Polyurethane polystyrene foam added with hyperbranched polyesteramine and preparation method of polyurethane polystyrene foam

Abstract

The invention relates to the technical field of polystyrene foam, in particular to polyurethane polystyrene foam added with hyperbranched polyesteramine and a preparation method of the polyurethane polystyrene foam. The polyurethane polystyrene foam is prepared from 30 to 45 parts of vegetable oil polyol, 15 to 53 parts of polyether polyol, 1 to 5 parts of a foaming agent, 0.5 to 4 parts of a foam stabilizer, 1 to 1.5 parts of nano filler, 1.5 to 2 parts of hyperbranched polyesteramine, 60 to 80 parts of isocyanate and 0.05 to 0.3 part of a catalyst; the hyperbranched polyesteramine branched chain terminal amino group and the hydroxyl group in the polyhydric alcohol form a reversible hydrogen bond, so that the stability of the polyurethane foaming adhesive system is improved, layering in a static state can be prevented, and the mechanical property of the polyurethane foaming adhesive is improved.

Description

Technical Field

[0001] The invention relates to the technical field of foaming glue, in particular to a polyurethane foaming glue added with hyperbranched polyesteramine and a preparation method thereof. Background Art

[0002] Polyurethane foam is a relatively common adhesive, generally used in the fields of automobiles, building decoration, electrical appliances, etc. It is mainly used as a special product for filling, bonding, sealing, and sound insulation and heat insulation purposes.

[0003] Polyurethane foams are primarily divided into two categories: two-component and one-component. Two-component polyurethane fillers require mixing in a specific ratio and curing at room temperature. This makes them inconvenient to use, requiring time and labor for mixing and metering. Furthermore, they require mixing as needed, which can lead to waste. One-component polyurethane foams avoid these shortcomings. They are typically made by reacting polyester polyol resins, polyether polyol resins, and isocyanates to form an elastic cured product that bonds gaps between substrate materials.

[0004] Existing single-component polyurethane foam has poor mechanical properties, especially poor adhesive properties and poor stability, which greatly affects the expansion of the application field and application environment of polyurethane foam.

[0005] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a polyurethane foam added with a hyperbranched polyesteramine and a preparation method thereof. The terminal amino groups of the hyperbranched polyesteramine side chains form reversible hydrogen bonds with the hydroxyl groups in the polyol, thereby improving the stability of the polyurethane foam system, preventing stratification in a static state, and improving the mechanical properties of the polyurethane foam.

[0007] The first object of the present invention is to provide a polyurethane foam with added hyperbranched polyester amine, wherein the polyurethane foam comprises, by weight:

[0008]

[0009]

[0010] As a preferred embodiment of the present invention, the hyperbranched polyester amine is a hyperbranched structure generated by Michael addition reaction of trimethylolpropane as a core with dimethylaminoethyl acrylate;

[0011] More specifically, the synthesis reaction of hyperbranched polyesteramine is based on the Michael addition reaction of trimethylolpropane (TMP) and dimethylaminoethyl acrylate (DMAEA), and the specific reaction equation is as follows:

[0012] TMP-(OH)3+3CH2=CHCOOCH2CH2N(CH3)2→TMP-(O-CH2-CH(COOCH2CH2N(CH3)2))3+3H2O;

[0013] The hydroxyl group (-OH) of TMP acts as a nucleophile, attacking the β-carbon of the α,β-unsaturated ester in dimethylaminoethyl acrylate. The oxygen atom of the hydroxyl group forms a new CO bond with the β-carbon, and the double bond is transferred between the α and γ positions to form a saturated structure. The three hydroxyl groups of TMP react with three molecules of DMAEA in sequence to form a three-arm branched structure with TMP as the core. In subsequent reactions, the active groups at the ends of each arm can continue to participate in addition to form a hyperbranched polymer with a highly branched three-dimensional structure. In this process, the core molecule continuously expands its branches outward, eventually forming a large number of terminal amino groups distributed on the periphery.

[0014] The terminal amino groups on the periphery of hyperbranched polyester amine can form a reversible hydrogen bond network with the hydroxyl groups of polyols (such as vegetable oil polyols and polyether polyols) in the polyurethane system, tightly connecting different components like molecular-level anchor points, effectively inhibiting the sedimentation and phase separation of fillers, making the raw materials easier to disperse evenly during the mixing process, and fundamentally solving the stability defects of traditional single-component polyurethane foams caused by static stratification.

[0015] As a preferred embodiment of the present invention, the nanofiller is a compound of nano-silica modified with a silane coupling agent and carbon nanotubes;

[0016] More specifically, the surface of nano-silica contains a large number of hydroxyl groups. When modified by an aminosilane coupling agent (such as KH550), the siloxy group (-SiOR) at one end of the silane coupling agent molecule reacts with the hydroxyl group (-OH) on the surface of the nano-silica to form a covalent bond (Si-O-Si). The amino group (-NH 2 ) is exposed to the surface, turning the hydrophilic nano-silica surface into an organophilic one, thereby enhancing the compatibility with the polyurethane matrix. The reaction equation is:

[0017] SiO2-OH+NH2(CH2)3Si(OR)3→SiO2-O-Si(CH2)3NH2+ROH;

[0018] The amino groups on the surface of the modified nano-silica can react chemically with the isocyanate groups (-NCO) to form urea bonds (-NH-CO-NH-), firmly anchoring the nano-fillers in the polyurethane matrix to form a chemically bonded interface. The reaction equation is:

[0019] -NH2+O=C=NR→-NH-CO-NH-R;

[0020] Carbon nanotubes have a highly conjugated graphite layer structure, which adsorbs polyurethane molecular chains through π-π interactions, forming a three-dimensional network physical entanglement structure in the matrix, enhancing the mechanical transmission efficiency of the material. Although carbon nanotubes do not chemically react with polyurethane components, their high aspect ratio and surface energy properties make them efficient physical reinforcement fillers, hindering crack propagation through the bridge effect.

[0021] Modified nano-silica provides rigid support through chemical bonding, carbon nanotubes enhance toughness and dispersibility through physical entanglement, and hyperbranched polyesteramine achieves molecular-level stability through a hydrogen bond network. The three form a composite mechanism of chemical anchoring-physical entanglement-hydrogen bond stabilization, which jointly inhibits filler agglomeration and prevents phase separation, ultimately improving the storage stability and construction uniformity of polyurethane foam.

[0022] As a preferred embodiment of the present invention, the vegetable oil polyol is at least one of castor oil polyol and soybean oil polyol; both are bio-based vegetable oil polyols, containing multiple hydroxyl groups in their molecular structure, which can undergo cross-linking reaction with isocyanate to form a polyurethane network, and their long-chain hydrocarbon structure has compatibility advantages with the polar groups of polyether polyols and hyperbranched polyester amines, and forms hydrogen bonds with the terminal amino groups of hyperbranched polyester amines through hydroxyl groups, thereby synergistically improving the stability of the system; in addition, castor oil polyol can provide a higher cross-linking density to enhance mechanical strength due to its ricinoleic acid structure with a high hydroxyl content, and the long-chain flexible structure of soybean oil polyol can improve the toughness of foamed rubber. The use of the two alone or in combination can balance the rigidity and elasticity of the material and improve the mechanical properties.

[0023] As a preferred embodiment of the present invention, the foaming agent is water; water, as a chemical foaming agent, can react with isocyanate (-NCO) to generate carbon dioxide (CO2) gas. The specific reaction is:

[0024] R-NCO+H2O→R-NH2+CO2↑;

[0025] The generated carbon dioxide gas forms bubbles in the system, causing the polyurethane foam to expand and foam; at the same time, the amino groups generated by the reaction can further react with isocyanate to form urea bonds, increasing the cross-linking density of the polymer and improving the mechanical properties;

[0026] Water is non-toxic and releases no volatile organic compounds, meeting the requirements of green chemistry and environmental protection. Water has good compatibility with polyols and can directly participate in the reaction without the need for additional solvents, simplifying the preparation process. The foaming process is highly controllable, making it easy to adjust the foam density and pore structure. The urea bond generated by the reaction of water and isocyanate is stronger than ordinary urethane bonds, and can significantly improve the mechanical properties of the foam, such as tensile strength and bonding strength.

[0027] As a preferred embodiment of the present invention, the foam stabilizer is silicone oil. Silicone oil is selected as the foam stabilizer because it has low surface tension and chemical inertness. It can be adsorbed on the bubble interface during the polyurethane foaming process to form an elastic film layer, and inhibits bubble merging or rupture by reducing the gas-liquid interfacial tension, thereby regulating a fine and uniform foam structure. At the same time, silicone oil has good compatibility with components such as polyols and isocyanates and does not participate in the main reaction. It can remain stable over a wide temperature range to adapt to the exothermic foaming environment. Its smooth molecular chain can also assist in the uniform dispersion of nanofillers through physical space steric effect, thereby reducing particle agglomeration. In addition, the physical steric effect of silicone oil and the chemical hydrogen bond network formed by hyperbranched polyester amine through terminal amino groups and polyol hydroxyl groups form a synergistic effect. The former physically blocks direct contact between filler particles, and the latter chemically anchors the filler to the polymer molecular chain, jointly forming a stabilization mechanism to prevent system stratification, thereby improving the uniformity of mechanical properties and storage stability of the foamed adhesive.

[0028] As a preferred embodiment of the present invention, the catalyst includes a tertiary amine catalyst and an organotin catalyst; the tertiary amine catalyst mainly accelerates the chemical reaction between isocyanate and water, prompting the foaming agent water to quickly generate carbon dioxide gas and uniformly nucleate, and controls the bubble generation rate to avoid uneven foaming or gas escape; the organotin catalyst efficiently catalyzes the reaction between isocyanate and the hydroxyl group of the polyol to generate carbamate bonds, quickly constructing a polyurethane cross-linked network to enhance the foam skeleton strength; the two are used in combination to avoid the reaction imbalance caused by a single catalyst, thereby synergistically optimizing the foaming efficiency, foam uniformity, and mechanical properties such as tensile strength and compressive strength of the foam glue.

[0029] As a preferred embodiment of the present invention, the weight ratio of the tertiary amine catalyst to the organotin catalyst is 6-7:1-2. This ratio ensures that the foaming reaction rate of the isocyanate and water is faster than the cross-linking reaction by prioritizing the dominant role of the tertiary amine catalyst, so that carbon dioxide gas is uniformly generated and nucleated in a timely manner, providing sufficient expansion power for the foam structure. The organotin catalyst catalyzes the cross-linking reaction rate of the isocyanate and the polyol to form a dynamic balance with the foaming rate, thereby avoiding too slow cross-linking that causes the foam skeleton to be soft and easy to break, and preventing excessive organotin from causing too fast cross-linking and hindering bubble expansion.

[0030] As a preferred embodiment of the present invention, the organotin catalyst is dibutyltin dilaurate or dibutyltin diacetate, and the tertiary amine catalyst is N,N-dimethylcyclohexylamine; the tin atom active center in the molecular structure of dibutyltin dilaurate and dibutyltin diacetate has high catalytic selectivity for the reaction between isocyanate (-NCO) and the hydroxyl group of the polyol, can quickly promote the formation of carbamate bonds, accelerate the construction of the polyurethane cross-linking network, and significantly improve the mechanical properties of the foam, such as tensile strength and compressive strength; the ligand laurate or acetate group has good compatibility with the long-chain hydrocarbon group of the vegetable oil polyol in the system, reduces catalyst agglomeration or side reactions, and ensures that the cross-linking reaction proceeds uniformly;

[0031] The cyclic tertiary amine structure of N,N-dimethylcyclohexylamine has unique catalytic activity for the foaming reaction of isocyanate and water. By activating the hydrogen atoms of water, it accelerates the generation of carbon dioxide (CO2) gas and controls the bubble nucleation rate, making the foam pore size fine and uniform, avoiding foaming defects caused by uneven gas generation.

[0032] A second object of the present invention is to provide a method for preparing the polyurethane foam adhesive added with a hyperbranched polyesteramine, comprising:

[0033] S1 Weigh all raw materials according to weight ratio; the nanofiller needs to be ultrasonically dispersed for 30-60 minutes, using the high-frequency vibration energy of ultrasound to destroy the van der Waals force agglomeration between the nanofiller particles, dispersing them into nanoscale single particles or small aggregates, significantly improving the dispersion uniformity of the filler in the polyol matrix;

[0034] S2: The vegetable oil polyol, polyether polyol, hyperbranched polyester amine and nanofiller are mixed and then ball-milled; during the ball-milling process, the terminal amino group of the hyperbranched polyester amine and the hydroxyl group of the polyol are accelerated to form a hydrogen bond pre-network during the dynamic mixing of the ball mill, and the amino group or π electron structure on the surface of the nanofiller is anchored to the polyol molecular chain through intermolecular forces, thereby enhancing the interfacial compatibility between the filler and the matrix, laying a foundation for uniform reaction for the subsequent chemical bonding after the addition of isocyanate, and at the same time, through the synergy of the flexible chain segment of the polyether polyol and the long chain structure of the vegetable oil polyol, the viscosity and rheology of the system are improved, thereby ensuring the dispersion efficiency and reaction uniformity when subsequent components such as blowing agents and catalysts are added;

[0035] S3 then adds a blowing agent and a foam stabilizer, stirs evenly, and then adds isocyanate, and then adds a catalyst, and stirs evenly to obtain a polyurethane foam;

[0036] Isocyanate is the core component of the polyurethane cross-linking reaction. Adding it after the polyol, nanofiller, and foaming agent are fully mixed can prevent premature reaction with water or polyol, which would cause a sudden increase in the system viscosity. It ensures that the isocyanate is evenly diffused throughout the system, providing sufficient reaction sites for subsequent cross-linking reactions.

[0037] Finally, the addition of a catalyst can precisely control the time difference between the foaming reaction and the cross-linking reaction, first forming a uniformly dispersed prepolymer system, and then initiating a two-way reaction through the catalyst to achieve dynamic matching between the bubble expansion process and the matrix curing process, avoiding foam collapse or restricted foaming due to reaction imbalance, and ultimately obtaining a polyurethane foam with fine pores and stable structure.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1) In the present invention, the terminal amino groups of the hyperbranched polyester amine form reversible hydrogen bonds with the hydroxyl groups of the polyol, tightly connecting the nanofiller to the polymer molecular chain and inhibiting the sedimentation of the filler due to gravity or polarity differences. After the modified nanosilica is treated with aminosilane, the surface organophilicity is enhanced, and its amino groups react with isocyanate to form urea bonds, so that the filler is fixed in the polyurethane matrix through chemical bonding. The carbon nanotubes, by virtue of their high aspect ratio and π-π interaction, adsorb the polymer chains to form a physical entanglement network, hindering particle agglomeration. The silicone oil stabilizes the bubble interface by virtue of its low surface tension and assists in the dispersion of the filler through steric hindrance. The hydrogen bonding effect with the hyperbranched polyester amine forms a composite stabilization mechanism, ensuring that the system is not easily delaminated during storage and is uniformly dispersed during construction.

[0040] 2) The urea bond generated by the reaction of modified nano-silica and isocyanate serves as a high-strength connecting node to enhance the tensile strength of the material; the three-dimensional physical entanglement network of carbon nanotubes hinders crack propagation and improves toughness; hyperbranched polyester amine promotes uniform dispersion of fillers to avoid local stress concentration; castor oil polyol provides high cross-linking density to enhance strength, and the long-chain structure of soybean oil polyol improves flexibility, synergistically balancing the rigidity and elasticity of the material with polyether polyol; tertiary amines and organotin catalysts are compounded in proportion to precisely control the foaming reaction of water and isocyanate and the cross-linking reaction rate of polyol and isocyanate, so that the bubble expansion and foam skeleton curing are synchronized to form a fine and uniform pore structure, and ultimately the tensile strength, bonding strength and other properties are significantly improved compared to traditional formulas. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The present invention is a schematic flow chart of a method for preparing a polyurethane foam containing hyperbranched polyesteramine. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0043] The sources of raw materials used in this specific embodiment are as follows:

[0044] Castor oil polyol, Guangzhou Chubu Chemical Co., Ltd.

[0045] Soybean oil polyol, Guangzhou Haierma Vegetable Oil Co., Ltd.

[0046] Silicone oil, Wacker Group, Germany.

[0047] N,N-Dimethylcyclohexylamine, Hubei Chengfeng Chemical Co., Ltd.

[0048] Dibutyltin dilaurate, Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0049] Carbon nanotubes, Jiangsu Tiannai Technology Co., Ltd.

[0050] Aminosilane coupling agent KH550, Shandong Hengyu New Materials Co., Ltd.

[0051] Nano-silicon dioxide, Sanming Fengrun Chemical Co., Ltd.

[0052] Trimethylolpropane, Shandong Xuchen Chemical Technology Co., Ltd.

[0053] Dimethylaminoethyl acrylate (DMAEA) was purchased from Jinan Century Tongda Chemical Co., Ltd.

[0054] Example 1:

[0055] A polyurethane foam with hyperbranched polyesteramine added, comprising the following components in parts by mass:

[0056]

[0057] The vegetable oil polyol is castor oil polyol, the foaming agent is water, the foam stabilizer is silicone oil, and the catalyst is N,N-dimethylcyclohexylamine and dibutyltin dilaurate in a weight ratio of 6:2.

[0058] The nanofiller is silane coupling agent modified nano-silica and carbon nanotubes in a weight ratio of 2:1, wherein the modified nano-silica is obtained by soaking and modifying the nano-silica in an aminosilane coupling agent KH550-ethanol solution with a mass concentration of 1%.

[0059] Hyperbranched polyester amine is a hyperbranched structure generated by Michael addition reaction of trimethylolpropane as the core and dimethylaminoethyl acrylate (DMAEA). The specific steps are as follows:

[0060] TMP and DMAEA are added to a reactor equipped with a stirrer and a condenser, an anhydrous solvent (such as anhydrous methanol) is added, and nitrogen is introduced to expel air; the mixture is heated to 60-80°C under constant temperature and stirring to initiate an addition reaction, whereby the hydroxyl group of TMP acts as a nucleophile to attack the β-carbon of the α,β-unsaturated ester in DMAEA, forming a new CO bond accompanied by double bond transfer, thereby generating a three-arm branched intermediate with TMP as the core; the reaction conditions are maintained, and the active groups at the ends of the intermediate arms are continuously used to undergo subsequent addition reactions with excess DMAEA. By controlling the reaction time and the replenishment of raw materials, the branched structure is continuously expanded outward, ultimately forming a highly branched three-dimensional hyperbranched polymer; after completion of the reaction, the solvent is removed by distillation under reduced pressure, and the remaining product is precipitated, filtered, and vacuum-dried to obtain a hyperbranched polyesteramine solid containing a large number of peripheral terminal amino groups.

[0061] A method for preparing a polyurethane foam added with a hyperbranched polyesteramine comprises the following steps:

[0062] (1) Weigh the raw materials in various weight proportions and ultrasonically disperse the nanofiller for 40 min;

[0063] (2) mixing vegetable oil polyol, polyether polyol, hyperbranched polyester amine, and nanofiller and then ball milling;

[0064] (3) Then add the foaming agent and foam stabilizer and stir evenly, then continue to add isocyanate, then add the catalyst, stir evenly to obtain the polyurethane foam.

[0065] Example 2

[0066] A polyurethane foam with hyperbranched polyesteramine added, comprising the following components in parts by mass:

[0067]

[0068]

[0069] Among them, the vegetable oil polyol is soybean oil polyol, the foaming agent is water, the foam stabilizer is silicone oil, and the catalyst is N,N-dimethylcyclohexylamine and dibutyltin dilaurate in a weight ratio of 7:2.

[0070] The nanofiller is nano-silica modified with a silane coupling agent and carbon nanotubes in a weight ratio of 2:1. The preparation method of the modified nano-silica is the same as that in Example 1.

[0071] The hyperbranched polyester amine is a hyperbranched structure generated by Michael addition reaction of trimethylolpropane as a core with dimethylaminoethyl acrylate (DMAEA). The preparation method is the same as that in Example 1.

[0072] A method for preparing a polyurethane foam added with a hyperbranched polyesteramine comprises the following steps:

[0073] (1) Weigh the raw materials in various weight proportions and ultrasonically disperse the nanofiller for 40 minutes.

[0074] (2) mixing vegetable oil polyol, polyether polyol, hyperbranched polyester amine, and nanofiller and then ball milling;

[0075] (3) Then add the foaming agent and foam stabilizer and stir evenly, then continue to add isocyanate, then add the catalyst, stir evenly to obtain the polyurethane foam.

[0076] Example 3

[0077] A polyurethane foam with hyperbranched polyesteramine added, comprising the following components in parts by mass:

[0078]

[0079] Among them, the vegetable oil polyol is castor oil polyol, the foaming agent is water, the foam stabilizer is silicone oil, and the catalyst is N,N-dimethylcyclohexylamine and dibutyltin dilaurate in a weight ratio of 6:2.

[0080] The nanofiller is nano-silica modified with a silane coupling agent and carbon nanotubes in a weight ratio of 3:2. The preparation method of the modified nano-silica is the same as that in Example 1.

[0081] The hyperbranched polyester amine is a hyperbranched structure generated by Michael addition reaction of trimethylolpropane as a core with dimethylaminoethyl acrylate (DMAEA). The preparation method is the same as that in Example 1.

[0082] A method for preparing a polyurethane foam added with a hyperbranched polyesteramine comprises the following steps:

[0083] (1) Weigh the raw materials in different weight proportions. The nanofiller needs to be ultrasonically dispersed for 40 minutes.

[0084] (2) mixing vegetable oil polyol, polyether polyol, hyperbranched polyester amine, and nanofiller and then ball milling;

[0085] (3) Then add the foaming agent and foam stabilizer and stir evenly, then continue to add isocyanate, then add the catalyst and stir evenly until the polyurethane foam is formed.

[0086] Comparative Example 1: The difference from Example 1 is that no hyperbranched polyesteramine is added;

[0087] A polyurethane foam adhesive, comprising the following components in parts by mass:

[0088]

[0089] The vegetable oil polyol is castor oil polyol, the foaming agent is water, the foam stabilizer is silicone oil, and the catalyst is N,N-dimethylcyclohexylamine and dibutyltin dilaurate in a weight ratio of 6:2.

[0090] The nanofiller is silane coupling agent modified nano-silica and carbon nanotubes in a weight ratio of 2:1, wherein the modified nano-silica is obtained by soaking and modifying the nano-silica in an aminosilane coupling agent KH550-ethanol solution with a mass concentration of 1%.

[0091] A method for preparing polyurethane foam comprises the following steps:

[0092] (1) Weigh the raw materials in various weight proportions and ultrasonically disperse the nanofiller for 40 min;

[0093] (2) mixing the vegetable oil polyol, polyether polyol, and nanofiller and then ball milling;

[0094] (3) Then add the foaming agent and foam stabilizer and stir evenly, then continue to add isocyanate, then add the catalyst, stir evenly to obtain the polyurethane foam.

[0095] Comparative Example 2: The difference from Example 1 is that no nanofiller is added;

[0096] A polyurethane foam with hyperbranched polyesteramine added, comprising the following components in parts by mass:

[0097]

[0098]

[0099] The vegetable oil polyol is castor oil polyol, the foaming agent is water, the foam stabilizer is silicone oil, and the catalyst is N,N-dimethylcyclohexylamine and dibutyltin dilaurate in a weight ratio of 6:2.

[0100] The hyperbranched polyester amine is a hyperbranched structure generated by Michael addition reaction of trimethylolpropane as a core with dimethylaminoethyl acrylate (DMAEA). The preparation method is the same as that in Example 1.

[0101] A method for preparing a polyurethane foam added with a hyperbranched polyesteramine comprises the following steps:

[0102] (1) Weigh the raw materials in each weight ratio;

[0103] (2) mixing vegetable oil polyol, polyether polyol, and hyperbranched polyester amine and then ball milling;

[0104] (3) Then add the foaming agent and foam stabilizer and stir evenly, then continue to add isocyanate, then add the catalyst, stir evenly to obtain the polyurethane foam.

[0105] The surface drying time and tensile strength of the polyurethane foams of Examples 1-3 and Comparative Examples 1-2 were tested as follows:

[0106] Surface drying time: evenly apply the polyurethane foam product sample on the clean surface of the scraper fineness gauge with a thickness of 0.3mm. After the product sample is placed for a certain period of time at room temperature, a smooth corrugated paper vertical surface is freely dropped from a height of 3cm to the surface of the product sample. There is no adhesion or stringing phenomenon.

[0107] Tensile test: After pre-treatment, a 0.5mm thick plate is made into a sample with an area of ​​120mm*150mm. A production foam scraper is used to evenly brush a layer of product sample on the surface of the sample. The honeycomb paper is fixed in the sample. After hot pressing, the sample is placed at room temperature for 6 hours, and then placed in a constant temperature oven at coking point temperature for high temperature baking for 25 minutes. After baking, it is placed at room temperature for temperature balance for 2 hours; the tensile test of the hot pressed and baked samples is carried out using a universal testing machine.

[0108] The test results are shown in Table 1.

[0109] Table 1 Test results of surface drying time and tensile strength of polyurethane foams of Examples 1-3 and Comparative Examples 1-2

[0110] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Surface drying time (min) 10 12 9 16 12 Tensile strength (kg) 34 37 43 20 22

[0111] As can be seen from Table 1, Examples 1-3 add hyperbranched polyester amine and nanofiller. The former forms a hydrogen bond network anchoring the filler and inhibiting agglomeration through the terminal amino group and the polyol hydroxyl group, and the modified nanosilica reacts with the isocyanate to form urea bonds and the carbon nanotubes form a physical entanglement network. The two synergistically improve the dispersion uniformity and mechanical properties of the system. Combined with the catalyst compound to control the reaction rate matching, the surface dry time is shortened and the tensile strength is significantly enhanced.

[0112] In Comparative Example 1, no hyperbranched polyesteramine was added. The nanofiller lacked hydrogen bond anchoring during the mixing process, resulting in only physical mixing in the ball milling step. The amino groups on the surface of the modified silica and the hydroxyl groups of the polyol could not be effectively connected through the hyperbranched structure, forming local agglomerates. These agglomerates became stress concentration points during the foaming process, causing the tensile strength to drop to 20 kg. At the same time, due to the uneven reaction interface, the contact area between the isocyanate, water, and polyol was reduced, resulting in asynchronous foaming and cross-linking reactions, and the surface drying time was extended to 16 minutes.

[0113] In Comparative Example 2, no nanofiller was added. The system lacked the rigid chemical bonding points provided by modified silica and the physically reinforced network of carbon nanotubes. The polyurethane matrix was cross-linked only by intermolecular forces, and there was no barrier mechanism when the cracks expanded. The tensile strength was only 22 kg. In addition, the lack of nanofillers caused the rheological properties of the system to deteriorate. The foam stabilization effect of the silicone oil was limited due to the lack of particle assistance, and the pore structure was uneven. Although the surface drying time was close to that of Example 2, the mechanical properties were significantly reduced, verifying the synergistic key role of hyperbranched polyesteramine and nanofillers in constructing a stable dispersion system and enhancing mechanical properties.

[0114] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A polyurethane foam with a hyperbranched polyester amine added, characterized in that: The polyurethane foam comprises, by weight: 30-45 parts of vegetable oil polyols; 15-53 parts of polyether polyol; 1-5 parts of foaming agent; Foam stabilizer 0.5-4 parts; 1-1.5 parts of nanofiller; 1.5-2 parts of hyperbranched polyesteramine; 60-80 parts of isocyanate; Catalyst 0.05-0.3 parts.

2. The polyurethane foam adhesive added with a hyperbranched polyester amine as claimed in claim 1, wherein The hyperbranched polyester amine is a hyperbranched structure generated by Michael addition reaction of trimethylolpropane as a core and dimethylaminoethyl acrylate.

3. The polyurethane foam adhesive added with a hyperbranched polyester amine as claimed in claim 1, wherein The nano filler is a compound of silane coupling agent-modified nano silicon dioxide and carbon nano tubes.

4. The polyurethane foam adhesive added with a hyperbranched polyester amine as claimed in claim 1, wherein The vegetable oil polyol is at least one of castor oil polyol and soybean oil polyol.

5. The polyurethane foam adhesive added with hyperbranched polyesteramine as claimed in claim 1, characterized in that The foaming agent is water.

6. The polyurethane foam adhesive added with hyperbranched polyester amine as claimed in claim 1, characterized in that The foam stabilizer is silicone oil.

7. The polyurethane foam adhesive added with hyperbranched polyesteramine as claimed in claim 1, characterized in that The catalyst includes a tertiary amine catalyst and an organotin catalyst.

8. The polyurethane foam adhesive added with hyperbranched polyesteramine as claimed in claim 7, characterized in that The weight ratio of the tertiary amine catalyst to the organotin catalyst is 6-7:1-2.

9. The polyurethane foam adhesive added with hyperbranched polyesteramine as claimed in claim 7, characterized in that The organic tin catalyst is dibutyltin dilaurate or dibutyltin diacetate, and the tertiary amine catalyst is N,N-dimethylcyclohexylamine.

10. The method for preparing a polyurethane foamed adhesive added with a hyperbranched polyesteramine according to any one of claims 1 to 9, wherein: include: Weigh each raw material according to weight ratio; The vegetable oil polyol, the polyether polyol, the hyperbranched polyester amine and the nanofiller are mixed and then ball-milled; Then, the foaming agent and the foam stabilizer are added, and after being stirred evenly, the isocyanate is added, and then the catalyst is added, and stirred evenly to obtain the polyurethane foam.

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