A low voc polyurethane foam formulation and method of making same

Abstract

The application relates to the field of polyurethane foaming materials, and discloses a low-VOC polyurethane foaming compound and a preparation method thereof; the low-VOC polyurethane foaming compound comprises A component and B component which are mutually packed, the A component comprises low-aldehyde polyether polyol, polyether carbonate polyol, functionalized polyurethane oligomeric polyol, reactive tertiary amine catalyst, foam stabilizer and water, and the B component comprises a low-free-monomer isocyanate component; the functionalized polyurethane oligomeric polyol is prepared by reacting polyether carbonate polyol, diisocyanate and a hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups. The preparation method comprises the steps of functionalized polyurethane oligomeric polyol preparation, A component dispensing, B component dispensing and packing. By introducing the reactive oligomeric polyol with the 1,3-dicarbonyl structure into the foaming system, the volatile components brought by raw materials can be reduced, and the continuous control ability of aldehyde components in the foaming process and the post-maturation process can be improved.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam materials, specifically to a low-VOC polyurethane foam composite and its preparation method. Background Technology

[0002] Polyurethane foam materials are widely used in automotive interiors, furniture upholstery, thermal insulation layers, and sound-absorbing and insulating products. They are typically produced by foaming a mixture of polyol and isocyanate components. With increasingly stringent requirements for in-vehicle air quality, indoor environmental safety, and odor control in products, low-volatile organic compound (VOC) polyurethane foam compositions are gradually becoming an important development direction in this field.

[0003] In the prior art, in order to reduce the volatile organic compound content in polyurethane foam products, low-aldehyde polyether polyols, low free monomer isocyanate components, or small molecule aldehyde scavengers are usually used to reduce aldehyde impurities from the raw materials and small molecule volatiles from the isocyanate side.

[0004] However, in existing compound materials, low-aldehyde raw materials are mainly used to reduce the volatile components initially introduced, while the small-molecule aldehyde scavengers added later are usually in a free and dispersed state. During the mixing, foaming and post-curing process, they are prone to migration, uneven distribution or interference with the foaming system, making it difficult to continuously and stably control the aldehydes formed during the foaming process and the later stage of the product. As a result, the low volatile organic compound control effect of polyurethane foam products is unstable. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a low-VOC polyurethane foaming compound and its preparation method, thereby solving the technical problems existing in the prior art.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A low-VOC polyurethane foam composition, comprising: *Components A and B are packaged separately from each other; Component A comprises, by weight: 40-70 parts of low-aldehyde polyether polyol, 10-30 parts of polyether carbonate polyol, 2-12 parts of functionalized polyurethane oligomeric polyol, 0.1-1.0 parts of reactive tertiary amine catalyst, 0.3-1.5 parts of foam stabilizer, and 0.5-4.5 parts of water. The total content of formaldehyde, acetaldehyde and propionaldehyde in the low-aldehyde polyether polyol is no more than 300 mg / kg; The functionalized polyurethane oligomer is a hydroxyl-terminated polyurethane oligomer, which is prepared by reacting polyether carbonate polyol, diisocyanate and a hydroxy compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups. Its molecular chain contains 1,3-dicarbonyl side groups, and its hydroxyl value is 20-160 mgKOH / g, its number average molecular weight is 1000-6000, and its 1,3-dicarbonyl content is 0.2-3.0 mmol / g. Except for the functionalized polyurethane oligopolyol, component A does not contain small molecule aldehyde scavengers with a molecular weight of less than 500 and containing a 1,3-dicarbonyl structure; The B component is a low-free monomer isocyanate component, wherein the mass fraction of the total free isocyanate monomer content in the low-free monomer isocyanate component is not greater than 8%, and the low-free monomer isocyanate component is selected from one of modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate and isocyanate-terminated prepolymer, or is composed of two or three of modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate and isocyanate-terminated prepolymer; When component A and component B are mixed, a polyurethane foaming reaction occurs, forming a polyurethane foam.

[0007] Preferably, the low-aldehyde polyether polyol has a functionality of 2-3, a number-average molecular weight of 3000-6500, and a total content of formaldehyde, acetaldehyde, and propionaldehyde of no more than 200 mg / kg.

[0008] Preferably, the primary hydroxyl content of the polyether carbonate polyol is 45%-90%, and the polyether carbonate polyol is obtained by copolymerization of propylene oxide and carbon dioxide, or by copolymerization of propylene oxide, ethylene oxide and carbon dioxide.

[0009] Preferably, the hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups is selected from glycerol acetylation, trimethylolpropane acetylation, and pentaerythritol acetylation, or is composed of glycerol acetylation, trimethylolpropane acetylation, and pentaerythritol acetylation.

[0010] Preferably, component A further includes 5-20 parts of polymeric polyol and 0.5-4 parts of low-aldehyde chain extender or low-aldehyde crosslinking agent.

[0011] Preferably, the reactive tertiary amine catalyst is selected from dimethylethanolamine, methyldiethanolamine, triethanolamine and triisopropanolamine, or is composed of dimethylethanolamine, methyldiethanolamine, triethanolamine and triisopropanolamine; Component A further includes 0.03-0.25 parts of a metal catalyst, which is an organic bismuth catalyst or a zinc-based catalyst; The foam stabilizer is an organosilicon foam stabilizer.

[0012] Preferably, the mass fraction of the total free isocyanate monomer content in the low free monomer isocyanate component is not greater than 5%, and the isocyanate group content of the isocyanate-terminated prepolymer is 18%-28%.

[0013] Preferably, the isocyanate index of the mixture of component A and component B during foaming is 80-120.

[0014] A low-VOC polyurethane foam composition includes the following steps: S1: The polyether carbonate polyol used to prepare functionalized polyurethane oligomeric polyols is dehydrated to a moisture content of no more than 0.05%; S2: Under inert gas protection, the dehydrated polyether carbonate polyol is pre-reacted with diisocyanate to obtain an isocyanate-containing intermediate. Then, a hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups is added to continue the reaction to obtain a functionalized polyurethane oligopolyol. S3: Mix low-aldehyde polyether polyol, polyether carbonate polyol, functionalized polyurethane oligopolyol, reactive tertiary amine catalyst, foam stabilizer and water to obtain component A; S4: Mix one of the following: modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, and isocyanate-terminated prepolymer; or mix two or three of the following: modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, and isocyanate-terminated prepolymer to obtain component B. S5: Package component A and component B separately to obtain a low-volatile organic compound polyurethane foam composite.

[0015] Preferably, in step S2, the equivalence ratio of the total hydroxyl groups of the polyether carbonate polyol and hydroxyl compound to the isocyanate groups of the diisocyanate is 1.05-2.50:1, the reaction temperature is 50-90℃, and the reaction time is 1-6h. In step S3, after mixing, component A is subjected to vacuum devolatilization treatment at a temperature of 50-95℃, a vacuum degree of -0.06 to -0.098MPa, and a devolatilization time of 10-90min. In step S4, after component B is prepared, it undergoes depressurization to remove free monomers or thin-film evaporation to reduce the content of free isocyanate monomers. The isocyanate-terminated prepolymer in step S4 is prepared by reacting diisocyanate with polyol, and the isocyanate group content in the prepared isocyanate-terminated prepolymer is 18%-28%, and the mass fraction of the total free isocyanate monomer content is not greater than 5%.

[0016] In summary, the present invention has the following main beneficial effects: This application introduces a functionalized polyurethane oligomeric polyol into component A, and pre-reacts this functionalized polyurethane oligomeric polyol with polyether carbonate polyol, diisocyanate, and a hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups to form a reactive oligomeric polyol. This achieves the goal of stably introducing the 1,3-dicarbonyl structure into the polyurethane foaming system. The 1,3-dicarbonyl structure is not added to the system later as a small molecule aldehyde scavenger, but rather participates in the foaming reaction along with the functionalized polyurethane oligomeric polyol and is fixed in the foam network. This allows for in-situ control of aldehyde components in the system and avoids the problems of easy migration and precipitation of later-added small molecule aldehyde scavengers, as well as their adverse effects on the cell structure and product stability. This improves the sustainability of low-volatile organic compound control and the stability of the system structure.

[0017] By synergistically incorporating low-aldehyde polyether polyol, polyether carbonate polyol, and functionalized polyurethane oligomeric polyol into component A, the goal of reducing volatile organic compounds (VOCs) is achieved through three levels: source impurity control, reaction process structure adjustment, and network immobilization control. This allows the low-aldehyde polyether polyol to reduce the formaldehyde, acetaldehyde, and propionaldehyde load introduced from the raw materials; the polyether carbonate polyol to improve the system's reactivity and cell stability; and the functionalized polyurethane oligomeric polyol to continue in-situ control of aldehyde components that may form during the foaming and post-curing processes. Therefore, rather than relying solely on single raw material replacement or single additive adsorption to achieve low volatility, this approach further enhances the comprehensive control over total VOCs and aldehyde release while ensuring foaming feasibility, foam molding stability, and formulation compatibility.

[0018] By using a low-free-monomer isocyanate component as component B, and subjecting component A to vacuum devolatilization treatment, and component B to vacuum removal of free monomers or thin-film evaporation treatment, the aim is to simultaneously reduce the sources of volatility on both the component A and component B sides. This reduces the adverse effects of volatile small molecules in the raw materials before mixing, and maintains the required degree of crosslinking and foam structure during foaming through reasonable control of the isocyanate index. Thus, while reducing the risk of volatile organic compound release, the molding quality, structural uniformity, and stability of the foam products are also considered, thereby improving the applicability of the compound in the field of polyurethane foaming. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 refer to Figure 1 A low-VOC polyurethane foam composition, comprising: Component A and Component B are packaged separately from each other; Component A comprises, by weight: 40-70 parts of low-aldehyde polyether polyol, 10-30 parts of polyether carbonate polyol, 2-12 parts of functionalized polyurethane oligomeric polyol, 0.1-1.0 parts of reactive tertiary amine catalyst, 0.3-1.5 parts of foam stabilizer, and 0.5-4.5 parts of water. The total content of formaldehyde, acetaldehyde and propionaldehyde in the low-aldehyde polyether polyol is no more than 300 mg / kg; The functionalized polyurethane oligomer is a hydroxyl-terminated polyurethane oligomer, which is prepared by reacting polyether carbonate polyol, diisocyanate and a hydroxy compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups. Its molecular chain contains 1,3-dicarbonyl side groups, and its hydroxyl value is 20-160 mgKOH / g, its number average molecular weight is 1000-6000, and its 1,3-dicarbonyl content is 0.2-3.0 mmol / g. Except for the functionalized polyurethane oligopolyol, component A does not contain small molecule aldehyde scavengers with a molecular weight of less than 500 and containing a 1,3-dicarbonyl structure; The B component is a low-free monomer isocyanate component, wherein the mass fraction of the total free isocyanate monomer content in the low-free monomer isocyanate component is not greater than 8%, and the low-free monomer isocyanate component is selected from one of modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate and isocyanate-terminated prepolymer, or is composed of two or three of modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate and isocyanate-terminated prepolymer; When component A and component B are mixed, a polyurethane foaming reaction occurs, forming a polyurethane foam.

[0022] The core of this application lies in: pre-preparing a functionalized polyurethane oligomeric polyol and introducing this functionalized polyurethane oligomeric polyol as one of the reactive polyol components in component A of the polyurethane foaming system. The functionalized polyurethane oligomeric polyol is not a small-molecule aldehyde scavenger added later in component A, nor is it a simple polyether carbonate polyol, but rather a hydroxyl-terminated polyurethane oligomer prepared by reacting polyether carbonate polyol, diisocyanate, and a hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups. This oligomer incorporates a 1,3-dicarbonyl structure into its molecular structure and retains hydroxyl groups at the molecular ends that can react with isocyanate. Therefore, it can participate in the subsequent polyurethane foaming reaction and maintain the 1,3-dicarbonyl structure in the final foam network, thereby achieving in-situ control of the aldehyde components in the system.

[0023] The low-aldehyde polyether polyol in this application refers to a polyether polyol whose total content of formaldehyde, acetaldehyde, and propionaldehyde is not greater than 300 mg / kg when the polyether polyol raw material itself is tested. The total content is calculated using the following formula: in, Total aldehyde content, in mg / kg; Formaldehyde content, in mg / kg; This represents the acetaldehyde content, expressed in mg / kg. The content is propionaldehyde, expressed in mg / kg.

[0024] The formaldehyde, acetaldehyde, and propionaldehyde contents are preferably determined by headspace gas chromatography and quantified according to their respective standard curves. The total aldehyde content in the low-aldehyde polyether polyol is limited to no more than 300 mg / kg because when the total aldehyde content is higher than this value, the aldehyde load introduced into the system by the raw materials themselves is high, which is not conducive to the subsequent overall low volatile organic compound control; preferably no more than 200 mg / kg, in order to further reduce the impact of the raw materials, while taking into account the availability and cost of the raw materials.

[0025] The polyether carbonate polyol in this application refers to a polyol obtained by copolymerizing propylene oxide with carbon dioxide, or by copolymerizing propylene oxide, ethylene oxide, and carbon dioxide. The primary hydroxyl content of the polyether carbonate polyol is 45%-90%. The primary hydroxyl content is preferably determined by nuclear magnetic resonance (NMR) and calculated by integrating the peaks corresponding to primary hydroxyl groups with the peaks related to total hydroxyl groups. The primary hydroxyl content is limited to 45%-90% because below 45%, the reactivity is insufficient, making it difficult to balance the foaming reaction rate and cell stability; above 90%, the selection of raw materials is limited, and the difficulty in controlling system viscosity and cost increases, limiting further improvement.

[0026] The functionalized polyurethane oligomer polyol in this application refers to a hydroxyl-terminated polyurethane oligomer prepared by reacting polyether carbonate polyol, diisocyanate, and a hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups. The functionalized polyurethane oligomer polyol has a hydroxyl value of 20-160 mg KOH / g, a number-average molecular weight of 1000-6000, and a 1,3-dicarbonyl structure content of 0.2-3.0 mmol / g. The hydroxyl value is preferably determined by hydroxyl titration, the number-average molecular weight is preferably determined by gel permeation chromatography, the dynamic viscosity at 25°C is preferably determined by rotational viscometer at 25°C, and the 1,3-dicarbonyl structure content is preferably determined by nuclear magnetic resonance.

[0027] The hydroxyl value is limited to 20-160 mg KOH / g because when the hydroxyl value is below 20 mg KOH / g, the reactivity is low, which is not conducive to its stable introduction into the polyurethane network; when the hydroxyl value is above 160 mg KOH / g, the corresponding molecular weight is low or the active sites are too dense, which easily leads to difficulties in controlling the crosslinking density and viscosity of the system.

[0028] The number average molecular weight is limited to 1000-6000 because when the number average molecular weight is below 1000, it is closer to a low molecular weight reactive additive, which is not conducive to reflecting the characteristics of oligomeric polyols; when it is above 6000, the mixing uniformity and reaction control become more difficult.

[0029] The 1,3-dicarbonyl structure content is limited to 0.2-3.0 mmol / g because when it is below 0.2 mmol / g, there are insufficient structural sites available per unit mass of material; when it is above 3.0 mmol / g, the degree of acetylation is too high, which may lead to a decrease in the number of effective hydroxyl groups, affecting the subsequent polyurethane reaction and system compatibility.

[0030] The hydroxyl compounds containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups in this application are preferably partially acetylated products of polyols, retaining two or more hydroxyl groups capable of reacting with isocyanates after acetylation. Preferably, the hydroxyl compounds are selected from one of glycerol acetylated compounds, trimethylolpropane acetylated compounds, and pentaerythritol acetylated compounds, or composed of two or three of them.

[0031] The low free isocyanate monomer component in this application refers to an isocyanate component with a total free isocyanate monomer content of no more than 8% by mass, preferably no more than 5%. The total free isocyanate monomer content refers to the sum of the mass contents of each free isocyanate monomer in component B, preferably determined by chromatography. The isocyanate group content is preferably determined by chemical titration. The total free isocyanate monomer content is limited to no more than 8% because when it exceeds this value, the volatility of component B itself increases significantly, which is detrimental to overall low volatile organic compound (VOC) control; preferably no more than 5%, to further reduce the volatile components from component B. The isocyanate group content of the isocyanate-terminated prepolymer is limited to 18%-28% because when it is below 18%, the foaming reaction activity is insufficient; when it is above 28%, the difficulty of controlling free monomers increases, which is detrimental to overall low VOC control.

[0032] The reactive tertiary amine catalyst in this application refers to a tertiary amine compound containing a tertiary amine group and a hydroxyl group that can participate in the polyurethane reaction. Preferably, the reactive tertiary amine catalyst is selected from one of dimethylethanolamine, methyldiethanolamine, triethanolamine, and triisopropanolamine, or composed of two, three, or four of them.

[0033] The low-aldehyde chain extender or low-aldehyde crosslinking agent in this application refers to a chain extender or crosslinking agent whose total content of formaldehyde, acetaldehyde, and propionaldehyde is no more than 200 mg / kg. This limitation is intended to avoid reintroducing high levels of aldehyde impurities through the chain extender or crosslinking agent.

[0034] First, the polyether carbonate polyol used to prepare functionalized polyurethane oligomeric polyols is dehydrated. The preferred dehydration conditions are 90-110℃ and a vacuum of -0.08 to -0.098 MPa, until the moisture content is no more than 0.05%. This upper limit is set because if the moisture content is too high, side reactions are likely to occur during the reaction with diisocyanate, leading to uncontrolled molecular weight distribution and difficulty in controlling the residual isocyanate group content.

[0035] After dehydration, the polyether carbonate polyol and diisocyanate are subjected to a first-stage pre-reaction under inert gas protection to obtain an isocyanate-containing intermediate. In the first stage, the equivalence ratio of isocyanate groups to hydroxyl groups is preferably controlled at 1.02-1.30:1, the reaction temperature is preferably 50-80℃, and the holding time is preferably 0.5-3 hours. Setting the lower limit of the equivalence ratio at 1.02:1 ensures the formation of a sufficient amount of isocyanate-containing intermediate; setting the upper limit at 1.30:1 avoids excessive residual isocyanate groups in the system, which would make it difficult to stably obtain hydroxyl-terminated oligomers subsequently.

[0036] Subsequently, a hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups is added to the aforementioned isocyanate-containing intermediate for a second-stage reaction. In the second stage, the equivalence ratio of total hydroxyl groups to total isocyanate groups is preferably 1.05-2.50:1, the reaction temperature is preferably 50-90°C, and the reaction time is preferably 1-6 hours, until the residual isocyanate group content drops below 0.2%. Setting the lower limit of the equivalence ratio of total hydroxyl groups to total isocyanate groups at 1.05:1 ensures that a hydroxyl-terminated product is obtained; setting the upper limit at 2.50:1 avoids excessive unreacted hydroxyl groups, which would be detrimental to product composition stability.

[0037] This yields a functionalized polyurethane oligopolyol. This oligopolyol is not a small-molecule aldehyde scavenger added later in component A, but rather a pre-prepared reactive oligopolyol. Its hydroxyl groups can participate in the construction of the polyurethane network during subsequent foaming, and its 1,3-dicarbonyl structure can be retained in the network, thus possessing both reactivity and in-situ structural control capabilities.

[0038] First, add low-aldehyde polyether polyol, polyether carbonate polyol and functionalized polyurethane oligomeric polyol to a stirring container and stir and mix at 20-40℃ to obtain a preliminary mixture.

[0039] Add a reactive tertiary amine catalyst, a foam stabilizer, and water to the initial mixture; if necessary, polymeric polyols, low-aldehyde chain extenders or low-aldehyde crosslinking agents, and metal catalysts may also be added. Continue stirring until a homogeneous liquid phase is formed.

[0040] The resulting mixture is then subjected to vacuum devolatilization treatment. The devolatilization temperature is preferably 50-95℃, the vacuum degree is preferably -0.06 to -0.098MPa, and the devolatilization time is preferably 10-90min. After cooling, component A is obtained.

[0041] Setting the lower limit of the devolatilization temperature to 50℃ is to ensure devolatilization efficiency; setting the upper limit to 95℃ is to avoid difficulty in controlling the stability and storage safety of some formulation components. Setting the lower limit of the devolatilization time to 10 minutes is to avoid insufficient devolatilization; setting the upper limit to 90 minutes is to balance process efficiency.

[0042] In this application, apart from the functionalized polyurethane oligomeric polyol, no small molecule aldehyde scavengers with a molecular weight less than 500 and containing a 1,3-dicarbonyl structure are introduced into component A. This clearly distinguishes this application from the route that adds small molecule aldehyde scavengers later.

[0043] Component B is preferably composed of one of the following: modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, and isocyanate-terminated prepolymer, or a mixture of two or three of them.

[0044] The isocyanate-terminated prepolymer can be prepared by reacting diisocyanate with a polyol. Preferably, the polyol is first dehydrated to a moisture content of no more than 0.05%, and then reacted with diisocyanate under an inert atmosphere until the isocyanate-terminated prepolymer is obtained. The isocyanate group content of the isocyanate-terminated prepolymer is preferably 18%-28%.

[0045] After the preparation of component B is completed, it is preferable to perform depressurization to remove free monomers or thin-film evaporation to ensure that the total mass fraction of free isocyanate monomers is not greater than 8%, preferably not greater than 5%, so as to obtain a low free monomer isocyanate component.

[0046] Component A and Component B should be mixed and foamed according to an isocyanate index of 80-120. The isocyanate index is calculated using the following formula: in, The isocyanate index; The total equivalent number of isocyanate groups in component B; This represents the total equivalent number of active hydrogen atoms in component A that can react with isocyanates. Among them, in, For the first The mass of the isocyanate component, in grams; For the first The mass fraction of isocyanate groups in a component containing isocyanate; 42 is the equivalent mass of isocyanate groups.

[0047] in, For the first The mass of a hydroxyl-containing component, in grams; For the first The hydroxyl value of a hydroxyl-containing component, expressed in mgKOH / g; 56100 is the mass of water in grams; 18 is the hydroxyl value conversion constant; and 18 is the molecular weight of water.

[0048] The isocyanate index is limited to 80-120 because when it is below 80, the system is not cross-linked enough and the foam structure is not stable; when it is above 120, the risk of residual isocyanate increases, which is not conducive to foam flexibility and low volatile organic compound control.

[0049] Example 2 A method for preparing a low-VOC polyurethane foam composition includes the following steps: S1. The polyether carbonate polyol used to prepare functionalized polyurethane oligomeric polyols is dehydrated to a moisture content of no more than 0.05%; S2. Under inert gas protection, the dehydrated polyether carbonate polyol is pre-reacted with diisocyanate to obtain an isocyanate-containing intermediate. Then, a hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups is added to continue the reaction to obtain a functionalized polyurethane oligomeric polyol. S3. Mix low-aldehyde polyether polyol, polyether carbonate polyol, functionalized polyurethane oligopolyol, reactive tertiary amine catalyst, foam stabilizer and water to obtain component A. S4. Mix one of the following: modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, and isocyanate-terminated prepolymer; or mix two or three of the following: modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, and isocyanate-terminated prepolymer, to obtain component B. S5. Package component A and component B separately to obtain a low-volatile organic compound polyurethane foam composite.

[0050] In step S2, the equivalence ratio of the total hydroxyl groups of the polyether carbonate polyol and hydroxyl compound to the isocyanate groups of the diisocyanate is 1.05-2.50:1, the reaction temperature is 50-90℃, and the reaction time is 1-6h. In step S3, after mixing, component A is subjected to vacuum devolatilization treatment at a temperature of 50-95℃, a vacuum degree of -0.06 to -0.098MPa, and a devolatilization time of 10-90min. In step S4, after component B is prepared, it undergoes depressurization to remove free monomers or thin-film evaporation to reduce the content of free isocyanate monomers. The isocyanate-terminated prepolymer in step S4 is prepared by reacting diisocyanate with polyol, and the isocyanate group content in the prepared isocyanate-terminated prepolymer is 18%-28%, and the mass fraction of the total free isocyanate monomer content is not greater than 5%.

[0051] Example 3 A polyether carbonate polyol was selected as the starting polyol, with its primary hydroxyl content controlled within the range of 45%-90%. It was first dehydrated under reduced pressure at 100℃ to ensure a moisture content of no more than 0.05%.

[0052] Under nitrogen protection, the dehydrated polyether carbonate polyol and diphenylmethane diisocyanate were subjected to a first-stage pre-reaction, with the equivalent ratio of isocyanate groups to hydroxyl groups being 1.10:1. The reaction was carried out at 70°C for 1.5 h to obtain an isocyanate-containing intermediate.

[0053] Trimethylolpropane acetylated compound was then added to the intermediate to make the total hydroxyl group to total isocyanate group equivalent ratio 1.40:1. The reaction was continued at 65°C for 2 hours until the residual isocyanate group content dropped to below 0.2%, thus obtaining functionalized polyurethane oligomeric polyol.

[0054] The obtained functionalized polyurethane oligomeric polyols were tested, and their hydroxyl value, number-average molecular weight, dynamic viscosity at 25°C, and 1,3-dicarbonyl content were determined using the methods described above. The results showed that the obtained functionalized polyurethane oligomeric polyols had hydroxyl values ​​ranging from 20 to 160 mg KOH / g, number-average molecular weights ranging from 1000 to 6000, and 1,3-dicarbonyl content ranging from 0.2 to 3.0 mmol / g. Furthermore, they exhibited flowability at 25°C that met the requirements for mixing and foaming applications.

[0055] By weight, take 55 parts of low-aldehyde polyether polyol, 18 parts of polyether carbonate polyol, 8 parts of functionalized polyurethane oligomeric polyol, 10 parts of polymer polyol, 0.4 parts of reactive tertiary amine catalyst, 0.9 parts of foam stabilizer, 3.5 parts of water, 0.08 parts of metal catalyst, and 1.5 parts of low-aldehyde crosslinking agent.

[0056] First, mix low-aldehyde polyether polyol, polyether carbonate polyol and functionalized polyurethane oligomeric polyol, then add polymer polyol, reactive tertiary amine catalyst, foam stabilizer, water, metal catalyst and low-aldehyde crosslinking agent in sequence, and stir until uniform.

[0057] The resulting mixture was subjected to vacuum devolatilization at 70°C for 30 min, and after cooling, component A was obtained.

[0058] The low-aldehyde polyether polyol raw materials used were tested, and the test results showed that the total content of formaldehyde, acetaldehyde and propionaldehyde was not greater than 300 mg / kg, preferably not greater than 200 mg / kg, which meets the requirements of this application for low-aldehyde polyether polyols.

[0059] In this embodiment, no small molecule aldehyde scavenger with a molecular weight of less than 500 and containing a 1,3-dicarbonyl structure is added to component A.

[0060] By weight, 60 parts of modified diphenylmethane diisocyanate, 25 parts of polymeric diphenylmethane diisocyanate, and 15 parts of isocyanate-terminated prepolymer were mixed evenly and then subjected to depressurization to remove free monomers so that the total content of free isocyanate monomers was not greater than 5%, thus obtaining component B.

[0061] The results of the test on component B showed that the total content of free isocyanate monomers was no more than 5%, and the content of isocyanate groups was in the range of 18%-28%.

[0062] The components A and B are mixed at high speed at 25°C according to the isocyanate index of 100, and then injected into the mold. After foaming and curing, the mixture is demolded and then cured at 60°C for 4 hours to obtain polyurethane foam.

[0063] In this embodiment, low-aldehyde polyether polyol is used to reduce aldehydes introduced from the raw materials themselves, polyether carbonate polyol is used to improve reactivity and system stability, functionalized polyurethane oligomeric polyol is used to introduce reactive and fixed 1,3-dicarbonyl structures into the final foam network, and low-free monomer isocyanate component is used to reduce volatile components from component B. These components are not simply parallel; rather, they each play a role in source control, structural control, and network fixation control, respectively.

[0064] Example 4 The difference between this embodiment and Example 1 is that the hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups used to prepare the functionalized polyurethane oligopolyol is replaced with a glycerol acetylated compound; the amount of functionalized polyurethane oligopolyol in component A is 4 parts, the amount of polyether carbonate polyol is 25 parts, and the amount of low-aldehyde polyether polyol is 50 parts. The remaining preparation methods and detection methods are the same as in Example 1.

[0065] This embodiment shows that even with a low amount of functionalized polyurethane oligopolyol and a high amount of polyether carbonate polyol, the proposed solution can still be implemented and maintains the core technical logic of pre-prepared reactive oligopolyols playing a structural introduction role.

[0066] Example 5 The difference between this embodiment and Example 1 is that the hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups used to prepare functionalized polyurethane oligomeric polyols is replaced with pentaerythritol acetylated compound; component B consists of modified diphenylmethane diisocyanate and isocyanate-terminated prepolymer. The remaining preparation methods and detection methods are the same as in Example 1.

[0067] This embodiment shows that even when the composition of component B changes, the technical solution of this application can still be implemented as long as the limitation of low free monomer isocyanate component is still met.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-VOC polyurethane foam composite material, characterized in that, include: Component A and Component B are packaged separately from each other; Component A comprises, by weight: 40-70 parts of low-aldehyde polyether polyol, 10-30 parts of polyether carbonate polyol, 2-12 parts of functionalized polyurethane oligomeric polyol, 0.1-1.0 parts of reactive tertiary amine catalyst, 0.3-1.5 parts of foam stabilizer, and 0.5-4.5 parts of water. The total content of formaldehyde, acetaldehyde and propionaldehyde in the low-aldehyde polyether polyol is no more than 300 mg / kg; The functionalized polyurethane oligomer is a hydroxyl-terminated polyurethane oligomer, which is prepared by reacting polyether carbonate polyol, diisocyanate and a hydroxy compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups. Its molecular chain contains 1,3-dicarbonyl side groups, and its hydroxyl value is 20-160 mgKOH / g, its number average molecular weight is 1000-6000, and its 1,3-dicarbonyl content is 0.2-3.0 mmol / g. Except for the functionalized polyurethane oligopolyol, component A does not contain small molecule aldehyde scavengers with a molecular weight of less than 500 and containing a 1,3-dicarbonyl structure; The B component is a low-free monomer isocyanate component, wherein the mass fraction of the total free isocyanate monomer content in the low-free monomer isocyanate component is not greater than 8%, and the low-free monomer isocyanate component is selected from one of modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate and isocyanate-terminated prepolymer, or is composed of two or three of modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate and isocyanate-terminated prepolymer; When component A and component B are mixed, a polyurethane foaming reaction occurs, forming a polyurethane foam.

2. The low-VOC polyurethane foam composite material according to claim 1, characterized in that, The low-aldehyde polyether polyol has a functionality of 2-3, a number-average molecular weight of 3000-6500, and a total content of formaldehyde, acetaldehyde, and propionaldehyde of no more than 200 mg / kg.

3. The low-VOC polyurethane foam composite material according to claim 2, characterized in that, The primary hydroxyl content of the polyether carbonate polyol is 45%-90%, and the polyether carbonate polyol is obtained by copolymerization of propylene oxide and carbon dioxide, or by copolymerization of propylene oxide, ethylene oxide and carbon dioxide.

4. The low-VOC polyurethane foam composite material according to claim 3, characterized in that, The hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups is selected from glycerol acetylation, trimethylolpropane acetylation, and pentaerythritol acetylation, or is composed of glycerol acetylation, trimethylolpropane acetylation, and pentaerythritol acetylation.

5. The low-VOC polyurethane foam composite material according to claim 4, characterized in that, Component A further includes 5-20 parts of polymeric polyol and 0.5-4 parts of low-aldehyde chain extender or low-aldehyde crosslinking agent.

6. The low-VOC polyurethane foam composite material according to claim 5, characterized in that, The reactive tertiary amine catalyst is selected from dimethylethanolamine, methyldiethanolamine, triethanolamine and triisopropanolamine, or is composed of dimethylethanolamine, methyldiethanolamine, triethanolamine and triisopropanolamine; Component A further includes 0.03-0.25 parts of a metal catalyst, which is an organic bismuth catalyst or a zinc-based catalyst; The foam stabilizer is an organosilicon foam stabilizer.

7. The low-VOC polyurethane foam composite material according to claim 6, characterized in that, The mass fraction of the total free isocyanate monomer content in the low free monomer isocyanate component is no more than 5%, and the isocyanate group content of the isocyanate-terminated prepolymer is 18%-28%.

8. The low-VOC polyurethane foam composite material according to claim 7, characterized in that, The isocyanate index of the mixture of component A and component B during foaming is 80-120.

9. A method for preparing a low-VOC polyurethane foam composition is applicable to the low-VOC polyurethane foam composition according to any one of claims 1-7, characterized in that, Includes the following steps: S1: The polyether carbonate polyol used to prepare functionalized polyurethane oligomeric polyols is dehydrated to a moisture content of no more than 0.05%; S2: Under inert gas protection, the dehydrated polyether carbonate polyol is pre-reacted with diisocyanate to obtain an isocyanate-containing intermediate. Then, a hydroxyl compound containing a 1,3-dicarbonyl structure and having two or more hydroxyl groups is added to continue the reaction to obtain a functionalized polyurethane oligopolyol. S3: Mix low-aldehyde polyether polyol, polyether carbonate polyol, functionalized polyurethane oligopolyol, reactive tertiary amine catalyst, foam stabilizer and water to obtain component A; S4: Mix one of the following: modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, and isocyanate-terminated prepolymer; or mix two or three of the following: modified diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, and isocyanate-terminated prepolymer to obtain component B. S5: Package component A and component B separately to obtain a low-volatile organic compound polyurethane foam composite.

10. The method for preparing a low-VOC polyurethane foam composition according to claim 9, characterized in that, In step S2, the equivalence ratio of the total hydroxyl groups of the polyether carbonate polyol and hydroxyl compound to the isocyanate groups of the diisocyanate is 1.05-2.50:1, the reaction temperature is 50-90℃, and the reaction time is 1-6h. In step S3, after mixing, component A is subjected to vacuum devolatilization treatment at a temperature of 50-95℃, a vacuum degree of -0.06 to -0.098MPa, and a devolatilization time of 10-90min. In step S4, after component B is prepared, it undergoes depressurization to remove free monomers or thin-film evaporation to reduce the content of free isocyanate monomers. The isocyanate-terminated prepolymer in step S4 is prepared by reacting diisocyanate with polyol, and the isocyanate group content in the prepared isocyanate-terminated prepolymer is 18%-28%, and the mass fraction of the total free isocyanate monomer content is not greater than 5%.

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