Low-odor low-VOC (volatile organic compound) rigid polyurethane foam and preparation method thereof

Abstract

The embodiment of the invention discloses low-odor low-VOC (volatile organic compound) rigid polyurethane foam and a preparation method thereof. The rigid polyurethane foam comprises the following raw materials: a black material and a white material, wherein polyether polyol in the white material consists of vegetable oil-based polyether, low-unsaturation polyether and sucrose initial high-functionality polyether. The white material comprises 50-70 wt% of vegetable oil-based polyether, 2-5 wt% of low-unsaturation polyether and 5-20 wt% of sucrose initial high-functionality polyether. The vegetable oil-based polyether in the invention is natural and low in volatility, endows the foam with environmental protection performance and structural stability, and reduces VOC release; the polyether with low degree of unsaturation can reduce side reactions, optimize a microstructure, reduce odor and improve physical properties; the sucrose initial high-functionality polyether can easily form a three-dimensional network by virtue of the high functionality, so that the crosslinking density is increased, and the mechanical strength and the curing speed are improved. The three components cooperate to make the rigid polyurethane foam have the advantages of low odor, low VOC, high strength and rapid curing performance.

Description

Technical Field

[0001] This application relates to the technical field of rigid polyurethane foam, and particularly relates to a rigid polyurethane foam with low odor and low VOC and a preparation method thereof. Background Art

[0002] With the popularization of new energy vehicles, in-vehicle refrigerators, as a luxury configuration, are increasingly favored by consumers. Polyurethane foam, as an important thermal insulation material in in-vehicle refrigerators, can effectively reduce power consumption and the generation of refrigeration condensation. However, the space inside the car is airtight, and strict requirements are imposed on the odor and VOC emissions of materials. Traditional rigid polyurethane foam reacts with polyether polyols, organic amine catalysts, and polymeric MDI, and the resulting foam is likely to have a small amount of amines, free aldehydes, and low molecular weight alkanes remaining, generating an odor. In addition, the solvents in the flame retardant also release a special odor. To solve the above problems, it is necessary to start from aspects such as raw material selection and production process to eliminate odor generation. In addition, the packaging link also needs to be optimized to prevent the material from adsorbing odors during storage and transportation. Summary of the Invention

[0003] To solve the problems of odor and VOC emissions existing in the application of traditional rigid polyurethane foam in in-vehicle refrigerators, this application provides a rigid polyurethane foam with low odor and low VOC and a preparation method thereof. This technical solution realizes significant low odor and low VOC characteristics by optimizing the polyether polyol system and introducing a synergistic formulation of vegetable oil-based polyether, low unsaturation polyether, and sucrose-initiated high functionality polyether. The specific preparation method is as follows:

[0004] On the one hand, this application provides a rigid polyurethane foam with low odor and low VOC, the raw materials of which include black material and white material. The black material includes isocyanate compounds, and the white material includes polyether polyols, polyester polyols, silicone oil, catalysts, blowing agents, deodorants, flame retardants, and water. The polyether polyols include 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%.

[0005] In some specific embodiments, 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 - 370mg KOH / g, and the difference in viscosity is 5000 - 8000mPa·s.

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

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

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

[0009] The hydroxyl value of the low unsaturation polyether is 26 - 30 mg KOH / g, the viscosity at 25 °C is 1060 - 1260 mPa·s, the functionality is not greater than 3, and the unsaturation value is not greater than 0.08 mol / kg;

[0010] 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.

[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% - 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'-trimethylaminoethyl ethanolamine, N,N-dimethylaminoethoxyethanol, and N,N-dimethylaminohexanol.

[0014] In some specific embodiments, the mass ratio of monoethanolamine, diethanolamine to 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 - 1.3;

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

[0017] In some specific embodiments, the blowing 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 deodorant is HGD-50, and the flame retardant is tris(2-chloropropyl) phosphate.

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

[0020] 1) Raw material pretreatment: filtering the vegetable oil-based polyether and the silicone oil through a molecular sieve to obtain pretreated vegetable oil-based polyether and pretreated silicone oil;

[0021] 2) Mixing reaction: pumping the filtered pretreated vegetable oil-based polyether, pretreated silicone oil, low-unsaturation polyether, sucrose-initiated high-functionality polyether, polyester polyol, catalyst, blowing agent, and flame retardant into a stirring kettle, and then pumping water and deodorant into the stirring kettle, and mixing for 50-70 min;

[0022] 3) Aeration treatment: pumping the mixed liquid into an aeration tank and introducing nitrogen into the mixed liquid.

[0023] In some specific embodiments, the mixing reaction further includes: stirring with an anchor paddle and a dispersion disk during the mixing process, wherein the anchor paddle provides overall flow at a rotation speed of 30-60 RPM, and the dispersion disk provides local shear at a rotation speed of 1100-1300 RPM.

[0024] In some specific embodiments, after pumping water and deodorant in the mixing reaction, it further includes a premixing stage, and the premixing stage is mixing at a temperature of 30-40 °C for 4-10 min, and then continuing to mix at room temperature;

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

[0026] By adopting the above technical solutions, a low-odor and low-VOC rigid polyurethane foam and a preparation method thereof provided by the present application have the following beneficial effects:

[0027] The embodiment of the present application discloses a low-odor, low-VOC polyurethane rigid foam and a preparation method thereof. The raw materials of the polyurethane rigid foam include black material and white material, and the polyether polyol in the white material is composed of vegetable oil-based polyether, low-unsaturation polyether and sucrose-initiated high-functionality polyether. In the white material, the vegetable oil-based polyether accounts for 50wt% to 70wt%, the low-unsaturation polyether accounts for 2wt% to 5wt%, and the sucrose-initiated high-functionality polyether accounts for 5wt% to 20wt%. The present application effectively promotes the polyurethane rigid foam to achieve low odor and low VOC through the synergistic effect of vegetable oil-based polyether, low-unsaturation polyether and sucrose-initiated high-functionality polyether. Among them, plant oil-based polyether is the main component, and its molecular structure contains more natural and renewable components. In the preparation process of polyurethane rigid foam, natural components can reduce the possibility of generating volatile organic compounds during the reaction process, thereby effectively reducing the VOC content in the product; the lower unsaturation of low-unsaturation polyether can reduce the occurrence of side reactions, improve the stability of the foam, and further optimize the physical properties and odor performance of the foam; sucrose-initiated high-functionality polyether can quickly form a three-dimensional network structure with its high functionality, significantly increase the cross-linking density, and thus improve the mechanical strength and curing speed of the foam. This unique formula design not only achieves environmental protection goals, but also improves the overall performance of polyurethane rigid foam through the synergistic effect of various components, so that it has low odor and low VOC, as well as higher strength and faster curing ability, providing a new solution for the greening and high performance of polyurethane rigid foam. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] For the following defined terms, these definitions shall apply unless a different definition is given in the claims or elsewhere in this specification. All numerical values, whether or not explicitly indicated, are defined herein as modified by the term "about". The term "about" generally refers to a numerical range that a person of ordinary skill in the art considers to be equivalent to the stated values ​​to produce substantially the same properties, functions, results, etc. A numerical range indicated by a lower value and a higher value is defined to include all numerical values ​​included in the numerical range and all subranges included in the numerical range.

[0030] It should be noted that in the description and claims of this application, the terms "first", "second", etc. are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented in an order other than those described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0032] A kind of low-odor and low-VOC rigid polyurethane foam provided by an embodiment of this application, the raw materials of which include a black material and a white material. The black material includes isocyanate compounds, and the white material includes polyether polyols, polyester polyols, silicone oil, catalysts, blowing agents, deodorants, flame retardants and water. The polyether polyols include vegetable oil-based polyethers, low-unsaturation polyethers and sucrose-initiated high-functional polyethers. 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-functional polyether is 5wt% - 20wt%.

[0033] Among them, due to its unique molecular structure, the vegetable oil-based polyether plays an important role in the preparation process of rigid polyurethane foam, and the preferred content range is 50% - 70%. The vegetable oil-based polyether contains a long-chain fatty acid structure, and the long-chain fatty acid structure endows it with many excellent properties. First of all, it has a relatively high functionality and molecular weight. During the foaming process, it enables the formation of a denser crosslinked network. The dense network structure is like a tight "protective net", effectively reducing the migration and escape of small-molecule substances, thereby reducing the release amount of volatile organic compounds (VOCs) and reducing the generation of odor from the source. At the same time, the long-chain fatty acid structure also brings high hydrophobicity and high spatial reactivity (studies have shown that even in an aqueous polyurethane system, the vegetable oil-based polyether can play a good role and has relatively high reactivity without a catalyst). Moreover, the vegetable oil-based polyether has high thermal stability, and its decomposition temperature is usually higher than 200°C, which enables it to have a higher heat capacity. During the reaction process, the high heat capacity further promotes the formation of a denser crosslinked network, continuously reducing the migration and escape of small-molecule substances.

[0034] More importantly, this structure can prevent the catalyst from aggregating or having too high a local concentration in the reaction system. In a traditional reaction system, the aggregation or too high a local concentration of the catalyst easily leads to uneven distribution of reaction sites, which in turn triggers local intense heat release. The presence of vegetable oil-based polyether can effectively alleviate this problem, avoiding thermal decomposition and high-temperature volatilization of the catalyst caused by local overheating, and thus forming a local heat mitigation environment in the reaction system. This is conducive to reducing and dispersing the actual temperature of the catalyst microenvironment, further reducing the thermal decomposition of the catalyst, and thereby greatly reducing the possibility of side reactions and the generation of odor gases. In addition, the high-functional monomer characteristics of vegetable oil-based polyether make it easy to form a three-dimensional network structure with a high crosslinking density during the reaction, resulting in a final product with high hardness and strength. Its long-chain characteristics and the uniform distribution of hydroxyl functional groups are conducive to forming good compatibility with the modified functional groups (such as large organic groups) of the low-volatility catalyst, and thus better realizing the dispersion effect of the catalyst. Further reducing the problem of catalyst aggregation or too high a local concentration in the reaction system, avoiding local intense heat release, catalyst thermal decomposition, and high-temperature volatilization caused by uneven distribution of reaction sites, and further reducing the occurrence of side reactions and the generation of odor gases.

[0035] In addition, in terms of raw material selection, vegetable oil-based polyether preferably uses polyether polyols derived from castor oil, soybean oil or palm oil. The natural components can effectively reduce the generation of volatile gases. For example, Guangzhou Hairma HM-635A is a branched soybean oil-based polyol, which has a denser crosslinked structure compared to castor oil with a flexible triglyceride structure. Its branched characteristics make the reaction active sites more dense, and it has good catalytic effects with metal catalysts or non-volatile amine catalysts. While ensuring the reaction efficiency, it can reduce the amount of catalyst used and avoid the odor problem caused by the residue or decomposition of traditional organic amine catalysts.

[0036] Among them, low-unsaturation polyether is a high-performance polyether, and the preferred content range is between 2% and 5%. It has the characteristics of uniform molecular weight distribution and a high proportion of terminal primary hydroxyl groups. When reacting with isocyanate (such as MDI), low-unsaturation polyether can achieve more complete reactions, effectively reducing the residue of unreacted monomers and the generation of odor substances. In addition, a small amount of low-unsaturation polyether can significantly improve the controllability and timeliness of the reaction, making the materials in the reaction system react more fully, thereby reducing the high-temperature time of the reaction, lowering the viscosity, improving the fluidity and heat uniformity. For example, 10LD83E / 10LD83EK of Shandong Bluestar Dongda is a polyether with high activity, low VOC and high primary hydroxyl content, which can be used in combination with polymer grafted polyether to further optimize the reaction performance.

[0037] In addition, the synergistic combination of vegetable oil-based polyether and low-unsaturation polyether can significantly improve the comprehensive performance of polyurethane foam. When the vegetable oil-based polyether is combined with a non-amine catalyst, it exhibits high reactivity. The sufficient reactivity of the low-unsaturation polyether itself with the residual unreacted monomers enables the two to achieve uniform reaction under a non-amine catalyst, reducing the thermal decomposition of the catalyst and the probability of side reactions, thereby reducing the generation of odor gases. The high reactivity of the low-unsaturation polyether increases the possibility of rapid nucleation and improves the flexibility of the cell structure. The flexible chain segments of the vegetable oil-based polyether regulate the toughness of the cell walls, forming a fine and evenly 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 enhancing the heat insulation performance. In addition, the flexible long-chain segments of the vegetable oil-based polyether alleviate the brittleness of the rigid foam. Combined with the flexibility improvement effect of the low-unsaturation polyether, it achieves the optimal balance between a compressive strength ≥ 180 kPa and an elongation at break ≥ 8%.

[0038] Among them, sucrose-initiated high-functionality polyether is a polyether polyol synthesized with sucrose as the initiator, and its preferred content range is 5% - 20%. In the polyurethane foam system, adding this polyether in a relatively small proportion can make full use of its high functionality characteristics. Due to the high functionality, sucrose-initiated high-functionality polyether easily forms a three-dimensional network structure during the reaction process, thus significantly increasing the crosslinking density. The formation of the three-dimensional network structure can not only enhance the strength of the foam but also accelerate the curing speed of the foam, improving the mechanical properties and molding efficiency of the product. At the same time, by controlling the addition amount of sucrose-initiated high-functionality polyether at a low proportion and combining with the optimization adjustment of other components, the possible adverse effects can be minimized. For example, reducing the occurrence of side reactions and avoiding thermal decomposition problems caused by too fast reaction speed. This helps to achieve the goals of low odor and low VOC, thereby enhancing the environmental performance and odor performance of the product. However, once the addition amount exceeds the above proportion range, the low odor and low VOC indicators will increase significantly and it is difficult to effectively reduce them by other means. In addition, too high a usage ratio will also pose higher requirements for the amount of catalyst used, especially increasing the dependence on traditional organic amine catalysts. The use of traditional organic amine catalysts may lead to problems such as residual amines and odor generated by decomposition, thus affecting the environmental performance and odor performance of the product.

[0039] Through the synergistic effect of vegetable oil-based polyether, low-unsaturation polyether, and sucrose-initiated high-functionality polyether, this application has achieved a breakthrough in low-odor and low-VOC polyurethane rigid foam. 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 of polyurethane rigid foam.

[0040] 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.

[0041] Among them, the low unsaturation polyether is mainly composed of highly active primary hydroxyl groups and has a relatively high polarity; while the vegetable oil-based polyether usually contains secondary hydroxyl groups or ester groups (-COOR) and has relatively hydrophobic properties and a lower polarity. Due to the large difference in polarity between the two, the compatibility is poor, which may lead to a decrease in reaction uniformity, and it is impossible to sufficiently reduce the aggregation or excessive local concentration of the catalyst in the reaction system, thereby being disadvantageous for reducing the thermal decomposition of the catalyst and the occurrence of side reactions, and further increasing the risk of generating odor gases.

[0042] To solve this problem, by optimizing the hydroxyl value difference, ratio, and viscosity synergistic regulation between low-unsaturation polyether and vegetable oil-based polyether, the compatibility between the two can be effectively improved, the thermal decomposition of the catalyst and the occurrence of side reactions can be reduced, and the generation of odor gases can be decreased. First, by controlling the hydroxyl value difference between the two within a suitable range of 320 - 370 mg KOH / g, the influence of polarity difference on the reaction can be reduced, the phenomenon of catalyst aggregation or excessive local concentration can be minimized, and thus the thermal decomposition of the catalyst and the occurrence of side reactions can be more effectively reduced, and the generation of odor gases can be decreased. A further improvement measure is to optimize the ratio between the two. Control the ratio of low-unsaturation polyether to vegetable oil-based polyether at 0.07 - 0.1:1, increasing the proportion of the low-unsaturation polyether with higher polarity. This not only helps to improve the compatibility between the two but also ensures high reaction activity, promotes rapid nucleation, and forms a denser three-dimensional network structure and small and uniformly distributed closed-cell structures. It is beneficial to adjust the toughness of the cell wall, promote the dispersion reaction between the vegetable oil-based polyether and different catalysts, reduce local intense heat release, and thus further reduce the risk of thermal decomposition of the catalyst. At the same time, strictly control the total addition amount of the low-unsaturation polyether. By using a relatively higher proportion, the nucleation property can be improved, the gelation of the reaction system can be enhanced, the overall reaction time can be shortened, the relative amount of the catalyst can be reduced, the duration of the high-temperature stage can be decreased, and thus the occurrence of side reactions can be further reduced, and the risk of catalyst thermal decomposition can be lowered. In addition, the reaction system can also be optimized through viscosity synergistic regulation. Select a low-unsaturation polyether with a viscosity 5000 - 8000 mPa·s lower than that of the vegetable oil-based polyether to dilute the high-viscosity system of the vegetable oil-based polyether. Systems with high viscosity and high functionality are prone to form an overly dense network structure, resulting in excessive local heat, which increases the volatilization amount and speed of odoriferous substances. By choosing a relatively low-viscosity low-unsaturation polyether, the volatilization amount and speed of odor can be improved, achieving the goal of low odor. At the same time, the low-viscosity polyether can improve the mixing uniformity, reduce the unreacted areas caused by poor fluidity and the heat aggregation caused by local over-reaction, and thus further reduce the thermal decomposition of the catalyst in the polyurethane reaction, lower the generation of odoriferous substances, and enhance the reaction efficiency.

[0043] In some specific embodiments, the difference in hydroxyl value between the sucrose-initiated high functionality polyether and the vegetable oil-based polyether is controlled within ±100 mg KOH / g, and the difference in viscosity between the two is controlled within ±1000 mPa·s. Among them, in the preparation process of rigid polyurethane foam, the matching of certain parameters between the sucrose-initiated high functionality polyether and the vegetable-based polyether has an important impact on the reaction process and the quality of the final product. First, in terms of hydroxyl value, the difference in hydroxyl value between the sucrose-initiated high functionality polyether and the vegetable-based polyether needs to be controlled within a certain range. Specifically, the hydroxyl value difference between the two is usually controlled within ±100 mg KOH / g, and the preferred range is ±30 mg KOH / g. A suitable hydroxyl value difference can make the reaction activities of the two polyethers in the reaction system similar. Second, in terms of viscosity, the difference between the two also needs to be controlled. The viscosity difference between the sucrose-initiated high functionality polyether and the vegetable-based polyether should be controlled within ±1000 mPa·s. When the viscosities of the two are similar, the fluidities will also be relatively close. By strictly controlling the hydroxyl value difference and viscosity difference between the sucrose-initiated high functionality polyether and the vegetable-based polyether, the heat distribution in the reaction system becomes more uniform, forming a local heat relief effect. Heat relief can reduce the actual temperature of the catalyst microenvironment and reduce the thermal decomposition and high-temperature volatilization of the catalyst. Reducing the thermal decomposition of the catalyst not only helps to reduce the generation of odor gases, but also improves the stability and controllability of the reaction system. In addition, making their reactivity and fluidity similar can optimize the reaction process and improve the product quality.

[0044] In some specific embodiments, the primary hydroxyl group content of the low unsaturation polyether is not less than 80%. Specifically, when the primary hydroxyl group content of the low unsaturation polyether reaches more than 80%, the reaction with isocyanate (such as MDI) is more sufficient. On the one hand, it reduces the residual odor substances such as unreacted monomers, increases the reaction sufficiency and reduces the generation of odor gases; on the other hand, the ends of its molecular chains are mainly primary hydroxyl groups rather than secondary hydroxyl groups, with higher reaction activity, and the main reaction with isocyanate (-NCO) is more sufficient, thereby reducing the residual unreacted hydroxyl groups and reducing the probability of side reactions such as the oxidation of residual hydroxyl groups to aldehydes (such as formaldehyde, acetaldehyde) under high temperature or catalytic conditions, directly reducing the free aldehydes in the rigid foam. At the same time, due to the higher reaction activity, the main reaction efficiency is improved, and the bonding of isocyanate and polyol is more complete, which helps the system to form a denser three-dimensional network structure, facilitating the reduction of the migration and dissipation of small molecules. Moreover, due to the increased reactivity of the low unsaturation polyether, the dependence of the polyurethane reaction system on conventional amine catalysts (such as excluding reactive amine catalysts) can be reduced. Even when using other types of catalysts, good reactivity can be ensured, avoiding the pungent odor caused by amine volatilization. In addition, it can also improve the reaction activity, reduce the shrinkage or expansion caused by the migration of residual small molecules, form a more uniform cell structure, and the reduction of side reactions can avoid bubble coalescence or collapse, thereby forming fine and evenly distributed closed cell structures, improving the dimensional stability and reducing the thermal conductivity (λ value), which is beneficial to improving the heat insulation of the vehicle-mounted refrigerator.

[0045] In some specific embodiments, the hydroxyl value of the vegetable oil-based polyether is 350 - 390 mg KOH / g, the viscosity at 25°C is 6500 - 9000 mPa·s, the molecular weight is 500 - 700 g / mol, the functionality is 4.0 - 5.0, and the density at 20°C is 1.0000 - 1.2000 g / cm 3 ;

[0046] The hydroxyl value of the low unsaturation polyether is 26 - 30 mg KOH / g, the viscosity at 25°C is 1060 - 1260 mPa·s, the functionality is not greater than 3, the unsaturation value is not greater than 0.08 mol / kg, and the primary hydroxyl group content reaches more than 80%.

[0047] 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.

[0048] Among them, by controlling the parameter ranges of the hydroxyl value, viscosity, molecular weight, functionality, and density of the vegetable oil-based polyether, the vegetable oil-based polyether can not only ensure the stability and operability of the product under different process conditions, but also meet the usage requirements of the final product in terms of mechanical properties, chemical stability, etc. Specifically, the hydroxyl value range is controlled at 350-390 mg KOH / g, which can form a moderate cross-linked network structure when the polyether reacts with reactants such as isocyanates, avoiding problems such as poor product strength and stability, increased reaction difficulty and cost, and affected material flexibility caused by insufficient cross-linking due to too low hydroxyl value or excessive cross-linking due to too high hydroxyl value, and enabling the comprehensive performance of the product to reach a better balance; the viscosity range at 25°C is controlled at 6500-9000 mPa·s, making it have good fluidity and operability, preventing precipitation and stratification during storage and transportation, ensuring the stability of product quality, and enabling the polyether to be evenly dispersed in other materials in actual applications, ensuring reaction consistency and product performance uniformity, and improving the convenience of construction operation and production efficiency; the molecular weight range is controlled at 500-700 g / mol, enabling it to be soluble in a variety of organic solvents and other polymers, and helping to control the molecular chain length and entanglement degree when forming a polymer network, thereby affecting the mechanical properties and elasticity of the material, etc.; the functionality is controlled at 4.0-5.0, enabling it to form a highly cross-linked three-dimensional network structure in the polymerization reaction, and a higher functionality helps to improve properties such as material hardness, wear resistance, and chemical corrosion resistance, enhancing the service life and reliability of the product; the density at 20°C is controlled at 1.0000-1.2000 g / cm 3 , so that it can be evenly distributed when mixed with other materials, avoiding stratification due to density differences, and the density reflects the molecular structure and composition of the polyether to a certain extent, having an indirect impact on its physical and chemical properties.

[0049] Among them, by controlling the parameter ranges of the hydroxyl value, viscosity, functionality, and unsaturation value of the low unsaturation polyether, the stability and operability of the product under different process conditions can be ensured, and the usage requirements of the final product in terms of mechanical properties, chemical stability, etc. can be met. Specifically, its hydroxyl value is in the range of 26 - 30 mg KOH / g, which can not only ensure good reactivity compatibility when reacting with reactants such as isocyanates, making the reaction proceed at an appropriate speed, avoiding production operation and product quality problems caused by too high or too low hydroxyl value, but also balance the material properties, enabling the final product to achieve a balance in strength, flexibility, and processing performance; the viscosity at 25°C is 1060 - 1260 mPa·s, giving it good fluidity, preventing precipitation and stratification during storage, ensuring the quality stability of the product, and enabling the polyether to be evenly dispersed in other materials during processing operations, reducing energy consumption and equipment wear, and improving production efficiency; the functionality is not greater than 3, which can form a controllable crosslinked structure, avoiding problems such as material embrittlement caused by excessive crosslinking, meeting the requirements of application fields with high flexibility requirements, optimizing the reaction process, reducing side reactions, and improving the quality stability of the product; the unsaturation value is not greater than 0.08 mol / kg, which can effectively reduce the oxidation risk caused by unsaturated bonds, enhance the weather resistance and chemical stability of the material, extend the service life, and improve the processing performance, making the rheological properties of the polyether stable during the processing process, improving product consistency and yield rate, and ensuring the stability and operability of the product under different process conditions and meeting the usage requirements of the final product in terms of mechanical properties, chemical stability, etc.

[0050] Among them, the hydroxyl value of the sucrose - initiated high - functionality polyether is between 365 and 395 mg KOH / g, making its molecules contain abundant hydroxyl functional groups, which not only enhances the reactivity with reactants such as isocyanates, accelerates the curing process, shortens the product production cycle, but also helps to construct a highly crosslinked three - dimensional network structure, thus significantly enhancing the mechanical strength and durability of the material. At the same time, the viscosity of this polyether at 25°C is controlled within 6000 - 9000 mPa·s, and this viscosity range ensures good cohesion, effectively preventing the relative sliding and separation between molecular chains during storage, avoiding precipitation and stratification phenomena, and enhancing the stability of the material. In addition, this viscosity range also facilitates the mixing of the polyether with other components, ensuring the precise control and uniformity of the mixing ratio, and thus ensuring the consistency of the final product performance. Additionally, by precisely controlling the water content of the sucrose - initiated high - functionality polyether to be less than 0.10%, the pH value is maintained within the range of 9 - 12, and the chromaticity is lower than 8 GD, further reducing side reactions, improving the stability and durability of the material, remaining stable in an alkaline environment, enhancing the reaction efficiency and reducing equipment corrosion. The control of chromaticity also gives the polyether good transparency and appearance, being easy to color, thus enhancing the aesthetics of the product.

[0051] In some specific embodiments, the hydroxyl value of the polyester polyol is 100 to 200 mg KOH / g, and the mass of the polyester polyol accounts for 5% to 15% of the total mass of the white material. Preferably, a refined low-odor polyester polyol (grade: Stepan 3152, with a content of 10% in the white material) is used. The hydroxyl value of this polyester polyol is within the range of 100 - 200 mg KOH / g, and its molecular structure contains ester groups (-COOR) and hydroxyl groups (-OH), thus having relatively high polarity. When it is used in combination with vegetable oil-based polyether and low-unsaturation polyether, due to the small deviation of its hydroxyl value from the latter two and its relatively high polarity, by increasing the usage ratio of this polyester polyol in the system, the compatibility between materials can be significantly enhanced. And the benefits brought by good compatibility are multi-faceted: on the one hand, it is beneficial to improve the reaction activity of the entire reaction system, effectively reduce the occurrence probability of non-uniform reactions between materials, and avoid the phenomenon of thermal local aggregation; on the other hand, it helps to reduce the thermal decomposition degree of the catalyst during the polyurethane reaction, thereby effectively reducing the generation amount of odor substances and improving the reaction efficiency at the same time. In addition, the addition of polyester polyol helps to form a hard foam structure with a high crosslinking density. This special structure can reduce the thermal conductivity of the material, thereby improving the heat insulation performance of the material. Moreover, this structure can also limit the migration path of volatile organic compounds (VOCs), optimizing the performance of polyurethane materials from multiple dimensions.

[0052] 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.

[0053] Among them, in the preparation process of polyurethane rigid foam, reducing the dosage of organic amine catalysts is the key to reducing product odor and improving environmental friendliness. For this reason, it is preferred to use organometallic bismuth catalysts, such as the addition amount is controlled between 0.5% and 3%. This catalyst takes bismuth (Bi 3+) As the core, combined with organic ligands (such as carboxylic acids, mercapto groups, etc.), it is not only non-toxic but also has high thermal stability, with a decomposition temperature exceeding 300 °C. In reducing volatile organic compounds (VOCs), bismuth catalysts have a unique mechanism. After the reaction, the bismuth catalyst forms an inert complex and embeds into the polyurethane network structure. During the whole reaction process, no metal ions or organic fragments are released, thus avoiding the problem of volatile residues. In addition, the bismuth catalyst can preferentially catalyze the main reaction between isocyanate (-NCO) and hydroxyl (-OH), effectively inhibiting the occurrence of side reactions such as biuret formation, and then reducing the generation of amine volatiles. At the same time, the bismuth catalyst can also accelerate the gel reaction rate, shorten the induction period, reduce the residence time of the reaction system at the high-temperature stage, and further inhibit the occurrence of side reactions.

[0054] Among them, reactive amine catalysts are a class of functional molecules with both catalytic activity and chemical participation. Their core mechanism is that the active amino groups (primary amino group (-NH) and secondary amino group (-NH-)) in the molecular structure react with isocyanate (-NCO) to form an intermediate transition state, thus accelerating the main reaction of polyurethane (the reaction between isocyanate and polyol / water). During this process, the active hydrogen (such as -NH) in the catalyst molecule reacts with isocyanate to generate urea or biuret structures and is embedded in the polymer network through covalent bonds, becoming part of the polymer chain. It not only avoids the odor and residue problems caused by the volatilization of traditional amine catalysts after the reaction but also significantly improves the performance and environmental friendliness of polyurethane products, achieving "zero volatilization" and "low residue". In practical applications, preferably, the content range of fatty amine-based reactive catalysts is controlled between 0.5% and 3%.

[0055] Among them, non-volatile amine catalysts, based on their non-volatile components, can significantly reduce the odor 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%. contains a hydroxyl (-OH) reactive functional group in its molecular structure, which can chemically bond with isocyanate (-NCO) and become part of the polymer. This not only enhances the fixation of the catalyst but also further reduces the release of volatile organic compounds (VOCs), reducing the potential impact on the environment and health. From a chemical property perspective, has a relatively high molecular weight (>400 g / mol) and low volatility. Its large molecular structure is difficult to escape from the polymer network and can physically adsorb small molecule volatiles (such as unreacted monomers, aldehydes), delaying their release rate, thereby reducing the release of residual amines. In addition, this catalyst can also be used in combination with bismuth catalysts to optimize the gel-foaming balance, shorten the reaction time, reduce heat exposure, and thus further reduce the generation of VOCs.

[0056] For plant-based polyethers, the reactivity of their hydroxyl groups is different from that of traditional petroleum-based polyethers. The long-chain structure of plant-based polyethers may slow down the reaction rate, while the activity of low-volatility catalysts (such as modified amines) can precisely match the reaction kinetics of such polyethers. This not only makes the reaction rate more uniform but also avoids local overheating caused by too fast reaction, thus reducing the risk of catalyst decomposition and further reducing the generation of VOCs.

[0057] In some specific embodiments, the reactive amine catalyst is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, N,N,N'-trimethylaminoethyl ethanolamine, N,N-dimethylaminoethoxyethanol, and N,N-dimethylaminohexanol.

[0058] Specifically, the above reactive amine catalysts can be used alone or in combination of two or more. Among them, monoethanolamine (MEA) contains a primary amino group (-NH) and a hydroxyl group (-OH) in its molecule. In the polyurethane synthesis reaction, due to the significantly higher reactivity of the primary amino group than the hydroxyl group, MEA will react preferentially with isocyanate (-NCO) to form a urea bond. The fast reaction characteristic enables MEA to rapidly consume isocyanate, thus effectively promoting the main reaction process of polyurethane and ensuring the efficient progress of the reaction. Diethanolamine (DEA) contains a secondary amino group (-NH-) and two hydroxyl groups (-OH) in its molecule. In the polyurethane synthesis reaction, although the reactivity of the secondary amino group is lower than that of the primary amino group, it is higher than that of the hydroxyl group. Therefore, it can react preferentially with isocyanate (-NCO) to form a urea bond. This enables DEA to rapidly consume isocyanate, thus effectively promoting the main reaction process of polyurethane. Triethanolamine (TEA) contains three hydroxyl groups (-OH) and a secondary amino group (-NH-) in its molecule. In polyurethane synthesis, the secondary amino group of TEA has a certain reactivity and can react with isocyanate (-NCO) to form a urea bond, thus participating in the construction of the polyurethane network. At the same time, its three hydroxyl groups can further react with isocyanate to form additional cross-linking points, enhancing the stability and mechanical properties of the polymer network. Due to the relatively large number of hydroxyl groups in TEA, it can not only effectively consume isocyanate in the reaction, but also promote the formation of the polymer network through multi-point cross-linking, improving the overall reaction efficiency and product performance of the reaction system. Dimethylethanolamine (DMEA) contains a tertiary amino group (-N(CH)) and a hydroxyl group (-OH) in its molecule. In polyurethane synthesis, DMEA exhibits significant dual characteristics of catalysis and reaction. First of all, although the tertiary amino group of DMEA lacks the N-H bond for direct reaction with isocyanate (-NCO), its basic property enables it to effectively catalyze the reaction between isocyanate and hydroxyl group. By promoting the cross-linking reaction between isocyanate and polyol or other hydroxyl compounds, DMEA can significantly improve the reaction efficiency, reduce the residue of free isocyanate, and thus reduce the occurrence of side reactions. In addition, the hydroxyl group in the DMEA molecule can directly react with isocyanate to form a stable chemical bond, further embedding into the polyurethane network to achieve the "zero-volatility" catalytic effect. The unique chemical properties give DMEA significant advantages in polyurethane synthesis. It can not only improve the reaction rate and product performance, but also reduce the release of volatile organic compounds (VOCs) by reducing the residues of free amine and isocyanate, enhancing the environmental friendliness of the production process. N,N-Dimethylaminoethanol (DMEA) contains a tertiary amino group (-N(CH)) and a hydroxyl group (-OH). Due to the lack of the N-H bond in the tertiary amino group, DMEA itself cannot directly react with isocyanate (-NCO). However, the basic property of its tertiary amino group enables it to act as an efficient catalyst, significantly promoting the reaction between isocyanate and hydroxyl group.Through catalysis, DMEA can accelerate the synthesis reaction of polyurethane, improve the reaction efficiency, and at the same time reduce the residue of free isocyanate, thereby effectively reducing the occurrence of side reactions. In addition, the hydroxyl group in the DMEA molecule can further react with isocyanate to form stable chemical bonds and be embedded in the polyurethane network, possessing both catalytic and reaction functions. The unique dual characteristics make DMEA an ideal choice with both high catalytic performance and low volatility in polyurethane synthesis. N,N-Dimethylaminoethoxyethanol (DMAEE) is a reactive low-odor catalyst. Its molecule contains a tertiary amino group (-N(CH)) and a hydroxyl group (-OH), and the hydroxyl group can react with isocyanate (-NCO), thus embedding the DMAEE molecule into the polyurethane polymer network to form 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 of all, as a reactive catalyst, it can significantly increase the reaction rate between isocyanate (-NCO) and polyol, thereby accelerating the forming process of rigid polyurethane foam. This not only shortens the reaction time but also improves the production efficiency. Secondly, this catalyst can be embedded in the polyurethane network during the reaction, reducing the volatilization of free amine and significantly reducing the release of volatile organic compounds (VOCs), thus meeting the environmental protection requirements. In addition, N,N-Dimethylaminohexanol can also effectively regulate the pore size and density of rigid polyurethane foam, making the foam structure more uniform and delicate, and then enhancing the mechanical strength and thermal insulation performance of the rigid foam. At the same time, this catalyst can be used in combination with other catalysts (such as organometallic bismuth catalysts) to further optimize the gel-foaming balance and enhance the overall performance of the foam.

[0059] In some specific embodiments, the mass ratio of monoethanolamine, diethanolamine, and N,N-dimethylaminoethanol is 1:(1.1 - 1.4):(0.6 - 0.9).

[0060] Specifically, in polyurethane synthesis, a combination of monoethanolamine (MEA), diethanolamine (DEA), and N,N-dimethylaminoethanol (DMEA) is preferably used, and their ratio is MEA:DEA:DMEA = 1:(1.1 - 1.4):(0.6 - 0.9). For example, MEA:DEA:DMEA = 1:1.2:0.8. Through this compounding method, the ratios of secondary amino groups, primary amino groups, hydroxyl groups, and tertiary amino groups can be precisely adjusted, thereby achieving different reactivity and catalytic effects with isocyanates. The primary amino group of MEA has the highest reactivity and can rapidly react with isocyanates to form urea bonds, promoting the main reaction; the secondary amino group of DEA has the second highest reactivity and can further consume isocyanates; although the tertiary amino group of DMEA cannot directly react with isocyanates, it can effectively catalyze the reaction between isocyanates and hydroxyl groups, reduce the residue of free isocyanates, and reduce the occurrence of side reactions. The synergistic effect of the three makes the reaction process more controllable, conducive to heat dissipation, avoids local high-temperature aggregation, reduces the precipitation or phase separation phenomena that may occur during the polyurethane reaction, reduces the generation of volatile by-products, thereby achieving the synthesis of low-odor and low-VOC polyurethanes, and significantly improving the environmental friendliness and performance of the products.

[0061] In some specific embodiments, the mass ratio of the white material to the black material is 1:1.15 - 1.3;

[0062] Based on the total mass of the white material, the content of silicone oil is 0.5wt% - 4wt%, the content of the blowing agent is 1wt - 20wt%, the content of the deodorant is 0.1wt% - 0.8wt%, the content of the flame retardant is 3wt% - 15wt%, and the content of water is 0.1wt% - 3wt%.

[0063] Among them, in the synthesis of polyurethane, the ratio of the white material to the black material has an important impact on the completeness of the reaction and the low odor and low VOC characteristics of the product. Generally, the ratio of the white material to the black material is controlled between 1:1.15 - 1.3, and the preferred ratio is 1:1.2. Through precise control of the ratio, the residues of free isocyanate (NCO) and unreacted hydroxyl groups can be effectively reduced, thereby reducing the incidence of side reactions and the release of volatile organic compounds (VOC). Among them, when the proportion of the black material (polymeric MDI) is too high, the content of free NCO in the system increases. The unreacted NCO groups are not only likely to generate by-products in subsequent reactions, but also may escape during heat treatment or storage, resulting in odor problems and increased VOC emissions. In addition, excessive NCO may also trigger unnecessary cross-linking reactions, making the system too complex to control. On the contrary, when the proportion of the black material is too low, there are too many unreacted hydroxyl groups in the system. The excess hydroxyl groups will participate in side reactions, generating more small molecule volatiles, such as carbon dioxide decomposed by water or other low molecular weight alcohol compounds. The small molecule volatiles not only increase the odor of the system, but may also cause the foam structure to be unstable, affecting the performance of the final product. By precisely controlling the ratio of the white material to the black material at 1:1.15 - 1.3 (preferably 1:1.2), the reaction between isocyanate and hydroxyl can reach the optimal balance. This ratio can enable the full reaction of NCO and hydroxyl, reduce the residues of free NCO and unreacted hydroxyl groups, thereby reducing the incidence of side reactions and the generation of small molecule volatiles. At the same time, this ratio can also effectively avoid the problem of gas escape caused by incomplete reaction, and thus achieve a polyurethane product with low odor and low VOC, improving the environmental friendliness and overall performance of the product.

[0064] Among them, in the formulation of rigid polyurethane foam, the content ranges of each component have an important impact on the performance and quality of the foam. The preferred content of silicone oil is 0.5 wt% - 4 wt% (such as 3 wt%), which stabilizes the foam system by adjusting the pore structure of the foam, preventing foam collapse or excessive expansion, thereby improving the uniformity and stability of the foam; the preferred content of the foaming agent is 1 wt% - 20 wt% (such as 10 wt%), as a key component for foam formation, it forms a foam structure by generating gas (such as carbon dioxide or physical foaming gas), and its content directly affects the density and pore size of the foam; the preferred content of the deodorant is 0.1 wt% - 0.8 wt% (such as 0.5 wt%), which reduces the odor in the polyurethane foam and improves the odor characteristics of the product; the preferred content of the flame retardant is 3 wt% - 15 wt% (such as 10 wt%), which can improve the fire resistance of the foam; the preferred content of water is 0.1 wt% - 3 wt% (such as 2 wt%), which reacts with isocyanate in the polyurethane reaction to generate carbon dioxide and participates in the formation of the foam as a physical foaming agent, while adjusting 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 to achieve the best balance in terms of density, pore structure, fire resistance, odor control, etc., thereby enhancing the comprehensive quality and application performance of the product.

[0065] 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;

[0066] The silicone oil is polydimethylsiloxane, the deodorant is HGD-50, and the flame retardant is tris(2-chloropropyl) phosphate.

[0067] Among them, the foaming agent can be selected from one or more combinations of the following compounds: pentane-based foaming agents (including n-pentane, isopentane, and cyclopentane), pentafluoropropane (HFC-245fa), and other low-boiling liquid foaming agents (such as 1-chloro-3,3,3-trifluoropropene, methyl formate, butane, difluoroethane, tetrafluoropropene, hexafluorobutene, and hexafluoropropene, etc.). Pentane-based foaming agents have a low ozone depletion potential (ODP value is 0) and a low global warming potential (low GWP value), and exhibit good thermal insulation performance in polyurethane foam. The mixed use of cyclopentane and isopentane can further optimize the performance of the foam; pentafluoropropane (HFC-245fa), as a third-generation foaming agent, has a zero ozone depletion potential (ODP = 0) and a low global warming potential (GWP = 790).

[0068] Among them, polydimethylsiloxane (PDMS) silicone oil itself has the characteristics of low volatility, non-toxicity, and odorlessness, and is an ideal low-VOC additive. Its low surface tension and good lubricity can further optimize the pore structure of the foam and reduce gas escape caused by uneven pore size, thereby significantly reducing VOC emissions in polyurethane foam production while maintaining the high performance of the foam. Preferably, Meside's M-8808 and M-8825 are two low-VOC silicone oil products designed specifically for polyurethane foam. By optimizing the pore structure and foaming performance of the foam, they effectively reduce the release of VOCs while improving the uniformity and stability of the foam.

[0069] Among them, the preferred polyurethane foam deodorant is Hengguangda HGD-50, which is the latest environmentally friendly polyurethane foam deodorant. It uses high-efficiency adsorbents, interfering agents and microencapsulation technology, specifically targeting odor components such as ammonia, sulfur, and residual monomers in the polyurethane system. Through complexation reaction, HGD-50 can effectively reduce the odor concentration, and its preferred addition amount is 0.1% to 0.8% (for example, 0.6%). During the polyurethane foam foaming reaction, HGD-50 can react with harmful gases such as formaldehyde, and the treatment rate can reach 80% to 90%, significantly reducing the emission of toxic and harmful gases.

[0070] Among them, refined low-odor tris(2-chloropropyl) phosphate (TCPP) is a highly efficient flame retardant, preferably TCPP produced by Zhejiang Wansheng Chemical Co., Ltd., and the preferred addition amount is 3% to 15%, for example, 5%. TCPP can not only provide excellent flame retardant effect, but also significantly reduce the viscosity of the system. It helps to improve the mixing uniformity of raw materials and promote the smooth progress of the reaction. At the same time, reducing the viscosity can effectively disperse the reaction heat and reduce the local accumulation of heat, thereby reducing the occurrence of thermal decomposition side reactions caused by high temperature. It not only improves the safety of the reaction, but also further optimizes the performance and quality of polyurethane products.

[0071] The present application also provides a method for preparing a low-odor, low-VOC polyurethane rigid foam, the preparation method comprising: mixing and foaming a white material and a black material, wherein the preparation process of the white material comprises:

[0072] 1) Raw material pretreatment: filtering the vegetable oil-based polyether and silicone oil through a molecular sieve to obtain pretreated vegetable oil-based polyether and pretreated silicone oil;

[0073] 2) Mixing reaction: pumping the filtered pretreated vegetable oil-based polyether and pretreated silicone oil, as well as low unsaturation polyether, sucrose-initiated high-functionality polyether, polyester polyol, catalyst, foaming agent and flame retardant into a stirred tank, and then pumping water and deodorant into the stirred tank, and mixing for 50 to 70 minutes;

[0074] 3) Aeration treatment: Pump the mixed liquor into the aeration tank and introduce nitrogen into the mixed liquor.

[0075] Among them, during the preparation of the white material, the molecular sieve technology is used to pretreat low-molecular compounds in raw materials such as polyether polyol, polyester polyol, silicone oil, foaming agent, and flame retardant. By adsorbing low-molecular-weight organic impurities in the combined material, such as aldehyde organic compounds, without affecting other components in the formula. Preferably, the molecular sieve can be selected with grades ZSM-11, MZ-40, and Silicalite-1. Especially Silicalite-1 molecular sieve, due to its characteristics of not containing aluminum, having a neutral surface, and being highly hydrophobic, exhibits excellent thermal stability and chemical stability. Its uniform microporous system and pore diameter of about 0.56 nanometers endow it with the ability of selective adsorption of specific molecules. In the pretreatment of vegetable oil-based polyether, Silicalite-1 molecular sieve can efficiently adsorb and remove unreacted monomers, such as free fatty acids and glycerides. Preventing unreacted monomers from remaining in the polyether system and affecting the product to achieve low odor and low VOC. Under acidic or high-temperature conditions, free fatty acids and glycerides are prone to decompose to form low-molecular aldehydes, such as formaldehyde and acetaldehyde. Free fatty acids may also further oxidize during storage to form carboxylic acid substances, releasing an acid smell and reacting with hydroxyl groups or amine catalysts in the polyether to produce by-products. The residue of glycerides may hydrolyze during the neutralization stage to form glycerol and short-chain fatty acids, resulting in an increase in the acid value of the system, accelerating the degradation of the polyether and releasing volatile substances. The microporous structure and surface hydrophobicity of Silicalite-1 enable it to selectively adsorb these small-molecule impurities, while the relatively large molecular weight vegetable oil-based polyether cannot enter the pores due to its large size, thus achieving effective selective separation. Similarly, during the pretreatment of silicone oil, Silicalite-1 molecular sieve reduces the content of incompletely condensed cyclic siloxanes through physical adsorption, improves the thermal stability of silicone oil, and uses the silanol groups (Si-OH) on its surface to adsorb and remove the residue of metal catalysts, reducing the risk of catalytic side reactions during subsequent use. Further, use molecular sieve to pretreat low-molecular compounds in low-unsaturation polyether, sucrose-initiated high-functional polyether, polyester polyol, foaming agent, and flame retardant to further reduce the odor.

[0076] By comparing the foam odor intensity grades under different treatment systems, the results are shown in Table 1 below:

[0077] Table 1

[0078]

[0079] Generally, odor detection adopts a grading standard, and the mainstream uses a 6-level or 10-level evaluation system. For example, in the 6-level system (such as Volkswagen PV3900, BYD BYDQ-A1901.404-2015), level 1 indicates no abnormal odor, and level 6 indicates intolerable; while in the 10-level system (such as General Motors GMW3205), level 10 indicates no odor, and level 1 indicates intolerable. This application adopts a 10-level evaluation system. As can be seen from Table 1, for the ordinary combined polyether formula as the control group, the foam odor intensity is the highest, reaching level 10 (intolerable); while after using the low-odor combined polyether formula, the odor intensity is significantly reduced to level 5. When further treated with molecular sieves, the systems treated with ZSM-11 and MZ-40 molecular sieves show the same odor intensity, both being 4.5 levels, while the system treated with Silicalite-1 molecular sieve shows the lowest foam odor intensity, only 3.5 levels, indicating that it is the most effective in reducing foam odor. By optimizing the formula 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.

[0080] In addition, in the aeration treatment, by introducing nitrogen to displace the oxygen in the reaction system, the active groups in the polyether stock solution, such as hydroxyl groups and ether bonds, are effectively prevented from contacting with oxygen, thus preventing the occurrence of oxidation degradation or cross-linking side reactions, maintaining the stability of the molecular structure and properties of the polyether, and facilitating the reduction of side reactions. In addition, nitrogen can also eliminate volatile impurities and improve the purity of the polyether. During the polyether synthesis process, nitrogen can carry out low-molecular-weight by-products, such as unreacted monomers, residual solvents, and volatile organic compounds (VOCs), not only reducing the abnormal odor of the stock solution, but also reducing the migration of volatile substances in subsequent applications, and contributing to the generation of small and stable bubbles.

[0081] By comparing the foam odor intensity levels under different treatment conditions, the results are shown in Table 2 below:

[0082] Table 2

[0083] system Ordinary composite polyether formulation (control group) Aeration treatment Odor intensity 10 3

[0084] As can be seen from Table 2, the foam odor intensity level of the untreated ordinary combined polyether formula is 10, while the foam odor intensity level after aeration treatment is significantly reduced to 3. It can be seen that by introducing nitrogen and carrying out aeration treatment, the odor intensity of the foam can be significantly reduced.

[0085] In addition, after the white material is prepared, it is encapsulated using a packaging barrel. However, during the manufacturing process of the packaging barrel, it 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 barrel cleaning technology. This technology includes placing the packaging barrel into a cleaning pool equipped with ultrasonic equipment and using water as the cleaning agent. The power of the ultrasonic wave is controlled between 800 and 1000 watts, and the cleaning time is set to 30 to 50 minutes to ensure that the pollutants inside the barrel are completely removed. The cleaned packaging barrel can be dried with compressed air or left to dry naturally at room temperature for at least 3 days. This not only effectively reduces VOC emissions but also improves the cleaning efficiency and cleanliness, ensuring the quality of the final product and promoting environmental sustainability.

[0086] By comparing the foam odor intensity levels of two different packaging barrels, the results are shown in Table 3 below:

[0087] Table 3

[0088]

[0089]

[0090] As can be seen from Table 3, the foam odor intensity level of the ordinary packaging barrel is 3.5, and that of the ultrasonic-cleaned packaging barrel is 2.0. It can be seen that the foam odor intensity level of the ultrasonic-cleaned packaging barrel is significantly lower than that of the ordinary packaging barrel, indicating that the ultrasonic cleaning of the packaging barrel is more effective in reducing the foam odor. The ultrasonic cleaning technology can more thoroughly remove the residues and odors inside the packaging barrel, thereby reducing the intensity of the foam odor.

[0091] In some specific embodiments, the mixing reaction further includes: using an anchor impeller and a dispersion disc for stirring during the mixing process. Among them, the anchor impeller provides overall flow at a rotation speed of 30 - 60 RPM, and the dispersion disc provides local shear at a rotation speed of 1100 - 1300 RPM. Specifically, in the stirring kettle, in order to achieve uniform mixing of the polyether, a high-shear mixing process is adopted, combining the use of an anchor impeller and a high-shear dispersion disc. The anchor impeller provides the overall flow inside the stirring kettle, with a preferred rotation speed of 30 to 60 RPM to ensure sufficient mixing of the materials at the macroscopic level. At the same time, the high-shear dispersion disc operates at a rotation speed of 1100 to 1300 RPM, preferably 1200 RPM, to provide local high-shear force to achieve uniform dispersion of the materials at the microscopic level, effectively reducing the phase separation phenomenon. This enables the vegetable oil-based polyether, low-unsaturation polyether, and sucrose-initiated high-functional polyether to be mixed evenly, reduces the accumulation of local heat during the foaming reaction, shortens the high-temperature treatment time, reduces the occurrence of side reactions, and enables the product to have the characteristics of low odor and low VOC.

[0092] In some specific embodiments, after water and deodorant are pumped into the mixing reaction, a premixing stage is further included. The premixing stage is to mix at a temperature of 30 to 40 °C for 4 to 10 minutes, and then continue to mix at room temperature;

[0093] For the aeration treatment, the flow rate of nitrogen gas introduced is controlled at 10 to 30 L / min, and the aeration time is 40 to 60 minutes.

[0094] Among them, in the mixing reaction, at the beginning stage, the temperature is controlled between 30 and 40 °C, that is, a relatively high temperature is maintained, and the duration is controlled at 4 to 10 minutes, which helps the volatilization of low-molecular substances and reduces the viscosity of the system, thereby improving the mixing uniformity. Especially for the mixing of vegetable oil-based polyether and low-unsaturation polyether, this premixing condition can significantly improve its mixing uniformity, help reduce the accumulation of local heat, shorten the required high-temperature treatment time, and then reduce the probability of side reactions, and finally achieve the characteristics of low odor and low VOC of the product.

[0095] Among them, in the aeration treatment, nitrogen gas is introduced into the polyether stock solution at a flow rate of 10 to 30 L per minute, and this flow rate is precisely controlled according to the total output of the production batch. At the same time, the entire aeration process lasts for 40 to 60 minutes. It can remove the free volatile organic compound (VOCs) gas in the liquid, thereby reducing the odor and VOC emissions of the product during use. In addition, nitrogen aeration can also promote the mixing uniformity of the polyether stock solution, help reduce the heat accumulation phenomenon in the subsequent processing process, and then improve the stability and foaming performance of the product.

[0096] The following details the examples of the present application, which are exemplary and are only used to explain the present application and cannot be understood as a limitation to the present application. Among them, the raw materials used are as follows: for the black material, commercially available polymeric MDI is selected; for the white material, the polyether polyol includes the vegetable oil-based polyether (HM-635A) of Guangzhou Hairma, with a hydroxyl value of 350 to 390 mg KOH / g, a viscosity of 6500 to 9000 mPa·s at 25 °C, and a molecular weight of 500 to 700 g / mol;

[0097] The low-unsaturation polyether (10LD83E / 10LD83EK) of Shandong Bluestar Dongda, with a hydroxyl value of 26 to 30 mg KOH / g, a viscosity of 1060 to 1260 mPa·s at 25 °C, a functionality not greater than 3, and an unsaturation value not greater than 0.08 mol / kg;

[0098] And the sucrose-initiated high-functionality polyether of Hongqiang Chemical's brand HQOL-R8239, with a hydroxyl value of 365 to 395 mgKOH / g and a viscosity of 6000 to 9000 mPa·s at 25 °C;

[0099] The polyester polyol uses Stepan 3152; the silicone oil uses Meside's M-8808 and M-8825, the deodorant is Hengguangda HGD-50, the flame retardant is low-odor tris (2-chloropropyl) phosphate (TCPP) produced by Zhejiang Wansheng Chemical, and the metal organic bismuth catalyst is selected The foaming agent pentane and deionized distilled water can be selected from relevant commercial products.

[0100] Example 1

[0101] A low-odor, low-VOC polyurethane rigid foam raw material composition comprises a black material and a white material, wherein the black material is polymerized MDI, accounting for 55wt% of the total mass; the white material accounts for 45wt% of the total mass, and is composed of: vegetable oil-based polyether (50wt%), low-unsaturation polyether (5wt%), sucrose-initiated high-functionality polyether (10wt%), polyester polyol (10wt%), low-VOC polydimethylsiloxane (silicone oil, 0.5wt%), a catalyst consisting of monoethanolamine (1wt%), diethanolamine (1wt%) and N,N-dimethylaminoethanol (1wt%), the mass ratio of the three being 1:1.2:0.8, pentane (foaming agent, 10wt%), deodorant HGD-50 (0.5wt%), low-odor tris(2-chloropropyl) phosphate (flame retardant, 8wt%) and water (3wt%). Among them, the primary hydroxyl content of the low-unsaturation polyether is 80%, the mass ratio to the vegetable oil-based polyether is 0.1:1, the hydroxyl value is 28 mg KOH / g, and the viscosity at 25°C is 1100 mPa·s; the hydroxyl value of the vegetable oil-based polyether is 360 mg KOH / g, and the viscosity at 25°C is 7000 mPa·s; the hydroxyl value of the sucrose-initiated high-functionality polyether is 370 mg KOH / g, and the viscosity at 25°C is 7500 mPa·s.

[0102] A method for preparing low-odor and low-VOC polyurethane rigid foam, wherein white material and black material are mixed and foamed, wherein the preparation process of the white material is as follows: first, plant oil-based polyether, low unsaturation polyether, sucrose-initiated high-functionality polyether, catalyst, silicone oil, foaming agent and flame retardant are respectively filtered through molecular sieves and pumped into a stirring tank, and water and deodorant are pumped into the stirring tank at the same time; premixed at a temperature of 40°C for 10 minutes, and then continued to mix at room temperature for 50 minutes, and high shear was performed using an anchor paddle (speed 60RPM) and a dispersion disk (speed 1200RPM) during the mixing process. After the mixing is completed, the raw materials are pumped into an aeration tank and nitrogen (flow rate 20L / min, aeration time 50min) is introduced. By optimizing the formula and preparation process, the efficient preparation of low-odor and low-VOC polyurethane rigid foam is achieved, and the environmental performance and sensory quality of the product are significantly improved.

[0103] Example 2

[0104] Referring to the raw material composition of Example 1, the difference is that the mass ratio of the low-unsaturation polyether to the vegetable oil-based polyether is 0.07:1.2.

[0105] Example 3

[0106] Referring to the raw material composition of Example 1, the difference is that the hydroxyl value of the low-unsaturation polyether (Nanjing Kailian: Polyether 2000MD) is 56 mg KOH / g, the viscosity at 25 °C is 300-400 mPa·s, and the unsaturation value is ≤ 0.01 mol / kg; the hydroxyl value of the vegetable oil-based polyether (Lupranol Balance 50) is 50 mg KOH / g, and the viscosity at 25 °C is 725 mPa·s; the hydroxyl value of the sucrose-initiated high-functional polyether (polyether polyol 4110) is 430-470 mg KOH / g, and the viscosity at 25 °C is 3000-5000 mPa·s.

[0107] Example 4

[0108] Referring to the raw material composition of Example 1, the difference is that the primary hydroxyl group content of the low-unsaturation polyether is less than 60%.

[0109] Example 5

[0110] Referring to the raw material composition of Example 1, the difference is that the mass of the polyester polyol accounts for 3% of the total mass of the white material.

[0111] Example 6

[0112] Referring to the raw material composition of Example 1, the difference is that the mass of the polyester polyol accounts for 20% of the total mass of the white material.

[0113] Example 7

[0114] Referring to the raw material composition of Example 1, the difference is that the catalyst is an organic amine catalyst.

[0115] Example 8

[0116] Referring to the raw material composition of Example 1, the difference is that the mass ratio of monoethanolamine, diethanolamine to N,N-dimethylaminoethanol is 1:1.5:1.

[0117] Example 9

[0118] Referring to the raw material composition of Example 1, the difference is that based on the total mass of the raw material composition, the content of the black material is 50 wt%, and the content of the white material is 50 wt%.

[0119] Example 10

[0120] Referring to the preparation method of the low-odor and low-VOC rigid polyurethane foam of Reference Example 1, except that in the mixing stage, heating is not carried out, and mixing is directly carried out at room temperature for 60 min.

[0121] Example 11

[0122] Referring to the preparation method of the low-odor and low-VOC rigid polyurethane foam of Reference Example 1, except that in the mixing stage, an anchor impeller and a dispersion disc are not used for mixing and stirring, but direct mixing is carried out.

[0123] Example 12

[0124] Referring to the preparation method of the low-odor and low-VOC rigid polyurethane foam of Reference Example 1, except that the flow rate of nitrogen gas introduced in the aeration treatment is 40 L / min and the aeration time is 30 min.

[0125] Comparative Example 1

[0126] Referring to the raw material composition of Reference Example 1, except that the raw material composition does not include vegetable oil-based polyether, low-unsaturation polyether, and sucrose-initiated high-functionality polyether, but directly uses conventional polyether polyol as a substitute.

[0127] Comparative Example 2

[0128] Referring to the preparation method of the low-odor and low-VOC rigid polyurethane foam of Reference Example 1, except that the raw materials are not filtered through a molecular sieve.

[0129] Comparative Example 3

[0130] Referring to the preparation method of the low-odor and low-VOC rigid polyurethane foam of Reference Example 1, except that the raw materials are not aerated with nitrogen gas.

[0131] Test Example

[0132] Perform performance characterization on the rigid polyurethane foams prepared in Examples 1 to 12 and Comparative Examples 1 to 3, and measure the VOC content, odor grade, foam density, thermal conductivity, thermal stability, and compressive strength. Among them, the VOC content is determined by gas chromatography-mass spectrometry (GC-MS) to accurately evaluate the release amount of volatile organic compounds; the odor intensity grade is determined by sensory evaluation method, and professional perfume evaluators grade according to the odor intensity to ensure the objectivity and reliability of the results; the foam density is determined according to the ISO845 standard to reflect the basic physical properties of the material; the thermal conductivity is measured by the heat flow meter method (ASTM C518) to evaluate the heat insulation performance of the material; the dimensional stability is tested with reference to the ISO2796 standard to characterize the stability of the foam under the working condition of 70 °C; the compressive strength is tested with reference to the ISO844 standard to characterize the bearing capacity and mechanical properties of the material. The characterization results are shown in Table 4.

[0133] Table 4

[0134]

[0135]

[0136] By comparing and analyzing the performance data of Examples 1-12 and Comparative Examples 1-3, it can be seen that the high-performance foam material of the present application has significant advantages: while maintaining excellent mechanical properties (compressive strength of 162-175 kPa), it achieves ultra-low VOC emissions (≤0.009 mg / m3, a reduction of more than 85% compared to the comparative examples) and low odor characteristics (strength grade ≤ 3.5). Its foam density (35.0-36.4 kg / m3) is reduced by 12-15% compared to traditional materials, the thermal conductivity (0.0178-0.0193 W / (m·K)) is reduced by 17-20%, and the high-temperature dimensional stability (≤0.91%) is increased by 2-6 times. The comprehensive performance indicators are significantly better than those of conventional foam materials.

[0137] The preferred embodiments of the present application have been described in detail above. However, the present application is not limited thereto. Within the scope of the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A polyurethane rigid foam with low odor and low VOC, the raw materials of which include a black component and a white component. The black component includes isocyanate compounds, and the white component includes polyether polyols, polyester polyols, silicone oil, catalysts, blowing agents, deodorants, flame retardants and water. It is characterized in that, 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 the vegetable oil-based polyether is 50 wt% to 70 wt%, the content of the low-unsaturation polyether is 2 wt% to 5 wt%, and the content of the sucrose-initiated high-functionality polyether is 5 wt% to 20 wt%.

2. The rigid polyurethane foam according to claim 1, wherein 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.

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

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

5. The rigid polyurethane foam according to claim 1, characterized in that, The hydroxyl value of the vegetable oil-based polyether is 350 to 390 mg KOH / g, the viscosity at 25 °C is 6500 to 9000 mPa·s, the molecular weight is 500 to 700 g / mol, the functionality is 4.0 to 5.0, and the density at 20 °C is 1.0000 to 1.2000 g / cm 3 ; The hydroxyl value of the low-unsaturation polyether is 26 to 30 mg KOH / g, the viscosity at 25°C is 1060 to 1260 mPa·s, the functionality is not greater than 3, and the unsaturation value is not greater than 0.08 mol / kg; The hydroxyl value of the sucrose-initiated high-functionality polyether is 365 to 395 mg KOH / g, and the viscosity at 25°C is 6000 to 9000 mPa·s.

6. The rigid polyurethane foam according to claim 1, characterized in that The hydroxyl value of the polyester polyol is 100 to 200 mg KOH / g, and the mass of the polyester polyol accounts for 5% to 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, wherein The reactive amine catalyst is selected from one or more of monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, N,N,N'-trimethylaminoethyl ethanolamine, 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 to 1.4):(0.6 to 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 to 1.3; Based on the total mass of the white material, the content of the silicone oil is 0.5 wt% to 4 wt%, the content of the foaming agent is 1 wt to 20 wt%, the content of the deodorant is 0.1 wt% to 0.8 wt%, the content of the flame retardant is 3 wt% to 15 wt%, and the content of water is 0.1 wt% to 3 wt%.

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

12. A preparation method of a polyurethane rigid foam with low odor and low VOC, characterized in that, The rigid polyurethane foam is the rigid polyurethane foam according to any one of claims 1 to 11, and the preparation method includes: mixing and foaming the white material and the black material, wherein the preparation process of the white material includes: 1) Raw material pretreatment: Filter the vegetable oil-based polyether and silicone oil through molecular sieves to obtain pretreated vegetable oil-based polyether and pretreated silicone oil; 2) Mixing reaction: Pump the filtered pretreated vegetable oil-based polyether, pretreated silicone oil, low unsaturation polyether, sucrose-initiated high functionality polyether, polyester polyol, catalyst, foaming agent and flame retardant into a stirring kettle, and then pump water and deodorant into the stirring kettle and mix for 50 - 70 min; 3) Aeration treatment: Pump the mixed liquid into an aeration tank and introduce nitrogen gas into the mixed liquid.

13. The preparation method according to claim 12, characterized in that, The mixing reaction further includes: Stirring is carried out using an anchor paddle and a dispersion disk during the mixing process. Among them, the anchor paddle provides overall flow at a rotation speed of 30 - 60 RPM, and the dispersion disk provides local shear at a rotation speed of 1100 - 1300 RPM.

14. The preparation method according to claim 12, wherein, After pumping water and deodorant in the mixing reaction, it further includes a premixing stage, and the premixing stage is to mix at a temperature of 30 - 40 °C for 4 - 10 min and then continue to mix at room temperature; In the aeration treatment, the flow rate of the introduced nitrogen gas is controlled at 10 - 30 L / min, and the aeration time is 40 - 60 min.

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