Low odor low voc polyurethane rigid foam and method of making same

Abstract

The application discloses a low-odor and low-VOC polyurethane hard foam and a preparation method thereof. The raw material of the polyurethane hard foam comprises black material and white material. The polyether polyol in the white material is composed of vegetable oil-based polyether, low-unsaturation polyether and sucrose-initiated high-functionality polyether. The vegetable oil-based polyether accounts for 50wt%-70wt% in the white material, the low-unsaturation polyether accounts for 2wt%-5wt%, and the sucrose-initiated high-functionality polyether accounts for 5wt%-20wt%. The vegetable oil-based polyether in the application is natural and low in volatility, and can endow the foam with environmental protection performance and structural stability, and reduce VOC release. The low-unsaturation polyether can reduce side reactions, optimize microstructure, reduce odor and improve physical properties. The sucrose-initiated high-functionality polyether can easily form a three-dimensional network due to high functionality, increase crosslinking density, and improve mechanical strength and curing speed. The three components are synergistic, so that the polyurethane hard foam has low odor, low VOC, high strength and fast curing performance.

Description

Technical Field

[0001] This application relates to the field of rigid polyurethane foam technology, and in particular to a low-odor, low-VOC rigid polyurethane foam and its preparation method. Background Technology

[0002] With the increasing popularity of new energy vehicles, in-car refrigerators are becoming a more and more popular luxury feature among consumers. Polyurethane foam, as an important insulation material in in-car refrigerators, effectively reduces power consumption and condensation. However, the enclosed space inside a car imposes strict requirements on material odor and VOC emissions. Traditional rigid polyurethane foam uses polyether polyols, organic amine catalysts, and polymerized MDI to react, resulting in foam that easily retains small amounts of amines, free aldehydes, and low-molecular-weight alkanes, producing an unpleasant odor. Furthermore, solvents in flame retardants also release a distinctive odor. To address these issues, it is necessary to eliminate odor generation by focusing on raw material selection and the production process. In addition, the packaging process needs optimization to prevent the material from absorbing odors during storage and transportation. Summary of the Invention

[0003] To address the odor and VOC emissions issues associated with traditional rigid polyurethane foam in automotive refrigerator applications, this application provides a low-odor, low-VOC rigid polyurethane foam and its preparation method. This technical solution achieves significantly low odor and low VOC characteristics by optimizing the polyether polyol system and introducing a synergistic formulation of vegetable oil-based polyethers, low-unsaturation polyethers, and sucrose-based high-functionality polyethers. The specific preparation method is as follows:

[0004] On one hand, this application provides a low-odor, low-VOC rigid polyurethane foam, the raw materials of which include black material and white material. The black material includes isocyanate compounds, and the white material includes polyether polyol, polyester polyol, silicone oil, catalyst, foaming agent, deodorizer, flame retardant and water. The polyether polyol includes vegetable oil-based polyether, low-unsaturation polyether and sucrose-initiated high-functionality polyether. Based on the total mass of the white material, the content of vegetable oil-based polyether is 50wt% to 70wt%, the content of low-unsaturation polyether is 2wt% to 5wt%, and the content of sucrose-initiated high-functionality polyether is 5wt% to 20wt%.

[0005] In some specific embodiments, the mass ratio of the low-unsaturation polyether to the vegetable oil-based polyether is 0.07 to 0.1:1, and the difference in hydroxyl value between the two is 320 to 370 mg KOH / g, and the difference in viscosity is 5000 to 8000 mPa·s.

[0006] In some specific embodiments, the hydroxyl value difference between the sucrose-based high-functionality polyether and the vegetable oil-based polyether is controlled within ±100 mg KOH / g, and the viscosity difference between the two is controlled within ±1000 mPa·s.

[0007] In some specific embodiments, the primary hydroxyl content of the low-unsaturation polyether is not less than 80%.

[0008] In some specific embodiments, the vegetable oil-based polyether has a hydroxyl value of 350–390 mg KOH / g, a viscosity of 6500–9000 mPa·s at 25°C, a molecular weight of 500–700 g / mol, a functionality of 4.0–5.0, and a density of 1.0000–1.2000 g / cm³ at 20°C. 3 ;

[0009] The low-unsaturation polyether has a hydroxyl value of 26-30 mg KOH / g, a viscosity of 1060-1260 mPa·s at 25°C, a functionality of no more than 3, and an unsaturation value of no more than 0.08 mol / kg.

[0010] The sucrose-initiated high-functionality polyether has a hydroxyl value of 365–395 mg KOH / g and a viscosity of 6000–9000 mPa·s at 25°C.

[0011] In some specific embodiments, the hydroxyl value of the polyester polyol is 100-200 mg KOH / g, and the mass of the polyester polyol accounts for 5%-15% of the total mass of the white material.

[0012] In some specific embodiments, the catalyst is selected from one or more of organometallic bismuth catalysts, reactive amine catalysts, and non-volatile amine catalysts, and the total mass of the catalyst accounts for 1.5% to 9% of the total mass of the white material.

[0013] In some specific embodiments, the reactive amine catalyst is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, N,N,N'-trimethylaminoethylethanolamine, N,N-dimethylaminoethoxyethanol, and N,N-dimethylaminohexanol.

[0014] In some specific embodiments, the mass ratio of monoethanolamine, diethanolamine and N,N-dimethylaminoethanol is 1:(1.1-1.4):(0.6-0.9).

[0015] In some specific embodiments, the mass ratio of the white material to the black material is 1:1.15 to 1.3;

[0016] Based on the total mass of the white material, the content of the silicone oil is 0.5wt% to 4wt%, the content of the foaming agent is 1wt% to 20wt%, the content of the deodorizing agent is 0.1wt% to 0.8wt%, the content of the flame retardant is 3wt% to 15wt%, and the content of water is 0.1wt% to 3wt%.

[0017] In some specific embodiments, the foaming agent is selected from one or more of pentane, 1-chloro-3,3,3-trifluoropropene, pentafluoropropane, methyl formate, butane, propane, difluoroethane, tetrafluoropropene, hexafluorobutene, and hexafluoropropene;

[0018] The silicone oil is polydimethylsiloxane, the deodorizer is HGD-50, and the flame retardant is tris(2-chloropropyl) phosphate.

[0019] On the other hand, this application also provides a method for preparing low-odor, low-VOC rigid polyurethane foam, the method comprising: mixing and foaming a white component and a black component, wherein the preparation process of the white component includes:

[0020] 1) Raw material pretreatment: Vegetable oil-based polyether and silicone oil are filtered through molecular sieves to obtain pretreated vegetable oil-based polyether and pretreated silicone oil;

[0021] 2) Mixing reaction: The filtered pretreated vegetable oil-based polyether and pretreated silicone oil, as well as low unsaturated polyether, sucrose-initiated high-functionality polyether, polyester polyol, catalyst, foaming agent and flame retardant are pumped into a stirred tank, and then water and deodorizing agent are pumped into the stirred tank and mixed for 50-70 minutes.

[0022] 3) Aeration treatment: Pump the mixture into the aeration tank and introduce nitrogen into the mixture.

[0023] In some specific embodiments, the mixing reaction further includes stirring during the mixing process using an anchor paddle and a dispersing disc, wherein the anchor paddle provides overall flow at a rotational speed of 30–60 RPM, and the dispersing disc provides local shear at a rotational speed of 1100–1300 RPM.

[0024] In some specific embodiments, the mixing reaction further includes a premixing stage after the water and deodorizing agent are pumped in. The premixing stage involves mixing at a temperature of 30–40°C for 4–10 minutes, followed by continued mixing at room temperature.

[0025] The flow rate of nitrogen introduced into the aeration treatment is controlled at 10-30 L / min, and the aeration time is 40-60 min.

[0026] By adopting the above technical solution, the low-odor, low-VOC rigid polyurethane foam and its preparation method provided in this application have the following beneficial effects:

[0027] This application discloses a low-odor, low-VOC rigid polyurethane foam and its preparation method. The raw materials for this rigid polyurethane foam include a black component and a white component. The polyether polyol in the white component is composed of vegetable oil-based polyether, low-unsaturation polyether, and sucrose-initiated high-functionality polyether. In the white component, the vegetable oil-based polyether accounts for 50wt%–70wt%, the low-unsaturation polyether accounts for 2wt%–5wt%, and the sucrose-initiated high-functionality polyether accounts for 5wt%–20wt%. This application effectively achieves low odor and low VOC in the rigid polyurethane foam through the synergistic effect of the vegetable oil-based polyether, the low-unsaturation polyether, and the sucrose-initiated high-functionality polyether. Among them, vegetable oil-based polyethers, as the main component, contain more natural and renewable ingredients in their molecular structure. During the preparation of rigid polyurethane foam, these natural components reduce the possibility of generating volatile organic compounds (VOCs) during the reaction, thus effectively reducing the VOC content in the product. Low-unsaturation polyethers, with their lower unsaturation, reduce side reactions, improve foam stability, and further optimize the foam's physical properties and odor characteristics. Sucrose-based high-functionality polyethers, with their high functionality, can quickly form a three-dimensional network structure, significantly increasing crosslinking density, thereby enhancing the foam's mechanical strength and curing speed. This unique formulation design not only achieves environmental protection goals but also improves the overall performance of rigid polyurethane foam through the synergistic effect of its components. It achieves low odor and low VOCs while also possessing higher strength and faster curing ability, providing a new solution for the greening and high-performance development of rigid polyurethane foam. Detailed Implementation

[0028] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] For the terms defined below, unless a different definition is given elsewhere in the claims or this specification, these definitions shall apply. All numerical values, whether explicitly indicated or not, are defined herein as being modified by the term "about." The term "about" generally refers to a range of numerical values ​​that a person skilled in the art would consider equivalent to the stated values ​​to produce substantially the same properties, functions, results, etc. A range of numerical values ​​indicated by a low value and a high value is defined as including all numerical values ​​included within that range and all subranges included within that range.

[0030] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0031] This application provides a low-odor, low-VOC rigid polyurethane foam, the raw materials of which include black material and white material. The black material includes isocyanate compounds, and the white material includes polyether polyol, polyester polyol, silicone oil, catalyst, foaming agent, deodorizer, flame retardant and water. The polyether polyol includes vegetable oil-based polyether, low unsaturated polyether and sucrose-initiated high-functionality polyether. Based on the total mass of the white material, the content of vegetable oil-based polyether is 50wt% to 70wt%, the content of low unsaturated polyether is 2wt% to 5wt%, and the content of sucrose-initiated high-functionality polyether is 5wt% to 20wt%.

[0032] Among them, plant oil-based polyethers play an important role in the preparation of rigid polyurethane foam due to their unique molecular structure, with a preferred content range of 50% to 70%. Plant oil-based polyethers contain long-chain fatty acid structures, which endow them with many excellent properties. First, they have high functionality and molecular weight, enabling the formation of a denser cross-linked network during foaming. This dense network structure acts like a tight "protective net," effectively reducing the migration and escape of small molecules, thereby lowering the release of volatile organic compounds (VOCs) and reducing odor generation at the source. Simultaneously, the long-chain fatty acid structure also contributes to high hydrophobicity and high steric reactivity (studies have shown that even in aqueous polyurethane systems, plant oil-based polyethers can perform well and exhibit high reactivity without a catalyst). Furthermore, plant oil-based polyethers possess high thermal stability, typically with a decomposition temperature above 200℃, resulting in higher heat capacity. During the reaction, this high heat capacity further promotes the formation of a denser cross-linked network, continuously reducing the migration and escape of small molecules.

[0033] More importantly, this structure prevents catalyst aggregation or excessively high local concentrations in the reaction system. In traditional reaction systems, catalyst aggregation or excessively high local concentrations can easily lead to uneven distribution of reaction sites, resulting in localized and intense exothermic phenomena. The presence of vegetable oil-based polyethers effectively alleviates this problem, preventing thermal decomposition and high-temperature volatilization of the catalyst due to localized overheating, thus creating a localized thermal relief environment in the reaction system. This helps to lower and disperse the actual temperature of the catalyst microenvironment, further reducing catalyst thermal decomposition and significantly reducing the possibility of side reactions and the generation of odorous gases. In addition, the high functionality of the monomers in vegetable oil-based polyethers makes it easy to form a three-dimensional network structure with high crosslinking density during the reaction, resulting in a final product with high hardness and strength. Its long-chain characteristics and uniform distribution of hydroxyl functional groups facilitate good compatibility with modified functional groups of low-volatility catalysts (such as macromolecular organic groups), thereby better achieving catalyst dispersion. To further reduce the problem of catalyst aggregation or excessively high local concentration in the reaction system, and to avoid localized intense exothermic reactions, catalyst thermal decomposition and high-temperature volatilization caused by uneven distribution of reaction sites, and to further reduce the generation of side reactions and odor gases.

[0034] Furthermore, in terms of raw material selection, plant oil-based polyethers preferably use polyether polyols derived from castor oil, soybean oil, or palm oil. Natural components can effectively reduce the generation of volatile gases. For example, Guangzhou Haierma HM-635A is a branched soybean oil-based polyol, which has a denser cross-linked structure compared to castor oil with its flexible triglyceride structure. Its branching characteristics result in a more concentrated reactive site, exhibiting good catalytic effects with metal catalysts or non-volatile amine catalysts. While ensuring reaction efficiency, it can reduce the amount of catalyst used and avoid the odor problems caused by residual amines or decomposition of traditional organic amine catalysts.

[0035] Low-unsaturation polyethers are high-performance polyethers, preferably with a content range of 2% to 5%, characterized by uniform molecular weight distribution and a high proportion of terminal primary hydroxyl groups. When reacting with isocyanates (such as MDI), low-unsaturation polyethers can achieve a more complete reaction, effectively reducing unreacted monomer residues and the generation of off-odors. Furthermore, adding small amounts of low-unsaturation polyethers can significantly improve the controllability and timeliness of the reaction, allowing for more complete reactions in the reaction system, thereby reducing the high-temperature reaction time, lowering viscosity, and improving flowability and heat uniformity. For example, Shandong Lanxing Dongda's 10LD83E / 10LD83EK is a highly active, low-VOC polyether with a high primary hydroxyl content, which can be mixed with polymer-grafted polyethers to further optimize reaction performance.

[0036] Furthermore, the synergistic effect of vegetable oil-based polyethers and low-unsaturation polyethers can significantly improve the overall performance of polyurethane foam. Vegetable oil-based polyethers exhibit high reactivity when combined with non-amine catalysts, while the low-unsaturation polyethers themselves possess sufficient reactivity with unreacted monomer residues, enabling a uniform reaction under non-amine catalysts. This reduces catalyst thermal decomposition, lowers the probability of side reactions, and thus reduces the generation of odorous gases. The high reactivity of low-unsaturation polyethers increases the possibility of rapid nucleation and improves the flexibility of the cell structure, while the flexible segments of vegetable oil-based polyethers regulate the toughness of the cell walls, forming a fine and uniformly distributed closed-cell structure. This not only reduces the migration and escape of small molecules but also lowers the thermal conductivity (λ value) to 0.0190-0.021 W / (m·K), significantly improving thermal insulation performance. In addition, the flexible long-chain segments of plant oil-based polyethers alleviate the brittleness of rigid foams, and combined with the flexibility-enhancing effect of low-unsaturation polyethers, achieve an optimal balance between compressive strength ≥180kPa and elongation at break ≥8%.

[0037] Sucrose-initiated high-functionality polyether is a polyether polyol synthesized using sucrose as an initiator, with a preferred content range of 5% to 20%. In polyurethane foam systems, adding a relatively small proportion of this polyether allows for full utilization of its high functionality. Due to its high functionality, sucrose-initiated high-functionality polyether readily forms a three-dimensional network structure during the reaction, significantly increasing the crosslinking density. The formation of this three-dimensional network structure not only enhances the foam's strength but also accelerates its curing speed, improving the product's mechanical properties and molding efficiency. Furthermore, by controlling the addition of sucrose-initiated high-functionality polyether at a low proportion and optimizing other components, its potential adverse effects can be minimized. For example, it reduces the occurrence of side reactions and avoids thermal decomposition problems caused by excessively rapid reaction rates. This helps achieve the goals of low odor and low VOC, thereby improving the product's environmental performance and odor characteristics. However, once the addition amount exceeds the above-mentioned range, the low odor and low VOC indicators will significantly increase and become difficult to reduce effectively through other means. Furthermore, excessively high usage rates place higher demands on the amount of catalyst used, especially increasing reliance on traditional organic amine catalysts. The use of traditional organic amine catalysts may lead to residual amines and odor problems from decomposition, thus affecting the product's environmental performance and odor characteristics.

[0038] This application achieves a breakthrough in low-odor, low-VOC rigid polyurethane foam through the synergistic effect of vegetable oil-based polyethers, low-unsaturation polyethers, and sucrose-initiated high-functionality polyethers. The synergistic effect not only optimizes the physical properties of the foam but also significantly reduces odor and VOC emissions, providing an innovative solution for the greening and high-performance development of rigid polyurethane foam.

[0039] In some specific embodiments, the mass ratio of low-unsaturation polyether to vegetable oil-based polyether is 0.07 to 0.1:1, and the difference in hydroxyl value between the two is 320 to 370 mg KOH / g, and the difference in viscosity is 5000 to 8000 mPa·s.

[0040] Low-unsaturation polyethers are predominantly composed of highly reactive primary hydroxyl groups, exhibiting high polarity; while vegetable oil-based polyethers typically contain secondary hydroxyl groups or ester groups (-COOR), possessing relatively hydrophobic properties and lower polarity. Due to the significant difference in polarity, their compatibility is poor, potentially leading to reduced reaction uniformity. This can result in insufficient reduction of catalyst aggregation or excessively high local concentrations in the reaction system, hindering efforts to reduce catalyst thermal decomposition and side reactions, thereby increasing the risk of odor gas generation.

[0041] To address this issue, optimizing the hydroxyl value difference, ratio, and viscosity synergistic control of low-unsaturated polyether and vegetable oil-based polyether can effectively improve their compatibility, reduce catalyst thermal decomposition and side reactions, and decrease odor gas generation. Firstly, by controlling the hydroxyl value difference between the two within a suitable range of 320–370 mg KOH / g, the influence of polarity differences on the reaction can be reduced, minimizing catalyst aggregation or excessively high local concentrations. This, in turn, more effectively reduces catalyst thermal decomposition and side reactions, thus lowering odor gas generation. A further improvement involves optimizing the ratio of the two. Controlling the ratio of low-unsaturated polyether to vegetable oil-based polyether to 0.07–0.1:1, and increasing the proportion of the more polar low-unsaturated polyether, not only improves compatibility but also ensures high reactivity, promotes rapid nucleation, and results in a denser three-dimensional network structure and fine, uniformly distributed closed-pore structures. This process helps regulate the toughness of the cell walls, promotes the dispersion reaction of plant oil-based polyethers with different catalysts, reduces localized intense exothermic reactions, and further reduces the risk of catalyst thermal decomposition. Simultaneously, strictly controlling the total amount of low-unsaturated polyether added and using a relatively high proportion can improve nucleation, enhance gelation of the reaction system, shorten the overall reaction time, reduce the relative amount of catalyst, and shorten the duration of the high-temperature stage, thereby further reducing side reactions and the risk of catalyst thermal decomposition. Furthermore, the reaction system can be optimized through viscosity synergistic regulation. Selecting a low-unsaturated polyether with a viscosity 5000–8000 mPa·s lower than that of the plant oil-based polyether allows for the dilution of the high-viscosity system of the plant oil-based polyether. High-viscosity and high-functionality systems tend to form excessively dense network structures, leading to excessively high localized heat, thereby increasing the amount and rate of odorant volatilization. By selecting a relatively low-viscosity low-unsaturated polyether, the amount and rate of odor volatilization can be improved, achieving a low-odor target. Meanwhile, low-viscosity polyethers can improve mixing uniformity, reduce unreacted areas caused by poor flowability and heat accumulation caused by local over-reaction, thereby further reducing the thermal decomposition of the catalyst in the polyurethane reaction, reducing the generation of odorous substances, and improving reaction efficiency.

[0042] In some specific embodiments, the hydroxyl value difference between sucrose-based high-functionality polyether and plant-based polyether is controlled within ±100 mg KOH / g, and the viscosity difference between the two is controlled within ±1000 mPa·s. In the preparation of rigid polyurethane foam, the matching of certain parameters between sucrose-based high-functionality polyether and plant-based polyether has a significant impact on the reaction process and the quality of the final product. First, regarding the hydroxyl value, the difference between the hydroxyl values ​​of sucrose-based high-functionality polyether and plant-based polyether needs to be controlled within a certain range. Specifically, the difference is usually controlled within ±100 mg KOH / g, preferably within ±30 mg KOH / g. A suitable hydroxyl value difference allows the two polyethers to have similar reactivity in the reaction system. Second, regarding viscosity, the difference between the two also needs to be controlled. The viscosity difference between sucrose-based high-functionality polyether and plant-based polyether should be controlled within ±1000 mPa·s. When the viscosities are similar, the flowability will also be relatively similar. By strictly controlling the hydroxyl value and viscosity differences between sucrose-based high-functionality polyethers and plant-based polyethers, the heat distribution in the reaction system is made more uniform, resulting in a localized thermal mitigation effect. Thermal mitigation lowers the actual temperature of the catalyst microenvironment, reducing catalyst thermal decomposition and high-temperature volatilization. Reducing catalyst thermal decomposition not only helps reduce the generation of odor gases but also improves the stability and controllability of the reaction system. Furthermore, by making their reactivity and flowability similar, the reaction process can be optimized, improving product quality.

[0043] In some specific embodiments, the primary hydroxyl content of the low-unsaturation polyether is not less than 80%. Specifically, when the primary hydroxyl content of the low-unsaturation polyether reaches 80% or more, its reaction with isocyanates (such as MDI) is more complete. On the one hand, this reduces unreacted monomer residues and other odorous substances, increases the completeness of the reaction, and reduces the generation of odorous gases; on the other hand, its molecular chain ends are mainly composed of primary hydroxyl groups rather than secondary hydroxyl groups, resulting in higher reactivity and a more complete main reaction with isocyanates (-NCO), thereby reducing unreacted hydroxyl residues and lowering the probability of side reactions such as the easy oxidation of residual hydroxyl groups to aldehydes (such as formaldehyde and acetaldehyde) under high temperature or catalytic conditions, directly reducing free aldehydes in rigid foam. At the same time, due to the higher reactivity and improved main reaction efficiency, the bonding between isocyanates and polyols is more complete, which helps the system form a denser three-dimensional network structure and is beneficial to reducing the migration and escape of small molecules. Furthermore, the use of low-unsaturation polyethers, due to their increased reactivity, reduces the dependence of the polyurethane reaction system on conventional amine catalysts (such as exclusion-reactive amine catalysts). Even when using other types of catalysts, better reactivity can be ensured, avoiding the irritating odor caused by amine volatilization. In addition, it can improve reactivity, reduce shrinkage or expansion caused by the migration of residual small molecules, form a more uniform cell structure, and reduce side reactions to avoid bubble merging or collapse, thereby forming a fine and uniformly distributed closed-cell structure, improving dimensional stability and reducing thermal conductivity (λ value), which is beneficial for improving the heat insulation of vehicle refrigerators.

[0044] In some specific embodiments, the vegetable oil-based polyether has a hydroxyl value of 350–390 mg KOH / g, a viscosity of 6500–9000 mPa·s at 25°C, a molecular weight of 500–700 g / mol, a functionality of 4.0–5.0, and a density of 1.0000–1.2000 g / cm³ at 20°C. 3 ;

[0045] The low-unsaturation polyether has a hydroxyl value of 26-30 mg KOH / g, a viscosity of 1060-1260 mPa·s at 25℃, a functionality of no more than 3, an unsaturation value of no more than 0.08 mol / kg, and a primary hydroxyl content of more than 80%.

[0046] The hydroxyl value of the sucrose-initiated high-functionality polyether is 365–395 mg KOH / g, and the viscosity at 25°C is 6000–9000 mPa·s.

[0047] By controlling the range of parameters such as hydroxyl value, viscosity, molecular weight, functionality, and density of vegetable oil-based polyethers, the stability and operability of the product under different process conditions are ensured, while also meeting the requirements of the final product in terms of mechanical properties, chemical stability, and other aspects. Specifically, the hydroxyl value is controlled within the range of 350–390 mg KOH / g, which allows the polyether to form a moderately cross-linked network structure when reacting with reactants such as isocyanates. This avoids problems such as insufficient cross-linking due to too low a hydroxyl value or excessive cross-linking due to too high a hydroxyl value, resulting in poor product strength and stability, increased reaction difficulty and cost, and reduced material flexibility, thus achieving a better balance in overall product performance. The viscosity range at 25°C is controlled within the range of 6500–9000 mPa·s, giving it good flowability and operability. This prevents sedimentation and stratification during storage and transportation, ensuring stable product quality. In practical applications, it also allows the polyether to be uniformly dispersed in other materials, ensuring reaction consistency and product quality. Uniform performance improves ease of construction and production efficiency; the molecular weight range is controlled between 500 and 700 g / mol, ensuring compatibility with various organic solvents and other polymers. This helps control the molecular chain length and entanglement during polymer network formation, thus affecting the material's mechanical properties and elasticity; the functionality is controlled between 4.0 and 5.0, enabling the formation of a highly cross-linked three-dimensional network structure during polymerization. Higher functionality helps improve the material's hardness, wear resistance, and chemical corrosion resistance, enhancing product lifespan and reliability; the density at 20℃ is controlled between 1.0000 and 1.2000 g / cm³. 3 This allows it to be evenly distributed when mixed with other materials, avoiding stratification due to density differences. Furthermore, density reflects the molecular structure and composition of polyethers to a certain extent, indirectly affecting their physicochemical properties.

[0048] By controlling the range of parameters such as hydroxyl value, viscosity, functionality, and unsaturation value of low-unsaturation polyethers, the stability and operability of the product under different process conditions can be guaranteed, while also meeting the requirements of the final product in terms of mechanical properties, chemical stability, and other aspects. Specifically, a hydroxyl value of 26–30 mg KOH / g ensures good reactivity compatibility with reactants such as isocyanates, allowing the reaction to proceed at an appropriate rate and avoiding production and product quality problems caused by excessively high or low hydroxyl values. It also balances material properties, achieving a balance between strength, flexibility, and processing performance in the final product. A viscosity of 1060–1260 mPa·s at 25°C provides good flowability, preventing precipitation and stratification during storage, ensuring product quality stability, and allowing the polyether to be uniformly dispersed in other materials during processing, reducing energy consumption and equipment wear, and improving production efficiency. A functionality of no more than 3 allows for controllable crosslinking. The structure avoids problems such as material brittleness caused by excessive cross-linking, meeting the needs of applications with high flexibility requirements. At the same time, it optimizes the reaction process, reduces side reactions, and improves product quality stability. The unsaturation value is no more than 0.08 mol / kg, which can effectively reduce the oxidation risk caused by unsaturated bonds, improve the weather resistance and chemical stability of the material, extend its service life, and improve processing performance. It makes the rheological properties of polyether stable during processing, improves product consistency and yield, and can ensure the stability and operability of the product under different process conditions, while meeting the requirements of the final product in terms of mechanical properties, chemical stability and other aspects.

[0049] The sucrose-initiated high-functionality polyether has a hydroxyl value between 365 and 395 mg KOH / g, resulting in abundant hydroxyl functional groups in its molecules. This not only enhances its reactivity with reactants such as isocyanates, accelerates the curing process, and shortens the product manufacturing cycle, but also helps to construct a highly cross-linked three-dimensional network structure, thereby significantly improving the material's mechanical strength and durability. Simultaneously, the polyether's viscosity at 25°C is controlled between 6000 and 9000 mPa·s. This viscosity range ensures good cohesion, effectively preventing relative sliding and separation between molecular chains during storage, avoiding precipitation and stratification, and enhancing the material's stability. Furthermore, this viscosity range facilitates the mixing of the polyether with other components, ensuring precise control and uniformity of the mixing ratio, thus guaranteeing the consistency of the final product's performance. Furthermore, by precisely controlling the moisture content of the sucrose-initiated high-functionality polyether to be less than 0.10%, maintaining the pH value within the range of 9 to 12, and the color intensity below 8 GD, side reactions are further reduced, improving the stability and durability of the material. Simultaneously, it remains stable in alkaline environments, enhancing reaction efficiency and reducing equipment corrosion. The controlled color intensity also gives the polyether good transparency and appearance, making it easy to color and thus enhancing the product's aesthetics.

[0050] In some specific embodiments, the hydroxyl value of the polyester polyol is 100-200 mg KOH / g, and the mass of the polyester polyol accounts for 5%-15% of the total mass of the white material. Preferably, a refined low-odor polyester polyol (brand name Stepan 3152, its content in the white material is 10%) is used. This polyester polyol has a hydroxyl value in the range of 100-200 mg KOH / g and contains ester groups (-COOR) and hydroxyl groups (-OH) in its molecular structure, thus possessing high polarity. When it is used in combination with vegetable oil-based polyethers and low-unsaturation polyethers, because its hydroxyl value deviates little from the latter two and its own polarity is relatively high, increasing the proportion of this polyester polyol in the system can significantly enhance the compatibility between materials. The benefits of good compatibility are multifaceted: firstly, it enhances the overall reactivity of the reaction system, effectively reducing the probability of uneven reactions between materials and preventing localized thermal aggregation; secondly, it helps reduce the thermal decomposition of the catalyst during the polyurethane reaction, thereby significantly reducing the generation of odorous substances and improving reaction efficiency. Furthermore, the addition of polyester polyols helps form a high-crosslinking-density rigid foam structure. This unique structure reduces the material's thermal conductivity, thus improving its insulation performance. Moreover, this structure also restricts the migration pathways of volatile organic compounds (VOCs), optimizing the performance of polyurethane materials from multiple dimensions.

[0051] In some specific embodiments, the catalyst is selected from one or more of organometallic bismuth catalysts, reactive amine catalysts, and non-volatile amine catalysts, and the total mass of the catalyst accounts for 1.5% to 9% of the total mass of the white material.

[0052] In the preparation of rigid polyurethane foam, reducing the amount of organic amine catalysts is key to reducing product odor and improving environmental friendliness. Therefore, organometallic bismuth catalysts are preferred, such as... Its addition amount is controlled between 0.5% and 3%. This catalyst uses bismuth (Bi) 3With bismuth as its core, combined with organic ligands (such as carboxylic acids and thiol groups), it is not only non-toxic but also possesses high thermal stability, with a decomposition temperature exceeding 300℃. Bismuth catalysts exhibit a unique mechanism in reducing volatile organic compounds (VOCs). After the reaction, the bismuth catalyst forms an inert complex and embeds itself within the polyurethane network structure. Throughout the reaction, no metal ions or organic fragments are released, thus avoiding the problem of volatile residues. Furthermore, the bismuth catalyst preferentially catalyzes the main reaction between isocyanates (-NCO) and hydroxyl groups (-OH), effectively suppressing side reactions such as biuret formation, thereby reducing the generation of amine volatiles. Simultaneously, the bismuth catalyst can accelerate the gelation reaction rate, shorten the induction period, and reduce the residence time of the reaction system at high temperatures, further inhibiting the occurrence of side reactions.

[0053] Reactive amine catalysts are a class of functional molecules that possess both catalytic activity and chemical participation. Their core mechanism involves the reaction of active amino groups (primary amines (-NH) and secondary amines (-NH-)) in their molecular structure with isocyanates (-NCO) to form intermediate transition states, thereby accelerating the main reaction of polyurethane (the reaction of isocyanate with polyol / water). During this process, active hydrogens (such as -NH) in the catalyst molecule react with the isocyanate to generate urea groups or biuret structures, which are covalently embedded in the polymer network, becoming part of the polymer chain. This not only avoids the odor and residue problems caused by volatilization after the reaction of traditional amine catalysts but also significantly improves the performance and environmental friendliness of polyurethane products, achieving "zero volatilization" and "low residue." In practical applications, the content of aliphatic amine reactive catalysts is preferably controlled between 0.5% and 3%.

[0054] Among them, non-volatile amine catalysts, based on their non-volatile components, can significantly reduce odors during the production process, thereby improving the production environment and product quality. For example, The preferred content is usually controlled between 0.5% and 3%. The molecular structure contains a hydroxyl (-OH) reactive functional group, which can chemically bond with isocyanate (-NCO) to become part of the polymer. This not only enhances the catalyst's immobilization but also further reduces the release of volatile organic compounds (VOCs), minimizing potential environmental and health impacts. From a chemical perspective... It possesses a high molecular weight (>400 g / mol) and low volatility. Its large molecular structure makes it difficult for it to escape from the polymer network, enabling it to physically adsorb small volatile molecules (such as unreacted monomers and aldehydes), slowing down their release rate and thus reducing the release of residual amines. Furthermore, this catalyst can be used in conjunction with bismuth catalysts to optimize the gel-foaming balance, shorten reaction time, and reduce heat exposure, thereby further reducing VOC formation.

[0055] Plant-based polyethers exhibit different hydroxyl reactivity compared to traditional petroleum-based polyethers. The long-chain structure of plant-based polyethers may slow the reaction rate, while the activity of low-volatility catalysts (such as modified amines) can precisely match the reaction kinetics of these polyethers. This not only results in a more uniform reaction rate but also avoids localized overheating caused by excessively rapid reactions, thereby reducing the risk of catalyst decomposition and further lowering VOC emissions.

[0056] In some specific embodiments, the reactive amine catalyst is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, N,N,N'-trimethylaminoethylethanolamine, N,N-dimethylaminoethoxyethanol, and N,N-dimethylaminohexanol.

[0057] Specifically, the aforementioned reactive amine catalysts can be used alone or in combination of two or more. Monoethanolamine (MEA) molecules contain one primary amino group (-NH) and one hydroxyl group (-OH). In the polyurethane synthesis reaction, because the primary amino group has significantly higher reactivity than the hydroxyl group, MEA preferentially reacts with isocyanate (-NCO) to form a urea bond. This rapid reaction characteristic allows MEA to quickly consume isocyanate, effectively driving the main reaction process of polyurethane and ensuring high reaction efficiency. Diethanolamine (DEA) molecules contain one secondary amino group (-NH-) and two hydroxyl groups (-OH). In the polyurethane synthesis reaction, although the secondary amino group has lower reactivity than the primary amino group, it has higher reactivity than the hydroxyl group, thus preferentially reacting with isocyanate (-NCO) to form a urea bond. This allows DEA to quickly consume isocyanate, effectively driving the main reaction process of polyurethane. Triethanolamine (TEA) molecules contain three hydroxyl groups (-OH) and one secondary amino group (-NH-). In polyurethane synthesis, the secondary amino group of TEA exhibits certain reactivity, reacting with isocyanate (-NCO) to form urea bonds, thus participating in the construction of the polyurethane network. Simultaneously, its three hydroxyl groups can further react with isocyanate, forming additional crosslinking sites and enhancing the stability and mechanical properties of the polymer network. Due to the large number of hydroxyl groups in TEA, it not only effectively consumes isocyanate in the reaction but also promotes the formation of the polymer network through multi-point crosslinking, improving the overall reaction efficiency and product performance. Dimethylethanolamine (DMEA) contains one tertiary amino group (-N(CH)) and one hydroxyl group (-OH). In polyurethane synthesis, DMEA exhibits significant dual catalytic and reactive properties. First, although the tertiary amino group of DMEA lacks the NH bond for direct reaction with isocyanate (-NCO), its basicity allows it to effectively catalyze the reaction between isocyanate and hydroxyl groups. By promoting the crosslinking reaction of isocyanate with polyols or other hydroxyl compounds, DMEA can significantly improve reaction efficiency, reduce the residue of free isocyanate, and thus reduce the occurrence of side reactions. Furthermore, the hydroxyl groups in DMEA molecules can directly react with isocyanates to form stable chemical bonds, which are then embedded into the polyurethane network, achieving a "zero-volatility" catalytic effect. These unique chemical properties give DMEA significant advantages in polyurethane synthesis, not only improving reaction rates and product performance but also reducing the release of volatile organic compounds (VOCs) by decreasing the residue of free amines and isocyanates, thus enhancing the environmental friendliness of the production process. The N,N-dimethylaminoethanol (DMEA) molecule contains a tertiary amine (-N(CH)) and a hydroxyl group (-OH). Because the tertiary amine lacks an NH bond, DMEA itself cannot directly react with isocyanates (-NCO). However, the basic nature of its tertiary amine enables it to act as a highly efficient catalyst, significantly promoting the reaction between isocyanates and hydroxyl groups.Through catalysis, DMEA can accelerate the synthesis reaction of polyurethane, improve reaction efficiency, and reduce the residue of free isocyanate, thereby effectively reducing the occurrence of side reactions. Furthermore, the hydroxyl groups in the DMEA molecule can further react with isocyanate to form stable chemical bonds that embed into the polyurethane network, thus possessing both catalytic and reactive functions. This unique dual nature makes DMEA an ideal choice for polyurethane synthesis, combining high catalytic performance and low volatility. N,N-Dimethylaminoethoxyethanol (DMAEE) is a reactive, low-odor catalyst containing a tertiary amino group (-N(CH)) and a hydroxyl group (-OH). The hydroxyl group can react with isocyanate (-NCO), thereby embedding the DMAEE molecule into the polyurethane polymer network and forming stable chemical bonds. This not only makes DMAEE non-volatile but also significantly reduces the residual odor in polyurethane foam products. N,N-Dimethylaminohexanol has significant advantages in the preparation of rigid polyurethane foam. First, as a reactive catalyst, it can significantly increase the reaction rate of isocyanate (-NCO) with polyols, thereby accelerating the molding process of rigid polyurethane foam. This not only shortens the reaction time but also improves production efficiency. Secondly, the catalyst can be embedded in the polyurethane network during the reaction, reducing the volatilization of free amines and significantly lowering the release of volatile organic compounds (VOCs), thus meeting environmental protection requirements. Furthermore, N,N-dimethylaminohexanol can effectively adjust the pore size and density of rigid polyurethane foam, making the foam structure more uniform and delicate, thereby improving the mechanical strength and thermal insulation performance of the rigid foam. Simultaneously, this catalyst can be used in combination with other catalysts (such as organometallic bismuth catalysts) to further optimize the gel-foaming balance and improve the overall performance of the foam.

[0058] In some specific embodiments, the mass ratio of monoethanolamine, diethanolamine and N,N-dimethylaminoethanol is 1:(1.1-1.4):(0.6-0.9).

[0059] Specifically, in polyurethane synthesis, a combination of monoethanolamine (MEA), diethanolamine (DEA), and N,N-dimethylaminoethanol (DMEA) is preferred, with a ratio of MEA:DEA:DMEA = 1:(1.1-1.4):(0.6-0.9), for example, MEA:DEA:DMEA = 1:1.2:0.8. This compounding method allows for precise adjustment of the proportions of secondary, primary, hydroxyl, and tertiary amines, thereby achieving different reactivity and catalytic effects with isocyanates. The primary amine of MEA exhibits the highest reactivity, rapidly forming urea bonds with isocyanates and driving the main reaction; the secondary amine of DEA is less reactive, further consuming isocyanates; while the tertiary amine of DMEA, although unable to react directly with isocyanates, effectively catalyzes the reaction between isocyanates and hydroxyl groups, reducing the residue of free isocyanates and minimizing side reactions. The synergistic effect of these three factors makes the reaction process more controllable, facilitates heat dispersion, avoids local high-temperature accumulation, reduces precipitation or phase separation phenomena that may occur during the polyurethane reaction, and reduces the generation of volatile by-products, thereby achieving the synthesis of low-odor, low-VOC polyurethane and significantly improving the environmental friendliness and performance of the product.

[0060] In some specific implementations, the mass ratio of white material to black material is 1:1.15 to 1.3;

[0061] Based on the total mass of the white material, the content of silicone oil is 0.5wt% to 4wt%, the content of foaming agent is 1wt% to 20wt%, the content of deodorizer is 0.1wt% to 0.8wt%, the content of flame retardant is 3wt% to 15wt%, and the content of water is 0.1wt% to 3wt%.

[0062] In polyurethane synthesis, the ratio of white component to black component significantly impacts the completeness of the reaction and the low odor and low VOC characteristics of the product. Typically, the ratio of white component to black component is controlled between 1:1.15 and 1.3, with a preferred ratio of 1:1.2. Precise control of this ratio effectively reduces the residue of free isocyanate (NCO) and unreacted hydroxyl groups, thereby lowering the incidence of side reactions and the release of volatile organic compounds (VOCs). When the proportion of black component (polymeric MDI) is too high, the free NCO content in the system increases. Unreacted NCO groups not only easily generate byproducts in subsequent reactions but may also escape during heat treatment or storage, leading to odor problems and increased VOC emissions. Furthermore, excessive NCO may trigger unnecessary cross-linking reactions, making the system overly complex and difficult to control. Conversely, when the proportion of black component is too low, there are too many unreacted hydroxyl groups in the system. Excess hydroxyl groups participate in side reactions, generating more small-molecule volatiles, such as carbon dioxide from water decomposition or other low-molecular-weight alcohols. Small molecule volatiles not only increase the odor of the system but may also lead to unstable foam structure, affecting the performance of the final product. By precisely controlling the ratio of white to black components at 1:1.15–1.3 (preferably 1:1.2), the optimal balance of the reaction between isocyanate and hydroxyl groups can be ensured. This ratio allows NCO to react fully with hydroxyl groups, reducing the residue of free NCO and unreacted hydroxyl groups, thereby reducing the incidence of side reactions and the generation of small molecule volatiles. Simultaneously, this ratio effectively avoids gas escape problems caused by incomplete reaction, thus achieving low-odor, low-VOC polyurethane products, improving the product's environmental friendliness and overall performance.

[0063] In the formulation of rigid polyurethane foam, the content range of each component has a significant impact on the performance and quality of the foam. The preferred content of silicone oil is 0.5wt% to 4wt% (e.g., 3wt%), which stabilizes the foam system by adjusting the pore structure of the foam, preventing foam collapse or over-expansion, thereby improving the uniformity and stability of the foam; the preferred content of foaming agent is 1wt% to 20wt% (e.g., 10wt%), which, as a key component in foam formation, forms the foam structure by generating gases (such as carbon dioxide or physical foaming gases), and its content directly affects the density and pore size of the foam; the preferred content of deodorizer is 0.1wt% to 0.8wt% (e.g., 0.5wt%), which improves the odor characteristics of the product by reducing odors in polyurethane foam; the preferred content of flame retardant is 3wt% to 15wt% (e.g., 10wt%), which can improve the fire resistance of the foam; the preferred content of water is 0.1wt% to 3wt% (e.g., 2wt%), which reacts with isocyanate in the polyurethane reaction to generate carbon dioxide, participating in the formation of the foam as a physical foaming agent, while regulating the reaction rate and the density of the foam. By precisely controlling the content of these components, the performance of rigid polyurethane foam can be optimized, achieving an optimal balance in terms of density, pore structure, fire resistance, and odor control, thereby improving the overall quality and application performance of the product.

[0064] In some specific embodiments, the foaming agent is selected from one or more of pentane, 1-chloro-3,3,3-trifluoropropene, pentafluoropropane, methyl formate, butane, propane, difluoroethane, tetrafluoropropene, hexafluorobutene, and hexafluoropropene;

[0065] The silicone oil is polydimethylsiloxane, the deodorizer is HGD-50, and the flame retardant is tris(2-chloropropyl) phosphate.

[0066] The blowing agent can be selected from one or more combinations of the following compounds: pentane blowing agents (including n-pentane, isopentane, and cyclopentane), pentafluoropropane (HFC-245fa), and other low-boiling-point liquid blowing agents (such as 1-chloro-3,3,3-trifluoropropene, methyl formate, butane, difluoroethane, tetrafluoropropene, hexafluorobutene, and hexafluoropropene). Pentane blowing agents have low ozone depletion potential (ODP = 0) and global warming potential (GWP = low), and exhibit good thermal insulation properties in polyurethane foam. The mixed use of cyclopentane and isopentane can further optimize the foam performance. Pentafluoropropane (HFC-245fa), as a third-generation blowing agent, has zero ozone depletion potential (ODP = 0) and low global warming potential (GWP = 790).

[0067] Polydimethylsiloxane (PDMS) silicone oil, with its low volatility, non-toxicity, and odorless properties, is an ideal low-VOC additive. Its low surface tension and good lubricity further optimize the pore structure of the foam, reducing gas escape caused by pore size inhomogeneity, thereby significantly reducing VOC emissions in polyurethane foam production while maintaining high foam performance. Preferably, M-8808 and M-8825 from MSI are two low-VOC silicone oil products specifically designed for polyurethane foam. By optimizing the pore structure and foaming properties, they effectively reduce VOC release while improving foam uniformity and stability.

[0068] Among them, Hengguangda HGD-50 is the preferred polyurethane foam deodorizer. It is a latest environmentally friendly polyurethane foam deodorizer that utilizes highly efficient adsorbents, interfering agents, and microencapsulation technology to specifically target odor components such as ammonia, sulfur, and residual monomers in polyurethane systems. Through complexation reactions, HGD-50 can effectively reduce odor concentration, with a preferred addition amount of 0.1%–0.8% (e.g., 0.6%). During the polyurethane foam foaming reaction, HGD-50 can react with harmful gases such as formaldehyde, achieving a treatment rate of 80%–90%, significantly reducing the emission of toxic and harmful gases.

[0069] Among them, refined low-odor tris(2-chloropropyl) phosphate (TCPP) is a highly efficient flame retardant. TCPP produced by Zhejiang Wansheng Chemical Co., Ltd. is preferred, with an addition amount of 3% to 15%, for example, 5%. TCPP not only provides excellent flame retardant effects but also significantly reduces the viscosity of the system. This helps improve the mixing uniformity of raw materials and promotes the smooth progress of the reaction. Simultaneously, reducing viscosity effectively disperses the heat of reaction, reducing local heat accumulation and thus reducing the occurrence of thermal decomposition side reactions caused by high temperatures. This not only improves the safety of the reaction but also further optimizes the performance and quality of polyurethane products.

[0070] This application also provides a method for preparing low-odor, low-VOC rigid polyurethane foam. The preparation method includes: mixing and foaming a white component and a black component, wherein the preparation process of the white component includes:

[0071] 1) Raw material pretreatment: Vegetable oil-based polyether and silicone oil are filtered through molecular sieves to obtain pretreated vegetable oil-based polyether and pretreated silicone oil;

[0072] 2) Mixing reaction: The filtered pretreated vegetable oil-based polyether and pretreated silicone oil, as well as low unsaturated polyether, sucrose-initiated high-functionality polyether, polyester polyol, catalyst, foaming agent and flame retardant are pumped into the stirred tank, and then water and deodorizing agent are pumped into the stirred tank and mixed for 50-70 minutes.

[0073] 3) Aeration treatment: Pump the mixture into the aeration tank and introduce nitrogen into the mixture.

[0074] In the preparation of the white component, molecular sieve technology is used to pretreat low-molecular-weight compounds in raw materials such as polyether polyols, polyester polyols, silicone oils, foaming agents, and flame retardants. This pretreatment adsorbs low-molecular-weight organic impurities, such as aldehydes, from the composite material without affecting other components in the formulation. Preferably, the molecular sieves can be ZSM-11, MZ-40, or Silicalite-1. Silicalite-1, in particular, exhibits excellent thermal and chemical stability due to its aluminum-free, neutral, and highly hydrophobic properties. Its uniform microporous system and approximately 0.56 nm pore size enable selective adsorption of specific molecules. In the pretreatment of vegetable oil-based polyethers, Silicalite-1 molecular sieves can efficiently adsorb and remove unreacted monomers, such as free fatty acids and glycerides. This prevents unreacted monomers from remaining in the polyether system, which could affect the product's low odor and low VOC content. Under acidic or high-temperature conditions, free fatty acids and glycerides easily decompose to generate low-molecular-weight aldehydes, such as formaldehyde and acetaldehyde. Free fatty acids may further oxidize during storage to form carboxylic acids, releasing a sour odor, and react with hydroxyl or amine catalysts in the polyether to produce byproducts. Glyceryl ester residues may hydrolyze during neutralization, generating glycerol and short-chain fatty acids, leading to an increase in the system's acid value, accelerating polyether degradation, and releasing volatile substances. Silicalite-1's microporous structure and hydrophobic surface allow it to selectively adsorb these small-molecule impurities, while larger-molecule vegetable oil-based polyethers are too large to enter the pores, thus achieving effective selective separation. Similarly, in the pretreatment of silicone oil, Silicalite-1 molecular sieves reduce the content of incompletely condensed cyclic siloxanes through physical adsorption, improving the thermal stability of the silicone oil, and utilize its surface silanol groups (Si-OH) to adsorb and remove residual metal catalysts, reducing the risk of catalytic side reactions in subsequent use. Furthermore, molecular sieves are used to pretreat low-molecular-weight compounds in low-unsaturation polyethers and sucrose-based high-functionality polyethers, polyester polyols, foaming agents, and flame retardants to further reduce odor.

[0075] The results of comparing the foam odor intensity levels under different treatment systems are shown in Table 1 below:

[0076] Table 1

[0077]

[0078] Odor testing typically employs a grading system, with 6- or 10-level rating systems being the mainstream approach. For example, in a 6-level system (such as Volkswagen PV3900 and BYD BYDQ-A1901.404-2015), level 1 indicates no odor, and level 6 indicates intolerable odor; while in a 10-level system (such as GM GMW3205), level 10 indicates no odor, and level 1 indicates intolerable odor. This application uses a 10-level rating system. As shown in Table 1, the ordinary polyether blend formulation, serving as the control group, exhibits the highest foam odor intensity, reaching level 10 (intolerable). However, after using the low-odor polyether blend formulation, the odor intensity significantly decreases to level 5. Further molecular sieve treatment reveals that the systems treated with ZSM-11 and MZ-40 molecular sieves show the same odor intensity, both at level 4.5, while the system treated with Silicalite-1 molecular sieves exhibits the lowest foam odor intensity, at only level 3.5, indicating its effectiveness in reducing foam odor. By optimizing the formulation and using molecular sieve treatment, the odor intensity of polyurethane foam can be significantly reduced, improving the sensory quality and user experience of the product.

[0079] Furthermore, during aeration, the introduction of nitrogen gas effectively prevents active groups in the polyether stock solution, such as hydroxyl and ether bonds, from contacting oxygen by replacing oxygen in the reaction system. This prevents oxidative degradation or cross-linking side reactions, maintaining the stability of the polyether's molecular structure and properties, and reducing the occurrence of side reactions. In addition, nitrogen gas can eliminate volatile impurities and improve the purity of the polyether. During polyether synthesis, nitrogen gas can carry away low-molecular-weight byproducts, such as unreacted monomers, residual solvents, and volatile organic compounds (VOCs). This not only reduces the odor of the stock solution but also reduces the migration of volatile substances in subsequent applications, contributing to the formation of small and stable bubbles.

[0080] The results of comparing the foam odor intensity levels under different treatment conditions are shown in Table 2 below:

[0081] Table 2

[0082] System General polyether formulation (control) Aeration treatment Odor intensity 10 3

[0083] As shown in Table 2, the odor intensity level of the untreated ordinary polyether formulation is 10, while the odor intensity level of the foam after aeration treatment is significantly reduced to 3. This demonstrates that aeration treatment with nitrogen gas can significantly reduce the odor intensity of the foam.

[0084] Furthermore, after the white material is prepared, it is sealed in packaging drums. However, during the manufacturing process, the packaging drums may come into contact with substances such as hydraulic oil and paint containing organic solvents. To reduce the residue of volatile organic compounds (VOCs), this application proposes an environmentally friendly packaging drum cleaning technology. This technology involves placing the packaging drums into a cleaning tank equipped with ultrasonic equipment, using water as the cleaning agent. The ultrasonic power is controlled between 800 and 1000 watts, and the cleaning time is set to 30 to 50 minutes to ensure that contaminants inside the drum are thoroughly removed. After cleaning, the packaging drums can be dried by compressed air or left to air dry naturally at room temperature for at least 3 days. This not only effectively reduces VOC emissions but also improves cleaning efficiency and cleanliness, ensuring the quality of the final product and promoting environmental sustainability.

[0085] The results of comparing the foam odor intensity levels of the two different packaging containers are shown in Table 3 below:

[0086] Table 3

[0087]

[0088]

[0089] Table 3 shows that the foam odor intensity level of ordinary packaging containers is 3.5, while that of ultrasonically cleaned packaging containers is 2.0. This demonstrates that the foam odor intensity level of ultrasonically cleaned packaging containers is significantly lower than that of ordinary packaging containers, indicating that ultrasonic cleaning is more effective in reducing foam odor. Ultrasonic cleaning technology can more thoroughly remove residues and odors from inside the packaging containers, thereby reducing the intensity of foam odor.

[0090] In some specific embodiments, the mixing reaction further includes stirring using an anchor paddle and a dispersion disc during the mixing process. The anchor paddle provides overall flow at a rotation speed of 30–60 RPM, while the dispersion disc provides localized shear at a rotation speed of 1100–1300 RPM. Specifically, in the stirred tank, a high-shear mixing process is employed in combination with the anchor paddle and the high-shear dispersion disc to achieve uniform mixing of the polyether. The anchor paddle provides overall flow within the stirred tank, preferably at a rotation speed of 30–60 RPM, to ensure thorough mixing of the materials at the macroscopic level. Simultaneously, the high-shear dispersion disc operates at a rotation speed of 1100–1300 RPM, preferably 1200 RPM, to provide localized high shear forces, achieving uniform dispersion of the materials at the microscopic level and effectively reducing phase separation. This ensures uniform mixing of vegetable oil-based polyethers, low-unsaturation polyethers, and sucrose-initiated high-functionality polyethers, reducing localized heat accumulation during the foaming reaction, shortening the high-temperature treatment time, reducing side reactions, and resulting in a product with low odor and low VOC characteristics.

[0091] In some specific embodiments, the mixing reaction includes a premixing stage after the water and deodorizing agent are pumped in. The premixing stage involves mixing at a temperature of 30–40°C for 4–10 minutes, followed by continued mixing at room temperature.

[0092] The flow rate of nitrogen introduced during aeration is controlled at 10–30 L / min, and the aeration time is 40–60 min.

[0093] In the initial stage of the mixing reaction, the temperature is controlled between 30 and 40°C, maintaining a relatively high temperature for 4 to 10 minutes. This facilitates the volatilization of low-molecular-weight substances and reduces the viscosity of the system, thereby improving the uniformity of the mixture. This premixing condition is particularly effective for mixing vegetable oil-based polyethers with low-unsaturation polyethers, significantly improving mixing uniformity, reducing localized heat accumulation, shortening the required high-temperature treatment time, and thus lowering the probability of side reactions. Ultimately, this results in a product with low odor and low VOCs.

[0094] In the aeration process, nitrogen gas is introduced into the polyether concentrate at a flow rate of 10 to 30 L per minute, precisely controlled according to the total production batch output. The entire aeration process lasts 40 to 60 minutes. This removes free volatile organic compounds (VOCs) from the liquid, thereby reducing odor and VOC emissions during product use. Furthermore, nitrogen aeration promotes uniform mixing of the polyether concentrate, helping to reduce heat buildup during subsequent processing, thus improving product stability and foaming properties.

[0095] The following detailed description of examples of this application is exemplary and is only used to explain this application, and should not be construed as limiting this application. The raw materials used are as follows: the black component is commercially available polymeric MDI; the white component is a polyether polyol including Guangzhou Haierma's vegetable oil-based polyether (HM-635A), with a hydroxyl value of 350–390 mg KOH / g, a viscosity of 6500–9000 mPa·s at 25°C, and a molecular weight of 500–700 g / mol.

[0096] Shandong Lanxing Dongda's low-unsaturation polyether (10LD83E / 10LD83EK) has a hydroxyl value of 26-30 mg KOH / g, a viscosity of 1060-1260 mPa·s at 25℃, a functionality of no more than 3, and an unsaturation value of no more than 0.08 mol / kg.

[0097] And Hongqiang Chemical's HQOL-R8239 sucrose-starting high-functionality polyether, with a hydroxyl value of 365-395 mgKOH / g and a viscosity of 6000-9000 mPa·s at 25℃;

[0098] The polyester polyol used is Stepan 3152; the silicone oils used are M-8808 and M-8825 from Meiside; the deodorizer is Hengguangda HGD-50; the flame retardant is low-odor tris(2-chloropropyl) phosphate (TCPP) produced by Zhejiang Wansheng Chemical; and the organometallic bismuth catalyst is... The foaming agent pentane and deionized distilled water can be selected from commercially available products.

[0099] Example 1

[0100] A low-odor, low-VOC rigid polyurethane foam raw material composition includes a black component and a white component. The black component is polymeric MDI, accounting for 55 wt% of the total mass. The white component accounts for 45 wt% of the total mass and is composed of: vegetable oil-based polyether (50 wt%), low-unsaturation polyether (5 wt%), sucrose-initiated high-functionality polyether (10 wt%), polyester polyol (10 wt%), low-VOC polydimethylsiloxane (silicone oil, 0.5 wt%), a catalyst composed of monoethanolamine (1 wt%), diethanolamine (1 wt%), and N,N-dimethylaminoethanol (1 wt%) in a mass ratio of 1:1.2:0.8, pentane (blowing agent, 10 wt%), deodorizing agent HGD-50 (0.5 wt%), low-odor tris(2-chloropropyl) phosphate (flame retardant, 8 wt%), and water (3 wt%). Among them, the primary hydroxyl content of the low-unsaturation polyether is 80%, the mass ratio of the low-unsaturation polyether to the vegetable oil-based polyether is 0.1:1, the hydroxyl value is 28 mg KOH / g, and the viscosity at 25℃ is 1100 mPa·s; the hydroxyl value of the vegetable oil-based polyether is 360 mg KOH / g, and the viscosity at 25℃ is 7000 mPa·s; the hydroxyl value of the sucrose-initiated high-functionality polyether is 370 mg KOH / g, and the viscosity at 25℃ is 7500 mPa·s.

[0101] A method for preparing low-odor, low-VOC rigid polyurethane foam involves mixing and foaming white and black components. The preparation process of the white component is as follows: First, vegetable oil-based polyether, low-unsaturation polyether, sucrose-initiated high-functionality polyether, catalyst, silicone oil, foaming agent, and flame retardant are filtered through molecular sieves and then pumped into a stirred tank. Simultaneously, water and a deodorizing agent are pumped into the stirred tank. Premixing is carried out at 40°C for 10 minutes, followed by continued mixing at room temperature for 50 minutes. During mixing, a high-shear process is achieved using an anchor paddle (60 RPM) and a dispersion disc (1200 RPM). After mixing, the raw materials are pumped into an aeration tank, and nitrogen gas is introduced (flow rate 20 L / min, aeration time 50 minutes). By optimizing the formulation and preparation process, the efficient preparation of low-odor, low-VOC rigid polyurethane foam is achieved, significantly improving the product's environmental performance and sensory quality.

[0102] Example 2

[0103] The raw material composition is the same as that in Example 1, except that the mass ratio of low-unsaturation polyether to vegetable oil-based polyether is 0.07:1.2.

[0104] Example 3

[0105] Referring to the raw material composition of Example 1, the differences are as follows: the low unsaturated polyether (Nanjing Kailian: polyether 2000MD) has a hydroxyl value of 56 mg KOH / g, a viscosity of 300-400 mPa·s at 25°C, and an unsaturation value of ≤0.01 mol / kg; the vegetable oil-based polyether (Lupranol Balance 50) has a hydroxyl value of 50 mg KOH / g and a viscosity of 725 mPa·s at 25°C; and the sucrose-initiated high-functionality polyether (polyether polyol 4110) has a hydroxyl value of 430-470 mg KOH / g and a viscosity of 3000-5000 mPa·s at 25°C.

[0106] Example 4

[0107] The raw material composition is the same as that in Example 1, except that the primary hydroxyl content of the low-unsaturation polyether is less than 60%.

[0108] Example 5

[0109] The raw material composition is the same as that in Example 1, except that the mass of polyester polyol accounts for 3% of the total mass of the white material.

[0110] Example 6

[0111] The raw material composition is the same as that in Example 1, except that the polyester polyol accounts for 20% of the total mass of the white material.

[0112] Example 7

[0113] The raw material composition is the same as in Example 1, except that the catalyst is an organic amine catalyst.

[0114] Example 8

[0115] The raw material composition is the same as in Example 1, except that the mass ratio of monoethanolamine, diethanolamine and N,N-dimethylaminoethanol is 1:1.5:1.

[0116] Example 9

[0117] The raw material composition is the same as that in Example 1, except that the content of black material is 50 wt% and the content of white material is 50 wt% based on the total mass of the raw material composition.

[0118] Example 10

[0119] The preparation method of low-odor, low-VOC rigid polyurethane foam in Example 1 is different in that the mixing stage is not heated, but directly mixed at room temperature for 60 minutes.

[0120] Example 11

[0121] The preparation method of low-odor, low-VOC rigid polyurethane foam in Example 1 differs in that the mixing stage does not use an anchor paddle and a dispersion disc for mixing and stirring, but is carried out directly.

[0122] Example 12

[0123] The preparation method of low-odor, low-VOC rigid polyurethane foam in Example 1 is the same, except that the flow rate of nitrogen introduced during aeration is 40 L / min and the aeration time is 30 min.

[0124] Comparative Example 1

[0125] The raw material composition is similar to that in Example 1, except that it does not include vegetable oil-based polyethers, low-unsaturation polyethers, or sucrose-based high-functionality polyethers, but instead directly uses conventional polyether polyols.

[0126] Comparative Example 2

[0127] The preparation method of low-odor, low-VOC rigid polyurethane foam in Example 1 is different in that the raw materials are not filtered through molecular sieves.

[0128] Comparative Example 3

[0129] The preparation method of low-odor, low-VOC rigid polyurethane foam in Example 1 is different in that nitrogen gas is not introduced into the raw materials for aeration treatment.

[0130] Test case

[0131] The polyurethane rigid foams prepared in Examples 1-12 and Comparative Examples 1-3 were characterized for performance, with measurements of VOC content, odor level, foam density, thermal conductivity, thermal stability, and compressive strength. VOC content was determined by gas chromatography-mass spectrometry (GC-MS) to accurately assess the release of volatile organic compounds; odor intensity was assessed using a sensory evaluation method, graded by professional fragrance evaluators to ensure objective and reliable results; foam density was determined according to ISO 845 standard to reflect the basic physical properties of the material; thermal conductivity was determined using the heat flow meter method (ASTM C518) to evaluate the material's thermal insulation performance; dimensional stability was tested according to ISO 2796 standard to characterize the stability of the foam under 70°C conditions; and compressive strength was tested according to ISO 844 standard to characterize the material's load-bearing capacity and mechanical properties. The characterization results are detailed in Table 4.

[0132] Table 4

[0133]

[0134]

[0135] Comparative analysis of the performance data of Examples 1-12 and Comparative Examples 1-3 shows that the high-performance foam material of this application has significant advantages: while maintaining excellent mechanical properties (compressive strength 162-175kPa), it achieves ultra-low VOC release (≤0.009mg / m3, more than 85% lower than the comparative examples) and low odor characteristics (strength grade ≤3.5). Its foam density (35.0-36.4kg / m3) is 12-15% lower than that of traditional materials, its thermal conductivity (0.0178-0.0193W / (m·K)) is 17-20% lower, and its high-temperature dimensional stability (≤0.91%) is 2-6 times higher. Its comprehensive performance indicators are significantly better than those of conventional foam materials.

[0136] The preferred embodiments of this application have been described in detail above; however, this application is not limited thereto. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in this application and are all within the protection scope of this application.

Claims

1. A low-odor, low-VOC rigid polyurethane foam, comprising a black component and a white component, wherein the black component comprises isocyanate compounds, and the white component comprises polyether polyol, polyester polyol, silicone oil, catalyst, foaming agent, deodorizing agent, flame retardant, and water, characterized in that, The polyether polyol comprises vegetable oil-based polyether, low-unsaturation polyether, and sucrose-initiated high-functionality polyether. Based on the total mass of the white material, the content of the vegetable oil-based polyether is 50wt%~70wt%, the content of the low-unsaturation polyether is 2wt%~5wt%, and the content of the sucrose-initiated high-functionality polyether is 5wt%~20wt%. The foaming agent is selected from one or more of pentane, 1-chloro-3,3,3-trifluoropropene, pentafluoropropane, methyl formate, butane, propane, difluoroethane, tetrafluoropropene, hexafluorobutene, and hexafluoropropene. The preparation method includes: mixing and foaming white and black components, wherein the preparation process of the white component includes: 1) Raw material pretreatment: Vegetable oil-based polyether and silicone oil are filtered through a molecular sieve to obtain pretreated vegetable oil-based polyether and pretreated silicone oil; 2) Mixing reaction: The filtered pretreated vegetable oil-based polyether and pretreated silicone oil, as well as low unsaturated polyether, sucrose-initiated high-functionality polyether, polyester polyol, catalyst, foaming agent and flame retardant are pumped into a stirred tank, and then water and deodorizing agent are pumped into the stirred tank and mixed for 50~70 minutes. 3) Aeration treatment: Pump the mixture into the aeration tank and introduce nitrogen into the mixture.

2. The rigid polyurethane foam according to claim 1, characterized in that, The mass ratio of the low-unsaturation polyether to the vegetable oil-based polyether is 0.07~0.1:1, and the difference in hydroxyl value between the two is 320~370 mg KOH / g, and the difference in viscosity is 5000~8000 mPa·s.

3. The rigid polyurethane foam according to claim 1, characterized in that, The hydroxyl value difference between the sucrose-based high-functionality polyether and the vegetable oil-based polyether is controlled within ±100 mg KOH / g, and the viscosity difference between the two is controlled within ±1000 mPa·s.

4. The rigid polyurethane foam according to claim 1, characterized in that, The primary hydroxyl content of the low-unsaturation polyether is not less than 80%.

5. The rigid polyurethane foam according to claim 1, characterized in that, The plant oil-based polyether has a hydroxyl value of 350-390 mg KOH / g, a viscosity of 6500-9000 mPa·s at 25°C, a molecular weight of 500-700 g / mol, a functionality of 4.0-5.0, and a density of 1.0000-1.2000 g / cm³ at 20°C. 3 ; The low-unsaturation polyether has a hydroxyl value of 26~30 mg KOH / g, a viscosity of 1060~1260 mPa·s at 25℃, a functionality of no more than 3, and an unsaturation value of no more than 0.08 mol / kg. The sucrose-initiated high-functionality polyether has a hydroxyl value of 365~395 mg KOH / g and a viscosity of 6000~9000 mPa·s at 25°C.

6. The rigid polyurethane foam according to claim 1, characterized in that, The hydroxyl value of the polyester polyol is 100~200mg KOH / g, and the mass of the polyester polyol accounts for 5%~15% of the total mass of the white material.

7. The rigid polyurethane foam according to claim 1, characterized in that, The catalyst is selected from one or more of organometallic bismuth catalysts, reactive amine catalysts, and non-volatile amine catalysts, and the total mass of the catalyst accounts for 1.5% to 9% of the total mass of the white material.

8. The rigid polyurethane foam according to claim 7, characterized in that, The reactive amine catalyst is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, N,N,N'-trimethylaminoethylethanolamine, N,N-dimethylaminoethoxyethanol, and N,N-dimethylaminohexanol.

9. The rigid polyurethane foam according to claim 8, characterized in that, The mass ratio of monoethanolamine, diethanolamine and N,N-dimethylaminoethanol is 1:(1.1~1.4):(0.6~0.9).

10. The rigid polyurethane foam according to claim 1, characterized in that, The mass ratio of the white material to the black material is 1:1.15~1.3; Based on the total mass of the white material, the content of the silicone oil is 0.5wt%~4wt%, the content of the foaming agent is 1wt%~20wt%, the content of the deodorizing agent is 0.1wt%~0.8wt%, the content of the flame retardant is 3wt%~15wt%, and the content of water is 0.1wt%~3wt%.

11. The rigid polyurethane foam according to claim 1, characterized in that, The silicone oil is polydimethylsiloxane, the deodorizer is HGD-50, and the flame retardant is tris(2-chloropropyl) phosphate.

12. The rigid polyurethane foam according to claim 1, characterized in that, The mixing reaction further includes stirring using an anchor paddle and a dispersing disc during the mixing process, wherein the anchor paddle provides overall flow at a rotation speed of 30-60 RPM, and the dispersing disc provides local shear at a rotation speed of 1100-1300 RPM.

13. The rigid polyurethane foam according to claim 1, characterized in that, The mixing reaction, after pumping in water and deodorizing agent, also includes a premixing stage, in which the mixture is mixed at a temperature of 30-40°C for 4-10 minutes, and then mixed at room temperature. The flow rate of nitrogen introduced into the aeration treatment is controlled at 10~30L / min, and the aeration time is 40~60min.

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