Amino polysiloxane and use in epoxy resin based intumescent fireproofing coatings

Abstract

The application belongs to the technical field of fireproof coating and discloses amino polysiloxane and application of the amino polysiloxane in epoxy resin-based intumescent fireproof coating. The B component of the fireproof coating is the amino polysiloxane obtained by synthesis. The amino polysiloxane improves the compatibility with the epoxy resin by introducing phenyl side groups. The introduction of side-chain amino groups provides the reactivity of the polysiloxane, so that the polysiloxane can crosslink and cure the epoxy resin. The high chain flexibility of the polysiloxane improves the behavior that the crosslinking network structure of the traditional epoxy resin hinders the expansion of the coating, and improves the expansion effect and the fireproof performance. When the thickness of the coating is 2 mm, the limiting fire resistance time measured on a small fire resistance performance testing device is up to 63.4 min, which is obviously higher than the fire resistance time of the fireproof coating using a general polyamide curing agent. The introduction of the polysiloxane improves the fireproof performance of the epoxy resin-based intumescent fireproof coating, and also improves the weather resistance and corrosion resistance of the coating.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coating, and relates to an epoxy resin-based intumescent fireproof coating containing amino polysiloxane and a preparation method thereof. BACKGROUND

[0002] Generally, intumescent fireproof coating contains intumescent flame retardant: acid source, carbon source, gas source, and a binder is used to combine them together, and ammonium polyphosphate, pentaerythritol, and melamine are commonly used as the acid source, the carbon source, and the gas source, respectively. When in contact with heat, the intumescent coating reaches a critical temperature, starts to melt, and is converted into a high-viscosity liquid, the gas source undergoes a chemical reaction to generate inert gas, the acid reacts with the carbon source to form an ester, the gas is trapped in the viscous fluid and forms bubbles, resulting in the expansion of the coating. According to the classical foaming theory of polymers and the bubble growth mechanism, the intumescent fireproof performance of the intumescent fireproof coating is closely related to the molecular chain structure, crosslinking density, and molecular chain length of the resin.

[0003] Using epoxy resin as the base resin of the fireproof coating makes the fireproof coating have higher adhesion and better resistance to acid, alkali, and corrosion of other chemical substances. However, as a thermosetting resin, the epoxy resin is crosslinked into a network structure, does not melt when heated, and has poor molecular chain movement ability. For the above reasons, the high crosslinking density epoxy coating film obtained by using a common epoxy resin curing agent will affect the expansion and foaming of the coating when heated in a fire, which limits its application in fireproof coatings. Therefore, designing and synthesizing a new type of epoxy resin curing agent so that the cured and crosslinked epoxy resin still has a certain deformability when heated is a difficult problem that needs to be solved in the intumescent epoxy fireproof coating industry. At the same time, since the weather resistance of the epoxy resin itself is not good, when the epoxy fireproof coating is directly used outdoors, how to improve the weather resistance and corrosion resistance of the epoxy coating is also very crucial.

[0004] Silicones have the characteristics of high and low temperature resistance, weather resistance, high chain flexibility, electrical insulation, hydrophobicity, and flame retardancy. Currently, in the field of silicone-modified epoxy resin, the modified resin needs to be added with an epoxy resin curing agent for crosslinking and curing after modification, which is complicated and has a complex process. For example, Chinese Patent CN115505239A provides a preparation method of a silicone-modified epoxy resin material. The preparation steps are as follows: mixing a functional silane monomer and an epoxy resin, heating and stirring until they are uniformly mixed; adding an alkali solution, a catalyst, and an epoxy resin curing agent, stirring and reacting, and then curing to obtain a silicone-modified epoxy resin material. This modification method has a complex process and harsh curing conditions, and the silane monomer is not chemically bonded to the epoxy resin, which affects the mechanical properties of the material. Chinese Patent CN1662581A designs an amino-functionalized silicone, in which the side groups can be substituted by various different groups, but the silicone segment has only one structural unit, which cannot accurately adjust the composition of the silicone and its performance when used in epoxy resin. The above-mentioned research on amino-silicone-modified epoxy resin is complicated in steps, and an additional curing agent is needed to cure the epoxy resin. On the other hand, there is a lack of research on the influence of different compositions of amino-silicone side groups on the performance of modified epoxy resin cured products, and there is no report on the use of amino-silicone as a curing agent and epoxy resin modifier in the field of epoxy resin-based intumescent fireproof coating. SUMMARY

[0005] To solve the above problems, an amino-silicone with side chain amino and phenyl groups is synthesized by anionic ring-opening polymerization in this paper to cure the epoxy resin and prepare an intumescent fireproof coating. The synthesized amino-silicone is used in an epoxy resin-based intumescent fireproof coating to solve the problem of poor intumescent fireproof ability and weather and corrosion resistance of the epoxy fireproof coating obtained by using traditional epoxy resin curing agents.

[0006] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows:

[0007] The epoxy resin-based intumescent fireproof coating according to the present application comprises A and B components, wherein the A component comprises the following components: epoxy resin 15-18 parts, ammonium polyphosphate 25-30 parts, melamine 10-15 parts, pentaerythritol 10-15 parts, titanium white 10-15 parts, solvent dimethylbenzene 5-10 parts, and solvent n-butanol 4-8 parts. The B component comprises amino-silicone 12-15 parts. The sum of the weight fractions of all components in the A and B components is 100 parts.

[0008] The synthesis of the amino-silicone is shown in the following schematic route:

[0009]

[0010] x, y, and z represent the proportions of different side chain structural units, where methyl groups account for 50%–90% of the total side chain molar percentage, phenyl groups account for 0%–40% of the total side chain molar percentage, and amino groups account for 10%–40% of the total side chain molar percentage.

[0011] (1) Synthesis of aminopolysiloxane: Deionized water was added to a three-necked flask equipped with a stirrer. Silane coupling agent KH-602 was slowly added dropwise using a constant-pressure dropping funnel. After reacting at 55°C for 8 hours, excess water was removed by rotary evaporation. The solution was then dissolved in acetone for later use, yielding a KH-602 oligomer solution with a concentration of 50–60%. Trimethyltriphenylcyclotrisiloxane (D3...) Ph Dissolve D3 in xylene to a concentration of 47-55%. Ph A mixed feed solution was prepared by mixing the solution, octamethylcyclotetrasiloxane (D4), and KH-602 oligomer solution. 30% of the total mixed feed solution was added to a four-necked flask, followed by the addition of tetramethylammonium hydroxide (TMAH). After reacting for 30 minutes under a nitrogen atmosphere, the remaining 70% of the mixed feed solution was slowly added dropwise using a constant-pressure dropping funnel. After reacting for 10–20 hours, the mixture was heated to 120°C to decompose excess catalyst. After 2 hours, the solvent was completely evaporated to obtain the final product.

[0012] KH-602, D3 Ph The molar ratio of D4 is 1:(0~0.7):(0~0.7), and the molar ratio of D3 is... Ph D4 is not simultaneously 0; the side groups of amino polysiloxane are composed of methyl, phenyl, and side-chain amino groups. By controlling the molar ratio of added monomers, the molar percentage of methyl in the total side groups can be controlled to be 60% to 90%, phenyl in the total side groups to be 0% to 40%, and side-chain amino in the total side groups to be 10% to 40%.

[0013] Further preferably, in the aminopolysiloxane, methyl groups account for 60%–90% of the total side group molar percentage, phenyl groups account for 0%–20% of the total side group molar percentage, and side-chain amino groups account for 10%–20% of the total side group molar percentage.

[0014] The preferred embodiment is that the side group molar percentage of the aminopolysiloxane consists of 70.0% methyl, 10.0% phenyl, and 20.0% amino.

[0015] Furthermore, the molar ratio of silane coupling agent KH-602 to deionized water is 1:2 to 1:4.

[0016] Furthermore, the amount of the catalyst tetramethylammonium hydroxide added is 0.05% to 0.1% of the total mass of all monomers.

[0017] Preparation of fireproof coating: ammonium polyphosphate, melamine, pentaerythritol, titanium dioxide, epoxy resin, dimethylbenzene, n-butanol were mixed and uniformly dispersed by high-speed dispersion machine at 1000 r / min for 10 min. Amino polysiloxane was added to the slurry obtained by dispersion.

[0018] Further, the epoxy resin is bisphenol A diglycidyl ether epoxy resin, and the epoxy value is 0.48-0.54 eq / 100 g.

[0019] Further, the addition amount of amino polysiloxane is 1:1 based on the equivalent of active hydrogen and the equivalent of epoxy.

[0020] Further, the mass ratio of solvent dimethylbenzene to n-butanol is 7:3.

[0021] On the one hand, the high chain flexibility of polysiloxane improves the behavior of the traditional high-density cross-linked network structure of epoxy resin hindering the expansion of the coating, and on the other hand, the introduction of the amino side chain improves the reactivity of polysiloxane, so that it can directly cure the epoxy resin, the introduction of the phenyl side group improves the compatibility of polysiloxane and epoxy resin, and at room temperature, the two will not appear phase separation phenomenon, and can be cured at room temperature, and by controlling the ratio of different side groups of polysiloxane, the glass transition temperature of the cured epoxy resin is adjusted, so that the coating has suitable viscoelastic properties after being heated, and cooperates with the intumescent flame retardant to foam. At the same time, the introduction of polysiloxane further improves the weather resistance and corrosion resistance of the epoxy resin-based intumescent fireproof coating.

[0022] Compared with the prior art, the advantages of the present application are:

[0023] The amino polysiloxane prepared in the present application is obtained by introducing different side group-containing organosilicon monomers, and a series of amino polysiloxanes with different side group ratios are obtained by controlling the molar ratio of the added monomers, which are used to directly cure the epoxy resin-based intumescent fireproof coating. The advantages are that the amino polysiloxane is used as an epoxy resin modifier and an epoxy resin curing agent at the same time, the side group composition (amino, methyl, phenyl) of the amino polysiloxane is adjusted, so that it has reactivity and compatibility with the epoxy resin, and the reactivity and good compatibility enable it to directly cure the epoxy resin at room temperature without high-temperature curing or additional curing agent. And by the high chain flexibility of polysiloxane and the appropriate side group ratio, the glass transition temperature of the coating is adjusted, the behavior of the traditional high-density cross-linked network structure of epoxy resin hindering the expansion of the coating is improved, and the expansion effect and fireproof performance of the epoxy resin-based intumescent fireproof coating are significantly improved. Compared with the traditional curing agent, the corrosion resistance and weather resistance of the epoxy resin-based intumescent fireproof coating are also greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 NMR spectrum of amino polysiloxane PPMS-1Ph in Example 2.

[0025] Figure 2 Glass transition temperature (Tg) curves of different formulations of cured epoxy varnish.

[0026] Figure 3 TGA / DTG curves of cured films of different formulations of coatings, respectively.

[0027] Figure 4 Limiting fire resistance test curve.

[0028] Figure 5 Microscopic morphology of carbon layer after fire resistance test of fireproof coating.

[0029] Figure 6 UV aging resistance curve of coating.

[0030] Figure 7 Electrochemical impedance spectrum of fireproof coating after 12 h.

[0031] Figure 8 Electrochemical impedance spectrum of fireproof coating after 24 h.

[0032] Figure 9 Preparation flow chart. DETAILED DESCRIPTION

[0033] The present application will now be further described in conjunction with specific examples, which are intended to illustrate the present application rather than further limit it.

[0034] The raw materials used in the present application are all commercially available industrial products, and the test methods used are:

[0035] 1H-NMR spectrum analysis: a German Bruker ARX-400 nuclear magnetic resonance instrument was used to determine the sample in deuterated acetone as solvent.

[0036] Glass transition temperature (Tg) test: a differential scanning calorimeter of Pyris 8500 type from Perkin Elmer Company of the United States was used to determine the sample in nitrogen atmosphere at a heating rate of 20℃ / min.

[0037] Limiting fire resistance test: the fire resistance test of the coating was tested by the fire resistance time test device Q / 6S 2153 developed by the company, and the limiting fire resistance time was the time required for the substrate backboard to reach 580℃. The test was based on the standards Q / 6S 2138-2007 and GB / T 9978.

[0038] Thermogravimetric analysis: Thermogravimetric analysis of different formulations of fireproof coating was determined by using TG 209F3 thermal gravimetric analyzer of Germany NETZSCH, nitrogen atmosphere, heating rate 20℃ / min, from 30℃ to 800℃.

[0039] UV aging resistance test: The aging rating of different epoxy varnish coatings was tested according to GB / T 1766-2008, and the color difference was tested according to GB / T 3181-2008. The varnish of different curing agents was tested by UV aging test using LUV-2 UV accelerated aging test machine of Puxin Testing Instrument (Shanghai) Co., Ltd. During the test, the wavelength of UV light was 313 nm, the temperature was 40℃, and the UV exposure power was 0.06 kW.

[0040] Basic performance test of paint film: The gloss of paint film was tested according to GB / T 9754-2007, the hardness of paint film was tested according to GB / T 6739-2006, the adhesion of paint film was tested according to GB / T 9286-1998, and the impact resistance of paint film was tested according to GB / T 1732-1993.

[0041] Test and characterization of expanded carbon layer structure: Macroscopic analysis of the appearance of the expanded carbon layer was performed using a digital camera, and the internal microstructure of the expanded carbon layer was observed using a JSM-6360LA scanning electron microscope from Japan Electronics. The internal pore size of the carbon layer was analyzed and counted using particle size distribution calculation software Nano Measurer.

[0042] The specific reaction principle of amino polysiloxane is as follows:

[0043]

[0044] Example 1:

[0045] (1) The reaction steps of amino polysiloxane are as follows: 7.2 g of deionized water was added to a three-necked flask equipped with a stirring paddle, and 20.63 g of silane coupling agent KH-602 was slowly added through a constant pressure dropping funnel. After 8 hours of reaction at 55℃, the excess water was removed by rotary evaporation, and 20 g of acetone was used to dissolve the KH-602 oligomer solution. 11.12 g of octamethylcyclotetrasiloxane (D4) and the KH-602 oligomer solution were mixed to obtain a mixed raw material solution. 30% of the mixed raw material solution was added to a four-necked flask, and 0.031 g of tetramethylammonium hydroxide (TMAH) was added. After 30 minutes of reaction under nitrogen atmosphere, the remaining 70% of the mixed raw material solution was slowly added through a constant pressure dropping funnel. After 10-20 hours of reaction, the excess catalyst was decomposed by heating to 120℃, and after 2 hours the solvent was completely removed by rotary evaporation to obtain the amino polysiloxane PPMS-0Ph.

[0046] (2) 6 g of ammonium polyphosphate, 2 g of melamine, 2 g of pentaerythritol, 2 g of titanium white, 3 g of epoxy resin, 1.4 g of xylene, and 0.6 g of n-butanol were mixed and uniformly dispersed using a high-speed dispersion machine at a speed of 1000 r / min for 10 min. To the dispersed slurry, 3 g of the amino polysiloxane PPMS-1Ph obtained in step (1) was added, and the coating was applied to a steel substrate using a brush. The average thickness of the coating sample was maintained at about 2 mm, and was measured using a thickness measuring instrument. The coating was cured at room temperature for 7 days.

[0047] Example 2:

[0048] (1) A three-necked flask equipped with a stirring paddle was charged with 7.2 g of deionized water, and 20.63 g of a silane coupling agent KH-602 was slowly added dropwise using a constant pressure dropping funnel. After reaction at 55°C for 8 hours, the excess water was removed by rotary evaporation, and 20 g of acetone was added to prepare a KH-602 oligomer solution. 6.81 g of trimethyl triphenyl cyclotrisiloxane (D3 Ph ) was dissolved in 7.7 g of xylene, and the D3 Ph solution, 7.42 g of octamethyl cyclotetrasiloxane (D4), and the KH-602 oligomer solution were mixed. 30% of the mixture was added to a four-necked flask, and 0.034 g of tetramethyl ammonium hydroxide (TMAH) was further added. After reaction under a nitrogen atmosphere for 30 minutes, the remaining 70% of the mixture was slowly added dropwise using a constant pressure dropping funnel. After reaction for 10-20 hours, the excess catalyst was decomposed by heating to 120°C, and after 2 hours, the solvent was completely removed by rotary evaporation to obtain an amino polysiloxane PPMS-1Ph.

[0049] (2) 6 g of ammonium polyphosphate, 2 g of melamine, 2 g of pentaerythritol, 2 g of titanium white, 3 g of epoxy resin, 1.4 g of xylene, and 0.6 g of n-butanol were mixed and uniformly dispersed using a high-speed dispersion machine at a speed of 1000 r / min for 10 min. To the dispersed slurry, 3 g of the amino polysiloxane PPMS-1Ph obtained in step (1) was added, and the coating was applied to a steel substrate using a brush. The average thickness of the coating sample was maintained at about 2 mm, and was measured using a thickness measuring instrument. The coating was cured at room temperature for 7 days.

[0050] Example 3:

[0051] (1) A three-necked flask equipped with a stirring paddle was charged with 7.2 g of deionized water, and 20.63 g of a silane coupling agent KH-602 was slowly added dropwise using a constant pressure dropping funnel. After reaction at 55°C for 8 hours, the excess water was removed by rotary evaporation, and 20 g of acetone was added to prepare a KH-602 oligomer solution. 6.81 g of trimethyl triphenyl cyclotrisiloxane (D3 Ph ) was dissolved in 7.7 g of xylene, and the D3 PhThe solution of D4, the KH-602 oligomer solution was mixed, 30% was added to a four-necked flask, 0.038 g of tetramethylammonium hydroxide (TMAH) was added, and the reaction was carried out under a nitrogen atmosphere for 30 minutes. The remaining 70% of the mixed solution was slowly added dropwise using a constant pressure dropping funnel, and the reaction was carried out for 10-20 hours. The excess catalyst was decomposed by heating to 120°C, and after 2 hours, the solvent was evaporated to obtain the aminopolysiloxane PPMS-2Ph.

[0052] (2) 6 g of ammonium polyphosphate, 2 g of melamine, 2 g of pentaerythritol, 2 g of titanium white, 3 g of epoxy resin, 1.4 g of xylene, and 0.6 g of n-butanol were mixed and uniformly dispersed using a high-speed disperser at a speed of 1000 r / min for 10 min. To the obtained slurry, 3 g of the aminopolysiloxane PPMS-2Ph obtained in step (1) was added, and the coating was applied to a steel substrate using a brush. The average thickness of the coating sample was maintained at about 2 mm, and was measured using a thickness measuring instrument. The coating was cured at room temperature for 7 days.

[0053] Example 4:

[0054] (1) 7.2 g of deionized water was added to a three-necked flask equipped with a stirring paddle, and 20.63 g of the silane coupling agent KH-602 was slowly added dropwise using a constant pressure dropping funnel. The reaction was carried out at 55°C for 8 hours, and the excess water was removed by evaporation. 20.43 g of trimethyltriphenylcyclotrisiloxane (D3 Ph ) was dissolved in 23 g of xylene, and the solution of D3 Ph , the KH-602 oligomer solution was mixed, 30% was added to a four-necked flask, 0.041 g of tetramethylammonium hydroxide (TMAH) was added, and the reaction was carried out under a nitrogen atmosphere for 30 minutes. The remaining 70% of the mixed solution was slowly added dropwise using a constant pressure dropping funnel, and the reaction was carried out for 10-20 hours. The excess catalyst was decomposed by heating to 120°C, and after 2 hours, the solvent was evaporated to obtain the aminopolysiloxane PPMS-3Ph.

[0055] (2) 6 g of ammonium polyphosphate, 2 g of melamine, 2 g of pentaerythritol, 2 g of titanium white, 3 g of epoxy resin, 1.4 g of xylene, and 0.6 g of n-butanol were mixed and uniformly dispersed using a high-speed disperser at a speed of 1000 r / min for 10 min. To the obtained slurry, 3 g of the aminopolysiloxane PPMS-3Ph obtained in step (1) was added, and the coating was applied to a steel substrate using a brush. The average thickness of the coating sample was maintained at about 2 mm, and was measured using a thickness measuring instrument. The coating was cured at room temperature for 7 days.

[0056] Example 5:

[0057] (1) In a three-necked flask equipped with a stirring paddle, 7.2 g of deionized water was added, and 20.63 g of silane coupling agent KH-602 was slowly added dropwise using a constant pressure dropping funnel. After reaction at 55°C for 8 hours, the excess water was removed by rotary evaporation, and the product was dissolved in 20 g of acetone for use. 27.24 g of trimethyltriphenylcyclotrisiloxane (D3 Ph ) was dissolved in 30 g of xylene, and the D3 Ph solution, 14.83 g of octamethylcyclotetrasiloxane (D4), and the KH-602 oligomer solution were mixed. 30% of the mixture was added to a four-necked flask, and 0.062 g of tetramethylammonium hydroxide (TMAH) was added. After reaction under a nitrogen atmosphere for 30 minutes, the remaining 70% of the mixture was slowly added dropwise using a constant pressure dropping funnel. After reaction for 10 to 20 hours, the excess catalyst was decomposed by heating to 120°C, and after 2 hours, the solvent was completely removed by rotary evaporation to obtain an aminopolysiloxane PPMS-1NH2.

[0058] (2) 6 g of ammonium polyphosphate, 2 g of melamine, 2 g of pentaerythritol, 2 g of titanium white, 2 g of epoxy resin, 1.4 g of xylene, and 0.6 g of n-butanol were mixed and uniformly dispersed using a high-speed disperser at a rotation speed of 1000 r / min for 10 min. To the obtained slurry, 4 g of the aminopolysiloxane PPMS-1NH2 obtained in step (1) was added, and the coating was applied to a steel substrate using a brush. The average thickness of the coating sample was maintained at about 2 mm, and the thickness was measured using a thickness measuring instrument. The coating was cured at room temperature for 7 days.

[0059] Example 6:

[0060] (1) In a three-necked flask equipped with a stirring paddle, 7.2 g of deionized water was added, and 20.63 g of silane coupling agent KH-602 was slowly added dropwise using a constant pressure dropping funnel. After reaction at 55°C for 8 hours, the excess water was removed by rotary evaporation, and the product was dissolved in 20 g of acetone for use. 27.24 g of trimethyltriphenylcyclotrisiloxane (D3 Ph ) was dissolved in 30 g of xylene, and the D3 Ph solution, KH-602 oligomer solution were mixed, and 30% of the mixture was added to a four-necked flask. Then, 0.029 g of tetramethylammonium hydroxide (TMAH) was added, and after reaction under a nitrogen atmosphere for 30 minutes, the remaining 70% of the mixture was slowly added dropwise using a constant pressure dropping funnel. After reaction for 10 to 20 hours, the excess catalyst was decomposed by heating to 120°C, and after 2 hours, the solvent was completely removed by rotary evaporation to obtain an aminopolysiloxane PPMS-3NH2.

[0061] (2) 6 g of ammonium polyphosphate, 2 g of melamine, 2 g of pentaerythritol, 2 g of titanium white, 3.6 g of epoxy resin, 1.4 g of dimethylbenzene, and 0.6 g of n-butanol were mixed and uniformly dispersed by a high-speed dispersion machine at a speed of 1000 r / min for 10 min. To the slurry obtained by dispersion, 2.4 g of the amino polysiloxane PPMS-3NH2 obtained in step (1) was added, and the coating was applied on a steel substrate by a brush, the average thickness of the coating sample was maintained at about 2 mm, and was measured by a thickness measuring instrument. The coating was cured at room temperature for 7 days.

[0062] Comparative Example 1

[0063] (2) 6 g of ammonium polyphosphate, 2 g of melamine, 2 g of pentaerythritol, 2 g of titanium white, 3.6 g of epoxy resin, 1.4 g of dimethylbenzene, and 0.6 g of n-butanol were mixed and uniformly dispersed by a high-speed dispersion machine at a speed of 1000 r / min for 10 min. To the slurry obtained by dispersion, 2.4 g of the amino polysiloxane PPMS-3NH2 obtained in step (1) was added, and the coating was applied on a steel substrate by a brush, the average thickness of the coating sample was maintained at about 2 mm, and was measured by a thickness measuring instrument. The coating was cured at room temperature for 7 days.

[0064] Table 1

[0065]

[0066]

[0067] Table 2

[0068]

[0069] Table 3

[0070]

[0071] Table 4

[0072]

[0073] Table 5

[0074]

[0075] Figure 1 The nuclear magnetic resonance hydrogen spectrum of the amino polysiloxane PPMS-1Ph in Example 2 is shown in Table 2, which is the theoretical ratio of the side group composition of the polysiloxane and the actual ratio calculated by nuclear magnetic resonance, δ a = 0-0.5 ppm is the peak of -CH3 hydrogen protons of all side groups on the polysiloxane, δ b = 0.5-0.75 ppm is the peak of -CH2 hydrogen protons connected to the silicon atom in the amino side chain on the polysiloxane, δ c=7.2~7.8ppm is the hydrogen proton peak on the benzene ring, δ d =1.5ppm and δe=2.5~3.0ppm are both residual -CH2 hydrogen proton peaks in the amino side chain.

[0076] Figure 2 The glass transition temperatures of epoxy varnishes cured with different formulations of aminopolysiloxane were determined. Examples 1-4 show that increasing the phenyl content in the aminopolysiloxane increases the glass transition temperature of the epoxy varnish. Examples 3, 5, and 6 show that the higher the amount of aminopolysiloxane added, the lower the glass transition temperature of the epoxy resin. By controlling the glass transition temperature of the cured epoxy resin through the structure of the curing agent, and then controlling the deformation capacity of the coating film after heating through the glass transition temperature of the cured epoxy resin, the requirements for char formation and expansion of the intumescent flame retardant system can be maintained.

[0077] Figure 3 Table 3 shows the TGA graphs of different formulations under a nitrogen atmosphere. Figure 2 The data obtained are shown in the figure. It can be seen from the figure that the residual amounts of Examples 1-5 at 800℃ are all higher than 50%, far higher than Comparative Example 1. Example 5 has the highest residual amount at 51.99%, and this high residual amount is more conducive to the formation of the carbon layer in the intumescent fire-retardant coating. The table shows that the T of Example 4... 10％ The highest temperature was 278.8℃.

[0078] Figure 4 Table 3 shows the ultimate fire resistance test curves, with the ultimate fire resistance time defined as the time required for the substrate backing to reach 580°C. As can be seen from the figure, the ultimate fire resistance times of Examples 1-6 are all higher than those of Comparative Example 1, indicating that the fire resistance performance of Examples 1-6 is superior to that of Comparative Example 1. Combined with Table 2, it can be found that Example 2 has the longest fire resistance time, reaching 63.4 min, indicating that Example 2 has the best fire resistance performance, while Comparative Example 1 has the worst. Examples 1, 3, and 5 also exhibit excellent fire resistance performance, with an expansion ratio reaching 14 times. Figure 2 The glass transition temperature of the paint film corresponding to Comparative Example 2 is 46.04℃, which is 21℃ higher than the room temperature of 25℃. It is in a hard glass state at room temperature and has a large free volume after being heated. It has strong deformability and meets the expansion requirements of the expansion flame retardant system. Therefore, the fire retardant coating corresponding to Comparative Example 2 has the longest fire resistance time.

[0079] Figure 5The micro-morphology of carbon layer. Figures a-g are examples 1-6, comparative example 1, respectively. Compared with the carbon layer of comparative example 1, the carbon layer of the fireproof coating prepared with aminopolysiloxane shows better compactness and continuity, in which the carbon layer of example 2 has the best morphology, with small and dense pores, a compact and continuous carbon layer structure greatly isolating the heat transfer to the steel substrate. The carbon layer of comparative example 1 has large and sparse pores, which is not easy to isolate the heat transfer.

[0080] Figure 6 The results of the UV aging resistance of the coating. After 175h of UV aging test, the color difference value ΔE of examples 1 and 5 is already greater than 12, and the paint film has been seriously discolored, the ΔE values of examples 2-4 and 6 are all lower than that of comparative example 1, showing good weather resistance, in which the weather resistance of example 6 is the best, with a ΔE value of only 9.09 after 175h.

[0081] Figure 7 The electrochemical impedance spectrogram of the fireproof coating after 12h of immersion. It can be seen that after 12h of immersion in sodium chloride solution, examples 2 and 3 do not show obvious semicircle trend at high frequency, and the others have shown obvious semicircle capacitive arc, indicating that a new solution / metal interface has been formed under the coating, the electrolyte has penetrated to the metal surface, and the coating protection ability has been seriously reduced. The diameter of the capacitive arc represents the coating resistance, and by fitting and comparing the diameters of the capacitive arcs, it can be found that the coating resistance of comparative example 1 is the lowest, the coating resistances of examples 1, 4-6 are all higher than that of comparative example 1, and the corrosion resistance of the coatings is better than that of comparative example 1.

[0082] Figure 8 The electrochemical impedance spectrogram of the fireproof coating after 24h of immersion. It can be seen that after 24h of immersion in sodium chloride solution, examples 2 and 3 also have semicircle capacitive arcs, but still maintain a relatively high coating resistance, in which examples 1-4 maintain a relatively good coating resistance and corrosion resistance, followed by example 6, and examples 5 and comparative example 1 have a relatively low coating resistance, only 27.35 and 18.16Ω / cm 2 , respectively, and the corrosion resistance of the coating of comparative example 1 is the worst.

Claims

1. The application of an aminopolysiloxane in an epoxy resin-based intumescent fire-retardant coating, characterized in that: The amino polysiloxane is first prepared by hydrolysis of an amino silane coupling agent to obtain side-chain amino silane oligomers, and then the polymerization of trimethyltriphenylcyclotrisiloxane and octamethylcyclotetrasiloxane is initiated to obtain amino polysiloxane with side groups composed of methyl, phenyl and amino groups. The structural formula of aminopolysiloxane is as follows: ； x, y, z represent the proportions of different side chain structural units; in amino polysiloxanes, methyl groups account for 50% to 90% of the total side chain molar percentage, phenyl groups account for 0% to 40% of the total side chain molar percentage, and side chain amino groups account for 10% to 40% of the total side chain molar percentage.

2. The application of the aminopolysiloxane according to claim 1 in epoxy resin-based intumescent fire-retardant coatings, characterized in that: In aminopolysiloxanes, methyl groups account for 60% to 90% of the total side group molar percentage, phenyl groups account for 0% to 20% of the total side group molar percentage, and amino groups in the side chain account for 10% to 20% of the total side group molar percentage.

3. The application of the aminopolysiloxane according to claim 1 in epoxy resin-based intumescent fire-retardant coatings, characterized in that: The preparation steps of aminopolysiloxane are as follows: (1) Add deionized water to the reaction vessel, add aminosilane coupling agent KH-602 dropwise, react at 55 °C for 8 hours, remove excess water by rotary evaporation, dissolve in acetone to obtain KH-602 oligomer solution; (2) Trimethyltriphenylcyclotrisiloxane (D3) Ph D3 was obtained by dissolving in xylene. Ph Solution, D3 Ph A mixed raw material solution was prepared by mixing the solution, octamethylcyclotetrasiloxane (D4), and KH-602 oligomer solution. 30% of the mixed raw material solution was added to a four-necked flask, followed by the addition of tetramethylammonium hydroxide. After reacting under a nitrogen atmosphere for 30 minutes, the remaining 70% of the mixed raw material solution was added dropwise. After reacting for 10-20 hours, the mixture was heated to 120 °C to decompose the excess catalyst. After 2 hours, the solvent was completely evaporated to obtain the final product, aminopolysiloxane.

4. The application of the aminopolysiloxane according to claim 3 in epoxy resin-based intumescent fire-retardant coatings, characterized in that: KH-602, D3 Ph The molar ratio of D4 is 1:(0~0.7):(0~0.7), and the molar ratio of D3 is... Ph D4 cannot be 0 at the same time.

5. The application of the aminopolysiloxane according to claim 3 in epoxy resin-based intumescent fire-retardant coatings, characterized in that: The molar ratio of silane coupling agent KH-602 to deionized water is 1:2 to 1:

4.

6. The application of the aminopolysiloxane according to claim 3 in epoxy resin-based intumescent fire-retardant coatings, characterized in that: The amount of the catalyst tetramethylammonium hydroxide added is 0.05% to 0.1% of the total mass of all monomers.

7. The application of the aminopolysiloxane according to claim 1 in epoxy resin-based intumescent fire-retardant coatings, characterized in that: The epoxy resin-based intumescent fire-retardant coating comprises, by weight, components A and B, wherein component A consists of: 15-18 parts epoxy resin, 25-30 parts ammonium polyphosphate, 10-15 parts melamine, 10-15 parts pentaerythritol, 10-15 parts titanium dioxide, 5-10 parts xylene solvent, and 4-8 parts n-butanol solvent; component B consists of: 12-15 parts amino curing agent; the sum of the weight parts of all components in components A and B is 100 parts; wherein the amino curing agent is the amino polysiloxane described in any one of claims 1-6.

8. The application according to claim 7, characterized in that: The epoxy resin is a bisphenol A diglycidyl ether epoxy resin with an epoxy value of 0.48~0.54 eq / 100g.

9. The application according to claim 7, characterized in that: The preparation method of epoxy resin-based intumescent fireproof coating is as follows: ammonium polyphosphate, melamine, pentaerythritol, titanium dioxide, epoxy resin, xylene solvent, and n-butanol solvent in component A are mixed and dispersed evenly using a high-speed disperser; amino curing agent of component B is added to the dispersed slurry.

10. The application according to claim 7, characterized in that: The amount of amino curing agent added is based on a 1:1 ratio of active hydrogen equivalent to epoxy equivalent.

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