Durable smoke suppression flame retardant and preparation method thereof

Abstract

The invention belongs to the field of functional aids, and particularly relates to a durable smoke suppression flame retardant and a preparation method thereof. The preparation method of the flame retardant comprises the following steps: firstly, adding cyanuric chloride and a solvent into a reaction device together, stirring until cyanuric chloride is completely dissolved, and heating to reflux temperature; dissolving boron spiro with a corresponding molar weight with a solvent, and dropwise adding into the reaction device; after complete reaction, phosphoric acid is diluted with a solvent and dropped into the reaction device, heating, reaction, reduced pressure distillation, washing, purification and drying are performed, and the target flame retardant is obtained. The flame retardant has more reactive groups and forms firmer chemical bond combination with fabric, the washing resistance of the flame retardant is effectively improved, the synergistic effect of the smoke suppression component and the flame retardant component is better, and the smoke suppression performance of the flame retardant is effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of functional additives, and specifically relates to a durable smoke suppression flame retardant and a preparation method thereof. Background Art

[0002] Cotton fabrics are widely used in clothing fabrics, industrial fabrics, home textiles and other special fields due to their excellent moisture absorption and breathability, biocompatibility, wide sources and renewable resource products. However, since cotton fabrics contain more hydrocarbon structures that are easily ignited and cause fires, they need to be flame-retardant to meet their high-value applications in many fields. Phosphorus-containing flame retardants are highly valued in the cotton flame retardant market due to their excellent flame retardancy and durability. Cotton fabrics treated with Proban and Pyrovatex CP flame retardants commonly used in the market have the advantages of being colorless, low strength loss, and high durability in the initial use. However, as the storage time increases, the formaldehyde content will gradually increase, endangering the life and health of users.

[0003] In order to overcome the formaldehyde release problem of durable flame retardants, current advanced research work has pointed out some feasible flame retardant finishing solutions for cotton fabrics, such as the use of polysiloxane coatings, polycarboxylic acid crosslinking, chlorination reagent substitution, etc., but these solutions do not show the effect of inhibiting smoke release. Patent CN118288377A discloses a solution for impregnating wood with diammonium phosphate and nano-silicon dioxide to achieve its flame retardant and smoke suppression effect. The peak heat release rate of the wood prepared by this solution is 460.1KW / m 2 Down to 38.2KW / m 2 , the smoke release volume is 4.36m 2 Down to 1.55m 2 , among which diammonium dihydrogen phosphate is the flame retardant component and silicon dioxide is the main smoke suppression component, but its smoke suppression effect is not significant. Patent CN118257134A discloses a scheme for preparing flame retardant and smoke suppression cotton fabric by impregnating pretreated cotton fabric with zirconium tetrachloride aqueous solution. The LOI value of cotton fabric prepared by this scheme can reach up to 32.7%, and the maximum specific optical density is as low as 22.1. However, heavy metal elements not only pose a threat to human life and health, but some metal flame retardants also use precious rare earth elements, which is inconsistent with the concept of sustainable development. Therefore, it is necessary to provide a flame retardant and a preparation method thereof that has better durability and better smoke suppression while maintaining the mechanical properties of cotton fabrics. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a durable smoke suppression flame retardant and a preparation method thereof, by adding more water-resistant reactive groups and more smoke suppression elements in the molecule, the durability and smoke suppression of the flame retardant are improved, and the invention is green and environmentally friendly, does not release formaldehyde, and the product has high purity.

[0005] The technical solutions adopted are:

[0006] A durable smoke suppression flame retardant, the chemical structure of the durable smoke suppression flame retardant is as follows:

[0007]

[0008] The preparation method of the above-mentioned durable smoke suppression flame retardant comprises the following steps:

[0009] (1) synthesizing borospirocyclic ring by boric acid and pentaerythritol in an organic solvent for later use;

[0010] (2) adding cyanuric chloride and an organic solvent into a reaction apparatus, introducing nitrogen gas and heating to reflux temperature;

[0011] (3) taking another borospiro ring synthesized in step (1), dissolving it in an organic solvent, and adding it to the reaction device in step (2) to react;

[0012] (4) dissolving and diluting phosphoric acid with an organic solvent, adding the solution dropwise to a reaction device, heating the solution to react, and adjusting the pH of the reaction system to 6.5-7.0 with an alkaline substance during the entire reaction process;

[0013] (5) The product obtained in step (4) is subjected to reduced pressure distillation to remove the solvent, and then washed, purified and dried to obtain the product.

[0014] Preferably, in step (1), the molar ratio of boric acid to pentaerythritol is 2-2.3:1; and the organic solvent is any one of toluene, n-hexane, cyclohexane, xylene and benzene.

[0015] Preferably, in the step (1), the boric acid and pentaerythritol are heated to react and stirred under reflux until no more water is generated, and the reaction is terminated; the organic solvent is removed by separation, and the obtained transparent viscous liquid is washed with tetrahydrofuran until it becomes colorless and transparent, and then dried in vacuum.

[0016] Preferably, in step (1), the molar ratio of boric acid to pentaerythritol is 2 to 2.3:1

[0017] Preferably, in step (2), the reflux temperature is the boiling point of the mixed solution in the reaction device, wherein the organic solvent is any one of tetrahydrofuran, ethanol and acetone.

[0018] Preferably, in step (3), the organic solvent is tetrahydrofuran, ethanol or acetone, and the reaction time is 8-12 hours.

[0019] Preferably, in step (2) and step (3), the molar ratio of cyanuric chloride, borospirocyclic ring and phosphoric acid used is 1:3:3.

[0020] Preferably, in step (4), the organic solvent is tetrahydrofuran, ethanol or acetone, and the dropping speed is 1 to 10 drops / min.

[0021] Preferably, in step (4), the heating temperature is 110-130° C., the reaction time is 4-8 hours, and the alkaline substance used is aqueous ammonia.

[0022] Preferably, the solvent used for washing and purification in step (5) is at least one of tetrahydrofuran, dimethyl sulfoxide and acetonitrile.

[0023] Compared with the prior art, the present invention is beneficial in that:

[0024] The durable smoke suppression flame retardant provided by the present invention has more smoke suppression groups and reactive groups as can be seen from the chemical structure. On the one hand, the flame retardant and the fabric produce more chemical connections and are more firmly combined with the fabric, which can effectively improve the water washability of the flame retardant. On the other hand, the excess reactive groups will take effect during combustion, and the flame retardant and smoke suppression effects are also better and more efficient. The preparation method provided by the present invention has the advantages of simple synthesis process, mild conditions, no formaldehyde release, green environmental protection, and high product purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The scanning electron microscope photographs of the carbon residue after burning the durable smoke suppression flame retardant prepared by the present invention on pure cotton fabric, treated cotton fabric and treated cotton;

[0026] Figure 2 is the limiting oxygen index value of the cotton fabric after being treated with the synthetic flame retardant in Example 1 of the present invention;

[0027] Figure 3 The limiting oxygen index test result of the cotton fabric treated with the synthetic flame retardant after washing is shown in the figure. DETAILED DESCRIPTION

[0028] The accompanying drawings are only for illustrative purposes; it should be understood that common knowledge or prior art in the embodiments may be omitted; the cases mentioned below are only used to explain the present invention in order to facilitate the description of the present invention and simplify the description, and therefore, cannot be understood as limiting the present invention.

[0029] The present invention is described in detail below with reference to the embodiments.

[0030] Embodiment 1:

[0031] In a 250mL three-necked flask equipped with an oil-water separator and a spherical condenser, 20.3g of boric acid, 22.4g of pentaerythritol and 40mL of cyclohexane were added, and the mixture was heated, stirred and refluxed until no more water was generated, and the reaction was terminated. The solvent toluene was removed by separation to obtain a transparent viscous liquid, which was thoroughly washed with tetrahydrofuran until colorless and transparent, and vacuum dried at 45°C to obtain 28.2g of a colorless, transparent and viscous liquid, with a yield of about 65.2%. The obtained borospiro ring was used for standby use.

[0032] In a three-necked flask equipped with a thermometer, a magnetic stirrer and a spherical condenser, add 18.44g of cyanuric chloride to 200mL of tetrahydrofuran as a solvent, heat and stir under the protection of nitrogen to dissolve all the cyanuric chloride and heat to the reflux temperature. Take another 2.82g of borospiro ring, dissolve it in tetrahydrofuran and add it to the reaction device, and react for 8h. Take 14.7g of phosphoric acid, dissolve it in tetrahydrofuran and dilute it, then slowly add it dropwise into the reaction device, heat it to 130℃, react for 4h, and use ammonia water to adjust the pH of the reaction system to 6.5 during the whole reaction process. Then, the liquid in the reaction device is distilled under reduced pressure to remove the solvent, and then washed, purified and dried with tetrahydrofuran to obtain a durable smoke suppression flame retardant with a yield of 86.6%.

[0033] Embodiment 2:

[0034] In a 250mL three-necked flask equipped with an oil-water separator and a spherical condenser, 23.4g of boric acid, 22.4g of pentaerythritol and 40mL of xylene were added, and the reaction was terminated when no more water was generated by heating, stirring and refluxing. The solvent toluene was removed by separation to obtain a transparent viscous liquid, which was thoroughly washed with tetrahydrofuran until colorless and transparent, and vacuum dried at 45°C to obtain 28.6g of colorless, transparent and viscous liquid, with a yield of about 64.8%. The obtained borospiro ring was used for standby.

[0035] In a three-necked flask equipped with a thermometer, a magnetic stirrer and a spherical condenser, add 18.44g of cyanuric chloride to 200mL of ethanol as a solvent, heat and stir under the protection of nitrogen to dissolve all the cyanuric chloride and heat to the reflux temperature. Take another 2.82g of borospiro ring, dissolve it in ethanol and add it to the reaction device, and react for 9h. Take 14.7g of phosphoric acid, dissolve it in ethanol and dilute it, then slowly add it dropwise into the reaction device, heat it to 120℃, and react for 5h. During the whole reaction process, use ammonia water to adjust the pH of the reaction system to 7. Subsequently, the liquid in the reaction device is distilled under reduced pressure to remove the solvent, and then washed, purified and dried with dimethyl sulfoxide to obtain a durable smoke suppression flame retardant with a yield of 85.9%.

[0036] Embodiment 3:

[0037] In a 250mL three-necked flask equipped with an oil-water separator and a spherical condenser, 23.4g of boric acid, 22.4g of pentaerythritol and 40mL of benzene were added, and the reaction was terminated when no more water was generated by heating, stirring and refluxing. The solvent toluene was separated to obtain a transparent viscous liquid, which was thoroughly washed with tetrahydrofuran until colorless and transparent, and vacuum dried at 45°C to obtain 28.6g of colorless, transparent and viscous liquid, with a yield of about 65.7%. The obtained borospiro ring was used for standby.

[0038] In a three-necked flask equipped with a thermometer, a magnetic stirrer and a spherical condenser, add 18.44g of cyanuric chloride to 200mL of acetone as a solvent, heat and stir under the protection of nitrogen to dissolve all the cyanuric chloride and heat to the reflux temperature. Take another 2.82g of borospiro ring, dissolve it in acetone and add it to the reaction device, and react for 10 hours. Take 14.7g of phosphoric acid, dissolve it in acetone and dilute it, then slowly add it dropwise into the reaction device, heat it to 120℃, react for 6 hours, and use ammonia water to adjust the pH of the reaction system to 6.8 during the entire reaction process. Subsequently, the liquid in the reaction device is distilled under reduced pressure to remove the solvent, and then washed, purified and dried with tetrahydrofuran to obtain a durable smoke suppression flame retardant with a yield of 85.2%.

[0039] Embodiment 4:

[0040] In a 250mL three-necked flask equipped with an oil-water separator and a spherical condenser, 20.3g of boric acid, 22.4g of pentaerythritol and 40mL of toluene were added, and the reaction was terminated when no more water was generated by heating, stirring and refluxing. The solvent toluene was separated to obtain a transparent viscous liquid, which was thoroughly washed with tetrahydrofuran until colorless and transparent, and vacuum dried at 45°C to obtain 28.2g of colorless, transparent and viscous liquid, with a yield of about 66.0%. The obtained borospiro ring was used for standby.

[0041] In a three-necked flask equipped with a thermometer, a magnetic stirrer and a spherical condenser, add 18.44g of cyanuric chloride to 200mL of tetrahydrofuran as a solvent, heat and stir under the protection of nitrogen to dissolve all the cyanuric chloride and heat to the reflux temperature. Take another 2.82g of borospiro ring, dissolve it in ethanol and add it to the reaction device, and react for 11 hours. Take 14.7g of phosphoric acid, dissolve it in ethanol and dilute it, then slowly add it dropwise into the reaction device, heat it to 110°C, and react for 7 hours. During the entire reaction process, use ammonia water to adjust the pH of the reaction system to 6.6. Subsequently, the liquid in the reaction device is distilled under reduced pressure to remove the solvent, and then washed, purified and dried with acetonitrile to obtain a durable smoke suppression flame retardant with a yield of 76.9%.

[0042] Embodiment 5:

[0043] In a 250mL three-necked flask equipped with an oil-water separator and a spherical condenser, 23.4g of boric acid, 22.4g of pentaerythritol and 40mL of n-hexane were added, and the reaction was terminated when no more water was generated by heating, stirring and refluxing. The solvent toluene was separated to obtain a transparent viscous liquid, which was thoroughly washed with tetrahydrofuran until colorless and transparent, and vacuum dried at 45°C to obtain 28.6g of colorless, transparent and viscous liquid, with a yield of about 62.4%. The obtained borospiro ring was used for standby.

[0044] In a three-necked flask equipped with a thermometer, a magnetic stirrer and a spherical condenser, add 18.44g of cyanuric chloride to 200mL of acetone as a solvent, heat and stir under the protection of nitrogen to dissolve all the cyanuric chloride and heat to the reflux temperature. Take another 2.82g of borospiro ring, dissolve it in acetone and add it to the reaction device, and react for 12 hours. Take 14.7g of phosphoric acid, dissolve it in tetrahydrofuran and dilute it, then slowly add it dropwise into the reaction device, heat it to 110°C, react for 8 hours, and use ammonia water to adjust the pH of the reaction system to 6.9 during the entire reaction process. Subsequently, the liquid in the reaction device is distilled under reduced pressure to remove the solvent, and then washed, purified and dried with acetonitrile to obtain a durable smoke suppression flame retardant with a yield of 78.6%.

[0045] Comparative Example 1: 20.3 g of boric acid, 22.4 g of pentaerythritol and 40 mL of toluene were added to a 250 mL three-necked flask equipped with an oil-water separator and a spherical condenser, and the reaction was terminated when no more water was generated by heating, stirring and refluxing. The solvent toluene was separated to obtain a transparent viscous liquid, which was thoroughly washed with tetrahydrofuran until colorless and transparent, and vacuum dried at 45°C to obtain 28.2 g of a colorless, transparent and viscous liquid, with a yield of about 66.0%, and the obtained borospiro ring was used for standby.

[0046] In a three-necked flask equipped with a thermometer, a magnetic stirrer and a spherical condenser, add 18.44g of cyanuric chloride to 200mL of ethanol as a solvent, heat and stir under the protection of nitrogen to dissolve all the cyanuric chloride and heat to the reflux temperature. Take another 2.82g of borospiro ring, dissolve it in ethanol and add it to the reaction device, and react for 8h. Take 14.7g of phosphoric acid, dissolve it in ethanol and dilute it, then slowly add it dropwise into the reaction device, heat it to 80℃, and react for 4h. During the whole reaction process, use ammonia water to adjust the pH of the reaction system to 6.5. The liquid in the reaction device is then distilled under reduced pressure to remove the solvent, then washed, purified and dried with tetrahydrofuran, and the yield of durable smoke suppression flame retardant is 0.

[0047] The reaction apparatuses in each stage are conventional reaction equipment in actual operation, such as a three-necked flask, etc., and therefore will not be described in detail.

[0048] Comparative Example 2: 23.4 g of boric acid, 22.4 g of pentaerythritol and 40 mL of n-hexane were added to a 250 mL three-necked flask equipped with an oil-water separator and a spherical condenser, and the reaction was terminated when no more water was generated by heating, stirring and refluxing. The solvent toluene was separated to obtain a transparent viscous liquid, which was thoroughly washed with tetrahydrofuran until colorless and transparent, and vacuum dried at 45°C to obtain 28.6 g of colorless, transparent and viscous liquid, with a yield of about 62.4%, and the obtained borospiro ring was used for standby.

[0049] In a three-necked flask equipped with a thermometer, a magnetic stirrer and a spherical condenser, add 18.44g of cyanuric chloride to 200mL of tetrahydrofuran as a solvent, and stir under the protection of nitrogen to dissolve all the cyanuric chloride. Take another 2.82g of borospiro ring, dissolve it in tetrahydrofuran, and add it to the reaction device for 9h. Take 14.7g of phosphoric acid, dissolve it in tetrahydrofuran, and then slowly add it dropwise into the reaction device, heat it to 120℃, and react for 5h. During the whole reaction process, use ammonia water to adjust the pH of the reaction system to 7. Subsequently, the liquid in the reaction device is distilled under reduced pressure to remove the solvent, and then washed, purified and dried with dimethyl sulfoxide. The yield of durable smoke suppression flame retardant is 30%.

[0050] like Figure 1 As shown, the picture on the left is a scanning electron microscope photo of pure cotton fabric, the picture in the middle is a scanning electron microscope photo of cotton fabric treated with flame retardant, and the picture on the right is a scanning electron microscope photo of the carbon residue after combustion of treated cotton fabric. As can be seen from the figure, the cotton fabric has a regular structure, the fiber surface is smooth, there are natural distortions and cracks, and the microfibril structure can be observed after magnification. The structure of the fabric after finishing is regular and orderly, there is a layer of film-like substance on the fiber surface, and there is a crystalline substance attached to the outer layer. After magnification, it can be observed that the original microfibril structure of the fiber is covered, indicating that the flame retardant has been successfully finished on the surface of the cotton fabric. After burning, the finished fabric retains complete and continuous carbon residue, the fabric weaving structure is not destroyed, and no obvious crystals and air chambers appear on the surface of the carbon residue. However, pure cotton fabric leaves almost no carbon residue after burning. The results show that the use of the flame retardant significantly improves the carbon-forming performance of the fabric.

[0051] like Figure 2 As shown, the limiting oxygen index test results of cotton fabric after finishing with the synthetic flame retardant in Example 1 are shown. The LOI value of the fabric before finishing is about 18.0%, and it is very easy to burn in the atmospheric environment. When the weight gain rate after finishing is 9.8%, the LOI value of the fabric increases to 31.5%, and it can achieve self-extinguishing in the air, reaching the standard of flame-retardant fabric. Continuing to increase the concentration of the flame retardant, the LOI value of the fabric continues to increase. When the weight gain rate reaches 29.9%, the LOI value of the fabric reaches 49.0%. The flame retardant involved in the present invention has a good flame retardant effect on cotton fabrics, and the added amount is small, and the flame retardant efficiency is high.

[0052] like Figure 3 As shown, the limiting oxygen index test results of flame-retardant cotton fabrics with different weight gain rates after washing and scanning electron microscope photos of the washed fabrics. The synthetic flame retardant-finished cotton fabric was placed in a 250ml conical flask, and then 200ml of water containing 0.15wt% was added. The conical flask was placed in an 80rpm oscillating water bath at a temperature of 48°C, and 45min was defined as 5 washing cycles. When the washing cycle was 10 times, the LOI value decreased compared with the unwashed flame retardant-finished cotton fabric. This is because some flame retardants agglomerated on the fiber surface and did not react with cotton. After washing, these agglomerates disappeared, resulting in a decrease in the flame retardant properties of the synthetic flame retardant-finished cotton fabric. After 50 washing cycles, the LOI value of the synthetic flame retardant-finished cotton fabric was not significantly different from that of 10 washings. They decreased by 2.4%, 4.5% and 3.0% respectively. The flame retardant involved in the present invention has better flame retardant durability for cotton fabrics.

[0053] Those skilled in the art will appreciate that the experimental examples shown here are intended to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other variations that do not deviate from the essence of the present invention based on the technical revelations disclosed in the present invention, and these variations are still within the protection scope of the present invention.

Claims

1. A durable smoke suppression flame retardant, characterized in that: The chemical structure of the durable smoke suppression flame retardant is as follows:

2. The method for preparing a durable smoke suppression flame retardant according to claim 1, characterized in that: The synthesis steps are as follows: (1) synthesizing borospirocyclic ring by boric acid and pentaerythritol in an organic solvent for later use; (2) adding cyanuric chloride and an organic solvent into a reaction apparatus, introducing nitrogen gas and heating to reflux temperature; (3) taking another borospiro ring synthesized in step (1), dissolving it in an organic solvent, and adding it to the reaction device in step (2) to react; (4) dissolving and diluting phosphoric acid with an organic solvent, adding the solution dropwise to a reaction device, heating the solution to react, and adjusting the pH of the reaction system to 6.5-7.0 with an alkaline substance during the entire reaction process; (5) The product obtained in step (4) is subjected to reduced pressure distillation to remove the solvent, and then washed, purified and dried to obtain the product.

3. The method for preparing a durable smoke suppression flame retardant according to claim 2, characterized in that: In the step (1), the molar ratio of boric acid to pentaerythritol is 2-2.3:1; and the organic solvent is any one of toluene, n-hexane, cyclohexane, xylene, and benzene.

4. The method for preparing a durable smoke suppression flame retardant according to claim 2, characterized in that: In the step (1), boric acid and pentaerythritol are heated to react and stirred under reflux until no more water is generated, and the reaction is terminated; the organic solvent is removed by separation, and the obtained transparent viscous liquid is washed with tetrahydrofuran until it becomes colorless and transparent, and then dried in vacuum.

5. The method for preparing a durable smoke suppression flame retardant according to claim 2, characterized in that: In the step (2), the reflux temperature is the boiling point of the mixed solution in the reaction device, wherein the organic solvent is any one of tetrahydrofuran, ethanol and acetone.

6. The method for preparing a durable smoke suppression flame retardant according to claim 2, characterized in that: In the step (3), the organic solvent is tetrahydrofuran, ethanol, or acetone, and the reaction time is 8-12 hours.

7. The method for preparing a durable smoke suppression flame retardant according to claim 2, characterized in that: In step (2) and step (3), the molar ratio of cyanuric chloride, borospirocyclic ring and phosphoric acid used is 1:3:

3.

8. The method for preparing a durable smoke suppression flame retardant according to claim 2, characterized in that: In the step (4), the organic solvent is tetrahydrofuran, ethanol, or acetone, and the dropping speed is 1 to 10 drops / min.

9. The method for preparing a durable smoke suppression flame retardant according to claim 8, characterized in that: The heating temperature is 110-130°C, the reaction time is 4-8h; the alkaline substance used is ammonia water.

10. The method for preparing a durable smoke suppression flame retardant according to claim 2, characterized in that: The solvent used for washing and purification in step (5) is at least one of tetrahydrofuran, dimethyl sulfoxide and acetonitrile.

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