Flame retardant copolyester material and preparation method thereof

Abstract

The present invention discloses a flame-retardant copolyester material and a preparation method thereof. A reactive triazine-based organic flame retardant uses a triazine ring structure as a nitrogen source and 2,6,7-trioxa-1-phosphabicyclo (2.2.2) octane-4-methanol-1-oxide as a phosphorus source to form a nitrogen-phosphorus synergistic flame retardant system. In the absence of a catalyst, a diol, a dicarboxylic acid and / or a dibasic acid anhydride and / or a dibasic acid ester and a reactive triazine-based organic flame retardant pass through an esterification stage and a polycondensation stage, and then a triazine-based flame retardant component is introduced into the polyester backbone to prepare a synthetic high-molecular-weight flame-retardant copolyester. The introduction of the reactive triazine-based flame retardant helps the flame-retardant copolyester to form an expanded carbon layer on its surface during combustion, thereby isolating heat propagation and suppressing melt dripping. The introduction of the triazine-based flame retardant gives the copolyester an excellent flame retardant effect and good mechanical properties.

Description

Technical Field

[0001] The present invention relates to the field of flame retardant technology, in particular to a flame retardant copolyester material and a preparation method thereof. Background Art

[0002] Polyesters are a type of polymer material containing ester bonds in their backbone. Polyesters are categorized as aromatic or aliphatic depending on whether they contain aromatic rings. Polyesters are widely used in industries such as food packaging and textiles due to their potential for biodegradability and excellent processability. However, most polyesters are flammable and can drip during combustion, potentially spreading the fire and causing potential damage to life and property.

[0003] Currently, flame-retardant polyester materials are typically blended with intumescent flame retardants, introducing nitrogen- and phosphorus-containing flame retardants. This creates an intumescent char layer during combustion, inhibiting melt dripping. However, traditional intumescent flame retardants have poor compatibility with most polyesters and require a large addition amount. The addition of large amounts of intumescent flame retardants reduces the mechanical properties and ductility of flame-retardant polyester materials, limiting their widespread application.

[0004] The typical industrial route for large-scale polyester synthesis is the melt polycondensation of dicarboxylic acids and diols, with the addition of typical metal catalysts (such as germanium, antimony, and titanium) to increase the molecular weight of the polyester product. However, heavy metals in metal catalysts can pose significant risks to human health and the natural environment. Generally speaking, the use of less toxic organic catalysts and more efficient catalysts can effectively reduce the hazards of metal catalysts. However, the catalytic activity of organic catalysts is far lower than that of traditional metal catalysts, requiring larger dosages. Furthermore, more efficient catalysts have more side reactions, which reduce monomer utilization and product purity.

[0005] Patent CN110790906B proposes using diols and an excess molar ratio of cyclic dicarboxylic acids or anhydrides as raw materials to synthesize high molecular weight aliphatic polyesters with properties comparable to commercial polyester materials, avoiding problems associated with catalysts.

[0006] Patent publication number CN115679470A discloses a dicarboxy triazine phosphate flame retardant. This reactive flame retardant undergoes an ester exchange and polycondensation reaction with dimethyl terephthalate and ethylene glycol, thereby grafting the triazine phosphate flame retardant onto the PET polyester chain. The triazine phosphate uses the triazine ring as a nitrogen source and a tetrafunctional dioxahexanoyl phosphate as a phosphorus source, forming a nitrogen-phosphorus synergistic flame retardant system. This system promotes the dehydration of PET fibers into charcoal, forming an expanded char layer on the surface. This layer provides thermal insulation and oxygen isolation during combustion, preventing melt dripping and exhibiting excellent flame retardancy. Summary of the Invention

[0007] The invention provides a flame retardant copolyester material and a preparation method thereof.

[0008] The present invention first synthesizes a novel reactive triazine-based organic flame retardant. This reactive triazine-based organic flame retardant uses a triazine ring structure as a nitrogen source and 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide as a phosphorus source, forming a nitrogen-phosphorus synergistic flame retardant system. In the absence of a catalyst, diols, dicarboxylic acids and / or dibasic acid anhydrides and / or dibasic acid esters are reacted with the reactive triazine-based organic flame retardant through esterification and polycondensation stages. The triazine-based flame retardant component is then incorporated into the polyester backbone to prepare a high-molecular-weight flame-retardant copolyester. The introduction of the reactive triazine-based flame retardant helps form an intumescent char layer on the surface of the flame-retardant copolyester during combustion, insulating it from heat transfer and further suppressing melt dripping. Tensile testing, limiting oxygen index testing, and the UL-94 vertical burn test demonstrate that the triazine-based flame retardant imparts excellent flame retardancy to the copolyester, while also exhibiting good mechanical properties.

[0009] A method for preparing a flame-retardant copolyester material, comprising:

[0010] Esterification stage: Under the condition of no catalyst, diol, reactive triazine-based organic flame retardant and cyclic dicarboxylic acid and / or corresponding acid anhydride and / or corresponding acid ester are used as raw materials to carry out esterification reaction to obtain a carboxyl-terminated prepolymer; the reactive triazine-based organic flame retardant and cyclic dicarboxylic acid and / or corresponding acid anhydride and / or corresponding acid ester are in excess relative to the diol;

[0011] Polycondensation stage: under reduced pressure, controlling the reaction temperature to be not lower than the boiling point of the anhydride corresponding to the cyclic dicarboxylic acid, removing the anhydride corresponding to the cyclic dicarboxylic acid from the carboxyl-terminated prepolymer to obtain the flame-retardant copolyester material;

[0012] The method for preparing the reactive triazine-based organic flame retardant comprises the following steps:

[0013] (1) adding 2,4,6-trichloro-1,3,5-triazine and 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide to a first organic solvent, heating to 90-120° C. under inert gas protection for reaction, removing the solvent after the reaction, washing and drying the obtained crude product to obtain an intermediate product;

[0014] (2) adding the compound NH2-R-COOH and the intermediate product of step (1) to a second organic solvent, heating the mixture to 100-150°C for reaction, removing the solvent after the reaction, washing and drying the obtained solid, and obtaining the reactive triazine-based organic flame retardant; wherein R is an alkylene group containing 1 to 18 carbon atoms.

[0015] The chemical structure of the reactive triazine-based organic flame retardant provided by the present invention can be expressed as follows:

[0016]

[0017] Wherein, R is an alkylene group containing 1 to 18 carbon atoms.

[0018] In the present invention, an alkylene group refers to an alkane having lost two hydrogen atoms, and the alkane may be a straight-chain alkane, a branched-chain alkane, a cyclic alkane, or the like.

[0019] In step (1), the first organic solvent may be acetonitrile.

[0020] In step (1), the molar ratio of 2,4,6-trichloro-1,3,5-triazine to 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide may be 1:1.05 to 1.5.

[0021] In step (1), the inert gas may be a rare gas and / or nitrogen.

[0022] In step (1), the reaction can be carried out under conditions of continuous stirring and condensation reflux.

[0023] In step (1), the reaction time can be 9 to 18 hours.

[0024] In step (1), the washing may be performed using acetone and / or ethyl acetate.

[0025] In step (2), for example, the compound NH2-R-COOH may include at least one of glycine, alanine, leucine, isoleucine, methionine, proline, phenylalanine, tryptophan, valine, etc.

[0026] In step (2), the second organic solvent may be N,N-diisopropylethylamine.

[0027] In step (2), the molar ratio of the intermediate product to the compound NH2-R-COOH can be 1:2.1 to 2.8, more preferably 1:2.1 to 2.4. In the further preferred case, the product yield meets the requirements and the raw material consumption is less.

[0028] In step (2), the reaction time can be 12 to 18 hours.

[0029] In step (2), the washing may be performed using acetone.

[0030] In the preparation method of the flame-retardant copolyester material, the diol can be selected from at least one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-cyclohexanedimethanol, phenyl glycol, catechol, resorcinol, hydroquinone, 1,3-adamantanediol, and 1,1-cyclopropane dimethanol.

[0031] In the preparation method of the flame-retardant copolyester material, the cyclic dicarboxylic acid can be selected from at least one of oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, phthalic acid, 5-sodium sulfoisophthalate, 5-sodium sulfoterephthalate, 2,5-furandicarboxylic acid, and 2,6-naphthalene dicarboxylic acid.

[0032] In the preparation method of the flame-retardant copolyester material, the acid anhydride can be selected from at least one of succinic anhydride, glutaric anhydride, maleic anhydride, adipic anhydride, phthalic anhydride, maleic anhydride, 1,2-naphthalene dicarboxylic anhydride, 2,3-pyrazine dicarboxylic anhydride and 2,3-pyridinedicarboxylic anhydride.

[0033] In the method for preparing the flame-retardant copolyester material, the acid ester can be selected from at least one of dimethyl succinate, diethyl succinate, dimethyl fumarate, dimethyl glutarate, dimethyl adipate, dimethyl terephthalate, and dimethyl 2,5-furandicarboxylate.

[0034] In the preparation method of the flame-retardant copolyester material, the molar ratio of the diol to the cyclic dicarboxylic acid and / or the corresponding acid anhydride and / or the corresponding acid ester can be 1:1.05-2, more preferably 1:1.05-1.5. In the further preferred case, the product yield meets the requirements and the raw material consumption is less.

[0035] In the preparation method of the flame-retardant copolyester material, the total addition amount of the reactive triazine organic flame retardant can be 1wt% to 15wt%, based on the sum of the mass of the diol and the cyclic dicarboxylic acid and / or the corresponding anhydride and / or the corresponding acid ester being 100%.

[0036] In the method for preparing the flame-retardant copolyester material, the esterification stage can be carried out in an inert gas atmosphere. The inert gas can be a rare gas and / or nitrogen.

[0037] In the method for preparing the flame-retardant copolyester material, the temperature of the esterification reaction in the esterification stage can be 160 to 220° C., and the time can be 8 to 16 hours.

[0038] In the preparation method of the flame-retardant copolyester material, the reaction temperature in the polycondensation stage can be 210-280°C, more preferably 240-280°C. The temperature in the polycondensation stage is low and the reaction rate is slow. In the more preferred case, the reaction rate is faster, the reaction pressure can be lower than 100 Pa, and the reaction time can be 8-24 hours.

[0039] The present invention also provides a flame retardant copolyester material prepared by the method for preparing the flame retardant copolyester material.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention proposes a novel flame retardant containing a triazine ring structure that can be used for polyester polymerization and a preparation method thereof. The novel flame retardant is applied to the synthesis of flame-retardant copolyesters under catalyst-free conditions to obtain a copolyester material with a molecular weight equivalent to that of commercial polyester, and has both good mechanical properties and excellent flame retardant properties.

[0042] The flame-retardant copolyester structure of the present invention incorporates a reactive flame retardant containing a triazine ring and 2,6,7-trioxa-1-phosphabicyclo (2.2.2) octane-4-methanol-1-oxide into the polyester backbone. The triazine ring serves as a nitrogen source, and the 2,6,7-trioxa-1-phosphabicyclo (2.2.2) octane-4-methanol-1-oxide component serves as a phosphorus source, forming a nitrogen-phosphorus synergistic flame retardant system. During combustion, the flame-retardant copolyester material forms an expanded char layer on its surface, isolating it from heat and oxygen, further suppressing melt dripping and reducing the risk of fire spread. This helps protect personal and property safety and broadens the application areas of polyester materials. DETAILED DESCRIPTION

[0043] The present invention will be further described below with reference to specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0044] Example 1

[0045]

[0046] Preparation method of reactive triazine organic flame retardant:

[0047] (1) 2,4,6-trichloro-1,3,5-triazine (8 g), 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide (10.68 g) and acetonitrile (100 mL) were added to a flask. The temperature was raised to 100°C under argon protection. A condenser was connected, magnetic stirring was applied, and the mixture was refluxed. After reacting for 14 h, the acetonitrile solvent was removed by rotary evaporation. The crude product was washed with ethyl acetate several times, centrifuged, and the supernatant was discarded. The product was collected and dried in vacuo at 40°C for 12 h. The product was collected for use to obtain the intermediate product with a yield of 67.8%.

[0048] (2) The intermediate product (6 g) of (1), alanine (3.59 g) and N,N-diisopropylethylamine (150 mL) were added to a flask, heated to 120°C, and the reaction was continued for 18 h. After cooling, the N,N-diisopropylethylamine solvent was removed by rotary evaporation. The crude product was washed with acetone several times, centrifuged and the supernatant was discarded, and the product was collected. After vacuum drying at 80°C for 12 h, the product was collected for use to obtain a reactive triazine-based organic flame retardant with a yield of 70.5%.

[0049] Synthesis of flame-retardant polybutylene succinate copolyester under catalyst-free conditions:

[0050] Esterification stage: Succinic acid (14.4 g), 1,4-butanediol (10 g) and the triazine organic flame retardant prepared above (0.976 g) were added to a 250 mL three-necked flask, heated to 200 ° C, and reacted with stirring at 200 rpm. Argon was introduced to exhaust the air in the device and take out the water and other small molecular products produced by esterification. After 10 hours of reaction, no water was produced in the system and the reaction was stopped to obtain a prepolymer of polybutylene succinate copolyester.

[0051] Condensation stage: stop the argon flow, connect the three-necked flask to a vacuum oil pump and evacuate the flask, gradually raise the temperature to 220°C, and keep the pressure in the flask less than 100 Pa. Perform the polymerization reaction under stirring at 200 rpm for 18 hours to obtain polybutylene succinate copolyester with a viscosity-average molecular weight of 43 kDa and an intrinsic viscosity of 0.81 dL / g.

[0052] Example 2

[0053] Preparation method of reactive triazine organic flame retardant:

[0054] (1) 2,4,6-trichloro-1,3,5-triazine (8 g), 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide (10.68 g) and acetonitrile (100 mL) were added to a flask. The temperature was raised to 100°C under argon protection. A condenser was connected, magnetic stirring was applied, and the mixture was refluxed. After reacting for 14 h, the acetonitrile solvent was removed by rotary evaporation. The crude product was washed with ethyl acetate several times, centrifuged, and the supernatant was discarded. The product was collected and dried in vacuo at 40°C for 12 h. The product was collected for use to obtain the intermediate product with a yield of 67.8%.

[0055] (2) The intermediate product (6 g) of (1), alanine (3.59 g) and N,N-diisopropylethylamine (150 mL) were added to a flask, heated to 120°C, and the reaction was continued for 18 h. After cooling, the N,N-diisopropylethylamine solvent was removed by rotary evaporation. The crude product was washed with acetone several times, centrifuged and the supernatant was discarded, and the product was collected. After vacuum drying at 80°C for 12 h, the product was collected for use to obtain a reactive triazine-based organic flame retardant with a yield of 70.5%.

[0056] Synthesis of flame-retardant polybutylene succinate copolyester under catalyst-free conditions:

[0057] Esterification stage: Succinic acid (14.4 g), 1,4-butanediol (10 g) and the triazine organic flame retardant prepared above (0.488 g) were added to a 250 mL three-necked flask, heated to 200 ° C, and reacted with stirring at 200 rpm. Argon was introduced to exhaust the air in the device and take out the water and other small molecular products produced by esterification. After 10 hours of reaction, no water was produced in the system and the reaction was stopped to obtain a prepolymer of polybutylene succinate copolyester.

[0058] Polycondensation stage: stop the argon flow, and connect the three-necked flask to a vacuum oil pump to evacuate the flask, gradually raise the temperature to 220°C, and the pressure in the three-necked flask is less than 100 Pa. The polymerization reaction is carried out under stirring at 200 rpm for 18 hours to obtain polybutylene succinate copolyester with a viscosity-average molecular weight of 45 kDa and an intrinsic viscosity of 0.85 dL / g.

[0059] Example 3

[0060] Preparation method of reactive triazine organic flame retardant:

[0061] (1) 2,4,6-trichloro-1,3,5-triazine (8 g), 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide (10.68 g) and acetonitrile (100 mL) were added to a flask. The temperature was raised to 100°C under argon protection. A condenser was connected, magnetic stirring was applied, and the mixture was refluxed. After reacting for 14 h, the acetonitrile solvent was removed by rotary evaporation. The crude product was washed with ethyl acetate several times, centrifuged, and the supernatant was discarded. The product was collected and dried in vacuo at 40°C for 12 h. The product was collected for use to obtain the intermediate product with a yield of 67.8%.

[0062] (2) The intermediate product (6 g) of step (1), glycine (3.30 g) and N, N-diisopropylethylamine (150 mL) were added to a flask, the temperature was raised to 120°C, the reaction was continued for 18 h, and the N, N-diisopropylethylamine solvent was removed by rotary evaporation after cooling. The crude product was washed with acetone several times, centrifuged and the supernatant was discarded, the product was collected, and vacuum dried at 80°C for 12 h. The product was collected for use to obtain a reactive triazine-based organic flame retardant with a yield of 72.9%.

[0063] Synthesis of flame-retardant polybutylene succinate copolyester under catalyst-free conditions:

[0064] Esterification stage: Succinic acid (14.4 g), 1,4-butanediol (10 g) and the triazine organic flame retardant prepared above (0.976 g) were added to a 250 mL three-necked flask, heated to 200 ° C, and reacted with stirring at 200 rpm. Argon was introduced to exhaust the air in the device and take out the water and other small molecular products produced by esterification. After 10 hours of reaction, no water was produced in the system and the reaction was stopped to obtain a prepolymer of polybutylene succinate copolyester.

[0065] Condensation stage: stop the argon flow, connect the three-necked flask to a vacuum oil pump and evacuate the flask, gradually raise the temperature to 220°C, and keep the pressure in the flask less than 100 Pa. Perform the polymerization reaction under stirring at 200 rpm for 18 hours to obtain polybutylene succinate copolyester with a viscosity-average molecular weight of 50 kDa and an intrinsic viscosity of 0.90 dL / g.

[0066] Example 4

[0067] Preparation method of reactive triazine organic flame retardant:

[0068] (1) 2,4,6-trichloro-1,3,5-triazine (8 g), 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide (10.68 g) and acetonitrile (100 mL) were added to a flask. The temperature was raised to 100°C under argon protection. A condenser was connected, magnetic stirring was applied, and the mixture was refluxed. After reacting for 14 h, the acetonitrile solvent was removed by rotary evaporation. The crude product was washed with ethyl acetate several times, centrifuged, and the supernatant was discarded. The product was collected and dried in vacuo at 40°C for 12 h. The product was collected for use to obtain the intermediate product with a yield of 67.8%.

[0069] (2) The intermediate product (6 g) of step (1), glycine (3.30 g) and N, N-diisopropylethylamine (150 mL) were added to a flask, the temperature was raised to 120°C, the reaction was continued for 18 h, and the N, N-diisopropylethylamine solvent was removed by rotary evaporation after cooling. The crude product was washed with acetone several times, centrifuged and the supernatant was discarded, the product was collected, and vacuum dried at 80°C for 12 h. The product was collected for use to obtain a reactive triazine-based organic flame retardant with a yield of 72.9%.

[0070] Synthesis of flame-retardant polybutylene succinate copolyester under catalyst-free conditions:

[0071] Esterification stage: Succinic acid (14.4 g), 1,4-butanediol (10 g) and the triazine organic flame retardant prepared above (0.488 g) were added to a 250 mL three-necked flask, heated to 200 ° C, and reacted with stirring at 200 rpm. Argon was introduced to exhaust the air in the device and take out the water and other small molecular products produced by esterification. After 10 hours of reaction, no water was produced in the system and the reaction was stopped to obtain a prepolymer of polybutylene succinate copolyester.

[0072] Condensation stage: stop the argon flow, connect the three-necked flask to a vacuum oil pump and evacuate the flask, gradually raise the temperature to 220°C, and keep the pressure in the flask less than 100 Pa. Perform the polymerization reaction under stirring at 200 rpm for 18 hours to obtain polybutylene succinate copolyester with a viscosity-average molecular weight of 44 kDa and an intrinsic viscosity of 0.83 dL / g.

[0073] Example 5

[0074] Preparation method of reactive triazine organic flame retardant:

[0075] (1) 2,4,6-trichloro-1,3,5-triazine (8 g), 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide (10.68 g) and acetonitrile (100 mL) were added to a flask. The temperature was raised to 100°C under argon protection. A condenser was connected, magnetic stirring was applied, and the mixture was refluxed. After reacting for 14 h, the acetonitrile solvent was removed by rotary evaporation. The crude product was washed with ethyl acetate several times, centrifuged, and the supernatant was discarded. The product was collected and dried in vacuo at 40°C for 12 h. The product was collected for use to obtain the intermediate product with a yield of 67.8%.

[0076] (2) The intermediate product (6 g) of step (1), leucine (5.76 g) and N, N-diisopropylethylamine (150 mL) were added to a flask, the temperature was raised to 120°C, the reaction was continued for 18 h, and the N, N-diisopropylethylamine solvent was removed by rotary evaporation after cooling. The crude product was washed with acetone several times, centrifuged and the supernatant was discarded, the product was collected, and vacuum dried at 80°C for 12 h. The product was collected for use to obtain a reactive triazine-based organic flame retardant with a yield of 71.3%.

[0077] Synthesis of flame-retardant polybutylene succinate copolyester under catalyst-free conditions:

[0078] Esterification stage: Succinic acid (14.4 g), 1,4-butanediol (10 g) and the triazine organic flame retardant prepared above (0.976 g) were added to a 250 mL three-necked flask, heated to 200 ° C, and reacted with stirring at 200 rpm. Argon was introduced to exhaust the air in the device and take out the water and other small molecular products produced by esterification. After 10 hours of reaction, no water was produced in the system and the reaction was stopped to obtain a prepolymer of polybutylene succinate copolyester.

[0079] Condensation stage: stop the argon flow, connect the three-necked flask to a vacuum oil pump and evacuate the flask, gradually raise the temperature to 220°C, and keep the pressure in the flask less than 100 Pa. Perform the polymerization reaction under stirring at 200 rpm for 18 hours to obtain polybutylene succinate copolyester with a viscosity-average molecular weight of 47 kDa and an intrinsic viscosity of 0.87 dL / g.

[0080] Example 6

[0081] Preparation method of reactive triazine organic flame retardant:

[0082] (1) 2,4,6-trichloro-1,3,5-triazine (8 g), 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide (10.68 g) and acetonitrile (100 mL) were added to a flask. The temperature was raised to 100°C under argon protection. A condenser was connected, magnetic stirring was applied, and the mixture was refluxed. After reacting for 14 h, the acetonitrile solvent was removed by rotary evaporation. The crude product was washed with ethyl acetate several times, centrifuged, and the supernatant was discarded. The product was collected and dried in vacuo at 40°C for 12 h. The product was collected for use to obtain the intermediate product with a yield of 67.8%.

[0083] (2) The intermediate product (6 g) of step (1), leucine (5.76 g) and N, N-diisopropylethylamine (150 mL) were added to a flask, the temperature was raised to 120°C, the reaction was continued for 18 h, and the N, N-diisopropylethylamine solvent was removed by rotary evaporation after cooling. The crude product was washed with acetone several times, centrifuged and the supernatant was discarded, the product was collected, and vacuum dried at 80°C for 12 h. The product was collected for use to obtain a reactive triazine-based organic flame retardant with a yield of 71.3%.

[0084] Synthesis of flame-retardant polybutylene succinate copolyester under catalyst-free conditions:

[0085] Esterification stage: Succinic acid (14.4 g), 1,4-butanediol (10 g) and the triazine organic flame retardant prepared above (0.488 g) were added to a 250 mL three-necked flask, heated to 200 ° C, and reacted with stirring at 200 rpm. Argon was introduced to exhaust the air in the device and take out the water and other small molecular products produced by esterification. After 10 hours of reaction, no water was produced in the system and the reaction was stopped to obtain a prepolymer of polybutylene succinate copolyester.

[0086] Condensation stage: stop the argon flow, connect the three-necked flask to a vacuum oil pump and evacuate the flask, gradually raise the temperature to 220°C, and keep the pressure in the flask less than 100 Pa. Perform the polymerization reaction under stirring at 200 rpm for 18 hours to obtain polybutylene succinate copolyester with a viscosity-average molecular weight of 49 kDa and an intrinsic viscosity of 0.89 dL / g.

[0087] Comparative Example 1

[0088] Synthesis of polybutylene succinate under catalyst-free conditions:

[0089] Esterification stage: Add succinic acid (14.4 g) and 1,4-butanediol (10 g) into a 250 mL three-necked flask, heat to 200 ° C, and react with stirring at 200 rpm. Enter argon to exhaust the air in the device and take out the water and other small molecular products produced by esterification. After 10 hours of reaction, the reaction is stopped when no water is produced in the system to obtain a prepolymer of polybutylene succinate.

[0090] Condensation stage: stop the argon flow, connect the three-necked flask to a vacuum oil pump and evacuate the flask, gradually raise the temperature to 220°C, and keep the pressure in the flask less than 100 Pa. Perform the polymerization reaction under stirring at 200 rpm for 18 hours to obtain polybutylene succinate copolyester with a viscosity-average molecular weight of 48 kDa and an intrinsic viscosity of 0.88 dL / g.

[0091] The polybutylene succinate copolyester materials prepared in the above embodiments and comparative examples were subjected to a tensile property test, a limiting oxygen index test (GB / T2406-93 standard) and a UL-94 vertical burning test.

[0092] Table 1 shows the performance test results of the polybutylene succinate copolyester materials of the above embodiments and comparative examples.

[0093] Table 1

[0094] sample Tensile strength / MPa Limiting oxygen index / % UL-94(3.2mm) Example 1 30.78 34.4 V-0 Example 2 29.86 32.2 V-0 Example 3 31.77 37.3 V-0 Example 4 32.08 38.1 V-0 Example 5 28.62 30.4 V-1 Example 6 32.14 31.2 V-1 Comparative Example 1 35.76 22.6 NR

[0095] Note: NR means No Result.

[0096] As shown in Table 1, compared with the polybutylene succinate in Comparative Example 1, the flame-retardant polybutylene succinate copolyester in the embodiment has an improved limiting oxygen index and has excellent mechanical properties, flame retardant properties and melt dripping resistance.

[0097] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a flame retardant copolyester material, characterized in that: include: Esterification stage: Under the condition of no catalyst, diol, reactive triazine-based organic flame retardant and cyclic dicarboxylic acid and / or corresponding acid anhydride and / or corresponding acid ester are used as raw materials to carry out esterification reaction to obtain a carboxyl-terminated prepolymer; the reactive triazine-based organic flame retardant and cyclic dicarboxylic acid and / or corresponding acid anhydride and / or corresponding acid ester are in excess relative to the diol; Polycondensation stage: under reduced pressure, controlling the reaction temperature to be not lower than the boiling point of the anhydride corresponding to the cyclic dicarboxylic acid, removing the anhydride corresponding to the cyclic dicarboxylic acid from the carboxyl-terminated prepolymer to obtain the flame-retardant copolyester material; The method for preparing the reactive triazine-based organic flame retardant comprises the following steps: (1) Add 2,4,6-trichloro-1,3,5-triazine and 2,6,7-trioxa-1-phosphabicyclo (2.2.2) octane-4-methanol-1-oxide to the first organic solvent, and heat to 90-120°C under the protection of inert gas for reaction. After the reaction is completed, remove the solvent, wash and dry the obtained crude product to obtain an intermediate product; (2) Adding the compound NH2-R-COOH and the intermediate product of step (1) to a second organic solvent, heating the mixture to 100-150°C for reaction, removing the solvent after the reaction, washing and drying the obtained solid, and obtaining the reactive triazine-based organic flame retardant; wherein R is an alkylene group containing 1-18 carbon atoms.

2. The preparation method according to claim 1, characterized in that In step (1): The first organic solvent is acetonitrile; The molar ratio of 2,4,6-trichloro-1,3,5-triazine to 2,6,7-trioxa-1-phosphabicyclo(2.2.2)octane-4-methanol-1-oxide is 1:1.05-1.5; The inert gas is a rare gas and / or nitrogen; The reaction is carried out under conditions of continuous stirring and condensation reflux; The reaction time of the reaction is 9 to 18 h; The washing is performed using acetone and / or ethyl acetate.

3. The preparation method according to claim 1, characterized in that In step (2): The second organic solvent is N,N-diisopropylethylamine; The molar ratio of the intermediate product to the compound NH2-R-COOH is 1:2.1-2.8; The reaction time of the reaction is 12 to 18 h; The washing is performed with acetone.

4. The preparation method according to claim 3, characterized in that In step (2), the molar ratio of the intermediate product to the compound NH2-R-COOH is 1:2.1~2.

4.

5. The preparation method according to claim 1, characterized in that The diol is selected from at least one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-cyclohexanedimethanol, phenyl glycol, catechol, resorcinol, hydroquinone, 1,3-adamantanediol, and 1,1-cyclopropane dimethanol; The cyclic dicarboxylic acid is selected from at least one of oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, phthalic acid, 5-sodium sulfoisophthalate, 5-sodium sulfoterephthalate, 2,5-furandicarboxylic acid, and 2,6-naphthalene dicarboxylic acid; The acid anhydride is selected from at least one of succinic anhydride, glutaric anhydride, maleic anhydride, adipic anhydride, phthalic anhydride, 1,2-naphthalene dicarboxylic anhydride, 2,3-pyrazine dicarboxylic anhydride and 2,3-pyridinedicarboxylic anhydride; The acid ester is selected from at least one of dimethyl succinate, diethyl succinate, dimethyl fumarate, dimethyl glutarate, dimethyl adipate, dimethyl terephthalate, and dimethyl 2,5-furandicarboxylate; The molar ratio of the diol to the cyclic dicarboxylic acid and / or the corresponding acid anhydride and / or the corresponding acid ester is 1:1.05-2; Based on the sum of the mass of the diol and the cyclic dicarboxylic acid and / or the corresponding acid anhydride and / or the corresponding acid ester being 100%, the total addition amount of the reactive triazine-based organic flame retardant is 1 wt% to 15 wt%.

6. The preparation method according to claim 5, characterized in that The molar ratio of the diol to the cyclic dicarboxylic acid and / or the corresponding acid anhydride and / or the corresponding acid ester is 1:1.05-1.

5.

7. The preparation method according to claim 1, characterized in that The esterification stage is carried out in an inert gas atmosphere; the inert gas is a rare gas and / or nitrogen.

8. The preparation method according to claim 1, characterized in that The esterification reaction temperature in the esterification stage is 160-220° C. and the reaction time is 8-16 hours.

9. The preparation method according to claim 1, characterized in that The reaction temperature in the polycondensation stage is 210-280° C., the reaction pressure is lower than 100 Pa, and the reaction time is 8-24 hours.

10. The preparation method according to claim 9, characterized in that The reaction temperature in the polycondensation stage is 240-280°C.

11. The flame retardant copolyester material prepared according to the preparation method according to any one of claims 1 to 10.

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