CN115716903A - Expandable graphite/TiO 2 Preparation method of polyurethane flame-retardant material - Google Patents

Abstract

The invention relates to expandable graphite/TiO ₂ The preparation method of the polyurethane flame-retardant material is characterized by comprising the following steps: (1) Adding expansible graphite into ammonia water, performing ultrasonic treatment, continuously adding titanium source, mixing, and 160-180% ^o C, reacting for 120-180min, centrifuging, washing and drying; (2) Expandable graphite/TiO obtained in step (1) ₂ Adding the composite material and the surface modifier into deionized water, stirring for 1-3h at 78-82 ℃, centrifuging, washing and drying; (3) Surface-modified expandable graphite/TiO obtained in the step (2) ₂ Mixing the composite material, polyalcohol and chain extender, distilling under reduced pressure at 80-100 deg.C under 2.67-3.33KPa for 25-35min, and cooling to below 60 deg.C; adding a catalyst and a foaming agent, and uniformly stirring to form a mixture B; heating to 40-50 deg.C, mixing isocyanate with mixture B, and curing for 6-8 days to obtain expandable graphite/TiO ₂ A polyurethane flame-retardant material. The invention has the advantages that: expandable graphite/TiO ₂ The polyurethane flame-retardant material has the limit oxygen absorption index of 24.2-34.8, the flame-retardant grade of V-0, the compression strength of 4.7-6.5MPa and the bending strength of 4.4-4.9MPa.

Description

A kind of preparation method of expandable graphite/TiO2/polyurethane flame retardant material

technical field

The invention belongs to the field of preparation of polyurethane flame retardant materials, and relates to a preparation method of expandable graphite/TiO ₂ /polyurethane flame retardant materials.

Background technique

As a kind of polyurethane material, polyurethane foam is widely used in the field of construction as thermal insulation material because of its excellent thermal insulation performance. However, due to the low limiting oxygen index of polyurethane foam, it is easy to burn under the action of high temperature, and produces toxic gas during the combustion process, which causes great harm to people's life and health. In order to improve the flame retardancy of polyurethane foam as insulation material, adding flame retardants to polyurethane foam has become an effective method to improve the flame retardancy of polyurethane foam.

Traditional flame retardants are organic compounds of elements such as phosphorus, bromine, and chlorine. However, with the continuous improvement of comprehensive environmental protection indicators, traditional flame retardants have been unable to meet the requirements of high-temperature flame retardancy. As a new type of intumescent flame retardant, expandable graphite has attracted much attention because of its halogen-free, non-toxic and stable properties. Expandable graphite is added to the polymer material matrix as a flame retardant material, and does not affect the physical properties of the polymer material itself. However, when expandable graphite is used alone as a flame retardant, due to the insufficient cohesive force of the expanded carbon layer, the formed carbon layer is not strong, and the phenomenon of "fly ash" will be generated under the action of heat and air flow, and the flame retardant effect will become poor. . Therefore, it is necessary to improve the flame retardant effect of polymer materials through the flame retardant effect of composite flame retardants.

Contents of the invention

The purpose of the present invention is to solve the problem of poor flame retardant effect when expandable graphite is used as a flame retardant, and to provide a preparation method of expandable graphite/TiO ₂ /polyurethane flame retardant material.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A preparation method of expandable graphite/TiO ₂ /polyurethane flame retardant material, characterized in that it comprises the following steps:

(1) Preparation of expandable graphite/TiO ₂ composites:

Add expandable graphite to ammonia water with a concentration of 0.5-1mol/L to control the volume (mL) mass (g) ratio of ammonia water: expandable graphite to 25:1. After ultrasonic dispersion is uniform, add titanium source to the system to control expandability The mass ratio of graphite:titanium source is 1:2~5, and then the mixed solution is transferred to the reactor, reacted at 160-180 ^o C for 120-180min, centrifuged, washed and dried (78-83°C for 10- 14h), to obtain expandable graphite/TiO ₂ composites;

(2) Surface modification of expandable graphite/ _TiO2 composites:

The expandable graphite/ _TiO2 composite material and surface modifier were added to deionized water, and the mass ratio of surface modifier: expandable graphite/ _TiO2 composite material: deionized water was 1-2:50:1000, at 78- Stir continuously at 82°C for 1-3h, centrifuge, wash and dry (dry at 78-83°C for 10-14h) to obtain a surface-modified expandable graphite/TiO ₂ composite material;

(3) Preparation of expandable graphite/TiO ₂ /polyurethane flame retardant material:

a. Take polyol, surface-modified expandable graphite/ _TiO2 composite material, and chain extender and stir evenly to form mixture A, and control the mass ratio of polyol: surface-modified expandable graphite/ _TiO2 composite material: chain extender The ratio is 1:1:87-96. After the mixture A is distilled under reduced pressure at 2.67-3.33KPa and 80-100°C for 25-35min, the temperature of the material is reduced to below 60°C;

b. Continue to add catalyst and blowing agent to the material, control the chain extender: the mass ratio of catalyst: blowing agent is 1:1:1, stir evenly to form mixture B; after mixture B is heated to 40-50°C, put Mix isocyanate with mixture B, control the molar ratio of isocyanate and polyol to 1:1, mechanically stir for 1-2min and then cure for 6-8 days to obtain expandable graphite/TiO ₂ /polyurethane flame retardant material; wherein step a, step b The medium chain extender is 1,4-butanediol, ethylene glycol, diethylene glycol, propylene glycol, trimethylolpropane, diethanolamine, triethanolamine, triisopropanol or dimethylthiotoluene Amine; Catalyst is dimethylethanolamine or triethylenediamine in the step b; Blowing agent is water in the step b.

Further, the expandable graphite particle size in the step (1) is 100-300 mesh.

Further, the titanium source in the step (1) is butyl titanate, titanium sulfate, isopropanol titanate or titanium tetrachloride.

Further, the surface modifier in the step (2) is one or more of stearic acid, lignosulfonate, cetyl alcohol, and silane coupling agent.

Further, the silane coupling agent is KH-550, KH-602, KH-560 or KH-570.

Further, the polyol in the step (3) is polyether polyol, polyester polyol, polytetrahydrofuran ether glycol, polycaprolactone polyol or polycarbonate polyol.

Further, the isocyanate in the step (3) is toluene-2,4-diisocyanate or diphenylmethane diisocyanate.

Further, in the expandable graphite/TiO ₂ /polyurethane flame retardant material, the mass ratio of expandable graphite to theoretically produced titanium dioxide is 1-3:1, wherein the expandable graphite/TiO ₂ content is 1-3:1 of the theoretically produced polyurethane mass. 10%, the expandable graphite/TiO ₂ composite material is evenly distributed in the polyurethane foam, and its compatibility with polyurethane is good; the limiting oxygen absorption index is 24.2-34.8, the flame retardant grade is V-0, and the compressive strength is 4.7- 6.5MPa, the bending strength is 4.4-4.9MPa.

Beneficial effects of the present invention:

The present invention uses expandable graphite as a carrier, adopts hydrothermal synthesis technology to prepare expandable graphite/TiO ₂ composite material and modifies its surface, and then adopts a one-step method to prepare expandable graphite/TiO ₂ /polyurethane flame-retardant material; TiO ₂ and expandable As a flame retardant material, expanded graphite composite can solve the problem of weak expanded graphite carbon layer under high temperature conditions and improve the flame retardant effect of polymer materials; in case of fire, graphite carbon atoms in expandable graphite will react with acid radical ions A series of chemical reactions produce water vapor, carbon dioxide, sulfur dioxide and other substances to force the expandable graphite to expand to produce an expanded carbon layer; when the expanded carbon layer is coated on the surface of the material, it can play a flame-retardant role.

Description of drawings

Figure 1 is the limit oxygen index curve of expandable graphite/TiO ₂ /polyurethane flame retardant material, wherein the mass ratio of expandable graphite to TiO ₂ is 1:1;

Figure 2 is the compressive strength curve of expandable graphite/TiO ₂ /polyurethane flame retardant material, where the mass ratio of expandable graphite to TiO ₂ is 1:1.

Detailed ways

A preparation method of expandable graphite/TiO ₂ /polyurethane flame retardant material, the specific implementation steps are as follows:

Example 1

(1) Preparation of expandable graphite/TiO ₂ composites (expandable graphite is used as a carrier, and expandable graphite/TiO ₂ composites are prepared by hydrothermal synthesis):

Take 200 mesh expandable graphite 2g, add it to 50mL 0.5mol/L ammonia solution, ultrasonic for 20min, then add 8.55g of butyl titanate into the system, ultrasonically disperse evenly, transfer to a 100mL hydrothermal reaction kettle, Reaction at ℃ for 180min, centrifugation, washing, and drying at 80℃ for 12h to obtain an expandable graphite/TiO composite material with a mass ratio of 1: ₁ between expandable graphite and theoretically produced TiO ₂ ;

(2) Surface modification of expandable graphite/ _TiO2 composites:

Take 5 g of expandable graphite and theoretically produced TiO ₂ with a mass ratio of 1:1 for expandable graphite/TiO ₂ composites and 0.1 g of lignosulfonate into 100 mL of deionized water, keep stirring at 80°C for 2 h, centrifuge, Washing and drying at 80°C for 12h to obtain a surface-modified expandable graphite/TiO ₂ composite material;

(3) Preparation of expandable graphite/TiO ₂ /polyurethane flame retardant material:

Take 46g of polytetrahydrofuran ether glycol 1000, 2.5g of lignosulfonate surface-modified expandable graphite/ _{TiO2composite} material, 0.5g of ethylene glycol and stir evenly to form mixture A, which is distilled under reduced pressure at 2.67KPa and 80°C for 30min Finally, lower the temperature of the material to 58°C, add 0.5g of triethylenediamine and 0.5g of water to the mixture A, stir well to form a mixture B; after heating the mixture B to 45°C, take 8.011g of toluene-2,4- The diisocyanate was mixed with the mixture B, mechanically stirred for 1 min and cured for 7 days to obtain an expandable graphite/TiO ₂ /polyurethane flame retardant material.

The expandable graphite/ _TiO2 /polyurethane flame-retardant material prepared in Example 1 of the present invention has an expandable graphite/ _TiO2 composite material content of 4.70%, a limiting oxygen absorption index of 31.2, a flame-retardant grade of V-0, and a compressive strength of It is 6.0MPa, and the bending strength is 4.7MPa.

Example 2

(1) Preparation of expandable graphite/TiO ₂ composites (expandable graphite is used as a carrier, and expandable graphite/TiO ₂ composites are prepared by hydrothermal synthesis):

Take 200 mesh expandable graphite 2g, add it to 50mL of 0.5mol/L ammonia solution, ultrasonicate for 20min, then add 4.73g of butyl titanate to the system, ultrasonically disperse it evenly, transfer it to a 100mL hydrothermal reaction kettle, and heat it at 180 Reaction at ℃ for 180min, centrifugation, washing, and drying at 80℃ for 12h to obtain expandable graphite/TiO ₂ composite material with a mass ratio of expandable graphite and theoretically produced TiO ₂ of 2:1;

(2) Surface modification of expandable graphite/ _TiO2 composites:

Take 5g of expandable graphite and theoretically produced TiO ₂ with a mass ratio of 2:1 for expandable graphite/TiO ₂ composite material and 0.1g of silane coupling agent KH570 into 100mL deionized water, keep stirring at 82°C for 2.5h, and centrifuge , washing, and drying at 83°C for 11 hours to obtain a surface-modified expandable graphite/TiO ₂ composite material;

(3) Preparation of expandable graphite/TiO ₂ /polyurethane flame retardant material:

Take 46g of polytetrahydrofuran ether glycol 1000, 1.5g of surface-modified expandable graphite/TiO _Composite material, 0.5g of propylene glycol and stir evenly to form mixture A. After distillation under reduced pressure at 3.33kPa and 90°C for 35min, the temperature of the material is reduced to 56°C, add 0.5g dimethylethanolamine and 0.5g water to mixture A, stir well to form mixture B; after heating mixture B to 48°C, take 11.76g diphenylmethane diisocyanate and mix with mixture B, mechanically stir After curing for 8 days after 1.5 min, an expandable graphite/TiO ₂ /polyurethane flame retardant material was obtained.

The expandable graphite/ _TiO2 /polyurethane flame-retardant material prepared in Example 2 of the present invention has an expandable graphite/ _TiO2 composite material content of 2.59%, a limiting oxygen absorption index of 29.4, a flame-retardant grade of V-0, and a compressive strength of It is 5.7MPa, and the bending strength is 4.6MPa.

Example 3

(1) Preparation of expandable graphite/TiO ₂ composites (expandable graphite is used as a carrier, and expandable graphite/TiO ₂ composites are prepared by hydrothermal synthesis):

Take 2g of 200-mesh expandable graphite, add it to 50mL of 0.5mol/L ammonia solution, ultrasonicate for 20min, then add 7.09g of butyl titanate to the system, ultrasonically disperse it evenly, transfer it to a 100mL hydrothermal reaction kettle, and heat it at 180 Reaction at ℃ for 180min, centrifugation, washing, and drying at 78℃ for 12.5h to obtain an expandable graphite/TiO ₂ composite material with a mass ratio of expandable graphite and theoretically produced TiO ₂ of 3:2;

(2) Surface modification of expandable graphite/ _TiO2 composites:

Take 5 g of expandable graphite and theoretically produced TiO ₂ with a mass ratio of 3:2 for expandable graphite/TiO ₂ composites and 0.1 g of stearic acid into 100 mL of deionized water, continue stirring at 78 ° C for 3 h, centrifuge, wash, Dry at 78°C for 13h to obtain a surface-modified expandable graphite/TiO ₂ composite material;

(3) Preparation of expandable graphite/TiO ₂ /polyurethane flame retardant material:

Get 48g of polytetrahydrofuran ether glycol 1000, 1.5g of surface-modified expandable graphite/TiO _Composite material, 0.5g of triethanolamine and stir evenly to form mixture A. After 40min of vacuum distillation at 3.33MPa and 100°C, the temperature of the material is lowered to To 52°C, add 0.5g triethylenediamine and 0.5g water to mixture A, stir well to form mixture B; after heating mixture B to 43°C, take 8.359g toluene-2,4-diisocyanate and mix with mixture B , after being mechanically stirred for 2 minutes and cured for 7.5 days, an expandable graphite/TiO ₂ /polyurethane flame-retardant material was obtained.

The expandable graphite/ _TiO2 /polyurethane flame-retardant material prepared in Example 3 of the present invention has an expandable graphite/ _TiO2 composite material content of 0.90%, a limiting oxygen absorption index of 24.8, a flame-retardant grade of V-0, and a compressive strength of It is 5.4MPa, and the bending strength is 4.6MPa.

Finally, it is noted that the contents mentioned in the present invention are all mass percentages, unless otherwise specified. The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still understand the foregoing embodiments. Modification of the technical solution, or equivalent replacement of some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A preparation method of expandable graphite/TiO ₂ /polyurethane flame-retardant material, is characterized in that comprising the steps: (1) Preparation of expandable graphite/TiO ₂ composites: Add expandable graphite to ammonia water with a concentration of 0.5-1mol/L to control the volume (mL) mass (g) ratio of ammonia water:expandable graphite to 25:1. After the ultrasonic dispersion is uniform, the titanium source added to the system can be controlled. The mass ratio of expanded graphite: titanium source is 1:2~5, then transfer the mixed solution to the reactor, react at 160-180 ^o C for 120-180min, centrifuge, wash and dry to obtain expandable graphite/TiO ₂ composite materials; (2) Surface modification of expandable graphite/ _TiO2 composites: The expandable graphite/ _TiO2 composite material and surface modifier were added to deionized water, and the mass ratio of surface modifier: expandable graphite/ _TiO2 composite material: deionized water was 1-2:50:1000, at 78- Stir continuously at 82°C for 1-3h, centrifuge, wash, and dry to obtain a surface-modified expandable graphite/TiO ₂ composite material; (3) Preparation of expandable graphite/TiO ₂ /polyurethane flame retardant material: a. Take polyol, surface-modified expandable graphite/ _TiO2 composite material, and chain extender and stir evenly to form mixture A, and control the mass ratio of polyol: surface-modified expandable graphite/ _TiO2 composite material: chain extender The ratio is 1:1:87-96. After the mixture A is distilled under reduced pressure at 2.67-3.33KPa and 80-100°C for 25-35min, the temperature of the material is reduced to below 60°C; b. Continue to add catalyst and foaming agent to the material, control the chain extender: catalyst: foaming agent mass ratio is 1:1:1, stir evenly to form mixture B; after heating mixture B to 40-50°C, Mix isocyanate with mixture B, control the molar ratio of isocyanate to polyol to be 1:1, mechanically stir for 1-2min and then solidify for 6-8 days to obtain expandable graphite/TiO ₂ /polyurethane flame retardant material; wherein step a, step The chain extender in b is 1,4-butanediol, ethylene glycol, diethylene glycol, propylene glycol, trimethylolpropane, diethanolamine, triethanolamine, triisopropanol or dimethylthiotoluene Diamine; in the step b, the catalyst is dimethylethanolamine or triethylenediamine; in the step b, the blowing agent is water. 2. The method for preparing an expandable graphite/TiO ₂ /polyurethane flame retardant material according to claim 1, characterized in that: in the step (1), the particle size of the expandable graphite is 100-300 mesh. 3. A method for preparing an expandable graphite/TiO ₂ /polyurethane flame retardant material according to claim 1, characterized in that: the titanium source in the step (1) is butyl titanate, titanium sulfate, iso-titanate propanol or titanium tetrachloride. 4. A method for preparing an expandable graphite/TiO ₂ /polyurethane flame retardant material according to claim 1, characterized in that: in the step (2), the surface modifier is stearic acid, lignosulfonate, One or more of cetyl alcohol and silane coupling agent. 5. A method for preparing expandable graphite/TiO ₂ /polyurethane flame retardant material according to claim 4, characterized in that: the silane coupling agent is KH-550, KH-602, KH-560, KH- 570. 6 . The method for preparing an expandable graphite/TiO ₂ /polyurethane flame-retardant material according to claim 1, characterized in that: the drying condition in the step (2) is: 78-83° C. for 10-14 hours. 7. A method for preparing an expandable graphite/TiO ₂ /polyurethane flame retardant material according to claim 1, wherein the polyol in the step (3) is polyether polyol, polyester polyol, poly Tetrahydrofuran ether diol, polycaprolactone polyol or polycarbonate polyol. 8. A method for preparing expandable graphite/TiO ₂ /polyurethane flame retardant material according to claim 1, characterized in that: the isocyanate in the step (3) is toluene-2,4-diisocyanate or diphenyl methane diisocyanate. 9. A method for preparing an expandable graphite/TiO ₂ /polyurethane flame retardant material according to any one of claims 1-8, characterized in that: in the expandable graphite/TiO ₂ /polyurethane flame retardant material, The expanded graphite/TiO ₂ composite material is evenly distributed in polyurethane foam, and its compatibility with polyurethane is good; the limiting oxygen absorption index is 24.2-34.8, the flame retardant grade is V-0, the compressive strength is 4.7-6.5MPa, and the flexural strength is 4.7-6.5MPa. The strength is 4.4-4.9MPa.

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