Polyurethane foam composition, polyurethane foam and method of making, refrigeration appliance

Abstract

The application discloses a polyurethane foam composition, a polyurethane foam and a preparation method and a refrigeration equipment, relates to the technical field of polyurethane, and the polyurethane foam composition comprises a polyurethane prepolymer mixture, the polyurethane prepolymer mixture comprises the polyurethane prepolymer, and the polyurethane prepolymer is mainly obtained by performing an aminolysis reaction on a cyclic carbonate composition and an amine curing agent; wherein the cyclic carbonate composition comprises carbonated soybean oil and butanediol biscyclocarbonate. The application utilizes the synergy of the carbonated soybean oil and the butanediol biscyclocarbonate, so that the polyurethane foam composition has both rigidity and foaming activity.

Description

Technical Field

[0001] This application relates to the field of polyurethane technology, and in particular to polyurethane foam compositions, polyurethane foams and their preparation methods, and refrigeration equipment. Background Technology

[0002] Non-isocyanate rigid polyurethane foam is usually prepared by using a single small molecule cyclic carbonate system, combined with external chemical foaming agents such as sodium bicarbonate and azodicarbonamide. However, this cyclic carbonate system cannot achieve both rigidity and foaming activity. Summary of the Invention

[0003] In view of this, this application provides a polyurethane foam composition, a polyurethane foam and a preparation method thereof, and a refrigeration device.

[0004] The embodiments of this application are implemented as follows: a polyurethane foam composition comprising a polyurethane prepolymer mixture, wherein the polyurethane prepolymer mixture includes the polyurethane prepolymer, and the polyurethane prepolymer is mainly obtained by an aminolysis reaction of a cyclic carbonate composition and an amine curing agent; wherein the cyclic carbonate composition includes carbonated soybean oil and butanediol bicyclic carbonate.

[0005] Optionally, in some embodiments of this application, the carbonated soybean oil is a multifunctional bio-based cyclic carbonate obtained by cycloaddition reaction of epoxidized soybean oil and carbon dioxide, and the average functionality of the carbonated soybean oil is 3.5 to 4.0. The butanediol bicyclic carbonate is derived from bio-based 1,4-butanediol; The amine curing agent includes aliphatic amine curing agents, which include one or more of 1,4-butanediamine, diethylenetriamine, and triethylenetetramine. In the cyclic carbonate composition, the mass ratio of the carbonated soybean oil to the butanediol bicyclic carbonate is (3~7):(3~7); The ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition is (0.6~0.85):1; Based on 100 parts by weight of the cyclic carbonate composition, the amine curing agent comprises 22 to 42 parts by weight.

[0006] Optionally, in some embodiments of this application, the cyclic carbonate composition and the amine curing agent undergo an aminolysis reaction in the presence of a catalyst; The catalyst includes an organic base catalyst, which includes one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene; The polyurethane prepolymer also includes a polyurethane prepolymer obtained by aminolysis reaction of a crosslinking agent and an amine curing agent; The crosslinking agent includes a cyclic carbonate crosslinking agent, wherein the functionality of the cyclic carbonate crosslinking agent is 3 to 8. Optionally, the crosslinking agent includes one or more of trimethylolpropane tricarbonate, glyceryl tricarbonate, and pentaerythritol tetraglycidyl ether carbonate; Based on 100 parts by mass of the cyclic carbonate composition, the catalyst comprises 2 to 7 parts by mass, and the crosslinking agent comprises 0 to 18 parts by mass.

[0007] Optionally, in some embodiments of this application, the polyurethane prepolymer mixture further includes fillers, foam stabilizers, and antioxidants; the fillers, foam stabilizers, and antioxidants are each independently dispersed in the polyurethane prepolymer. The filler includes inorganic nucleation-reinforcing filler, which includes one or more of diatomaceous earth and fumed silica. The foam leveling agent includes an organosilicon foam leveling agent, which includes one or more of rigid foam silicone oil AK8805, rigid foam silicone oil AK8809, rigid foam silicone oil AK8805, and Dow Corning DC5598. The antioxidant includes hindered phenolic antioxidants, and the hindered phenolic antioxidants include one or more of antioxidant 1010 and antioxidant 1076; Based on 100 parts by weight of the cyclic carbonate composition, the filler comprises 0.8 to 4.5 parts by weight, the foam leveler comprises 0.8 to 2.5 parts by weight, and the antioxidant comprises 0.2 to 0.8 parts by weight.

[0008] Optionally, in some embodiments of this application, The number-average molecular weight of the polyurethane prepolymer is 1500 g / mol to 5000 g / mol; The viscosity of the polyurethane prepolymer mixture is 1500 mPa·s to 2500 mPa·s.

[0009] Optionally, in some embodiments of this application, the polyurethane foam composition further includes a self-foaming agent, which includes a difunctional thiol self-foaming agent; The molecular formula of the bifunctional thiol self-foaming agent is HS-R1-O-R2-SH or HS-R3-O-R4-O-R5-SH; wherein R1 and R2 are each independently selected from C1 to C2. 10 Alkylenes, R3, R4, and R5 are each independently selected from C1 to C5 alkylenes; Optionally, the self-foaming agent includes 3,6-dioxa-1,8-octanedithiol; The ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates in the cyclic carbonate composition is (0.15~0.4):1; Based on 100 parts by weight of the cyclic carbonate composition, the self-foaming agent comprises 12 to 28 parts by weight.

[0010] Accordingly, embodiments of this application also provide a polyurethane foam, which is made from the polyurethane foam composition described above.

[0011] Optionally, in some embodiments of this application, the initial thermal conductivity of the polyurethane foam is 0.0192 W / (m·K) to 0.0198 W / (m·K); The closed-cell rate of the polyurethane foam is ≥92%; The deformation compressive stress of the polyurethane foam is ≥130 kPa; The apparent core density of the polyurethane foam is ≤36 kg / m³. 3 ; The low-temperature dimensional stability of the polyurethane foam is ≤0.8%; The dimensional stability of the polyurethane foam under humid heat is ≤1.5%.

[0012] Accordingly, this application also provides a method for preparing polyurethane foam, comprising the following steps: A mixture is provided; the mixture comprises a cyclic carbonate composition comprising carbonated soybean oil and butanediol bicyclic carbonate; An amine curing agent and a catalyst are added to the mixture to carry out an aminolysis reaction to obtain a polyurethane prepolymer mixture; the polyurethane prepolymer mixture and a self-foaming agent are mixed and injected into a mold for curing and aging to obtain polyurethane foam.

[0013] Optionally, in some embodiments of this application, the method for preparing the carbonated soybean oil includes the following steps: Epoxidized soybean oil undergoes a cycloaddition reaction with carbon dioxide to obtain the carbonated soybean oil; In the cycloaddition reaction process, the cycloaddition reaction catalyst used includes at least one of tetrabutylammonium iodide, tetrabutylammonium chloride, and lithium bromide; The mass ratio of the epoxidized soybean oil to the cycloaddition reaction catalyst is 100:(4~8). The pressure of the cycloaddition reaction is 2.0 MPa to 6.0 MPa, the reaction temperature is 110℃ to 150℃, and the reaction time is 12h to 36h.

[0014] Optionally, in some embodiments of this application, the mixture further includes fillers, foam stabilizers, and antioxidants; The provided mixture includes: The carbonated soybean oil, butanediol bicyclic carbonate, filler, foaming agent and antioxidant are mixed at 65℃~75℃ and stirred at 300 rpm~500 rpm for 15 min~30 min to obtain the mixture.

[0015] Optionally, in some embodiments of this application, providing the mixture further includes: A crosslinking agent is added when the carbonated soybean oil, the butanediol bicyclic carbonate, the filler, the foaming agent, and the antioxidant are mixed. The crosslinking agent includes a cyclic carbonate crosslinking agent, wherein the functionality of the cyclic carbonate crosslinking agent is 3 to 8; Optionally, the crosslinking agent includes one or more of trimethylolpropane tricarbonate, glycerol tricarbonate, and pentaerythritol tetraglycidyl ether carbonate.

[0016] Optionally, in some embodiments of this application, the addition of an amine curing agent and a catalyst to the mixture for an aminolysis reaction includes: Under conditions of 65℃~75℃, an amine curing agent and a catalyst are added to the mixture, and the mixture is stirred at a speed of 300 rpm~500 rpm for 8 min~12 min to obtain the polyurethane prepolymer mixture, wherein the polyurethane prepolymer mixture includes the polyurethane prepolymer. The polyurethane prepolymer is mainly obtained by the cyclic carbonate composition and the amine curing agent under the action of the catalyst through an aminolysis reaction.

[0017] Optionally, in some embodiments of this application, the mixing speed of the polyurethane prepolymer mixture and the self-foaming agent is 900 rpm to 1100 rpm, and the mixing time of the polyurethane prepolymer mixture and the self-foaming agent is 1.5 min to 2.5 min. The temperature of the mold is 40~60℃; The curing temperature is 90~110℃, and the curing time is 15 min~25 min; The curing temperature is 90~110℃, and the curing time is 0.5 h~1.5 h.

[0018] Accordingly, this application also provides a refrigeration device, which includes an insulation layer. The insulation layer is made of the polyurethane foam described above, or the insulation layer is made of polyurethane foam prepared by the method described above.

[0019] It is understandable that carbonated soybean oil serves as the core rigid framework for constructing the polymer crosslinking network, while butanediol bicyclic carbonate provides end sites for foaming activity and participates in the construction of the polymer crosslinking network. Furthermore, through the synergy of carbonated soybean oil and butanediol bicyclic carbonate, that is, carbonated soybean oil and butanediol bicyclic carbonate respectively form structurally complementary polymer crosslinking networks with amine curing agents, a sufficiently high crosslinking density can be provided to ensure that a polyurethane prepolymer with a certain melt strength is obtained, thus providing a foundation for the subsequent nucleation and shaping of bubbles. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of the polyurethane foam preparation method provided in the embodiments of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0025] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0026] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0027] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0028] Nonisocyanate polyurethane (NIPU) rigid foam is usually prepared by using a single small molecule cyclic carbonate system combined with external chemical foaming agents such as sodium bicarbonate and azodicarbonamide. However, the NIPU rigid foam obtained in this way has the following problems: (1) The single cyclic carbonate system cannot take into account the foaming reactivity, foaming effect and rigid mechanical properties and dimensional stability of NIPU rigid foam, resulting in insufficient comprehensive performance of NIPU rigid foam; (2) The added chemical foaming agent will cause the foaming agent decomposition temperature to be mismatched with the curing temperature, and thus the foaming and gelation rates will be seriously disconnected, resulting in low closed-cell rate and excessive thermal conductivity of the obtained NIPU rigid foam. In addition, the impurities remaining after the decomposition of the foaming agent will significantly reduce the aging resistance of NIPU rigid foam; (3) the proportion of bio-based raw materials is generally less than 50%, the carbon reduction value is limited, and the core properties of the obtained NIPU rigid foam, such as closed cell rate, compressive strength, and dimensional stability, cannot meet the national mandatory standard GB / T 26689-2024 "Rigid polyurethane foam for refrigerators and freezers", and have no industrial application value.

[0029] The technical solution of this application is as follows: In a first aspect, embodiments of this application provide a polyurethane foam composition comprising a polyurethane prepolymer mixture, wherein the polyurethane prepolymer mixture includes the polyurethane prepolymer, and the polyurethane prepolymer is mainly obtained by an aminolysis reaction of a cyclic carbonate composition and an amine curing agent; wherein the cyclic carbonate composition includes carbonated soybean oil and butanediol bicyclic carbonate.

[0030] In this embodiment, the polyurethane prepolymer refers to the non-isocyanate polyurethane (NIPU) prepolymer.

[0031] The carbonated soybean oil is a multifunctional bio-based cyclic carbonate obtained by cycloaddition reaction of epoxidized soybean oil and carbon dioxide. The average functionality of the carbonated soybean oil is 3.5 to 4.0. The average functionality can be calculated based on the fatty acid composition of epoxidized soybean oil, the number of epoxy groups, and the carbonation conversion rate (≥98%), by dividing the total number of functional groups by the total number of molecules. For example, it can be 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, or any value or range between two values.

[0032] The butanediol bicyclic carbonate is a bifunctional terminal cyclic carbonate derived from bio-based 1,4-butanediol. It has highly reactive terminal sites and can therefore serve as a core matrix resin component and a self-foaming reactive component to participate in the construction of polyhydroxycarbamate crosslinking networks (hereinafter referred to as polymer crosslinking networks).

[0033] In this embodiment, the amine curing agent may include one or more of aliphatic diamines (such as ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,6-hexanediamine, and 2,2'-(ethylenedioxy)-bis-ethylamine), alicyclic diamines (such as isophorone diamine and cyclohexanediamine), aromatic diamines (such as m-phenylenediamine and diaminodiphenylmethane), and aliphatic polyamines (such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine).

[0034] Considering the high volatility and toxic odor of ethylenediamine and 1,3-propanediamine; the slightly low reactivity and excessively long gel time of 1,6-hexanediamine; the presence of ether bonds in 2,2'-(ethylenedioxy)-bis-ethylamine, making it more suitable for flexible foam preparation but expensive; the low reactivity of alicyclic diamines, with gel times >90s, resulting in insufficient melt strength of the prepared polyurethane prepolymer, leading to foam collapse, and their high cost; the extremely low reactivity of aromatic diamines, requiring high temperatures for aminolysis, resulting in a dark yellow, brittle rigid polyurethane foam, and the carcinogenicity of some aromatic diamines; and the fact that excessively high functionality of aliphatic polyamines, when used alone, can lead to excessively rapid gelation rates and overly rigid crosslinking networks, resulting in brittle rigid polyurethane foam, in some embodiments, the amine curing agent includes aliphatic amine curing agents, specifically one or more of 1,4-butanediamine, diethylenetriamine, and triethylenetetramine.

[0035] It should also be noted that when the amine curing agent includes diethylenetriamine and / or triethylenetetramine, it needs to be used in combination with 1,4-butanediamine. If the amine curing agent only includes diethylenetriamine and / or triethylenetetramine, its high functionality will lead to an excessively fast gelation rate and an overly rigid crosslinking network, resulting in a more brittle rigid polyurethane foam.

[0036] In some embodiments, based on 100 parts by weight of the cyclic carbonate composition, the amine curing agent is 22 to 42 parts by weight, for example, 22 parts, 25 parts, 30 parts, 35 parts, 40 parts, 42 parts, or any value or range between two parts.

[0037] In some embodiments, the mass ratio of the carbonated soybean oil to the butanediol bicyclic carbonate in the cyclic carbonate composition is (3~7):(3~7), for example, it can be 1:1, 3:4, 3:5, 3:6, 3:7, 4:5, 4:6, 6:4, 6:5 or any value or range between two ratios.

[0038] It is understandable that carbonated soybean oil serves as the core rigid framework for constructing the polymer crosslinking network, while butanediol bicyclic carbonate provides end sites for foaming activity and participates in the construction of the polymer crosslinking network. Furthermore, through the synergy of carbonated soybean oil and butanediol bicyclic carbonate, that is, carbonated soybean oil and butanediol bicyclic carbonate respectively form structurally complementary polymer crosslinking networks with amine curing agents, a sufficiently high crosslinking density can be provided to ensure that a polyurethane prepolymer with a certain melt strength is obtained, thus providing a foundation for the subsequent nucleation and shaping of bubbles.

[0039] Specifically, on the one hand, bio-based butanediol bicyclic carbonate provides linear flexible segments, balancing the rigidity and toughness of the resulting polyurethane foam to prevent brittleness. Carbonated soybean oil provides high functionality, high rigidity, and high bio-based content, serving as the core rigid framework of the polymer crosslinking network and the core source of the system's mechanical strength, resulting in polyurethane foam with high strength and high dimensional stability. On the other hand, the crosslinking density can be precisely controlled by blending carbonated soybean oil and butanediol bicyclic carbonate in a certain ratio, achieving a match between foaming rate and gelation rate. Thus, through these two aspects, namely the synergy of carbonated soybean oil and butanediol bicyclic carbonate, core properties such as high closed-cell rate (≥92%, up to 95.1%), high strength (10% deformation compressive stress ≥150 kPa, up to 185 kPa), and dimensional stability (-30℃ low-temperature dimensional change rate ≤0.75%, 70℃ damp-heat dimensional change rate ≤1.05%) can be obtained, fully complying with the standards GB / T 26689-2024 Ⅰ for rigid refrigerator foam. This addresses the issue of "low bio-based content in non-isocyanate polyurethane rigid foam systems, and the inability to simultaneously achieve self-foaming reactivity, foaming effect, and the mechanical properties and dimensional stability of NIPU rigid foam" by meeting national standards. It should also be noted that without amine curing agents, non-isocyanate polyurethane rigid foam systems cannot form a stable polymer crosslinking network, still exhibiting problems such as poor foaming, insufficient rigidity, and poor dimensional stability. Furthermore, the polyurethane prepolymer formed by the aminolysis reaction of the cyclic carbonate composition and the amine curing agent is the first step in constructing a highly crosslinked rigid polymer crosslinking network. Therefore, the aminolysis reaction here specifically refers to the aminolysis prepolymerization reaction. Subsequent low-temperature prepolymerization (65℃~75℃, 8 min~12 min) yields the polyurethane prepolymer, which solves the problem of "differences in structure and reactivity between carbonated soybean oil and butanediol bicyclic carbonate," thus achieving a balance between self-foaming reactivity, foaming effect, and the mechanical properties and dimensional stability of NIPU rigid foam.

[0040] Furthermore, the polyurethane foam composition provided in this embodiment can achieve a bio-based content of up to 94% in the resulting polyurethane foam, reducing its carbon footprint over its entire life cycle by more than 60% compared to traditional systems. Consequently, the polyurethane foam is cyanide-free, environmentally friendly, and recyclable after disposal, with no solid waste pollution. Moreover, the polyurethane foam does not release highly toxic gases such as hydrogen cyanide when it burns, significantly improving the fire safety performance of the polyurethane foam and meeting the requirements of the dual-carbon policy and the development of a circular economy.

[0041] In some embodiments, the cyclic carbonate composition and the amine curing agent undergo an aminolysis reaction in the presence of a catalyst.

[0042] The catalyst includes an organic base catalyst, which includes one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0043] The catalyst provided in this embodiment is used not only to catalyze the aminolysis reaction, but also to catalyze the subsequent S-alkylation self-foaming reaction, so as to simultaneously catalyze the aminolysis reaction (i.e., the gelation reaction) and the S-alkylation self-foaming reaction, ensuring that the activation energies of the two reactions are completely matched.

[0044] Considering the catalytic activity and selectivity, the organic base catalyst preferably comprises 1,8-diazabicyclo[5.4.0]undec-7-ene (CAS: 6674-22-2).

[0045] In some embodiments, the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition is (0.6~0.85):1, for example, it can be 0.6:1, 0.7:1, 0.8:1, 0.85:1, or any value or range between two ratios. Within this range, the crosslinking density of the polymer crosslinking network is moderate, and the polymer crosslinking network has both rigidity and toughness. It should also be noted that the amine curing agent is used to precisely control the crosslinking density. If the molar ratio is lower than 0.6, the crosslinking is insufficient, and the final polyurethane foam is too soft; if the molar ratio is higher than 0.85, the crosslinking is too dense, and the final polyurethane foam is too brittle and prone to cracking.

[0046] The cyclic carbonate composition includes cyclic carbonates of carbonated soybean oil and cyclic carbonates of butanediol bicyclic carbonate. It should also be noted that when the system further includes a crosslinking agent, the total molar number of cyclic carbonates also includes the molar number of cyclic carbonates of the crosslinking agent.

[0047] In some embodiments, based on 100 parts by weight of the cyclic carbonate composition, the mass of the catalyst is 2 to 7 parts, for example, 2, 3, 4, 5, 6, 7 parts or any value or range between two parts. If the mass of the catalyst is less than 2 parts, the melt strength of the polyurethane prepolymer will be insufficient, resulting in cell rupture and incomplete curing. If the mass of the catalyst is more than 7 parts, the cyclic carbonate composition will gel prematurely, fail to foam, and have excessively brittle foam.

[0048] It should also be noted that when the catalyst includes one or more of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, it is necessary to use 1,8-diazabicyclo[5.4.0]undec-7-ene as the main catalyst. In this embodiment, 1,8-diazabicyclo[5.4.0]undec-7-ene is used as the main catalyst, and the amount of the main catalyst is controlled at 3 to 5 parts by mass to simultaneously catalyze the amine degelation reaction and the S-alkylation self-foaming reaction, ensuring that the activation energies of the two reactions are completely matched. At the critical node of polymer crosslinking network formation, the nucleation, growth and shaping of bubbles are completed simultaneously.

[0049] To further improve the crosslinking density and mechanical rigidity of the polyurethane prepolymer, in some embodiments, the polyurethane prepolymer also includes a polyurethane prepolymer obtained by aminolysis reaction of a crosslinking agent and an amine curing agent.

[0050] The crosslinking agent includes a cyclic carbonate crosslinking agent, wherein the functionality of the cyclic carbonate crosslinking agent is 3 to 8.

[0051] Furthermore, the crosslinking agent includes one or more of trimethylolpropane tricarbonate, glycerol tricarbonate, and pentaerythritol tetraglycidyl ether carbonate.

[0052] Trimethylolpropane tricarbonate is prepared by cycloaddition of trimethylolpropane triglycidyl ether (CAS: 30499-70-8) with CO2, glycerol tricarbonate is prepared by cycloaddition of glycerol triglycidyl ether with CO2, and pentaerythritol tetraglycidyl ether carbonate is prepared by cycloaddition of pentaerythritol tetraglycidyl ether (CAS: 3126-63-4) with CO2.

[0053] In this embodiment, a high-functionality cyclic carbonate crosslinking agent simultaneously participates in the aminolysis prepolymerization reaction of the cyclic carbonate composition to form a polyurethane prepolymer with a certain melt strength. This improves the crosslinking density, rigidity, and dimensional stability of the polyurethane foam, thereby further solving the problem that "the self-foaming reactivity, foaming effect, and mechanical properties and dimensional stability of NIPU rigid foam cannot be simultaneously considered, resulting in the core performance of NIPU rigid foam failing to meet the national standard requirements of GB / T 26689-2024 for rigid refrigerator foam." Specifically, the deformation compressive stress of the polyurethane foam can be further increased from 170 kPa to 185 kPa, and the closed-cell rate of the polyurethane foam can be further increased from 94.2% to 95.1%.

[0054] In some embodiments, the crosslinking agent is 0 to 18 parts by mass, based on 100 parts by mass of the cyclic carbonate composition. For example, it can be 0 parts, 5 parts, 10 parts, 15 parts, 18 parts, or any value or range between two values.

[0055] In some embodiments, the polyurethane prepolymer mixture further includes fillers, foam levelers, and antioxidants, each of which is independently dispersed in the polyurethane prepolymer.

[0056] The filler includes inorganic nucleating and reinforcing filler, which includes one or more of diatomaceous earth and fumed silica; the foam leveler includes organosilicon foam leveler, which includes one or more of rigid foam silicone oil AK8805, rigid foam silicone oil AK8809, and Dow Corning DC5598; the antioxidant includes hindered phenolic antioxidant, which includes one or more of antioxidant 1010 (CAS: 6683-19-8) and antioxidant 1076 (CAS: 2082-79-3).

[0057] In this embodiment, the filler, foam stabilizer, and antioxidant are each independently and uniformly dispersed in the polyurethane prepolymer. The inorganic nucleating reinforcing filler provides a large number of uniform nucleation sites for the bubbles, precisely controlling the pore size of the polyurethane foam to 150~250μm and the pore size distribution coefficient ≤0.3, thus achieving uniform and controllable pore structure and providing a structural basis for excellent thermal insulation and mechanical properties. The silicone foam stabilizer reduces the surface tension of the reaction system, stabilizes the bubble walls, and improves the closed-cell rate and pore uniformity. The hindered phenolic antioxidant inhibits the thermo-oxidative aging of the polyurethane foam and improves the long-term aging resistance of the polyurethane foam product.

[0058] In some embodiments, based on 100 parts by weight of the cyclic carbonate composition, the filler comprises 0.8 to 4.5 parts by weight, the foam leveler comprises 0.8 to 2.5 parts by weight, and the antioxidant comprises 0.2 to 0.8 parts by weight.

[0059] For example, the mass fraction of the filler can be 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, or any value or range between two such fractions; the mass fraction of the foaming agent can be 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, or any value or range between two such fractions; and the mass fraction of the antioxidant can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, or any value or range between two such fractions.

[0060] In some embodiments, the number-average molecular weight of the polyurethane prepolymer is 1500 g / mol to 5000 g / mol; In some embodiments, the viscosity of the polyurethane prepolymer mixture is 1500 mPa·s to 2500 mPa·s.

[0061] In this embodiment, the viscosity of the polyurethane prepolymer can be precisely controlled between 1500 and 2500 mPa·s through a low-temperature prepolymerization process (65℃~75℃, 8 min~12 min). This not only ensures the uniformity of the subsequent S-alkylation self-foaming reaction, but also provides suitable melt strength for the nucleation, growth, and shaping of bubbles. As a result, the melt strength is always greater than the internal pressure of the bubbles, and the cell walls do not rupture before gel solidification. This avoids problems such as cell collapse, merging, and rupture, and enables the controllable preparation of closed-cell cell structures to obtain a uniform and fine closed-cell cell structure.

[0062] Considering that the addition of external chemical foaming agents can lead to a mismatch between the decomposition temperature and curing temperature, resulting in a severe disconnect between the foaming rate and gelation rate, the resulting rigid NIPU foam will have a low closed-cell rate and a thermal conductivity exceeding national standards. Furthermore, impurities remaining after the foaming agent decomposition will significantly reduce the aging resistance of the rigid NIPU foam. Therefore, in some embodiments, the polyurethane foam composition further includes a self-foaming agent, which includes a difunctional thiol self-foaming agent.

[0063] Furthermore, the molecular formula of the bifunctional thiol self-foaming agent is HS-R1-O-R2-SH or HS-R3-O-R4-O-R5-SH; wherein R1 and R2 are each independently selected from C1 to C2. 10 The alkylene groups R3, R4, and R5 are each independently selected from C1 to C5 alkylene groups.

[0064] In this embodiment, in order to match the molecular structure of butanediol bicyclic carbonate and make the S-alkylation self-foaming reaction activity moderate so that its foaming rate matches the ammonolysis gelation rate (ammonolysis reaction rate), this embodiment selects a bifunctional thiol self-foaming agent with two symmetrical thiol groups (functionality = 2.0) and a flexible ether bond (-O-) in the middle of its molecule.

[0065] Considering the high functionality and extremely high reactivity of pentaerythritol tetramercaptoethanol ester, the S-alkylation self-foaming reaction rate can spike instantly, leading to problems such as premature gelation, inability to foam, or severe cell rupture and collapse. Furthermore, considering the highly volatile nature of some linear aliphatic dithiols (such as ethylenedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, and 1,6-hexanedithiol), and the fact that some have a highly toxic and irritating odor, and more importantly, that linear aliphatic dithiols lack flexible ether bonds, resulting in poor foam flexibility after crosslinking, easy microcracks at low temperatures (-30℃), and decreased dimensional stability with long-term use, their molecular structure is incompatible with that of butanediol bicyclic carbonate. Finally, considering that monofunctional thiols (such as methanethiol, ethanethiol, 2-mercaptoethanol, and mercaptoacetic acid) contain only one thiol group, they cannot form a polymer crosslinking network. Therefore, in some embodiments, preferably, the self-foaming agent comprises 3,6-dioxa-1,8-octanedithiol.

[0066] For example, when R3, R4, and R5 in HS-R3-O-R4-O-R5-SH are each independently selected from -C2H4-, the self-foaming agent includes 3,6-dioxa-1,8-octanedithiol (CAS: 14970-87-7).

[0067] It should be noted that the polyurethane prepolymer is obtained by aminolysis prepolymerization. After the polyurethane prepolymer is thoroughly mixed with a difunctional thiol self-foaming agent, an S-alkylation self-foaming reaction is triggered. Specifically, the S-alkylation self-foaming reaction refers to the S-alkylation self-foaming reaction of the cyclic carbonate groups in the reaction system under the action of a catalyst and a difunctional thiol self-foaming agent in the absence of an external blowing agent. The thiol group of the difunctional thiol self-foaming agent undergoes a nucleophilic attack reaction on the (unaminolyzed) cyclic carbonate. During the reaction, the cyclic carbonate opens its ring and releases carbon dioxide gas in situ, causing the reaction system to expand and form a cell structure. At the same time, a hydroxy sulfide structure is generated and integrated into the polymer crosslinking network to ultimately form a three-dimensional polymer crosslinking network with high crosslinking density. This is the second step in the stepwise construction of a polymer crosslinking network with high crosslinking rigidity. Furthermore, it should be noted that the fixed functionality (2.0) of butanediol bicyclic carbonate is precisely matched with the functionality of the difunctional thiol self-foaming agent, thus ensuring the efficient and stable conduct of the S-alkylation self-foaming reaction.

[0068] This embodiment achieves in-situ self-foaming by utilizing a combination of a difunctional thiol self-foaming agent and a cyclic carbonate, without the need to add any chemical foaming agents or flammable and explosive physical foaming agents. As a result, the production workshop does not require explosion-proof modifications, safety management costs are reduced by more than 70%, there is no release of volatile organic compounds (VOCs), and the highly toxic isocyanate raw material is completely eliminated, which complies with global environmental regulations.

[0069] In some embodiments, the ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates in the cyclic carbonate composition is (0.15~0.4):1, for example, it can be 0.15:1, 0.2:1, 0.3:1, 0.4:1 or any value or range between two ratios.

[0070] The cyclic carbonate composition includes cyclic carbonates of carbonated soybean oil and cyclic carbonates of butanediol bicyclic carbonate. It should also be noted that when the system further includes a crosslinking agent, the total molar number of cyclic carbonates also includes the molar number of cyclic carbonates of the crosslinking agent.

[0071] In this embodiment, by controlling the molar ratio and the catalyst and its dosage, a precise match between the foaming rate and the aminolysis gelation rate can be achieved. Specifically, on the one hand, the total molar ratio of mercapto groups to the total molar ratio of cyclic carbonates is (0.15~0.4):1, which ensures a sufficient carbon dioxide gas supply to achieve polyurethane foam of 30~36 kg / m³. 3 The target apparent core density is achieved while avoiding cell rupture caused by excessively fast foaming rate. On the other hand, 1,8-diazabicyclo[5.4.0]undec-7-ene is used as the main catalyst, and the amount of 1,8-diazabicyclo[5.4.0]undec-7-ene added is controlled at 2~7 parts by mass. Thus, the main catalyst can simultaneously catalyze the amine degelation reaction and the S-alkylation self-foaming reaction, ensuring that the activation energies of the two reactions are completely matched. At the critical node of polymer crosslinking network formation, the nucleation, growth and shaping of bubbles are completed simultaneously.

[0072] In some embodiments, the self-foaming agent is 12 to 28 parts by mass, based on 100 parts by mass of the cyclic carbonate composition. For example, it can be 12 parts, 14 parts, 15 parts, 18 parts, 20 parts, 24 parts, 28 parts, or any value or range between two parts.

[0073] Secondly, embodiments of this application also provide a polyurethane foam, which is prepared using the polyurethane foam composition described above.

[0074] Since this polyurethane foam adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0075] In some embodiments, the initial thermal conductivity of the polyurethane foam is 0.0192 W / (m·K) to 0.0198 W / (m·K); the closed-cell ratio of the polyurethane foam is ≥92%, the deformation compressive stress of the polyurethane foam is ≥130 kPa, and the apparent core density of the polyurethane foam is ≤36 kg / m³. 3 The low-temperature dimensional stability of the polyurethane foam is ≤0.8%, and the hygrothermal dimensional stability of the polyurethane foam is ≤1.5%.

[0076] Thirdly, this application also provides a method for preparing polyurethane foam; please refer to [link to relevant documentation]. Figure 1 This includes the following steps S10~S30: S10, providing a mixture; the mixture comprising a cyclic carbonate composition comprising carbonated soybean oil and butanediol bicyclic carbonate; S20, an amine curing agent and a catalyst are added to the mixture to carry out an amine hydrolysis reaction to obtain a polyurethane prepolymer mixture; S30, the polyurethane prepolymer mixture and the self-foaming agent are mixed and then injected into a mold for curing and maturation to obtain polyurethane foam.

[0077] It is understandable that by precisely controlling the formulation of the polyurethane foam composition and the preparation method of the polyurethane foam, the polyurethane foam prepared can achieve a closed-cell rate of up to 95.1%, an initial thermal conductivity as low as 0.0192 W / (m·K), a 10% deformation compressive stress as high as 185 kPa, excellent dimensional stability at high and low temperatures, and all core properties are comprehensively superior to the requirements of Class I products in GB / T26689-2024 national standard.

[0078] Specifically, the initial thermal conductivity of the polyurethane foam is 0.0192 W / (m·K) to 0.0198 W / (m·K); the closed-cell ratio of the polyurethane foam is ≥92%; the deformation compressive stress of the polyurethane foam is ≥130 kPa; and the apparent core density of the polyurethane foam is ≤36 kg / m³. 3The low-temperature dimensional stability of the polyurethane foam is ≤0.8%, and the hygrothermal dimensional stability of the polyurethane foam is ≤1.5%. It should also be noted that the formulation of the polyurethane foam composition refers to the selection of cyclic carbonates (carbonated soybean oil, butanediol bicyclic carbonate) and the specific ratio of carbonated soybean oil and butanediol bicyclic carbonate, the selection of amine curing agents (1,4-butanediamine) and their dosage, the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition, the selection of catalysts (1,8-diazabicyclo[5.4.0]undec-7-ene) and their dosage, the selection of self-foaming agents (3,6-dioxa-1,8-octanedithiol) and their dosage, and the ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates in the cyclic carbonate composition; the preparation method of the polyurethane foam refers to a stepwise construction method.

[0079] In some embodiments, the method for preparing the carbonated soybean oil includes the following steps: Epoxidized soybean oil undergoes a cycloaddition reaction with carbon dioxide to obtain the carbonated soybean oil; In the cycloaddition reaction process, the cycloaddition reaction catalyst used includes at least one of tetrabutylammonium iodide, tetrabutylammonium chloride, and lithium bromide; The mass ratio of the epoxidized soybean oil to the cycloaddition reaction catalyst is 100:(4~8). The pressure of the cycloaddition reaction is 2.0 MPa to 6.0 MPa, the reaction temperature is 110℃ to 150℃, and the reaction time is 12h to 36h.

[0080] In some embodiments, the mixture further includes filler, foam stabilizer, and antioxidant; step S10 includes: The carbonated soybean oil, butanediol bicyclic carbonate, filler, foaming agent and antioxidant are mixed at 65℃~75℃ and stirred at 300 rpm~500 rpm for 15 min~30 min to obtain the mixture.

[0081] In some embodiments, step S10 further includes: A crosslinking agent is added when the carbonated soybean oil, the butanediol bicyclic carbonate, the filler, the foaming agent, and the antioxidant are mixed.

[0082] The amounts of the carbonated soybean oil and the butanediol bicyclic carbonate, as well as the types and amounts of the filler, the foaming agent, the antioxidant, the self-foaming agent, and the crosslinking agent, are as described above and will not be repeated here.

[0083] In some embodiments, step S20 includes: Under conditions of 65℃~75℃, an amine curing agent and a catalyst are added to the mixture, and the mixture is stirred at a speed of 300 rpm~500 rpm for 8 min~12 min to obtain the polyurethane prepolymer mixture, wherein the polyurethane prepolymer mixture includes the polyurethane prepolymer. The polyurethane prepolymer is mainly obtained by the cyclic carbonate composition and the amine curing agent under the action of the catalyst through an aminolysis reaction.

[0084] In some embodiments, in step S30, The mixing speed of the polyurethane prepolymer mixture and the self-foaming agent is 900 rpm to 1100 rpm, and the mixing time of the polyurethane prepolymer mixture and the self-foaming agent is 1.5 min to 2.5 min. The temperature of the mold is 40~60℃; The curing temperature is 90~110℃, and the curing time is 15 min~25 min; The curing temperature is 90~110℃, and the curing time is 0.5 h~1.5 h.

[0085] The mixing speed and time provided in this embodiment can not only ensure that the mixture of self-foaming agent and polyurethane prepolymer reaches molecular-level uniform mixing in a very short time, avoiding asynchronous foaming and gelation caused by local concentration differences, but also provide sufficient shear force to enable the CO2 generated by the S-alkylation self-foaming reaction to rapidly nucleate and uniformly disperse into fine bubbles.

[0086] By using the pre-curing and then ripening process provided in this embodiment, the gelation reaction can be fully carried out without any unreacted monomer residue, thus avoiding a decrease in strength due to insufficient curing.

[0087] In this embodiment, in step S30, under the action of a catalyst, the amino group in the amine curing agent continues to undergo anamine hydrolysis gelation reaction with carbonated soybean oil, butanediol bicyclic carbonate, and the cyclic carbonate of the crosslinking agent to form a three-dimensional polymer crosslinking network. At the same time, under the action of a catalyst, the thiol group of the self-foaming agent undergoes nucleophilic attack on the terminal cyclic carbonate of butanediol bicyclic carbonate, triggering the S-alkylation self-foaming reaction, completing the final curing of the polymer crosslinking network. The cyclic carbonate opens its ring and releases carbon dioxide gas in situ. Carbon dioxide gas serves as the sole gas source for foaming, and no external foaming agent needs to be added throughout the process. Meanwhile, the hydroxy sulfide structure generated by the S-alkylation self-foaming reaction is directly integrated into the polymer molecular chain (i.e., the polymer crosslinking network), and the self-foaming agent becomes a component of the polymer crosslinking network. This achieves the effect of "in-situ generation of foaming gas source and simultaneous participation of foaming agent in crosslinking." Not only is there no residue of any small molecule impurities, thus avoiding the problems caused by external foaming agents from the root, but the resulting polyurethane foam has a thermal decomposition initiation temperature ≥220℃, which can meet the long-term use requirements of refrigerators for more than 10 years. It should be noted that when the self-blowing agent undergoes nucleophilic attack on the terminal cyclic carbonate of butanediol bicyclic carbonate, the terminal cyclic carbonate of butanediol bicyclic carbonate undergoes an S-alkylation ring-opening reaction with the thiol group of the self-blowing agent. This delays the gelation time and adjusts the melt strength of the polyurethane prepolymer, providing adjustable space for reaction rate matching. It should also be noted that carbonated soybean oil does not contain terminal cyclic carbonate; therefore, it is inert in the S-alkylation self-blowing reaction.

[0088] Furthermore, this embodiment achieves uniform nucleation of bubbles by constructing the polyurethane prepolymer in two steps (first, constructing a polyurethane prepolymer to form a rigid main chain, and further controlling the basic viscosity of the polyurethane prepolymer through a low-temperature prepolymerization process; second, adding a self-foaming agent to complete the final curing of the polymer crosslinking network to form flexible side chains and realize a gradient crosslinking network), ultimately forming a uniform and dense closed-cell structure.

[0089] Fourthly, embodiments of this application provide a refrigeration device, the refrigeration device including a heat insulation layer, the heat insulation layer being made of the polyurethane foam described above, or the heat insulation layer being made of polyurethane foam prepared by the method described above.

[0090] Since this refrigeration equipment adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here. The refrigeration equipment can be various types of refrigeration and insulation equipment such as household refrigerators, cold chain refrigerators, freezers, refrigerated trucks, and refrigerated containers.

[0091] The present application will be specifically described below through specific embodiments. These embodiments are only some embodiments of the present application and are not intended to limit the present application. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0092] Example 1 Epoxidized soybean oil (epoxide value 6.5, epoxy group concentration 4.43 mol / L) in a mass ratio of 100:7.5 and tetrabutylammonium bromide were added to a high-pressure reactor. After sealing, the air inside the reactor was purged with nitrogen three times. The temperature was raised to 130℃, the stirring speed was 800 rpm, and carbon dioxide was continuously introduced to maintain the pressure inside the reactor at 4.0 MPa. The reaction was carried out at constant temperature and pressure for 24 h. After the reaction was completed, the temperature was lowered to room temperature, the pressure was released, and the product was extracted five times with ethyl acetate-deionized water to remove the catalyst. The solvent and residual water were removed by rotary evaporation to obtain carbonated soybean oil. The epoxide conversion rate of the epoxidized soybean oil was 98.5%, the yield of carbonated soybean oil was 92.3%, and the average functionality was 3.7.

[0093] Add 50 parts of the carbonated soybean oil prepared above, 50 parts of butanediol bicyclic carbonate, 2 parts of filler (diatomaceous earth), 1.5 parts of AK8805 rigid foam-specific silicone foam stabilizer, and 0.5 parts of antioxidant 1010 to the reactor, heat to 70℃, preheat for 20 min, and stir at 400 rpm until uniformly mixed; after uniform mixing, add 32 parts of amine curing agent (1,4-butanediamine) and 4 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene), wherein the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonate groups in the cyclic carbonate composition is 0.72:1, maintain the temperature at 70℃, stir for 10 min to complete the amine depolymerization prepolymerization reaction, and obtain a polyurethane prepolymer mixture (a transparent and homogeneous non-isocyanate polyurethane prepolymer mixture). The number average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture is 2800 g / mol, and the viscosity of the polyurethane prepolymer mixture is 2100 g / mol. mPa·s.

[0094] 20 parts of self-foaming agent (3,6-dioxa-1,8-octanedithiol) were rapidly added to the polyurethane prepolymer mixture, wherein the ratio of the total molar number of mercapto groups to the total molar number of cyclic carbonates in the self-foaming agent was 0.22:1. The stirring speed was immediately increased to 1000 rpm and stirred at high speed for 2 min to ensure that the self-foaming agent was fully mixed with the polyurethane prepolymer in the polyurethane prepolymer mixture, triggering the S-alkylation self-foaming reaction. Subsequently, it was quickly poured into a refrigerator cabinet mold, the mold was preheated to 50°C, and the mold was sent to a curing oven at 100°C for 20 min, and then cured at 100°C for 1 h. After the mold was opened, rigid non-isocyanate polyurethane foam for refrigerators was obtained.

[0095] Example 2 The difference between this embodiment and Example 1 is that the mass fractions of carbonated soybean oil and butanediol bicyclic carbonate are different, and the mass fractions of other components are adjusted accordingly. Specifically, 50 parts of carbonated soybean oil and 50 parts of butanediol bicyclic carbonate are replaced with 60 parts of carbonated soybean oil and 40 parts of butanediol bicyclic carbonate; 32 parts of amine curing agent (1,4-butanediamine) are replaced with 30 parts of amine curing agent (1,4-butanediamine); 4 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene) are replaced with 3.5 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene); and 20 parts of self-foaming agent (3,6-dioxa-1,8-octanedithiol) are replaced with 18 parts of self-foaming agent (3,6-dioxa-1,8-octanedithiol). In this embodiment, the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition is 0.68:1, and the ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates is 0.20:1.

[0096] In this embodiment, the number-average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture is 3100 g / mol, and the viscosity of the polyurethane prepolymer mixture is 2350 mPa·s.

[0097] Example 3 The difference between this embodiment and Example 1 is that the mass fractions of carbonated soybean oil and butanediol bicyclic carbonate are different, and the mass fractions of other components are adjusted accordingly. Specifically, 50 parts of carbonated soybean oil and 50 parts of butanediol bicyclic carbonate are replaced with 40 parts of carbonated soybean oil and 60 parts of butanediol bicyclic carbonate; 32 parts of amine curing agent (1,4-butanediamine) are replaced with 35 parts of amine curing agent (1,4-butanediamine); 4 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene) are replaced with 4.5 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene); and 20 parts of self-foaming agent (3,6-dioxa-1,8-octanedithiol) are replaced with 22 parts of self-foaming agent (3,6-dioxa-1,8-octanedithiol). In this embodiment, the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition is 0.78:1, and the ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates is 0.24:1.

[0098] In this embodiment, the number-average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture is 2500 g / mol, and the viscosity of the polyurethane prepolymer mixture is 1850 mPa·s.

[0099] Example 4 The difference between this embodiment and Embodiment 1 is that the mass fractions of carbonated soybean oil and butanediol bicyclic carbonate are different, and a crosslinking agent is added, with the mass fractions of other components adjusted accordingly. Specifically, 45 parts of the carbonated soybean oil prepared above, 45 parts of butanediol bicyclic carbonate, 2 parts of filler (diatomaceous earth), 1.5 parts of AK8805 rigid foam-specific silicone foam stabilizer, 0.5 parts of antioxidant 1010 and 10 parts of crosslinking agent (trimethylolpropane tricarbonate crosslinking agent) were added to the reactor, heated to 70°C, preheated for 20 min, and stirred at 400 rpm until uniformly mixed. After uniform mixing, 36 parts of amine curing agent (32 parts of 1,4-butanediamine and 2 parts of diethylenetriamine) and 4 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene) were added, the temperature was maintained at 70°C, and stirred for 10 min to complete the amine decomposition prepolymerization reaction, and a polyurethane prepolymer mixture was obtained. The number average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture was 3400 g / mol, and the viscosity of the polyurethane prepolymer mixture was 2400 mPa·s.

[0100] In this embodiment, the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition (including carbonated soybean oil, butanediol bicyclic carbonate and crosslinking agent) is 0.78:1, and the ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates is 0.22:1.

[0101] Comparative Example 1 The difference between this comparative example and Example 1 is that it lacks butanediol bicyclic carbonate, and the mass fractions of other components are adjusted accordingly.

[0102] Specifically, 100 parts of the carbonated soybean oil prepared above, 2 parts of filler (diatomaceous earth), 1.5 parts of AK8805 rigid foam-specific silicone foam stabilizer and 0.5 parts of antioxidant 1010 were added to the reactor, heated to 70°C, preheated for 20 min, and stirred at 400 rpm until uniformly mixed. After uniform mixing, 28 parts of amine curing agent (1,4-butanediamine) and 4 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene) were added, the temperature was maintained at 70°C, and stirred for 10 min to complete the amine decomposition prepolymerization reaction and obtain a polyurethane prepolymer mixture. In this comparative example, the number average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture was 3600 g / mol, and the viscosity of the polyurethane prepolymer mixture was 3200 mPa·s.

[0103] In this comparative example, the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition was 0.69:1, and the ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates was 0.24:1.

[0104] Comparative Example 2 The difference between this comparative example and Example 1 is that it lacks carbonated soybean oil, and the mass fractions of other components are adjusted accordingly.

[0105] Specifically, 100 parts of butanediol bicyclic carbonate, 2 parts of filler (diatomaceous earth), 1.5 parts of AK8805 rigid foam silicone foam stabilizer and 0.5 parts of antioxidant 1010 were added to the reactor, heated to 70°C, preheated for 20 minutes, and stirred at 400 rpm until uniformly mixed. After uniform mixing, 38 parts of amine curing agent (1,4-butanediamine) and 4 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene) were added, the temperature was maintained at 70°C, and stirred for 10 minutes to complete the amine decomposition prepolymerization reaction and obtain a polyurethane prepolymer mixture. In this comparative example, the number average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture was 2200 g / mol, and the viscosity of the polyurethane prepolymer mixture was 1600 mPa·s.

[0106] In this comparative example, the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition was 0.80:1, and the ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates was 0.20:1.

[0107] Comparative Example 3 The difference between this comparative example and Example 1 is that an external foaming agent is used for foaming.

[0108] Specifically, 50 parts of the carbonated soybean oil prepared above, 50 parts of butanediol bicyclic carbonate, 2 parts of filler (diatomaceous earth), 1.5 parts of AK8805 rigid foam-specific silicone foam stabilizer and 0.5 parts of antioxidant 1010 are added to the reactor, heated to 70°C, preheated for 20 min, and stirred at 400 rpm until uniformly mixed; after uniform mixing, 32 parts of amine curing agent (1,4-butanediamine) and 4 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene) are added, wherein the ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonate groups in the cyclic carbonate composition is 0.72:1, the temperature is maintained at 70°C, and stirred for 10 min to complete the amine decomposition prepolymerization reaction, and a polyurethane prepolymer mixture is obtained. The number average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture is 2800 g / mol, and the viscosity of the polyurethane prepolymer mixture is 2100 mPa·s.

[0109] Add 20 parts of foaming agent (sodium bicarbonate) quickly to the polyurethane prepolymer mixture, immediately increase the stirring speed to 1000 rpm, stir at high speed for 2 minutes, and then quickly pour it into the refrigerator cabinet mold. Preheat the mold to 50°C, send the mold into the curing oven, and cure it at 100°C for 20 minutes, and then cure it at 100°C for 1 hour. After opening the mold, rigid non-isocyanate polyurethane foam for refrigerators is obtained.

[0110] Comparative Example 4 The difference between this comparative example and Example 1 is that the polyurethane foam was prepared using a conventional isocyanate polyurethane foam preparation method.

[0111] Mix 100 parts of polyether polyol 4110, 2 parts of amine catalyst A33, 0.3 parts of stannous octoate T-9 catalyst, 2 parts of filler (diatomaceous earth), 1.5 parts of AK8805 rigid foam silicone foam stabilizer, and 0.5 parts of antioxidant 1010 at 800 rpm. Then add 12 parts of cyclopentane (as a physical foaming agent with a purity ≥95%) and continue stirring at 800 rpm for 10 minutes to obtain the combined polyether.

[0112] At an ambient temperature of 25°C, 155 parts of polymeric diphenylmethane diisocyanate were added to the polyether mixture. The mixture was then mixed at high speed with an injection pressure of 14 MPa using a high-pressure foaming machine commonly used in the refrigerator industry. The mixing time was controlled to be 3 seconds. Immediately after 3 seconds, the mixture was injected into a refrigerator body mold preheated to 45°C. After the mold was closed, the foaming reaction was carried out. After foaming was completed (25 seconds), the refrigerator body mold was kept at a constant temperature of 45°C for 20 minutes for curing. Then, the mold was opened and the cured polyurethane foam inside the mold was removed. The cured polyurethane foam inside the mold was placed in an oven at 60°C for post-curing treatment for 8 hours to obtain polyurethane foam.

[0113] Comparative Example 5 The difference between this comparative example and Example 1 is that 4 parts of catalyst (1,8-diazabicyclo[5.4.0]undec-7-ene) were replaced with 3 parts of 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene as the catalyst.

[0114] In this comparative example, the number-average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture is 3050 g / mol, and the viscosity of the polyurethane prepolymer mixture is 2280 mPa·s.

[0115] Comparative Example 6 The difference between this comparative example and Example 1 is that the self-foaming agent (3,6-dioxa-1,8-octanedithiol) is replaced with pentaerythritol tetra(3-mercaptopropionate) as the self-foaming agent.

[0116] Specifically, the ratio of the total molar number of mercapto groups to the total molar number of cyclic carbonates in pentaerythritol tetra(3-mercaptopropionate) is 0.22:1.

[0117] Comparative Example 7 The difference between this comparative example and Example 1 is that the temperature of the amine hydrolysis prepolymerization reaction is different; in this comparative example, a medium-high temperature of 85°C is used for prepolymerization.

[0118] In this comparative example, the number-average molecular weight of the polyurethane prepolymer in the polyurethane prepolymer mixture is 3750 g / mol, and the viscosity of the polyurethane prepolymer mixture is 3120 mPa·s.

[0119] The content of each component in the polyurethane foam compositions of Examples 1-4 and Comparative Examples 1-7 is shown in Table 1 below.

[0120] Table 1. Content of each component in the polyurethane foam compositions of Examples 1-4 and Comparative Examples 1-7

[0121] The polyurethane foams obtained in Examples 1-4 and Comparative Examples 1-7 were subjected to performance tests. The performance tests included: initial thermal conductivity, 10% deformation compressive stress, low temperature dimensional stability, hygrothermal dimensional stability, apparent core density, closed-cell rate, water absorption rate, and high and low temperature cycling performance. The performance test results of each example and comparative example are shown in Table 2 and Table 3.

[0122] The testing methods for each performance aspect are as follows: Initial thermal conductivity (W / (m·K)): GB / T 10294-2008 "Determination of steady-state thermal resistance and related properties of thermal insulation materials - protective hot plate method", Class I rigid foam requires an initial thermal conductivity (average temperature 10℃) of ≤0.0205W / (m·K); 10% deformation compressive stress (kPa): Tested according to GB / T 8813-2020, the compressive stress (minimum values ​​in the length, width and height directions) of the sample when it is 10% deformed, in kPa, which is used to reflect the structural stability of polyurethane foam. Class I rigid foam requires ≥130kPa. Low-temperature dimensional stability (%): The test was conducted according to GB / T 8811-2008 Test Method for Dimensional Stability of Rigid Foamed Plastics. The test conditions were -30±2℃ and 24h. For Class I rigid foam, the low-temperature dimensional change rate was required to be ≤1.0%. Dimensional stability under damp heat (%): The test was conducted according to GB / T 8811-2008 Test Method for Dimensional Stability of Rigid Foamed Plastics. The test conditions were: temperature 70±2℃, relative humidity 95±5%, and time 24h. For Class I rigid foam, the dimensional change rate under damp heat should be ≤1.5%. Apparent core density (kg / m³) 3 According to GB / T 6343-2009, the requirement for Class I rigid polyurethane foam is ≤36 kg / m³. 3 ; Closed-cell rate (%): GB / T 10799-2008 "Determination of open-cell and closed-cell volume percentage of rigid foamed plastics", Class I rigid polyurethane foam requires a closed-cell rate of ≥90%; Water absorption rate: According to GB / T 8810-2005, it is determined by measuring the buoyancy of polyurethane foam after being submerged in water for 50 mm and 96 hours, and the unit is %, Class I rigid foam requires ≤4%; High and low temperature cycling performance: The high and low temperature cycling aging test is adopted. The polyurethane foam sample is placed in the high and low temperature alternating test chamber. The cycle is completed by keeping it at -30℃ for 4 hours and at 60℃ for 4 hours. After a total of 100 cycles, observe whether the foam is deformed, delaminated or cracked. If none of these are found, it is considered qualified.

[0123] Table 2. Performance test results of polyurethane foam in Examples 1-4

[0124] Table 3. Performance test results of polyurethane foams from Comparative Examples 1 to 7

[0125] As can be seen from Tables 2 and 3, From Examples 1 to 4, and Comparative Examples 3 (without self-foaming agent, using a sodium bicarbonate-added chemical foaming system) and 4 (a general formulation for commercially available isocyanate-based rigid polyurethane foam used in traditional refrigerators), it can be seen that the solution provided in this application can completely replace the external foaming solution and traditional rigid polyurethane foam. Through precise control of the polyurethane foam composition formulation and process, this application achieves a polyurethane foam with a closed-cell rate of up to 95.1%, an initial thermal conductivity as low as 0.0192 W / (m·K), a 10% deformation compressive stress as high as 185 kPa, and excellent high and low temperature dimensional stability. All core properties comprehensively exceed the requirements of Class I products in GB / T 26689-2024 national standard. Furthermore, the solution provided in this application also solves the problems of dependence on petroleum-based materials and solid waste pollution associated with rigid polyurethane foam.

[0126] Example 1 is the example with the optimal ratio and process parameters. It can be seen from Examples 1 and 4 that the addition of crosslinking agent can further improve the mechanical properties of polyurethane foam.

[0127] As can be seen from Examples 1 to 4 and Comparative Example 1, the polyurethane foam prepared from single carbonated soybean oil cannot meet the national standard requirements. This is because carbonated soybean oil only contains internal cyclic carbonates and lacks unsubstituted methylene groups. The nucleophilic attack of 3,6-dioxa-1,8-octanedithiol requires the structural characteristics of terminal cyclic carbonates. Therefore, carbonated soybean oil is inert in the S-alkylation self-foaming reaction. As can be seen from Examples 1 to 4 and Comparative Example 2, single butanediol bicyclic carbonate (functionality 2.0) can only form linear or low-crosslinked networks, with a compressive stress of less than 100 kPa, which cannot meet the national standard requirements. This demonstrates that the rigid framework of the three-dimensional crosslinked network provided by carbonated soybean oil is the core source of the system's mechanical strength.

[0128] Examples 1 to 4 and Comparative Example 5 show that the poor catalytic activity and selectivity of Comparative Example 5 lead to a mismatch between the foaming rate and gelation rate, resulting in a low closed-cell rate and high thermal conductivity in the polyurethane foam. Examples 1 to 4 and Comparative Example 6 show that excessively high functionality (trifunctionality, tetrafunctionality) of the self-foaming agent leads to a mismatch between the foaming rate and gelation rate, resulting in a low closed-cell rate and high thermal conductivity in the polyurethane foam. Examples 1 to 4 and Comparative Example 7 show that the closed-cell rate, apparent core density, dimensional stability, mechanical strength, and initial thermal conductivity of the polyurethane foam do not meet the requirements of Class I in the national standard. This indicates that using medium-high temperature prepolymers above 80℃ results in defects such as large viscosity fluctuations in the polyurethane prepolymer, uneven reaction, and easy collapse and merging of cells.

[0129] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A polyurethane foam composition, characterized in that, The polyurethane foam composition includes a polyurethane prepolymer mixture, which includes the polyurethane prepolymer. The polyurethane prepolymer is mainly obtained by aminolysis reaction of a cyclic carbonate composition and an amine curing agent. The cyclic carbonate composition includes carbonated soybean oil and butanediol bicyclic carbonate.

2. The polyurethane foam composition according to claim 1, characterized in that, The carbonated soybean oil is a multifunctional bio-based cyclic carbonate obtained by cycloaddition reaction of epoxidized soybean oil and carbon dioxide, and the average functionality of the carbonated soybean oil is 3.5 to 4.

0. The butanediol bicyclic carbonate is derived from bio-based 1,4-butanediol; The amine curing agent includes aliphatic amine curing agents, which include one or more of 1,4-butanediamine, diethylenetriamine, and triethylenetetramine. In the cyclic carbonate composition, the mass ratio of the carbonated soybean oil to the butanediol bicyclic carbonate is (3~7):(3~7). The ratio of the total molar number of amino groups in the amine curing agent to the total molar number of cyclic carbonates in the cyclic carbonate composition is (0.6~0.85):1; Based on 100 parts by weight of the cyclic carbonate composition, the amine curing agent comprises 22 to 42 parts by weight.

3. The polyurethane foam composition according to claim 1, characterized in that, The cyclic carbonate composition and the amine curing agent undergo an aminolysis reaction under the action of a catalyst; The catalyst includes an organic base catalyst, which includes one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene; The polyurethane prepolymer also includes a polyurethane prepolymer obtained by aminolysis reaction of a crosslinking agent and an amine curing agent; The crosslinking agent includes a cyclic carbonate crosslinking agent, wherein the functionality of the cyclic carbonate crosslinking agent is 3 to 8. Optionally, the crosslinking agent includes one or more of trimethylolpropane tricarbonate, glyceryl tricarbonate, and pentaerythritol tetraglycidyl ether carbonate; Based on 100 parts by mass of the cyclic carbonate composition, the catalyst comprises 2 to 7 parts by mass, and the crosslinking agent comprises 0 to 18 parts by mass.

4. The polyurethane foam composition according to claim 1, characterized in that, The polyurethane prepolymer mixture also includes fillers, foam stabilizers, and antioxidants; the fillers, foam stabilizers, and antioxidants are each independently dispersed in the polyurethane prepolymer. The filler includes inorganic nucleation-reinforcing filler, which includes one or more of diatomaceous earth and fumed silica. The foam leveling agent includes an organosilicon foam leveling agent, which includes one or more of rigid foam silicone oil AK8805, rigid foam silicone oil AK8809, rigid foam silicone oil AK8805, and Dow Corning DC5598. The antioxidant includes hindered phenolic antioxidants, and the hindered phenolic antioxidants include one or more of antioxidant 1010 and antioxidant 1076; Based on 100 parts by weight of the cyclic carbonate composition, the filler comprises 0.8 to 4.5 parts by weight, the foam leveler comprises 0.8 to 2.5 parts by weight, and the antioxidant comprises 0.2 to 0.8 parts by weight.

5. The polyurethane foam composition according to any one of claims 1 to 4, characterized in that, The number-average molecular weight of the polyurethane prepolymer is 1500 g / mol to 5000 g / mol; The viscosity of the polyurethane prepolymer mixture is 1500 mPa·s to 2500 mPa·s.

6. The polyurethane foam composition according to claim 1, characterized in that, The polyurethane foam composition further includes a self-foaming agent, which includes a difunctional thiol self-foaming agent. The molecular formula of the bifunctional thiol self-foaming agent is HS-R1-O-R2-SH or HS-R3-O-R4-O-R5-SH; wherein R1 and R2 are each independently selected from C1 to C2. 10 Alkylenes, R3, R4, and R5 are each independently selected from C1 to C5 alkylenes; Optionally, the self-foaming agent includes 3,6-dioxa-1,8-octanedithiol; The ratio of the total molar number of mercapto groups in the self-foaming agent to the total molar number of cyclic carbonates in the cyclic carbonate composition is (0.15~0.4):1; Based on 100 parts by weight of the cyclic carbonate composition, the self-foaming agent comprises 12 to 28 parts by weight.

7. A polyurethane foam, characterized in that, The polyurethane foam is prepared from the polyurethane foam composition according to any one of claims 1 to 6.

8. The polyurethane foam as described in claim 7, characterized in that, The initial thermal conductivity of the polyurethane foam is 0.0192 W / (m·K) to 0.0198 W / (m·K); The closed-cell rate of the polyurethane foam is ≥92%; The deformation compressive stress of the polyurethane foam is ≥130 kPa; The apparent core density of the polyurethane foam is ≤36 kg / m³. 3 ; The low-temperature dimensional stability of the polyurethane foam is ≤0.8%; The dimensional stability of the polyurethane foam under humid heat is ≤1.5%.

9. A method for preparing polyurethane foam, characterized in that, Includes the following steps: A mixture is provided; the mixture comprises a cyclic carbonate composition comprising carbonated soybean oil and butanediol bicyclic carbonate; An amine curing agent and a catalyst are added to the mixture to carry out an aminolysis reaction to obtain a polyurethane prepolymer mixture; the polyurethane prepolymer mixture and a self-foaming agent are mixed and injected into a mold for curing and aging to obtain polyurethane foam.

10. The method for preparing polyurethane foam as described in claim 9, characterized in that, The method for preparing the carbonated soybean oil includes the following steps: Epoxidized soybean oil undergoes a cycloaddition reaction with carbon dioxide to obtain the carbonated soybean oil; In the cycloaddition reaction process, the cycloaddition reaction catalyst used includes at least one of tetrabutylammonium iodide, tetrabutylammonium chloride, and lithium bromide; The mass ratio of the epoxidized soybean oil to the cycloaddition reaction catalyst is 100:(4~8). The pressure of the cycloaddition reaction is 2.0 MPa to 6.0 MPa, the reaction temperature is 110℃ to 150℃, and the reaction time is 12h to 36h.

11. The method for preparing polyurethane foam as described in claim 9, characterized in that, The mixture also includes fillers, foam stabilizers, and antioxidants; The provided mixture includes: The carbonated soybean oil, butanediol bicyclic carbonate, filler, foaming agent and antioxidant are mixed at 65℃~75℃ and stirred at 300 rpm~500 rpm for 15 min~30 min to obtain the mixture.

12. The method for preparing polyurethane foam according to claim 11, characterized in that, The provision of the mixture also includes: A crosslinking agent is added when the carbonated soybean oil, the butanediol bicyclic carbonate, the filler, the foaming agent, and the antioxidant are mixed. The crosslinking agent includes a cyclic carbonate crosslinking agent, wherein the functionality of the cyclic carbonate crosslinking agent is 3 to 8; Optionally, the crosslinking agent includes one or more of trimethylolpropane tricarbonate, glycerol tricarbonate, and pentaerythritol tetraglycidyl ether carbonate.

13. The method for preparing polyurethane foam as described in claim 9, characterized in that, The addition of an amine curing agent and a catalyst to the mixture for an aminolysis reaction includes: Under conditions of 65℃~75℃, an amine curing agent and a catalyst are added to the mixture, and the mixture is stirred at a speed of 300 rpm~500 rpm for 8 min~12 min to obtain the polyurethane prepolymer mixture, wherein the polyurethane prepolymer mixture includes the polyurethane prepolymer. The polyurethane prepolymer is mainly obtained by the cyclic carbonate composition and the amine curing agent under the action of the catalyst through an aminolysis reaction.

14. The method for preparing polyurethane foam as described in claim 9, characterized in that, The mixing speed of the polyurethane prepolymer mixture and the self-foaming agent is 900 rpm to 1100 rpm, and the mixing time of the polyurethane prepolymer mixture and the self-foaming agent is 1.5 min to 2.5 min. The temperature of the mold is 40~60℃; The curing temperature is 90~110℃, and the curing time is 15 min~25 min; The curing temperature is 90~110℃, and the curing time is 0.5 h~1.5 h.

15. A refrigeration device, characterized in that, The refrigeration equipment includes an insulation layer, which is made of polyurethane foam as described in claim 7 or 8, or polyurethane foam prepared by the method described in any one of claims 9 to 14.

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