead of hydroxyl-terminated polybutadiene. The remaining steps and amounts are exactly the same as in Example 4.

[0069] Performance testing: 1. Limiting Oxygen Index (LOI) Test: The composite foam materials prepared in each example and comparative example were cut into standard samples with a size of 150mm×10mm×10mm. The samples were vertically clamped in the sample holder of the oxygen index tester. The top of the sample was ignited under different oxygen-nitrogen mixed atmospheres. By gradually adjusting the oxygen concentration, the minimum oxygen volume fraction required for the sample to maintain combustion was measured, which is the limiting oxygen index (%). The average value of 5 samples in each group was taken.

[0070] 2. Vertical flammability rating (UL-94) test: Cut the composite foam material into standard specimens of 125mm×13mm×10mm, clamp them vertically, and ignite them twice with a Bunsen burner flame (10s each time). Record the flaming time (t1, t2) of the specimen after each ignition and whether it ignites the cotton below. Determine the flame retardancy rating (V-0, V-1, V-2 or no rating NR) according to the standard.

[0071] 3. Rebound rate test: Cut the composite foam material into samples with dimensions of 100mm×100mm×50mm. Drop a standard steel ball with a diameter of 16mm and a mass of 16.3g from a height of 500mm to impact the sample surface. Use a photoelectric sensor to record the rebound height of the steel ball. Rebound rate (%) = (rebound height / drop height) × 100%. Test each sample 5 times and take the average value.

[0072] 4. Compression set test: Cut the composite foam material into samples with dimensions of 50mm×50mm×25mm, compress them to 50% of their original thickness in a compression device, keep them in a constant temperature chamber of 70℃±1℃ for 22h, remove them and let them recover at room temperature for 30min, and measure the thickness of the recovered sample. Compression set (%) = (original thickness - recovered thickness) / (original thickness - compressed thickness) × 100%, and take the average value of 3 samples in each group of tests.

[0073] 5. Compression Cycle Rebound Rate Test: The composite foam material was cut into samples with dimensions of 150mm × 150mm × 50mm and placed on a fatigue testing machine. The samples were repeatedly compressed to 75% of their original thickness using compression-release cycles at a frequency of 1Hz for a total of 50,000 cycles. The rebound rate of the samples was measured before and after each cycle. Rebound rate (%) = (Rebound rate after cycle / Rebound rate before cycle) × 100%.

[0074] Table 1: Test Results of Examples and Comparative Samples

[0075] From the table above, we can obtain: Comparative Example 1, without the addition of MF@IFR flame retardant, exhibited a sharp drop in limiting oxygen index to 18.2%, failing to achieve any rating (NR) in vertical burning and completely lacking flame retardant capability. This demonstrates that MF@IFR flame retardant is the core component imparting flame retardant properties to the composite foam material. Notably, the resilience rate (67.0%) and resilience retention rate (96.5%) of Comparative Example 1 were slightly higher than those of Example 4. This, in turn, confirms the negative impact of rigid flame-retardant fillers on the resilience performance of foam, further illustrating the technical necessity of introducing a synergistic system of modified aluminosilicate fiber and hydroxyl-terminated polybutadiene to mitigate this negative impact.

[0076] Comparative Example 2, without the addition of castor oil-based flexible segment prepolymer, had a resilience of only 46.5%, a decrease of 29.9% compared to Example 4, and a compression set of 8.6%, an increase of 177% compared to Example 4. This indicates that the castor oil-based flexible segment prepolymer is a key functional component for improving the resilience of foam. Without the castor oil-based flexible segment prepolymer, the polyurethane soft segments lack the synergistic effect of long-chain flexible structures and ester bond flexible units. The soft segments have a higher glass transition temperature, and the driving force for conformational recovery after compression is insufficient, leading to a significant decrease in resilience and a significant increase in compression set.

[0077] Comparative Example 3 replaced the modified aluminosilicate fibers with an equal amount of untreated aluminosilicate fibers. Its resilience (63.5%) decreased only slightly compared to Example 4, but after 50,000 cycles, the resilience retention rate dropped to 90.6%, a decrease of 6.4 percentage points compared to Example 4, and the compression set also increased from 3.1% to 5.6%. This indicates that the untreated aluminosilicate fibers, lacking amino active groups on their surface, cannot form chemical bonds with the polyurethane matrix. The fibers are only physically anchored within the cell walls, making them prone to slippage and debonding during repeated compression. This prevents them from effectively dispersing stress and bridging cracks, resulting in a significant decrease in the foam's fatigue resistance.

[0078] Comparative Example 4 used a physical mixture of expandable graphite, ammonium polyphosphate, and melamine powder to replace the MF@IFR flame retardant. Its limiting oxygen index was only 24.3%, a decrease of 7.2 percentage points compared to Example 4, and its vertical burning rating decreased from V-0 to V-1. This demonstrates that the melamine-formaldehyde resin coating structure is crucial for improving flame retardant efficiency: the coating structure integrates and coordinates the three elements of carbon source, acid source, and gas source at the microscale, enabling synchronous and synergistic response upon heating; while the physically mixed flame retardant components are dispersed individually in the foam matrix, failing to achieve precise coordination at the microscale, significantly reducing the synergistic flame retardant efficiency. Furthermore, uncoated flame retardant particles have poor dispersion in the matrix, easily agglomerating to form weak flame retardant areas, further reducing flame retardant reliability. Meanwhile, the rebound rate of Comparative Example 4 (58.2%) was also significantly lower than that of Example 4. This is because the uncoated flame retardant particles have rough surfaces and poor compatibility, forming more stress concentration points in the cell walls, causing more severe damage to the foam's rebound performance.

[0079] Comparative Example 5, which simultaneously removed both modified aluminosilicate fibers and hydroxyl-terminated polybutadiene, exhibited a rebound retention rate of only 85.3% after 50,000 cycles, the lowest among all samples, representing a significant decrease of 11.5 percentage points compared to Example 4. Its compression set also increased from 3.1% to 7.5%. This result strongly demonstrates that the synergistic system of modified aluminosilicate fibers and hydroxyl-terminated polybutadiene plays an indispensable role in maintaining the sustained resilience of foams containing rigid flame-retardant fillers. Without this synergistic system, the interfacial stress between the rigid MF@IFR particles and the flexible matrix cannot be effectively buffered and dispersed. Microcracks continuously develop and accumulate in the cell walls during repeated compression, leading to a continuous decline in resilience with increasing cycle count.

[0080] Comparative Example 6, which added only hydroxyl-terminated polybutadiene without modified aluminosilicate fibers, and Comparative Example 7, which added only modified aluminosilicate fibers without hydroxyl-terminated polybutadiene, showed rebound retention rates of 91.5% and 91.0% after 50,000 cycles, respectively. Both were significantly lower than the 96.8% of Example 4, but higher than the 85.3% of Comparative Example 5. This set of comparative data clearly demonstrates that the interfacial buffering effect of hydroxyl-terminated polybutadiene and the skeletal reinforcement effect of modified aluminosilicate fibers can only provide partial improvement when used independently. Both must work synergistically to fully leverage the dual effects of structural reinforcement and interfacial softening, effectively mitigating the negative impacts of rigid flame-retardant fillers.

[0081] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the essence and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite foam material filled with biocrystal powder, characterized in that, Includes the following steps: 1) Preparation of biocrystal powder; 2) Melamine and formaldehyde aqueous solution are reacted under alkaline conditions to obtain melamine-formaldehyde prepolymer solution; expandable graphite is acidified and modified with concentrated sulfuric acid and potassium permanganate to obtain acidified expandable graphite; the melamine-formaldehyde prepolymer solution, acidified expandable graphite and ammonium polyphosphate are mixed and heated to allow the prepolymer to deposit and condense on the particle surface to form a resin coating layer; then the system is adjusted to acidity to carry out curing and crosslinking reaction; after washing, drying and grinding, melamine-formaldehyde resin-coated intumescent flame retardant is obtained. 3) Castor oil polyol and polycaprolactone diol undergo transesterification under the protection of a catalyst and nitrogen, and byproducts are removed by depressurization to obtain castor oil-based flexible segment prepolymer. 4) Surface grafting modification treatment of aluminosilicate fibers was performed using an aminosilane coupling agent to obtain modified aluminosilicate fibers; 5) Mix polyether polyol, polymer polyol, castor oil-based flexible segment prepolymer obtained in step 3), hydroxyl-terminated polybutadiene, biocrystal powder obtained in step 1), melamine-formaldehyde resin-coated intumescent flame retardant obtained in step 2), nano-montmorillonite, modified aluminum silicate fiber obtained in step 4), foaming agent, foam stabilizer and catalyst evenly to obtain a mixture; 6) Mix the mixture with polyisocyanate, inject it into a mold for foaming and curing, demold and then perform post-curing to obtain the composite foam material.

2. The method for preparing a composite foam material filled with biocrystal powder according to claim 1, characterized in that, In step 1), the biocrystal powder comprises the following components in parts by weight: 81-81.3 parts silicon dioxide, 4.2-4.5 parts aluminum oxide, 3.1-3.5 parts calcium oxide, 0.8-1.2 parts iron oxide, and 2.2-2.6 parts magnesium oxide.

3. The method for preparing a composite foam material filled with biocrystal powder according to claim 1, characterized in that, In step 2), the mass ratio of the melamine-formaldehyde prepolymer solution, acidified expandable graphite, and ammonium polyphosphate is 27:(2-5):(4-8).

4. The method for preparing a composite foam material filled with biocrystal powder according to claim 1, characterized in that, In step 2), the curing and crosslinking reaction temperature is 50-65℃, and the curing and crosslinking reaction time is 0.8-1.5h.

5. The method for preparing a composite foam material filled with biocrystal powder according to claim 1, characterized in that, In step 3), the catalyst is tetrabutyl titanate; the mass ratio of castor oil polyol to polycaprolactone diol is (2.5-3.5):

1.

6. The method for preparing a composite foam material filled with biocrystal powder according to claim 1, characterized in that, In step 4), the aminosilane coupling agent is aminopropyltriethoxysilane; The amount of aminopropyltriethoxysilane used is 1.5% to 3.5% of the mass of aluminum silicate fiber.

7. The method for preparing a composite foam material filled with biocrystal powder according to claim 1, characterized in that, In step 5), the mass ratio of the hydroxyl-terminated polybutadiene to the modified aluminum silicate fiber is 1.2:(0.6-1.0).

8. The method for preparing a composite foam material filled with biocrystal powder according to claim 1, characterized in that, In step 5), the foaming agent is deionized water; the foam stabilizer is silicone oil; and the catalyst is composed of dibutyltin dilaurate and triethylenediamine.

9. A composite foam material filled with biocrystal powder, characterized in that, It is prepared by the method described in any one of claims 1-8.

10. The application of a composite foam material filled with biocrystal powder according to claim 9 in a sleep pillow.

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