Single-component halogen-free flame retardant with high char forming function and application of single-component halogen-free flame retardant

Abstract

The invention relates to a single-component halogen-free flame retardant with a high char forming function and application, the structural formula of the flame retardant is as shown in formula I or II, and the preparation method comprises the following steps: S1, adding reactants phosphonitrilic chloride trimer, an acid-binding agent and a reaction solvent into a three-neck flask, and stirring to form a reaction solution 1; s2, introducing nitrogen into a three-neck flask filled with the reaction solution 1 to form an oxygen-free environment; s3, dissolving an alkynyl functional group-containing reactant in a reaction solvent in a beaker to form a reaction solution 2; s4, dropwise adding the reaction solution 2 into a three-neck flask filled with the reaction solution 1; s5, stirring the reaction mixture in the step S4; s6, after stirring, a reaction mixture is subjected to suction filtration, obtained filtrate is subjected to rotary evaporation, an obtained crude product is washed and then dried, and the flame retardant is obtained.The single-component halogen-free flame retardant with the high char forming function is good in char forming performance and high in flame retardant efficiency, and when the flame retardant is applied to thermoplastic polyurethane and other materials, the carbon residue rate can be greatly increased, the carbon layer quality can be improved, and the flame retardant efficiency is improved. And the prepared flame-retardant material realizes flame molten drop resistance and has an excellent flame-retardant effect.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardants, and in particular relates to a single-component halogen-free flame retardant with high charring function and application thereof. Background Art

[0002] With the development of polymer material science and technology, thermoplastic polyurethane (TPU) has been widely used in many fields such as electronics, rail transportation, aerospace, and automobiles. As a polymer material, TPU is extremely easy to burn, easy to produce droplets when burning, and has a low limiting oxygen index. These pain points seriously limit its further application in many fields. In order to broaden the application of TPU, it is very necessary to modify it to be flame retardant. Since the promulgation of the EU RoHS and WEEE directives, the call for the development of green and environmentally friendly flame retardants has become increasingly louder. Traditional halogen flame retardants will gradually be eliminated because they produce toxic gases such as dioxins when burned. Therefore, it is very necessary to develop environmentally friendly flame retardants with high flame retardant efficiency. Summary of the invention

[0003] In order to solve the problems in the prior art, the present invention provides a single-component halogen-free flame retardant with high charring function and its application, so as to achieve a single-component halogen-free flame retardant with high charring function, good charring performance and high flame retardant efficiency. The flame retardant is used on materials such as thermoplastic polyurethane, which can greatly increase the residual carbon rate and improve the quality of the carbon layer. The prepared flame retardant material achieves resistance to flame droplets and has an excellent flame retardant effect.

[0004] At present, flame retardants that integrate phosphorus and nitrogen are one of the research hotspots in the field of flame retardancy. However, when traditional phosphorus-nitrogen series flame retardants are used to flame retard TPU, there are problems such as poor carbon layer quality and low flame retardant efficiency. The cross-linking reaction of alkynyl groups can improve the quality of the carbon layer, thereby better isolating heat transfer and improving flame retardant efficiency. However, the flame retardant effect of using alkynyl-containing additives alone to flame retard TPU is not good, so how to use the cross-linking reaction of phosphorus-nitrogen flame retardants and alkynyl functional groups to improve the flame retardant efficiency is a key problem that needs to be solved and disclosed in the present invention.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] The present invention aims to provide a single-component halogen-free flame retardant with high carbonization function, the flame retardant structural formula is as shown in Formula I or II,

[0007] Formula I is:

[0008]

[0009] Formula II is:

[0010]

[0011] Wherein, R1 in Formula I and II is one of Formula III, Formula IV or Formula V; Formula III is:

[0012]

[0013] Formula IV is:

[0014]

[0015] Formula V is:

[0016]

[0017] In formula V, n=1-3.

[0018] Furthermore, the preparation method of the flame retardant comprises the following steps:

[0019] S1, adding the reactant hexachlorocyclotriphosphazene (HCCP), an acid binding agent and a reaction solvent into a three-necked flask, and stirring to form a reaction solution 1;

[0020] S2, nitrogen is introduced into the three-necked flask containing the reaction solution 1 to form an oxygen-free environment;

[0021] S3, dissolving the reactant containing an alkynyl functional group in a reaction solvent in a beaker to form a reaction solution 2;

[0022] S4, adding the reaction solution 2 dropwise into the three-necked flask containing the reaction solution 1;

[0023] S5, stirring the reaction mixture of S4;

[0024] S6. After stirring, the reaction mixture is filtered and the filtrate is rotary evaporated. The crude product is washed and then dried to obtain a flame retardant.

[0025] Furthermore, the acid-binding agent is one of triethylamine, pyridine and potassium carbonate; the reaction solvent is a mixture of one or more of tetrahydrofuran (THF), dimethylformamide (DMF), dichloromethane (DCM) and acetonitrile (MeCN).

[0026] Furthermore, in S3, the alkynyl functional group-containing reactant also contains an amino or imino functional group, and the alkynyl functional group-containing reactant is one of aminopropyne, aminophenylacetylene, and dipropargylamine.

[0027] Furthermore, in S4, the molar ratio of the reactant containing an alkynyl functional group to the hexachlorocyclotriphosphazene is 3 to 7:1.

[0028] Further, in S4, the reaction solution 2 is slowly added dropwise into the three-necked flask containing the reaction solution 1 at 0° C. using a dropping funnel, and stirred.

[0029] Further, in S5, the reaction mixture is stirred at 50°C-100°C for 12-48 hours.

[0030] Furthermore, in S6, the filtrate is subjected to rotary evaporation in a rotary evaporator, and the crude product obtained after rotary evaporation is washed three times with dichloromethane, and then dried in a vacuum drying oven at 60-80° C. for 24 hours to obtain a flame retardant.

[0031] A method for preparing flame-retardant thermoplastic polyurethane comprises the following steps: adding the aforementioned single-component halogen-free flame retardant with high carbonization function and thermoplastic polyurethane (TPU) into an extruder for blending at a blending temperature of 170°C-220°C for a blending time of 3-10 minutes, followed by injection molding at a temperature of 180°C-230°C.

[0032] Furthermore, the mass ratio of the single-component halogen-free flame retardant with high charring function to the thermoplastic polyurethane added to the extruder is 3-7:100, for example, when there are 100 parts of thermoplastic polyurethane, the single-component halogen-free flame retardant with high charring function is 3-7 parts, such as 3 parts, 4 parts, 5 parts, 6 parts or 7 parts can be added.

[0033] Compared with the prior art, the beneficial technical effects of the present invention are:

[0034] 1. The flame retardant of the present invention is a single-component halogen-free flame retardant with high carbonization function. The quality of the carbon layer can be improved by utilizing the acetylenic cross-linking reaction in the flame retardant, thereby better isolating heat transfer.

[0035] 2. The flame retardant of the present invention has high flame retardant efficiency. Only 3% of the flame retardant needs to be added to TPU, and the vertical combustion grade of the material is increased from V2 to V0.

[0036] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above contents of the present invention and its objectives, features and advantages more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a photograph of the oxygen index test of ordinary TPU (Comparative Example 1) at an oxygen concentration of 27.5%.

[0038] Figure 2 This is a photograph of the oxygen index test of the flame retardant TPU (Example 6) of the present invention at an oxygen concentration of 27.5%.

[0039] Figure 3 It is a comparison chart of thermogravimetric curves of the flame retardant TPU (Example 6) of the present invention and the ordinary TPU (Comparative Example 1).

[0040] Figure 4 The photos are of the residual carbon layer after the cone calorimetry test of the flame retardant TPU (Example 6) of the present invention and the ordinary TPU (Comparative Example 1). DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary illustrations and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0042] In addition, unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0043] Example 1

[0044] A method for preparing a single-component halogen-free flame retardant with high carbonization function:

[0045] S1. Add HCCP (38.24 g, 0.11 mol), pyridine (52.21 g, 0.66 mol) and 400 ml of DMF into a three-necked flask and stir to form a reaction solution 1;

[0046] S2, introducing nitrogen into the three-necked flask containing the reaction solution 1 to form an oxygen-free environment;

[0047] S3, dissolving dipropargylamine (71.71 g, 0.77 mol) in 100 ml of DMF solvent in a beaker to form reaction solution 2;

[0048] S4. At 0°C, slowly drop the reaction solution 2 into the three-necked flask containing the reaction solution 1 using a dropping funnel and stir;

[0049] S5, stirring the reaction mixture at 100° C. for 12 hours;

[0050] S6. Filter the reaction mixture by suction, and evaporate the obtained filtrate in a rotary evaporator. Wash the obtained crude product with dichloromethane three times, and then dry it in a vacuum drying oven at 80° C. for 24 hours to obtain a flame retardant.

[0051] Example 2

[0052] A method for preparing a single-component halogen-free flame retardant with high carbonization function:

[0053] S1. Add HCCP (38.24 g, 0.11 mol), triethylamine (66.79 g, 0.66 mol) and 400 ml of THF into a three-necked flask and stir to form a reaction solution 1;

[0054] S2, introducing nitrogen into the three-necked flask containing the reaction solution 1 to form an oxygen-free environment;

[0055] S3, dissolving propargylamine (36.35 g, 0.66 mol) in 100 ml of THF in a beaker to form reaction solution 2;

[0056] S4. At 0°C, slowly drop the reaction solution 2 into the three-necked flask containing the reaction solution 1 using a dropping funnel and stir;

[0057] S5, stirring the reaction mixture at 80° C. for 24 hours;

[0058] S6. Filter the reaction mixture by suction, and evaporate the obtained filtrate in a rotary evaporator. Wash the obtained crude product with dichloromethane three times, and then dry it in a vacuum drying oven at 60° C. for 24 hours to obtain a flame retardant.

[0059] Example 3

[0060] A method for preparing a single-component halogen-free flame retardant with high carbonization function:

[0061] S1. Add HCCP (38.24 g, 0.11 mol), potassium carbonate (45.61 g, 0.33 mol), 300 ml of DCM and 100 ml of MeCN into a three-necked flask and stir to form a reaction solution 1;

[0062] S2, introducing nitrogen into the three-necked flask containing the reaction solution 1 to form an oxygen-free environment;

[0063] S3, dissolving 4-aminophenylacetylene (38.66 g, 0.33 mol) in 100 ml of DCM in a beaker to form reaction solution 2;

[0064] S4. At 0°C, slowly drop the reaction solution 2 into the three-necked flask containing the reaction solution 1 using a dropping funnel and stir;

[0065] S5, stirring the reaction mixture at 50° C. for 48 hours;

[0066] S6. Filter the reaction mixture by suction, and evaporate the obtained filtrate in a rotary evaporator. Wash the obtained crude product with dichloromethane three times, and then dry it in a vacuum drying oven at 70° C. for 24 hours to obtain a flame retardant.

[0067] Taking the single-component halogen-free flame retardant with high carbonization function prepared in Example 1 as an example, it is used to prepare flame-retardant TPU resin, such as the following Examples 4-8.

[0068] Example 4

[0069] The preparation method of flame retardant TPU resin comprises the following steps.

[0070] S1. Add 100 parts of TPU resin and 1 part of flame retardant into an extruder and blend for 10 minutes at a blending temperature of 180°C.

[0071] S2, and then injection molding into samples, the injection temperature is 190 ° C.

[0072] Example 5

[0073] The preparation method of flame retardant TPU resin comprises the following steps.

[0074] S1. Add 100 parts of TPU resin and 3 parts of flame retardant into an extruder and blend for 5 minutes at a blending temperature of 170°C.

[0075] S2, and then injection molding into samples, the injection temperature is 180 ° C.

[0076] Example 6

[0077] The preparation method of flame retardant TPU resin comprises the following steps.

[0078] S1. Add 100 parts of TPU resin and 5 parts of flame retardant into an extruder and blend for 5 minutes at a blending temperature of 170°C.

[0079] S2, and then injection molding into samples, the injection temperature is 180 ° C.

[0080] Example 7

[0081] The preparation method of flame retardant TPU resin comprises the following steps.

[0082] S1. Add 100 parts of TPU resin and 7 parts of flame retardant into an extruder and blend for 3 minutes at a blending temperature of 160°C.

[0083] S2, and then injection molding into samples, the injection molding temperature is 170 ° C.

[0084] Example 8

[0085] The preparation method of flame retardant TPU resin comprises the following steps.

[0086] S1. Add 100 parts of TPU resin, 5 parts of flame retardant and 0.5 parts of PTFE into an extruder and blend for 5 minutes at a blending temperature of 170°C.

[0087] S2, and then injection molding into samples, the injection temperature is 180 ° C.

[0088] In order to demonstrate the superiority of the single-component halogen-free flame retardant with high charring function of the present invention, Comparative Example 1 is set up herein.

[0089] Comparative Example 1

[0090] S1, add 100 parts of TPU resin into the extruder and mix for 5 minutes at a mixing temperature of 180°C;

[0091] S2, and then injection molding into samples, the injection temperature is 180 ° C.

[0092] The properties of the flame retardant TPU prepared in Test Examples 4 to 8 and Comparative Example 1 are shown in Table 1 below:

[0093] Table 1

[0094]

[0095]

[0096] The flame retardant thermoplastic polyurethane of the present invention is compared Figure 1 and Figure 2 It can be seen that in an environment with an oxygen concentration of 27.5%, conventional TPU continues to burn, accompanied by molten droplets with flames, and the flame spreads to 5 cm at 15 seconds. However, the flame-retardant TPU of the present invention extinguishes at 35 seconds, accompanied by molten droplets, but the molten droplets do not have flames, and the flame does not spread to 5 cm during the whole process.

[0097] from Figure 3 From the thermogravimetric curve, it can be found that at 800°C, the residual carbon rate of conventional TPU is only 2.91%, while the residual carbon rate of the flame-retarded TPU of the present invention is as high as 18.84% at 800°C. The single-component halogen-free flame retardant with high carbonization function greatly improves the residual carbon rate of TPU.

[0098] It can be found from Table 1 that the addition of the flame retardant of the present invention improves the oxygen index of TPU. With the addition of the flame retardant, the oxygen index shows a trend of first increasing and then decreasing. When 5 parts of the flame retardant are added, the oxygen index reaches a maximum of 27.5%. The vertical burning test found that when 3 parts of the flame retardant are added, the vertical burning level of TPU can reach V0 level; with the increase of the amount of flame retardant, the weight of the sample after the test changes, showing a trend of first decreasing and then increasing. When 3 parts of the flame retardant are added, its weight becomes 0.455g. The heat release peak test found that with the increase of the flame retardant, its heat release peak becomes smaller, but when 7 parts of the flame retardant are added, its heat release peak is 355.5kW / m 2 , compared with TPU, it has dropped by 46.5%.

[0099] In order to improve the anti-dripping property of the flame retardant TPU during combustion, 0.5 parts of polytetrafluoroethylene (PTFE) were added in Example 8. At this time, the oxygen index of the flame retardant TPU was 27.5%, the vertical combustion grade was V0, no molten dripping occurred during the test, and the weight change of the sample after the test was only 0.045g.

[0100] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0101] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A single-component halogen-free flame retardant with high carbonization function, characterized in that: The flame retardant structural formula is as shown in Formula Ⅰ or Ⅱ, Formula I is: Formula II is: Wherein, R1 in Formula I and II is one of Formula III, Formula IV or Formula V; Formula III is: Formula IV is: Formula V is: In formula V, n=1-3.

2. A single-component halogen-free flame retardant with high carbonization function as claimed in claim 1, characterized in that: The preparation method of the flame retardant comprises the following steps: S1, adding the reactant hexachlorocyclotriphosphazene, the acid binding agent and the reaction solvent into a three-necked flask, and stirring to form a reaction solution 1; S2, nitrogen is introduced into the three-necked flask containing the reaction solution 1 to form an oxygen-free environment; S3, dissolving the reactant containing an alkynyl functional group in a reaction solvent in a beaker to form a reaction solution 2; S4, adding the reaction solution 2 dropwise into the three-necked flask containing the reaction solution 1; S5, stirring the reaction mixture of S4; S6. After stirring, the reaction mixture is filtered and the filtrate is rotary evaporated. The crude product is washed and then dried to obtain a flame retardant.

3. A single-component halogen-free flame retardant with high carbonization function as claimed in claim 2, characterized in that: The acid-binding agent is one of triethylamine, pyridine and potassium carbonate; the reaction solvent is a mixture of one or more of tetrahydrofuran, dimethylformamide, dichloromethane and acetonitrile.

4. A single-component halogen-free flame retardant with high carbonization function as claimed in claim 2, characterized in that: In S3, the alkynyl functional group-containing reactant also contains an amino or imino functional group, and the alkynyl functional group-containing reactant is one of aminopropyne, aminophenylacetylene, and dipropargylamine.

5. A single-component halogen-free flame retardant with high carbonization function as claimed in claim 2, characterized in that: In S4, the molar ratio of the reactant containing an alkynyl functional group to the hexachlorocyclotriphosphazene is 3 to 7:

1.

6. A single-component halogen-free flame retardant with high carbonization function as claimed in claim 2, characterized in that: In S4, the reaction solution 2 is slowly added dropwise to the three-necked flask containing the reaction solution 1 at 0°C using a dropping funnel, and stirred.

7. A single-component halogen-free flame retardant with high carbonization function as claimed in claim 2, characterized in that: In S5, the reaction mixture is stirred at 50°C-100°C for 12-48 hours.

8. A single-component halogen-free flame retardant with high carbonization function as claimed in claim 2, characterized in that: In S6, the filtrate is subjected to rotary evaporation in a rotary evaporator, and the crude product obtained after rotary evaporation is washed three times with dichloromethane, and then dried in a vacuum drying oven at 60-80° C. for 24 hours to obtain a flame retardant.

9. Use of a single-component halogen-free flame retardant with high carbonization function as claimed in any one of claims 1 to 8 in the preparation of flame-retardant thermoplastic polyurethane, characterized in that: The preparation method of flame-retardant thermoplastic polyurethane is as follows: a single-component halogen-free flame retardant with high carbonization function and thermoplastic polyurethane are added into an extruder for blending at a blending temperature of 170°C-220°C for 3-10 minutes, followed by injection molding at a molding temperature of 180°C-230°C.

10. The use according to claim 9, characterized in that: The mass ratio of the single-component halogen-free flame retardant with high carbonization function added into the extruder and blended to the thermoplastic polyurethane is 3-7:100.

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