A flame-retardant PET material and its preparation method

Abstract

The present invention discloses a flame-retardant PET material and a preparation method thereof, belonging to the technical field of PET materials, and comprising the following raw materials in parts by weight: 50 parts of PET resin, 14-16 parts of flame retardant, 8-12 parts of glass fiber, 0.8-1 part of coupling agent, 2-4 parts of toughening agent, and 0.9-1 part of lubricant; the glass fiber and the coupling agent are put into a high-speed kneader for treatment, and then premixed with the remaining raw materials in a high-speed mixer, and finally melt-extruded and granulated to obtain the PET material. In the present invention, a synthesized flame retardant is added to the PET material. The flame retardant contains Si-N-P synergistic flame-retardant components, and has an efficient and safe flame-retardant effect. Moreover, it belongs to a polyester-type polymer, has higher stability, migration resistance and exudation resistance, and has extremely high compatibility with the PET matrix, and can be uniformly distributed in the PET material; in addition, the addition of the flame retardant can also improve the heat resistance of the PET material.

Description

Technical Field

[0001] The present invention belongs to the technical field of PET materials, and specifically relates to a flame-retardant PET material and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate (PET) is currently one of the most important thermoplastic engineering materials, with excellent wear resistance, heat resistance, corrosion resistance, electrical insulation, etc. PET is widely used in the production of fibers, films, bottled containers, etc.; in recent years, the demand ratio of PET in the fields of automobiles, household appliances, machinery, etc. has also been increasing continuously. Pure PET is extremely easy to burn in the air, and the limiting oxygen index value is only 21%, so it becomes very important to improve the flame retardancy of PET. In the prior art, the method of adding flame retardants is mostly used to improve the flame retardant performance of PET materials.

[0003] The prior art such as the Chinese invention patent with the publication number of CN112300543A discloses a halogen-free flame-retardant PET material. By weight percentage, the raw materials at least include: 7-15% zinc hypophosphite, 4-12% nitrogen-based flame retardant, and polyolefin plastic to make up the balance; among them, zinc hypophosphite and nitrogen-based flame retardant belong to P-based and N-based flame retardant active components respectively. Adding the two into the PET material can improve the flame retardancy of PET to a certain extent. However, due to the poor interfacial compatibility with the PET polymer matrix, they are difficult to be evenly dispersed, and they belong to small molecule flame retardant components, which are easy to exude and migrate in the PET material, and it is difficult to ensure the lasting stability of the flame retardant effect. Therefore, the flame retardant effect of PET materials is still difficult to meet the use requirements. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a flame-retardant PET material and a preparation method thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A flame-retardant PET material, comprising the following raw materials in parts by weight: 50 parts of PET resin, 14-16 parts of flame retardant, 8-12 parts of glass fiber, 0.8-1 part of coupling agent, 2-4 parts of toughening agent, 0.9-1 part of lubricant;

[0007] The preparation method of the PET material comprises the following steps:

[0008] Put the glass fiber and the coupling agent into a high-speed kneader for treatment;

[0009] Add the treated glass fiber, PET resin, flame retardant, toughening agent and lubricant into a high-speed mixer for premixing, and then extrude the mixture by melting, draw it into strips, cool it with water, cut it into pellets and dry it to obtain the PET material.

[0010] Further, the coupling agent is silane coupling agent KH550 or silane coupling agent KH560.

[0011] Further, the toughening agent is one of POE grafted maleic anhydride, POE-g-GMA, and ethylene-methyl acrylate-glycidyl methacrylate.

[0012] Further, the lubricant is selected from PETS or silicone powder.

[0013] Further, the flame retardant is prepared by the following steps:

[0014] S1. Place tetramethyldisiloxane in a three-necked flask, add a platinum catalyst and stir for 20 min. Heat the mixture. After the temperature rises to 50 °C, slowly dropwise add a chloroform solution of allylamine into the system, and continue to react at this temperature for 3 h. After the reaction is completed, filter to remove the catalyst, and rotary evaporate the reaction solution (to remove the solvent and slightly excessive allylamine) to obtain intermediate 1; the molar ratio of tetramethyldisiloxane to allylamine is 1:2.1; the addition amount of the platinum catalyst is 10 μg / g of the total mass of the reaction raw materials (tetramethyldisiloxane and allylamine);

[0015] Under the action of the platinum catalyst, the unsaturated carbon-carbon double bonds on the molecules of tetramethyldisiloxane and allylamine undergo a hydrosilylation reaction. By controlling the molar ratio of the two to be close to 1:2, intermediate 1 is obtained. The reaction process is as follows:

[0016]

[0017] S2. Add intermediate 1, triethylamine, and DMF (N,N-dimethylformamide) to a dry three-necked flask. Place the flask in an ice bath, stir and mix. When the system temperature stabilizes at 0 - 2 °C, slowly dropwise add chloroethanol through a constant pressure dropping funnel with stirring. After the addition is completed, react at 0 - 2 °C for 3 h. Filter to remove the salt, rotary evaporate under reduced pressure to remove most of the DMF, and then perform column chromatography purification using a methanol-chloroform mixed solvent as the eluent (the volume ratio of the two is 9:11). Rotary evaporate the eluent to obtain intermediate 2; the dosage ratio of intermediate 1, triethylamine, and chloroethanol is 12.4 g:10.1 g:8 g;

[0018] The -NH2 on the molecule of intermediate 1 undergoes a nucleophilic substitution reaction with the -Cl on the molecule of chloroethanol to obtain intermediate 2. The process is as follows:

[0019]

[0020] S3. Add dimethyl phosphite, carbon tetrachloride, and tetrahydrofuran into a three-necked flask equipped with a stirring device in sequence. Transfer the flask to an ice bath and stir. While stirring, dropwise add a mixed solution of triethylamine, intermediate 2, and tetrahydrofuran into the flask simultaneously. After the addition is completed, transfer the three-necked flask to room temperature and continue stirring for reaction for 10 h. After the reaction is completed, perform suction filtration, take the filtrate, and conduct vacuum distillation to obtain a glycol derivative. The dosage ratio of dimethyl phosphite, carbon tetrachloride, triethylamine, and intermediate 2 is 11 g:15.4 g:10.1 g:16.8 g;

[0021] The -NH- on intermediate 2 undergoes an Atherton-Todd reaction with dimethyl phosphite, and the reaction process is as shown below to obtain a glycol derivative:

[0022]

[0023] S4. Add terephthalic acid, ethylene glycol, and antimony trioxide into a reaction kettle, react at a temperature of 240 °C and a pressure of 0.35 MPa for 2 h, then add the glycol derivative to the reaction system, and conduct a pre-condensation reaction at 260 °C and a vacuum degree of 1000 Pa for 1 h. Subsequently, raise the temperature to 280 °C and react at a vacuum degree of 100 Pa for 2 h. Finally, discharge the material into a water tank for rapid cooling, and obtain a flame retardant through pelletizing and drying processes. The dosage ratio of terephthalic acid, ethylene glycol, antimony trioxide, and glycol derivative is 100 g:28 - 32 g:0.05 g:38 - 46 g.

[0024] Copolymerize terephthalic acid, ethylene glycol, and the glycol derivative to obtain a polyester-based high molecular flame retardant. Compared with ordinary organic flame retardants, the high molecular type has higher stability, migration resistance, and exudation resistance, and has a long-lasting flame retardant effect. In addition, this high molecular flame retardant belongs to the polyester molecular chain and has extremely high compatibility with the PET matrix. Therefore, it can be evenly distributed in the PET material. It should be noted that the glycol derivative molecule contains a -Si-O-Si- chain segment and a P-N synergistic flame retardant component. When the glycol derivative copolymerizes with terephthalic acid and ethylene glycol, both the -Si-O-Si- chain segment and the P-N synergistic flame retardant component exist in the polyester main chain. Compared with high molecules with active ingredients in the side chain, when the active ingredients are located in the main chain, the stability is higher and the effect is better. The -Si-O-Si- chain segment is a good char-forming and smoke-suppressing agent, and the P-N synergistic flame retardant component has a safe and efficient multi-effect flame retardant mechanism. Therefore, the flame retardant itself has good flame retardant and smoke suppression performance. In addition, the presence of the -Si-O-Si- chain segment in the main chain can also effectively improve the heat resistance of the flame retardant, thereby improving the heat resistance of the PET material.

[0025] Advantages of the present invention:

[0026] In the present invention, a synthesized flame retardant is added to the PET material. The flame retardant contains Si-N-P synergistic flame retardant components, and has an efficient and safe flame retardant effect. It belongs to a polyester-type polymer. Compared with ordinary organic flame retardants, the polymer type has higher stability, migration resistance and exudation resistance, and has a long-lasting flame retardant effect. Moreover, it has extremely high compatibility with the PET matrix. Therefore, it can be evenly distributed in the PET material. In addition, the addition of this flame retardant can also improve the heat resistance of the PET material. Detailed implementation mode

[0027] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0028] Example 1

[0029] Preparation of flame retardant:

[0030] S1. Place 6.7 g of tetramethyldisiloxane in a three-necked flask, add 127 μg of platinum catalyst and stir for 20 min. Heat it. After the temperature rises to 50 °C, slowly drop 30 mL of chloroform solution containing 6 g of allylamine into the system, and continue to react for 3 h at this temperature. After the reaction is completed, filter to remove the catalyst, and rotary evaporate the reaction solution (remove the solvent and slightly excessive allylamine) to obtain intermediate 1.

[0031] S2. Add 12.4 g of intermediate 1, 10.1 g of triethylamine and DMF to a dry three-necked flask. Place the flask in an ice bath and stir to mix. When the temperature of the system stabilizes at 0 °C, slowly drop 8 g of chloroethanol dropwise into it with stirring through a constant pressure dropping funnel. After the dropping is completed, react at 0 °C for 3 h, filter to remove the salt, rotary evaporate under reduced pressure to remove most of the DMF, and then carry out column chromatography purification with a methanol-chloroform mixed solvent as the eluent (the volume ratio of the two is 9:11), and rotary evaporate the eluent to obtain intermediate 2.

[0032] S3. Add 11 g of dimethyl phosphite, 15.4 g of carbon tetrachloride and 50 mL of tetrahydrofuran to a three-necked flask equipped with a stirring device in sequence. Transfer the flask to an ice bath and stir. While dropping 10.1 g of triethylamine, 16.8 g of intermediate 2 and 30 mL of tetrahydrofuran into the flask drop by drop at the same time. After the dropping is completed, transfer the three-necked flask to room temperature and continue to stir and react for 10 h. After the reaction is completed, carry out suction filtration, take the filtrate, and distill under reduced pressure to obtain a glycol derivative.

[0033] S4. Add 100 g of terephthalic acid, 32 g of ethylene glycol, and 0.05 g of antimony trioxide into a reaction kettle, react for 2 h under the conditions of a temperature of 240 °C and a pressure of 0.35 MPa, then add 38 g of glycol derivative into the reaction system, and conduct a pre-condensation reaction for 1 h at 260 °C and a vacuum degree of 1000 Pa. Subsequently, raise the temperature to 280 °C and react for 2 h under the condition of a vacuum degree of 100 Pa. Finally, discharge the product into a water tank for rapid cooling, and obtain the flame retardant through pelletizing and drying processes.

[0034] Example 2

[0035] Preparation of flame retardant:

[0036] S1. Place 6.7 g of tetramethyldisiloxane in a three-necked flask, add 127 μg of platinum catalyst and stir for 20 min. Heat, and after the temperature rises to 50 °C, slowly drop 30 mL of a chloroform solution containing 6 g of allylamine into the system. Continue to react at this temperature for 3 h. After the reaction is completed, filter to remove the catalyst, and rotary evaporate the reaction solution (to remove the solvent and slightly excessive allylamine) to obtain Intermediate 1.

[0037] S2. Add 12.4 g of Intermediate 1, 10.1 g of triethylamine, and DMF into a dry three-necked flask. Place the flask in an ice bath, stir and mix. When the system temperature stabilizes at 2 °C, slowly drop 8 g of chloroethanol dropwise through a constant pressure dropping funnel under stirring. After the dropping is completed, react at 2 °C for 3 h. Filter to remove the salt, rotary evaporate under reduced pressure to remove most of the DMF, and then conduct column chromatography purification using a methanol-chloroform mixed solvent as the eluent (the volume ratio of the two is 9:11). Rotary evaporate the eluent to obtain Intermediate 2.

[0038] S3. Add 11 g of dimethyl phosphite, 15.4 g of carbon tetrachloride, and 50 mL of tetrahydrofuran into a three-necked flask equipped with a stirring device in sequence. Transfer the flask to an ice bath and stir. While dropping 10.1 g of triethylamine, 16.8 g of Intermediate 2, and a mixed solution of 30 mL of tetrahydrofuran dropwise into the flask simultaneously. After the dropping is completed, transfer the three-necked flask to room temperature and continuously stir and react for 10 h. After the reaction is completed, conduct suction filtration, take the filtrate, and distill under reduced pressure to obtain the glycol derivative.

[0039] S4. Add 100 g of terephthalic acid, 28 g of ethylene glycol, and 0.05 g of antimony trioxide into a reaction kettle, react for 2 h under the conditions of a temperature of 240 °C and a pressure of 0.35 MPa, then add 46 g of glycol derivative into the reaction system, and conduct a pre-condensation reaction for 1 h at 260 °C and a vacuum degree of 1000 Pa. Subsequently, raise the temperature to 280 °C and react for 2 h under the condition of a vacuum degree of 100 Pa. Finally, discharge the product into a water tank for rapid cooling, and obtain the flame retardant through pelletizing and drying processes.

[0040] Example 3

[0041] Preparation of flame-retardant PET material:

[0042] Put 80 g of glass fiber and 8 g of silane coupling agent KH550 into a high-speed kneader for treatment;

[0043] Pre-mix the treated glass fiber with 500 g of PET resin, 140 g of the flame retardant prepared in Example 1, 20 g of POE-grafted maleic anhydride, and 9 g of PETS in a high-speed mixer, and then melt-extrude, draw, water-cool, pelletize, and dry the mixture to obtain the PET material.

[0044] Example 4

[0045] Preparation of flame-retardant PET material:

[0046] Put 100 g of glass fiber and 9 g of silane coupling agent KH560 into a high-speed kneader for treatment;

[0047] Pre-mix the treated glass fiber with 500 g of PET resin, 150 g of the flame retardant prepared in Example 1, 30 g of POE-g-GMA, and 9.5 g of silicone powder in a high-speed mixer, and then melt-extrude, draw, water-cool, pelletize, and dry the mixture to obtain the PET material.

[0048] Example 5

[0049] Preparation of flame-retardant PET material:

[0050] Put 120 g of glass fiber and 10 g of silane coupling agent KH550 into a high-speed kneader for treatment;

[0051] Pre-mix the treated glass fiber with 500 g of PET resin, 160 g of the flame retardant prepared in Example 2, 40 g of ethylene-methyl acrylate-glycidyl methacrylate, and 10 g of PETS in a high-speed mixer, and then melt-extrude, draw, water-cool, pelletize, and dry the mixture to obtain the PET material.

[0052] Comparative example

[0053] The PET material obtained by replacing the flame retardant in Example 3 with an equal mass of DOPO flame retardant, with the remaining raw materials and preparation process unchanged.

[0054] Process and cut the PET materials obtained in Examples 3-5 and the comparative example into test samples, and conduct the following performance tests:

[0055] Tensile strength: Test according to the standard of ASTM D638-03;

[0056] Oxygen index LOI value: Tested according to the standard of GB / T 2406.2-2009;

[0057] UL-94 vertical burning: Tested according to the standard of GB / T 2408-2008;

[0058] Maximum smoke density Dmax: Tested according to the standard of GB / T 8323.2-2008;

[0059] Resistance to migration and exudation: The film samples made of PET materials are divided into nine groups, with 10 film pieces of 10 cm * 10 cm in each group. They are placed in an incubator at 100 °C for 100 h. After maintaining a constant temperature of 100 h, observe the surface of each group of film pieces to see if it becomes mottled, judge whether there is an additive migrating to the surface of the film pieces, and evaluate the anti-migration property of the film pieces. If 0-1 film piece becomes mottled, the anti-migration property is excellent; if 2-5 film pieces become mottled, the anti-migration property is good; if 5-10 film pieces become mottled, the anti-migration property is poor;

[0060] The measured results are shown in the following table:

[0061] Example 3 Example 4 Example 5 Comparative Example Tensile strength / MPa 29.8 30.4 31.5 26.8 LOI / % 31.7 32.1 32.7 29.2 UL94 / rating V-0 V-0 V-0 V-1 Dmax 375.9 373.2 370.6 422.5 Anti-migration property Excellent Excellent Excellent Good

[0062] It can be seen from the data in the above table that the PET material obtained by the present invention has excellent flame retardant and smoke suppression properties; combined with the data of the comparative examples, it can be known that the addition of the flame retardant in the present invention can significantly improve the flame retardant and smoke suppression properties of the PET material and improve the migration resistance of the flame retardant components.

[0063] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0064] The above content is only an example and explanation of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A flame-retardant PET material, characterized in that, It includes the following raw materials in parts by weight: 50 parts of PET resin, 14 - 16 parts of flame retardant, 8 - 12 parts of glass fiber, 0.8 - 1 part of coupling agent, 2 - 4 parts of toughening agent, and 0.9 - 1 part of lubricant; Among them, the flame retardant is prepared through the following steps: S1. Place tetramethyldisiloxane in a three - necked flask, add a platinum catalyst and stir for 20 min, then heat. After the temperature rises to 50 °C, slowly drop the chloroform solution of allylamine into the system, and continue to react at this temperature for 3 h. After the reaction ends, filter to remove the catalyst, and rotary evaporate the reaction solution to obtain intermediate 1; the molar ratio of tetramethyldisiloxane to allylamine is 1:2.1; the addition amount of the platinum catalyst is 10 μg / g of the total mass of tetramethyldisiloxane and allylamine; S2. Add intermediate 1, triethylamine, and DMF to a dry three - necked flask, place the flask in an ice bath, stir and mix. When the system temperature stabilizes at 0 - 2 °C, slowly drop chloroethanol through a constant - pressure dropping funnel under stirring. After the dropping is completed, react at 0 - 2 °C for 3 h, filter to remove salts, rotary evaporate under reduced pressure to remove most of the DMF, and then perform column chromatography purification, rotary evaporate the eluent to obtain intermediate 2; the dosage ratio of intermediate 1, triethylamine, and chloroethanol is 12.4 g:10.1 g:8 g; S3. Add dimethyl phosphite, carbon tetrachloride, and tetrahydrofuran to a three - necked flask in sequence, transfer the flask to an ice bath and stir. While simultaneously dropping a mixture of triethylamine, intermediate 2, and tetrahydrofuran dropwise into the flask, after the dropping ends, transfer the three - necked flask to room temperature and continue to stir and react for 10 h. After the reaction ends, perform suction filtration, take the filtrate, and distill under reduced pressure to obtain a diol derivative; the dosage ratio of dimethyl phosphite, carbon tetrachloride, triethylamine, and intermediate 2 is 11 g:15.4 g:10.1 g:16.8 g; S4. Add terephthalic acid, ethylene glycol, and antimony trioxide to a reaction kettle, react at a temperature of 240 °C and a pressure of 0.35 MPa for 2 h, then add the diol derivative to the reaction system, and perform a pre - condensation reaction at 260 °C and a vacuum degree of 1000 Pa for 1 h. Subsequently, raise the temperature to 280 °C and react at a vacuum degree of 100 Pa for 2 h. Finally, discharge the material into a water tank for rapid cooling, and obtain the flame retardant through pelletizing and drying processes; the dosage ratio of terephthalic acid, ethylene glycol, antimony trioxide, and the diol derivative is 100 g:28 - 32 g:0.05 g:38 - 46 g.

2. A flame-retardant PET material according to claim 1, characterized in that, The coupling agent is silane coupling agent KH550 or silane coupling agent KH560.

3. A flame-retardant PET material according to claim 1, wherein, The toughening agent is one of POE grafted maleic anhydride, POE - g - GMA, and ethylene - methyl acrylate - glycidyl methacrylate.

4. The preparation method of a flame-retardant PET material according to claim 1, wherein, It includes the following steps: Put the glass fiber and the coupling agent into a high - speed kneader for treatment; Pre - mix the treated glass fiber with PET resin, flame retardant, toughening agent, and lubricant in a high - speed mixer, and then melt - extrude, draw into strips, cool with water, pelletize, and dry the mixture to obtain the PET material.

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