阅读说明：本技术 一种dopo基反应型阻燃剂改性聚醚酰胺及其制备方法 (DOPO-based reactive flame retardant modified polyether amide and preparation method thereof ) 是由 李桃桃 刘可 魏良跃 于 2020-12-29 设计创作，主要内容包括：本发明涉及阻燃聚醚酰胺领域,公开了一种DOPO基反应型阻燃剂改性聚醚酰胺及其制备方法。本发明改性聚醚酰胺的制备方法包括以下步骤：(1)将己内酰胺熔融后,与二元酸、开环剂一起加入反应容器中,在搅拌下进行开环反应,获得低聚物；(2)向反应容器中加入DOPO基反应型阻燃剂,在搅拌下进行酯化反应,获得聚酰胺预聚物；(3)向反应容器中加入聚二元醇和缩聚反应催化剂,在搅拌下进行缩聚反应,获得阻燃聚醚酰胺。本发明采用的DOPO基反应型阻燃剂以羟基为两端活性基团,能参与聚醚酰胺的共聚,有效提高聚醚酰胺的阻燃性能,且与聚二元醇结构类似,对聚醚酰胺力学性能的负面影响较小。(The invention relates to the field of flame retardant polyether amide, and discloses a DOPO-based reactive flame retardant modified polyether amide and a preparation method thereof. The preparation method of the modified polyether amide comprises the following steps: (1) melting caprolactam, adding the caprolactam, dibasic acid and a ring-opening agent into a reaction vessel, and carrying out a ring-opening reaction under stirring to obtain an oligomer; (2) adding a DOPO-based reactive flame retardant into a reaction vessel, and carrying out esterification reaction under stirring to obtain a polyamide prepolymer; (3) and adding the polyglycol and a polycondensation reaction catalyst into the reaction vessel, and carrying out polycondensation reaction under stirring to obtain the flame-retardant polyether amide. The DOPO-based reactive flame retardant disclosed by the invention takes hydroxyl groups as active groups at two ends, can participate in the copolymerization of the polyether amide, effectively improves the flame retardant property of the polyether amide, is similar to a polyglycol structure, and has small negative influence on the mechanical property of the polyether amide.)

1. The DOPO-based reactive flame retardant modified polyether amide is characterized by comprising caprolactam, polyglycol, dibasic acid and a DOPO-based reactive flame retardant; the DOPO-based reactive flame retardant has the structural formula:

wherein R is one of aliphatic carbon chain, carbon chain containing benzene ring or carbon chain containing hetero atom.

2. The modified polyetheramide of claim 1 wherein the ratio of moles of diacid to the total moles of polyglycol and DOPO-based reactive flame retardant is 1:0.8 to 1.2.

3. The modified polyetheramide of claim 1 further comprising a ring-opener and a polycondensation catalyst.

4. The flame-retardant polyetheramide according to claim 3, wherein the mass fraction of caprolactam is 50 to 90 wt%, the mass fraction of polyglycol is 9 to 40 wt%, the mass fraction of DOPO-based reactive flame retardant is 1.5 to 8 wt%, the mass fraction of ring-opening agent is 2 to 6 wt%, and the content of polycondensation reaction catalyst is 1 to 2 wt% of polyglycol.

5. The polyetheramide of claim 3 or 4 wherein:

the dibasic acid is adipic acid; and/or

The polyglycol is one or more of polyethylene glycol, polypropylene glycol and polybutylene glycol, and the molecular weight is 1000-4000; and/or

The ring-opening agent is water and/or aminocaproic acid; and/or

The polycondensation catalyst is tetrabutyl titanate.

6. A process for preparing the flame-retardant polyetheramide according to any one of claims 2 to 5, characterized by comprising the steps of:

(1) melting caprolactam, adding the caprolactam, dibasic acid and a ring-opening agent into a reaction vessel, and carrying out a ring-opening reaction under stirring to obtain an oligomer;

(2) adding a DOPO-based reactive flame retardant into a reaction vessel, and carrying out esterification reaction under stirring to obtain a polyamide prepolymer;

(3) and adding the polyglycol and a polycondensation reaction catalyst into the reaction vessel, and carrying out polycondensation reaction under stirring to obtain the flame-retardant polyether amide.

7. The preparation method according to claim 6, wherein in the step (1), the temperature of the ring-opening reaction is 240-260 ℃, the pressure is 0.3-0.5 MPa, and the time is 2-3 h.

8. The method according to claim 6, wherein in the step (2), the esterification reaction is carried out as follows: after reacting for 0.5-1 h under normal pressure, reducing the pressure to 300-350 Pa, and continuing to react for 2-3 h.

9. The method according to claim 6, wherein in the step (3), the polycondensation reaction is carried out as follows: reducing the pressure in the reaction container to be below 80Pa within 60-90 min, and then carrying out polycondensation reaction at 240-260 ℃ for 2-5 h.

10. The method according to claim 6, wherein the stirring is performed at a rotation speed of 60 to 100r/min in the steps (1) to (3).

Technical Field

The invention relates to the field of flame retardant polyether amide, and particularly relates to DOPO-based reactive flame retardant modified polyether amide and a preparation method thereof.

Background

The polyether amide elastomer is a block copolymer, which consists of a high-melting-point crystalline polyamide hard segment and a non-crystalline polyglycol soft segment, is used as a copolymer elastic material, and has various excellent properties of polyamide and polyether materials. The polyamide has excellent mechanical properties, is light and wear resistant, the polyglycol is a polymer with a polyether structure as a main chain and hydroxyl as a terminal active functional group, the polyamide is copolymerized with the polyglycol, the flexibility, the toughness and the hydrophilicity of the polyamide can be improved while the original excellent performance of the polyamide is maintained, and the excellent performances of the polyether material, such as creep resistance size, low-temperature flexibility, impact strength and the like, are added to the copolymerized elastic material. The copolymerization elastic materials with different softness can be obtained by controlling the addition ratio of the soft segments of different polydiols.

9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a commonly used flame retardant in high polymer materials, and can improve the flame retardant property of the materials through a dual mechanism of gas-phase flame retardant and condensed-phase flame retardant. Because DOPO begins to decompose at 180 ℃, the weight loss is about 90 wt% at 213-427 ℃, so that the DOPO reactive flame retardant has wider application field for improving the thermal reliability, flame retardance and compatibility with a matrix, reducing the negative influence on the matrix material and being more efficient, environment-friendly and designable. Because the polyether amide elastomer mainly comprises an amide group, an ether group and an aliphatic carbon chain, belongs to a combustible material, and has high heat generation, high combustion speed and serious molten drop during combustion, the polyether amide elastomer is usually required to be subjected to flame retardant modification during actual application, and the DOPO-based reactive flame retardant is polymerized in a polyether amide molecular chain, so that the polyether amide elastomer can be better applied to the fields of machinery, electricity, automobiles, textile and the like. However, currently, few reports have been made on flame retardant modification of polyether amides using DOPO-based flame retardants.

Disclosure of Invention

In order to solve the technical problems, the invention provides the DOPO-based reactive flame retardant modified polyether amide and the preparation method thereof.

The specific technical scheme of the invention is as follows:

a DOPO-based reactive flame retardant modified polyether amide comprises caprolactam, polydihydric alcohol, dibasic acid and a DOPO-based reactive flame retardant; the DOPO-based reactive flame retardant has the structural formula:

wherein R is one of aliphatic carbon chain, carbon chain containing benzene ring or carbon chain containing hetero atom.

9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a flame retardant with gas phase and condensed phase flame retardant effects, PO & free radical is formed at high temperature, the free radical can react with HO & free radical, H & free radical and alkyl free radical in gas phase during combustion, chain reaction is stopped, heat release amount is reduced, and gas phase flame retardant effect is achieved; in addition, DOPO can generate strong dehydrating agents such as metaphosphoric acid, metaphosphoric acid and the like in the pyrolysis process, so that the flame-retardant material is dehydrated and carbonized to form a heat-insulating carbon layer which is difficult to pyrolyze, oxygen and heat are prevented from being transmitted to the interior of the matrix, and the condensed phase flame-retardant effect is played.

The DOPO-based reactive flame retardant is a DOPO derivative, the two ends of the DOPO derivative contain two hydroxyl groups, the DOPO derivative can participate in the copolymerization of the polyether amide, and flame-retardant and heat-resistant groups are introduced into the molecular chain of the polyether amide to prepare the intrinsic flame-retardant polyether amide, so that the problem of poor thermal reliability of the DOPO is solved, and the flame retardant property of the polyether amide can be effectively improved. In addition, active groups at two ends of the DOPO-based reactive flame retardant are hydroxyl groups, and the structure of the DOPO-based reactive flame retardant is similar to that of polyglycol, so that the DOPO-based reactive flame retardant is better compatible with a polyether amide body, and has smaller negative influence on the mechanical property of polyether amide.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting caprolactam, adding the caprolactam, dibasic acid and a ring-opening agent into a reaction vessel, and carrying out a ring-opening reaction under stirring to obtain an oligomer;

the reaction process of step (1) is as follows (taking adipic acid as an example of dibasic acid):

the caprolactam is fully hydrolyzed and opened to generate aminocaproic acid under the action of a ring-opening agent, a small amount of aminocaproic acid is subjected to self-polycondensation, and meanwhile, dibasic acid reacts with amino to ensure that both ends of the oligomer are blocked by carboxyl.

(2) Adding a DOPO-based reactive flame retardant into a reaction vessel, and carrying out esterification reaction under stirring to obtain a polyamide prepolymer;

the reaction process of step (2) is as follows (taking adipic acid as an example of dibasic acid):

the hydroxyl group of the DOPO-based reactive flame retardant is esterified with the carboxyl group at the terminal of the oligomer, thereby being linked to the oligomer; meanwhile, a connection can be formed between two oligomer molecules through two hydroxyl groups in the DOPO-based reactive flame retardant.

(3) And adding the polyglycol and a polycondensation reaction catalyst into the reaction vessel, and carrying out polycondensation reaction under stirring to obtain the flame-retardant polyether amide.

The reaction process of step (3) is as follows (taking adipic acid as an example of dibasic acid):

hydroxyl groups at two ends of the polyglycol and carboxyl groups at the tail end of the polyamide prepolymer are subjected to esterification reaction to synthesize the block copolymer, namely the polyether amide.

In the preparation method, the DOPO-based reactive flame retardant is added after the caprolactam oligomer carboxyl is blocked, so that free flame retardant in finished product slices can be reduced, and the flame retardant can be distributed in the modified polyether amide molecular chain more uniformly.

Preferably, the ratio of the mole number of the dibasic acid to the total mole number of the polyglycol and the DOPO-based reactive flame retardant is 1: 0.8-1.2.

Preferably, the ratio of the number of moles of the dibasic acid to the total number of moles of the polyglycol and the DOPO-based reactive flame retardant is 1:1.

In the invention, the ratio of the mole number of the dibasic acid to the total mole number of the polyglycol and the DOPO-based reaction type flame retardant is controlled to be close to 1:1, and the preparation method has the following meanings for the preparation of the flame retardant polyether amide: 1, in the step (2), the mol number of the DOPO-based reactive flame retardant is less than that of the dibasic acid, so that both ends of the polyamide prepolymer can be prevented from being terminated by the DOPO-based reactive flame retardant, and the subsequent reaction with the polyglycol to generate polyether amide can not be carried out; 2, because both ends of the oligomer prepared in the step (1) are terminated by carboxyl, the mole number of the dibasic acid is the mole number of the oligomer, the ratio of the mole number of the dibasic acid to the total mole number of the polyglycol and the DOPO-based reaction type flame retardant is controlled to be close to 1:1, namely, after the DOPO-based reaction type flame retardant and the polyglycol are subsequently added, the number of the carboxyl and the hydroxyl is controlled to be close to 1:1, and the phenomenon that the product cannot continue to generate polycondensation reaction because of being terminated by the carboxyl or the hydroxyl in the reaction process of the step (3) is prevented, so that the viscosity of the generated flame-retardant polyether amide is too low, and the mechanical property is influenced.

Preferably, the modified polyether amide also comprises a ring-opening agent and a polycondensation reaction catalyst.

Preferably, the mass fraction of the caprolactam is 50-90 wt%, the mass fraction of the polyglycol is 9-40 wt%, the mass fraction of the DOPO-based reaction type flame retardant is 1.5-8 wt%, the mass fraction of the ring-opening agent is 2-6 wt%, and the content of the polycondensation reaction catalyst is 1-2 wt% of the polyglycol.

Preferably, the dibasic acid is adipic acid.

Preferably, the polyglycol is one or more of polyethylene glycol, polypropylene glycol and polybutylene glycol, and the molecular weight is 1000-4000.

Preferably, the ring-opener is water and/or aminocaproic acid.

Preferably, the polycondensation catalyst is tetrabutyl titanate.

Preferably, in the step (1), the temperature of the ring-opening reaction is 240-260 ℃, the pressure is 0.3-0.5 MPa, and the time is 2-3 h.

Preferably, in the step (2), the esterification reaction is performed in the following specific steps: after reacting for 0.5-1 h under normal pressure, reducing the pressure to 300-350 Pa, and continuing to react for 2-3 h.

Preferably, in step (3), the polycondensation reaction is performed in the following specific steps: reducing the pressure in the reaction container to be below 80Pa within 60-90 min, and then carrying out polycondensation reaction at 240-260 ℃ for 2-5 h.

Preferably, in the steps (1) to (3), the rotation speed of the stirring is 60 to 100 r/min.

Compared with the prior art, the invention has the following advantages:

(1) the DOPO-based reactive flame retardant adopted by the invention can participate in the copolymerization of the polyether amide, so that the flame retardant property of the polyether amide is effectively improved;

(2) the DOPO-based reactive flame retardant has the advantages that hydroxyl groups are used as active groups at two ends, the structure of the DOPO-based reactive flame retardant is similar to that of polyglycol, and the DOPO-based reactive flame retardant has small negative influence on the mechanical property of polyether amide;

(3) in the preparation method, the DOPO-based reactive flame retardant is added after the caprolactam oligomer carboxyl is blocked, so that the free flame retardant in the finished product slices is less, and the flame retardant in the modified polyether amide molecular chain is uniformly distributed.

Detailed Description

The present invention will be further described with reference to the following examples.

General examples

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

wherein R is one of aliphatic carbon chain, carbon chain containing benzene ring or carbon chain containing hetero atom.

The dibasic acid is adipic acid; the polyglycol is one or more of polyethylene glycol, polypropylene glycol and polybutylene glycol, and the molecular weight is 1000-4000; the ring-opening agent is water and/or aminocaproic acid; the polycondensation catalyst is tetrabutyl titanate.

The ratio of the mole number of the dibasic acid to the total mole number of the polyglycol and the DOPO-based reactive flame retardant is 1: 0.8-1.2; the mass fraction of the caprolactam is 50-90 wt%, the mass fraction of the polyglycol is 9-40 wt%, the mass fraction of the DOPO-based reaction type flame retardant is 1.5-8 wt%, the mass fraction of the ring opener is 2-6 wt%, and the content of the polycondensation reaction catalyst is 1-2 wt% of the polyglycol.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting caprolactam, adding the caprolactam, dibasic acid and a ring-opening agent into a reaction vessel, continuously stirring at the speed of 60-100 r/min, and carrying out ring-opening polymerization reaction at the temperature of 240-260 ℃ and under the pressure of 0.3-0.5 MPa for 2-3 h to obtain an oligomer;

(2) adding a DOPO-based reactive flame retardant into a reaction container, continuously stirring at the speed of 60-100 r/min, reacting for 0.5-1 h under normal pressure, reducing the pressure to 300-350 Pa, and continuously reacting for 2-3 h to obtain a polyamide prepolymer;

(3) adding polyglycol and a polycondensation reaction catalyst into a reaction container, continuously stirring at the speed of 60-100 r/min, reducing the pressure in the reaction container to be below 80Pa within 60-90 min, and carrying out polycondensation reaction at the temperature of 240-260 ℃ for 2-5 h to obtain the flame-retardant polyether amide.

Example 1

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

the preparation method of the DOPO-based reactive flame retardant comprises the following steps: adding DOPO and p-hydroxybenzaldehyde into ethylene glycol monomethyl ether, keeping the temperature at 90 ℃ for 30min under the protection of nitrogen, heating to 140 ℃ after all the DOPO and the p-hydroxybenzaldehyde are dissolved, reacting for 4h, decompressing and filtering after the reaction is finished to obtain a solid crude product, washing the solid crude product with a mixed solvent of ethyl acetate and petroleum ether for three times, and drying the solid crude product in vacuum at 80 ℃ for 10h to obtain white powder, namely the DOPO-based reactive flame retardant. The reaction process is as follows:

the dibasic acid is adipic acid; the polyglycol is polyethylene glycol, and the average molecular weight is 1000; the ring-opening agent is water; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting 900g of caprolactam at 90 ℃, adding the caprolactam, 32g of adipic acid and 36g of water into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotating speed of 90r/min, and carrying out ring-opening polymerization reaction at the temperature of 240 ℃ and the pressure of 0.4MPa for 3 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, 40g of DOPO-based reactive flame retardant powder is added, nitrogen is continuously introduced for reaction for 0.5h under the normal pressure, then the pressure in the reaction kettle is slowly reduced to 300Pa by a vacuum pump, the reaction is continued for 2h, and micromolecules such as water and the like are evaporated out to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 100g of polyethylene glycol and 1g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 90min, and carrying out polycondensation reaction at 260 ℃ for 2h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

Example 2

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

the preparation method of the DOPO-based reactive flame retardant comprises the following steps: respectively dissolving 54g of DOPO and 27g of p-benzoquinone in a toluene solution to obtain a DOPO solution and a p-benzoquinone solution; slowly adding the p-benzoquinone solution into the DOPO solution, and reacting for 5 hours at 80 ℃ under the protection of nitrogen; after the reaction is finished, cooling until a solid product is fully separated out, washing with toluene, carrying out suction filtration, and drying to obtain white powder, namely the DOPO-based reactive flame retardant. The reaction process is as follows:

the dibasic acid is adipic acid; the polyglycol is polyethylene glycol, and the average molecular weight is 1000; the ring-opening agent is aminocaproic acid; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting 800g of caprolactam at 80 ℃, adding the caprolactam, 65.2g of adipic acid and 24g of aminocaproic acid into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotating speed of 90r/min, and carrying out ring-opening polymerization reaction at the temperature of 240 ℃ and the pressure of 0.3MPa for 3 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, 80g of DOPO-based reactive flame retardant powder is added, nitrogen is continuously introduced for reaction for 1 hour under the normal pressure, then the pressure in the reaction kettle is slowly reduced to 300Pa by a vacuum pump, the reaction is continued for 3 hours, and micromolecules such as water and the like are evaporated to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 200g of polyethylene glycol and 2g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 80min, and carrying out polycondensation reaction at 240 ℃ for 5h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

Example 3

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

the preparation method of the DOPO-based reactive flame retardant comprises the following steps: mixing 43.2g of DOPO, 21g of diethanolamine and 100mL of deionized water, stirring and heating to 80 ℃, dripping 6.7g of paraformaldehyde after 10min, carrying out constant-temperature reflux reaction for 1h under the protection of nitrogen, cooling to room temperature, carrying out vacuum rotary evaporation to obtain a yellow colloidal substance, washing with absolute ethyl alcohol, and carrying out vacuum drying for 3h at 120 ℃ to obtain white powder, namely the DOPO-based reactive flame retardant. The reaction process is as follows:

the dibasic acid is adipic acid; the polyglycol is polytetramethylene glycol, and the average molecular weight is 1000; the ring-opening agent is aminocaproic acid; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting 700g of caprolactam at 80 ℃, adding the caprolactam, 52g of adipic acid and 42g of aminocaproic acid into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotating speed of 70r/min, and carrying out ring-opening polymerization reaction at 260 ℃ and 0.5MPa for 2 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, 20g of DOPO-based reactive flame retardant powder is added, nitrogen is continuously introduced to keep the normal pressure reaction for 0.5h, then the pressure in the reaction kettle is slowly reduced to 300Pa by a vacuum pump, and the reaction is continued for 3h to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 300g of polytetramethylene glycol and 3g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 80min, and carrying out polycondensation reaction at 260 ℃ for 2h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

Example 4

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

the preparation method of the DOPO-based reactive flame retardant comprises the following steps: melting 26.6g of diisopropanolamine at 60 ℃, adding 6.7g of paraformaldehyde, reacting for 4h, and distilling under reduced pressure for 6h after the reaction is finished to obtain a liquid intermediate product, namely 3- (2-hydroxyisopropyl) -5-methyloxazole; and adding 43.2g of DOPO powder into the intermediate product, adding 200mL of methanol, quickly stirring until most of DOPO disappears, heating to 55 ℃ for reaction for 6 hours, then decompressing to evaporate the methanol, and recrystallizing with ethyl acetate to obtain white powder, namely the DOPO-based reactive flame retardant. The reaction process is as follows:

the dibasic acid is adipic acid; the polyglycol is polytetramethylene glycol, and the average molecular weight is 1000; the ring-opening agent is aminocaproic acid; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting 600g of caprolactam at 80 ℃, adding the caprolactam, 83g of adipic acid and 30g of aminocaproic acid into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotating speed of 70r/min, and carrying out ring-opening polymerization reaction at 260 ℃ and 0.3MPa for 2 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, 60g of DOPO-based reactive flame retardant powder is added, nitrogen is continuously introduced for reaction for 0.5h, then the pressure in the reaction kettle is slowly reduced to 300Pa by a vacuum pump, the reaction is continued for 2h, and micromolecules such as water and the like are evaporated out to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 400g of polytetramethylene glycol and 4g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 60min, and carrying out polycondensation reaction at 240 ℃ for 5h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

Example 5

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

the preparation method of the DOPO-based reactive flame retardant comprises the following steps: mixing 43.2g of DOPO, 21g of diethanolamine and 100mL of deionized water, stirring and heating to 80 ℃, dripping 6.7g of paraformaldehyde after 10min, carrying out constant-temperature reflux reaction for 1h under the protection of nitrogen, cooling to room temperature, carrying out vacuum rotary evaporation to obtain a yellow colloidal substance, washing with absolute ethyl alcohol, and carrying out vacuum drying for 3h at 120 ℃ to obtain white powder, namely the DOPO-based reactive flame retardant. The reaction process is as follows:

the dibasic acid is adipic acid; the polyglycol is polyethylene glycol, and the average molecular weight is 1000; the ring-opening agent is water; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting 900g of caprolactam at 90 ℃, adding the caprolactam, 32g of adipic acid and 36g of water into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotating speed of 90r/min, and carrying out ring-opening polymerization reaction at the temperature of 240 ℃ and the pressure of 0.4MPa for 3 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, 39.4g of DOPO-based reactive flame retardant powder is added, nitrogen is continuously introduced for reaction for 0.5h, then the pressure in the reaction kettle is slowly reduced to 300Pa by a vacuum pump, the reaction is continued for 2h, and micromolecules such as water and the like are evaporated out to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 100g of polyethylene glycol and 1g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 90min, and carrying out polycondensation reaction at 260 ℃ for 2h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

Example 6

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

the preparation method of the DOPO-based reactive flame retardant comprises the following steps: melting 26.6g of diisopropanolamine at 60 ℃, adding 6.7g of paraformaldehyde, reacting for 4h, and distilling under reduced pressure for 6h after the reaction is finished to obtain a liquid intermediate product, namely 3- (2-hydroxyisopropyl) -5-methyloxazole; and adding 43.2g of DOPO powder into the intermediate product, adding 200mL of methanol, quickly stirring until most of DOPO disappears, heating to 55 ℃ for reaction for 6 hours, then decompressing to evaporate the methanol, and recrystallizing with ethyl acetate to obtain white powder, namely the DOPO-based reactive flame retardant. The reaction process is as follows:

the dibasic acid is adipic acid; the polyglycol is polyethylene glycol, and the average molecular weight is 1000; the ring-opening agent is water; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting 900g of caprolactam at 90 ℃, adding the caprolactam, 32g of adipic acid and 36g of water into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotating speed of 90r/min, and carrying out ring-opening polymerization reaction at the temperature of 240 ℃ and the pressure of 0.4MPa for 3 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, 42.7g of DOPO-based reactive flame retardant powder is added, nitrogen is continuously introduced for reaction for 0.5h, then the pressure in the reaction kettle is slowly reduced to 300Pa by a vacuum pump, the reaction is continued for 2h, and micromolecules such as water and the like are evaporated out to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 100g of polyethylene glycol and 1g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 90min, and carrying out polycondensation reaction at 260 ℃ for 2h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

Comparative example 1

A polyether amide contains caprolactam, polydihydric alcohol, dibasic acid, ring-opening agent and polycondensation catalyst.

The dibasic acid is adipic acid; the polyglycol is polyethylene glycol, and the average molecular weight is 1000; the ring-opening agent is water; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the polyether amide comprises the following steps:

(1) melting 900g of caprolactam at 90 ℃, adding the caprolactam, 14.6g of adipic acid and 36g of water into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotating speed of 90r/min, and carrying out ring-opening polymerization reaction at the temperature of 240 ℃ and the pressure of 0.4MPa for 3 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, continuously introducing nitrogen to maintain the normal pressure for 0.5h, then slowly reducing the pressure in the reaction kettle to 300Pa by using a vacuum pump, and maintaining the pressure for 2h to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 100g of polyethylene glycol and 1g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 90min, and carrying out polycondensation reaction at 260 ℃ for 2h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

Comparative example 2

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

the preparation method of the DOPO-based reactive flame retardant comprises the following steps: adding DOPO and p-hydroxybenzaldehyde into ethylene glycol monomethyl ether, keeping the temperature at 90 ℃ for 30min under the protection of nitrogen, heating to 140 ℃ after all the DOPO and the p-hydroxybenzaldehyde are dissolved, reacting for 4h, decompressing and filtering after the reaction is finished to obtain a solid crude product, washing the solid crude product with a mixed solvent of ethyl acetate and petroleum ether for three times, and drying the solid crude product in vacuum at 80 ℃ for 10h to obtain white powder, namely the DOPO-based reactive flame retardant. The reaction process is as follows:

the dibasic acid is adipic acid; the polyglycol is polyethylene glycol, and the average molecular weight is 1000; the ring-opening agent is water; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting 900g of caprolactam at 90 ℃, adding the caprolactam, 64g of adipic acid and 36g of water into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotation speed of 90r/min, and carrying out ring-opening polymerization reaction at 240 ℃ and 0.4MPa for 3 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, 40g of DOPO-based reactive flame retardant powder is added, nitrogen is continuously introduced to keep the normal pressure reaction for 0.5h, then the pressure in the reaction kettle is slowly reduced to 300Pa by a vacuum pump, the reaction is continued for 2h, and micromolecules such as water and the like are evaporated out to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 100g of polyethylene glycol and 1g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 90min, and carrying out polycondensation reaction at 260 ℃ for 2h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

Comparative example 3

A modified polyether amide of DOPO-based reactive flame retardant comprises caprolactam, polydihydric alcohol, dibasic acid, DOPO-based reactive flame retardant, ring-opening agent and polycondensation reaction catalyst.

The DOPO-based reactive flame retardant has the structural formula:

the preparation method of the DOPO-based reactive flame retardant comprises the following steps: adding DOPO and p-hydroxybenzaldehyde into ethylene glycol monomethyl ether, keeping the temperature at 90 ℃ for 30min under the protection of nitrogen, heating to 140 ℃ after all the DOPO and the p-hydroxybenzaldehyde are dissolved, reacting for 4h, decompressing and filtering after the reaction is finished to obtain a solid crude product, washing the solid crude product with a mixed solvent of ethyl acetate and petroleum ether for three times, and drying the solid crude product in vacuum at 80 ℃ for 10h to obtain white powder, namely the DOPO-based reactive flame retardant. The reaction process is as follows:

the dibasic acid is adipic acid; the polyglycol is polyethylene glycol, and the average molecular weight is 1000; the ring-opening agent is water; the polycondensation catalyst is tetrabutyl titanate.

A preparation method of the flame-retardant polyether amide comprises the following steps:

(1) melting 900g of caprolactam at 90 ℃, adding the caprolactam, 21.3g of adipic acid and 36g of water into a polymerization kettle, discharging air in the kettle by using nitrogen, starting stirring at the rotating speed of 90r/min, and carrying out ring-opening polymerization reaction at the temperature of 240 ℃ and the pressure of 0.4MPa for 3 hours to obtain an oligomer;

(2) after the pressure in the polymerization kettle is relieved to the normal pressure, 40g of DOPO-based reactive flame retardant powder is added, nitrogen is continuously introduced to keep the normal pressure reaction for 0.5h, then the pressure in the reaction kettle is slowly reduced to 300Pa by a vacuum pump, the reaction is continued for 2h, and micromolecules such as water and the like are evaporated out to obtain a polyamide prepolymer;

(3) filling a polymerization kettle to normal pressure by using nitrogen, adding 100g of polyethylene glycol and 1g of tetrabutyl titanate, sealing, reducing the pressure of the polymerization kettle to be below 80Pa within 90min, and carrying out polycondensation reaction at 260 ℃ for 2h to obtain flame-retardant polyether amide;

(4) and (3) the flame-retardant polyether amide enters a water tank from the bottom of the polymerization kettle, and is cast and cut into particles to obtain flame-retardant polyether amide slices.

The relative viscosity of the flame-retardant polyether amide prepared in examples 1 to 6 and comparative examples 1 to 3, and the flame retardant property and mechanical property of the cut sheet were measured, and the results are shown in table 1.

TABLE 1 Properties of flame-retardant Polyetheramide chips

Example 1 used a DOPO-based reactive flame retardant and comparative example 1 did not add a flame retardant. As can be seen from Table 1, compared with comparative example 1, the modified polyether amide prepared in example 1 has significantly improved flame retardant property, and the tensile strength, elongation at break and impact strength are respectively reduced by 7%, 5% and 5%, which shows that the flame retardant property of polyether amide can be effectively improved by using the DOPO-based reactive flame retardant of the present invention, and the negative effect on the mechanical property of polyether amide is small, because: the DOPO-based reactive flame retardant has two hydroxyl active groups at two ends, is similar to a polyglycol structure, introduces flame-retardant and heat-resistant groups into a molecular chain of polyether amide, and has better compatibility with the polyether amide, so that the negative influence on the mechanical property of the polyether amide is reduced under the condition of effectively improving the flame retardance of the polyether amide.

Examples 1, 5 and 6 used equimolar amounts of different DOPO-based reactive flame retardants, and other raw materials and preparation processes were the same. As can be seen from Table 1, the flame retardant polyetheramides obtained in examples 5 and 6 have better flame retardant properties than those obtained in example 1. The reason is that: the DOPO-based reactive flame retardant prepared by the methods of the embodiment 5 and the embodiment 6 can introduce two hydroxyl groups and nitrogen elements, and can play a synergistic effect with a phosphorus flame retardant to improve the flame retardant effect.

In example 1, comparative example 2 and comparative example 3, the ratios of the number of moles of the dibasic acid to the total number of moles of the polyglycol and the DOPO-based reactive flame retardant were 1:1, 1:0.5 and 1:1.5, respectively, and the other raw materials and the preparation process were the same. As can be seen from Table 1, the flame retardant polyetheramides obtained in comparative examples 2 and 3 had significantly lower viscosities than those of example 1, and were not pelletized into strands. The reason is that: because both ends of the oligomer prepared in the step (1) are terminated by carboxyl, the mole number of the dibasic acid is the mole number of the oligomer, and the ratio of the mole number of the dibasic acid in the raw material to the total mole number of the polyglycol and the DOPO-based reactive flame retardant is the mole number ratio of the carboxyl to the hydroxyl after the DOPO-based reactive flame retardant and the polyglycol are subsequently added, so that the excessive or insufficient ratio can cause that in the reaction process of the step (3), the product is terminated by the carboxyl or the hydroxyl and cannot continue to perform polycondensation reaction, and the molecular weight of the generated flame-retardant polyether amide is too small and the viscosity is too low.

The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.