High-functionality melamine rigid foam polyol and its preparation method and application

Abstract

The invention relates to a high-functionality melamine rigid foam polyol and a preparation method and application thereof, and mainly solves the problems of complicated steps, harsh conditions and high energy consumption in the production method of polyhydroxy structure amino resin in the prior art. The invention provides a high-functionality melamine rigid foam polyol, and the preparation method comprises the following steps: (1) adding hexamethoxymethyl melamine, polyol and diol into a reaction kettle in a molar ratio of 1:1-6:1-6; (2) heating to 80-129 DEG C under stirring, and adjusting the pH to 2-6; (3) reacting material II at normal pressure, at a temperature of 80-129 DEG C, and for 3-8 hours; (4) adjusting the pH to 7-9; (5) performing reduced pressure distillation, at a temperature of 80-129 DEG C, and a pressure of -0.08-0.10MPa; and (6) monitoring the moisture content until the moisture mass percentage is less than or equal to 0.5%, thereby obtaining a high-functionality melamine rigid foam polyol and a technical solution for the application thereof, which better solves the problem and can be used in industrial applications of polyurethane foam.

Description

Technical Field

[0001] The invention relates to the field of melamine rigid foam polyols, and in particular to a high-functionality melamine rigid foam polyol and a preparation method and application thereof. Background Art

[0002] Polyurethane (PU) is the abbreviation of polyurethane, which is formed by the addition polymerization of polyisocyanate and polyhydroxy polymer. It is a polymer compound containing many repeated carbamate segments (-NHCOO-) on the polymer main chain. In recent years, polyurethane has developed rapidly in my country, thanks to the excellent properties of polyurethane materials, such as wear resistance, high mechanical strength, high elasticity, aging resistance, corrosion resistance, etc.

[0003] With the development of the industry, the requirements for polyurethane products are getting higher and higher, such as flame retardancy, low thermal conductivity, low formaldehyde, high strength, good dimensional stability, etc. of polyurethane foam. Considering that melamine has a triazine ring structure, the introduction of melamine structure into the polyurethane microstructure can theoretically improve the compressive strength of polyurethane foam and obtain better dimensional stability. However, melamine is a solid powder and is difficult to use in the application and molding process of polyurethane products.

[0004] Chinese patent CN 102295616B discloses an amino resin with a polyhydroxy structure and a preparation method thereof. The preparation method comprises: (1) melamine methylolation reaction; (2) methyl etherification reaction; (3) alkali neutralization; (4) distillation to dehydrate methanol and formaldehyde; (5) cooling and filtration; (6) ether exchange reaction; (7) distillation dealcoholization, cooling and filtration to obtain the finished product. The preparation method has many steps, and the reaction conditions are relatively harsh and the energy consumption is high. The polyurethane foam plastic prepared by using the amino resin with a polyhydroxy structure is very brittle, has poor bonding performance and high cost, which limits its application and is not suitable for large-scale industrial production.

[0005] Therefore, the present invention uses hexamethoxymethyl melamine (HMMM) as a raw material to conduct experiments, aiming to provide a melamine rigid foam polyol that replaces melamine as the main microstructure for the polyurethane industry, and use it in polyurethane foam. Summary of the invention

[0006] One of the technical problems to be solved by the present invention is that the production method of polyhydroxy structure amino resin in the prior art has complicated steps, harsh conditions and high energy consumption. A high-functionality melamine rigid foam polyol is provided, which has the advantages of simple preparation steps, mild conditions and low energy consumption.

[0007] The second technical problem to be solved by the present invention is to provide a preparation method corresponding to the first technical problem to be solved.

[0008] The third technical problem to be solved by the present invention is to provide an application corresponding to solving one of the technical problems.

[0009] In order to solve one of the above technical problems, the technical solution adopted by the present invention is as follows: a high-functionality melamine rigid foam polyol, whose molecular structure is as follows:

[0010]

[0011] Wherein, R is selected from one of R1 and R2, R1 is selected from one of —CH2CH(CH3)OH, —CH2CH(OH)CH2OH or —CH(CH3)CH2OCH2CH(CH3)OH, and R2 is selected from one of —CH2CH2OCH2CH(CH3)OH or —CH(CH3)CH2OCH2CH2OCH2CH(CH3)OH.

[0012] In order to solve the second technical problem mentioned above, the technical solution adopted by the present invention is: a method for preparing a high-functionality melamine rigid foam polyol, comprising the following steps:

[0013] (1) adding hexamethoxymethylmelamine, polyol and diol into a reaction kettle at a molar ratio of 1:1-6:1-6 to form material I, wherein the diol is obtained by reacting ethylene glycol with propylene oxide;

[0014] (2) Under stirring conditions, the material is heated using a heating medium. When the temperature of the material in the reactor reaches 80 to 129° C., an acidic regulator is added to the material I to adjust the pH value of the system to 2 to 6, thereby obtaining a material II;

[0015] (3) Material II is reacted under normal pressure, the reaction temperature is 80-129° C., and the reaction time is 3-8 h to obtain material III;

[0016] (4) adding an alkaline regulator to material III to adjust the pH value of the system to 7-9 to obtain material IV;

[0017] (5) subjecting material IV to vacuum distillation to separate small molecules in the system, wherein the vacuum distillation temperature is 80 to 129° C. and the pressure is -0.08 to -0.10 MPa, as measured by gauge pressure, to obtain material V;

[0018] (6) Monitoring the moisture content of material V until the moisture content by mass is ≤0.5%, thereby obtaining a high-functionality melamine rigid foam polyol.

[0019] In the above technical solution, preferably, the polyol in step (1) is selected from at least one of propylene glycol, dipropylene glycol or glycerol.

[0020] In the above technical solution, preferably, the diol in step (1) is obtained by reacting ethylene glycol and propylene oxide in a molar ratio of 1:1 or 1:2.

[0021] In the above technical solution, preferably, the functionality of the diol is 2, and the hydroxyl value is 550-950 mgKOH / g.

[0022] In the above technical solution, preferably, the acidic regulator in step (2) is selected from at least one of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, p-toluenesulfonic acid, formic acid or oxalic acid.

[0023] In the above technical solution, preferably, the alkaline regulator in step (4) is selected from at least one of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution or an alkaline organic amine.

[0024] In the above technical solution, preferably, the small molecule substance in step (5) is a mixture of free formaldehyde, water, methanol and diols.

[0025] In order to solve the third technical problem mentioned above, the technical solution adopted by the present invention is: adding the prepared high-functionality melamine rigid foam polyol to the formula of polyurethane foam for foaming to prepare a polyurethane foam product.

[0026] The invention provides a high-functionality melamine rigid foam polyol, and the preparation method thereof involves only one chemical reaction, namely, a reaction in which hexamethoxymethyl melamine and a multi-component alcohol mixture are subjected to an ether exchange reaction under acidic conditions to obtain the high-functionality melamine rigid foam polyol; at the beginning of the preparation, all the main raw materials are added to a reactor at one time, and the reaction is subsequently controlled by controlling the temperature and pH of the reaction system; the entire preparation process is simple in steps, the reaction is carried out under normal pressure, the temperature is low, the conditions are mild, and the energy consumption is low; the obtained high-functionality melamine rigid foam polyol is a series of medium molecular weight compounds with multiple hydroxyl groups and a certain degree of crosslinking, the appearance is a light yellow viscous liquid, and it has good compatibility with other raw materials for polyurethane foaming, storage Stable; the performance test results of high-functionality melamine rigid foam polyol show that its viscosity can be as low as 4450mPa·s / 25℃, which is convenient for later operation, and the hydroxyl value can be as high as 572.30mgKOH / g, which is beneficial to improve the mechanical properties of the later foamed foam; the performance test of the polyurethane rigid foam product obtained by foaming shows that the dimensional change rate in the three directions of length, width and height can be less than 0.1%, the dimensional stability is good, the compression strength can be as high as 194.20kPa, and the mechanical properties are good; the present invention has the advantages of simple preparation steps, mild conditions, low energy consumption, low viscosity and high-functionality melamine rigid foam polyol, high hydroxyl value, dimensional stability and good mechanical properties of polyurethane rigid foam, and has achieved good technical effects. DETAILED DESCRIPTION

[0027] The following are only preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All technical solutions that fall within the scope of protection of the present invention should fall within the scope of protection of the present invention. For professionals in this technical field, minor improvements and modifications to the present invention without departing from the principles of the present invention should also fall within the scope of protection of the present invention. The preparation method of the diol used in Examples 1 to 6 is as follows:

[0028] (1) EG-120: functionality is 2, hydroxyl value is 920 mgKOH / g, obtained by reacting ethylene glycol and propylene oxide in a molar ratio of 1:1;

[0029] (2) EG-178: functionality is 2, hydroxyl value is 600 mgKOH / g, obtained by reacting ethylene glycol and propylene oxide in a molar ratio of 1:2.

[0030] [Example 1]

[0031] A high-functionality melamine rigid foam polyol, the preparation method of which comprises the following steps:

[0032] (1) adding 1 mol of hexamethoxymethyl melamine, 3 mol of propylene glycol and 3 mol of EG-178 into a reaction kettle and stirring them uniformly to form material I;

[0033] (2) When the temperature in the autoclave reaches 95° C., add 20% by weight hydrochloric acid aqueous solution to material I to adjust the pH to 2.5 to obtain material II;

[0034] (3) Material II was reacted under normal pressure, at a reaction temperature of 95°C, for a reaction time of 3 h to obtain material III;

[0035] (4) adding a 30% by weight NaOH aqueous solution to material III and adjusting the pH to 7 to obtain material IV;

[0036] (5) subjecting material IV to vacuum distillation to separate small molecules in the system, wherein the vacuum distillation temperature is 95° C. and the pressure is −0.095 MPa, as measured by gauge pressure, to obtain material V;

[0037] (6) The moisture content of material V is monitored until the moisture content by mass is ≤0.5%, thereby obtaining high-functionality melamine rigid foam polyol S1. The performance data of S1 are shown in Table 3.

[0038] The prepared high-functionality melamine rigid foam polyol S1 was added to the polyurethane foaming formula according to the mass fraction in Table 1, and the performance index data of the prepared polyurethane rigid foam are shown in Table 4.

[0039] The raw materials used in Table 1 are as follows:

[0040] 1) AK-8805: silicone oil, manufactured by Meside;

[0041] 2) PC8: N,N-dimethylcyclohexylamine, amine catalyst, manufactured by Evonik;

[0042] 3) HCFC-141b: dichloromonofluoroethane, blowing agent, produced by Zhejiang Sanmei;

[0043] 4) M20S: A mixture of 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate, manufactured by Wanhua Chemical.

[0044] Table 1 Mass fractions of polyurethane foaming formula in Examples 1 to 6 and Comparative Example 1

[0045]

[0046] [Examples 2 to 6]

[0047] Examples 2 to 6 are carried out according to the steps in Example 1, except that the reaction raw materials, raw material ratio, reaction time, reaction temperature, acidic regulator, alkaline regulator, and adjusted pH value are different, as shown in Table 2; the prepared high-functionality melamine rigid foam polyol is added to the foaming formula of the polyurethane foam according to the mass fraction in Table 1 for foaming, and the performance index data of the prepared polyurethane rigid foam are shown in Table 4.

[0048] Table 2 Raw material mole number and reaction conditions in the preparation of high-functionality melamine rigid foam polyols in Examples 1 to 6

[0049]

[0050] [Comparative Example 1]

[0051] Referring to the scheme in Example 1 of patent CN 102295616B, the polyhydroxy structure amino resin is synthesized in the following steps:

[0052] (1) Hydroxylation reaction

[0053] 30.45 mol of water, 8 mol of paraformaldehyde and 1 mol of melamine are put into a reaction bottle, 6.5 mol of methanol is added, the pH value is adjusted to 8.5 with a 30% by mass sodium hydroxide aqueous solution, steam heated to 65° C., stirring speed is 85 rpm, and the reaction is kept warm; after the liquid in the kettle becomes clear, the hydroxymethylated melamine is completely precipitated, the reaction is completed, and the precipitated hydroxymethylated melamine is a white solid.

[0054] (2) Methylation reaction

[0055] The temperature was lowered to 48° C., 13.5 mol of methanol was added, and the pH value was adjusted to 3.5 with a 65% by mass aqueous nitric acid solution. The reaction was carried out for 1.5 hours until all the materials were dissolved and the methyl etherification was completed.

[0056] (3) Alkali neutralization

[0057] After the methyl etherification is completed, the pH value is adjusted to 7.5 with a 30% by mass sodium hydroxide aqueous solution under stirring at a speed of 60 rpm; the temperature is kept below 40° C. during the neutralization process.

[0058] (4) Distillation to remove methanol, water and formaldehyde

[0059] Vacuum degree: -0.095MPa, temperature: 110℃, methanol, water and formaldehyde are evaporated; the water content is qualified when it reaches less than 0.1% by mass.

[0060] (5) Cooling filtration

[0061] The mixture was cooled to 60°C, 2% by weight of diatomaceous earth filter aid was added, and the salt was filtered out with a plate filter to obtain a colorless and transparent finished product, namely, methyl etherified amino resin.

[0062] (6) Ether exchange reaction

[0063] 18 mol of ethylene glycol was added to the methyl etherified amino resin, and an ether exchange reaction was carried out at 150°C. The generated methanol was continuously evaporated under normal pressure. When the mass of the evaporated methanol reached the theoretical amount, the ether exchange was completed.

[0064] (7) Distillation and dealcoholization

[0065] At a pressure of -0.095 MPa and a temperature of 180°C, the excess ethylene glycol is evaporated and recycled; after cooling, a polyhydroxy structure amino resin S is obtained. The performance data of S are shown in Table 3.

[0066] The prepared polyhydroxy structure amino resin S was added to the foaming formula of the polyurethane foam according to the mass fraction in Table 1 for foaming. The performance index data of the prepared polyurethane rigid foam are shown in Table 4.

[0067] Table 3 Performance data of high-functionality melamine rigid foam polyol and polyhydroxy structure amino resin in Examples 1 to 6 and Comparative Example 1

[0068]

[0069] Table 4 Performance data of polyurethane rigid foams prepared in Examples 1 to 6 and Comparative Example 1

[0070]

[0071] It can be seen from the performance data in Table 3 that in the conventional performance index data of the high-functionality melamine rigid foam polyols prepared in Examples 1 to 6 of the present invention, the hydroxyl value is greater than that of Comparative Example 1, as high as 572.30 mgKOH / g, which is beneficial to the improvement of the mechanical properties of the foam in the later foaming; the viscosity of Comparative Example 1 is high, which is 15940 mPa·s / 25°C. This is because its reaction temperature is high, and cross-linking easily occurs between the polyhydroxy structure amino resin molecules, resulting in high viscosity, which is not convenient for later application operations, and high high temperature energy consumption, while the viscosity of Examples 1 to 6 can be as low as 4450 mPa·s / 25°C, which is convenient for later operations, and its reaction temperature is mild, between 80 and 129°C, with low temperature, low energy consumption, and simple steps; the high-functionality melamine rigid foam polyol prepared by the present invention has the advantages of large hydroxyl value and low viscosity.

[0072] From the performance data of the polyurethane rigid foams in Examples 1 to 6 and Comparative Example 1 in Table 4, it can be seen that the dimensional change rate of the polyurethane rigid foams in the length, width and height directions in Examples 1 to 6 can be less than 0.1%, the dimensional stability is good, the compressive strength can be as high as 194.20 kPa, and the mechanical properties are good.

[0073] In summary, the present invention has the advantages of simple preparation steps, mild conditions, low energy consumption, low viscosity and high hydroxyl value of high-functionality melamine rigid foam polyol, and good dimensional stability and mechanical properties of polyurethane rigid foam, and has achieved good technical effects, and can be used in the industrial production of polyurethane foam.

Claims

1. A high-functionality melamine rigid foam polyol, the molecular structure of which is as follows: in, R is selected from one of R1 and R2, R1 is selected from one of -CH2CH(CH3)OH, -CH2CH(OH)CH2OH or -CH(CH3)CH2OCH2CH(CH3)OH, and R2 is selected from one of -CH2CH2OCH2CH(CH3)OH or -CH(CH3)CH2OCH2CH2OCH2CH(CH3)OH.

2. A method for preparing the high-functionality melamine rigid foam polyol according to claim 1, comprising the following steps: (1) adding hexamethoxymethylmelamine, polyol and diol into a reaction kettle at a molar ratio of 1:1-6:1-6 to form material I, wherein the diol is obtained by reacting ethylene glycol with propylene oxide; (2) Under stirring conditions, the material is heated using a heating medium. When the temperature of the material in the reactor reaches 80 to 129° C., an acidic regulator is added to the material I to adjust the pH value of the system to 2 to 6, thereby obtaining the material II; (3) Material II is reacted under normal pressure, the reaction temperature is 80-129° C., and the reaction time is 3-8 h to obtain material III; (4) adding an alkaline regulator to material III to adjust the pH value of the system to 7-9 to obtain material IV; (5) subjecting material IV to vacuum distillation to separate small molecules in the system, wherein the vacuum distillation temperature is 80 to 129° C. and the pressure is -0.08 to -0.10 MPa, as measured by gauge pressure, to obtain material V; (6) monitoring the moisture content of material V until the moisture content by mass is ≤0.5%, thereby obtaining a high-functionality melamine rigid foam polyol; in, The polyol in step (1) is selected from at least one of propylene glycol, dipropylene glycol or glycerol, and the diol is obtained by reacting ethylene glycol and propylene oxide in a molar ratio of 1:1 or 1:2; the acidic regulator in step (2) is selected from at least one of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, p-toluenesulfonic acid, acetic acid, formic acid or oxalic acid, and the alkaline regulator in step (4) is selected from at least one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution or alkaline organic amines.

3. The method for preparing high-functionality melamine rigid foam polyol according to claim 2, characterized in that The functionality of the diol is 2, and the hydroxyl value is 550-950 mgKOH / g.

4. The method for preparing high-functionality melamine rigid foam polyol according to claim 2, characterized in that The small molecule substance in step (5) is a mixture of free formaldehyde, water, methanol and diol.

5. Use of the high-functionality melamine rigid foam polyol according to claim 1 in polyurethane foam.

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