Preparation method of high-flame-retardant regenerated PIR foam

Abstract

The invention relates to a preparation method of high-flame-retardant regenerated PIR foam, which comprises the following steps: adding a waste PIR material into a sodium hydroxide solution for pretreatment, and putting the pretreated PIR material and fatty amine into a hydrothermal reaction kettle; adding alkaline hydroxide into the hydrothermal reaction kettle, heating, stirring, cooling, standing, recovering and distilling an upper-layer product in the product to obtain a product A; the preparation method comprises the following steps: mixing expanded graphite, layered double hydroxide and rare earth oxide, heating, and cooling to room temperature to obtain a component A; mixing a foaming agent, a catalyst, a foam stabilizer and the product A, and stirring to obtain a component B; adding the component A into the component B, and then adding deionized water to obtain a component C; and mixing the component C with isocyanate in proportion, pouring the mixture into a foaming mold for foaming to prepare flame-retardant foam, and then putting the flame-retardant foam into a drying oven for curing treatment. The regenerated PIR foam prepared by the invention is relatively high in flame retardant property, simple in preparation process and relatively low in cost, and the market competitiveness and economic benefits of the PIR foam are improved.

Description

Technical Field

[0001] The present invention relates to the technical fields of PIR material degradation and recycled foam preparation, and specifically to a method for preparing highly flame-retardant recycled PIR foam. Background Art

[0002] Polyisocyanurate (PIR) foam has good high and low temperature dimensional stability, lower thermal decomposition rate and thermal conductivity, and better mechanical strength, and is widely used in fields such as petrochemical industry, construction, and electric power. The isocyanurate ring in PIR can improve the temperature resistance and flame retardancy of PIR foam, but the flame retardancy is insufficient. With the strengthening of the fire protection grade requirements for polymer materials, PIR foam faces the challenge of further improving its flame retardant performance. To improve the flame retardant performance of PIR, flame retardants are usually selected to be added during its preparation. During combustion, the flame retardant can prevent the polymer material from being ignited or hinder the spread of the flame to inhibit combustion.

[0003] Chinese Patent CN114736364A proposes a method for preparing a reactive flame-retardant polyether polyol using 3,4-dibromo-3-chloro-1,2-diol as the initiator and applying it to the preparation of PIR foam. This method can prepare flame-retardant PIR foam with good dimensional stability, high compressive strength, and low thermal conductivity. However, by using polyols containing halogenated flame-retardant elements or groups to prepare PIR flame-retardant foam, the process is cumbersome, the cost is high, and the halogenated flame retardant will have an adverse impact on the environment during combustion.

[0004] Chinese Patent CN201910915674.7 proposes a method for preparing nano-scale transition metal oxide-supported expanded graphite particles by calcination, ultrasonic-microwave, making it have the advantages of flame retardancy and smoke suppression. However, the calcination needs to be carried out at 800°C. This method has high requirements for equipment and harsh process conditions, and cannot be applied industrially; the prepared flame-retardant particles have poor compatibility with the matrix, and as additives, they reduce the mechanical properties of the material.

[0005] Currently, the flame retardants used to prepare flame-retardant PIR foam usually include halogen-based flame retardants and phosphorus-based flame retardants. However, halogen-based flame retardants have a large amount of smoke generation, and substances such as hydrogen halide gas, dioxins, and organic halides generated during combustion are toxic and corrosive, threatening human life and property safety, and affecting environmental protection and ecological construction. Phosphorus-based flame retardants have poor compatibility. Inorganic phosphorus-based flame retardants such as red phosphorus are prone to generating toxic and harmful gases, and organic phosphorus-based flame retardants have poor thermal stability, large smoke generation, strong volatility, high price, high addition amount, and reduce the material properties. Halogen-based flame retardants and phosphorus-based flame retardants are not only expensive, have poor effects when used alone, and affect the mechanical properties of the material, but also produce toxic substances to pollute the environment when used to prepare PIR foam. Summary of the Invention

[0006] The present invention aims to provide, compared with the prior art, a method for preparing a flame-retardant PIR foam that can replace the use of halogen-based flame retardants and phosphorus-based flame retardants, which cause problems such as environmental pollution by toxic and harmful gases, high prices, and degradation of material properties. The method proposes using the degradation products obtained by treating PIR materials with fatty amines and alkaline metal hydroxides as raw materials, and adding a flame retardant system composed of expanded graphite as a flame retardant, layered double hydroxides, and rare earth oxides as synergists to the degradation products to prepare a highly flame-retardant recycled PIR foam.

[0007] To solve the above technical problems, the specific solution adopted in the present invention is a method for preparing a highly flame-retardant recycled PIR foam, which specifically includes the following steps:

[0008] S1: Take the PIR material, crush it, add it to a sodium hydroxide solution for pretreatment, and then filter, wash, and dry it in sequence;

[0009] S2: Place the particles obtained in S1 and the fatty amine in a hydrothermal reaction kettle, heat to 120 - 150 °C and stir;

[0010] S3: Add the alkaline hydroxide to the hydrothermal reaction kettle, heat to 170 - 220 °C and stir, then cool and let stand;

[0011] S4: Layer and purify the product in S3, recover and distill the upper-layer product to obtain product A;

[0012] S5: Mix the expanded graphite, layered double hydroxides, and rare earth oxides, heat to 150 - 200 °C, and then cool to room temperature to obtain component A;

[0013] S6: Mix, stir the blowing agent, catalyst, foam stabilizer with product A obtained in S4 to obtain component B; Add component A in step S5 to component B, and then add deionized water and stir to obtain component C;

[0014] S7: Mix and stir component C in S6 and isocyanate in proportion, pour it into a foaming mold for foaming to prepare a flame-retardant foam, and then place the flame-retardant foam in an oven at 50 - 70 °C for curing treatment.

[0015] As an optimized scheme of the above method for preparing a highly flame-retardant recycled PIR foam: In step S2, the mass ratio of the fatty amine to the PIR material is 0.2 - 2:1.

[0016] As another optimized scheme of the above method for preparing a highly flame-retardant recycled PIR foam: The fatty amine is one of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0017] As another optimization scheme of the above preparation method of a highly flame-retardant recycled PIR foam: In step S3, the mass ratio of the alkaline hydroxide to the PIR material is 0.1 - 0.6:1.

[0018] As another optimization scheme of the above preparation method of a highly flame-retardant recycled PIR foam: The alkaline hydroxide is one or more of NaOH, KOH, LiOH, Al(OH)3, and Ca(OH)2.

[0019] As another optimization scheme of the above preparation method of a highly flame-retardant recycled PIR foam: In the layered double hydroxide, the molar ratio of Mg 2+ to Al 3+ is 3:1.

[0020] As another optimization scheme of the above preparation method of a highly flame-retardant recycled PIR foam: The rare earth oxide is one of La2O3, CeO2, and Y2O3.

[0021] As another optimization scheme of the above preparation method of a highly flame-retardant recycled PIR foam: The foaming agent in step S6 is one of HCFC141b, HCFC-22, cyclopentane, and petroleum ether; the catalyst is one of triethylamine, triethyleneimine, N,N-dimethylcyclohexylamine, triethanolamine, dimethylethanolamine, dibutyltin dilaurate, dibutyltin diacetate, potassium oleate, and stannous octoate; the foam stabilizer is one of silicone oil SD611, silane foam stabilizer AK8803, silane foam stabilizer AK880, and silane foam stabilizer L580.

[0022] As another optimization scheme of the above preparation method of a highly flame-retardant recycled PIR foam: The mass percentage of the foam stabilizer to product A is 12 - 18%; the mass percentage of the catalyst to product A is 3 - 10%; the mass percentage of the foam stabilizer to product A is 2 - 8%; the mass percentage of the layered double hydroxide to product A is 1 - 5%; the mass percentage of the rare earth oxide to product A is 0.5 - 1.5%.

[0023] As another optimization scheme of the above preparation method of a highly flame-retardant recycled PIR foam: The isocyanate in step S7 is one of polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, and toluene diisocyanate.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention degrades PIR materials through the synergistic action of alkaline hydroxides and fatty amines, which can reduce the temperature required for the degradation reaction of waste PIR and accelerate the reaction rate. Moreover, since the layered double hydroxides (LDHs) in the present invention are layered inorganic nanomaterials and do not contain any toxic substances themselves, they are excellent flame-retardant and smoke-suppressing green materials. LDHs can decompose into CO2, H2O, metal oxides, etc. during the combustion process. On the one hand, a large amount of CO2 and H2O are released, which can dilute combustible gases and O2, absorb a large amount of heat, and reduce the temperature of the combustion system; on the other hand, the metal oxides generated by thermal decomposition will form a protective film, which plays a role in isolating O2 and heat, and further reduces the degradation rate of the substrate. The rare earth oxides in the present invention help to improve the flame retardancy of polymers. The large number of empty orbitals of rare earth elements have a strong ability to combine with free radicals. When the rare earth oxides are heated, they will undergo redox reactions with free radicals involving single or multiple electron transfers, being reduced from a high valence state to a low valence state, capturing free radicals and hindering their combustion; secondly, due to the presence of rare earth elements, a complex structure is formed, which hinders the oxidation process, thereby improving the heat resistance and flame retardancy of PIR materials; it can also make the generated carbon layer more dense, uniform and hard, increasing the stability of the carbon layer and further preventing the spread of flames; in addition, the layered double hydroxide contains chemically active Mg, and the formed magnesium oxide has a loose structure, resulting in the infiltration of oxygen. If an appropriate amount of rare earth oxides is added, it can effectively promote the sintering of Mg-containing materials at high temperatures, enhance the denseness of the materials, and further improve the flame retardancy of the materials. The layered double hydroxides (LDHs) and rare earth oxides, as synergists, form a synergistic flame-retardant system with expanded graphite, and its comprehensive flame-retardant effect is better than that of the expanded graphite single flame-retardant system. Adding the flame-retardant system to the PIR matrix can effectively increase the ignition time and improve the self-extinguishing property of the polymer. Therefore, the regenerated PIR foam prepared by the preparation method using the degradation product as a raw material and adding expanded graphite, layered double hydroxides (LDHs), and rare earth oxides has high flame retardancy, and the preparation process is non-toxic and harmless, which is not only beneficial to the harmless treatment of waste, but also reduces environmental pollution, promotes sustainable development, can effectively reduce costs, and improves market competitiveness. Detailed implementation manners

[0026] A preparation method of a highly flame-retardant regenerated PIR foam according to the present invention specifically includes the following steps:

[0027] S1: Take the PIR material, crush it, add it to a sodium hydroxide solution for pretreatment, and then filter, wash and dry it in sequence.

[0028] S2: Place the particles obtained in S1 and the fatty amine in a hydrothermal reaction kettle, heat up to 120-150 °C and stir.

[0029] The above-mentioned particles are mixed with fatty amine and stirred by a stirrer arranged in a hydrothermal reactor, and the reaction time is 1-3 h.

[0030] The above-mentioned fatty amine is one of ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine, and the mass ratio of fatty amine to PIR material is 0.2-2:1.

[0031] S3: Add alkaline hydroxide into the hydrothermal reactor, heat up to 170-220 °C and stir, then cool and stand still.

[0032] S4: Layer and purify the product in S3, recover and distill the upper-layer product to obtain product A.

[0033] The above-mentioned alkaline hydroxide is one or more of NaOH, KOH, LiOH, Al(OH)3 and Ca(OH)2, and the mass ratio of alkaline hydroxide to PIR material is 0.1-0.6:1.

[0034] S5: Mix expanded graphite, layered double hydroxide and rare earth oxide, heat to 150-200 °C, and then cool to room temperature to obtain component A.

[0035] In the above-mentioned layered double hydroxide, the molar ratio of Mg 2+ to Al 3+ is 3:1.

[0036] The above-mentioned rare earth oxide is one of La2O3, CeO2 and Y2O3.

[0037] The mass ratio of the above-mentioned expanded graphite to product A is 0.03-0.15:1.

[0038] The mass percentage of the above-mentioned layered double hydroxide in product A is 1-5%.

[0039] The mass percentage of the above-mentioned rare earth oxide in product A is 0.5-1.5%.

[0040] S6: Mix the foaming agent, catalyst, foam stabilizer with product A obtained in S4 and stir to obtain component B; add component A in step S5 into component B, and then add deionized water and stir to obtain component C.

[0041] The above-mentioned foaming agent is one of HCFC141b, HCFC-22, cyclopentane and petroleum ether.

[0042] The above-mentioned catalyst is one of triethylamine, triethyleneimine, N,N-dimethylcyclohexylamine, triethanolamine, dimethylethanolamine, dibutyltin dilaurate, dibutyltin diacetate, potassium oleate and stannous octoate.

[0043] The above-mentioned foam stabilizer is one of silicone oil SD611, silane foam stabilizer AK8803, silane foam stabilizer AK880, and silane foam stabilizer L580.

[0044] The mass percentage of the above-mentioned foam stabilizer and product A is 12-18%; the mass percentage of the catalyst and product A is 3-10%; the mass percentage of the foam stabilizer and product A is 2-8%.

[0045] S7: Mix component C in S6 and isocyanate in proportion, stir, and pour the mixture into a foaming mold for foaming to prepare a flame-retardant foam. Then, place the flame-retardant foam in an oven at 50-70°C for curing treatment.

[0046] The above-mentioned isocyanate is one of polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, and toluene diisocyanate.

[0047] Example 1

[0048] Crush the waste PIR material into particles, wash it with clean water and 1mol / L sodium hydroxide solution, and then wash the PIR particles with clean water until neutral. Mix the PIR particles and ethylenediamine and place them in a hydrothermal reaction kettle, while stirring, heat up to 120°C. After reacting for 1.5h, add NaOH into the hydrothermal reaction kettle, while continuing to stir, heat up to 180°C and react for 3h. After the product is cooled to room temperature, let it stand for 1h, separate and purify to recover the upper-layer product to obtain product A.

[0049] Then, weigh a certain amount of expanded graphite, layered double hydroxide, La2O3 and mix them, and heat to 150°C. After heating for 10min, then cool it to room temperature to obtain component A. Then, fully mix and stir HCFC141b, triethylamine, silane foam stabilizer AK8803 and product A to obtain component B, add component A to component B, then add 2g of deionized water and stir evenly to obtain component C. Then, mix component C and toluene diisocyanate in proportion, quickly stir for 20s and then pour it into a foaming mold for foaming to prepare a flame-retardant foam, and place the prepared flame-retardant foam in an oven at 50°C for 24h for curing treatment.

[0050] Among them, the mass ratio of ethylenediamine, NaOH and PIR particles is 0.5:0.2:1. The mass ratio of HCFC141b, triethylamine, silane foam stabilizer AK8803, expanded graphite, layered double hydroxide, La2O3 and product A is 0.15:0.05:0.03:0.05:0.02:0.005:1. The mass ratio of product A and toluene diisocyanate is 1:1.2.

[0051] Example 2

[0052] The waste PIR material is crushed into particles, washed with clean water and 1 mol / L sodium hydroxide solution, and then washed with clean water until the PIR particles are neutral. The PIR particles are mixed with diethylenetriamine and placed in a hydrothermal reaction kettle, and stirred while heating to 130 °C. After reacting for 2 h, KOH is added to the hydrothermal reaction kettle, and the temperature is raised to 200 °C while continuing to stir, and the reaction is carried out for 4 h. After the product is cooled to room temperature, it is left standing for 1 h, and the upper layer product is separated and purified to obtain product A.

[0053] Then, a certain amount of expanded graphite, layered double hydroxide, and CeO2 are weighed and mixed, and heated to 150 °C. After heating for 10 min, it is cooled to room temperature to obtain component A. Then, HCFC-22, dimethylethanolamine, and silane foam stabilizer L580 are fully mixed and stirred with product A to obtain component B, and component A is added to component B, and then 2 g of deionized water is added and stirred evenly to obtain component C. Then, component C and phenylmethane diisocyanate are mixed in proportion, quickly stirred for 20 s, and then poured into a foaming mold for foaming to obtain a flame-retardant foam, and the obtained flame-retardant foam is placed in an oven at 50 °C for 24 h for curing treatment.

[0054] Among them, the mass ratio of PIR particles to diethylenetriamine and KOH is 1:0.8:0.5. The mass ratio of HCFC-22, dimethylethanolamine, silane foam stabilizer L580, expanded graphite, layered double hydroxide, CeO2 to product A is 0.13:0.07:0.05:0.08:0.02:0.01:1. The mass ratio of product A to phenylmethane diisocyanate is 1:1.2.

[0055] Example 3

[0056] The waste PIR material is crushed into particles, washed with clean water and 1 mol / L sodium hydroxide solution, and then washed with clean water until the PIR particles are neutral. The PIR particles are mixed with triethylenetetramine and placed in a hydrothermal reaction kettle, and stirred while heating to 130 °C. After reacting for 2 h, Ca(OH)2 is added to the hydrothermal reaction kettle, and the temperature is raised to 200 °C while continuing to stir, and the reaction is carried out for 5 h. After the product is cooled to room temperature, it is left standing for 1 h, and the upper layer product is separated and purified to obtain product A.

[0057] Then, weigh a certain amount of expanded graphite, layered double hydroxide, and Y2O3 and mix them, and heat to 200 °C. After heating for 5 min, cool it to room temperature to obtain Component A. Then, fully mix and stir cyclopentane, dibutyltin dilaurate, silicone oil SD611 with Product A to obtain Component B, add Component A to Component B, then add 2 g of deionized water and stir evenly to obtain Component C. Then, mix Component C with toluene diisocyanate in proportion, quickly stir for 20 s, pour it into a foaming mold for foaming to obtain a flame-retardant foam, and place the obtained flame-retardant foam in an oven at 50 °C for 24 h for curing treatment.

[0058] Among them, the mass ratio of PIR particles, triethylenetetramine, and Ca(OH)2 is 1:0.8:0.5. The mass ratio of cyclopentane, dibutyltin dilaurate, silicone oil SD611, expanded graphite, LDHs, Y2O3 to Product A is 0.13:0.07:0.05:0.08:0.02::0.01:0.012:1. The mass ratio of Product A to toluene diisocyanate is 1:1.2.

[0059] Example 4

[0060] Crush the waste PIR material into particles, wash it with clean water and 1 mol / L sodium hydroxide solution, and then wash the PIR particles with clean water until neutral. Mix the PIR particles with tetraethylenepentamine and place them in a hydrothermal reaction kettle, and stir while heating to 150 °C. After reacting for 2.5 h, add NaOH to the hydrothermal reaction kettle, continue to stir while heating to 200 °C, and react for 3 h. After the product cools to room temperature, let it stand for 1 h, separate and purify to recover the upper-layer product to obtain Product A.

[0061] Then, weigh a certain amount of expanded graphite, layered double hydroxide, and La2O3 and mix them, and heat to 190 °C. After heating for 15 min, cool it to room temperature to obtain Component A. Then, fully mix and stir HCFC141b, dibutyltin diacetate, silicone oil SD611 with Product A to obtain Component B, add Component A to Component B, then add 2 g of deionized water and stir evenly to obtain Component C. Then, mix Component C with toluene diisocyanate in proportion, quickly stir for 20 s, pour it into a foaming mold for foaming to obtain a flame-retardant foam, and place the obtained flame-retardant foam in an oven at 50 °C for 24 h for curing treatment.

[0062] Among them, the mass ratio of PIR particles, tetraethylenepentamine, and NaOH is 1:0.8:0.5. The mass ratio of HCFC141b, dibutyltin diacetate, silicone oil SD611, expanded graphite, LDHs, La2O3, and product A is 0.13:0.07:0.05:0.08:0.02::0.01:0.015:1. The mass ratio of product A to toluene diisocyanate is 1:1.2.

[0063] The compressive strength, volume water absorption, thermal conductivity, and oxygen index of the foam materials prepared in Examples 1-4 were measured by a testing device, and the test results are shown in the following table:

[0064] In summary, the comprehensive properties of the prepared foam are higher than the national standards. Moreover, the regenerated PIR foam with high flame retardancy prepared by the preparation method of the present invention has excellent thermal conductivity and mechanical properties. In addition, the flame retardant used in the preparation method is inexpensive, non-toxic, and harmless, and does not pollute the environment. The preparation process is simple, with low cost, effectively broadening the application fields of PIR foams, and enhancing the market competitiveness and economic benefits.

Claims

1. A preparation method of a highly flame-retardant recycled PIR foam, characterized in that: Specifically, it includes the following steps: S1: Take the PIR material, crush it, add it to a sodium hydroxide solution for pretreatment, and then filter, wash, and dry it in sequence; S2: Place the particles obtained in S1 and the fatty amine in a hydrothermal reaction kettle, heat it to 120 - 150 °C and stir; S3: Add the alkaline hydroxide to the hydrothermal reaction kettle, heat it to 170 - 220 °C and stir, then cool and let it stand; S4: Layer and purify the product in S3, recover and distill the upper-layer product to obtain product A; S5: Mix expanded graphite, layered double hydroxide, and rare earth oxide, heat it to 150 - 200 °C, and then cool it to room temperature to obtain component A; S6: Mix, stir the blowing agent, catalyst, foam stabilizer with the product A obtained in S4 to obtain component B; add the component A in step S5 to component B, and then add deionized water and stir to obtain component C; S7: Mix and stir the component C in S6 and the isocyanate in proportion, pour it into a foaming mold for foaming to prepare a flame-retardant foam, and then place the flame-retardant foam in an oven at 50 - 70 °C for curing treatment.

2. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, characterized in that: In step S2, the mass ratio of the fatty amine to the PIR material is 0.2 - 2:

1.

3. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, characterized in that: The fatty amine is one of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

4. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, characterized in that: In step S3, the mass ratio of the alkaline hydroxide to the PIR material is 0.1 - 0.6:

1.

5. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, characterized in that: The alkaline hydroxide is one or more of NaOH, KOH, LiOH, Al(OH)3, and Ca(OH)2.

6. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, characterized in that: Mg in layered double hydroxide 2+ With Al 3+ The amount of substance ratio is 3:

1.

7. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, wherein: The rare earth oxide is one of La2O3, CeO2, and Y2O3.

8. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, characterized in that: In step S6, the blowing agent is one of HCFC141b, HCFC-22, cyclopentane, and petroleum ether; the catalyst is one of triethylamine, triethyleneimine, N,N-dimethylcyclohexylamine, triethanolamine, dimethylethanolamine, dibutyltin dilaurate, dibutyltin diacetate, potassium oleate, and stannous octoate; the foam stabilizer is one of silicone oil SD611, silane foam stabilizer AK8803, silane foam stabilizer AK880, and silane foam stabilizer L580.

9. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, characterized in that: The mass percentage of the foam stabilizer to product A is 12 - 18%; the mass percentage of the catalyst to product A is 3 - 10%; the mass percentage of the foam stabilizer to product A is 2 - 8%; the mass percentage of the layered double hydroxide to product A is 1 - 5%; the mass percentage of the rare earth oxide to product A is 0.5 - 1.5%.

10. The preparation method of a highly flame-retardant recycled PIR foam according to claim 1, characterized in that: In step S7, the isocyanate is one of polymethylene polyphenyl isocyanate, diphenylmethane diisocyanate, and toluene diisocyanate.

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