阅读说明：本技术 一种保温夹芯板用阻燃聚氨酯发泡保温材料及其制备方法 (Flame-retardant polyurethane foaming thermal insulation material for thermal insulation sandwich board and preparation method thereof ) 是由 万贤虎 万子涵 于 2020-12-14 设计创作，主要内容包括：本发明公开了一种保温夹芯板用阻燃聚氨酯发泡保温材料,包括下述重量份的原料：多元醇20-30份、异氰酸酯35-45份、阻燃剂15-20份、硅油2-3份、纳米添加剂1-2份、环戊烷1.5-2.5份、催化剂1-2份、交联剂0.5-1份、水0.2-0.3份；所述纳米添加剂由季铵盐插层膨润土和羧基化纳米纤维素组成。本发明还公开了保温夹芯板用阻燃聚氨酯发泡保温材料的制备方法。本发明的保温夹芯板用阻燃聚氨酯发泡保温材料兼具优良的强度、保温性能和阻燃性能,使用性能好。(The invention discloses a flame-retardant polyurethane foaming thermal insulation material for a thermal insulation sandwich board, which comprises the following raw materials in parts by weight: 20-30 parts of polyol, 35-45 parts of isocyanate, 15-20 parts of flame retardant, 2-3 parts of silicone oil, 1-2 parts of nano additive, 1.5-2.5 parts of cyclopentane, 1-2 parts of catalyst, 0.5-1 part of cross-linking agent and 0.2-0.3 part of water; the nano additive consists of quaternary ammonium salt intercalated bentonite and carboxylated nano cellulose. The invention also discloses a preparation method of the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board. The flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board has excellent strength, thermal insulation performance and flame retardant performance, and has good use performance.)

1. The flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board is characterized by comprising the following raw materials in parts by weight: 20-30 parts of polyol, 35-45 parts of isocyanate, 15-20 parts of flame retardant, 2-3 parts of silicone oil, 1-2 parts of nano additive, 1.5-2.5 parts of cyclopentane, 1-2 parts of catalyst, 0.5-1 part of cross-linking agent and 0.2-0.3 part of water;

the nano additive consists of quaternary ammonium salt intercalated bentonite and carboxylated nano cellulose.

2. The flame-retardant polyurethane foam thermal insulation material for the thermal insulation sandwich board according to claim 1, wherein in the nano additive, the mass ratio of the quaternary ammonium salt intercalated bentonite to the carboxylated nanocellulose is 1: (3-5).

3. The flame-retardant polyurethane foam thermal-insulation material for the thermal-insulation sandwich board according to claim 1 or 2, wherein the preparation method of the quaternary ammonium salt intercalated bentonite comprises the following steps: adding 200-mesh 400-mesh bentonite into water, uniformly dispersing to obtain bentonite suspension with the solid content of 5-10%, then adding quaternary ammonium salt surfactant, stirring for 2-4h at 75-85 ℃, centrifuging, washing and drying to obtain the bentonite suspension, wherein the mass ratio of the quaternary ammonium salt surfactant to the bentonite is (0.3-0.4): 1.

4. the flame-retardant polyurethane foam thermal insulation material for the thermal insulation sandwich board according to any one of claims 1 to 3, wherein the preparation method of the carboxylated nanocellulose comprises the following steps: uniformly mixing microcrystalline cellulose and an ammonium persulfate solution with the concentration of 200-300g/L, carrying out ultrasonic treatment for 150-100 min at the temperature of 70-80 ℃, and then centrifuging, washing and drying to obtain the composite material, wherein the mass ratio of the microcrystalline cellulose to the ammonium persulfate is 1 (2-3).

5. The flame-retardant polyurethane foam thermal-insulation material for the thermal-insulation sandwich board according to any one of claims 1 to 4, wherein the flame retardant comprises antimony trioxide, ammonium polyphosphate and an organic silicon flame retardant in a mass ratio of (6-10): (3-8): (1-2).

6. The flame retardant polyurethane foam insulation material for insulation sandwich panels according to claim 5, wherein the silicone flame retardant is Dow Corning FCA-117 or Xinyue KR-2710.

7. The flame-retardant polyurethane foam insulation material for the insulation sandwich panel according to any one of claims 1 to 6, wherein the polyol is prepared from polyether polyol and polyester polyol in a mass ratio of 3: (1-2); the number average molecular weight of the polyether polyol is 400-500, the hydroxyl value is 350-500mgKOH/g, the hydroxyl value of the polyester polyol is 300-400mgKOH/g, and the viscosity at 25 ℃ is 1500-3000 mPa.S.

8. The flame retardant polyurethane foamed insulation material for insulation sandwich panels according to any one of claims 1 to 7, wherein the isocyanate is polymethylene polyphenyl polyisocyanate having an isocyanate group content of 30 to 40%.

9. The flame-retardant polyurethane foam thermal-insulation material for the thermal-insulation sandwich plate according to any one of claims 1 to 8, wherein the silicone oil is a mai chart Niax L-6863 or mai chart Niax L-5440; the catalyst is an organic tin catalyst; the cross-linking agent is pentaerythritol.

10. A method for preparing the flame retardant polyurethane foam insulation material for the insulation sandwich panel according to any one of claims 1 to 9, which comprises the following steps:

s1, mixing the silicone oil and the nano additive, and then uniformly dispersing by ultrasonic to obtain a mixture A;

s2, mixing the polyol, the flame retardant, the cyclopentane, the catalyst, the mixture A and the water uniformly, adding the isocyanate and the crosslinking agent, mixing uniformly to obtain a mixture B, injecting the mixture B into a mold, foaming at 50-55 ℃, curing for 1-2h at normal temperature, and curing for 1-2h at 70-80 ℃ to obtain the flame-retardant polyurethane foam material.

Technical Field

The invention relates to the technical field of heat-insulating materials, in particular to a flame-retardant polyurethane foaming heat-insulating material for a heat-insulating sandwich plate and a preparation method thereof.

Background

The heat-insulating sandwich board is a widely used building heat-insulating material, mainly composed of a color steel plate on the outer surface and a heat-insulating material used as a core layer material. Wherein, the common thermal insulation materials for the thermal insulation sandwich board comprise phenolic aldehyde thermal insulation materials, polyurethane thermal insulation materials, polystyrene thermal insulation materials and the like. The polyurethane foam material has the advantages of light weight, high strength, good dimensional stability, low thermal conductivity coefficient and the like, and is considered to be the heat-insulating material with the best performance at present. However, the polyurethane foam material has inflammability and is low in safety factor in use. In order to improve the flame retardant property of the polyurethane foam material, a mode of adding a flame retardant into raw materials is generally adopted at present, wherein the flame retardant comprises an antimony-based flame retardant, magnesium hydroxide, ammonium polyphosphate and the like. However, the addition of the flame retardant affects the stability of the cells, destroys the structure of the cells, and adversely affects the quality of the formed cells, thereby affecting the strength and the heat insulation performance of the polyurethane foam material.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a flame-retardant polyurethane foaming thermal insulation material for a thermal insulation sandwich board and a preparation method thereof.

The invention provides a flame-retardant polyurethane foaming thermal insulation material for a thermal insulation sandwich plate, which comprises the following raw materials in parts by weight: 20-30 parts of polyol, 35-45 parts of isocyanate, 15-20 parts of flame retardant, 2-3 parts of silicone oil, 1-2 parts of nano additive, 1.5-2.5 parts of cyclopentane, 1-2 parts of catalyst, 0.5-1 part of cross-linking agent and 0.2-0.3 part of water;

the nano additive consists of quaternary ammonium salt intercalated bentonite and carboxylated nano cellulose.

Preferably, in the nano additive, the mass ratio of the quaternary ammonium salt intercalated bentonite to the carboxylated nano cellulose is 1: (3-5).

Preferably, the preparation method of the quaternary ammonium salt intercalated bentonite comprises the following steps: adding 200-mesh 400-mesh bentonite into water, uniformly dispersing to obtain bentonite suspension with the solid content of 5-10%, then adding quaternary ammonium salt surfactant, stirring for 2-4h at 75-85 ℃, centrifuging, washing and drying to obtain the bentonite suspension, wherein the mass ratio of the quaternary ammonium salt surfactant to the bentonite is (0.3-0.4): 1.

preferably, the preparation method of the carboxylated nanocellulose comprises the following steps: uniformly mixing microcrystalline cellulose and an ammonium persulfate solution with the concentration of 200-300g/L, carrying out ultrasonic treatment for 150-100 min at the temperature of 70-80 ℃, and then centrifuging, washing and drying to obtain the composite material, wherein the mass ratio of the microcrystalline cellulose to the ammonium persulfate is 1 (2-3).

Preferably, the flame retardant is prepared from antimony trioxide, ammonium polyphosphate and an organic silicon flame retardant according to the mass ratio (6-10): (3-8): (1-2).

Preferably, the silicone flame retardant is Dow Corning FCA-117 or Xinyue KR-2710.

Preferably, the polyol is prepared from polyether polyol and polyester polyol in a mass ratio of 3: (1-2); the number average molecular weight of the polyether polyol is 400-500, the hydroxyl value is 350-500mgKOH/g, the hydroxyl value of the polyester polyol is 300-400mgKOH/g, and the viscosity at 25 ℃ is 1500-3000 mPa.S.

Preferably, the isocyanate is polymethylene polyphenyl polyisocyanate with the isocyanate content of 30-40%.

Preferably, the silicone oil is Michelia Niax L-6863 or Michelia Niax L-5440; the catalyst is an organic tin catalyst; the cross-linking agent is pentaerythritol.

The preparation method of the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board is characterized by comprising the following steps of:

s1, mixing the silicone oil and the nano additive, and then uniformly dispersing by ultrasonic to obtain a mixture A;

s2, mixing the polyol, the flame retardant, the cyclopentane, the catalyst, the mixture A and the water uniformly, adding the isocyanate and the crosslinking agent, mixing uniformly to obtain a mixture B, injecting the mixture B into a mold, foaming at 50-55 ℃, curing for 1-2h at normal temperature, and curing for 1-2h at 70-80 ℃ to obtain the flame-retardant polyurethane foam material.

The invention has the following beneficial effects:

according to the invention, quaternary ammonium salt intercalated bentonite and carboxylated nano-cellulose are compounded to be used as a nano additive, wherein the quaternary ammonium salt intercalated bentonite is subjected to intercalation modification by adopting a quaternary ammonium salt surfactant, so that the bentonite is subjected to interlayer peeling, the particle size and the surface property of the bentonite are changed, the formed quaternary ammonium salt intercalated bentonite nano-material has a synergistic effect with the carboxylated nano-cellulose with a large amount of carboxyl on the surface and an organic silicon surfactant, and can be uniformly distributed on a foam interface during polyurethane foaming to achieve the effect of improving the fineness and uniformity of foam pores, so that the adverse effects of adding a large amount of flame retardant on the structure and stability of the foam pores are overcome, and the good heat preservation performance and strength are ensured on the premise that the polyurethane foaming material meets the flame retardant requirement; the carboxylated nanocellulose can be crosslinked under the action of a crosslinking agent, so that the stability and strength of foam pores are further improved; by selecting and compounding proper flame retardant, the flame retardant performance is ensured to meet the requirement on the premise of less addition, the use amount of the flame retardant is reduced, and the heat insulation performance and the strength of the polyurethane foam material are improved; by selecting and compounding the proper polyether polyol and the proper polyester polyol according to a proper proportion, the strength of the polyurethane foam material is favorably further improved, and the adverse effect of the added flame retardant on the polyurethane foam material is weakened.

In conclusion, the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board provided by the invention has excellent strength, thermal insulation performance and flame retardant performance, can reach the performance indexes of oxygen index being more than or equal to 32.0%, compressive strength being more than or equal to 150kPa, and thermal conductivity coefficient being less than or equal to 0.028W/mK, meets the requirements of core material thermal insulation materials for building wall sandwich boards, and has excellent comprehensive performance.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.

Example 1

The flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following raw materials in parts by weight: 20 parts of polyol, 35 parts of isocyanate, 15 parts of flame retardant, 2 parts of Mai chart Niax L-6863 silicone oil, 1 part of nano additive, 1.5 parts of cyclopentane, 1 part of organic tin catalyst, 0.5 part of pentaerythritol and 0.2 part of water;

the nano additive is prepared from quaternary ammonium salt intercalated bentonite and carboxylated nano cellulose according to a mass ratio of 1:3, and (3).

The preparation method of the quaternary ammonium salt intercalated bentonite comprises the following steps: adding 200-mesh bentonite into water, uniformly dispersing to obtain a bentonite suspension with the solid content of 5%, then adding cetyl trimethyl ammonium bromide, stirring for 4 hours at 75 ℃, and then centrifuging, washing and drying to obtain the bentonite suspension, wherein the mass ratio of the cetyl trimethyl ammonium bromide to the bentonite is 0.3: 1.

the preparation method of the carboxylated nano-cellulose comprises the following steps: uniformly mixing microcrystalline cellulose and an ammonium persulfate solution with the concentration of 200g/L, carrying out ultrasonic treatment for 150min at 70 ℃, and then centrifuging, washing and drying to obtain the composite material, wherein the mass ratio of the microcrystalline cellulose to the ammonium persulfate is 1:2.

The flame retardant is prepared from antimony trioxide, ammonium polyphosphate and a Xinyue KR-2710 organic silicon flame retardant in a mass ratio of 6: 3: 1.

The polyol is prepared from polyether polyol and polyester polyol according to the mass ratio of 3: 1, preparing a composition; the polyether polyol is T-403 in east of Shandong Lanxingdong, the number average molecular weight is 440, the hydroxyl value is 374-390mgKOH/g, the polyester polyol is PS-3152 in Qingdao Ruinoo chemical industry, the hydroxyl value is 300-330mgKOH/g, and the viscosity at 25 ℃ is 1700-2700 mPa.S; the isocyanate is polymethylene polyphenyl polyisocyanate with the type of Dow PAPI-135C and the content of isocyanic acid radical is 30-32.1%.

The preparation method of the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following steps:

s1, mixing the Megasan Niax L-6863 silicone oil and the nano additive, and then performing ultrasonic dispersion to obtain a mixture A;

s2, mixing the polyol, the flame retardant, the cyclopentane, the organic tin catalyst, the mixture A and the water uniformly, adding the isocyanate and the pentaerythritol, mixing uniformly to obtain a mixture B, injecting the mixture B into a mold, foaming at 50 ℃, curing for 1 hour at normal temperature, and curing for 2 hours at 70 ℃ to obtain the flame retardant.

Example 2

The flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following raw materials in parts by weight: 30 parts of polyol, 45 parts of isocyanate, 20 parts of flame retardant, 3 parts of Mai chart Niax L-6863 silicone oil, 2 parts of nano additive, 2.5 parts of cyclopentane, 2 parts of organic tin catalyst, 1 part of pentaerythritol and 0.3 part of water;

the nano additive is prepared from quaternary ammonium salt intercalated bentonite and carboxylated nano cellulose according to a mass ratio of 1: 5.

The preparation method of the quaternary ammonium salt intercalated bentonite comprises the following steps: adding 400-mesh bentonite into water, uniformly dispersing to obtain a bentonite suspension with a solid content of 10%, then adding cetyl trimethyl ammonium bromide, stirring for 2 hours at 85 ℃, and then centrifuging, washing and drying to obtain the bentonite suspension, wherein the mass ratio of the cetyl trimethyl ammonium bromide to the bentonite is 0.4: 1.

the preparation method of the carboxylated nano-cellulose comprises the following steps: uniformly mixing microcrystalline cellulose and an ammonium persulfate solution with the concentration of 300g/L, carrying out ultrasonic treatment for 100min at the temperature of 80 ℃, and then centrifuging, washing and drying to obtain the composite material, wherein the mass ratio of the microcrystalline cellulose to the ammonium persulfate is 1: 3.

The flame retardant is prepared from antimony trioxide, ammonium polyphosphate and a Xinyue KR-2710 organic silicon flame retardant in a mass ratio of 10: 8: 2.

The polyol is prepared from polyether polyol and polyester polyol according to the mass ratio of 3: 2, preparing a composition; the polyether polyol is T-403 in east of Shandong Lanxingdong, the number average molecular weight is 440, the hydroxyl value is 374-390mgKOH/g, the polyester polyol is PS-3152 in Qingdao Ruinoo chemical industry, the hydroxyl value is 300-330mgKOH/g, and the viscosity at 25 ℃ is 1700-2700 mPa.S; the isocyanate is polymethylene polyphenyl polyisocyanate with the type of Dow PAPI-135C and the content of isocyanic acid radical is 30-32.1%.

The preparation method of the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following steps:

s1, mixing the Megasan Niax L-6863 silicone oil and the nano additive, and then performing ultrasonic dispersion to obtain a mixture A;

s2, mixing the polyol, the flame retardant, the cyclopentane, the organic tin catalyst, the mixture A and the water uniformly, adding the isocyanate and the pentaerythritol, mixing uniformly to obtain a mixture B, injecting the mixture B into a mold, foaming at 55 ℃, curing for 2 hours at normal temperature, and curing for 1 hour at 80 ℃ to obtain the flame retardant.

Example 3

The flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following raw materials in parts by weight: 25 parts of polyol, 40 parts of isocyanate, 18 parts of flame retardant, 2.5 parts of Mai chart Niax L-6863 silicone oil, 1.5 parts of nano additive, 2 parts of cyclopentane, 1.5 parts of organic tin catalyst, 0.8 part of pentaerythritol and 0.25 part of water;

the nano additive is prepared from quaternary ammonium salt intercalated bentonite and carboxylated nano cellulose according to a mass ratio of 1: 4.

The preparation method of the quaternary ammonium salt intercalated bentonite comprises the following steps: adding 300-mesh bentonite into water, uniformly dispersing to obtain a bentonite suspension with a solid content of 8%, adding cetyl trimethyl ammonium bromide, stirring at 80 ℃ for 3 hours, centrifuging, washing and drying to obtain the bentonite suspension, wherein the mass ratio of the cetyl trimethyl ammonium bromide to the bentonite is 0.35: 1.

the preparation method of the carboxylated nano-cellulose comprises the following steps: uniformly mixing microcrystalline cellulose and an ammonium persulfate solution with the concentration of 250g/L, carrying out ultrasonic treatment for 120min at 75 ℃, and then centrifuging, washing and drying to obtain the composite material, wherein the mass ratio of the microcrystalline cellulose to the ammonium persulfate is 1: 2.5.

The flame retardant is prepared from antimony trioxide, ammonium polyphosphate and a Xinyue KR-2710 organic silicon flame retardant in a mass ratio of 8: 5: 1.5.

The polyol is prepared from polyether polyol and polyester polyol according to the mass ratio of 3: 1.5; the polyether polyol is T-403 in east of Shandong Lanxingdong, the number average molecular weight is 440, the hydroxyl value is 374-390mgKOH/g, the polyester polyol is PS-3152 in Qingdao Ruinoo chemical industry, the hydroxyl value is 300-330mgKOH/g, and the viscosity at 25 ℃ is 1700-2700 mPa.S; the isocyanate is polymethylene polyphenyl polyisocyanate with the type of Dow PAPI-135C and the content of isocyanic acid radical is 30-32.1%.

The preparation method of the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following steps:

s1, mixing the Megasan Niax L-6863 silicone oil and the nano additive, and then performing ultrasonic dispersion to obtain a mixture A;

s2, mixing the polyol, the flame retardant, the cyclopentane, the organic tin catalyst, the mixture A and the water uniformly, adding the isocyanate and the pentaerythritol, mixing uniformly to obtain a mixture B, injecting the mixture B into a mold, foaming at 52 ℃, curing for 1.5h at normal temperature, and curing for 1.5h at 75 ℃ to obtain the flame retardant.

Comparative example 1

The flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following raw materials in parts by weight: 25 parts of polyol, 40 parts of isocyanate, 18 parts of flame retardant, 2.5 parts of Mai chart Niax L-6863 silicone oil, 2 parts of cyclopentane, 1.5 parts of organic tin catalyst, 0.8 part of pentaerythritol and 0.25 part of water;

the flame retardant is prepared from antimony trioxide, ammonium polyphosphate and a Xinyue KR-2710 organic silicon flame retardant in a mass ratio of 8: 5: 1.5.

The polyol is prepared from polyether polyol and polyester polyol according to the mass ratio of 3: 1.5; the polyether polyol is T-403 in east of Shandong Lanxingdong, the number average molecular weight is 440, the hydroxyl value is 374-390mgKOH/g, the polyester polyol is PS-3152 in Qingdao Ruinoo chemical industry, the hydroxyl value is 300-330mgKOH/g, and the viscosity at 25 ℃ is 1700-2700 mPa.S; the isocyanate is polymethylene polyphenyl polyisocyanate with the type of Dow PAPI-135C and the content of isocyanic acid radical is 30-32.1%.

The preparation method of the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following steps:

firstly, uniformly mixing polyol, a flame retardant, cyclopentane, an organic tin catalyst, Mai chart Niax L-6863 silicone oil and water, then adding isocyanate and pentaerythritol, uniformly mixing to obtain a mixture, injecting the mixture into a mold, foaming at 52 ℃, then curing for 1.5h at normal temperature, and then curing for 1.5h at 75 ℃ to obtain the flame retardant.

Comparative example 2

The flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following raw materials in parts by weight: 25 parts of polyol, 40 parts of isocyanate, 18 parts of flame retardant, 2.5 parts of Mai chart Niax L-6863 silicone oil, 1.5 parts of quaternary ammonium salt intercalated bentonite, 2 parts of cyclopentane, 1.5 parts of organic tin catalyst, 0.8 part of pentaerythritol and 0.25 part of water;

the preparation method of the quaternary ammonium salt intercalated bentonite comprises the following steps: adding 300-mesh bentonite into water, uniformly dispersing to obtain a bentonite suspension with a solid content of 8%, adding cetyl trimethyl ammonium bromide, stirring at 80 ℃ for 3 hours, centrifuging, washing and drying to obtain the bentonite suspension, wherein the mass ratio of the cetyl trimethyl ammonium bromide to the bentonite is 0.35: 1.

the flame retardant is prepared from antimony trioxide, ammonium polyphosphate and a Xinyue KR-2710 organic silicon flame retardant in a mass ratio of 8: 5: 1.5.

The polyol is prepared from polyether polyol and polyester polyol according to the mass ratio of 3: 1.5; the polyether polyol is T-403 in east of Shandong Lanxingdong, the number average molecular weight is 440, the hydroxyl value is 374-390mgKOH/g, the polyester polyol is PS-3152 in Qingdao Ruinoo chemical industry, the hydroxyl value is 300-330mgKOH/g, and the viscosity at 25 ℃ is 1700-2700 mPa.S; the isocyanate is polymethylene polyphenyl polyisocyanate with the type of Dow PAPI-135C and the content of isocyanic acid radical is 30-32.1%.

The preparation method of the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following steps:

s1, mixing the Meyer Niax L-6863 silicone oil and quaternary ammonium salt intercalated bentonite, and then performing ultrasonic dispersion to obtain a mixture A;

s2, mixing the polyol, the flame retardant, the cyclopentane, the organic tin catalyst, the mixture A and the water uniformly, adding the isocyanate and the pentaerythritol, mixing uniformly to obtain a mixture B, injecting the mixture B into a mold, foaming at 52 ℃, curing for 1.5h at normal temperature, and curing for 1.5h at 75 ℃ to obtain the flame retardant.

Comparative example 3

The flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following raw materials in parts by weight: 25 parts of polyol, 40 parts of isocyanate, 18 parts of flame retardant, 2.5 parts of Mai chart Niax L-6863 silicone oil, 1.5 parts of carboxylated nano-cellulose, 2 parts of cyclopentane, 1.5 parts of organic tin catalyst, 0.8 part of pentaerythritol and 0.25 part of water;

the preparation method of the carboxylated nano-cellulose comprises the following steps: uniformly mixing microcrystalline cellulose and an ammonium persulfate solution with the concentration of 250g/L, carrying out ultrasonic treatment for 120min at 75 ℃, and then centrifuging, washing and drying to obtain the composite material, wherein the mass ratio of the microcrystalline cellulose to the ammonium persulfate is 1: 2.5.

The flame retardant is prepared from antimony trioxide, ammonium polyphosphate and a Xinyue KR-2710 organic silicon flame retardant in a mass ratio of 8: 5: 1.5.

The polyol is prepared from polyether polyol and polyester polyol according to the mass ratio of 3: 1.5; the polyether polyol is T-403 in east of Shandong Lanxingdong, the number average molecular weight is 440, the hydroxyl value is 374-390mgKOH/g, the polyester polyol is PS-3152 in Qingdao Ruinoo chemical industry, the hydroxyl value is 300-330mgKOH/g, and the viscosity at 25 ℃ is 1700-2700 mPa.S; the isocyanate is polymethylene polyphenyl polyisocyanate with the type of Dow PAPI-135C and the content of isocyanic acid radical is 30-32.1%.

The preparation method of the flame-retardant polyurethane foaming thermal insulation material for the thermal insulation sandwich board comprises the following steps:

s1, mixing the Megasan Niax L-6863 silicone oil and the carboxylated nano-cellulose, and then performing ultrasonic dispersion to obtain a mixture A;

s2, mixing the polyol, the flame retardant, the cyclopentane, the organic tin catalyst, the mixture A and the water uniformly, adding the isocyanate and the pentaerythritol, mixing uniformly to obtain a mixture B, injecting the mixture B into a mold, foaming at 52 ℃, curing for 1.5h at normal temperature, and curing for 1.5h at 75 ℃ to obtain the flame retardant.

Test examples

The performance tests of the flame-retardant polyurethane foam heat-insulating material for the heat-insulating sandwich plates prepared in the examples 1-3 and the comparative examples 1-3 are carried out, wherein the oxygen index refers to GB/T2046.2, the compressive strength refers to GB/T8813, and the thermal conductivity refers to GB/T3399. The test results are shown in table 1:

TABLE 1 insulation Performance test results

	Oxygen index (%)	Compressive Strength (kPa)	Coefficient of thermal conductivity (W/mK)
				Example 1	32.1	168	0.0269
Example 2	32.2	161	0.0268
				Example 3	32.5	170	0.0265
Comparative example 1	32.3	127	0.0293
				Comparative example 2	32.4	139	0.0279
Comparative example 3	32.1	144	0.0286

The polyurethane foam material can reach the performance indexes of oxygen index more than or equal to 32.0%, compressive strength more than or equal to 150kPa and thermal conductivity coefficient less than or equal to 0.028W/mK, meets the requirements of core material heat-insulating materials for building wall sandwich boards, and has excellent comprehensive performance.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.