Bio-based polyurethane foam formulations and methods for their production

Abstract

The present disclosure relates to a bio-based polyurethane foam formulation comprising: a polyol component comprising 50 to 90 weight percent of one or more bio-based polyols derived from renewable resources; an isocyanate component comprising 40 to 70 weight percent of one or more isocyanates; one or more optional additives selected from nucleating agents, surfactants, cell stabilizers, chain extenders, crosslinkers, and bio-fillers; a catalyst system comprising a gelling catalyst and / or a blowing catalyst; a blowing agent system comprising a chemical blowing agent and / or a physical blowing agent. All weight percents are based on the total formulation. The bio-based polyurethane foam has a predetermined thermal decomposition temperature, a predetermined tensile strength, and a predetermined elongation at break.

Description

Technical Field

[0001] This invention relates to the fields of materials science and polymer-based formulations, specifically to a bio-based polyurethane foam formulation and its production method to achieve high heat resistance. Background Technology

[0002] This disclosure describes a bio-based polyurethane foam formulation and related preparation methods aimed at achieving high renewable content while maintaining robust mechanical and structural properties, such as high heat resistance. The invention integrates a controlled combination of bio-based polyols derived from renewable resources with isocyanate components, additives, catalysts, blowing agents, chain extenders, crosslinking agents, and bio-based fillers. The formulation includes one or more bio-fillers and incorporates nanonucleating agents to improve foam pore size control and morphological stability, while using environmentally friendly blowing agents, such as water and acetone. The preparation method utilizes controlled high-shear mixing and defined thermal conditions to form a uniform open-cell foam structure. The resulting polyurethane foam exhibits fine cell morphology, enhanced compression and tensile properties, improved elongation, high bio-based carbon content, and high heat resistance, enabling the foam to maintain structural integrity and mechanical properties after exposure to high temperatures and heat-based post-processing (including hot pressing), and exhibiting a decomposition temperature of at least 260°C. This disclosure addresses the thermal limitations of bio-based foams while maintaining compatibility with conventional polyurethane processing equipment and industrial manufacturing practices. Foam materials support applications that require lightweight structures, elasticity, durability, and reduced environmental impact.

[0003] Existing bio-based polyurethane foam technologies heavily rely on partially replacing fossil-based polyols with renewable polyols, resulting in formulations exhibiting limited total bio-based content. These systems maintain a dependence on fossil-based components to preserve mechanical integrity and thermal stability. Foam structures exhibit trade-offs in compressive strength, reduced tensile properties, and inconsistent cell morphology. This reliance on conventional formulations limits sustainable development while continuing to impose an environmental burden. These materials remain unsuitable for demanding applications requiring both performance and renewable content. The lack of holistic formulation design and low heat resistance limit broader industrial applications because the foams cannot maintain structural and mechanical integrity during heat-based molding processes, including thermoforming.

[0004] Another drawback of existing inventions is the insufficient control over the foaming reaction and cell nucleation behavior. Many conventional systems use only chemical foaming agents, leading to uncontrolled gas escape and irregular pore formation. The resulting foam exhibits uneven large pore sizes and lower open-cell content. Mechanical properties deteriorate due to structural defects in the foam matrix, particularly due to low heat resistance, which leads to degradation of the foam structure and reduction in mechanical properties after heating or hot pressing. Processing reproducibility is affected under large-scale production conditions. The lack of a synergistic nucleation strategy prevents consistent foam quality.

[0005] Another drawback of current polyurethane foam technology stems from the continued use of toxic and environmentally harmful catalysts. Tin-based catalysts remain prevalent in many existing formulations. These catalysts pose health hazards, environmental pollution, and regulatory challenges. The manufacturing environment faces increasing safety requirements and disposal complexities. As regulations evolve, sustainability compliance becomes increasingly difficult. This continued reliance on such catalysts limits the long-term viability of existing polyurethane foam solutions.

[0006] CN107151302B describes a method for preparing vegetable oil-based flexible polyurethane foam derived from tung oil polyols and related renewable raw materials. This disclosure aims to produce biodegradable and environmentally friendly foam materials via vegetable oil modification. However, compared to petroleum-based polyurethane foams, the resulting polyurethane foam exhibits significantly reduced tensile strength, elongation, and compressive properties. The formulation strategy relies primarily on renewable polyol substitution without addressing structural reinforcement of the foam matrix. The foam morphology shows limited control over pore size uniformity and open-cell consistency. Mechanical defects limit the use of this foam in applications requiring durability, elasticity, and load-bearing capacity.

[0007] CN117487114A describes a corn gluten-modified bio-based polyurethane flexible foam material, which addresses foaming stability and cell uniformity through protein-based modification. This disclosure aims to improve foam structure and elasticity by introducing corn gluten as a modifier. However, the prior art does not quantify or ensure the total bio-based carbon content of the final foam material. The lack of a clear renewable content metric limits sustainability assessment and regulatory consistency. The approach does not strike a balance between high renewable content and mechanical reinforcement. Industrial scalability and performance reproducibility remain insufficiently addressed.

[0008] CN116425947A describes a highly resilient bio-based polyurethane flexible foam and a corresponding preparation method aimed at improving its resilience. This disclosure achieves enhanced resilience comparable to petroleum-based foams. However, the formulation limits the amount of bio-based polyols to approximately 50% by weight. Therefore, the total bio-based carbon content remains below the sustainability threshold of over 80%. The solution prioritizes resilience over optimizing the renewable content. This limitation restricts its applicability in markets demanding high performance and high renewable material content.

[0009] US9212250B2 describes a polyurethane foam system incorporating bio-based polyols while aiming to maintain acceptable mechanical properties. This disclosure addresses the formulation balancing issues associated with renewable polyols. However, this method has not demonstrated fine control over open-cell morphology at high levels of renewable content. Existing technologies do not integrate nanoscale biofillers or synergistic treatment strategies. In addressing the combined challenges of sustainability and performance, the solutions remain incremental rather than transformative.

[0010] US12258435B1 describes a tin-free catalyst system for the production of polyurethane foam and aims to improve the environment and health by replacing tin-based catalysts. While this disclosure improves catalyst sustainability, it does not address the broader formulation challenges associated with achieving very high bio-based content and fine foam morphology. Prior art does not address the mechanical degradation associated with highly bio-based formulations. Prior art further addresses the heat resistance achieved using polyisocyanurate (PIR), but this is achieved by increasing the isocyanate content, resulting in rigid, brittle foams with lower bio-based content and poorer mechanical balance. In contrast, the present invention achieves high heat resistance while maintaining high bio-based content, high elongation, and excellent morphological stability.

[0011] This disclosure provides a universal solution that addresses the persistent limitations related to sustainability, mechanical properties, and foam morphology identified in the prior art. The solution integrates material selection, filler incorporation, blowing agent strategies, and processing controls into a unified formulation and preparation method. This integrated approach resolves the disconnect between renewable content, mechanical integrity, and thermal stability present in previous disclosures. The solution emphasizes structural consistency, controls cell formation, strengthens the polymer network, while maintaining a high proportion of renewable carbon content. The universal solution overcomes the drawbacks associated with weak mechanical properties, inconsistent pore structures, and limited sustainability metrics characteristic of the prior art.

[0012] This disclosure also provides a solution that combines environmental responsibility with industrial applicability by improving thermal stability. The solution reduces reliance on hazardous components while improving the reproducibility and scalability of foam production. This approach supports compatibility with existing manufacturing equipment and processes, thereby facilitating use without significant infrastructure changes. This solution enables the production of polyurethane foams to achieve a performance balance between mechanical strength, elasticity, morphology, and sustainability. This universal solution framework addresses the shortcomings of existing technologies by advancing a holistic and integrated strategy rather than isolated material substitutions or incremental process changes. Summary of the Invention

[0013] This invention relates to a bio-based polyurethane foam formulation. The formulation includes a polyol component comprising 50 to 90 weight percent of one or more bio-based polyols derived from renewable resources. The formulation also includes an isocyanate component comprising 40 to 70 weight percent of one or more isocyanates. The formulation further includes one or more optional additives selected from nucleating agents, surfactants, cell-opening stabilizers, chain extenders, and biofillers. The formulation also includes a catalyst system, including a gelling catalyst and / or a foaming catalyst. The formulation further includes a foaming agent system, including a chemical foaming agent and / or a physical foaming agent, wherein all weight percentages are based on the total formulation. The bio-based polyurethane foam has a predetermined thermal decomposition temperature, a predetermined tensile strength, and a predetermined elongation at break.

[0014] According to embodiments of the present invention, the bio-based polyol is selected from polyester polyols, polyether polyols, or combinations thereof used to enhance heat resistance.

[0015] According to embodiments of the present invention, the functionality of the bio-based polyol is 2 to 6.

[0016] According to embodiments of the present invention, the hydroxyl value of the bio-based polyol is 20 to 100 mg KOH / g.

[0017] According to embodiments of the present invention, the bio-based polyol has a molecular weight of 400 to 12,000 Da and a viscosity of 20 to 2,000 cps.

[0018] According to embodiments of the present invention, the isocyanate component has an NCO content of 15% to 60% and a viscosity of 20 to 2,000 cps.

[0019] According to embodiments of the present invention, one or more additives include a nanonucleating agent as a biofiller, which improves the pore nucleation, structural integrity, and heat resistance of the resulting polyurethane foam. In alternative embodiments, other bio-based or nanocellulose fillers may be used instead of cellulose nanocrystals and inorganic nanoparticles selected from nano-silica and nanoclay, or in combination with cellulose nanocrystals and inorganic nanoparticles selected from nano-silica and nanoclay. According to embodiments of the present invention, one or more additives include one or more nucleating agents in an amount of up to 2% by weight.

[0020] According to embodiments of the present invention, the nanonucleating agent has a content of up to 3% by weight and an average particle size of 5 to 50 nm.

[0021] According to embodiments of the present invention, the catalyst system comprises a gelling catalyst at a content of up to 2% by weight and / or a foaming catalyst at a content of up to 0.4% by weight.

[0022] According to an embodiment of the present invention, the chemical foaming agent comprises water at a content of up to 5% by weight.

[0023] According to embodiments of the present invention, the physical blowing agent comprises acetone in an amount of up to 20% by weight. Acetone is described herein as an illustrative example of a physical blowing agent, not a limiting one.

[0024] According to embodiments of the present invention, one or more additives include one or more surfactants in an amount of up to 2% by weight.

[0025] According to embodiments of the present invention, one or more additives include one or more open-cell stabilizers in an amount of up to 5% by weight.

[0026] According to embodiments of the present invention, one or more additives include one or more chain extenders in an amount of up to 10% by weight.

[0027] According to embodiments of the present invention, one or more additives include one or more crosslinking agents in an amount of up to 10% by weight.

[0028] According to embodiments of the present invention, the bio-based polyurethane foam has: a compressive strength of at least 25 kPa; a density of less than 150 kg / m³; and an open-cell structure of at least 80%.

[0029] According to embodiments of the present invention, the bio-based polyurethane foam has a predetermined thermal decomposition temperature of at least 260°C, a predetermined tensile strength of at least 1,000 kPa, and a predetermined elongation at break of at least 450%.

[0030] According to an embodiment of the present invention, the bio-based content of the foam is greater than 80%.

[0031] Another embodiment of the invention relates to a method for producing bio-based polyurethane foam. The method includes the steps of: forming a polyol-based mixture by combining: 50 to 90 weight percent of one or more bio-based polyols derived from renewable resources; optionally one or more additives; a catalyst system, including a gelling catalyst and / or a foaming catalyst; and optionally a chemical blowing agent, wherein all weight percentages are based on the total formulation.

[0032] According to an embodiment of the present invention, the method further includes the steps of: forming an isocyanate-based mixture (part B) by combining the following: 40 to 70 weight percent of one or more isocyanates, and optionally a physical blowing agent; combining a polyol-based mixture (part A) with the isocyanate-based mixture (part B) to initiate a foaming reaction; and foaming and curing the reaction mixture in a mold to form a bio-based polyurethane foam.

[0033] According to an embodiment of the present invention, the method further includes the following steps: adding a flexible foam polyol to a bio-based polyol to form a portion A2; dehydrating the polyol-based chemicals in portion A2; combining the polyol in portion A2 with an isocyanate (portion A1) to initiate a reaction to form a prepolymer solution (portion A); forming a secondary polyol-based mixture (portion B); combining portion A and portion B to initiate a foaming reaction; and foaming and curing the reaction mixture in a mold to form a bio-based polyurethane foam.

[0034] According to embodiments of the present invention, the bio-based polyol is selected from polyester polyols, polyether polyols, or combinations thereof.

[0035] According to embodiments of the present invention, forming a polyol-based mixture includes mixing at a speed of 1,000 to 10,000 rpm for 1 to 10 minutes in a mixing head or a high-shear mixing head.

[0036] According to an embodiment of the present invention, the mold temperature is maintained at 40 to 90°C for 5 to 60 minutes.

[0037] According to embodiments of the present invention, the method further includes demolding the foam and subjecting the foam to post-curing treatment. Attached Figure Description

[0038] To gain a detailed understanding of the above-described features of the present invention, a more specific description of the invention, which has been briefly summarized above, can be obtained with reference to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings only show typical embodiments of the invention and should not be considered as limiting its scope, as the invention may allow for other equivalent embodiments.

[0039] The invention can be better understood from the following description with reference to the accompanying drawings, in which:

[0040] Figure 1 A flowchart of a method for producing bio-based polyurethane foam according to an embodiment of the present invention is shown;

[0041] Figure 2A The polyurethane gelation reaction between polyol and isocyanate according to an embodiment of the present invention is illustrated;

[0042] Figure 2B A foaming reaction involving isocyanate and water according to an embodiment of the present invention is illustrated, which results in the generation of gas.

[0043] It should be noted that the accompanying drawings are intended to illustrate exemplary embodiments of the present disclosure. The drawings are not intended to limit the scope of the disclosure. It should also be noted that the drawings are not necessarily drawn to scale. Detailed Implementation

[0044] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of embodiments of the invention. Specific embodiments in which the invention may be practiced have been described in sufficient detail as illustrative or exemplary embodiments of the invention to enable those skilled in the art to implement the disclosed embodiments. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced with or without these specific details. In other instances, well-known methods, processes, and components have not been described in detail so as not to unnecessarily obscure various aspects of embodiments of the invention.

[0045] Therefore, the following detailed description is not intended to be limiting, and the scope of the invention is defined by the appended claims and their equivalents. The terms “comprising,” “including,” “having,” etc., are synonymous, used inclusively in an open-ended manner, and do not exclude additional elements, features, actions, operations, etc. Furthermore, the term “or” is used in its inclusive sense (rather than its exclusive sense), and thus, when used, for example, to connect a series of elements, the term “or” indicates one, some, or all of the elements in the list. References in the specification to “one embodiment,” “embodiment,” “multiple embodiments,” or “one or more embodiments” are intended to indicate that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention.

[0046] Although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally used only to distinguish one element from another and do not indicate any order, sequence, quantity, or importance, but are used to distinguish one element from another. Furthermore, the terms “a” and “an” in this document do not indicate a limitation on quantity, but rather indicate the presence of at least one of the cited items.

[0047] Unless otherwise expressly stated or understood in the context in which they are used, the conditional language used herein (e.g., “can,” “may,” “possibly,” “can,” “for example,” etc.) is generally intended to convey that a particular embodiment includes a particular feature, element, and / or step, while other embodiments do not include a particular feature, element, and / or step.

[0048] Unless otherwise expressly stated, the disjunctive language (e.g., the phrase "at least one of X, Y, Z") should be understood to mean that the context in which items, terms, etc., are typically used can be X, Y, or Z or any combination thereof (e.g., X, Y, and / or Z). Therefore, such disjunctive language is generally not intended and should not imply that some embodiments require at least one of X, at least one of Y, or at least one of Z to be present respectively.

[0049] The following brief definitions of terms should apply throughout this invention.

[0050] The terms “determine,” “measure,” “evaluate,” “assess,” “determine,” and “analyze” are used interchangeably herein to refer to any form of measurement, including determining the presence of an element (e.g., detection). These terms may include quantitative and / or qualitative determinations. Assessments may be relative or absolute.

[0051] Figure 1 A flowchart of a method 100 for producing bio-based polyurethane foam according to an embodiment of the present invention is shown.

[0052] In step 102, according to the formulation and process disclosed in the specification, a polyol-based mixture is formed by mixing one or more bio-based polyols derived from renewable resources with selected auxiliary components to establish the initial and foundational stage of a method 100 for producing bio-based polyurethane foam, wherein the chemical composition, dispersion quality and reactivity are defined before the foaming reaction begins.

[0053] Based on the overall formulation, one or more bio-based polyols are introduced into the container in an amount of 50% to 90% by weight. The bio-based polyols are selected from polyester polyols, polyether polyols, or combinations thereof, and are derived from renewable resources, including vegetable oils such as castor oil, soybean oil, rapeseed oil, sunflower oil, and other organic feedstocks. The bio-based polyols are characterized by a functionality of 2 to 6, a hydroxyl value of 20 mg / g to 100 mg / g, a molecular weight of 400 Daltons to 12,000 Daltons, and a viscosity of 20 centipoise to 2,000 centipoise, thereby providing controlled reactivity, processability, and compatibility with subsequent reactions involving isocyanates.

[0054] Optional additives are introduced into the polyol-based mixture to customize foam morphology, mechanical properties, and processing behavior. One or more additives are selected from nucleating agents, surfactants, open-cell stabilizers, chain extenders, crosslinking agents, and biofillers, and are added individually or in combination, depending on the desired foam characteristics. The additives are present in predetermined amounts, wherein the nucleating agent is added at up to 2% by weight to promote uniform cell nucleation, the surfactant is added at up to 2% by weight to stabilize foam cells and control cell size, the open-cell stabilizer is added at up to 5% by weight to ensure the formation of open-cell structures, the chain extender is added at up to 10% by weight to enhance the molecular weight growth and mechanical strength of the polymer network, and a crosslinking agent is further added at up to 10% by weight to increase the crosslinking density, thereby improving the structural integrity and thermal stability of the resulting polyurethane foam.

[0055] Optionally, bio-fillers are added to the polyol-based mixture to increase the total bio-based content and influence the nucleation and reinforcement of the foam structure, while further improving the thermal stability and heat resistance of the resulting polyurethane foam. In one embodiment, the bio-filler comprises up to 3% by weight of cellulose nanocrystals and inorganic nanoparticles selected from nano-silica and nano-clay, characterized in that the average particle size ranges from 5 nm to 50 nm. The cellulose nanocrystals and inorganic nanoparticles selected from nano-silica and nano-clay are distributed in the polyol matrix to act as nucleation sites during foaming and provide nanoscale mechanical reinforcement, thereby contributing to enhanced compressive strength, tensile strength, and elongation properties of the final foam.

[0056] A catalyst system is introduced into polyol-based mixture portion A to modulate reaction kinetics during subsequent gelation and foaming reactions. This catalyst system comprises a gelation catalyst and / or a foaming catalyst, wherein the gelation catalyst is selected to accelerate the reaction between the hydroxyl groups of the bio-based polyol and the isocyanate groups of the isocyanate component, and the foaming catalyst is selected to facilitate efficient gas generation by the chemical foaming agent. Controlled predetermined amounts of the catalyst system are introduced, with the gelation catalyst content up to 2 wt% and the foaming catalyst content up to 0.4 wt%. In some embodiments, the catalyst system may be substantially free of tin-based catalysts to improve environmental compatibility.

[0057] An optional chemical blowing agent is introduced into the polyol-based mixture as part of the blowing agent system. The chemical blowing agent includes up to 5% by weight water, which is configured to react with the isocyanate groups in a later stage of the process to generate carbon dioxide gas. The chemical blowing agent is included in a controlled manner to ensure uniform distribution within the polyol-based mixture while preventing premature gas escape before combination with the isocyanate-based mixture.

[0058] A mixture of bio-based polyols, optional additives, biofillers, a catalyst system, and optional chemical blowing agents is used to obtain an initial dispersion sufficient to define the polyol-based mixture. The polyol-based mixture is formed under conditions preventing phase separation, sedimentation of the biofiller, or local concentration gradients of the additives or catalysts. The resulting polyol-based mixture is characterized by a homogeneous composition, stable rheological behavior, and readiness for subsequent high-shear homogenization, vacuum degassing, reactive combination with isocyanate-based mixtures, and controlled foaming and curing within a mold, thereby enabling the formation of a bio-based polyurethane foam, in some embodiments of which may have a bio-based content greater than 80%, an open-cell structure, and enhanced mechanical and thermal properties as disclosed in the specification.

[0059] Method 100 may include adding a predetermined amount of polyol, various additives and biological filler into a container to obtain a primary mixture.

[0060] Method 100 may include mixing the primary mixture under controlled high-shear mixing conditions sufficient to achieve uniform dispersion of the polyol, various additives and biofillers.

[0061] Method 100 may include adding a predetermined amount of catalyst and one or more chemical foaming agents to a homogeneous primary mixture to form a first mixture.

[0062] Optionally, prior to the formation of the first mixture, the homogeneous primary mixture is subjected to vacuum treatment to remove entrained air and dissolved gases. In step 102, high-shear mixing of the polyol-based mixture is performed to achieve homogeneous dispersion of the bio-based polyol, various additives, biofillers, catalyst system, and any optional chemical foaming agent, thereby establishing the homogeneous physicochemical conditions required for controlled foaming and curing in subsequent stages of the method 100. This step is carried out as a critical homogenization stage, in which dispersion quality, interfacial compatibility, and reaction homogeneity are actively controlled prior to the introduction of the isocyanate-based mixture.

[0063] Within a mixing head or high-shear mixing head, the polyol-based mixture formed in the previous step is subjected to controlled high-shear mixing conditions. High-shear mixing is performed at speeds of 1,000 rpm to 10,000 rpm for 1 to 10 minutes, wherein the shear energy input is selected to overcome cohesion and viscosity gradients within the mixture. The applied shear force is sufficient to uniformly disperse cellulose nanocrystals (if present) with an average particle size of 5 nm to 50 nm and inorganic nanoparticles selected from nano-silica and nano-clay throughout the polyol matrix, thereby preventing localized aggregation and ensuring a nanoscale distribution of the biofiller.

[0064] In this step, bio-based polyols with functionality of 2 to 6, hydroxyl values ​​of 20 mg / g to 100 mg / g, and viscosities of 20 centipoise to 2,000 centipoise undergo intense mechanical mixing, which promotes close contact with nucleating agents, surfactants, cell-opening stabilizers, and chain extenders. The high-shear environment effectively distributes surfactants at concentrations up to 2 wt% along the resulting interface, thereby stabilizing the mixture and preparing the system for subsequent cell formation. Nucleating agents at concentrations up to 2 wt% are uniformly dispersed to ensure consistent nucleation density during foaming.

[0065] The mixture includes up to 5% by weight of an opening-cell stabilizer to regulate opening-cell behavior during foam expansion, and up to 10% by weight of a chain extender for uniform distribution to support uniform polymer chain growth during the gelation reaction. The catalyst system, including up to 2% by weight of a gelation catalyst and up to 0.4% by weight of a foaming catalyst, is uniformly dispersed to ensure consistent reaction kinetics throughout the entire volume of the polyol-based mixture.

[0066] As part of step 102, a vacuum treatment may optionally be applied to the polyol-based mixture after or during high-shear mixing. The vacuum treatment removes entrained air, dissolved gases, and microbubbles introduced during the mixing process. Removing entrained gases prevents uncontrolled bubble growth, foam collapse, or defect formation in subsequent foaming stages. The vacuum treatment is maintained until the polyol-based mixture exhibits visible degassing and a stable state, thereby improving the reproducibility and structural uniformity of the final bio-based polyurethane foam.

[0067] In one embodiment, the bio-based polyurethane foam has a predetermined thermal decomposition temperature, a predetermined tensile strength, and a predetermined elongation at break.

[0068] In one embodiment, the bio-based polyurethane foam has a predetermined thermal decomposition temperature of at least 260°C, a predetermined tensile strength of at least 1,000 kPa, and a predetermined elongation at break of at least 450%.

[0069] High-shear mixing conditions are selected to maintain the thermal stability of the mixture while avoiding premature gelation or foaming reactions. The temperature rise associated with the shear input is inherently controlled by selecting the mixing rate, duration, and container geometry, thereby maintaining the chemical stability of the polyol-based mixture before combination with the isocyanate-based mixture. The mixture formed from this step is characterized by uniform viscosity, no phase separation, and consistent dispersion of all solid and liquid components.

[0070] Step 102 yields a chemically active yet physically stable homogeneous polyol-based mixture, enabling precise control over subsequent reaction processing. The uniform dispersion achieved in this step is directly related to a uniform cell size distribution, controlled open-cell structure, and enhanced mechanical properties of the final foam, including compressive strength, tensile strength, elongation at break, and thermal stability. The polyol-based mixture produced in this stage is adequately prepared for the controlled addition of chemical blowing agents (if applicable), followed by reactive combination with the isocyanate-based mixture to initiate gelation and foaming reactions in a predictable and reproducible manner.

[0071] In step 102, a catalyst and one or more chemical foaming agents are added to the homogeneous polyol-based mixture obtained from the aforementioned high-shear mixing step to form a first mixture, which is then chemically activated for subsequent gelation and foaming reactions. This step is performed to precisely regulate reaction kinetics, gas generation behavior, and foam morphology before contact with the isocyanate-based mixture, while maintaining a uniform distribution of all reactive components throughout the formulation.

[0072] In this step, a catalyst system is introduced into a homogeneous polyol-based mixture in selected predetermined amounts to balance the gelation and foaming reactions. This catalyst system comprises one or more gelation catalysts and / or one or more foaming catalysts, wherein, based on the total formulation, the content of the gelation catalyst is up to 2% by weight and the content of the foaming catalyst is up to 0.4% by weight. The gelation catalyst is selected to accelerate the reaction between the hydroxyl groups of the bio-based polyol and the isocyanate groups of the isocyanate component introduced in subsequent steps, thereby controlling the formation of the polymer network and the development of mechanical strength. The foaming catalyst is selected to improve the rate and uniformity of gas generation by the chemical foaming agent, thereby supporting controlled foam expansion.

[0073] The catalyst system added in this step is essentially tin-free, including dibutyltin dilaurate, and is instead selected from environmentally friendly alternatives, such as bismuth-based and amine-based catalysts. The inclusion of a tin-free catalyst system in this stage reduces toxicity, improves environmental sustainability, and maintains compliance with regulatory and occupational safety requirements, while still providing effective catalytic activity for polyurethane formation and foaming reactions.

[0074] Simultaneously with the addition of a catalyst, one or more chemical foaming agents are added to a homogeneous polyol-based mixture to form a first mixture. The chemical foaming agent comprises water, with a water content of up to 5% by weight. Under controlled mixing conditions, the water is uniformly dispersed throughout the polyol-based mixture to prevent localized concentration gradients. The water introduced in this step is configured to react with the isocyanate groups during subsequent combination with the isocyanate-based mixture, thereby generating carbon dioxide gas in situ to drive foam expansion.

[0075] Carefully control the addition of the chemical foaming agent in this step to ensure that gas does not escape prematurely before reacting with the isocyanate component. Maintain the homogeneous dispersion obtained in the preceding high-shear mixing step and treat the mixture under conditions that maintain chemical stability until the desired foaming reaction is initiated. At this stage, fully utilize the presence of nucleating agents and nanoparticles (including cellulose nanocrystals and inorganic nanoparticles selected from nano-silica and nano-clay) already dispersed in the mixture to provide controlled nucleation sites for bubble formation as carbon dioxide begins to be generated.

[0076] In step 102, mixing takes place under conditions sufficient to uniformly distribute the catalyst system and chemical blowing agent without introducing excessive shear that could destabilize the mixture or trigger premature reactions. The first mixture formed in this stage is characterized by a uniform distribution of catalytic activity and a consistent chemical blowing agent concentration throughout the volume, thereby enabling predictable foaming behavior in subsequent processing.

[0077] In step 102, a first mixture is formed, establishing the chemical readiness of the reactive combination of the polyol-based system and the isocyanate-based mixture. The precise balance of the gelling catalyst, foaming catalyst, and chemical foaming agent introduced in this step is configured to ensure simultaneous polymerization and gas generation, which is crucial for achieving open-cell foam structures, controlling cell sizes to less than 3 mm, improving heat resistance, and enhancing mechanical properties (including compressive strength, tensile strength, and elongation at break).

[0078] After completing step 102, the first mixture remains stable, homogeneous, and chemically ready for foaming, enabling efficient and controlled initiation of gelation and foaming reactions when subsequently combined with the isocyanate-based mixture. The controlled activation achieved at this stage directly contributes to the formation of a bio-based polyurethane foam with over 80% bio-based carbon content, uniform cell morphology, and reproducible performance characteristics disclosed in the specification.

[0079] In one embodiment of this disclosure, method 100 further includes the steps of: forming an isocyanate-based mixture (part B) by combining the following: (i) 40 to 70 weight percent of one or more isocyanates, and (ii) an optional physical blowing agent; combining a polyol-based mixture (part A) with the isocyanate-based mixture (part B) to initiate a foaming reaction; and foaming and curing the reaction mixture in a mold to form a bio-based polyurethane foam.

[0080] In step 104, an isocyanate-based mixture (part B) is formed by combining the following: (i) 40 to 70 weight percent of one or more isocyanates, and (ii) an optional physical foaming agent.

[0081] Method 100 may include mixing a predetermined amount of isocyanate and one or more physical foaming agents in a separate container to obtain a second mixture.

[0082] In step 104, an isocyanate-based mixture (part B) is formed by mixing one or more isocyanates with one or more physical blowing agents in a separate container, thereby establishing a reactive counterpart to the polyol-based mixture (part A) prepared in the preceding steps. This step is performed as a unique, controlled operation to ensure that the isocyanate components remain chemically stable, uniformly mixed, and optimally tuned for subsequent reactive combinations, while preventing premature reaction or volatilization of the physical blowing agents.

[0083] In this step, one or more isocyanates are introduced into a dedicated container at a content of 40% to 70% by weight, based on the total formulation. The isocyanate is selected from aromatic isocyanates, aliphatic isocyanates, or combinations thereof, including methylene diphenyl diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, benzene-1,4-diisocyanate, pentamethylene diisocyanate, or mixtures thereof. The isocyanate component is characterized by an isocyanate content of 15% to 60% and a viscosity of 20 centipoise to 20,000 centipoise, thereby ensuring compatibility with the polyol-based mixture (part A) and enabling control of reaction kinetics during subsequent foaming.

[0084] The isocyanate component used in this step can be bio-based, petroleum-based, or a combination thereof, provided that the total formulation achieves a bio-based carbon content of over 80% in the final bio-based polyurethane foam. When using bio-based isocyanates, the isocyanates are derived from renewable or partially renewable raw materials, thus contributing to the sustainability goals of the formulation while maintaining the reactivity and performance required for polyurethane foam production.

[0085] In step 104, one or more physical blowing agents are added to the isocyanate component in a predetermined amount to form an isocyanate-based mixture. Based on the total formulation, the content of the physical blowing agent is up to 20% by weight, more specifically, from 3% to 15% by weight. Non-limiting examples of physical blowing agents include acetone, hydrocarbons, ketones, ethers, esters, or combinations thereof. In one embodiment, acetone is used as a physical blowing agent because of its volatility, environmental compatibility, and ability to evaporate under foaming conditions to generate a gas for foam expansion without chemically reacting with the isocyanate component.

[0086] The addition of the physical blowing agent in this step is carried out under controlled temperature and mixing conditions to ensure complete and uniform dispersion of acetone in the isocyanate phase. The isocyanate-based mixture is maintained under conditions that inhibit premature evaporation of acetone, thereby maintaining the blowing agent concentration until reactive mixing with the polyol-based mixture (part A). Separating the physical blowing agent into the isocyanate-based mixture, rather than the polyol-based mixture (part A), is configured to improve process stability and allow for precise control of gas generation during the foaming reaction.

[0087] In step 104, mixing is performed using a mixer sufficient to achieve homogeneity without causing excessive shear or heat accumulation. Mixing conditions are selected to ensure uniform distribution of the physical blowing agent throughout the isocyanate component, while avoiding localized concentration gradients that could lead to uneven cell size or foam breakage during expansion. The resulting isocyanate-based mixture is characterized by consistent viscosity, uniform blowing agent distribution, and stable storage behavior shortly before combination with the polyol-based mixture (part A).

[0088] Throughout step 104, the chemical integrity of the isocyanate groups was maintained, and no significant reaction occurred between the isocyanate components and the physical blowing agent. Therefore, the isocyanate-based mixture remained chemically active but physically stable, ready to undergo a gelation reaction with the hydroxyl groups of the bio-based polyol, and subsequently, a foaming reaction driven by both chemical and physical blowing agents, upon assembly.

[0089] In step 104, the formation of the isocyanate-based mixture (part B) is intentionally separated from the formation of the polyol-based mixture (part A) to allow for independent optimization of the composition, mixing, and processing conditions. This separation ensures the introduction of sensitive components such as acetone at the most suitable stage of the process, thereby minimizing losses due to volatilization and maximizing foaming efficiency in the reaction phase.

[0090] In step 106, the polyol-based mixture (part A) and the isocyanate-based mixture (part B) are combined to initiate a foaming reaction. The isocyanate-based mixture (part B) prepared in step 104 is configured to synergize with the polyol-based mixture (part A) formed in step 102. Upon subsequent combination, the isocyanate groups are positioned to react with the hydroxyl groups of the bio-based polyol to form urethane bonds, while the physical foaming agent is positioned to evaporate in response to the exothermic reaction generated during polymerization.

[0091] Step 106 yields a homogeneous, stable, and reactive polymer-forming mixture that supports simultaneous gelation and foaming reactions during the foaming stage. The controlled preparation of the reactive polymer-forming mixture in this step directly contributes to the formation of a bio-based polyurethane foam with an open-cell structure, an average pore size of less than 3 mm, a density of less than 150 kg / m³, and enhanced mechanical properties, including compressive strength, tensile strength, and elongation at break.

[0092] Method 100 may include mixing a first mixture and a second mixture in a mixing head to initiate a gelling reaction and a foaming reaction, thereby forming a reactive foam-forming mixture.

[0093] Controlled high-shear mixing is performed at speeds of 1,000 rpm to 10,000 rpm, with the duration of controlled high-shear mixing being 1 minute to 10 minutes.

[0094] The first and second mixtures are combined in the mixing head for a duration of 10 to 30 seconds.

[0095] During foaming and curing, the mold is maintained at a temperature range of 40 to 90 degrees Celsius.

[0096] During foaming, the mold is selectively pressurized or depressurized to control the foam density and cell structure.

[0097] In step 108, the reaction mixture is foamed and cured in a mold to form a bio-based polyurethane foam. Method 100 may include transferring a reactive foam-forming mixture into a mold and allowing the reactive foam-forming mixture to expand, foam, and cure to produce a bio-based polyurethane foam.

[0098] The reactive foam-forming mixture is foamed and cured in a mold for a period of 5 to 60 minutes.

[0099] Method 100 further includes a post-curing step, wherein the demolded bio-based polyurethane foam is maintained at a temperature of 10°C to 40°C, and wherein the duration of the post-curing step is 12 hours to 60 hours.

[0100] In one embodiment of this disclosure, the bio-based polyurethane foam exhibits an open-cell structure with an average cell diameter of less than 3 mm, wherein the cell size distribution is modulated by the synergistic gelation reaction, foaming reaction, and nucleation effect of the bio-filler.

[0101] In one embodiment of this disclosure, the mechanical, thermal, and structural properties of bio-based polyurethane foam are evaluated according to applicable ASTM and ISO standard test methods, with particular emphasis on heat resistance and the ability of the foam to maintain its mechanical and structural integrity after exposure to thermal stress and heat-based treatments, to ensure reproducible and comparable performance characterization.

[0102] In one embodiment of this disclosure, high-shear mixing is performed at a rotation speed of 4,000 rpm or greater to achieve uniform dispersion of cellulose nanocrystals, additives and catalysts in the polyol phase.

[0103] In one embodiment of this disclosure, the foam production equipment is configured to process foam to a defined foam volume at a controlled foam rise height, wherein the equipment maintains uniform mixing, controlled expansion, and stable foam formation during the production process.

[0104] In another embodiment of this disclosure, method 100 further includes the steps of: adding a flexible foam polyol to a polyol-based mixture to form portion A2; dehydrating the polyol-based chemicals in portion A2; combining the polyol in portion A2 with an isocyanate (portion A1) to initiate a reaction to form a prepolymer solution (portion A); forming a polyol-based mixture (portion B); combining portion A and portion B to initiate a foaming reaction; and foaming and curing the reaction mixture in a mold to form a bio-based polyurethane foam.

[0105] In step 110, a flexible foam polyol is added to a bio-based polyol to form portion A2. The flexible foam polyol is included under controlled mixing conditions to ensure homogeneity. The resulting portion A2 is configured to adjust the flexibility, elasticity, and overall foam performance characteristics.

[0106] In step 112, a portion of the polyol-based chemicals in A2 is dehydrated. This dehydration removes residual moisture present in the bio-based polyols and flexible foam polyols. The dehydration step prevents premature reaction between water and isocyanate groups, thereby ensuring controlled prepolymer formation, uniform foaming, and improved mechanical and thermal stability of the resulting bio-based polyurethane foam.

[0107] In step 114, the polyol in portion A2 is combined with the isocyanate (portion A1) to initiate a reaction that forms a prepolymer solution (portion A). The polyol in portion A2 is combined with the isocyanate (portion A1) under controlled mixing conditions to initiate a reaction between the hydroxyl groups of the polyol and the isocyanate groups, thereby forming an isocyanate-terminated prepolymer solution (portion A).

[0108] Isocyanate (part A1) is configured to synergize with the dehydrated polyol-based chemicals in part A2. This reaction between the polyol in part A2 and isocyanate (part A1) leads to the formation of a prepolymer solution (part A). The formation of the prepolymer improves control over polymer network development, thereby enhancing the structural integrity and thermal stability of the resulting bio-based polyurethane foam.

[0109] In step 116, a minor polyol-based mixture (part B) is prepared by combining one or more bio-based polyols with selected additives, including catalysts, surfactants, chain extenders, crosslinking agents, and foaming agents.

[0110] In step 118, the prepolymer solution (part A) is combined with a minor polyol group mixture (part B) under controlled mixing conditions to initiate foaming and polymerization reactions. The interaction between the reactive components in the isocyanate-terminated prepolymer solution (part A) and part B leads to gas generation, cross-linked network formation, and the development of a uniform foam structure, resulting in enhanced mechanical integrity and heat resistance.

[0111] In step 120, method 100 may include transferring a reactive foam forming mixture into a mold and causing the reactive foam forming mixture to expand, foam, and cure to produce a bio-based polyurethane foam.

[0112] The reactive foam-forming mixture is foamed and cured within the mold for a duration of 5 to 60 minutes.

[0113] Method 100 further includes a post-curing step, wherein the demolded bio-based polyurethane foam is maintained at a temperature of 10°C to 40°C, and wherein the duration of the post-curing step is 12 hours to 60 hours.

[0114] In one embodiment of this disclosure, the bio-based polyurethane foam exhibits an open-cell structure with an average cell diameter of less than 3 mm, wherein the cell size distribution is modulated by the synergistic gelation reaction, foaming reaction, and nucleation effect of the bio-filler.

[0115] In one embodiment of this disclosure, the mechanical, thermal, and structural properties of bio-based polyurethane foam are evaluated according to applicable ASTM and ISO standard test methods, with particular emphasis on heat resistance and the ability of the foam to maintain its mechanical and structural integrity after exposure to thermal stress and heat-based treatments, to ensure reproducible and comparable performance characterization.

[0116] In one embodiment of this disclosure, high-shear mixing is performed at a rotation speed of 4,000 rpm or greater to achieve uniform dispersion of cellulose nanocrystals, inorganic nanoparticles including nano-silica and nano-clay, additives and catalysts in a polyol phase.

[0117] In one embodiment of this disclosure, the foam production equipment is configured to process foam to a defined foam volume at a controlled foam rise height, wherein the equipment maintains uniform mixing, controlled expansion, and stable foam formation during the production process.

[0118] In one exemplary embodiment, Table 1 shows the mechanical properties of the bio-based polyurethane foams according to Examples 1 and 2, evaluated before and after heat treatment by hot pressing, demonstrating improved retention of mechanical integrity and heat resistance in Example 2 compared to Example 1.

[0119] Table 1:

[0120]

[0121] In Example 1, the high-bio-based foam formed by a single-step direct casting method was hot-pressed at approximately 150°C for 5 to 10 minutes. After the hot-pressing process, the density decreased from approximately 80 to 100 kg / m³. 3Increased to 205 to 242 kg / m 3 The results indicate structural densification. However, mechanical properties deteriorated significantly. Tensile strength decreased from approximately 1275±103 kPa to 554±17 kPa, elongation decreased from approximately 580±21% to 99±0.7%, and tear strength decreased from approximately 7517±776 N / m to 2104 N / m. Elasticity also decreased significantly. This indicates that the foam structure degraded due to heat treatment.

[0122] In Example 2, the highly bio-based polyurethane foam of the present invention, formed by a prepolymer-based method, was hot-pressed at approximately 170°C for 5 to 10 minutes. After heat treatment, the density decreased from approximately 135 kg / m³. 3 Increased to 325 kg / m 3 This indicates effective structural reinforcement. Tensile strength increased significantly from approximately 2195 ± 188 kPa to 3990 ± 196 kPa, elongation increased from approximately 342 ± 8.5% to 454 ± 55%, tear strength increased from approximately 4980 N / m to 9500 N / m, and hardness also increased from approximately 55 Shore F to 72 to 78 Shore F, indicating enhanced structural integrity. Importantly, mechanical properties were maintained or improved.

[0123] These results demonstrate that, unlike conventional high-bio-based foams, the bio-based polyurethane foam of this invention retains and improves its mechanical properties after heat treatment. This indicates enhanced crosslinking stability, structural integrity, and thermal durability, enabling the foam to be used in applications requiring thermoforming, hot pressing, or high-temperature processing.

[0124] In one exemplary embodiment, Table 1A provides the formulation and component mass ratios used in the production of bio-based polyurethane foam using a single-step direct casting method according to Example 1.

[0125] Table 1A:

[0126]

[0127] In one embodiment, the bio-based polyurethane foam is produced using a single-step direct casting method. In this embodiment, a polyol-based mixture (part A) is first prepared by combining 100 parts by weight of a bio-based polyol (B2000), which serves as the main renewable polyol component. A blowing agent (H2O) is added in an amount of 0.5 to 2 parts by weight to promote foam expansion by generating carbon dioxide during the reaction with isocyanate. A surfactant (B2370) is incorporated in an amount of 0.5 to 2 parts by weight to stabilize the foam structure and regulate cell formation. Optionally, an opening agent (SK1900) is added in an amount of 0 to 5 parts by weight to enhance cell openness and improve foam permeability. A nucleating agent (R974) is added in an amount of 0.2 to 2 parts by weight to promote uniform cell nucleation and refine the foam morphology. A catalyst system comprising 0.05 to 1 part by weight of A300 catalyst and 0.2 to 2 parts by weight of bismuth neodecanoate is added to promote the urethane formation reaction and control the reaction kinetics. Individually, an isocyanate-based mixture (part B) is prepared by combining 10 to 35 parts by weight of toluene diisocyanate (TDI) as a reactive isocyanate component. 0.5 to 5 parts by weight of a physical blowing agent containing acetone is added to aid foam expansion through volatilization during the exothermic reaction. Parts A and B are then combined and mixed to form a reactive foam-forming mixture, which is poured into a mold and allowed to foam and cure to form a bio-based polyurethane foam.

[0128] In one exemplary embodiment, Table 1B lists the formulation and component mass ratios for producing bio-based polyurethane foam using a prepolymer-based method according to Example 2.

[0129] Table 1B:

[0130]

[0131] In another embodiment, a prepolymer method is used to produce bio-based polyurethane foam to improve the structural integrity and heat resistance of the resulting foam. In this embodiment, a prepolymer mixture (part A) is first prepared by reacting an isocyanate component comprising 30 to 50 parts by weight of methylene diphenyl diisocyanate (MDI) with 20 to 40 parts by weight of a bio-based polyol (part A2) (B2000) and 2 to 10 parts by weight of a flexible foam polyol (part A2) (EP-330N). The reaction between the isocyanate and polyol components forms an isocyanate-terminated prepolymer with a controlled molecular structure and enhanced reactivity. A polyol-based mixture (part B) is prepared separately by combining 100 parts by weight of the bio-based polyol (B2000). 0.5 to 5 parts by weight of a blowing agent (H2O) is added to promote foam expansion. 0.5 to 3 parts by weight of a surfactant (DC-193) is added to stabilize the porous structure of the foam. One to three parts by weight of a chain extender containing propylene glycol (BDO) are added to increase the molecular weight and improve mechanical strength. One to three parts by weight of a crosslinking agent containing trimethylolpropane (TMP) are added to enhance crosslinking density and improve structural stability. 0.2 to one part by weight of a catalyst (A33) is added to promote the urethane formation reaction. The prepolymer mixture (part A) is then combined with and thoroughly mixed with a polyol-based mixture (part B) to form a reactive foam-forming composition. The mixture is then foamed and cured to form a bio-based polyurethane foam. The prepolymer method allows for improved control over polymer network formation, resulting in enhanced mechanical properties and improved retention of structural integrity after heat exposure.

[0132] Figure 2A The polyurethane gelation reaction between polyols and isocyanates according to an embodiment of the present invention is illustrated.

[0133] Figure 2A This diagram illustrates the fundamental chemical reactions responsible for forming the polyurethane polymer network during the production of bio-based polyurethane foam. The figure shows the reaction of an isocyanate compound containing reactive isocyanate groups with a polyol containing hydroxyl functional groups. During this reaction, the isocyanate groups combine with the hydroxyl groups of the polyol, resulting in the formation of urethane bonds within the polymer backbone. This reaction is characterized by the formation of repeating urethane units, which collectively define the polyurethane chain structure. The polymerization process is driven by the chemical affinity between the isocyanate groups and hydroxyl groups, leading to polymer chain growth and the development of a three-dimensional polymer network. This gelation reaction is responsible for the solidification of the reaction mixture and the development of the foam's mechanical integrity. As polymerization proceeds, the molecular weight of the polymer network increases, resulting in a transformation from a liquid reaction mixture to a solid polymer matrix. Figure 2AThe reaction shown is central to the formation of the polyurethane framework, which encapsulates additives, biofillers, and blowing agents within the foam structure. This gelation mechanism is fundamental to achieving the structural stability, elasticity, and load-bearing capacity of the bio-based polyurethane foam produced according to this invention.

[0134] Figure 2B A foaming reaction involving isocyanate and water according to an embodiment of the present invention is illustrated, which results in the generation of gas.

[0135] Figure 2B This diagram illustrates the chemical foaming reaction that occurs during the formation of polyurethane foam when isocyanate groups react with water. The figure depicts a multi-step reaction sequence in which isocyanate initially reacts with water to form an unstable carbamic acid intermediate. The carbamic acid then decomposes, producing an amine and carbon dioxide gas. The carbon dioxide gas produced during this reaction is released into the reaction mixture and is responsible for forming bubbles that expand the polymer matrix. The amine formed during demolding further reacts with additional isocyanate groups to form urea bonds within the polymer structure. This series of reactions simultaneously contributes to foam expansion and the formation of the polymer network. Figure 2B The foaming reaction shown is essential for producing a porous foam structure by generating internal gas pressure that expands the reactants. The formation of urea bonds also contributes to the stiffness and strength of the polymer network. The controlled interaction between the gelation and foaming reactions is responsible for the development of open-cell or controlled-cell polyurethane foam structures. This reaction mechanism is indispensable for achieving uniform cell formation and the desired foam density in the bio-based polyurethane foam produced according to the present invention.

[0136] A polyol-based mixture portion A is formed by combining one or more bio-based polyols derived from renewable resources in an amount of 50 to 90 wt% with one or more additives, and further comprising a catalyst system including a gelling catalyst and / or a foaming catalyst, thereby performing the optimal operating mode of method 100 for producing bio-based polyurethane foam. The bio-based polyol is selected from polyester polyols, polyether polyols, or combinations thereof, characterized by a functionality of 2 to 6, a hydroxyl value of 20 mg / g to 100 mg / g, and a molecular weight of 400 Daltons to 12,000 Daltons. One or more additives are present in predetermined amounts to regulate foam morphology, polymer network development, and processing behavior, and optionally include biofillers comprising cellulose nanocrystals with an average particle size of 5 nm to 50 nm and inorganic nanoparticles selected from nano-silica and nano-clay to enhance nucleation and mechanical reinforcement. The amount of catalyst added is controlled, with the content of the gelling catalyst up to 2% by weight and the content of the foaming catalyst up to 0.4% by weight. The catalyst system is essentially free of tin-based catalysts. The polyol-based mixture is subjected to controlled high-shear mixing in a mixing head or high-shear mixing head at a speed of 1,000 rpm to 10,000 rpm for 1 to 10 minutes to obtain uniform dispersion. Optionally, the homogeneous polyol-based mixture is subjected to vacuum treatment to remove entrained air and dissolved gases.

[0137] One or more chemical blowing agents comprising up to 5% by weight of water are included in the polyol-based mixture to generate gas during a subsequent foaming reaction. Method 100, in a first embodiment, further includes the steps of: forming an isocyanate-based mixture (part B) by combining (i) 40 to 70% by weight of one or more isocyanates, and (ii) an optional physical blowing agent; combining the obtained polyol-based mixture (part A) with the isocyanate-based mixture (part B) to initiate a foaming reaction; and foaming and curing the reaction mixture in a mold to form a bio-based polyurethane foam. The isocyanate-based mixture is formed by combining one or more isocyanates comprising 40 to 70% by weight (the isocyanate content of the one or more isocyanates being 15% to 60%) with one or more physical blowing agents comprising up to 20% by weight of acetone. The polyol-based mixture (part A) and the isocyanate-based mixture (part B) are then combined in a mixing head to initiate a gelation and foaming reaction to form a bio-based polyurethane foam. In another embodiment, method 100 further includes the following steps: adding a flexible foam polyol to a polyol-based mixture to form portion A2; dehydrating the polyol-based chemicals in portion A2; combining the polyol in portion A2 with an isocyanate (portion A1) to initiate a reaction to form a prepolymer solution (portion A); forming a polyol-based mixture (portion B); combining portion A and portion B to initiate a foaming reaction; and foaming and curing the reaction mixture in a mold to form a bio-based polyurethane foam. A secondary polyol-based mixture (portion B) is prepared separately, followed by combining the prepolymer solution (portion A) with portion B to initiate a foaming and curing reaction. A reactive foam-forming mixture is formed. The reactive foam-forming mixture is transferred to a mold at a temperature of 40°C to 90°C and allowed to expand, foam, and cure for 5 to 60 minutes. After curing, the foam is demolded and can optionally undergo post-curing at a temperature of 10°C to 40°C for 12 to 60 hours to produce a bio-based polyurethane foam with an open-cell structure, a bio-based carbon content of over 80%, and improved mechanical properties such as thermal stability and resistance to thermal degradation.

[0138] In various alternative embodiments, the formulations and methods described herein may be modified without departing from the scope of the invention. Such modifications may include changes in process sequence, order of component addition, mixing conditions, degassing or vacuum treatment steps, curing and post-curing conditions, batch or continuous processing configurations, and scale of operation. Further embodiments may include alternative bio-based polyol sources, polyol mixtures, isocyanate types, additive systems, biofillers, foaming agent systems, foam morphology, performance characteristics, end-use applications, and equipment configurations. These embodiments are provided to illustrate the scope of the invention and to enable further adjustments, optimizations, modifications, or extensions to the disclosed subject matter.

[0139] This invention introduces a technologically advanced bio-based polyurethane foam system that achieves a high total bio-based carbon content of over 80% while maintaining excellent mechanical properties and controlled foam morphology. The formulation integrates a high proportion of bio-based polyols with controlled amounts of isocyanates and optional bio-fillers, such as nanonucleating agents, to establish a polymer network that supports a balance of sustainability, structural integrity, and thermal stability. This coordinated formulation directly addresses the long-standing challenge of performance degradation typically associated with high bio-based polyurethane foam content.

[0140] The key technological advancement lies in the mandatory inclusion of nanonucleating agents with nanoscale particle size at a concentration of 1 to 5% by weight. These nanonucleating agents act as bio-based reinforcing fillers and nucleation centers, enabling the formation of uniform pores, reducing average pore size, and improving load-bearing capacity. This nanoscale reinforcement mechanism contributes to improved compressive strength, tensile strength, and elongation at break without compromising foam flexibility, thus achieving high mechanical properties in a predominantly bio-based system. The prepolymer solution step controls the reaction between hydroxyl and isocyanate groups, leading to the formation of isocyanate-terminated intermediates that enhance the crosslinking density, structural uniformity, and thermal stability of the resulting bio-based polyurethane foam.

[0141] Another significant advancement is the restricted use of a combination of chemical and physical blowing agents, or combinations thereof, with water and acetone used in controlled proportions. This dual-foaming strategy synchronizes gas generation and evaporation, resulting in a stable open-cell foam structure with controlled cell size and high cell uniformity. The coordinated foaming behavior directly supports fine pore morphology and consistent foam expansion, overcoming the instabilities commonly found in bio-based foam systems.

[0142] This invention further enhances processing technology through forced high-shear mixing at speeds equal to or greater than 4,000 rpm. These processing conditions ensure uniform dispersion of nanonucleating agents, additives, and catalysts within the polyol phase, preventing agglomeration and phase separation. The resulting homogeneous reaction mixture enables predictable gelation and foaming reactions, directly translating into consistent foam quality and reproducible material properties.

[0143] By using an environmentally friendly catalyst system that does not contain tin-based catalysts, environmental and processing safety is further improved. The selection of catalysts allows for control of reaction kinetics while reducing toxicity and environmental impact, thus aligning performance targets with sustainability requirements.

[0144] In general, this invention provides a technically robust polyurethane foam system that integrates high bio-based content, nanoscale reinforcement, controlled foaming chemistry, and advanced processing conditions. These combined advancements result in bio-based polyurethane foams with high mechanical strength, fine and uniform cell structure, excellent heat resistance, overcoming the weaknesses of bio-based systems, stable open-cell morphology, and reproducible performance, thus providing a comprehensive technical solution to the challenges associated with sustainable polyurethane foam production.

[0145] Without conflict, the embodiments and features described herein can be combined with each other. The foregoing description is merely a specific implementation of this disclosure and is not intended to limit the scope of protection of this disclosure. Any variations or substitutions that are readily conceived by those skilled in the art within the scope of the technology disclosed herein will fall within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

[0146] For purposes of illustration and description, specific embodiments of the present technology have been described above. These descriptions are not intended to be exhaustive or to limit the present technology to the precise forms disclosed; obviously, many modifications and variations are possible in accordance with the foregoing teachings. These embodiments were chosen and described in order to best explain the principles of the present technology and its practical application, thereby enabling others skilled in the art to best utilize the present technology and various embodiments with various modifications suitable for their intended specific use. It should be understood that various substitutions of omissions and equivalents may be contemplated when circumstances may imply or provide convenience, without departing from the spirit or scope of the claims of the present technology; however, such substitutions of omissions and equivalents are intended to cover the application or implementation.

Claims

1. A bio-based polyurethane foam formulation, comprising: The polyol component includes 50 to 90% by weight of one or more bio-based polyols derived from renewable resources; Isocyanate component, comprising 40 to 70% by weight of one or more isocyanates; One or more optional additives are selected from nucleating agents, surfactants, pore-opening stabilizers, chain extenders, crosslinking agents, and biofillers; Catalyst systems, including gelation catalysts and / or foaming catalysts; and Foaming agent systems, including chemical foaming agents and / or physical foaming agents, All weight percentages are based on the total formula. The bio-based polyurethane foam has a predetermined thermal decomposition temperature, a predetermined tensile strength, and a predetermined elongation at break.

2. The bio-based polyurethane foam formulation according to claim 1, wherein, The bio-based polyol is selected from polyester polyols, polyether polyols, or combinations thereof.

3. The bio-based polyurethane foam formulation according to claim 1, wherein, The functionality of the bio-based polyol is 2 to 6.

4. The bio-based polyurethane foam formulation according to claim 1, wherein, The hydroxyl value of the bio-based polyol is 20 to 100 mg KOH / g.

5. The bio-based polyurethane foam formulation according to claim 1, wherein, The bio-based polyol has a molecular weight of 400 to 12,000 Da and a viscosity of 20 to 2,000 cps.

6. The bio-based polyurethane foam formulation according to claim 1, wherein, The isocyanate component has an NCO content of 15% to 60% and a viscosity of 20 to 2,000 cps.

7. The bio-based polyurethane foam formulation according to claim 1, wherein, The one or more additives include nanonucleating agents as biological fillers.

8. The bio-based polyurethane foam formulation according to claim 7, wherein, The nanonucleating agent has a content of up to 3% by weight and an average particle size of 5 to 50 nm.

9. The bio-based polyurethane foam formulation according to claim 1, wherein, The catalyst system includes a gelling catalyst at a content of up to 2% by weight and / or a foaming catalyst at a content of up to 0.4% by weight.

10. The bio-based polyurethane foam formulation according to claim 1, wherein, The chemical foaming agent includes water at a content of up to 5% by weight.

11. The bio-based polyurethane foam formulation according to claim 1, wherein, The content of the physical foaming agent is as high as 20% by weight.

12. The bio-based polyurethane foam formulation according to claim 1, wherein, The one or more additives include one or more nucleating agents in an amount of up to 2% by weight.

13. The bio-based polyurethane foam formulation according to claim 1, wherein, The one or more additives include one or more surfactants in an amount of up to 2% by weight.

14. The bio-based polyurethane foam formulation according to claim 1, wherein, The one or more additives include one or more open-cell stabilizers in an amount of up to 5% by weight.

15. The bio-based polyurethane foam formulation according to claim 1, wherein, The one or more additives include one or more chain extenders in an amount of up to 10% by weight.

16. The bio-based polyurethane foam formulation according to claim 1, wherein, The one or more additives include one or more crosslinking agents in an amount of up to 10% by weight.

17. The bio-based polyurethane foam formulation according to claim 1, wherein, The bio-based polyurethane foam has the following characteristics: (a) Compressive strength of at least 25 kPa, (b) Density less than 150 kg / m³, and (c) At least 80% of the structure is open.

18. The bio-based polyurethane foam formulation according to claim 1, wherein, The bio-based polyurethane foam has a predetermined thermal decomposition temperature of at least 260°C, a predetermined tensile strength of at least 1,000 kPa, and a predetermined elongation at break of at least 450%.

19. The bio-based polyurethane foam formulation according to claim 1, wherein, The foam has a bio-based content of more than 80%.

20. A method for producing bio-based polyurethane foam, comprising the following steps: A polyol-based mixture can be formed by combining the following items: (i) 50 to 90% by weight of one or more bio-based polyols derived from renewable resources, (ii) Optional one or more additives, (iii) Catalyst systems, including gelation catalysts and / or foaming catalysts, and (iv) Optional chemical foaming agents, All weight percentages are based on the total recipe.

21. The method according to claim 20, wherein, The method further includes the steps of: forming an isocyanate-based mixture (part B) by combining the following: (i) 40 to 70 weight percent of one or more isocyanates, and (ii) an optional physical blowing agent; combining a polyol-based mixture (part A) with an isocyanate-based mixture (part B) to initiate a foaming reaction; and foaming and curing the reaction mixture in a mold to form the bio-based polyurethane foam.

22. The method according to claim 20, wherein, The method further includes the following steps: adding a flexible foam polyol to the bio-based polyol to form a portion A2; dehydrating the polyol-based chemicals in portion A2; combining the polyol in portion A2 with an isocyanate (portion A1) to initiate a reaction to form a prepolymer solution (portion A); forming a secondary polyol-based mixture (portion B); combining portion A and portion B to initiate a foaming reaction; and foaming and curing the reaction mixture in a mold to form the bio-based polyurethane foam.

23. The method of claim 20, wherein, The bio-based polyol is selected from polyester polyols, polyether polyols, or combinations thereof.

24. The method of claim 20, wherein, The formation of the polyol-based mixture involves mixing at a speed of 1,000 to 10,000 rpm for 1 to 10 minutes in a mixing head or high-shear mixing head.

25. The method according to claim 20, wherein, The mold temperature is maintained at 40 to 90°C for 5 to 60 minutes.

26. The method of claim 20, further comprising demolding the foam and subjecting the foam to post-curing treatment.

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