Process for the preparation of high strength flame retardant wood-like foams

Abstract

The present application relates to polyurethane preparation technical field, specifically for the preparation method of high-strength flame-retardant wood-like foam, the preparation method comprises the following steps: (1) in 30-35 DEG C condition, in 120 weight parts of polyether, 0.8-1.5 weight parts of water, 2.5-4 weight parts of catalyst, 3.5-5 weight parts of foam stabilizer are added, and the combined material is obtained;(2) in 30-35 DEG C condition, 130-140 weight parts of polyisocyanate are added to the combined material obtained in step (1), and after stirring, foaming, curing, polyurethane foam is obtained;Wherein the polyether is prepared by reacting propylene oxide with modified melem, sucrose and glycerol as starter, and the mass fraction of propylene oxide in polyether is 60-70%. The foam prepared by the method has high strength and good flame retardant performance.

Description

Technical Field

[0001] This invention relates to the field of polyurethane preparation technology, specifically a method for preparing high-strength flame-retardant wood-like foam. Background Technology

[0002] In fields such as architectural decoration, rail transit, shipbuilding, and public facilities, handrails, as important functional and decorative components, always face the triple demands of "practicality, safety, and aesthetics" in their material selection. Traditional wooden handrails, with their natural texture and warm feel, have long dominated the market. However, natural wood has inherent drawbacks: on the one hand, wood is flammable and produces toxic fumes when burning, posing a significant fire hazard in densely populated areas (such as shopping malls, subways, and hospitals) or scenarios with stringent fire protection requirements (such as high-rise buildings and ships); on the other hand, the mechanical properties of natural wood are greatly affected by tree species and moisture content, making it prone to cracking, deformation, and decay, resulting in a short service life. Furthermore, its reliance on forest resources does not align with the trend of environmentally friendly and sustainable development.

[0003] With increasingly stringent fire safety regulations and rising consumer demands for product quality and durability, the market urgently needs new handrail materials that combine high strength, high flame retardancy, wood-like appearance, and environmental friendliness. Against this backdrop, the development of high-strength, flame-retardant, wood-like handrails has become a focus of the industry. The core requirement is to overcome the technical bottleneck of traditional wood-like materials, which struggle to balance flame retardancy and mechanical properties, through optimized material formulations and innovative processes, while simultaneously replicating the texture and feel of natural wood to meet the installation and usage requirements of various scenarios.

[0004] In the existing technology, wood-imitation polyurethane (PU wood-imitation) is a medium-to-high density structural rigid polyurethane foam material. Its own characteristics are naturally adapted to the core needs of high-strength flame-retardant wood-imitation handrails. Compared with traditional alternative materials, it shows multiple irreplaceable advantages. The polyurethane molecular structure itself has a certain flame-retardant basis. By adding phosphorus and nitrogen-based intumescent flame retardants, magnesium hydroxide and other environmentally friendly flame-retardant additives to the combined polyether components, the flame retardant level can reach B1 level and above, and the smoke density and toxic gas release during combustion are low.

[0005] However, existing technologies still have drawbacks: some high flame-retardant wood-like materials suffer from excessive flame retardant addition, leading to a significant decrease in the mechanical properties of the substrate and failing to meet the load-bearing and impact resistance requirements of handrails; some high-strength wood-like composite materials have poor flame-retardant properties and are difficult to pass stringent fire resistance tests. Therefore, developing a high-strength flame-retardant wood-like handrail represents a new market demand. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing high-strength flame-retardant wood-like foam, which produces foam with high strength and high flame-retardant properties.

[0007] This invention is achieved using the following technical solution:

[0008] The preparation method of the high-strength flame-retardant wood-like foam includes the following steps:

[0009] Component A and component B are mixed, foamed, and cured to obtain the polyurethane wood-like foam;

[0010] in,

[0011] Component A is made from the following raw materials in parts by weight:

[0012] Polyether polyol: 120 parts;

[0013] Water: 0.8-1.5 parts;

[0014] Catalyst: 2.5-4 parts;

[0015] Foam stabilizer: 3.5-5 parts;

[0016] Component B is a polyisocyanate, and its dosage is 130-140 parts by weight;

[0017] Furthermore, the polyether polyol is polymerized from modified melamine, sucrose, and glycerol as initiators, and propylene oxide as a monomer; based on the total mass of the polyether polyol being 100%:

[0018] The mass fraction of the melamine is 7.4-12%;

[0019] The mass fraction of sucrose is 19-25%;

[0020] The glycerol has a mass fraction of 4.0-6.7%;

[0021] The mass fraction of propylene oxide is the balance.

[0022] The mixing and foaming process is carried out at a temperature of 25-35℃.

[0023] The modified melleramine is prepared by reacting melleramine with formaldehyde under alkaline conditions, followed by dehydration and drying.

[0024] The preparation method of the polyether polyol includes: adding modified melamine, sucrose and glycerol into a reaction vessel, adding a catalyst, introducing a portion of propylene oxide to initiate the reaction, then heating to dehydrate, and then introducing the remaining propylene oxide for polymerization and aging, finally obtaining the polyether polyol.

[0025] The temperature for heating and dehydration is 110-120℃, and the time is 3-4 hours; the temperature for polymerization and ripening is 95-120℃, and the time is 2-5 hours.

[0026] The catalyst in component A is one or a mixture of two of triethylenediamine and N,N-dimethylcyclohexylamine.

[0027] The foam stabilizer in component A is either L580 or L590.

[0028] The polyisocyanate in component B is PM200.

[0029] Specifically, the preparation method of high-strength flame-retardant wood-like foam includes the following steps:

[0030] (1) At 30-35℃, 0.8-1.5 parts by weight of water, 2.5-4 parts by weight of catalyst, and 3.5-5 parts by weight of foam stabilizer are added to 120 parts by weight of polyether to obtain the composite material;

[0031] (2) Add 130-140 parts by weight of polyisocyanate to the obtained composite material, stir and foam, and cure to obtain high-strength flame-retardant wood-like foam.

[0032] The preparation method of the polyether is as follows: Modified melamine, sucrose, glycerol, and water (used only as solvent and not participating in the reaction) are added to the reaction vessel. After displacement and vacuuming, the catalyst is introduced, the temperature is raised to 80°C, and some propylene oxide is introduced to initiate the reaction. The temperature is then raised to 110°C and bubbled to dehydrate for 3-4 hours. The remaining propylene oxide is then introduced for polymerization and ripening. After degassing, polyether polyol is obtained.

[0033] in:

[0034] The modified melamine accounts for 7.4-9.3% of the mass of the polyether.

[0035] The sucrose accounts for 19.6-21.2% of the polyether by mass, and the glycerol accounts for 5.4-5.8% of the polyether by mass.

[0036] The catalyst mentioned is trimethylamine.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] (1) In the raw material system of polyether of the present invention, the high-functionality raw material sucrose can play a key role in supporting high strength, while the polyether modified by melamine can give the material excellent flame retardant properties. The two work together to support the high strength characteristics of polyether polyol.

[0039] (2) The flame-retardant material modified melamine used does not contain halogens, and the product prepared is an environmentally friendly polyurethane.

[0040] (3) The preparation process of the present invention is simple and easy to implement, and the operation process is concise, which lays the foundation for its promotion and application in many fields and has broad market prospects and practical value. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0042] This invention provides a method for preparing high-strength flame-retardant wood-like foam, which is obtained by mixing and reacting component A and component B.

[0043] In a preferred embodiment of the present invention, component A is made from the following raw materials in parts by weight: 120 parts of polyether polyol, 0.8-1.5 parts of water as a blowing agent, 2.5-4 parts of catalyst, and 3.5-5 parts of foam stabilizer. Component B is a polyisocyanate, and its dosage is 130-140 parts by weight.

[0044] The modified melleramine of this invention is prepared as follows: Take a certain amount of formaldehyde, adjust the pH of the reaction system to 8-9 with triethanolamine, then add a certain amount of melleramine, slowly heat until the melleramine is completely dissolved, the reaction temperature is 85℃, and the reaction is carried out for 1 hour. During this period, the alkaline catalyst triethanolamine needs to be added to maintain the pH between 8-9 (meleramine (mol): formaldehyde (mol) = 1:3). Finally, dehydration and drying can obtain hydroxymethylated modified melleramine.

[0045] The key technology in this invention lies in the selection and preparation of the polyether polyol. This polyether polyol is prepared by polymerization of modified melamine, sucrose, and glycerol with propylene oxide, using these as composite initiators. The introduction of modified melamine, utilizing its nitrogen-rich, stable triazine ring structure, endows the polymer segments with excellent intrinsic flame retardancy, forming a so-called "reactive flame retardant," and resulting in low smoke production and no halogen release during combustion, making it environmentally friendly. High-functionality sucrose, as an initiator, can form a highly cross-linked network structure in the subsequent polyurethane reaction, which is the structural basis for the high mechanical strength of the final wood-like foam material. Glycerol, as a low-molecular-weight polyol, is used to adjust the overall functionality and reactivity of the system. In this invention, the mass fraction of propylene oxide in the polyether polyol is preferably 60-70%. This invention does not have special restrictions on the sources of the melamine, sucrose, glycerol, and propylene oxide; commercially available industrial products well known to those skilled in the art can be used.

[0046] In this invention, the polyether polyol is preferably a polyether, which gives the final product additional hygienic properties and broadens its application in public facilities, medical environments and other scenarios.

[0047] In this invention, the catalyst in component A is preferably a tertiary amine catalyst, such as one or a mixture of two of triethylenediamine and N,N-dimethylcyclohexylamine. These catalysts can effectively catalyze the reaction of isocyanate with compounds containing active hydrogen (such as water or polyether polyols), balancing the foaming and gelation rates. This invention does not impose any particular restrictions on the source of the catalyst and commercially available products can be used.

[0048] In this invention, the foam stabilizer in component A is preferably a polysiloxane-polyether copolymer, such as one of the brands L580 and L590. This type of stabilizer effectively reduces the surface tension of the system, stabilizes the cell structure during foam growth, prevents foam collapse, and ensures uniform and fine foam. This invention does not impose any special restrictions on the source of the foam stabilizer; commercially available products from companies such as Momentive, Inc., can be used.

[0049] In this invention, the polyisocyanate in component B is preferably polymeric MDI, such as PM200. Polymeric MDI has a low vapor pressure and suitable reactivity, and is a commonly used raw material for preparing rigid polyurethane foam. This invention does not impose any special restrictions on the source of the polyisocyanate; commercially available products, such as those from Wanhua Chemical Group Co., Ltd., can be used.

[0050] The preparation method provided by this invention involves mixing component A, which contains a special polyether polyol, and component B at a preferred temperature of 25-35°C. Through synergistic effects, the polyurethane wood-like foam prepared not only has a texture comparable to wood, but also possesses high strength and excellent flame retardant properties, successfully solving the technical problem of traditional wood-like materials where mechanical properties and flame retardancy are difficult to balance.

[0051] This invention also provides a preferred preparation method for the above-mentioned polyether polyol, comprising: adding modified melamine, sucrose, and glycerol to a reaction vessel; in the presence of a catalyst (preferably trimethylamine); first introducing a portion of propylene oxide to initiate the reaction; then heating and dehydrating (preferably at 110-120°C for 3-4 hours) to remove water introduced from the initiator and reaction byproduct water; then introducing the remaining propylene oxide; and polymerizing and maturing at a suitable temperature (preferably 95-120°C) and time (preferably 2-5 hours); finally, degassing to obtain the finished product. This preparation process is stable and reliable, and easy to industrialize.

[0052] To further illustrate the present invention, the following embodiments provide a detailed description. Unless otherwise specified, all raw materials used in the following embodiments of the present invention are commercially available products.

[0053] Example 1

[0054] Preparation of high-strength flame-retardant polyether:

[0055] 130g of modified mellamide, 369g of sucrose and 101g of glycerol were added to the reactor. After pressure testing for 20 minutes, nitrogen was replaced three times and the pressure was evacuated to -0.99MPa. 100g of pure water and 5g of trimethylamine catalyst were added. After heating to 80℃, 410g of propylene oxide was pre-dropped to initiate polymerization. After 1 hour of curing, the temperature was raised to 110℃ and bubbled for 3 hours to dehydrate. 513g of propylene oxide was added and the mixture was kept warm for 2 hours to cure. After degassing, polyether polyol was obtained.

[0056] High-strength flame-retardant wood-like foam material was prepared using the following method:

[0057] (1) At 25°C, 0.8 parts by weight of water, 2.5 parts by weight of triethylenediamine catalyst, and 3.5 parts by weight of foam stabilizer L580 were added to 120 parts by weight of polyether and mixed thoroughly to obtain the composite material.

[0058] (2) At 25°C, 130 parts by weight of PM200 were added to the composite material obtained in step (1), stirred and foamed, and cured at 25°C for 24 hours to obtain polyurethane foam.

[0059] Example 2

[0060] Preparation of high-strength flame-retardant polyether:

[0061] 150g of modified mellamide, 365g of sucrose and 101g of glycerol were added to the reactor. After pressure testing for 20 minutes, nitrogen was replaced three times. The pressure was then reduced to -0.99MPa, and 100g of pure water and 5g of trimethylamine catalyst were added. After heating to 80℃, 417g of propylene oxide was pre-dropped to initiate polymerization. After 1 hour of curing, the temperature was raised to 110℃, and the mixture was bubbled and dehydrated for 4 hours. Then, 622g of propylene oxide was added, and the mixture was kept at this temperature for 3 hours. After degassing, polyether polyol was obtained.

[0062] High-strength flame-retardant wood-like foam material was prepared using the following method:

[0063] (1) At 30°C, 1 part by weight of water, 3 parts by weight of catalyst N,N-dimethylcyclohexylamine, and 4 parts by weight of foam stabilizer L590 were added to 120 parts by weight of polyether and mixed thoroughly to obtain the composite material.

[0064] (2) At 30°C, 140 parts by weight of PM200 were added to the composite material obtained in step (1), stirred and foamed, and cured at 25°C for 24 hours to obtain polyurethane foam.

[0065] Example 3

[0066] Preparation of high-strength flame-retardant polyether:

[0067] 200g of modified melamine, 350g of sucrose and 100g of glycerol were added to the reactor. After pressure testing for 20 minutes, nitrogen was replaced three times. The reactor was then evacuated to -0.99MPa. 100g of pure water and 5g of trimethylamine catalyst were added. After heating to 80℃, 417g of propylene oxide was pre-dropped to initiate polymerization. After 1 hour of curing, the temperature was raised to 120℃, 658g of propylene oxide was added, and the reactor was kept at this temperature for 5 hours. After degassing, polyether polyol was obtained.

[0068] High-strength flame-retardant wood-like foam material was prepared using the following method:

[0069] (1) At 35°C, 1.5 parts by weight of water, 4 parts by weight of triethylenediamine catalyst, and 5 parts by weight of foam stabilizer L580 are added to 120 parts by weight of polyether and mixed thoroughly to obtain the composite material.

[0070] (2) At 35°C, 140 parts by weight of PM200 were added to the composite material obtained in step (1), stirred and foamed, and cured at 25°C for 24 hours to obtain polyurethane foam.

[0071] Comparative Example 1

[0072] Preparation of polyethers:

[0073] While ensuring that the functionality, hydroxyl value and viscosity of the polyether are consistent with those in the examples, 405g of sucrose and 100g of glycerol were added to the reactor. After pressure testing for 20 minutes, nitrogen was replaced three times. The reactor was then evacuated to -0.99MPa, and 100g of pure water and 5g of trimethylamine catalyst were introduced. After heating to 80°C, 372g of propylene oxide was pre-dropped to initiate polymerization. After the addition was completed and the reactor was matured for 1 hour, the temperature was raised to 110°C, 551g of propylene oxide was added, and the reactor was kept at this temperature for 3 hours. After degassing, polyether polyol was obtained.

[0074] High-strength flame-retardant wood-like foam material was prepared using the following method:

[0075] (1) At 25°C, 0.8 parts by weight of water, 2.5 parts by weight of triethylenediamine catalyst, and 3.5 parts by weight of foam stabilizer L580 were added to 120 parts by weight of polyether and mixed thoroughly to obtain the composite material.

[0076] (2) At 25°C, 130 parts by weight of PM200 were added to the combined material obtained in step (1), and foamed after stirring.

[0077] Comparative Example 2

[0078] Preparation of polyethers:

[0079] While ensuring that the functionality, hydroxyl value and viscosity of the polyether are consistent with those in the examples, 240g of modified melleramine, 305g of sucrose and 91g of glycerol were added to the reactor. After pressure testing for 20 minutes, nitrogen was replaced three times. The reactor was then evacuated to -0.99MPa, and 100g of pure water and 5g of trimethylamine catalyst were introduced. After heating to 80°C, 426g of propylene oxide was pre-dropped to initiate polymerization. After 1 hour of curing, the temperature was raised to 110°C, 598g of propylene oxide was added, and the reactor was kept at this temperature for 3 hours. After degassing, polyether polyol was obtained.

[0080] High-strength flame-retardant wood-like foam material was prepared using the following method:

[0081] (1) At 25°C, 1 part by weight of water, 3 parts by weight of the catalyst triethylenediamine, and 4 parts by weight of the foam stabilizer L580 were added to 120 parts by weight of polyether and mixed thoroughly to obtain the composite material.

[0082] (2) At 25°C, 130 parts by weight of PM200 were added to the composite material obtained in step (1), stirred and foamed, and cured at 25°C for 24 hours to obtain polyurethane foam.

[0083] Comparative Example 3

[0084] The polyether prepared in Example 1 was used.

[0085] High-strength flame-retardant wood-like foam material was prepared using the following method:

[0086] (1) At 25°C, 1 part by weight of water, 3 parts by weight of the catalyst triethylenediamine, and 4 parts by weight of the foam stabilizer L580 were added to 100 parts by weight of polyether and mixed thoroughly to obtain the composite material.

[0087] (2) At 25°C, 100 parts by weight of PM200 were added to the composite material obtained in step (1), stirred and foamed, and cured at 25°C for 24 hours to obtain polyurethane foam.

[0088] The performance indicators and raw material contents of the polyether products prepared in the examples and comparative examples are shown in Table 1.

[0089] The performance indicators and dosages of the polyurethane foam products prepared in the examples and comparative examples are shown in Table 2.

[0090] Table 1. Performance indicators and raw material content of the polyether products prepared in the examples and comparative examples.

[0091]

[0092] Table 2. Performance indicators and dosage of polyurethane foam products prepared in the examples and comparative examples.

[0093]

[0094] As can be seen from Table 1, the viscosity of polyether with different contents obtained after the formulation design is 23000±1000mPa·s, and the hydroxyl value is 500±2mgKOH / g.

[0095] As shown in Table 2, the three examples demonstrate that the wood-like polyether composite prepared from the modified melamine, sucrose, and glycerol exhibits high foam hardness. A comparison between Comparative Example 1 and Example 1 shows that using only sucrose and glycerol as initiators results in foam with almost no flame retardancy. Examples 1 and Comparative Example 2 show that reducing the sucrose content significantly reduces the foam's strength and hardness. A comparison between Example 1 and Comparative Example 3 shows that the polyether composite formulation also affects the foam's performance.

[0096] The high-strength flame-retardant wood-like foam prepared by this invention has excellent foam strength and hardness, as well as excellent flame-retardant properties.

Claims

1. A method for preparing high-strength flame-retardant wood-like foam, characterized in that, Includes the following steps: Component A and component B are mixed, foamed, and cured to obtain polyurethane wood-like foam. in, Component A is made from the following raw materials in parts by weight: Polyether polyol: 120 parts; Water: 0.8-1.5 parts; Catalyst I: 2.5-4 parts; Foam stabilizer: 3.5-5 parts; Component B is a polyisocyanate, and its dosage is 130-140 parts by weight; Furthermore, the polyether polyol is polymerized from modified melamine, sucrose, and glycerol as initiators, and propylene oxide as a monomer; based on the total mass of the polyether polyol being 100%: The modified melleramine has a mass fraction of 7.4-12%; The mass fraction of the sucrose is 19-25%; The glycerol has a mass fraction of 4.0-6.7%; The mass fraction of propylene oxide is the balance. The preparation method of the polyether polyol includes: adding modified melamine, sucrose and glycerol into a reaction vessel, adding catalyst II, introducing a portion of propylene oxide to initiate the reaction, then heating to dehydrate, and then introducing the remaining propylene oxide for polymerization and aging, finally obtaining the polyether polyol; The modified melamine is prepared as follows: Take a certain amount of formaldehyde, adjust the pH of the reaction system to 8-9 with triethanolamine, then add a certain amount of melamine, slowly heat until the melamine is completely dissolved, the reaction temperature is 85℃, and the reaction is timed for 1 hour. During this period, the alkaline catalyst triethanolamine needs to be added to maintain the pH between 8 and 9. Finally, dehydrate and dry to obtain hydroxymethylated modified melamine; the molar ratio of melamine to formaldehyde is 1:

3.

2. The method for preparing high-strength flame-retardant wood-like foam according to claim 1, characterized in that, The mixing and foaming process is carried out at a temperature of 25-35℃.

3. The method for preparing high-strength flame-retardant wood-like foam according to claim 1, characterized in that, The temperature for heating and dehydration is 110-120℃, and the time is 3-4 hours; the temperature for polymerization and ripening is 95-120℃, and the time is 2-5 hours.

4. The method for preparing high-strength flame-retardant wood-like foam according to claim 1, characterized in that, The catalyst I in component A is one or a mixture of two of triethylenediamine and N,N-dimethylcyclohexylamine.

5. The method for preparing high-strength flame-retardant wood-like foam according to claim 1, characterized in that, The foam stabilizer in component A is either L580 or L590.

6. The method for preparing high-strength flame-retardant wood-like foam according to claim 1, characterized in that, The polyisocyanate in component B is PM200.

Images