Flame retardants for fire-retardant coatings and their preparation methods

Abstract

This application provides a fire retardant for fire-retardant coatings and its preparation method. The method includes the following steps: (1) Heating step of long-chain paraffin: adding carbon chain C18-C25 paraffin into a reaction vessel and heating it to 85-90℃; (2) Chlorination reaction step: passing chlorine gas into the reaction vessel to carry out the chlorination reaction, and controlling the flow rate of the introduced chlorine gas in a gradient manner, with the chlorine gas flow rate being 1.2t / h for the first 8 hours and 1t / h for the next 7 hours, and the reaction time being 15 hours. After the reaction is completed, a stabilizer is added to the reaction vessel; (3) Water washing and neutralization step: transferring the reaction liquid to a water washing vessel, washing the reaction liquid with water, and then neutralizing it with a neutralizing agent, filtering, and drying to obtain the fire retardant for fire-retardant coatings. This application uses gradient flow control to make the flame retardant more uniform in color, higher in whiteness, and better in stability, and the whiteness of the product reaches more than 80, which meets the high requirements of the coating industry for color stability.

Description

Technical Field

[0001] This application relates to the field of flame retardant materials technology, and in particular to a flame retardant for fireproof coatings and its preparation method. Background Technology

[0002] With increasing societal emphasis on fire safety, fire-retardant coatings, as special coatings that effectively reduce the flammability of materials, inhibit the spread of fire, and improve the fire resistance of materials, have been widely used in various fields such as construction, transportation, and power. Fire-retardant coatings not only protect people's lives and property but also reduce economic losses caused by fires, thus possessing significant social and economic value.

[0003] Currently, halogenated flame retardants (especially bromine-based and chlorine-based flame retardants) have become the most widely produced and used type of flame retardant globally due to their high flame retardant efficiency, wide range of applications, high thermal stability, and low water solubility. Among them, chlorinated paraffin, as a typical chlorine-based flame retardant, is highly favored by the coatings industry due to its low addition amount, good flame retardant effect, and minimal impact on material processing, mechanical, and electrochemical properties. However, the market's performance requirements for fire-retardant coatings and their flame retardants are increasingly demanding, requiring higher standards not only in terms of basic flame retardant properties but also in terms of stability, color, and odor. Therefore, developing high-performance, high-stability halogenated flame retardants for fire-retardant coatings has become an important issue for the industry. Summary of the Invention

[0004] This application provides a fire-retardant coating flame retardant and its preparation method to solve the problems mentioned in the background art.

[0005] In a first aspect, this application provides a method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: (1) Heating steps for long-chain paraffin: Add carbon chain C18-C25 paraffin to the reactor and heat to 85-90℃; (2) Chlorination reaction steps: Chlorine gas is introduced into the reactor to carry out the chlorination reaction. The flow rate of the introduced chlorine gas is controlled by gradient. The flow rate of chlorine gas is 1.2t / h for the first 8 hours and 1t / h for the next 7 hours. The reaction time is 15 hours. After the reaction is completed, a stabilizer is added to the reactor. (3) Water washing and neutralization step: Transfer the reaction solution to a water washing kettle, wash the reaction solution with water, then neutralize it with a neutralizing agent, filter and dry to obtain the fire retardant coating.

[0006] Optionally, the weight ratio of carbon chain C18-C25 paraffin to chlorine is 5:1.

[0007] Optionally, the temperature of the chlorination reaction can be controlled as follows: 70-90℃ for the first 8-9 hours and 90-120℃ for the next 6-7 hours.

[0008] Optionally, the neutralizing agent may be selected from calcium carbonate or sodium bicarbonate.

[0009] The amount of stabilizer added is 0.01-0.05 wt% of paraffin.

[0010] The stabilizer comprises the following components by weight percentage: 70 wt% glyceryl ether, 5 wt% UV absorber, 20 wt% triphenyl phosphite, and 5 wt% antioxidant (based on 100% stabilizer).

[0011] Optionally, in the water washing and neutralization step, the amount of water added for washing is 20-30 wt% of the reaction solution.

[0012] Optionally, in the water washing and neutralization step, the amount of neutralizing agent added is 5-6 wt% of the reaction solution.

[0013] Secondly, this application provides a fire-retardant coating flame retardant, which is obtained by the above-described preparation method.

[0014] Optionally, the chlorine content in the flame retardant of the fire-retardant coating is 68%-72%.

[0015] The fire-retardant for fire-retardant coatings and its preparation method provided in this application realize the preparation of fire-retardant for fire-retardant coatings, and have the following beneficial effects compared with the prior art: (1) This application uses long-chain C18-C25 paraffin as the substrate for the chlorination reaction, which is beneficial for the flame retardant obtained after the chlorination reaction to have a moderate melting point and viscosity, ensuring the stability of the flame retardant at the coating processing temperature and good compatibility with the coating matrix. Gradient flow control is adopted to control the chlorine flow rate and reaction time. The high flow rate in the early stage promotes the reaction rate, and the low flow rate in the later stage prevents over-chlorination. This innovative technology significantly improves the utilization rate of chlorine, reduces the generation of the chromogenic gene -CH=CH- in the side reaction, ensures the stability of the product color, and reduces tail gas emissions and the occurrence of side reactions. Gradient flow control technology helps to achieve uniform chlorine distribution in the reactor, thereby ensuring the stability of product quality. The use of gradient flow control makes the final product more uniform in color and whiter after water washing and neutralization, with no obvious odor, and the whiteness of the product reaches above 80, meeting the high requirements of the coating industry for color stability.

[0016] (2) The fire retardant provided in this application has the characteristics of having no obvious odor, stable white color and whiteness of 80 or above, while ensuring the flame retardant efficiency and application range of the product, so that it can be widely used in various decorative fire retardant coatings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a physical image of the fire-retardant coating provided in Embodiment 3 of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0020] In a first aspect, this application provides a method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: (1) Heating steps for long-chain paraffin: Add carbon chain C18-C25 paraffin to the reactor and heat to 85-90℃; (2) Chlorination reaction steps: Chlorine gas is introduced into the reactor to carry out the chlorination reaction. The flow rate of the introduced chlorine gas is controlled by gradient. The flow rate of chlorine gas is 1.2t / h for the first 8 hours and 1t / h for the next 7 hours. The reaction time is 15 hours. After the reaction is completed, a stabilizer is added to the reactor. (3) Water washing and neutralization step: Transfer the reaction solution to a water washing kettle, wash the reaction solution with water, then neutralize it with a neutralizing agent, filter and dry to obtain the fire retardant coating.

[0021] Specifically, this application uses paraffin with a carbon chain of C18-C25 as the substrate for the chlorination reaction. Its moderate molecular weight and carbon chain length are beneficial for the flame retardant obtained after the chlorination reaction to have a suitable melting point and viscosity, ensuring both the stability of the flame retardant at the coating processing temperature and good compatibility with the coating matrix. If the carbon chain is too short, the resulting chlorinated paraffin has poor thermal stability, leading to a decrease in flame retardant efficiency. If the carbon chain is too long (above C25), the resulting chlorinated paraffin has an excessively high melting point and viscosity, resulting in poor compatibility with the coating resin when added to the coating, affecting the leveling and film-forming properties of the coating. Before the reaction, the paraffin is heated to 85-90℃ to completely melt it. The lower viscosity of the liquid paraffin facilitates the uniform dispersion and diffusion of chlorine gas, improving gas-liquid contact efficiency and ensuring the uniformity of the chlorination reaction.

[0022] Chlorine gas is introduced into paraffin to carry out a chlorination reaction. The chlorination reaction is a free radical substitution reaction, which is exothermic and causes the temperature in the reaction vessel to rise. In this application, a cooling device is installed on the reaction vessel during the chlorination reaction to control the reaction temperature, making full use of the exothermic reaction. No additional heating is required during the reaction, ensuring the stable progress of the chlorination reaction.

[0023] Furthermore, during the chlorination reaction, since the reaction is exothermic, the reaction temperature will fluctuate dynamically. The process of controlling the reaction temperature in this application is a prior art well known to those skilled in the art. For example, when heating, a heat exchange medium (hot water, steam, heat transfer oil, etc.) can be introduced into the jacket or coil. If cooling is required during the reaction, cooling water or low-temperature fluid can be introduced into the jacket or coil to cool the reactor. Alternatively, a high-low temperature integrated heating and cooling unit can be used to control the temperature during the heat preservation reaction process. The above-mentioned operations for temperature control of the chlorination reactor are all prior art, and those skilled in the art can adjust them according to the actual working conditions, so they will not be elaborated here.

[0024] Simultaneously, a gradient flow rate control was implemented for chlorine gas. The flow rate was 1.2 t / h for the first 8 hours and 1 t / h for the following 7 hours. The chlorine flow rate affected the gas-liquid phase mass transfer rate and the uniformity of chlorine distribution within the reactor. In the initial stage of the reaction, the paraffin raw material had a high hydrogen atom concentration and abundant active sites, resulting in favorable reaction kinetics. At this point, a higher chlorine flow rate (1.2 t / h) was used to fully utilize the high reactivity of the raw material and quickly establish a stable free radical chain reaction system. As the reaction progressed, the number of easily substituted hydrogen atoms in the paraffin molecules gradually decreased, leaving mostly less reactive primary hydrogen atoms or sites with significant steric hindrance. Reducing the chlorine flow rate to 1.0 t / h at this stage prevented the accumulation of excessive chlorine in the reaction system and facilitated deeper chlorination, resulting in a more uniform distribution of chlorine atoms on the paraffin molecular chains and preventing localized over-chlorination. This also reduced the content of unreacted chlorine in the tail gas, lowered the tail gas treatment load, and improved chlorine utilization.

[0025] This innovative technology, which promotes the reaction with a high flow rate in the early stage and prevents over-chlorination with a low flow rate in the later stage, significantly improves chlorine utilization while reducing tail gas emissions and side reactions. Gradient flow control technology helps achieve uniform chlorine distribution within the reactor, thus ensuring product quality stability. Products produced using gradient flow control have more uniform color and higher whiteness; light-colored or white powdered chlorinated paraffin flame retardants do not interfere with the base color of coatings, which is particularly beneficial for color matching in light-colored coatings. When the overall chlorine flow rate is controlled at 1 t / h, the flow rate is too low, resulting in poor chlorine dispersion and insufficient chlorine supply in some areas, leading to uneven reaction. Some paraffin molecules are underchlorinated (pale yellow), while some areas experience over-chlorination due to chlorine accumulation (generating colored substances), resulting in uneven product color and decreased whiteness. Conversely, excessively high flow rates lead to excessively large bubbles or short residence times, resulting in low chlorine utilization. Furthermore, vigorous agitation exacerbates the contact between the material and oxygen in the air, inducing oxidation side reactions and generating dark impurities such as quinones, causing the product to turn yellow. In addition, high flow rates increase tail chlorine emissions; if the tail gas is not properly treated, the workshop environment will have a strong odor. Peroxides produced by localized oxidation decompose into aldehydes and ketones, resulting in an unpleasant odor.

[0026] The reaction time must ensure complete chlorination while avoiding ineffective extension that could induce side reactions. If the reaction time is less than 15 hours, the reaction will be incomplete, leaving unchlorinated alkanes (yellow oily residue), and the product will be yellowish with low whiteness. Conversely, if the reaction time is too long, under high temperature and the presence of chlorine, the C-Cl bond may break, leading to dechlorination or oxidation, generating conjugated polyenes (chromophores) that deepen the color (from light yellow to brownish-yellow), and drastically reduce whiteness. Furthermore, extending the reaction time intensifies thermal decomposition, releasing more HCl and small-molecule chlorinated hydrocarbons (chloromethane), producing a strong, pungent odor. Residual solvent may also generate sulfides with an unpleasant odor due to prolonged heating.

[0027] After the chlorination reaction, the product may contain small amounts of active chlorine, peroxides, or unstable structures (such as allyl chloride, tertiary carbon chloride, etc.). These structures are easily decomposed during storage or heating, releasing hydrogen chloride, leading to increased acidity, darker color, and decreased molecular weight. Adding stabilizers can react with these unstable groups, neutralize acidic substances, capture free radicals, and inhibit the dehydrochlorination reaction. Water-soluble impurities (mainly HCl and some chlorine) are transferred from the organic phase (chlorinated paraffin) to the aqueous phase by washing. HCl is highly soluble in water, forming a hydrochloric acid solution, which separates from the chlorinated paraffin product. The neutralizing agent removes acidic substances from the product, improving the stability and safety of the flame retardant.

[0028] The above scheme achieves the preparation of flame retardants for fire-retardant coatings. This application uses long-chain C18-C25 paraffin as the substrate for the chlorination reaction, which is beneficial for the flame retardant obtained after the chlorination reaction to have a suitable melting point and viscosity. This ensures the stability of the flame retardant at the coating processing temperature and good compatibility with the coating matrix. Gradient flow control of chlorine flow rate and reaction time is employed. High flow rate in the early stage promotes the reaction rate, while low flow rate in the later stage prevents over-chlorination. This innovative technology significantly improves chlorine utilization, reduces the generation of chromogenic genes (—CH=CH—) in the side reaction, ensures product color stability, and reduces exhaust emissions and side reactions. Gradient flow control technology helps to achieve uniform chlorine distribution within the reactor, thereby ensuring product quality stability. The gradient flow control results in a more uniform color and higher whiteness of the final product after water washing and neutralization, with no obvious odor, and a whiteness of over 80, meeting the high requirements of the coating industry for color stability.

[0029] Optionally, the weight ratio of carbon chain C18-C25 paraffin to chlorine is 5:1.

[0030] Specifically, the amount of paraffin added directly affects the total amount of chlorine absorbed and the molecular structure of the product. Under a reasonable chlorine flow rate, fully chlorinated paraffin molecules are saturated, and the flame retardant tends to be white. When the amount of paraffin is too high and the amount of chlorine is relatively insufficient, it will lead to incomplete chlorination, leaving unreacted alkanes or generating low-chlorinated compounds (chlorine content <50%). These low-chlorinated compounds are mostly pale yellow oily liquids, which, when mixed into the product, will significantly reduce the whiteness of the flame retardant and give it a yellowish tint. In addition, unreacted paraffin or low-chlorinated paraffin carries an alkane odor and is more volatile due to its low molecular weight, resulting in a "waxy" or solvent-like smell in the final product.

[0031] The total amount of chlorine gas introduced determines the chlorine content of the final product, which is a core control factor for the product's flame retardancy rating and appearance. When the chlorine gas introduction is too low, the flame retardant has a low chlorine content, fewer C-Cl bonds in its molecular structure, weak molecular polarity, and is difficult to crystallize, appearing as a pale yellow viscous liquid rather than a white powder, with a significant decrease in whiteness. When the chlorine gas introduction is too high, excessive chlorine leads to over-chlorination, inducing a deHCl reaction to generate double bonds (olefins). Compounds containing double bonds are easily oxidized to aldehydes, ketones, and other colored substances (yellow → brown), and catalyze further degradation, causing the flame retardant product to darken in color and deteriorate in whiteness. If the hydrogen chloride produced by the deHCl side reaction is not removed in time, it will dissolve to form hydrochloric acid, corroding equipment and introducing metal ions (such as Fe). 3+ Excessive chlorination catalyzes oxidation and produces a pungent sour taste. Furthermore, the olefins formed by excessive chlorination are easily oxidized into short-chain carboxylic acids and aldehydes, resulting in rancidity or a pungent odor.

[0032] Optionally, in the chlorination reaction step, the introduced chlorine gas is controlled by a gradient flow rate, specifically: the chlorine gas flow rate is 1.2 t / h for the first 8 hours and 1 t / h for the next 7 hours.

[0033] Optionally, the temperature of the chlorination reaction can be controlled as follows: 70-90℃ for the first 8-9 hours and 90-120℃ for the next 6-7 hours.

[0034] Specifically, a lower temperature is used in the initial stage of the reaction to avoid an increase in side reactions; the temperature is appropriately increased in the later stage to promote the reaction. Excessive temperature will accelerate side reactions, such as the formation of unsaturated bonds and the production of colored substances, leading to a darker product color. At the same time, excessively high temperatures may also promote thermal decomposition reactions, releasing more small-molecule chlorinated hydrocarbons and HCl, producing an irritating odor. On the other hand, if the initial temperature is too low, the reaction may be incomplete, leaving unreacted raw materials or intermediates, which will also affect the color and whiteness of the product.

[0035] Optionally, the neutralizing agent may be selected from calcium carbonate or sodium bicarbonate.

[0036] Optionally, the amount of stabilizer added is 0.01-0.05 wt% of paraffin.

[0037] The stabilizer comprises the following components by weight percentage: 70 wt% glyceryl ether, 5 wt% UV absorber, 20 wt% triphenyl phosphite, and 5 wt% antioxidant (based on 100% stabilizer).

[0038] Optionally, in the water washing and neutralization step, the amount of water added for washing is 20-30 wt% of the reaction solution.

[0039] Optionally, in the water washing and neutralization step, the amount of neutralizing agent added is 5-6 wt% of the reaction solution.

[0040] Specifically, the water washing and neutralization step can remove residual acidic substances and impurities from chlorinated paraffin flame retardants, making the flame retardant more stable.

[0041] Secondly, this application provides a fire-retardant coating flame retardant, which is obtained by the above-described preparation method.

[0042] Optionally, the chlorine content in the flame retardant of the fire-retardant coating is 68%-72%.

[0043] The following are embodiments and effect test examples of this application, further describing the technical solution and technical effects of the present invention. However, the scope of protection of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not depart from the concept of the present invention are within the scope of protection of the present invention. Furthermore, for those embodiments where specific technical operation steps or conditions are not specified, they are performed according to the techniques or conditions described in general literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products. Example 1

[0044] A method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: (1) Heating steps for long-chain paraffin: Add 2t of carbon chain C18-C25 paraffin to the reactor and heat to 85℃; (2) Chlorination reaction steps: Chlorine gas is introduced into the reactor to carry out the chlorination reaction. The flow rate of the introduced chlorine gas is controlled by gradient. The flow rate of chlorine gas is 1.2t / h for the first 8 hours and 1t / h for the next 7 hours. The reaction time is 15 hours. After the reaction is completed, a stabilizer is added to the reactor.

[0045] The temperature control for the chlorination reaction is as follows: 70-75℃ for the first 9 hours and 90-100℃ for the last 6 hours.

[0046] (3) Water washing and neutralization step: Transfer the reaction solution to a water washing kettle, wash the reaction solution with water, and then neutralize it with sodium bicarbonate as a neutralizing agent. Filter and dry to obtain the fire retardant for fireproof coating. The chlorine content in the fire retardant is 68%.

[0047] The amount of water added for washing is 20 wt% of the reaction solution, and the amount of sodium bicarbonate added is 5 wt% of the reaction solution. Example 2

[0048] A method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: (1) Heating steps for long-chain paraffin: Add 2t of carbon chain C18-C25 paraffin to the reactor and heat to 90℃; (2) Chlorination reaction steps: Chlorine gas is introduced into the reactor to carry out the chlorination reaction. The flow rate of the introduced chlorine gas is controlled by gradient. The flow rate of chlorine gas is 1.2t / h for the first 8 hours and 1t / h for the next 7 hours. The reaction time is 15 hours. After the reaction is completed, a stabilizer is added to the reactor.

[0049] The temperature control for the chlorination reaction is as follows: 75-80℃ for the first 9 hours and 115-120℃ for the last 6 hours.

[0050] (3) Water washing and neutralization step: Transfer the reaction solution to a water washing kettle, wash the reaction solution with water, and then neutralize it with sodium bicarbonate as a neutralizing agent. Filter and dry to obtain the fire retardant for fireproof coating. The chlorine content in the fire retardant is 70%.

[0051] The amount of water added for washing is 25 wt% of the reaction solution, and the amount of sodium bicarbonate added is 6 wt% of the reaction solution. Example 3

[0052] A method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: (1) Heating steps for long-chain paraffin: Add 3t of carbon chain C18-C25 paraffin to the reactor and heat to 90℃; (2) Chlorination reaction steps: Chlorine gas is introduced into the reactor to carry out the chlorination reaction. The flow rate of the introduced chlorine gas is controlled by gradient. The flow rate of chlorine gas is 1.2t / h for the first 8 hours and 1t / h for the next 7 hours. The reaction time is 15 hours. After the reaction is completed, a stabilizer is added to the reactor.

[0053] The temperature control for the chlorination reaction is as follows: 80-85℃ for the first 9 hours and 115-120℃ for the last 6 hours.

[0054] (3) Water washing and neutralization step: Transfer the reaction solution to a water washing tank, wash the reaction solution with water, then neutralize it with sodium bicarbonate as a neutralizing agent, filter and dry to obtain the fire retardant coating (e.g. Figure 1 As shown in the figure, the chlorine content in the flame retardant of the fireproof coating is 72%.

[0055] The amount of water added for washing is 30 wt% of the reaction solution, and the amount of sodium bicarbonate added is 6 wt% of the reaction solution. Example 4

[0056] A method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: (1) Heating steps for long-chain paraffin: Add 2t of carbon chain C18-C25 paraffin to the reactor and heat to 90℃; (2) Chlorination reaction steps: Chlorine gas is introduced into the reactor to carry out the chlorination reaction. The flow rate of the introduced chlorine gas is controlled by gradient. The flow rate of chlorine gas is 1.2t / h for the first 8 hours and 1t / h for the next 7 hours. The reaction time is 15 hours. After the reaction is completed, a stabilizer is added to the reactor.

[0057] The temperature control for the chlorination reaction is as follows: 85-90℃ for the first 8 hours and 100-115℃ for the next 7 hours.

[0058] (3) Water washing and neutralization step: Transfer the reaction solution to a water washing kettle, wash the reaction solution with water, and then neutralize it with sodium bicarbonate as a neutralizing agent. Filter and dry to obtain the fire retardant for fireproof coating. The chlorine content in the fire retardant is 69%.

[0059] The amount of water added for washing is 20 wt% of the reaction solution, and the amount of sodium bicarbonate added is 5 wt% of the reaction solution.

[0060] Comparative Example 1 A method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: The difference from Example 3 is that: (2) Chlorination reaction steps: The chlorine gas was introduced with gradient flow control: the chlorine gas flow rate was 1.2 t / h for the first 7 hours and 1 t / h for the next 8 hours.

[0061] Comparative Example 2 A method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: The difference from Example 3 is that: (2) Chlorination reaction steps: The flow rate of chlorine gas introduced is always controlled at 1t / h.

[0062] Comparative Example 3 A method for preparing a flame retardant for fire-retardant coatings, the method comprising the following steps: The difference from Example 3 is that: (2) Chlorination reaction steps: The temperature for the chlorination reaction is controlled at 100-110℃.

[0063] Experimental Example 1 Flame retardants for fire-retardant coatings were synthesized in Examples 1-4. The color, odor, and whiteness of the flame retardants provided in Examples 1-4 and Comparative Examples 1-3 were tested. Visual observation and colorimeter measurement were used to assess whether the product color was consistently white. The presence of a noticeable odor was determined by smell. The whiteness value of the product was measured using a whiteness meter. The results are shown in Table 1.

[0064] Table 1

[0065] As can be clearly seen from Table 1, the flame retardants provided in Examples 1-4 are significantly superior to those in Comparative Examples 1-3. In these examples, the chlorine flow rate, reaction temperature, and reaction time were controlled by gradient flow rate. The high flow rate in the early stage promoted the reaction rate, while the low flow rate in the later stage prevented over-chlorination. At the same time, the temperature control before and after the reaction not only made the reaction efficient, but also significantly improved the utilization rate of chlorine, reduced the generation of the chromogenic gene -CH=CH- in the side reaction, ensured the stability of the product color, and reduced exhaust emissions and side reactions, thereby ensuring the stability of product quality. The final product has a more uniform color, higher whiteness, no obvious odor, and a whiteness of over 80, meeting the high requirements of the coating industry for color stability.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a flame retardant for fire-retardant coatings, characterized in that, The method includes the following steps: (1) Heating steps for long-chain paraffin: Add carbon chain C18-C25 paraffin to the reactor and heat to 85-90℃; (2) Chlorination reaction steps: Chlorine gas is introduced into the reactor to carry out the chlorination reaction. The chlorine gas is controlled by gradient flow. The chlorine gas flow rate is 1.2t / h for the first 8 hours and 1t / h for the next 7 hours. The reaction time is 15 hours. After the reaction is completed, a stabilizer is added to the reactor. (3) Water washing and neutralization step: Transfer the reaction solution to a water washing tank, wash the reaction solution with water, then neutralize it with a neutralizing agent, filter and dry to obtain the fire retardant of the fireproof coating.

2. The method for preparing the flame retardant of the fire-retardant coating according to claim 1, characterized in that, The weight ratio of the paraffin wax (carbon chain C18-C25) to the chlorine gas is 5:

1.

3. The method for preparing the fire-retardant coating flame retardant according to claim 1, characterized in that, The temperature control of the chlorination reaction is as follows: the chlorination reaction temperature is 70-90℃ for the first 8-9 hours and 90-120℃ for the last 6-7 hours.

4. The method for preparing the flame retardant of the fire-retardant coating according to claim 1, characterized in that, The amount of stabilizer added is 0.01-0.05 wt% of the paraffin.

5. The method for preparing the flame retardant of the fire-retardant coating according to claim 4, characterized in that, The stabilizer comprises the following components by weight percentage: 70 wt% glyceryl ether, 5 wt% UV absorber, 20 wt% triphenyl phosphite, and 5 wt% antioxidant.

6. The method for preparing the flame retardant of the fire-retardant coating according to claim 1, characterized in that, In the water washing and neutralization step, the amount of water added for washing is 20-30 wt% of the reaction solution.

7. The method for preparing the flame retardant of the fire-retardant coating according to claim 1, characterized in that, The neutralizing agent is selected from calcium carbonate or sodium bicarbonate.

8. The method for preparing the flame retardant of the fire-retardant coating according to claim 7, characterized in that, In the water washing and neutralization step, the amount of neutralizing agent added is 5-6 wt% of the reaction solution.

9. A flame retardant for fire-retardant coatings, characterized in that, It is obtained by the preparation method described in any one of claims 1-8.

10. The fire-retardant coating flame retardant according to claim 9, characterized in that, The chlorine content in the flame retardant of the fireproof coating is 68%-72%.

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