Synthesis and application of triazine derivative flame retardant
Technical Field
The invention relates to the technical field of flame retardant material preparation, in particular to preparation of a novel triazine derivative flame retardant material based on cyanuric chloride and DOPO structures and application of the flame retardant material in various flame-retardant base materials, especially application in cotton textiles.
Background
With the widespread use of polymers, fire safety is becoming an increasing concern. Many safety testing organizations, including the Underwriters Laboratories (UL), the international organization for standardization (ISO), and the American Society for Testing and Materials (ASTM), have promulgated various types of standard standards that define the flame retardant properties required of a polymer in a given classification.
Most commercial textiles are too flammable, cotton fiber is one of the most commonly used textile raw materials, the limited oxygen index of the cotton fiber is only 18%, and the cotton fiber is extremely easy to burn, so that fire hazards are caused to the safety of human life and property, and therefore, the cotton fiber has to be subjected to flame retardant finishing to improve the fire resistance. The flame retardant materials applied to the textile at present mainly comprise an organic halogen flame retardant system, a nitrogen flame retardant system, a phosphorus flame retardant system, a silicon flame retardant system and the like, wherein the organic halogen flame retardant material has excellent flame retardant property and small addition amount, but generates a large amount of toxic, harmful and strong irritant gases during combustion, and causes direct, potential and long-term harm to human health and environment, so that the research and development of the halogen-free flame retardant material become necessary trends; the main advantages of nitrogen, phosphorus and silicon flame retardant materials are low toxicity, low smoke and low corrosion, but the mechanical properties of the materials are often influenced due to large addition amount required, so the application of the materials is limited to a certain extent, the health and environmental problems become increasingly focused with the development of social economy, the green development strategy becomes more important development strategy of the country, the P-N flame retardant is a new one in modern flame retardants, the defect that the traditional halogen flame retardant is decomposed to release toxic gas is overcome, the advantages of the phosphorus flame retardant and the nitrogen flame retardant are cooperated, and the nitrogen, phosphorus and silicon flame retardant is a great hotspot researched by current scholars.
In order to obtain a high-efficiency, environment-friendly and green textile flame-retardant material, the novel triazine derivative flame-retardant material is invented, and the novel triazine derivative flame-retardant material has the structural characteristics that: (1) taking a triazine six-membered heterocyclic structure with excellent thermal stability as a basic skeleton, and grafting a DOPO structure into the triazine skeleton through nucleophilic substitution reaction; (2) triazine ring in the molecular structure contains abundant N source, and DOPO group contains P source. According to the characteristics of molecular structures, the material is a novel triazine derivative flame retardant with excellent performance, can endow a flame-retardant substrate with good flame retardant performance, and is expected to have excellent application prospects in the fields of textile industry, plastics, leather and the like.
Disclosure of Invention
The invention aims to provide a novel environment-friendly and efficient triazine derivative flame-retardant material and a preparation method thereof.
The technical scheme of the invention is as follows:
a triazine derivative flame-retardant material has a molecular structure shown as follows:
the chemical structure name of the triazine derivative is tris- [4- (p-hydroxyphenylamine-phosphaphenanthrene) methylene-phenoxy ] -1,3, 5-triazine, and the name is simply called as follows: NPFR.
The preparation method of the novel triazine derivative flame retardant material takes triazine six-membered heterocyclic ring as a basic skeleton, introduces structures such as DOPO and the like into the triazine skeleton through nucleophilic substitution reaction, and comprises the following steps:
(1) using dichloromethane as solvent, reacting TCT with 4-HBA to obtain 2,4, 6-tri (4-aldehyde phenoxy) -1,3, 5-triazine (ZJT).
(2) Under the nitrogen atmosphere, DOPO and PAP are introduced into a ZJT structure to obtain the novel triazine derivative flame-retardant molecule NPFR.
Further, in the step (1), the molar ratio of the raw materials TCT to 4-HBA is 1: 2.4-3.6.
Further, in the step (2), the molar ratio ZJT, DOPO and PAP is 1: 2.4-3.6.
Furthermore, in the step (1), triethylamine is selected as a catalyst (TEA), and the dosage of the catalyst is TEA:4-HBA which is 0.1-0.4: 1.
Further, in the step (1), the dripping temperature of the NAOH solution is selected to be 5-10 ℃, and the reflux temperature is selected to be the final reaction temperature. .
Further, in the step (1), the reaction time is 0.5 to 2.5 hours
Further, in the step (2), the 1, 4-dioxane solution of p-aminophenol is dripped and then subjected to reflux reaction for about 12 hours, and the 1, 4-dioxane solution of DOPO is added and then subjected to reflux reaction for about 12 hours.
Further, in the step (2), the reaction environment is a nitrogen atmosphere.
Further, the reaction of the step (1) is specifically as follows:
synthesis of 2,4, 6-tris (4-formylphenoxy) -1,3, 5-triazine (ZJT)
Weighing a certain amount of p-hydroxybenzaldehyde and cyanuric chloride in a 250mL beaker, adding dichloromethane for dissolution, carrying out ice-water bath at 0-5 ℃, stirring, and adding Triethylamine (TEA) as a phase transfer catalyst. The corresponding amount of sodium hydroxide was weighed and dissolved in distilled water. The sodium hydroxide solution was then added slowly and stirred for 1O min to complete the reaction. The reaction mixture was introduced into a 500mL three-necked flask and heated under reflux for two hours. Then the dichloromethane is distilled off, filtered, dried and recrystallized by ethyl acetate. To obtain the organic intermediate 2,4, 6-tri (4-aldehyde phenoxy) -1,3, 5-triazine (ZJT).
The reaction in the step (2) is specifically as follows:
synthesis of novel triazine derivative flame-retardant molecule NPFR
Weighing a certain amount of ZJT, dissolving the ZJT in a three-neck flask filled with 1, 4-dioxane, stirring the mixture until the ZJT is dissolved under the protection of nitrogen, weighing a corresponding molar amount of p-aminophenol, dissolving the p-aminophenol in the 1, 4-dioxane, dropwise adding the p-aminophenol into the three-neck flask, heating the mixture to 102 ℃, carrying out reflux reaction for about 12 hours, adding a corresponding molar amount of DOPO, continuously refluxing for about 12 hours, carrying out suction filtration while the mixture is hot, concentrating the filtrate by using a rotary evaporator, pouring the concentrated filtrate into cold ethanol, stirring the mixture until white precipitate is separated out, carrying out suction filtration, washing, and carrying out vacuum drying at 65 ℃ overnight to obtain the target triazine derivative flame-retardant molecule: NPFR.
The invention also aims to apply the triazine derivative-based flame-retardant material to the flame retardance of various flame-retardant base materials, particularly cotton fabrics, so as to endow the flame-retardant base materials with green and efficient flame-retardant properties.
Taking the flame retardant application of the novel triazine derivative flame retardant material in cotton fabric as an example, the invention has the beneficial effects that:
(1) the invention takes TCT, 4-HBA, DOPO and PAP as raw materials to synthesize a novel environment-friendly and high-efficiency triazine derivative flame-retardant material: NPFR, which compound is not reported in the prior art.
(2) DSC and TG tests show that the novel triazine derivative flame retardant material has good thermal property and char forming property, and can endow a flame-retardant base material with good flame retardant property.
(3) By taking the flame retardant finishing of cotton fabrics as an example, performance tests such as limit oxygen index, vertical combustion experiments and the like show that the novel triazine derivative flame retardant material disclosed by the invention endows the cotton fabrics with excellent flame retardant performance and can play an outstanding flame retardant effect at high temperature.
Drawings
FIG. 1 is a DSC and TG analysis test curve of NPFR obtained in example 2 of the present invention.
FIG. 2 is a TG and TGA curve of cotton fabric before and after flame retardant finishing in example 2 of the present invention.
FIG. 3 is an IR spectrum of NPFR obtained in example 2 of the present invention.
FIG. 4 is a nuclear magnetic hydrogen spectrum of ZJT obtained in example 1 of the present invention.
FIG. 5 is a nuclear magnetic hydrogen spectrum of NPFR obtained in example 3 of the present invention.
FIG. 6 is a comparison diagram of the state of the cotton fabric after combustion before and after finishing by the novel triazine derivative flame retardant material.
FIG. 7 is a scanning electron microscope image of cotton fabric before and after finishing by the novel triazine derivative flame retardant material.
Detailed Description
The present invention is further illustrated in detail below with reference to specific examples, which are not intended to limit the scope of the invention in any way.
Example 1
Synthesis of 2,4, 6-tris (4-formylphenoxy) -1,3, 5-triazine (ZJT).
22.00g (0.054mol) of p-hydroxybenzaldehyde and 10.00g (0.18mol) of cyanuric chloride are weighed into a 100 mL beaker, dissolved in 80.00mL of dichloromethane, stirred in an ice-water bath at 0-5 ℃, and added with 6.00mL of Triethylamine (TEA) as a phase transfer catalyst. 7.20g of sodium hydroxide was weighed and dissolved in 50.00mL of distilled water. Then the sodium hydroxide solution was slowly added and stirred for 10 minutesThe reaction was completed. The reaction mixture was introduced into a 500mL three-necked flask and heated under reflux for two hours. Then the dichloromethane is distilled off, filtered, dried and recrystallized by ethyl acetate. To obtain the organic intermediate 2,4, 6-tri (4-aldehyde phenoxy) -1,3, 5-triazine (ZJT). Yield: 95.86 percent. FTIR (KBr), v/cm-1: 1161.95, 1214.49(C-O-Ar), 1569.18, 1501.37, 1376.00(Ar), 2836.37, 2742.30, 1701.16 (Ar-CHO).1H NMR(CDCl3,300MHz) δ:7.31~7.33(t,6H),7.91~7.93(m,6H),10.00(s,3H)。
Example 2
Synthesis of novel triazine derivative flame retardant material NPFR
7.58g (69mmol) of p-aminophenol was weighed into 150.00mL1, 4-dioxane, heated until all was dissolved, and 9.35g (21mmol) of intermediate was added and heated under reflux for 12h under nitrogen. 14.60 g of DOPO (69mmol) was weighed out and dissolved in 60.00mL of 1, 4-dioxane, and heated until all was dissolved, and the solution was colorless and transparent. And slowly adding DOPO solvent into the reaction, vacuumizing, heating and refluxing for 12h under the protection of nitrogen, performing rotary evaporation, washing with cold ethanol, and drying in a vacuum drying oven at 60 ℃ for 24 h. The yield was 94.76%. FTIR (KBr), v/cm-1:3317.65(N-H),1569.37、1371.31(P-Ar),1213.11 (P=O)。1H NMR(DMSO-d6,300MHz)δ:8.46-8.44(m,3H),δ:8.20-7.02(m,36H),δ:6.54-6.19(m,12H),6:5.68-5.58(m,3H),δ:5.07-5.01(m,3H)。
Example 3
Example 2 thermodynamic analysis of the novel triazine derivative flame retardant Material (NPFR)
DSC thermodynamic analysis test conditions for NPFR were: in N2In the atmosphere, the temperature is increased from room temperature to 280 ℃ at the temperature increasing speed of 10 ℃/min, and the TG analysis test conditions are as follows: in N2In the atmosphere, the temperature was raised from room temperature to 700 ℃ at a temperature raising rate of 20 ℃/min, and the results of the DSC and TG analysis of NPFR are shown in FIG. 1. In the DSC curve of NPFR, 189.5 ℃ is the absorption peak when NPFR melts, and 261.1 ℃ is the decomposition of NPFR-2 phosphorus-containing DOPO group started by heating. With the temperature rise, absorption peaks appear at 324.2 deg.C, 349.6 deg.C, 387.1 deg.C, 462.1 deg.C, etc. successively,it means that other bonds such as triazine ring and benzene ring are successively broken. The TG test result of NPFR is basically consistent with that of DSC, and with the increase of temperature, about 260-420 ℃ is taken as a first weight loss stage, at the moment, the DOPO group containing phosphorus is broken and decomposed, and a large amount of volatile substances are released, so that a carbon layer containing phosphorus is generated. And (3) the weight loss at the second stage is at 420-550 ℃, and possible reasons are that a large amount of volatile substances are released due to the breakage of bonds such as triazine rings and benzene rings, and the mass of the product is greatly lost. When the test temperature reached 700 ℃, the carbon residue of the product after degradation was 34.2%, which is 29.9% higher than that of the compound Trif-DOPO (see CN 106498732A) known in the prior art at 700 ℃. When the testing temperature reaches 780 ℃, the residual carbon content of the flame retardant is still 26.0 percent. The compound of the invention has very good char forming effect, and the probable reason is that the product structure contains higher phosphorus content and more benzene ring groups, so that the flame retardant material can be endowed with better flame retardant property.
Example 4
In N2TG and TGA of the cotton fabric before and after finishing were measured at a temperature rising rate of 20 ℃/min from room temperature to 500 ℃ under the atmosphere, and the results are shown in FIG. 2. As can be seen from FIG. 2, the residual carbon content of the non-flame-retardant finished cotton fabric is only 14.6% when the cotton fabric is heated to 500 ℃, and the residual carbon content of the treated cotton fabric reaches 27.5% when the cotton fabric is heated to 500 ℃. This shows that NPFR is carbonized to form an expansion type carbon layer to cover the surface of the fabric, which has good heat insulation effect and prevents the fabric from being continuously decomposed, thereby showing that NPFR has good flame retardant effect on cotton fabrics and excellent char forming performance.
Example 5
The flame retardant NPFR is applied to the flame retardant finishing of cotton fabrics.
The process flow comprises the following steps: preparing finishing liquid, padding (two times of padding and two times of padding, the rolling residual rate is 70%), pre-drying (80 ℃, 5min), baking (170 ℃, 3min), washing with standard water for one time, drying and then performing a sample shearing test.
The process prescription is as follows: 200g/L of flame retardant and 60g/L of crosslinking agent.
Example 6
The flame retardant NPFR is applied to the flame-retardant finishing of cotton fabrics and then is subjected to electron microscope scanning test, the amplification is 3000 times, the surface morphology of the flame retardant NPFR is compared with that of blank sample fibers, whether the flame retardant is on the surface of the fibers or not is researched, and the test result is shown in figure 5. The KONGBAI group indicates cotton fabrics which have not been flame-retardant treated, and NPFR indicates cotton fabrics which have been flame-retardant treated. As can be seen from the figure, the surface of the unfinished cotton fabric fiber is relatively smooth, and uniform and fine gaps or ravines exist. The surface of the cotton fabric fiber after the second dipping and the second rolling of the flame retardant becomes unsmooth, and the surface of the fiber is wrapped by a layer of covering, which shows that the flame retardant molecules are successfully attached to the cotton fabric, thereby increasing the flame retardant property of the cotton fabric.
Example 7
The state of the cotton fabric before and after the flame retardant NPFR treatment is shown in fig. 6. The residues of unfinished cotton fabrics (KONGBAI) after combustion are light grey, producing a thin layer of ashes, in an amorphous state, which is easily blown off; the surface of the cotton fabric sample treated by the flame retardant is dark black after combustion, and a thick carbon layer is generated, because the flame retardant is burnt to form carbon which is attached to the surface of the cotton fabric, the treated cotton fabric can form a stable skeleton state after combustion, the heat insulation effect is achieved, and meanwhile, the outward diffusion of combustible gases such as oxygen and the like is isolated.
Example 8
The M606 type limit oxygen index instrument produced by Qingdao mountain spinning is adopted to carry out limit oxygen index test and vertical burning test on the cotton fabric before and after flame retardant finishing, and the test results are shown in Table 1. As can be seen from Table 1, the test of the limited oxygen index shows that the cotton fabric (KONGBAI) without flame retardant finishing is extremely easy to burn, the LOI value is only 18%, the flame retardant performance of the cotton fabric after flame retardant finishing is obviously enhanced, when the concentration of the flame retardant NPFR is 200.0g/L, the LOI value reaches 28.3%, and the LOI value is increased by 1.57 times compared with the cotton fabric without flame retardant finishing. While the LOI value of the cotton fabric subjected to flame-retardant finishing by the Trif-DOPO is only 24.8 percent. Through the vertical combustion experiment, the following results are obtained: the KONGBAI sample still burns and the sample is totally destroyed after the open fire is removed, when the concentration of the flame retardant is 200.0g/L, the continuous burning time of the NPFR sample is 3.6s, the smoldering time is 0s, and the damage length is reduced to 6.9cm from the original total damage. The continuous burning time of the cotton fabric after flame retardant finishing by the Trif-DOPO is 4.5s, the smoldering time is 0s, and the damage length is 7.5 cm. The conclusion is that the novel flame retardant can endow the cotton fabric with good flame retardant performance, and compared with the flame retardant in the prior art, the flame retardant performance of the cotton fabric finished by the flame retardant is obviously improved, and the cotton fabric is changed from flammable fabrics into flame-retardant fabrics.
TABLE 1