Bio-based flame-retardant polyurethane foam adhesive

Abstract

The present application belongs to the technical field of polyurethane, and particularly relates to a bio-based flame-retardant polyurethane foaming adhesive. The bio-based flame-retardant polyurethane foaming adhesive is composed of the following raw materials in parts by weight: amino acid-based modified polyether polyol: 60-75 parts; nitrogen and phosphorus-containing hydroxyl-terminated modified polymer: 25-40 parts; modified isocyanate: 380-440 parts; chlorinated paraffin: 100-130 parts; filler: 40-60 parts; silicone oil: 8-10 parts; propellant: 80-100 parts; catalyst: 3-5 parts. By introducing bio-based raw materials such as castor oil and amino acid into the molecular structure of the polyurethane foaming adhesive through chemical modification, the biodegradability of the material is improved; by screening suitable polymer monomers, the flame-retardant element-chlorine is introduced into the polyether molecular structure through chemical polymerization, and the nitrogen and phosphorus elements are bridged through ester bonds to form a multi-element synergy, effectively increasing the content of the flame-retardant element in the foaming adhesive material and improving the flame retardancy.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane technology, specifically relating to bio-based flame-retardant polyurethane foam. Background Technology

[0002] Polyurethane foam materials are widely used in everyday life applications such as carpets, furniture, and transportation. However, polyurethane foam is a highly flammable polymer, and flame retardancy remains a significant challenge for the industry. Besides traditional additive flame retardants, flame-retardant polyethers have evolved to include various flame retardant methods such as biomass flame retardancy, halogen flame retardancy, and phosphorus-based flame retardancy. Biomass flame retardancy methods, such as those using phosphorus-containing castor oil or straw liquefaction, are costly and have low yields, making them difficult to compete with traditional halogen flame retardants. Phosphorus-nitrogen flame retardants, as a new type of high-efficiency additive flame retardant, possess good thermal stability, low water solubility, long-lasting flame retardant performance, and low toxicity. They also overcome the poor compatibility of small-molecule phosphorus-based flame retardants with the flame-retarded materials, and have experienced rapid development in the past 20 years. The addition of nitrogen to phosphorus-based flame retardants often enhances thermal stability, overcomes hydrolysis, and reduces smoke production. Phosphorus-nitrogen intumescent flame retardants can form a pyrophosphate protective film when heated and decompose, and then form an expanded foam-like carbon layer structure, which plays a role in heat insulation and oxygen barrier.

[0003] Chinese patent application CN102633972A, published on August 15, 2012, discloses a method for preparing a phosphorus halogen synergistic flame-retardant polyether polyol, which involves hydrolyzing epichlorohydrin followed by reaction with a halogenated aromatic diphenol product; however, the process is relatively cumbersome. Chinese patent application CN118005882A, published on May 10, 2024, discloses a highly flame-retardant rigid polyurethane foam insulation material, using hydrobromic acid as the halogen source, but the process involves concentrated sulfuric acid, posing a high risk to safe operation. Chinese patent application CN104004175A, published on August 31, 2016... A flame-retardant polyether polyol, a combined polyether, and a polyurethane foam are disclosed. The process involves diethanolamine and triethyl phosphite in a solvent, followed by vacuum distillation to obtain a nitrogen- and phosphorus-containing initiator. This initiator is then combined with a multifunctional hydroxyl compound to synthesize the flame-retardant polyether. However, the process is complex, and the unstable nature of diethanolamine leads to harsh reaction conditions. Chinese patent application CN120554585A, published on August 29, 2025, discloses a multi-component synergistic flame-retardant polymer polyol. In this polyol, a halogen-containing monomer introduced into the POP polymer monomer directly participates in free polymerization, synergistically interacting with the flame-retardant elements in the basic polyether. However, the improvement in flame-retardant effect is not significant. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a bio-based flame-retardant polyurethane foam. By introducing bio-based raw materials such as castor oil and amino acids into the polyether polyol structure for foam preparation, the biodegradability of the material can be improved.

[0005] This invention is achieved using the following technical solution:

[0006] The aforementioned bio-based flame-retardant polyurethane foam is composed of the following raw materials in parts by weight:

[0007] Amino acid-based modified polyether polyol: 60-75 parts;

[0008] Nitrogen- and phosphorus-terminated hydroxyl-modified polymers: 25-40 parts;

[0009] Modified isocyanate: 380~440 parts;

[0010] Chlorinated paraffin: 100-130 parts;

[0011] Filler: 40-60 parts;

[0012] Silicone oil: 8-10 parts;

[0013] Propellant: 80-100 parts;

[0014] Catalyst: 3-5 parts.

[0015] Preferably, the amino acid-based modified polyether polyol is obtained by polymerizing epichlorohydrin with alanine and castor oil (functionality 2.7, hydroxyl value 162 mg KOH / g) as initiators under the action of a catalyst; the number average molecular weight is 550-700 g·mol⁻¹. -1 Its functionality is 2.2.

[0016] Preferably, the preparation steps of the nitrogen-phosphorus-terminated hydroxyl-modified polymer are as follows: adding dicarboxylic acid, trimethylolphosphine oxide, and p-toluenesulfonic acid into a reactor equipped with a condenser, purging with nitrogen three times, heating to 150-170°C, stirring the reaction, and continuously separating and distilling off byproducts through a distillation column during the reaction, and reacting for 6-8 hours; the molar ratio of dicarboxylic acid to trimethylolphosphine oxide is 1:2.05; and the amount of p-toluenesulfonic acid catalyst is 500-800 ppm of the total amount of dicarboxylic acid and trimethylolphosphine oxide.

[0017] Preferably, the dicarboxylic acid is either aspartic acid or glutamic acid.

[0018] Preferably, the preparation steps of the modified isocyanate are as follows: adding flame-retardant polyether polyol to a reaction vessel, heating to 100~120℃, vacuum dehydrating to a moisture content of <0.05wt.%, cooling to 60~80℃, adding isocyanate, and reacting until the -NCO content is 27~33wt.%, wherein the mass ratio of isocyanate to flame-retardant polyether is 100:(32~41).

[0019] Preferably, the flame-retardant polyether polyol is obtained by polymerizing propylene oxide with dibromoneopentyl glycol and INOVOL C204 as initiators under the action of a catalyst; the number average molecular weight is 600 g·mol⁻¹. -1 Its functionality is 2.

[0020] Preferably, the isocyanate is toluene diisocyanate and polymethylene polyphenyl isocyanate.

[0021] Preferably, the filler is expanded graphite. By introducing nano-flame-retardant fillers, an organic-inorganic composite flame-retardant system is constructed to reduce the smoke toxicity of the foam.

[0022] Preferably, the catalyst is DMDEE.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) By introducing bio-based raw materials such as castor oil and amino acids into the structure of polyether polyols for use in the preparation of foam, the biodegradability of the material can be improved.

[0025] (2) Nitrogen and phosphorus elements are introduced into nitrogen- and phosphorus-terminated hydroxyl-modified polymers through ester bond bridging. The synthesis method is simple, low-cost, and easy to industrialize. It works synergistically with chlorine elements in amino acid-based modified polyether polyols and directly participates in the reaction, effectively increasing the content of flame-retardant elements in foamed materials and thus improving their flame retardancy.

[0026] (3) Use bromine-containing flame-retardant polyether polyols to modify isocyanates, introduce bromine into the isocyanate structure, realize the intrinsic flame-retardant properties of the material, and avoid the risk of migration caused by the use of flame retardants. Detailed Implementation

[0027] To make the objectives and technical solutions of this invention clearer, the invention will be further described in detail below.

[0028] Unless otherwise specified, all raw materials used in the examples were commercially available.

[0029] The following is a description of some of the raw materials used in the examples and comparative examples:

[0030] Tris(hydroxymethyl)phosphine oxide (THPO), Hubei Xingfa Group;

[0031] Dibromonepentylene glycol, Jiangsu Zhenri Chemical Co., Ltd.;

[0032] Silicone oils: QG-8526, QG-6855, Shanghai Qiguang Industry & Trade Co., Ltd.;

[0033] INOVOL C204 (hydroxyl value 280mgKOH / g, functionality 2), Shandong Yinuowei New Materials Co., Ltd.

[0034] INOVOL C206 (hydroxyl value 187mgKOH / g, functionality 2), Shandong Yinuowei New Materials Co., Ltd.

[0035] Toluene diisocyanate (2,4) TDI is approximately 80%, 2,6 TDI (approximately 20%), Wanhua Chemical Group Co., Ltd.

[0036] Polymethylene polyphenyl isocyanate, Wanhua Chemical Group Co., Ltd.;

[0037] The method for preparing the flame-retardant polyether polyol is as follows: 393g of dibromoneopentyl glycol, 600g of INOVOL C204, and 0.93g of DMC catalyst are added to a high-pressure reactor. The temperature is raised to 130℃, and 80g of propylene oxide is added dropwise to initiate the reaction. After the pressure drops to -0.08MPa, the remaining 830g of propylene oxide is gradually added dropwise to the reactor, controlling the pressure inside the reactor to ≤0.3MPa. After the reaction is completed, the monomer is removed for 0.5h to obtain the flame-retardant polyether polyol with a functionality of 2 and a number-average molecular weight of 600g·mol⁻¹. -1 .

[0038] Example 1

[0039] The preparation steps of the amino acid-based modified polyether polyol are as follows: 445g of alanine, 1870g of castor oil (hydroxyl value of 162mgKOH / g), and 2.24g of boron trifluoride catalyst are added to a pressure-resistant reactor. The temperature is raised to 100℃, the vacuum is evacuated to -0.09MPa, and nitrogen is purged for 2 hours to remove small molecule monomers and water. Nitrogen is then introduced, and 2170g of epichlorohydrin is added dropwise. After the addition is complete, the reaction is carried out for 2 hours. Vacuum is then applied to remove unreacted residual monomers to obtain the amino acid-based modified polyether polyol with Mn of 600g / mol and functionality of 2.2.

[0040] The preparation steps of the nitrogen-phosphorus-terminated hydroxyl-modified polymer are as follows: 147g of glutamic acid, 287g of tris(hydroxymethyl)phosphonium oxide and 0.217g of p-toluenesulfonic acid are added to a reaction vessel equipped with a condenser, nitrogen gas is introduced to purge three times, the temperature is raised to 150℃, and the reaction is stirred. During the reaction, by-products are continuously separated and distilled off through a distillation column. The reaction is carried out for 7 hours to obtain the nitrogen-phosphorus-terminated hydroxyl-modified polymer with Mn of 377g / mol and a functionality of 4.

[0041] The preparation steps of the isocyanate-based flame-retardant prepolymer are as follows: 82g of flame-retardant polyether polyol is added to a reaction vessel, heated to 120°C, vacuum dehydrated to a moisture content of <0.05wt.%, cooled to 70°C, 200g of toluene diisocyanate and 100g of polymethylene polyphenyl isocyanate are added, and the reaction is carried out at 70°C for 2 hours, with an NCO content of 30.39%.

[0042] The aforementioned bio-based flame-retardant polyurethane foam is composed of the following raw materials in parts by weight:

[0043] Amino acid-based modified polyether polyol: 65 parts;

[0044] Nitrogen- and phosphorus-terminated hydroxyl-modified polymers: 35 parts;

[0045] Modified isocyanate: 427 parts;

[0046] Chlorinated paraffin: 100 parts;

[0047] Expanded graphite: 50 parts;

[0048] QG-8526: 5 copies;

[0049] QG-6855: 3 copies;

[0050] Propane and butane: 40 parts;

[0051] Dimethyl ether: 50 parts;

[0052] DMDEE: 5 copies.

[0053] The above raw materials are mixed evenly at room temperature to obtain bio-based flame-retardant polyurethane foam.

[0054] Example 2

[0055] The preparation steps of the amino acid-based modified polyether polyol are as follows: 445g of alanine, 1870g of castor oil (hydroxyl value of 162mgKOH / g), and 2.03g of boron trifluoride catalyst are added to a pressure-resistant reactor. The temperature is raised to 100℃, the vacuum is evacuated to -0.09MPa, and nitrogen is purged for 2 hours to remove small molecule monomers and water. Nitrogen is then introduced, and 1750g of epichlorohydrin is added dropwise. After the addition is complete, the reaction is allowed to proceed for 2 hours. Vacuum is then applied to remove unreacted residual monomers to obtain the amino acid-based modified polyether polyol with a Mn of 550g / mol and a functionality of 2.2.

[0056] The preparation steps of the nitrogen-phosphorus-terminated hydroxyl-modified polymer are as follows: 147g of glutamic acid, 287g of tris(hydroxymethyl)phosphonium oxide and 0.347g of p-toluenesulfonic acid are added to a reaction vessel equipped with a condenser, nitrogen gas is introduced to purge three times, the temperature is raised to 170℃, and the reaction is stirred. During the reaction, by-products are continuously separated and distilled off through a distillation column. After 6 hours of reaction, the nitrogen-phosphorus-terminated hydroxyl-modified polymer with Mn of 377g / mol and functionality of 4 is obtained.

[0057] The preparation steps of the isocyanate-based flame-retardant prepolymer are as follows: 103g of flame-retardant polyether polyol is added to a reaction vessel, heated to 100°C, vacuum dehydrated to a moisture content of <0.05wt.%, cooled to 60°C, 200g of toluene diisocyanate and 100g of polymethylene polyphenyl isocyanate are added, and the reaction is carried out at 60°C for 2.5h, with an NCO content of 28.12%.

[0058] The aforementioned bio-based flame-retardant polyurethane foam is composed of the following raw materials in parts by weight:

[0059] Amino acid-based modified polyether polyol: 75 parts;

[0060] Nitrogen- and phosphorus-terminated hydroxyl-modified polymers: 25 parts;

[0061] Modified isocyanate: 440 parts;

[0062] Chlorinated paraffin: 120 parts;

[0063] Expanded graphite: 60 parts;

[0064] QG-8526: 5 copies;

[0065] QG-6855: 4 copies;

[0066] Propane and butane: 40 parts;

[0067] Dimethyl ether: 40 parts;

[0068] DMDEE: 4 copies.

[0069] The above raw materials are mixed evenly at room temperature to obtain bio-based flame-retardant polyurethane foam.

[0070] Example 3

[0071] The preparation steps of the amino acid-based modified polyether polyol are as follows: 445g of alanine, 1870g of castor oil (hydroxyl value of 162mgKOH / g), and 2.24g of boron trifluoride catalyst are added to a pressure-resistant reactor. The temperature is raised to 100℃, the vacuum is evacuated to -0.09MPa, and nitrogen is purged for 2 hours to remove small molecule monomers and water. Nitrogen is then introduced, and 2940g of epichlorohydrin is added dropwise. After the addition is complete, the reaction is carried out for 2 hours. Vacuum is then applied to remove unreacted residual monomers to obtain the amino acid-based modified polyether polyol with Mn of 700g / mol and functionality of 2.2.

[0072] The preparation steps of the nitrogen-phosphorus-terminated hydroxyl-modified polymer are as follows: 133g of aspartic acid, 287g of tris(hydroxymethyl)phosphonium oxide and 0.336g of p-toluenesulfonic acid are added to a reaction vessel equipped with a condenser, nitrogen gas is introduced to purge the mixture three times, the temperature is raised to 150℃, and the mixture is stirred to react. During the reaction, byproducts are continuously separated and distilled off through a distillation column. After reacting for 8 hours, the nitrogen-phosphorus-terminated hydroxyl-modified polymer with Mn of 391g / mol and a functionality of 4 is obtained.

[0073] The preparation steps of the isocyanate-based flame-retardant prepolymer are as follows: 64g of flame-retardant polyether polyol is added to a reaction vessel, heated to 110°C, vacuum dehydrated to a moisture content of <0.05wt.%, cooled to 80°C, 200g of toluene diisocyanate and 100g of polymethylene polyphenyl isocyanate are added, and the reaction is carried out at 80°C for 2 hours, with an NCO content of 32.59%.

[0074] The aforementioned bio-based flame-retardant polyurethane foam is composed of the following raw materials in parts by weight:

[0075] Amino acid-based modified polyether polyol: 60 parts;

[0076] Nitrogen- and phosphorus-terminated hydroxyl-modified polymers: 40 parts;

[0077] Modified isocyanate: 380 parts;

[0078] Chlorinated paraffin: 130 parts;

[0079] Expanded graphite: 40 parts;

[0080] QG-8526: 6 copies;

[0081] QG-6855: 4 copies;

[0082] Propane and butane: 40 parts;

[0083] Dimethyl ether: 60 parts;

[0084] DMDEE: 3 copies.

[0085] The above raw materials are mixed evenly at room temperature to obtain bio-based flame-retardant polyurethane foam.

[0086] Comparative Example 1

[0087] Using a number-average molecular weight of 600 g·mol -1 The composite polyether polyol replaces the amino acid-modified polyether polyol (which is prepared by catalytic polymerization of propylene oxide with propylene glycol and glycerol as initiators and a functionality of 2.2). Other raw materials and preparation methods are the same as in Example 1.

[0088] Comparative Example 2

[0089] It was prepared by polymerizing pentaerythritol polyether polyol (using pentaerythritol as a starter and catalyzing the polymerization of propylene oxide under the action of a catalyst, with a functionality of 4 and a number-average molecular weight of 377 g·mol⁻¹) -1 (The polymer containing nitrogen and phosphorus terminal hydroxyl groups is used instead of the polymer modified with nitrogen and phosphorus, and other raw materials and preparation methods are the same as in Example 1.)

[0090] Comparative Example 3

[0091] Modified isocyanate was prepared using INOVOL C206 instead of flame-retardant polyether polyol. The preparation steps were the same as those described in Example 1. Other raw materials and preparation methods were the same as in Example 1.

[0092] The performance of the polyurethane foams prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the test methods are as follows:

[0093] The cumulative biodegradation percentage was tested in accordance with GB / T 19276.1, and the limiting oxygen index was tested in accordance with GB / T2406.1-2008.

[0094] The test results are shown in Table 1.

[0095] Table 1 Performance test results of Examples 1-3 and Comparative Examples 1-3

[0096]

[0097] As can be seen from the data in Table 1, introducing bio-based raw materials such as castor oil and amino acids into the foaming adhesive system can significantly improve the biodegradability of the material; flame retardant elements such as nitrogen, phosphorus, and chlorine work synergistically to achieve the intrinsic flame retardant properties of the material, thereby enhancing the flame retardant effect.

Claims

1. A bio-based flame-retardant polyurethane foam adhesive, characterized by, It consists of the following parts by weight of raw materials: Amino acid-based modified polyether polyol: 60-75 parts; Nitrogen- and phosphorus-terminated hydroxyl-modified polymers: 25-40 parts; Modified isocyanate: 380~440 parts; Chlorinated paraffin: 100-130 parts; Filler: 40-60 parts; Silicone oil: 8-10 parts; Propellant: 80-100 parts; Catalyst: 3-5 parts; The amino acid-based modified polyether polyol is obtained by polymerizing epichlorohydrin under the action of a catalyst with alanine and castor oil as starting agents; the number average molecular weight is 550-700 g·mol -1 , and the functionality is 2.2; The preparation steps of the nitrogen-phosphorus-terminated hydroxyl-modified polymer are as follows: dicarboxylic acid, trimethylolphosphine oxide, and p-toluenesulfonic acid are added to a reaction vessel equipped with a condenser, nitrogen is introduced to purge the mixture three times, the temperature is raised to 150-170°C, and the mixture is stirred to react. During the reaction, by-products are continuously separated and distilled off through a distillation column, and the reaction is carried out for 6-8 hours. The molar ratio of dicarboxylic acid to trimethylolphosphine oxide is 1:2.

05. The amount of p-toluenesulfonic acid catalyst used is 500-800 ppm of the total amount of dicarboxylic acid and trimethylolphosphine oxide. The modified isocyanate is prepared by adding flame-retardant polyether polyol to a reaction vessel, heating to 100-120°C, vacuum dehydrating to a moisture content of <0.05wt.%, cooling to 60-80°C, adding isocyanate, and reacting until the -NCO content is 27-33wt.%, wherein the mass ratio of isocyanate to flame-retardant polyether is 100:(32-41). The flame-retardant polyether polyol is obtained by polymerizing propylene oxide with dibromoneopentyl glycol and INOVOL C204 as initiators and a catalyst; the number average molecular weight is 600 g·mol⁻¹. -1 Its functionality is 2.

2. The bio-based flame-retardant polyurethane foam glue according to claim 1, characterized in that, The dicarboxylic acid is either aspartic acid or glutamic acid.

3. The bio-based flame-retardant polyurethane foam glue according to claim 1, characterized in that, The isocyanate is toluene diisocyanate and polymethylene polyphenyl isocyanate.

4. The bio-based flame-retardant polyurethane foam glue according to claim 1, characterized in that, The filler is expanded graphite. By introducing nano flame-retardant fillers, an organic-inorganic composite flame-retardant system is constructed to reduce the smoke toxicity of the foam.

5. The bio-based flame-retardant polyurethane foam glue according to claim 1, characterized in that, The catalyst is DMDEE.

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