CN115490922B - Polyurethane-coated expandable graphite flame retardant and preparation method thereof - Google Patents
Polyurethane-coated expandable graphite flame retardant and preparation method thereof Download PDFInfo
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- CN115490922B CN115490922B CN202211436269.5A CN202211436269A CN115490922B CN 115490922 B CN115490922 B CN 115490922B CN 202211436269 A CN202211436269 A CN 202211436269A CN 115490922 B CN115490922 B CN 115490922B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K9/00—Use of pretreated ingredients
- C08K9/10—Encapsulated ingredients
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/48—Polyethers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K7/00—Use of ingredients characterised by shape
- C08K7/22—Expanded, porous or hollow particles
- C08K7/24—Expanded, porous or hollow particles inorganic
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2101/00—Manufacture of cellular products
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2110/00—Foam properties
- C08G2110/0025—Foam properties rigid
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Abstract
The invention discloses a polyurethane-coated expandable graphite flame retardant and a preparation method thereof, belonging to the field of organic modified expandable graphite. The method comprises the steps of uniformly stirring polyol and a catalyst, adding expandable graphite, uniformly stirring, adding polyisocyanate, fully stirring, and reacting the polyisocyanate and the polyol on the surface of graphite to generate polyurethane under the action of the catalyst, thereby obtaining the polyurethane-coated expandable graphite. The preparation process of the invention is simple and convenient without using solvent, the polyurethane coated on the surface accelerates the coking speed, the flame retardant property of the material is improved, the compatibility problem of the expandable graphite and the high polymer material is improved by the coating of the polyurethane, and compared with the expandable graphite with the same addition amount, the flame retardant property and the mechanical property of the polyurethane foam prepared by coating the expandable graphite with the polyurethane are obviously improved. The polyurethane-coated expandable graphite is a non-toxic environment-friendly flame retardant with high efficiency, flame retardance and good compatibility.
Description
Technical Field
The invention relates to the field of organic modified expandable graphite, in particular to a polyurethane-coated expandable graphite flame retardant and a preparation method thereof.
Background
The expandable graphite is a novel low-smoke halogen-free flame retardant, which begins to expand at about 200 ℃ through the decomposition of an interlayer compound, reaches the maximum value at about 900 ℃, has the expansion rate of 280 times, and is changed into a worm shape from a flake shape to form a thicker porous carbon layer, thereby playing the role of insulating heat and oxygen and extinguishing flame. However, the expandable graphite alone produces a popcorn effect when being burned, i.e., the loose worm-like carbon layer is easy to fall off under the disturbance of flame impact, and the flame retardant and smoke suppression effects of the expandable graphite are seriously influenced. In addition, the mechanical properties of the polymer material are seriously deteriorated due to weak interfacial force between the expandable graphite as an inorganic particle flame retardant and the polymer matrix material, serious agglomeration phenomenon and interface compatibility problem with the polymer material. The modification of the expandable graphite can improve the popcorn effect, improve the interface compatibility between the expandable graphite and a high polymer material matrix, enhance the flame retardant efficiency of the expandable graphite and weaken the deterioration of the expandable graphite to the mechanical property of the matrix material. At present, the modification of expandable graphite is mainly realized by three ways of surface treatment, surface grafting, coating and the like. Among the methods for modifying expandable graphite, the surface treatment method has simple process and low cost, but the acting force between the expandable graphite and the surface treatment agent is weaker and the expandable graphite is easy to desorb; the surface grafting method is to graft organic functional groups containing polarity on the surface of the expandable graphite through chemical reaction, so that the compatibility of the expandable graphite and a substrate is improved, but generally used grafting reagents are expensive and the process is complex; the coating method is to completely coat the expandable graphite through polymerization reaction to form the modified expandable graphite particles with the core-shell structure.
In the chinese patent CN103554428B, expandable graphite particles are used as a capsule core, polyurethane formed by crosslinking cyclodextrin or cyclodextrin/modified resin and toluene diisocyanate is used as a capsule shell, and the polyurethane microcapsule modified expandable graphite with core-shell synergistic flame retardant is prepared by heating and catalytic reaction in dimethylsulfoxide and dioxane solvent, and when the expandable graphite is applied to polyurethane rigid foam plastics, the flame retardant property and the mechanical property are both improved. Ye and the like [ Ye L, etc. Polymer, degrad, stab, 2009, 94, 971-979] adopt an emulsion polymerization method to carry out polymethyl methacrylate coating modification on expandable graphite and are applied to hard polyurethane foam, so that the polyurethane foam has a good flame retardant effect and improved mechanical properties. Although the above patent and literature of the invention have improved flame retardant properties to some extent, the improvement of mechanical properties is small, or the manufacturing method is complicated and the cost is high although the mechanical properties are improved.
Disclosure of Invention
A preparation method of a polyurethane-coated expandable graphite flame retardant comprises the following steps: firstly, adding polyol and a catalyst into a container, wherein the mass ratio of the catalyst to the polyol is 0.01 to 5, stirring uniformly at room temperature, then adding expandable graphite, wherein the mass ratio of the expandable graphite to the total amount of polyurethane is 5 to 50, stirring uniformly, then adding polyisocyanate into the container at room temperature, wherein the mass ratio of the polyisocyanate to the polyol is 1 to 5.
The expandable graphite is 40 to 200 meshes of dry expandable graphite which is obtained by treating natural crystalline flake graphite with a strong acid and a strong oxidant.
The polyol is any one or a mixture of more of polyether polyol, polyester polyol, pentaerythritol, ethylene glycol, diethylene glycol, glycerol, xylitol, sorbitol, propylene glycol, butanediol and hexanediol.
Further, the hydroxyl value of the polyether polyol is 10 to 800mgKOH/g, and the hydroxyl value of the polyester polyol is 10 to 800mgKOH/g.
The polyisocyanate is polymeric diphenylmethane diisocyanate with the mass content of-NCO being 25-40%.
Further, the polyisocyanate is any one or a mixture of more of CW-20, PM-130, PM-200, PM-2010, PM-2025 and PM-400 in Wanhua chemistry.
The catalyst is any one or a mixture of more of tris (dimethylaminopropyl) hexahydrotriazine (PC-41), 2,4, 6-tris (dimethylaminomethyl) phenol (TMR-30), 2-hydroxy-N, N, N-trimethyl-1-propylamine formate (TMR-2), triethylene diamine (A33), pentamethyl diethylenetriamine (PC-5), dimethylcyclohexylamine (PC-8), dibutyltin dilaurate, stannous octoate, potassium acetate and potassium isooctanoate.
The sieving condition according to the invention is 20 to 200 meshes.
The drying condition is that the temperature is 30 to 120 ℃, and the time is 1 to 24h.
The polyurethane-coated expandable graphite flame retardant prepared by the method is of a core-shell structure, takes expandable graphite as a core, and takes polyurethane generated by reaction of polyisocyanate and polyol as a shell.
The polyurethane-coated expandable graphite flame retardant prepared by the method has an average particle size of 20-200 meshes, preferably 40-120 meshes.
The invention has the beneficial effects that:
1. according to the invention, polyurethane is coated on the surface of the expandable graphite, the polyurethane and the expandable graphite always keep stable structure and uniform distribution in the using process, and the material forms a compact carbonized layer in the combustion process, which is more compact and stable compared with a conventional carbon layer, has better heat insulation, oxygen isolation and char formation capabilities, and reduces the combustion and melting dripping of the tissue material;
2. according to the invention, polyurethane and the expandable graphite flame retardant are combined, so that the polyurethane is coated on the surface of the expandable graphite, the coking speed is accelerated, and the flame retardant capability of the expandable graphite is obviously improved;
3. the polyurethane is coated on the surface of the expandable graphite, so that the compatibility of the expandable graphite with polymer material matrixes such as polyurethane and the like is remarkably improved, and the dispersion stability of the expandable graphite in the polymer material matrixes is greatly improved;
4. according to the invention, organic polyurethane molecules are coated on the surface of the expandable graphite, so that the compatibility of the flame retardant and a high polymer material is improved, and the mechanical property of the composite material is obviously improved;
5. the polyurethane-coated expandable graphite flame retardant mainly comprises elements C, O, H and N, and the prepared flame retardant is halogen-free and phosphorus-free and meets the requirements of environmental protection;
6. the preparation method disclosed by the invention is simple and convenient, does not need a solvent, is low in raw material price, and is beneficial to large-scale production, so that the application prospect is wide.
Drawings
FIG. 1 is a scanning electron micrograph of expandable graphite;
FIG. 2 is a scanning electron microscope photograph of polyurethane coated expandable graphite of example 4;
FIG. 3 is an X-ray photoelectron spectrum of the expandable graphite and the polyurethane-coated expandable graphite of example 4.
Detailed Description
For better understanding of the present invention, the following further illustrates the contents of the present invention in connection with the embodiments, but the embodiments of the present invention are not limited to the contents described in the following embodiments.
Example 1
Firstly, adding 8.3g of polyether polyol (with a hydroxyl value of 600 mgKOH/g) and 0.1g of catalyst PC-41 into a plastic cup, uniformly stirring, then adding 81.2g of expandable graphite into the solution at room temperature, fully and uniformly stirring in a high-speed stirrer, then adding 12g of PM-200 into the plastic cup, uniformly stirring at high speed, reacting for 4 hours at room temperature, crushing, sieving and drying after the reaction is finished, and drying the product in an oven at 60 ℃ for 12 hours to obtain the polyurethane-coated expandable graphite flame retardant with the particle size of 40 to 120 meshes.
Example 2
Firstly, adding 8.3g of polyether polyol (with a hydroxyl value of 600 mgKOH/g) and 0.1g of catalyst PC-41 into a plastic cup, uniformly stirring, then adding 101.5g of expandable graphite into the solution at room temperature, fully and uniformly stirring under a high-speed stirrer, then adding 12g of PM-200 into the plastic cup, uniformly stirring at high speed, reacting for 4 hours at room temperature, crushing, sieving and drying after the reaction is finished, and drying the product in an oven at 60 ℃ for 12 hours to obtain the polyurethane-coated expandable graphite flame retardant with the particle size of 40-120 meshes.
Embodiment 3
Firstly, adding 8.3g of polyether polyol (with a hydroxyl value of 600 mgKOH/g) and 0.1g of catalyst PC-41 into a plastic cup, uniformly stirring, then adding 121.8g of expandable graphite into the solution at room temperature, fully and uniformly stirring in a high-speed stirrer, then adding 12g of PM-200 into the plastic cup, uniformly stirring at high speed, reacting for 4 hours at room temperature, crushing, sieving and drying after the reaction is finished, and drying the product in an oven at 60 ℃ for 12 hours to obtain the polyurethane-coated expandable graphite flame retardant with the particle size of 40 to 120 meshes.
Example 4
Firstly, adding 4.2g of polyether polyol (with a hydroxyl value of 600 mgKOH/g) and 0.05g of catalyst PC-41 into a plastic cup, uniformly stirring, then adding 82.8g of expandable graphite into the solution at room temperature, fully and uniformly stirring under a high-speed stirrer, then adding 6g of PM-200 into the plastic cup, uniformly stirring at high speed, reacting for 4 hours at room temperature, crushing, sieving and drying after the reaction is finished, and drying the product in an oven at 60 ℃ for 12 hours to obtain the polyurethane-coated expandable graphite flame retardant with the particle size of 40-120 meshes.
Fig. 1 is a scanning electron microscope photograph of expandable graphite, and fig. 2 is a scanning electron microscope photograph of polyurethane-coated expandable graphite according to the present embodiment. It can be observed that the uncoated expandable graphite has a smooth surface, and the surface of the expandable graphite particles is rough after the polyurethane coating treatment, which indicates that the polyurethane is coated on the surface of the expandable graphite after the reaction.
FIG. 3 is an X-ray photoelectron spectrum of expandable graphite and the present case of polyurethane-coated expandable graphite. As can be seen from fig. 3, carbon (284.8 eV), oxygen (532.6 eV) and a trace amount of nitrogen (399.9 eV) were detected in the original expandable graphite. The oxygen content of the expandable graphite after the polyurethane coating treatment is increased from 14.58% to 17.83%, and the nitrogen content is increased from 1.53% to 2.04%. The increase of the content of oxygen and nitrogen indicates the introduction of polyurethane on the surface of the expandable graphite.
Example 5
Firstly, adding 4.2g of polyether polyol (with a hydroxyl value of 600 mgKOH/g) and 0.05g of catalyst PC-41 into a plastic cup, uniformly stirring, then adding 103.5g of expandable graphite into the solution at room temperature, fully and uniformly stirring in a high-speed stirrer, then adding 6g of PM-200 into the plastic cup, uniformly stirring at high speed, reacting for 4 hours at room temperature, crushing, sieving and drying after the reaction is finished, and drying the product in an oven at 60 ℃ for 12 hours to obtain the polyurethane-coated expandable graphite flame retardant with the particle size of 40 to 120 meshes.
The application data of the surface-coated polyurethane expandable graphite prepared in examples 1 to 5 in rigid polyurethane foam (composition: 100 parts of polyether polyol, 4 parts of water, 2 parts of silicone oil, 1 part of PC-41, and 240 parts of PM-200) are shown in Table 1. Compared with expandable graphite, the expandable graphite with polyurethane coated on the surface is added into polyurethane foam as a flame retardant to improve the compressive strength of the polyurethane foam, which shows that the compatibility of the flame retardant and a polyurethane high polymer material is improved by introducing surface organic groups; meanwhile, the oxygen index of the rigid polyurethane foam added with the expandable graphite with the polyurethane coated on the surface is obviously improved compared with the oxygen index of the rigid polyurethane foam added with the unmodified expandable graphite, which shows that the synergistic action of the polyurethane coated on the surface and the expandable graphite improves the flame retardant property.
TABLE 1 data for the samples prepared in examples 1 to 5 and for the use of comparative samples in rigid polyurethane foams
Claims (11)
1. A preparation method of a polyurethane-coated expandable graphite flame retardant is characterized by comprising the following steps: firstly, adding polyol and a catalyst into a container, wherein the mass ratio of the catalyst to the polyol is 0.01 to 5, stirring uniformly at room temperature, then adding expandable graphite, the mass ratio of the expandable graphite to the total amount of polyurethane is 5 to 50, stirring uniformly, then adding polyisocyanate, wherein the polyisocyanate is polymeric diphenylmethane diisocyanate with 25-40% of-NCO mass content, the mass ratio of the polyisocyanate to the polyol is 1 to 5, stirring sufficiently, reacting for 0.1 to 6h at normal temperature and normal pressure, crushing, sieving and drying to obtain the polyurethane-coated expandable graphite flame retardant.
2. The method for preparing the polyurethane-coated expandable graphite flame retardant according to claim 1, wherein the expandable graphite is 40 to 200 meshes of dry expandable graphite obtained by treating natural crystalline flake graphite with a strong acid and strong oxidant.
3. The method for preparing the polyurethane-coated expandable graphite flame retardant according to claim 1, wherein the polyol is any one or a mixture of polyether polyol, polyester polyol, pentaerythritol, ethylene glycol, diethylene glycol, glycerol, xylitol, sorbitol, propylene glycol, butylene glycol and hexylene glycol.
4. The preparation method of the polyurethane-coated expandable graphite flame retardant according to claim 3, wherein the hydroxyl value of the polyether polyol is 10 to 800mgKOH/g;
the hydroxyl value of the polyester polyol is 10 to 800mgKOH/g.
5. The preparation method of the polyurethane-coated expandable graphite flame retardant according to claim 1, wherein the polyisocyanate is any one or a mixture of several of Wanhua chemical CW-20, PM-130, PM-200, PM-2010, PM-2025 and PM-400.
6. The method of claim 1, wherein the catalyst is any one or more selected from tris (dimethylaminopropyl) hexahydrotriazine, 2,4, 6-tris (dimethylaminomethyl) phenol, 2-hydroxy-N, N, N-trimethyl-1-propylamine formate, triethylenediamine, pentamethyldiethylenetriamine, dimethylcyclohexylamine, dibutyltin dilaurate, stannous octoate, potassium acetate, and potassium isooctanoate.
7. The preparation method of the polyurethane-coated expandable graphite flame retardant according to claim 1, wherein the sieving condition is 20 to 200 meshes.
8. The preparation method of the polyurethane-coated expandable graphite flame retardant according to claim 1, wherein the drying condition is 30 to 120 ℃ for 1 to 24h.
9. The polyurethane-coated expandable graphite flame retardant prepared by the method according to any one of claims 1 to 8, wherein the polyurethane-coated expandable graphite flame retardant is of a core-shell structure, expandable graphite is used as a core, and polyurethane generated by reaction of polyisocyanate and polyol is used as a shell.
10. The polyurethane-coated expandable graphite flame retardant prepared by the method according to claim 9, wherein the average particle size of the polyurethane-coated expandable graphite flame retardant is 20-200 meshes.
11. The polyurethane-coated expandable graphite flame retardant prepared by the method according to claim 10, wherein the average particle size of the polyurethane-coated expandable graphite flame retardant is 40-120 meshes.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2359308A (en) * | 2000-02-07 | 2001-08-22 | Graftech Inc | Expandable graphite as a flame retardant in unsaturated polyester resins |
| CN103554428A (en) * | 2013-11-18 | 2014-02-05 | 中国林业科学研究院林产化学工业研究所 | Core-shell synergistic flame retardant polyurethane microencapsulation expandable graphite and application thereof in rigid polyurethane foaming plastic |
| CN106928491A (en) * | 2017-03-13 | 2017-07-07 | 南京大学 | A kind of microencapsulation expansible graphite and its preparation method and the application in composite polyurethane rigid foam is prepared |
| CN107880316A (en) * | 2017-11-07 | 2018-04-06 | 常州福隆工控设备有限公司 | A kind of preparation method of the anti-molten drop fire retardant of thermostabilization |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2359308A (en) * | 2000-02-07 | 2001-08-22 | Graftech Inc | Expandable graphite as a flame retardant in unsaturated polyester resins |
| CN103554428A (en) * | 2013-11-18 | 2014-02-05 | 中国林业科学研究院林产化学工业研究所 | Core-shell synergistic flame retardant polyurethane microencapsulation expandable graphite and application thereof in rigid polyurethane foaming plastic |
| CN106928491A (en) * | 2017-03-13 | 2017-07-07 | 南京大学 | A kind of microencapsulation expansible graphite and its preparation method and the application in composite polyurethane rigid foam is prepared |
| CN107880316A (en) * | 2017-11-07 | 2018-04-06 | 常州福隆工控设备有限公司 | A kind of preparation method of the anti-molten drop fire retardant of thermostabilization |
Non-Patent Citations (1)
| Title |
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| 基于微胶囊化聚磷酸铵和微胶囊化膨胀石墨的阻燃硬质聚氨酯泡沫复合材料的制备及性能;杨亚东;《复合材料学报》;20210531;第38卷(第5期);第1.1节、1.2.2节、图6 * |
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