Flame retardant polyurethane rigid foam, preparation method and application thereof

Abstract

The present invention relates to a flame retardant polyurethane rigid foam, a preparation method and an application thereof, and mainly solves the problem of high cost in the flame retardant polyurethane rigid foam in the prior art. The present invention adopts a new flame retardant polyurethane rigid foam, which is composed of the following components by weight: component A: including 60-80 parts of polyether polyol, 20-40 parts of modified urea-formaldehyde resin, 0.1-15 parts of foaming agent, 0.01-5 parts of foam stabilizer, 0.1-5 parts of water, and 0.01-5 parts of catalyst; component B: 110-180 parts of isocyanate; and the technical scheme of the preparation method thereof, which better solves the problem and can be used in building thermal insulation materials.

Description

Technical Field

[0001] The invention relates to a flame retardant polyurethane rigid foam, a preparation method and application thereof. Background Art

[0002] Rigid polyurethane foam (RPUF), also known as rigid polyurethane foam, is an organic polymer material mainly generated by the reaction of isocyanate and polyol. RPUF is widely used in construction, automobiles, furniture, electronics, aerospace and other fields due to its advantages such as light weight, good thermal insulation performance and high compressive strength. However, RPUF without flame retardant treatment is a highly flammable material, and a large amount of smoke and toxic gases such as CO, NO, HCN will be produced during the combustion process, posing a huge hidden danger to human life and property safety. With the continuous expansion of the application field of RPUF, the potential fire hazard is also increasing. Therefore, research on flame retardant modification of RPUF has practical significance for preventing problems before they occur.

[0003] The combustion process of RPUF can be simply summarized as follows: (1) RPUF decomposes under high temperature to produce flammable gas; (2) When the flammable gas reaches a certain concentration and temperature in the gas phase, it will burn in the air environment; (3) The heat generated by the combustion of the flammable gas causes the RPUF to further degrade until the RPUF is completely burned. Based on its combustion process, the flame retardant mechanism of RPUF is mainly divided into condensed phase flame retardant mechanism and gas phase flame retardant mechanism. Condensed phase flame retardant mechanism: (1) The flame retardant decomposes and absorbs heat after being heated, reducing the surface temperature of the material and preventing it from reaching the decomposition temperature; (2) The flame retardant decomposes under heat to form a non-flammable porous carbon layer covering the surface of the material, which acts as a heat and oxygen barrier, thereby inhibiting the combustion. Gas phase flame retardant mechanism: (1) The flame retardant decomposes to produce non-flammable gas, which reduces the concentration of flammable gas and oxygen, causing the combustion to terminate; (2) The fine particles generated by the flame retardant when heated can combine free radicals, thereby terminating the combustion chain reaction.

[0004] Chinese patent CN 106046285 B can also meet the requirements for preparing flame-retardant polyurethane rigid foam by synthesizing a melamine series polyol, but the melamine series polyol has a high cost and is therefore not the best solution for flame-retardant polyurethane rigid foam plastics. Summary of the invention

[0005] One of the technical problems to be solved by the present invention is that the flame retardant polyurethane rigid foam in the prior art has the problem of high cost, and a new flame retardant polyurethane rigid foam is provided, which has the advantages of good flame retardancy and durability and low cost.

[0006] In order to solve one of the above technical problems, the technical solution adopted by the present invention is as follows: a flame retardant polyurethane rigid foam, which is composed of the following components in parts by weight: (1) component A: including 60-80 parts of polyether polyol, 20-40 parts of modified urea-formaldehyde resin, 0.1-15 parts of foaming agent, 0.01-5 parts of foam stabilizer, 0.1-5 parts of water, and 0.01-5 parts of catalyst; (2) component B: 110-180 parts of isocyanate.

[0007] In the above technical solution, preferably, in the step (1), the functionality of the polyether polyol is 2-6, and the hydroxyl value is 200-600 mgKOH / g.

[0008] In the above technical scheme, preferably, the polyether polyol is selected from one of NJ-4110 and NJ-8238; the blowing agent is at least one of HCFC-141b, CFC-11 or cyclopentane; the foam stabilizer is at least one of AK8805, UA6001 or L6900; the catalyst is at least one of PC-5, PC-8 or PC-41; and the isocyanate is M20S.

[0009] In the above technical solution, preferably, the preparation method of the modified urea-formaldehyde resin in step (1) is as follows:

[0010] (1) adding urea, melamine, paraformaldehyde and polyol in a molar ratio of 1:0.1-0.3:2-6:2-6 into a reaction kettle to form material I;

[0011] (2) heating under stirring conditions, when the temperature of the material in the reactor is 70-100° C., adjusting the pH of the system to 9-11, and the reaction time is 1-3 hours to obtain material II;

[0012] (3) Adding a pH adjuster under normal pressure to adjust the pH to 3-5, the reaction temperature to 70-100° C., and reacting for 1-3 hours to obtain material III;

[0013] (4) adding a pH regulator to material III to adjust the pH to 7-8 to obtain material IV;

[0014] (5) subjecting material IV to vacuum distillation to separate small molecular substances in the system to obtain modified urea-formaldehyde resin.

[0015] In the above technical scheme, preferably, the polyol in step (1) is selected from at least one of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol or glycerol; the pH adjusting agent in step (2) and step (4) is at least one of an aqueous solution of sodium hydroxide or potassium hydroxide or an alkaline organic amine; the pH adjusting agent in step (3) is a stock solution or aqueous solution of one or more of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, p-toluenesulfonic acid, formic acid and oxalic acid; the small molecule by-product in step (5) is a mixture of free formaldehyde, water and methanol; the reduced pressure distillation temperature is 70 to 100°C and the pressure is -0.08 to -0.10 MPa.

[0016] To solve the second of the above technical problems, the technical solution adopted by the present invention is as follows:

[0017] A method for preparing the aforementioned flame retardant polyurethane rigid foam comprises the following steps:

[0018] (1) 60-80 parts of polyether polyol, 20-40 parts of modified urea-formaldehyde resin, 0.1-15 parts of foaming agent, 0.01-5 parts of foam stabilizer, 0.1-5 parts of water, and 0.01-5 parts of catalyst are uniformly mixed to obtain component A;

[0019] (2) Weighing 110-180 parts of isocyanate and controlling the temperature at 20-25° C. to obtain component B;

[0020] (3) Control the mold temperature at 20-50°C, add component B to component A, and quickly stir to obtain material C;

[0021] (4) Pour material C into a mold to foam it, and demould it after the foam matures to obtain the flame retardant polyurethane rigid foam.

[0022] To solve the third of the above technical problems, the technical solution adopted by the present invention is as follows:

[0023] The aforementioned flame retardant polyurethane rigid foam is used in building thermal insulation materials.

[0024] The present invention provides a flame retardant polyurethane rigid foam and a preparation method thereof, which has the beneficial effects of: using a special modified urea-formaldehyde resin to replace the conventional additive halogen-containing flame retardant to act on the polyurethane foam plastic, effectively solving the problems of poor flame retardant performance of ordinary rigid polyurethane foam plastic and high flame retardant cost. The combustion oxygen index of the polyurethane rigid foam plastic prepared by the method of the present invention can reach more than 26%, greatly improving the flame retardant performance of the polyurethane foam plastic, while maintaining various excellent properties of the polyurethane foam plastic, meeting the fire resistance requirements of the polyurethane foam plastic, and the preparation steps are simple, the process conditions are easy to control, it is environmentally friendly, the raw material cost is low, it is suitable for industrial production, and has achieved good technical effects. DETAILED DESCRIPTION

[0025] The following are only preferred implementations of the present invention, and are not intended to limit the scope of protection of the present invention. All technical solutions within the scope of the present invention should fall within the scope of protection of the present invention. For professional and technical personnel 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.

[0026] [Example 1]

[0027] 1. A flame retardant polyurethane rigid foam, the preparation method of which comprises the following steps:

[0028] (1) 60 parts of polyether polyol 4110, 40 parts of modified urea-formaldehyde resin, 12 parts of foaming agent HCFC-141b, 1.5 parts of foam stabilizer AK8805, 2 parts of water, and 0.7 parts of catalyst PC-8 were mixed uniformly to obtain component A;

[0029] (2) Weighing 165 parts of isocyanate M20S and controlling the temperature at 25° C. to obtain component B;

[0030] (3) Control the mold temperature at 45°C, add component B to component A, and quickly stir to obtain material C;

[0031] (4) Pour material C into a mold, foam it, mature it, and then demould it to obtain the flame-retardant polyurethane rigid foam. The preparation method of the modified urea-formaldehyde resin is as follows:

[0032] (1) adding urea, melamine, paraformaldehyde and polyol into a reaction kettle in a molar ratio of 1:0.1:3:3 to form material I;

[0033] (2) heating under stirring conditions, when the temperature of the material in the reactor is 75°C, adjusting the pH of the system to 9, the reaction time is 1 hour, and obtaining material II;

[0034] (3) Adding a pH adjuster under normal pressure to adjust the pH to 4, the reaction temperature to 75°C, and reacting for 2 hours to obtain material III;

[0035] (4) adding a pH adjuster to material III and adjusting the pH to 7.5 to obtain material IV;

[0036] (5) Material IV was subjected to vacuum distillation to remove small molecular by-products. The vacuum distillation temperature was 75° C. and the pressure was −0.098 MPa. The solid salt was filtered out to obtain a modified urea-formaldehyde resin S1.

[0037] [Examples 2 to 6]

[0038] Examples 2 to 6 are carried out according to the steps in Example 1. The material ratios are shown in Table 1. The preparation method of the modified urea-formaldehyde resin is shown in Table 2, wherein the concentrations of the pH adjusting agents are all mass percentage concentrations. The performance index data of the flame retardant polyurethane rigid foam obtained are shown in Table 3.

[0039] Table 1 Mass fractions of polyurethane rigid foam formulations in Examples 1 to 6 and Comparative Example 1

[0040]

[0041] Table 2 Raw material molar ratio and reaction conditions in the preparation of modified urea-formaldehyde resin in Examples 1 to 6

[0042]

[0043]

[0044] [Comparative Example 1]

[0045] 1. Prepare propylene glycol type melamine polyol S according to the scheme in Example 1 in patent CN 106046285 B, and add it to the formula of the polyurethane rigid foam plastic of the present invention, the steps are as follows:

[0046] (1) By weight, 60 parts of polyether polyol, 15 parts of foaming agent, 2 parts of catalyst, 2 parts of foam stabilizer, 1 part of water and 40 parts of propylene glycol type melamine polyol are mixed uniformly by high-speed stirring in a mixer to prepare a white material;

[0047] (2) mixing the above white material with 135 parts of polyisocyanate and injecting into a foaming equipment for foaming molding;

[0048] (3) Demolding and cutting to obtain specimens.

[0049] The performance index data of the prepared polyurethane foam plastic are shown in Table 3.

[0050] Table 3 Performance data of polyurethane rigid foam prepared in Examples 1 to 6 and Comparative Example 1

[0051]

[0052] It can be seen from the performance data in Table 3 that the oxygen index of the low-cost polyurethane rigid foam prepared in Examples 1 to 6 of the present invention has reached more than 23%. Although the oxygen index of Comparative Example 1 can reach 24.5%, its raw material cost is relatively high, because the raw material cost of propylene glycol melamine polyol is higher than the cost of urea-formaldehyde resin in the present invention; the oxygen index of Comparative Example 2 reaches 23.2%, but the compressive strength is also about 18% lower, because TCPP is added, which is an additive flame retardant and cannot be grafted into the foam molecular structure through reaction; the oxygen index of Comparative Example 3 is only 19.9%, and there is basically no flame retardant effect. The modified urea-formaldehyde resin used in the present invention is a reactive nitrogen-containing flame retardant, which can react chemically with black material isocyanate, thereby effectively maintaining the excellent mechanical strength of polyurethane, making the flame retardancy more lasting and the cost lower, achieving better technical effects, and can be used in the application of polyurethane rigid foam.

Claims

1. A flame retardant polyurethane rigid foam is used in building insulation materials, wherein: The flame retardant polyurethane rigid foam is composed of the following components in parts by weight: (1) Component A: 60-80 parts of polyether polyol, 20-40 parts of modified urea-formaldehyde resin, 0.1-15 parts of foaming agent, 0.01-5 parts of foam stabilizer, 0.1-5 parts of water, and 0.01-5 parts of catalyst; (2) Component B: 110-180 parts of isocyanate; wherein the functionality of the polyether polyol is 2-6 and the hydroxyl value is 200-600 mgKOH / g; the polyether polyol is selected from one of NJ-4110 and NJ-8238; the foaming agent is at least one of HCFC-141b, CFC-11 or cyclopentane; the foam stabilizer is at least one of AK8805, UA6001 or L6900; the catalyst is at least one of PC-5, PC-8 or PC-41; the isocyanate is M20S; The preparation method of the modified urea-formaldehyde resin is as follows: (1) adding urea, melamine, paraformaldehyde and polyol into a reaction kettle at a molar ratio of 1:0.1-0.3:2-6:2-6 to form material I, wherein the polyol is at least one selected from ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol or glycerol; (2) Heating and raising the temperature under stirring conditions, when the temperature of the material in the reactor is 70-100°C, adjusting the pH of the system to 9-11, and the reaction time is 1-3 hours to obtain material II; (3) Add a pH adjuster under normal pressure to adjust the pH to 3-5, the reaction temperature to 70-100°C, and react for 1-3 hours to obtain material III; (4) Adding a pH regulator to material III and adjusting the pH to 7-8 to obtain material IV; (5) Material IV is subjected to reduced pressure distillation to separate small molecular substances in the system to obtain modified urea-formaldehyde resin.

2. The flame retardant polyurethane rigid foam according to claim 1 is used in building thermal insulation materials, characterized in that: In the preparation method of the modified urea-formaldehyde resin, the pH adjusting agent in step (2) and step (4) is at least one of an aqueous solution of sodium hydroxide, potassium hydroxide or an alkaline organic amine; the pH adjusting agent in step (3) is a stock solution or aqueous solution of one or more of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, p-toluenesulfonic acid, formic acid and oxalic acid; the small molecular by-product in step (5) is a mixture of free formaldehyde, water and methanol; the reduced pressure distillation temperature is 70-100° C. and the pressure is -0.08--0.10 MPa.

3. The flame retardant polyurethane rigid foam according to claim 1 is used in building thermal insulation materials, characterized in that: The method for preparing the flame retardant polyurethane rigid foam comprises the following steps: (1) 60-80 parts of polyether polyol, 20-40 parts of modified urea-formaldehyde resin, 0.1-15 parts of foaming agent, 0.01-5 parts of foam stabilizer, 0.1-5 parts of water and 0.01-5 parts of catalyst are uniformly mixed to obtain component A; (2) Weigh 110-180 parts of isocyanate and control the temperature at 20-25°C to obtain component B; (3) Control the mold temperature at 20-50°C, add component B to component A, and quickly stir to obtain material C; (4) Pour material C into a mold to foam it, and demould it after the foam matures to obtain the flame retardant polyurethane rigid foam.

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