Hollow microsphere modified expanded graphite, anti-settling flame-retardant polyurethane foam and preparation method and application of hollow microsphere modified expanded graphite and anti-settling flame-retardant polyurethane foam

Abstract

The invention provides hollow microsphere modified expanded graphite, anti-settling flame-retardant polyurethane foam as well as a preparation method and application of the hollow microsphere modified expanded graphite and the anti-settling flame-retardant polyurethane foam. The hollow microsphere modified expanded graphite is prepared from raw materials including hollow microspheres, hydroxylamine, expanded graphite and a catalyst. The anti-settling flame-retardant polyurethane foam is prepared from the following raw materials: expanded graphite modified by hollow microspheres, polyether polyol, a foam stabilizer, isocyanate and a foaming agent. By introducing the hollow microsphere modified expanded graphite, the dispersity of the expanded graphite in polyurethane is remarkably improved, the problem that the expanded graphite is easy to settle is effectively solved, and the conductivity of the graphite is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to hollow microsphere modified expanded graphite, anti-settling polyurethane foam, and a preparation method and application thereof. Background Art

[0002] As an important polymer material, polyurethane is widely used in new energy vehicles, consumer electronics, smart home appliances and other fields due to its excellent physical and mechanical properties, chemical stability and processing performance. However, in some special application scenarios, conventional polyurethane materials still have some limitations, such as insufficient flame retardancy.

[0003] In order to improve the flame retardant properties of polyurethane, expanded graphite is introduced into the polyurethane system. Expanded graphite has excellent flame retardant efficiency and can significantly improve the flame retardancy of polyurethane. However, the density of expanded graphite is 2.2g / cm 3 About, polyether polyol density 1g / cm 3 There are problems of poor dispersibility and easy sedimentation in polyurethane raw materials, and the conductivity of expanded graphite may affect electronic components. This not only affects the uniformity of the material, but also limits its effect in practical applications. Summary of the invention

[0004] In order to solve the problems in the prior art that expanded graphite is easy to settle in polyurethane, has poor dispersibility and too high conductivity, the present invention provides a hollow microsphere modified expanded graphite, anti-settling polyurethane foam and a preparation method and use thereof.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A first aspect of the present invention provides a hollow microsphere modified expanded graphite, which is prepared from raw materials including hollow microspheres, hydroxylamine, expanded graphite and a catalyst.

[0007] The cyano group on the surface of the hollow microspheres can be reduced by hydroxylamine to generate an amide oxime group. Under the action of a catalyst, the carboxyl group on the surface of the expanded graphite reacts with the amide oxime on the surface of the hollow microspheres modified by hydroxylamine, so that the hollow microspheres successfully modify the expanded graphite. Through the modification of the hollow microspheres, the true density of the expanded graphite can be significantly reduced, and the subsequent use of the hollow microspheres to prepare anti-settling flame-retardant polyurethane foam can be stably suspended in a polyether polyol mixture, thereby effectively solving the problem of rapid sedimentation of the expanded graphite during the production process of the flame-retardant polyurethane foam, and improving the flame-retardant stability of the product batch. At the same time, since the hollow microspheres are coated on the surface of the expanded graphite, the overlap between adjacent graphite particles can be isolated, the path of electron migration can be cut off, and the insulation performance of the polyurethane foam can be improved. The present invention provides a new idea for solving the performance differences within the batch caused by graphite sedimentation during the production process of flame-retardant polyurethane foam products, and developing flame-retardant polyurethane foam materials with high insulation performance, which has important theoretical significance and application value.

[0008] According to some embodiments of the present invention, in parts by weight, the expanded graphite is 2-16 parts by weight, the hydroxylamine is 2-5 parts by weight, the hollow microspheres are 8-30 parts by weight, and the catalyst is 0.5-1 part by weight.

[0009] According to some embodiments of the present invention, the hollow microspheres are organic hollow microspheres.

[0010] According to some embodiments of the present invention, the hydroxylamine is in the form of a hydroxylamine aqueous solution, and the concentration of the hydroxylamine aqueous solution is 1 to 3 mol / L;

[0011] According to some embodiments of the present invention, the catalyst is at least one of O-benzotriazole-tetramethyluronium hexafluorophosphate and N,N-diisopropylethylamine.

[0012] The second aspect of the present invention provides a method for preparing the hollow microsphere modified expanded graphite according to any one of the first aspects, comprising:

[0013] (1) mixing a hydroxylamine aqueous solution and hollow microspheres, heating to a first predetermined temperature, performing a first reaction, and performing a first drying to obtain hydroxylamine-modified hollow microspheres;

[0014] (2) mixing the hydroxylamine-modified hollow microspheres, expanded graphite, an achiral organic solvent and a catalyst, performing a second reaction at a second predetermined temperature, and performing a second drying to obtain the hollow microsphere-modified expanded graphite.

[0015] According to some embodiments of the present invention, the achiral organic solvent is at least one of chloroform, dimethyl sulfoxide, ethanol and n-butanol.

[0016] According to some embodiments of the present invention, in step (1), the first predetermined temperature is 40-60° C., and the first reaction time is 1-2 hours; the first drying temperature is 70-90° C., and the first drying time is 4-6 hours.

[0017] According to some embodiments of the present invention, in step (2), the second predetermined temperature is 50-80° C., and the second reaction time is 1-3 hours; the second drying temperature is 80-120° C., and the second drying time is 1-3 hours.

[0018] The third aspect of the present invention provides an anti-settling flame-retardant polyurethane foam, which is obtained by comprising the following raw materials:

[0019] The hollow microsphere-modified expanded graphite, polyether polyol, foam stabilizer, isocyanate and foaming agent as described in any one of the first aspects.

[0020] In some embodiments of the present invention, in parts by weight, the hollow microsphere modified expanded graphite is 2-10 parts by weight, the polyether polyol is 20-70 parts by weight, the foam stabilizer is 2-6 parts by weight, the isocyanate is 10-40 parts by weight, and the foaming agent is 0.5-5 parts by weight.

[0021] In some embodiments of the present invention, the polyether polyol is at least one of a difunctional polyether, a trifunctional polyether, or a multifunctional polyether.

[0022] In some embodiments of the present invention, the foam stabilizer is at least one of a copolymer of polyethylene oxide methyl siloxane or silicone oil.

[0023] In some embodiments of the present invention, the foaming agent is nitrogen.

[0024] The fourth aspect of the present invention provides a method for preparing the anti-settling polyurethane foam according to any one of the third aspects, comprising:

[0025] (1) uniformly mixing a polyether polyol, hollow microsphere-modified expanded graphite and a foam stabilizer to obtain a polyether component;

[0026] (2) uniformly mixing the polyether component obtained in step (1) with isocyanate and a foaming agent in a predetermined ratio, and foaming the mixture under stirring to obtain a foamed material;

[0027] (3) coating the foamed material obtained in step (2), and heating and curing the foamed material to obtain the anti-settling polyurethane foam.

[0028] In some embodiments of the present invention, the mixing temperature in step (1) is 20-30° C. and the mixing time is 0.5-1 h.

[0029] In some embodiments of the present invention, in step (2), the foaming temperature is 15-30° C., and the stirring speed is 300-800 rpm.

[0030] In some embodiments of the present invention, the mass ratio of the polyether component to the isocyanate is (3.21-3.58):1.

[0031] The fifth aspect of the present invention provides an application of the anti-settling flame-retardant polyurethane foam described in any one of the third aspects in the field of heat insulation, insulation and shock absorption materials.

[0032] The technical solution provided by the present invention includes at least the following beneficial effects:

[0033] By introducing hollow microspheres to modify expanded graphite, the dispersibility of expanded graphite in polyurethane is significantly improved, effectively solving the problem of easy sedimentation of expanded graphite. The introduction of hollow microspheres reduces the conductivity of graphite, achieving the goal of reducing conductivity while maintaining the good performance of polyurethane.

[0034] The hollow microsphere modified expanded graphite preparation method provided by the present invention is simple, wherein the hollow microspheres are grafted with amino groups, and then a condensation reaction occurs with the carboxyl groups on the surface of the expanded graphite. The method not only solves the problem of easy sedimentation and poor dispersibility of expanded graphite in polyurethane in the prior art, but also achieves the goal of reducing electrical conductivity. The material has higher stability and uniformity while maintaining the excellent properties of polyurethane, provides a new idea for the development of high-performance and multifunctional polyurethane materials, and has important theoretical significance and application value.

[0035] The invention is simple and easy to prepare polyurethane foam, can be realized on conventional polyurethane production equipment, and has good industrial application prospects. The obtained anti-settling flame-retardant polyurethane foam has excellent stability, uniformity and comprehensive performance, and can be widely used in the fields of heat insulation, insulation, shock absorption, etc. By controlling the ratio of each component and the preparation process parameters, the performance of the product can be flexibly adjusted to meet the needs of different application scenarios. DETAILED DESCRIPTION

[0036] The exemplary embodiments of the present disclosure will be described in more detail below. Although exemplary embodiments of the present disclosure are shown, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to enable the scope of the present disclosure to be fully communicated to those skilled in the art.

[0037] The invention provides a hollow microsphere modified expanded graphite, wherein the expanded graphite is modified by the hollow microspheres, and then can be compounded with a polyurethane raw material to prepare a polyurethane foam. The addition of the hollow microspheres can significantly improve the dispersibility of the expanded graphite in polyether polyols, improve the stability and uniformity of the polyurethane, and effectively solve the problem that the expanded graphite is easy to settle during use. At the same time, the introduction of the hollow microspheres can also reduce the conductivity of the expanded graphite, thereby achieving the goal of reducing the conductivity while improving the product stability.

[0038] The hollow microsphere modified expanded graphite provided by the present invention is synthesized from hollow microspheres, hydroxylamine and expanded graphite as raw materials using a non-chiral organic solvent under the action of a catalyst.

[0039] According to a specific implementation manner, in parts by weight, the hollow microspheres are 8-30 parts, the hydroxylamine is 2-5 parts, the expanded graphite is 2-16 parts, and the catalyst is 0.5-1 part.

[0040] According to a preferred embodiment, in parts by weight, the hollow microspheres are 18-23 parts, the hydroxylamine is 2.5-3.5 parts, the expanded graphite is 8-12 parts, and the catalyst is 0.7-1 part.

[0041] According to a preferred embodiment, in parts by weight, the hollow microspheres are 20 parts, the hydroxylamine is 3 parts, the expanded graphite is 10 parts, and the catalyst is 0.8 parts.

[0042] The particle size of the expanded graphite used is 150 mesh; the hollow microspheres are expanded hollow microspheres with a particle size of 50 microns.

[0043] According to a specific embodiment, the catalyst used is at least one of O-benzotriazole-tetramethyluronium hexafluorophosphate and N,N-diisopropylethylamine.

[0044] According to a preferred embodiment, the catalyst is a mixture of O-benzotriazole-tetramethyluronium hexafluorophosphate and N,N-diisopropylethylamine in a weight ratio of 1:1.

[0045] The present invention also provides a method for preparing hollow microsphere modified expanded graphite, comprising the following steps:

[0046] (1) mixing a hydroxylamine aqueous solution and hollow microspheres, heating to a first predetermined temperature, performing a first reaction, and performing a first drying to obtain hydroxylamine-modified hollow microspheres;

[0047] (2) mixing the hydroxylamine-modified hollow microspheres, expanded graphite, an achiral organic solvent and a catalyst, performing a second reaction at a second predetermined temperature, and performing a second drying to obtain the hollow microsphere-modified expanded graphite.

[0048] Wherein step (1) can be completed in a heat-collecting heating magnetic stirrer, the heating temperature of the magnetic stirrer is 50°C, the reaction time is 1.5h, the oven temperature is 80°C, and the drying time is 5 hours;

[0049] Step (2) can be completed in an oil bath pot, the temperature of the oil bath is 65° C., the reaction time is 2 hours; the drying temperature is 80° C., and the drying time is 5 hours.

[0050] The achiral organic solvent mentioned includes but is not limited to chloroform, dimethyl sulfoxide, ethanol, n-butanol, etc. According to a preferred embodiment, the achiral organic solvent is n-butanol.

[0051] The concentration of the hydroxylamine aqueous solution in step (1) is 1 mol / L to 3 mol / L, preferably 1 mol / L.

[0052] The invention also provides an anti-settling polyurethane foam, which is synthesized from hollow microsphere modified expanded graphite, polyether polyol, foam stabilizer, isocyanate and foaming agent as raw materials.

[0053] According to a specific embodiment, by weight, the hollow microsphere modified expanded graphite is 2-10 weight parts, the polyether polyol is 20-70 weight parts, the foam stabilizer is 2-6 weight parts, the isocyanate is 10-40 weight parts, and the whipping agent is 0.5-5 weight parts. By compounding the hollow microsphere modified expanded graphite with polyurethane raw materials in different proportions, a novel polyurethane material with excellent thermal properties, mechanical properties and electrical properties can be manufactured. This modification method not only solves the sedimentation problem of expanded graphite, but also improves the stability and uniformity of polyurethane, and reduces electrical conductivity. According to a preferred embodiment, by weight, the hollow microsphere modified expanded graphite is 6 weight parts, the polyether polyol is 50 weight parts, the foam stabilizer is 4 weight parts, the isocyanate is 30 weight parts, and the whipping agent is 2 weight parts.

[0054] The polyether polyol mentioned is at least one of a difunctional polyether, a trifunctional polyether, or a multifunctional polyether. According to a preferred embodiment, the polyether polyol is polyoxypropylene triol.

[0055] The foam stabilizer mentioned is at least one of a copolymer of polyethylene oxide methyl siloxane or silicone oil. According to a preferred embodiment, the foam stabilizer is a copolymer of polyethylene oxide methyl siloxane.

[0056] According to a preferred embodiment, the isocyanate is diphenylmethane diisocyanate.

[0057] The blowing agent used in this article is nitrogen.

[0058] The present invention also provides a method for preparing an anti-settling polyurethane foam, comprising the following steps:

[0059] (1) uniformly mixing a polyether polyol, hollow microsphere-modified expanded graphite and a foam stabilizer to obtain a polyether component;

[0060] (2) uniformly mixing the polyether component obtained in step (1) with isocyanate and a foaming agent in a predetermined ratio, and foaming the mixture under stirring to obtain a foamed material;

[0061] (3) coating the foamed material obtained in step (2), and heating and curing the foamed material to obtain the anti-settling polyurethane foam.

[0062] According to a specific implementation, in step (1), the mixing temperature is 20-30° C. and the mixing time is 0.5-1 h.

[0063] According to a preferred embodiment, the mixing temperature in step (1) is 25° C. and the mixing time is 1 h.

[0064] Step (2) can be foamed in a foaming machine. According to a preferred embodiment, in step (2), the temperature of the foaming machine is 24°C and the stirring speed is 600 rpm. In step (3), heating and curing can be performed in an oven, the temperature of the oven can be adjusted to 150°C, the curing time is 15 minutes, and the mass ratio of the polyether component to the isocyanate is controlled at 3.42:1.

[0065] The anti-settling polyurethane foam provided can be used in the fields of heat insulation, insulation, shock absorption and the like, for example, it can be used to prepare heat insulation, insulation or shock absorption materials.

[0066] For example, the polyurethane foam provided can be used in the automotive industry, where it is used for automotive interior parts, seats, sound insulation materials, shock-absorbing materials, etc. It can provide good sound insulation, reduce noise interference, and has excellent buffering properties to protect in-vehicle equipment from vibration and impact.

[0067] Polyurethane foam can also be used in electronic devices such as mobile phones, laptops, LCD monitors, etc. It is used to make shock pads, seals, shock-absorbing cushioning materials, etc., effectively protecting electronic components from damage. In addition, polyurethane foam is also used for dustproof and waterproof sealing of mobile phones.

[0068] The technical scheme of the present invention is described below by specific examples. If the specific conditions are not specified in the embodiments of the present invention, the conditions are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be obtained commercially. Only some reagents used in the embodiments of the present invention are provided below. Raw materials of different manufacturers and models do not affect the implementation of the technical scheme of the present invention and the realization of technical effects.

[0069]

[0070] Example 1

[0071] Example 1 provides a hollow microsphere modified expanded graphite, which is synthesized from the following raw materials in parts by weight: 12 parts by weight of hollow microspheres, 2 parts by weight of hydroxylamine, 10 parts by weight of expanded graphite, and 0.7 parts by weight of a catalyst.

[0072] The specific preparation method is as follows:

[0073] (1) adding the hollow microspheres to a hydroxylamine aqueous solution, heating to 50° C. using a heat-collecting heating magnetic stirrer, reacting for 1.5 hours, and after the reaction is completed, rinsing with deionized water and drying at 80° C. for 5 hours to obtain hydroxylamine-modified hollow microspheres;

[0074] (2) placing the modified hollow microspheres obtained in step (1), expanded graphite, solvent and catalyst in a bath, reacting at 65° C. for 2 h, and then drying in an oven at 100° C. for 2 h to obtain expanded graphite modified with hollow microspheres.

[0075] Then, the prepared hollow microspheres and expanded graphite were used to prepare anti-settling polyurethane foam, wherein the raw materials used are as follows:

[0076] 6 parts by weight of hollow microsphere modified expanded graphite, 50 parts by weight of polyether polyol, 4 parts by weight of foam stabilizer, 30 parts by weight of isocyanate, and 3.5 parts by weight of blowing agent.

[0077] The specific preparation method is as follows:

[0078] (1) Expanded graphite modified with hollow microspheres, polyether polyol, and a foam stabilizer were stirred and mixed at 25° C. for 1 h to obtain a polyether component.

[0079] (2) The polyether component obtained in step (1) is mixed with isocyanate and nitrogen in a foaming machine at a speed of 600 rpm and stirred for foaming, and the temperature of the foaming machine is controlled at 24° C.

[0080] (3) applying the foamed material obtained in step (2) into a high-temperature oven, and heating and curing at 150° C. for 15 min to obtain a hollow microsphere-modified expanded graphite anti-settling polyurethane.

[0081] Example 2

[0082] Example 2 provides a hollow microsphere modified expanded graphite, which is synthesized from the following raw materials in parts by weight: 20 parts by weight of hollow microspheres, 3 parts by weight of hydroxylamine, 10 parts by weight of expanded graphite, and 0.8 parts by weight of catalyst. The preparation method is the same as that of Example 1.

[0083] Then, the prepared hollow microspheres and expanded graphite were modified to prepare anti-settling polyurethane foam according to the method of Example 1, wherein the raw materials used are as follows:

[0084] 6 parts by weight of hollow microsphere modified expanded graphite, 50 parts by weight of polyether polyol, 4 parts by weight of foam stabilizer, 30 parts by weight of isocyanate, and 2 parts by weight of blowing agent.

[0085] Example 3

[0086] Example 3 provides a hollow microsphere modified expanded graphite, which is synthesized from the following raw materials in parts by weight: 25 parts by weight of hollow microspheres, 5 parts by weight of hydroxylamine, 10 parts by weight of expanded graphite, and 0.9 parts by weight of catalyst. The preparation method is the same as that of Example 1.

[0087] Then, the prepared hollow microspheres were used to modify the expanded graphite, and the anti-settling polyurethane foam was prepared according to the method of Example 1, wherein the raw materials used were as follows:

[0088] 6 parts by weight of hollow microsphere modified expanded graphite, 50 parts by weight of polyether polyol, 4 parts by weight of foam stabilizer, 30 parts by weight of isocyanate, and 1 part by weight of foaming agent.

[0089] Example 4

[0090] Example 4 provides a hollow microsphere modified expanded graphite, which is synthesized from the following raw materials in parts by weight: 30 parts by weight of hollow microspheres, 5 parts by weight of hydroxylamine, 10 parts by weight of expanded graphite, and 1 part by weight of catalyst. The preparation method is the same as that of Example 1.

[0091] Then, the prepared hollow microsphere modified expanded graphite was used to prepare anti-settling polyurethane foam with reference to the method of Example 1, wherein the raw materials used were as follows:

[0092] 6 parts by weight of hollow microsphere modified expanded graphite, 50 parts by weight of polyether polyol, 4 parts by weight of foam stabilizer, 30 parts by weight of isocyanate, and 0.8 parts by weight of blowing agent.

[0093] Example 5

[0094] Example 5 provides a hollow microsphere modified expanded graphite, which is synthesized from the following raw materials in parts by weight: 30 parts by weight of hollow microspheres, 3.5 parts by weight of hydroxylamine, 8 parts by weight of expanded graphite, and 1 part by weight of a catalyst.

[0095] Then, the prepared hollow microspheres and expanded graphite were modified to prepare anti-settling polyurethane foam according to the method of Example 1, wherein the raw materials used are as follows:

[0096] 7 parts by weight of hollow microsphere modified expanded graphite, 55 parts by weight of polyether polyol, 5 parts by weight of foam stabilizer, 35 parts by weight of isocyanate, and 0.5 parts by weight of blowing agent.

[0097] Comparative Example 1

[0098] This comparative example does not use hollow microsphere modification, and directly composites expanded graphite with polyurethane raw materials. The formula is as follows:

[0099] 6 parts by weight of unmodified expanded graphite, 50 parts by weight of polyether polyol, 4 parts by weight of foam stabilizer, 30 parts by weight of isocyanate, and 5 parts by weight of blowing agent.

[0100] The preparation process is the same as that of Example 1.

[0101] Effect comparison ratio

[0102] In order to compare the effects of the hollow microsphere modified expanded graphite and the anti-settling flame-retardant polyurethane foam provided by the present invention, the following tests were conducted:

[0103] 1. Density and suspension performance comparison

[0104] The unmodified expanded graphite of Comparative Example 1 and the hollow microsphere modified expanded graphite of Example 1 were tested for density, the suspension performance of the polyether component in the preparation process was tested, and the density of the prepared polyurethane foam was tested. The results are shown in Table 1 below.

[0105] Table 1 Density and suspension performance results

[0106]

[0107] From the above results, it can be seen that the density of the unmodified expanded graphite in Comparative Example 1 is 2.20 g / cm 3 , much higher than polyether polyols (about 1.0g / cm 3), which will lead to rapid sedimentation when mixed with polyether polyols. The density of the expanded graphite modified by the hollow microspheres of Examples 1 to 5 is equivalent to that of the polyether polyol. In particular, the dosage of the hollow microspheres of Example 2 is the most appropriate (20 parts), so that the density of the modified expanded graphite is close to that of the polyether polyol, achieving the best suspension effect. When the dosage of the hollow microspheres in Examples 3-5 is large (25-30 parts), the density is too low and floating occurs. The density of the polyurethane foam prepared by Comparative Example 1 and Examples 1-5 is equivalent, which is obtained by nitrogen adjustment.

[0108] 2. Flame retardant performance comparison (UL-94 test)

[0109] The polyurethane foams prepared in Comparative Example 1 and Examples 1-5 were used to test the horizontal flame retardancy of the head and tail materials of the same roll of polyurethane foam. The specific steps are as follows:

[0110] Cut the polyurethane foam sample into 50mm*150mm strips, 5 samples per group, and mark the positions of 25mm, 60mm, and 125mm; place the sample at the specified position, the flame height is about 38mm, and the fire source is applied for 60s; HBF: the burning rate of the material between the 25mm and 125mm marks does not exceed 40mm / min, or it extinguishes itself before the 125mm mark but does not meet the requirements of HF-1 and HF-2. The results are shown in Table 2 below:

[0111] Table 2 Horizontal flame retardant performance test results

[0112]

[0113] It can be seen from the results of Table 2 above that due to the serious sedimentation of expanded graphite in Comparative Example 1, there are obvious differences in the flame retardant properties of the sample head / tail. It can be seen from the results of Comparative Example 1 that the uniformity of the polyurethane foam prepared by Examples 1-5 in the entire experiment is significantly improved. In particular, the flame retardant properties of the head and tail of the polyurethane foam prepared by Example 2 are more stable and uniform with the increase of the content of hollow microspheres, which shows that as the hollow microspheres are successfully grafted onto the expanded graphite, good compatibility is formed in the polyether component at the same time. Due to the best suspension, the head / tail of the sample reaches the HF-1 level and there is no difference. In other embodiments, after the amount of hollow microspheres increases to a certain proportion, stratification and flame retardant instability occur again. This is because there are too many hollow microspheres, resulting in too low density of expanded graphite after the hollow microspheres are modified, and floating occurs. Although they all reach the HF-1 level, due to the presence of slight sedimentation or floating, the uniformity is slightly inferior to Example 2.

[0114] 3. Electrical performance

[0115] The electrical properties of the polyurethane foam prepared above were compared as follows (test conditions: 23±2°C, 50%RH):

[0116] Volume resistivity: According to GB / T 1410 standard, tested using ZC-36 high resistance meter

[0117] Breakdown voltage: According to GB / T 1408 standard, electrode diameter 25mm

[0118] Dielectric constant: According to GB / T 1409 standard, frequency 1kHz

[0119] The results are shown in Table 3 below:

[0120] Table 3 Electrical performance test results

[0121]

[0122]

[0123] By comparing the volume resistivity test, it was found that the modified samples were significantly improved compared with the comparative example 1. The volume resistivity of the comparative example 1 was 2.3×108Ω·m, while the volume resistivity of the examples 1-5 was increased to 10 11 The highest value of 8.5×10 11 Ω·m. This shows that the hollow microsphere modification effectively blocks the conductive path between graphite particles and significantly improves the insulation performance of the material.

[0124] The breakdown voltage test results show that the breakdown voltage of comparative example 1 is 12.5 kV / mm, while the breakdown voltages of examples 1 to 5 are all improved. Among them, example 2 reaches 15.8 kV / mm, which is 26.4% higher than comparative example 1. This result shows that the coating of hollow microspheres significantly enhances the material's ability to resist electrical breakdown and improves the insulation strength.

[0125] The dielectric constant test results show that the dielectric constant of comparative example 1 is 4.2, while Examples 1-5 all show lower dielectric constant values. The dielectric constant of Example 2 is reduced to 3.2, which is 23.8% lower than that of comparative example 1, achieving the most ideal effect. The reduction of the dielectric constant means that the dielectric loss of the material is reduced and the insulation performance is improved.

[0126] From the comprehensive electrical performance test results, all modified samples have obvious improvements over comparative example 1, and example 2 performs the best. This verifies the effectiveness of the hollow microsphere modification and the rationality of the formula used in example 2. The electrical performance of the modified material is significantly improved, making it more suitable for use in situations where insulation performance is required.

[0127] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hollow microsphere modified expanded graphite, characterized in that: The method is prepared by using raw materials including hollow microspheres, hydroxylamine, expanded graphite and a catalyst; Optionally, in parts by weight, the hollow microspheres are 8-30 parts, the hydroxylamine is 2-5 parts, the expanded graphite is 2-16 parts by weight, and the catalyst is 0.5-1 part by weight.

2. The hollow microsphere modified expanded graphite according to claim 1, characterized in that: The hollow microspheres are organic hollow microspheres; Optionally, the hydroxylamine is in the form of a hydroxylamine aqueous solution, and the concentration of the hydroxylamine aqueous solution is 1 to 3 mol / L; Optionally, the catalyst is at least one of O-benzotriazole-tetramethyluronium hexafluorophosphate and N,N-diisopropylethylamine.

3. A method for preparing hollow microsphere modified expanded graphite according to claim 1 or 2, characterized in that: include: (1) mixing a hydroxylamine aqueous solution and hollow microspheres, heating to a first predetermined temperature, performing a first reaction, and performing a first drying to obtain hydroxylamine-modified hollow microspheres; (2) mixing the hydroxylamine-modified hollow microspheres, expanded graphite, a non-chiral organic solvent and a catalyst, performing a second reaction at a second predetermined temperature, and performing a second drying to obtain the hollow microsphere-modified expanded graphite; Optionally, the achiral mobile phone solvent is at least one of chloroform, dimethyl sulfoxide, ethanol and n-butanol.

4. The method for preparing hollow microsphere modified expanded graphite according to claim 3, characterized in that, In step (1), the first predetermined temperature is 40-60° C., and the first reaction time is 1-2 hours; the first drying temperature is 70-90° C., and the first drying time is 4-6 hours; Optionally, in step (2), the second predetermined temperature is 50-80° C., and the second reaction time is 1-3 hours; the second drying temperature is 80-120° C., and the second drying time is 1-3 hours. 5.An anti-settling flame-retardant polyurethane foam, characterized in that: Obtained from raw materials comprising: The hollow microsphere-modified expanded graphite according to claim 1 or 2, polyether polyol, foam stabilizer, isocyanate and foaming agent.

6. The anti-settling flame-retardant polyurethane foam according to claim 5, wherein the composition is, in parts by weight: The hollow microsphere modified expanded graphite is 2-10 parts by weight, The polyether polyol is 20-70 parts by weight, The foam stabilizer is 2-6 parts by weight, The isocyanate is 10-40 parts by weight, The foaming agent is 0.5-5 parts by weight.

7. The anti-settling flame-retardant polyurethane foam according to claim 5, characterized in that: The polyether polyol is at least one of a difunctional polyether, a trifunctional polyether, or a multifunctional polyether; Optionally, the foam stabilizer is at least one of a copolymer of polyethylene oxide methyl siloxane or silicone oil; Optionally, the blowing agent is nitrogen.

8. A method for preparing the anti-settling flame-retardant polyurethane foam according to any one of claims 5 to 7, characterized in that: include: (1) uniformly mixing a polyether polyol, hollow microsphere-modified expanded graphite and a foam stabilizer to obtain a polyether component; (2) uniformly mixing the polyether component obtained in step (1) with isocyanate and a foaming agent in a predetermined ratio, and foaming the mixture under stirring to obtain a foamed material; (3) coating the foaming material obtained in step (2), and heating and curing the foaming material to obtain the anti-settling flame-retardant polyurethane foam.

9. The method for preparing the anti-settling flame-retardant polyurethane foam according to claim 8, characterized in that: The mixing temperature in step (1) is 20-30° C. and the mixing time is 0.5-1 h; Optionally, in step (2), the foaming temperature is 15-30° C., and the stirring speed is 300-800 rpm; Optionally, the mass ratio of the polyether component to the isocyanate is (3.21-3.58):

1.

10. Use of the anti-settling flame-retardant polyurethane foam according to any one of claims 5 to 7 in the field of heat insulation, insulation and shock absorption materials.

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